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Sample records for nanophase ferric oxide

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-07-01

    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

  3. 21 CFR 186.1300 - Ferric oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Substances Affirmed as GRAS § 186.1300 Ferric oxide. (a) Ferric oxide (iron (III) oxide, Fe2O3, CAS Reg. No... iron hydroxide oxide. The product is red-brown to black trigonal crystals. (b) In accordance with § 186... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ferric oxide. 186.1300 Section 186.1300 Food...

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  6. 21 CFR 186.1300 - Ferric oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ferric oxide. 186.1300 Section 186.1300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT FOOD... as the mineral hematite. It may be prepared synthetically by heating brown iron hydroxide oxide....

  7. 21 CFR 186.1300 - Ferric oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ferric oxide. 186.1300 Section 186.1300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of...

  8. 21 CFR 186.1300 - Ferric oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ferric oxide. 186.1300 Section 186.1300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of...

  9. 21 CFR 186.1300 - Ferric oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ferric oxide. 186.1300 Section 186.1300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of...

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

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

    PubMed

    Morris, R V; Golden, D C; Bell JF 3rd; Lauer, H V; Adams, J B

    1993-10-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    PubMed Central

    Birkner, Nancy; Navrotsky, Alexandra

    2014-01-01

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

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

    PubMed

    Birkner, Nancy; Navrotsky, Alexandra

    2014-04-29

    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.

  16. High pressure structural studies on nanophase praseodymium oxide

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    SciTech Connect

    Garaje, Sunil N.; Apte, Sanjay K.; Kumar, Ganpathy; Panmand, Rajendra P.; Naik, Sonali D.; Mahajan, Satish M.; Chand, Ramesh; Kale, Bharat B.

    2013-02-15

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2013-09-10

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

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

    PubMed

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

    2013-09-10

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

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

    USGS Publications Warehouse

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

    2013-01-01

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

  2. Granulation and ferric oxides loading enable biochar derived from cotton stalk to remove phosphate from water.

    PubMed

    Ren, Jing; Li, Nan; Li, Lei; An, Jing-Kun; Zhao, Lin; Ren, Nan-Qi

    2015-02-01

    Granulation of biochar powder followed by immobilization of ferric oxides on the macroporous granular biochar (Bg-FO-1) substantially enhanced phosphate removal from water. BET analysis confirmed that both granulation and ferric oxides loading can increase the surface areas and pore volumes effectively. Bg-FO-1 was proven to be a favorable adsorbent for phosphate. The phosphate adsorption capacity was substantially increased from 0 mg/g of raw biochar powder to 0.963 mg/g (Bg-FO-1). When the ferric oxides loading was prior to granulation, the adsorption capacity was decreased by 59-0.399 mg/g, possibly due to the decrease of micropore and mesopore area as well as the overlaying of binders to the activated sites produced by ferric oxides.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  5. 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...

  6. A turn-on fluorescent probe based on hydroxylamine oxidation for detecting ferric ion selectively in living cells.

    PubMed

    Wang, Rui; Yu, Fabiao; Liu, Ping; Chen, Lingxin

    2012-05-28

    We have described a turn on fluorescent probe BOD-NHOH based on hydroxylamine oxidation for detecting intracellular ferric ions. The probe comprises a signal transducer of BODIPY dye and a Fe(3+)-response modulator of hydroxylamine. It is readily employed for assessing intracellular ferric ion levels, and confocal imaging is achieved successfully.

  7. The biostimulation of anaerobic digestion with (semi)conductive ferric oxides: their potential for enhanced biomethanation.

    PubMed

    Baek, Gahyun; Kim, Jaai; Cho, Kyungjin; Bae, Hyokwan; Lee, Changsoo

    2015-12-01

    The effect of biostimulation with ferric oxides, semiconductive ferric oxyhydroxide, and conductive magnetite on the anaerobic digestion of dairy wastewater was examined in a batch mode. The reactors supplemented with ferric oxyhydroxide (R2) and magnetite (R3) showed significantly enhanced biomethanation performance compared with the control (R1). The removal of chemical oxygen demand (COD) after 30 days was 31.9, 59.3, and 82.5% in R1, R2, and R3, respectively. The consumed COD was almost fully recovered as biogas in R2 and R3, while only 79% was recovered in R1. The total energy production as biogas was accordingly 32.2, 71.0, and 97.7 kJ in R1, R2, and R3, respectively. The reactors also differed in the acid formation profile with more propionate and butyrate found in R1 and more acetate found in R3. The enhanced biomethanation seems to be associated with variations in the bacterial community structure supposedly induced by the ferric oxides added. In contrast, no evident variation was observed in the archaeal community structure among the reactors. The potential electric syntrophy formed between Methanosaeta concilii-like methanogens and electroactive iron-reducing bacteria, particularly Trichococcus, was likely responsible for the enhanced performance. The stimulated growth of fermentative iron reducers may also have contributed by altering the metabolic characteristics of the bacterial communities to produce more favorable acidogenic products for methanogenesis. The overall results suggest the potential of biostimulation with (semi)conductive ferric oxides to enhance the rate and efficiency of the biomethanation of organic wastes. This seems to be potentially attractive, as increasing attention is being paid to the energy self-sufficiency of waste/wastewater treatment processes today. PMID:26272096

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

    PubMed

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

    2013-05-28

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

    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.

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

    PubMed

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

    2008-04-01

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

  12. Carcinogenic and cocarcinogenic effects of inhaled synthetic smog and ferric oxide particles.

    PubMed

    Nettesheim, P; Creasia, D A; Mitchell, T J

    1975-07-01

    The carcinogenic and cocarcinogenic activity of synthetic smog, ferric oxide (Fe2O3) dust, and a mixture of the two air contaminants was determined in a long-term inhalation study with Syrian hamsters. Inhaled Fe2O3 particles definitely enhanced diethylnitrosamine tumorigenicity in the peripheral lung. Synthetic smog did not. When tested at a concentration of 40 ppm methane equivalents or 40 mg/m3, respectively, neither air pollutant by itself appeared carcinogenic. Fe2O3 caused pulmonary fibrosis and synthetic smog caused alveolar bronchiolization in many of the exposed animals.

  13. Sorption of ferric iron from ferrioxamine B to synthetic and biogenic layer type manganese oxides

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

    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.

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

    PubMed

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

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.

    1992-01-01

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

  16. 21 CFR 184.1307 - Ferric sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ....1307 Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2(SO4)3 CAS Reg. No. 10028-22-5) is a yellow substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide...

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

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-02-01

    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

  19. Are there multiple mechanisms of anaerobic sulfur oxidation with ferric iron in Acidithiobacillus ferrooxidans?

    PubMed

    Kucera, Jiri; Pakostova, Eva; Lochman, Jan; Janiczek, Oldrich; Mandl, Martin

    2016-06-01

    To clarify the pathway of anaerobic sulfur oxidation coupled with dissimilatory ferric iron reduction in Acidithiobacillus ferrooxidans strain CCM 4253 cells, we monitored their energy metabolism gene transcript profiles. Several genes encoding electron transporters involved in aerobic iron and sulfur respiration were induced during anaerobic growth of ferrous iron-grown cells. Most sulfur metabolism genes were either expressed at the basal level or their expression declined. However, transcript levels of genes assumed to be responsible for processing of elemental sulfur and other sulfur intermediates were elevated at the beginning of the growth period. In contrast, genes with predicted functions in formation of hydrogen sulfide and sulfate were significantly repressed. The main proposed mechanism involves: outer membrane protein Cyc2 (assumed to function as a terminal ferric iron reductase); periplasmic electron shuttle rusticyanin; c4-type cytochrome CycA1; the inner membrane cytochrome bc1 complex I; and the quinone pool providing connection to the sulfur metabolism machinery, consisting of heterodisulfide reductase, thiosulfate:quinone oxidoreductase and tetrathionate hydrolase. However, an alternative mechanism seems to involve a high potential iron-sulfur protein Hip, c4-type cytochrome CycA2 and inner membrane cytochrome bc1 complex II. Our results conflict with findings regarding the type strain, indicating strain- or phenotype-dependent pathway variation.

  20. Are there multiple mechanisms of anaerobic sulfur oxidation with ferric iron in Acidithiobacillus ferrooxidans?

    PubMed

    Kucera, Jiri; Pakostova, Eva; Lochman, Jan; Janiczek, Oldrich; Mandl, Martin

    2016-06-01

    To clarify the pathway of anaerobic sulfur oxidation coupled with dissimilatory ferric iron reduction in Acidithiobacillus ferrooxidans strain CCM 4253 cells, we monitored their energy metabolism gene transcript profiles. Several genes encoding electron transporters involved in aerobic iron and sulfur respiration were induced during anaerobic growth of ferrous iron-grown cells. Most sulfur metabolism genes were either expressed at the basal level or their expression declined. However, transcript levels of genes assumed to be responsible for processing of elemental sulfur and other sulfur intermediates were elevated at the beginning of the growth period. In contrast, genes with predicted functions in formation of hydrogen sulfide and sulfate were significantly repressed. The main proposed mechanism involves: outer membrane protein Cyc2 (assumed to function as a terminal ferric iron reductase); periplasmic electron shuttle rusticyanin; c4-type cytochrome CycA1; the inner membrane cytochrome bc1 complex I; and the quinone pool providing connection to the sulfur metabolism machinery, consisting of heterodisulfide reductase, thiosulfate:quinone oxidoreductase and tetrathionate hydrolase. However, an alternative mechanism seems to involve a high potential iron-sulfur protein Hip, c4-type cytochrome CycA2 and inner membrane cytochrome bc1 complex II. Our results conflict with findings regarding the type strain, indicating strain- or phenotype-dependent pathway variation. PMID:26924114

  1. Enhanced dark hydrogen fermentation by addition of ferric oxide nanoparticles using Enterobacter aerogenes.

    PubMed

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Liu, Min; Zhou, Junhu; Cen, Kefa

    2016-05-01

    Ferric oxide nanoparticles (FONPs) were used to facilitate dark hydrogen fermentation using Enterobacter aerogenes. The hydrogen yield of glucose increased from 164.5±2.29 to 192.4±1.14mL/g when FONPs concentration increased from 0 to 200mg/L. SEM images of E. aerogenes demonstrated the existence of bacterial nanowire among cells, suggesting FONPs served as electron conduits to enhance electron transfer. TEM showed cellular internalization of FONPs, indicating hydrogenase synthesis and activity was potentially promoted due to the released iron element. When further increasing FONPs concentration to 400mg/L, the hydrogen yield of glucose decreased to 147.2±2.54mL/g. Soluble metabolic products revealed FONPs enhanced acetate pathway of hydrogen production, but weakened ethanol pathway. This shift of metabolic pathways allowed more nicotinamide adenine dinucleotide for reducing proton to hydrogen.

  2. Enhanced dark hydrogen fermentation by addition of ferric oxide nanoparticles using Enterobacter aerogenes.

    PubMed

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Liu, Min; Zhou, Junhu; Cen, Kefa

    2016-05-01

    Ferric oxide nanoparticles (FONPs) were used to facilitate dark hydrogen fermentation using Enterobacter aerogenes. The hydrogen yield of glucose increased from 164.5±2.29 to 192.4±1.14mL/g when FONPs concentration increased from 0 to 200mg/L. SEM images of E. aerogenes demonstrated the existence of bacterial nanowire among cells, suggesting FONPs served as electron conduits to enhance electron transfer. TEM showed cellular internalization of FONPs, indicating hydrogenase synthesis and activity was potentially promoted due to the released iron element. When further increasing FONPs concentration to 400mg/L, the hydrogen yield of glucose decreased to 147.2±2.54mL/g. Soluble metabolic products revealed FONPs enhanced acetate pathway of hydrogen production, but weakened ethanol pathway. This shift of metabolic pathways allowed more nicotinamide adenine dinucleotide for reducing proton to hydrogen. PMID:26890796

  3. Protective effect of butylated hydroxytoluene on ferric nitrilotriacetate induced hepatotoxicity and oxidative stress in mice.

    PubMed

    Ansar, S; Tabassum, H; Al Jameil, N

    2013-05-01

    The present study was undertaken to evaluate the possible ameliorating effect of butylated hydroxyl toluene (BHT), associated with ferric nitrilotriacetate (Fe-NTA)-induced oxidative stress and liver injury in mice. The treatment of mice with Fe-NTA alone enhances ornithine decarboxylase activity to 4.6 folds, protein carbonyl formation increased up to 2.9 folds and DNA synthesis expressed in terms of [(3)H] thymidine incorporation increased to 3.2 folds, and antioxidants and antioxidant enzymes decreased to 1.8-2.5 folds, compared with the corresponding saline-treated controls. These changes were reversed significantly (p < 0.001) in animals receiving a pretreatment of BHT. Our data show that BHT can reciprocate the toxic effects of Fe-NTA and can serve as a potent chemopreventive agent.

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

    PubMed

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

    2008-05-01

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

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

    SciTech Connect

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

    2001-04-01

    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.

  6. Effects of nitrogen oxides, sulfur dioxide, and ferric ions on the corrosion of mild steel in concentrated sulfuric acid

    NASA Astrophysics Data System (ADS)

    Andersen, Terrell N.; Vanorden, Naola; Schlitt, W. Joseph

    1980-08-01

    Effects of nitrate ions, nitrous acid, sulfur dioxide, and ferric ions on the corrosion of mild steel in unstirred, concentrated sulfuric acid were determined in laboratory tests. Nitrate and nitrous acid at levels up to 1000 ppm accelerate corrosion. At concentrations greater than 1000 ppm nitrate passivates the steel. Sulfur dioxide and ferric ions have no detectable influence on the corrosion. Reaction mechanisms are presented to explain the observed effects. The impact of nitrogen oxides on the storage and handling of sulfide smelter by-product acid is discussed.

  7. The oxidation state of nanophase Fe particles in lunar soil: Implications for space weathering

    NASA Astrophysics Data System (ADS)

    Thompson, Michelle S.; Zega, Thomas J.; Becerra, Patricio; Keane, James T.; Byrne, Shane

    2016-06-01

    We report measurements of the oxidation state of Fe nanoparticles within lunar soils that experienced varied degrees of space weathering. We measured >100 particles from immature, submature, and mature lunar samples using electron energy-loss spectroscopy (EELS) coupled to an aberration-corrected transmission electron microscope. The EELS measurements show that the nanoparticles are composed of a mixture of Fe0, Fe2+, and Fe3+ oxidation states, and exhibit a trend of increasing oxidation state with higher maturity. We hypothesize that the oxidation is driven by the diffusion of O atoms to the surface of the Fe nanoparticles from the oxygen-rich matrix that surrounds them. The oxidation state of Fe in the nanoparticles has an effect on modeled reflectance properties of lunar soil. These results are relevant to remote sensing data for the Moon and to the remote determination of relative soil maturities for various regions of the lunar surface.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

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

    PubMed

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

    2013-04-10

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

  10. 21 CFR 184.1307 - Ferric sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Substances Affirmed as GRAS § 184.1307 Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2(SO4)3 CAS Reg. No. 10028-22-5) is a yellow substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The ingredient must be of a...

  11. 21 CFR 184.1307 - Ferric sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Substances Affirmed as GRAS § 184.1307 Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2(SO4)3 CAS Reg. No. 10028-22-5) is a yellow substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The ingredient must be of a...

  12. 21 CFR 184.1307 - Ferric sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Substances Affirmed as GRAS § 184.1307 Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2(SO4)3 CAS Reg. No. 10028-22-5) is a yellow substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The ingredient must be of a...

  13. 21 CFR 184.1307 - Ferric sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Substances Affirmed as GRAS § 184.1307 Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2(SO4)3 CAS Reg. No. 10028-22-5) is a yellow substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The ingredient must be of a...

  14. The Campylobacter jejuni Ferric Uptake Regulator Promotes Acid Survival and Cross-Protection against Oxidative Stress

    PubMed Central

    Askoura, Momen; Sarvan, Sabina; Couture, Jean-François

    2016-01-01

    Campylobacter jejuni is a prevalent cause of bacterial gastroenteritis in humans worldwide. The mechanisms by which C. jejuni survives stomach acidity remain undefined. In the present study, we demonstrated that the C. jejuni ferric uptake regulator (Fur) plays an important role in C. jejuni acid survival and acid-induced cross-protection against oxidative stress. A C. jejuni Δfur mutant was more sensitive to acid than the wild-type strain. Profiling of the acid stimulon of the C. jejuni Δfur mutant allowed us to uncover Fur-regulated genes under acidic conditions. In particular, Fur was found to upregulate genes involved in flagellar and cell envelope biogenesis upon acid stress, and mutants with deletions of these genes were found to be defective in surviving acid stress. Interestingly, prior acid exposure of C. jejuni cross-protected against oxidative stress in a catalase (KatA)- and Fur-dependent manner. Western blotting and reverse transcription-quantitative PCR revealed increased expression of KatA upon acid stress. Electrophoretic mobility shift assays (EMSAs) demonstrated that the binding affinity between Fur and the katA promoter is reduced in vitro under conditions of low pH, rationalizing the higher levels of expression of katA under acidic conditions. Strikingly, the Δfur mutant exhibited reduced virulence in both human epithelial cells and the Galleria mellonella infection model. Altogether, this is the first study showing that, in addition to its role in iron metabolism, Fur is an important regulator of C. jejuni acid responses and this function cross-protects against oxidative stress. Moreover, our results clearly demonstrate Fur's important role in C. jejuni pathogenesis. PMID:26883589

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

    NASA Astrophysics Data System (ADS)

    Peak, Derek; Luther, George W.; Sparks, Donald L.

    2003-07-01

    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 hydrous ferric oxide (HFO). On the HFO surface, boric acid adsorbs via both physical adsorption (outer-sphere) and ligand exchange (inner-sphere) reactions. Both trigonal (boric acid) and tetrahedral (borate) boron are complexed on the HFO surface, and a mechanism where trigonal boric acid in solution reacts to form either trigonal or tetrahedral surface complexes is proposed based upon the spectroscopic results. The presence of outer-sphere boric acid complexes can be explained based on the Lewis acidity of the B metal center, and this complex has important implications for boron transport and availability. Outer-sphere boric acid is more likely to leach downward in soils in response to water flow. Outer-sphere boron would also be expected to be more available for plant uptake than more strongly bound boron complexes, and may more readily return to the soil solution when solution concentrations decrease.

  16. The effect of solids residence time on phosphorus adsorption to hydrous ferric oxide floc.

    PubMed

    Conidi, Daniela; Parker, Wayne J

    2015-11-01

    The impact of solids residence time (SRT) on phosphate adsorption to hydrous ferric oxide (HFO) floc when striving for ultra-low P concentrations was characterized and an equilibrium model that describes the adsorption of P onto HFO floc of different ages was developed. The results showed that fresh HFO had a higher adsorption capacity in comparison to aged (2.8, 7.4, 10.8 and 22.8 days) HFO and contributed substantially to P removal at steady state. P adsorption onto HFO solids was determined to be best described by the Freundlich isotherm. P desorption from HFO solids was negligible supporting the hypothesis that chemisorption is the mechanism of P adsorption on HFO solids. A model that included the contribution of different classes of HFO solids (i.e. High, Low or Old, containing high concentration, low concentration or no active surface sites, respectively) to adsorption onto HFO from a sequencing batch reactor (SBR) system was found to adequately describe P adsorption onto HFO solids of different ages. From the model it was determined that the fractions of High and Low HFO decreased with SRT while the fraction of Old HFO increased with SRT. The transformation of High HFO to Low HFO did not limit the overall production of Old HFO and the fresh HFO solids contributed more to P removal at steady state than the aged solids.

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

    NASA Astrophysics Data System (ADS)

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

    2006-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

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

    PubMed

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

    2006-07-01

    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. PMID:16458577

  20. Effect of saccharated ferric oxide and iron dextran on the metabolism of phosphorus in rats.

    PubMed

    Sanai, Toru; Oochi, Nobuaki; Okada, Mitsuo; Imamura, Kenzaburo; Okuda, Seiya; Iida, Mitsuo

    2005-07-01

    As a means of investigating the physiologic damage to and histologic deterioration of the kidney caused by saccharated ferric oxide (SFO) and iron dextran (ID), we administered these substances intraperitoneally to rats. The rats were divided into 3 groups. Group 1 rats ( n = 7) were given SFO, 28 mg/kg for 9 days and 20 mg/kg for 19 days. Group 2 rats ( n = 5) were given ID, 28 mg/kg for 9 days and 20 mg/kg for 19 days. Group 3 rats (control, n = 9) were given normal saline solution. After 28 days, serum calcium, total protein, and albumin concentrations were significantly lower in the SFO group than in the ID group. Serum phosphorus concentrations were significantly lower in the SFO group than in the control group. Serum iron concentrations were significantly higher in the ID group than in the SFO group or the control, and the fractional excretion of sodium was significantly lower in the ID group than in the control group. The percent tubular reabsorption of phosphorus was significantly greater in the ID group than in the SFO group or the control group, and the theoretical threshold concentration of phosphorus was also significantly lower in the SFO group than in the ID or the control group. Histologic examination of the kidney after treatment revealed neither iron in the tubules nor any structural damage to the tubules. ID was not found to induce hypophosphatemia, whereas SFO did. We believe that the cause of such hypophosphatemia is impaired tubular reabsorption.

  1. Study on sulfadimethoxine removal from aqueous solutions by hydrous ferric oxides.

    PubMed

    Zhu, Weixiao; Wang, Jianduo; Wang, Yili; Wang, Hongjie

    2016-01-01

    Significant concerns have been raised over the presence of antibiotics including sulfadimethoxine (SDMO) in aquatic environments. This study investigated the removal capability and mechanism involved in the removal of SDMO by hydrous ferric oxides (HFO). Results showed that SDMO removal was highly pH and ionic strength dependent. The pseudo-first-order model fitted well the kinetic results, and the value of the calculated activation energy for SDMO adsorption onto HFO was 8.6 kJ mol(-1). Adsorption isotherms at varied temperatures were well described by the Langmuir model. Thermodynamic parameters (change in enthalpy > 0, change in entropy > 0, and change in Gibbs free energy < 0) calculated from the temperature-dependent sorption data revealed spontaneous and endothermic process. The exchange of the surface hydroxyl groups of HFO and the negative anions of SDMO(-) and the electrostatic interaction between the positively charged surface of HFO and the deprotonated imino (-N(-)-) accounted for the uptake of SDMO by HFO. PMID:27642833

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

    PubMed

    Fernández; Sánchez-López; Caballero; Martin; Vacher; Ponsonnet

    1998-08-01

    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.

  3. Free gp70 from FeLV: enrichment from cell culture fluid by ferric oxide-agarose chromatography.

    PubMed

    Zelikman, I; Akerblom, L; Hjertèn, S; Morein, B

    1989-04-01

    A new chromatographic material based on beads of macroporous crosslinked agarose containing ferric oxide particles was used for enrichment of gp70--the envelope glycoprotein of feline leukemia virus (FeLV). Free gp70 was purified from cell culture fluid in one step with a recovery of 50 to 60% and a purification of about 60 times. The described procedure is a suitable first step for the purification of gp70 from large volumes of cell culture fluid.

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

    SciTech Connect

    Holmes, P.R.; Crundwell, F.K.

    2000-01-01

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

  5. Evidence of Nitrogen Loss from Anaerobic Ammonium Oxidation Coupled with Ferric Iron Reduction in an Intertidal Wetland.

    PubMed

    Li, Xiaofei; Hou, Lijun; Liu, Min; Zheng, Yanling; Yin, Guoyu; Lin, Xianbiao; Cheng, Lv; Li, Ye; Hu, Xiaoting

    2015-10-01

    Anaerobic ammonium oxidation coupled with nitrite reduction is an important microbial pathway of nitrogen removal in intertidal wetlands. However, little is known about the role of anaerobic ammonium oxidation coupled with ferric iron reduction (termed Feammox) in intertidal nitrogen cycling. In this study, sediment slurry incubation experiments were combined with an isotope-tracing technique to examine the dynamics of Feammox and its association with tidal fluctuations in the intertidal wetland of the Yangtze Estuary. Feammox was detected in the intertidal wetland sediments, with potential rates of 0.24-0.36 mg N kg(-1) d(-1). The Feammox rates in the sediments were generally higher during spring tides than during neap tides. The tidal fluctuations affected the growth of iron-reducing bacteria and reduction of ferric iron, which mediated Feammox activity and the associated nitrogen loss from intertidal wetlands to the atmosphere. An estimated loss of 11.5-18 t N km(-2) year(-1) was linked to Feammox, accounting for approximately 3.1-4.9% of the total external inorganic nitrogen transported into the Yangtze Estuary wetland each year. Overall, the co-occurrence of ferric iron reduction and ammonium oxidation suggests that Feammox can act as an ammonium removal mechanism in intertidal wetlands.

  6. Evidence of Nitrogen Loss from Anaerobic Ammonium Oxidation Coupled with Ferric Iron Reduction in an Intertidal Wetland.

    PubMed

    Li, Xiaofei; Hou, Lijun; Liu, Min; Zheng, Yanling; Yin, Guoyu; Lin, Xianbiao; Cheng, Lv; Li, Ye; Hu, Xiaoting

    2015-10-01

    Anaerobic ammonium oxidation coupled with nitrite reduction is an important microbial pathway of nitrogen removal in intertidal wetlands. However, little is known about the role of anaerobic ammonium oxidation coupled with ferric iron reduction (termed Feammox) in intertidal nitrogen cycling. In this study, sediment slurry incubation experiments were combined with an isotope-tracing technique to examine the dynamics of Feammox and its association with tidal fluctuations in the intertidal wetland of the Yangtze Estuary. Feammox was detected in the intertidal wetland sediments, with potential rates of 0.24-0.36 mg N kg(-1) d(-1). The Feammox rates in the sediments were generally higher during spring tides than during neap tides. The tidal fluctuations affected the growth of iron-reducing bacteria and reduction of ferric iron, which mediated Feammox activity and the associated nitrogen loss from intertidal wetlands to the atmosphere. An estimated loss of 11.5-18 t N km(-2) year(-1) was linked to Feammox, accounting for approximately 3.1-4.9% of the total external inorganic nitrogen transported into the Yangtze Estuary wetland each year. Overall, the co-occurrence of ferric iron reduction and ammonium oxidation suggests that Feammox can act as an ammonium removal mechanism in intertidal wetlands. PMID:26360245

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

    NASA Astrophysics Data System (ADS)

    Tommaseo, C. E.; Kersten, M.

    2002-12-01

    X-ray absorption spectroscopy (EXAFS) was used to determine the near range order of three elements (Fe, As, Si) on the surface of hydrous ferric oxide (HFO) from thermal water scales. Fe K-edge EXAFS analyses of the 2nd shell show a better fit including Si as backscattering neighbor. Validation of the Si-Fe bond was obtained by Si K-edge EXAFS spectra, where the light absorber element is surrounded favourably by much heavier second-shell elements. Least-squares fitting of the second-shell Fourier-filtered EXAFS spectrum in the k-range of 5-11 Å-1 yields in a Si-Fe distance of 3.10-3.13Å, and a Si-Si distance of 3.00Å. Both these interatomic distances and the coordination number N = 2 obtained for the Si-Fe shell are consistent with the formation of a corner-bridging bidentate binuclear (2C) surface complex on the HFO surface. The Si-Si bonds and existance of a vibrational band at 964 cm-1 in the infrared spectrum indicate polymerisation of the silicate on the HFO surface (Tommaseo and Kersten). As K-edge XANES analyses showed the As present in form of arsenate scavenged by the HFO phase. As and Si K-edge EXAFS analyses revealed both elements to compete for 2C surface complexation sites. A mean As-Fe distance of 3.03Å indicate an approx. equal distribution of arsenate between 2C (3.24Å) and another 1E (bidentate mononuclear surface complexation) sites (2.84Å). The average Fe-(O,OH) bond length of 2.09Å is compatible with a high proportion of distorted surficial FeIII(O,OH)6 octahedra in the colloidal HFO precipitates of the scale deposits. The slight distortion of the FeIII(O,OH)6 octahedra is consistent with the apparent strong binding of the 1E arsenate surface complexes (Manceau, 1995). The adverse effect of silicate would therefore be overpredicted without surface complexation models constructed to account for both surface functional groups. The Si K-edge EXAFS data provide also a basis for explaining at the molecular level the poisoning of HFO particle

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

    USGS Publications Warehouse

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

    2004-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1998-10-01

    Dissimilatory iron-reducing bacteria (DIRB) couple the oxidation of organic matter or H 2 to the reduction of iron oxides. The factors controlling the rate and extent of these reduction reactions and the resulting solid phases are complex and poorly understood. Batch experiments were conducted with amorphous hydrous ferric oxide (HFO) and the DIRB Shewanella putrefaciens, strain CN32, in well-defined aqueous solutions to investigate the reduction of HFO and formation of biogenic Fe(II) minerals. Lactate-HFO solutions buffered with either bicarbonate or 1,4-piperazinediethanesulfonic acid (PIPES) containing various combinations of phosphate and anthraquinone-2,6-disulfonate (AQDS), were inoculated with S. putrefaciens CN32. AQDS, a humic acid analog that can be reduced to dihydroanthraquinone by CN32, was included because of its ability to function as an electron shuttle during microbial iron reduction and as an indicator of pe. Iron reduction was measured with time, and the resulting solids were analyzed by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED). In HCO 3- buffered medium with AQDS, HFO was rapidly and extensively reduced, and the resulting solids were dominated by ferrous carbonate (siderite). Ferrous phosphate (vivianite) was also present in HCO 3- medium containing P, and fine-grained magnetite was present as a minor phase in HCO 3- medium with or without P. In the PIPES-buffered medium, the rate and extent of reduction was strongly influenced by AQDS and P. With AQDS, HFO was rapidly converted to highly crystalline magnetite whereas in its absence, magnetite mineralization was slower and the final material less crystalline. In PIPES with both P and AQDS, a green rust type compound [Fe (6-x)IIFe xIII(OH) 12] x+[(A 2-) x/2 · yH 2O] x- was the dominant solid phase formed; in the absence of AQDS a poorly

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

    PubMed Central

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

    2008-01-01

    Background The application of surface complexation models (SCMs) to natural sediments and soils is hindered by a lack of consistent models and data for large suites of metals and minerals of interest. Furthermore, the surface complexation approach has mostly been developed and tested for single solid systems. Few studies have extended the SCM approach to systems containing multiple solids. Results Cu adsorption was measured on pure hydrous ferric oxide (HFO), pure kaolinite (from two sources) and in systems containing mixtures of HFO and kaolinite over a wide range of pH, ionic strength, sorbate/sorbent ratios and, for the mixed solid systems, using a range of kaolinite/HFO ratios. Cu adsorption data measured for the HFO and kaolinite systems was used to derive diffuse layer surface complexation models (DLMs) describing Cu adsorption. Cu adsorption on HFO is reasonably well described using a 1-site or 2-site DLM. Adsorption of Cu on kaolinite could be described using a simple 1-site DLM with formation of a monodentate Cu complex on a variable charge surface site. However, for consistency with models derived for weaker sorbing cations, a 2-site DLM with a variable charge and a permanent charge site was also developed. Conclusion Component additivity predictions of speciation in mixed mineral systems based on DLM parameters derived for the pure mineral systems were in good agreement with measured data. Discrepancies between the model predictions and measured data were similar to those observed for the calibrated pure mineral systems. The results suggest that quantifying specific interactions between HFO and kaolinite in speciation models may not be necessary. However, before the component additivity approach can be applied to natural sediments and soils, the effects of aging must be further studied and methods must be developed to estimate reactive surface areas of solid constituents in natural samples. PMID:18783619

  11. Genotoxicity of ferric oxide nanoparticles in Raphanus sativus: Deciphering the role of signaling factors, oxidative stress and cell death.

    PubMed

    Saquib, Quaiser; Faisal, Mohammad; Alatar, Abdulrahman A; Al-Khedhairy, Abdulaziz A; Ahmed, Mukhtar; Ansari, Sabiha M; Alwathnani, Hend A; Okla, Mohammad K; Dwivedi, Sourabh; Musarrat, Javed; Praveen, Shelly; Khan, Shams T; Wahab, Rizwan; Siddiqui, Maqsood A; Ahmad, Javed

    2016-09-01

    We have studied the genotoxic and apoptotic potential of ferric oxide nanoparticles (Fe2O3-NPs) in Raphanus sativus (radish). Fe2O3-NPs retarded the root length and seed germination in radish. Ultrathin sections of treated roots showed subcellular localization of Fe2O3-NPs, along with the appearance of damaged mitochondria and excessive vacuolization. Flow cytometric analysis of Fe2O3-NPs (1.0mg/mL) treated groups exhibited 219.5%, 161%, 120.4% and 161.4% increase in intracellular reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), nitric oxide (NO) and Ca(2+) influx in radish protoplasts. A concentration dependent increase in the antioxidative enzymes glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) and lipid peroxidation (LPO) has been recorded. Comet assay showed a concentration dependent increase in deoxyribonucleic acid (DNA) strand breaks in Fe2O3-NPs treated groups. Cell cycle analysis revealed 88.4% of cells in sub-G1 apoptotic phase, suggesting cell death in Fe2O3-NPs (2.0mg/mL) treated group. Taking together, the genotoxicity induced by Fe2O3-NPs highlights the importance of environmental risk associated with improper disposal of nanoparticles (NPs) and radish can serve as a good indicator for measuring the phytotoxicity of NPs grown in NP-polluted environment. PMID:27593272

  12. Genotoxicity of ferric oxide nanoparticles in Raphanus sativus: Deciphering the role of signaling factors, oxidative stress and cell death.

    PubMed

    Saquib, Quaiser; Faisal, Mohammad; Alatar, Abdulrahman A; Al-Khedhairy, Abdulaziz A; Ahmed, Mukhtar; Ansari, Sabiha M; Alwathnani, Hend A; Okla, Mohammad K; Dwivedi, Sourabh; Musarrat, Javed; Praveen, Shelly; Khan, Shams T; Wahab, Rizwan; Siddiqui, Maqsood A; Ahmad, Javed

    2016-09-01

    We have studied the genotoxic and apoptotic potential of ferric oxide nanoparticles (Fe2O3-NPs) in Raphanus sativus (radish). Fe2O3-NPs retarded the root length and seed germination in radish. Ultrathin sections of treated roots showed subcellular localization of Fe2O3-NPs, along with the appearance of damaged mitochondria and excessive vacuolization. Flow cytometric analysis of Fe2O3-NPs (1.0mg/mL) treated groups exhibited 219.5%, 161%, 120.4% and 161.4% increase in intracellular reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), nitric oxide (NO) and Ca(2+) influx in radish protoplasts. A concentration dependent increase in the antioxidative enzymes glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) and lipid peroxidation (LPO) has been recorded. Comet assay showed a concentration dependent increase in deoxyribonucleic acid (DNA) strand breaks in Fe2O3-NPs treated groups. Cell cycle analysis revealed 88.4% of cells in sub-G1 apoptotic phase, suggesting cell death in Fe2O3-NPs (2.0mg/mL) treated group. Taking together, the genotoxicity induced by Fe2O3-NPs highlights the importance of environmental risk associated with improper disposal of nanoparticles (NPs) and radish can serve as a good indicator for measuring the phytotoxicity of NPs grown in NP-polluted environment.

  13. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... GRAS § 184.1297 Ferric chloride. (a) Ferric chloride (iron (III) chloride, FeC13, CAS Reg. No. 7705-08-0) may be prepared from iron and chlorine or from ferric oxide and hydrogen chloride. The pure... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ferric chloride. 184.1297 Section 184.1297...

  14. Optical Study of Cuprous Oxide and Ferric Oxide Based Materials for Applications in Low Cost Solar Cells

    NASA Astrophysics Data System (ADS)

    Than, Thi Cuc; Bui, Bao Thoa; Wegmuller, Benjamin; Nguyen, Minh Hieu; Hoang Ngoc, Lam Huong; Bui, Van Diep; Nguyen, Quoc Hung; Hoang, Chi Hieu; Nguyen-Tran, Thuat

    2016-05-01

    One of the interesting forms of cuprous oxide and ferric oxide based materials is CuFeO2 which can be a delafossite-type compound and is a well known p-type semiconductor. This compound makes up an interesting family of materials for technological applications. CuFeO2 thin films recently gained renewed interest for potential applications in solar cell devices especially as absorption layers. One of the interesting facts is that CuFeO2 is made from cheap materials such as copper and iron. In this study, CuFeO2 thin films are intentionally deposited on corning glass and silicon substrates by the radio-frequency and direct current sputtering method with complicated and well developed co-sputtering recipes. The deposition was performed at room temperature which leads to an amorphous phase with extremely low roughness and high density. The films also were annealed at 500°C in 5% H2 in Ar for the passivation. A detailed optical study was performed on these thin films by spectroscopic ellipsometry and by ultra-violet visible near infrared spectroscopy. Depending on sputtering conditions, the direct band gap was extrapolated to be from 1.96 eV to 2.2 eV and 2.92 eV to 2.96 eV and the indirect band gap is about 1.22 eV to 1.42 eV. A good electrical conduction is also observed which is suitable for solar cell applications. In future more study on the structural properties will be carried out in order to fully understand these materials.

  15. Filamentous hydrous ferric oxide biosignatures in a pipeline carrying acid mine drainage at Iron Mountain Mine, California

    USGS Publications Warehouse

    Williams, Amy J.; Alpers, Charles N.; Sumner, Dawn Y.; Campbell, Kate M.

    2016-01-01

    A pipeline carrying acidic mine effluent at Iron Mountain, CA, developed Fe(III)-rich precipitate caused by oxidation of Fe(II)aq. The native microbial community in the pipe included filamentous microbes. The pipe scale consisted of microbial filaments, and schwertmannite (ferric oxyhydroxysulfate, FOHS) mineral spheres and filaments. FOHS filaments contained central lumina with diameters similar to those of microbial filaments. FOHS filament geometry, the geochemical environment, and the presence of filamentous microbes suggest that FOHS filaments are mineralized microbial filaments. This formation of textural biosignatures provides the basis for a conceptual model for the development and preservation of biosignatures in other environments.

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

    NASA Astrophysics Data System (ADS)

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

    2002-09-01

    The potential for incorporation of strontium (Sr) into biogenic Fe(II)-bearing minerals formed during microbial reduction of synthetic hydrous ferric oxide (HFO) was investigated in circumneutral bicarbonate-buffered medium containing SrCl 2 at concentrations of 10 μM, 100 μM, or 1.0 mM. CaCl 2 (10 mM) was added to some experiments to simulate a Ca-rich groundwater. In Ca-free systems, 89 to 100% of total Sr was captured in solid-phase compounds formed during reduction of 30 to 40 mmol Fe(III) L -1 over a 1-month period. A smaller fraction of total Sr (25 to 34%) was incorporated into the solid phase in cultures amended with 10 mM CaCl 2. X-ray diffraction identified siderite and ferroan ankerite as major end products of HFO reduction in Ca-free and Ca-amended cultures, respectively. Scanning electron microscopy-energy dispersive x-ray spectroscopy revealed the presence of Sr associated with carbonate phases. Selective extraction of HFO reduction end products indicated that 46 to 100% of the solid-phase Sr was associated with carbonates. The sequestration of Sr into carbonate phases in the Ca-free systems occurred systematically according to a heterogeneous (Doerner-Hoskins) partition coefficient (D D-H) of 1.81 ± 0.15. This D D-H value was 2 to 10 times higher than values determined for incorporation of Sr (10 μM) into FeCO 3(s) precipitated abiotically at rates comparable to or greater than rates observed during HFO reduction, and fivefold higher than theoretical partition coefficients for equilibrium Fe(Sr)CO 3 solid solution formation. Surface complexation and entrapment of Sr by rapidly growing siderite crystals (and possibly other biogenic Fe(II) solids) provides an explanation for the intensive scavenging of Sr in the Ca-free systems. The results of abiotic siderite precipitation experiments in the presence and absence of excess Ca indicate that substitution of Ca for Sr at foreign element incorporation sites (mass action effect) on growing FeCO 3(s

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

    SciTech Connect

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

    2002-08-15

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

  18. Comparative proteomic analysis of sulfur-oxidizing Acidithiobacillus ferrooxidans CCM 4253 cultures having lost the ability to couple anaerobic elemental sulfur oxidation with ferric iron reduction.

