Sample records for nanophase ferric oxide

  1. Modified electrochromism of tungsten oxide via platinum nanophases

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

    We report electrochromic properties of WO3 modified by platinum nanophases. The WO3 incorporated by Pt metallic nanophases (Pt -WO3) showed exactly reverse electrochromic phenomenon compared with that of both pure WO3 and WO3 intercepted and coated by metallic Pt thin-film layer. In addition, to investigate the origin of modified electrochromic properties, electrodes consisting of WO3 and/or Pt layers were designed and observed in optical properties during electrochemical reaction. The change of electrochromic properties in the Pt -WO3 is caused by modified structural and electrochemical properties of the WO3 by Pt metallic nanophases dispersed in the oxide matrix.

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Morris, Richard V.; Golden, D. C.; Bell, James F., III; Lauer, Howard V., Jr.; Adams, John 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 Moessbauer and reflectance spectroscopy, X-ray diffraction, instrumental neutron activation analysis, electron probe microanalysis, transmission electron microscopy, and dithionite-citrate-bicarbonate extraction. Chemically, PN-9 has a Hawaiitic composition with alkali (and presumably silica) loss resulting from leaching by meteoric water during palagonitization; no Ce anomaly is present in the REE pattern. Mineralogically, our results show that nanophase ferric oxide (np-Ox) particles (either nanophase hematite (np-Hm) or a mixture of ferrihydrite and np-Hm) are responsible for the distinctive ferric doublet and visible-wavelength ferric absorption edge. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars.

  5. Microwave drying of ferric oxide pellets

    SciTech Connect

    Pickles, C.A.; Xia, D.K. [Queens` Univ., Kingston, Ontario (Canada). Dept. of Materials and Metallurgical Engineering

    1997-12-31

    The application of microwave energy for the drying of ferric oxide pellets has been investigated and evaluated. It is shown that the microwave drying rates are much higher than those observed in the conventional process. Also there is some potential for improved quality of the product. As a stand-alone technology it is unlikely that microwave drying would be economical for pellets due to the low cost of conventional fuels. However, based on an understanding of the drying mechanisms in the conventional process and in the microwave process, it is shown that microwave-assisted drying offers considerable potential. In this hybrid process, the advantages of the two drying techniques are combined to provide an improved drying process.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  8. ADSORPTION OF TRACE METALS BY HYDROUS FERRIC OXIDE IN SEAWATER

    EPA Science Inventory

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

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

    NASA Astrophysics Data System (ADS)

    Balasubramanian, Rama

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

  10. 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.

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

    SciTech Connect

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

    2013-02-15

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

  12. 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

  13. 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

  14. Quantitative determination of elemental sulfur at the arsenopyrite surface after oxidation by ferric iron: mechanistic implications

    Microsoft Academic Search

    Molly M. McGuire; Jillian F. Banfield; Robert J. Hamers

    2001-01-01

    : The elemental sulfur formed at the arsenopyrite surface after oxidation by ferric iron was quantitatively measured by extraction in perchloroethylene and subsequent quantitative analysis by HPLC. Reactions with ferric iron in perchloric acid solutions or in sulfuric acid solutions (both at pH = 1 and 42°C, which approximate extreme acid mine drainage conditions) produced elemental sulfur in quantities greater

  15. Electrochromic Properties of Tungsten Oxide Combined with Metal Nanophases

    Microsoft Academic Search

    Hee-Sang Shim; Kyung-Won Park; Hyo-Jin Ahn; Tae-Yeon Seong

    Electrochromic coatings are of increasing interest for applications in a wide range of fields for energy saving. The possibility of controlling the optical properties of tungsten oxide (WO3) that has good electrochromic properties by applying small specific voltages in a reversible way has been widely investigated.1 However, researches for electrochromic tungsten oxide have been mainly focused on the realization of

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

    EPA Science Inventory

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

  17. Transport properties of polypyrrole-ferric oxide conducting nanocomposites

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, R.; De, A.; Das, S.

    2000-03-01

    Conducting nanocomposite samples were prepared combining colloidal ferric oxide particles with conducting polypyrrole. Three composite samples (prepared keeping colloidal content fixed and varying the content of the conducting polypyrrole) and the pure polymer were used in the present investigation. Temperature dependent dc and ac conductivity and thermoelectric power for the samples have been measured. The dc conductivity results were analyzed by Mott's variable range hopping mechanism. The variation of ac conductivity with the frequency shows very little change in total conductivity up to a critical frequency, followed by a sudden jump with discontinuity and then increases monotonically following a power law. The frequency exponent decreases with temperature as predicted by the correlated barrier hopping theory. Above 50 K the ac component of the conductivity increases almost linearly as predicted by the quantum mechanical tunneling model. It is found that all the features of ac conductivity cannot be reconciled into an existing single theory. The thermoelectric power is positive, low, and varies linearly with temperature, indicating a metallic character and the presence of polarons and/or bipolarons as the cationic charge carriers in the composites. The overall nature of the S(T) curves suggests that in addition to a contribution from hopping a linear metallike component is also active for the thermopower.

  18. 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...

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

    Microsoft Academic Search

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

    2006-01-01

    Bismuth ferric oxide (BFO) thin films were prepared on fluorine doped tin oxide (FTO) coated glass substrates using electrodeposition method from aqueous nitrate bath at room temperature. The various preparative parameters, such as bath composition, current density, deposition time, etc were optimized to get good quality BFO thin films. The structural, surface morphological, optical and dielectrical properties of the films

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

    Microsoft Academic Search

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

    1986-01-01

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

  1. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    SciTech Connect

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

    1986-05-14

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

  4. Role of a ferric ion-reducing system in sulfur oxidation of Thiobacillus ferrooxidans

    SciTech Connect

    Sugio, T.; Domatsu, C.; Munakata, O.; Tano, T.; Imai, K.

    1985-06-01

    The properties of a ferric ion-reducing system which catalyzes the reduction of ferric ion with elemental sulfur was investigated with a pure strain of Thiobacillus ferrooxidans. In anaerobic conditions, washed intact cells of the strain reduced 6 mol of Fe/sup 3 +/ with 1 mol of elemental sulfur to give 6 mol of Fe/sup 2 +/, 1 mol of sulfate, and a small amount of sulfite. In aerobic conditions, the 6 mol Fe/sup 2 +/ produced was immediately reoxidized by the iron oxidase of the cell, with a consumption of 1.5 mol of oxygen. As a result, Fe/sup 2 +/ production was never observed under aerobic conditions. However, in the presence of 5 mM cyanide, which completely inhibits the iron oxidase of the cell, an amount of Fe/sup 2 +/ production comparable to that formed under anaerobic conditions was observed under aerobic conditions. The ferric ion-reducing system had a pH optimum between 2.0 and 3.8, and the activity was completely destroyed by 10 min of incubation at 60/sup 0/C. A short treatment of the strain with 0.5% phenol completely destroyed the ferric ion-reducing system of the cell. However, this treatment did not affect the iron oxidase of the cell. Since a concomitant complete loss of the activity of sulfur oxidation by molecular oxygen was observed in 0.5% phenol-treated cells, it was concluded that the ferric ion-reducing system plays an important role in the sulfur oxidation activity of this strain, and a new sulfur-oxidizing route is proposed for T. ferrooxidans.

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

    NASA Astrophysics Data System (ADS)

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

    1987-06-01

    Rates of aqueous, abiotic pyrite oxidation were measured in oxygen-saturated and anaerobic Fe(III)-saturated solutions with initial pH from 2 to 9. These studies included analyses of sulfite, thiosulfate, polythionates and sulfate and procedures for cleaning oxidation products from pyrite surfaces were evaluated. Pyrite oxidation in oxygen-saturated solutions produced (1) rates that were only slightly dependent on initial pH, (2) linear increases in sulfoxy anions and (3) thiosulfate and polythionates at pH > 3.9. Intermediate sulfoxy anions were observed only at high stirring rates. In anaerobic Fe(III)-saturated solutions, no intermediates were observed except traces of sulfite at pH 9. The faster rate of oxidation in Fe(III)-saturated solutions supports a reaction mechanism in which Fe(III) is the direct oxidant of pyrite in both aerobic and anaerobic systems. The proposal of this mechanism is also supported by theoretical considerations regarding the low probability of a direct reaction between paramagnetic molecular oxygen and diamagnetic pyrite. Results from a study of sphalerite oxidation support the hypothesis that thiosulfate is a key intermediate in sulfate production, regardless of the bonding structure of the sulfide mineral.

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

    Microsoft Academic Search

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

    2008-01-01

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

  7. Induction of oxidative DNA damage by ferric iron in mammalian cells.

    PubMed

    Hartwig, A; Schlepegrell, R

    1995-12-01

    Ferric nitrilotriacetate (Fe-NTA) and ferric citrate (Fe-citrate) were compared with respect to their potential to induce oxidative DNA damage in V79 Chinese hamster cells. DNA base modifications, including 8-hydroxyguanine (7,8-dihydro-8-oxoguanine), were quantified by the frequency of lesions recognized by the bacterial Fpg protein (formamidopyrimidine-DNA glycosylase) in combination with the alkaline unwinding assay. Fe-NTA induced oxidative DNA damage in a time- and dose-dependent manner, yielding significant increases in Fpg-sensitive sites above background after incubation for 24 or 48 h with 500 and 250 microM respectively. At both time points the frequency of DNA base modifications exceeded the number of DNA strand breaks. In contrast, neither DNA strand breaks nor Fpg-sensitive sites were detected after treatment with Fe-citrate at concentrations up to 2 microM for 24 or 48 h; this inactivity of Fe-citrate was independent of the molar ratio of iron to ligand (1:1, 1:2, 1:10 or 1:20). The results indicate that the cellular damage induced by ferric iron depends strongly on the actual complex applied, possibly due to differences in the intracellular distribution, which in turn may affect the availability of iron for redox reactions at or in close proximity to the DNA. PMID:8603477

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1990-04-01

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

  10. Removal of cerium ions from aqueous solution by hydrous ferric oxide--a radiotracer study.

    PubMed

    Dubey, Som Shankar; Rao, Battula Sreenivasa

    2011-02-28

    Radiotracer technique has been used to study the removal behavior of Ce (III) ions from aqueous solutions by synthesized and well characterized hydrous ferric oxide (HFO). Adsorptive concentration (10(-4)-10(-8) mol dm(-3)), pH (ca 4.0-10.0) and temperature (303-333 K) were examined for assessing optimal conditions for removal of these ions. The uptake of Ce (III) ions, which fitted well for Freundlich and D-R isotherms, increased with increase in the temperature and no significant desorption took place in the studied temperature range. The presence of some anions/cations affected the uptake of metal ion markedly. Irradiation of hydrous ferric oxide and tungsten oxide by using a 11.1×10(9) Bq (Ra-Be) neutron source having a neutron flux of 3.9×10(6) cm(-2) s(-1) with associated ?-dose rate of 1.72 Gy/h did not influence the extent of adsorption of Ce (III) significantly. PMID:21168956

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

    PubMed Central

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

    2010-01-01

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

  12. 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 particle size (magnetometry blocking temperature), weaker Fe to particle bond strength (Mössbauer center shift), and no six-line Fh (6L-Fh) admixture (pXRD, magnetometry). Contrary to current belief, we find that 6L-Fh appears to be precipitated directly, under a-HFO conditions, from either Fe(II) or Fe(III), and depending on Fe concentration and pH, whereas the presence of bacteria disables all such 6L-Fh precipitation and produces two-line Fh (2L-Fh)-like biotic coprecipitates. Given the nature of the differences between a-HFO and b-HFO and their synthesis condition dependences, several biotic precipitation mechanisms (template effect, near-cell environment effect, catalyzed nucleation and/or growth effect, and substrate-based coprecipitation) are ruled out. The prevailing present view of a template or heterogeneous nucleation barrier reduction effect, in particular, is shown not to be the cause of the large observed biotic effects on the resulting HFOs. The only proposed mechanism (relevant to Fh) that is consistent with all our observations is coprecipitation with and possible surface poisoning by ancillary bacteriagenic compounds. That bacterial cell wall functional groups are redox active and the characteristics of biotic (i.e., natural) HFOs compared to those of abiotic (i.e., synthetic) HFOs have several possible biogeochemical implications regarding Fe cycling, in the photic zones of water columns in particular.

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

    Microsoft Academic Search

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

    1994-01-01

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

  14. Magnetic ordering of ferric oxide within SiO{sub 2}-based mesoporous materials

    SciTech Connect

    Guo Haiquan [Center for Analysis of Structures and Interfaces (CASI), Chemistry Department, City College of New York, Convent Ave. at 138th St., New York, NY 10031 (United States); Zhang Xiaoming [Center for Analysis of Structures and Interfaces (CASI), Chemistry Department, City College of New York, Convent Ave. at 138th St., New York, NY 10031 (United States); Cui Minhui [Chemistry Department, The College of Staten Island, 2800 Victory Blvd., Staten Island, NY 10314 (United States); Sharma, Renu [Center for Solid State Science, Arizona State University, Tempe, AZ 85287-1704 (United States); Yang Nanloh [Chemistry Department, The College of Staten Island, 2800 Victory Blvd., Staten Island, NY 10314 (United States); Akins, Daniel L. [Center for Analysis of Structures and Interfaces (CASI), Chemistry Department, City College of New York, Convent Ave. at 138th St., New York, NY 10031 (United States)]. E-mail: akins@sci.ccny.cuny.edu

    2005-10-06

    Nanostructural ferric oxide was encapsulated within one-dimensional (1-D) silicate mesoporous molecular materials, resulting in the formation of nanocomposites. The resulting nanocomposites were characterized by UV-vis, IR, TEM, EPR and X-ray diffraction. The occluded Fe{sub 2}O{sub 3} nanostructures were found to evince optical spectra and magnetic properties that were significantly different from that of bulk Fe{sub 2}O{sub 3}. EPR measurements indicate that the various nanocomposites (whose dimensions were controllable by the pore sizes of the silicate materials), when sufficiently loaded with small Fe{sub 2}O{sub 3} nanoparticles, possess nonzero absorptions at zero applied magnetic field, as well as significant microwave absorption capacities as a function of applied magnetic field strength.

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

    PubMed Central

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

    2012-01-01

    Milk provides a well-balanced source of amino acids and other ingredients. One of the functional ingredients in milk is lactoferrin (LF). LF presents a wide variety of bioactivities and functions as a radical scavenger in models using iron-ascorbate complexes and asbestos. Human clinical trials of oral LF administration for the prevention of colon polyps have been successful and demonstrated that dietary compounds exhibit direct interactions. However, antioxidative properties of LF in distant organs require further investigation. To study the antioxidant property of LF, we employed bovine lactoferrin (bLF) using the rat model of ferric nitrilotriacetate (Fe-NTA)-induced renal tubular oxidative injury. We fed rats with bLF (0.05%, w/w) in basal chow for 4 weeks and sacrificed them after Fe-NTA treatment. After intraperitoneal administration of 9.0 mg iron/kg Fe-NTA for 4 and 24 h, bLF pretreatment suppressed elevation of serum creatinine and blood urea nitrogen levels. In addition, we observed protective effects against renal oxidative tubular damage and maintenance of antioxidant enzyme activities in the bLF-pretreated group. We thus demonstrated the antioxidative effect of bLF against Fe-NTA-induced renal oxidative injury. These results suggest that LF intake is useful for the prevention of renal tubular oxidative damage mediated by iron. PMID:22962523

  16. Ion sorption onto hydrous ferric oxides: Effect on major element fluid chemistry at Aspo, Sweden

    SciTech Connect

    Bruton, C.J.; Viani, B.E.

    1996-06-01

    The observed variability of fluid chemistry at the Aespoe Hard Rock Laboratory is not fully described by conservative fluid mixing models. Ion exchange may account for some of the observed discrepancies. It is also possible that variably charged solids such as oxyhydroxides of Fe can serve as sources and sinks of anions and cations through surface complexation. Surface complexation reactions on hydrous ferric oxides involve sorption of both cations and anions. Geochemical modeling of the surface chemistry of hydrous ferric oxides (HFOs) in equilibrium with shallow HBH02 and deep KA0483A waters shows that HFOs can serve as significant, pH-sensitive sources and sinks for cations and anions. Carbonate sorption is favored especially at below-neutral pH. A greater mass of carbonate is sorbed onto HFO surfaces than is contained in the fluid when 10 g goethite, used as a proxy for HFOs, is in contact with 1 kg H{sub 2}O. The masses of sorbent required to significantly impact fluid chemistry through sorption/desorption reactions seem to be reasonable when compared to the occurrences of HFOs at Aespoe. Thus, it is possible that small changes in fluid chemistry can cause significant releases of cations or anions from HFOs into the fluid phase or, alternately, result in uptake of aqueous species onto HFO surfaces. Simulations of the mixing of shallow HBH02 and native KA0483A waters in the presence of a fixed mass of goethite show that surface complexation does not cause the concentrations of Ca, Sr, and SO{sub 4} to deviate from those that are predicted using conservative mixing models. Results for HCO{sub 3} are more difficult to interpret and cannot be addressed adequately at this time.

  17. Occurrence of surface polysulfides during the interaction between ferric (hydr)oxides and aqueous sulfide.

    PubMed

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

    2014-05-01

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

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

    PubMed

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

    2011-03-01

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

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

    Microsoft Academic Search

    Jennifer A Wilkie; Janet G Hering

    1996-01-01

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

  20. Magneto-optic characteristics of ferric oxide quantum-dot-phosphate glass nanocomposite

    NASA Astrophysics Data System (ADS)

    Kumar, Ganapathy; Apte, Sanjay K.; Garaje, Sunil N.; Kulkarni, Milind V.; Mahajan, Satish M.; Kale, B. B.

    2010-03-01

    A phosphate-based glass was embedded with ferric oxide (Fe2O3) quantum dots in an effort to significantly enhance the magneto-optic properties of the glass. The phosphate glass was prepared with a composition 63P2O515.5K2O10ZnO6Na2O5.5BaO and doped with naked nanostructured Fe2O3 varying from 0.25 to 2%. The optical band gap of these glasses was observed to have reduced with an increasing in the concentration of Fe2O3. A maximum increase in Verdet constant of approximately 17 times that in a plain phosphate glass was observed at a wavelength of 632.8 nm, for an Fe2O3 doping concentration of 1% in the host glass. Preliminary measurements show that the resulting composite exhibits good enhancement in the Verdet constant and will have application in magneto-optical devices.

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

    PubMed

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

    2012-06-01

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

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

    Microsoft Academic Search

    Philip L. Verplanck; D. Kirk Nordstrom; Howard E. Taylor; Briant A. Kimball

    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

  3. Synthesis of Waste Cooking Oil Based Biodiesel via Ferric-Manganese Promoted Molybdenum Oxide / Zirconia Nanoparticle Solid acid Catalyst: Influence of Ferric and Manganese Dopants.

    PubMed

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

    2015-05-01

    The utilization of ferric-manganese promoted molybdenum oxide/zirconia (Fe-Mn- MoO3/ZrO2) (FMMZ) solid acid catalyst for production of biodiesel was demonstrated. FMMZ is produced through impregnation reaction followed by calcination at 600°C for 3 h. The characterization of FMMZ had been done using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), temperature programmed desorption of NH3 (TPD-NH3), transmission electron microscopy(TEM) and Brunner-Emmett-Teller (BET) surface area measurement. The effect of waste cooking oil methyl esters (WCOME's) yield on the reactions variables such as reaction temperature, catalyst loading, molar ratio of methanol/oil and reusability were also assessed. The catalyst was used to convert the waste cooking oil into corresponding methyl esters (95.6%±0.15) within 5 h at 200? reaction temperature, 600 rpm stirring speed, 1:25 molar ratio of oil to alcohol and 4% w/w catalyst loading. The reported catalyst was successfully recycled in six connective experiments without loss in activity. Moreover, the fuel properties of WCOME's were also reported using ASTM D 6751 methods. PMID:25843280

  4. 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.

  5. 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

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

    PubMed

    Majzlan, Juraj

    2011-06-01

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

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

    Microsoft Academic Search

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

    2003-01-01

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

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

    PubMed Central

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

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

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

    E-print Network

    Sparks, Donald L.

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

  11. Removal and recovery of phosphate from municipal wastewaters using a polymeric anion exchanger bound with hydrated ferric oxide nanoparticles.

    PubMed

    Martin, B D; Parsons, S A; Jefferson, B

    2009-01-01

    A new type of ion exchange media which is highly selective for phosphate, and can be easily regenerated has been investigated. The media consists of hydrated ferric oxide nanoparticles dispersed within the pore structures of polymeric anion exchanger beads. The media combines the durability and mechanical strength of ion exchange resins with the high sorption capacity of ferric oxide for phosphate. The media was trialled in fixed bed mini column experiments with real final effluent from two UK sewage treatment works, one with treatment based on chemical precipitation with iron chloride salts into an activated sludge process (population >250,000), and one based on trickling filter treatment with no specific phosphorus removal process (population <10,000). Results show that the media has high capacity for removing phosphate, reaching capacity at 4000 and 1300 bed volumes for the chemical precipitation and trickling filter works respectively, with performance greatly exceeding that of a standard anion exchanger, Amberlite IRA-410. Also trialled was the media's ability to elute the phosphorus after breakthrough, with the aim of recovering and processing it into a useful product. A one step regenerative process using a single solution containing 4% NaOH and 2% NaCl was passed through the resin bed and the phosphorus concentration of each bed volume leaving the column analysed. 80% of the phosphorus was eluted in the first bed volume. Subsequent tests investigated the performance of the media after successive partial regenerations of one bed volume of the NaOH/NaCl solution. There was no loss of performance observed after ten regeneration cycles, and levels of eluted phosphate were consistently high. These results suggest that the media has high potential for the removal and recovery of phosphate from wastewater streams. Additionally, the small volume of regenerant required translates to a very small operational footprint. PMID:19923770

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

    PubMed Central

    Nganai, Shadrack; Lomnicki, Slawo; Dellinger, Barry

    2012-01-01

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

  13. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

  14. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

  15. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

  16. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

  17. 21 CFR 73.1298 - Ferric ammonium ferrocyanide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...The color additive ferric ammonium ferrocyanide is the blue pigment obtained by oxidizing under acidic conditions with sodium...The oxidized product is filtered, washed, and dried. The pigment consists principally of ferric ammonium ferrocyanide...

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

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  20. 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

  1. Clinical efficacy of two forms of intravenous iron--saccharated ferric oxide and cideferron--for iron deficiency anemia.

    PubMed

    Araki, T; Takaai, M; Miyazaki, A; Ohshima, S; Shibamiya, T; Nakamura, T; Yamamoto, K

    2012-12-01

    Over 90% of iron deficiency anemia cases are due to iron deficiency associated with depletion of stored iron or inadequate intake. Parenteral iron supplementation is an important part of the management of anemia, and some kinds of intravenous iron are used. However, few studies have evaluated the clinical efficacy of these drugs. The purpose of this study was to compare and assess the clinical efficacy of two types of intravenous iron injection, saccharated ferric oxide (SFO) and cideferron (CF). Medical records were obtained for 91 unrelated Japanese anemia patients treated with SFO (n = 37) or CF (n = 54) from May 2005 to May 2010 at Gunma University Hospital. Patients treated with blood transfusion, erythropoietin or oral iron were excluded. Hemoglobin (Hb) values measured on day 0, 7 and 14 were used to assess the efficacy of intravenous irons. A significant increase was observed in the mean Hb value by day 14 of administration in both the CF group and SFO group, and the mean Hb increase due to administration of CF for 7 days was comparable to that of SFO for 14 days. Age and sex did not affect improvement of Hb value. CF is fast acting and highly effective compared with SFO for the treatment of iron deficiency anemia. The use of CF may shorten a therapeutic period for iron deficiency anemia, and CF may be feasible for reducing the hospitalization period. PMID:23346769

  2. Effect of anesthetic agent on lung tumor induction in hamsters given benzo[a]pyrene-ferric oxide.

    PubMed

    Henry, M C; Port, C D

    1978-11-01

    The effects of an anesthetic agent on lung tumor induction in noninbred Syrian golden hamsters were investigated after intratracheal instillation of a benzo[a]pyrene-ferric oxide mixture. Inhalation anesthesia with ether or methoxyflurane was accomplished with a closed recirculatory system that allowed a short induction time for anesthesia and a good control over the concentration of anesthetic. This type of anesthetic induction was compared with systemic induction by Brevital. Survival rates during the 10 weekly instillations were least for the Brevital-treated group and greatest for the methoxyflurane-treated group. Body weight gain was lower in both the ether- and Brevital-treated groups as compared to the group anesthetized with methoxyflurane. The animals anesthetized with Brevital had the shortest tumor latency, but the tumor incidence during the weeks of the experiment was similar in the group treated with this agent and the group treated with ether. Exposure to methoxyflurane and the carcinogen produced a slow onset of deaths from tumors and lower tumor incidence. These results are discussed in relation to retention of the dose of carcinogen in the respiratory tract and effect of inhalation anesthia on consequent lung tissue pathology. PMID:280710

  3. Differential Scanning Calorimetric Study of HTPB based Composite Propellants in Presence of Nano Ferric Oxide

    Microsoft Academic Search

    Satyawati S. Joshi

    2006-01-01

    A comparative study of the thermal decomposition of ammonium perchlorate (AP)\\/hydroxy terminated polybutadiene (HTPB) based composite propellants has been carried out in presence and absence of nano iron oxide at different heating rates in a dynamic nitrogen atmosphere using differential scanning calorimetry. The pronounced effect was a lowering of the high temperature decomposition by 49?°C. A higher heat release up

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

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

  6. 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.

  7. Mechanical properties of nanophase materials

    SciTech Connect

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

    1993-11-01

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

  8. Thermodynamic and Properties of Nanophases

    SciTech Connect

    Wunderlich, Bernhard {nmn} [ORNL

    2009-01-01

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

  9. 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.

  10. Nuclear fuel elements made from nanophase materials

    DOEpatents

    Heubeck, Norman B. (Schenectady, NY)

    1998-01-01

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

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

    SciTech Connect

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

    2013-11-29

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

  12. Protective effect of Rumex patientia (English Spinach) roots on ferric nitrilotriacetate (Fe-NTA) induced hepatic oxidative stress and tumor promotion response.

    PubMed

    Lone, Irshad A; Kaur, Gurpreet; Athar, Mohammad; Alam, M Sarwar

    2007-10-01

    In this communication, we document the antioxidant potential of ethanolic extract of Rumex patientia L. (Polygonaceae) roots and its chemopreventive effects against Fe-NTA mediated hepatic oxidative stress, hepatotoxicity and tumor promotion response. The extract exhibited high polyphenolic content, potent reducing power and significantly scavenged free radicals (including several reactive oxygen species (ROS) and reactive nitrogen species (RNS)). The extract also significantly and dose dependently protected against oxidative damage to lipids and DNA. These results indicated R. patientia root extract to exert a potent antioxidant activity in vitro. The efficacy of extract was also evaluated in vivo and it was found to exert a potent protective affect in acute oxidative tissue injury animal model: ferric nitrilotriacetate (Fe-NTA) induced hepatotoxicity in mice. Administration of Fe-NTA (9 mg/kg body weight, i.p.) to mice led to a significant oxidative stress and allied damage in liver tissues and induced hyperproliferation. A significant depletion was observed in GSH content and enzymes implicated in its metabolism. Attenuation also occurred in activities of other hepatic antioxidant enzymes including SOD, CAT, and GPX. Fe-NTA also incited hyperproliferation response elevating ornithine decarboxylase activity and [(3)H]-thymidine incorporation into DNA. Histopathological investigations and liver function tests (LFT) indicated Fe-NTA to cause extensive hepatic damage. However, prophylactic treatment with R. patientia root extract at a dose regimen of 100-200mg/kg body weight for a week not only restored hepatic antioxidant armory close to normal, but also significantly precluded oxidative damage restoring normal hepatic architecture and levels of hepatic damage markers. The data obtained in the present study illustrates R. patientia roots to possess potent antioxidant and free radical scavenging activities and thwart oxidative damage and hyperproliferation in hepatic tissues. PMID:17517459

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    PubMed Central

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

    1999-01-01

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

  15. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Drugs § 73.1299 Ferric ferrocyanide. (a) Identity. (1) The color additive ferric ferrocyanide is a ferric hexacyanoferrate pigment...contain small amounts of ferric sodium ferrocyanide and ferric potassium...

  16. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Drugs § 73.1299 Ferric ferrocyanide. (a) Identity. (1) The color additive ferric ferrocyanide is a ferric hexacyanoferrate pigment...contain small amounts of ferric sodium ferrocyanide and ferric potassium...

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

    Microsoft Academic Search

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

    2001-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    PubMed Central

    Caccavo, Frank

    1999-01-01

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

  20. Mineralogical confirmation of a near-P:Fe = 1:2 limiting stoichiometric ratio in colloidal P-bearing ferrihydrite-like hydrous ferric oxide

    NASA Astrophysics Data System (ADS)

    Thibault, Pierre-Jean; Rancourt, Denis G.; Evans, R. James; Dutrizac, John E.

    2009-01-01

    We present a chemical and mineralogical explanation, derived from powder X-ray diffraction and Mössbauer spectroscopy measurements of synthetic samples, of the P:Fe = 1:2 limiting ratio of P incorporation (as PO 4) that was previously observed in natural aquatic oxic iron precipitates. The 57Fe Mössbauer hyperfine parameters are interpreted with the help of state-of-the-art ab initio electronic structure calculations. We find that there is a strong tendency for solid solution P-Fe mixing in the P-bearing hydrous ferric oxide (P-HFO) aqueous coprecipitate system, interpreted as occurring between the P-free (ferrihydrite) end-member and an inferred P:Fe = 1:2 end-member beyond which P is not incorporated in the structure of the P-HFO solid. Up to and somewhat beyond the limiting end-member P:Fe ratio, all available P is scavenged by the coprecipitation reaction, suggesting strong P-Fe complexation in the precipitation-precursor dissolved species. The P-HFO solids are more stable (i.e., have stronger chemical bonds) than the P-free ferrihydrite end-member. We show that in coprecipitation the P specifically incorporates within the nanoparticle structure rather than complexing to the nanoparticle surface. Our results are relevant to the question of the mechanisms of coupling between the Fe and P cycles in natural aqueous environments and highlight a strong affinity between Fe and P in aqueous environments.

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

    SciTech Connect

    Caccavo, F. Jr.

    1999-11-01

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

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

    Microsoft Academic Search

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

    2010-01-01

    Iron is essential in numerous cellular functions. Intracellular iron homeostasis must be maintained for cell survival and\\u000a 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.\\u000a Herein, we isolated spontaneous Xcc fur mutants that

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

    SciTech Connect

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

    2012-10-15

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

  4. 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

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

    SciTech Connect

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

    2009-01-01

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

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

    PubMed

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

    2009-07-01

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

  7. 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.

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

    PubMed

    Azam, Hossain M; Finneran, Kevin T

    2013-01-01

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

  9. 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

  10. Center for Nanophase Materials Sciences Strategic Plan

    E-print Network

    Center for Nanophase Materials Sciences Strategic Plan 2015­2019 October 2014 #12;#12;iii CONTENTS ................................................................... 5 3. Integration into ORNL Missions: Neutron Sciences, Materials by Design, Imaging ................ 6 The Link to Neutron Sciences

  11. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...1299 Ferric ferrocyanide. (a) Identity. (1) The color additive ferric ferrocyanide is a ferric hexacyanoferrate pigment characterized by the structual formula Fe4 [Fe(CN)6 ]3 ·XH2 O, which may contain small amounts of ferric...

  12. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...1299 Ferric ferrocyanide. (a) Identity. (1) The color additive ferric ferrocyanide is a ferric hexacyanoferrate pigment characterized by the structual formula Fe4 [Fe(CN)6 ]3 ·XH2 O, which may contain small amounts of ferric...

  13. 21 CFR 73.1299 - Ferric ferrocyanide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...1299 Ferric ferrocyanide. (a) Identity. (1) The color additive ferric ferrocyanide is a ferric hexacyanoferrate pigment characterized by the structual formula Fe4 [Fe(CN)6 ]3 ·XH2 O, which may contain small amounts of ferric...

  14. Protein and Cell Interactions with Nanophase Biomaterials

    Microsoft Academic Search

    Courtney M. Creecy; David A. Puleo; Rena Bizios

    This chapter provides an overview of current knowledge regarding protein and cell interactions with nanophase materials, that\\u000a is, materials with feature sizes of less than 100 nm in (at least) one dimension. Nanophase biomaterials promote select and\\u000a specific interactions with biomolecules and, subsequently, support enhanced mammalian cell functions pertinent to new tissue\\u000a formation. Although some advances have been made in elucidating

  15. Structural Transformation in Nanophase Titanium Dioxide

    Microsoft Academic Search

    Muying Wu; Weifeng Zhang; Zuliang Du; Yabin Huang

    1999-01-01

    Nanophase TiO2 was prepared by a stearic acid sol-gel technique. X-ray measurements showed that the as-prepared sample is anatase TiO2 phase with an average grain size of 10.4 nm. Raman spectroscopy was used to investigate the structural transformation from anatase-to-rutile in the nanophase TiO2 annealed at a series of temperatures from 450 to 650°C. The results showed that the transformation

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

    Microsoft Academic Search

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

    2004-01-01

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

  17. Enhancement of chalcopyrite leaching by ferrous ions in acidic ferric sulfate solutions

    Microsoft Academic Search

    Naoki Hiroyoshi; Hajime Miki; Tsuyoshi Hirajima; Masami Tsunekawa

    2001-01-01

    The effects of ferrous ions on chalcopyrite oxidation with ferric ions in 0.1 mol dm?3 sulfuric acid solutions were investigated by leaching experiments at 303 K in nitrogen. With high cupric ion concentrations, the chalcopyrite oxidation was enhanced by high concentrations of ferrous ions and copper extraction was mainly controlled by the concentration ratio of ferrous to ferric ions or

  18. Nanophase change for data storage applications.

    PubMed

    Shi, L P; Chong, T C

    2007-01-01

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

  19. Altered responses of chondrocytes to nanophase PLGA\\/nanophase titania composites

    Microsoft Academic Search

    Jennifer K Savaiano; Thomas J Webster

    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

  20. Ferric ions doped 5A molecular sieves for the oxidation of HCHO with low concentration in the air at moderate temperatures

    Microsoft Academic Search

    Yang Xuzhuang; Shen Yuenian; Yuan zhangfu; Zhu Huaiyong

    2005-01-01

    Zeolite 5A molecular sieve was doped with iron ions Fe3+ by ion exchange and the catalytic activity of the obtained solids for the formaldehyde oxidation was investigated. The catalysts are able to oxidize formaldehyde of a very low concentration at moderate temperatures. The light-off temperatures were about 70–100°C and the temperatures for the complete oxidation were about 160–190°C. The oxidation

  1. A fundamental study of ferric oxalate for dissolving gold in thiosulfate solutions

    Microsoft Academic Search

    I. Chandra; M. I. Jeffrey

    2005-01-01

    A fundamental study was undertaken of the dissolution of gold using a novel thiosulfate leaching system that utilises ferric oxalate as the oxidant in place of the traditional cupric ammine. The key advantage of the ferric oxalate system is that the thiosulfate consumption is negligible compared to the cupric ammine system. The gold leaching kinetics were measured using the rotating

  2. Molecular Structure of Ferric chloride

    NSDL National Science Digital Library

    2002-08-27

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

  3. 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...

  4. 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...

  5. 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). PMID:23013221

  6. Protective effect of Rumex patientia (English Spinach) roots on ferric nitrilotriacetate (Fe-NTA) induced hepatic oxidative stress and tumor promotion response

    Microsoft Academic Search

    Irshad A. Lone; Gurpreet Kaur; Mohammad Athar; M. Sarwar Alam

    2007-01-01

    In this communication, we document the antioxidant potential of ethanolic extract of Rumex patientia L. (Polygonaceae) roots and its chemopreventive effects against Fe-NTA mediated hepatic oxidative stress, hepatotoxicity and tumor promotion response. The extract exhibited high polyphenolic content, potent reducing power and significantly scavenged free radicals (including several reactive oxygen species (ROS) and reactive nitrogen species (RNS)). The extract also

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  8. Low spin ferric hemoglobin complexes

    Microsoft Academic Search

    Gilda Harris

    1966-01-01

    A caloulation has been made of the energy eigenfunotions and eigenvalues of low spin ferric ion in complexes with a strong cubic crystal field including the effects of tetragonal and rhombic distortions and of spin-orbit coupling among the ground state components and with excited states. Using the resultant, spin-orbit coupled eigenfunotions as a basis set, the magnetic susceptibility, the components

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed Central

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

    2008-01-01

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

  11. Impact performance of nanophased foam core sandwich composites

    Microsoft Academic Search

    M. V. Hosur; A. A. Mohammed; S. Zainuddin; S. Jeelani

    2008-01-01

    In this study, sandwich panels were fabricated with neat and nanophased foam core and three-layered plain weave carbon fabric\\/Sc-15 epoxy composite face sheets. Neat and nanophased foam cores with Nanocor® I-28E nanoclay at a loading of 0.5% and 1% by weight were prepared. Sandwich panels were then fabricated using co-injection resin transfer molding process. Samples of size 100mm×100mm were then

  12. Adverse Reactions of Ferric Carboxymaltose

    PubMed Central

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

    2014-01-01

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

  13. 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 indicates the complexity of biological responses to nanoparticles. We believe that the exposure methodology and aerosol technology employed in our research will provide an effective means to systematically investigate cellular responses to nanoparticles, structured or unstructured, in ongoing research projects. Different cell lines, chemicals, and particle morphology can also be investigated using such a methodology. PMID:15509017

  14. Ferric oxyhydroxide microparticles in water

    PubMed Central

    Whittemore, Donald O.; Langmuir, Donald

    1974-01-01

    Mineralogy and specific surface area are major controls on the stabilities of ferric oxyhydroxide microparticles in natural waters. The thermodynamic stabilities of ferric oxyhydroxides, as described by the activity product in solution pK = ?log [Fe3+] [OH?]3 range from pK = 37.1 for freshly precipitated amorphous oxyhydroxide to pK = 44.2 for well crystallized goethite. The sizes of suspended oxyhydroxide particles in natural waters range from less than 0.01 ?m to greater than 5 ?m. Oxyhydroxides precipitated in the laboratory from solutions simulating high-iron natural waters are needlelike or lathlike in shape and have mean thicknesses as small as 60 Å. Large specific surface areas resulting from the small sizes of ferric oxyhydroxide particles cause increased solubilities and thus decreased pK values. Specific surface areas of 40–170 m2/g determined for laboratory precipitates gave computed decreases in pK of 0.4 to 1.6 units. ImagesFIGURE 1.FIGURE 3.FIGURE 3.FIGURE 4. PMID:4470932

  15. 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.

  16. 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.

  17. 21 CFR 582.5306 - Ferric sodium pyrophosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 false Ferric sodium pyrophosphate. 582.5306 ...Supplements 1 § 582.5306 Ferric sodium pyrophosphate. (a) Product. Ferric sodium pyrophosphate. (b) Conditions of use. This substance is...

