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Sample records for fe floc part

  1. Size and structure of Chlorella zofingiensis /FeCl 3 flocs in a shear flow: Algae Floc Structure

    Energy Technology Data Exchange (ETDEWEB)

    Wyatt, Nicholas B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); O' Hern, Timothy J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Shelden, Bion [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hughes, Lindsey G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mondy, Lisa A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-07-26

    Flocculation is a promising method to overcome the economic hurdle to separation of algae from its growth medium in large scale operations. But, understanding of the floc structure and the effects of shear on the floc structure are crucial to the large scale implementation of this technique. The floc structure is important because it determines, in large part, the density and settling behavior of the algae. Freshwater algae floc size distributions and fractal dimensions are presented as a function of applied shear rate in a Couette cell using ferric chloride as a flocculant. Comparisons are made with measurements made for a polystyrene microparticle model system taken here as well as reported literature results. The algae floc size distributions are found to be self-preserving with respect to shear rate, consistent with literature data for polystyrene. Moreover, three fractal dimensions are calculated which quantitatively characterize the complexity of the floc structure. Low shear rates result in large, relatively dense packed flocs which elongate and fracture as the shear rate is increased. Our results presented here provide crucial information for economically implementing flocculation as a large scale algae harvesting strategy.

  2. Fe(II)-regulated moderate pre-oxidation of Microcystis aeruginosa and formation of size-controlled algae flocs for efficient flotation of algae cell and organic matter.

    Science.gov (United States)

    Qi, Jing; Lan, Huachun; Liu, Ruiping; Liu, Huijuan; Qu, Jiuhui

    2018-06-15

    The coagulation/flocculation/flotation (C/F/F) process is becoming a popular method for algae-laden water treatment. However, the efficiency of flotation is highly dependent on the ability of the preceding coagulation/flocculation process to form flocculated algae flocs. This study aims to improve the Microcystis aeruginosa flotation efficiency from algae cell and organic matter aspects by applying Fe(II)-regulated pretreatment enhanced Al coagulation process. The ability of the C/F/F process to remove cyanobacterial cells can be enhanced from 8% to 99% at a Fe(II) dose of 30 μM. The Al dose needed can be reduced by more than half while achieving successful flotation. The introduced Fe(II) after KMnO 4 can not only realize moderate pre-oxidation of cyanobacterial cells, but also form in-situ Fe(III). The DOC value can also be decreased significantly due to the formation of in-situ Fe(III), which is more efficient in dissolved organic matter (DOM) removal compared with pre-formed Fe(III). In addition, the gradually hydrolyzed in-situ Fe(III) can facilitate the hydrolysis of Al as a dual-coagulant and promote the clustering and cross-linking of Al hydrolyzates, which can enhance the formation of size-controlled algae flocs. Finally, the size-controlled algae flocs can be effectively floated by the bubbles released in the flotation process due to the efficient collision and attachment between flocs and bubbles. Therefore, the efficient flotation of algae cell and organic matter can be realized by the Fe(II) regulated moderate pre-oxidation of M. aeruginosa and formation of size-controlled algae flocs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Coagulation performance and floc characteristics of polytitanium tetrachloride (PTC) compared with titanium tetrachloride (TiCl4) and ferric chloride (FeCl3) in algal turbid water

    KAUST Repository

    Chekli, L.

    2016-11-11

    Seasonal green algae blooms in freshwaters have raised attention on the need to develop novel effective treatment processes for the removal of algae in water. In the present study, the performance of newly developed polytitanium tetrachloride (PTC) coagulant for the removal of freshwater microalga Chlorella vulgaris has been investigated and compared with titanium tetrachloride (TiCl4) coagulant and the conventional ferric chloride (FeCl3) coagulant. The main benefit of using titanium-based coagulants is that the sludge produced after flocculation may be recycled into a valuable product: titanium dioxide photocatalyst. Both titanium-based coagulants achieved good flocculation over a broader pH range and coagulant dose compared to conventional FeCl3 coagulant. All three coagulants achieved comparable performance in terms of turbidity removal (i.e. turbidity removal efficiency >97%); although TiCl4 performed slightly better at the lower tested dose (i.e. <9 mg/L). Zeta potential measurements indicated that charge neutralisation may not be the sole mechanism involved in the coagulation of algae for all three coagulants. Analysis of the dynamic floc size variation during floc breakage showed no regrowth after floc breakage for the three coagulants. The flocs formed by both Ti-based coagulants were larger than those formed by FeCl3 and also grew at a faster rate. This study indicates that Ti-based coagulants are effective and promising coagulants for algae removal in water.

  4. Synthesis and absorbing mechanism of two-layer microwave absorbers containing flocs-like nano-BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27} and carbonyl iron

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Miaojie, E-mail: qmj1933@sina.com [Faculty of Material Science, Materials Science and Engineering School, Beihang University, Beijing 100191 (China); No. 33rd Research Institute of China Electronics Technology Group Corporation, Taiyuan 030006 (China); Zhang, Cunrui, E-mail: zcr19831616@sina.com [Faculty of Material Science, Materials Science and Engineering School, Beihang University, Beijing 100191 (China); No. 33rd Research Institute of China Electronics Technology Group Corporation, Taiyuan 030006 (China); Jia, Haiye [Faculty of Material Science, Materials Science and Engineering School, Beihang University, Beijing 100191 (China); No. 33rd Research Institute of China Electronics Technology Group Corporation, Taiyuan 030006 (China)

    2012-08-15

    Flocs-like nano-barium ferrite (BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27}) was synthesized by sol-gel method using the absorbent cotton as template for the first time. A possible mechanism for the formation of flocs-like nano-barium ferrite had been proposed. Two-layer microwave nano-BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27}/carbonyl iron composite has been prepared by as-prepared material. The structure, morphology and properties of the composites are characterized with X-ray diffraction (XRD), scanning electron microscope (SEM), Net-work Analyzer. The complex permittivity and reflection loss (dB) of the composites have been measured at different microwave frequencies from 30 MHz to 6000 MHz employing vector network analyzer model PNA 3629D vector. The effect of the layer thickness of carbonyl iron on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of nano-BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27}/carbonyl iron composite has been proposed. The nano-BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27}/carbonyl iron composite can find applications in suppression of electromagnetic interference (EMI), and reduction of radar signature. -- Highlights: Black-Right-Pointing-Pointer Flocs-like BaZn{sub 1.5}Co{sub 0.5}Fe{sub 16}O{sub 27} was synthesized for the first time. Black-Right-Pointing-Pointer A possible formation mechanism for flocs-like ferrite had been proposed. Black-Right-Pointing-Pointer Two-layer microwave composite has been prepared. Black-Right-Pointing-Pointer A possible microwave absorbing mechanism of the composite has been proposed.

  5. Sequestration of phosphorus by acid mine drainage floc

    Science.gov (United States)

    Adler, P.R.; Sibrell, P.L.