    PubMed

    Kucera, Jiri; Sedo, Ondrej; Potesil, David; Janiczek, Oldrich; Zdrahal, Zbynek; Mandl, Martin

    2016-09-01

    In extremely acidic environments, ferric iron can be a thermodynamically favorable electron acceptor during elemental sulfur oxidation by some Acidithiobacillus spp. under anoxic conditions. Quantitative 2D-PAGE proteomic analysis of a resting cell suspension of a sulfur-grown Acidithiobacillus ferrooxidans CCM 4253 subculture that had lost its iron-reducing activity revealed 147 protein spots that were downregulated relative to an iron-reducing resting cell suspension of the antecedent sulfur-oxidizing culture and 111 that were upregulated. Tandem mass spectrometric analysis of strongly downregulated spots identified several physiologically important proteins that apparently play roles in ferrous iron oxidation, including the outer membrane cytochrome Cyc2 and rusticyanin. Other strongly repressed proteins were associated with sulfur metabolism, including heterodisulfide reductase, thiosulfate:quinone oxidoreductase and sulfide:quinone reductase. Transcript-level analyses revealed additional downregulation of other respiratory genes. Components of the iron-oxidizing system thus apparently play central roles in anaerobic sulfur oxidation coupled with ferric iron reduction in the studied microbial strain. PMID:27394989

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  20. Syzyguim guineense Extracts Show Antioxidant Activities and Beneficial Activities on Oxidative Stress Induced by Ferric Chloride in the Liver Homogenate

    PubMed Central

    Pieme, Constant Anatole; Ngoupayo, Joseph; Khou-Kouz Nkoulou, Claude Herve; Moukette Moukette, Bruno; Njinkio Nono, Borgia Legrand; Ama Moor, Vicky Jocelyne; Ze Minkande, Jacqueline; Yonkeu Ngogang, Jeanne

    2014-01-01

    The aim of this study was to determine the in vitro antioxidant activity, free radical scavenging property and the beneficial effects of extracts of various parts of Syzygium guineense in reducing oxidative stress damage in the liver. The effects of extracts on free radicals were determined on radicals DPPH, ABTS, NO and OH followed by the antioxidant properties using Ferric Reducing Antioxidant Power assay (FRAP) and hosphomolybdenum (PPMB). The phytochemical screening of these extracts was performed by determination of the phenolic content. The oxidative damage inhibition in the liver was determined by measuring malondialdehyde (MDA) as well as the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and peroxidase. Overall, the bark extract of the ethanol/water or methanol showed the highest radical scavenging activities against DPPH, ABTS and OH radicals compared to the other extracts. This extract also contained the highest phenolic content implying the potential contribution of phenolic compounds towards the antioxidant activities. However, the methanol extract of the root demonstrated the highest protective effects of SOD and CAT against ferric chloride while the hydro-ethanol extract of the leaves exhibited the highest inhibitory effects on lipid peroxidation. These findings suggest that antioxidant properties of S. guineense extracts could be attributed to phenolic compounds revealed by phytochemical studies. Thus, the present results indicate clearly that the extracts of S. guineense possess antioxidant properties and could serve as free radical inhibitors or scavengers, acting possibly as primary antioxidants. The antioxidant properties of the bark extract may thus sustain its various biological activities. PMID:26785075

  1. Characterization of Nanophase Materials

    NASA Astrophysics Data System (ADS)

    Wang, Zhong Lin

    2000-01-01

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

  2. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Substances Affirmed as GRAS § 184.1297 Ferric chloride. (a) Ferric chloride (iron (III) chloride, FeC13, CAS Reg. No. 7705-08-0) may be prepared from iron and chlorine or from ferric oxide and hydrogen chloride... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ferric chloride. 184.1297 Section 184.1297 Food...

  3. Simultaneous microbial reduction of iron(III) and arsenic(V) in suspensions of hydrous ferric oxide.

    PubMed

    Campbell, Kate M; Malasarn, Davin; Saltikov, Chad W; Newman, Dianne K; Hering, Janet G

    2006-10-01

    Bacterial reduction of arsenic(V) and iron(III) oxides influences the redox cycling and partitioning of arsenic (As) between solid and aqueous phases in sediment-porewater systems. Two types of anaerobic bacterial incubations were designed to probe the relative order of As(V) and Fe(III) oxide reduction and to measure the effect of adsorbed As species on the rate of iron reduction, using hydrous ferric oxide (HFO) as the iron substrate. In one set of experiments, HFO was pre-equilibrated with As(V) and inoculated with fresh sediment from Haiwee Reservoir (Olancha, CA), an As-impacted field site. The second set of incubations consisted of HFO (without As) and As(III)- and As(V)- equilibrated HFO incubated with Shewanella sp. ANA-3 wild-type (WT) and ANA-3deltaarrA, a mutant unable to produce the respiratory As(V) reductase. Of the two pathways for microbial As(V) reduction (respiration and detoxification), the respiratory pathway was dominant under these experimental conditions. In addition, As(III) adsorbed onto the surface of HFO enhanced the rate of microbial Fe(III) reduction. In the sediment and ANA-3 incubations, As(V) was reduced simultaneously or prior to Fe(III), consistent with thermodynamic calculations based on the chemical conditions of the ANA-3 WT incubations.

  4. Mercury (II) reduction and co-precipitation of metallic mercury on hydrous ferric oxide in contaminated groundwater.

    PubMed

    Richard, Jan-Helge; Bischoff, Cornelia; Ahrens, Christian G M; Biester, Harald

    2016-01-01

    Mercury (Hg) speciation and sorption analyses in contaminated aquifers are useful for understanding transformation, retention, and mobility of Hg in groundwater. In most aquifers hydrous ferric oxides (HFOs) are among the most important sorbents for trace metals; however, their role in sorption or mobilization of Hg in aquifers has been rarely analyzed. In this study, we investigated Hg chemistry and Hg sorption to HFO under changing redox conditions in a highly HgCl2-contaminated aquifer (up to 870μgL(-1) Hg). Results from aqueous and solid phase Hg measurements were compared to modeled (PHREEQC) data. Speciation analyses of dissolved mercury indicated that Hg(II) forms were reduced to Hg(0) under anoxic conditions, and adsorbed to or co-precipitated with HFO. Solid phase Hg thermo-desorption measurements revealed that between 55 and 93% of Hg bound to HFO was elemental Hg (Hg(0)). Hg concentrations in precipitates reached more than 4 weight %, up to 7000 times higher than predicted by geochemical models that do not consider unspecific sorption to and co-precipitation of elemental Hg with HFO. The observed process of Hg(II) reduction and Hg(0) formation, and its retention and co-precipitation by HFO is thought to be crucial in HgCl2-contaminated aquifers with variable redox-conditions regarding the related decrease in Hg solubility (factor of ~10(6)), and retention of Hg in the aquifer.

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

    PubMed Central

    D'Autréaux, Benoît; Touati, Danièle; Bersch, Beate; Latour, Jean-Marc; Michaud-Soret, Isabelle

    2002-01-01

    Ferric uptake regulation protein (Fur) is a bacterial global regulator that uses iron as a cofactor to bind to specific DNA sequences. The function of Fur is not limited to iron homeostasis. A wide variety of genes involved in various mechanisms such as oxidative and acid stresses are under Fur control. Flavohemoglobin (Hmp) is an NO-detoxifying enzyme induced by NO and nitrosothiol compounds. Fur recently was found to regulate hmp in Salmonella typhimurium, and in Escherichia coli, the iron-chelating agent 2,2′-dipyridyl induces hmp expression. We now establish direct inhibition of E. coli Fur activity by NO. By using chromosomal Fur-regulated lacZ reporter fusion in E. coli, Fur activity is switched off by NO at micromolar concentration. In vitro Fur DNA-binding activity, as measured by protection of restriction site in aerobactin promoter, is directly sensitive to NO. NO reacts with FeII in purified FeFur protein to form a S = 1/2 low-spin FeFur–NO complex with a g = 2.03 EPR signal. Appearance of the same EPR signal in NO-treated cells links nitrosylation of the iron with Fur inhibition. The nitrosylated Fur protein is still a dimer and is stable in anaerobiosis but slowly decays in air. This inhibition probably arises from a conformational switch, leading to an inactive dimeric protein. These data establish a link between control of iron metabolism and the response to NO effects. PMID:12475930

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

    SciTech Connect

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

    2007-01-01

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

  7. Ameliorative effect of polyphenols from Padina boergesenii against ferric nitrilotriacetate induced renal oxidative damage: With inhibition of oxidative hemolysis and in vitro free radicals.

    PubMed

    Rajamani, Karthikeyan; Renju, V C; Sethupathy, S; Thirugnanasambandan, Somasundaram S

    2015-07-01

    The aim of this study was to evaluate the antioxidant activities of diethyl ether (DEE) and methanol (M) extracts from brown alga Padina boergesenii using in vitro and in vivo antioxidant assay, which may help to relate the antioxidant properties with the possible outline of its ameliorative effect. M extract showed higher radical scavenging activity through ferric reducing antioxidant power 139.11 µmol tannic acid equivalent/g; DPPH 71.32 ± 0.56%; deoxyribose radical 88.31 ± 0.47%, and total antioxidant activity 0.47 ± 0.02 mg ascorbic acid equivalents/g. Oxidative red blood cell (RBC) hemolysis inhibition rate was significantly higher in M extract (150 mg/kg body weight) in reference to total phenolic content (r = 0.935). Rats administered with DEE and M extracts (150 mg/kg body weight) for seven days before the administration of ferric nitrilotriacetate (9 mg of Fe/mg/kg bodyweight). Rats pretreated with extracts significantly changed the level of renal microsomal lipid peroxidation, glutathione, and antioxidant enzymes in post-mitochondrial supernatant (P < 0.05). Ameliorative effect of extracts against renal oxidative damage was evident in rat kidney through changes in necrotic and epithelial cells. HPTLC technique has identified the presence of rutin with reference to retardation factor (Rf ) in both the extracts. These findings support the source of polyphenols (rutin) from P. boergesenii had potent antioxidant activity; further work on isolation of bioactive compounds can be channeled to develop as a natural antioxidant.

  8. Can ferric-superoxide act as a potential oxidant in P450(cam)? QM/MM investigation of hydroxylation, epoxidation, and sulfoxidation.

    PubMed

    Lai, Wenzhen; Shaik, Sason

    2011-04-13

    In view of recent reports of high reactivity of ferric-superoxide species in heme and nonheme systems (Morokuma et al. J. Am. Chem. Soc. 2010, 132, 11993-12005; Que et al. Inorg. Chem. 2010, 49, 3618-3628; Nam et al. J. Am. Chem. Soc. 2010, 132, 5958-5959; J. Am. Chem. Soc. 2010, 132, 10668-10670), we use herein combined quantum mechanics/molecular mechanics (QM/MM) methods to explore the potential reactivity of P450(cam) ferric-superoxide toward hydroxylation, epoxidation, and sulfoxidation. The calculations demonstrate that P450 ferric-superoxide is a sluggish oxidant compared with the high-valent oxoiron porphyrin cation-radical species. As such, unlike heme enzymes with a histidine axial ligand, the P450 superoxo species does not function as an oxidant in P450(cam). The origin of this different behavior of the superoxo species of P450 vis-à-vis other heme enzymes like tryptophan 2, 3-dioxygenase (TDO) is traced to the ability of the latter superoxo species to make a stronger FeOO-X (X = H,C) bond and to stabilize the corresponding bond-activation transition states by resonance with charge-transfer configurations. By contrast, the negatively charged thiolate ligand in the P450 superoxo species minimizes the mixing of charge transfer configurations in the transition state and raises the reaction barrier. However, as we demonstrate, an external electric field oriented along the Fe-O axis with a direction pointing from Fe toward O will quench Cpd I formation by slowing the reduction of ferric-superoxide and will simultaneously lower the barriers for oxidation by the latter species, thereby enabling observation of superoxo chemistry in P450. Other options for nascent superoxo reactivity in P450 are discussed.

  9. Kinetic Modeling of Phosphate Adsorption by Preformed and In situ formed Hydrous Ferric Oxides at Circumneutral pH

    PubMed Central

    Mao, Yanpeng; Yue, Qinyan

    2016-01-01

    Kinetics of phosphate removal by Fe(III) was investigated by both preformed and in situ formed hydrous ferric oxides (HFO) at pH 6.0–8.0. A pseudo-second-order empirical model was found to adequately describe phosphate removal in the two cases. The Elovich and intra-particle diffusion models, however, were only capable of describing phosphate adsorption to preformed HFO (PF-HFO). By using surface complexation kinetic models (SCKMs) to describe phosphate adsorption to PF-HFO, the adsorption rate constant (0.0386–0.205 mM−1 min−1 for SCKM-1 and 0.0680–0.274 mM−1 min−1 for SCKM-2) decreased with increasing pH while the protonation reaction rate constant in SCKM-2 (0.0776–0.0947 mM−1 min−1) increased over the pH range 6.0–8.0. Using the rate constants obtained from the process of phosphate adsorption to PF-HFO, the amount of active surface sites on the in situ formed HFO were calculated as 0.955 ± 0.170, 1.46 ± 0.39 and 2.98 ± 0.78 mM for pH = 6.0, 7.0 and 8, respectively. Generally, as the SCKMs incorporate phosphate complexation on HFO surface sites and protons competiting for the surface sites, they could provide a good description of the rate and extent of phosphate removal by both preformed and in-situ formed HFO over a wide range of conditions. PMID:27739456

  10. Kinetic Modeling of Phosphate Adsorption by Preformed and In situ formed Hydrous Ferric Oxides at Circumneutral pH

    NASA Astrophysics Data System (ADS)

    Mao, Yanpeng; Yue, Qinyan

    2016-10-01

    Kinetics of phosphate removal by Fe(III) was investigated by both preformed and in situ formed hydrous ferric oxides (HFO) at pH 6.0–8.0. A pseudo-second-order empirical model was found to adequately describe phosphate removal in the two cases. The Elovich and intra-particle diffusion models, however, were only capable of describing phosphate adsorption to preformed HFO (PF-HFO). By using surface complexation kinetic models (SCKMs) to describe phosphate adsorption to PF-HFO, the adsorption rate constant (0.0386–0.205 mM‑1 min‑1 for SCKM-1 and 0.0680–0.274 mM‑1 min‑1 for SCKM-2) decreased with increasing pH while the protonation reaction rate constant in SCKM-2 (0.0776–0.0947 mM‑1 min‑1) increased over the pH range 6.0–8.0. Using the rate constants obtained from the process of phosphate adsorption to PF-HFO, the amount of active surface sites on the in situ formed HFO were calculated as 0.955 ± 0.170, 1.46 ± 0.39 and 2.98 ± 0.78 mM for pH = 6.0, 7.0 and 8, respectively. Generally, as the SCKMs incorporate phosphate complexation on HFO surface sites and protons competiting for the surface sites, they could provide a good description of the rate and extent of phosphate removal by both preformed and in-situ formed HFO over a wide range of conditions.

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

    PubMed

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

    2010-01-01

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

  12. Nuclear fuel elements made from nanophase materials

    DOEpatents

    Heubeck, N.B.

    1998-09-08

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

  13. Nuclear fuel elements made from nanophase materials

    DOEpatents

    Heubeck, Norman B.

    1998-01-01

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

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

    SciTech Connect

    Warshawsky, D.; Bingham, E.

    1984-01-01

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

  15. Osteoblast adhesion on nanophase ceramics.

    PubMed

    Webster, T J; Siegel, R W; Bizios, R

    1999-07-01

    Osteoblast adhesion on nanophase alumina (Al2O3) and titania (TiO2) was investigated in vitro. Osteoblast adhesion to nanophase alumina and titania in the absence of serum from Dulbecco's modified Eagle medium (DMEM) was significantly (P < 0.01) less than osteoblast adhesion to alumina and titania in the presence of serum. In the presence of 10% fetal bovine serum in DMEM osteoblast adhesion on nanophase alumina (23 nm grain size) and titania (32 nm grain size) was significantly (P < 0.05) greater than on conventional alumina (177 nm grain size) and titania (2.12 microm grain size), respectively, after 1, 2, and 4 h. Further investigation of the dependence of osteoblast adhesion on alumina and titania grain size indicated the presence of a critical grain size for osteoblast adhesion between 49 and 67 nm for alumina and 32 and 56 nm for titania. The present study provides evidence of the ability of nanophase alumina and titania to simulate material characteristics (such as surface grain size) of physiological bone that enhance protein interactions (such as adsorption, configuration, bioactivity, etc.) and subsequent osteoblast adhesion.

  16. Oxidation of thiamine on reaction with nitrogen dioxide generated by ferric myoglobin and hemoglobin in the presence of nitrite and hydrogen peroxide.

    PubMed

    Stepuro, I I; Oparin, A Yu; Stsiapura, V I; Maskevich, S A; Titov, V Yu

    2012-01-01

    It is shown that nitrogen dioxide oxidizes thiamine to thiamine disulfide, thiochrome, and oxodihydrothiochrome (ODTch). The latter is formed during oxidation of thiochrome by nitrogen dioxide. Nitrogen dioxide was produced by incubation of nitrite with horse ferric myoglobin and human hemoglobin in the presence of hydrogen peroxide. After addition of tyrosine or phenol to aqueous solutions containing oxoferryl forms of the hemoproteins, thiamine, and nitrite, the yield of thiochrome greatly increased, whereas the yield of ODTch decreased. In the presence of high concentrations of tyrosine or phenol compounds ODTch was not formed at all. The neutral form of thiamine with the closed thiazole cycle and minor tricyclic form of thiamine do not enter the heme pocket of the protein and do not interact with the oxoferryl heme complex Fe(IV=O) or porphyrin radical. The tricyclic form of thiamine is oxidized to thiochrome by tyrosyl radicals located on the surface of the hemoprotein. The thiol form of thiamine is oxidized to thiamine disulfide by both hemoprotein tyrosyl radicals and oxoferryl heme complexes. Nitrite and also tyrosine, tyramine, and phenol readily penetrate into the heme pocket of the protein and reduce the oxyferryl complex to ferric cation. These reactions yield nitrogen dioxide as well as tyrosyl and phenoxyl radicals of tyrosine molecules and phenol compounds, respectively. Tyrosyl and phenoxyl radicals of low molecular weight compounds oxidize thiamine only to thiochrome and thiamine disulfide. The effect of oxoferryl forms of myoglobin and hemoglobin, nitrogen dioxide, and phenol on thiamine oxidative transformation as well as antioxidant properties of the hydrophobic thiamine metabolites thiochrome and ODTch are discussed.

  17. Sodium Ferric Gluconate Injection

    MedlinePlus

    Sodium ferric gluconate injection is used to treat iron-deficiency anemia (a lower than normal number of ... are also receiving the medication epoetin (Epogen, Procrit). Sodium ferric gluconate injection is in a class of ...

  18. Relationship between reaction rate constants of organic pollutants and their molecular descriptors during Fenton oxidation and in situ formed ferric-oxyhydroxides.

    PubMed

    Jia, Lijuan; Shen, Zhemin; Su, Pingru

    2016-05-01

    Fenton oxidation is a promising water treatment method to degrade organic pollutants. In this study, 30 different organic compounds were selected and their reaction rate constants (k) were determined for the Fenton oxidation process. Gaussian09 and Material Studio software sets were used to carry out calculations and obtain values of 10 different molecular descriptors for each studied compound. Ferric-oxyhydroxide coagulation experiments were conducted to determine the coagulation percentage. Based upon the adsorption capacity, all of the investigated organic compounds were divided into two groups (Group A and Group B). The percentage adsorption of organic compounds in Group A was less than 15% (wt./wt.) and that in the Group B was higher than 15% (wt./wt.). For Group A, removal of the compounds by oxidation was the dominant process while for Group B, removal by both oxidation and coagulation (as a synergistic process) took place. Results showed that the relationship between the rate constants (k values) and the molecular descriptors of Group A was more pronounced than for Group B compounds. For the oxidation-dominated process, EHOMO and Fukui indices (f(0)x, f(-)x, f(+)x) were the most significant factors. The influence of bond order was more significant for the synergistic process of oxidation and coagulation than for the oxidation-dominated process. The influences of all other molecular descriptors on the synergistic process were weaker than on the oxidation-dominated process.

  19. Relationship between reaction rate constants of organic pollutants and their molecular descriptors during Fenton oxidation and in situ formed ferric-oxyhydroxides.

    PubMed

    Jia, Lijuan; Shen, Zhemin; Su, Pingru

    2016-05-01

    Fenton oxidation is a promising water treatment method to degrade organic pollutants. In this study, 30 different organic compounds were selected and their reaction rate constants (k) were determined for the Fenton oxidation process. Gaussian09 and Material Studio software sets were used to carry out calculations and obtain values of 10 different molecular descriptors for each studied compound. Ferric-oxyhydroxide coagulation experiments were conducted to determine the coagulation percentage. Based upon the adsorption capacity, all of the investigated organic compounds were divided into two groups (Group A and Group B). The percentage adsorption of organic compounds in Group A was less than 15% (wt./wt.) and that in the Group B was higher than 15% (wt./wt.). For Group A, removal of the compounds by oxidation was the dominant process while for Group B, removal by both oxidation and coagulation (as a synergistic process) took place. Results showed that the relationship between the rate constants (k values) and the molecular descriptors of Group A was more pronounced than for Group B compounds. For the oxidation-dominated process, EHOMO and Fukui indices (f(0)x, f(-)x, f(+)x) were the most significant factors. The influence of bond order was more significant for the synergistic process of oxidation and coagulation than for the oxidation-dominated process. The influences of all other molecular descriptors on the synergistic process were weaker than on the oxidation-dominated process. PMID:27155432

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

    PubMed

    Förstner, U; Jacobs, P; Kammer, F

    2001-11-01

    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.

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

    PubMed

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

    1993-11-25

    A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (gamma-Fe2O3) by mild heat treatment and then to nanophase hematite (alpha-Fe2O3) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism

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

    PubMed

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

    1993-11-25

    A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (gamma-Fe2O3) by mild heat treatment and then to nanophase hematite (alpha-Fe2O3) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (gamma-Fe2O3) by mild heat treatment and then to nanophase hematite (alpha-Fe2O3) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism

  4. System for continuous production of nanophase materials using a microwave-driven polyol process.

    PubMed

    Gold, Steven H; Bruce, Ralph W; Fliflet, Arne W; Lewis, David; Kurihara, Lynn K; Imam, M A

    2007-02-01

    A prototype system is described for the large scale, continuous production of nanophase metals, metal oxides, and other nanophase materials using the polyol process. The polyol process employs an organic solvent such as ethylene glycol to reduce a metal oxide/metal salt at high temperature to the metal oxide or metal. The system employs a 6 kW, 2.45 GHz microwave source to rapidly heat the continuously flowing solution to a desired process temperature as it flows through a silica tube placed along the center line of a section of waveguide.

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

    PubMed Central

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

    1990-01-01

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

  6. Center for Nanophase Materials Sciences

    NASA Astrophysics Data System (ADS)

    Horton, Linda

    2002-10-01

    The Center for Nanophase Materials Sciences (CNMS) will be a user facility with a strong component of joint, collaborative research. CNMS is being developed, together with the scientific community, with support from DOE's Office of Basic Energy Sciences. The Center will provide a thriving, multidisciplinary environment for research as well as the education of students and postdoctoral scholars. It will be co-located with the Spallation Neutron Source (SNS) and the Joint Institute for Neutron Sciences (JINS). The CNMS will integrate nanoscale research with neutron science, synthesis science, and theory/modeling/simulation, bringing together four areas in which the United States has clear national research and educational needs. The Center's research will be organized under three scientific thrusts: nano-dimensioned "soft" materials (including organic, hybrid, and interfacial nanophases); complex "hard" materials systems (including the crosscutting areas of interfaces and reduced dimensionality that become scientifically critical on the nanoscale); and theory/modeling/simulation. This presentation will summarize the progress towards identification of the specific research focus topics for the Center. Currently proposed topics, based on two workshops with the potential user community, include catalysis, nanomagnetism, synthetic and bio-inspired macromolecular materials, nanophase biomaterials, nanofluidics, optics/photonics, carbon-based nanostructures, collective behavior, nanoscale interface science, virtual synthesis and nanomaterials design, and electronic structure, correlations, and transport. In addition, the proposed 80,000 square foot facility (wet/dry labs, nanofabrication clean rooms, and offices) and the associated technical equipment will be described. The CNMS is scheduled to begin construction in spring, 2003. Initial operations are planned for late in 2004.

  7. Arsenic removal by ferric chloride

    SciTech Connect

    Hering, J.G.; Chen, P.Y.; Wilkie, J.A.; Elimelech, M.; Liang, S.

    1996-04-01

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

  8. Ferric sulfates on Mars

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.

    1987-01-01

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

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

    SciTech Connect

    Li, X.

    1998-11-23

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

  10. Enhanced functions of osteoblasts on nanophase ceramics.

    PubMed

    Webster, T J; Ergun, C; Doremus, R H; Siegel, R W; Bizios, R

    2000-09-01

    Select functions of osteoblasts (bone-forming cells) on nanophase (materials with grain sizes less than 100 nm) alumina, titania, and hydroxyapatite (HA) were investigated using in vitro cellular models. Compared to conventional ceramics, surface occupancy of osteoblast colonies was significantly less on all nanophase ceramics tested in the present study after 4 and 6 days of culture. Osteoblast proliferation was significantly greater on nanophase alumina, titania, and HA than on conventional formulations of the same ceramic after 3 and 5 days. More importantly, compared to conventional ceramics, synthesis of alkaline phosphatase and deposition of calcium-containing mineral was significantly greater by osteoblasts cultured on nanophase than on conventional ceramics after 21 and 28 days. The results of the present study provided the first evidence of enhanced long-term (on the order of days to weeks) functions of osteoblasts cultured on nanophase ceramics; in this manner, nanophase ceramics clearly represent a unique and promising class of orthopaedic/dental implant formulations with improved osseointegrative properties.

  11. Flavins secreted by roots of iron-deficient Beta vulgaris enable mining of ferric oxide via reductive mechanisms.

    PubMed

    Sisó-Terraza, Patricia; Rios, Juan J; Abadía, Javier; Abadía, Anunciación; Álvarez-Fernández, Ana

    2016-01-01

    Iron (Fe) is abundant in soils but generally poorly soluble. Plants, with the exception of Graminaceae, take up Fe using an Fe(III)-chelate reductase coupled to an Fe(II) transporter. Whether or not nongraminaceous species can convert scarcely soluble Fe(III) forms into soluble Fe forms has deserved little attention so far. We have used Beta vulgaris, one among the many species whose roots secrete flavins upon Fe deficiency, to study whether or not flavins are involved in Fe acquisition. Flavins secreted by Fe-deficient plants were removed from the nutrient solution, and plants were compared with Fe-sufficient plants and Fe-deficient plants without flavin removal. Solubilization of a scarcely soluble Fe(III)-oxide was assessed in the presence or absence of flavins, NADH (nicotinamide adenine dinucleotide, reduced form) or plant roots, and an Fe(II) trapping agent. The removal of flavins from the nutrient solution aggravated the Fe deficiency-induced leaf chlorosis. Flavins were able to dissolve an Fe(III)-oxide in the presence of NADH. The addition of extracellular flavins enabled roots of Fe-deficient plants to reductively dissolve an Fe(III)-oxide. We concluded that root-secretion of flavins improves Fe nutrition in B. vulgaris. Flavins allow B. vulgaris roots to mine Fe from Fe(III)-oxides via reductive mechanisms.

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

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Lauer, Howard V., Jr.

    1990-01-01

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

  13. Carbon quantum dots directly generated from electrochemical oxidation of graphite electrodes in alkaline alcohols and the applications for specific ferric ion detection and cell imaging.

    PubMed

    Liu, Mengli; Xu, Yuanhong; Niu, Fushuang; Gooding, J Justin; Liu, Jingquan

    2016-04-25

    Carbon quantum dots (CQDs) are attracting tremendous interest owing to their low toxicity, water dispersibility, biocompatibility, optical properties and wide applicability. Herein, CQDs with an average diameter of (4.0 ± 0.2) nm and high crystallinity were produced simply from the electrochemical oxidation of a graphite electrode in alkaline alcohols. The as-formed CQDs dispersion was colourless but the dispersion gradually changed to bright yellow when stored in ambient conditions. Based on UV-Vis absorption, fluorescence spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM), this colour change appeared to be due to oxygenation of surface species over time. Furthermore, the CQDs were used in specific and sensitive detection of ferric ion (Fe(3+)) with broad linear ranges of 10-200 μM with a low limit of detection of 1.8 μM (S/N = 3). The application of the CQDs for Fe(3+) detection in tap water was demonstrated and the possible mechanism was also discussed. Finally, based on their good characteristics of low cytotoxicity and excellent biocompatibility, the CQDs were successfully applied to cell imaging. PMID:26878217

  14. Nanophase materials assembled from clusters

    SciTech Connect

    Siegel, R.W.

    1992-02-01

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

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

    PubMed

    Refat, Moamen S

    2014-12-10

    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

  16. Mutations of ferric uptake regulator (fur) impair iron homeostasis, growth, oxidative stress survival, and virulence of Xanthomonas campestris pv. campestris.

    PubMed

    Jittawuttipoka, Thichakorn; Sallabhan, Ratiboot; Vattanaviboon, Paiboon; Fuangthong, Mayuree; Mongkolsuk, Skorn

    2010-05-01

    Iron is essential in numerous cellular functions. Intracellular iron homeostasis must be maintained for cell survival and protection against iron's toxic effects. Here, we characterize the roles of Xanthomonas campestris pv. campestris (Xcc) fur, which encodes an iron sensor and a transcriptional regulator that acts in iron homeostasis, oxidative stress, and virulence. Herein, we isolated spontaneous Xcc fur mutants that had high intracellular iron concentrations due to constitutively high siderophore levels and increased expression of iron transport genes. These mutants also had reduced aerobic plating efficiency and resistance to peroxide killing. Moreover, one fur mutant was attenuated on a host plant, thus indicating that fur has important roles in the virulence of X. campestris pv. campestris.

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

    SciTech Connect

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

    2012-10-15

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  20. [Effect of Ferric Iron on Nitrogen Immigration and Transformation and Nitrous Oxide Emission During Simultaneous Nitrification Denitrification Process].

    PubMed

    Li, Hao; Yan, Yu-jie; Xie, Hui-jun; Jia, Wen-lin; Hu, Zhen; Zhang, Jian

    2015-04-01

    Effect of Fe(III) concentration on nitrogen immigration and transformation and nitrous oxide emission during the simultaneous nitrification denitrification (SND) process was investigated. Higher nitrogen removal efficiency was obtained when the Fe(III) concentration was 20 mg x L(-1), while lower nitrogen removal efficiency was observed when the Fe (III) concentration turned to 60 mg x L(-1). In addition, higher Fe(III) concentration significantly enhanced the N2O emission, as well as the N2O conversion ratio. This was mainly attributed to (1) the high concentration of nitrite accumulation during the oxic stage, which was caused by lower dehydrogenase activity at high Fe(III) concentration; (2) less PHB production during the anoxic stage, which would led to shortage of carbon source for denitrification in the following oxic stage. The results also showed that Fe(III) addition could improve the TP removal efficiency. TP removal efficiency increased with increasing Fe(III) concentration, mainly because of extra chemical reaction.

  1. Altered responses of chondrocytes to nanophase PLGA/nanophase titania composites.

    PubMed

    Savaiano, Jennifer K; Webster, Thomas J

    2004-01-01

    Chondrocyte (cartilage-synthesizing cells) cell density and synthesis of select intracellular proteins by chondrocytes were investigated on novel nanophase poly-lactic/glycolic acid (PLGA) and titania composites in the present in vitro study. Nanophase PLGA films were created by chemically treating conventional (or micron-structured) PLGA films with 10N NaOH for 1h. Titania particle dimensions in ceramic compacts were controlled by utilizing either conventional (i.e., micron) or nanometer grain size titania. Composites of either conventional or nanophase PLGA with either conventional or nanophase titania at 70/30wt% were also created. Compared to surfaces with a conventional or micron topography, results provided the first evidence of stagnant confluent cell densities on nanostructured surfaces at time points between 1 and 7 days. Moreover, compared to surfaces with a conventional topography, increased chondrocyte intracellular synthesis of alkaline phosphatase and chondrocyte expressed protein-68 (proteins that have been correlated with the functions of chondrocytes) were observed on nanophase PLGA/nanophase titania composites. The present study, thus, provided the first evidence of different chondrocyte responses to nanostructured PLGA/nanophase titania composites; in light of other reports demonstrating increased functions of bone cells on the same materials, such data indicates that further investigation of these materials at the bone-cartilage interface should be conducted.

  2. Ferric Tourmaline from Mexico.

    PubMed

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

    1964-04-01

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

  3. Ferric Tourmaline from Mexico.

    PubMed

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

    1964-04-01

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

  4. Formation, reactivity, and aging of ferric oxide particles formed from Fe(II) and Fe(III) sources: Implications for iron bioavailability in the marine environment

    NASA Astrophysics Data System (ADS)

    Bligh, Mark W.; Waite, T. David

    2011-12-01

    Freshly formed amorphous ferric oxides (AFO) in the water column are potentially highly reactive, but with reactivity declining rapidly with age, and have the capacity to partake in reactions with dissolved species and to be a significant source of bioavailable iron. However, the controls on reactivity in aggregated oxides are not well understood. Additionally, the mechanism by which early rapid aging occurs is not clear. Aging is typically considered in terms of changes in crystallinity as the structure of an iron oxide becomes more stable and ordered with time thus leading to declining reactivity. However, there has been recognition of the role that aggregation can play in determining reactivity, although it has received limited attention. Here, we have formed AFO in seawater in the laboratory from either an Fe(II) or Fe(III) source to produce either AFO(II) or AFO(III). The changes in reactivity of these two oxides following formation was measured using both ligand-promoted dissolution (LPD) and reductive dissolution (RD). The structure of the two oxides was examined using light scattering and X-ray adsorption techniques. The dissolution rate of AFO(III) was greater than that of AFO(II), as measured by both dissolution techniques, and could be attributed to both the less ordered molecular structure and smaller primary particle size of AFO(III). From EXAFS analysis shortly (90 min) following formation, AFO(II) and AFO(III) were shown to have the same structure as aged lepidocrocite and ferrihydrite respectively. Both oxides displayed a rapid decrease in dissolution rate over the first hours following formation in a pattern that was very similar when normalised. The early establishment and little subsequent change of crystal structure for both oxides undermined the hypothesis that increasing crystallinity was responsible for early rapid aging. Also, an aging model describing this proposed process could only be fitted to the data with kinetic parameters that were

  5. [Study on Raman spectrum of nanophase anatase].

    PubMed

    Li, Y; Duan, Y; Li, W

    2000-10-01

    The nanophase anatase of different sizes (2-40 nm) were synthesized with chemical precipitation method. Nanophase anatase (2-40 nm), anatase (micron) and natural anatase were investigated by Raman spectrum. The spectra indicate: when the crystalline particles sizes decreased, obvious Raman shifts towards higher frequencies were observed and the intensity of Raman scattering decreased markedly. The shift towards higher frequencies reached max (10 cm-1) at 143 cm-1 comparing 2 nm anatase and natural anatase; when the crystalline particles sizes decreased; the shifts at 515 and 637 cm-1 towards higher frequencies reached max, but while the crystalline particles sizes became smaller, the shifts reached towards lower frequencies; There was no obvious shift at 396 cm-1 with the decreasing of the crystalline particle sizes. These reflect the complexity of nanophase materials structure, that may be caused by flexibility distortion of crystal.

  6. Nanophase change for data storage applications.

    PubMed

    Shi, L P; Chong, T C

    2007-01-01

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

  7. Influence of the dose levels of cocarcinogen ferric oxide on the metabolism of benzo[a]pyrene by pulmonary alveolar macorphages in suspension culture

    SciTech Connect

    Greife, A.L. ); Warshawsky, D. )

    1993-01-01

    The concurrent administration of a cocarcinogenic carrier particle such as ferric oxide (Fe[sub 2]O[sub 3]) and the polycyclic aromatic hydrocarbon lung carcinogen benzo[a]pyrene (BaP) results in a decreased latency and an increased incidence in the production of lung tumors in hamsters compared to the administration of BaP alone. The pulmonary alveolar macrophage (AM), the primary lung defense cell, has been shown to endoctyze BaP, metabolize BaP to a more biologically active form, and then release metabolites. Therefore, a study was undertaken to determine in a dose-response manner the effect of AM phagocysosis of a carrier particle (Fe[sub 2]O[sub 3]) on the metabolism of a carcinogen (BaP) and on the production of reactive oxygen. The AM were lavaged from hamsters and cultured in suspension (2.5 [times] 10[sup 6] cells/vial) with bAp (62.5 NMOL, [sup 14]c labeled) alone or adsorbed onto 0.5, 1.0, or 2.0 mg Fe[sub 2]O[sub 3] in the presence of cytochrome c. Following separate ethyl acetate extractions of the AM and medium, the metabolites were isolated by high-performance liquid chromatography (HPLC) and quantified by liquid scintillation spectrometry. The production of superoxide anions was monitored by the reduction of cyctochrome c. Concurrent exposure of AM to BaP-coated Fe[sub 2]O[sub 3] resulted in a significant increase in the amount of BaP metabolites and superoxide anions produced with dose of Fe[sub 2]O[sub 3]. The following metabolites and superoxide anions produced with dose of Fe[sub e]O[sub 3]. The following metabolites were identified in both the medium and the AM: 9,10-dihydrodiol, 7,8-dihydrodiol, 4,5-dihydrodiol, 9-hydroxy, 3-hydroxy, and 3,6 quinone. 44 refs., 5 figs., 2 tabs.

  8. Adhesion of Pseudomonas fluorescens onto nanophase materials

    NASA Astrophysics Data System (ADS)

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

    2005-07-01

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

  9. Adhesion of Pseudomonas fluorescens onto nanophase materials.

    PubMed

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

    2005-07-01

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

  10. Crossed ferric oxide nanosheets supported cobalt oxide on 3-dimensional macroporous Ni foam substrate used for diesel soot elimination under self-capture contact mode

    NASA Astrophysics Data System (ADS)

    Cao, Chunmei; Li, Xingang; Zha, Yuqing; Zhang, Jing; Hu, Tiandou; Meng, Ming

    2016-03-01

    Crossed Fe2O3 nanosheets supported cobalt oxide nanoparticles on three-dimensionally macroporous nickel foam substrate (xCo/Fe-NF) was designed and successfully prepared through a facile hydrothermal and impregnation route. These catalysts showed high catalytic soot combustion activities under self-capture contact mode. The three-dimensional macroporous structures of Ni foam and the crossed Fe2O3 nanosheets constituted macroporous voids can greatly increase the contact efficiency between soot particulates and catalysts. The interaction between Co and Fe facilitated the activation of the Fe-O bond and increased the amounts of active oxygen species, thus improving the redox property of the catalysts. The 0.6Co/Fe-NF catalyst exhibited the highest turnover frequency (TOF) for soot combustion, which is in good accordance with the largest amount of active oxygen species. Based upon the catalytic performance and multiple characterization results, two reaction pathways for soot oxidation are identified, namely, the direct oxidation by the activated oxygen species via oxygen vacancies and the NOx-aided soot oxidation.Crossed Fe2O3 nanosheets supported cobalt oxide nanoparticles on three-dimensionally macroporous nickel foam substrate (xCo/Fe-NF) was designed and successfully prepared through a facile hydrothermal and impregnation route. These catalysts showed high catalytic soot combustion activities under self-capture contact mode. The three-dimensional macroporous structures of Ni foam and the crossed Fe2O3 nanosheets constituted macroporous voids can greatly increase the contact efficiency between soot particulates and catalysts. The interaction between Co and Fe facilitated the activation of the Fe-O bond and increased the amounts of active oxygen species, thus improving the redox property of the catalysts. The 0.6Co/Fe-NF catalyst exhibited the highest turnover frequency (TOF) for soot combustion, which is in good accordance with the largest amount of active oxygen

  11. Mechanisms of enhanced osteoblast adhesion on nanophase alumina involve vitronectin.

    PubMed

    Webster, T J; Schadler, L S; Siegel, R W; Bizios, R

    2001-06-01

    The role, including concentration, conformation, and bioactivity, of adsorbed vitronectin in enhancing osteoblast adhesion on nanophase alumina was investigated in the present study. Vitronectin adsorbed in a competitive environment in the highest concentration on nanophase alumina compared to conventional alumina. Enhanced adsorption of vitronectin on nanophase alumina was possibly due to decreased adsorption of apolipoprotein A-I and/or increased adsorption of calcium on nanophase alumina. In a novel manner, the present study utilized surface-enhanced Raman scattering (SERS) to determine the conformation of vitronectin adsorbed on nanophase alumina. These results provided the first evidence of increased unfolding of vitronectin adsorbed on nanophase alumina. Increased adsorption of calcium on nanophase alumina may affect the conformation of adsorbed vitronectin specifically to promote unfolding of the macromolecule to expose cell-adhesive epitopes recognized by specific cell-membrane receptors. Results of the present study also provided evidence of dose-dependent inhibition of osteoblast adhesion on nanophase alumina pretreated with vitronectin following preincubation (and thus blocking respective cell-membrane receptors) with either Arginine-Glycine-Aspartic Acid-Serine (RGDS) or Lysine-Arginine-Serine-Arginine (KRSR). These events, namely, enhanced vitronectin adsorption, comformation, and bioactivity, may explain the increased osteoblast adhesion on nanophase alumina.

  12. Characterization of the coral allene oxide synthase active site with UV-visible absorption, magnetic circular dichroism, and electron paramagnetic resonance spectroscopy: evidence for tyrosinate ligation to the ferric enzyme heme iron.