  18. 21 CFR 582.5306 - Ferric sodium pyrophosphate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 false Ferric sodium pyrophosphate. 582.5306 ...Supplements 1 § 582.5306 Ferric sodium pyrophosphate. (a) Product. Ferric sodium pyrophosphate. (b) Conditions of use. This substance is...

  19. 21 CFR 582.5306 - Ferric sodium pyrophosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 false Ferric sodium pyrophosphate. 582.5306 ...Supplements 1 § 582.5306 Ferric sodium pyrophosphate. (a) Product. Ferric sodium pyrophosphate. (b) Conditions of use. This substance is...

  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. Structure and properties of nanophase TiO/sub 2/

    SciTech Connect

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

    1987-07-01

    Ultrafine-grained, nanophase samples of TiO/sub 2/ (rutile) were synthesized by the gas-condensation method and subsequent in-situ compaction, and then studied by transmission electron microscopy, Vickers hardness measurements, and positron annihilation spectroscopy as a function of sintering temperature. The nanophase compacts densified rapidly above 500/sup 0/C, with only a small increase in grain size. The hardness values obtained by this method are comparable to or greater than coarser-grained compacts, but at temperatures 400 to 600/sup 0/C lower than conventional sintering temperatures and without the need for sintering aids. 11 refs., 3 figs.

  2. Imaging and Nanoscale Characterization Group Center for Nanophase Materials Sciences

    E-print Network

    Pennycook, Steve

    An-Ping Li R&D Staff Imaging and Nanoscale Characterization Group Center for Nanophase Materials-59 Focus Topic Conference on Electron Transport at the Nanoscale. 2011-2012 Organizing Committee and Session Chair, AVS-58 Focus Topic Conference on Electron Transport in Low-Dimensional Materials. 2010

  3. Postdoctoral Research Associate Center for Nanophase Materials Sciences

    E-print Network

    Pennycook, Steve

    , the materials design process can be significantly expedited and simplified. Machine learning algorithms canYu Xie Postdoctoral Research Associate Center for Nanophase Materials Sciences Oak Ridge National, design, and control complex behavior emerges at the nanoscale that can improve the performance

  4. The dissolution of chalcopyrite in ferric sulfate and ferric chloride media

    Microsoft Academic Search

    J. E. Dutrizac

    1981-01-01

    The literature on the ferric ion leaching of chalcopyrite has been surveyed to identify those leaching parameters which are\\u000a well established and to outline areas requiring additional study. New experimental work was undertaken to resolve points still\\u000a in dispute. It seems well established that chalcopyrite dissolution in either ferric chloride or ferric sulfate media is independent\\u000a of stirring speeds above

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

    Microsoft Academic Search

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

    2004-01-01

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

  6. AN IMPROVED SPECTROSCOPIC MODEL FOR SPACE WEATHERING THROUGH THE FORMATION OF A VAPOR DEPOSITION LAYER CONTAINING NANOPHASE REDUCED IRON

    E-print Network

    Hiroi, Takahiro

    LAYER CONTAINING NANOPHASE REDUCED IRON PARTICLES. T. Nimura1, 2, 3 , T. Hiroi1 , and C. M. Pieters1 , 1 coating layer of dw in thickness, containing nanophase metallic iron (npFe0 ) particles of about 10 nm of nanophase reduced iron (npFe0 ) parti- cles in a semi-transparent matrix [2]. In this paper, an improved

  7. 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 ferrihydrite growth in the precipitates with molar Fe/As ratios of 1-4, whereas increased reaction gradually transforms two-line ferrihydrite to six-line ferrihydrite at Fe/As ratios of 5 and greater.

  8. 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.

  9. New nanophase iron-based catalysts for hydrocracking applications

    SciTech Connect

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

    1994-11-01

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

  10. 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.

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

    PubMed Central

    Kosman, Daniel J.

    2012-01-01

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

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

    E-print Network

    Prozorov, Ruslan

    . for the first time reported the synthesis of nanophasic, amorphous, elemental iron by a sonochemical method involving the irradiation of iron pentacarbonyl by a high-intensity ultrasound radiation.7 This method cavitation have been exploited in this method to break the metal carbonyl bonds to form nanophasic amorphous

  13. A method for preparing ferric activated carbon composites adsorbents to remove arsenic from drinking water

    Microsoft Academic Search

    Qiao Li Zhang; Y. C. Lin; X. Chen; Nai Yun Gao

    2007-01-01

    Iron oxide\\/activated carbon (FeO\\/AC) composite adsorbent material, which was used to modify the coal-based activated carbon (AC) 12×40, was prepared by the special ferric oxide microcrystal in this study. This composite can be used as the adsorbent to remove arsenic from drinking water, and Langmuir isotherm adsorption equation well describes the experimental adsorption isotherms. Then, the arsenic desorption can subsequently

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

    Microsoft Academic Search

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

    1997-01-01

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

  15. Characterization of a soluble ferric reductase from Neisseria gonorrhoeae

    Microsoft Academic Search

    Alain E. Le Faou; Stephen A. Morse

    1991-01-01

    Summary An NADH-dependent ferric reductase was identified in extracts ofNeisseria gonorrhoeae. Enzyme activity was measured in an assay using ferrozine as the ferrous iron acceptor. Ferric reductase activity was enhanced by Mg2+ and flavine nucleotides. The enzyme reduced both citrate- and diphosphate-bound ferric iron as well as ferric hydroxide (Imferon). However, no activity was observed with either 30%-iron-saturated transferrin or

  16. Anion-independent iron coordination by the Campylobacter jejuni ferric binding protein.

    PubMed

    Tom-Yew, Stacey A L; Cui, Diana T; Bekker, Elena G; Murphy, Michael E P

    2005-03-11

    Campylobacter jejuni, the leading cause of human gastroenteritis, expresses a ferric binding protein (cFbpA) that in many pathogenic bacteria functions to acquire iron as part of their virulence repertoire. Recombinant cFbpA is isolated with ferric iron bound from Escherichia coli. The crystal structure of cFbpA reveals unprecedented iron coordination by only five protein ligands. The histidine and one tyrosine are derived from the N-terminal domain, whereas the three remaining tyrosine ligands are from the C-terminal domain. Surprisingly, a synergistic anion present in all other characterized ferric transport proteins is not observed in the cFbpA iron-binding site, suggesting a novel role for this protein in iron uptake. Furthermore, cFbpA is shown to bind iron with high affinity similar to Neisserial FbpA and exhibits an unusual preference for ferrous iron (oxidized subsequently to the ferric form) or ferric iron chelated by oxalate. Sequence and structure analyses reveal that cFbpA is a member of a new class of ferric binding proteins that includes homologs from invasive and intracellular bacteria as well as cyanobacteria. Overall, six classes are defined based on clustering within the tree and by their putative iron coordination. The absence of a synergistic anion in the iron coordination sphere of cFbpA also suggests an alternative model of evolution for FbpA homologs involving an early iron-binding ancestor instead of a requirement for a preexisting anion-binding ancestor. PMID:15613474

  17. Understanding Arsenate Reaction Kinetics with Ferric Hydroxides

    PubMed Central

    Farrell, James; Chaudhary, Binod K.

    2015-01-01

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

  18. The leaching of chalcopyrite with ferric sulfate

    Microsoft Academic Search

    Tetsuji Hirato; Hiroshi Majima; Yasuhiro Awakura

    1987-01-01

    The leaching kinetics of natural chalcopyrite crystals with ferric sulfate was studied. The morphology of the leached chalcopyrite\\u000a and the electrochemical properties of chalcopyrite electrodes also were investigated. The leaching of chalcopyrite showed\\u000a parabolic-like kinetics initially and then showed linear kinetics. In the initial stage, a dense sulfur layer formed on the\\u000a chalcopyrite surface. The growth of the layer caused

  19. Nickel hydroxide and other nanophase cathode materials for rechargeable batteries

    NASA Astrophysics Data System (ADS)

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

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

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

    PubMed Central

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

    2012-01-01

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

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

    Microsoft Academic Search

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

    Efforts to explore possible relationships between nitric oxide (NO) and antioxidant enzymes in an Escherichia coli model have uncovered a possible interaction between sodium nitroprusside (SNP), a potent, NO-donating drug, and the ferric uptake regulator (Fur), an iron(II) – dependent regulator of antioxidant and iron acquisition proteins present in Gram-negative bacteria. The enzymatic profiles of superoxide dismutase and hydroperoxidase during

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

    Microsoft Academic Search

    Hergen Eilers

    2007-01-01

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

  3. Pilot-scale tests of poly ferric sulfate synthesized using SO 2 at Des Moines Water Works

    Microsoft Academic Search

    Aron D. Butler; Maohong Fan; Robert C. Brown; Shihwu Sung; Barbara Duff

    2005-01-01

    Poly ferric sulfate (PFS) was synthesized by absorbing a dilute sulfur dioxide gas stream into a bench-scale reactor containing a stirred solution of ferrous sulfate, with sodium chlorate added as an oxidant. The reaction product was a solution containing approximately 50wt.% PFS, a highly effective coagulant used in water treatment. The reaction took place near atmospheric pressure and at temperatures

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

    PubMed

    Keating, Gillian M

    2015-01-01

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

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

    Microsoft Academic Search

    MICHELLE M. TIMMERMAN; JON P. WOODS

    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 glutathi- one-dependent ferric reductase enzyme, extracellular nonproteinaceous ferric reductant(s), and cell surface ferric reducing agent(s). We examined the relationship between these mechanisms

  6. 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.

  7. Determination of ferrous and ferric iron in aqueous biological solutions.

    PubMed

    Pepper, S E; Borkowski, M; Richmann, M K; Reed, D T

    2010-03-24

    A solvent extraction method was employed to determine ferrous and ferric iron in aqueous samples. Fe(3+) is selectively extracted into the organic phase (n-heptane) using HDEHP (bis(2-ethylhexyl) hydrogen phosphate) and is then stripped using a strong acid. After separation, both oxidation states and the total iron content were determined directly by ICP-MS analysis. This extraction method was refined to allow determination of both iron oxidation states in the presence of strong complexing ligands, such as citrate, NTA and EDTA. The accuracy of the method was verified by crosschecking using a refinement of the ferrozine assay. Presented results demonstrate the ability of the extraction method to work in a microbiological system in the presence of strong chelating agents following the bioreduction of Fe(3+) by the Shewanella alga BrY. Based on the results we report, a robust approach was defined to separately analyze Fe(3+) and Fe(2+) under a wide range of potential scenarios in subsurface environments where radionuclide/metal contamination may coexist with strongly complexing organic contaminants. PMID:20206007

  8. 46 CFR 151.50-75 - Ferric chloride solution.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Ferric chloride solution. 151.50-75 Section 151.50-75...Requirements § 151.50-75 Ferric chloride solution. A containment system (cargo tank...system, and gauging system) carrying this solution must be lined with rubber,...

  9. 46 CFR 151.50-75 - Ferric chloride solution.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Ferric chloride solution. 151.50-75 Section 151.50-75...Requirements § 151.50-75 Ferric chloride solution. A containment system (cargo tank...system, and gauging system) carrying this solution must be lined with rubber,...

  10. 21 CFR 73.1025 - Ferric ammonium citrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...Ferric ammonium citrate may be safely used in combination with pyrogallol (as listed in § 73.1375), for coloring plain and chromic...1980). (2) The level of the ferric ammonium citrate-pyrogallol complex shall not exceed 3 percent of the total weight...

  11. 21 CFR 73.1025 - Ferric ammonium citrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...Ferric ammonium citrate may be safely used in combination with pyrogallol (as listed in § 73.1375), for coloring plain and chromic...1980). (2) The level of the ferric ammonium citrate-pyrogallol complex shall not exceed 3 percent of the total weight...

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

    SciTech Connect

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

    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.

  13. Anacardic acids and ferric ion chelation.

    PubMed

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

    2007-01-01

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

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

    E-print Network

    Schlabach, Michael Ray

    1974-01-01

    found to be nonsyn- ergistic. Dihydroxyacetone and glyceraldehyde were also ineffective in promoting ternary complex formation. Dicarboxylic acids were found 3+ to form stable Fe -transferrin ? anion complexes which were only slowly displaced...-TRANSFERRIN BINARY COMPLEXES EXPERIMENTAL PROCEDURES RESULTS AND INTERPRETATION FERRIC-TRANSFERRIN-ANION TERNARY COMPLEXES ~ ~ ~ ~ o ~ ~ EXPERIMENTAL PROCEDURES RESULTS AND INTERPRETATION DISCUSSION 21 21 25 47 VITA 56 viii LIST OF TABLES Table Page A...

  15. The near-infra-red spectra of ferric acetylacetonate 

    E-print Network

    Owen, James Travis

    1965-01-01

    15 23 Bibliography. Appendix 1. Appendix 2. 26 27 LIST OF FIGURES Figure 6a 6b 10 Oh d Orbital Energies. D d Orbital Energies 3 Energy-Level Matrix Ferric Ion Transitions . Spectrum of Filter DO-2-600 Electric Vector Parallel... in ferric acetylacetonate, Hence, the absorption spectrum cf crystal samples was obtained. Barnum (2) has studied these transitions with the sample dissolved in carbcn tetrachloride, This solvent's "heavy atom" imposed spin-orbit coupling on the iron...

  16. Ferric ion leaching of chalcopyrites from different localities

    Microsoft Academic Search

    J. E. Dutrizac

    1982-01-01

    Carefully sized and characterized chalcopyrite concentrates were produced from eleven different geographical localities, and\\u000a were subsequently leached in both ferric chloride-hydrochloric acid and ferric sulfate-sulfuric acid media. When the leaching\\u000a rates were corrected for the amount of CuFeS2 in the particular sample, similar leaching rates (±50 pct) were observed for all eleven chalcopyrites under all experimental\\u000a conditions. Furthermore, all the

  17. The kinetics of dissolution of chalcopyrite in ferric ion media

    Microsoft Academic Search

    J. E. Dutrizac

    1978-01-01

    The kinetics of dissolution of chalcopyrite (CuFeS2) in ferric chloride-hydrochloric acid and in ferric sulfate-sulfuric acid solutions have been investigated using the rotating\\u000a disk technique. Over the temperature range 50 to 100‡C, linear kinetics were observed in the chloride media while nonlinear\\u000a kinetics were noted in the sulfate system. The apparent activation energy in the chloride system was about 11

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

    Microsoft Academic Search

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

    2002-01-01

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

  19. 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 implications of these findings in relation to a stereospecific high-affinity binding followed by a nonstereospecific postreceptor processing is discussed. PMID:2185228

  20. Evidence of the direct involvement of the substrate TCP radical in functional switching from oxyferrous O2 carrier to ferric peroxidase in the dual-function hemoglobin/dehaloperoxidase from Amphitrite ornata.

    PubMed

    Sun, Shengfang; Sono, Masanori; Du, Jing; Dawson, John H

    2014-08-01

    The coelomic O2-binding hemoglobin dehaloperoxidase (DHP) from the sea worm Amphitrite ornata is a dual-function heme protein that also possesses a peroxidase activity. Two different starting oxidation states are required for reversible O2 binding (ferrous) and peroxidase (ferric) activity, bringing into question how DHP manages the two functions. In our previous study, the copresence of substrate 2,4,6-trichlorophenol (TCP) and H2O2 was found to be essential for the conversion of oxy-DHP to enzymatically active ferric DHP. On the basis of that study, a functional switching mechanism involving substrate radicals (TCP(•)) was proposed. To further support this mechanism, herein we report details of our investigations into the H2O2-mediated conversion of oxy-DHP to the ferric or ferryl ([TCP] < [H2O2]) state triggered by both biologically relevant [TCP and 4-bromophenol (4-BP)] and nonrelevant (ferrocyanide) compounds. At <50 ?M H2O2, all of these conversion reactions are completely inhibited by ferric heme ligands (KCN and imidazole), indicating the involvement of ferric DHP. Furthermore, the spin-trapping reagent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) effectively inhibits the TCP/4-BP (but not ferrocyanide)-triggered conversion of oxy-DHP to ferric DHP. These results and O2 concentration-dependent conversion rates observed in this study demonstrate that substrate TCP triggers the conversion of oxy-DHP to a peroxidase by TCP(•) oxidation of the deoxyferrous state. TCP(•) is progressively generated, by increasingly produced amounts of ferric DHP, upon H2O2 oxidation of TCP catalyzed initially by trace amounts of ferric enzyme present in the oxy-DHP sample. The data presented herein further address the mechanism of how the halophenolic substrate triggers the conversion of hemoglobin DHP into a peroxidase. PMID:24972312

  1. Simulation of nanophase iron production in lunar space weathering

    NASA Astrophysics Data System (ADS)

    Tang, Hong; Wang, Shijie; Li, Xiongyao

    2012-01-01

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

  2. 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.

  3. 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 compared to the nanocrystalline HA coatings. These results suggested that the availability of integrin binding domains in fibronectin did not correlate to enhanced mineralization by osteoblasts on nanocrystalline HA coatings. Lastly, undoped nanocrystalline HA coatings were studied using a well-established rat calvaria in vivo. Histological analysis showed that nanocrystalline HA coated on tantalum scaffolds increased bone and fibrous tissue infiltration into the scaffolds while uncoated and UltraCaP HA coated scaffolds did not after as early as 6 weeks. In summary, these results encourage further studies on nanocrystalline IonTiteTM HA coatings on various metals for orthopedic and dental applications.

  4. 62 FR 56102 - Ferric Phosphate; Establishment of an Exemption from the Requirement of a Tolerance

    Federal Register 2010, 2011, 2012, 2013, 2014

    1997-10-29

    ...contains 10-15 mg of iron a day. Ferric phosphate is also sometimes used as a fertilizer. In addition, iron is found in abundance in nature; the low water- solubility of ferric phosphate limits its absorption across the intestinal...

  5. The Effect of Ferric Chloride on Superficial Bleeding

    PubMed Central

    Nouri, Saeed; Sharif, Mohammad Reza; Sahba, Sare

    2015-01-01

    Background: Controlling superficial bleeding, despite all the progress in surgical science, is still a challenge in some settings. Objectives: This study assesses the hemostatic effects of ferric chloride and compares it with the standard method (suturing technique) to control superficial bleeding. Materials and Methods: In this animal model study, 60 male Wistar rats were used. An incision, 2 cm long and 0.5 cm deep was made on rat skin and the hemostasis time was recorded using ferric chloride at different concentrations (5%, 10%, 15%, 25%, and 50%) and then using a control (i.e. control of bleeding by suturing). The skin tissue was examined for pathological changes. Finally, the obtained data were entered into SPSS (ver. 16) and analyzed using Kruskal-Wallis test, Mann-Whitney, Kolmogorov-Smirnov, and Wilcoxon signed ranks test. Results: The hemostasis time for the ferric chloride concentration group was significantly less than for the control group (P < 0.001). Conclusions: Ferric chloride may be an effective hemostatic agent to control superficial bleeding in rats. PMID:25825694

  6. Thermal battery comprising iron pyrite depolarizer and ferric sulfate additive

    SciTech Connect

    Winchester, C.S.; Williams, M.T.

    1987-06-23

    This patent describes a thermal battery having a salt electrolyte, means to activate the battery by melting the electrolyte, and a FeS/sub 2/ depolarizer. The improvement comprises an amount of ferric sulfate effective to cause the occurrence of a voltage transient of predetermined magnitude and duration on activation of the battery.

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

    NASA Astrophysics Data System (ADS)

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

    2000-10-01

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

  8. 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

  9. 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, ? E a, ? H #, ? S #, ? G ?, for the reaction were calculated by using Arrhenius and Eyring plot. Surface excess concentration (?max), minimum area per surfactant molecule ( A min), average area occupied by each molecule of surfactant ( a), surface pressure at the CMC (?max), Gibb's energy of micellization (? G M°), Gibb's energy of adsorption (? G ad°), were calculated. It was found that the reaction in the presence of surfactant showed faster oxidation rate than the aqueous ethanol solution. Reaction mechanism has been deduced in the presence and absence of surfactant.

  10. The Reduction of Ferric Oxalate by Isolated Chloroplasts

    Microsoft Academic Search

    R. Hill; R. Scarisbrick

    1940-01-01

    1. The isolated chloroplasts from Stellaria media show a progressive fall in activity approaching zero in 3-6 hr. Four different strains of the plant were grown which showed differences in the stability of chloroplasts after removal. 2. Two methods have been used to measure the activity of chloroplasts: (a) The measurement with HbO2 of oxygen produced from ferric potassium oxalate

  11. Reaction mechanism for the acid ferric sulfate leaching of chalcopyrite

    Microsoft Academic Search

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

    1979-01-01

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

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

    Microsoft Academic Search

    D L Fleming; B Y Lum; A K Roy

    1998-01-01

    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 (FeClâ) 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,

  13. 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.

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

  16. Wastewater Treatment Technology Based on Iron Oxides

    Microsoft Academic Search

    J. D. Navratil

    \\u000a Iron oxides have been used in a variety of forms for wastewater treatment. In most precipitation processes ferric ions are\\u000a used to treat basic aqueous solutions by forming a ferric hydroxide floc to scavenge radioactive and heavy metal contaminants.\\u000a In adsorption processes, a variety of iron containing minerals have been utilised. Since 1970, we have utilised ferrites and\\u000a the mineral

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

    SciTech Connect

    Beitz, James V. [Chemistry Division, 9700 South Cass Avenue, Argonne National Laboratory, Argonne, IL 60439-4831 (United States)]. E-mail: beitz@anl.gov; Williams, C.W. [Chemistry Division, 9700 South Cass Avenue, Argonne National Laboratory, Argonne, IL 60439-4831 (United States); Hong, K.-S. [Chemistry Division, 9700 South Cass Avenue, Argonne National Laboratory, Argonne, IL 60439-4831 (United States); Liu, G.K. [Chemistry Division, 9700 South Cass Avenue, Argonne National Laboratory, Argonne, IL 60439-4831 (United States)

    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.

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

    NASA Astrophysics Data System (ADS)

    Sageshima, Yoshio; Noro, Atsushi; Matsushita, Yushu

    2013-03-01

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

  19. 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.

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

    PubMed

    Biasetti, M; Dawson, R

    2002-06-01

    Taurine is a free amino acid found in high concentrations in tissues containing catecholamines. The ability of taurine and its metabolic precursors to inhibit or stimulate catecholamine oxidation and subsequent quinone formation was examined. Ferric chloride was used as the catalyzing agent to stimulate L-dopa or norepinephrine oxidation and NO donors were also examined for their actions to stimulate quinone formation. Taurine attenuated iron-stimulated quinone formation from catecholamines suggesting that it may function as an endogenous antioxidant. Several other sulfur-containing amino acids (homocysteic acid, cysteine sulfinic acid and SAM) were found to inhibit catecholamine oxidation. Among other amino acids tested, homocysteine had biphasic effects; attenuating L-dopa oxidation catalyzed by ferric chloride and potentiating norepinephrine's oxidation catalyzed by both ferric chloride and sodium nitroprusside (SNP). Homotaurine and homocysteine (1 or 10 mM) greatly stimulated SNP-induced norepinephrine oxidation. Homotaurine potentiated quinone formation in the presence of ferric iron and this effect was attenuated by desferroxamine. In order to exclude a possible NO/iron interaction in SNP's oxidizing action, SIN-1 chloride, a specific NO-donor, was tested as an oxidizing agent. The failure of desferroxamine or taurine to attenuate SIN-1 oxidation of norepinephrine suggests that peroxynitrite-mediated oxidation was likely the dominant mechanism. Our results show that endogenous sulfur containing amino acids, like taurine, could serve a protective role to reduce cellular damage associated with both NO and metal-stimulated catecholamine oxidation. PMID:12107762

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

    NASA Technical Reports Server (NTRS)

    Orwoll, Robert A.; Thompson, David W.

    1999-01-01

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

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    SciTech Connect

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

    2012-10-15

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

  5. QTL analysis of ferric reductase activity in the model legume lotus japonicus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Physiological and molecular studies have demonstrated that iron accumulation from the soil into Strategy I plants can be limited by ferric reductase activity. An initial study of Lotus japonicus ecotypes Miyakojima MG-20 and Gifu B-129 identified significant leaf chlorosis and ferric reductase activ...

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

    Microsoft Academic Search

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

    1996-01-01

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

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

    PubMed

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Szlachta, Ma?gorzata; W?odarczyk, Pawe?; 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 ferric hydroxides for treatment As-contaminated waters. This research is a part of the study supported by the National Centre for Research and Development grant (2014-2017) "Sustainable and responsible supply of primary resources - SUSMIN" (http://projects.gtk.fi/susmin), within the EU ERA-NET ERA-MIN program.

  9. Sintering of nanophase oxide ceramics by using millimeter-wave radiation

    Microsoft Academic Search

    Y. Bykov; S. Gusev; A. Eremeev; V. Holoptsev; N. Malygin; S. Pivarunas; A. Sorokin; A. Shurov

    1995-01-01

    Sintering of nanocrystalline powder materials by microwave heating has been studied. Two types of materials have been investigated: compacts of Al2 O3 ? ZrO2 (Y2 O3) (average grain size 15 nm), prepared by the sol gel method, and TiO2 compacts (?100 nm) produced by the blasted-wire method. The kinetics of Al2O3 ? ZrO2 compact densification and grain growth under microwave

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

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

    PubMed Central

    Troxell, Bryan; Hassan, Hosni M.

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

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

    USGS Publications Warehouse

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

    1997-01-01

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

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

    PubMed

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

    2014-01-01

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

  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. How the Ferric Iron Proportion in Basalts Changes Towards the Iceland Plume

    NASA Astrophysics Data System (ADS)

    Shorttle, O.; Moussallam, Y.; Hartley, M. E.; Edmonds, M.; Maclennan, J.; Murton, B. J.

    2014-12-01

    Planetary differentiation has been driven by the Earth's giant convective system, which has been redistributing heat, volatile elements and myriad other chemical species for 4.5 billion years. A key exchange in this transport process is between the mantle and the atmosphere through the volcanic degassing of sulfur, carbon and hydrogen from silicate melts forming in the deep Earth. The speciation and mobility of volatile elements during silicate melting is modulated by the oceanic mantle's oxygen fugacity (fO2), which away from subduction zones has long been considered uniform. However, a recent study has challenged this paradigm with new measurements of ferric iron proportions (Fe3+/Fe) in glasses from mid-ocean ridge basalts (Cottrell & Kelley, 2013). These new results suggest mantle domains containing material recycled from the Earth's surface are more reducing than ambient mantle and contain high concentrations of carbon. The pervasive mantle heterogeneity well documented in other geochemical indices may therefore be systematically associated with changes in oxidation state In this study we have produced a dataset of combined XANES, volatile element (C, S, F, Cl, H, B) and boron isotope analyses of 65 basalts from the Mid-Atlantic Ridge south of Iceland. These samples form a transect from 1000 km south of the Iceland plume to within 300 km of the plume centre, crossing into the zone experiencing the greatest geophysical and geochemical influence from the plume. Accordingly there are major changes in the isotopic and trace element composition of the basalts in this sample set, driven by both an increase in the proportion of recycled oceanic crustal components towards Iceland and a shift to a plume driven flow field. This suite of basalts therefore form an excellent test of the global correlations observed by Cottrell & Kelley (2013), where ferric iron contents anti-correlated with isotopic enrichment, with a high resolution regional dataset. By combining major element, volatile element and boron isotope data we have also interrogated the role of magmatic processes such as assimilation and degassing in influencing magmatic redox state. References: E. Cottrell & K. A. Kelley, Science, 340:1314 2013.

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

    Microsoft Academic Search

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

    2009-01-01

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

  19. 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.

  20. 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

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

    PubMed Central

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

    2014-01-01

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

  2. Computational support for a pyrolitic lower mantle containing ferric iron

    NASA Astrophysics Data System (ADS)

    Wang, Xianlong; Tsuchiya, Taku; Hase, Atsushi

    2015-07-01

    The dominant minerals in Earth’s lower mantle are thought to be Fe- and Al-bearing MgSiO3 bridgmanite and (Mg, Fe)O ferropericlase. However, experimental measurements of the elasticity of these minerals at realistic lower-mantle pressures and temperatures remain impractical. As a result, different compositional models for the Earth’s lower mantle have been proposed. Theoretical simulations, which depend on empirical evaluations of the effects of Fe incorporation into these minerals, support a pyrolitic lower mantle that contains a significant amount of ferropericlase, much like the Earth’s upper mantle. Here we present first-principles computations combined with a lattice dynamics approach that include the effects of Fe2+ and Fe3+ incorporation. We calculate the densities and elastic-wave velocities of several possible lower-mantle compositions with varying amounts of ferropericlase along a mantle geotherm. On the basis of our calculations of aggregate elasticities, we conclude that neither a perovskitic composition (about 9:1 bridgmanite to ferropericlase by volume) nor an olivine-like composition (about 7:3) reproduces the seismological reference model of average Earth properties. However, an intermediate volume fraction (about 8:2) consistent with a pyrolitic composition can reproduce the reference velocities and densities. Bridgmanite that is rich in ferric iron produces the best fit. Our findings support a uniform chemical composition throughout the present-day mantle, which we suggest is the result of whole-mantle convection.

  3. 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.

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

    Microsoft Academic Search

    Danna Zhou; Feng Wu; Nansheng Deng; Wu Xiang

    2004-01-01

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

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

    Microsoft Academic Search

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

    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?m) in this work. The experimental results have shown that arsenic-borne coagulates produced by coagulation with ferric ions alone were very fine, so micro-filtration (membrane as filter medium) was needed to remove the coagulates from water.

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

    Microsoft Academic Search

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

    2008-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

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

    PubMed

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

    2014-07-16

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

  9. 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

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

    SciTech Connect

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

    1991-03-15

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

  11. Ferrous iron oxidation by anoxygenic phototrophic bacteria

    Microsoft Academic Search

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

    1993-01-01

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

  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. 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. PMID:21413720

  14. Side chain crystallization and non-equilibrium phenomena in nanophase separated poly(3-alkyl thiophenes)

    NASA Astrophysics Data System (ADS)

    Pankaj, Shireesh; Beiner, Mario

    2010-06-01

    A series of regio-random poly(3-alkyl thiophenes) containing C = 6-12 carbon atoms per side chain is studied using shear, calorimetry and x-ray scattering methods. Dynamic and structural data indicate a nanophase separation of thiophene main chains and alkyl groups. Alkyl nanodomains of size of 1-3 nm are formed as indicated by pre-peaks in scattering data at 0.2Å-1?q?0.6Å-1. Apart from the conventional ? relaxation, an additional ?PE process appears at low temperatures reflecting an independent dynamics within the alkyl nanodomains. The influence of slow side chain crystallization and densification processes during physical aging below Tg on the relaxation behavior is studied. Long term experiments show that short alkyl groups do not crystallize, whereas for longer alkyl groups, side chain crystallization is occurring but hindered by immobile and rigid main chains. Slow side chain crystallization processes are indicated in poly(3-decyl thiophene) and poly(3-dodecyl thiophene) by melting peaks in DSC scans, a decreasing ?PE intensity and an increase in the plateau modulus. Isothermal crystallization experiments on these samples show that the alkyl groups can exist in different polymorphic states.

  15. In Situ Iron Oxide Emplacement for Groundwater Arsenic Remediation

    E-print Network

    Abia, Thomas Sunday

    2012-02-14

    onto the surface as ferric oxide. The iron oxide (FeOx) emplacement process was significantly affected by (1) the initial surface area and surface-bound iron content of the sand, (2) the pH and solubility of the coating reagents, (3) the stability...

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

    Microsoft Academic Search

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

    2006-01-01

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

  17. Oxidation and coagulation of humic substances by potassium ferrate.

    PubMed

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

    2010-01-01

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

  18. 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, ? < 0.0701 u (b) transition regime, 0.0701 u ? ? ? 0.0916 u and (c) thick coating regime, ? > 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 < ? < 7.0 nm transition regime, 7.0 < ? < 9.2 nm and thick coating, ? > 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 components can have substantial effects upon aggregation for concentrations less than 1%. PMID:25347720

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

    PubMed

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

    2014-07-22

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

  20. Mutation in the flavin mononucleotide domain modulates magnetic circular dichroism spectra of the iNOS ferric cyano complex in a substrate-specific manner.

    PubMed

    Sempombe, Joseph; Galinato, Mary Grace I; Elmore, Bradley O; Fan, Weihong; Guillemette, J Guy; Lehnert, Nicolai; Kirk, Martin L; Feng, Changjian

    2011-08-01

    We have obtained low-temperature magnetic circular dichroism (MCD) spectra for ferric cyano complexes of the wild type and E546N mutant of a human inducible nitric oxide synthase (iNOS) oxygenase/flavin mononucleotide (oxyFMN) construct. The mutation at the FMN domain has previously been shown to modulate the MCD spectra of the l-arginine-bound ferric iNOS heme (Sempombe, J.; et al. J. Am. Chem. Soc. 2009, 131, 6940-6941). The addition of l-arginine to the wild-type protein causes notable changes in the CN(-)-adduct MCD spectrum, while the E546N mutant spectrum is not perturbed. Moreover, the MCD spectral perturbation observed with l-arginine is absent in the CN(-) complexes incubated with N-hydroxy-L-arginine, which is the substrate for the second step of NOS catalysis. These results indicate that interdomain FMN-heme interactions exert a long-range effect on key heme axial ligand-substrate interactions that determine substrate oxidation pathways of NOS. PMID:21718007

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

    PubMed

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

    2014-04-30

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

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

    PubMed Central

    Kuster, Martina; Meli, Damian N.

    2015-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  4. Oxidation of phenol by green rust and hydrogen peroxide at neutral pH

    Microsoft Academic Search

    Roger Matta; Khalil Hanna; Serge Chiron

    2008-01-01

    The reactions involving green rusts (GRs), mixed ferrous–ferric oxides, remain poorly described relative to other iron oxides minerals which have been studied much more extensively. While the role of GRs in the reduction of chlorinated solvents and inorganic contaminants has been investigated, no work has appeared concerning the use of GR to promote Fenton reaction and oxidize organic pollutants.In this

  5. Recognition of Ferric Catecholates by FepA

    PubMed Central

    Annamalai, Rajasekaran; Jin, Bo; Cao, Zhenghua; Newton, Salete M. C.; Klebba, Phillip E.

    2004-01-01

    Escherichia coli FepA transports certain catecholate ferric siderophores, but not others, nor any noncatecholate compounds. Direct binding and competition experiments demonstrated that this selectivity originates during the adsorption stage. The synthetic tricatecholate Fe-TRENCAM bound to FepA with 50- to 100-fold-lower affinity than Fe-enterobactin (FeEnt), despite an identical metal center, and Fe-corynebactin only bound at much higher concentrations. Neither Fe-agrobactin nor ferrichrome bound at all, even at concentrations 106-fold above the Kd. Thus, FepA only adsorbs catecholate iron complexes, and it selects FeEnt among even its close homologs. We used alanine scanning mutagenesis to study the contributions of surface aromatic residues to FeEnt recognition. Although not apparent from crystallography, aromatic residues in L3, L5, L7, L8, and L10 affected FepA's interaction with FeEnt. Among 10 substitutions that eliminated aromatic residues, Kd increased as much as 20-fold (Y481A and Y638A) and Km increased as much as 400-fold (Y478), showing the importance of aromaticity around the pore entrance. Although many mutations equally reduced binding and transport, others caused greater deficiencies in the latter. Y638A and Y478A increased Km 10- and 200-fold more, respectively, than Kd. N-domain loop deletions created the same phenotype: ?60-67 (in NL1) and ?98-105 (in NL2) increased Kd 10- to 20-fold but raised Km 500- to 700-fold. W101A (in NL2) had little effect on Kd but increased Km 1,000-fold. These data suggested that the primary role of the N terminus is in ligand uptake. Fluorescence and radioisotopic experiments showed biphasic release of FeEnt from FepA. In spectroscopic determinations, koff1 was 0.03/s and koff2 was 0.003/s. However, FepAY272AF329A did not manifest the rapid dissociation phase, corroborating the role of aromatic residues in the initial binding of FeEnt. Thus, the ?-barrel loops contain the principal ligand recognition determinants, and the N-domain loops perform a role in ligand transport. PMID:15150246

  6. 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.

  7. 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

    2010-07-01

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

  8. Microbial acquisition of iron from ferric iron bearing minerals

    SciTech Connect

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

    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.

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

    NASA Astrophysics Data System (ADS)

    Taylor, Lawrence A.

    2002-01-01

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

  10. Structure of Amorphous Ferric Arsenate from EXAFS Spectroscopy and Total X-ray Scattering

    NASA Astrophysics Data System (ADS)

    Mikutta, Christian; Michel, Frederick Marc; Mandaliev, Petar; Kretzschmar, Ruben

    2013-04-01

    Short-range ordered ferric arsenate (FeAsO4 ×nH2O) is a secondary As mineral frequently encountered in acid mine-waste environments. Its structure has been proposed to resemble that of scorodite (FeAsO4×2H2O) in which isolated FeO6 octahedra share corners with four adjacent arsenate (AsO4) tetrahedra in a three-dimensional network (scorodite model). Conversely, short-range ordered ferric arsenate was postulated to consist of single chains of corner-sharing FeO6 octahedra being bridged by arsenate bound in a monodentate binuclear 2C complex (butlerite/fibroferrite model). In order to test the accuracy of both structural models, we synthesized ferric arsenates and analyzed their structure by As and Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy and total X-ray scattering. We found that both As and Fe K-edge EXAFS spectra were most compatible with isolated FeO6 octahedra being bridged by AsO4 tetrahedra (RFe-As= 3.33 ± 0.01 Å). EXAFS shell-fits and reduced pair distribution functions, G(r), indicated a lack of evidence for single corner-sharing FeO6 linkages in ferric arsenate. Wavelet-transform analyses of the Fe K-edge EXAFS spectra of ferric arsenates complemented by shell fitting confirmed Fe atoms at an average distance of 5.3 Å, consistent with crystallographic data of scorodite and in disagreement with the butlerite/fibroferrite model. A scorodite-type local structure of short-range ordered ferric arsenates provides a plausible explanation for their rapid transformation into scorodite in acid mining environments.

  11. DBAR investigation on films of polypyrrole incorporated polyvinylalcohol doped with ferric chloride

    NASA Astrophysics Data System (ADS)

    Lobo, Blaise; Baraker, B. M.; Hammannavar, P. B.; Bhajantri, R. F.; Ranganath, M. R.; Hurkadli, M.; Ravindrachary, V.