    2003-01-01

    Solubilization and transport of phosphorus (P) to the water environment is a critical environmental issue. Flocs resulting from neutralizing acid mine drainage (AMD) were tested as a possible lowcost amendment to reduce the loss of soluble P from agricultural fields and animal wastewater. Flocs were prepared by neutralizing natural and synthetic solutions of AMD with limestone, lime, ammonium hydroxide, and sodium hydroxide. Phosphorus sequestration was tested in three distinct environments: water, soil, and manure storage basins. In water, flocs prepared from AMD adsorbed 10 to 20 g P kg-1 dry floc in equilibrium with 1 mg L-1 soluble P. Similar results were observed for both Fe-based and A1-based synthetic flocs. A local soil sample adsorbed about 0.1 g P kg-1, about two orders of magnitude less. The AMD-derived flocs were mixed with a highP soil at 5 to 80 g floc kg-1 soil, followed by water and acid (Mehlich1) extractions. All flocs performed similarly. About 70% of the waterextractable P was sequestered by the floc when applied at a rate of 20 g floc kg-1 soil, whereas plant-available P only decreased by about 30%. Under anaerobic conditions simulating manure storage basins, all AMD flocs reduced soluble P by greater than 95% at a rate of 0.2 g floc g-1 rainbow trout (Oncorhynchus mykiss) manure. These findings indicate that AMD flocs could be an effective agent for preventing soluble P losses from soil and manure to the water environment, while at the same time decreasing the costs associated with AMD treatment.

  6. Performance of titanium salts compared to conventional FeCl 3 for the removal of algal organic matter (AOM) in synthetic seawater: Coagulation performance, organic fraction removal and floc characteristics

    KAUST Repository

    Chekli, L.

    2017-06-20

    During algal bloom periods, operation of seawater reverse osmosis (SWRO) pretreatment processes (e.g. ultrafiltration (UF)) has been hindered due to the high concentration of algal cells and algal organic matter (AOM). The present study evaluated for the first time the performance of titanium salts (i.e. titanium tetrachloride (TiCl4) and polytitanium tetrachloride (PTC)) for the removal of AOM in seawater and results were compared with the conventional FeCl3 coagulant. Previous studies already demonstrated that titanium salts not only provide a cost-effective alternative to conventional coagulants by producing a valuable by-product but also minimise the environmental impact of sludge production. Results from this study showed that both TiCl4 and PTC achieved better performance than FeCl3 in terms of turbidity, UV254 and dissolved organic carbon (DOC) removal at similar coagulant dose. Liquid chromatography – organic carbon detection (LC-OCD) was used to determine the removal of AOM compounds based on their molecular weight (MW). This investigation revealed that both humic substances and low MW organics were preferentially removed (i.e. up to 93% removal) while all three coagulants showed poorer performance for the removal of high MW biopolymers (i.e. less than 50% removal). The detailed characterization of flocs indicated that both titanium coagulants can grow faster, reach larger size and present a more compact structure, which is highly advantageous for the design of smaller and more compact mixing and sedimentation tanks. Both titanium coagulants also presented a higher ability to withstand shear force, which was related to the higher amount of DOC adsorbed with the aggregated flocs. Finally, TiCl4 had a better recovery after breakage suggesting that charge neutralization may be the dominant mechanism for this coagulant, while the lower recovery of both PTC and FeCl3 indicated that sweep flocculation is also a contributing mechanism for the coagulation of AOM.

  7. Performance of titanium salts compared to conventional FeCl3for the removal of algal organic matter (AOM) in synthetic seawater: Coagulation performance, organic fraction removal and floc characteristics.

    Science.gov (United States)

    Chekli, L; Corjon, E; Tabatabai, S A A; Naidu, G; Tamburic, B; Park, S H; Shon, H K

    2017-10-01

    During algal bloom periods, operation of seawater reverse osmosis (SWRO) pretreatment processes (e.g. ultrafiltration (UF)) has been hindered due to the high concentration of algal cells and algal organic matter (AOM). The present study evaluated for the first time the performance of titanium salts (i.e. titanium tetrachloride (TiCl 4 ) and polytitanium tetrachloride (PTC)) for the removal of AOM in seawater and results were compared with the conventional FeCl 3 coagulant. Previous studies already demonstrated that titanium salts not only provide a cost-effective alternative to conventional coagulants by producing a valuable by-product but also minimise the environmental impact of sludge production. Results from this study showed that both TiCl 4 and PTC achieved better performance than FeCl 3 in terms of turbidity, UV 254 and dissolved organic carbon (DOC) removal at similar coagulant dose. Liquid chromatography - organic carbon detection (LC-OCD) was used to determine the removal of AOM compounds based on their molecular weight (MW). This investigation revealed that both humic substances and low MW organics were preferentially removed (i.e. up to 93% removal) while all three coagulants showed poorer performance for the removal of high MW biopolymers (i.e. less than 50% removal). The detailed characterization of flocs indicated that both titanium coagulants can grow faster, reach larger size and present a more compact structure, which is highly advantageous for the design of smaller and more compact mixing and sedimentation tanks. Both titanium coagulants also presented a higher ability to withstand shear force, which was related to the higher amount of DOC adsorbed with the aggregated flocs. Finally, TiCl 4 had a better recovery after breakage suggesting that charge neutralization may be the dominant mechanism for this coagulant, while the lower recovery of both PTC and FeCl 3 indicated that sweep flocculation is also a contributing mechanism for the coagulation

  8. Investigation of the shape change of bio-flocs and its influence on mass transport using particle image velocimetry.

    Science.gov (United States)

    Ren, T T; Xiao, F; Sun, W J; Sun, F Y; Lam, K M; Li, X Y

    2014-01-01

    In this laboratory study, an advanced flow visualization technique - particle image velocimetry (PIV) - was employed to investigate the change of shape of activated sludge flocs in water and its influence on the material transport characteristics of the flocs. The continuous shape change of the bio-flocs that occurred within a very short period of time could be captured by the PIV system. The results demonstrate that the fluid turbulence caused the shift of parts of a floc from one side to the other in less than 200 ms. During the continuous shape change, the liquid within the floc was forced out of the floc, which was then refilled with the liquid from the surrounding flow. For the bio-flocs saturated with a tracer dye, it was shown that the dye could be released from the flocs at a faster rate when the flocs were swayed around in water. The experimental results indicate that frequent shape change of bio-flocs facilitates the exchange of fluid and materials between the floc interior and the surrounding water. This mass transfer mechanism can be more important than molecular diffusion and internal permeation to the function and behavior of particle aggregates, including bio-flocs, in natural waters and treatment systems.