    PubMed

    Abraham, B D; Sono, M; Boutaud, O; Shriner, A; Dawson, J H; Brash, A R; Gaffney, B J

    2001-02-20

    Coral allene oxide synthase (AOS), a hemoprotein with weak sequence homology to catalase, is the N-terminal domain of a naturally occurring fusion protein with an 8R-lipoxygenase. AOS converts 8R-hydroperoxyeicosatetraenoic acid to the corresponding allene oxide. The UV--visible absorption and magnetic circular dichroism spectra of ferric AOS and of its cyanide and azide complexes, and the electron paramagnetic resonance spectra of native AOS (high-spin, g = 6.56, 5.22, 2.00) and of its cyanide adduct (low-spin, g = 2.86, 2.24, 1.60) closely resemble the corresponding spectra of bovine liver catalase (BLC). These results provide strong evidence for tyrosinate ligation to the heme iron of AOS as has been established for catalases. On the other hand, the positive circular dichroism bands in the Soret region for all three derivatives of ferric AOS are almost the mirror image of those in catalase. In addition, the cyanide affinity of native AOS (K(d) = 10 mM at pH 7) is about 3 orders of magnitude lower than that of BLC. Thus, while these results conclusively support a common tyrosinate-ligated heme in AOS as in catalase, significant differences exist in the interaction between their respective heme prosthetic groups and protein environments, and in the access of small molecules to the heme iron. PMID:11329294

  13. Functionally Graded Nanophase Beryllium/Carbon Composites

    NASA Technical Reports Server (NTRS)

    Voronov, Oleg A.; Tompa, Gary S.

    2003-01-01

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

  14. Enhanced osteoclast-like cell functions on nanophase ceramics.

    PubMed

    Webster, T J; Ergun, C; Doremus, R H; Siegel, R W; Bizios, R

    2001-06-01

    Synthesis of tartrate-resistant acid phosphatase (TRAP) and formation of resorption pits by osteoclast-like cells, the bone-resorbing cells, on nanophase (that is, material formulations with grain sizes less than 100nm) alumina and hydroxyapatite (HA) were investigated in the present in vitro study. Compared to conventional (that is, grain sizes larger than 100 nm) ceramics, synthesis of TRAP was significantly greater in osteoclast-like cells cultured on nanophase alumina and on nanophase HA after 10 and 13 days, respectively. In addition, compared to conventional ceramics, formation of resorption pits was significantly greater by osteoclast-like cells cultured on nanophase alumina and on nanophase HA after 7, 10, and 13 days, respectively. The present study, therefore, demonstrated, for the first time, enhanced osteoclast-like cell function on ceramic surfaces with nanometer-size surface topography.

  15. Recognizing Sulfate and Phosphate Complexes Adsorbed onto Nanophase Weathering Products on Mars

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Morris, R. V.; Archer, P. D., Jr.

    2015-01-01

    Nanophase weathering products (i.e., secondary phases that lack long-range atomic order) have been recognized on the martian surface via orbital observations and in-situ measurements from landed missions. Allophane, a poorly crystalline, hydrated aluminosilicate, has been identified at the regional scale in models of thermal-infrared (TIR) data from the Thermal Emission Spectrometer (TES) and at the local scale from visible/near-IR (VNIR) data from the Compact Reconnaissance Impact Spectrometer for Mars (CRISM) instrument and phase calculations of Alpha Particle X-ray Spectrometer (APXS) data of rocks encountered by the Mars Exploration Rovers (MER) Spirit and Opportunity. Nanophase iron oxides (npOx) have been recognized in rocks and soils measured by the Mössbauer Spectrometer on Spirit and Opportunity. Furthermore, analyses of X-ray diffraction data measured by the CheMin instrument onboard the Mars Science Laboratory rover Curiosity indicate rock and soil samples are comprised of approx. 20-50 wt.% X-ray amorphous materials. Chemical measurements by landed missions indicate the presence of sulfur and phosphorus in martian rocks in soils, and APXS data from Gusev crater demonstrate abundances of up to approx. 5 wt.% P2O5 and approx. 30 wt.% SO3. However, the speciation of phosphorus and sulfur is not always evident. On Earth, phosphate and sulfate anions can be chemisorbed onto the surfaces of nanophase weathering products. This process may also occur on Mars, and calculations of the composition of the amorphous component at Gale crater using CheMin mineral models and APXS data show that amorphous material is enriched in volatiles, including S. Here, we examine the ability to detect chemisorbed sulfate and phosphate complexes by analyzing sulfate- and phosphate-adsorbed nanophase weathering products using instruments similar to those on landed and orbital missions.

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

    SciTech Connect

    Koretsky, Carla

    2013-11-29

    Hexavalent chromium is a highly toxic contaminant that has been introduced into aquifers and shallow sediments and soils via many anthropogenic activities. Hexavalent chromium contamination is a problem or potential problem in the shallow subsurface at several DOE sites, including Hanford, Idaho National Laboratory, Los Alamos National Laboratory and the Oak Ridge Reservation (DOE, 2008). To accurately quantify the fate and transport of hexavalent chromium at DOE and other contaminated sites, robust geochemical models, capable of correctly predicting changes in chromium chemical form resulting from chemical reactions occurring in subsurface environments are needed. One important chemical reaction that may greatly impact the bioavailability and mobility of hexavalent chromium in the subsurface is chemical binding to the surfaces of particulates, termed adsorption or surface complexation. Quantitative thermodynamic surface complexation models have been derived that can correctly calculate hexavalent chromium adsorption on well-characterized materials over ranges in subsurface conditions, such pH and salinity. However, models have not yet been developed for hexavalent chromium adsorption on many important constituents of natural soils and sediments, such as clay minerals. Furthermore, most of the existing thermodynamic models have been developed for relatively simple, single solid systems and have rarely been tested for the complex mixtures of solids present in real sediments and soils. In this study, the adsorption of hexavalent chromium was measured as a function of pH (3-10), salinity (0.001 to 0.1 M NaNO3), and partial pressure of carbon dioxide(0-5%) on a suite of naturally-occurring solids including goethite (FeOOH), hydrous manganese oxide (MnOOH), hydrous ferric oxide (Fe(OH)3), γ-alumina (Al2O3), kaolinite (Al2Si2O5(OH)4), and montmorillonite (Na3(Al, Mg)2Si4O10(OH)2-nH2O). The results show that all of these materials can bind substantial quantities of

  17. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1299 Ferric ferrocyanide. (a) Identity. (1) The color additive ferric ferrocyanide is a ferric hexacyanoferrate pigment characterized by the structual... ferrocyanide. (2) Color additive mixtures for drug use made with ferric ferrocyanide may contain only...

  18. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1299 Ferric ferrocyanide. (a) Identity. (1) The color additive ferric ferrocyanide is a ferric hexacyanoferrate pigment characterized by the structual... ferrocyanide. (2) Color additive mixtures for drug use made with ferric ferrocyanide may contain only...

  19. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1299 Ferric ferrocyanide. (a) Identity. (1) The color additive ferric ferrocyanide is a ferric hexacyanoferrate pigment characterized by the structual... ferrocyanide. (2) Color additive mixtures for drug use made with ferric ferrocyanide may contain only...

  20. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1299 Ferric ferrocyanide. (a) Identity. (1) The color additive ferric ferrocyanide is a ferric hexacyanoferrate pigment characterized by the structual... ferrocyanide. (2) Color additive mixtures for drug use made with ferric ferrocyanide may contain only...

  1. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... hydrogen chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ferric chloride. 184.1297 Section 184.1297 Food... Specific Substances Affirmed as GRAS § 184.1297 Ferric chloride. (a) Ferric chloride (iron (III)...

  2. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... hydrogen chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ferric chloride. 184.1297 Section 184.1297 Food... Specific Substances Affirmed as GRAS § 184.1297 Ferric chloride. (a) Ferric chloride (iron (III)...

  3. 21 CFR 184.1297 - Ferric chloride.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... hydrogen chloride. The pure material occurs as hydroscopic, hexagonal, dark crystals. Ferric chloride... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ferric chloride. 184.1297 Section 184.1297 Food... Specific Substances Affirmed as GRAS § 184.1297 Ferric chloride. (a) Ferric chloride (iron (III)...

  4. 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.

    PubMed

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

    2011-12-01

    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 allene epoxide, whereas the MAP protein is a putative organic peroxide-dependent peroxidase. To elucidate factors influencing the functions of these and related heme proteins, we have investigated the heme iron coordination properties of these tyrosinate-ligated heme enzymes in their ferric and ferrous states using magnetic circular dichroism and UV-visible absorption spectroscopy. The MAP protein shows remarkable spectral similarities to cAOS and BLC in its native Fe(III) state, but clear differences from ferric proximal heme ligand His93Tyr Mb (myoglobin) mutant, which may be attributed to the presence of an Arg(+)-N(ω)-H···¯O-Tyr (proximal heme axial ligand) hydrogen bond in the first three heme proteins. Furthermore, the spectra of Fe(III)-CN¯, Fe(III)-NO, Fe(II)-NO (except for five-coordinate MAP), Fe(II)-CO, and Fe(II)-O(2) states of cAOS and MAP, but not H93Y Mb, are also similar to the corresponding six-coordinate complexes of BLC, suggesting that a tyrosinate (Tyr-O¯) is the heme axial ligand trans to the bound ligands in these complexes. The Arg(+)-N(ω)-H to ¯O-Tyr hydrogen bond would be expected to modulate the donor properties of the proximal tyrosinate oxyanion and, combined with the subtle differences in the catalytic site structures, affect the activities of cAOS, MAP and BLC. PMID:22104301

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  6. Is superplasticity in the future of nanophase materials

    SciTech Connect

    Siegel, R.W.

    1990-07-01

    The ultrafine grain sizes and high diffusivities in nanophase materials assembled from atomic clusters suggest that these materials may have a strong tendency toward superplastic mechanical behavior. Both small grain size and enhanced diffusivity can be expected to lead to increased diffusional creep rates as well as to a significantly greater propensity for grain boundary sliding. Recent mechanical properties measurements at room temperature on nanophase Cu, Pd, and TiO{sub 2}, however, give no indications of superplasticity. Nonetheless, significant ductility has been clearly demonstrated in these studies of both nanophase ceramics and metals. The synthesis of cluster-assembled nanophase materials is described and the salient features of what is known of their structure and mechanical properties is reviewed. Finally, the answer to the question posed in the title is addressed. 34 refs., 6 figs.

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

    PubMed

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

    2008-01-01

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

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

    PubMed

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

    1995-09-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  10. Increased osteoblast function on PLGA composites containing nanophase titania.

    PubMed

    Webster, Thomas J; Smith, Tyler A

    2005-09-15

    Nanotechnology creates materials that potentially outperform, at several boundaries, existing materials in terms of mechanical, electrical, catalytic, and optical properties. However, despite their promise to mimic the surface roughness cells experience in vivo, the use of nanophase materials in biological applications remains to date largely unexplored. The objective of the present in vitro study was, therefore, to determine whether when added to a polymer scaffold, nanophase compared to conventional ceramics enhance functions of osteoblasts (or bone-forming cells). Results from this study provided the first evidence that functions (specifically, adhesion, synthesis of alkaline phosphatase, and deposition of calcium-containing mineral) of osteoblasts increased on poly-lactic-co-glycolic acid (PLGA) scaffolds containing nanophase compared to conventional grain size titania with greater weight percentage (from 10-30 wt %). Because the chemistry, material phase, porosity (%), and pore size of the composites were similar, this study implies that the surface features created by adding nanophase compared to conventional titania was a key parameter that enhanced functions of osteoblasts. In this manner, the study adds another novel property of nanophase ceramics: their ability to promote osteoblast functions in vitro when added to a polymer scaffold. For this reason, nanophase ceramics (and nanomaterials in general) deserve further attention as orthopedic tissue engineering materials.

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

    SciTech Connect

    1996-10-01

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

  12. Superhard nanophase materials for rock drilling applications

    SciTech Connect

    Sadangi, R.K.; Voronov, O.A.; Tompa, G.S.; Kear, B.H.

    1997-12-31

    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.

  13. Transparent monolithic metal ion containing nanophase aerogels

    SciTech Connect

    Risen, W. M., Jr.; Hu, X.; Ji, S.; Littrell, K.

    1999-12-01

    The formation of monolithic and transparent transition metal containing aerogels has been achieved through cooperative interactions of high molecular weight functionalized carbohydrates and silica precursors, which strongly influence the kinetics of gelation. After initial gelation, subsequent modification of the ligating character of the system, coordination of the group VIII metal ions, and supercritical extraction afford the aerogels. The structures at the nanophase level have been probed by photon and electron transmission and neutron scattering techniques to help elucidate the basis for structural integrity together with the small entity sizes that permit transparency in the visible range. They also help with understanding the chemical reactivities of the metal-containing sites in these very high surface area materials. These results are discussed in connection with new reaction studies.

  14. Effects of nanophase materials (< or = 20 nm) on biological responses.

    PubMed

    Cheng, Meng-Dawn

    2004-01-01

    Nanophase materials have enhanced properties (thermal, mechanical, electrical, surface reactivity, etc.) not found in bulk materials. Intuitively, the enhancement of material properties could occur when the materials encounter biological specimens. Previous investigations of biological interactions with nanometer-scale materials have been very limited. With the ability to manipulate atoms and molecules, we now can create predefined nanostructures with unprecedented precision. In parallel with this development, improved understanding of the biological effects of the nanophase materials, whatever those may be, should also deserve attention. In this study, we have applied precision aerosol technology to investigate cellular response to nanoparticles. We used synthetic nanoparticles generated by an electrospray technique to produce nanoparticles in the size range of 8-13 nm with practically monodispersed aerosol particles and approximately the same number concentration. We report here on the potency of nano-metal particles with single or binary chemical components in eliciting interleukin-8 (IL-8) production from epithelial cell lines. For single-component nanoparticles, we found that nano-Cu particles were more potent in IL-8 production than nano-Ni and nano-V particles. However, the kinetics of IL-8 production by these three nanoparticles was different, the nano-Ni being the highest among the three. When sulfuric acid was introduced to form acidified nano-Ni particles, we found that the potency of such binary-component nanoparticles in eliciting IL-8 production was increased markedly, by about six times. However, the acidified binary nano-Na and -Mg nanoparticles did not exhibit the same effects as binary nano-Ni particles did. Since Ni, a transition metal, could induce free radicals on cell surfaces, while Na and Mg could not, the acidity might have enhanced the oxidative stress caused by radicals to the cells, leading to markedly higher IL-8 production. This result

  15. 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...

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

    PubMed

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

    2012-10-16

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

  17. 21 CFR 582.5301 - Ferric phosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  18. 21 CFR 582.5304 - Ferric pyrophosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use....

  19. 21 CFR 582.5304 - Ferric pyrophosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use....

  20. 21 CFR 582.5301 - Ferric phosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  1. 21 CFR 582.5301 - Ferric phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  2. 21 CFR 582.5301 - Ferric phosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  3. 21 CFR 582.5304 - Ferric pyrophosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use....

  4. 21 CFR 582.5301 - Ferric phosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  5. 21 CFR 582.5304 - Ferric pyrophosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use....

  6. 21 CFR 582.5304 - Ferric pyrophosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use....

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

    SciTech Connect

    Tushar K Ghosh

    2008-10-13

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

  8. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Specific Substances Affirmed as GRAS § 184.1301 Ferric phosphate. (a) Ferric phosphate (ferric orthophosphate, iron (III) phosphate, FePO4·xH2O, CAS Reg. No. 10045-86-0) is an odorless, yellowish-white to... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ferric phosphate. 184.1301 Section 184.1301...

  9. Specific proteins mediate enhanced osteoblast adhesion on nanophase ceramics.

    PubMed

    Webster, T J; Ergun, C; Doremus, R H; Siegel, R W; Bizios, R

    2000-09-01

    Osteoblast, fibroblast, and endothelial cell adhesion on nanophase (that is, materials with grain sizes less than 100 nm) alumina, titania, and hydroxyapatite (HA) was investigated using in vitro cellular models. Osteoblast adhesion was significantly (p < 0.01) greater after 4 h on nanophase alumina, titania, and HA than it was on conventional formulations of the same ceramics. In contrast, compared to conventional alumina, titania, and HA, after 4 h fibroblast adhesion was significantly (p < 0.01) less on nanophase ceramics. Examination of the underlying mechanism(s) of cell adhesion on nanophase ceramics revealed that these ceramics adsorbed significantly (p < 0.01) greater quantities of vitronectin, which, subsequently, may have contributed to the observed select enhanced adhesion of osteoblasts. Select enhanced osteoblast adhesion was independent of surface chemistry and material phase but was dependent on the surface topography (specifically on grain and pore size) of nanophase ceramics. The capability of synthesizing and processing nanomaterials with tailored (through, for example, specific grain and pore size) structures and topographies to control select subsequent cell functions provides the possibility of designing the novel proactive biomaterials (that is, materials that elicit specific, timely, and desirable responses from surrounding cells and tissues) necessary for improved implant efficacy.

  10. Superhard nanophase cutter materials for rock drilling applications

    SciTech Connect

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

    2000-06-23

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

  11. The Center for Nanophase Materials Sciences

    NASA Astrophysics Data System (ADS)

    Lowndes, Douglas

    2005-03-01

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

  12. Direct formation of nanophase hydroxyapatite on cathodically polarized electrodes.

    PubMed

    Shirkhanzadeh, M

    1998-02-01

    Ultrafine-grained, nanophase coatings of hydroxyapatite were synthesized by electrocrystallization from dilute electrolytes ([Ca]=6.1 x 10-4 M, [phosphate]=3.6 x 10-4 M) at pH values comparable with the biological pH. At these comparatively low supersaturations, hydroxyapatite is shown to be precipitated without the formation of a precursor phase. A description of the sequence of events occurring at the electrode-electrolyte interface is given to explain the mechanism involved in the direct formation of nanophase hydroxyapatite on polarized electrodes.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

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

    SciTech Connect

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

    2005-01-01

    The conventional copper electrowinning process uses the water hydrolysis reaction as the anodic source of electrons. However this reaction generates acid mist and requires large quantities of energy. In order to improve energy efficiency and avoid acid mist, an alternative anodic reaction of ferrous ion oxidation has been proposed. This reaction does not involve evolution of acid mist and can be carried out at a lower cell voltage than the conventional process. However, because ferrous ions are converted to ferric ions at the anode in this process, there is a need for reduction of ferric ions to ferrous ions to continue this process. The most promising method for this reduction is the use of hydrogen gas since the resulting byproduct acid can be used elsewhere in the process and, unlike other reductants, hydrogen does not introduce other species that need subsequent removal. Because the hydrogen reduction technology has undergone only preliminary lab scale testing, additional research is needed to evaluate its commercial potential. Two issues for this research are the potentially low mass transfer rate of hydrogen into the electrolyte stream because of its low solubility in water, and whether other gaseous reductants less expensive than hydrogen, such as natural gas or syngas, might work. In this study various reductants were investigated to carry out the reduction of ferric ions to ferrous ions using a simulated electrolyte solution recycled through a trickle bed reactor packed with catalyst. The gases tested as reductants were hydrogen, methane, carbon monoxide, and a 50/50 mixture of H2 and CO. Nitrogen was also tested as an inert control. These gases were tested because they are constituents in either natural gas or syngas. The catalysts tested were palladium and platinum. Two gas flow rates and five electrolyte flow rates were tested. Pure hydrogen was an effective reductant of ferric ion. The rates were similar with both palladium and platinum. The ferric

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

    DOEpatents

    Atcher, Robert W.; Hines, John J.

    1992-01-01

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

  16. 21 CFR 184.1298 - Ferric citrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ferric citrate. 184.1298 Section 184.1298 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD... prepared from reaction of citric acid with ferric hydroxide. It is a compound of indefinite ratio of...

  17. 21 CFR 184.1304 - Ferric pyrophosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... colorless powder. It is prepared by reacting sodium pyrophosphate with ferric citrate. (b) The ingredient... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ferric pyrophosphate. 184.1304 Section 184.1304 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED)...

  18. Hydrolysis of ferric chloride in solution

    SciTech Connect

    Lussiez, G.; Beckstead, L.

    1996-11-01

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

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

    PubMed

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

    2008-01-01

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

  20. Ferric sulfate montmorillonites as Mars soil analogs

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Pieters, C. M.; Burns, R. G.

    1993-01-01

    Spectroscopic analyses have shown that Fe(3+)-doped smectites prepared in the laboratory exhibit important similarities to the soils on Mars. Ferrihydrite in these smectites has features in the visible to near-infrared region that resemble the energies and band-strengths of features in reflectance spectra observed for several bright regions on Mars. Ferric - sulfate - montmorillonite samples have been prepared more recently because they are a good compositional match with the surface material on Mars as measured by Viking. Reflectance spectra of montmorillonite doped with ferric sulfate in the interlayer regions include a strong 3 micron band that persists under dry conditions. This is in contrast to spectra of similarly prepared ferric-doped montmorillonites, which exhibit a relatively weaker 3 micron band under comparable dry environmental conditions. Presented here are reflectance spectra of a suite of ferric-sulfate exchanged montmorillonites prepared with variable ferric sulfate concentrations and variable pH conditions.

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

    PubMed

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

    2006-04-20

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

  2. An investigation of carbonaceous materials reducing ferric ions in aqueous solution

    NASA Astrophysics Data System (ADS)

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

    1988-10-01

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

  3. Nanophase Nickel-Zirconium Alloys for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram; Whitacre, jay; Valdez, Thomas

    2008-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  6. A purple acidophilic di-ferric DNA ligase from Ferroplasma.

    PubMed

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

    2008-07-01

    We describe here an extraordinary purple-colored DNA ligase, LigFa, from the acidophilic ferrous iron-oxidizing archaeon Ferroplasma acidiphilum, a di-ferric enzyme with an extremely low pH activity optimum. Unlike any other DNA ligase studied to date, LigFa contains two Fe(3+)-tyrosinate centers and lacks any requirement for either Mg(2+) or K(+) for activity. DNA ligases from closest phylogenetic and ecophysiological relatives have normal pH optima (6.0-7.5), lack iron, and require Mg(2+)/K(+) for activity. Ferric iron retention is pH-dependent, with release resulting in partial protein unfolding and loss of activity. Reduction of the Fe(3+) to Fe(2+) results in an 80% decrease in DNA substrate binding and an increase in the pH activity optimum to 5.0. DNA binding induces significant conformational change around the iron site(s), suggesting that the ferric irons of LigFa act both as structure organizing and stabilizing elements and as Lewis acids facilitating DNA binding at low pH.

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

    PubMed

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

    2005-07-01

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

  8. 21 CFR 184.1298 - Ferric citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Reg. No. 2338-05-8) is prepared from reaction of citric acid with ferric hydroxide. It is a compound of indefinite ratio of citric acid and iron. (b) The ingredient must be of a purity suitable for...

  9. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2299 Ferric ferrocyanide. (a) Identity and... coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in...

  10. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2299 Ferric ferrocyanide. (a) Identity and... coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in...

  11. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2299 Ferric ferrocyanide. (a) Identity and... coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in...

  12. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2299 Ferric ferrocyanide. (a) Identity and... coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in...

  13. 21 CFR 73.2299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2299 Ferric ferrocyanide. (a) Identity and... coloring externally applied cosmetics, including cosmetics applied to the area of the eye, in...

  14. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ferric ammonium citrate. 184.1296 Section 184.1296... Listing of Specific Substances Affirmed as GRAS § 184.1296 Ferric ammonium citrate. (a) Ferric ammonium citrate (iron (III) ammonium citrate) is prepared by the reaction of ferric hydroxide with citric...

  15. The leaching of chalcopyrite with ferric sulfate

    NASA Astrophysics Data System (ADS)

    Hirato, Tetsuji; Majima, Hiroshi; Awakura, Yasuhiro

    1987-09-01

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

  16. Top-down approach for nanophase reconstruction in bulk heterojunction solar cells.

    PubMed

    Kong, Jaemin; Hwang, In-Wook; Lee, Kwanghee

    2014-09-01

    "Top-Down" nanophase reconstruction via a post-additive soaking process is first presented with various BHJ binary composites. By simply rinsing as-cast BHJ films with a solvent mixture containing a few traces of a nanophase-control reagent such as 1,8-diiodooctane, oversized fullerene-rich clusters (>100 nm in dia-meter) in the BHJ film are instataneously disassembled and entirely reorganized into finely intermixed donor/acceptor nanophases (ca. 10 nm) with a 3D compositional homogeneity, without surface segregation.

  17. Ferric chloride graphite intercalation compounds prepared from graphite fluoride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1994-01-01

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

  18. Synthesis and phase transformations involving scorodite, ferric arsenate and arsenical ferrihydrite: Implications for arsenic mobility

    NASA Astrophysics Data System (ADS)

    Paktunc, Dogan; Dutrizac, John; Gertsman, Valery

    2008-06-01

    Scorodite, ferric arsenate and arsenical ferrihydrite are important arsenic carriers occurring in a wide range of environments and are also common precipitates used by metallurgical industries to control arsenic in effluents. Solubility and stability of these compounds are controversial because of the complexities in their identification and characterization in heterogeneous media. To provide insights into the formation of scorodite, ferric arsenate and ferrihydrite, series of synthesis experiments were carried out at 70 °C and pH 1, 2, 3 and 4.5 from 0.2 M Fe(SO 4) 1.5 solutions also containing 0.02-0.2 M Na 2HAsO 4. The precipitates were characterized by transmission electron microscopy, X-ray diffraction and X-ray absorption fine structure techniques. Ferric arsenate, characterized by two broad diffuse peaks on the XRD pattern and having the structural formula of FeAsO 4·4-7H 2O, is a precursor to scorodite formation. As defined by As XAFS and Fe XAFS, the local structure of ferric arsenate is profoundly different than that of scorodite. It is postulated that the ferric arsenate structure is made of single chains of corner-sharing Fe(O,OH) 6 octahedra with bridging arsenate tetrahedra alternating along the chains. Scorodite was precipitated from solutions with Fe/As molar ratios of 1 over the pH range of 1-4.5. The pH strongly controls the kinetics of scorodite formation and its transformation from ferric arsenate. The scorodite crystallite size increased from 7 to 33 nm by ripening and aggregation. Precipitates, resulting from continuous synthesis at pH 4.5 from solutions having Fe/As molar ratios ranging from 1 to 4 and resembling the compounds referred to as ferric arsenate, arsenical ferrihydrite and As-rich hydrous ferric oxide in the literature, represent variable mixtures of ferric arsenate and ferrihydrite. When the Fe/As ratio increases, the proportion of ferrihydrite increases at the expense of ferric arsenate. Arsenate adsorption appears to retard

  19. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Ferric ferrocyanide. 73.1299 Section 73.1299 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF... diluents listed in this subpart as safe and suitable for use in color additive mixtures for coloring...

  20. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ferric phosphate. 184.1301 Section 184.1301 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed...

  1. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ferric phosphate. 184.1301 Section 184.1301 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing...

  2. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ferric phosphate. 184.1301 Section 184.1301 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing...

  3. 21 CFR 184.1298 - Ferric citrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ferric citrate. 184.1298 Section 184.1298 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of...

  4. 21 CFR 184.1298 - Ferric citrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ferric citrate. 184.1298 Section 184.1298 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of...

  5. 21 CFR 184.1298 - Ferric citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ferric citrate. 184.1298 Section 184.1298 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of...

  6. 21 CFR 184.1301 - Ferric phosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ferric phosphate. 184.1301 Section 184.1301 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing...

  7. Biocompatibility of poly(carbonate urethane)s with various degrees of nanophase separation.

    PubMed

    Hsu, Shan-Hui; Kao, Yu-Chih

    2005-03-15

    Nanophase separation has been suggested to influence the biological performance of polyurethane. In a previous work, six different 4,4'-diphenylmethane diisocyanate (MDI)-based poly(carbonate urethane)s (PCUs) that exhibited various degrees of nanophase separation were synthesized and characterized. In the present work, these PCUs were used as a model system to study the effect of nanometric structures on the biocompatibility of polyurethane. Human blood platelet activation, monocyte activation, protein adsorption, and bacterial adhesion on PCU were investigated in vitro. It was found that human blood platelets as well as monocytes were less activated on the PCU surfaces with a greater degree of nanophase separation in general. This phenomenon was closely associated with the lower ratio of human fibrinogen/albumin competitively adsorbed on these surfaces. Bacterial adhesion was also inhibited in some nanophase-separated PCUs. [diagram in text].

  8. Synthesis and cellular biocompatibility of two nanophase hydroxyapatite with different Ca/P ratio.

    PubMed

    Zhao, Yantao; Zhang, Yumei; Zhao, Yimin; Hou, Shuxun; Chu, Paul K

    2011-12-01

    The cellular biocompatibility of two types of nanophase hydroxyapatites including nanophase standard hydroxyapatite (n-HA) and nanophase calcium deficient hydroxyapatite (n-CDHA) synthesized by a wet chemical method were assessed using primary cultured osteoblasts. Cytotoxicity of both materials was investigated with L929 cell line. The MTT method was used to evaluate the proliferation of osteoblasts on the third day and ALP activity assay was carried out on the fifth day. SEM was used to observe the morphology of the osteoblasts on the third day. Two types of nanophase hydroxyapatite both showed no cytotoxicity. Higher cell proliferation was observed on n-CDHA than n-HA. At the same time, cells spread more actively on the n-CDHA group. The ALP level of n-CDHA was also significantly higher on the former. Our results show that the n-CDHA is more suitable for osteoblasts growth and is also helpful for ALP synthesis.

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

    PubMed

    Kosman, Daniel J

    2013-01-01

    Aerobes and anaerobes alike express a plethora of essential iron enzymes; in the resting state, the iron atom(s) in these proteins are in the ferrous state. For aerobes, ferric iron is the predominant environmental valence form which, given ferric iron's aqueous chemistry, occurs as 'rust', insoluble, bio-inert polymeric ferric oxide that results from the hydrolysis of [Fe(H(2)O)(6)](3+). Mobilizing this iron requires bio-ferrireduction which in turn requires managing the rapid autoxidation of the resulting Fe(II) which occurs at pH > 6. This review examines the aqueous redox chemistry of iron and the mechanisms evolved in aerobes to suppress the 'rusting out' of Fe(III) and the ROS-generating autoxidation of Fe(II) so as to make this metal ion available as the most ubiquitous prosthetic group in metallobiology. PMID:23264695

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

    PubMed

    Jadhav, Umesh U; Hocheng, Hong

    2014-01-01

    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

  11. 21 CFR 73.1025 - Ferric ammonium citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... color additive ferric ammonium citrate consists of complex chelates prepared by the interaction of ferric hydroxide with citric acid in the presence of ammonia. The complex chelates occur in brown...

  12. 21 CFR 582.5306 - Ferric sodium pyrophosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Dietary Supplements 1 § 582.5306 Ferric sodium pyrophosphate. (a) Product. Ferric sodium pyrophosphate....

  13. [Experimental research on the effect of nanophase ceramics on osteoblasts functions].

    PubMed

    Wen, Bo; Chen, Zhiqing; Jiang, Yinshan; Yang, Zhengwen; Xu, Yongzhong

    2005-06-01

    In order to study the cytocompatibility of nanophase hydroxyapatite ceramic in vitro, we prepared hydroxyapatite by use of the wet chemistry techniques. The grain size of hydroxyapatite of interest to the present study was determined by scanning electron microscopy and atomic force microscopy with image analysis software. Primary culture of osteoblast from rat calvaria was established. Protein content, synthesis of alkaline phosphatase and deposition of calcium-containing mineral by osteoblasts cultured on nanophase hydroxyapatite ceramics and on conventional hydroxyapatite ceramics for 7, 14, 21 and 28 days were examined. The results showed that the average surface grain size of the nanophase and that of the conventional HA compact formulations was 55 (nanophase) and 780 (conventional) nm, respectively. More importantly, compared to the synthesis of alkaline phosphatase and deposition of calcium-containing mineral by osteoblasts cultured on nanophase was significantly greater than that on conventional ceramics after 21 and 28 days. The cytocompatibility was significantly greater on nanophase HA than on conventional formulations of the same ceramic.

  14. Modeling ferrous ferric iron chemistry with application to martian surface geochemistry

    NASA Astrophysics Data System (ADS)

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

    2008-01-01

    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

  15. Temperature sensitive copolymer microgels with nanophase separated structure.

    PubMed

    Keerl, Martina; Pedersen, Jan Skov; Richtering, Walter

    2009-03-01

    Small-angle neutron scattering data from a thermosensitive copolymer microgel consisting of N-isopropylacrylamide (PNIPAM) and N-isopropylmethacrylamide (PNIPMAM regions) were analyzed using a new form factor model. The neutron scattering data display an exceptional shape of the scattering curve at the transition temperature of the microgel indicating an additional characteristic length scale inside the microgel. A new form factor model with a nanophase separated internal morphology was derived which describes the experimental scattering very well. At the transition temperature of the copolymer, which is in between the transition temperatures of the two components, the copolymer microgel particles consist of collapsed PNIPAM domains and swollen PNIPMAM regions. The results demonstrate that a one-pot synthesis can lead to a highly sophisticated material with phase separated domains on a microscopic length scale.

  16. Recent advances in research applications of nanophase hydroxyapatite.

    PubMed

    Fox, Kate; Tran, Phong A; Tran, Nhiem

    2012-07-16

    Hydroxyapatite, the main inorganic material in natural bone, has been used widely for orthopaedic applications. Due to size effects and surface phenomena at the nanoscale, nanophase hydroxyapatite possesses unique properties compared to its bulk-phase counterpart. The high surface-to-volume ratio, reactivities, and biomimetic morphologies make nano-hydroxyapatite more favourable in applications such as orthopaedic implant coating or bone substitute filler. Recently, more efforts have been focused on the possibility of combining hydroxyapatite with other drugs and materials for multipurpose applications, such as antimicrobial treatments, osteoporosis treatments and magnetic manipulation. To build more effective nano-hydroxyapatite and composite systems, the particle synthesis processes, chemistry, and toxicity have to be thoroughly investigated. In this Minireview, we report the recent advances in research regarding nano-hydroxyapatite. Synthesis routes and a wide range of applications of hydroxyapatite nanoparticles will be discussed. The Minireview also addresses several challenges concerning the biosafety of the nanoparticles.

  17. Nanophase bone substitute in vivo response to subcutaneous implantation.

    PubMed

    Baskin, Jonathan Z; Vasanji, Amit; McMasters, James; Soenjaya, Yohannes; Barbu, Anca M; Eppell, Steven J

    2012-09-01

    A collagen-apatite composite designed as a load-bearing bone substitute implant is used to characterize the relationship between implant morphology and in vivo behavior. This nanophase bone substitute (NBS) is studied morphologically using a nondestructive imaging technique and biologically using the rodent subcutaneous model. Porosity and pore interconnectivity are correlated with histological outcomes showing cellular invasion occurs with average pore sizes below 100 μm. Crosslinking with D-ribose is shown to affect cellular infiltration in a dose-response manner. These data suggest that collagen-apatite bone substitutes can support cellular infiltration with pore size significantly smaller than 100 μm, an encouraging result regarding development of the NBS into a platform of biomaterials with enhanced mechanical properties. The data also indicate that increasing crosslinking density decreases cellular infiltration of NBS. Thus, modulating mechanical properties of the material by altering crosslink density is likely to produce decreased biological response within the material.

  18. Arsenic removal from acidic solutions with biogenic ferric precipitates.

    PubMed

    Ahoranta, Sarita H; Kokko, Marika E; Papirio, Stefano; Özkaya, Bestamin; Puhakka, Jaakko A

    2016-04-01

    Treatment of acidic solution containing 5g/L of Fe(II) and 10mg/L of As(III) was studied in a system consisting of a biological fluidized-bed reactor (FBR) for iron oxidation, and a gravity settler for iron precipitation and separation of the ferric precipitates. At pH 3.0 and FBR retention time of 5.7h, 96-98% of the added Fe(II) precipitated (99.1% of which was jarosite). The highest iron oxidation and precipitation rates were 1070 and 28mg/L/h, respectively, and were achieved at pH 3.0. Subsequently, the effect of pH on arsenic removal through sorption and/or co-precipitation was examined by gradually decreasing solution pH from 3.0 to 1.6 (feed pH). At pH 3.0, 2.4 and 1.6, the highest arsenic removal efficiencies obtained were 99.5%, 80.1% and 7.1%, respectively. As the system had ferric precipitates in excess, decreased arsenic removal was likely due to reduced co-precipitation at pH<2.4. As(III) was partially oxidized to As(V) in the system. In shake flask experiments, As(V) sorbed onto jarosite better than As(III). Moreover, the sorption capacity of biogenic jarosite was significantly higher than that of synthetic jarosite. The developed bioprocess simultaneously and efficiently removes iron and arsenic from acidic solutions, indicating potential for mining wastewater treatment. PMID:26705889

  19. Understanding Arsenate Reaction Kinetics with Ferric Hydroxides

    PubMed Central

    Farrell, James; Chaudhary, Binod K.

    2015-01-01

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

  20. High Strain Rate Response of Sandwich Composites with Nanophased Cores

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

    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.

  1. Desilication from DWPF Recycle using Ferric Flocculation

    SciTech Connect

    Wilmarth, W.R.

    2002-10-24

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

  2. Ferric iron reduction and iron assimilation in Saccharomyces cerevisiae.

    PubMed

    Anderson, G J; Lesuisse, E; Dancis, A; Roman, D G; Labbe, P; Klausner, R D

    We have used the yeast Saccharomyces cerevisiae as a model organism to study the role of ferric iron reduction in eucaryotic iron uptake. S. cerevisiae is able to utilize ferric chelates as an iron source by reducing the ferric iron to the ferrous form, which is subsequently internalized by the cells. A gene (FRE1) was identified which encodes a protein required for both ferric iron reduction and efficient ferric iron assimilation, thus linking these two activities. The predicted FRE1 protein appears to be a membrane protein and shows homology to the beta-subunit of the human respiratory burst oxidase. These data suggest that FRE1 is a structural component of the ferric reductase. Subcellular fractionation studies showed that the ferric reductase activity of isolated plasma membranes did not reflect the activity of the intact cells, implying that cellular integrity was necessary for function of the major S. cerevisiae ferric reductase. An NADPH-dependent plasma membrane ferric reductase was partially purified from plasma membranes. Preliminary evidence suggests that the cell surface ferric reductase may, in addition to mediating cellular iron uptake, help modulate the intracellular redox potential of the yeast cell.

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

    PubMed

    Webster, Thomas J; Ejiofor, Jeremiah U

    2004-08-01

    Previous studies have demonstrated increased functions of osteoblasts (bone-forming cells) on nanophase compared to conventional ceramics (specifically, alumina, titania, and hydroxyapatite), polymers (such as poly lactic-glycolic acid and polyurethane), carbon nanofibers/nanotubes, and composites thereof. Nanophase materials are unique materials that simulate dimensions of constituent components of bone since they possess particle or grain sizes less than 100 nm. However, to date, interactions of osteoblasts on nanophase compared to conventional metals remain to be elucidated. For this reason, the objective of the present in vitro study was to synthesize, characterize, and evaluate osteoblast adhesion on nanophase metals (specifically, Ti, Ti6Al4V, and CoCrMo alloys). Such metals in conventional form are widely used in orthopedic applications. Results of this study provided the first evidence of increased osteoblast adhesion on nanophase compared to conventional metals. Interestingly, osteoblast adhesion occurred preferentially at surface particle boundaries for both nanophase and conventional metals. Since more particle boundaries are present on the surface of nanophase compared to conventional metals, this may be an explanation for the measured increased osteoblast adhesion. Lastly, material characterization studies revealed that nanometal surfaces possessed similar chemistry and only altered in degree of nanometer surface roughness when compared to their respective conventional counterparts. Because osteoblast adhesion is a necessary prerequisite for subsequent functions (such as deposition of calcium-containing mineral), the present study suggests that nanophase metals should be further considered for orthopedic implant applications.

  4. Increased viable osteoblast density in the presence of nanophase compared to conventional alumina and titania particles.

    PubMed

    Gutwein, Luke G; Webster, Thomas J

    2004-08-01

    In the present in vitro study, osteoblast (bone-forming cells) viability and cell density were investigated when cultured in the presence of nanophase compared to conventional (i.e. micron) alumina and titania particles at various concentrations (from 10,000 to 100 microg/ml of cell culture media) for up to 6h. Results confirmed previous studies of the detrimental influences of all ceramic particulates on osteoblast viability and cell densities. For the first time, however, results provided evidence of increased apoptotic cell death when cultured in the presence of conventional compared to nanophase alumina and titania particles. Moreover, since material characterization studies revealed that the only difference between respective ceramic particles was nanometer- and conventional-dimensions (specifically, phase and chemical properties were similar between respective nanophase and conventional alumina as well as titania particles), these results indicated that osteoblast viability and densities were influenced solely by particle size. Such nanometer particulate wear debris may result from friction between articulating components of orthopedic implants composed of novel nanophase ceramic materials. Results of a less detrimental effect of nanometer--as compared to conventional-dimensioned particles on the functions of osteoblasts provide additional evidence that nanophase ceramics may become the next generation of bone prosthetic materials with increased efficacy and, thus, deserve further testing.