    2015-06-01

    Flexible films of pyrrole(Py) sorbed, ferric chloride (FeCl3) doped polyvinylalcohol(PVA) were prepared by solution casting. The films were characterized by XRD, UV-Visible spectrometry, Thermal Analysis (DSC, DTA/TGA), FTIR and electrical measurements. In this paper, the results of Doppler Broadening of Annihilation Radiation (DBAR) spectra in the doping range, from 4 wt% up to 18 wt%, are discussed. The XRD and DSC scans complement the DBAR results. The computed S- parameter and W -parameter reflect changes in the degree of crystallinity and the average crystallite size, respectively, of polypyrrole(PPy) incorporated PVA samples doped with ferric chloride.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

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

    Microsoft Academic Search

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

    2007-01-01

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

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

    Microsoft Academic Search

    Priyabrata Sarkar; Priyabrata Pal; Dipankar Bhattacharyay; Suchanda Banerjee

    2010-01-01

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

  15. 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...

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

    EPA Science Inventory

    The behavior 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 nanner. ew method for determining dissolved fer...

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

    PubMed

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

    2014-03-15

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

  18. Iron Bioavailability from Pate Enriched with Encapsulated Ferric Pyrophosphate or Ferrous Gluconate in Rats

    Microsoft Academic Search

    S. Navas-Carretero; A. M. Pérez-Granados; B. Sarriá; S. Schoppen; M. P. Vaquero

    2007-01-01

    Fortifying food with iron has been widely studied as a strategy to prevent iron deficiency anaemia. This work comparatively assessed the bioavailability of two forms of iron, ferrous gluconate or ferric pyrophosphate encapsulated in liposomes (lipofer®), when used as fortificants in meat pate. Three groups of growing rats consumed during 28 days either a control diet (AIN-93G), or two diets

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

    Microsoft Academic Search

    C. S. Poon; C. W. Chu

    1999-01-01

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

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

    Microsoft Academic Search

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

    1986-01-01

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

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

    Microsoft Academic Search

    Michael Vella; Joseph D. Zuckerman; Sonya Shortkroff; Prasanna Venkatesan; Clement B. Sledge

    1988-01-01

    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

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

    Microsoft Academic Search

    MATTHIAS HOMUTH; PETER VALENTIN-WEIGAND; M. ROHDE

    1998-01-01

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

  3. Opsonic Activity of Serum and Whey from Cows Immunized with the Ferric Citrate Receptor1

    Microsoft Academic Search

    A. J. Wise; J. S. Hogan; K. Takemura; K. L. Smith

    2003-01-01

    The effects of immunizing dairy cows with the ferric citrate receptor, FecA, on the opsonic activity of serum and whey were measured in a phagocytosis assay. Fif- teen cows were assigned to five blocks of three cows based on date of expected parturition. Cows within a block were randomly assigned to one of three treat- ments: 1) FecA immunization, 2)

  4. A 13-week subchronic toxicity study of ferric citrate in F344 rats.

    PubMed

    Toyoda, Takeshi; Cho, Young-Man; Mizuta, Yasuko; Akagi, Jun-ichi; Ogawa, Kumiko

    2014-12-01

    Ferric citrate has been used as a food additive for supplementation of iron. We performed a 13-week subchronic toxicity study of ferric citrate in F344 rats with oral administration in the diet at concentrations of 0%, 0.25%, 1.0%, and 4.0%. Reduction of body weight gain was noted in 4.0% males and females. On hematology assessment, decreases of red blood cells and lymphocytes and increases of platelets and eosinophils were noted in 4.0% males and females. Serum biochemistry demonstrated increased iron and decreased total protein and transferrin in both sexes treated with 4.0% ferric citrate. In addition, an increase of serum inorganic phosphorus levels was noted in 4.0% females. Regarding organ weights, an increase of relative spleen weights was detected in 4.0% males and females and a decrease of absolute and relative heart weights in 4.0% females. On histopathological assessment, colitis with infiltration of eosinophils and hyperplasia of mucosal epithelium, eosinophilic infiltration in mesenteric lymph nodes, and increased hemosiderosis in spleen were observed as treatment-related toxicological changes in 4.0% males and females. Based on the results, the no-observed-adverse-effect level (NOAEL) of ferric citrate was estimated to be 1.0% (596?mg/kg bw/day for males and 601?mg/kg bw/day for females). PMID:25257695

  5. Ferric reductase activity and PsFRO1 sequence variation in pisum sps

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Physiological studies in pea (Pisum sativum) suggest that the reduction of iron (Fe) is the rate-limiting physiological process in Fe acquisition by dicotyledonous plants. Previous molecular work suggests that ferric reductase activity is regulated at both the transcriptional and post-translational ...

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

    Microsoft Academic Search

    Yu Yang; Peng Wang; Yuan Liu

    2010-01-01

    In the present work, the investigations were firstly focused on the effect of microwave on the species distribution of ferric hydrolysates, as well as the effect of hydrolysates speciation on the treatment efficiency of organic compounds in the process of coagulation. A ferron-complexation timed spectrophotometric method was used to classify the Fe(III) speciation under different reaction conditions. Effects of microwave

  7. MOLECULAR AND PHENOTYPIC CHARACTERIZATION OF TRANSGENIC SOYBEAN EXPRESSING THE ARABIDOPSIS FERRIC CHELATE REDUCTASE GENE, FRO2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean (Glycine max Merr.) production is reduced under iron-limiting calcareous soils throughout the upper Midwest regions of the U.S. Soybean like other dicotyledonous plants responds to iron-limiting environments by induction of an active proton pump, a ferric iron reductase and a Fe transporter....

  8. 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...

  9. Achievable Magnetic Fields of Super-Ferric Helical Undulators for the ILC

    E-print Network

    Kemner, Ken

    Achievable Magnetic Fields of Super-Ferric Helical Undulators for the ILC S.H. Kim Advanced Photon Source, Argonne National Laboratory Abstract ­ The magnetic fields on the beam axis of helical undulators superconducting coils was estimated to about 1.1. A transverse periodic helical magnetic field may be generated

  10. 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 ...

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

    Microsoft Academic Search

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

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

  12. Spectrophotometric Determination of some Recently Introduced Antibacterial Drugs Using Ferric Chloride

    Microsoft Academic Search

    S. K. Bhowal; T. K. Das

    1991-01-01

    Simple and selective spectrophotometric methods for the determination of norfloxacin, ciprofloxacin, cinoxacin and nalidixic acid are described. The methods are based on the measurement of the intensity of the orange-red colour produced by the drugs with ferric chloride in dimethylsulphoxide-methanol medium. The methods are highly accurate and have been successfully applied for analysis of bulk drugs and pharmaceutical preparations. The

  13. A predictive model (ETLM) for As(III) adsorption and surface speciation on oxides consistent with spectroscopic data

    E-print Network

    Sverjensky, Dimitri A.

    been built into a recent extension of the triple-layer model (ETLM) for the formation of inner for magnetite, goethite, gibbsite, amorphous hydrous alumina, hydrous ferric oxide (HFO), ferrihydrite constants on all oxides, including both amorphous and poorly crys- talline oxides, enables prediction

  14. Microwave-assisted synthesis of iron(III) oxyhydroxides\\/oxides characterized using transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy

    Microsoft Academic Search

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

    2009-01-01

    Microwave-assisted synthesis of iron oxide\\/oxyhydroxide nanophases was conducted using iron(III) chloride titrated with sodium hydroxide at seven different temperatures from 100 to 250°C with pulsed microwaves. From the X-ray diffraction (XRD) results, it was determined that there were two different phases synthesized during the reactions which were temperature dependent. At the lower temperatures, 100 and 125°C, it was determined that

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

    PubMed Central

    Thomas, Anila; Peterson, Leif E

    2014-01-01

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

  16. 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.

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

    Microsoft Academic Search

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

    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:

  18. 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.

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

    Microsoft Academic Search

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

    2003-01-01

    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

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

    Microsoft Academic Search

    M. Biasetti; R. Dawson Jr.

    2002-01-01

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

  1. Taurine inhibition of metal-stimulated catecholamine oxidation.

    PubMed

    Dawson, R; Baker, D; Eppler, B; Tang, E; Shih, D; Hern, H; Hu, M

    2000-01-01

    Taurine is an abundant amino acid found in mammalian tissues and it has been suggested to have cytoprotective functions. The aim of the present study was to determine if taurine had the potential to reduce oxidative stress associated with metal-stimulated catecholamine oxidation. Taurine and structural analogs of taurine were tested for their ability to inhibit metal-stimulated quinone formation from dopamine or L-dopa. Oxidative damage to proteins and lipids were also assessed in vitro and the effects of taurine were determined. Taurine (20 mM) was found to decrease significantly ferric iron (50-500 microM)- and manganese (10 microM)-stimulated L-dopa or dopamine oxidation. Taurine had no effect on zinc-induced dopamine oxidation and slightly potentiated copper- and NaIO(4)-stimulated quinone formation. Ferric iron-stimulated lipid peroxidation was not affected by taurine (1-20 mM). Protein carbonyl formation induced by ferric iron (500 microM) and L-dopa (500 microM) was significantly reduced by 10 mM taurine. The cytotoxicity of L-dopa (250 microM) and ferric chloride (75 microM) to LLC-PK(1) cells was attenuated by 10 mM taurine or hypotaurine. Homotaurine alone stimulated L-dopa oxidation and potentiated the cytotoxic effects of ferric iron. Homotaurine was found to be cytotoxic when combined with L-dopa or L-dopa/iron. In contrast, hypotaurine inhibited quinone formation and protected LLC-PK(1) cells. These studies suggest that taurine may exhibit cytoprotective effects against the oxidation products of catecholamines by acting as a scavenger for free radicals and cytotoxic quinones. PMID:15545001

  2. Increase in ferric and ferrous iron in the rat hippocampus with time after kainate-induced excitotoxic injury.

    PubMed

    Wang, X S; Ong, W Y; Connor, J R

    2002-03-01

    The present study aimed to elucidate the distribution of ferric and ferrous iron in the hippocampus after kainate-induced neuronal injury. A modified Perl's or Turnbull's blue histochemical stain was used to demonstrate Fe3+ and Fe2+ respectively. Very light staining for iron was observed in the hippocampus, in normal or saline-injected rats and 1-day post-kainate-injected rats. At 1 week postinjection, a number of Fe3+-positive, but very few Fe2+-positive, cells were present, in the degenerating CA fields. At 1 month postinjection, large numbers of Fe3+-positive glial cells, and some Fe2+-positive blood vessels, were observed. At 2 months postinjection, large numbers of Fe3+- and Fe2+-positive glial cells were present. The labeled cells had light and electron microscopic features of oligodendrocytes, and were double labeled with CNPase, a marker for oligodendrocytes. The observation of an increasing number of Fe3+- and Fe2+-positive cells in the degenerating hippocampus with time is consistent with the results of a nuclear microscopic study, in which an increasing amount of iron was detected in the degenerating hippocampus after kainate injection. In addition, the present study showed a shift in the oxidation state of the accumulated iron, with more cells becoming Fe2+ at a late stage. A possible consequence of the high amounts of Fe2+ in the hippocampus after kainate injection is that it could promote free radical damage in the lesioned areas. PMID:11880890

  3. Influence of anions on the morphology of nanophase alpha-MnO2 crystal via hydrothermal process.

    PubMed

    Gao, Yongqian; Wang, Zhenghua; Liu, Shenglin Xiong Yi; Qian, Yitai

    2006-08-01

    The alpha-MnO2 nanocrystal nanowires, nanoplates, and nanoflowers have been successfully synthesized by a common hydrothermal treatment of different solutions containing KMnO4 and NH4X (X = Cl-, Ac-, NO3-, SO4(2-), and PO4(3-)) at 140 degrees C for 24 h. The influence of anions on the morphology of final product is discussed. According to our experimental results, we proposed a possible mechanism of the formation of different morphologies of nano-phase alpha-MnO2 and considered that the growing process was due to the initial plate-like MO(x) absorbing different anions and cooperation with them, which contributes to the final morphology of the product. PMID:17037875

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

    PubMed

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

    2014-11-01

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

  5. Energy cascades, excited state dynamics, and photochemistry in cob(III)alamins and ferric porphyrins.

    PubMed

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

    2015-03-17

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

  6. CAN NANO-PHASE SILICA ORIGINATE FROM CHONDRITIC FLUIDS? THE APPLICATION TO ENCELADUS' SiO2 PARTICLES. M. Yu. Zolotov1

    E-print Network

    Rhoads, James

    CAN NANO-PHASE SILICA ORIGINATE FROM CHONDRITIC FLUIDS? THE APPLICATION TO ENCELADUS' SiO2 indicates water-rock interaction in the history of the icy moon [1,2]. Silica (SiO2) nano-size particles, evaporation or freez- ing of the fluids. On Earth, amorphous opaline silica (SiO2 nH2O or SiO2(am)) commonly

  7. Iron-Titanium Oxides and Oxygen Fugacities in Volcanic Rocks

    Microsoft Academic Search

    I. S. E. Carmichael; J. Nicholls

    1967-01-01

    It is shown that in silicate liquids the ferric-ferrous equilibrium is controlled by temperature, oxygen fugacity, and the composition of the liquid, particularly its alkali content. Thus, if the iron-titanium oxide minerals that precipitate from a silicate liquid reflect the ferricferrous equilibrium, the oxygen geobarometer of Buddington and Lindsley will have to be calibrated, especially for such volcanics as phonolites

  8. 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.

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

    SciTech Connect

    Crowe, C.W.

    1982-03-02

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

  10. 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.

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

    PubMed

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

    1989-08-01

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

  12. Magnetic Anisotropy in Single-Crystal Ferric Ammonium Alum below Its Magnetic Critical Point

    Microsoft Academic Search

    C. W. Dempesy; R. C. Sapp

    1958-01-01

    The adiabatic susceptibility of single crystals of ferric ammonium alum has been determined as a function of entropy and applied field below 0.1°K. Two methods of measurement have been employed: in addition to a standard ballistic bridge technique, a moving-coil device has been developed to yield static values. A ballistic galvanometer of period 4.6 seconds was used in both circuits.

  13. Reduction of post-surgical adhesions with ferric hyaluronate gel: a European study

    Microsoft Academic Search

    Per Lundorff; Hans van Geldorp; Sven Erik Tronstad; Othon Lalos; Bertil Larsson; Douglas B. Johns

    BACKGROUND: The objective of this study was to assess the safety and efficacy of a 0.5% ferric hyaluronate gel, in reducing adhesions in patients undergoing peritoneal cavity surgery by laparotomy, with a planned 'second- look' laparoscopy. METHODS: The study was a randomized (by computer-generated schedule), third party blinded, placebo-controlled, parallel-group design conducted at five centres in Europe. Females aged 18-46

  14. Treatment of antigen-induced arthritis in rabbits with dysprosium-165-ferric hydroxide macroaggregates

    Microsoft Academic Search

    Joseph D. Zuckerman; Clement B. Sledge; Sonya Shortkroff; Prasanna Venkatesan

    1989-01-01

    Dysprosium-165-ferric hydroxide macroaggregates (¹⁶⁵Dy-FHMA) was used as an agent of radiation synovectomy in an antigen-induced arthritis model in New Zealand white rabbits. Animals were killed up to 6 months after treatment. ¹⁶⁵Dy-FHMA was found to have a potent but temporary antiinflammatory effect on synovium for up to 3 months after treatment. Treated knees also showed significant preservation of articular cartilage

  15. 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 ?-delocalization along the alkyl chain. The As values of 2T2 and 6A1 states have the same sign.

  16. Effects of silicate, sulfate, and carbonate on arsenic removal by ferric chloride

    Microsoft Academic Search

    Xiaoguang Meng; Sunbaek Bang; George P Korfiatis

    2000-01-01

    Effects of silicate, sulfate, and carbonate on the removal of arsenite [As(III)] and arsenate [As(V)] by coprecipitation with ferric chloride were studied. Silicate significantly decreased As(III) removal when Si concentration was higher than 1 mg\\/l and the pH was greater than 5. The removal of As(V) was decreased moderately by silicate in 0.04 M KNO3 solution. Addition of Ca2+ and Mg2+ to

  17. Crystal-Field Theory Investigation of Bis(N, N-Dialkyldithiocarbamato) Ferric Halides

    Microsoft Academic Search

    Robert L. Ake; Gilda M. Harris Loew

    1970-01-01

    The crystal-field model is used to describe ferric ion in the five-coordinated bis(dialkyldithiocarbamato) halide complexes. All seven compounds investigated have quartet ground states. A fit to experimental zero-field splittings is obtained naturally and provides eigenfunctions and eigenvalues which can be used to calculate magnetic properties. The calculated electric-field gradient, due to a large lattice term, and magnetic moment, showing little

  18. Degradation of Ferric Chelate of Ethylenediaminetetraacetic Acid by Bacterium Isolated from Deep-Sea Stalked Barnacle

    Microsoft Academic Search

    Chiaki Imada; Yohei Harada; Takeshi Kobayashi; Naoko Hamada-Sato; Etsuo Watanabe

    2005-01-01

    Twenty strains of marine bacteria that degrade ferric chelate of ethylenediaminetetraacetic acid (Fe-EDTA) were isolated from among 117 strains collected from a marine environment. Among them strain 02-N-2, which was isolated from stalked barnacle collected from the deep sea in the Indian Ocean, had the highest Fe-EDTA degradation ability and was selected for further study. The strain showed high Fe-EDTA

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

    Microsoft Academic Search

    S. M. Macfie; A. A. Crowder

    1987-01-01

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

  20. 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-?XRF) imaging at Fe and As K-edges showed that As formed surface complexes with ferrihydrite > siderite > green rust in the low sulfate column; while discrete realgar-like phases formed in the high sulfate systems. Results indicate that landfill sulfur chemistry exerts strong control over the potential mobilization of As from ferric sorbent residuals by controlling secondary As and Fe sulfide coprecipitate formation. PMID:24102155

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

    Microsoft Academic Search

    Züleyha Özlem Kocaba?; Yuda Yürüm

    2011-01-01

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

  2. Characterisation of aqueous ferric chloride etchants used in industrial photochemical machining

    Microsoft Academic Search

    David M. Allen; Heather J. A. Almond

    2004-01-01

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

  3. Inhibition of sulfate-reducing and methanogenic activities of anaerobic sewer biofilms by ferric iron dosing

    Microsoft Academic Search

    Lishan Zhang; Jürg Keller; Zhiguo Yuan

    2009-01-01

    Ferric iron is commonly used for sulfide precipitation in sewers, thus achieving corrosion and odour control. Its impact on the activities of sulfate-reducing bacteria and methanogens in anaerobic sewer biofilms is investigated in this study. Two lab-scale rising main sewer systems fed with real sewage were operated for 8 months. One received Fe3+ dosage (experimental system) and the other was

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

    PubMed Central

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

    2013-01-01

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

  5. Effect of polymer ferric sulfate on EPS in A2\\/O system

    Microsoft Academic Search

    Ai-cui Liu; Qin-xue Wen; Zhi-qiang Chen; Yu-fei Li

    2011-01-01

    An A 2 \\/O system was built up to simulate Luchun wastewater treatment plant in Wuxi. Polymer ferric sulfate (PFS) was added into the system at the end of aeration tank to enhance phosphorus removal. When the dosage of PFS was 2.99 mg Fe\\/L, the average total phosphorus (TP) in the effluent was 0.24 mg\\/L, which met the discharge standard

  6. Iron regulates transcription of the Escherichia coli ferric citrate transport genes directly and through the transcription initiation proteins

    Microsoft Academic Search

    Annemarie Angerer; Volkmar Braun

    1998-01-01

    Ferric citrate induces transcription of the ferric citrate transport genes fecABCDE in Escherichia coli by binding to the outer-membrane receptor protein FecA without entering the cell. Replete iron concentrations inhibit transcription\\u000a of the fec transport system via the iron-loaded Fur repressor. Here we show that the Fur repressor activated by Mn2+ (used instead of Fe2+) binds to the promoter of

  7. 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. PMID:19587418

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

    PubMed Central

    Ruvin Kumara, V. M.

    2012-01-01

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

  9. 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.

  10. 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

  11. Inhibition of sulfate-reducing and methanogenic activities of anaerobic sewer biofilms by ferric iron dosing.

    PubMed

    Zhang, Lishan; Keller, Jürg; Yuan, Zhiguo

    2009-09-01

    Ferric iron is commonly used for sulfide precipitation in sewers, thus achieving corrosion and odour control. Its impact on the activities of sulfate-reducing bacteria and methanogens in anaerobic sewer biofilms is investigated in this study. Two lab-scale rising main sewer systems fed with real sewage were operated for 8 months. One received Fe(3+) dosage (experimental system) and the other was used as a control. In addition to precipitating sulfide from bulk water, Fe(3+) dosage was found to significantly inhibit sulfate reduction and methane production by sewer biofilms. The experimental reactor discharged an effluent containing a higher concentration of sulfate and a lower concentration of methane in comparison with the reference reactor. Batch experiments showed that the addition of ferric ions reduced the sulfate reduction and methane production rates of the sewer biofilms by 60% and 80%, respectively. The batch experiments further showed that Fe(3+) dosage changed the final products of sulfate reduction with sulfide accounting for only 54% of the sulfate reduced. The other products could not be confirmed, but were not dissolved inorganic sulfur species such as sulfite or thiosulfate. The results suggest the addition of Fe(3+) at upstream locations would minimize the ferric salts required for achieving the same level of sulfide removal. Fe(3+) dosing could also substantially reduce the formation of methane, a potent greenhouse gas, in sewers. PMID:19576610

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

    PubMed Central

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

    1991-01-01

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

  13. Localization of functional domains in the Escherichia coli coprogen receptor FhuE and the Pseudomonas putida ferric-pseudobactin 358 receptor PupA

    Microsoft Academic Search

    Wilbert Bitter; I. S. Leeuwen; J. Boer; H. W. M. Zomer; M. C. Koster; P. J. Weisbeek; J. Tommassen

    1994-01-01

    Transport of ferric-siderophores across the outer membrane of gram-negative bacteria is mediated by specific outer membrane receptors. To localize the substrate-binding domain of the ferric-pseudobactin 358 receptor, PupA, of Pseudomonas putida WCS358, we constructed chimeric receptors in which different domains of PupA were replaced by the corresponding domains of the related ferric-pseudobactin receptors PupB and PupX, or the coprogen receptor

  14. Kinetic and Spectroscopic Studies of N694C Lipoxygenase: A Probe of the Substrate Activation Mechanism of a Non-Heme Ferric Enzyme

    PubMed Central

    Neidig, Michael L.; Wecksler, Aaron T.; Schenk, Gerhard; Holman, Theodore R.; Solomon, Edward I.

    2010-01-01

    Lipoxygenases (LOs) comprise a class of substrate activating mononuclear non-heme iron enzymes which catalyze the hydroperoxidation of unsaturated fatty acids. A commonly proposed mechanism for LO catalysis involves H-atom abstraction by an FeIII-OH- site, best described as a proton coupled electron transfer (PCET) process, followed by direct reaction of O2 with the resulting substrate radical to yield product. An alternative mechanism that has also been discussed involves the abstraction of a proton from the substrate by the FeIII-OH leading to a ?-organoiron intermediate, where the subsequent ? bond insertion of dioxygen into the C-Fe bond completes the reaction. H-atom abstraction is favored by a high Eo of the FeII/FeIII couple and high pKa of water bound to the ferrous state, while an organoiron mechanism would be favored by a low Eo (to keep the site oxidized) and a high pKa of water bound to the ferric state (to deprotonate the substrate). A first coordination sphere mutant of soybean LO (N694C) has been prepared and characterized by near-infrared circular dichroism (CD) and variable-temperature, variable-field (VTVH) magnetic circular dichroism (MCD) spectroscopies (FeII site), as well as UV/Vis absorption, UV/Vis CD and electron paramagnetic resonance (EPR) spectroscopies (FeIII site). These studies suggest that N694C has a lowered Eo of the FeII/FeIII couple and a raised pKa of water bound to the ferric site relative to WT sLO-1 which would favor the organoiron mechanism. However, the observation in N694C of a significant deuterium isotope effect, anaerobic reduction of iron by substrate and a substantial decrease in kcat (~3000-fold) support H-atom abstraction as the relevant substrate-activation mechanism in sLO-1. PMID:17523638

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

    PubMed

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

    2014-12-31

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

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

    PubMed

    King, G M; Garey, M A

    1999-10-01

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

  17. Availability to Rats of Iron in Ferric Hydroxide Polymers1-2

    Microsoft Academic Search

    Louise A. Berner; Dennis D. Miller; Darrell Vancampen

    ABSTRACT,Availability to rats of Fe in isolated ferric hydroxide,polymers,was assessed. Polymers were prepared,by hydrolyzing,an 59Fe-labeledferric nitrate solution with base (KHCO3). After isolation by gel filtration, the polymers were characterized by spectrophotometric, dialysis, and ultracentrifugation methods. In a split- plot design experiment, Fe-adequate (Hb 11.4-14.0 g\\/dl) or Fe-deficient (Hb 4.7-9.6 g\\/dl) male,Sprague-Dawley rats (10\\/treatment) were dosed by stomach,tube with one of

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

    SciTech Connect

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

    2007-09-01

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

  19. 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.

  20. Ferric citrate.

    PubMed

    Cada, Dennis J; Cong, Jasen; Baker, Danial E

    2015-02-01

    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

  1. Ferric carboxymaltose.

    PubMed

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

    2014-01-01

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

  2. Ferric Carboxymaltose

    PubMed Central

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

    2014-01-01

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

  3. Microanalysis of iron oxidation states in earth and planetary materials

    NASA Astrophysics Data System (ADS)

    Bajt, S.; Sutton, S. R.; Delaney, J. S.

    1995-02-01

    Initial studies have been made on quantifying Fe oxidation states in different iron-bearing minerals using K-edge XANES. The energy of a weak pre-edge peak in the XANES spectrum due to 1s-3d electron transition was used to quantify ferric/ferrous ratios with microprobe spatial resolution. The estimated accuracy of the technique was +/- 10% in terms of Fe3+/((Fe2+ + Fe3+)). The detection limit was ~ 100 ppm with a synchrotron beam of ~ 100 ?m in diameter. The pre-edge peak energy in well-characterized samples with known Fe oxidation states was found to be a linear function of the ferric/(ferrous) ratio. The technique was applied to altered magnetics (ideally Fe3O4), and various silicates and oxides from meteorites.

  4. 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.

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

    PubMed Central

    Gupta, Ajay

    2014-01-01

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

  6. [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 ?g x L(-1). The treatment system could supply 64 984 L As-safe drinking water (< 10 ?g L(-1)) using Fe 1.5 mg x L(-1). Toxicity characteristic leaching procedure (TCLP) demonstrated that the leachate As was 3.4 ?g 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. PMID:26031078

  7. Dissociation of a ferric maltol complex and its subsequent metabolism during absorption across the small intestine of the rat.

    PubMed Central

    Barrand, M. A.; Callingham, B. A.; Dobbin, P.; Hider, R. C.

    1991-01-01

    1. The fate and disposition of [59Fe]-ferric [3H]-maltol after intravenous administration were investigated in anaesthetized rats. Immediate dissociation of ferric iron from maltol took place in the circulation even with high doses of ferric maltol (containing 1 mg elemental iron). In plasma samples withdrawn within 1 min of injection and subjected to gel filtration, 59Fe eluted with the high molecular weight proteins whilst the tritium was associated with low molecular weight material. 2. The rates of elimination of 59Fe and of tritium from the plasma and their ultimate fate were very different. The half life for 59Fe in the plasma was around 70 min and 59Fe appeared mainly in the bone marrow and liver. There was an initial rapid exit of tritium from the plasma with a half life of around 12 min. This was followed either by a plateau or by a rise in tritium levels, involving entry of maltol metabolites into the circulation. These metabolites could be recovered in the urine. 3. Entry of 59Fe and of tritium into the blood plasma after intraduodenal administration of [59Fe]-ferric [3H]-maltol was also very different. At low doses of ferric maltol (containing 100 micrograms elemental iron), the tritium appeared in the plasma in highest amounts within seconds and then decreased whilst there was a slow rise in 59Fe levels. At higher doses of ferric maltol (containing 7 mg elemental iron), levels of 59Fe in the plasma were highest at 5 min and then fell whereas tritium levels rose steadily. Mucosal processing of 59Fe prevented further entry of iron at high dose into the circulation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1364845

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

    E-print Network

    Mommessin, Pierre Robert

    1950-01-01

    ". . Ch!. :?. Soc. , Ql, 35(1 (ig2o) PHOCEDI'HE Two stages could be distinguished in the proce- dure: the preparati . n of the arh-'drous ferric chloride and the condensation of benzene with 2-methyipropene. I, PHEPAHATIO!' OI' AH!D'DHOUS I'CHIC C...:!c chloride was sublimed into the flask and the side arm was sealed a, ca' culated amount of anhy- drous benzene wa "- introduces! t'. rough the tos of the con!e?scr (10) from the senar;tory i'u?s el (11). The ferric chloride-be?ze. ' e mixture was stir...

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

    E-print Network

    Mommessin, Pierre Robert

    1950-01-01

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

  10. Nanophase modification of concrete for Enhancement of microbial properties and durability: Present status and future scope

    Microsoft Academic Search

    D. Ramachandran; Vinita Vishwakarma; S. S Samal

    2011-01-01

    Concrete structures are widely used in civil engineering which a mixture of calcium oxides, hydroxides and carbonates with quartz minerals and water. It is alkaline in nature with pH range 11–13.Concrete normally used in construction has large variety in mix proportion as well as type of cementitious materials. The basic characteristics of concrete structures and materials can be altered by

  11. Metal tungstates at the ultimate two-dimensional limit: fabrication of a CuWO? 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. PMID:24617647

  12. Ultrafiltration evaluation with depleted uranium oxide

    SciTech Connect

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

    1998-03-01

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

  13. Decoupling photochemical Fe(II) oxidation from shallow-water BIF deposition

    E-print Network

    Konhauser, Kurt

    ­Paleoproterozoic banded iron formations (BIFs) are commonly taken to indicate the presence of biogenic O2 to the ferrous silicate mineral greenalite ((Fe)3Si2O5 (OH)4), and/or the ferrous carbonate, siderite (FeCO3(II) was exposed either to phototrophic Fe(II)-oxidizing bacteria or to O2, ferric hydroxide formed rapidly

  14. Surface complexation of arsenic(V) to iron(III) (hydr)oxides: structural mechanism from ab initio molecular geometries and EXAFS spectroscopy

    Microsoft Academic Search

    David M Sherman; Simon R Randall

    2003-01-01

    Arsenic(V), as the arsenate (AsO4)3? ion and its conjugate acids, is strongly sorbed to iron(III) oxides (?-Fe2O3), oxide hydroxides (?–,?–FeOOH) and poorly crystalline ferrihydrite (hydrous ferric oxide). The mechanism by which arsenate complexes with iron oxide hydroxide surfaces is not fully understood. There is clear evidence for inner sphere complexation but the nature of the surface complexes is controversial. Possible

  15. ADVANCED CHEMICAL OXIDATION OF 2,4,6 TRICHLOROPHENOL IN AQUEOUS PHASE BY FENTON'S REAGENT-PART II: EFFECTS OF VARIOUS REACTION PARAMETERS ON THE TREATMENT REACTION

    Microsoft Academic Search

    SOMNATH BASU; IRVINE W. WEI

    1998-01-01

    Part I of this paper examined the effects of the amounts of oxidant and catalyst on the rates and extents of oxidation of 2,4,6-Trichlorophenol (TCP), in aqueous phase, by Fenton's Reagent. In this part the effects of various reaction parameters, e.g. temperature, pH, oxidation state of catalyst (ferrous versus ferric), mode of addition of oxidant to the reactor (single batch

  16. Comparative Evaluation of Aluminum Sulfate and Ferric Sulfate-Induced Coagulations as Pretreatment of Microfiltration for Treatment of Surface Water

    PubMed Central

    Song, Yali; Dong, Bingzhi; Gao, Naiyun; Deng, Yang

    2015-01-01

    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. PMID:26075726

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

    E-print Network

    regions on Mars by Neutron Spectrometer on Mars Odyssey Orbiter. Citation: Wang, A., and Z. C. Ling (2011Ferric sulfates on Mars: A combined mission data analysis of salty soils at Gusev crater with high degree of hydration during the moderate obliquity period on Mars. Additionally, the sulfates

  18. A bipolar membrane combined with ferric iron reduction as an efficient cathode system in microbial fuel cells

    Microsoft Academic Search

    Annemiek ter Heijne; Hubertus V. M. Hamelers; Wilde de V; René A. Rozendal; Cees J. N. Buisman

    2006-01-01

    There is a need for alternative catalysts for oxygen reduction in the cathodic compartment of a microbial fuel cell (MFC). In this study, we show that a bipolar membrane combined with ferric iron reduction on a graphite electrode is an efficient cathode system in MFCs. A flat plate MFC with graphite felt electrodes, a volume of 1.2 L and a

  19. Regulation of Ferritin-Mediated Cytoplasmic Iron Storage by the Ferric Uptake Regulator Homolog (Fur) of Helicobacter pylori

    Microsoft Academic Search

    STEFAN BERESWILL; STEFAN GREINER; ARNOUD H. M. VAN VLIET; BARBARA WAIDNER; FRANK FASSBINDER; EMILE SCHILTZ; JOHANNES G. KUSTERS; MANFRED KIST

    2000-01-01

    Homologs of the ferric uptake regulator Fur and the iron storage protein ferritin play a central role in maintaining iron homeostasis in bacteria. The gastric pathogen Helicobacter pylori contains an iron-induced prokaryotic ferritin (Pfr) which has been shown to be involved in protection against metal toxicity and a Fur homolog which has not been functionally characterized in H. pylori. Analysis

  20. Effects of suspended particles on the rate of mass transfer to a rotating disk electrode. [Ferric cyanide

    Microsoft Academic Search

    Roha

    1981-01-01

    Limiting currents for the reduction of ferric cyanide at a rotating disk were determined in the presence of 0 to 40 percent by volume of spherical glass beads. Experiments were conducted with six different particle diameters, and with rotation speeds in the range of 387 to 270 rpm, usong both a 0.56 cm and a 1.41 cm radius disk electrode.

  1. An open-label, crossover study of a new phosphate-binding agent in haemodialysis patients: ferric citrate

    Microsoft Academic Search

    Wu-Chang Yang; Chwei-Shiun Yang; Chun-Chen Hou; Tsai-Hung Wu; Eric W. Young; Chen H. Hsu

    Background. Hyperphosphataemia contributes to sec- ondary hyperparathyroidism and renal osteodystrophy in patients with end-stage renal disease (ESRD). Calcium salts are widely employed to bind dietary phosphate (P) but they may promote positive net calcium balance and metastatic calcification. We recently reported that ferric compounds bind intestinal phosphate in studies of normal and azotemic rats. Methods. To extend this observation, we

  2. A critical review of the surface chemistry of acidic ferric sulphate dissolution of chalcopyrite with regards to hindered dissolution

    Microsoft Academic Search

    C. Klauber

    2008-01-01

    The present understanding of the surface chemistry of acidic ferric sulphate dissolution of chalcopyrite is critically reviewed with regard to hindered dissolution and how the hydrometallurgical limitations, especially for microbial heap leaching operations, might be overcome. In particular the surface science investigations of what surface phases might be responsible for hindered dissolution are reviewed. Some other mechanistic issues are also

  3. Relative importance of diffusion and reaction control during the bacterial and ferric sulphate leaching of zinc sulphide

    Microsoft Academic Search

    Gabriel da Silva

    2004-01-01

    A study has been undertaken on the bacterial and ferric sulphate leaching of sphalerite, with the aim of observing the relative importance of both diffusion and reaction control, across a range of operating conditions. To facilitate this kinetic analysis a mixed-control rate equation was developed based upon the shrinking particle and shrinking core models, featuring both an intrinsic rate of

  4. Facile preparation of ferric giniite hollow microspheres and their enhanced Fenton-like catalytic performance under visible-light irradiation.

    PubMed

    Zhang, Xuhong; Zhang, Yu; Gao, Lin; Yu, Haitao; Wei, Yu

    2015-08-15

    Ferric giniite hollow spheres with diameters of about 1.2-1.4?m were successfully fabricated with a one-pot hydrothermal process. All chemicals used were low-cost compounds and environmentally benign. The obtained products were characterized by field emission scanning electron microscope (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, Fourier-transform IR spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It was found that as-prepared ferric giniite hollow spheres exhibited much enhanced photocatalytic activity (99.5%) for the degradation of methylene blue in the presence of visible light irradiation and H2O2. Experimental results indicate that the existence of the carbonaceous shells enhances the photocatalytic activity of ferric giniite hollow spheres via the synergistic effect between carbon and ferric giniite, such as improving the adsorption, absorbing more light and exhibiting high activity to produce hydroxyl radicals through catalytic decomposition of H2O2. PMID:25910223

  5. 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

    2015-01-01

    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. PMID:26075726

  6. Degradation of ferric chelate of ethylenediaminetetraacetic acid by bacterium isolated from deep-sea stalked barnacle.