  9. Ferrihydrite flocs, native copper nanocrystals and spontaneous remediation in the Fosso dei Noni stream, Tuscany, Italy

    International Nuclear Information System (INIS)

    Genovese, Alessandro; Mellini, Marcello

    2007-01-01

    The Fosso dei Noni stream drains the abandoned mixed-sulfide mining area of Fenice Capanne in Italy. Water pollution mostly derives from two tributaries, one of which adds Cu and the other Zn. Downstream, water pollution is progressively remediated through the spontaneous precipitation of abundant, deeply-colored flocs. Within 1 km, flocs change from yellow-red to whitish and green, as the pH increases from 4.59 to 7.70 and the Eh decreases from +311 to +165 mV. Flocs are initially amorphous; with a near-neutral pH, their X-ray diffraction properties suggest the presence of two-line ferrihydrite. Transmission electron microscopy reveals major nanotextural modifications in flocs along the entire stream. Upstream, flocs consist of globular particles with a radius of 25-50 nm. Downstream, they change to globular particles with elongated features. Lastly, further downstream, flocs consist of elongated features interconnected by continuous films. Nanochemical data are consistent with Al and Fe hydroxides (largely contaminated by S, Si, Ca, Cu and Zn); the Cu content increases progressively downstream to a maximum of 18 at. %. The increasing Cu content is paralleled by the appearance of isolated Cu nanocrystals adsorbed on floc surfaces. Spontaneous processes in the Fosso dei Noni stream (water neutralization, formation of ferrihydrite-like flocs and crystallization of native Cu) allow the temporary storage of Cu, providing hints on how to optimize remediation processes and Cu recovery

  10. Influence of microbial acitivity on the stability of activated sludge flocs

    DEFF Research Database (Denmark)

    Wilén, Britt-Marie; Nielsen, Jeppe Lund; Keiding, Kristian

    2000-01-01

    activity. When anaerobic conditions prevailed, a microbial iron reduction immediately started with iron reduction rates of 4–150 μmol/gVS·h. Subsequently, a decrease in floc strength was observed which could also be observed when the iron-reducing bacterium Shewanella alga BrY was added to the activated...... sludge. Furthermore, the importance of Fe(III) for the floc strength was illustrated by removal of Fe(III) from the sludge matrix by adding sulphide, which resulted in strong deflocculation. Thus, the deflocculation observed could be either directly due to lack of aerobic microbial activity or indirectly...

  11. Iron(II)-Catalyzed Iron Atom Exchange and Mineralogical Changes in Iron-rich Organic Freshwater Flocs: An Iron Isotope Tracer Study.

    Science.gov (United States)

    ThomasArrigo, Laurel K; Mikutta, Christian; Byrne, James; Kappler, Andreas; Kretzschmar, Ruben

    2017-06-20

    In freshwater wetlands, organic flocs are often found enriched in trace metal(loid)s associated with poorly crystalline Fe(III)-(oxyhydr)oxides. Under reducing conditions, flocs may become exposed to aqueous Fe(II), triggering Fe(II)-catalyzed mineral transformations and trace metal(loid) release. In this study, pure ferrihydrite, a synthetic ferrihydrite-polygalacturonic acid coprecipitate (16.7 wt % C), and As- (1280 and 1230 mg/kg) and organic matter (OM)-rich (18.1 and 21.8 wt % C) freshwater flocs dominated by ferrihydrite and nanocrystalline lepidocrocite were reacted with an isotopically enriched 57 Fe(II) solution (0.1 or 1.0 mM Fe(II)) at pH 5.5 and 7. Using a combination of wet chemistry, Fe isotope analysis, X-ray absorption spectroscopy (XAS), 57 Fe Mössbauer spectroscopy and X-ray diffraction, we followed the Fe atom exchange kinetics and secondary mineral formation over 1 week. When reacted with Fe(II) at pH 7, pure ferrihydrite exhibited rapid Fe atom exchange at both Fe(II) concentrations, reaching 76 and 89% atom exchange in experiments with 0.1 and 1 mM Fe(II), respectively. XAS data revealed that it transformed into goethite (21%) at the lower Fe(II) concentration and into lepidocrocite (73%) and goethite (27%) at the higher Fe(II) concentration. Despite smaller Fe mineral particles in the coprecipitate and flocs as compared to pure ferrihydrite (inferred from Mössbauer-derived blocking temperatures), these samples showed reduced Fe atom exchange (9-30% at pH 7) and inhibited secondary mineral formation. No release of As was recorded for Fe(II)-reacted flocs. Our findings indicate that carbohydrate-rich OM in flocs stabilizes poorly crystalline Fe minerals against Fe(II)-catalyzed transformation by surface-site blockage and/or organic Fe(II) complexation. This hinders the extent of Fe atom exchange at mineral surfaces and secondary mineral formation, which may consequently impair Fe(II)-activated trace metal(loid) release. Thus, under short

  12. The role of lipids in activated sludge floc formation

    OpenAIRE

    Anna Liza Kretzschmar; Mike Manefield

    2015-01-01

    Activated sludge is widely used to treat municipal and industrial wastewater globally and the formation of activated sludge flocculates (flocs) underpins the ability to separate sludge from treated water. Despite the importance of activated sludge flocs to human civilization there have been precious few attempts to rationally design fit for purpose flocs using a bottom-up approach based on a solid scientific foundation. Recently we have been developing experimental models for activated sludge...

  13. Properties of sediment-algae flocs as function of shear and environmental conditions : a laboratory study

    Science.gov (United States)

    Deng, Z.; He, Q.; Chassagne, C.; Manning, A. J.

    2017-12-01

    It has been observed that flocculation in-situ is greatly influenced by biochemical parameters[De Lucas Pardo, 2014]. In our previous work [Deng, 2017], we have found that flocs observed in the Yangtze Estuary are composed of mixtures of sediment and algae. In particular we have shown that flocs can be composed solely of algae aggregates. Depending on their position in the water column, the composition of flocs changes, as more or less sediment can be part of the floc. The presence of algae (phytoplankton biomass) in a floc is linked to the measured chlorophyll α concentration [Uncles et al., 1998]. The Particle Size Distribution (PSD) found in-situ depends on parameters such as position in the water column and shear rate, and also seasons. We showed that the PSD found in-situ is similar to the one measured in the lab, for the same floc composition and environmental conditions. In the present work we extend the laboratory investigations by analysing the impact of the floc history on its PSD. The PSD can be bimodal after a grow-break-up-regrow phase, indicating that flocs growth process depend on a timescale that is larger than the timescale associated to the change in shear rate. We will discuss the behaviour of the parameters needed in the flocculation model we propose upon the relevant variables. The ultimate goal is to propose a model that can be implemented in large scale sediment transport models. ReferencesDe Lucas Pardo, M. (2014), Effect of biota on fine sediment transport processes: A study of Lake Markermeer, TU Delft, Delft University of Technology. Deng, Z. (2017), Algae effects on cohesive sediment flocculation: a case study based on field observation in Yangtze Estuary, China (submitted)Uncles, R., A. Easton, M. Griffiths, C. Harris, R. Howland, I. Joint, R. King, A. Morris, and D. Plummer (1998), Concentrations of suspended chlorophyll in the tidal Yorkshire Ouse and Humber Estuary, Science of The Total Environment, 210-211, 367-375, doi:10.1016/s

  14. Impact of sludge flocs on membrane fouling in membrane bioreactors

    DEFF Research Database (Denmark)

    Christensen, Morten Lykkegaard; Niessen, Wolfgang; Jørgensen, Mads Koustrup

    of divalent ions such as calcium and iron. Furthermore, it was shown that the ratio between cations and EPS was important for the fouling potential of the sludge. A high ratio between divalent ions and EPS reduced membrane fouling as soluble EPS were adsorbed and bound within the sludge flocs. Strong compact...... flocs reduced membrane fouling, and more compact and strong flocs were formed if the concentration of divalent ions were high. Sludge was fractionated by centrifugation providing supernatant with soluble EPS and colloidal particles but without flocs. Filtration test on untreated sludge and supernatant...