  5. Cell attachment and proliferation on poly(carbonate urethanes) with various degrees of nanophase separation.

    PubMed

    Hsu, Shan-hui; Kao, Yu-Chih

    2004-09-16

    In this work, we synthesized six 4,4'-diphenylmethane diisocyanate (MDI)-based poly(carbonate urethanes) (PCU) by using the macrodiol poly(1,6-hexyl, 1,2-ethyl carbonate) diol (MW = 2,017) in different molar ratios to MDI. The bulk and surface properties of cast PCU films were analyzed. The glass transition temperatures measured by dynamic mechanical analysis (DMA) and surface images obtained from atomic force microscopy (AFM) indicated that these PCU had various degrees of nanophase separation that changed with the time and film casting temperatures. The degree of nanophase separation correlated very well with endothelial cell attachment and proliferation on PCU.

  6. Nanophase hydroxyapatite as a biomaterial in advanced hard tissue engineering: a review.

    PubMed

    Zakaria, Siti Maisurah; Sharif Zein, Sharif Hussein; Othman, Mohd Roslee; Yang, Fang; Jansen, John A

    2013-10-01

    Hydroxyapatite is a biocompatible material that is extensively used in the replacement and regeneration of bone material. In nature, nanostructured hydroxyapatite is the main component present in hard body tissues. Hence, the state of the art in nanotechnology can be exploited to synthesize nanophase hydroxyapatite that has similar properties with natural hydroxyapatite. Sustainable methods to mass-produce synthetic hydroxyapatite nanoparticles are being developed to meet the increasing demand for these materials and to further develop the progress made in hard tissue regeneration, especially for orthopedic and dental applications. This article reviews the current developments in nanophase hydroxyapatite through various manufacturing techniques and modifications.

  7. Structural, morphological, magnetic and dielectric characterization of nano-phased antimony doped manganese zinc ferrites

    NASA Astrophysics Data System (ADS)

    Sridhar, Ch. S. L. N.; Lakshmi, Ch. S.; Govindraj, G.; Bangarraju, S.; Satyanarayana, L.; Potukuchi, D. M.

    2016-05-01

    Nano-phased doped Mn-Zn ferrites, viz., Mn0.5-x/2Zn0.5-x/2SbXFe2O4 for x=0 to 0.3 (in steps of 0.05) prepared by hydrothermal method are characterized by X-ray diffraction, Infrared and scanning electron microscopy. XRD and SEM infer the growth of nano-crystalline cubic and hematite (α-Fe2O3) phase structures. IR reveals the ferrite phase abundance and metal ion replacement with dopant. Decreasing trend of lattice constant with dopant reflects the preferential replacement of Fe3+ions by Sb5+ion. Doping is found to cause for the decrease (i.e., 46-14 nm) of grain size. An overall trend of decreasing saturation magnetization is observed with doping. Low magnetization is attributed to the diamagnetic nature of dopant, abundance of hematite (α-Fe2O3) phase, non-stoichiometry and low temperature (800 °C) sintering conditions. Increasing Yafet-Kittel angle reflects surface spin canting to pronounce lower Ms. Lower coercivity is observed for x≤0.1, while a large Hc results for higher concentrations. High ac resistivity (~106 ohm-cm) and low dielectric loss factor (tan δ~10-2-10-3) are witnessed. Resistivity is explained on the base of a transformation in the Metal Cation-to-Oxide anion bond configuration and blockade of conductivity path. Retarded hopping (between adjacent B-sites) of carriers across the grain boundaries is addressed. Relatively higher resistivity and low dielectric loss in Sbdoped Mn-Zn ferrite systems pronounce their utility in high frequency applications.

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

    PubMed Central

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

    1987-01-01

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

  9. 21 CFR 73.1025 - Ferric ammonium citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Ferric ammonium citrate. 73.1025 Section 73.1025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF... color additive ferric ammonium citrate consists of complex chelates prepared by the interaction...

  10. 21 CFR 73.1025 - Ferric ammonium citrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Ferric ammonium citrate. 73.1025 Section 73.1025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF... color additive ferric ammonium citrate consists of complex chelates prepared by the interaction...

  11. 21 CFR 73.1025 - Ferric ammonium citrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Ferric ammonium citrate. 73.1025 Section 73.1025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF... color additive ferric ammonium citrate consists of complex chelates prepared by the interaction...

  12. 21 CFR 73.1025 - Ferric ammonium citrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Ferric ammonium citrate. 73.1025 Section 73.1025 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF... color additive ferric ammonium citrate consists of complex chelates prepared by the interaction...

  13. 21 CFR 582.5306 - Ferric sodium pyrophosphate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5306 Ferric...

  14. 46 CFR 151.50-75 - Ferric chloride solution.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Ferric chloride solution. 151.50-75 Section 151.50-75... CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-75 Ferric chloride solution... solution must be lined with rubber, corrosion resistant plastic, or a material approved by the...

  15. 46 CFR 151.50-75 - Ferric chloride solution.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Ferric chloride solution. 151.50-75 Section 151.50-75... CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-75 Ferric chloride solution... solution must be lined with rubber, corrosion resistant plastic, or a material approved by the...

  16. Energy transduction by anaerobic ferric iron respiration in Thiobacillus ferrooxidans

    SciTech Connect

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

    1991-07-01

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

  17. Spectrophotometric ferric ion biosensor from Pseudomonas fluorescens culture.

    PubMed

    Gupta, Varun; Saharan, Krishna; Kumar, Lalit; Gupta, Roohi; Sahai, Vikram; Mittal, Aditya

    2008-06-01

    Pseudomonas fluorescens cultures produce fluorescent siderophores. By utilizing optimal conditions for maximizing siderophore production in shake flask cultures of P. fluorescens, we report successful characterization of the culture broth supernatant as a robust ferric ions biosensor. For characterizing the ferric ions biosensor, we tested the effects of pH, buffers, different ferric salts and possible interference by ferrous ions under different solution conditions. We find that the biosensor is very specific to ferric ions only with sensitivity to concentrations as low as 10 microM. Further, the response time of the biosensor is the shortest (approximately 5 min or smaller) for citrate as the accompanying anion with ferric ions. While the response time is longer than that expected of normal biosensors, it is well compensated by the simplicity and economics of the biosensor production. Extremely low standard deviations in several experimental repeats also highlight the robustness of the ferric ions biosensor. Most importantly, the biosensor is extremely easy to use due to its straightforward spectrophotometric applications. We also show the utility of the biosensor with the high resolution technique of fluorescence microscopy. Finally, we report a novel mechanistic finding that siderophores present in the culture broth supernatants have two distinct optically active sites on them, which can be monitored independently in presence or absence of ferric ions. PMID:18080345

  18. Nanophase hydroxyapatite coatings for dental and orthopedic applications

    NASA Astrophysics Data System (ADS)

    Sato, Michiko

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

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    PubMed

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

    2015-04-01

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

  1. Potential Role for Extracellular Glutathione-Dependent Ferric Reductase in Utilization of Environmental and Host Ferric Compounds by Histoplasma capsulatum

    PubMed Central

    Timmerman, Michelle M.; Woods, Jon P.

    2001-01-01

    The mammalian host specifically limits iron during Histoplasma capsulatum infection, and fungal acquisition of iron is essential for productive infection. H. capsulatum expresses several iron acquisition mechanisms under iron-limited conditions in vitro. These components include hydroxamate siderophores, extracellular glutathione-dependent ferric reductase enzyme, extracellular nonproteinaceous ferric reductant(s), and cell surface ferric reducing agent(s). We examined the relationship between these mechanisms and a potential role for the extracellular ferric reductase in utilization of environmental and host ferric compounds through the production of free, soluble Fe(II). Siderophores and ferric reducing agents were coproduced under conditions of iron limitation. The H. capsulatum siderophore dimerum acid and the structurally similar basidiomycete siderophore rhodotorulic acid acted as substrates for the ferric reductase, and rhodotorulic acid removed Fe(III) bound by transferrin. The mammalian Fe(III)-binding compounds hemin and transferrin served both as substrates for the ferric reductase and as iron sources for yeast-phase growth at neutral pH. In the case of transferrin, there was a correlation between the level of iron saturation and efficacy for both of these functions. Our data are not consistent with an entirely pH-dependent mechanism of iron acquisition from transferrin, as has been suggested to occur in the macrophage phagolysosome. The foreign siderophore ferrioxamine B also acted as a substrate for the ferric reductase, while the foreign siderophore ferrichrome did not. Both ferrioxamine and ferrichrome served as iron sources for yeast- and mold-phase growth, the latter presumably by some other acquisition mechanism(s). PMID:11705947

  2. Fe-heme conformations in ferric myoglobin.

    PubMed Central

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

    1998-01-01

    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

  3. Ferric Chloride-induced Murine Thrombosis Models.

    PubMed

    Li, Wei; Nieman, Marvin; Sen Gupta, Anirban

    2016-01-01

    Arterial thrombosis (blood clot) is a common complication of many systemic diseases associated with chronic inflammation, including atherosclerosis, diabetes, obesity, cancer and chronic autoimmune rheumatologic disorders. Thrombi are the cause of most heart attacks, strokes and extremity loss, making thrombosis an extremely important public health problem. Since these thrombi stem from inappropriate platelet activation and subsequent coagulation, targeting these systems therapeutically has important clinical significance for developing safer treatments. Due to the complexities of the hemostatic system, in vitro experiments cannot replicate the blood-to-vessel wall interactions; therefore, in vivo studies are critical to understand pathological mechanisms of thrombus formation. To this end, various thrombosis models have been developed in mice. Among them, ferric chloride (FeCl3) induced vascular injury is a widely used model of occlusive thrombosis that reports platelet activation and aggregation in the context of an aseptic closed vascular system. This model is based on redox-induced endothelial cell injury, which is simple and sensitive to both anticoagulant and anti-platelets drugs. The time required for the development of a thrombus that occludes blood flow gives a quantitative measure of vascular injury, platelet activation and aggregation that is relevant to thrombotic diseases. We have significantly refined this FeCl3-induced vascular thrombosis model, which makes the data highly reproducible with minimal variation. Here we describe the model and present representative data from several experimental set-ups that demonstrate the utility of this model in thrombosis research. PMID:27684194

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

    PubMed

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

    2003-10-01

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

  5. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  6. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  7. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  8. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  9. 21 CFR 73.2298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  10. Thermal Properties of Phase Change Composites Containing Ferric Oxide Nanoparticles.

    PubMed

    Wang, Jifen; Xie, Huaqing; Li, Yang

    2015-04-01

    We prepared a series of homogeneous nanocomposites by suspending Fe2O3 nanoparticles into paraffin wax (PW) matrix. Fe2O3/PW nanocomposites have reduced both solid-solid phase change latent heat capacity (Ls-s) and solid-liquid phase change latent heat capacity (Ls-l) with an increase in the mass fraction of Fe2O3 nanoparticles. There is almost equable solid-solid phase change temperature (Ts-s) between PW and Fe2O3/PW composites, as well as melting temperature (Ts-l). Fe2O3 nanoparticle addition leads to substantial enhancement in the thermal conductivity of Fe2O3/PW and the enhancement ratio increases with the nanoparticle loading. Thermal conductivity of Fe2O3/PW composite with 3.0 wt% nanoparticles is about 0.27 W/(m · K) at 15 °C, which close to that of γ-Al2O3/PW with 5.0 wt% nanoparticles but higher than that of ZnO/PW containing 5.0 wt% nanoparticles. At 60 °C, Fe2O3/PW has higher thermal conductivity than γ-A12O3/PW and ZnO/PW contained with same fraction of nanoparticles. PMID:26353577

  11. Nanophase Carbonates on Mars: Does Evolved Gas Analysis of Nanophase Carbonates Reveal a Large Organic Carbon Budget in Near-Surface Martian Materials?

    NASA Technical Reports Server (NTRS)

    Archer, P. Douglas, Jr.; Niles, Paul B.; Ming, Douglas W.; Sutter, Brad; Eigenbrode, Jen

    2015-01-01

    Evolved Gas Analysis (EGA), which involves heating a sample and monitoring the gases released, has been performed on Mars by the Viking gas chromatography/mass spectrometry instruments, the Thermal and Evolved Gas Analyzer (TEGA) on the Phoenix lander, and the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory. All of these instruments detected CO2 released during sample analysis at abundances of approx. 0.1 to 5 wt% assuming a carbonate source. The source of the CO2 can be constrained by evaluating the temperature of the gas release, a capability of both the TEGA and SAM instruments. The samples analyzed by SAM show that the majority of the CO2 is released below 400C, much lower than traditional carbonate decomposition temperatures which can be as low as 400C for some siderites, with magnesites and calcites decomposing at even higher temperatures. In addition to mineralogy, decomposition temperature can depend on particle size (among other factors). If carbonates formed on Mars under low temperature and relative humidity conditions, the resulting small particle size (nanophase) carbonates could have low decomposition temperatures. We have found that calcite can be synthesized by exposing CaO to water vapor and CO2 and that the resulting mineral has an EGA peak of approx. 550C for CO2, which is about 200C lower than for other calcites. Work is ongoing to produce Fe and Mg-bearing carbonates using the same process. Current results suggest that nanophase calcium carbonates cannot explain the CO2 released from martian samples. If the decomposition temperatures of Mg and Fe-bearing nanophase carbonates are not significantly lower than 400C, other candidate sources include oxalates and carboxylated organic molecules. If present, the abundance of organic carbon in these samples could be greater than 0.1 wt % (1000s of ppm), a signficant departure from the paradigm of the organic-poor Mars based on Viking results.

  12. Nanophase Carbonates on Mars: Does Evolved Gas Analysis of Nanophase Carbonates Reveal a Large Organic Carbon Budget in Near-surface Martian Materials?

    NASA Astrophysics Data System (ADS)

    Archer, P. D., Jr.; Ming, D. W.; Sutter, B.; Niles, P. B.; Eigenbrode, J. L.

    2015-12-01

    Evolved Gas Analysis (EGA), which involves heating a sample and monitoring the gases released, has been performed on Mars by the Viking gas chromatography/mass spectrometry instruments, the Thermal and Evolved Gas Analyzer (TEGA) on the Phoenix lander, and the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory. All of these instruments detected CO2 released during sample analysis at abundances of ~0.1 to 5 wt% assuming a carbonate source. The source of the CO2 can be constrained by evaluating the temperature of the gas release, a capability of both the TEGA and SAM instruments. The samples analyzed by SAM show that the majority of the CO2is released below 400 °C, much lower than traditional carbonate decomposition temperatures which can be as low as 400 °C for some siderites, with magnesites and calcites decomposing at even higher temperatures. In addition to mineralogy, decomposition temperature can depend on particle size (among other factors). If carbonates formed on Mars under low temperature and relative humidity conditions, the resulting small particle size (nanophase) carbonates could have low decomposition temperatures. We have found that calcite can be synthesized by exposing CaO to water vapor and CO2 and that the resulting mineral has an EGA peak of ~550 °C for CO2, which is about 200 °C lower than for other calcites. Work is ongoing to produce Fe and Mg-bearing carbonates using the same process. Current results suggest that nanophase calcium carbonates cannot explain the CO2 released from martian samples. If the decomposition temperatures of Mg and Fe-bearing nanophase carbonates are not significantly lower than 400 °C, other candidate sources include oxalates and carboxylated organic molecules. If present, the abundance of organic carbon in these samples could be > 0.1 wt % (1000s of ppm), a signficant departure from the paradigm of the organic-poor Mars based on Viking results.

  13. Hydrogen and Ferric Iron in Mars Materials

    NASA Technical Reports Server (NTRS)

    Dyar, Melinda D.

    2004-01-01

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

  14. Induced anticlinic ordering and nanophase segregation of bow-shaped molecules in a smectic solvent.

    PubMed

    Maiti, Prabal K; Lansac, Yves; Glaser, Matthew A; Clark, Noel A

    2002-02-11

    Recent experiments indicate that doping low concentrations of bent-core molecules into calamitic smectic solvents can induce anticlinic and biaxial smectic phases. We have carried out Monte Carlo simulations of mixtures of rodlike molecules (hard spherocylinders with length/breadth ratio L(rod)/D = 5) and bow-shaped molecules (hard spherocylinder dimers with length/breadth ratio L(ban)/D = 5 or 2.5 and opening angle psi). We find that a low concentration ( 3%) of L(ban)/D = 5 dimers induces anticlinic ( SmC(A)) ordering in an untilted smectic ( SmA) phase for 100 < or = psi < 150. For L(ban)/D = 2.5, no tilted phases are induced. However, with decreasing psi we observe a sharp transition from intralamellar nanophase segregation (bow-shaped molecules segregated within smectic layers) to interlamellar nanophase segregation (bow-shaped molecules concentrated between smectic layers) near psi = 130.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  16. Kinetics of iron acquisition from ferric siderophores by Paracoccus denitrificans.

    PubMed Central

    Bergeron, R J; Weimar, W R

    1990-01-01

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

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

    PubMed

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

    2007-05-01

    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

  18. Nanophase separation and hindered glass transition in side-chain polymers.

    PubMed

    Beiner, Mario; Huth, Heiko

    2003-09-01

    Nanophase separation on length scales of 1-5 nanometres has been reported previously for small-molecule liquids, metallic glasses and also for several semicrystalline, liquid-crystalline and amorphous polymers. Here we show that nanophase separation of incompatible main and side-chain parts is a general phenomenon in amorphous side-chain polymers with long alkyl groups. We conclude from X-ray scattering and relaxation spectroscopy data for higher poly(n-alkyl acrylates) (PnAA) and poly(n-alkyl methacrylates) (PnAMA) that alkyl groups of different monomeric units aggregate in the melt and form self-assembled alkyl nanodomains with a typical size of 0.5-2 nm. A comparison with data for other polymer series having alkyl groups reveals that important structural and dynamic aspects are main-chain independent. A polyethylene-like glass transition within the alkyl nanodomains is observed and discussed in the context of a hindered glass transition in self-assembled confinements. This is an interesting link between central questions in glass-transition research and structural aspects in nanophase-separated materials.

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

    PubMed

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

    2012-04-01

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

  20. Effect of Fe-chelating complexes on a novel M2FC performance with ferric chloride and ferricyanide catholytes.

    PubMed

    Chung, Kyungmi; Lee, Ilgyu; Han, Jong-In

    2012-01-01

    As an effort to better utilize the microbial fuel cell (MFC) technology, we previously proposed an innovative MFC system named M2FC consisting of ferric-based MFC part and ferrous-based fuel cell (FC) part. In this reactor, ferric ion, the catholyte in the MFC part, was efficiently regenerated by the FC part with the generation of additional electricity. When both units were operated separately, the ferric-based MFC part produced approximately 1360 mW m(-2) of power density with FeCl(3) as catholyte and Fe-citrate as anolyte. The ferrous-based FC part with FeCl(3) as catholyte and Fe-EDTA as anolyte displayed the highest power density (1500 mW m(-2)), while that with ferricyanide as catholyte and Fe-noligand as anolyte had the lowest power density (380 mW m(-2)). The types of catholytes and chelating complexes as anolyte were found to play important roles in the reduction of ferric ions and oxidation of ferrous ion. Linear sweep voltammetry results supported that the cathode electrolytes were electrically active and these agreed well with the M2FC reactor performance. These results clearly showed that ligands played critical role in the efficiency and rate for recycling iron ion and thus the M2FC performance.

  1. The reevaluation of the ferric thiocyanate assay for lipid hydroperoxides with special considerations of the mechanistic aspects of the response.

    PubMed

    Mihaljević, B; Katusin-Razem, B; Razem, D

    1996-01-01

    The mechanistic aspects of the spectrophotometric method of analysis of lipid hydroperoxides (LOOH) based on the oxidation of ferrous to ferric ion and subsequent complexation of the latter by thiocyanate are considered. The method of analysis, as revised by us, was carried out in the same solvent that had been used for the extraction of lipids from the sample, a deoxygenated chloroform:methanol or a dichloromethane:methanol (2:1, v/v) mixture, and used a single solution containing both reagents, Fe2+ and SCN-, for developing the response. In that solvent, total lipids up to 5 mg/ml did not interfere, and linear increase of the absorbance of ferric thiocyanate complex was obtained up to 2 x 10(-5) M LOOH. Molar absorptivity of the ferric thiocyanate complex expressed per mol of LOOH was determined as 58,440 M-1 cm-1, based on the average of four ferric ions produced by each LOOH molecule. The estimated lowest detectable limit was about 170 pmol LOOH/ml of analyzed solution, which corresponded to about 50 mumol LOOH/kg lipid in complex natural mixtures. In addition to good sensitivity, and in contrast to some other more popular spectrophotometric assays for LOOH, the method is responsive also to hydroperoxides of mono- and di-unsaturated fatty acids. The method, thus, provides an easy, rapid, sensitive, and complete measure of hydroperoxidation of lipids. PMID:8791093

  2. Chalcopyrite concentrate leaching with biologically produced ferric sulphate.

    PubMed

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

    2006-09-01

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

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

    PubMed

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

    2013-06-01

    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.

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

    SciTech Connect

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

    1980-12-01

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

  5. [Pathway of aqueous ferric hydroxide catalyzed ozone decomposition and ozonation of trace nitrobenzene].

    PubMed

    Ma, Jun; Zhang, Tao; Chen, Zhong-lin; Sui, Ming-hao; Li, Xue-yan

    2005-03-01

    In this paper, the decomposition rate of ozone in water was measured over GAC and ferric hydroxide/GAC (FeOOH/GAC) catalyst and the mechanism of ozone catalytic decomposition was discussed. The catalytic ozonation activity of trace nitrobenzene in water was determined on several metal oxides and correlated with their surface density of hydroxyl groups and pHzpc,(pH of zero point of charge). The results show that: 1) The pseudo-first order rate of ozone decomposition increased by 68 and 108 percent for GAC and FeOOH/GAC catalysts respectively; 2) When t-butanol was added, the rate constant decreased by 9 % for GAC and 20% for FeOOH/GAC; 3) There was no direct correlation between surface density of hydroxyl groups and the activity of catalytic ozonation of nitrobenzene; 4) The oxide surface at nearly zero charged point was favorable for the catalytic ozonation of nitrobenzene.

  6. Treatment of wastewater phosphate by reductive dissolution of iron: use of ferric oxyhydroxide media.

    PubMed

    Robertson, W D; Lombardo, P S

    2011-01-01

    In smaller wastewater treatment systems such as septic systems, there is an interest in the development of passive phosphorus (P) removal methods. This study tested fixed-bed filters containing ferric oxyhydroxide media for wastewater P removal in a laboratory column test and in a full-scale domestic septic system. In the column test, during 30 mo of dosing with domestic wastewater, reductive iron dissolution reactions delivered consistent moderate concentrations of Fe into solution (2.9 ± 1.6 mg L), and influent PO-P of 3.7 ± 1.0 mg L was attenuated to 0.09 + 0.04 mg L in the column effluent (98% removal). Phosphorus breakthrough at successive locations along the column indicated that in addition to sorption, mineral precipitation reactions probably also played an important role in the observed P attenuation. This was supported by electron microprobe analyses, which showed the presence of thick (20 μm) secondary Fe-rich coatings containing P on the primary ferric media grains. Assays of NaHCO-leachable and acid-extractable P on the column solids showed accumulation of up to 5.4 mg g acid-extractable P near the column inlet, but <5% of this amount was easily desorbable, further indicating P attenuation from processes other than sorption. Over 19 mo of operation, the domestic septic system also showed generally consistent increased Fe in the filter effluent (2.6 ± 1.7 mg L) and achieved 99% P removal to 0.03 ± 0.02 mg L when the effluent was subsequently oxidized in a sand filter. Ferric iron filters could be attractive options for P removal in smaller wastewater systems because of their passive nature.

  7. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide... manufacturing practice: Oxalic acid or its salts, not more than 0.1 percent. Water soluble matter, not more than 3 percent. Water soluble cyanide, not more than 10 parts per million. Volatile matter, not more...

  8. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide... manufacturing practice: Oxalic acid or its salts, not more than 0.1 percent. Water soluble matter, not more than 3 percent. Water soluble cyanide, not more than 10 parts per million. Volatile matter, not more...

  9. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide... manufacturing practice: Oxalic acid or its salts, not more than 0.1 percent. Water soluble matter, not more than 3 percent. Water soluble cyanide, not more than 10 parts per million. Volatile matter, not more...

  10. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide... manufacturing practice: Oxalic acid or its salts, not more than 0.1 percent. Water soluble matter, not more than 3 percent. Water soluble cyanide, not more than 10 parts per million. Volatile matter, not more...

  11. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... citrate (iron (III) ammonium citrate) is prepared by the reaction of ferric hydroxide with citric acid... 18.5 percent iron, approximately 9 percent ammonia, and 65 percent citric acid and occurs as reddish... composed of 14.5 to 16 percent iron, approximately 7.5 percent ammonia, and 75 percent citric acid...

  12. 21 CFR 582.5306 - Ferric sodium pyrophosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients...

  13. 21 CFR 582.5306 - Ferric sodium pyrophosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients...

  14. 21 CFR 582.5306 - Ferric sodium pyrophosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients...

  15. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... for drug use made with ferric ammonium ferrocyanide may contain only those diluents listed in this subpart as safe and suitable for use in color additive mixtures for coloring drugs. (b) Specifications... manufacturing practice: Oxalic acid or its salts, not more than 0.1 percent. Water soluble matter, not more...

  16. Ligand Induced Spin Crossover in Penta-Coordinated Ferric Dithiocarbamates

    NASA Astrophysics Data System (ADS)

    Ganguli, P.; Iyer, R. M.

    1981-09-01

    On addition of lewis bases to Fe(dtc)2X, ligand exchange takes place through a SN2 mechanism, with a parallel spin crossover in the ferric ion. The two species (S = 3/2 and S = 5/2) formed are in dynamic chemical equilibrium, and a slow decomposition is then initiated.

  17. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ferric ammonium citrate. 184.1296 Section 184.1296 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed...

  18. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ferric ammonium citrate. 184.1296 Section 184.1296 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS...

  19. 21 CFR 184.1296 - Ferric ammonium citrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ferric ammonium citrate. 184.1296 Section 184.1296 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS...

  20. Sono synthesis and characterization of nanophase molybdenum-based materials for catalytic hydrodesulfurization.

    SciTech Connect

    Mahajan, D.; Marshall, C. L.; Castagnola, N.; Hanson, J. C.; BNL

    2004-02-10

    Unsupported nano-phase MoS{sub 2}, CoS, and CoS-MoS{sub 2} (Mo/Co mole ratio {approx}6/1) materials were prepared in hexadecane by sonolysis of the corresponding metal carbonyls at {approx}50 {sup o}C in high (>90%) yields as measured by the evolved carbon monoxide. Direct sonolysis of commercial micron-sized MoS{sub 2} in hexadecane did not result in nano-sizing. The TEM images showed that the synthesized MoS{sub 2} were aggregates of {approx}20 nm mean particle diameter, CoS was {approx}50 nm and the mixed-metal CoS-MoS{sub 2} could be viewed as a composite in which smaller MoS{sub 2} particles resided on the larger crystallites of CoS. The broad XRD peaks were consistent with nano-structured MoS{sub 2} and the sharp peaks were consistent with a more crystalline CoS-MoS{sub 2} species. The sharp peaks did not fit any single CoS pattern suggesting multiple phases. The XRD data showed that sonolysis did not alter the morphology of the micron-sized commercial MoS{sub 2} sample. In the HDS comparative activity study of dibenzothiophene, the synthesized nano-phase MoS{sub 2} exhibited more than an order of magnitude higher activity than its commercial micron-sized counterpart and the addition of Co further enhanced the activity. The HDS activity mirrored the temperature programmed reduction data. Interestingly, the nano-phase materials were less active for hydrogenation of 1-octene during the HDS study.

  1. Nanophased CoFe 2O 4 prepared by combustion method

    NASA Astrophysics Data System (ADS)

    Yan, C.-H.; Xu, Z.-G.; Cheng, F.-X.; Wang, Z.-M.; Sun, L.-D.; Liao, C.-S.; Jia, J.-T.

    1999-07-01

    The combustion method has been utilized to prepare nanophased powders of cobalt spinel ferrite using glycine as fuel. Structural and magnetic properties of the products were investigated with an X-ray diffractometer, a surface analyzer, and an alternating gradient magnetometer, respectively. Cobalt spinel ferrite prepared by the present method can easily form the well-crystallized nanoscale particles with a large specific surface area. The magnetization and coercivity show a strong dependence on the G/N (glycine to nitrates) ratio in the range from 0.2 to 1.0.

  2. Modeling the early stages of self-assembly in nanophase materials.

    PubMed

    Kozak, John J; Nicolis, C; Nicolis, G

    2007-04-21

    The early stages of self-assembly of the elementary building blocks of nanophase materials are studied. The relative roles of entropic and energetic factors in determining the relative abundance of the final products present is analyzed using both a kinetic mean field model and a mesoscopic approach in which self-assembly is viewed as an encounter-controlled process on a discrete lattice. The relevance of the results in zeolite synthesis in connection with the ordered liquid phases recently discovered in these materials is discussed.

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

    SciTech Connect

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

    1996-12-31

    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.

  4. 40 CFR 180.1191 - Ferric phosphate; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Ferric phosphate; exemption from the... Exemptions From Tolerances § 180.1191 Ferric phosphate; exemption from the requirement of a tolerance. An..., ferric phosphate (FePO4, CAS No. 11045-86-0) in or on all food commodities....

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Ferric phosphate; exemption from the... Exemptions From Tolerances § 180.1191 Ferric phosphate; exemption from the requirement of a tolerance. An..., ferric phosphate (FePO4, CAS No. 11045-86-0) in or on all food commodities....

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    Iron-enriched smectites have been suggested as important mineral compounds of the Martian soil. They were shown to comply with the chemical analysis of the Martian soil, to simulate many of the findings of the Viking Labeled Release Experiments on Mars, to have spectral reflectance in the VIS-NIR strongly resembling the bright regions on Mars. The analogy with Mars soil is based, in a number of aspects, on the nature and behavior of the iron oxides and oxyhydroxides deposited on the surface of the clay particles. A summary of the properties of these iron phases and some recent findings are presented. Their potential relevance to Mars surface processes is discussed.

  7. The leaching of chalcopyrite with ferric chloride

    NASA Astrophysics Data System (ADS)

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

    1986-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  9. Increased osteoblast functions among nanophase titania/poly(lactide-co-glycolide) composites of the highest nanometer surface roughness.

    PubMed

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

    2006-09-15

    Currently, the scientific challenges for bone tissue engineering lie in the development of suitable scaffold materials that can improve bone cell adhesion, proliferation, and differentiation. The design of nanophase titania/poly(lactide-co-glycolide) (PLGA) composites offers an exciting approach to combine the advantages of a degradable polymer with nanosize ceramic particles to optimize the physical and biological properties necessary for bone regeneration. Moreover, because of the presence of nanosized ceramics, such composites can be formulated to match the surface roughness of bone. For these reasons, the objective of the present in vitro study was to investigate osteoblast (bone-forming cell) adhesion and long-term functions on nanophase titania/PLGA composites that mimic the surface roughness of bone. Various sonication powers were applied in this study to manipulate titania dispersions in PLGA and consequently control their surface roughness. Most importantly, results correlated better osteoblast adhesion and long-term functions (such as collagen, alkaline phosphatase activity, and calcium-containing mineral deposition) among nanophase titania/PLGA composites that had surface roughness values closer to natural bone. In this manner, this present study demonstrated that the nanophase titania/PLGA composites sonicated to have nanometer surface roughness values can improve osteoblast functions necessary for enhanced bone tissue engineering applications.

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

    SciTech Connect

    Beitz, James V. . E-mail: beitz@anl.gov; Williams, C.W.; Hong, K.-S.; Liu, G.K.

    2005-02-15

    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{sub 4} nanophases embedded in silica were probed based on excitation of 5f states of Cm{sup 3+}, Bk{sup 3+}, and Es{sup 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{sub 4} nanophases. This conclusion is consistent with predictions of an ion transport code commonly used to model ion implantation. Luminescence from the {sup 6}D{sub 7/2} state of Cm{sup 3+}was used as an internal standard. Ion-ion energy transfer dominated the dynamics of the observed emitting 5f 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.

  11. Reducing bacteria and macrophage density on nanophase hydroxyapatite coated onto titanium surfaces without releasing pharmaceutical agents

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Garima; Yazici, Hilal; Webster, Thomas J.

    2015-04-01

    Reducing bacterial density on titanium implant surfaces has been a major concern because of the increasing number of nosocomial infections. Controlling the inflammatory response post implantation has also been an important issue for medical devices due to the detrimental effects of chronic inflammation on device performance. It has recently been demonstrated that manipulating medical device surface properties including chemistry, roughness and wettability can control both infection and inflammation. Here, we synthesized nanophase (that is, materials with one dimension in the nanoscale) hydroxyapatite coatings on titanium to reduce bacterial adhesion and inflammatory responses (as measured by macrophage functions) and compared such results to bare titanium and plasma sprayed hydroxyapatite titanium coated surfaces used clinically today. This approach is a pharmaceutical-free approach to inhibit infection and inflammation due to the detrimental side effects of any drug released in the body. Here, nanophase hydroxyapatite was synthesized in sizes ranging from 110-170 nm and was subsequently coated onto titanium samples using electrophoretic deposition. Results indicated that smaller nanoscale hydroxyapatite features on titanium surfaces alone decreased bacterial attachment in the presence of gram negative (P. aeruginosa), gram positive (S. aureus) and ampicillin resistant gram-negative (E. coli) bacteria as well as were able to control inflammatory responses; properties which should lead to their further investigation for improved medical applications.

  12. Reducing bacteria and macrophage density on nanophase hydroxyapatite coated onto titanium surfaces without releasing pharmaceutical agents.

    PubMed

    Bhardwaj, Garima; Yazici, Hilal; Webster, Thomas J

    2015-05-14

    Reducing bacterial density on titanium implant surfaces has been a major concern because of the increasing number of nosocomial infections. Controlling the inflammatory response post implantation has also been an important issue for medical devices due to the detrimental effects of chronic inflammation on device performance. It has recently been demonstrated that manipulating medical device surface properties including chemistry, roughness and wettability can control both infection and inflammation. Here, we synthesized nanophase (that is, materials with one dimension in the nanoscale) hydroxyapatite coatings on titanium to reduce bacterial adhesion and inflammatory responses (as measured by macrophage functions) and compared such results to bare titanium and plasma sprayed hydroxyapatite titanium coated surfaces used clinically today. This approach is a pharmaceutical-free approach to inhibit infection and inflammation due to the detrimental side effects of any drug released in the body. Here, nanophase hydroxyapatite was synthesized in sizes ranging from 110-170 nm and was subsequently coated onto titanium samples using electrophoretic deposition. Results indicated that smaller nanoscale hydroxyapatite features on titanium surfaces alone decreased bacterial attachment in the presence of gram negative (P. aeruginosa), gram positive (S. aureus) and ampicillin resistant gram-negative (E. coli) bacteria as well as were able to control inflammatory responses; properties which should lead to their further investigation for improved medical applications.

  13. Nanophase-separated amphiphilic conetworks as versatile matrixes for optical chemical and biochemical sensors.

    PubMed

    Hanko, Michael; Bruns, Nico; Rentmeister, Sara; Tiller, Jörg C; Heinze, Jürgen

    2006-09-15

    As a novel class of sensor matrixes, nanophase-separated amphiphilic polymeric conetworks (APCNs) open a new dimension for optical chemical and biochemical sensing. These conetworks consist of a hydrophilic phase-we used poly(2-hydroxyethyl acrylate), poly(2-(dimethylamino)ethyl acrylate), or polycationic poly(2-(trimethylammonium)ethyl acrylate)-and of a hydrophobic phase-poly(dimethylsiloxane). Sensors can be prepared by simple impregnation of the matrix. Due to nanophase separation, there is a spatial separation between areas in which the indicator reagents are well immobilized and areas that advantageously take care of the diffusive transport of the analyte, whereby these functionalities of the contrary phases can be exchanged. Thanks to the huge interface between the contrary phases, the accessibility of the indicator reagents is good, which makes it possible to design sensors with high sensitivity. To demonstrate the advantages of APCNs as matrixes, different prototypes of sensors were prepared, e.g., one to determine gaseous chlorine based on its reaction with immobilized o-tolidine and another to determine vaporous acids based on immobilized bromophenol blue dianions. As a breakthrough in biochemical sensing, we are also able to present an easily producible, optically transparent biochemical sensor to determine peroxides in nonpolar organic media-based on coimmobilized horseradish peroxidase and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate).

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

    SciTech Connect

    Burgos, W. D.

    2005-02-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

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

    2012-10-16

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

  17. Paracoccidioides spp. ferrous and ferric iron assimilation pathways

    PubMed Central

    Bailão, Elisa Flávia L. C.; Lima, Patrícia de Sousa; Silva-Bailão, Mirelle G.; Bailão, Alexandre M.; Fernandes, Gabriel da Rocha; Kosman, Daniel J.; Soares, Célia Maria de Almeida

    2015-01-01

    Iron is an essential micronutrient for almost all organisms, including fungi. Usually, fungi can uptake iron through receptor-mediated internalization of a siderophore or heme, and/or reductive iron assimilation (RIA). Traditionally, the RIA pathway consists of ferric reductases (Fres), ferroxidase (Fet3) and a high-affinity iron permease (Ftr1). Paracoccidioides spp. genomes do not present an Ftr1 homolog. However, this fungus expresses zinc regulated transporter homologs (Zrts), members of the ZIP family of membrane transporters that are able in some organisms to transport zinc and iron. A 2,3,5-triphenyltetrazolium chloride (TTC)-overlay assay indicates that both Pb01 and Pb18 express a ferric reductase activity; however, 59Fe uptake assays indicate that only in Pb18 is this activity coupled to a reductase-dependent iron uptake pathway. In addition, Zrts are up-regulated in iron deprivation, as indicated by RNAseq and qRT-PCR using Pb01 transcripts. RNAseq strategy also demonstrated that transcripts related to siderophore uptake and biosynthesis are up-regulated in iron-deprived condition. The data suggest that the fungus could use both a non-classical RIA, comprising ferric reductases and Fe/Zn permeases (Zrts), and siderophore uptake pathways under iron-limited conditions. The study of iron metabolism reveals novel surface molecules that could function as accessible targets for drugs to block iron uptake and, consequently, inhibit pathogen's proliferation. PMID:26441843

  18. Drug insight: Safety of intravenous iron supplementation with sodium ferric gluconate complex.

    PubMed

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

    2006-02-01

    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 large phase IV trials documenting its safety. SFGC is efficacious and, at recommended doses, is associated with a low incidence of adverse events. There have been few comparative studies of the nondextran intravenous iron preparations; however, they are known to have different pharmacokinetic characteristics. There is also evidence to indicate that these compounds differ in terms of their cytotoxic and proinflammatory properties, and their propensity to induce oxidative stress. This paper reviews the current literature on the safety of SFGC and examines the emerging safety issues surrounding the use of intravenous iron.

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

    PubMed

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

    2015-02-01

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

  20. Experimental Evidence of the Origin of Nanophase Separation in Low Hole-Doped Colossal Magnetoresistant Manganites.

    PubMed

    Cortés-Gil, Raquel; Ruiz-González, M Luisa; González-Merchante, Daniel; Alonso, José M; Hernando, Antonio; Trasobares, Susana; Vallet-Regí, María; Rojo, Juan M; González-Calbet, José M

    2016-01-13

    While being key to understanding their intriguing physical properties, the origin of nanophase separation in manganites and other strongly correlated materials is still unclear. Here, experimental evidence is offered for the origin of the controverted phase separation mechanism in the representative La1-xCaxMnO3 system. For low hole densities, direct evidence of Mn(4+) holes localization around Ca(2+) ions is experimentally provided by means of aberration-corrected scanning transmission electron microscopy combined with electron energy loss spectroscopy. These localized holes give rise to the segregated nanoclusters, within which double exchange hopping between Mn(3+) and Mn(4+) remains restricted, accounting for the insulating character of perovskites with low hole density. This localization is explained in terms of a simple model in which Mn(4+) holes are bound to substitutional divalent Ca(2+) ions.

  1. Communication: Influence of nanophase segregation on ion transport in room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Griffin, Philip J.; Wang, Yangyang; Holt, Adam P.; Sokolov, Alexei P.

    2016-04-01

    We report measurements of the ionic conductivity, shear viscosity, and structural dynamics in a homologous series of quaternary ammonium ionic liquids (ILs) and a prototypical imidazolium-based IL over a wide range of temperatures down to the glass transition. We find that the ionic conductivity of these materials generally decreases, while the shear viscosity correspondingly increases, with increasing volume fraction of aliphatic side groups. Upon crossing an aliphatic volume fraction of ˜0.40, we observe a sharp, order-of-magnitude decrease in ionic conductivity and enhancement of viscosity, which coincides with the presence of long-lived, nanometer-sized alkyl aggregates. These strong changes in dynamics are not mirrored in the ionicity of these ILs, which decreases nearly linearly with aliphatic volume fraction. Our results demonstrate that nanophase segregation in neat ILs strongly reduces ionic conductivity primarily due to an aggregation-induced suppression of dynamics.