    PubMed

    Imada, Chiaki; Harada, Yohei; Kobayashi, Takeshi; Hamada-Sato, Naoko; Watanabe, Etsuo

    2005-01-01

    Twenty strains of marine bacteria that degrade ferric chelate of ethylenediaminetetraacetic acid (Fe-EDTA) were isolated from among 117 strains collected from a marine environment. Among them strain 02-N-2, which was isolated from stalked barnacle collected from the deep sea in the Indian Ocean, had the highest Fe-EDTA degradation ability and was selected for further study. The strain showed high Fe-EDTA degradation ability at different seawater concentrations. In addition, the intact cells of this strain had the ability to degrade such metal-EDTAs as Ca, Cu, and Mg. The strain was an aerobic, gram-variable, rod-shaped organism. The results of various taxonomic studies revealed that the strain had significant similarity to Bacillus jeotgali JCM 10885(T), which was isolated from a Korean traditional fermented seafood, Jeotgal. PMID:15747087

  7. 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)). PMID:25116055

  8. Role of Ferric Reductases in Iron Acquisition and Virulence in the Fungal Pathogen Cryptococcus neoformans

    PubMed Central

    Saikia, Sanjay; Oliveira, Debora; Hu, Guanggan

    2014-01-01

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

  9. Ferric carboxymaltose: A revolution in the treatment of postpartum anemia in Indian women

    PubMed Central

    Rathod, Setu; Samal, Sunil K; Mahapatra, Purna C; Samal, Sunita

    2015-01-01

    Objectives: The objective of the present study is to compare the safety and efficacy of ferric carboxymaltose (FCM), intravenous (IV) iron sucrose and oral iron in the treatment of post = partum anemia (PPA). Materials and Methods: A total of 366 women admitted to SCB Medical College, Cuttack between September 2010 and August 2012 suffering from PPA hemoglobin (Hb) <10 g/dL were randomly assigned to receive either oral iron or IV FCM or iron sucrose. FCM, IV iron sucrose, and oral iron were given as per the protocol. Changes in hemoglobin (Hb) and serum ferritin levels at 2 and 6 weeks after treatment were measured and analyzed using ANOVA. Adverse effects to drug administration were also recorded. Results: A statistically significant increase in Hb and serum ferritin level were observed in all three groups, but the increase in FCM group was significantly higher (P < 0.0001) than conventional iron sucrose and oral iron group. The mean increase in Hb after 2 weeks was 0.8, 2.4, and 3.2 g/dL and 2.1, 3.4, and 4.4 g/dL at 6 weeks in oral iron, iron sucrose and FCM groups, respectively. The mean increase in serum ferritin levels after 2 weeks was 2.5, 193.1, and 307.1 and 14.2, 64, and 106.7 ng/mL after 6 weeks in oral iron, iron sucrose and FCM groups, respectively. Adverse drug reactions were significantly less (P < 0.001) in FCM group when compared with other two groups. Conclusion: Ferric carboxymaltose elevates Hb level and restores iron stores faster than IV iron sucrose and oral iron, without any severe adverse reactions. There was better overall satisfaction reported by the patients who received FCM treatment. PMID:25664264

  10. 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

  11. Application of ferric sludge to immobilize leachable mercury in soils and concrete.

    PubMed

    Zhuang, J Ming; Walsh, T; Lam, T; Boulter, D

    2003-11-01

    A Hg-contaminated site in B.C. Province, Canada was caused by the previous operation of Hg-cell in chlor-alkali process for over 25 years. The soils and groundwater at the site are highly contaminated with mercury. An analysis of groundwater at the site has shown that most of the mercury is bonded with humic and fulvic acids (HFA) in colloidal form. The Hg-HFA colloids can be completely removed from the groundwater with ferric chloride treatment under optimized process conditions to form ferric sludge (FS), which is rendered non-leachable by standard TCLP (Toxicity Characteristic Leaching Procedure) test. The effluent discharged from a clarifier has achieved mercury levels of < 0.5 microkg l(-1). The studies of mercury adsorption characteristics of FS show it has low mercury leachability by TCLP, and great mercury adsorption capability. This feature is the basis for the application of FS to immobilization of leachable Hg-contaminants in solid wastes. Full-scale stabilization tests of Hg-contaminated soil have been carried out, and the time-based stability of the treated soil has been monitored by TCLP over a period of 60 days. All the results have shown a small variation in TCLP mercury levels within a range of 10-40 microg l(-1). Based on these results and with the approval of the B.C. Ministry of the Environment, 1850 tons of Hg-contaminated soils and 260 tons of Hg-contaminated concrete fines have been treated, stabilized with FS, and disposed in a non-hazardous waste disposal site. PMID:14733397

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

    PubMed

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

    2014-02-01

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

  13. Enargite oxidation: A review

    NASA Astrophysics Data System (ADS)

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

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Borisov, Alexander; Behrens, Harald; Holtz, Francois

    2013-12-01

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

  15. Iron Oxide Minerals in Atmospheric Dust and Source Sediments-Studies of Types and Properties to Assess Environmental Effects

    NASA Astrophysics Data System (ADS)

    Reynolds, R. L.; Goldstein, H. L.; Moskowitz, B. M.; Till, J. L.; Flagg, C.; Kokaly, R. F.; Munson, S.; Landry, C.; Lawrence, C. R.; Hiza, M. M.; D'Odorico, P.; Painter, T. H.

    2011-12-01

    Ferric oxide minerals in atmospheric dust can influence atmospheric temperatures, accelerate melting of snow and ice, stimulate marine phytoplankton productivity, and impact human health. Such effects vary depending on iron mineral type, size, surface area, and solubility. Generally, the presence of ferric oxides in dust is seen in the red, orange, or yellow hues of plumes that originate in North Africa, central and southwest Asia, South America, western North America, and Australia. Despite their global importance, these minerals in source sediments, atmospheric dust, and downwind aeolian deposits remain poorly described with respect to specific mineralogy, particle size and surface area, or presence in far-traveled aerosol compounds. The types and properties of iron minerals in atmospheric dust can be better understood using techniques of rock magnetism (measurements at 5-300 K), Mössbauer and high-resolution visible and near-infrared reflectance spectroscopy; chemical reactivity of iron oxide phases; and electron microscopy for observing directly the ferric oxide coatings and particles. These studies can elucidate the diverse environmental effects of iron oxides in dust and can help to identify dust-source areas. Dust-source sediments from the North American Great Basin and Colorado Plateau deserts and the Kalahari Desert, southern Africa, were used to compare average reflectance values with a magnetic parameter (hard isothermal remanent magnetization, HIRM) for ferric oxide abundance. Lower reflectance values correspond strongly with higher HIRM values, indicating that ferric oxides (hematite or goethite, or both) contribute to absorption of solar radiation in these sediments. Dust deposited to snow cover of the San Juan Mountains (Colorado) and Wasatch Mountains (Utah) was used to characterize dust composition compared with properties of sediments exposed in source-areas identified from satellite retrievals. Results from multiple methods indicate that nanohematite is the dominant ferric oxide in most dust-on-snow (DOS) samples (collected 2005-2010) from the San Juan Mountains and in many redbed-derived dust sources upwind in Colorado Plateau drylands. Goethite in some San Juan Mountain DOS is probably derived from source-area sediments from Cretaceous marine deposits. In contrast, goethite appears to be the dominant ferric oxide in Wasatch Mountains DOS collected in 2010. Goethite-bearing Late Pleistocene lake sediments in west-central Utah have been identified as the dominant dust sources for these DOS layers from satellite retrievals. The distinction between hematite and goethite is useful for modeling radiative forcing by dust in mountain snow and ice and in the atmosphere.

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

    PubMed

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

    1998-07-01

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

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Kyriacou, Andreas

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

  19. Spectral study of the interaction between 2-pyridinecarbaldehyde-p-phenyldihydrazone and ferric iron and its analytical application

    NASA Astrophysics Data System (ADS)

    Zhou, Quanying; Liu, Weizhou; Chang, Lin; Chen, Fang

    2012-06-01

    The synthesis and spectral characterization of a schiff base, 2-pyridinecarbaldehyde-p-phenylenedihydrazone (short for 2PC-PPH), were described. It was found that ferric ion (Fe3+) could selectively quench the fluorescence of 2PC-PPH, whereas many other metal ions, such as Mn2+, Zn2+, Cu2+, K+, Al3+, Ca2+, Ni2+, Co2+, Cr3+ and Fe2+, could not quench its fluorescence. Based on this, a sensitive method for ferric ion selective detection was established. Under the optimum conditions, the decreasing fluorescence intensity of 2PC-PPH is proportional to the concentration of Fe3+ within the range of 6.0 × 10-7-1.0 × 10-5 mol L-1. The detection limit (3?) for Fe3+ determination is 3.6 × 10-7 mol L-1. The proposed method was successfully applied to determine iron in tea and milk powder.

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

    SciTech Connect

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

    2011-11-15

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

  1. Effect of interface states associated with transitional nanophase precipitates in the enhancement of red emission from SrAl12O19:Pr3+ by Ti4+ incorporation

    NASA Astrophysics Data System (ADS)

    Nag, Abanti; Kutty, T. R. N.

    2005-01-01

    SrAl12O19:Pr3+, Ti4+ phosphor suitable for field emission displays is prepared by the wet chemical gel-carbonate method and the mechanism of enhancement in red photoluminescence (PL) intensity with Ti4+ therein has been investigated. The PL spectra of Pr3+ show both 1D2-3H4 and 3P0-3H6 emission in the red region with very weak intensity when excited at 355 nm. The emission intensity has increased by about 100 times at room temperature in the compositional range SrAl12-xTixO19+x/2:Pr3+, with 0.1?x?0.3 in comparison to Ti-free SrAl12O19:Pr3+. TEM investigations show the presence of exsolved nanophase of SrAl8Ti3O19, the precipitation of which is preceded by the presence of defect centers at the interfacial regions between the semicoherent transient phase and the parent SrAl12O19 matrix. The presence of transitional nanophase and the associated defects modify the excitation-emission process by way of formation of electronic sub-levels at lower energy (3.5 eV) than the band gap of SrAl12O19 (?7 eV) followed by non-resonance energy transfer to Pr3+ level, leading to magnetic-dipole related red emission with enhanced intensity. The PL intensity of Pr3+ decreases at high Ti4+ concentrations (x>0.3) due to higher extent of segregation of non-emissive SrAl8Ti3O19:Pr3+ phase.

  2. Absorption of dilute SO 2 gas stream with conversion to polymeric ferric sulfate for use in water treatment

    Microsoft Academic Search

    Aron D Butler; Maohong Fan; Robert C Brown; Adrienne T Cooper; J. H van Leeuwen; Shihwu Sung

    2004-01-01

    Use of sulfur dioxide (SO2) in the production of polymeric ferric sulfate (PFS) was investigated. PFS is a highly effective coagulant useful in treatment of drinking water and wastewater, and could serve as a value-added sink for sulfur removed during coal gas cleanup. SO2 was absorbed from a dilute gas stream by sparging it into a bench-scale reactor containing a

  3. Production of a Poly-ferric Sulphate Chemical Coagulant by Selective Precipitation of Iron from Acidic Coal Mine Drainage

    Microsoft Academic Search

    J. C. S. S. Menezes; R. A. Silva; I. S. Arce; I. A. H. Schneider

    2009-01-01

    The aim of this work was to produce a ferric sulphate rich solution from acidic coal mine drainage that could be used as coagulant.\\u000a Precipitating the iron at pH 3.8, followed by dissolution in sulphuric acid, produced a coagulant consisting of 12.4% iron\\u000a and 1.3% aluminium. Water treatment tests proved that this coagulant was as efficient as the coagulant chemicals conventionally

  4. Ferric and cupric reductase activities in the green alga Chlamydomonas reinhardtii : experiments using iron-limited chemostats

    Microsoft Academic Search

    Harold G. Weger

    1999-01-01

    .   Cells of the green alga Chlamydomonas reinhardtii Dangeard were grown in Fe-limited chemostat culture over a range of growth rates (0.15–1.5?d?1). Greater cell densities and culture chlorophyll levels were achieved using an excess of chelator [ethylenediamine di-(o-hydroxyphenylacetic acid)] relative to FeCl3 (80:1), compared to growth using a 1:1 chelator:FeCl3 ratio. The C. reinhardtii cells reduced extracellular ferric chelates, and

  5. Selective Separation of Arsenic(III) and (V) Ions with Ferric Complex of Chelating Ion-Exchange Resin

    Microsoft Academic Search

    Isao Yoshida; Keihei Ueno; Hiroshi Kobayashi

    1978-01-01

    Trace levels of aqueous arsenic(III) and (V) ions were adsorbed selectively onto the ferric complex of a chelating resin, Uniselec UR-10. The adsorption was markedly dependent upon the pH of the aqueous phase. The distribution ratio and the specific adsorption capacity of arsenic(III) were 23,000 and 0.47 mmole\\/g, respectively, at the optimum pH for the adsorption, 9.2. The corresponding values

  6. The fate of Microcystis aeruginosa cells during the ferric chloride coagulation and flocs storage processes.

    PubMed

    Li, Xiuqing; Pei, Haiyan; Hu, Wenrong; Meng, Panpan; Sun, Feng; Ma, Guixia; Xu, Xiangchao; Li, Yuezhong

    2015-04-01

    Microcystis blooms could cause severe problems for drinking water supplies with their associated microcystins (MCs). As the majority of MCs are retained inside the cells, the effective removal of the intact Microcystis cells to avoid the release of additional MCs plays an important role in drinking water treatment. This study evaluated the effect of ferric chloride (FeCl3) coagulation and the flocs storage process on the integrity of Microcystis aeruginosa cells and the intracellular MCs release (and possible degradation) in both processes. Multiple analysis techniques including scanning electron microscopy and chlorophyll fluorescence were used to assess the integrity of M. aeruginosa. In the coagulation process, the coagulant dosage and mechanical actions caused no cell damage, and all the cells remained intact. Furthermore, 100?mg/L FeCl3 was effective in removing the extracellular MCs. In the flocs storage process, a number of intracellular MCs were released into the supernatant, but the cells remained viable up to 10?d. PMID:25241771

  7. 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. PMID:24124499

  8. CORRELATION BETWEEN THE OPTICAL AND MAGNETIC PROPERTIES OF FERRIC N-ACETYLATED HEME OCTAPEPTIDE COMPLEXES

    SciTech Connect

    Yang, E.K.; Sauer, K.

    1980-05-01

    The room temperature magnetic susceptibility of the complexes of the ferric N-acetylated heme octapeptide (N-H8PT) from horse heart cytochrome c is known to be generally consistent with the absorption and magnetic circular dichroism (MCD) spectra of these complexes. However, the N-acetylated methionine complex of the N-H8PT, which has axial coordination identical to that of the parent molecule, is found to exhibit a thermal mixture of high spin (S=5/2) and low spin (S=1/2) states. The temperature dependence of the magnetic susceptibility of the N-acetylmethionine complex yields {Delta}H{sup 0} = -7.6kca1/mole and {Delta}S° = -25.9 e.u. for a high to low spin transition. The electron spin resonance (ESR) spectrum of the N-acetylmethionine complex indicates a low spin ground state, with g values at 1.51, 2.31, and 2.91, which are distinct from those of cytochrome c. The axial ({Delta}) and rhombic (V) distortion parameters of the {sup 2}T{sub 2g} state correspond to 2.96{lambda} and 1.94{lambda}, respectively, where {lambda} is the spin-orbit coupling constant. A model is proposed to account for the uniqueness of the N-acetylmethionine complex: a change in the Fe-S distance may play a role in regulating the redox properties of cytochrome c.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed Central

    Yildiz, Esma; Tosun, Gul

    2014-01-01

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

  11. Chemical reduction of odour in fresh sewage sludge in the presence of ferric hydroxide.

    PubMed

    Su, Lianghu; Zhao, Youcai

    2013-01-01

    To assess the potential of ferric hydroxide (FH) to reduce odour emission from dewatered sewage sludge with a moisture of approximately 86%, odour reduction was evaluated using an electronic nose and measurements of odorous compounds (hydrogen sulphide, ammonia and volatile fatty acids (VFAs)). The sulphur species including sulphate, acid-volatile sulphide (AVS), Cr(II)-reducible sulphide (CRS) and elemental sulphur (ES), were analysed by a modified cold diffusion sequential extraction method before and after anaerobic incubation. Within 32 days, 69.3, 83.8 and 88.6% of the odour (or 81.3, 93.7 and 97.5% of hydrogen sulphide) were eliminated, respectively, at the rates of 0.05, 0.10 and 0.25% (wt) of FH. The sulphur species analysis indicated that FeS, FeS2 and a small portion of S0 were formed by FH-sulphide reaction. This study also found that the relationship between odour and H2S concentrations could be well expressed by Steven's law. We believe that FH can be a cost-effective reagent for sludge odour control in sewage treatment processes. PMID:23530327

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

    PubMed Central

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

    2013-01-01

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

  13. 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

  14. Investigations of the low frequency modes of ferric cytochrome c using vibrational coherence spectroscopy.

    PubMed

    Karunakaran, Venugopal; Sun, Yuhan; Benabbas, Abdelkrim; Champion, Paul M

    2014-06-12

    Femtosecond vibrational coherence spectroscopy is used to investigate the low frequency vibrational dynamics of the electron transfer heme protein, cytochrome c (cyt c). The vibrational coherence spectra of ferric cyt c have been measured as a function of excitation wavelength within the Soret band. Vibrational coherence spectra obtained with excitation between 412 and 421 nm display a strong mode at ~44 cm(-1) that has been assigned to have a significant contribution from heme ruffling motion in the electronic ground state. This assignment is based partially on the presence of a large heme ruffling distortion in the normal coordinate structural decomposition (NSD) analysis of the X-ray crystal structures. When the excitation wavelength is moved into the ~421-435 nm region, the transient absorption increases along with the relative intensity of two modes near ~55 and 30 cm(-1). The intensity of the mode near 44 cm(-1) appears to minimize in this region and then recover (but with an opposite phase compared to the blue excitation) when the laser is tuned to 443 nm. These observations are consistent with the superposition of both ground and excited state coherence in the 421-435 nm region due to the excitation of a weak porphyrin-to-iron charge transfer (CT) state, which has a lifetime long enough to observe vibrational coherence. The mode near 55 cm(-1) is suggested to arise from ruffling in a transient CT state that has a less ruffled heme due to its iron d(6) configuration. PMID:24823442

  15. Mechanistic insights into metal ion activation and operator recognition by the ferric uptake regulator

    PubMed Central

    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

    2015-01-01

    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. PMID:26134419

  16. Energy distributions at the high-spin ferric sites in myoglobin crystals.

    PubMed Central

    Fiamingo, F G; Brill, A S; Hampton, D A; Thorkildsen, R

    1989-01-01

    The orientation and temperature dependence (4.2-2.5 K) of electron paramagnetic resonance (EPR) power saturation and spin-lattice relaxation rate, and the orientation dependence of signal linewidth, were measured in single crystals of the aquo complex of ferric sperm whale skeletal muscle myoglobin. The spin-packet linewidth was found to be temperature independent and to vary by a factor of seven within the heme plane. An analysis is presented which enables one to arrive at (a) hyperfine component line-widths and, from the in-plane angular variation of the latter, at (b) the widths of distributions in energy differences between low-lying electronic levels and (c) the angular spread in the in-plane principal g-directions. The values of the energy level distributions in crystals obtained from the measurements and analysis reported here are compared with those obtained by a different method for the same protein complex in frozen solution. The spread in the rhombic energy splitting is significantly greater in solution than in the crystal. PMID:2539208

  17. Mechanism of adsorption of ferric iron by extracellular polymeric substances (EPS) from a bacterium Acidiphilium sp.

    PubMed

    Tapia, J M; Muñoz, J A; González, F; Blázquez, M L; Ballester, A

    2011-01-01

    The aim of this study was to assess the sorption of Fe(III) by extracellular polymeric substances (EPS) of the Acidiphilium 3.2Sup(5) bacterium, which has promising properties for use in microbial fuel cells (MFC). The EPS of A. 3.2Sup(5) was extracted using EDTA. The sorption isotherms were determined using aliquots of purified EPS. The exosubstances loaded with metal were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction spectroscopy (XRD) and Fourier transform infrared spectroscopy (FTIR). The sorption uptake approaches to 536.1 +/- 26.6 mg Fe(III) (g EPS)(-1) at an initial ferric concentration of 2.0 g l(-1). The sorption of Fe(III) by EPS can be fitted to the Freundlich model. The sorption process produces hydrated iron (III) oxalate [Fe(OH)(C2O4) x 2H2O] by a reversible reaction (log K = 1.06 +/- 0.16), indicating that a shift in the sorption of the cation can be easily achieved. Know the magnitude and form of iron sorption by EPS in MFC can foresee the potential impact on the metabolism of iron-reducing and iron-oxidazing bacteria and, therefore, on the feasibility of the system. PMID:22335116

  18. Sites of Interaction between the FecA and FecR Signal Transduction Proteins of Ferric Citrate Transport in Escherichia coli K-12

    Microsoft Academic Search

    Sabine Enz; Heidi Brand; Claudia Orellana; Susanne Mahren; U. H. Stroeher; V. Braun

    2003-01-01

    Transcription of the fecABCDE ferric citrate transport genes of Escherichia coli K-12 is initiated by a signal- ing cascade from the cell surface into the cytoplasm. FecR receives the signal in the periplasm from the outer membrane protein FecA loaded with ferric citrate, transmits the signal across the cytoplasmic membrane, and converts FecI in the cytoplasm to an active sigma

  19. Effect of Sorbed Fe(II) on the Initial Reduction Kinetics of 6Line Ferrihydrite and Amorphous Ferric Phosphate by Shewanella putrefaciens

    Microsoft Academic Search

    Christelle Hyacinthe; Steeve Bonneville; Philippe Van Cappellen

    2008-01-01

    Incomplete utilization of reactive ferric iron minerals by dissimilatory iron-reducing bacteria has been ascribed to inhibition by adsorption of Fe to the mineral or bacterial surfaces. We tested this hypothesis by monitoring the reduction of 6-line ferrihydrite and amorphous ferric phosphate by Shewanella putrefaciens for up to 50 hours, at circumneutral pH and in the presence of excess electron donor.

  20. Synthesis of Fullerene-Fused Dioxanes/Dioxepanes: Ferric Perchlorate-Mediated One-Step Reaction of [60]Fullerene with Diols.

    PubMed

    Zhang, Xiao-Feng; Li, Fa-Bao; Wu, Jun; Shi, Ji-Long; Liu, Zhan; Liu, Li

    2015-06-19

    The facile one-step reaction of [60]fullerene with various diols in the presence of ferric perchlorate afforded a series of rare fullerene-fused dioxanes/dioxepanes. Nevertheless, the reaction of [60]fullerene with diethylene glycol, triethylene glycol, and tripropylene glycol promoted by ferric perchlorate unexpectedly generated fullerene-fused dioxanes instead of the anticipated fullerene-fused crown ethers. A plausible reaction mechanism is proposed to explain the formation of fullerene-fused dioxane/dioxepane products. PMID:25996442

  1. Ferric Maltol Is Effective in Correcting Iron Deficiency Anemia in Patients with Inflammatory Bowel Disease: Results from a Phase-3 Clinical Trial Program

    PubMed Central

    Ahmad, Tariq; Tulassay, Zsolt; Baumgart, Daniel C.; Bokemeyer, Bernd; Büning, Carsten; Howaldt, Stefanie; Stallmach, Andreas

    2014-01-01

    Background: Iron deficiency anemia (IDA) is frequently seen in inflammatory bowel disease. Traditionally, oral iron supplementation is linked to extensive gastrointestinal side effects and possible disease exacerbation. This multicenter phase-3 study tested the efficacy and safety of ferric maltol, a complex of ferric (Fe3+) iron with maltol (3-hydroxy-2-methyl-4-pyrone), as a novel oral iron therapy for IDA. Methods: Adult patients with quiescent or mild-to-moderate ulcerative colitis or Crohn's disease, mild-to-moderate IDA (9.5–12.0 g/dL and 9.5–13.0 g/dL in females and males, respectively), and documented failure on previous oral ferrous products received oral ferric maltol capsules (30 mg twice a day) or identical placebo for 12 weeks according to a randomized, double-blind, placebo-controlled study design. The primary efficacy endpoint was change in hemoglobin (Hb) from baseline to week 12. Safety and tolerability were assessed. Results: Of 329 patients screened, 128 received randomized therapy (64 ferric maltol-treated and 64 placebo-treated patients) and comprised the intent-to-treat efficacy analysis: 55 ferric maltol patients (86%) and 53 placebo patients (83%) completed the trial. Significant improvements in Hb were observed with ferric maltol versus placebo at weeks 4, 8, and 12: mean (SE) 1.04 (0.11) g/dL, 1.76 (0.15) g/dL, and 2.25 (0.19) g/dL, respectively (P < 0.0001 at all time-points; analysis of covariance). Hb was normalized in two-thirds of patients by week 12. The safety profile of ferric maltol was comparable with placebo, with no impact on inflammatory bowel disease severity. Conclusions: Ferric maltol provided rapid clinically meaningful improvements in Hb and showed a favorable safety profile, suggesting its possible use as an alternative to intravenous iron in IDA inflammatory bowel disease. PMID:25545376

  2. Surface complexation modeling of Co(II) adsorption on mixtures of hydrous ferric oxide, quartz and kaolinite

    Microsoft Academic Search

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

    2009-01-01

    Co sorption was measured as a function of pH, ionic strength (0.001–0.1M NaNO3) and sorbate\\/sorbent ratio on pure quartz, HFO and kaolinite and on binary and ternary mixtures of the three solids. Sorption data measured for the pure solids were used to derive internally-consistent diffuse layer surface complexation model (DLM) stability constants for Co sorption. Co sorption on HFO could

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  4. Synthesis of LiFePO 4\\/C cathode material from ferric oxide and organic lithium salts

    Microsoft Academic Search

    Zhongqi Shi; Ming Huang; Yongjian Huai; Ziji Lin; Kerun Yang; Xuebu Hu; Zhenghua Deng

    2011-01-01

    LiFePO4\\/C cathode material has been simply synthesized via a modified in situ solid-state reaction route using the raw materials of Fe2O3, NH4H2PO4, Li2C2O4 and lithium polyacrylate (PAALi). The sintering temperature of LiFePO4\\/C precursor is studied by thermo-gravimetric (TG)\\/differential thermal analysis (DTA). The physical properties of LiFePO4\\/C are then investigated through analysis using by X-ray diffraction (XRD), scanning electron microscopy (SEM),

  5. Enhanced photocatalytic activity of sprayed Au doped ferric oxide thin films for salicylic acid degradation in aqueous medium.

    PubMed

    Mahadik, M A; Shinde, S S; Kumbhar, S S; Pathan, H M; Rajpure, K Y; Bhosale, C H

    2015-01-01

    Various doping percentage of Au were successfully introduced into the Fe2O3 photocatalysts via a spray pyrolysis method different. The effect of Au doping on photoelectrochemical, structural, optical and morphological properties of these deposited thin films is studied. The PEC characterization shows that, the photocurrent increases gradually with increasing Au content initially up to 2at.% indicating the maximum values of short circuit current (Isc) and open circuit voltage (Voc) are (Isc=90?A and Voc=220.5mV) and then decreases after exceeding the optimal Au doping content. Therefore, the photocurrent of Au doped Fe2O3 photocatalysts can be adjusted by the Au content. Deposited films are polycrystalline with a rhombohedral crystal structure having (104) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform. The photocatalytic activities of the Fe2O3 and Au:Fe2O3 photocatalyst were evaluated by photoelectrocatalytic degradation of salicylic acid under sunlight irradiation. The results show that the Au:Fe2O3 thin film photocatalyst exhibited about 45% more degradation of pollutants than the pure Fe2O3. Thus, in Au doped Fe2O3 photocatalysts, the interaction between Au and Fe2O3 reduces the recombination of photogenerated charge carriers and improve the photocatalytic activity. PMID:25496876

  6. [Ethanol-induced influence on the structure and arsenate adsorption of resin-based nano-hydrated ferric oxide].

    PubMed

    Wan, Qi; Li, Xu-Chun; Pan, Bing-Cai

    2013-08-01

    Here the role of ethanol in the synthesis of a new nanocomposite (D201-HFO) was evaluated in terms of its structure variation and arsenate adsorption. Results indicated that the ethanol-induced procedure improved the dispersion of HFO inside the polymer host D201 and increased the HFO sorption capacities towards arsenate by 20%. Also, the ethanol-induced procedure resulted in the increase of pore size, pore volume, and specific surface area of D201-HFO by 52%, 65% and 28%, respectively. Nevertheless, ethanol rinsing did not affect the mechanical strength of D201-HFO and the crystal type of the immobilized HFO. Little effects of the ethanol process was observed on the pH and co-anion dependent adsorption of arsenate. Furthermore, the ethanol step posed insignificant influence on the fix-bed adsorption and the repeated use of the adsorbent. The results showed that the ethanol procedure exerted little influence on the sorption properties of D201-HFO from the viewpoint of practical application and thus, it could not be included. PMID:24191562

  7. Diagenetic crystallization and oxidation of siderite in red bed (Buntsandstein) sediments from the Central Iberian Chain, Spain

    NASA Astrophysics Data System (ADS)

    Stel, Harry

    2009-01-01

    Compactional deformation facilitated replacement of dolomite and calcite by siderite and its subsequent oxidation in carbonate cemented red beds of the Triassic Buntsandstein in the Iberian Chain. Locally, the sedimentary clasts were cemented by carbonate that was derived from dissolution of locally exposed dolomite in the basement. Microstructures indicate that during sedimentation of the rocks, oxidizing conditions prevailed in the sediments and the basement was reddened by impregnation of hematite. Reducing conditions prevailed during deformation of the sediments. Ferric iron was reduced to Fe 2+, that reacted with deformed dolomite and calcite cement to produce fine grained siderite. At a later stage, siderite crystallites were (partly) oxidized to form a secondary phase of brown ferric oxide (goethite). Locally, goethite transformed to fine grained hematite that caused secondary reddening of the sediments. The reactions are associated with a combined volume loss of the solid phases of c. 50% per reaction mol; this was accommodated by the formation of pores. Oxidation of siderite was associated with release of CO 2; localized dissolution took place of feldspar and concurrently growth of kaolinite occurred by acidifying condition during release of CO 2. The relation of redox reactions and deformation is comparable to those in red bed conglomerates in the region. Reductive dissolution occurred at sites of stress concentration, particularly at contact points of pebbles. Late stage precipitation of ferric oxides and pyrolusite took place at oxidizing conditions in association with uplift.

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

    NASA Technical Reports Server (NTRS)

    Farrand, William H.; Singer, Robert B.

    1991-01-01

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

  9. Solubility products of amorphous ferric arsenate and crystalline scorodite (FeAsO 4 · 2H 2O) and their application to arsenic behavior in buried mine tailings

    NASA Astrophysics Data System (ADS)

    Langmuir, Donald; Mahoney, John; Rowson, John

    2006-06-01

    Published solubility data for amorphous ferric arsenate and scorodite have been reevaluated using the geochemical code PHREEQC with a modified thermodynamic database for the arsenic species. Solubility product calculations have emphasized measurements obtained under conditions of congruent dissolution of ferric arsenate (pH < 3), and have taken into account ion activity coefficients, and ferric hydroxide, ferric sulfate, and ferric arsenate complexes which have association constants of 10 4.04 (FeH 2AsO 42+), 10 9.86 (FeHAsO 4+), and 10 18.9 (FeAsO 4). Derived solubility products of amorphous ferric arsenate and crystalline scorodite (as log Ksp) are -23.0 ± 0.3 and -25.83 ± 0.07, respectively, at 25 °C and 1 bar pressure. In an application of the solubility results, acid raffinate solutions (molar Fe/As = 3.6) from the JEB uranium mill at McClean Lake in northern Saskatchewan were neutralized with lime to pH 2-8. Poorly crystalline scorodite precipitated below pH 3, removing perhaps 98% of the As(V) from solution, with ferric oxyhydroxide (FO) phases precipitated starting between pH 2 and 3. Between pH 2.18 and 7.37, the apparent log Ksp of ferric arsenate decreased from -22.80 to -24.67, while that of FO (as Fe(OH) 3) increased from -39.49 to -33.5. Adsorption of As(V) by FO can also explain the decrease in the small amounts of As(V)(aq) that remain in solution above pH 2-3. The same general As(V) behavior is observed in the pore waters of neutralized tailings buried for 5 yr at depths of up to 32 m in the JEB tailings management facility (TMF), where arsenic in the pore water decreases to 1-2 mg/L with increasing age and depth. In the TMF, average apparent log Ksp values for ferric arsenate and ferric hydroxide are -25.74 ± 0.88 and -37.03 ± 0.58, respectively. In the laboratory tests and in the TMF, the increasing crystallinity of scorodite and the amorphous character of the coexisting FO phase increases the stability field of scorodite relative to that of the FO to near-neutral pH values. The kinetic inability of amorphous FO to crystallize probably results from the presence of high concentrations of sulfate and arsenate.

  10. Method for fluorination of uranium oxide

    DOEpatents

    Petit, George S. (Oak Ridge, TN)

    1987-01-01

    Highly pure uranium hexafluoride is made from uranium oxide and fluorine. The uranium oxide, which includes UO.sub.3, UO.sub.2, U.sub.3 O.sub.8 and mixtures thereof, is introduced together with a small amount of a fluorine-reactive substance, selected from alkali chlorides, silicon dioxide, silicic acid, ferric oxide, and bromine, into a constant volume reaction zone. Sufficient fluorine is charged into the zone at a temperature below approximately 0.degree. C. to provide an initial pressure of at least approximately 600 lbs/sq. in. at the ambient atmospheric temperature. The temperature is then allowed to rise in the reaction zone until reaction occurs.

  11. [Quantitative investigation on flocculation and destruction of poly-silicic-ferric (PSF) coagulant].

    PubMed

    Fu, Ying; Yu, Shui-Li; Yu, Yan-Zhen; Qiu, Li-Ping

    2008-01-01

    An inorganic polymer, poly-silicic-ferric (PSF) coagulant was prepared using water glass, FeSO4 x 7H2O and NaClO3 by copolymerization. A comparison of coagulation performance, distribution of residual flocs in finished water and influence of turbulent shear force on the flocs between PSF and polyferric aluminum (PFA) was explored by jar tests and particle counter approach. The results indicate that PSF has superior removal of COD at higher dose to PFA. Flocculating speed should not be much higher or lower when using PSF as coagulant in treating surface water, and excellent coagulation efficiency can be obtained by the close cooperation of flocculation speed with flocculation time, that is, higher flocculation speed should be consistent with shorter flocculation time. The PFA flocs are much easier destructed than PSF flocs when increasing the turbulent shear force, and the destructed PSF flocs tend to be more easily re-coupled than PFA flocs. From the order magnitude, the flocculation coefficient KA of PSF is from 10(-2) to 10(-3), in comparison with the destruction coefficient KB from 10(-7) to 10(-8). For particles whose size is smaller than 2 microm, KA of PSF is 4 order magnitude more than that of PFA, and KB of PSF is almost the same to that of PFA; while for the other particles, KA of PSF is 2 order magnitude more than that of PFA, and KB of PSF is almost ten times smaller than that of PFA. PMID:18441923

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

    PubMed Central

    Bijlsma, Jetta J. E.; Waidner, Barbara; Vliet, Arnoud H. M. van; Hughes, Nicky J.; Häg, Stephanie; Bereswill, Stefan; Kelly, David J.; Vandenbroucke-Grauls, Christina M. J. E.; Kist, Manfred; Kusters, Johannes G.

    2002-01-01

    The only known niche of the human pathogen Helicobacter pylori is the gastric mucosa, where large fluctuations of pH occur, indicating that the bacterial response and resistance to acid are important for successful colonization. One of the few regulatory proteins in the H. pylori genome is a homologue of the ferric uptake regulator (Fur). In most bacteria, the main function of Fur is the regulation of iron homeostasis. However, in Salmonella enterica serovar Typhimurium, Fur also plays an important role in acid resistance. In this study, we determined the role of the H. pylori Fur homologue in acid resistance. Isogenic fur mutants were generated in three H. pylori strains (1061, 26695, and NCTC 11638). At pH 7 there was no difference between the growth rates of mutants and the parent strains. Under acidic conditions, growth of the fur mutants was severely impaired. No differences were observed between the survival of the fur mutant and parent strain 1061 after acid shock. Addition of extra iron or removal of iron from the growth medium did not improve the growth of the fur mutant at acidic pH. This indicates that the phenotype of the fur mutant at low pH was not due to increased iron sensitivity. Transcription of fur was repressed in response to low pH. From this we conclude that Fur is involved in the growth at acidic pH of H. pylori; as such, it is the first regulatory protein implicated in the acid resistance of this important human pathogen. PMID:11796589

  13. Optimizing iron delivery in the management of anemia: patient considerations and the role of ferric carboxymaltose.

    PubMed

    Toblli, Jorge Eduardo; Angerosa, Margarita

    2014-01-01

    With the challenge of optimizing iron delivery, new intravenous (iv) iron-carbohydrate complexes have been developed in the last few years. A good example of these new compounds is ferric carboxymaltose (FCM), which has recently been approved by the US Food and Drug Administration for the treatment of iron deficiency anemia in adult patients who are intolerant to oral iron or present an unsatisfactory response to oral iron, and in adult patients with non-dialysis-dependent chronic kidney disease (NDD-CKD). FCM is a robust and stable complex similar to ferritin, which minimizes the release of labile iron during administration, allowing higher doses to be administered in a single application and with a favorable cost-effective rate. Cumulative information from randomized, controlled, multicenter trials on a diverse range of indications, including patients with chronic heart failure, postpartum anemia/abnormal uterine bleeding, inflammatory bowel disease, NDD-CKD, and those undergoing hemodialysis, supports the efficacy of FCM for iron replacement in patients with iron deficiency and iron-deficiency anemia. Furthermore, as FCM is a dextran-free iron-carbohydrate complex (which has a very low risk for hypersensitivity reactions) with a small proportion of the reported adverse effects in a large number of subjects who received FCM, it may be considered a safe drug. Therefore, FCM appears as an interesting option to apply high doses of iron as a single infusion in a few minutes in order to obtain the quick replacement of iron stores. The present review on FCM summarizes diverse aspects such as pharmacology characteristics and analyzes trials on the efficacy/safety of FCM versus oral iron and different iv iron compounds in multiple clinical scenarios. Additionally, the information on cost effectiveness and data on change in quality of life are also discussed. PMID:25525337

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

    PubMed

    Bregman, David B; Goodnough, Lawrence T

    2014-04-01

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

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

    PubMed Central

    Goodnough, Lawrence T.