  15. The role of lipids in activated sludge floc formation

    Directory of Open Access Journals (Sweden)

    Anna Liza Kretzschmar

    2015-03-01

    Full Text Available Activated sludge is widely used to treat municipal and industrial wastewater globally and the formation of activated sludge flocculates (flocs underpins the ability to separate sludge from treated water. Despite the importance of activated sludge flocs to human civilization there have been precious few attempts to rationally design fit for purpose flocs using a bottom-up approach based on a solid scientific foundation. Recently we have been developing experimental models for activated sludge floc formation based on the colonization and consumption of particulate organic matter (chitin and cellulose. In this study we lay the foundation for investigation of activated sludge floc formation based on biofilm formation around spheres of the lipid glycerol trioleate (GT that form spontaneously when GT is introduced into activated sludge incubations. Sludge biomass was observed to associate tightly with the lipid spheres. An increase in extracellular lipase activity was associated with a decrease in size of the colonized lipid spheres over a 25 day incubation. Bacterial community composition shifted from predominantly Betaproteobacteria to Alphaproteobacteria in GT treated sludge. Four activated sludge bacteria were isolated from lipid spheres and two of them were shown to produce AHL like quorum sensing signal activity, suggesting quorum sensing may play a role in lipid spheres colonization and biodegradation in activated sludge. The development of this experimental model of activated sludge floc formation lays the foundation for rational production of flocs for wastewater treatment using lipids as floc nuclei and further development of the flocculate life-cycle concept.

  16. Use of DAIME for characterisation of activated sludge flocs

    Directory of Open Access Journals (Sweden)

    Gnida Anna

    2017-12-01

    Full Text Available Monitoring of activated sludge flocs may provide important information for effective operation and control of wastewater treatment. The research objective is to demonstrate methodology for activated sludge image processing aimed to describe morphological characteristics of activated sludge flocs. The proposed software- -based method was presented and verified by analysis of several activated sludge samples. The results show high efficiency of image segmentation and floc recognition of more than 94% floc components. The analysis of a series of 50 pictures gives rapid and reliable results and can be performed in an automatic or semiautomatic mode. Given inherent heterogeneity of activated sludge flocs, multiple and repeated sample images capture (processing of 50 pictures at a time, repeated at least 4 times is recommended.

  17. Factors controlling floc settling velocity along a longitudinal estuarine transect

    Science.gov (United States)

    Manning, A.J.; Schoellhamer, D.H.

    2013-01-01

    A 147 km longitudinal transect of flocculated cohesive sediment properties in San Francisco Bay (SFB) was conducted on June 17th, 2008. Our aim was to determine the factors that control floc settling velocity along the longitudinal axis of the estuary. The INSSEV-LF video system was used to measure floc diameters and settling velocities at 30 stations at a distance of 0.7 m above the estuary bed. Floc sizes (D) ranged from 22 μm to 639 μm and settling velocities (Ws) ranged between 0.04 mm·s− 1 and 15.8 mm·s− 1 during the longitudinal transect. Nearbed turbulent shear stresses throughout the transect duration were within the 0.2–0.5 Pa range which typically stimulates flocculation growth. The individual D–Ws–floc density plots suggest the suspended sediments encountered throughout SFB were composed of both muddy cohesive sediment and mixed sediments flocs. Mass-weighted population mean settling velocity (Wsmass) ranged from 0.5 mm·s− 1 to 10 mm·s− 1. The macrofloc and microfloc (demarcation at 160 μm) sub-populations demonstrated parameterised settling velocities which spanned nearly double the range of the sample mean settling velocities (Wsmean). The macroflocs tended to dominate the suspended mass (up to 77% of the ambient suspended solid concentration; SSC) from San Pablo Bay to Carquinez Strait (the vicinity of the turbidity maximum zone). Microfloc mass was particularly significant (typically 60–100% of the SSC) in the northern section of South Bay and most of Central Bay. The transect took eleven hours to complete and was not fully synoptic. During slack tide, larger and faster settling flocs deposited, accounting for most of the longitudinal variability. The best single predictor of settling velocity was water velocity 39 min prior to sampling, not suspended-sediment concentration or salinity. Resuspension and settling lags are likely responsible for the lagged response of settling velocity to water velocity. The distribution of

  18. Diversity of Integron- and Culture-Associated Antibiotic Resistance Genes in Freshwater Floc

    OpenAIRE

    Drudge, Christopher N.; Elliott, Amy V. C.; Plach, Janina M.; Ejim, Linda J.; Wright, Gerard D.; Droppo, Ian G.; Warren, Lesley A.

    2012-01-01

    Clinically important antibiotic resistance genes were detected in culturable bacteria and class 1 integron gene cassettes recovered from suspended floc, a significant aquatic repository for microorganisms and trace elements, across freshwater systems variably impacted by anthropogenic activities. Antibiotic resistance gene cassettes in floc total community DNA differed appreciably in number and type from genes detected in bacteria cultured from floc. The number of floc antibiotic resistance g...

  19. Arsenic removal by using colloidal adsorption flotation utilizing Fe(OH)3 floc in a dissolved air flotation system; Eliminacion de arsenico mediante flotacion por adsorcion coloidal utilizando floculos de Fe(OH){sub 3} en un sistema de flotacion por aire disuelto

    Energy Technology Data Exchange (ETDEWEB)

    Pavez, O.; Palacios, J. M.; Aguilar, C.

    2009-07-01

    In the present work, the influence of Fe/As ratio on the As removal, from aqueous solutions, applying flotation by colloidal adsorption was studied. Ferric chloride was used as coagulant and dodec il sulfate as collector, and arsenic trioxide was utilized to preparing the solutions. The obtained results show that the highest arsenic removal was accomplished in the range of pH between 4 and 5,5, and the increasing of the initial concentration of Fe(III), increases the removal of arsenic from the solution. However, with the decreasing of the initial concentration of arsenic in the solution, it is required a larger Fe/As ratio for its removal. For solutions containing: 13,73, 1,71 and 0,105 mg/L of arsenic, it was shown that to remove around 95% of the dissolved arsenic, a Fe/As ratios of approximately 6/1, 18/1 and 800/1, respectively, are required. (Author) 31 refs.