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

    SciTech Connect

    Lahoz, F.; Martin, I.R.; Calvilla-Quintero, J.M.

    2005-01-31

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

  3. Communication: Influence of nanophase segregation on ion transport in room temperature ionic liquids.

    PubMed

    Griffin, Philip J; Wang, Yangyang; Holt, Adam P; Sokolov, Alexei P

    2016-04-21

    We report measurements of the ionic conductivity, shear viscosity, and structural dynamics in a homologous series of quaternary ammonium ionic liquids (ILs) and a prototypical imidazolium-based IL over a wide range of temperatures down to the glass transition. We find that the ionic conductivity of these materials generally decreases, while the shear viscosity correspondingly increases, with increasing volume fraction of aliphatic side groups. Upon crossing an aliphatic volume fraction of ∼0.40, we observe a sharp, order-of-magnitude decrease in ionic conductivity and enhancement of viscosity, which coincides with the presence of long-lived, nanometer-sized alkyl aggregates. These strong changes in dynamics are not mirrored in the ionicity of these ILs, which decreases nearly linearly with aliphatic volume fraction. Our results demonstrate that nanophase segregation in neat ILs strongly reduces ionic conductivity primarily due to an aggregation-induced suppression of dynamics.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  5. Preliminary oxidation in histochemical staining methods for cholesterol.

    PubMed

    Adams, C W; High, O B

    1980-08-01

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

  6. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films

    PubMed Central

    Zhang, Huairuo; Reaney, Ian M.; Marincel, Daniel M.; Trolier-McKinstry, Susan; Ramasse, Quentin M.; MacLaren, Ian; Findlay, Scott D.; Fraleigh, Robert D.; Ross, Ian M.; Hu, Shunbo; Ren, Wei; Mark Rainforth, W.

    2015-01-01

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)3+ Fe3+O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community. PMID:26272264

  7. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films.

    PubMed

    Zhang, Huairuo; Reaney, Ian M; Marincel, Daniel M; Trolier-McKinstry, Susan; Ramasse, Quentin M; MacLaren, Ian; Findlay, Scott D; Fraleigh, Robert D; Ross, Ian M; Hu, Shunbo; Ren, Wei; Rainforth, W Mark

    2015-08-14

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)(3+) Fe(3+)O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community.

  8. Stabilisation of Fe2O3-rich Perovskite Nanophase in Epitaxial Rare-earth Doped BiFeO3 Films.

    PubMed

    Zhang, Huairuo; Reaney, Ian M; Marincel, Daniel M; Trolier-McKinstry, Susan; Ramasse, Quentin M; MacLaren, Ian; Findlay, Scott D; Fraleigh, Robert D; Ross, Ian M; Hu, Shunbo; Ren, Wei; Rainforth, W Mark

    2015-01-01

    Researchers have demonstrated that BiFeO3 exhibits ferroelectric hysteresis but none have shown a strong ferromagnetic response in either bulk or thin film without significant structural or compositional modification. When remanent magnetisations are observed in BiFeO3 based thin films, iron oxide second phases are often detected. Using aberration-corrected scanning transmission electron microscopy, atomic resolution electron energy loss spectrum-mapping and quantitative energy dispersive X-ray spectroscopy analysis, we reveal the existence of a new Fe2O3-rich perovskite nanophase, with an approximate formula (Fe0.6Bi0.25Nd0.15)(3+) Fe(3+)O3, formed within epitaxial Ti and Nd doped BiFeO3 perovskite films grown by pulsed laser deposition. The incorporation of Nd and Bi ions on the A-site and coherent growth with the matrix stabilise the Fe2O3-rich perovskite phase and preliminary density functional theory calculations suggest that it should have a ferrimagnetic response. Perovskite-structured Fe2O3 has been reported previously but never conclusively proven when fabricated at high-pressure high-temperature. This work suggests the incorporation of large A-site species may help stabilise perovskite-structured Fe2O3. This finding is therefore significant not only to the thin film but also to the high-pressure community. PMID:26272264

  9. Reaction mechanism for the ferric chloride leaching of sphalerite

    NASA Astrophysics Data System (ADS)

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

    1985-12-01

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

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

    DOEpatents

    Clark, H.M.; Duffey, D.

    1958-06-10

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

  11. Ferric hydroxamate transport without subsequent iron utilization in Bacillus megaterium.

    PubMed Central

    Arceneaux, J E; Byers, B R

    1976-01-01

    Iron transport and utilization were examined in Bacillus megaterium Ard1, a mutant that is resistant to the hydroxymate antibiotic A22765 and whose growth is inhibited by the structurally similar hydroxamate Desferal. Rapid, low-level uptake of Desferal-50Fe was observed; such uptake was temperature and energy independent. Gel filtration chromatography of the cytoplasmic fraction of protoplasts labeled with Desferal-55Fe for 30 to 120 s demonstrated only unchanged esferal-55Fe in the cytoplasm. Although B. megaterium Ard1 showed transport of Desferal-59Fe by a process that resembles facilitated diffusion, this organism was unable to transfer iron from this chelate to cellular macromolecules for metabolic use. High-level transport of the ferric hydroxamate schizokinen-59Fe by B. megaterium Ard1 was both temperature and energy dependent. Within 30 s, protoplasts labeled with schizokinen-55Fe contained iron associated with certain macromolecules and in an apparent "pool" of schizokinen-55Fe in the cytoplasmic fraction. Prior transport of Dseferal-55Fe by protoplasts of strain Ard1 did not interfere with subsequent transport and utilization of schizokinen-59Fe. These studies suggest that transport of ferric hydroxamates may occur by a facilitated diffusion-type process; transfer of iron to cellular macromolecules may drive high-level transport of the chelate and may be the step at which energy is required in the iron transport-assimilation process. PMID:821926

  12. Particulate and THM precursor removal with ferric chloride

    SciTech Connect

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

    1999-11-01

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

  13. Functional characterization of the chloroplast ferric chelate oxidoreductase enzyme.

    PubMed

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

    2014-05-01

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

  14. Intravenous ferric carboxymaltose for the treatment of iron deficiency anemia

    PubMed Central

    Friedrisch, João Ricardo; Cançado, Rodolfo Delfini

    2015-01-01

    Nutritional iron deficiency anemia is the most common deficiency disorder, affecting more than two billion people worldwide. Oral iron supplementation is usually the first choice for the treatment of iron deficiency anemia, but in many conditions, oral iron is less than ideal mainly because of gastrointestinal adverse events and the long course needed to treat the disease and replenish body iron stores. Intravenous iron compounds consist of an iron oxyhydroxide core, which is surrounded by a carbohydrate shell made of polymers such as dextran, sucrose or gluconate. The first iron product for intravenous use was the high molecular weight iron dextran. However, dextran-containing intravenous iron preparations are associated with an elevated risk of anaphylactic reactions, which made physicians reluctant to use intravenous iron for the treatment of iron deficiency anemia over many years. Intravenous ferric carboxymaltose is a stable complex with the advantage of being non-dextran-containing and a very low immunogenic potential and therefore not predisposed to anaphylactic reactions. Its properties permit the administration of large doses (15 mg/kg; maximum of 1000 mg/infusion) in a single and rapid session (15-minute infusion) without the requirement of a test dose. The purpose of this review is to discuss some pertinent issues in relation to the history, pharmacology, administration, efficacy, and safety profile of ferric carboxymaltose in the treatment of patients with iron deficiency anemia. PMID:26670403

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Acid mine drainage (AMD) is a widespread environmental problem with deleterious impacts on water quality in streams and watersheds. AMD is generated largely by the oxidation of metal sulfides (i.e. pyrite) by ferric iron. This abiotic reaction is catalyzed by conversion of ferrous to ferric iron by iron and sulfur oxidizing microorganisms. Biostimulation is currently being investigated as an attempt to inhibit the oxidation of pyrite and growth of iron oxidizing bacteria through addition of organic carbon. This may stimulate growth of indigenous communities of acidophilic heterotrophic bacteria to compete for oxygen. The goal of this research is to investigate a secondary mechanism associated with carbon addition: complexation of free Fe(III) by soluble microbial growth products (SMPs) produced by microorganisms growing in waste rock. Exploratory research at the laboratory scale examined the effect of soluble microbial products (SMPs) on the kinetics of oxidation of pure pyrite during shaker flask experiments. The results confirmed a decrease in the rate of pyrite oxidation that was dependent upon the concentration of SMPs in solution. We are using these data to verify results from a pyrite oxidation model that accounts for SMPs. This reactor model involves differential-algebraic equations incorporating total component mass balances and mass action laws for equilibrium reactions. Species concentrations determined in each time step are applied to abiotic pyrite oxidation rate expressions from the literature to determine the evolution of total component concentrations. The model was embedded in a parameter estimation algorithm to determine the reactive surface area of pyrite in an abiotic control experiment, yielding an optimized value of 0.0037 m2. The optimized model exhibited similar behavior to the experiment for this case; the root mean squared of residuals for Fe(III) was calculated to be 7.58 x 10-4 M, which is several orders of magnitude less than the actual

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

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

    PubMed

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

    2014-07-01

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

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

    PubMed

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

    2014-07-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    For the prospective return of humans to the Moon and the extensive amount of premonitory studies necessary, large quantities of lunar soil simulants are required, for a myriad of purposes from construction/engineering purposes all the way to medical testing of its effects from ingestion by humans. And there is only a limited and precious quantity of lunar soil available on Earth (i.e., Apollo soils) - therefore, the immediate need for lunar soil simulants. Since the Apollo era, there have been several simulants; of these JSC-1 (Johnson Space Center) and MLS-1 (Minnesota Lunar Simulant) have been the most widely used. JSC-1 was produced from glassy volcanic tuff in order to approximate lunar soil geotechnical properties; whereas, MLS-1 approximates the chemistry of Apollo 11 high-Ti soil, 10084. Stocks of both simulants are depleted, but JSC-1 has recently gone back into production. The lunar soil simulant workshop, held at Marshall Space Flight Center in January 2005, identified the need to make new simulants for the special properties of lunar soil, such as nanophase iron (np-Fe(sup 0). Hill et al. (2005, this volume) showed the important role of microscale Fe(sup 0) in microwave processing of the lunar soil simulants JSC-1 and MLS-1. Lunar soil is formed by space weathering of lunar rocks (e.g., micrometeorite impact, cosmic particle bombardment). Glass generated during micrometeorite impact cements rock and mineral fragments together to form aggregates called agglutinates, and also produces vapor that is deposited and coats soil grains. Taylor et al. (2001) showed that the relative amount of impact glass in lunar soil increases with decreasing grain size and is the most abundant component in lunar dust (less than 20 micrometer fraction). Notably, the magnetic susceptibility of lunar soil also increases with the decreasing grain size, as a function of the amount of nanophase-sized Fe(sup 0) in impact-melt generated glass. Keller et al. (1997, 1999) also

  20. Functional analysis of the ferric uptake requlator gene, fur, in Xanthomonas vesicatoria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iron is essential for the growth and survival of many organisms. Intracellular iron homeostasis must be maintained for cell survival and protection against iron toxicity. The ferric uptake regulator protein (Fur) regulates the high-affinity ferric uptake system in many bacteria. To investigate the f...

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    NASA Mars Exploration Rover (MER) Spirit explored Gusev Crater to look for signs of ancient aqueous activity, assess past environmental conditions and suitability for life. Spirit excavated light-toned, S-rich soils at several locations. These are likely of hydrothermal, possibly fumarolic origin. At a location dubbed Paso Robles the light-toned soil was also rich in P - a signature from surrounding rock. While S is mainly bound in ferric hydrated sulfates [1], the mineralogy of P is ill-constrained [2]. P is a key element for life and its mineralogy constrains its availability. Ferrous phases observed in Paso Robles Mössbauer spectra may represent olivine and pyroxene from surrounding basaltic soil [1] or ferrous phosphate minerals [3]. Phosphate is well-known to complex and stabilize Fe 2+ against oxidation to Fe 3+ . Schröder et al. [3] proposed a formation pathway of ferrous phosphate/ferric sulfate associations: sulfuric acid reacts with basalt containing apatite, forming CaSO4 and phosphoric acid. The phosphoric and/or excess sulfuric acid reacts with olivine, forming Fe2+-phosphate and sulfate. The phosphate is less soluble and precipitates. Ferrous sulfate remains in solution and is oxidized as pH increases. To verify this pathway, we dissolved Fe2+-chloride and Na-phosphate salts in sulfuric acid inside an anoxic glovebox. The solution was titrated to pH 6 by adding NaOH when a first precipitate formed, which was ferrous phosphate according to Mössbauer spectroscopy (MB). At that point the solution was removed from the glovebox and allowed to evaporate in the presence of atmospheric oxygen, leading to the oxidation of Fe2+. The evaporation rate was controlled by keeping the suspensions at different temperatures; pH was monitored during the evaporation process. The final precipitates were analyzed by MB and X-Ray Fluorescence (XRF), comparable to MER MB and Alpha Particle X-ray Spectrometer instrument datasets, and complementary techniques such as X

  2. Magnetic Susceptibility Analyses of Nanophase Iron Particle Diameters and Volumes Produced through Laser Irradiation.

    NASA Astrophysics Data System (ADS)

    Markley, M. M.; Kletetschka, G.

    2015-12-01

    Micrometeorite impacts greatly modify surfaces exposed to the space environment. This interaction vaporizes the surficial material and allows for the re-precipitation of minerals and iron. Characterizing the recondensed iron or nanophase metallic iron (npFe0) improves our interpretations in remote sensing of planetary surfaces. We irradiated olivine samples with energies simulating micrometeorite impact energies from around the inner Solar System. They revealed npFe0 as single domain (SD) and superparamagnetic (SPM) iron grains varying in size. Spectrally they changed the spectral reflectance of silicate minerals and contribute to "space weathering": (1) darkens the overall reflectance, (2) steepens (or reddens) the spectral slope, and (3) decreases the contrast in the silicate 1 µm band. Using frequency dependent magnetic susceptibility (MS), we revealed patterns of npFe0 sizes. Fresh samples contained some nanophase magnetic sources due to decreasing magnetic susceptibility, when changing frequency from 4 kHz to 16 kHz. Using the fresh olivine as a standard, the lunar analog displayed increased MS at the lower 4 kHz indicating that more iron was transformed into magnetic sources. At 16 kHz, the MS decreased due to SPM particles that were being formed with sizes <10 nm. With the Mercury analog, at higher 16 kHz frequencies the MS increased rather than decreased. We can infer that the excess energy from our laser converted the amount of smaller <10 nm SPM particles by growth into an increasing volume of >10 nm particles. With the asteroid analog, we found a lower MS at 16 kHz, but nothing less MS than the Lunar analog. The 4 kHz MS was similar to the fresh olivine. At the lowest irradiation energy for the asteroid sample we have evidence that we are producing npFe0 particles. Our data compares well with traditional methods of forming npFe0, such as thermal processing of olivine, suggesting that with laser irradiation there is a linear increase of nanoparticles

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

    SciTech Connect

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

    2003-09-15

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

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

    PubMed Central

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

    2010-01-01

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

  5. Deposition rates of oxidized iron on Mars

    NASA Technical Reports Server (NTRS)

    Burns, R. G.

    1993-01-01

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

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

    PubMed

    Troxell, Bryan; Hassan, Hosni M

    2013-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Dyar, Melinda D.

    2003-01-01

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

  8. Application of granular ferric hydroxides for removal elevated concentrations of arsenic from mine waters

    NASA Astrophysics Data System (ADS)

    Szlachta, Małgorzata; Włodarczyk, Paweł; Wójtowicz, Patryk

    2015-04-01

    Arsenic is naturally occurring element in the environment. Over three hundred minerals are known to contain some form of arsenic and among them arsenopyrite is the most common one. Arsenic-bearing minerals are frequently associated with ores containing mined metals such as copper, tin, nickel, lead, uranium, zinc, cobalt, platinum and gold. In the aquatic environment arsenic is typically present in inorganic forms, mainly in two oxidation states (+5, +3). As(III) is dominant in more reduced conditions, whereas As(V) is mostly present in an oxidizing environment. However, due to certain human activities the elevated arsenic levels in aquatic ecosystems are arising to a serious environmental problem. High arsenic concentrations found in surface and groundwaters, in some regions originate from mining activities and ore processing. Therefore, the major concern of mining industry is to maintain a good quality of effluents discharged in large volumes. This requires constant monitoring of effluents quality that guarantee the efficient protection of the receiving waters and reacting to possible negative impact of contamination on local communities. A number of proven technologies are available for arsenic removal from waters and wastewaters. In the presented work special attention is given to the adsorption method as a technically feasible, commonly applied and effective technique for the treatment of arsenic rich mine effluents. It is know that arsenic has a strong affinity towards iron rich materials. Thus, in this study the granular ferric hydroxides (CFH 12, provided by Kemira Oyj, Finland) was applied to remove As(III) and As(V) from aqueous solutions. The batch adsorption experiments were carried out to assess the efficiency of the tested Fe-based material under various operating parameters, including composition of treated water, solution pH and temperature. The results obtained from the fixed bed adsorption tests demonstrated the benefits of applying granular

  9. The synthesis and characterization of nanophase hydroxyapatite using a novel dispersant-aided precipitation method.

    PubMed

    Cunniffe, Gráinne M; O'Brien, Fergal J; Partap, Sonia; Levingstone, Tanya J; Stanton, Kenneth T; Dickson, Glenn R

    2010-12-15

    The synthesis of nanophase hydroxyapatite (nHA) is of importance in the field of biomaterials and bone tissue engineering. The bioactive and osteoconductive properties of nHA are of much benefit to a wide range of biomedical applications such as producing bone tissue engineered constructs, coating medical implants, or as a carrier for plasmid DNA in gene delivery. This study aimed to develop a novel low-temperature dispersant-aided precipitation reaction to produce nHA particles (<100 nm), which are regarded as being preferable to micron-sized agglomerates of nHA. The variables investigated and optimized include the reaction pH, the rate of reactant mixing, use of sonication, order of addition, and concentration of the primary reactants, in addition, the effect of using poly(vinyl alcohol) (PVA) surfactant and Darvan 821A® dispersing agent during the reaction was also examined. It was found that by fine-tuning the synthesis parameters and incorporating the dispersing agent, monodisperse, phase-pure nano-sized particles under 100 nm were attained, suitable for clinical applications in bone regeneration.

  10. Fully aromatic block copolymers for fuel cell membranes with densely sulfonated nanophase domains.

    PubMed

    Takamuku, Shogo; Jannasch, Patric

    2011-03-01

    Two multiblock copoly(arylene ether sulfone)s with similar block lengths and ion exchange capacities (IECs) were prepared by a coupling reaction between a non-sulfonated precursor block and a highly sulfonated precursor block containing either fully disulfonated diarylsulfone or fully tetrasulfonated tetraaryldisulfone segments. The latter two precursor blocks were sulfonated via lithiation-sulfination reactions whereby the sulfonic acid groups were exclusively placed in ortho positions to the many sulfone bridges, giving these blocks IECs of 4.1 and 4.6 meq·g⁻¹, respectively. Copolymer membranes with IECs of 1.4 meq·g⁻¹ displayed well-connected hydrophilic nanophase domains and had decomposition temperatures at, or above, 300 °C under air. The copolymer with the tetrasulfonated tetraaryldisulfone segments showed a proton conductivity of 0.13 S·cm⁻¹ at 80 °C under fully humidified conditions, and surpassed that of a perfluorosulfonic acid membrane (NRE212) by a factor of 5 at -20 °C over time.

  11. Solid-solid interface adsorption of proteins and enzymes in nanophase-separated amphiphilic conetworks.

    PubMed

    Dech, Stephan; Cramer, Tobias; Ladisch, Reinhild; Bruns, Nico; Tiller, Joerg C

    2011-05-01

    Amphiphilic polymer conetworks (APCNs) are materials with a very large interface between their hydrophilic and hydrophobic phases due to their nanophase-separated morphologies. Proteins were found to enrich in APCNs by up to 2 orders of magnitude when incubated in aqueous protein solutions, raising the question of the driving force of protein uptake into APCNs. The loading of poly(2-hydroxyethyl acrylate)-linked by-poly(dimethylsiloxane) (PHEA-l-PDMS) with heme proteins (myoglobin, horseradish peroxidase, hemoglobin) and lipases was studied under variation of parameters such as incubation time, pH, concentration of the protein solution, and conetwork composition. Adsorption of enzymes to the uncharged interface is the main reason for protein uptake, resulting in protein loading of up to 23 wt %. Experimental results were supported by computation of electrostatic potential maps of a lipase, indicating that hydrophobic patches are responsible for the adsorption to the interface. The findings underscore the potential of enzyme-loaded APCNs in biocatalysis and as sensors.

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

    PubMed Central

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

    2013-01-01

    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

  13. Nanophase iron production through laser irradiation and magnetic detection of space weathering analogs

    NASA Astrophysics Data System (ADS)

    Markley, Matthew; Kletetschka, Gunther

    2016-04-01

    Airless bodies are constantly exposed to space weathering. The Moon and other similar S-type asteroids physically change through comminution, melting, and agglutinate formation, while spectrally they are darkening, steepening (or reddening) the spectral slope toward longer wavelengths, and reducing silicate mineral absorption bands. In these S-type bodies the production of submicroscopic metallic iron, or nanophase iron (SMFe, npFe0) is a major contributor in these spectral changes. We made a qualitative estimate of both quantity and size distribution of produced metallic iron by space weathered analog, olivine irradiated by laser. Through SEM observation we confirmed that nanoparticles of metallic iron formed in the nm range. Spectroscopic and magnetic susceptibility (MS) through temperature analyses reveal an increasing trend of npFe0 formation, darkening, reddening, and shallowing of the 1 μm olivine absorption band. Olivine that produced the larger end of the size range of npFe0 produced similar effects, except for increased reddening. The magnetic data suggests that with laser irradiation there is both a linear increase of nanoparticles and a logarithmic increase in spectral change with SW time.

  14. Osteoblast function on nanophase alumina materials: Influence of chemistry, phase, and topography.

    PubMed

    Price, Rachel L; Gutwein, Luke G; Kaledin, Leonid; Tepper, Frederick; Webster, Thomas J

    2003-12-15

    Alumina is a material that has been used in both dental and orthopedic applications. It is with these uses in mind that osteoblast (bone-forming cell) function on alumina of varying particulate size, chemistry, and phase was tested in order to determine what formulation might be the most beneficial for bone regeneration. Specifically, in vitro osteoblast adhesion, proliferation, intracellular alkaline phosphatase activity, and calcium deposition was observed on delta-phase nanospherical, alpha-phase conventional spherical, and boehmite nanofiber alumina. Results showed for the first time increased osteoblast functions on the nanofiber alumina. Specifically, a 16% increase in osteoblast adhesion over nanophase spherical alumina and a 97% increase over conventional spherical alumina were found for nanofiber alumina after 2 h. A 29% increase in cell number after 5 days and up to a 57% greater amount of calcium was found on the surface of the nanofiber alumina compared with other alumina surfaces. Some of the possible explanations for such enhanced osteoblast behavior on nanofiber alumina may be attributed to chemistry, crystalline phase, and topography. Increased osteoblast function on nanofiber alumina suggests that it may be an ideal material for use in orthopedic and dental applications.

  15. Analysis on fluorescence intensity reverse photonic phenomenon between red and green fluorescence of oxyfluoride nanophase vitroceramics.

    PubMed

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

    2007-10-01

    An interesting fluorescence intensity reverse photonic phenomenon between red and green fluorescence is investigated. The dynamic range Sigma of intensity reverse between red and green fluorescence of Er(0.5)Yb(3):FOV oxyfluoride nanophase vitroceramics, when excited by 378.5nm and 522.5nm light respectively, is about 4.32x10(2). It is calculated that the phonon-assistant energy transfer rate of the electric multi-dipole interaction of {(4)G(11/2)(Er(3+))?(4)F(9/2)(Er(3+)), (2)F(7/2)(Yb(3+))?(2)F(5/2)(Yb(3+))} energy transfer of Er(0.5)Yb(3):FOV is around 1.380x10(8)s(-1), which is much larger than the relative multiphonon nonradiative relaxation rates 3.20x10(5)s(-1). That energy transfer rate for general material with same rare earth ion's concentration is about 1.194x10(5)s(-1). These are the reason to emerge the unusual intensity reverse phenomenon in Er(0.5)Yb(3):FOV.

  16. [Stabilization of Cadmium Contaminated Soils by Ferric Ion Modified Attapulgite (Fe/ATP)--Characterizations and Stabilization Mechanism].

    PubMed

    Rong, Yang; Li, Rong-bo; Zhou, Yong-li; Chen, Jing; Wang, Lin-ling; Lu, Xiao-hua

    2015-08-01

    Ferric ion modified attapulgite (Fe/ATP) was prepared by impregnation and its structure and morphology were characterized. The toxicity characteristic leaching procedure (TCLP) was used to evaluate the effect of Cadmium( Cd) stabilization in soil with the addition of attapulgite (ATP) and Fe/ATP. The stabilization mechanism of Cd was further elucidated by comparing the morphologies and structure of ATP and Fe/ATP before and after Cd adsorption. Fe/ATP exhibited much better adsorption capacity than ATP, suggesting different adsorption mechanisms occurred between ATP and Fe/ATP. The leaching concentrations of Cd in soil decreased by 45% and 91% respectively, with the addition of wt. 20% ATP and Fe/ATP. The former was attributed to the interaction between Cd2 and --OH groups by chemical binding to form inner-sphere complexes in ATP and the attachment between Cd2+ and the defect sites in ATP framework. Whereas Cd stabilization with Fe/ATP was resulted from the fact that the active centers (--OH bonds or O- sites) on ATP could react with Fe3+ giving Fe--O--Cd-- bridges, which helped stabilize Cd in surface soil. What'more, the ferric oxides and metal hydroxides on the surface of ATP could interact with Cd, probably by the formation of cadmium ferrite. In conclusion, Fe/ATP, which can be easily prepared, holds promise as a potential low-cost and environmental friendly stabilizing agent for remediation of soil contaminated with heavy metals.

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

    SciTech Connect

    Lauff, J.J.; Coogan, L.A.; Breitfeller, J.M. ); Steele, D.B. )

    1990-11-01

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

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

    PubMed

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

    2008-05-01

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

  19. 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...

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

    USGS Publications Warehouse

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

    1997-01-01

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

  1. Multidomain Human Peroxidasin 1 Is a Highly Glycosylated and Stable Homotrimeric High Spin Ferric Peroxidase*

    PubMed Central

    Soudi, Monika; Paumann-Page, Martina; Delporte, Cedric; Pirker, Katharina F.; Bellei, Marzia; Edenhofer, Eva; Stadlmayr, Gerhard; Battistuzzi, Gianantonio; Boudjeltia, Karim Zouaoui; Furtmüller, Paul G.; Van Antwerpen, Pierre; Obinger, Christian

    2015-01-01

    Human peroxidasin 1 (hsPxd01) is a multidomain heme peroxidase that uses bromide as a cofactor for the formation of sulfilimine cross-links. The latter confers critical structural reinforcement to collagen IV scaffolds. Here, hsPxd01 and various truncated variants lacking nonenzymatic domains were recombinantly expressed in HEK cell lines. The N-glycosylation site occupancy and disulfide pattern, the oligomeric structure, and unfolding pathway are reported. The homotrimeric iron protein contains a covalently bound ferric high spin heme per subunit with a standard reduction potential of the Fe(III)/Fe(II) couple of −233 ± 5 mV at pH 7.0. Despite sequence homology at the active site and biophysical properties similar to human peroxidases, the catalytic efficiency of bromide oxidation (kcat/KMapp) of full-length hsPxd01 is rather low but increased upon truncation. This is discussed with respect to its structure and proposed biosynthetic function in collagen IV cross-linking. PMID:25713063

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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, Δ E a, Δ H #, Δ S #, Δ G ≠, for the reaction were calculated by using Arrhenius and Eyring plot. Surface excess concentration (Γmax), minimum area per surfactant molecule ( A min), average area occupied by each molecule of surfactant ( a), surface pressure at the CMC (Πmax), Gibb's energy of micellization (Δ G M°), Gibb's energy of adsorption (Δ 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.

  3. Near the Ferric Pseudobrookite Composition (Fe2TiO5).

    PubMed

    Seitz, Guillaume; Penin, Nicolas; Decoux, Léa; Wattiaux, Alain; Duttine, Mathieu; Gaudon, Manuel

    2016-03-01

    Because of a very low thermodynamic stability, obtaining a pure monophasic compound of ferric pseudobrookite is quite difficult to achieve. Indeed, the low reticular energy of this phase leads easily to its decomposition and the occurrence of the secondary phases: hematite (Fe2O3) and/or rutile (TiO2). Samples with global composition Fe2-xTi1+xO5 (x = 0, 0.05, and 0.10) have been synthesized by the Pechini route and, thereafter, thermally treated at different temperatures. The concentrations of Fe2O3 and TiO2 secondary phases were accurately determined and correlated with the target compositions and the synthesis parameters, especially the thermal treatment temperature. As revealed by Mössbauer spectroscopy, all iron ions are at the III+ oxidation state. Thus, the formation of hematite or rutile as a secondary phase may be related to the occurrence of cationic vacancies within the pseudobrookite structure, with the amount of vacancies depending on the annealing temperature. In light of the presented results, it appears unreasonable to propose a "fixed" binary phase diagram for such a complex system. Furthermore, the occurrence of cationic vacancies induces a coloration change (darkening), preventing any industrial use of this reddish-brown pseudobrookite as a ceramic pigment. PMID:26866894

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

    PubMed

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

    2008-07-01

    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 gain an understanding of the adsorption process kinetics, a detailed study was conducted in a controlled batch system. The effects of temperature and pH on the adsorption rates of arsenic (V) and arsenic (III) were investigated. Reaction rate constants were calculated at pH levels of 6.5 and 7.5. Rate data are best described by a pseudo first-order kinetic model at each temperature and pH condition studied. At lower pH values, arsenic (V) exhibits greater removal rates than arsenic (III). An increase in temperature increases the overall adsorption reaction rate constant values for both arsenic (V) and arsenic (III). An examination of thermodynamic parameters shows that the adsorption of arsenic (V) as well as arsenic (III) by GFH is an endothermic process and is spontaneous at the specific temperatures investigated.

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

    NASA Astrophysics Data System (ADS)

    Jaén, Juan A.; Navarro, César

    2009-07-01

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

  6. Biogenic catalysis of soil formation on Mars?

    PubMed

    Bishop, J L

    1998-10-01

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

  7. Biogenic catalysis of soil formation on Mars?

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.

    1998-01-01

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

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

    PubMed

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

    2014-11-19

    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 component, 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, Δ < 0.0701 u (b) transition regime, 0.0701 u ≤ Δ ≤ 0.0916 u and (c) thick coating regime, Δ > 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 < Δ < 7.0 nm transition regime, 7.0 < Δ < 9.2 nm and thick coating, Δ > 9.2 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    Triacylglycerols (TAGs) are biologically important molecules which form crystalline nanoplatelets (CNPs) and, ultimately, fat crystal networks in edible oils. Characterizing the self-assembled hierarchies of these networks is important to understanding their functionality and oil binding capacity. We have modelled CNPs in multicomponent oils and studied their aggregation. The oil comprises (a) a liquid componentt, and (b) components which phase separately on a nano-scale (nano-phase separation) to coat the surfaces of the CNPs impenetrably, either isotropically or anisotropically, with either liquid-like coatings or crystallites, forming a coating of thickness Δ. 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, Δ \\lt 0.0701 u (b) transition regime, 0.0701 u≤slant Δ ≤slant 0.0916 u and (c) thick coating regime, Δ \\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 Δ \\lt 7.0 \\text{nm} transition regime, 7.0\\ltΔ \\lt 9.2 \\text{nm} and thick coating, Δ \\gt 9.2 \\text{nm} (5) The minimum minority TAG concentration required to undergo nano-phase separation is, approximately, 0.29% (thin

  10. Ferric Phosphate Hydroxide Microstructures Affect Their Magnetic Properties.

    PubMed

    Zhao, Junhong; Zhang, Youjuan; Run, Zhen; Li, Pengwei; Guo, Qifei; Pang, Huan

    2015-06-01

    Uniformly sized and shape-controlled nanoparticles are important due to their applications in catalysis, electrochemistry, ion exchange, molecular adsorption, and electronics. Several ferric phosphate hydroxide (Fe4(OH)3(PO4)3) microstructures were successfully prepared under hydrothermal conditions. Using controlled variations in the reaction conditions, such as reaction time, temperature, and amount of hexadecyltrimethylammonium bromide (CTAB), the crystals can be grown as almost perfect hyperbranched microcrystals at 180 °C (without CTAB) or relatively monodisperse particles at 220 °C (with CTAB). The large hyperbranched structure of Fe4(OH)3(PO4)3 with a size of ∼19 μm forms with the "fractal growth rule" and shows many branches. More importantly, the magnetic properties of these materials are directly correlated to their size and micro/nanostructure morphology. Interestingly, the blocking temperature (T B) shows a dependence on size and shape, and a smaller size resulted in a lower T B. These crystals are good examples that prove that physical and chemical properties of nano/microstructured materials are related to their structures, and the precise control of the morphology of such functional materials could allow for the control of their performance.

  11. Defluoridation from aqueous solutions by granular ferric hydroxide (GFH).

    PubMed

    Kumar, Eva; Bhatnagar, Amit; Ji, Minkyu; Jung, Woosik; Lee, Sang-Hun; Kim, Sun-Joon; Lee, Giehyeon; Song, Hocheol; Choi, Jae-Young; Yang, Jung-Seok; Jeon, Byong-Hun

    2009-02-01

    This research was undertaken to evaluate the feasibility of granular ferric hydroxide (GFH) for fluoride removal from aqueous solutions. Batch experiments were performed to study the influence of various experimental parameters such as contact time (1 min-24h), initial fluoride concentration (1-100 mgL(-1)), temperature (10 and 25 degrees C), pH (3-12) and the presence of competing anions on the adsorption of fluoride on GFH. Kinetic data revealed that the uptake rate of fluoride was rapid in the beginning and 95% adsorption was completed within 10 min and equilibrium was achieved within 60 min. The sorption process was well explained with pseudo-first-order and pore diffusion models. The maximum adsorption capacity of GFH for fluoride removal was 7.0 mgg(-1). The adsorption was found to be an endothermic process and data conform to Langmuir model. The optimum fluoride removal was observed between pH ranges of 4-8. The fluoride adsorption was decreased in the presence of phosphate followed by carbonate and sulphate. Results from this study demonstrated potential utility of GFH that could be developed into a viable technology for fluoride removal from drinking water.

  12. Localized corrosion of candidate container materials in ferric chloride solutions

    SciTech Connect

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

    1998-10-01

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

  13. Exfoliation of Hexagonal Boron Nitride via Ferric Chloride Intercalation

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    PubMed

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

    2010-09-01

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

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

    PubMed

    Ansari, Azaj; Kaushik, Abhishek; Rajaraman, Gopalan

    2013-03-20

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

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

    PubMed Central

    Santiago, Palacios

    2012-01-01

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

  18. Graphene-supported ferric porphyrin as a peroxidase mimic for electrochemical DNA biosensing.

    PubMed

    Wang, Quanbo; Lei, Jianping; Deng, Shengyuan; Zhang, Lei; Ju, Huangxian

    2013-01-30

    A novel peroxidase mimic was designed by loading ferric porphyrin and streptavidin onto graphene, which was used to recognize a biotinylated molecular beacon for specific electrochemical detection of DNA down to attomolar levels.

  19. [Arsenic (V) removal from drinking water by ferric salt and aluminum salt coagulation/microfiltration process].

    PubMed

    Li, Xiao-bo; Wu, Shui-bo; Gu, Ping

    2007-10-01

    Two lab-scale coagulation/microfiltration membrane reactors were used to compare the arsenic removal from drinking water by ferric salt and aluminum salt coagulation/microfiltration process. FeCl3 and Al2(SO4)3 were appointed as the coagulants. The results show that the arsenic removal efficiency of the two processes are almost equal. Arsenic concentration can be lowered from about 100 microg/L to below 10 microg/L and the lowest is 1.68 microg x L(-1). All of the turbidity of the treated water is less than 0.1 NTU. The concentrations of ferric, aluminum and SO4(2-) of the treated water are entirely satisfied the standard of drinking water. After treated by ferric salt process, pH value of the treated water is increased about 0.5. However, aluminum salt process does not change pH of the drinking water. The concentration ratio of the ferric salt process is 1,791 which is about 2.54 times of the aluminum salt process. Arsenic concentration of the sludge of ferric salt process is also higher greatly than that of the aluminum salt process. Therefore, the volume of the sludge produced by the ferric salt process is smaller than that of the aluminum salt process when equal amount of drinking water was treated. Accordingly, ferric salt process should be used when only high concentration arsenic existed in drinking water. On the other hand, fluoride also can be removed simultaneously while arsenic was removed by aluminum salt process. The amount of coagulant needed is the amount of coagulant required to remove fluoride separately. Fluoride can not be removed from drinking water by the ferric salt process. It was concluded that aluminum salt process should be used to remove arsenic and fluoride simultaneously from high arsenic and high fluoride coexisted drinking water.

  20. Nanophase segregation and water dynamics in the dendrion diblock copolymer formed from the Fréchet polyaryl ethereal dendrimer and linear PTFE.

    PubMed

    Jang, Seung Soon; Lin, Shiang-Tai; Cagin, Tahir; Molinero, Valeria; Goddard, William A

    2005-05-26

    We propose a new material consisting of a dendrion copolymer formed from (a) a water-soluble dendritic polymer and (b) a hydrophobic backbone. Using molecular dynamics simulations techniques, we determine the structure and dynamics of the dendrion formed by second-generation Fréchet polyaryl ethereal dendrimer as the hydrophilic component and linear polytetrafluoroethylene (PTFE) as the hydrophobic polymer, with 5 and 10 wt % of water. We find that this material produces a well-developed nanoscale structure in which water forms a continuous nanophase, making this new family of compounds promising candidates for applications in fuel cell membranes. We find that the water molecules are incorporated into the dendrimer block of the copolymer to form a nanophase-segregated structure. The well-developed nanophase-segregated structures rendered by this material have characteristic dimensions of segregation ( approximately 30 Angstrom) and dendrimer conformational properties that are independent of water content. Calculations of water dynamics and proton transport in these nanophase-segregated structures indicate that the dendrion copolymer membrane with 10 wt % of water content has a water structure and transport properties equivalent to that of the hydrated Nafion membrane with 20 wt % of water content.

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

    NASA Astrophysics Data System (ADS)

    Kozak, John J.; Nicolis, G.

    2011-02-01

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

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

    PubMed

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

    2010-04-01

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

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

    PubMed

    Kozak, John J; Nicolis, G

    2011-02-14

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

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

    PubMed

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

    2008-02-21

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2013-02-01

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

  7. Ferric gluconate reduces epoetin requirements in hemodialysis patients with elevated ferritin.

    PubMed

    Kapoian, Toros; O'Mara, Neeta B; Singh, Ajay K; Moran, John; Rizkala, Adel R; Geronemus, Robert; Kopelman, Robert C; Dahl, Naomi V; Coyne, Daniel W

    2008-02-01

    The Dialysis Patients Response to IV Iron with Elevated Ferritin (DRIVE) study demonstrated the efficacy of intravenous ferric gluconate to improve hemoglobin levels in anemic hemodialysis patients who were receiving adequate epoetin doses and who had ferritin levels between 500 and 1200 ng/ml and transferrin saturation (TSAT) < or = 25%. The DRIVE-II study reported here was a 6-wk observational extension designed to investigate how ferric gluconate impacted epoetin dosage after DRIVE. During DRIVE-II, treating nephrologists and anemia managers adjusted doses of epoetin and intravenous iron as clinically indicated. By the end of observation, patients in the ferric gluconate group required significantly less epoetin than their DRIVE dose (mean change of -7527 +/- 18,021 IU/wk, P = 0.003), whereas the epoetin dose essentially did not change for patients in the control group (mean change of 649 +/- 19,987 IU/wk, P = 0.809). Mean hemoglobin, TSAT, and serum ferritin levels remained higher in the ferric gluconate group than in the control group (P = 0.062, P < 0.001, and P = 0.014, respectively). Over the entire 12-wk study period (DRIVE plus DRIVE-II), the control group experienced significantly more serious adverse events than the ferric gluconate group (incidence rate ratio = 1.73, P = 0.041). In conclusion, ferric gluconate maintains hemoglobin and allows lower epoetin doses in anemic hemodialysis patients with low TSAT and ferritin levels up to 1200 ng/ml. PMID:18216316

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

    NASA Astrophysics Data System (ADS)

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

    1993-02-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  10. Concentration of MS2 phage in river water by a combined ferric colloid adsorption and foam separation-based method, with MS2 phage leaching from ferric colloid.