    2014-01-01

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

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

    PubMed

    Zarzycki, Piotr; Kerisit, Sebastien; Rosso, Kevin

    2011-09-01

    The limitations of common theoretical and molecular computational approaches for predicting electron transfer quantities were assessed, using an archetypal bridged ferrous-ferric electron transfer system in aqueous solution. The basis set effect on the magnitude of the electronic coupling matrix element computed using the quasi-diabatic method was carefully examined, and it was found that the error related to a poor basis set could exceed the thermal energy at room temperature. A range of approaches to determining the external (solvent) reorganization energy were also investigated. Significant improvements from the Marcus continuum model can be obtained by including dipolar Born-Kirkwood-Onsager correction. In this regard, we also found that Klamt's Conductor-Like Screening Model (COSMO) yields estimations of the external reorganization energy similar to those obtained with explicit solvent molecular dynamics simulations if the fast-frequency modes are neglected, which makes it an attractive alternative to laborious umbrella sampling simulations. By using the COSMO model, we also confirm that a decrease in curvature of the potential energy surface is a manifestation of the dielectric saturation observed in the first solvation layer. The linearity of solvent response to the charge redistribution was assessed by analyzing the energy gap autocorrelation function as well as the solvent density and dipole moment fluctuations. Molecular dynamics was also used to evaluate the sign and magnitude of the solvent reorganization entropy and to determine its effect on the predicted electron transfer rate. Finally, we present a simple way of estimating the vibration frequency along the reaction coordinate, which also enables prediction of the mass-dependent isotopic signature of electron transfer reactions. PMID:21696749

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

    SciTech Connect

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

    2011-07-29

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

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

    SciTech Connect

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

    2013-02-04

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

  19. Optimizing iron delivery in the management of anemia: patient considerations and the role of ferric carboxymaltose

    PubMed Central

    Toblli, Jorge Eduardo; Angerosa, Margarita

    2014-01-01

    With the challenge of optimizing iron delivery, new intravenous (iv) iron–carbohydrate complexes have been developed in the last few years. A good example of these new compounds is ferric carboxymaltose (FCM), which has recently been approved by the US Food and Drug Administration for the treatment of iron deficiency anemia in adult patients who are intolerant to oral iron or present an unsatisfactory response to oral iron, and in adult patients with non-dialysis-dependent chronic kidney disease (NDD-CKD). FCM is a robust and stable complex similar to ferritin, which minimizes the release of labile iron during administration, allowing higher doses to be administered in a single application and with a favorable cost-effective rate. Cumulative information from randomized, controlled, multicenter trials on a diverse range of indications, including patients with chronic heart failure, postpartum anemia/abnormal uterine bleeding, inflammatory bowel disease, NDD-CKD, and those undergoing hemodialysis, supports the efficacy of FCM for iron replacement in patients with iron deficiency and iron-deficiency anemia. Furthermore, as FCM is a dextran-free iron–carbohydrate complex (which has a very low risk for hypersensitivity reactions) with a small proportion of the reported adverse effects in a large number of subjects who received FCM, it may be considered a safe drug. Therefore, FCM appears as an interesting option to apply high doses of iron as a single infusion in a few minutes in order to obtain the quick replacement of iron stores. The present review on FCM summarizes diverse aspects such as pharmacology characteristics and analyzes trials on the efficacy/safety of FCM versus oral iron and different iv iron compounds in multiple clinical scenarios. Additionally, the information on cost effectiveness and data on change in quality of life are also discussed. PMID:25525337

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  2. Free radical scavenging capacity and inhibition of lipid oxidation of wines, grape juices and related polyphenolic constituents

    Microsoft Academic Search

    Concepción Sánchez-Moreno; José A. Larrauri; Fulgencio Saura-Calixto

    1999-01-01

    The antioxidant activity of grape juices, wines made from the same lot as juices and their major polyphenolic constituents was measured by the inhibition of lipid oxidation (ferric-thiocyanate) and free radical scavenging (2,2-diphenyl-1-picrylhydrazyl) methods. dl-?-Tocopherol and 3-tertiary-butyl-4-hydroxyanisole (BHA) were used as references. The inhibition of lipid oxidation of the standards followed the order: rutin = ferulic acid > tannic acid

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

    NASA Astrophysics Data System (ADS)

    Otsuka, Kazuhiko; Karato, Shun-ichiro

    2015-04-01

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

  4. Suppressive effects of Active Hexose Correlated Compound on the increased activity of hepatic and renal ornithine decarboxylase induced by oxidative stress

    Microsoft Academic Search

    She-Fang Ye; Kaoru Ichimura; Koji Wakame; Masato Ohe

    2003-01-01

    Active Hexose Correlated Compound (AHCC), an extract derived from fungi of Basidiomycetes family has been shown to act as a biological response modifier in various disorders. In our present study, ferric nitrilotriacetate (Fe-NTA), which generates hydroxyl radicals in vivo, was given intraperitoneally to rats and AHCC was tested for its ability to suppress oxidative stress and the activity of ornithine

  5. Surface signaling in transcriptional regulation of the ferric citrate transport system of Escherichia coli : mutational analysis of the alternative sigma factor FecI supports its essential role in fec transport gene transcription

    Microsoft Academic Search

    M. Ochs; A. Angerer; S. Enz; V. Braun

    1996-01-01

    Ferric citrate induces transcription of the ferric citrate transport genes (fec) inEscherichia coli by binding to the outer membrane receptor protein FecA without entering the cell. The signal elicited by ferric citrate crosses the outer membrane via TonB, ExbB, and ExbD. FecR transmits the signal across the cytoplasmic membrane and activates FecI located in the cytoplasm. FecI belongs to a

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

    PubMed Central

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

    2014-01-01

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

  7. Potentially Life-Threatening Phosphate Diabetes Induced by Ferric Carboxymaltose Injection: A Case Report and Review of the Literature

    PubMed Central

    Vandemergel, Xavier; Vandergheynst, Frédéric

    2014-01-01

    We report the case of a 45-year-old female patient who developed phosphate diabetes after administration of ferric carboxymaltose. Ten days after the second dose, she complained of intense fatigue and blood analysis showed a phosphate plasma level of 0.93?mg/dL with phosphate excretion rate of 23%. She received phosphate supplementation which resulted in phosphate clearance improvement which persisted for two months. We reviewed other cases described in the literature and would draw attention to this rare but potentially life-threatening side effect. PMID:25478250

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

    PubMed

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

    2014-11-01

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

  9. Exploring metal effects and synergistic interactions of ferric stimulation on azo-dye decolorization by new indigenous Acinetobacter guillouiae Ax-9 and Rahnella aquatilis DX2b.

    PubMed

    Ng, I-Son; Xu, Fangxin; Ye, Chiming; Chen, Bor-Yann; Lu, Yinghua

    2014-02-01

    The first-attempt study deciphered metal-interacting effects on dye-decolorizing capabilities of indigenous bioelectricity-generating strains, Acinetobacter guillouiae Ax-9 and Rahnella aquatilis DX2b. Most of the metallic ions were inhibitory to color removal capabilities of these strains. However, with supplementation of 5 mM ferric chloride, specific decolorization rate (SDR) of Ax-9 increased by 55.48% compared to Fe(3+)-free conditions. In contrast, SDR of DX2b decreased 75.35% due to the inhibition of ferric chloride. On the other hand, ferric citrate could stimulate SDR of DX2b for 21.5% at same dosage. Enzymatic assay indicated that Fe reductase activity was consistent with synergistic effects of ferric chloride on Ax-9, and ferric citrate on DX2b. Protein analysis via SDS-PAGE and identification of Tandem MS/MS afterwards showed that outer membrane protein (Omp) primarily deals with decolorization as a channeling regulation. Moreover, molecular modeling and bioinformatics data also provided detailed evidences to confirm the biological significance of Omp. PMID:23743733

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

    USGS Publications Warehouse

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

    2010-01-01

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

  11. [Analysis of reaction process between Si and Fe in poly-silicic-ferric sulfate (PSF) coagulant].

    PubMed

    Fu, Ying; Yu, Shui-Li; Yang, Yuan-Jing; Lu, Yan

    2007-03-01

    A new inorganic polymer coagulant, poly-silic-ferric sulfate (PSF) with various Si/Fe ratios (PSF0.5, PSF1 and PSF denote Si/Fe molar ratios of 0.5, 1 and 3, respectively), was prepared using water glass, ferrous sulfate and sodium chlorate by co-polymerization, and pH value was measured during the preparation process. The influence of both Si/Fe ratio and reaction time (polymerization time) on the complexation process (bonding mode) between Si and Fe was explored with many analytical methods (such as X-ray diffraction (XRD), ultraviolet/visible absorption (UVA) scanning, transmission electron microscope (TEM), photon correlation spectra (PCS) and infrared spectrum (IR) using PSF samples taken from different reaction time at different Si/Fe ratios. The results show that the characteristics of PSF are largely influenced by both reaction time and Si/Fe ratios. PSF is found to be a complexation compound of Si, Fe and many other ions, instead of a simple mixture of raw materials. The complexation process between Si and Fe may be different from various Si/Fe ratios, namely, the bonding rate, bonding mode and the stability of the bond between Si and Fe are different from various Si/Fe ratios: the polymer based on Si-O-Fe-O-Fe-O-Si bond may be formed at low Si/Fe ratio, in comparison with that based on Si-O-Fe-O-Si-O-Si bond at high Si/Fe ratio; the formation rate of Fe-O-Fe bond is rapid and there may be a mutual acceleration between Fe-O-Fe bond and Si-O-Fe bond, while the formation rate of Si-O-Si is slow and maybe there is a mutual retardation between Si-O-Fe bond and Si-O-Si bond; the stability of Fe-O-Fe bond is weaker than that of Si-O-Fe or Si-O-Si bond. PMID:17633635

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

    PubMed Central

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

    2009-01-01

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

  13. The Reduction of Aqueous Metal Species on the Surfaces of Fe(II)-Containing Oxides: The Role of Surface Passivation

    USGS Publications Warehouse

    White, A.F.; Peterson, M.L.

    1998-01-01

    The reduction of aqueous transition metal species at the surfaces of Fe(II)- containing oxides has important ramifications in predicting the transport behavior in ground water aquifers. Experimental studies using mineral suspensions and electrodes demonstrate that structural Fe(II) heterogeneously reduces aqueous ferric, cupric, vanadate and chromate ions on magnetite and ilmenite surfaces. The rates of metal reduction on natural oxides is strongly dependent on the extent of surface passivation and redox conditions in the weathering environment. Synchrotron studies show that surface oxidation of Fe(II)-containing oxide minerals decreases their capacity for Cr(VI) reduction at hazardous waste disposal sites.

  14. [Removal of arsenic (II) by ferrate oxidation-coagulation from drinking water].

    PubMed

    Yuan, Bao-ling; Li, Kun-lin; Deng, Lin-li; Zhang, Zhi-dong

    2006-02-01

    Ferrate is multi-function agent in water treatment and shows great oxidizing ability and excellent purifying effect. This experiment evaluated the performance of ferrate for arsenic removal. Experimental results show that the best rate of ferrate and arsenic (III) is 15:1, the efficiency of As removal can be achieved 98%, and the residual concentration of As3 + is < 0.05 mg/L. The optimum pH is 5.5 to approximately 7.5. The oxidative and coagulation time is 10 min and 30 min respectively. The salinity and hardness did not interfere with removal arsenic. This method is easy, very effective comparing with ferric method and KMnO4-Ferric method. PMID:16686189

  15. Cloning and characterization of the iutA gene which encodes ferric aerobactin receptor from marine Vibrio species.

    PubMed

    Murakami, K; Fuse, H; Takimura, O; Inoue, H; Yamaoka, Y

    2000-01-01

    The iutA gene from marine Vibrio species SD004, which encoded a ferric aerobactin receptor for the uptake of iron(III), was cloned onto a multicopy plasmid, pUC 18, in Escherichia coli. Identification of the positive clone was achieved on the basis of its deferrization activity and was detected as a halo formation on the chrome azurol S (CAS)-containing selective plate. Nucleotide sequence analysis of the cloned DNA fragment revealed an open reading frame (ORF) which encoded a polypeptide of 706 amino acid residues, and the deduced molecular mass of this polypeptide was 77.906 kD. The amino acid sequence showed a 41% homology with that of the lutA protein from E. coli. The cloned gene was iutA, which encoded the ferric aerobactin receptor. Another incomplete ORF was found 100 bp upstream of the iutA gene, which was homologous (31 out of 49 amino acids) with the C-terminal region of the luc D protein of E. coli. It is suggested that aerobactin biosynthesis and the transport genes are located tandemly on the Vibrio chromosome and may form an aerobactin operon. PMID:10756518

  16. Unique properties of polyaniline in the presence of applied magnetic field and ferric chloride

    Microsoft Academic Search

    Shengqi Li; Chunxia Zhu; Li Tang; Jinqing Kan

    2010-01-01

    Fe-contained polyaniline (abbreviated as PANI–Fe) was prepared by chemical oxidation of aniline with ammonium peroxydisulfate oxidant in 0.5moldm?3 HCl and an adequate content of FeCl3·6H2O solution in the presence of an applied magnetic field at room temperature. The X-ray photoelectron spectroscopy (XPS) and UV–vis and FTIR spectra suggest that there is an interaction between FeCl3 and PANI chains, but PANI–Fe

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

    SciTech Connect

    Lins, Roberto D.; Devanathan, Ramaswami; Dupuis, Michel

    2011-03-03

    Solvated phenylated sulfonated poly ether ether ketone ketone (Ph-SPEEKK) membranes in the presence of hydronium ions were modeled by classical molecular dynamics simulations. The characterization of the nanophase structure and dynamics of such membranes was carried out as a function of the water content lambda, where lambda is the number of water molecules per sulfonate group, for lambda values of 3.5, 6, 11, 25, and 40. Analysis of pair correlation functions supports the experimental observation of membrane swelling upon hydration as well the increase in water and hydronium ion diffusion with increasing lambda. While the average number of hydrogen bonds between hydronium ions and sulfonate groups is dramatically affected by the hydration level, the average lifetime of the hydrogen bonds remains essentially constant. The membrane is found to be relatively rigid and its overall flexibility shows little dependence on water content. Compared to Nafion, water and ion diffusion coefficients are considerably smaller at lower hydration levels and room temperature. However, at higher lambda values of 25 and 40 these coefficients are comparable to those in Nafion at a lambda value of 16. This study also shows that water diffusion in Ph-SPEEKK membranes at low hydration levels can be significantly improved by raising the temperature with important implications for proton conductivity.

  18. Influence of microstructure on the corrosion resistance of AISI type 304L and type 316L sintered stainless steels exposed to ferric chloride solution

    SciTech Connect

    Otero, E.; Pardo, A.; Utrilla, M.V.; Perez, F.J. [Univ. Complutense, Madrid (Spain). Dept. of Materials Sciences] [Univ. Complutense, Madrid (Spain). Dept. of Materials Sciences; Saenz, E. [Pontificia Univ. Catolica del Peru, Lima (Peru). Corrosion Lab.] [Pontificia Univ. Catolica del Peru, Lima (Peru). Corrosion Lab.

    1995-10-01

    The corrosion behavior of type 304L and type 316L austenitic stainless steels, produced by powder metallurgy, when exposed to a ferric chloride solution was studied. The exposures were conducted according to ASTM G48-76, Method A. The influence of ferric chloride concentration and exposure temperature on the corrosion kinetics of these materials was evaluated. A mechanism is proposed to explain the associated morphology observed in the microstructures produced after exposure of these P/M alloys to the aggressive medium.

  19. A biocompatible approach to surface modification: Biodegradable polymer functionalized super-paramagnetic iron oxide nanoparticles

    Microsoft Academic Search

    Lin Sun; Chi Huang; Tao Gong; Shaobing Zhou

    2010-01-01

    In the study, Fe3O4 nanoparticles with a size range of 10–20nm were firstly prepared by the modified controlled chemical coprecipitation method from the solution of ferrous\\/ferric mixed salt-solution in alkaline medium. Then, the super-paramagnetic iron oxide nanoparticles were covalently modified by biodegradable polymers such as polyethylene glycol (PEG) and poly(ethylene glycol)-co-poly(d,l-lactide) (PELA). The size and its distribution of the nanoparticles

  20. Differential Behaviour of Cell Membranes towards Iron-Induced Oxidative Damage and the Effects of Melatonin

    Microsoft Academic Search

    P. L. Tang; M. F. Xu; Z. M. Qian

    1997-01-01

    The ability of melatonin to protect iron-induced lipid peroxidation was studied in various rat cell membranes. The concentration of cellular membrane malondialdehyde (MDA) was used as an index of induced oxidative membrane damage. Cell membranes from the brain, heart, kidney and liver of the male Sprague-Dawley rat were incubated with ferric ammonium citrate (20 ?g\\/ml iron) alone for 3 h

  1. Treatment of landfill leachate by ozone-based advanced oxidation processes

    Microsoft Academic Search

    Jerry J. Wu; Chih-Chao Wu; Hong-Wen Ma; Chia-Chi Chang

    2004-01-01

    In this study, laboratory experiments are conducted to compare the efficacy using several ozone-based advanced oxidation processes (AOPs), such as O3, O3\\/H2O2, and O3\\/UV, to treat landfill leachate. Raw leachate was initially coagulated by ferric chloride (FeCl3) at the experimental-determined optimal dosage of 900 mgl?1, and the ozone-based AOPs were subsequently applied. Results indicate that all AOPs would result in

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

    EPA Science Inventory

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

  3. Soluble ferric iron as an effective protective agent against UV radiation: Implications for early life

    NASA Astrophysics Data System (ADS)

    Gómez, Felipe; Aguilera, Angeles; Amils, Ricardo

    2007-11-01

    Some recent MER Rover Opportunity results on ancient sedimentary rocks from Mars describe sandstones originated from the chemical weathering of olivine basalts by acidic waters [Squyres, S.W., Knoll, A.H., 2005. Earth Planet. Sci. Lett. 240, 1-10]. The absence of protective components in early Mars atmosphere forced any possible primordial life forms to deal with high doses of UV radiation. A similar situation occurred on the primitive Earth during the development of early life in the Archean [Berkner, L.V., Marshall, L.C., 1965. J. Atmos. Sci. 22 (3), 225-261; Kasting, J.F., 1993. Science 259, 920-926]. It is known that some cellular and/or external components can shield organisms from damaging UV radiation or quench its toxic effects [Olson, J.M., Pierson, B.K., 1986. Photosynth. Res. 9, 251-259; García-Pichel, F., 1998. Origins Life Evol. B 28, 321-347; Cockell, C., Rettberg, P., Horneck, G., Scherer, K., Stokes, M.D., 2003. Polar Biol. 26, 62-69]. The effectiveness of iron minerals for UV protection has also been reported [Phoenix, V.R., Konhauser, K.O., Adams, D.G., Bottrell, S.H., 2001. Geology 29 (9), 823-826], but nothing is known about the effect of iron in solution. Here we demonstrate the protective effect of soluble ferric iron against UV radiation on acidophilic photosynthetic microorganisms. These results offer an interesting alternative means of protection for life on the surface of early Mars and Earth, especially in light of the geochemical conditions in which the sedimentary minerals, jarosite and goethite, recently reported by the MER missions, were formed [Squyres, S.W., Arvidson, R.E., Bell III, J.F., Brückner, J., Cabrol, N.A., Calvin, W., Carr, M.H., Christensen, P.R., Clark, B.C., Crumpler, L., Des Marais, D.J., d'Uston, C., Economou, T., Farmer, J., Farrand, W., Folkner, W., Golombek, M., Gorevan, S., Grant, J.A., Greeley, R., Grotzinger, J., Haskin, L., Herkenhoff, K.E., Hviid, S., Johnson, J., Klingelhöfer, G., Knoll, A.H., Landis, G., Lemmon, M., Li, R., Madsen, M.B., Malin, M.C., McLennan, S.M., McSween, H.Y., Ming, D.W., Moersch, J., Morris, R.V., Parker, T., Rice Jr., J.W., Richter, L., Rieder, R., Sims, M., Smith, M., Smith, P., Soderblom, L.A., Sullivan, R., Wänke, H., Wdowiak, T., Wolff, M., Yen, A., 2004. Science 306, 1698-1703; Klingelhöfer, G., Morris, R.V., Bernhardt, B., Schröder, C., Rodionov, D.S., de Souza Jr., P.A., Yen, A., Gellert, R., Evlanov, E.N., Zubkov, B., Foh, J., Bonnes, U., Kankeleit, E., Gütlich, P., Ming, D.W., Renz, F., Wdowiak, T., Squyres, S.W., Arvidson, R.E., 2004. Science 306, 1740-1745].

  4. Progress in the development and use of ferrate(VI) salt as an oxidant and coagulant for water and wastewater treatment

    Microsoft Academic Search

    Jia-Qian Jiang; Barry Lloyd

    2002-01-01

    This paper reviews the progress in preparing and using ferrate(VI) salt as an oxidant and coagulant for water and wastewater treatment. The literature revealed that due to its unique properties (viz. strong oxidizing potential and simultaneous generation of ferric coagulating species), ferrate(VI) salt can disinfect microorganisms, partially degrade and\\/or oxidise the organic and inorganic impurities, and remove suspended\\/colloidal particulate materials

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

    Microsoft Academic Search

    Thomas N. Mashapa; Johann D. Rademan; Matthys J. Janse van Vuuren

    2007-01-01

    The selective oxidation of hydrogen sulfide to elemental sulfur, using a commercial, precipitated silica promoted ferric oxide based catalyst, was investigated in laboratory and pilot-plant reactors. Low levels of hydrogen sulfide (1-3 vol%) can be readily removed, but a continuous slow decrease in catalyst activity was apparent. X-ray photoelectron spectroscopy showed that the loss of activity was due to the

  6. Influence of oxidizing or reducing agents on gastrointestinal absorption of U, Pu, Am, Cm and Pm by rats

    SciTech Connect

    Sullivan, M.F.; Ruemmler, P.S.; Ryan, J.L.; Buschbom, R.L.

    1986-02-01

    Absorption of 233U, 238Pu, 241Am, and 244Cm from the gastrointestinal (GI) tract was measured in rats, fed ad libitum or fasted, that were gavaged with solutions containing ferric iron, ferrous iron, iron powder, quinhydrone or ascorbic acid. Absorption and retention of all of these actinides was increased substantially by fasting and by the addition of mild oxidizing agents, ferric iron and quinhydrone. In contrast, absorption and retention were decreased to below the fasted level by all the reducing agents except ascorbic acid, which caused diarrhea and an increase in absorption. Absorption of the lanthanide element 147Pm from the intestine of fasted rats was also increased by ferric iron. Some of these actinide elements are polyvalent and are, in some cases, known to be absorbed from the GI tract more readily in their higher oxidation states. This suggested an oxidation-reduction mechanism for the effect of fasting and the action of the chemical agents used. However, the improbability that either 241Am(III) 244Cm(III) or 147Pm is converted to a different oxidation state under these conditions makes that mechanism unlikely. Other explanations are suggested.

  7. A comparison of various ion exchange resins for the removal of ferric ions from copper electrowinning electrolyte solutions part I: Electrolytes containing no other impurities

    Microsoft Academic Search

    Bethan McKevitt; David Dreisinger

    2009-01-01

    Column testing was performed on four commercially available ion exchange resins to evaluate their ability to remove ferric from a synthetic copper electrowinning electrolyte. Results from the loading test indicated that the sulphonated diphosphonic resin, Eichrom Diphonix, has significantly lower capacity than other resins tested. Stripping tests were performed using cuprous elution and showed that the aminophosphonic resin, LanXess Lewatit

  8. Breadboard wash water renovation system. [using ferric chloride and ion exchange resins to remove soap and dissolved salts

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A total wash water renovation system concept was developed for removing objectionable materials from spacecraft wash water in order to make the water reusable. The breadboard model system described provides for pretreatment with ferric chloride to remove soap by chemical precipitation, carbon adsorption to remove trace dissolved organics, and ion exchange for removal of dissolved salts. The entire system was put into continuous operation and carefully monitored to assess overall efficiency and equipment maintenance problems that could be expected in actual use. In addition, the capacity of the carbon adsorbers and the ion-exchange resin was calculated and taken into consideration in the final evaluation of the system adequacy. The product water produced was well within the Tentative Wash Water Standards with regard to total organic carbon, conductivity, urea content, sodium chloride content, color, odor, and clarity.

  9. Nitrogen doped carbon nanotubes with encapsulated ferric carbide as excellent electrocatalyst for oxygen reduction reaction in acid and alkaline media

    NASA Astrophysics Data System (ADS)

    Zhong, Guoyu; Wang, Hongjuan; Yu, Hao; Peng, Feng

    2015-07-01

    Nitrogen doped carbon nanotubes (NCNTs) with encapsulated Fe3C nanoparticles (Fe3C@NCNTs) are synthesized by a simple direct pyrolysis of melamine and ferric chloride. The characterization results reveal that Fe3C is mainly encapsulated in the interior of NCNTs and N species is mainly distributed on the outside surface of NCNTs. Iron and iron carbide catalyze the growth of NCNTs and are wrapped by carbon to form Fe3C@NCNTs. The as-prepared Fe3C@NCNTs catalyst exhibits superior oxygen reduction reaction (ORR) activity, excellent methanol tolerance and long-term stability in both acid and alkaline media. It is proven that the doped N is the main active site for ORR and the inner Fe3C with outside carbon form the synergetic active site to enhance ORR activity. The ORR mechanism of direct four electron transfer pathway is proved in acid and alkaline media.

  10. Spin-state crossover and hyperfine interactions of ferric iron in MgSiO$_3$ perovskite

    E-print Network

    Hsu, Han; Cococcioni, Matteo; Wentzcovitch, Renata M

    2011-01-01

    Using density functional theory plus Hubbard $U$ calculations, we show that the ground state of (Mg,Fe)(Si,Fe)O$_3$ perovskite, a major mineral phase in the Earth's lower mantle, has high-spin ferric iron ($S=5/2$) at both the dodecahedral (A) and octahedral (B) site. As the pressure increases, the B-site iron undergoes a spin-state crossover to the low-spin state ($S=1/2$), while the A-site iron remains in the high-spin state. Our calculation shows that the B-site spin-state crossover in the pressure range of 40-70 GPa is accompanied by a noticeable volume reduction and an increase in quadrupole splitting, consistent with recent X-ray diffraction and M\\"ossbauer spectroscopy measurements. The volume reduction leads to a significant softening in the bulk modulus, which suggests a possible source of seismic velocity anomalies in the lower mantle.

  11. Switching Patients with Non-Dialysis Chronic Kidney Disease from Oral Iron to Intravenous Ferric Carboxymaltose: Effects on Erythropoiesis-Stimulating Agent Requirements, Costs, Hemoglobin and Iron Status

    PubMed Central

    Toblli, Jorge Eduardo; Di Gennaro, Federico

    2015-01-01

    Background Patients with non-dialysis-dependent chronic kidney disease (ND-CKD) often receive an erythropoiesis-stimulating agent (ESA) and oral iron treatment. This study evaluated whether a switch from oral iron to intravenous ferric carboxymaltose can reduce ESA requirements and improve iron status and hemoglobin in patients with ND-CKD. Methods This prospective, single arm and single-center study included adult patients with ND-CKD (creatinine clearance ?40 mL/min), hemoglobin 11–12 g/dL and iron deficiency (ferritin <100 ?g/L or transferrin saturation <20%), who were regularly treated with oral iron and ESA during 6 months prior to inclusion. Study patients received an intravenous ferric carboxymaltose dose of 1,000 mg iron, followed by a 6-months ESA/ ferric carboxymaltose maintenance regimen (target: hemoglobin 12 g/dL, transferrin saturation >20%). Outcome measures were ESA dose requirements during the observation period after initial ferric carboxymaltose treatment (primary endpoint); number of hospitalizations and transfusions, renal function before and after ferric carboxymaltose administration, number of adverse reactions (secondary endpoints). Hemoglobin, mean corpuscular volume, ferritin and transferrin saturation were measured monthly from baseline until end of study. Creatinine clearance, proteinuria, C-reactive protein, aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase bimonthly from baseline until end of study. Results Thirty patients were enrolled (age 70.1±11.4 years; mean±SD). Mean ESA consumption was significantly reduced by 83.2±10.9% (from 41,839±3,668 IU/patient to 6,879±4,271 IU/patient; p<0.01). Hemoglobin increased by 0.7±0.3 g/dL, ferritin by 196.0±38.7 ?g/L and transferrin saturation by 5.3±2.9% (month 6 vs. baseline; all p<0.01). No ferric carboxymaltose-related adverse events were reported and no patient withdrew or required transfusions during the study. Conclusion Among patients with ND-CKD and stable normal or borderline hemoglobin, switching from oral iron to intravenous ferric carboxymaltose was associated with significant improvements in hematological and iron parameters and a significant reduction in ESA dose requirements in this single-center pilot study. Trial Registration ClinicalTrials.gov NCT02232906 PMID:25928811

  12. High-yield syntheses and reactivity studies of Fe10 "ferric wheels": structural, magnetic, and computational characterization of a star-shaped Fe8 complex.

    PubMed

    Stamatatos, Theocharis C; Christou, Alexander G; Mukherjee, Shreya; Poole, Katye M; Lampropoulos, Christos; Abboud, Khalil A; O'Brien, Ted A; Christou, George

    2008-10-01

    Convenient, high-yield routes have been developed to [Fe 10(OMe) 20(O 2CR) 10] ( 1) "ferric wheels" involving the alcoholysis of [Fe 3O(O 2CR) 6(H 2O) 3] (+) salts in MeOH in the presence of NEt 3. Reactivity studies have established [Fe 10(OMe) 20(O 2CMe) 10] ( 1a) to undergo clean carboxylate substitution with a variety of other RCO 2H groups to the corresponding [Fe 10(OMe) 20(O 2CR) 10] product. In contrast, the reaction with phenol causes a nuclearity change to give a smaller [Fe 8(OH) 4(OPh) 8(O 2CR) 12] ( 2) wheel. Similarly, reactions of [Fe 10(OMe) 20(O 2CR) 10] with the bidentate chelate ethylenediamine (en) cause a structural change to give either [Fe 8O 5(O 2CMe) 8(en) 8](ClO 4) 6 ( 3) or [Fe 2O(O 2CBu (t))(en) 4](NO 3) 3 ( 4), depending on conditions. Complex 3 possesses a "Christmas-star" Fe 8 topology comprising a central planar [Fe 4(mu 4-O)] (10+) square subunit edge-fused to four oxide-centered [Fe 3(mu 3-O)] (7+) triangular units. Variable-temperature, solid-state dc and ac magnetization studies on complexes 1a- 4 in the 5.0-300 K range established that all the complexes possess an S = 0 ground state. The magnetic susceptibility data for 4 were fit to the theoretical chi M versus T expression derived by the use of an isotropic Heisenberg spin Hamiltonian and the Van Vleck equation, and this revealed an antiferromagnetic exchange parameter with a value of J = -107.7(5) cm (-1). This value is consistent with that predicted by a previously published magnetostructural relationship. Theoretically computed values of the exchange constants in 3 were obtained with the ZILSH method, and the pattern of spin frustration within its core and the origin of its S = 0 ground state have been analyzed in detail. PMID:18698763

  13. Groundwater arsenic removal by coagulation using ferric(III) sulfate and polyferric sulfate: A comparative and mechanistic study.

    PubMed

    Cui, Jinli; Jing, Chuanyong; Che, Dongsheng; Zhang, Jianfeng; Duan, Shuxuan

    2015-06-01

    Elevated arsenic (As) in groundwater poses a great threat to human health. Coagulation using mono- and poly-Fe salts is becoming one of the most cost-effective processes for groundwater As removal. However, a limitation comes from insufficient understanding of the As removal mechanism from groundwater matrices in the coagulation process, which is critical for groundwater treatment and residual solid disposal. Here, we overcame this hurdle by utilizing microscopic techniques to explore molecular As surface complexes on the freshly formed Fe flocs and compared ferric(III) sulfate (FS) and polyferric sulfate (PFS) performance, and finally provided a practical solution in As-geogenic areas. FS and PFS exhibited a similar As removal efficiency in coagulation and coagulation/filtration in a two-bucket system using 5mg/L Ca(ClO)2. By using the two-bucket system combining coagulation and sand filtration, 500L of As-safe water (<10?g/L) was achieved during five treatment cycles by washing the sand layer after each cycle. Fe k-edge X-ray absorption near-edge structure (XANES) and As k-edge extended X-ray absorption fine structure (EXAFS) analysis of the solid residue indicated that As formed a bidentate binuclear complex on ferrihydrite, with no observation of scorodite or poorly-crystalline ferric arsenate. Such a stable surface complex is beneficial for As immobilization in the solid residue, as confirmed by the achievement of much lower leachate As (0.9?g/L-0.487mg/L) than the US EPA regulatory limit (5mg/L). Finally, PFS is superior to FS because of its lower dose, much lower solid residue, and lower cost for As-safe drinking water. PMID:26040730

  14. Induction of hepatic and renal metallothionein synthesis by ferric nitrilotriacetate in mice: the role of MT as an antioxidant

    SciTech Connect

    Min, Kyong-Son [Faculty of Nutrition, Kobe Gakuin University, Kobe, 651-2180 (Japan)]. E-mail: min@nutr.kobegakuin.ac.jp; Morishita, Fumio [Faculty of Nutrition, Kobe Gakuin University, Kobe, 651-2180 (Japan); Tetsuchikawahara, Noriko [Faculty of Nutrition, Kobe Gakuin University, Kobe, 651-2180 (Japan); Onosaka, Satomi [Faculty of Nutrition, Kobe Gakuin University, Kobe, 651-2180 (Japan)

    2005-04-01

    Metallothionein (MT) demonstrates strong antioxidant properties, yet the physiological relevance of its antioxidant action is not clear. Injection of mice with ferric nitrilotriacetate (Fe-NTA) caused a dose-dependent increase in hepatic and renal MT. Fe-NTA caused a greater increase in hepatic and renal MT concentration (2.5- and 4-fold) compared with FeCl{sub 3} at the same dose of ferric ion. MT mRNA levels were markedly elevated in both of tissues. Thiobarbituric acid (TBA) values in both tissues reached a maximum after 2-4 h. The MT concentrations were significantly increased after 2-4 h in liver and after 8-16 h in kidneys. Plasma concentrations of cytokines such as IL-6 and TNF{alpha} were elevated by 4 h; IL-6 levels were 24 times higher after Fe-NTA than that after injection of FeCl{sub 3}. Pretreatment of mice with ZnSO{sub 4} attenuated nephrotoxicity induced by Fe-NTA after 2 h, but was not effective 4 h after injection. After a Fe-NTA injection, a loss of Cd-binding properties of preinduced MT was observed only in kidneys of Zn-pretreated mice but not in liver. Treatment with BSO, glutathione (GSH) depletor, intensified a loss of its Cd-binding properties after a Fe-NTA injection. These results indicate that induction of MT synthesis may result from reactive oxygen species (ROS) generated by Fe-NTA, and MT may act in vivo as a complementary antioxidant.

  15. Physico-chemical properties of the new generation IV iron preparations ferumoxytol, iron isomaltoside 1000 and ferric carboxymaltose.

    PubMed

    Neiser, Susann; Rentsch, Daniel; Dippon, Urs; Kappler, Andreas; Weidler, Peter G; Göttlicher, Jörg; Steininger, Ralph; Wilhelm, Maria; Braitsch, Michaela; Funk, Felix; Philipp, Erik; Burckhardt, Susanna

    2015-08-01

    The advantage of the new generation IV iron preparations ferric carboxymaltose (FCM), ferumoxytol (FMX), and iron isomaltoside 1000 (IIM) is that they can be administered in relatively high doses in a short period of time. We investigated the physico-chemical properties of these preparations and compared them with those of the older preparations iron sucrose (IS), sodium ferric gluconate (SFG), and low molecular weight iron dextran (LMWID). Mössbauer spectroscopy, X-ray diffraction, and Fe K-edge X-ray absorption near edge structure spectroscopy indicated akaganeite structures (?-FeOOH) for the cores of FCM, IIM and IS, and a maghemite (?-Fe2O3) structure for that of FMX. Nuclear magnetic resonance studies confirmed the structure of the carbohydrate of FMX as a reduced, carboxymethylated, low molecular weight dextran, and that of IIM as a reduced Dextran 1000. Polarography yielded significantly different fingerprints of the investigated compounds. Reductive degradation kinetics of FMX was faster than that of FCM and IIM, which is in contrast to the high stability of FMX towards acid degradation. The labile iron content, i.e. the amount of iron that is only weakly bound in the polynuclear iron core, was assessed by a qualitative test that confirmed decreasing labile iron contents in the order SFG ? IS > LMWID ? FMX ? IIM ? FCM. The presented data are a step forward in the characterization of these non-biological complex drugs, which is a prerequisite to understand their cellular uptake mechanisms and the relationship between the structure and physiological safety as well as efficacy of these complexes. PMID:25801756

  16. The role of lipid hydroperoxides in the myoglobin-dependent oxidation of LDL.

    PubMed

    Hogg, N; Rice-Evans, C; Darley-Usmar, V; Wilson, M T; Paganga, G; Bourne, L

    1994-10-01

    It has previously been reported that mb in both the iron-oxo ferryl and the ferric oxidation states can promote lipid peroxidation and lead to oxidative modification of low-density lipoprotein. The mechanism of these oxidation reactions is unclear and could involve either lipid hydroperoxide-dependent or independent reactions. In order to ascertain which of the afore-mentioned mechanisms predominates, the effects of exogenous lipid hydroperoxides on the ability of Mb, in its various oxidation states, to oxidize low-density lipoprotein has been investigated. The results suggest that oxidation proceeds through a one-electron redox cycle between met and ferryl myoglobin and that the reactions of both redox forms are at least partially dependent on lipid hydroperoxides within the LDL particle. PMID:7944405

  17. The structural behavior of ferric and ferrous iron in aluminosilicate glass near meta-aluminosilicate joins

    NASA Astrophysics Data System (ADS)

    Mysen, Bjorn O.

    2006-05-01

    Iron-57 resonant absorption Mössbauer spectroscopy was used to describe the redox relations and structural roles of Fe 3+ and Fe 2+ in meta-aluminosilicate glasses. Melts were formed at 1500 °C in equilibrium with air and quenched to glass in liquid H 2O with quenching rates exceeding 200 °C/s. The aluminosilicate compositions were NaAlSi 2O 6, Ca 0.5AlSi 2O 6, and Mg 0.5AlSi 2O 6. Iron oxide was added in the form of Fe 2O 3, NaFeO 2, CaFe 2O 4, and MgFe 2O 4 with total iron oxide content in the range ˜0.9 to ˜5.6 mol% as Fe 2O 3. The Mössbauer spectra, which were deconvoluted by assuming Gaussian distributions of the hyperfine field, are consistent with one absorption doublet of Fe 2+ and one of Fe 3+. From the area ratios of the Fe 2+ and Fe 3+ absorption doublets, with corrections for differences in recoil-fractions of Fe 3+ and Fe 2+, the Fe 3+/?Fe is positively correlated with increasing total iron content and with decreasing ionization potential of the alkali and alkaline earth cation. There is a distribution of hyperfine parameters from the Mössbauer spectra of these glasses. The maximum in the isomer shift distribution function of Fe 3+, ?Fe 3+, ranges from about 0.25 to 0.49 mm/s (at 298 K relative to Fe metal) with the quadrupole splitting maximum, ?Fe 3+, ranging from ˜1.2 to ˜1.6 mm/s. Both ?Fe 3+ and ?Fe 2+ are negatively correlated with total iron oxide content and Fe 3+/?Fe. The dominant oxygen coordination number Fe 3+ changes from 4 to 6 with decreasing Fe 3+/?Fe. The distortion of the Fe 3+-O polyhedra of the quenched melts (glasses) decreases as the Fe 3+/?Fe increases. These polyhedra do, however, coexist with lesser proportions of polyhedra with different oxygen coordination numbers. The ?Fe 2+ and ?Fe 2+ distribution maxima at 298 K range from ˜0.95 to 1.15 mm/s and 1.9 to 2.0 mm/s, respectively, and decrease with increasing Fe 3+/?Fe. We suggest that these hyperfine parameter values for the most part are more consistent with Fe 2+ in a range of coordination states from 4- to 6-fold. The lower ?Fe 2+-values for the most oxidized melts are consistent with a larger proportion of Fe 2+ in 4-fold coordination compared with more reduced glasses and melts.

  18. Oxone/Co(2+) oxidation as an advanced oxidation process: comparison with traditional Fenton oxidation for treatment of landfill leachate.