  20. Micro-environment characteristics and microbial communities in activated sludge flocs of different particle size.

    Science.gov (United States)

    Han, Yunping; Liu, Junxin; Guo, Xuesong; Li, Lin

    2012-11-01

    Microorganisms in activated sludge flocs (ASF) play important roles in the wastewater treatment process. However, the interplay between micro-environmental variation and microbial responses within ASF is poorly understood. In this study, microelectrodes and molecular culture-independent techniques were applied to detect the internal environment, microbial composition, and distribution in flocs with different particle size. Results showed dissolved oxygen (DO) concentrations within the center of the flocs were less than at the surface, and the DO concentration distributions were distinct in flocs of different particle size. With floc particle size increasing from 100 to 250 μm, the DO concentrations in the floc centers decreased 10-55%, respectively, while no distinct change was observed in flocs of less than 100 μm. Similar phenomenon occurred for the distributions of NH(4)(+) and NO(3)(-) in flocs. Microbial structure indicated bacterial compositions and distributions were heterogeneous and responded to micro-environment variation in flocs of different particle size. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Diversity of Integron- and Culture-Associated Antibiotic Resistance Genes in Freshwater Floc

    Science.gov (United States)

    Drudge, Christopher N.; Elliott, Amy V. C.; Plach, Janina M.; Ejim, Linda J.; Wright, Gerard D.; Droppo, Ian G.

    2012-01-01

    Clinically important antibiotic resistance genes were detected in culturable bacteria and class 1 integron gene cassettes recovered from suspended floc, a significant aquatic repository for microorganisms and trace elements, across freshwater systems variably impacted by anthropogenic activities. Antibiotic resistance gene cassettes in floc total community DNA differed appreciably in number and type from genes detected in bacteria cultured from floc. The number of floc antibiotic resistance gene cassette types detected across sites was positively correlated with total (the sum of Ag, As, Cu, and Pb) trace element concentrations in aqueous solution and in a component of floc readily accessible to bacteria. In particular, concentrations of Cu and Pb in the floc component were positively correlated with floc resistance gene cassette diversity. Collectively, these results identify suspended floc as an important reservoir, distinct from bulk water and bed sediment, for antibiotic resistance in aquatic environments ranging from heavily impacted urban sites to remote areas of nature reserves and indicate that trace elements, particularly Cu and Pb, are geochemical markers of resistance diversity in this environmental reservoir. The increase in contamination of global water supplies suggests that aquatic environments will become an even more important reservoir of clinically important antibiotic resistance in the future. PMID:22467502

  2. Investigating the characteristic strength of flocs formed from crude and purified Hibiscus extracts in water treatment.

    Science.gov (United States)

    Jones, Alfred Ndahi; Bridgeman, John

    2016-10-15

    The growth, breakage and re-growth of flocs formed using crude and purified seed extracts of Okra (OK), Sabdariffa (SB) and Kenaf (KE) as coagulants and coagulant aids was assessed. The results showed floc size increased from 300 μm when aluminium sulphate (AS) was used as a coagulant to between 696 μm and 722 μm with the addition of 50 mg/l of OK, KE and SB crude samples as coagulant aids. Similarly, an increase in floc size was observed when each of the purified proteins was used as coagulant aid at doses of between 0.123 and 0.74 mg/l. The largest floc sizes of 741 μm, 460 μm and 571 μm were obtained with a 0.123 mg/l dose of purified Okra protein (POP), purified Sabdariffa (PSP) and purified Kenaf (PKP) respectively. Further coagulant aid addition from 0.123 to 0.74 mg/l resulted in a decrease in floc size and strength in POP and PSP. However, an increase in floc strength and reduced d50 size was observed in PKP at a dose of 0.74 mg/l. Flocs produced when using purified and crude extract samples as coagulant aids exhibited high recovery factors and strength. However, flocs exhibited greater recovery post-breakage when the extracts were used as a primary coagulant. It was observed that the combination of purified proteins and AS improved floc size, strength and recovery factors. Therefore, the applications of Hibiscus seeds in either crude or purified form increases floc growth, strength, recoverability and can also reduce the cost associated with the import of AS in developing countries. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  3. Bacterial composition of activated sludge - importance for floc and sludge properties

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Per H.; Thomsen, Trine R.; Nielsen, Jeppe L.

    2003-07-01

    Activated sludge flocs consist of numerous constituents which, together with other factors, are responsible for floc structure and floc properties. These properties largely determine the sludge properties such as flocculation, settling and dewaterability. In this paper we briefly review the present knowledge about the role of bacteria in relation to floc and sludge properties, and we present a new approach to investigate the identity and function of the bacteria in the activated sludge flocs. The approach includes identification of the important bacteria and a characterization of their physiological and functional properties. It is carried out by use of culture-independent molecular biological methods linked with other methods to study the physiology and function maintaining a single cell resolution. Using this approach it was found that floc-forming properties differed among the various bacterial groups, e.g. that different microcolony-forming bacteria had very different sensitivities to shear and that some of them deflocculated under anaerobic conditions. in our opinion, the approach to combine identity with functional analysis of the dominant bacteria in activated sludge by in situ methods is a very promising way to investigate correlations between presence of specific bacteria, and floc and sludge properties that are of interest. (author)

  4. Investigation and visualization of internal flow through particle aggregates and microbial flocs using particle image velocimetry.

    Science.gov (United States)

    Xiao, Feng; Lam, Kit Ming; Li, Xiao-yan

    2013-05-01

    An advanced particle-tracking and flow-visualization technology, particle image velocimetry (PIV), was utilized to investigate the hydrodynamic properties of large aggregates in water. The laser-based PIV system was used together with a settling column to capture the streamlines around two types of aggregates: latex particle aggregates and activated sludge (AS) flocs. Both types of the aggregates were highly porous and fractal with fractal dimensions of 2.13±0.31 for the latex particle aggregates (1210-2144 μm) and 1.78±0.24 for the AS flocs (1265-3737 μm). The results show that PIV is a powerful flow visualization technique capable of determining flow field details at the micrometer scale around and through settling aggregates and flocs. The PIV streamlines provided direct experimental proof of internal flow through the aggregate interiors. According to the PIV images, fluid collection efficiency ranged from 0.052 to 0.174 for the latex particle aggregates and from 0.008 to 0.126 for AS flocs. AS flocs are apparently less permeable than the particle aggregates, probably due to the extracellular polymeric substances (EPSs) produced by bacteria clogging the pores within the flocs. The internal permeation of fractal aggregates and bio-flocs would enhance flocculation between particles and material transport into the aggregates. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Calcium phosphate flocs and the clarification of sugar cane juice from whole of crop harvesting.

    Science.gov (United States)

    Thai, Caroline C D; Moghaddam, Lalehvash; Doherty, William O S

    2015-02-11

    Sugar cane biomass is one of the most viable feedstocks for the production of renewable fuels and chemicals. Therefore, processing the whole of crop (WC) (i.e., stalk and trash, instead of stalk only) will increase the amount of available biomass for this purpose. However, effective clarification of juice expressed from WC for raw sugar manufacture is a major challenge because of the amounts and types of non-sucrose impurities (e.g., polysaccharides, inorganics, proteins, etc.) present. Calcium phosphate flocs are important during sugar cane juice clarification because they are responsible for the removal of impurities. Therefore, to gain a better understanding of the role of calcium phosphate flocs during the juice clarification process, the effects of impurities on the physicochemical properties of calcium phosphate flocs were examined using small-angle laser light scattering technique, attenuated total reflectance Fourier transformed infrared spectroscopy, and X-ray powder diffraction. Results on synthetic sugar juice solutions showed that the presence of SiO2 and Na(+) ions affected floc size and floc structure. Starch and phosphate ions did not affect the floc structure; however, the former reduced the floc size, whereas the latter increased the floc size. The study revealed that high levels of Na(+) ions would negatively affect the clarification process the most, as they would reduce the amount of suspended particles trapped by the flocs. A complementary study on prepared WC juice using cold and cold/intermediate liming techniques was conducted. The study demonstrated that, in comparison to the one-stage (i.e., conventional) clarification process, a two-stage clarification process using cold liming removed more polysaccharides (≤19%), proteins (≤82%), phosphorus (≤53%), and SiO2 (≤23%) in WC juice but increased Ca(2+) (≤136%) and sulfur (≤200%).