    PubMed

    Suzuki, Yoshihiro; Kobayashi, Takumi; Nishiyama, Masateru; Kono, Tomoya

    2016-08-01

    The concentration of MS2 phage as a model RNA virus in river water using a combined ferric colloid adsorption and foam separation-based method was examined. The MS2 phage concentrations were determined by the plaque-forming unit (PFU) method and reverse transcription quantitative PCR (RT-qPCR) analysis. When ferric colloid adsorption was performed prior to foam separation, MS2 phage was effectively removed from river water and concentrated in the generated foam within 7 min. The removal efficiency was >99% at the optimum iron and casein concentrations of 5 mg-Fe/L and 10 mg/L, respectively. Furthermore, based on the analysis of the collected ferric colloid dissolved using deferoxamine, the MS2 concentration in the colloid-dissolved solution was 190-fold higher than that found in raw water according to RT-qPCR analysis. This is a novel method for concentrating RNA viruses to facilitate their detection in river water using coagulation and foam separation combined with chelate dissolution of ferric flocs.

  11. Concentration of MS2 phage in river water by a combined ferric colloid adsorption and foam separation-based method, with MS2 phage leaching from ferric colloid.

    PubMed

    Suzuki, Yoshihiro; Kobayashi, Takumi; Nishiyama, Masateru; Kono, Tomoya

    2016-08-01

    The concentration of MS2 phage as a model RNA virus in river water using a combined ferric colloid adsorption and foam separation-based method was examined. The MS2 phage concentrations were determined by the plaque-forming unit (PFU) method and reverse transcription quantitative PCR (RT-qPCR) analysis. When ferric colloid adsorption was performed prior to foam separation, MS2 phage was effectively removed from river water and concentrated in the generated foam within 7 min. The removal efficiency was >99% at the optimum iron and casein concentrations of 5 mg-Fe/L and 10 mg/L, respectively. Furthermore, based on the analysis of the collected ferric colloid dissolved using deferoxamine, the MS2 concentration in the colloid-dissolved solution was 190-fold higher than that found in raw water according to RT-qPCR analysis. This is a novel method for concentrating RNA viruses to facilitate their detection in river water using coagulation and foam separation combined with chelate dissolution of ferric flocs. PMID:26868517

  12. Impedance spectroscopy and mechanical response of porous nanophase hydroxyapatite-barium titanate composite.

    PubMed

    Dubey, Ashutosh Kumar; Kakimoto, Ken-ichi

    2016-06-01

    The present study aims to develop the porous nanophase hydroxyapatite (HA)-barium titanate (BT) composite with reasonable mechanical and electrical properties as an electrically-active prosthetic orthopedic implant alternate. The porous samples (densification ~40-70%) with varying amounts of BT (0, 25, 35 and 100 vol.%) in HA were synthesized using optimal spark plasma sintering conditions, which revealed the thermochemical stability between both the phases. The reasonably good combination of functional properties such as compressive [(236.00 ± 44.90)MPa] and flexural [(56.18 ± 5.82) MPa] strengths, AC conductivity [7.62 × 10(-9)(ohm-cm)(-1) at 10 kHz] and relative permittivity [15.20 at 10 kHz] have been achieved with nanostructured HA-25 vol.% BT composite as far as significant sample porosity (~30%) is concerned. Detailed impedance spectroscopic analysis was performed to reveal the electrical microstructure of developed porous samples. The resistance and capacitance values (at 500 °C) of grain (RG, CG) and grain boundary (RGB, CGB) for the porous HA-25 vol.% BT composite are (1.3 × 10(7) ohm, 3.1 × 10(-11)F) and (1.6 × 10(7) ohm, 5.9 × 10(-10)F), respectively. Almost similar value of activation energy (~1-1.5 eV) for grain and grain boundary has been observed for all the samples. The mechanism of conduction is found to be same for porous monolithic HA as well as composite samples. Relaxation spectroscopic analyses suggest that both the localized as well as long range charge carrier translocations are responsible for conduction in these samples. The degree of polarization of porous samples has been assessed by measuring thermally stimulated depolarization current of the poled samples. The depolarization current is observed to depend on the heating rate. The maximum current density, measured for HA-25 vol.% BT sample at a heating rate of 1 °C/min is 2.7 nA/cm(2). Formation of oxygen vacancies due to the reduced atmosphere sintering contribute to the space

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

    PubMed

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

    2008-05-12

    Ferric hexacyanoferrate (Fe4III[FeII(CN)6]3), also known as insoluble Prussian blue (PB) is the active pharmaceutical ingredient (API) of the drug product, Radiogardase. Radiogardase is the first FDA approved medical countermeasure for the treatment of internal contamination with radioactive cesium (Cs) or thallium in the event of a major radiological incident such as a "dirty bomb". A number of pre-clinical and clinical studies have evaluated the use of PB as an investigational decorporation agent to enhance the excretion of metal cations. There are few sources of published in vitro data that detail the binding capacity of cesium to insoluble PB under various chemical and physical conditions. The study objective was to determine the in vitro binding capacity of PB APIs and drug products by evaluating certain chemical and physical factors such as medium pH, particle size, and storage conditions (temperature). In vitro experimental conditions ranged from pH 1 to 9, to cover the range of pH levels that PB may encounter in the gastrointestinal (GI) tract in humans. Measurements of cesium binding were made between 1 and 24h, to cover gastric and intestinal tract residence time using a validated atomic emission spectroscopy (AES) method. The results indicated that pH, exposure time, storage temperature (affecting moisture content) and particle size play significant roles in the cesium binding to both the PB API and the drug product. The lowest cesium binding was observed at gastric pH of 1 and 2, whereas the highest cesium binding was observed at physiological pH of 7.5. It was observed that dry storage conditions resulted in a loss of moisture from PB, which had a significant negative effect on the PB cesium binding capacity at time intervals consistent with gastric residence. Differences were also observed in the binding capacity of PB with different particle sizes. Significant batch to batch differences were also observed in the binding capacity of some PB API and

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

    PubMed

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

    2008-05-12

    Ferric hexacyanoferrate (Fe4III[FeII(CN)6]3), also known as insoluble Prussian blue (PB) is the active pharmaceutical ingredient (API) of the drug product, Radiogardase. Radiogardase is the first FDA approved medical countermeasure for the treatment of internal contamination with radioactive cesium (Cs) or thallium in the event of a major radiological incident such as a "dirty bomb". A number of pre-clinical and clinical studies have evaluated the use of PB as an investigational decorporation agent to enhance the excretion of metal cations. There are few sources of published in vitro data that detail the binding capacity of cesium to insoluble PB under various chemical and physical conditions. The study objective was to determine the in vitro binding capacity of PB APIs and drug products by evaluating certain chemical and physical factors such as medium pH, particle size, and storage conditions (temperature). In vitro experimental conditions ranged from pH 1 to 9, to cover the range of pH levels that PB may encounter in the gastrointestinal (GI) tract in humans. Measurements of cesium binding were made between 1 and 24h, to cover gastric and intestinal tract residence time using a validated atomic emission spectroscopy (AES) method. The results indicated that pH, exposure time, storage temperature (affecting moisture content) and particle size play significant roles in the cesium binding to both the PB API and the drug product. The lowest cesium binding was observed at gastric pH of 1 and 2, whereas the highest cesium binding was observed at physiological pH of 7.5. It was observed that dry storage conditions resulted in a loss of moisture from PB, which had a significant negative effect on the PB cesium binding capacity at time intervals consistent with gastric residence. Differences were also observed in the binding capacity of PB with different particle sizes. Significant batch to batch differences were also observed in the binding capacity of some PB API and

  15. Hydrogen sulfide attenuates ferric chloride-induced arterial thrombosis in rats.

    PubMed

    Qin, Yi-Ren; You, Shou-Jiang; Zhang, Yan; Li, Qian; Wang, Xian-Hui; Wang, Fen; Hu, Li-Fang; Liu, Chun-Feng

    2016-06-01

    Hydrogen sulfide (H2S) is a novel gaseous transmitter, regulating a multitude of biological processes in the cardiovascular and other systems. However, it remains unclear whether it exerts any effect on arterial thrombosis. In this study, we examined the effect of H2S on ferric chloride (FeCl3)-induced thrombosis in the rat common carotid artery (CCA). The results revealed a decrease of the H2S-producing enzyme cystathionine γ-lyase (CSE) expression and H2S production that persisted until 48 h after FeCl3 application. Intriguingly, administration with NaHS at appropriate regimen reduced the thrombus formation and enhanced the blood flow, accompanied with the alleviation of CSE and CD31 downregulation, and endothelial cell apoptosis in the rat CCA following FeCl3 application. Moreover, the antithrombotic effect of H2S was also observed in Rose Bengal photochemical model in which the development of thrombosis is contributed by oxidative injury to the endothelium. The in vitro study demonstrated that the mRNA and protein expression of CSE, as well as H2S production, was decreased in hydrogen peroxide (H2O2)-treated endothelial cells. Exogenous supplement of NaHS and CSE overexpression consistently alleviated the increase of cleaved caspase-3 and endothelial cell damage caused by H2O2. Taken together, our findings suggest that endogenous H2S generation in the endothelium may be impaired during arterial thrombosis and that modulation of H2S, either exogenous supplement or boost of endogenous production, may become a potential venue for arterial thrombosis therapy.

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

    PubMed

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

    2014-04-30

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

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

    PubMed

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

    2013-12-31

    Vc H-NOX (or VCA0720) is an H-NOX (heme-nitric oxide and oxygen binding) protein from facultative aerobic bacterium Vibrio cholerae. It shares significant sequence homology with soluble guanylyl cyclase (sGC), a NO sensor protein commonly found in animals. Similar to sGC, Vc H-NOX binds strongly to NO and CO with affinities of 0.27 nM and 0.77 μM, 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.

  18. Microbial acquisition of iron from ferric iron bearing minerals

    SciTech Connect

    Hersman, L.E.; Sposito, G.

    1998-12-31

    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.

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

    PubMed

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

    2007-07-15

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

  20. Increased osteoblast and decreased Staphylococcus epidermidis functions on nanophase ZnO and TiO2.

    PubMed

    Colon, Gabriel; Ward, Brian C; Webster, Thomas J

    2006-09-01

    Many engineers and surgeons trace implant failure to poor osseointegration (or the bonding of an orthopedic implant to juxtaposed bone) and/or bacteria infection. By using novel nanotopographies, researchers have shown that nanostructured ceramics, carbon fibers, polymers, metals, and composites enhance osteoblast adhesion and calcium/phosphate mineral deposition. However, the function of bacteria on materials with nanostructured surfaces remains largely uninvestigated. This is despite the fact that during normal surgical insertion of an orthopedic implant, bacteria from the patient's own skin and/or mucosa enters the wound site. These bacteria (namely, Staphylococcus epidermidis) irreversibly adhere to an implant surface while various physiological stresses induce alterations in the bacterial growth rate leading to biofilm formation. Because of their integral role in determining the success of orthopedic implants, the objective of this in vitro study was to examine the functions of (i) S. epidermidis and (ii) osteoblasts (or bone-forming cells) on ZnO and titania (TiO(2)), which possess nanostructured compared to microstructured surface features. ZnO is a well-known antimicrobial agent and TiO(2) readily forms on titanium once implanted. Results of this study provided the first evidence of decreased S. epidermidis adhesion on ZnO and TiO(2) with nanostructured when compared with microstructured surface features. Moreover, compared with microphase formulations, results of this study showed increased osteoblast adhesion, alkaline phosphatase activity, and calcium mineral deposition on nanophase ZnO and TiO(2). In this manner, this study suggests that nanophase ZnO and TiO(2) may reduce S. epidermidis adhesion and increase osteoblast functions necessary to promote the efficacy of orthopedic implants.

  1. Quantifying the VNIR Effects of Nanophase Iron Generated through the Space Weathering of Silicates: Reconciling Modeled Data with Laboratory Observations

    NASA Astrophysics Data System (ADS)

    Legett, C., IV; Glotch, T. D.; Lucey, P. G.

    2015-12-01

    Space weathering is a diverse set of processes that occur on the surfaces of airless bodies due to exposure to the space environment. One of the effects of space weathering is the generation of nanophase iron particles in glassy rims on mineral grains due to sputtering of iron-bearing minerals. These particles have a size-dependent effect on visible and near infrared (VNIR) reflectance spectra with smaller diameter particles (< 50 nm) causing both reddening and darkening of the spectra with respect to unweathered material (Britt-Pieters particle behavior), while larger particles (> 300 nm) darken without reddening. Between these two sizes, a gradual shift between these two behaviors occurs. In this work, we present results from the Multiple Sphere T-Matrix (MSTM) scattering model in combination with Hapke theory to explore the particle size and iron content parameter spaces with respect to VNIR (700-1700 nm) spectral slope. Previous work has shown that the MSTM-Hapke hybrid model offers improvements over Mie-Hapke models. Virtual particles are constructed out of an arbitrary number of spheres, and each sphere is assigned a refractive index and extinction coefficient for each wavelength of interest. The model then directly solves Maxwell's Equations at every wave-particle interface to predict the scattering, extinction and absorption efficiencies. These are then put into a simplified Hapke bidirectional reflectance model that yields a predicted reflectance. Preliminary results show an area of maximum slopes for iron particle diameters < 80 nm and iron concentrations of ~1-10wt% in an amorphous silica matrix. Further model runs are planned to better refine the extent of this region. Companion laboratory work using mixtures of powdered aerogel and nanophase iron particles provides a point of comparison to modeling efforts. The effects on reflectance and emissivity values due to particle size in a nearly ideal scatterer (aerogel) are also observed with comparisons to

  2. Equilibrium Iron Isotopic Fractionation Among Ferric Chloride Complexes

    NASA Astrophysics Data System (ADS)

    Hill, P. S.; Schauble, E. A.

    2006-12-01

    Four sets of ab initio models, including Unrestricted Hartree Fock (UHF) and hybrid Density Function Theory (DFT) were calculated for each species in a series of aqueous ferric chloride complexes: (FeH2O)6{3+, FeCl(H2O)5{2+, FeCl2(H2O)4{+, FeCl3(H2O)3, FeCl3(H2O)2, FeCl4{-, FeCl5H2O{2-, FeCl5{2-, FeCl6{^{3-}) in order to determine the relative isotopic fractionation among the complexes, to compare the results of different models for the same complexes, and to examine factors that influence the magnitude of the isotopic fractionation. Relative to Fe(H2O)6{3+, all models show a nearly linear decrease in the isotopic fractionation factor as the number of Cl{- ions per Fe{3+ ion increases, with slopes of -0.8‰ to - 1.0‰ per Cl-. At 20°C, 1000 ln β56-54 (β = reduced partition function ratio relative to a dissociated Fe atom) values range from 8.93 to 9.73‰ for Fe(H2O)6{3+, 8.04 to 9.12‰ for FeCl(H2O)5{2+, 7.61 to 8.73‰ for FeCl2(H2O)4{+, 7.14 to 8.25‰ for FeCl4{-, and 3.09 to 4.41‰ for FeCl6{^{3-}. The fractionation between Fe(H2O)6{3+ and FeCl4{- ranges from 1.48 to 2.45‰, depending on the model; this is comparable to fractionation effects due to iron redox reactions. β56-54 values from the UHF models are consistently higher than those from the hybrid DFT models. Theoretical studies predict isotopic fractionation due to differences in ligand bond stiffness, coordination number, bond length, and the frequency of the asymmetric Fe-X stretching vibrational mode (Schauble et al., 2001, Geochim. et Cosmochim. Acta, 65, 15, 2487-2497; Schauble, 2004, in Reviews in Mineralogy & Geochemistry, 55, 65-111). Complexes with more Fe-OH2 bonds (see above) and/or smaller coordination numbers have higher fractionation factors (7.43‰, 4.91‰, 3.94‰ for FeCl4{-, FeCl5{2-, FeCl6{^{3-} respectively from the UHF model). The length of the Fe-Cl bonds increases as the number of chloride ligands increases while the Fe-O bond lengths decrease as the number of H2O

  3. Sequence diversity and enzyme activity of ferric-chelate reductase LeFRO1 in tomato.

    PubMed

    Kong, Danyu; Chen, Chunlin; Wu, Huilan; Li, Ye; Li, Junming; Ling, Hong-Qing

    2013-11-20

    Ferric-chelate reductase which functions in the reduction of ferric to ferrous iron on root surface is a critical protein for iron homeostasis in strategy I plants. LeFRO1 is a major ferric-chelate reductase involved in iron uptake in tomato. To identify the natural variations of LeFRO1 and to assess their effect on the ferric-chelate reductase activity, we cloned the coding sequences of LeFRO1 from 16 tomato varieties collected from different regions, and detected three types of LeFRO1 (LeFRO1(MM), LeFRO1(Ailsa) and LeFRO1(Monita)) with five amino acid variations at the positions 21, 24, 112, 195 and 582. Enzyme activity assay revealed that the three types of LeFRO1 possessed different ferric-chelate reductase activity (LeFRO1(Ailsa) > LeFRO1(MM) > LeFRO1(Monita)). The 112th amino acid residue Ala of LeFRO1 is critical for maintaining the high activity of ferric-chelate reductase, because modification of this amino acid resulted in a significant reduction of enzyme activity. Further, we showed that the combination of the amino acid residue Ile at the site 24 with Lys at the site 582 played a positive role in the enzyme activity of LeFRO1. In conclusion, the findings are helpful to understand the natural adaptation mechanisms of plants to iron-limiting stress, and may provide new knowledge to select and manipulate LeFRO1 for improving the iron deficiency tolerance in tomato.

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

    PubMed

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

    2013-06-01

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

  5. Experimental Spinel Standards for Ferric Iron (Fe3+) Determination During Peridotite Partial Melting

    NASA Astrophysics Data System (ADS)

    Wenz, M. D.; Sorbadere, F.; Rosenthal, A.; Frost, D. J.; McCammon, C. A.

    2014-12-01

    The presence of ferric iron (Fe3+) in the mantle plays a significant role in the oxygen fugacity (fO2) of the Earth's interior. This has a wide range of implications for Earth related processes ranging from the composition of the atmosphere to magmatic phase relations during melting and crystallization processes [1]. A major source of Earth's mantle magmas is spinel peridotite. Despite its low abundance, spinel (Fe3+/ƩFe = 15-34%, [2]) is the main contributor of Fe3+to the melt upon partial melting. Analyses of Fe3+ on small areas of spinel and melt are required to study the Fe3+ behavior during partial melting of spinel peridotite. Fe K-edge X-ray Absorption Near Edge Structure (XANES) combines both high precision and small beam size, but requires standards with a wide range of Fe3+ content to obtain good calibration. Glasses with varying Fe3+ content are easily synthesized [3, 4]. Spinel, however, presents a challenge for experimental standards due to the low diffusion of Cr and Al preventing compositional homogeneity. Natural spinel standards are often used, but only cover a narrow Fe3+ range. Thus, there is a need for better experimental spinel standards over a wider range of fO2. Our study involves making experimental mantle spinels with variable Fe3+ content. We used a sol-gel auto-combustion method to synthesize our starting material [5]. FMQ-2, FMQ+0, and air fO2 conditions were established using a gas mixing furnace. Piston cylinder experiments were performed at 1.5GPa, and 1310 -1370°C to obtain solid material for XANES. To maintain distinct oxidizing conditions, three capsules were used: graphite for reduced, Re for intermediate and AuPd for oxidized conditions. The spinels were analyzed by Mössbauer spectroscopy. Fe3+/ƩFe ranged from 0.3 to 0.6. These values are consistent with the Fe edge position obtained using XANES analyses, between 7130 and 7132 eV, respectively. Our spinels are thus suitable standards for Fe3+ measurements in peridotite

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

    PubMed

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

    2010-06-24

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

  7. Effects of phosphate and silicate on the transformation of hydroxycarbonate green rust to ferric oxyhydroxides

    NASA Astrophysics Data System (ADS)

    Feng, Xionghan; Wang, Xiaoming; Zhu, Mengqiang; Koopal, Luuk K.; Xu, Huanhuan; Wang, Yan; Liu, Fan

    2015-12-01

    Hydroxycarbonate green rust (GR1(CO32-)) was prepared by oxidation of aerated aqueous suspensions of Fe(II) hydroxide, and the presence of light promoted the transformation of GR1(CO32-) by dissolved O2 at pH 7.8 and 25 °C. Further transformation of GR1(CO32-) in the light was conducted in the presence of orthophosphate (P) or silicate (Si) anions, followed by solution analysis and solid product characterization using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). Results show that both P and Si anions significantly affect the transformation of GR1(CO32-) through adsorption on the intermediate products. The time required for complete GR1(CO32-) transformation and the phases, crystallinity and morphology of the transformation products all depend on the Fe/anion molar ratio. When compared to the control, the transformation can be promoted by low Si concentrations but retarded by P. With decreasing Fe/P ratio, the products change from acicular goethite (absence of P) to tabular lepidocrocite (Fe/P: 120-48) and to mixed phases of platelets of ferric GR1(CO32-) (EX-GR1) and minor ferrihydrite (Fe/P: 24-3). In terms of Si, the products are goethites when the Fe/Si ratio of 48-12, and with increasing ratio, the goethite crystallinity and particle size decrease and the morphology changes from acicular (absence of Si) to plate-like or isodimensional particles. The goethite morphology at low Fe/Si ratios is comparable to natural goethite samples commonly found in soils. At Fe/Si = 3, the products are EX-GR1 platelets with minor ferrihydrite coexisting. The likely pathway of the oxidative GR1(CO32-) transformation in the control system and in the presence of low concentrations of Si (Fe/Si ⩾ 12) is GR1(CO32-) → amorphous γ-FeOOH-like phase → α-FeOOH via a dissolution-oxidation-precipitation mechanism. In addition, Fe(II) released during dissolution of GR1(CO32-) is adsorbed on the products and the

  8. A novel mode of ferric ion coordination by the periplasmic ferric ion-binding subunit FbpA of an ABC-type iron transporter from Thermus thermophilus HB8.

    PubMed

    Wang, Shipeng; Ogata, Misaki; Horita, Shoichiro; Ohtsuka, Jun; Nagata, Koji; Tanokura, Masaru

    2014-01-01

    Crystal structures of FbpA, the periplasmic ferric ion-binding protein of an iron-uptake ABC transporter, from Thermus thermophilus HB8 (TtFbpA) have been solved in apo and ferric ion-bound forms at 1.8 and 1.7 Å resolution, respectively. The latter crystal structure shows that the bound ferric ion forms a novel six-coordinated complex with three tyrosine side chains, two bicarbonates and a water molecule in the metal-binding site. The results of gel-filtration chromatography and dynamic light scattering show that TtFbpA exists as a monomer in solution regardless of ferric ion binding and that TtFbpA adopts a more compact conformation in the ferric ion-bound state than in the apo state in solution.

  9. Chemical, physical, and sensory characteristics of mozzarella cheese fortified using protein-chelated iron or ferric chloride.

    PubMed

    Rice, W H; McMahon, D J

    1998-02-01

    Mozzarella cheese containing 25 and 50 mg of iron/kg of cheese was manufactured from milk that had been fortified with casein-chelated iron, whey protein-chelated iron, or FeCl3. Chemical, physical, and sensory characteristics were compared with those of a control cheese. Physical properties were assessed by testing melting, apparent viscosity, and browning of heated cheese. Cheeses were evaluated by trained panelists for the presence of metallic flavors, oxidized flavors, and other undesirable flavors. Addition of 25 mg iron/kg of cheese had no effects on the physical properties of Mozzarella cheese. Apparent viscosity of cheese fortified with 50 mg of iron/kg of cheese tended to be slightly higher than the control cheese, although this difference was not statistically significant at all storage times. Cook color was not affected by iron fortification. No increase in chemical oxidation (measured using thiobarbituric acid assay) was observed between the control and iron-fortified cheeses. Slight but statistically significant increases in metallic flavors, oxidized flavors, and off-flavors in the iron-fortified cheese were observed by the trained sensory panel, but the flavor defects were of very low intensity. For metallic flavors, oxidized flavors, and off-flavors, the control cheese scored 1.5, 1.5, and 1.3, respectively; the iron-fortified cheese scored 2.1, 2.0, and 1.6 based on a nine-point scale (where 1 = not perceptible to 3 = slightly perceptible). Sensory scores for iron-fortified cheese made using casein-chelated iron or whey protein-chelated iron was not significantly different from those of cheese made using ferric chloride. When used on pizza, consumer panels rated the iron-fortified cheeses as comparable with the control cheese.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    PubMed Central

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

    1990-01-01

    Monoclonal antibodies to ferric pseudobactin, the siderophore (microbial iron transport agent) of plant growth-promoting Pseudomonas putida B10, have been developed. Three immunoglobulin G subclass 1-type monoclonal antibodies have been characterized. Each antibody appears to be unique on the basis of their reactions with ferric pseudobactin and with culture supernatants from other pseudomonads. None of the three cross-reacts with ferric pseudobactin-type siderophores produced by seven other pseudomonads. However, P. aeruginosa ATCC 15692 and P. fluorescens ATCC 17400 produced relatively high-molecular-mass compounds (mass greater than approximately 30,000 daltons) that did react with the antibodies. The compound from P. aeruginosa was not iron regulated, while the compound from P. fluorescens was produced only under iron-limiting conditions. A competitive assay using these antibodies has a detection limit of 5 × 10−12 mol of ferric pseudobactin. This is, to our knowledge, the first report of monoclonal antibodies reactive with siderophores. PMID:16348116

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

    EPA Science Inventory

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

  13. 40 CFR 180.1302 - Sodium Ferric Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance. 180.1302 Section 180.1302 Protection of... Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of sodium ferric EDTA in or on all food commodities when applied as...

  14. 40 CFR 180.1302 - Sodium Ferric Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance. 180.1302 Section 180.1302 Protection of... Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of sodium ferric EDTA in or on all food commodities when applied as...

  15. 40 CFR 180.1302 - Sodium Ferric Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance. 180.1302 Section 180.1302 Protection of... Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of sodium ferric EDTA in or on all food commodities when applied as...

  16. 40 CFR 180.1302 - Sodium Ferric Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance. 180.1302 Section 180.1302 Protection of... Ethylenediaminetetraacetate (EDTA); exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of sodium ferric EDTA in or on all food commodities when applied as...

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

  19. Accessible and green manufacturing of magnetite (ferrous ferric oxide) nanocrystals and their use in magnetic separations

    NASA Astrophysics Data System (ADS)

    Yavuz, Cafer Tayyar

    This work describes the first size dependent magnetic separation in nanoscale. Magnetite (Fe3O4) nanocrystals of high quality and uniform size were synthesized with monodispersity below 10%. Magnetite nanocrystals of 4 nm to 33 nm (average diameter) were produced. Batch synthesis was shown to go up to 20 grams which is more than 10 times of a standard nanocrystal synthesis, without loosing the quality and monodispersity. Reactor design for mass (1 gram per hour) production of magnetite nanocrystals is reported for the first time. The cost of a kg of lab purity magnetite nanocrystals was shown to be 2600. A green synthesis that utilizes rust and edible oils was developed. The cost of a kg was brought down to 22. Size dependency of magnetism was shown in nanoscale for the first time. Reversible aggregation theory was developed to explain the low field magnetic separation and solution behavior of magnetite nanocrystals. Arsenic was removed from drinking water with magnetite nanocrystals 200 times better than commercial adsorbents. Silica coating was successfully applied to enable the known silica related biotechnologies. Magnetite-silica nanoshells were functionalized with amino groups. For the first time, silver was coated on the magnetite-silica nanoshells to produce triple multishells. Anti-microbial activity of multishells is anticipated.

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

    PubMed

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

    2014-10-15

    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.

  1. Methane-induced Activation Mechanism of Fused Ferric Oxide-Alumina Catalysts during Methane Decomposition.

    PubMed

    Reddy Enakonda, Linga; Zhou, Lu; Saih, Youssef; Ould-Chikh, Samy; Lopatin, Sergei; Gary, Daniel; Del-Gallo, Pascal; Basset, Jean-Marie

    2016-08-01

    Activation of Fe2 O3 -Al2 O3 with CH4 (instead of H2 ) is a meaningful method to achieve catalytic methane decomposition (CMD). This reaction of CMD is more economic and simple against commercial methane steam reforming (MSR) as it produces COx -free H2 . In this study, for the first time, structure changes of the catalyst were screened during CH4 reduction with time on stream. The aim was to optimize the pretreatment conditions through understanding the activation mechanism. Based on results from various characterization techniques, reduction of Fe2 O3 by CH4 proceeds in three steps: Fe2 O3 →Fe3 O4 →FeO→Fe0. Once Fe0 is formed, it decomposes CH4 with formation of Fe3 C, which is the crucial initiation step in the CMD process to initiate formation of multiwall carbon nanotubes. PMID:27345621

  2. Microglial activation, recruitment and phagocytosis as linked phenomena in ferric oxide nanoparticle exposure.

    PubMed

    Wang, Yun; Wang, Bing; Zhu, Mo-Tao; Li, Ming; Wang, Hua-Jian; Wang, Meng; Ouyang, Hong; Chai, Zhi-Fang; Feng, Wei-Yue; Zhao, Yu-Liang

    2011-08-10

    Microglia as the resident macrophage-like cells in the central nervous system (CNS) play a pivotal role in the innate immune responses of CNS. Understanding the reactions of microglia cells to nanoparticle exposure is important in the exploration of neurobiology of nanoparticles. Here we provide a systemic mapping of microglia and the corresponding pathological changes in olfactory-transport related brain areas of mice with Fe(2)O(3)-nanoparticle intranasal treatment. We showed that intranasal exposure of Fe(2)O(3) nanoparticle could lead to pathological alteration in olfactory bulb, hippocampus and striatum, and caused microglial proliferation, activation and recruitment in these areas, especially in olfactory bulb. Further experiments with BV2 microglial cells showed the exposure to Fe(2)O(3) nanoparticles could induce cells proliferation, phagocytosis and generation of ROS and NO, but did not cause significant release of inflammatory factors, including IL-1β, IL-6 and TNF-α. Our results indicate that microglial activation may act as an alarm and defense system in the processes of the exogenous nanoparticles invading and storage in brain.

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

    PubMed

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

    2004-08-01

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

  4. Chemical evolution. XL - Clay-mediated oxidation of diaminomaleonitrile

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Hagan, W. J., Jr.; Alwis, K. W.; Mccrea, J.

    1982-01-01

    The inhibition of the oligomerization of HCN by montmorillonite clays is shown to be caused by oxidation of diaminomaleonitrile (DAMN) by ferric ion in the clay lattice, with ferrous ion and oxalic acid the reaction products. It is demonstrated that diiminosuccinonitrile is the initial reaction product and is rapidly hydrolized to oxalic acid and HCN. The same oxidative transformations are effected by ferric ion bound to Dowex 50, ferric ion in solution, and Ni(NH3)6(2+). The rate of reaction of DAMN indicates no catalytic role for the clay in the oxidation of DAMN, and little reaction of the latter was observed with montmorillonite in which the bulk of the iron was in the divalent state. The possible significance of these redox reactions to chemical evolution is discussed.

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

    PubMed Central

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

    2014-01-01

    For decades, a link between increased levels of iron and areas of Alzheimer's disease (AD) pathology has been recognized, including AD lesions comprised of the peptide β-amyloid (Aβ). Despite many observations of this association, the relationship between Aβ 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 Aβ(1–42) and synthetic iron(III), reminiscent of ferric iron stores in the brain. We report Aβ to be capable of accumulating iron(III) within amyloid aggregates, with this process resulting in Aβ-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 Aβ, enabling the redox cycling of the iron. These results demonstrate the ability of Aβ 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 Aβ and iron deliver valuable insights into the process of AD progression, which may ultimately provide targets for disease therapies. PMID:24671940

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

    USGS Publications Warehouse

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

    1941-01-01

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

  7. Low temperature optical spectroscopy of low-spin ferric hemeproteins.

    PubMed

    Leone, M; Cupane, A; Cordone, L

    1996-01-01

    We report the Soret absorption spectra (500-350 nm) of the cyanomet derivatives of human hemoglobin and horse myoglobin, in the temperature range 300-20 K and in two different solvents (65% v/v glycerol-water or 65% v/v ethylene glycol-water). In order to obtain information on stereodynamic properties of active site of the two hemeproteins, we perform an analysis of the band profiles within the framework of electron-vibrations coupling. This approach enables us to single out the various contributions to the spectral bandwidth, such as those arising from non-radiative decay of the excited electronic state (homogeneous broadening) and from the coupling of the electronic transition i) with high frequency modes (that determines the vibronic structure of the band) and ii) with a "bath" of low frequency modes (that is responsible for the temperature dependence of the experimental spectra). We discuss the relevant parameters and their temperature dependence and compare them with the ones already reported for other derivatives of the same hemeproteins in the same solvents. In particular, non-harmonic contributions to soft modes are found, for cyanomet derivatives, to be larger than those observed for liganded carbonmonoxy but smaller than those observed for unliganded deoxy derivatives. The reported data enable us to obtain information on the dependence of stereodynamic properties of the heme pocket upon iron oxidation state, dimensions of the exogenous ligand and composition of the external matrix.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  9. Molecular dynamics in nanophase-separated comb-like poly(alpha-n-alkyl beta-L-aspartate)s.

    PubMed

    Grimau, M; Laredo, E; Sánchez, F; López-Carrasquero, F; Báez, M E; Bello, A

    2004-12-01

    A series of poly(alpha-n-alkyl beta-L-aspartates) which are nanophase self-assembled comb-like polymers has been studied by dielectric spectroscopy in a broad frequency range (10(-2) < or = nu < or = 3 x 10(6) Hz), with n-alkyls side chains of various lengths, 10 < or = n < or =18. In every member of the series the same relaxations were identified after the decomposition of the experimental isothermal trace in up to three peaks with relaxation times distributions. The strength, width and average relaxation time for all the relaxation modes were determined for each material. Besides the local low temperature, Arrhenius modes, two relaxation modes, alpha and alpha(PE), present a cooperative character whose dynamics are not affected by the side chains melting. The alpha(PE) relaxation is a polyethylene-like glass transition of the amorphous side chains and its dynamics is strongly dependent on the n value due to the increasing restrictions imposed by the self-assembled confinement. The strength of the alpha(PE) relaxation mode increases as the lateral chains loose their 2D order. The restricted chopstick motion of the rigid rods is thought to be the origin of the alpha mode; this motion is hindered at temperatures where the cage size decreases as a result of the increasing disorder with temperature.

  10. Energy cascades, excited state dynamics, and photochemistry in cob(III)alamins and ferric porphyrins.

    PubMed

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

    2015-03-17

    Porphyrins and the related chlorins and corrins contain a cyclic tetrapyrrole with the ability to coordinate an active metal center and to perform a variety of functions exploiting the oxidation state, reactivity, and axial ligation of the metal center. These compounds are used in optically activated applications ranging from light harvesting and energy conversion to medical therapeutics and photodynamic therapy to molecular electronics, spintronics, optoelectronic thin films, and optomagnetics. Cobalt containing corrin rings extend the range of applications through photolytic cleavage of a unique axial carbon-cobalt bond, permitting spatiotemporal control of drug delivery. The photochemistry and photophysics of cyclic tetrapyrroles are controlled by electronic relaxation dynamics including internal conversion and intersystem crossing. Typically the electronic excitation cascades through ring centered ππ* states, ligand to metal charge transfer (LMCT) states, metal to ligand charge transfer (MLCT) states, and metal centered states. Ultrafast transient absorption spectroscopy provides a powerful tool for the investigation of the electronic state dynamics in metal containing tetrapyrroles. The UV-visible spectrum is sensitive to the oxidation state, electronic configuration, spin state, and axial ligation of the central metal atom. Ultrashort broadband white light probes spanning the range from 270 to 800 nm, combined with tunable excitation pulses, permit the detailed unravelling of the time scales involved in the electronic energy cascade. State-of-the-art theoretical calculations provide additional insight required for precise assignment of the states. In this Account, we focus on recent ultrafast transient absorption studies of ferric porphyrins and corrin containing cob(III)alamins elucidating the electronic states responsible for ultrafast energy cascades, excited state dynamics, and the resulting photoreactivity or photostability of these compounds. Iron

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    Northwest Africa 4590 is a heterogeneous olivine gabbro with cumulate texture composed of Al-Ti-rich clinopyroxene, pure anorthite, Ca-rich olivine, kirschsteinite and ulvöspinel, with accessory troilite, merrillite, Ca silicophosphate, kamacite and glasses [1]. Rhönite now has been identified in this specimen (for the first time in any angrite) as (1) a large (0.65 mm long), blocky, anhedral grain adjacent to anorthite, kirschsteinite and troilite, (2) ca. 15 micron grains along grain boundaries of the major phases (in one case in contact with clinopyroxene and metal), and (3) ca. 30 micron grains within melt inclusions and veins composed of kirschsteinite, olivine, anorthite, troilite, hercynite and glass. The rhönite is nearly opaque in transmitted light, with a deep cinnamon-red color on thin grain edges. The average composition of the largest grain is (in wt.%): SiO2 23.6, TiO2 9.9, Al2O3 16.3, Cr2O3 0.1, FeOt 33.6, MnO 0.14, MgO 3.5, CaO 13.1. Stoichiometry (14 cations, 20 oxygen atoms) requires about 12% of the total iron to be in the ferric state, resulting in the nominal formula: (Ca2.01Mn0.02)(Fe2+3.55Fe3+0.45Mg0.75Al0.12Cr0.15)Ti0.9 5(Si3.37Al2.63)O20 In the co-existing ulvöspinel about 18% of the iron must be ferric to achieve charge balance; likewise, Fe-Ti spinel coexisting with metal in Angra dos Reis contains ferric iron [2]. In contrast, the spinel (Cr-pleonaste) in metal-rich angrite NWA 2999 is stoichiometric without any apparent ferric iron. The coexistence of ferric iron- bearing silicate and oxide phases with Fe metal implies that the oxygen fugacity during crystallization of NWA 4590 was somewhat more oxidizing than that of the IW buffer. Compositions of primary (pre-exsolution) olivine and kirschsteinite in NWA 4590 record a minimum magmatic temperature of 910-950°C, based on the solvus of [3]. Previous experimental studies [4] also imply that other metal-bearing plutonic (AdoR, LEW 86010) and quench-textured (LEW 87051) angrites

  12. Flocculation properties of several microalgae and a cyanobacterium species during ferric chloride, chitosan and alkaline flocculation.

    PubMed

    Lama, Sanjaya; Muylaert, Koenraad; Karki, Tika Bahadur; Foubert, Imogen; Henderson, Rita K; Vandamme, Dries

    2016-11-01

    Flocculation holds great potential as a low-cost harvesting method for microalgae biomass production. Three flocculation methods (ferric chloride, chitosan, and alkaline flocculation) were compared in this study for the harvesting of 9 different freshwater and marine microalgae and one cyanobacterium species. Ferric chloride resulted in a separation efficiency greater than 90% with a concentration factor (CF) higher than 10 for all species. Chitosan flocculation worked generally very well for freshwater microalgae, but not for marine species. Alkaline flocculation was most efficient for harvesting of Nannochloropsis, Chlamydomonas and Chlorella sp. The concentration factor was highly variable between microalgae species. Generally, minimum flocculant dosages were highly variable across species, which shows that flocculation may be a good harvesting method for some species but not for others. This study shows that microalgae and cyanobacteria species should not be selected solely based on their productivity but also on their potential for low-cost separation. PMID:27611030

  13. Functional Analysis of the Ferric Uptake Regulator Gene fur in Xanthomonas vesicatoria

    PubMed Central

    Liu, Huiqin; Dong, Chunling; Zhao, Tingchang; Han, Jucai; Wang, Tieling; Wen, Xiangzhen; Huang, Qi

    2016-01-01

    Iron is essential for the growth and survival of many organisms. Intracellular iron homeostasis must be maintained for cell survival and protection against iron toxicity. The ferric uptake regulator protein (Fur) regulates the high-affinity ferric uptake system in many bacteria. To investigate the function of the fur gene in Xanthomonas vesicatoria (Xv), we generated a fur mutant strain, fur-m, by site-directed mutagenesis. Whereas siderophore production increased in the Xv fur mutant, extracellular polysaccharide production, biofilm formation, swimming ability and quorum sensing signals were all significantly decreased. The fur mutant also had significantly reduced virulence in tomato leaves. The above-mentioned phenotypes significantly recovered when the Xv fur mutation allele was complemented with a wild-type fur gene. Thus, Fur either negatively or positively regulates multiple important physiological functions in Xv. PMID:26910324

  14. Functional Analysis of the Ferric Uptake Regulator Gene fur in Xanthomonas vesicatoria.

    PubMed

    Liu, Huiqin; Dong, Chunling; Zhao, Tingchang; Han, Jucai; Wang, Tieling; Wen, Xiangzhen; Huang, Qi

    2016-01-01

    Iron is essential for the growth and survival of many organisms. Intracellular iron homeostasis must be maintained for cell survival and protection against iron toxicity. The ferric uptake regulator protein (Fur) regulates the high-affinity ferric uptake system in many bacteria. To investigate the function of the fur gene in Xanthomonas vesicatoria (Xv), we generated a fur mutant strain, fur-m, by site-directed mutagenesis. Whereas siderophore production increased in the Xv fur mutant, extracellular polysaccharide production, biofilm formation, swimming ability and quorum sensing signals were all significantly decreased. The fur mutant also had significantly reduced virulence in tomato leaves. The above-mentioned phenotypes significantly recovered when the Xv fur mutation allele was complemented with a wild-type fur gene. Thus, Fur either negatively or positively regulates multiple important physiological functions in Xv.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  16. Flocculation properties of several microalgae and a cyanobacterium species during ferric chloride, chitosan and alkaline flocculation.