    PubMed

    Sun, Jianhui; Li, Xiaoyan; Feng, Jinglan; Tian, Xiaoke

    2009-09-01

    In this paper, the application of Fenton and Oxone/Co(2+) oxidation processes for landfill leachate treatment was investigated. The removal of the chemical oxygen demand (COD), suspended substances (SS) and the color of the landfill leachate by Fenton oxidation to that by Oxone/Co(2+) oxidation were compared under optimal operational conditions. For Fenton oxidation process, the optimal conditions were determined as: [H(2)O(2)]=80 mmol L(-1), [H(2)O(2)]/[Fe(2+)]=2.0, initial pH=2.5, reaction temperature=37.5+/-1 degrees C, reaction time=160 min, number of stepwise addition=3. Under the given conditions, 56.9% of the COD removal efficiency was achieved, but the SS and the color of the treated landfill leachate increased due to the generation of a large quantity of ferric hydroxide sludge. In reference to Oxone/Co(2+) oxidation process, the optimal conditions were determined as: [Oxone]=4.5 mmol L(-1), [Oxone]/[Co(2+)]=10(4), pH=6.5, reaction temperature=30+/-1 degrees C, reaction time=300 min, number of stepwise addition=7, the COD, SS and the color removal efficiencies were 57.5, 53.3 and 83.3%, respectively. From this work, it can be concluded that Oxone/Co(2+) oxidation process demonstrated higher degradation efficiencies of the COD, SS and color for landfill leachate treatment than that by Fenton oxidation process. It also suggested that Oxone/Co(2+) oxidation process could be considered as one of the most promising technologies for practical applicability to treat landfill leachate in large scale. For further improving the efficiency of Oxone/Co(2+) oxidation process, we proposed that combination of it with other technologies in future such as ultraviolet, ultrasound and biological methods. PMID:19595430

  19. Treatment of biologically treated leachate by oxidation and coagulation.

    PubMed

    Zhang, H Y; Zhao, Y C; Qi, J Y

    2011-01-01

    This work aims to investigate removal efficiency of oxidation and coagulation/flocculation processes, to provide an effective method for the treatment of biologically pre-treated leachate. Leachate containing 985 mg L(-1) COD was treated by using three treatment schemes, i.e. oxidation, coagulation/flocculation and the combined process of coagulation/flocculation followed by oxidation. The application of single oxidation resulted in the effective removal of COD and color up to 80.4 and 83.2%, respectively. However, residual COD values lower than 200 mg L(-1) could only be achieved under intensive experimental conditions (high dosage of Ca(ClO)(2) and prolonged oxidation time). Coagulation/flocculation yielded residual COD values higher than 200 mg L(-1) even at the optimum coagulation conditions. The combined treatment by coagulation/flocculation followed by oxidation yielded final COD lower than 100 mg L(-1) at the following conditions: pre-coagulation with 250 mg L(-1) PFS (poly-ferric sulfate) and over 30-min post-oxidation, or pre-coagulation with 300 mg L(-1) PFS and over 20-min post-oxidation. Hence, pre-coagulation with PFS followed by oxidation with Ca(ClO)(2) was recommended for advanced treatment of biologically treated leachate. PMID:22179637

  20. Enhanced hydrogen oxidation activity and H2S tolerance of Ni-infiltrated ceria solid oxide fuel cell anodes

    NASA Astrophysics Data System (ADS)

    Mirfakhraei, Behzad; Paulson, Scott; Thangadurai, Venkataraman; Birss, Viola

    2013-12-01

    The effect of Ni infiltration into porous Gd-doped ceria (GDC) anodes on their H2 oxidation performance, with and without added 10 ppm H2S, is reported here. Porous GDC anodes (ca. 10 ?m thick) were deposited on yttria stabilized zirconia (YSZ) supports and then infiltrated with catalytic amounts of a Ni nitrate solution, followed by electrochemical testing in a 3-electrode half-cell setup at 500-800 °C. Infiltration of 3 wt.% Ni into the porous GDC anode lowered the polarization resistance by up to 85%, affecting mainly the low frequency impedance arc. When exposed to 10 ppm H2S, the Ni-infiltrated anodes exhibited a ca. 5 times higher tolerance toward sulfur poisoning compared to GDC anodes alone, also showing excellent long-term stability in 10 ppm H2S. In the presence of H2S, it is proposed that Ni, likely distributed as a nanophase, helps to maintain a clean GDC surface at the Ni/GDC interface at which the H2 oxidation reaction takes place. In turn, the GDC will readily supply oxygen anions to the adjacent Ni surfaces, thus helping to remove adsorbed sulfur.

  1. Prebiotic Oxidative Polymerization of 2,3 Dimercaptopropanol on the Surface of Iron(III) Hydroxide Oxide

    NASA Technical Reports Server (NTRS)

    Weber, Arthur L.

    1994-01-01

    The oxidation of 2,3-Dimercapto-1-propanol by ferric ions on the surface of iron (III) hydroxide oxide yielded polydisulfide polymers. This polymerization occured readily at low dithiol concentration under mild aqueous conditions. Polydisulfide polymers up to the 15-mer were synthesized from 1 mM dithiol in 5 ml water reacted with iron (III) hydroxide oxide (20 mg, 160 micro mole Fe) for 3 days under anaerobic conditions at 40 C and pH 4. About 91% of the dithiol was converted to short soluble oligomers and 9% to insoluble larger oligomers that were isolated with the mineral phase. Reactions at higher dithiol concentrations with the same ratio of dithiol to mineral gave a higher yield of the larger insoluble oligomers. The relationship of these results to prebiotic polymer synthesis will be discussed.

  2. Prebiotic polymerization: Oxidative polymerization of 2, 3-dimercapto-1-propanol on the surface of iron(III) hydroxide oxide

    NASA Technical Reports Server (NTRS)

    Weber, Arthur L.

    1995-01-01

    The oxidation of 2, 3-dimercapto-1-propanol by ferric ions on the surface of iron(III) hydroxide oxide (Fe(OH)O) yielded polydisulfide oligomers. This polymerization occurred readily at low dithiol concentration under mild aqueous conditions. Polydisulfide polymers up to the 15-mer were synthesized from 1 mM dithiol in 5 ml water reacted with iron(III) hydroxide oxide (20 mg, 160 micromole Fe) for 3 days under anaerobic conditions at 40 C and pH 4. About 91% of the dithiol was converted to short soluble oligomers and 9% to insoluble larger oligomers that were isolated with the Fe(OH)O phase. Reactions carried out at the same ratio of dithiol to Fe(OH)O but at higher dithiol concentrations gave higher yields of the larger insoluble oligomers. The relationship of these results to prebiotic polymer synthesis is discussed.

  3. Prebiotic Polymerization: Oxidative Polymerization of 2,3 Dimercapto-1- Propanol on the Surface of Iron(III) Hydroxide Oxide

    NASA Technical Reports Server (NTRS)

    Weber, Arthur L.

    1995-01-01

    The oxidation of 2,3-dimercapto-1-propanol by ferric ions on the surface of iron(III) hydroxide oxide (Fe(OH)O) yielded polydisulfide oligomers. This polymerization occurred readily at low dithiol concentration under mild aqueous conditions. Polydisulfide polymers up to the 15-mer were synthesized from 1 mM dithiol in 5 ml water reacted with iron(III) hydroxide oxide (20 mg, 160 micromole Fe) for 3 days under anaerobic conditions at 40 C and pH 4. About 91% of the dithiol was converted to short soluble oligomers and 9% to insoluble larger oligomers that were isolated with the FE(OH)O phase. Reactions carried out at the same ratio of dithiol to FE(OH)O but at higher dithiol concentrations gave higher yields of the larger insoluble oligomers. The relationship of these results to prebiotic polymer synthesis is discussed.

  4. Sampling the oxidative weathering products and the potentially acidic permafrost on Mars

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.

    1988-01-01

    Large areas of Mars' surface are covered by oxidative weathering products containing ferric and sulfate ions having analogies to terrestrial gossans derived from sulfide mineralization associated with iron-rich basalts. Chemical weathering of such massive and disseminated pyrrhotite-pentlandite assemblages and host basaltic rocks in the Martian environment could have produced metastable gossaniferous phases (limonite containing poorly crystalline hydrated ferric sulfates and oxyhydroxides, clay silicates and opal). Underlying groundwater, now permafrost on Mars, may still be acidic due to incomplete buffering reactions by wall-rock alteration of unfractured host rock. Such acidic solutions stabilize temperature-sensitive complex ions and sols which flocculate to colloidal precipitates at elevated temperatures. Sampling procedures of Martian regolith will need to be designed bearing in mind that the frozen permafrost may be corrosive and be stabilizing unique complex ions and sols of Fe, Al, Mg, Ni and other minor elements.

  5. Spectroscopic investigation of isonitrile complexes of ferric and ferrous microperoxidase 8.

    PubMed

    Ricoux, Rémy; Lecomte, Sophie; Policar, Clotilde; Boucher, Jean-Luc; Mahy, Jean-Pierre

    2005-05-01

    Microperoxidase 8 (MP8) is able to react with alkyl- and aryl-isonitriles (RNC) both in its reduced and oxidized states, to form MP8Fe(II)- and MP8Fe(III)-CNR complexes. The coordination and spin states of these complexes have been fully characterized by UV-visible and resonance Raman spectroscopies. Both MP8Fe(II)- and MP8Fe(III)-CNR complexes are hexacoordinate low-spin complexes, which bear a single RNC ligand on the distal face of the heme and keep the His 18 ligand on its proximal face, trans to the RNC ligand. A comparison of these characteristics with those of the Fe-CNR complexes of other hemoproteins suggests that both MP8Fe(II)- and MP8Fe(III)-CNR complexes present a Fe-C-N linear arrangement. This may be due to the lack of any interactions of the RNC ligand with the octapeptide of MP8 that is mainly located over the opposite face of the heme. Finally the formation of hexacoordinate low-spin MP8Fe(II)- and MP8Fe(III)-CNR complexes constitutes a new example of the reactivity of MP8 with a new class of weak sigma-donating and strong pi-accepting ligands, which adds to its already very rich coordination chemistry. PMID:15833340

  6. A modular continuous flow reactor system for the selective bio-oxidation of iron and precipitation of schwertmannite from mine-impacted waters.

    PubMed

    Hedrich, Sabrina; Johnson, D Barrie

    2012-02-01

    A novel modular bioremediation system which facilitates the selective removal of soluble iron from extremely acidic (pH ?2) metal-rich wastewaters by ferrous iron oxidation and selective precipitation of the ferric iron produced is described. In the first of the three modules, rapid ferrous iron oxidation was mediated by the recently-characterized iron-oxidizing autotrophic acidophile, "Ferrovum myxofaciens", which grew as long "streamers" within the reactor. Over 90% of the iron present in influent test liquors containing 280mg/L iron was oxidized at a dilution rate of 0.41h(-1), in a proton-consuming reaction. The ferric iron-rich solutions produced were pumped into a second reactor where controlled addition of sodium hydroxide caused the water pH to increase to 3.5 and ferric iron to precipitate as the mineral schwertmannite. Addition of a flocculating agent promoted rapid aggregation and settling of the fine-grain schwertmannite particles. A third passive module (a packed-bed bioreactor, also inoculated with "Fv. myxofaciens") acted as a polishing reactor, lowering soluble iron concentrations in the processed water to <1mg/L. The system was highly effective in selectively removing iron from a synthetic acidic (pH 2.1) mine water that contained soluble aluminum, copper, manganese and zinc in addition to iron. Schwertmannite was again produced, with little or no co-precipitation of other metals. PMID:22197072

  7. Zirconium doped nano-dispersed oxides of Fe, Al and Zn for destruction of warfare agents

    SciTech Connect

    Stengl, Vaclav, E-mail: stengl@uach.cz [Institute of Inorganic Chemistry AS CR v.v.i., 250 68 Rez (Czech Republic); Houskova, Vendula; Bakardjieva, Snejana; Murafa, Nataliya; Marikova, Monika [Institute of Inorganic Chemistry AS CR v.v.i., 250 68 Rez (Czech Republic); Oplustil, Frantisek; Nemec, Tomas [Military Technical Institute of Protection Brno, Veslarska 230, 628 00 Brno (Czech Republic)

    2010-11-15

    Zirconium doped nano dispersive oxides of Fe, Al and Zn were prepared by a homogeneous hydrolysis of the respective sulfate salts with urea in aqueous solutions. Synthesized metal oxide hydroxides were characterized using Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX). These oxides were taken for an experimental evaluation of their reactivity with sulfur mustard (HD or bis(2-chloroethyl)sulfide), soman (GD or (3,3'-Dimethylbutan-2-yl)-methylphosphonofluoridate) and VX agent (S-[2-(diisopropylamino)ethyl]-O-ethyl-methylphosphonothionate). The presence of Zr{sup 4+} dopant can increase both the surface area and the surface hydroxylation of the resulting doped oxides, decreases their crystallites' sizes thereby it may contribute in enabling the substrate adsorption at the oxide surface thus it can accelerate the rate of degradation of warfare agents. Addition of Zr{sup 4+} converts the product of the reaction of ferric sulphate with urea from ferrihydrite to goethite. We found out that doped oxo-hydroxides Zr-FeO(OH) - being prepared by a homogeneous hydrolysis of ferric and zirconium oxo-sulfates mixture in aqueous solutions - exhibit a comparatively higher degradation activity towards chemical warfare agents (CWAs). Degradation of soman or VX agent on Zr-doped FeO(OH) containing ca. 8.3 wt.% of zirconium proceeded to completion within 30 min.

  8. Formation of 4Hydroxy2-Nonenal-Modified Proteins in the Renal Proximal Tubules of Rats Treated with a Renal Carcinogen, Ferric Nitrilotriacetate

    Microsoft Academic Search

    Shinya Toyokuni; Koji Uchida; Keisei Okamoto; Yukari Hattori-Nakakuki; Hiroshi Hiai; Earl R. Stadtman

    1994-01-01

    An iron chelate, ferric nitrilotriacetate (Fe-NTA), induces proximal tubular necrosis, a consequence of lipid peroxidation, that finally leads to a high incidence of renal adenocarcinoma in rodents. Lipid peroxidation as monitored by formation of thiobarbituric acid-reactive substances and free 4-hydroxy-2-nonenal (HNE) was observed in the kidney homogenates of rats treated with Fe-NTA. Based on the fact that HNE is capable

  9. Effect of Immunoglobulin G from Cows Immunized with Ferric Citrate Receptor (FecA) on Iron Uptake by Escherichia coli1

    Microsoft Academic Search

    K. Takemura; J. S. Hogan; K. L. Smith

    2003-01-01

    The effects of immunoglobulin (Ig) G from cows immu- nized with the ferric citrate receptor (FecA) on iron up- take by Escherichia coli were investigated. Receptor FecA was purified from E. coli UT5600\\/pSV66. Cows were immunized with 400 µg purified FecA three times at 21 d intervals during late lactation and the nonlactat- ing period. Immunoglobulin G was purified by

  10. Mineralogy of Juventae Chasma: Sulfates in the light-toned mounds, mafic minerals in the bedrock, and hydrated silica and hydroxylated ferric sulfate on the plateau

    Microsoft Academic Search

    Janice L. Bishop; Mario Parente; Catherine M. Weitz; Eldar Z. Noe Dobrea; Leah H. Roach; Scott L. Murchie; Patrick C. McGuire; Nancy K. McKeown; Christopher M. Rossi; Adrian J. Brown; Wendy M. Calvin; Ralph Milliken; John F. Mustard

    2009-01-01

    Juventae Chasma contains four light-toned sulfate-bearing mounds (denoted here as A–D from west to east) inside the trough, mafic outcrops at the base of the mounds and in the wall rock, and light-toned layered deposits of opal and ferric sulfates on the plateau. Hyperspectral visible\\/near-infrared Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectra were used to identify monohydrated and polyhydrated

  11. Hepatic reduction of carbamoyl-PROXYL in ferric nitrilotriacetate induced iron overloaded mice: an in vivo ESR study.

    PubMed

    Morales, Noppawan Phumala; Yamaguchi, Yumiko; Murakami, Kimiyo; Kosem, Nuttavut; Utsumi, Hideo

    2012-01-01

    Reduction of a nitroxyl radical, carbamoyl-PROXYL in association of free radical production and hepatic glutathione (GSH) was investigated in iron overloaded mice using an in vivo L-band electron spin resonance (ESR) spectrometer. Significant increases in hepatic iron, lipid peroxidation and decrease in hepatic GSH were observed in mice intraperitoneally (i.p.) administrated with ferric nitrilotriacetate (Fe(III)-NTA, a total 45?µmol/mouse over a period of 3 weeks). Free radical production in iron overloaded mice was evidenced by significantly enhanced rate constant of ESR signal decay of carbamoyl-PROXYL, which was slightly reduced by treatment with iron chelator, deferoxamine. Moreover, the rate constant of ESR signal decay was negatively correlated with hepatic GSH level (r=-0.586, p<0.001). On the other hand, hepatic GSH-depletion (>80%) in mice through daily i.p. injection and drinking water supplementation of L-buthionine-[S,R]-sulfoximine (BSO) significantly retarded ESR signal decay, while there were no changes in serum aspartate aminotransferase and liver thiobarbituric acid-reactive substances levels. In conclusion, GSH plays two distinguish roles on ESR signal decay of carbamoyl-PROXYL, as an antioxidant and as a reducing agent, dependently on its concentration. Therefore, it should be taken into account in the interpretation of free radical production in each specific experimental setting. PMID:22791149

  12. Harmful algal bloom removal and eutrophic water remediation by commercial nontoxic polyamine-co-polymeric ferric sulfate-modified soils.

    PubMed

    Dai, Guofei; Zhong, Jiayou; Song, Lirong; Guo, Chunjing; Gan, Nanqin; Wu, Zhenbin

    2015-07-01

    Harmful algal bloom has posed great threat to drinking water safety worldwide. In this study, soils were combined with commercial nontoxic polyamine poly(epichlorohydrin-dimethylamine) (PN) and polymeric ferric sulfate (PFS) to obtain PN-PFS soils for Microcystis removal and eutrophic water remediation under static laboratory conditions. High pH and temperature in water could enhance the function of PN-PFS soil. Algal removal efficiency increased as soil particle size decreased or modified soil dose increased. Other pollutants or chemicals (such as C, P, and organic matter) in eutrophic water could participate and promote algal removal by PN-PFS soil; these pollutants were also flocculated. During PN-PFS soil application in blooming field samples, the removal efficiency of blooming Microcystis cells exceeded 99 %, the cyanotoxin microcystins reduced by 57 %. Water parameters (as TP, TN, SS, and SPC) decreased by about 90 %. CODMn, PO4-P, and NH4-N also sharply decreased by >45 %. DO and ORP in water improved. Netting and bridging effects through electrostatic attraction and complexation reaction could be the two key mechanisms of Microcystis flocculation and pollutant purification. Considering the low cost of PN-PFS soil and its nontoxic effect on the environment, we proposed that this soil combination could be applied to remove cyanobacterial bloom and remediate eutrophic water in fields. PMID:25752635

  13. Ferric-salicylaldehyde isonicotinoyl hydrazone, a synthetic iron chelate, alleviates defective iron utilization by reticulocytes of the Belgrade rat.

    PubMed

    Garrick, L M; Gniecko, K; Hoke, J E; al-Nakeeb, A; Ponka, P; Garrick, M D

    1991-03-01

    The Belgrade rat has a hypochromic, microcytic anemia inherited as an autosomal recessive mutation. Although transferrin binds normally to reticulocytes and internalizes normally, iron accumulation into cells and heme is much slower than normal. We have investigated the role of the transferrin cycle in this mutant by bypassing transferrin iron delivery with the iron chelate ferric salicylaldehyde isonicotinoyl hydrazone (Fe-SIH). Fe-SIH increases iron uptake into heme by Belgrade reticulocytes, restoring it almost to normal levels. This increase indicates that Fe-SIH delivers iron to a step in iron utilization that is after the Belgrade defect. Depleting reticulocytes of transferrin did not alter these observations. Failure to achieve above normal rates of iron incorporation could indicate damage due to chronic intracellular iron deficiency. Also, iron delivery by Fe-SIH restored globin synthesis to near-normal levels in Belgrade reticulocytes. The rates of glycine incorporation into porphyrin and heme in Belgrade reticulocytes incubated with Fe2-transferrin or Fe-SIH paralleled the rates of iron incorporation into heme. These data are consistent with the concept that iron availability limits protoporphyrin formation in rat reticulocytes. The protoporphyrin used for heme synthesis is provided by de novo synthesis and not by a pool of pre-existing protoporphyrin. The Belgrade defect occurs in the movement of iron from transferrin to a step prior to the ferrous state and insertion into heme. This defect diminishes the synthesis of heme and, consequently, that of protoporphyrin and globin. PMID:2022700

  14. Regulation of Ferritin-Mediated Cytoplasmic Iron Storage by the Ferric Uptake Regulator Homolog (Fur) of Helicobacter pylori

    PubMed Central

    Bereswill, Stefan; Greiner, Stefan; van Vliet, Arnoud H. M.; Waidner, Barbara; Fassbinder, Frank; Schiltz, Emile; Kusters, Johannes G.; Kist, Manfred

    2000-01-01

    Homologs of the ferric uptake regulator Fur and the iron storage protein ferritin play a central role in maintaining iron homeostasis in bacteria. The gastric pathogen Helicobacter pylori contains an iron-induced prokaryotic ferritin (Pfr) which has been shown to be involved in protection against metal toxicity and a Fur homolog which has not been functionally characterized in H. pylori. Analysis of an isogenic fur-negative mutant revealed that H. pylori Fur is required for metal-dependent regulation of ferritin. Iron starvation, as well as medium supplementation with nickel, zinc, copper, and manganese at nontoxic concentrations, repressed synthesis of ferritin in the wild-type strain but not in the H. pylori fur mutant. Fur-mediated regulation of ferritin synthesis occurs at the mRNA level. With respect to the regulation of ferritin expression, Fur behaves like a global metal-dependent repressor which is activated under iron-restricted conditions but also responds to different metals. Downregulation of ferritin expression by Fur might secure the availability of free iron in the cytoplasm, especially if iron is scarce or titrated out by other metals. PMID:11029412

  15. Direct Comparison of the Safety and Efficacy of Ferric Carboxymaltose versus Iron Dextran in Patients with Iron Deficiency Anemia.

    PubMed

    Hussain, Iftikhar; Bhoyroo, Jessica; Butcher, Angelia; Koch, Todd A; He, Andy; Bregman, David B

    2013-01-01

    Several intravenous iron complexes are available for the treatment of iron deficiency anemia (IDA). Iron dextran (DEX) is associated with an elevated risk of potentially serious anaphylactic reactions, whereas others must be administered in several small infusions to avoid labile iron reactions. Ferric carboxymaltose (FCM) is a nondextran intravenous iron which can be administered in high single doses. A randomized, open label, and multicenter comparison of FCM to DEX in adults with IDA and baseline hemoglobin of ?11.0?g/dL was conducted. A total of 160 patients were in the safety population (FCM n = 82; DEX n = 78). Adverse events, including immune system disorders (0% in FCM versus 10.3% in DEX, P = 0.003) and skin disorders (7.3% in FCM versus 24.4% in DEX, P = 0.004), were less frequently observed in the FCM group. A greater portion of patients in the FCM group experienced a transient, asymptomatic decrease in phosphate compared to patients in the DEX group (8.5% in FCM versus 0% in DEX, P = 0.014). In the FCM arm, the change in hemoglobin from baseline to the highest observed level was 2.8?g/dL, whereas the DEX arm displayed a change of 2.4?g/dL (P = 0.20). Treatment of IDA with FCM resulted in fewer hypersensitivity-related reactions than DEX. PMID:24069536

  16. Direct Comparison of the Safety and Efficacy of Ferric Carboxymaltose versus Iron Dextran in Patients with Iron Deficiency Anemia

    PubMed Central

    Bhoyroo, Jessica; Butcher, Angelia; Koch, Todd A.; Bregman, David B.

    2013-01-01

    Several intravenous iron complexes are available for the treatment of iron deficiency anemia (IDA). Iron dextran (DEX) is associated with an elevated risk of potentially serious anaphylactic reactions, whereas others must be administered in several small infusions to avoid labile iron reactions. Ferric carboxymaltose (FCM) is a nondextran intravenous iron which can be administered in high single doses. A randomized, open label, and multicenter comparison of FCM to DEX in adults with IDA and baseline hemoglobin of ?11.0?g/dL was conducted. A total of 160 patients were in the safety population (FCM n = 82; DEX n = 78). Adverse events, including immune system disorders (0% in FCM versus 10.3% in DEX, P = 0.003) and skin disorders (7.3% in FCM versus 24.4% in DEX, P = 0.004), were less frequently observed in the FCM group. A greater portion of patients in the FCM group experienced a transient, asymptomatic decrease in phosphate compared to patients in the DEX group (8.5% in FCM versus 0% in DEX, P = 0.014). In the FCM arm, the change in hemoglobin from baseline to the highest observed level was 2.8?g/dL, whereas the DEX arm displayed a change of 2.4?g/dL (P = 0.20). Treatment of IDA with FCM resulted in fewer hypersensitivity-related reactions than DEX. PMID:24069536

  17. Effect of ferric tartrate/sodium hydroxide solvent pretreatment on enzyme hydrolysis of cellulose in corn residue. [Trichoderma reesei

    SciTech Connect

    Hamilton, T.J.; Dale, B.E.; Ladisch, M.R.; Tsao, G.T.

    1984-01-01

    Lignocellulose containing 62% cellulose was prepared from corn residue by dilute acid hydrolysis using 5% H/sub 2/SO/sub 4/ at 90/sup 0/C. The lignocellulose was then treated with a cellulose solvent consisting of a ferric sodium tartrate complex in 1.5 N sodium hydroxide at levels ranging from 4:1 to 12:1 (solvent volume:corn residue lignocellulose) or a 1.5 N sodium hydroxide solution alone. Subsequent hydrolysis with cellulase enzymes from Trichoderma reesei gave cellulose conversions which were two to three times higher than untreated lignocellulose (30%) and approached 90% conversion after 24 h in the best cases. It was found that increasing cellulase enzyme levels from 3.74 IU/g lignocellulose to 7.71 IU/g lignocellulose increased cellulose conversion by 50% at all pretreatment conditions, while an increase from 7.71 to 10.1 IU/g gave only an additional 5-10% increase. Pretreatment with sodium hydroxide resulted in 5-25% lower conversions than observed for cellulose treated with the solvent, depending on enzyme levels and treatment levels. At high enzyme levels, sodium hydroxide pretreatment is almost as effective enhancing cellulose conversion after 24 h as is pretreatment using the cellulose solvent.

  18. The crystal structures of the ferric and ferrous forms of the heme complex of HmuO, a heme oxygenase of Corynebacterium diphtheriae.

    PubMed

    Hirotsu, Shoko; Chu, Grace C; Unno, Masaki; Lee, Dong-Sun; Yoshida, Tadashi; Park, Sam-Yong; Shiro, Yoshitsugu; Ikeda-Saito, Masao

    2004-03-19

    Crystal structures of the ferric and ferrous heme complexes of HmuO, a 24-kDa heme oxygenase of Corynebacterium diphtheriae, have been refined to 1.4 and 1.5 A resolution, respectively. The HmuO structures show that the heme group is closely sandwiched between the proximal and distal helices. The imidazole group of His-20 is the proximal heme ligand, which closely eclipses the beta- and delta-meso axis of the porphyrin ring. A long range hydrogen bonding network is present, connecting the iron-bound water ligand to the solvent water molecule. This enables proton transfer from the solvent to the catalytic site, where the oxygen activation occurs. In comparison to the ferric complex, the proximal and distal helices move closer to the heme plane in the ferrous complex. Together with the kinked distal helix, this movement leaves only the alpha-meso carbon atom accessible to the iron-bound dioxygen. The heme pocket architecture is responsible for stabilization of the ferric hydroperoxo-active intermediate by preventing premature heterolytic O-O bond cleavage. This allows the enzyme to oxygenate selectively at the alpha-meso carbon in HmuO catalysis. PMID:14645223

  19. Ferric iron partitioning between plagioclase and silicate liquid: thermodynamics and petrological applications

    NASA Astrophysics Data System (ADS)

    Sugawara, Toru

    2001-06-01

    A series of Fe and Mg partition experiments between plagioclase and silicate liquid were performed in the system SiO2-Al2O3-Fe2O3-FeO-MgO-CaO-Na2O under oxygen fugacities from below the IW buffer up to that of air. A thermodynamic model of plagioclase solid solution for the (CaAl,NaSi,KSi)(Fe3+,Al3+)Si2O8-Ca(Fe2+,Mg)Si3O8 system is proposed and is calibrated by regression analysis based on new and previously reported experimental data of Fe and Mg partitioning between plagioclase and silicate liquid, and reported thermodynamic properties of end members, ternary feldspar and silicate liquid. Using the derived thermodynamic model, FeOt, MgO content and Mg/(Fet+Mg) in plagioclase can be predicted from liquid composition with standard deviations of +/-0.34 wt% (relative error =9%) and +/-0.08 wt% (14%) and +/-0.7 (8%) respectively. Calculated Fe3+-Al exchange chemical potentials of plagioclase, $? { Fe{ 3 + } ( {Al} ){ - 1} }{ Pl} agree with those calculated using reported thermodynamic models for multicomponent spinel, ? { Fe{ 3 + } ( {Al} ){ - 1} }{ Sp} and clinopyroxene, ? { Fe{ 3 + } ( {Al} ){ - 1} }{ Cpx} $ . The FeOt content of plagioclase coexisting with spinel or clinopyroxene is affected by Fe3+/(Fe3++Al) and Mg/(Fe+Mg) of spinel or clinopyroxene and temperature, while it is independent of the anorthite content of plagioclase. Three oxygen barometers based on the proposed model are investigated. Although the oxygen fugacities predicted by the plagioclase-liquid oxygen barometer are scattered, this study found that plagioclase-spinel-clinopyroxene-oxygen and plagioclase-olivine-oxygen equilibria can be used as practical oxygen barometers. As a petrological application, prediction of plagioclase composition and fO2 are carried out for the Upper Zone of the Skaergaard intrusion. The estimated oxygen fugacities are well below QFM buffer and consistent with the estimation of oxidization states in previous studies.

  20. Determination of the ferric iron (Fe3+) behaviour during MORB petrogenesis

    NASA Astrophysics Data System (ADS)

    Sorbadere, F.; Frost, D. J.; McCammon, C. A.

    2013-12-01

    The oxidation state of iron in MORB glasses is proposed to be directly related to the oxygen fugacity of the upper mantle from which it derives [e.g., 1]. Fe3+/?Fe ratios of MORB recently measured by Cottrell and Kelley [2, 3], show a very narrow range, from 0.15 to 0.18, with a global average of 0.16×0.01, which corresponds to a fO2 very close to the Fayalite-Magnetite-Quartz (FMQ) buffer. For comparison, oceanic island basalts which derive from lower degrees of melting than MORB display higher Fe3+/?Fe ratio, i.e., about 0.29 [4]. This is consistent with the Fe3+ behaving incompatibly during partial melting (i.e., from 0.1; [5] to 0.2; [6]). Hence, MORB Fe3+/?Fe ratios are expected to be essentially controlled by magmatic processes of partial melting and fractional crystallisation, similar to other incompatible elements. Correlations between Fe3+/?Fe ratios and indices of low pressure fractional crystallization have been recognized in global MORB [2], but are not systematic [7]. However, Fe3+/?Fe ratios do not vary with melt-fraction related parameters, such as the Na2O(8) [7, 2], reflecting a relatively constant oxygen fugacity (fO2). Studies of other redox sensitive elements such as V and Cr, which have variable valence states and partition coefficients as a function of fO2 [e.g., 6, 8] also seem to imply that mantle melting occurs over a relatively small range of fO2. The absence of a correlation between magmatic processes and the Fe3+/?Fe ratio of MORB implies that this ratio is controlled or even buffered by some processes. One possibility to account for this Fe3+/?Fe paradox might be a change in the Fe3+ partition coefficient as a function of the degree of peridotite melting [2]. The decrease in the Fe3+ content of the melt expected for increasing melt extraction would have to be off-set by a process that would make Fe3+ more incompatible at higher degrees of melting [2]. To determine the effect of P, T and fO2 on the Fe3+ partition coefficient between spinel and liquid during the partial melting of a MORB-mantle source, we have performed partial melting experiments of the peridotite MPY-90 [9] at 1.5 GPa, between 1320 and 1430°C (i.e., 2 and 20 % of melting respectively), over a range of fO2 varying from FMQ-2 to FMQ+2. Oxygen fugacity values were measured using an Ir-Fe alloy redox sensor. A first stage of melting experiments were performed using a microdike melt extraction technique developed by Laporte et al. [10], to determine the compositions of the melt and spinel. A second stage of experiments consists of a spinel layer surrounding by anhydrous glass layers, in a sandwich configuration. This technique allows the generation of large pools of melt easily analysable by Mössbauer spectroscopy. The resulting Fe3+/?Fe ratios of melt and spinel have been compared with those measured by electron energy loss spectroscopy using a transmission electron microscope. [1] Carmichael (1991), CMP 106, 129-141. [2] Cottrell and Kelley (2011), EPSL 305, 270-282. [3] Cottrell and Kelley (2013), Science 340, 1314-17. [4] Lecuyer and Ricard (1999), EPSL 165, 197-211. [5] Canil et al. (1994), EPSL 123, 205-220. [6] Mallmann and O'Neill (2009), J. Petrol. 50, 1765-94. [7] Bezos and Humler (2005), GCA 69, 711-725. [8] Canil et al. (2006), EPSL, 248, 106-117. [9] Falloon and Green (1987), Mineral. Petrol. 37, 181-219. [10] Laporte et al. (2004), CMP 146, 463-484.

  1. Rates of oxidative weathering on the surface of Mars

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.

    1992-01-01

    Implicit in the mnemonic 'MSATT' (Mars surface and atmosphere through time) is that rates of surface processes on Mars through time should be investigated, including studies of the kinetics and mechanism of oxidative weathering reactions occurring in the Martian regolith. Such measurements are described. Two major elements analyzed in the Viking Lander XRF experiment that are most vulnerable to atmospheric oxidation are iron and sulfur. Originally, they occurred as Fe(2+)-bearing silicate and sulfide minerals in basaltic rocks on the surface of Mars. However, chemical weathering reactions through time have produced ferric- and sulfate-bearing assemblages now visible in the Martian regolith. Such observations raise several question about: (1) when the oxidative weathering reactions took place on Mars; (2) whether or not the oxidized regolith is a fossilized remnant of past weathering processes; (3) deducting chemical interactions of the ancient Martian atmosphere with its surface from surviving phases; (4) possible weathering reactions still occurring in the frozen regolith; and (5) the kinetics and mechanism of past and present-day oxidative reactions on Mars. These questions may be addressed experimentally by studying reaction rates of dissolution and oxidation of basaltic minerals, and by identifying reaction products forming on the mineral surfaces. Results for the oxidation of pyrrhotite and dissolved ferrous iron are reported.

  2. The high temperature thermoelectric performances of Zr0.5Hf0.5Ni0.8Pd0.2Sn0.99Sb0.01 alloy with nanophase inclusions

    NASA Astrophysics Data System (ADS)

    Chen, L. D.; Huang, X. Y.; Zhou, M.; Shi, X.; Zhang, W. B.

    2006-03-01

    The Zr0.5Hf0.5Ni0.8Pd0.2Sn0.99Sb0.01/ZrO2 nanocomposites have been prepared by spark plasma sintering technique. The thermoelectric properties were measured in the temperature range of 300-900 K. Thermal conductivity for the nanocomposites is considerably reduced, because the nanophase scatters the thermal phonons which transport most of the heat in the ZrNiSn-based alloy. Seebeck coefficient for the nanocomposites is enhanced due to the potential barrier scattering. The dimensionless figure of merit ZT is improved, with ZT~0.75 at 800 K for the samples containing 9 vol % ZrO2 nanoinclusions. The results obtained suggest that considerable improvements in the thermoelectric figure of merit may be obtainable by inducing appropriate nanoinclusions into the matrix.

  3. Pseudopotentials for quantum Monte Carlo calculations of transition metal oxides

    NASA Astrophysics Data System (ADS)

    Krogel, Jaron; Santana, Juan; Kent, Paul; Reboredo, Fernando

    2015-03-01

    Quantum Monte Carlo calculations of transition metal oxides are partially limited by the availability of high quality pseudopotentials that are both accurate in QMC and compatible with major electronic structure codes, e.g. by not being overly hard in the standard planewave basis. Following insight gained from recent GW calculations, a set of neon core pseudopotentials with small cutoff radii have been created for the early transition metal elements Sc to Zn within the local density approximation of DFT. The pseudopotentials have been tested for energy consistency within QMC by calculating the first through fourth ionization potentials of the isolated transition metal (TM) atoms and the binding curve of each TM-O dimer. The vast majority of the ionization potentials fall within 0.3 eV of the experimental values, with exceptions occurring mainly for atoms with multiple unpaired d electrons where multireference effects are the strongest. The equilibrium bond lengths of the dimers are within 1% of experimental values and the binding energy errors are typically less than 0.3 eV. Given the uniform treatment of the core, the larger deviations occasionally observed may primarily reflect the limitations of a Slater-Jastrow trial wavefunction. This work is supported by the Materials Sciences & Engineering Division of the Office of Basic Energy Sciences, U.S. DOE. Research by PRCK was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

  4. Site-specific hypochlorous acid-induced oxidation of recombinant human myoglobin affects specific amino acid residues and the rate of cytochrome b5-mediated heme reduction.

    PubMed

    Szuchman-Sapir, Andrea J; Pattison, David I; Davies, Michael J; Witting, Paul K

    2010-01-01

    Myeloperoxidase catalyzes the reaction of chloride ions with H(2)O(2) to yield hypochlorous acid (HOCl), which can damage proteins. Human myoglobin (HMb) differs from other Mbs by the presence of a cysteine residue at position 110 (Cys110). This study has (i) compared wild-type and a Cys110Ala variant of HMb to assess the influence of Cys110 on HOCl-induced amino acid modification and (ii) determined whether HOCl oxidation of HMb affects the rate of ferric heme reduction by cytochrome b(5). For wild-type HMb (HOCl:Mb ratio of 5:1 mol:mol), Cys110 was preferentially oxidized to a homodimeric or cysteic acid product-sulfenic/sulfinic acids were not detected. At a HOCl:Mb ratio 10:1 mol:mol, methionine (Met) oxidation was detected, and this was enhanced in the Cys110Ala variant. Tryptophan (Trp) oxidation was detected only in the Cys110Ala variant at the highest HOCl dose tested, with oxidation susceptibility following the order Cys>Met>Trp. Tyrosine chlorination was evident only in reactions between HOCl and the Cys110Ala variant and at a longer incubation time (24 h), consistent with the formation via chlorine-transfer reactions from preformed chloramines. HOCl-mediated oxidation of wild-type HMb resulted in a dose-dependent decrease in the observed rate constant for ferric heme reduction (approx two-fold at HOCl:Mb of 10:1 mol:mol). These data indicate that Cys110 influences the oxidation of HMb by HOCl and that oxidation of Cys, Met, and Trp residues is associated with a decrease in the one-electron reduction of ferric HMb by other proteins; such heme-Fe(3+) reduction is critical to the maintenance of function as an oxygen storage protein in tissues. PMID:19800968

  5. Treatment of Iron Deficiency with or without Anaemia with Intravenous Ferric Carboxymaltose in Gynaecological Practices – A Non-Interventional Study

    PubMed Central

    Herfs, R.; Fleitmann, L.; Kocsis, I.