  6. Advances in the measurement of mud flocs within turbulent suspensions in both the laboratory and field

    Science.gov (United States)

    Strom, K.; Tran, D. A.; Dillon, B.

    2017-12-01

    Predicting the size and settling velocity of mud suspensions under the influence of flocculation is crucial for the accurate prediction of mud movement and deposition in sediment transport modeling of environments such as agricultural streams, large coastal rivers, estuaries, river plumes, boundary currents, and turbidity currents. Yet, collecting accurate and high resolution data on mud flocs is difficult. For example, measurement of flocs with camera systems generally provide the best avenue for preserving floc structure and obtaining accurate information about true floc sizes. However, capturing images of flocs in swirling turbulent flows can be difficult and often limited to suspensions where concentrations are low (influence of flocculation on mud settling velocity are based on sparse data that often present non-congruent functionality in floc size and settling velocity with basic influencers such as suspended sediment concentration. Here we present developments in image acquisition systems and processing methods that allow for measurement of floc size distributions in turbulent suspensions approaching 500 mg/L. At the heart of these developments are the introduction of a simple flow-through cell, modern digital sensor technology, and automated image processing. The combination of these elements allows for high-resolution times series of floc size populations to be measured in turbulent suspensions over a much broader range of suspended sediment concentration than has previously been possible — all without the need to transfer samples to a separate imaging container. We show applications and results from these developments in laboratory experiments and highlight their use in a newly-developed, low-cost, and field-deployable floc camera system.

  7. The influence of protruding filamentous bacteria on floc stability and solid-liquid separation in the activated sludge process.

    Science.gov (United States)

    Burger, Wilhelm; Krysiak-Baltyn, Konrad; Scales, Peter J; Martin, Gregory J O; Stickland, Anthony D; Gras, Sally L

    2017-10-15

    Filamentous bacteria can impact on the physical properties of flocs in the activated sludge process assisting solid-liquid separation or inducing problems when bacteria are overabundant. While filamentous bacteria within the flocs are understood to increase floc tensile strength, the relationship between protruding external filaments, dewatering characteristics and floc stability is unclear. Here, a quantitative methodology was applied to determine the abundance of filamentous bacteria in activated sludge samples from four wastewater treatment plants. An automated image analysis procedure was applied to identify filaments and flocs and calculate the length of the protruding filamentous bacteria (PFB) relative to the floc size. The correlation between PFB and floc behavior was then assessed. Increased filament abundance was found to increase interphase drag on the settling flocs, as quantified by the hindered settling function. Additionally, increased filament abundance was correlated with a lower gel point concentration leading to poorer sludge compactability. The floc strength factor, defined as the relative change in floc size upon shearing, correlated positively with filament abundance. This influence of external protruding filamentous bacteria on floc stability is consistent with the filamentous backbone theory, where filamentous bacteria within flocs increase floc resistance to shear-induced breakup. A qualitative correlation was also observed between protruding and internal filamentous structure. This study confirms that filamentous bacteria are necessary to enhance floc stability but if excessively abundant will adversely affect solid-liquid separation. The tools developed here will allow quantitative analysis of filament abundance, which is an improvement on current qualitative methods and the improved method could be used to assist and optimize the operation of waste water treatment plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The tail of two models: Impact of circularity and biomass non-homogeneity on UV disinfection of wastewater flocs.

    Science.gov (United States)

    Azimi, Y; Liu, Y; Tan, T C; Allen, D G; Farnood, R R

    2017-12-01

    The effects of floc structural characteristics, i.e. shape and dense biomass distribution, were evaluated on ultraviolet (UV) disinfection resistance, represented by the tailing level of the UV dose response curve (DRC). Ellipsoid-shaped flocs of similar volume and different projected circularities were constructed in-silico and a mathematical model was developed to compare their UV DRC tailing levels (indicative of UV-resistance). It was found that floc shape can significantly influence tailing level, and rounder flocs (i.e. flocs with higher circularity) were more UV-resistant. This result was confirmed experimentally by obtaining UV DRCs of two 75-90 μm floc populations with different percentages (20% vs. 30%) of flocs with circularities higher than 0.5. The population enriched in less circular flocs (i.e. 20% flocs with circularities >0.5) had a lower tailing level (at least by 1-log) compared to the other population. The second model was developed to describe variations in UV disinfection kinetics observed in flocs with transverse vs. radial biomass non-homogeneity, indicative of biofilm-originated vs. suspended flocs. The varied-density hemispheres model and shell-core model were developed to simulate transverse and radial non-homogeneity, respectively. The UV DRCs were mathematically constructed and biofilm-originated flocs showed higher UV resistance compared to suspended flocs. The calculated UV DRCs agreed well with the experimental data collected from activated sludge and trickling filter flocs (no fitting parameters were used). These findings provide useful information in terms of designing/modifying upstream processes for reducing UV disinfection energy demand. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. How do floc characteristics change once they have deposited to a bed, and how, if at all, are they modified during re-entrainment?

    Science.gov (United States)

    Tran, D. A.; Kuprenas, R.; Strom, K.

    2017-12-01

    In many environments, recently deposited flocs (Kaolinite and 20% Montmorillonite) with concentrations of 25, 100 and 400 mg/L, along with two bed conditions, i.e., smooth and rough bed. The results show three primary conclusions: (1) during the low shear period the bed-flocs grow and have larger sizes compare to that of the re-suspended flocs. Yet, during high shear period, re-entrained flocs reached to its equilibrium size in the order of 1-20 minutes; (2) bed-floc size is a function of the consolidation time. For 12 day experiments, the bed-floc size was approximate 8-16 times larger than the freshly deposited floc. In 6 hour and 6 day experiments, there was unnoticeable difference between freshly deposited flocs and re-suspended flocs; and (3) the data showed that all the deposited floc re-suspended, albeit at different rates depending on concentration.