    PubMed

    Lama, Sanjaya; Muylaert, Koenraad; Karki, Tika Bahadur; Foubert, Imogen; Henderson, Rita K; Vandamme, Dries

    2016-11-01

    Flocculation holds great potential as a low-cost harvesting method for microalgae biomass production. Three flocculation methods (ferric chloride, chitosan, and alkaline flocculation) were compared in this study for the harvesting of 9 different freshwater and marine microalgae and one cyanobacterium species. Ferric chloride resulted in a separation efficiency greater than 90% with a concentration factor (CF) higher than 10 for all species. Chitosan flocculation worked generally very well for freshwater microalgae, but not for marine species. Alkaline flocculation was most efficient for harvesting of Nannochloropsis, Chlamydomonas and Chlorella sp. The concentration factor was highly variable between microalgae species. Generally, minimum flocculant dosages were highly variable across species, which shows that flocculation may be a good harvesting method for some species but not for others. This study shows that microalgae and cyanobacteria species should not be selected solely based on their productivity but also on their potential for low-cost separation.

  17. Functional Analysis of the Ferric Uptake Regulator Gene fur in Xanthomonas vesicatoria.

    PubMed

    Liu, Huiqin; Dong, Chunling; Zhao, Tingchang; Han, Jucai; Wang, Tieling; Wen, Xiangzhen; Huang, Qi

    2016-01-01

    Iron is essential for the growth and survival of many organisms. Intracellular iron homeostasis must be maintained for cell survival and protection against iron toxicity. The ferric uptake regulator protein (Fur) regulates the high-affinity ferric uptake system in many bacteria. To investigate the function of the fur gene in Xanthomonas vesicatoria (Xv), we generated a fur mutant strain, fur-m, by site-directed mutagenesis. Whereas siderophore production increased in the Xv fur mutant, extracellular polysaccharide production, biofilm formation, swimming ability and quorum sensing signals were all significantly decreased. The fur mutant also had significantly reduced virulence in tomato leaves. The above-mentioned phenotypes significantly recovered when the Xv fur mutation allele was complemented with a wild-type fur gene. Thus, Fur either negatively or positively regulates multiple important physiological functions in Xv. PMID:26910324

  18. Using Crystal Structure Groups to Understand Mössbauer parameters of Ferric Sulfates

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    A Mössbauer doublet assigned to ferric sulfate (Fe3D2) was identified in Paso Robles, Mars, spectra by Morris et al. (2006), who noted that its parameters are not diagnostic of any specific mineral because a number of different sulfates with varying parageneses might be responsible for this doublet. Work by Lane et al. (2008) used a multi-instrument approach based on Fe3+ sulfate spectra acquired with VNIR and midinfrared reflectance, mid-infrared emission and Mössbauer spectrometers to narrow down the possible ferric sulfate phases present at Paso Robles to ferricopiapite possibly mixed with other ferric sulfates such as butlerite, parabutlerite, fibroferrite, or metahomanite. Thus, we explore here the crystal-chemical rationale behind these interpretations of the Mössbauer results, using similarities and difference among mineral structures to explore which phases might have similar coordination polyhedra around the Fe atoms in sulfates. Work by Hawthorne et al. (2000) organizes the sulfate minerals into groups with analogous crystal structures. Mössbauer doublets assigned to ferric sulfates ubiquitously have isomer shifts (IS) of 0.40-53 mm/s so that IS is non-diagnostic. However, quadrupole splitting of doublets in these mineral groups has a wide range (0-1.4 mm/s) and the variation can be systematically correlated with different structure types. Members of the hydration series Fe2(SO4)3 · n H2O, which includes quenstedtite, coquimbite, paracoquimbite, kornelite, and lausenite have Mössbauer spectra that closely resemble singlets because of their near-zero QS. These minerals share structures involving finite clusters of sulfate tetrahedral and Fe octahedral or chains of depolymerized clusters, and all mineral species with these structures share similar Mössbauer parameters. At the other extreme, ferric sulfates with structures based on infinite sheets (hydrotalcite, alunite, jarosite), tend to have large electric field gradients at the nucleus of the Fe3

  19. Nephrotoxicity of ferric nitrilotriacetate. An electron-microscopic and metabolic study.

    PubMed Central

    Hamazaki, S.; Okada, S.; Ebina, Y.; Fujioka, M.; Midorikawa, O.

    1986-01-01

    Repeated intraperitoneal injections of ferric nitrilotriacetate (Fe-NTA) induce nephrotoxic features such as proximal tubular necrosis and renal failure, an unexpected phenomenon for a ferric compound. The mechanism of Fe-NTA toxicity was investigated by electron microscopy and respiration studies of renal cortical mitochondria in rats. Four hours after a single intraperitoneal injection of Fe-NTA, 5 mg iron/kg body wt, loss of microvilli, increased number of cytoplasmic vacuoles, electron-dense cytoplasmic deposits, mitochondrial swelling, karyorrhexis, and rupture of cytoplasmic membrane were observed in proximal tubular epithelia. At 24 hours, an increased number of cells had become necrotic. Polarographic studies of mitochondria from renal cortex 4 hours after Fe-NTA treatment showed a significant decrease in State 3 respiration and DNP-uncoupled respiration, whereas little change was observed in State 4 respiration and ADP/O. Images Figure 1 Figure 2 Figure 3 PMID:3706495

  20. Structure of Hemoglobin M Boston, a Variant with a Five-Coordinated Ferric Heme

    PubMed Central

    Pulsinelli, P. D.; Perutz, M. F.; Nagel, R. L.

    1973-01-01

    X-ray analysis of the natural valency hybrid α2+M Bostonβ2deoxy shows that the ferric iron atoms in the abnormal α subunits are bonded to the phenolate side chains of the tyrosines that have replaced the distal histidines; the iron atoms are displaced to the distal side of the porphyrin ring and are not bonded to the proximal histidines. The resulting changes in tertiary structure of the α subunits stabilize the hemoglobin tetramer in the quaternary deoxy structure, which lowers the oxygen affinity of the normal β subunits and causes cyanosis. The strength of the bond from the ferric iron to the phenolate oxygen appears to be the main factor responsible for the many abnormal properties of hemoglobin M Boston. Images PMID:4521212

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

    SciTech Connect

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

    1988-06-01

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

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

    PubMed

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

    2013-11-19

    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-μXRF) 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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2013-11-19

    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-μXRF) 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.

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

    PubMed

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

    2010-05-15

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

  6. The ferric enterobactin transporter Fep is required for persistent Salmonella enterica serovar typhimurium infection.

    PubMed

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

    2013-11-01

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

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

    SciTech Connect

    Sisk, L.; Benefield, L.; Reed, B.

    1987-01-01

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

  8. Effect of ferric and bromide ions on the formation and speciation of disinfection byproducts during chlorination.

    PubMed

    Liu, Shaogang; Zhu, Zhiliang; Qiu, Yanling; Zhao, Jianfu

    2011-01-01

    The effects of ferric ion, pH, and bromide on the formation and distribution of disinfection byproducts (DBPs) during chlorination were studied. Two raw water samples from Huangpu River and Yangtze River, two typical drinking water sources of Shanghai, were used for the investigation. Compared with the samples from Huangpu River, the raw water samples from Yangtze River had lower content of total organic carbon (TOC) and ferric ions, but higher bromide concentrations. Under controlled chlorination conditions, four trihalomethanes (THMs), nine haloacetic acids (HAAs), total organic halogen (TOX) and its halogen species fractions, including total organic chlorine (TOC1) and total organic bromide (TOBr), were determined. The results showed that co-existent ferric and bromide ions significantly promoted the formation of total THMs and HAAs for both raw water samples. Higher concentration of bromide ions significantly changed the speciation of the formed THMs and HAAs. There was an obvious shift to brominated species, which might result in a more adverse influence on the safety of drinking water. The results also indicated that high levels of bromide ions in raw water samples produced higher percentages of unknown TOBr.

  9. Potential of Alginate Encapsulated Ferric Saccharate Microemulsions to Ameliorate Iron Deficiency in Mice.

    PubMed

    Mukhija, Kimmi; Singhal, Kirti; Angmo, Stanzin; Yadav, Kamalendra; Yadav, Hariom; Sandhir, Rajat; Singhal, Nitin Kumar

    2016-07-01

    Iron deficiency is one of the most prominent mineral deficiencies around the world, which especially affects large population of women and children. Development of new technologies to combat iron deficiency is on high demand. Therefore, we developed alginate microcapsule with encapsulated iron that had better oral iron bioavailability. Microcapsules containing iron with varying ratios of sodium alginate ferric(III)-saccharide were prepared using emulsification method. In vitro studies with Caco-2 cells suggested that newly synthesized microemulsions had better iron bioavailability as compared to commercially available iron dextran formulations. Ferrozine in vitro assay showed that alginate-encapsulated ferric galactose microemulsion (AFGM) had highest iron bioavailability in comparison to other four ferric saccharate microemulsions, namely AFGlM, AFMM, AFSM, and AFFM synthesized in our laboratory. Mice studies also suggested that AFGM showed higher iron absorption as indicated by increased serum iron, hemoglobin, and other hematopoietic measures with almost no toxicity at tested doses. Development of iron-loaded microemulsions leads to higher bioavailability of iron and can provide alternative strategies to treat iron deficiency. PMID:26637994

  10. Highly covalent ferric-thiolate bonds exhibit surprisingly low mechanical stability.

    PubMed

    Zheng, Peng; Li, Hongbin

    2011-05-01

    Depending on their nature, different chemical bonds show vastly different stability with covalent bonds being the most stable ones that rupture at forces above nanonewton. Studies have revealed that ferric-thiolate bonds are highly covalent and are conceived to be of high mechanical stability. Here, we used single molecule force spectroscopy techniques to directly determine the mechanical strength of such highly covalent ferric-thiolate bonds in rubredoxin. We observed that the ferric-thiolate bond ruptures at surprisingly low forces of ∼200 pN, significantly lower than that of typical covalent bonds, such as C-Si, S-S, and Au-thiolate bonds, which typically ruptures at >1.5 nN. And the mechanical strength of Fe-thiolate bonds is observed to correlate with the covalency of the bonds. Our results indicated that highly covalent Fe-thiolate bonds are mechanically labile and display features that clearly distinguish themselves from typical covalent bonds. Our study not only opens new avenues to investigating this important class of chemical bonds, but may also shed new lights on our understanding of the chemical nature of these metal thiolate bonds.

  11. Removal of Silicon from High Level Waste Streams via Ferric Flocculation

    SciTech Connect

    Wilmarth, W.R.

    2004-04-07

    The presence of silicate from glass-forming frit in the recycle waste from the Defense Waste Processing Facility (DWPF) produces wastes that when combined with the traditional aluminate-bearing wastes stored in Savannah River Site's tank farms can produce insoluble sodium aluminosilicates. Currently, aluminum-bearing wastes and silicon-bearing wastes are processed in separate evaporators. This, however, limits operational flexibility. Therefore, treatment to remove silicon has been proposed to allow greater flexibility for processing these wastes in the Site's evaporators. The use of a ferric precipitation (flocculation) to remove the silicon has been tested using waste simulants. Ferric precipitation following ferric nitrate addition to two different alkaline DWPF recycle waste simulants was effective at removing silicon to levels below concern for processing in the any of the Savannah River Site's evaporators. Removal of silicon was rapid with removal complete in 2 hours. Elevated temperatures were tested and found to be not required. Capacities of the resultant iron flocculent were approximately 0.1 g of silicon per gram of iron at a final silicon concentration of 50 mg/L. Moreover, the silicon removal obeys a classical Freundlich adsorption isotherm.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2009-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    DOEpatents

    Barbour, John C.; Knapp, James Arthur; Follstaedt, David Martin; Myers, Samuel Maxwell

    1998-12-15

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

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

    SciTech Connect

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

    1999-12-13

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

  17. Metal tungstates at the ultimate two-dimensional limit: fabrication of a CuWO₄ nanophase.

    PubMed

    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

    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.

  18. Ordered mesoporous platinum@graphitic carbon embedded nanophase as a highly active, stable, and methanol-tolerant oxygen reduction electrocatalyst.

    PubMed

    Wu, Zhangxiong; Lv, Yingying; Xia, Yongyao; Webley, Paul A; Zhao, Dongyuan

    2012-02-01

    Highly ordered mesoporous platinum@graphitic carbon (Pt@GC) composites with well-graphitized carbon frameworks and uniformly dispersed Pt nanoparticles embedded within the carbon pore walls have been rationally designed and synthesized. In this facile method, ordered mesoporous silica impregnated with a variable amount of Pt precursor is adopted as the hard template, followed by carbon deposition through a chemical vapor deposition (CVD) process with methane as a carbon precursor. During the CVD process, in situ reduction of Pt precursor, deposition of carbon, and graphitization can be integrated into a single step. The mesostructure, porosity and Pt content in the final mesoporous Pt@GC composites can be conveniently adjusted over a wide range by controlling the initial loading amount of Pt precursor and the CVD temperature and duration. The integration of high surface area, regular mesopores, graphitic nature of the carbon walls as well as highly dispersed and spatially embedded Pt nanoparticles in the mesoporous Pt@GC composites make them excellent as highly active, extremely stable, and methanol-tolerant electrocatalysts toward the oxygen reduction reaction (ORR). A systematic study by comparing the ORR performance among several carbon supported Pt electrocatalysts suggests the overwhelmingly better performance of the mesoporous Pt@GC composites. The structural, textural, and framework properties of the mesoporous Pt@GC composites are extensively studied and strongly related to their excellent ORR performance. These materials are highly promising for fuel cell applications and the synthesis method is quite applicable for constructing mesoporous graphitized carbon materials with various embedded nanophases.

  19. Reactions of metal ions at surfaces of hydrous iron oxide

    USGS Publications Warehouse

    Hem, J.D.

    1977-01-01

    Cu, Ag and Cr concentrations in natural water may be lowered by mild chemical reduction involving ferric hydroxide-ferrous ion redox processes. V and Mo solubilities may be controlled by precipitation of ferrous vanadate or molybdate. Concentrations as low as 10-8.00 or 10-9.00 M are readily attainable for all these metals in oxygen-depleted systems that are relatively rich in Fe. Deposition of manganese oxides such as Mn3O4 can be catalyzed in oxygenated water by coupling to ferrous-ferric redox reactions. Once formed, these oxides may disproportionate, giving Mn4+ oxides. This reaction produces strongly oxidizing conditions at manganese oxide surfaces. The solubility of As is significantly influenced by ferric iron only at low pH. Spinel structures such as chromite or ferrites of Cu, Ni, and Zn, are very stable and if locally developed on ferric hydroxide surfaces could bring about solubilities much below 10-9.00 M for divalent metals near neutral pH. Solubilities calculated from thermodynamic data are shown graphically and compared with observed concentrations in some natural systems. ?? 1977.

  20. Suppressive effects of dietary curcumin on the increased activity of renal ornithine decarboxylase in mice treated with a renal carcinogen, ferric nitrilotriacetate.

    PubMed

    Okazaki, Yasumasa; Iqbal, Mohammad; Okada, Shigeru

    2005-06-10

    Curcumin, a natural, biologically active compound extracted from rhizomes of Curcuma species, has been shown to act as a biological response modifier in various disorders. We have reported previously that the dietary supplementation of curcumin enhances the activities of antioxidant and phase II metabolizing enzymes in mice (M. Iqbal, S.D. Sharma, Y. Okazaki, M. Fujisawa, S. Okada, Dietary supplementation of curcumin enhances antioxidant and phase II metabolizing enzymes in ddY mice: possible role in protection against chemical carcinogenesis and toxicity, Pharmacol and Toxicol. 92 (2003) 33_38.) and inhibits ferric nitrilotriacetate (Fe-NTA) induced oxidative injury of lipids and DNA in vitro (M. Iqbal, Y. Okazaki, S. Okada, In vitro curcumin modulates Ferric Nitrilotriacetate (Fe-NTA) and hydrogen peroxide (H(2)O(2))-induced peroxidation of microsomal membrane lipids and DNA damage, Teratogenesis Carcinogenesis and Mutagenesis Supplement 23 (2003) 151-160.). In our present study, Fe-NTA, a known complete renal carcinogen, which generate ROS in vivo, was given intraperitoneally to mice and curcumin was tested for its ability to inhibits oxidative stress and the activity of ornithine decarboxylase (ODC) as well as histopathological changes in the kidney. Substantial changes in glutathione, antioxidant enzymes as well as changes in phase II metabolizing enzymes were observed in the kidney at 12 h after treatment with Fe-NTA (9.0 mg Fe/kg body weight). Effect of oxidative stress induced by Fe-NTA were also demonstrated by the increase in lipid peroxidation as monitored by formation of thiobarbituric acid-reactive substances and 4-hydroxy-2-nonenal (HNE)-modified proteins in kidney. Likewise, the level of protein carbonyl contents, an indicator of protein oxidation was also increased after Fe-NTA administration. However, the changes in these parameters were restored to normal in curcumin-pretreated mice. The ODC activity in the kidney was significantly increased by Fe

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

    PubMed Central

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

    2015-01-01

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

  2. Ferric Citrate

    PubMed Central

    Cada, Dennis J.; Cong, Jasen; Baker, Danial E.

    2015-01-01

    Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, call The Formulary at 800-322-4349. The February 2015 monograph topics are netupitant/palonosetron, naltrxone SR/bupropion SR, nintedanib, pirfenidone, and ivabradine. The Safety MUE is on netupitant/palonosetron. PMID:25717210

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

    PubMed

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

    2011-01-01

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

  4. Understanding Regeneration of Arsenate-Loaded Ferric Hydroxide-Based Adsorbents

    PubMed Central

    Chaudhary, Binod Kumar; Farrell, James

    2015-01-01

    Abstract Adsorbents comprising ferric hydroxide loaded on a variety of support materials are commonly used to remove arsenic from potable water. Although several studies have investigated the effects of support properties on arsenic adsorption, there have been no investigations of their effects on adsorbent regeneration. Furthermore, the effect of regenerant solution composition and the kinetics of regeneration have not been investigated. This research investigated the effects of adsorbent and regenerant solution properties on the kinetics and efficiency of regeneration of arsenate-loaded ferric hydroxide-based adsorbents. Solutions containing only 0.10–5.0 M NaOH or 0.10–1.0 M NaCl, as well as solutions containing both compounds, were used as regenerants. On all media, >99% of arsenate was adsorbed through complexation with ferric hydroxide. Arsenate recovery was controlled by both equilibrium and kinetic limitations. Adsorbents containing support material with weak base anion-exchange functionality or no anion-exchange functionality could be regenerated with NaOH solutions alone. Regeneration of media containing strong base anion (SBA)-exchange functionality was greatly enhanced by addition of 0.10 M NaCl to the NaOH regenerant solutions. Adsorbed silica had a significant effect on NaOH regeneration of media containing type I SBA-exchange functionality, but on other media, adsorbed silica had little impact on regeneration. On all media, 5–25% of arsenate was resistant to desorption in 1.0 M NaOH solutions. However, the use of 2.5–5.0 M NaOH solutions significantly reduced the desorption-resistant fraction. PMID:25873779

  5. Solute-Solvent Interactions and High Spin ⇌ Low Spin Transitions in Ferric Dithiocarbamates

    NASA Astrophysics Data System (ADS)

    Ganguli, P.

    1985-01-01

    The HS ⇌ LS transition in ferric dithiocarbamates in a number of solvents has been investigated using NMR and is interpreted in terms of preferential solvation or second co-ordination sphere reorganisation effects. These studies clearly demonstrate that neglect of pseudo contact shifts can lead to erroneous conclusions about the spin delocalisation mechanisms. The spin derealization in these systems is by direct σ-delocalization along the alkyl chain. The As values of 2T2 and 6A1 states have the same sign.

  6. Ferric ion as a scavenging agent in a solvent extraction process

    DOEpatents

    Bruns, Lester E.; Martin, Earl C.

    1976-01-01

    Ferric ions are added into the aqueous feed of a plutonium scrap recovery process that employs a tributyl phosphate extractant. Radiolytic degradation products of tributyl phosphate such as dibutyl phosphate form a solid precipitate with iron and are removed from the extraction stages via the waste stream. Consequently, the solvent extraction characteristics are improved, particularly in respect to minimizing the formation of nonstrippable plutonium complexes in the stripping stages. The method is expected to be also applicable to the partitioning of plutonium and uranium in a scrap recovery process.

  7. Formation of iron (hydr)oxides during the abiotic oxidation of Fe(II) in the presence of arsenate.

    PubMed

    Song, Jia; Jia, Shao-Yi; Yu, Bo; Wu, Song-Hai; Han, Xu

    2015-08-30

    Abiotic oxidation of Fe(II) is a common pathway in the formation of Fe (hydr)oxides under natural conditions, however, little is known regarding the presence of arsenate on this process. In hence, the effect of arsenate on the precipitation of Fe (hydr)oxides during the oxidation of Fe(II) is investigated. Formation of arsenic-containing Fe (hydr)oxides is constrained by pH and molar ratios of As:Fe during the oxidation Fe(II). At pH 6.0, arsenate inhibits the formation of lepidocrocite and goethite, while favors the formation of ferric arsenate with the increasing As:Fe ratio. At pH 7.0, arsenate promotes the formation of hollow-structured Fe (hydr)oxides containing arsenate, as the As:Fe ratio reaches 0.07. Arsenate effectively inhibits the formation of magnetite at pH 8.0 even at As:Fe ratio of 0.01, while favors the formation of lepidocrocite and green rust, which can be latterly degenerated and replaced by ferric arsenate with the increasing As:Fe ratio. This study indicates that arsenate and low pH value favor the slow growth of dense-structured Fe (hydr)oxides like spherical ferric arsenate. With the rapid oxidation rate of Fe(II) at high pH, ferric (hydr)oxides prefer to precipitate in the formation of loose-structured Fe (hydr)oxides like lepidocrocite and green rust.

  8. Formation of iron (hydr)oxides during the abiotic oxidation of Fe(II) in the presence of arsenate.

    PubMed

    Song, Jia; Jia, Shao-Yi; Yu, Bo; Wu, Song-Hai; Han, Xu

    2015-08-30

    Abiotic oxidation of Fe(II) is a common pathway in the formation of Fe (hydr)oxides under natural conditions, however, little is known regarding the presence of arsenate on this process. In hence, the effect of arsenate on the precipitation of Fe (hydr)oxides during the oxidation of Fe(II) is investigated. Formation of arsenic-containing Fe (hydr)oxides is constrained by pH and molar ratios of As:Fe during the oxidation Fe(II). At pH 6.0, arsenate inhibits the formation of lepidocrocite and goethite, while favors the formation of ferric arsenate with the increasing As:Fe ratio. At pH 7.0, arsenate promotes the formation of hollow-structured Fe (hydr)oxides containing arsenate, as the As:Fe ratio reaches 0.07. Arsenate effectively inhibits the formation of magnetite at pH 8.0 even at As:Fe ratio of 0.01, while favors the formation of lepidocrocite and green rust, which can be latterly degenerated and replaced by ferric arsenate with the increasing As:Fe ratio. This study indicates that arsenate and low pH value favor the slow growth of dense-structured Fe (hydr)oxides like spherical ferric arsenate. With the rapid oxidation rate of Fe(II) at high pH, ferric (hydr)oxides prefer to precipitate in the formation of loose-structured Fe (hydr)oxides like lepidocrocite and green rust. PMID:25855615

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

    PubMed

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

    2014-11-25

    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.

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

    SciTech Connect

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

    2008-01-01

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

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

    SciTech Connect

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

    1999-07-16

    Rare earth (RE) modification of automotive catalysts (e.g., ZrO{sub 2}) for exhaust gas treatment results in outstanding improvement of the structural stability, catalytic functions and resistance to sintering at high temperatures. Owing to the low redox potential of nonstoichiometric CeO{sub 2}, oxygen release and intake associated with the conversion between the 3+ and 4+ oxidation states of the Ce ions in Ce-doped ZrO{sub 2} provide the oxygen storage capacity that is essentially to effective catalytic functions under dynamic air-to-fuel ratio cycling. Doping tripositive RE ions such as La and Nd in ZrO{sub 2}, on the other hand, introduces oxygen vacancies that affect the electronic and ionic conductivity. These effects, in conjunction with the nanostructure and surface reactivity of the fine powders, present a challenging problem in the development of better ZrO{sub 2}-containing three-way catalysts. We have carried out in-situ small-to-wide angle neutron diffraction at high temperatures and under controlled atmospheres to study the structural phase transitions, sintering behavior, and Ce{sup 3+} {leftrightarrow} Ce{sup 4+} redox process. We found substantial effects due to RE doping on the nature of aggregation of nanoparticles, defect formation, crystal phase transformation, and metal-support interaction in ZrO{sub 2} catalysts for automotive emission control.

  12. Regulation of ferric iron transport in Escherichia coli K12: isolation of a constitutive mutant.

    PubMed

    Hantke, K

    1981-01-01

    The lac genes were inserted with phage Mu(Ap, lac) into the fhuA, fepA, cir and tonB genes which specify components of iron uptake systems. The expression of lac in all these operon fusions was controlled by the availability of iron to the cells, thereby facilitating a quick and simple measurement of the expression of the genes listed above. In an iron rich medium under anaerobic conditions all systems were strongly repressed. fhuA was depressed at higher iron concentration than was fepA or cir, and tonB was repressed only under anaerobic conditions and could be induced by iron limitation. Mutants constitutive for the expression of beta-galactosidase were selected in a fhuA-lac fusion strain. The outer membrane proteins Cir, FhuA, FecA, 76K and 83K were made constitutively in such mutant strains. Therefore, they were termed fur mutants. In these fur mutant strains, the synthesis of a 19K protein was reduced. Furthermore, it was found that transport of ferric enterochelin and ferrichrome was also constitutive in the fur mutant cells, and that ferric citrate uptake could be induced by only 10 microM citrate in the growth medium in contrast to wild-type cells in which at least 100 microM citrate was necessary. The fepA gene was concluded to be under an additional control, because it was not fully derepressed by the fur mutation. PMID:7026976

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

    SciTech Connect

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

    1987-09-01

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

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

    SciTech Connect

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

    1986-02-01

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

  15. Concerted loop motion triggers induced fit of FepA to ferric enterobactin.

    PubMed

    Smallwood, Chuck R; Jordan, Lorne; Trinh, Vy; Schuerch, Daniel W; Gala, Amparo; Hanson, Mathew; Hanson, Matthew; Shipelskiy, Yan; Majumdar, Aritri; Newton, Salete M C; Klebba, Phillip E

    2014-07-01

    Spectroscopic analyses of fluorophore-labeled Escherichia coli FepA described dynamic actions of its surface loops during binding and transport of ferric enterobactin (FeEnt). When FeEnt bound to fluoresceinated FepA, in living cells or outer membrane fragments, quenching of fluorophore emissions reflected conformational motion of the external vestibular loops. We reacted Cys sulfhydryls in seven surface loops (L2, L3, L4, L5, L7 L8, and L11) with fluorophore maleimides. The target residues had different accessibilities, and the labeled loops themselves showed variable extents of quenching and rates of motion during ligand binding. The vestibular loops closed around FeEnt in about a second, in the order L3 > L11 > L7 > L2 > L5 > L8 > L4. This sequence suggested that the loops bind the metal complex like the fingers of two hands closing on an object, by individually adsorbing to the iron chelate. Fluorescence from L3 followed a biphasic exponential decay as FeEnt bound, but fluorescence from all the other loops followed single exponential decay processes. After binding, the restoration of fluorescence intensity (from any of the labeled loops) mirrored cellular uptake that depleted FeEnt from solution. Fluorescence microscopic images also showed FeEnt transport, and demonstrated that ferric siderophore uptake uniformly occurs throughout outer membrane, including at the poles of the cells, despite the fact that TonB, its inner membrane transport partner, was not detectable at the poles.

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

    PubMed

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

    2006-01-01

    Arsenic removal from high-arsenic water in a mine drainage system has been studied through an enhanced coagulation process with ferric ions and coarse calcite (38-74 microm) in this work. The experimental results have shown that arsenic-borne coagulates produced by coagulation with ferric ions alone were very fine, so micro-filtration (membrane as filter medium) was needed to remove the coagulates from water. In the presence of coarse calcite, small arsenic-borne coagulates coated on coarse calcite surfaces, leading the settling rate of the coagulates to considerably increase. The enhanced coagulation followed by conventional filtration (filter paper as filter medium) achieved a very high arsenic removal (over 99%) from high-arsenic water (5mg/l arsenic concentration), producing a cleaned water with the residual arsenic concentration of 13 microg/l. It has been found that the mechanism by which coarse calcite enhanced the coagulation of high-arsenic water might be due to attractive electrical double layer interaction between small arsenic-borne coagulates and calcite particles, which leads to non-existence of a potential energy barrier between the heterogeneous particles.

  17. [Mechanism of groundwater As(V) removal with ferric flocculation and direct filtration].

    PubMed

    Kang, Ying; Duan, Jin-Ming; Jing, Chuan-Yong

    2015-02-01

    The As removal process and mechanism from groundwater using ferric flocculation-direct filtration system was investigated using batch, field pilot tests, extended X-ray absorption fine structure ( EXAFS) spectroscopy, and charge-distribution multisite complexation (CD-MUSIC) model. The results showed that arsenate [As(V)] was the dominant As species in the groundwater with a concentration of 40 μg x L(-1). The treatment system could supply 64 984 L As-safe drinking water (< 10 μg L(-1)) using Fe 1.5 mg x L(-1). Toxicity characteristic leaching procedure (TCLP) demonstrated that the leachate As was 3.4 μg x L(-1), much lower than the EPA regulatory concentration (5 mg x L(-1)). EXAFS and CD-MUSIC model indicated that As(V) was adsorbed onto ferric hydroxide via bidentate binuclear complexes in the pH range of 3 to 9.5, while formation of precipitate with Ca or Mg dominated the As removal at pH > 9.5.

  18. Combining Ferric Salt and Cactus Mucilage for Arsenic Removal from Water.

    PubMed

    Fox, Dawn I; Stebbins, Daniela M; Alcantar, Norma A

    2016-03-01

    New methods to remediate arsenic-contaminated water continue to be studied, particularly to fill the need for accessible methods that can significantly impact developing communities. A combination of cactus mucilage and ferric (Fe(III)) salt was investigated as a flocculation-coagulation system to remove arsenic (As) from water. As(V) solutions, ferric nitrate, and mucilage suspensions were mixed and left to stand for various periods of time. Visual and SEM observations confirmed the flocculation action of the mucilage as visible flocs formed and settled to the bottom of the tubes within 3 min. The colloidal suspensions without mucilage were stable for up to 1 week. Sample aliquots were tested for dissolved and total arsenic by ICP-MS and HGAFS. Mucilage treatment improved As removal (over Fe(III)-only treatment); the system removed 75-96% As in 30 min. At neutral pH, removal was dependent on Fe(III) and mucilage concentration and the age of the Fe(III) solution. The process is fast, achieving maximum removal in 30 min, with the majority of As removed in 10-15 min. Standard jar tests with 1000 μg/L As(III) showed that arsenic removal and settling rates were pH-dependent; As removal was between 52% (high pH) and 66% (low pH). PMID:26824141

  19. The effect of cupric and ferric ions on antioxidant properties of human serum albumi.

    PubMed

    Rezaei Behbehani, Gholamreza; Gonbadi, Katayon; Eslami, Nasrin

    2014-01-01

    The interaction of both ferric (Fe³⁺) and cupric (Cu²⁺) ions with human serum albumin (HSA) was assayed at a temperature of 27°C in aqueous solution using isothermal titration calorimetry. The association equilibrium constant and the molar enthalpy for one binding is 1.7 × 10⁵ M-1 and -31.37 kJ • M⁻¹, respectively. To obtain the binding parameters of metal ion-protein interaction over the whole range of Fe³⁺ concentrations, the extended solvation model was applied. The solvation parameters obtained from this model were attributed to the structural change of HSA. The binding parameters obtained from the extended solvation model indicate that the stability of HSA was decreased as a result of its binding with ferric ions, which cause dampening the antioxidant property of HSA. Cuperic ion increases the stability of HSA considerably, indicating that the antioxidant property of human serum albumin are increased as a result of its interaction with cupric ion.

  20. Chlorinated aromatic compounds in a thermal process promoted by oxychlorination of ferric chloride.

    PubMed

    Fujimori, Takashi; Takaoka, Masaki; Morisawa, Shinsuke

    2010-03-15

    The relationship between the formation of chlorinated aromatic (aromatic-Cl) compounds and ferric chloride in the solid phase during a thermal process motivated us to study the chemical characteristics of iron in a model solid sample, a mixture of FeCl(3) x 6H(2)O, activated carbon, and boron nitride, with increasing temperature. Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed drastic changes in the chemical form of amorphous iron, consistent with other analytical methods, such as X-ray diffraction using synchrotron radiation (SR-XRD) and Fourier-transform infrared (FT-IR) spectroscopy. Atomic-scale evidence of the chlorination of aromatic carbon was detected by Cl-K X-ray absorption near edge structure (XANES) spectroscopy. These results showed the thermal formation mechanism of aromatic-Cl compounds in the solid phase with ferric chloride. We attribute the formation of aromatic-Cl compounds to the chlorination of carbon, based on the oxychlorination reaction of FeCl(3) at temperatures in excess of ca. 300 degrees C, when the carbon matrix is activated by carbon gasification, catalyzed by Fe(2)O(3), and surface oxygen complexes (SOC) generated by a catalytic cycle of FeCl(2) and FeOCl. Chemical changes of trace iron in a thermal process may offer the potential to generate aromatic-Cl compounds in the solid phase.

  1. Effect of ionic strength on ligand exchange kinetics between a mononuclear ferric citrate complex and siderophore desferrioxamine B

    NASA Astrophysics Data System (ADS)

    Ito, Hiroaki; Fujii, Manabu; Masago, Yoshifumi; Waite, T. David; Omura, Tatsuo

    2015-04-01

    The effect of ionic strength (I) on the ligand exchange reaction between a mononuclear ferric citrate complex and the siderophore, desferrioxamine B (DFB), was examined in the NaCl concentration range of 0.01-0.5 M, particularly focusing on the kinetics and mechanism of ligand exchange under environmentally relevant conditions. Overall ligand exchange rate constants were determined by spectrophotometrically measuring the time course of ferrioxamine B formation at a water temperature of 25 °C, pH 8.0, and citrate/Fe molar ratios of 500-5000. The overall ligand exchange rate decreased by 2-11-fold (depending on the citrate/Fe molar ratios) as I increased from approximately 0.01 to 0.5 M. In particular, a relatively large decrease was observed at lower I (<0.1 M). A ligand exchange model describing the effect of I on the ligand exchange rate via disjunctive and adjunctive pathways was developed by considering the pseudo-equilibration of ferric citrate complexes and subsequent ferrioxamine formation on the basis of the Eigen-Wilkins metal-ligand complexation theory. The model and experimental data consistently suggest that the adjunctive pathway (i.e., direct association of DFB with ferric mono- and di-citrate complexes following dissociation of citrate from the parent complexes) dominates in ferrioxamine formation under the experimental conditions used. The model also predicts that the higher rate of ligand exchange at lower I is associated with the decrease in the ferric dicitrate complex stability because of the relatively high electrical repulsion between ferric monocitrate and free citrate at lower I (note that the reactivity of ferric dicitrate with DFB is smaller than that for the monocitrate complex). Overall, the findings of this study contribute to the understanding of the potential effect of I on ligand exchange kinetics in natural waters and provide fundamental knowledge on iron transformation and bioavailability.

  2. Oxidative degradation of hydrocortisone in presence of attapulgite.

    PubMed

    Cornejo, J; Hermosin, M C; White, J L; Peck, G E; Hem, S L

    1980-08-01

    Degradation of hydrocortisone in attapulgite suspensions was monitored by high-pressure liquid chromatography and UV spectrophotometry. The rate of oxidative degration of hydrocortisone was accelerated significantly in the presence of attapulgite. In addition, degradation appeared to be composed of two apparent first-order reactions rather than the single apparent first-order degradation reaction observed for hydrocortisone solutions. However, the same degradation products were obtained in both hydrocortisone solutions and attapulgite suspensions, indicating that interaction with attapulgite did not alter the degradation pathway. Kinetic and adsorption studies suggested that hydrocortisone is adsorbed weakly by attapulgite and undergoes oxidative degradation, which is catalyzed by adsorbed iron oxides or hydroxides as well as by structural ferric iron at the clay surface. Since clay minerals generally contain surface ferric iron, the potentiala for accelerating the oxidative degradation of drugs should be considered whenever clays and drugs are combined.

  3. Polybenzimidazole block copolymers for fuel cell: synthesis and studies of block length effects on nanophase separation, mechanical properties, and proton conductivity of PEM.

    PubMed

    Maity, Sudhangshu; Jana, Tushar

    2014-05-14

    A series of meta-polybenzimidazole-block-para-polybenzimidazole (m-PBI-b-p-PBI), segmented block copolymers of PBI, were synthesized with various structural motifs and block lengths by condensing the diamine terminated meta-PBI (m-PBI-Am) and acid terminated para-PBI (p-PBI-Ac) oligomers. NMR studies and existence of two distinct glass transition temperatures (Tg), obtained from dynamical mechanical analysis (DMA) results, unequivocally confirmed the formation of block copolymer structure through the current polymerization methodology. Appropriate and careful selection of oligomers chain length enabled us to tailor the block length of block copolymers and also to make varieties of structural motifs. Increasingly distinct Tg peaks with higher block length of segmented block structure attributed the decrease in phase mixing between the meta-PBI and para-PBI blocks, which in turn resulted into nanophase segregated domains. The proton conductivities of proton exchange membrane (PEM) developed from phosphoric acid (PA) doped block copolymer membranes were found to be increasing substantially with increasing block length of copolymers even though PA loading of these membranes did not alter appreciably with varying block length. For example when molecular weight (Mn) of blocks were increased from 1000 to 5500 then the proton conductivities at 160 °C of resulting copolymers increased from 0.05 to 0.11 S/cm. Higher block length induced nanophase separation between the blocks by creating less morphological barrier within the block which facilitated the movement of the proton in the block and hence resulting higher proton conductivity of the PEM. The structural varieties also influenced the phase separation and proton conductivity. In comparison to meta-para random copolymers reported earlier, the current meta-para segmented block copolymers were found to be more suitable for PBI-based PEM.

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

    PubMed

    Falagán, Carmen; Johnson, D Barrie

    2014-11-01

    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)).

  5. Concerted loop motion triggers induced fit of FepA to ferric enterobactin

    PubMed Central

    Smallwood, Chuck R.; Jordan, Lorne; Trinh, Vy; Schuerch, Daniel W.; Gala, Amparo; Hanson, Mathew; Shipelskiy, Yan; Majumdar, Aritri; Newton, Salete M.C.

    2014-01-01

    Spectroscopic analyses of fluorophore-labeled Escherichia coli FepA described dynamic actions of its surface loops during binding and transport of ferric enterobactin (FeEnt). When FeEnt bound to fluoresceinated FepA, in living cells or outer membrane fragments, quenching of fluorophore emissions reflected conformational motion of the external vestibular loops. We reacted Cys sulfhydryls in seven surface loops (L2, L3, L4, L5, L7 L8, and L11) with fluorophore maleimides. The target residues had different accessibilities, and the labeled loops themselves showed variable extents of quenching and rates of motion during ligand binding. The vestibular loops closed around FeEnt in about a second, in the order L3 > L11 > L7 > L2 > L5 > L8 > L4. This sequence suggested that the loops bind the metal complex like the fingers of two hands closing on an object, by individually adsorbing to the iron chelate. Fluorescence from L3 followed a biphasic exponential decay as FeEnt bound, but fluorescence from all the other loops followed single exponential decay processes. After binding, the restoration of fluorescence intensity (from any of the labeled loops) mirrored cellular uptake that depleted FeEnt from solution. Fluorescence microscopic images also showed FeEnt transport, and demonstrated that ferric siderophore uptake uniformly occurs throughout outer membrane, including at the poles of the cells, despite the fact that TonB, its inner membrane transport partner, was not detectable at the poles. PMID:24981231

  6. ENDOR investigation of the liganding environment of mixed-spin ferric cytochrome c'.

    PubMed

    Usov, Oleg M; Choi, Peter S-T; Shapleigh, James P; Scholes, Charles P

    2005-07-01

    The electronic structure of the 5-coordinate quantum-mechanically mixed-spin (sextet-quartet) heme center in cytochrome c' was investigated by electron nuclear double resonance (ENDOR), a technique not previously applied to this mixed-spin system. Cytochrome c' was obtained from overexpressing variants of Rhodobacter sphaeroides 2.4.3. ENDOR for this study was done at the g(//) = 2.00 extremum where single-crystal-like, well-resolved spectra prevail. The heme meso protons of cytochrome c' showed a contact interaction that implied spin delocalization arising from the heme (d(z)(2)) orbital enhanced by iron out-of-planarity. An exchangeable proton ENDOR feature appeared from the proximal His123 Ndelta hydrogen. This Ndelta hydrogen, which crystallographically has no hydrogen-bonding partner and thus belongs to a neutral imidazole, showed a larger hyperfine coupling than the corresponding hydrogen-bonded Ndelta proton from metmyoglobin. The unique residue Phe14 occludes binding of a sixth ligand in cytochrome c', and ENDOR from a proton of the functionally important Phe14 ring, approximately 3.3 A away from the heme iron, was detected. ENDOR of the nitrogen ligand hyperfine structure is a direct probe into the sigma-antibonding (d(z)(2)) and (d(x)(2)-d(y)(2)) orbitals whose energies alter the relative stability and admixture of sextet and quartet states and whose electronic details were thus elucidated. ENDOR frequencies showed for cytochrome c' larger hyperfine couplings to the histidine nitrogen and smaller hyperfine couplings to the heme nitrogens than for high-spin ferric hemes. Both of these findings followed from the mixed-spin ground state, which has less (d(x)(2)-d(y)(2)) character than have fully high-spin ferric heme systems.