    2014-01-01

    In this multi-centre, prospective, non-interventional study, the effectiveness and tolerance of ferric carboxymaltose (ferinject®; FCM) was tested through use in standard gynaecological practice. In total, data from 273 patients was evaluated. 193 of these patients displayed iron deficiency anaemia (IDA), and 68 had iron deficiency without anaemia (ID). The reasons for the ID/IDA were hypermenorrhoea (HyM) (n?=?170), post-partum condition (PP) (n?=?53) or another indication (n?=?53). The average age of the patients was 40 years old, with 8?% of them being vegetarians. Half of the patients had already been treated for anaemia, primarily with oral iron products (94?%). The primary, serious accompanying symptoms of anaemia were fatigue (72?%), lack of concentration (42?%), pale mucous membranes (42?%), headache (26?%) and sleep disorders (21?%). Only one patient did not show serious symptoms at the start of the study. The most frequent indications for parenteral therapy were the need for rapid iron substitution to reduce symptoms (>?70?%), followed by the lower effectiveness or intolerance of oral products (42?% each) as well as patients not completing the course of treatment with oral products (12?%). Patient information was collected at both the beginning and the end of the observation period, which lasted 15 weeks on average. FCM was most frequently administered via infusion (92?%; average infusion duration 21 minutes). Seven percent of patients received bolus injections. The average total iron dosage per patient was 788.7?mg (median 550?mg; range: 50–3000?mg); the median individual dosage was 500?mg (range: 50–1000?mg). The total dosage was, in most cases, administered through a single application (range: 1–10). Symptoms, blood values (Hb), iron stores (serum-ferritin [S-ferritin]) and transport iron (transferrin saturation [TSAT]) normalised to a large extent. In all subgroups, 92?% of women displayed a marked improvement in all of their symptoms. The average increase in Hb-value in the group as a whole was statistically significant, increasing from 10.5 to 13.0?g/dl. In the group with anaemia, the value increased from 9.9 to 13.3?g/dl, with 80?% of women reaching normal Hb-values. The average S-ferritin value increased by a statistically significant >?70?µg/L from 17.2 to 88.8?µg/l and the value for the TSAT increased from 16.3?% to 22.8?%. Seven patients reported experiencing side effects. None of the results were severe. Overall, as part of this non-interventional study for everyday routine in a gynaecological practice, a rapid improvement in symptoms accompanied by the rectification of iron deficiency and anaemia was shown with low occurrences of mild undesirable events, and therefore the data obtained from controlled clinical studies on the effectiveness and tolerance of intravenous ferric carboxymaltose could be confirmed. PMID:24741123

  6. Treatment of Iron Deficiency with or without Anaemia with Intravenous Ferric Carboxymaltose in Gynaecological Practices - A Non-Interventional Study.

    PubMed

    Herfs, R; Fleitmann, L; Kocsis, I

    2014-01-01

    In this multi-centre, prospective, non-interventional study, the effectiveness and tolerance of ferric carboxymaltose (ferinject®; FCM) was tested through use in standard gynaecological practice. In total, data from 273 patients was evaluated. 193 of these patients displayed iron deficiency anaemia (IDA), and 68 had iron deficiency without anaemia (ID). The reasons for the ID/IDA were hypermenorrhoea (HyM) (n?=?170), post-partum condition (PP) (n?=?53) or another indication (n?=?53). The average age of the patients was 40 years old, with 8?% of them being vegetarians. Half of the patients had already been treated for anaemia, primarily with oral iron products (94?%). The primary, serious accompanying symptoms of anaemia were fatigue (72?%), lack of concentration (42?%), pale mucous membranes (42?%), headache (26?%) and sleep disorders (21?%). Only one patient did not show serious symptoms at the start of the study. The most frequent indications for parenteral therapy were the need for rapid iron substitution to reduce symptoms (>?70?%), followed by the lower effectiveness or intolerance of oral products (42?% each) as well as patients not completing the course of treatment with oral products (12?%). Patient information was collected at both the beginning and the end of the observation period, which lasted 15 weeks on average. FCM was most frequently administered via infusion (92?%; average infusion duration 21 minutes). Seven percent of patients received bolus injections. The average total iron dosage per patient was 788.7?mg (median 550?mg; range: 50-3000?mg); the median individual dosage was 500?mg (range: 50-1000?mg). The total dosage was, in most cases, administered through a single application (range: 1-10). Symptoms, blood values (Hb), iron stores (serum-ferritin [S-ferritin]) and transport iron (transferrin saturation [TSAT]) normalised to a large extent. In all subgroups, 92?% of women displayed a marked improvement in all of their symptoms. The average increase in Hb-value in the group as a whole was statistically significant, increasing from 10.5 to 13.0?g/dl. In the group with anaemia, the value increased from 9.9 to 13.3?g/dl, with 80?% of women reaching normal Hb-values. The average S-ferritin value increased by a statistically significant >?70?µg/L from 17.2 to 88.8?µg/l and the value for the TSAT increased from 16.3?% to 22.8?%. Seven patients reported experiencing side effects. None of the results were severe. Overall, as part of this non-interventional study for everyday routine in a gynaecological practice, a rapid improvement in symptoms accompanied by the rectification of iron deficiency and anaemia was shown with low occurrences of mild undesirable events, and therefore the data obtained from controlled clinical studies on the effectiveness and tolerance of intravenous ferric carboxymaltose could be confirmed. PMID:24741123

  7. A universally calibrated microplate ferric reducing antioxidant power (FRAP) assay for foods and applications to Manuka honey.

    PubMed

    Bolanos de la Torre, Amparo Angelica S; Henderson, Terence; Nigam, Poonam Singh; Owusu-Apenten, Richard K

    2015-05-01

    The ferric reducing antioxidant power (FRAP) assay was recently adapted to a microplate format. However, microplate-based FRAP (mFRAP) assays are affected by sample volume and composition. This work describes a calibration process for mFRAP assays which yields data free of volume effects. From the results, the molar absorptivity (?) for the mFRAP assay was 141,698 M(-1) cm(-1) for gallic acid, 49,328 M(-1) cm(-1) for ascorbic acid, and 21,606 M(-1) cm(-1) for ammonium ferrous sulphate. The significance of ? (M(-1) cm(-1)) is discussed in relation to mFRAP assay sensitivity, minimum detectable concentration, and the dimensionless FRAP-value. Gallic acid showed 6.6 mol of Fe(2+) equivalents compared to 2.3 mol of Fe(+2) equivalents for ascorbic acid. Application of the mFRAP assay to Manuka honey samples (rated 5+, 10+, 15+, and 18+ Unique Manuka Factor; UMF) showed that FRAP values (0.54-0.76 mmol Fe(2+) per 100g honey) were strongly correlated with UMF ratings (R(2)=0.977) and total phenols content (R(2) = 0.982)whilst the UMF rating was correlated with the total phenols (R(2) = 0.999). In conclusion, mFRAP assay results were successfully standardised to yield data corresponding to 1-cm spectrophotometer which is useful for quality assurance purposes. The antioxidant capacity of Manuka honey was found to be directly related to the UMF rating. PMID:25529660

  8. In Vivo Evaluation of the Treatment Outcome of Pulpotomy in Primary Molars Using Diode Laser, Formocresol, and Ferric Sulphate

    PubMed Central

    Tanboga, Ilknur

    2014-01-01

    Abstract Objective: The purpose of this study was to assess whether the diode laser (DL) pulpotomy method is a suitable alternative to formocresol (FC) and ferric sulphate (FS) pulpotomies in human primary teeth. Background data: Pulpotomy is the amputation of infected coronal pulp to maintain radicular pulp vitality and function. Although FC is regarded as the gold standard for pulpotomy in primary teeth, concerns about its safety have been reported. Lasers are an effective nonpharmacological alternative for treating pulp in children. Methods: This study included 120 primary molars in 58 children 5–9 years of age who underwent an identical conventional pulpotomy technique; the molars were allocated to FC, FS, and DL groups. After removal of the coronal tissue, complete hemostasis of the remaining pulp in the DL group was achieved by DL at 1.5 W, 30?Hz, and 50?mJ, with a 10?sec exposure time. For the FC group, diluted FC (1:5 Buckley's formocresol) was used for 5?min., and for the FS group, a 15.5% FS solution was used for 15?sec. Treatments in all groups were completed with stainless steel crowns and monitored clinically and radiographically at 1, 3, 6, 9, and 12 months. Results: The clinical success rates at 12 months were 97%, 95%, and 100%, whereas the radiographic success rates were 87%, 79%, and 75%, for the FC, FS and DL groups, respectively. The differences in the results were not statistically significant according to the ?2 test (p>0.05). Conclusions: DL pulpotomy offers a high clinical success rate, however considering radiographic success rate, it may not replace traditional FC and FS pulpotomies in primary molars. PMID:24717147

  9. Inhibition of in vitro growth of coliform bacteria by a monoclonal antibody directed against ferric enterobactin receptor FepA.

    PubMed

    Lin, J; Hogan, J S; Smith, K L

    1998-05-01

    The ability of a murine monoclonal antibody that blocks the enterobactin ligand-binding site of the ferric enterobactin receptor FepA to inhibit the growth of coliform bacteria derived from a bovine intramammary infection (IMI) was determined in an iron-restricted medium. Bacterial isolates from bovine IMI in five herds were tested by the chrome azurol sulfonate assay to detect siderophore production. Each of the isolates of Escherichia coli (n = 25) and Klebsiella pneumoniae (n = 25) were positive for siderophore production. Each isolate expressed iron-regulated outer membrane proteins when grown in trypticase soy broth plus the iron chelator alpha-alpha'-dipyridyl. Immunoblots revealed that the monoclonal antibody recognized FepA that was expressed by each of the E. coli isolates (n = 25). Only 4 of 25 K. pneumoniae isolates produced FepA that reacted with the monoclonal antibody. This result coincided with the results of an in vitro growth assay. Growth of all E. coli isolates was significantly inhibited by the addition of monoclonal antibody to synthetic medium containing apolactoferrin. Antigenic variation in the enterobactin-binding site resulted in a low percentage of K. pneumoniae isolates that were inhibited by the monoclonal antibody. Inhibition of bacterial growth by the monoclonal antibody was dose-dependent. As little as 50 micrograms/ml of purified antibody had an inhibitory effect on bacterial growth in the synthetic iron-restricted medium. Monoclonal antibody specific for the enterobactin ligand-binding site of FepA inhibited the growth of E. coli that was isolated from bovine IMI. PMID:9621228

  10. Elasticity of Single-Crystal Phase D across the Spin Transitions of Ferrous and Ferric Iron in the Lower Mantle

    NASA Astrophysics Data System (ADS)

    Wu, X.; Lin, J. F.; Liu, J.; Mao, Z.; Guo, X.; Yoshino, T.; McCammon, C. A.; Xiao, Y.; Prakapenka, V.

    2014-12-01

    Phase D, the densest hydrous magnesium silicate synthesized at the Earth's mantle P-T conditions thus far, has been proposed to be a potential candidate for transportation of H2O into the lower mantle by subduction of the hydrated oceanic lithosphere. A certain amount of iron, the most abundant transition metal element in the Earth's interior, is expected to be incorporated into the phase D. Here we synthesized high-quality single-crystal Fe,Al-bearing Phase D (Mg0.89Fe0.11Al0.37Si1.55H2.65O6, ~13.3wt% H2O) with grain sizes of ~200 micron using the Kawai multianvil apparatus at 21 GPa and 1200 °C at the Institute for Study of the Earth's Interior, University of Oakayama, Japan. Conventional Mössbauer results indicate that the sample contains both ferrous and ferric iron that occupy the octahedral sites of the hexagonal structure. In situ high-pressure single crystal XRD and NFS experiments were performed up to megabar pressures at 13IDD beamline (GSECARS) and 16IDD beamline (HPCAT) of the Advanced Photon Source, respectively. Both experimental results clearly show that both Fe2+ and Fe3+ undergo a HS-LS transition at high pressures. High-resolution XRD results further indicate an abnormal compression behavior at approximately 37 GPa that can be linked with the previously proposed hydrogen bond symmetrization. Elasticity of phase D has a marked influence by the two-step spin transitions of both Fe2+ and Fe3+ and the hydrogen bond symmetrization, presenting in the seismic wave model, which is of implication for our understanding of the deep-Earth geophysics and geochemistry especially along the subducted slabs.

  11. Regulation of the Expression of the Vibrio parahaemolyticus peuA Gene Encoding an Alternative Ferric Enterobactin Receptor

    PubMed Central

    Tanabe, Tomotaka; Kato, Ayaka; Shiuchi, Keiichi; Miyamoto, Katsushiro; Tsujibo, Hiroshi; Maki, Jun; Yamamoto, Shigeo; Funahashi, Tatsuya

    2014-01-01

    A pvsB-vctA-irgA triple deletion mutant of Vibrio parahaemolyticus can utilize enterobactin under iron-limiting conditions by inducing a previously undescribed receptor, PeuA (VPA0150), in response to extracellular alkaline pH and enterobactin. In silico analyses revealed the existence of a two-component regulatory system operon, peuRS, immediately upstream of peuA, which constitutes an operon with the TonB2 system genes. Both the peuRS and peuA-tonB2 operons were found to be upregulated under iron-limiting conditions in a ferric uptake regulator (Fur)-dependent manner. The involvement of peuA and peuRS in enterobactin utilization was analyzed by complementation experiments using deletion mutants. Primer extension analysis indicated that, under iron-limiting conditions, the transcription of peuA was initiated from the +1 site at pH 7.0 and from both the +1 and +39 sites at pH 8.0 in the presence of enterobactin. The +39 transcript was absent from the peuRS deletion mutant. Secondary structure prediction of their 5?-untranslated regions suggested that translation initiation is blocked in the +1 transcript, but not in the +39 transcript. Consistent with this, in vitro translation analysis demonstrated that production of PeuA was determined only by the +39 transcript. These studies establish a novel gene regulation mechanism in which the two-component regulatory system PeuRS enhances expression of the alternative +39 transcript that possesses non-inhibitory structure, allowing the peuA expression to be regulated at the translation stage. PMID:25148374

  12. Inhibition of bactericidal and bacteriolytic activities of poly-D-lysine and lysozyme by chitotriose and ferric iron.

    PubMed

    Tompkins, G R; O'Neill, M M; Cafarella, T G; Germaine, G R

    1991-02-01

    In a previous report from this laboratory (N. J. Laible and G. R. Germaine, Infect. Immun. 48:720-728, 1985), evidence was presented to suggest that the bactericidal actions of both reduced (i.e., muramidase-inactive) human placental lysozyme and the synthetic cationic homopolymer poly-D-lysine involved the activation of a bacterial endogenous activity that was inhibitable by N,N',N"-triacetylchitotriose (chitotriose). In the present investigation however, we found that the bactericidal and bacteriolytic action of poly-D-lysine could be prevented only by some commercially available chitotriose preparations and not by others. Analysis by physical and chemical methods failed to distinguish protective chitotriose (CTa) and nonprotective chitotriose (CTi) preparations. CTi and CTa preparations displayed equal capacities to competitively inhibit binding of [3H]chitotriose by immobilized lysozyme and were indistinguishable in their abilities to block the lytic activity of lysozyme against Micrococcus lysodeikticus cells. Elemental analysis revealed significantly higher levels of phosphorus, calcium, iron, sodium, manganese, and copper in CTa. Removal of metals from CTa by chelate chromatography completely abolished the poly-D-lysine-protective capacity. Of the metals detected, only ferric iron (5 to 10 microM) mimicked the protective action of CTa. A Fe(III) concentration of 50 microM was required to inhibit lysozyme (5 micrograms/ml). Both Fe(III) and CTa (but not CTi) quantitatively blocked the labeling of poly-D-lysine by fluorescamine, suggesting that the primary amino groups of the lysine residues participate in iron binding. Thus, it appears that the poly-D-lysine-protective capacity of certain chitotriose preparations was due not to the chitotriose itself but to contaminating metal ions which interact directly with the polycationic agent. In contrast, Fe(III) cannot account for inhibition of either the bactericidal or bacteriolytic activity of lysozyme by chitotriose. PMID:1987082

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

    PubMed

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

    2010-01-01

    Numerous studies on various animal species, with variability in the site of application and the concentration of ferric chloride (FeCl3) to induce intravascular thrombosis has prompted us to undertake the present study to obtain a threshold concentration of FeCl3 and validate this model by clinically used anti-thrombotic drugs. A small piece of filter paper, soaked in FeCl3 solution (10, 20, 40, 60 or 80%, w/v), was topically applied on the carotid artery of SD rats to measure the time till occlusion (TTO), to ascertain 20% as an optimal FeCl3 concentration. Anti-platelet drugs, aspirin (30 mg/kg), ticlopidine (200 mg/kg) or clopidogrel (30 mg/kg), administered by oral route for 3 days (once daily) or 4h (single dose) prior to the induction of thrombosis, showed the rank-order: clopidogrel>ticlopidine>aspirin based on TTO by 20% FeCl3. Anti-coagulant drug, heparin (10 U/kg, 30 U/kg and 100 U/kg, i.v) increased TTO in a dose dependent manner (18+/-1.7, 22+/-0.9 and 27+/-3.9 min respectively), while warfarin treated rats at 0.1 mg/kg or 0.3 mg/kg, (po for 5 days), exhibited TTO augmentation to 85+/-11.8 and 120+/-0 min respectively. The results obtained indicate that among the drugs tested warfarin and clopidogrel were most efficacious in this model, while rank order of the other anti-thrombotic drugs were heparin>ticlopidine>aspirin. The present study thus provides a simple, reproducible and well controlled methodology to induce thrombosis in rats by the topical application of 20% FeCl3 to assess the efficacy of new anti-thrombotic agents. PMID:19961942

  14. Short-term effect of the soil amendments activated carbon, biochar, and ferric oxyhydroxide on bacteria and invertebrates.

    PubMed

    Hale, Sarah E; Jensen, John; Jakob, Lena; Oleszczuk, Patryk; Hartnik, Thomas; Henriksen, Thomas; Okkenhaug, Gudny; Martinsen, Vegard; Cornelissen, Gerard

    2013-08-01

    The aim of the present study was to evaluate the secondary ecotoxicological effects of soil amendment materials that can be added to contaminated soils in order to sequester harmful pollutants. To this end, a nonpolluted agricultural soil was amended with 0.5, 2, and 5% of the following four amendments: powder activated carbon (PAC), granular activated carbon, corn stover biochar, and ferric oxyhydroxide powder, which have previously been proven to sequester pollutants in soil. The resulting immediate effects (i.e., without aging the mixtures before carrying out tests) on the springtail Folsomia candida, the earthworm species Aporectodea caliginosa and Eisenia fetida, the marine bacteria Vibrio fischeri, a suite of ten prokaryotic species, and a eukaryote (the yeast species Pichia anomalia) were investigated. Reproduction of F. candida was significantly increased compared to the unamended soil when 2% biochar was added to it. None of the treatments caused a negative effect on reproduction. All amendments had a deleterious effect on the growth of A. caliginosa when compared to the unamended soil, except the 0.5% amendment of biochar. In avoidance tests, E. fetida preferred biochar compared to all other amendments including the unamended soil. All amendments reduced the inhibition of luminescence to V. fischeri, i.e., were beneficial for the bacteria, with PAC showing the greatest improvement. The effects of the amendments on the suite of prokaryotic species and the eukaryote were variable, but overall the 2% biochar dose provided the most frequent positive effect on growth. It is concluded that the four soil amendments had variable but never strongly deleterious effects on the bacteria and invertebrates studied here during the respective recommended experimental test periods. PMID:23802136

  15. Ferric iron chelation lowers brain iron levels after intracerebral hemorrhage in rats but does not improve outcome.

    PubMed

    Auriat, Angela M; Silasi, Gergely; Wei, Zhouping; Paquette, Rosalie; Paterson, Phyllis; Nichol, Helen; Colbourne, Frederick

    2012-03-01

    Iron-mediated free radical damage contributes to secondary damage after intracerebral hemorrhage (ICH). Iron is released from heme after hemoglobin breakdown and accumulates in the parenchyma over days and then persists in the brain for months (e.g., hemosiderin). This non-heme iron has been linked to cerebral edema and cell death. Deferoxamine, a ferric iron chelator, has been shown to mitigate iron-mediated damage, but results vary with less protection in the collagenase model of ICH. This study used rapid-scanning X-ray fluorescence (RS-XRF), a synchrotron-based imaging technique, to spatially map total iron and other elements (zinc, calcium and sulfur) at three survival times after collagenase-induced ICH in rats. Total iron was compared to levels of non-heme iron determined by a Ferrozine-based spectrophotometry assay in separate animals. Finally, using RS-XRF we measured iron levels in ICH rats treated with deferoxamine versus saline. The non-heme iron assay showed elevations in injured striatum at 3 days and 4 weeks post-ICH, but not at 1 day. RS-XRF also detected significantly increased iron levels at comparable times, especially notable in the peri-hematoma zone. Changes in other elements were observed in some animals, but these were inconsistent among animals. Deferoxamine diminished total parenchymal iron levels but did not attenuate neurological deficits or lesion volume at 7 days. In summary, ICH significantly increased non-heme and total iron levels. We evaluated the latter and found it to be significantly lowered by deferoxamine, but its failure to attenuate injury or functional impairment in this model raises concern about successful translation to patients. PMID:22226595

  16. Structure of Oxidized Alpha-Haemoglobin Bound to AHSP Reveals a Protective Mechanism for HAEM

    SciTech Connect

    Feng,L.; Zhou, S.; Gu, L.; Gell, D.; MacKay, J.; Weiss, M.; Gow, A.; Shi, Y.

    2005-01-01

    The synthesis of hemoglobin A (HbA) is exquisitely coordinated during erythrocyte development to prevent damaging effects from individual {alpha}- and {beta}-subunits. The {alpha}-hemoglobin-stabilizing protein (AHSP) binds {alpha}-hemoglobin ({alpha}Hb), inhibits the ability of {alpha}Hb to generate reactive oxygen species and prevents its precipitation on exposure to oxidant stress. The structure of AHSP bound to ferrous {alpha}Hb is thought to represent a transitional complex through which {alpha}Hb is converted to a non-reactive, hexacoordinate ferric form. Here we report the crystal structure of this ferric {alpha}Hb-AHSP complex at 2.4 Angstrom resolution. Our findings reveal a striking bis-histidyl configuration in which both the proximal and the distal histidines coordinate the haem iron atom. To attain this unusual conformation, segments of {alpha}Hb undergo drastic structural rearrangements, including the repositioning of several {alpha}-helices. Moreover, conversion to the ferric bis-histidine configuration strongly and specifically inhibits redox chemistry catalysis and haem loss from {alpha}Hb. The observed structural changes, which impair the chemical reactivity of haem iron, explain how AHSP stabilizes {alpha}Hb and prevents its damaging effects in cells.

  17. Fast Kinetics of Fe2+ Oxidation in Packed-Bed Reactors

    PubMed Central

    Grishin, Sergei I.; Tuovinen, Olli H.

    1988-01-01

    Thiobacillus ferrooxidans was used in fixed-film bioreactors to oxidize ferrous sulfate to ferric sulfate. Glass beads, ion-exchange resin, and activated-carbon particles were tested as support matrix materials. Activated carbon was tested in both a packed-bed bioreactor and a fluidized-bed bioreactor; the other matrix materials were used in packed-bed reactors. Activated carbon displayed the most suitable characteristics for use as a support matrix of T. ferrooxidans fixed-film formation. The reactors were operated within a pH range of 1.35 to 1.5, which effectively reduced the amount of ferric iron precipitation and eliminated diffusion control of mass transfer due to precipitation. The activated-carbon packed-bed reactor displayed the most favorable biomass holdup and kinetic performance related to ferrous sulfate oxidation. The fastest kinetic performance achieved with the activated-carbon packed-bed bioreactor was 78 g of Fe2+ oxidized per liter per h (1,400 mmol of Fe2+ oxidized per liter per h) at a true dilution rate of 40/h, which represents a hydraulic retention time of 1.5 min. PMID:16347798

  18. Association of uranium with iron oxides typically formed on corroding steel surfaces.

    PubMed

    Dodge, C J; Francis, A J; Gillow, J B; Halada, G P; Eng, C; Clayton, C R

    2002-08-15

    Decontamination of metal surfaces contaminated with low levels of radionuclides is a major concern at Department of Energy facilities. The development of an environmentally friendly and cost-effective decontamination process requires an understanding of their association with the corroding surfaces. We investigated the association of uranium with the amorphous and crystalline forms of iron oxides commonly formed on corroding steel surfaces. Uranium was incorporated with the oxide by addition during the formation of ferrihydrite, goethite, green rust II, lepidocrocite, maghemite, and magnetite. X-ray diffraction confirmed the mineralogical form of the oxide. EXAFS analysis at the U L(III) edge showed that uranium was present in hexavalent form as a uranyl oxyhydroxide species with goethite, maghemite, and magnetite and as a bidentate inner-sphere complex with ferrihydrite and lepidocrocite. Iron was present in the ferric form with ferrihydrite, goethite, lepidocrocite, and maghemite; whereas with magnetite and green rust II, both ferrous and ferric forms were present with characteristic ferrous:total iron ratios of 0.65 and 0.73, respectively. In the presence of the uranyl ion, green rust II was converted to magnetite with concomitantreduction of uranium to its tetravalent form. The rate and extent of uranium dissolution in dilute HCl depended on its association with the oxide: uranium present as oxyhydroxide species underwent rapid dissolution followed by a slow dissolution of iron; whereas uranium present as an inner-sphere complex with iron resulted in concomitant dissolution of the uranium and iron. PMID:12214641

  19. Coordinated analyses of orbital and spirit rover data to characterize surface materials on the cratered plains of Gusev Crater, Mars

    USGS Publications Warehouse

    Lichtenberg, K.A.; Arvidson, R.E.; Poulet, F.; Morris, R.V.; Knudson, A.; Bell, J.F.; Bellucci, G.; Bibring, J.-P.; Farrand, W.H.; Johnson, J.R.; Ming, D.W.; Pinet, P.C.; Rogers, A.D.; Squyres, S.W.

    2007-01-01

    Comparison of the Mars Exploration Rover Spirit's Pancam (0.4 to 1.0 ??m) and Mars Express Observatoire pour la Mineralogie l'Eau, les Glaces et l'Activite?? (OMEGA) (0.4 to 2.5 ??m) spectral reflectance data over Spirit's traverses shows that Gusev cratered plains are dominated by nanophase ferric-oxide-rich dust covering weakly altered basaltic sands. This interpretation is also consistent with both observations from OMEGA data covering plains beyond the traverse region and interpretations of data from the other payload instruments on the Spirit Rover. OMEGA observations of relatively low albedo regions where dust has presumably been stripped by dust devils show negative spectral reflectance slopes from 1.5 to 2.5 ??m and moderately masked spectral features which are indicative of olivine or pyroxene. High-albedo regions north and south of the Spirit landing site have flat spectral reflectance slopes and few spectral features, although all spectra have a nanophase ferric-oxide absorption edge between 0.4 and 0.75 ??m. Comparison of THEMIS-derived thermal inertia values with OMEGA-derived spectral parameters shows that although the dust cover can be optically thick (0.4 to 2.5 ??m wavelength region) in some areas, it is not thick enough (???1 cm) to mask the thermal inertia of the underlying substrate for areas included in this study. Copyright 2007 by the American Geophysical Union.

  20. Pilot scale application of nanosized iron oxides as electron acceptors for bioremediation

    NASA Astrophysics Data System (ADS)

    Bosch, Julian; Fritzsche, Andreas; Frank-Fahle, Beatrice; Lüders, Tilmann; Höss, Sebastian; Eisenmann, Heinrich; Held, Thomas; Totsche, Kai U.; Meckenstock, Rainer U.

    2014-05-01

    Microbial reduction of ferric iron is a major biogeochemical process in groundwater aquifer ecosystems and often associated with the degradation of organic contaminants, as bacteria couple iron reduction to the oxidation reduced carbon like e.g. BTEX. Yet in general the low bioavailability of natural iron oxides limits microbial reduction rates. However, nanosized iron oxides have an unequally enhanced bioavailability and reactivity compared to their respective bulk, macro-sized, and more crystalline materials. At the same time, nanosized iron oxides can be produced in stable colloidal suspensions, permitting efficient injections into contaminated aquifers. We examined the reactivity of nanosized synthetic colloidal iron oxides in microbial iron reduction. Application of colloidal nanoparticles led to a strong and sustainable enhancement of microbial reaction rates in batch experiments and sediment columns. Toluene oxidation was increased five-fold as compared to bulk, non-colloidal ferrihydrite as electron acceptor. Furthermore, we developed a unique approach for custom-tailoring the subsurface mobility of these particles after being injected into a contaminant plume. In a field pilot application, we injected 18 m3 of an iron oxide nanoparticle solution into a BTEX contaminated aquifer with a maximum excess pressure as low as 0.2 bar. The applied suspension showed a superior subsurface mobility, creating a reactive zone of 4 m height (corresponding to the height of the confined aquifer) and 6 m in diameter. Subsequent monitoring of BTEX, microbial BTEX degradation metabolites, ferrous iron generation, stable isotopes fractionation, microbial populations, and methanogenesis demonstrated the strong impact of our approach. Mathematic processed X-ray diffractograms and FTIR spectra provided a semi-quantitatively estimate of the long-term fate of the iron oxide colloids in the aquifer. Potential environmental risks of the injection itself were monitored with ecotoxicological investigations. Our data suggest that the injection of ferric iron nanoparticles as electron acceptors into contaminated aquifers for the enhancement of microbial contaminant degradation might develop into a novel bioremediation strategy.

  1. Magnesium Oxide

    MedlinePLUS

    Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some ... to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative ...

  2. Oxides (GCMP)

    NSDL National Science Digital Library

    Oxides: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will explore the properties of the oxides of a few elements. We will add samples of the oxides to universal indicator solution and learn about the acid-base character of the oxides. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

  3. FhuD1, a Ferric Hydroxamate-binding Lipoprotein in Staphylococcus aureus - A case of gene duplication and lateral transfer

    SciTech Connect

    Sebulsky, M. Tom; Speziali, Craig D.; Shilton, Brian H.; Edgell, David R. (UWO)

    2010-11-16

    Staphylococcus aureus can utilize ferric hydroxamates as a source of iron under iron-restricted growth conditions. Proteins involved in this transport process are: FhuCBG, which encodes a traffic ATPase; FhuD2, a post-translationally modified lipoprotein that acts as a high affinity receptor at the cytoplasmic membrane for the efficient capture of ferric hydroxamates; and FhuD1, a protein with similarity to FhuD2. Gene duplication likely gave rise to fhuD1 and fhuD2. While the genomic locations of fhuCBG and fhuD2 in S. aureus strains are conserved, both the presence and the location of fhuD1 are variable. The apparent redundancy of FhuD1 led us to examine the role of this protein. We demonstrate that FhuD1 is expressed only under conditions of iron limitation through the regulatory activity of Fur. FhuD1 fractions with the cell membrane and binds hydroxamate siderophores but with lower affinity than FhuD2. Using small angle x-ray scattering, the solution structure of FhuD1 resembles that of FhuD2, and only a small conformational change is associated with ferrichrome binding. FhuD1, therefore, appears to be a receptor for ferric hydroxamates, like FhuD2. Our data to date suggest, however, that FhuD1 is redundant to FhuD2 and plays a minor role in hydroxamate transport. However, given the very real possibility that we have not yet identified the proper conditions where FhuD1 does provide an advantage over FhuD2, we anticipate that FhuD1 serves an enhanced role in the transport of untested hydroxamate siderophores and that it may play a prominent role during the growth of S. aureus in its natural environments.

  4. Microbial reduction of ferric iron oxyhydroxides as a way for remediation of grey forest soils heavily polluted with toxic metals by infiltration of acid mine drainage

    NASA Astrophysics Data System (ADS)

    Georgiev, Plamen; Groudev, Stoyan; Spasova, Irena; Nicolova, Marina

    2015-04-01

    The abandoned uranium mine Curilo is a permanent source of acid mine drainage (AMD) which steadily contaminated grey forest soils in the area. As a result, the soil pH was highly acidic and the concentration of copper, lead, arsenic, and uranium in the topsoil was higher than the relevant Maximum Admissible Concentration (MAC) for soils. The leaching test revealed that approximately half of each pollutant was presented as a reducible fraction as well as the ferric iron in horizon A was presented mainly as minerals with amorphous structure. So, the approach for remediation of the AMD-affected soils was based on the process of redoxolysis carried out by iron-reducing bacteria. Ferric iron hydroxides reduction and the heavy metals released into soil solutions was studied in the dependence on the source of organic (fresh or silage hay) which was used for growth and activity of soil microflora, initial soil pH (3.65; 4.2; and 5.1), and the ion content of irrigation solutions. The combination of limestone (2.0 g/ kg soil), silage addition (at rate of 45 g dry weight/ kg soil) in the beginning and reiterated at 6 month since the start of soil remediation, and periodical soil irrigation with slightly acidic solutions containing CaCl2 was sufficient the content of lead and arsenic in horizon A to be decreased to concentrations similar to the relevant MAC. The reducible, exchangeable, and carbonate mobile fractions were phases from which the pollutants was leached during the applied soil remediation. It determined the higher reduction of the pollutants bioavailability also as well as the process of ferric iron reduction was combined with neutralization of the soil acidity to pH (H2O) 6.2.

  5. Ethylene Oxide

    Cancer.gov

    At room temperature, ethylene oxide is a flammable colorless gas with a sweet odor. It is used primarily to produce other chemicals, including antifreeze. In smaller amounts, ethylene oxide is used as a pesticide and a sterilizing agent. The ability of ethylene oxide to damage DNA makes it an effective sterilizing agent but also accounts for its cancer-causing activity.

  6. A study of the condensation of primary, secondary, and tertiary butyl alcohols with benzene in the presence of anhydrous ferric chloride 

    E-print Network

    Dodson, Ralph Jordan

    1939-01-01

    A PKDT Qt THE COND%SATION QE PRECUT, SSQGNDART~ AND T~ NOTCL ALCOHOLS NITH SEEZEEE IN THE ~E GF ANBIINKU8 mRIQ CHLORIDE Asm 1959 4 et Chea1stxy and 0 A STOSX Gf THE OQtGRWSATIOR Of PRXRARX, SWOORBARX ARRI TCBTXARX WTXL ALQOBOLB WITH 8%%ESSE IR... THS F58XWOR Of AWHXQREUS FERRIC CBLORISR A STUART OF TBR CNRRGATTGR OF PIIRSGKo SROOP~e ARD TRRTZART RDTTL ALCOHOLS RITE ~R ZN TKR FRRSRBCR OP ARBTDROUS PRIBKC OHLORTDR A Theete Parttal Palfileaat cf the ReRNLreewate Ter the aeggso cf Rse4e et...

  7. The safety and efficacy of high dose ferric carboxymaltose in patients with chronic kidney disease: A single center study.

    PubMed

    Vikrant, S; Parashar, A

    2015-01-01

    Ferric carboxymaltose (FCM) is a parenteral, dextran-free iron formulation designed to overcome the limitations of existing intravenous (IV) iron preparations. We investigated the safety and efficacy of high dose administration of FCM in our anemic chronic kidney disease (CKD) patients. It was a prospective observational study from June 2011 to August 2013. FCM was administered as IV infusion 1000 mg in 250 ml of normal saline over 15-30 min. Efficacy was evaluated by comparing the Hb and/or serum iron status at the first follow-up visit after the infusion with that at the baseline. A total of 500 infusions were administered to 450 patients. All patients had a successful administration of the FCM. None of the patients had any serious drug-related AE. AE of mild to moderate severity observed or reported after the infusion were: accelerated hypertension (0.2%), feeling abnormal (0.6%), headache and bodyaches (0.6% each), and infusion site reaction (0.8%). 261 patients had a follow up Hb, which showed an increase of 1.7 ± 1.5 g/dl after a period of 11 ± 7.2 weeks (P = 0.001); 188 (72%) patients had a rise in Hb of ?1 g/dl. The increase in Hb was observed uniformly across all stages of CKD. Proportions of patients with an Hb of above 10 and 11 g/dl increased from 30.2% to 62.8% and 16.1% to 37.9%, respectively (P = 0.001). Iron status evaluation done in 44 patients after a follow up period of 15.1 ± 11.5 weeks showed increases in Hb of 1.6 ± 2.2 g/dl (P = 0.001), transferrin saturation of 9.1 ± 16.9% (P = 0.001), and ferritin of 406 ± 449 ng/ml (P = 0.001). We conclude high dose administration of FCM is safe and well-tolerated. It was effective in the treatment of iron deficiency in nondialysis and peritoneal dialysis CKD patients. PMID:26199472

  8. Ferric Tourmaline from Mexico

    Microsoft Academic Search

    Brian Mason; Gabrielle Donnay; L. A. Hardie

    1964-01-01

    Dark brown crystals, up to 10 mm long, occur in rhyolite at Mexquitic, San Luis Potosi, Mexico. They are short prismatic, showing {11overline{2}0}, {30overline{3}0}, {10overline{1}1}, {02overline{2}1}, with c\\/a 0.4521, measured with a goniometer, and distinct {11overline{2}0} 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

  9. Ferric iron in tourmaline

    Microsoft Academic Search

    Stephanie M. Mattson; George R. Rossman

    1984-01-01

    Red Fe3+-rich and black Fe3+, Fe2+-rich tourmalines have been studied by optical and Mössbauer spectroscopies to determine the optical characteristics of Fe3+ in tourmaline. Prominent optical absorption features at 485 and 540 nm are assigned to transitions of multiple exchange-coupled Fe3+ pairs in several site combinations. These transitions are more intense than those of isolated Fe3+ and are polarized along

  10. Removal of Endocrine Disrupting Chemicals in Wastewater Treatment by Fenton-Like Oxidation

    Microsoft Academic Search

    Augustine O. Ifelebuegu; Chinyere P. Ezenwa

    2011-01-01

    The presence of endocrine-disrupting chemicals (EDCs) in wastewater effluent is a major concern to the scientific community.\\u000a This research effort was aimed at investigating Fenton-like degradation of two EDCs 17?-estradiol (E2) and 17?-ethinylestradiol\\u000a (EE2). The results of the study showed that E2 and EE2 were effectively removed by the Fenton-like oxidation process. Removal\\u000a efficiencies of 95% and 98% at ferric

  11. Nanophase and Composite Optical Materials

    NASA Technical Reports Server (NTRS)

    2003-01-01

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

  12. The energetics of nanophase calcite

    Microsoft Academic Search

    Tori Z. Forbes; A. V. Radha; Alexandra Navrotsky

    Calcium carbonate (CaCO3) is an important component of the near-surface environment. Understanding the nature of its precipitation is important for a variety of environmental processes, as well as for the geologic sequestration of anthropogenic carbon dioxide. Calcite is the most thermodynamically stable bulk polymorph, but energy crossovers may exist that could favor the precipitation of vaterite or aragonite with decreasing

  13. Ferrous iron oxidation by foam immobilized Acidithiobacillus ferrooxidans: Experiments and modeling.

    PubMed

    Jaisankar, S; Modak, J M

    2009-01-01

    Ferrous iron bio-oxidation by Acidithiobacillus ferrooxidans immobilized on polyurethane foam was investigated. Cells were immobilized on foams by placing them in a growth environment and fully bacterially activated polyurethane foams (BAPUFs) were prepared by serial subculturing in batches with partially bacterially activated foam (pBAPUFs). The dependence of foam density on cell immobilization process, the effect of pH and BAPUF loading on ferrous oxidation were studied to choose operating parameters for continuous operations. With an objective to have high cell densities both in foam and the liquid phase, pretreated foams of density 50 kg/m(3) as cell support and ferrous oxidation at pH 1.5 to moderate the ferric precipitation were preferred. A novel basket-type bioreactor for continuous ferrous iron oxidation, which features a multiple effect of stirred tank in combination with recirculation, was designed and operated. The results were compared with that of a free cell and a sheet-type foam immobilized reactors. A fivefold increase in ferric iron productivity at 33.02 g/h/L of free volume in foam was achieved using basket-type bioreactor when compared to a free cell continuous system. A mathematical model for ferrous iron oxidation by Acidithiobacillus ferrooxidans cells immobilized on polyurethane foam was developed with cell growth in foam accounted by an effectiveness factor. The basic parameters of simulation were estimated using the experimental data on free cell growth as well as from cell attachment to foam under nongrowing conditions. The model predicted the phase of both oxidation of ferrous in shake flasks by pBAPUFs as well as by fully activated BAPUFs for different cell loadings in foam. Model for stirred tank basket bioreactor predicted within 5% both transient and steady state of the experiments closely for the simulated dilution rates. Bio-oxidation at high Fe(2+) concentrations were simulated with experiments when substrate and product inhibition coefficients were factored into cell growth kinetics. PMID:19610075

  14. The conformation of P450cam in complex with putidaredoxin is dependent on oxidation state

    PubMed Central

    Myers, William K.; Lee, Young-Tae; Britt, R. David; Goodin, David B.