  10. Fractal analysis of polyferric chloride-humic acid (PFC-HA) flocs in different topological spaces.

    Science.gov (United States)

    Wang, Yili; Lu, Jia; Baiyu, Du; Shi, Baoyou; Wang, Dongsheng

    2009-01-01

    The fractal dimensions in different topological spaces of polyferric chloride-humic acid (PFC-HA) flocs, formed in flocculating different kinds of humic acids (HA) water at different initial pH (9.0, 7.0, 5.0) and PFC dosages, were calculated by effective density-maximum diameter, image analysis, and N2 absorption-desorption methods, respectively. The mass fractal dimensions (Df) of PFC-HA flocs were calculated by bi-logarithm relation of effective density with maximum diameter and Logan empirical equation. The Df value was more than 2.0 at initial pH of 7.0, which was 11% and 13% higher than those at pH 9.0 and 5.0, respectively, indicating the most compact flocs formed in flocculated HA water at initial pH of 7.0. The image analysis for those flocs indicates that after flocculating the HA water at initial pH greater than 7.0 with PFC flocculant, the fractal dimensions of D2 (logA vs. logdL) and D3 (logVsphere VS. logdL) of PFC-HA flocs decreased with the increase of PFC dosages, and PFC-HA flocs showed a gradually looser structure. At the optimum dosage of PFC, the D2 (logA vs. logdL) values of the flocs show 14%-43% difference with their corresponding Df, and they even had different tendency with the change of initial pH values. However, the D2 values of the flocs formed at three different initial pH in HA solution had a same tendency with the corresponding Dr. Based on fractal Frenkel-Halsey-Hill (FHH) adsorption and desorption equations, the pore surface fractal dimensions (Ds) for dried powders of PFC-HA flocs formed in HA water with initial pH 9.0 and 7.0 were all close to 2.9421, and the Ds values of flocs formed at initial pH 5.0 were less than 2.3746. It indicated that the pore surface fractal dimensions of PFC-HA flocs dried powder mainly show the irregularity from the mesopore-size distribution and marcopore-size distribution.

  11. Denitrification performance of acclimated bio-floc in sequencing batch reactor

    Science.gov (United States)

    Wang, Tao; Liu, Qingsong; Li, Hua; Dong, Hongbiao; Duan, Yafei; Zhang, Jiasong

    2018-01-01

    Bio-floc technology (BFT) is a new aquaculture models contain both aquaculture and water treatment. Nevertheless, there exists a universal phenomenon of nitrate accumulation in bio-floc system with zero water exchange. In this study, bio-floc was acclimated under 2 hours anaerobic conditions per day by sequencing batch method, which aims to enrichment culture denitrifying microorganisms. The results illustrated that NH4 +-N and NO2 --N concentration in effluent was remained below 0.5 mg/L and 0.1 mg/L respectively, coupled with NO3 --N below 57 mg/L during 240 days cultivation and acclimation. The nitrate concentration was far less than results reported in other bio-floc system with zero water exchange. After acclimation, the anaerobic denitrification performance of the bio-floc was tested and it exhibited high denitrification activity. Nitrate removal rate was approximately 100%, and special nitrate reduction rate was as high as 475.74 mg/(gVSS·d). This acclimation method made bio-floc could be used to nitrogen removal in aquaculture water treatment.

  12. On the Kaolinite Floc Size at the Steady State of Flocculation in a Turbulent Flow.

    Directory of Open Access Journals (Sweden)

    Zhongfan Zhu

    Full Text Available The flocculation of cohesive fine-grained sediment plays an important role in the transport characteristics of pollutants and nutrients absorbed on the surface of sediment in estuarine and coastal waters through the complex processes of sediment transport, deposition, resuspension and consolidation. Many laboratory experiments have been carried out to investigate the influence of different flow shear conditions on the floc size at the steady state of flocculation in the shear flow. Most of these experiments reported that the floc size decreases with increasing shear stresses and used a power law to express this dependence. In this study, we performed a Couette-flow experiment to measure the size of the kaolinite floc through sampling observation and an image analysis system at the steady state of flocculation under six flow shear conditions. The results show that the negative correlation of the floc size on the flow shear occurs only at high shear conditions, whereas at low shear conditions, the floc size increases with increasing turbulent shear stresses regardless of electrolyte conditions. Increasing electrolyte conditions and the initial particle concentration could lead to a larger steady-state floc size.

  13. On the Kaolinite Floc Size at the Steady State of Flocculation in a Turbulent Flow.

    Science.gov (United States)

    Zhu, Zhongfan; Wang, Hongrui; Yu, Jingshan; Dou, Jie

    2016-01-01

    The flocculation of cohesive fine-grained sediment plays an important role in the transport characteristics of pollutants and nutrients absorbed on the surface of sediment in estuarine and coastal waters through the complex processes of sediment transport, deposition, resuspension and consolidation. Many laboratory experiments have been carried out to investigate the influence of different flow shear conditions on the floc size at the steady state of flocculation in the shear flow. Most of these experiments reported that the floc size decreases with increasing shear stresses and used a power law to express this dependence. In this study, we performed a Couette-flow experiment to measure the size of the kaolinite floc through sampling observation and an image analysis system at the steady state of flocculation under six flow shear conditions. The results show that the negative correlation of the floc size on the flow shear occurs only at high shear conditions, whereas at low shear conditions, the floc size increases with increasing turbulent shear stresses regardless of electrolyte conditions. Increasing electrolyte conditions and the initial particle concentration could lead to a larger steady-state floc size.

  14. Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Tetsurou (Nitto Denko Corp., Ibaraki, Osaka (Japan)); Sawa, Toshio; Shindoh, Toshikazu

    1989-09-01

    The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author).

  15. Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

    International Nuclear Information System (INIS)

    Adachi, Tetsurou; Sawa, Toshio; Shindoh, Toshikazu.

    1989-01-01

    The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author)

  16. Formation of Polyphenol-Denatured Protein Flocs in Alcohol Beverages Sweetened with Refined Cane Sugars.

    Science.gov (United States)

    Eggleston, Gillian; Triplett, Alexa

    2017-11-08

    The sporadic appearance of floc from refined, white cane sugars in alcohol beverages remains a technical problem for both beverage manufacturers and sugar refiners. Cane invert sugars mixed with 60% pure alcohol and water increased light scattering by up to ∼1000-fold. Insoluble and soluble starch, fat, inorganic ash, oligosaccharides, Brix, and pH were not involved in the prevailing floc-formation mechanism. Strong polynomial correlations existed between the haze floc and indicator values (IVs) (color at 420 nm pH 9.0/color at pH 4.0-an indirect measure of polyphenolic and flavonoid colorants) (R 2 = 0.815) and protein (R 2 = 0.819) content of the invert sugars. Ethanol-induced denaturation of the protein exposed hydrophobic polyphenol-binding sites that were further exposed when heated to 80 °C. A tentative mechanism for floc formation was advanced by molecular probing with a haze (floc) active protein and polyphenol as well as polar, nonpolar, and ionic solvents.

  17. Variations of floc morphology and extracellular organic matters (EOM) in relation to floc filterability under algae flocculation harvesting using polymeric titanium coagulants (PTCs).