  7. Binding of ferric heme by the recombinant globin from the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Lecomte, J T; Scott, N L; Vu, B C; Falzone, C J

    2001-05-29

    The product of the cyanobacterium Synechocystis sp. PCC 6803 gene slr2097 is a 123 amino acid polypeptide chain belonging to the truncated hemoglobin family. Recombinant, ferric heme-reconstituted Synechocystis sp. PCC 6803 hemoglobin is a low-spin complex whose endogenous hexacoordination gives rise to optical and NMR characteristics reminiscent of cytochrome b(5) [Scott, N. L., and Lecomte, J. T. J. (2000) Protein Sci. 9, 587-597]. In this work, the sequential assignments using (15)N-(13)C-labeled protein, (1)H nuclear Overhauser effects, and longitudinal relaxation data identified His70 as the proximal histidine and His46 as the sixth ligand to the iron ion. It was also found that one of two possible heme orientations within the protein matrix is highly preferred (>90%) and that this orientation is the same as in vertebrate myoglobins. The rate constant for the 180 degrees rotation of the heme within a protein cage to produce the favored isomer was 0.5 h(-1) at 25 degrees C, approximately 35 times faster than in sperm whale myoglobin. Variable temperature studies revealed an activation energy of 132 +/- 4 kJ mol(-1), similar to the value in metaquomyoglobin at the same pH. The rate constant for heme loss from the major isomer was estimated to be 0.01 h(-1) by optical spectroscopy, close to the value for myoglobin and decades slower than in the related Nostoc commune cyanoglobin. The slow heme loss was attributed in part to the additional coordination bond to His46, whereas the relatively fast rate of heme reorientation suggested that this bond was weaker than the proximal His70-Fe bond. The standard reduction potential of the hexacoordinated protein was measured with and without poly-L-lysine as a mediator and found to be approximately -150 mV vs SHE, indicating a stabilization of the ferric state compared to most hemoglobins and b(5) cytochromes. PMID:11371218

  8. Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots. [Phadeolus vulgaris L. var Prelude

    SciTech Connect

    Cakmak, I.; van de Wetering, D.A.M.; Marschner, H.; Bienfait, H.F.

    1987-09-01

    The recent proposal of Tipton and Thowsen that iron-deficient plants reduce ferric chelates in cell walls by a system dependent on the leakage of malate from root cells was tested. Results are presented showing that this mechanism could not be responsible for the high rates of ferric reduction shown by roots of iron-deficient bean (Phaseolus vulgaris L. var Prelude) plants. The role of O/sub 2/ in the reduction of ferric chelates by roots of iron-deficient bean plants was also tested. The rate of Fe(III) reduction was the same in the presence and in the absence of O/sub 2/. However, in the presence of O/sub 2/ the reaction was partially inhibited by superoxide dismutase (SOD), which indicates a role for the superoxide radical, O/sub 2//sup -/, as a facultative intermediate electron carrier. The inhibition by SOD increased with substrate pH and with decrease in concentration of the ferrous scavenger bathophenanthroline-disulfonate. The results are consistent with a mechanism for transmembrane electron in which a flavin or quinone is the final electron carrier in the plasma membrane. The results are discussed in relation to the ecological importance that O/sub 2//sup -/ may have in the acquisition of ferric iron by dicotyledonous plants.

  9. Managing hyperphosphatemia in patients with chronic kidney disease on dialysis with ferric citrate: latest evidence and clinical usefulness

    PubMed Central

    Fadem, Stephen Z.; Kant, Kotagal S.; Bhatt, Udayan; Sika, Mohammed; Lewis, Julia B.; Negoi, Dana

    2015-01-01

    Ferric citrate is a novel phosphate binder that allows the simultaneous treatment of hyperphosphatemia and iron deficiency in patients being treated for end-stage renal disease with hemodialysis (HD). Multiple clinical trials in HD patients have uniformly and consistently demonstrated the efficacy of the drug in controlling hyperphosphatemia with a good safety profile, leading the US Food and Drug Administration in 2014 to approve its use for that indication. A concurrent beneficial effect, while using ferric citrate as a phosphate binder, is its salutary effect in HD patients with iron deficiency being treated with an erythropoietin-stimulating agent (ESA) in restoring iron that becomes available for reversing chronic kidney disease (CKD)-related anemia. Ferric citrate has also been shown in several studies to diminish the need for intravenous iron treatment and to reduce the requirement for ESA. Ferric citrate is thus a preferred phosphate binder that helps resolve CKD-related mineral bone disease and iron-deficiency anemia. PMID:26336594

  10. Viewing the Valence Electronic Structure of Ferric and Ferrous Hexacyanide in Solution from the Fe and Cyanide Perspectives.

    PubMed

    Kunnus, Kristjan; Zhang, Wenkai; Delcey, Mickaël G; Pinjari, Rahul V; Miedema, Piter S; Schreck, Simon; Quevedo, Wilson; Schröder, Henning; Föhlisch, Alexander; Gaffney, Kelly J; Lundberg, Marcus; Odelius, Michael; Wernet, Philippe

    2016-07-28

    The valence-excited states of ferric and ferrous hexacyanide ions in aqueous solution were mapped by resonant inelastic X-ray scattering (RIXS) at the Fe L2,3 and N K edges. Probing of both the central Fe and the ligand N atoms enabled identification of the metal- and ligand-centered excited states, as well as ligand-to-metal and metal-to-ligand charge-transfer excited states. Ab initio calculations utilizing the RASPT2 method were used to simulate the Fe L2,3-edge RIXS spectra and enabled quantification of the covalencies of both occupied and empty orbitals of π and σ symmetry. We found that π back-donation in the ferric complex is smaller than that in the ferrous complex. This is evidenced by the relative amounts of Fe 3d character in the nominally 2π CN(-) molecular orbital of 7% and 9% in ferric and ferrous hexacyanide, respectively. Utilizing the direct sensitivity of Fe L3-edge RIXS to the Fe 3d character in the occupied molecular orbitals, we also found that the donation interactions are dominated by σ bonding. The latter was found to be stronger in the ferric complex, with an Fe 3d contribution to the nominally 5σ CN(-) molecular orbitals of 29% compared to 20% in the ferrous complex. These results are consistent with the notion that a higher charge at the central metal atom increases donation and decreases back-donation. PMID:27380541

  11. Studying Equilibrium in the Chemical Reaction between Ferric and Iodide Ions in Solution Using a Simple and Inexpensive Approach

    ERIC Educational Resources Information Center

    Nikolaychuk, Pavel Anatolyevich; Kuvaeva, Alyona Olegovna

    2016-01-01

    A laboratory experiment on the study of the chemical equilibrium based on the reaction between ferric and iodide ions in solution with the formation of ferrous ions, free iodine, and triiodide ions is developed. The total concentration of iodide and triiodide ions in the reaction mixture during the reaction is determined by the argentometric…

  12. Managing hyperphosphatemia in patients with chronic kidney disease on dialysis with ferric citrate: latest evidence and clinical usefulness.

    PubMed

    Yagil, Yoram; Fadem, Stephen Z; Kant, Kotagal S; Bhatt, Udayan; Sika, Mohammed; Lewis, Julia B; Negoi, Dana

    2015-09-01

    Ferric citrate is a novel phosphate binder that allows the simultaneous treatment of hyperphosphatemia and iron deficiency in patients being treated for end-stage renal disease with hemodialysis (HD). Multiple clinical trials in HD patients have uniformly and consistently demonstrated the efficacy of the drug in controlling hyperphosphatemia with a good safety profile, leading the US Food and Drug Administration in 2014 to approve its use for that indication. A concurrent beneficial effect, while using ferric citrate as a phosphate binder, is its salutary effect in HD patients with iron deficiency being treated with an erythropoietin-stimulating agent (ESA) in restoring iron that becomes available for reversing chronic kidney disease (CKD)-related anemia. Ferric citrate has also been shown in several studies to diminish the need for intravenous iron treatment and to reduce the requirement for ESA. Ferric citrate is thus a preferred phosphate binder that helps resolve CKD-related mineral bone disease and iron-deficiency anemia. PMID:26336594

  13. Comparative Evaluation of Aluminum Sulfate and Ferric Sulfate-Induced Coagulations as Pretreatment of Microfiltration for Treatment of Surface Water.

    PubMed

    Song, Yali; Dong, Bingzhi; Gao, Naiyun; Deng, Yang

    2015-06-12

    Two coagulants, aluminum sulfate and ferric chloride, were tested to reduce natural organic matter (NOM) as a pretreatment prior to polyvinylidene fluoride (PVDF) microfiltration (MF) membranes for potable water treatment. The results showed that the two coagulants exhibited different treatment performance in NOM removal. Molecular weight (MW) distributions of NOM in the tested surface raw water were concentrated at 3-5 kDa and approximately 0.2 kDa. Regardless of the coagulant species and dosages, the removal of 0.2 kDa NOM molecules was limited. In contrast, NOM at 3-5 kDa were readily removed with increasing coagulant dosages. In particular, aluminum sulfate favorably removed NOM near 5 kDa, whereas ferric chloride tended to reduce 3 kDa organic substances. Although aluminum sulfate and ferric chloride could improve the flux of the ensuing MF treatment, the optimal coagulant dosages to achieve effective pretreatment were different: 2-30 mg/L for aluminum sulfate and >15 mg/L for ferric chloride. The scanning electron microscope (SEM) image of the membrane-filtered coagulated raw water showed that coagulation efficiency dramatically affected membrane flux and that good coagulation properties can reduce membrane fouling.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  15. Ferrous iron oxidation by Thiobacillus ferrooxidans: inhibition with benzoic acid, sorbic acid and sodium lauryl sulfate

    SciTech Connect

    Onysko, S.J.

    1984-07-01

    Acid mine drainage is formed by the weathering or oxidation of pyritic material exposed during coal mining. The rate of pyritic material oxidation can be greatly accelerated by certain acidophilic bacteria such as Thiobacillus ferrooxidans which catalyse the oxidation of ferrous to ferric iron. A number of organic compounds, under laboratory conditions, can apparently inhibit both the oxidation of ferrous to ferric iron by T. ferrooxidans and the weathering of pyritic material by mixed cultures of acid mine drainage micro-organisms. Sodium lauryl sulphate (SLS), an anionic surfactant has proved effective in this respect. Benzoic acid, sorbic acid and SLS at low concentrations, each effectively inhibited bacterial oxidation of ferrous iron in batch cultures of T. ferrooxidans. The rate of chemical oxidation of ferrous iron in low pH, sterile, batch reactors was not substantially affected at the tested concentrations of any of the compounds.

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

    SciTech Connect

    V. P. Evangelou

    1997-04-14

    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.

  17. Studies on Synthesis of Electrochemically Exfoliated Functionalized Graphene and Polylactic Acid/Ferric Phytate Functionalized Graphene Nanocomposites as New Fire Hazard Suppression Materials.

    PubMed

    Feng, Xiaming; Wang, Xin; Cai, Wei; Qiu, Shuilai; Hu, Yuan; Liew, Kim Meow

    2016-09-28

    Practical application of functionalized graphene in polymeric nanocomposites is hampered by the lack of cost-effective and eco-friendly methods for its production. Here, we reported a facile and green electrochemical approach for preparing ferric phytate functionalized graphene (f-GNS) by simultaneously utilizing biobased phytic acid as electrolyte and modifier for the first time. Due to the presence of phytic acid, electrochemical exfoliation leads to low oxidized graphene sheets (a C/O ratio of 14.8) that are tens of micrometers large. Successful functionalization of graphene was confirmed by the appearance of phosphorus and iron peaks in the X-ray photoelectron spectrum. Further, high-performance polylactic acid/f-GNS nanocomposites are readily fabricated by a convenient masterbatch strategy. Notably, inclusion of well-dispersed f-GNS resulted in dramatic suppression on fire hazards of polylactic acid in terms of reduced peak heat-release rate (decreased by 40%), low CO yield, and formation of a high graphitized protective char layer. Moreover, obviously improvements in crystallization rate and thermal conductivities of polylactic acid nanocomposites were observed, highlighting its promising potential in practical application. This novel strategy toward the simultaneous exfoliation and functionalization for graphene demonstrates a simple yet very effective approach for fabricating graphene-based flame retardants.

  18. Studies on Synthesis of Electrochemically Exfoliated Functionalized Graphene and Polylactic Acid/Ferric Phytate Functionalized Graphene Nanocomposites as New Fire Hazard Suppression Materials.

    PubMed

    Feng, Xiaming; Wang, Xin; Cai, Wei; Qiu, Shuilai; Hu, Yuan; Liew, Kim Meow

    2016-09-28

    Practical application of functionalized graphene in polymeric nanocomposites is hampered by the lack of cost-effective and eco-friendly methods for its production. Here, we reported a facile and green electrochemical approach for preparing ferric phytate functionalized graphene (f-GNS) by simultaneously utilizing biobased phytic acid as electrolyte and modifier for the first time. Due to the presence of phytic acid, electrochemical exfoliation leads to low oxidized graphene sheets (a C/O ratio of 14.8) that are tens of micrometers large. Successful functionalization of graphene was confirmed by the appearance of phosphorus and iron peaks in the X-ray photoelectron spectrum. Further, high-performance polylactic acid/f-GNS nanocomposites are readily fabricated by a convenient masterbatch strategy. Notably, inclusion of well-dispersed f-GNS resulted in dramatic suppression on fire hazards of polylactic acid in terms of reduced peak heat-release rate (decreased by 40%), low CO yield, and formation of a high graphitized protective char layer. Moreover, obviously improvements in crystallization rate and thermal conductivities of polylactic acid nanocomposites were observed, highlighting its promising potential in practical application. This novel strategy toward the simultaneous exfoliation and functionalization for graphene demonstrates a simple yet very effective approach for fabricating graphene-based flame retardants. PMID:27588582

  19. The Phosphate Binder Ferric Citrate and Mineral Metabolism and Inflammatory Markers in Maintenance Dialysis Patients: Results From Prespecified Analyses of a Randomized Clinical Trial

    PubMed Central

    Van Buren, Peter N.; Lewis, Julia B.; Dwyer, Jamie P.; Greene, Tom; Middleton, John; Sika, Mohammed; Umanath, Kausik; Abraham, Josephine D.; Arfeen, Shahabul S.; Bowline, Isai G.; Chernin, Gil; Fadem, Stephen Z.; Goral, Simin; Koury, Mark; Sinsakul, Marvin V.; Weiner, Daniel E.

    2016-01-01

    Background Phosphate binders are the cornerstone of hyperphosphatemia management in dialysis patients. Ferric citrate is an iron-based oral phosphate binder that effectively lowers serum phosphorus levels. Study Design 52-week, open-label, phase 3, randomized, controlled trial for safety-profile assessment. Setting & Participants Maintenance dialysis patients with serum phosphorus levels ≥6.0 mg/dL after washout of prior phosphate binders. Intervention 2:1 randomization to ferric citrate or active control (sevelamer carbonate and/or calcium acetate). Outcomes Changes in mineral bone disease, protein-energy wasting/inflammation, and occurrence of adverse events after 1 year. Measurements Serum calcium, intact parathyroid hormone, phosphorus, aluminum, white blood cell count, percentage of lymphocytes, serum urea nitrogen, and bicarbonate. Results There were 292 participants randomly assigned to ferric citrate, and 149, to active control. Groups were well matched. For mean changes from baseline, phosphorus levels decreased similarly in the ferric citrate and active control groups (−2.04 ± 1.99 [SD] vs −2.18 ± 2.25 mg/dL, respectively; P = 0.9); serum calcium levels increased similarly in the ferric citrate and active control groups (0.22 ± 0.90 vs 0.31 ± 0.95 mg/dL; P = 0.2). Hypercalcemia occurred in 4 participants receiving calcium acetate. Parathyroid hormone levels decreased similarly in the ferric citrate and active control groups (−167.1 ± 399.8 vs −152.7 ± 392.1 pg/mL; P = 0.8). Serum albumin, bicarbonate, serum urea nitrogen, white blood cell count and percentage of lymphocytes, and aluminum values were similar between ferric citrate and active control. Total and low-density lipoprotein cholesterol levels were lower in participants receiving sevelamer than those receiving ferric citrate and calcium acetate. Fewer participants randomly assigned to ferric citrate had serious adverse events compared with active control. Limitations Open

  20. The regulatory role of ferric uptake regulator (Fur) during anaerobic respiration of Shewanella piezotolerans WP3.

    PubMed

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

    2013-01-01

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

  1. Metal-responsive promoter DNA compaction by the ferric uptake regulator.

    PubMed

    Roncarati, Davide; Pelliciari, Simone; Doniselli, Nicola; Maggi, Stefano; Vannini, Andrea; Valzania, Luca; Mazzei, Luca; Zambelli, Barbara; Rivetti, Claudio; Danielli, Alberto

    2016-01-01

    Short-range DNA looping has been proposed to affect promoter activity in many bacterial species and operator configurations, but only few examples have been experimentally investigated in molecular detail. Here we present evidence for a metal-responsive DNA condensation mechanism controlled by the Helicobacter pylori ferric uptake regulator (Fur), an orthologue of the widespread Fur family of prokaryotic metal-dependent regulators. H. pylori Fur represses the transcription of the essential arsRS acid acclimation operon through iron-responsive oligomerization and DNA compaction, encasing the arsR transcriptional start site in a repressive macromolecular complex. A second metal-dependent regulator NikR functions as nickel-dependent anti-repressor at this promoter, antagonizing the binding of Fur to the operator elements responsible for the DNA condensation. The results allow unifying H. pylori metal ion homeostasis and acid acclimation in a mechanistically coherent model, and demonstrate, for the first time, the existence of a selective metal-responsive DNA compaction mechanism controlling bacterial transcriptional regulation. PMID:27558202

  2. Mechanistic insights into metal ion activation and operator recognition by the ferric uptake regulator

    NASA Astrophysics Data System (ADS)

    Deng, Zengqin; Wang, Qing; Liu, Zhao; Zhang, Manfeng; Machado, Ana Carolina Dantas; Chiu, Tsu-Pei; Feng, Chong; Zhang, Qi; Yu, Lin; Qi, Lei; Zheng, Jiangge; Wang, Xu; Huo, Xinmei; Qi, Xiaoxuan; Li, Xiaorong; Wu, Wei; Rohs, Remo; Li, Ying; Chen, Zhongzhou

    2015-07-01

    Ferric uptake regulator (Fur) plays a key role in the iron homeostasis of prokaryotes, such as bacterial pathogens, but the molecular mechanisms and structural basis of Fur-DNA binding remain incompletely understood. Here, we report high-resolution structures of Magnetospirillum gryphiswaldense MSR-1 Fur in four different states: apo-Fur, holo-Fur, the Fur-feoAB1 operator complex and the Fur-Pseudomonas aeruginosa Fur box complex. Apo-Fur is a transition metal ion-independent dimer whose binding induces profound conformational changes and confers DNA-binding ability. Structural characterization, mutagenesis, biochemistry and in vivo data reveal that Fur recognizes DNA by using a combination of base readout through direct contacts in the major groove and shape readout through recognition of the minor-groove electrostatic potential by lysine. The resulting conformational plasticity enables Fur binding to diverse substrates. Our results provide insights into metal ion activation and substrate recognition by Fur that suggest pathways to engineer magnetotactic bacteria and antipathogenic drugs.

  3. Granular ferric hydroxide adsorbent for phosphate removal: demonstration preparation and field study.

    PubMed

    Zhao, Bei; Zhang, Yu; Dou, Xiaomin; Yuan, Hongying; Yang, Min

    2015-01-01

    Ferric hydroxide (FHO), which has high phosphate adsorption capacity, was prepared by precipitation at industrial scale and then fabricated via the drum granulation method with cross-linked poly(vinyl alcohol) as the binder. The optimum binder/FHO powder ratio was 0.6 for producing a granular adsorbent with a high phosphate adsorption capacity and stability. The Langmuir maximum adsorption capacities of powder and granular FHOs were 74.07 mg g⁻¹ and 56.18 mg g(-1) at pH 7.0 ± 0.2, respectively, which were higher than those of other reported phosphate adsorbents under neutral or acidic conditions. Phosphate-loaded granular FHO could be regenerated by NaOH solution. Columns containing the granular FHO were used for phosphate removal from ozonated secondary effluents of a municipal wastewater treatment plant at space velocity (SV) of 2 and 5 h⁻¹. During more than 2 months' operation, the average removal percentage of PO(4)(3-) was more than 90% and the turbidity and concentration of CODMn in the effluents were lower than in the influents. In addition, energy dispersive X-ray results suggested that active sites inside the granular FHO were available for phosphate removal. The results demonstrated that granular FHO can be applied as an assist technology for phosphate removal from secondary effluents.

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

    PubMed

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

    2011-01-01

    The characteristics and kinetics of phosphate (P) adsorption on dewatered ferric-alum water treatment residuals (Fe-Al-WTRs) have been investigated. The existence of both aluminum (Al) and iron (Fe) in the residuals can result in significantly high P adsorption capacities. The P adsorption kinetics of Fe-Al-WTRs exhibited an initial rapid phase, followed by a slower phase. This could be described by three models, including a pseudo-first-order equation, a pseudo-second-order equation, and a double-constant rate equation. The latter was especially good for those runs with initial P concentrations of 500 and 1000 mg L(-1). Both the Langmuir and Freundlich isotherms fit the experimental data well, particularly the Freundlich isotherm, which had a correlation coefficient of 0.9930. The maximum measured P adsorption capacity of Fe-Al-WTRs was 45.42 mg g(-1), which is high when compared to those of most WTRs, as well as other reported adsorbents. The results also show that the P adsorption is a spontaneous endothermic process. Highest P adsorption capacities of Fe-Al-WTRs were measured at low pHs and a particle size range of 0.6 to 0.9 mm.

  5. Differential responses of soil nematode community to pig manure application levels in Ferric Acrisols

    PubMed Central

    Yang, Yi-Ru; Li, Xiao-Gang; Zhou, Zhi-Gao; Zhang, Tao-Lin; Wang, Xing-Xiang

    2016-01-01

    Excessive pig manure application probably degrades arable soil quality in some intensive pig farming areas. The responses of the nematode community to dosages of pig manure were investigated in Ferric Acrisols under 3-season peanut monoculture. Varying dosages of manure (1.75, 3.5, 7, 14 and 28 t·ha−1·yr−1) in combination with chemical fertilizer were applied to field plots, and chemical fertilizer alone was also applied as a control. With increasing manure application, the abundance of bacterivores and omnivores-predators increased, the abundance of plant parasites decreased, and fungivores abundance exhibited hump-shaped variation. Simpson diversity index and plant parasite index/maturity index of the nematode communities increased to a maximum level at a manure application rate of 3.5 t·ha−1·yr−1 and then sharply decreased. The changes in the soil nematode community were further determined to be correlated with chemical properties; available phosphorus had the strongest quadratic correlation with the two indices, implying that available phosphorus had a better indicative effect than other soil properties to nematode community. Available phosphorus in soil was deduced from 49 to 64 mg·kg−1 with the best nematode communities. Our results emphasized the importance of regular applications of manure in agriculture field to balance nematode diversity and build healthy agro-ecosystems. PMID:27734955

  6. Ultrafast Heme Dynamics of Ferric Cytochrome c in Different Environments: Electronic, Vibrational, and Conformational Relaxation.

    PubMed

    Karunakaran, Venugopal

    2015-12-21

    The excited-state dynamics of ferric cytochrome c (Cyt c), an important electron-transfer heme protein, in acidic to alkaline medium and in its unfolded form are investigated by using femtosecond pump-probe spectroscopy, exciting the heme and Tryptophan (Trp) to understand the electronic, vibrational, and conformational relaxation of the heme. At 390 nm excitation, the electronic relaxation of heme is found to be ≈150 fs at different pH values, increasing to 480 fs in the unfolded form. Multistep vibrational relaxation dynamics of the heme, including fast and slow processes, are observed at pH 7. However, in the unfolded form and at pH 2 and 11, fast phases of vibrational relaxation dominate, revealing the energy dissipation occurring through the covalent bond interaction between the heme and the nearest amino acids. A significant shortening of the excited-state lifetime of Trp is observed at various pH values at 280 nm excitation due to resonance energy transfer to the heme. The longer time constant (25 ps) observed in the unfolded form is attributed to a complete global conformational relaxation of Cyt c.

  7. Investigations of the low frequency modes of ferric cytochrome c using vibrational coherence spectroscopy.

    PubMed

    Karunakaran, Venugopal; Sun, Yuhan; Benabbas, Abdelkrim; Champion, Paul M

    2014-06-12

    Femtosecond vibrational coherence spectroscopy is used to investigate the low frequency vibrational dynamics of the electron transfer heme protein, cytochrome c (cyt c). The vibrational coherence spectra of ferric cyt c have been measured as a function of excitation wavelength within the Soret band. Vibrational coherence spectra obtained with excitation between 412 and 421 nm display a strong mode at ~44 cm(-1) that has been assigned to have a significant contribution from heme ruffling motion in the electronic ground state. This assignment is based partially on the presence of a large heme ruffling distortion in the normal coordinate structural decomposition (NSD) analysis of the X-ray crystal structures. When the excitation wavelength is moved into the ~421-435 nm region, the transient absorption increases along with the relative intensity of two modes near ~55 and 30 cm(-1). The intensity of the mode near 44 cm(-1) appears to minimize in this region and then recover (but with an opposite phase compared to the blue excitation) when the laser is tuned to 443 nm. These observations are consistent with the superposition of both ground and excited state coherence in the 421-435 nm region due to the excitation of a weak porphyrin-to-iron charge transfer (CT) state, which has a lifetime long enough to observe vibrational coherence. The mode near 55 cm(-1) is suggested to arise from ruffling in a transient CT state that has a less ruffled heme due to its iron d(6) configuration.

  8. Analysis of a ferric uptake regulator (Fur) knockout mutant in Aeromonas salmonicida subsp. salmonicida.

    PubMed

    Ebanks, Roger O; Goguen, Michel; Knickle, Leah; Dacanay, Andrew; Leslie, Andrew; Ross, Neil W; Pinto, Devanand M

    2013-03-23

    Aeromonas salmonicida subsp. salmonicida is the etiological agent of furunculosis; a serious infectious disease in aquaculture raised salmonids. Iron acquisition has been shown to be critical for the survival of pathogenic bacteria during the course of infection. Previous work has demonstrated that A. salmonicida expresses iron-repressible IROMP proteins, suggesting the presence of iron acquisition systems that are under the control of a ferric uptake regulator (Fur). In this study, the A. salmonicida fur has been sequenced and a fur deletion strain generated. The A. salmonicida fur gene has an open reading frame of 428 bp, coding for a protein of 143 amino acids, and with high homology to previously described Fur proteins. The Fur protein product had a 94% sequence identity and 96% sequence similarity to the Aeromonas hydrophila Fur protein product. Transcription of the A. salmonicida fur gene was not regulated by the iron status of the bacterium and is not autoregulated, as in Escherichia coli. Proteomic analysis of the A. salmonicida fur mutant, fails to repress iron-regulated outer membrane proteins in the presence of iron. The A. salmonicida fur::KO mutant shows significantly reduced pathogenicity compared to the wild-type parental strain. In addition, the A. salmonicida fur mutant provides an important tool for further investigation of the iron acquisition mechanisms utilized by A. salmonicida.

  9. Removal of Arsenic from Water Using Granular Ferric Hydroxide: Macroscopic and Microscopic Studies

    SciTech Connect

    Guan,X.; Wang, J.; Chusuei, C.

    2008-01-01

    Removal of arsenate from water using granular ferric hydroxide (GFH) was investigated under different pH and As(V) loading conditions, using batch equilibrium adsorption, FTIR, and EXAFS methods. The arsenate adsorption envelopes on GFH exhibited broad adsorption maxima when the initial As(V) concentration was less than 500 mg/L at sorbent concentration of 10 g/L. As the initial As(V) concentration increased to 500, 1000 or 2000 mg/L for the same sorbent concentration, distinct adsorption maxima appeared and shifted to lower pH. Acidimetric-alkalimetric titration and arsenic adsorption isotherm data indicated that the surface of GFH is high heterogeneous. FTIR spectra revealed that complexes of two different structures, bidentate and monodentate, were formed upon the adsorption of arsenate on GFH, and bidentate complexes were only observed at pH values greater than 6. The EXAFS analyses confirmed that arsenate form bidentate binuclear complexes with GFH at pH 7.4 as evidenced by an average Fe-As(V) bond distance of 3.32 Angstroms.

  10. Ferric ion-assisted in situ synthesis of silver nanoplates on polydopamine-coated silk.

    PubMed

    Xiao, Jing; Zhang, Huihui; Mao, Cuiping; Wang, Ying; Wang, Ling; Lu, Zhisong

    2016-10-01

    In the present study, a ferric ion (Fe(3+))-assisted in situ synthesis approach was developed to grow silver (Ag) nanoplates on the polydopamine (PDA)-coated silk without the use of additional reductants. The essential role of Fe(3+) in the formation of Ag nanoplates is revealed by comparing the morphologies of Ag nanostructures prepared on the silk-coated PDA film with/without Fe(3+) doping. Scanning electron micrographs show that high-density Ag nanoplates could be synthesized in the reaction system containing 50μg/mL FeCl3 and 50mM AgNO3. The size of the Ag nanoplate could be tuned by adjusting the reaction duration. Based on the data, a mechanism involving the Fe(3+)-selected growth of Ag atoms along the certain crystal faces was proposed to explain the fabrication process. Transmission electron microscopy and X-ray diffractometry indicate that the Ag nanoplates possess good crystalline structures. Raman spectra demonstrate that the nanoplates could strongly enhance the Raman scattering of the PDA molecules. The Ag nanoplate-coated silk could be utilized as a flexible substrate for the development of surface-enhanced Raman scattering biosensors. PMID:27390855

  11. Glutathione-dependent extracellular ferric reductase activities in dimorphic zoopathogenic fungi

    PubMed Central

    Zarnowski, Robert; Woods, Jon P.

    2009-01-01

    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

  12. The FUR (ferric uptake regulator) superfamily: diversity and versatility of key transcriptional regulators.

    PubMed

    Fillat, María F

    2014-03-15

    Control of metal homeostasis is essential for life in all kingdoms. In most prokaryotic organisms the FUR (ferric uptake regulator) family of transcriptional regulators is involved in the regulation of iron and zinc metabolism through control by Fur and Zur proteins. A third member of this family, the peroxide-stress response PerR, is present in most Gram-positives, establishing a tight functional interaction with the global regulator Fur. These proteins play a pivotal role for microbial survival under adverse conditions and in the expression of virulence in most pathogens. In this paper we present the current state of the art in the knowledge of the FUR family, including those members only present in more reduced numbers of bacteria, namely Mur, Nur and Irr. The huge amount of work done in the two last decades shows that FUR proteins present considerable diversity in their regulatory mechanisms and interesting structural differences. However, much work needs to be done to obtain a more complete picture of this family, especially in connection with the roles of some members as gas and redox sensors as well as to fully characterize their participation in bacterial adaptative responses.

  13. Ferric Chloride-induced Thrombosis Mouse Model on Carotid Artery and Mesentery Vessel.

    PubMed

    Bonnard, Thomas; Hagemeyer, Christoph E

    2015-06-29

    Severe thrombosis and its ischemic consequences such as myocardial infarction, pulmonary embolism and stroke are major worldwide health issues. The ferric chloride injury is now a well-established technique to rapidly and accurately induce the formation of thrombi in exposed veins or artery of small and large diameter. This model has played a key role in the study of the pathophysiology of thrombosis, in the discovery and validation of novel antithrombotic drugs and in the understanding of the mechanism of action of these new agents. Here, the implementation of this technique on a mesenteric vessel and carotid artery in mice is presented. The method describes how to label circulating leukocytes and platelets with a fluorescent dye and to observe, by intravital microscopy on the exposed mesentery, their accumulation at the injured vessel wall which leads to the formation of a thrombus. On the carotid artery, the occlusion caused by the clot formation is measured by monitoring the blood flow with a Doppler probe.

  14. Ferric ion-assisted in situ synthesis of silver nanoplates on polydopamine-coated silk.

    PubMed

    Xiao, Jing; Zhang, Huihui; Mao, Cuiping; Wang, Ying; Wang, Ling; Lu, Zhisong

    2016-10-01

    In the present study, a ferric ion (Fe(3+))-assisted in situ synthesis approach was developed to grow silver (Ag) nanoplates on the polydopamine (PDA)-coated silk without the use of additional reductants. The essential role of Fe(3+) in the formation of Ag nanoplates is revealed by comparing the morphologies of Ag nanostructures prepared on the silk-coated PDA film with/without Fe(3+) doping. Scanning electron micrographs show that high-density Ag nanoplates could be synthesized in the reaction system containing 50μg/mL FeCl3 and 50mM AgNO3. The size of the Ag nanoplate could be tuned by adjusting the reaction duration. Based on the data, a mechanism involving the Fe(3+)-selected growth of Ag atoms along the certain crystal faces was proposed to explain the fabrication process. Transmission electron microscopy and X-ray diffractometry indicate that the Ag nanoplates possess good crystalline structures. Raman spectra demonstrate that the nanoplates could strongly enhance the Raman scattering of the PDA molecules. The Ag nanoplate-coated silk could be utilized as a flexible substrate for the development of surface-enhanced Raman scattering biosensors.

  15. Effect of ferrous and ferric ions on copigmentation in model solutions

    NASA Astrophysics Data System (ADS)

    Kunsági-Máté, Sándor; Ortmann, Erika; Kollár, László; Szabó, Kornélia; Nikfardjam, Martin Pour

    2008-11-01

    The thermodynamics of the molecular association process between malvidin-3- O-glucoside and ellagic acid (so-called "copigmentation") was studied in model wine solutions in the presence and absence, respectively, of ferrous and ferric ions. The Gibbs free energy, enthalpy, and entropy values of the complexation process were determined by means of a spectrofluorometric method. A combination of the Job's method with the van't Hoff theory was used for data evaluation. The results show the generally exothermic character of the process. The free enthalpy changes obtained during formation of malvidin-3- O-glucoside-ellagic acid complexes increase from -17.8 kJ/mol to -40.5 kJ/mol in the presence of Fe(II) ions. The increased free enthalpy is a consequence of the drastic reduction of entropy change due to the slight "swinging" movement of the interacting malvidin and ellagic acid molecules in the complexes stabilized by the ferrous ions. These results are also supported by the findings of other authors stating that iron ions play an important role in the stabilization of color in the plant kingdom and various plant products.

  16. CIPK23 is involved in iron acquisition of Arabidopsis by affecting ferric chelate reductase activity.

    PubMed

    Tian, Qiuying; Zhang, Xinxin; Yang, An; Wang, Tianzuo; Zhang, Wen-Hao

    2016-05-01

    Iron deficiency is one of the major limiting factors affecting quality and production of crops in calcareous soils. Numerous signaling molecules and transcription factors have been demonstrated to play a regulatory role in adaptation of plants to iron deficiency. However, the mechanisms underlying the iron deficiency-induced physiological processes remain to be fully dissected. Here, we demonstrated that the protein kinase CIPK23 was involved in iron acquisition. Lesion of CIPK23 rendered Arabidopsis mutants hypersensitive to iron deficiency, as evidenced by stronger chlorosis in young leaves and lower iron concentration than wild-type plants under iron-deficient conditions by down-regulating ferric chelate reductase activity. We found that iron deficiency evoked an increase in cytosolic Ca(2+) concentration and the elevated Ca(2+) would bind to CBL1/CBL9, leading to activation of CIPK23. These novel findings highlight the involvement of calcium-dependent CBL-CIPK23 complexes in the regulation of iron acquisition. Moreover, mutation of CIPK23 led to changes in contents of mineral elements, suggesting that CBL-CIPK23 complexes could be as "nutritional sensors" to sense and regulate the mineral homeostasis in Arabisopsis.

  17. Metal-responsive promoter DNA compaction by the ferric uptake regulator

    PubMed Central

    Roncarati, Davide; Pelliciari, Simone; Doniselli, Nicola; Maggi, Stefano; Vannini, Andrea; Valzania, Luca; Mazzei, Luca; Zambelli, Barbara; Rivetti, Claudio; Danielli, Alberto

    2016-01-01

    Short-range DNA looping has been proposed to affect promoter activity in many bacterial species and operator configurations, but only few examples have been experimentally investigated in molecular detail. Here we present evidence for a metal-responsive DNA condensation mechanism controlled by the Helicobacter pylori ferric uptake regulator (Fur), an orthologue of the widespread Fur family of prokaryotic metal-dependent regulators. H. pylori Fur represses the transcription of the essential arsRS acid acclimation operon through iron-responsive oligomerization and DNA compaction, encasing the arsR transcriptional start site in a repressive macromolecular complex. A second metal-dependent regulator NikR functions as nickel-dependent anti-repressor at this promoter, antagonizing the binding of Fur to the operator elements responsible for the DNA condensation. The results allow unifying H. pylori metal ion homeostasis and acid acclimation in a mechanistically coherent model, and demonstrate, for the first time, the existence of a selective metal-responsive DNA compaction mechanism controlling bacterial transcriptional regulation. PMID:27558202

  18. Adsorption of phosphonate antiscalant from reverse osmosis membrane concentrate onto granular ferric hydroxide.

    PubMed

    Boels, Luciaan; Keesman, Karel J; Witkamp, Geert-Jan

    2012-09-01

    Adsorptive removal of antiscalants offers a promising way to improve current reverse osmosis (RO) concentrate treatment processes and enables the reuse of the antiscalant in the RO desalination process. This work investigates the adsorption and desorption of the phosphonate antiscalant nitrilotris(methylenephosphonic acid) (NTMP) from RO membrane concentrate onto granular ferric hydroxide (GFH), a material that consists predominantly of akaganéite. The kinetics of the adsorption of NTMP onto GFH was predicted fairly well with two models that consider either combined film-pore or combined film-surface diffusion as the main mechanism for mass transport. It is also demonstrated that NTMP is preferentially adsorbed over sulfate by GFH at pH 7.85. The presence of calcium causes a transformation in the equilibrium adsorption isotherm from a Langmuir type to a Freundlich type with much higher adsorption capacities. Furthermore, calcium also increases the rate of adsorption substantially. GFH is reusable after regeneration with sodium hydroxide solution, indicating that NTMP can be potentially recovered from the RO concentrate. This work shows that GFH is a promising adsorbent for the removal and recovery of NTMP antiscalant from RO membrane concentrates.

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

    PubMed Central

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

    1994-01-01

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

  20. Adsorption of phosphonate antiscalant from reverse osmosis membrane concentrate onto granular ferric hydroxide.

    PubMed

    Boels, Luciaan; Keesman, Karel J; Witkamp, Geert-Jan

    2012-09-01

    Adsorptive removal of antiscalants offers a promising way to improve current reverse osmosis (RO) concentrate treatment processes and enables the reuse of the antiscalant in the RO desalination process. This work investigates the adsorption and desorption of the phosphonate antiscalant nitrilotris(methylenephosphonic acid) (NTMP) from RO membrane concentrate onto granular ferric hydroxide (GFH), a material that consists predominantly of akaganéite. The kinetics of the adsorption of NTMP onto GFH was predicted fairly well with two models that consider either combined film-pore or combined film-surface diffusion as the main mechanism for mass transport. It is also demonstrated that NTMP is preferentially adsorbed over sulfate by GFH at pH 7.85. The presence of calcium causes a transformation in the equilibrium adsorption isotherm from a Langmuir type to a Freundlich type with much higher adsorption capacities. Furthermore, calcium also increases the rate of adsorption substantially. GFH is reusable after regeneration with sodium hydroxide solution, indicating that NTMP can be potentially recovered from the RO concentrate. This work shows that GFH is a promising adsorbent for the removal and recovery of NTMP antiscalant from RO membrane concentrates. PMID:22873428