    2013-01-01

    Double electron-electron resonance (DEER) spectroscopy was used to determine the conformational state in solution for the heme monooxygenase P450cam when bound to its natural redox partner, putidaredoxin (Pdx). When oxidized Pdx was titrated into substrate-bound ferric P450cam, the enzyme shifted from the closed to the open conformation. In sharp contrast however, the enzyme remained in the closed conformation when ferrous-CO P450cam was titrated with reduced Pdx. This result fully supports the proposal that binding of oxidized Pdx to P450cam opposes the open to closed transition induced by substrate binding. However, the data strongly suggest that, in solution, binding of reduced Pdx to P450cam does not favor the open conformation. This supports a model in which substrate recognition is associated with the open-to-closed transition and electron transfer from Pdx occurs in the closed conformation. The opening of the enzyme in the ferric-hydroperoxo state following electron transfer from Pdx would provide for efficient O2 bond activation, substrate oxidation and product release. PMID:23901883

  15. High affinity (/sup 3/H). beta. -Alanine uptake by scar margins of ferric chloride-induced epileptogenic foci in rat isocortex

    SciTech Connect

    Robitaille, Y.; Sherwin, A.

    1984-07-01

    Cortical astrocytes of normal mammalian brain are endowed with a high affinity uptake system for ..beta..-Alanine which is competitively inhibited by gamma aminobutyric acid (GABA), a neurotransmitter strongly implicated in epileptogenesis. The authors evaluated (/sup 3/H) ..beta..-Alanine uptake by reactive astrocytes proliferating within scar of epileptogenic foci induced in rat motor cortex by microinjections of 100 mM ferric chloride. Following in vitro incubation of scar tissue with (/sup 3/H) ..beta..-Alanine, ultrastructural morphometry of grain patterns at 5, 30 and 120 days post injection revealed early and significant grain count increases over astroglial processes, predominantly those related to perivascular glial end-feet. Astrocytic cell body and endothelial cell counts showed a more gradual and stepwise increase. Similar data were obtained by comparing visual and edited mean astrocytic grain counts. These results suggest that the enhanced uptake of reactive astrocytes may reflect a marked decrease of inhibitory GABAergic neurons within ferric chloride-induced scars. 7 figures, 1 table.

  16. Oxide Spintronics

    Microsoft Academic Search

    Manuel Bibes; Agns Barthelemy

    2007-01-01

    Concomitant with the development of metal-based spintronics in the late 1980s and 1990s, important advances were made on the growth of high-quality oxide thin films and heterostructures. While this was at first motivated by the discovery of high-temperature superconductivity in perovskite Cu oxides, this technological breakthrough was soon applied to other transition-metal oxides and, notably, mixed-valence manganites. The discovery of

  17. The oxidation products of crude mesobilirubinogen

    PubMed Central

    Stoll, M. S.; Gray, C. H.

    1970-01-01

    Bile pigment esters were separated by ascending t.l.c. Apparently pure pigments, obtained by ferric chloride oxidation of crude mesobilirubinogen, derived from commercial bilirubin by reduction with sodium amalgam, were shown to be complex mixtures. Successive chromatography of their dimethyl esters on silica gel in methyl acetate–methyl propionate–dichloromethane–carbon tetrachloride (1:1:1:1, by vol.), ethyl methyl ketone–1,2-dichloroethane (1:2, v/v) and benzene–ethanol (100:3, v/v) revealed two major blue pigments (verdins), six major violet pigments (violins) and a red pigment (rhodin) together with numerous minor components. i-Urobilin dimethyl ester, prepared from mesobilirubinogen by dehydrogenation with aqueous iodine, was resolved into three major and at least four minor components on silica gel–kieselguhr (3:1, w/w) in benzene–ethanol (25:2, v/v). The chemical nature of these pigments was investigated by oxidation, by visible and u.v. spectroscopy, by mass spectrometry and by n.m.r. spectrometry. The evidence suggests unusual rearrangement of bilirubin during reduction leading to the formation of III? and XIII? isomers. Isomeric forms of mesobiliviolin IX? and of i-urobilin IX? may also be formed. PMID:5420035

  18. The oxidation products of crude mesobilirubinogen.

    PubMed

    Stoll, M S; Gray, C H

    1970-04-01

    Bile pigment esters were separated by ascending t.l.c. Apparently pure pigments, obtained by ferric chloride oxidation of crude mesobilirubinogen, derived from commercial bilirubin by reduction with sodium amalgam, were shown to be complex mixtures. Successive chromatography of their dimethyl esters on silica gel in methyl acetate-methyl propionate-dichloromethane-carbon tetrachloride (1:1:1:1, by vol.), ethyl methyl ketone-1,2-dichloroethane (1:2, v/v) and benzene-ethanol (100:3, v/v) revealed two major blue pigments (verdins), six major violet pigments (violins) and a red pigment (rhodin) together with numerous minor components. i-Urobilin dimethyl ester, prepared from mesobilirubinogen by dehydrogenation with aqueous iodine, was resolved into three major and at least four minor components on silica gel-kieselguhr (3:1, w/w) in benzene-ethanol (25:2, v/v). The chemical nature of these pigments was investigated by oxidation, by visible and u.v. spectroscopy, by mass spectrometry and by n.m.r. spectrometry. The evidence suggests unusual rearrangement of bilirubin during reduction leading to the formation of IIIalpha and XIIIalpha isomers. Isomeric forms of mesobiliviolin IXalpha and of i-urobilin IXalpha may also be formed. PMID:5420035

  19. Postponed effect of neostigmine on oxidative homeostasis

    PubMed Central

    2014-01-01

    Cholinesterases are enzymes able to hydrolyze the neurotransmitter acetylcholine and thus to terminate transmission. Once the enzymes are inhibited, excitotoxicity can appear in the adjacent cells. It is well known that oxidative stress is involved in the toxicity of cholinesterase inhibitors. Commonly, stress follows inhibition of cholinesterases and disappears shortly afterwards. In the present experiment, it was decided to test the impact of an inhibitor, neostigmine, on oxidative stress in BALB/c mice after a longer interval. The animals were sacrificed three days after onset of the experiment and spleens and livers were collected. Reduced glutathione (GSH), glutathione reductase (GR), glutathione S-transferase (GST), thiobarbituric acid reactive substances (TBARS), ferric reducing antioxidant power (FRAP), caspase-3 and activity of acetylcholinesterase (AChE) were assayed. The tested markers were not altered with exceptions of FRAP. The FRAP values indicate accumulation of low molecular weight antioxidants in the examined organs. The role of low molecular weight antioxidants in the toxicity of AChE inhibitors is discussed.

  20. [Surface chemical behavior of 2,4-dichlorophenol in presence of metal oxides].

    PubMed

    Lin, Qi; Wu, Jianyang; Chen, Yingxu; Jin, Haifeng

    2005-04-01

    To understand the surface chemistry of phenolic pollutants in the presence of metal oxides, this paper studied the reactions of 2,4-dichlorophenol with metal oxides in a kinetic and batch experiment. The results showed that amorphous ferric oxyhydroxide, goethite, delta-MnO2 and alpha-MnO2 were the potential oxidizing agents of natural and xenobiotic organic compounds. The oxidation rate of 2,4-DCP on the surface of these metal oxides was in order of delta-MnO2 > alpha-MnO2 > iron oxides. It was observed from the pseudo-first-order kinetics that the reaction rates of manganese oxides were 3-50 times higher than those of iron oxides, and delta-MnO2 had a 1.5-3.2 times higher reaction rate than alpha-MnO2. Root exudates had a significant effect on the oxidation ability of metal oxides through changing the surface characteristics or involving in the reaction process. Upon the addition of ryegrass root exudates, the oxidation of 2,4-DCP was decreased in the suspension of alpha-MnO2 while increased in that of delta-MnO2. The coexistence of Cu probably influenced the oxidation process of 2,4-DCP on the surface of metal oxides. A greater negative effect of Cu on the oxidation of 2,4-DCP was also observed in the suspension of delta-MnO2 due to its strong adsorption toward Cu, as compared with that of alpha-MnO2. PMID:16011168

  1. Nickel-assisted growth and selective doping of spinel-like gallium oxide nanocrystals in germano-silicate glasses for infrared broadband light emission

    NASA Astrophysics Data System (ADS)

    Sigaev, V. N.; Golubev, N. V.; Ignat'eva, E. S.; Savinkov, V. I.; Campione, M.; Lorenzi, R.; Meinardi, F.; Paleari, A.

    2012-01-01

    The target of taking advantage of the near-infrared light-emission properties of nickel ions in crystals for the design of novel broadband optical amplifiers requires the identification of suitable nanostructured glasses able to embed Ni-doped nanocrystals and to preserve the workability of a glass. Here we show that Ni doping of Li2O-Na2O-Ga2O3-GeO2-SiO2 glass (with composition 7.5:2.5:20:35:35 and melting temperature 1480 °C, sensibly lower than in Ge-free silicates) enables the selective embedding of nickel ions in thermally grown nanocrystals of spinel-like gallium oxide. The analysis of transmission electron microscopy and x-ray diffraction data as a function of Ni-content (from 0.01 to 1 mol%) indicates that Ni ions promote the nanophase crystallization without affecting nanoparticle size (~6 nm) and concentration (~4 × 1018 cm - 3). Importantly, as shown by optical absorption spectra, all nickel ions enter into the nanophase, with a number of ions per nanocrystal that depends on the nanocrystal concentration and ranges from 1 to 102. Photoluminescence data indicate that fast non-radiative decay processes become relevant only at mean ion-ion distances shorter than 1.4 nm, which enables the incorporation of a few Ni ions per nanoparticle without too large a worsening of the light-emission efficiency. Indeed, at 0.1 mol% nickel, the room temperature quantum yield is 9%, with an effective bandwidth of 320 nm.

  2. Methanol oxidation on semiconducting oxides

    Microsoft Academic Search

    J. Estellé; J. E. Sueiras

    1993-01-01

    Correlations between reaction rates and selectivities vs. Egap (eV) of the semiconducting oxides Co3O4, CuO, NiO, Cr2O3, ?-Fe2O3, TiO2 and MoO3 were obtained for the catalytic air oxidation of methanol at 573 K. Higher and lower selectivities to formaldehyde for Egap>2 n-type, and Egap >2 p-type semiconducting oxides, are observed, respectively.

  3. Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

    NASA Astrophysics Data System (ADS)

    Evans, K.; Ferris, F.

    2009-05-01

    At concentrations above 1 mg/L, fluoride in drinking water can lead to dental and skeletal fluorosis, a disease that causes mottling of the teeth, calcification of ligaments, crippling bone deformities and many other physiological disorders that can, ultimately, lead to death. Conservative estimates are that fluorosis afflicts tens of millions of people worldwide. As there is no treatment for fluorosis, prevention is the only means of controlling the disease. While numerous defluoridation techniques have been explored, no single method has been found to be both effective and inexpensive enough to implement widely. Our research began in India, with a large-scale geochemical study of the groundwater in a fluoride-contaminated region of Orissa. Having developed a better understanding of the geochemical relationships that exist between fluoride and other parameters present in an affected area, as well as the complex relationships that arise among those parameters that can impact the presence of fluoride, we began investigating certain remediation scenarios involving iron oxides. A common approach to remediation involves the partitioning of fluoride from groundwater by sorption onto a variety of materials, one of the most effective of which is iron oxide whose surface area acts as a scavenger for fluoride. In the presence of iron oxidizing bacteria, the oxidation rate of iron has been shown to be ˜6 times greater than in their absence; fluoride should, therefore, be removed from an aqueous environment by bacteriogenic iron oxides (BIOS) much more quickly than by abiotic iron oxides. Most recently, sorption studies have been conducted using both BIOS and synthetic hydrous ferric oxides in order to compare the behavior between biotic and abiotic sorbents. These studies have provided sorption isotherms that allow comparison of fluoride removed by sorption to BIOS versus synthetic iron oxides. Sorption affinity constants have also been determined, which allow for the prediction of fluoride removal in a wide variety of groundwater systems. Sorption isotherms and affinity constants show the use of BIOS to be a promising technique for the remediation of fluoride in groundwater.

  4. Variations in the Fe mineralogy of bright Martian soil

    NASA Technical Reports Server (NTRS)

    Murchie, Scott; Mustard, John; Erard, Stephane; Geissler, Paul; Singer, Robert

    1993-01-01

    Bright regions on Mars are interpreted as 'soil' derived by chemical alteration of crustal rocks, whose main pigmentary component is ferric oxide or oxyhydroxide. The mineralogy and mineralogic variability of ferric iron are important evidence for the evolution of Martian soil: mineralogy of ferric phases is sensitive to chemical conditions in their genetic environments, and the spatial distributions of different ferric phases would record a history of both chemical environments and physical mixing. Reflectance spectroscopic studies provide several types of evidence that discriminate possible pigmentary phases, including the position of a crystal field absorption near 0.9 microns and position and strengths of absorptions in the UV-visible wavelength region. Recent telescopic spectra and laboratory measurements of Mars soil analogs suggest that spectral features of bright soil can be explained based on a single pigmentary phase, hematite (alpha-Fe2O3), occurring in both 'nanophase' and more crystalline forms. Here we report on a systematic investigation of Martian bright regions using ISM imaging spectrometer data, in which we examined spatial variations in the position and shape of the approximately 0.9 microns absorption. We found both local and regional heterogeneities that indicate differences in Fe mineralogy. These results demonstrate that bright soils do not represent a single lithology that has been homogenized by eolian mixing, and suggest that weathering of soils in different geologic settings has followed different physical and chemical pathways.

  5. Oxidation of chalcopyrite by in-situ electrogenerated Fe{sup III}and Cu{sup II} using an ion exchange membrane

    SciTech Connect

    Ivanaj, S.; Gaballah, I. [Lab. d`Environnement et de Mineralurgie, Vandoeuvre (France); [Ecole Nationale Superieure de Geologie, Vandoeuvre (France); [Centre National de la Recherche Scientifique, Paris (France); [Inst. National Polytechnique de Lorraine, Vandoeuvre (France)

    1995-08-01

    Oxidation of chalcopyrite from a copper concentrate in an electrochemical cell having separate anodic and cathodic compartments was studied by potentiodynamic, potentiostatic and galvanostatic experiments. Oxidation of chalcopyrite particles was mainly realized by in-situ electrogenerated Fe{sup III} and Cu{sup II} ions. The use of an ion exchange membrane, in this experimental set, avoids the reduction of the ferric and cupric ions. The effects of particle size, current feeder potential, current intensity and pulp density were studied to optimize the oxidation parameters. Selective complete oxidation of chalcopyrite was achieved. Oxidation of pyrite was negligible. More than 85% of sulfur was obtained in its elemental form. This may allow selective extraction of copper from the chalcopyrite concentrate without sulfur dioxide emissions. 49 refs.

  6. Towards determining details of anaerobic growth coupled to ferric iron reduction by the acidophilic archaeon ‘ Ferroplasma acidarmanus ’ Fer1

    Microsoft Academic Search

    Mark Dopson; Craig Baker-Austin; Philip Bond

    2007-01-01

    Elucidation of the different growth states of Ferroplasma species is crucial in understanding the cycling of iron in acid leaching sites. Therefore, a proteomic and biochemical study\\u000a of anaerobic growth in ‘Ferroplasma\\u000a acidarmanus’ Fer1 has been carried out. Anaerobic growth in Ferroplasma spp. occurred by coupling oxidation of organic carbon with the reduction of Fe3+; but sulfate, nitrate, sulfite, thiosulfate,

  7. Oxidative effect of several intravenous iron complexes in the rat.

    PubMed

    Bailie, George R; Schuler, Catherine; Leggett, Robert E; Li, Hsin; Li, Hsin-Dat; Patadia, Hiten; Levin, Robert

    2013-06-01

    The objective of this study was to compare the oxidative stress induced in rat internal organs by the administration of the following clinically used intravenous (IV) iron (Fe) containing compounds: iron sucrose (IS), iron dextran (ID), ferric carboxymaltose and ferumoxytol. Groups of six adult rats received 1 mg/kg of each compound weekly for 5 doses. Seven days following the last dose, animals were euthanized and tissue samples of heart, lung, liver, and kidney were obtained, washed in warmed saline and frozen under liquid nitrogen and stored at -80 °C for analysis for nitrotyrosine (NT) and dinitro phenyl (DNP) as markers of oxidative stress. All tissues showed a similar pattern of oxidative stress. All Fe products stimulated an increase in the tissue concentration of both NT and DNP. In general, DNP was stimulated significantly less than NT except for IS. DNP was stimulated to an equal degree except for ID where NT was significantly higher than the NT concentrations in all other Fe compounds. ID produced over 10-fold the concentration of NT than any other Fe. IV Fe compounds present a risk of oxidative stress to a variety of internal organs. However, we found that IS was the least damaging and ID was the worst. PMID:23681275

  8. Optical phonon spectra of lutetium fluoride, oxyfluoride, and lutetium oxide nanoparticles

    Microsoft Academic Search

    A. V. Bazhenov; T. N. Fursova; V. V. Kedrov; I. M. Shmytko; N. V. Klassen

    2008-01-01

    Nano-and microcrystalline LuF3 phases have been synthesized with particle sizes of 30 nm and 30 ?m, respectively. Analysis of the IR reflection spectra\\u000a measured at T = 300 K showed that the nanophase differs from the microcrystalline phase by reduced optical phonon frequencies. It is established\\u000a that annealing of the LuF3 nanophase in air leads to the formation of nanoparticles

  9. Stabilized-solubilized ferric pyrophosphate as a new iron source for food fortification. Bioavailability studies by means of the prophylactic-preventive method in rats.

    PubMed

    Salgueiro, M J; Arnoldi, S; Kaliski, M A; Torti, H; Messeri, E; Weill, R; Zubillaga, M; Boccio, J

    2009-02-01

    The purpose of the present work was to evaluate the iron bioavailability of a new ferric pyrophosphate salt stabilized and solubilized with glycine. The prophylactic-preventive test in rats, using ferrous sulfate as the reference standard, was applied as the evaluating methodology both using water and yogurt as vehicles. Fifty female Sprague-Dawley rats weaned were randomized into five different groups (group 1: FeSO(4); group 2: pyr; group 3: FeSO(4) + yogurt; group 4: pyr + yogurt and group 5: control). The iron bioavailability (BioFe) of each compound was calculated using the formula proposed by Dutra-de-Oliveira et al. where BioFe % = (HbFef - HbFei) x 100/ToFeIn. Finally, the iron bioavailability results of each iron source were also given as relative biological value (RBV) using ferrous sulfate as the reference standard. The results showed that both BioFe % and RBV % of the new iron source tested is similar to that of the reference standard independently of the vehicle employed for the fortification procedure (FeSO(4) 49.46 +/- 12.0% and 100%; Pyr 52.66 +/- 15.02% and 106%; FeSO(4) + yogurth 54.39 +/- 13.92% and 110%; Pyr + yogurt 61.97 +/- 13.54% and 125%; Control 25.30 +/- 6.60, p < 0.05). Therefore, the stabilized and soluble ferric pyrophosphate may be considered as an optimal iron source for food fortification. PMID:18802669

  10. The effects of phosphoric acid, sodium hypochlorite, ferric oxalate and Scotchbond Multipurpose on the rate of pressure change across dentine: a laboratory study.

    PubMed

    Ng, L P; Wilson, P R

    2005-06-01

    The aim of this study was to investigate the consequences of dentine treatment on dentine permeability of crown preparations treated with phosphoric acid, sodium hypochlorite (NaOCl), and then ferric oxalate (Sensodyne sealant) or bis-phenol-A-diglycidyldimethacrylate (BIS-GMA) and hydroxyethylmethacrylate (HEMA) resin combination (Scotchbond Multipurpose). Thirty human premolars received full crown preparations (stage A), were then acid etched (stage B) and subsequently the pulp chamber flushed with NaOCl (stage C). They were then randomly assigned to two groups: group 1 was treated with Scotchbond Multipurpose and group 2 with 6% ferric oxalate (Sensodyne sealant) (stage D). Both groups were acid etched a second time (stage E) as the final step in the sequence. The rise in pressure in the pulp chamber because of the transmission of saline from the pressure chamber through cut dentine was recorded by a pressure transducer after each of the stages described (A to E). The mean rate of pressure change across dentine (Pa s(-1)) for each measurement point (A to E) (n = 30) were A = 2.3; B = 9.8; C = 16; D = 2.1; E = 3.1. Acid etching and NaOCl were both effective in producing significant increases in the rate of pressure change across dentine (P < 0.05). Sensodyne sealant and Scotchbond Multipurpose are both effective dentine sealants and there is no significant difference (P > 0.05) in their abilities in sealing dentine. Acid etching-sealed dentine produced a significant increase in the rate of pressure change across dentine (P < 0.05). The sealing of dentine appears to be a sensible consideration following crown preparations on vital teeth. PMID:15899020

  11. Ferric carboxymaltose with or without erythropoietin for the prevention of red-cell transfusions in the perioperative period of osteoporotic hip fractures: a randomized contolled trial. The PAHFRAC-01 project

    PubMed Central

    2012-01-01

    Background Around one third to one half of patients with hip fractures require red-cell pack transfusion. The increasing incidence of hip fracture has also raised the need for this scarce resource. Additionally, red-cell pack transfusions are not without complications which may involve excessive morbidity and mortality. This makes it necessary to develop blood-saving strategies. Our objective was to assess safety, efficacy, and cost-effictveness of combined treatment of i.v. ferric carboxymaltose and erythropoietin (EPOFE arm) versus i.v. ferric carboxymaltose (FE arm) versus a placebo (PLACEBO arm) in reducing the percentage of patients who receive blood transfusions, as well as mortality in the perioperative period of hip fracture intervention. Methods/Design Multicentric, phase III, randomized, controlled, double blinded, parallel groups clinical trial. Patients > 65 years admitted to hospital with a hip fracture will be eligible to participate. Patients will be treated with either a single dosage of i.v. ferric carboxymaltose of 1 g and subcutaneous erythropoietin (40.000 IU), or i.v. ferric carboxymaltose and subcutaneous placebo, or i.v. placebo and subcutaneous placebo. Follow-up will be performed until 60 days after discharge, assessing transfusion needs, morbidity, mortality, safety, costs, and health-related quality of life. Intention to treat, as well as per protocol, and incremental cost-effectiveness analysis will be performed. The number of recruited patients per arm is set at 102, a total of 306 patients. Discussion We think that this trial will contribute to the knowledge about the safety and efficacy of ferric carboxymaltose with/without erythropoietin in preventing red-cell pack transfusions in patients with hip fracture. ClinicalTrials.gov identifier: NCT01154491. PMID:22353604

  12. Kinetic and equilibrium studies of acrylonitrile binding to cytochrome c peroxidase and oxidation of acrylonitrile by cytochrome c peroxidase compound I

    SciTech Connect

    Chinchilla, Diana, E-mail: Diana_Chinchilla@yahoo.com; Kilheeney, Heather, E-mail: raindropszoo@yahoo.com; Vitello, Lidia B., E-mail: lvitello@niu.edu; Erman, James E., E-mail: jerman@niu.edu

    2014-01-03

    Highlights: •Cytochrome c peroxidase (CcP) binds acrylonitrile in a pH-independent fashion. •The spectrum of the CcP/acrylonitrile complex is that of a 6c–ls ferric heme. •The acrylonitrile/CcP complex has a K{sub D} value of 1.1 ± 0.2 M. •CcP compound I oxidizes acrylonitrile with a maximum turnover rate of 0.61 min{sup ?1}. -- Abstract: Ferric heme proteins bind weakly basic ligands and the binding affinity is often pH dependent due to protonation of the ligand as well as the protein. In an effort to find a small, neutral ligand without significant acid/base properties to probe ligand binding reactions in ferric heme proteins we were led to consider the organonitriles. Although organonitriles are known to bind to transition metals, we have been unable to find any prior studies of nitrile binding to heme proteins. In this communication we report on the equilibrium and kinetic properties of acrylonitrile binding to cytochrome c peroxidase (CcP) as well as the oxidation of acrylonitrile by CcP compound I. Acrylonitrile binding to CcP is independent of pH between pH 4 and 8. The association and dissociation rate constants are 0.32 ± 0.16 M{sup ?1} s{sup ?1} and 0.34 ± 0.15 s{sup ?1}, respectively, and the independently measured equilibrium dissociation constant for the complex is 1.1 ± 0.2 M. We have demonstrated for the first time that acrylonitrile can bind to a ferric heme protein. The binding mechanism appears to be a simple, one-step association of the ligand with the heme iron. We have also demonstrated that CcP can catalyze the oxidation of acrylonitrile, most likely to 2-cyanoethylene oxide in a “peroxygenase”-type reaction, with rates that are similar to rat liver microsomal cytochrome P450-catalyzed oxidation of acrylonitrile in the monooxygenase reaction. CcP compound I oxidizes acrylonitrile with a maximum turnover number of 0.61 min{sup ?1} at pH 6.0.

  13. Lipoic acid and acetyl-carnitine reverse iron-induced oxidative stress in human fibroblasts.

    PubMed

    Lal, Ashutosh; Atamna, Wafa; Killilea, David W; Suh, Jung H; Ames, Bruce N

    2008-01-01

    Iron overload occurs frequently in thalassemia and other disorders that require regular blood transfusions. Excess iron is toxic owing to the generation of free radicals that lead to oxidation of biomolecules and tissue damage. In order to identify compounds that reduce oxidative injury from iron, we evaluated alpha-lipoic acid (LA), a multifunctional antioxidant, in iron-overloaded primary human fibroblasts (IMR-90). Oxidant stress was measured using dichlorodihydrofluorescein diacetate that is converted to the fluorescent dichlorofluorescein (DCF) upon oxidation. Exposure to ferric ammonium citrate (FAC) increased the iron-content of IMR-90 cells and caused a rise in oxidant appearance. The addition of LA improved the cellular redox status and attenuated the iron-mediated rise in oxidants in a dose-dependent manner. The R- and RS-enantiomers of LA demonstrated similar antioxidant activity. N-tert-butyl hydroxylamine (NtBHA) treated cells also exhibited a decrease in DCF fluorescence, but at a much higher concentration compared with LA. The combination acetyl-L-carnitine (ALCAR) and LA exhibited superior antioxidant effect at all dose levels. We conclude that LA is highly effective in reversing oxidative stress arising from iron overload and that its antioxidant efficacy is further enhanced in combination with ALCAR. PMID:18284845

  14. Ferric iron in sediments as a novel CO2 mineral trap: CO 2-SO2 reaction with hematite

    USGS Publications Warehouse

    Palandri, J.L.; Rosenbauer, R.J.; Kharaka, Y.K.

    2005-01-01

    Thermodynamic simulations of reactions among SO2-bearing CO 2-dominated gas, water and mineral phases predict that Fe III in sediments should be converted almost entirely to dissolved FeII and siderite (FeCO3), and that SO2 should simultaneously be oxidized to dissolved sulfate. The reactions are however, subject to kinetic constraints which may result in deviation from equilibrium and the precipitation of other metastable mineral phases. To test the prediction, a laboratory experiment was carried out in a well stirred hydrothermal reactor at 150??C and 300 bar with hematite, 1.0 m NaCl, 0.5 m NaOH, SO2 in quantity sufficient to reduce much of the iron, and excess CO2. The experiment produced stable siderite and metastable pyrite and elemental S. Changes in total dissolved Fe are consistent with nucleation of pyrite at ???17 h, and nucleation of siderite at ???600 h. Dissolution features present on elemental S at the conclusion of the experiment suggest nucleation early in the experiment. The experiment did not reach equilibrium after ???1400 h, as indicated by coexistence of hematite with metastable pyrite and elemental sulfur. However, the results confirm that FeIII can be used to trap CO2 in siderite if partly oxidized S, as SO2, is present to reduce the Fe with CO2 in the gas phase. ?? 2005 Elsevier Ltd. All rights reserved.

  15. Ferrous iron oxidation by molecular oxygen under acidic conditions: The effect of citrate, EDTA and fulvic acid

    NASA Astrophysics Data System (ADS)

    Jones, Adele M.; Griffin, Philippa J.; Waite, T. David

    2015-07-01

    In this study, the rates of Fe(II) oxidation by molecular oxygen in the presence of citrate, ethylenediaminetetraacetic acid (EDTA) and Suwannee River fulvic acid (SRFA) were determined over the pH range 4.0-5.5 and, for all of the ligands investigated, found to be substantially faster than oxidation rates in the absence of any ligand. EDTA was found to be particularly effective in enhancing the rate of Fe(II) oxidation when sufficient EDTA was available to complex all Fe(II) present in solution, with a kinetic model of the process found to adequately describe all results obtained. When Fe(II) was only partially complexed by EDTA, reactions with reactive oxygen species (ROS) and heterogeneous Fe(II) oxidation were found to contribute significantly to the removal rate of iron from solution at different stages of oxidation. This was possible due to the rapid rate at which EDTA enhanced Fe(II) oxidation and formed ROS and Fe(III). The rapid rate of Fe(III) generation facilitated the formation of free ferric ion activities in excess of those required for ferric oxyhydroxide precipitation following Fe(III)-EDTA dissociation. In comparison, the rate of Fe(II) oxidation was slower in the presence of citrate, and therefore the concentrations of free Fe(III) able to form in the initial stages of Fe(II) oxidation were much lower than those formed in the presence of EDTA, despite the resultant Fe(III)-citrate complex being less stable than that of Fe(III)-EDTA. The slower rate of citrate enhanced oxidation also resulted in slower rates of ROS generation, and, as such, oxidation of the remaining inorganic Fe(II) species by ROS was negligible. Overall, this study demonstrates that organic ligands may substantially enhance the rate of Fe(II) oxidation. Even under circumstances where the ligand is not present at sufficient concentrations to complex all of the Fe(II) in solution, ensuing oxidative processes may sustain an enhanced rate of Fe(II) oxidation relative to that of aqueous Fe(II) oxidation alone.

  16. Ultrahigh Capacity Due to Multi-Electron Conversion Reaction in Reduced Graphene Oxide-Wrapped MoO2 Porous Nanobelts.

    PubMed

    Tang, Wei; Peng, Cheng Xin; Nai, Chang Tai; Su, Jie; Liu, Yan Peng; Reddy, M V Venkatashamy; Lin, Ming; Loh, Kian Ping

    2015-05-01

    Multivalent transition metal oxides (MOx ) containing redox centers which can theoretically accept more than one electron have been suggested as promising anode materials for high-performance lithium ion batteries (LIBs). The Li-storage mechanism of these oxides is suggested to involve an unusual conversion reaction leading to the formation of metallic nanograins and Li2 O; however, a full-scale conversion reaction is seldom observed in molybdenum dioxide (MoO2 ) at room temperature due to slow kinetics. Herein, a full-scale multi-electron conversion reaction, leading to a high reversible capacity (974 mA h g(-1) charging capacity at 60 mA g(-1) ) in LIBs, is realized in a hybrid consisting of reduced graphene oxide (rGO) sheet-wrapped MoO2 porous nanobelts (rGO/MoO2 NBs). The rGO wrapping layers stabilize the nanophase transition in MoO2 and alleviate volume swing effects during lithiation/delithiation processes. This enables the hybrid to exhibit great cycle stability (tested to around 1900 cycles) and ultrafast rate capability (tested up to 50 A g(-1) ). PMID:25620728

  17. Oxidation of dissolved iron under warmer, wetter conditions on Mars: Transitions to present-day arid environments

    NASA Technical Reports Server (NTRS)

    Burns, R. G.

    1993-01-01

    The copious deposits of ferric-iron assemblages littering the surface of bright regions of Mars indicate that efficient oxidative weathering reactions have taken place during the evolution of the planet. Because the kinetics of atmosphere-surface (gas-solid) reactions are considerably slower than chemical weathering reactions involving an aqueous medium, most of the oxidation products now present in the martian regolith probably formed when groundwater flowed near the surface. This paper examines how chemical weathering reactions were effected by climatic variations when warm, wet environments became arid on Mars. Analogies are drawn with hydrogeochemical and weathering environments on the Australian continent where present-day oxidation of iron is occurring in acidic ground water under arid conditions.

  18. Relation between plasmatic and cerebrospinal fluid oxidative stress biomarkers and intrathecal Ig synthesis in Multiple Sclerosis patients.

    PubMed

    Pasquali, Livia; Pecori, Chiara; Chico, Lucia; Iudice, Alfonso; Siciliano, Gabriele; Bonuccelli, Ubaldo

    2015-06-15

    The aim of this study was to evaluate if cerebrospinal fluid (CSF) oxidative stress biomarkers were related to plasmatic levels and to intrathecal Ig synthesis in 51 patients with Multiple Sclerosis (MS) or clinically isolated syndrome (CIS). Plasmatic and CSF ferric reducing ability (FRA) showed a significant positive correlation (? 0.28, p=0.04), while advanced oxidation protein products (AOPPs) did not. A negative correlation was found between IgG synthesis index and CSF FRA levels. No difference in CSF AOPPs or FRA was observed between patients with and without intrathecal IgM synthesis. Our results indicate that plasmatic and CSF FRA are strictly linked, while CSF oxidative stress biomarkers are not related to intrathecal Ig synthesis. PMID:26004154

  19. Two kinds of ferritin protect ixodid ticks from iron overload and consequent oxidative stress.

    PubMed

    Galay, Remil Linggatong; Umemiya-Shirafuji, Rika; Bacolod, Eugene T; Maeda, Hiroki; Kusakisako, Kodai; Koyama, Jiro; Tsuji, Naotoshi; Mochizuki, Masami; Fujisaki, Kozo; Tanaka, Tetsuya

    2014-01-01

    Ticks are obligate hematophagous parasites that have successfully developed counteractive means against their hosts' immune and hemostatic mechanisms, but their ability to cope with potentially toxic molecules in the blood remains unclear. Iron is important in various physiological processes but can be toxic to living cells when in excess. We previously reported that the hard tick Haemaphysalis longicornis has an intracellular (HlFER1) and a secretory (HlFER2) ferritin, and both are crucial in successful blood feeding and reproduction. Ferritin gene silencing by RNA interference caused reduced feeding capacity, low body weight and high mortality after blood meal, decreased fecundity and morphological abnormalities in the midgut cells. Similar findings were also previously reported after silencing of ferritin genes in another hard tick, Ixodes ricinus. Here we demonstrated the role of ferritin in protecting the hard ticks from oxidative stress. Evaluation of oxidative stress in Hlfer-silenced ticks was performed after blood feeding or injection of ferric ammonium citrate (FAC) through detection of the lipid peroxidation product, malondialdehyde (MDA) and protein oxidation product, protein carbonyl. FAC injection in Hlfer-silenced ticks resulted in high mortality. Higher levels of MDA and protein carbonyl were detected in Hlfer-silenced ticks compared to Luciferase-injected (control) ticks both after blood feeding and FAC injection. Ferric iron accumulation demonstrated by increased staining on native HlFER was observed from 72 h after iron injection in both the whole tick and the midgut. Furthermore, weak iron staining was observed after Hlfer knockdown. Taken together, these results show that tick ferritins are crucial antioxidant molecules that protect the hard tick from iron-mediated oxidative stress during blood feeding. PMID:24594832

  20. Two Kinds of Ferritin Protect Ixodid Ticks from Iron Overload and Consequent Oxidative Stress

    PubMed Central

    Galay, Remil Linggatong; Umemiya-Shirafuji, Rika; Bacolod, Eugene T.; Maeda, Hiroki; Kusakisako, Kodai; Koyama, Jiro; Tsuji, Naotoshi; Mochizuki, Masami; Fujisaki, Kozo; Tanaka, Tetsuya

    2014-01-01

    Ticks are obligate hematophagous parasites that have successfully developed counteractive means against their hosts' immune and hemostatic mechanisms, but their ability to cope with potentially toxic molecules in the blood remains unclear. Iron is important in various physiological processes but can be toxic to living cells when in excess. We previously reported that the hard tick Haemaphysalis longicornis has an intracellular (HlFER1) and a secretory (HlFER2) ferritin, and both are crucial in successful blood feeding and reproduction. Ferritin gene silencing by RNA interference caused reduced feeding capacity, low body weight and high mortality after blood meal, decreased fecundity and morphological abnormalities in the midgut cells. Similar findings were also previously reported after silencing of ferritin genes in another hard tick, Ixodes ricinus. Here we demonstrated the role of ferritin in protecting the hard ticks from oxidative stress. Evaluation of oxidative stress in Hlfer-silenced ticks was performed after blood feeding or injection of ferric ammonium citrate (FAC) through detection of the lipid peroxidation product, malondialdehyde (MDA) and protein oxidation product, protein carbonyl. FAC injection in Hlfer-silenced ticks resulted in high mortality. Higher levels of MDA and protein carbonyl were detected in Hlfer-silenced ticks compared to Luciferase-injected (control) ticks both after blood feeding and FAC injection. Ferric iron accumulation demonstrated by increased staining on native HlFER was observed from 72 h after iron injection in both the whole tick and the midgut. Furthermore, weak iron staining was observed after Hlfer knockdown. Taken together, these results show that tick ferritins are crucial antioxidant molecules that protect the hard tick from iron-mediated oxidative stress during blood feeding. PMID:24594832