    Science.gov (United States)

    Zhang, Weijun; Song, Rongna; Cao, Bingdi; Yang, Xiaofang; Wang, Dongsheng; Fu, Xingmin; Song, Yao

    2018-05-01

    The work evaluated the algae cells removal efficiency using titanium salt coagulants with different degree of polymerization (PTCs), and the algae cells aggregates and extracellular organic matter (EOM) under chemical flocculation were investigated. The results indicated that PTCs performed well in algae cells flocculation and separation. The main mechanism using PTCs of low alkalisation degree for algae flocculation was associated with charge neutralization, while adsorption bridging and sweep flocculation was mainly responsible for algae removal by PTCs of high alkalisation degree treatment. In addition, the flocs formed by PTC 1.0 showed the best filtration property, and EOM reached the minimum at this time, indicating the flocs formed by PTC 1.0 were more compact than other PTCs, which can be confirmed by SEM analysis. Three-dimensional excitation emission matrix fluorescence (3D-EEM) and high performance size exclusion chromatography (HPSEC) revealed that the EOMs were removed under PTCs flocculation, which improved floc filterability. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Coagulation characteristics of titanium (Ti) salt coagulant compared with aluminum (Al) and iron (Fe) salts.

    Science.gov (United States)

    Zhao, Y X; Gao, B Y; Shon, H K; Cao, B C; Kim, J-H

    2011-01-30

    In this study, the performance of titanium tetrachloride (TiCl(4)) coagulation and flocculation is compared with commonly used coagulants such as aluminum sulfate (Al(2)(SO(4))(3)), polyaluminum chloride (PACl), iron chloride (FeCl(3)), and polyferric sulfate (PFS) in terms of water quality parameters and floc properties. TiCl(4) flocculation achieved higher removal of UV(254) (98%), dissolved organic carbon (DOC) (84%) and turbidity (93%) than other conventional coagulants. Charge neutralization and physical entrapment of colloids within coagulant precipitates and adsorption, seemed to play a significant role during TiCl(4) flocculation, while the main mechanism for conventional coagulants was bridge-aggregation and adsorption. The aggregated flocs after TiCl(4) flocculation showed the fastest growth rate compared to the other coagulants, with the largest floc size (801 μm) occurring within 8 min. The floc strength factor of PACl, Al(2)(SO(4))(3), PFS, FeCl(3) and TiCl(4) was 34, 30, 29, 26 and 29, respectively, while the floc recovery factor of the TiCl(4) coagulant was the lowest. Based on the results of the above study, it is concluded that the TiCl(4) flocculation can reduce the hydraulic retention time of slow and rapid mixing, however, careful handling of sludge is required due to the low recoverability of the aggregated floc. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. Primary Nutritional Content of Bio-Flocs Cultured with Different Organic Carbon Sources and Salinity

    Directory of Open Access Journals (Sweden)

    JULIE EKASARI

    2010-09-01

    Full Text Available Application of bio-flocs technology (BFT in aquaculture offers a solution to avoid environmental impact of high nutrient discharges and to reduce the use of artificial feed. In BFT, excess of nutrients in aquaculture systems are converted into microbial biomass, which can be consumed by the cultured animals as a food source. In this experiment, upconcentrated pond water obtained from the drum filter of a freshwater tilapia farm was used for bio-flocs reactors. Two carbon sources, sugar and glycerol, were used as the first variable, and two different levels of salinity, 0 and 30 ppt, were used as the second variable. Bio-flocs with glycerol as a carbon source had higher total n-6 PUFAs (19.1 ± 2.1 and 22.3 ± 8.6 mg/g DW at 0 and 30 ppt, respectively than that of glucose (4.0 ± 0.1 and 12.6 ± 2.5 mg/g DW at 0 and 30 ppt. However, there was no effect of carbon source or salinity on crude protein, lipid, and total n-3 PUFAs contents of the bio-flocs.

  20. Structure of Colloidal Flocs in relation to the Dynamic Properties of Unstable Suspension

    Directory of Open Access Journals (Sweden)

    Yasuhisa Adachi

    2012-01-01

    Full Text Available Dynamic behaviors of unstable colloidal dispersions are reviewed in terms of floc formation. Geometrical structure of flocs in terms of chemical conditions and formation mechanics is a key to predict macroscopic transportation properties. The rate of sedimentation and rheological properties can be described with the help of fractal dimension (D that is the function of the number of contacts between clusters (Nc. It is also well known that the application of water soluble polymers and polyelectrolytes, which are usually used as a conditioner or flocculants in colloidal dispersions, critically affects the process of flocculation. The resulted floc structure is also influenced by the application of polymer. In order to reveal the roles of the polymers, the elementary rate process of polymer reaching to colloidal interface and subsequent reconformation process into more stable adsorption state are needed to be analyzed. The properties of permeable flocs and adsorbed polymer (polyelectrolyte layers formed on the colloidal surfaces remain to be worked out in relation to inhomogeneous porous structure and electrokinetics in the future.

  1. Variable fractal dimension : A major control for floc structure and flocculation kinematics of suspended cohesive sediment

    NARCIS (Netherlands)

    Maggi, F.

    2007-01-01

    While the fractal dimension of suspended flocs of cohesive sediment is known to vary with the shear rate, electrochemical properties of the sediment and environment, geometrical restructuring, and presence of organic matter, experimental data presented in this work suggest changes in fractal

  2. Multiple dynamic Al-based floc layers on ultrafiltration membrane surfaces for humic acid and reservoir water fouling reduction.

    Science.gov (United States)

    Ma, Baiwen; Li, Wenjiang; Liu, Ruiping; Liu, Gang; Sun, Jingqiu; Liu, Huijuan; Qu, Jiuhui; van der Meer, Walter

    2018-04-05

    The integration of adsorbents with ultrafiltration (UF) membranes is a promising method for alleviating membrane fouling and reducing land use. However, adsorbents typically are only injected into the membrane tank once, resulting in a single dynamic protection layer and low removal efficiency over long-term operation. In addition, the granular adsorbents used can cause membrane surface damage. To overcome these disadvantages, we injected inexpensive and loose aluminum (Al)-based flocs directly into a membrane tank with bottom aeration in the presence of humic acid (HA) or raw water taken from the Miyun Reservoir (Beijing, China). Results showed that the flocs were well suspended in the membrane tank, and multiple dynamic floc protection layers were formed (sandwich-like) on the membrane surface with multiple batch injections. Higher frequency floc injections resulted in better floc utilization efficiency and less severe membrane fouling. With continuous injection, acid solutions demonstrated better performance in removing HA molecules, especially those with small molecular weight, and in alleviating membrane fouling compared with the use of high aeration rate or polyacrylamide injection. This was attributed to the small particle size, large specific surface area, and high zeta potential of the flocs. Additionally, excellent UF membrane performance was exhibited by reservoir water with continuous injection and acid solution. Based on the outstanding UF membrane performance, this innovative integrated filtration with loose Al-based flocs has great application potential for water treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Flocculation and floc break-up related to tidally induced turbulent shear in a low-turbidity, microtidal estuary

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Andersen, Thorbjørn Joest

    2014-01-01

    mean threshold diameter of 50–60 μm present at high turbulent shear flocculated to form fragile macroflocs with sizes of several hundred microns and mean diameters above 80 μm around slack water periods. A hysteresis in floc break-up and flocculation was found at high water slack (HWS), as flocs formed...... at a root mean square velocity gradient (G) around 1 s− 1 were not broken up until the shear reached G > 4 s− 1. As an effect, the flocculation time (time for flocculation from constituent microflocs to fragile macroflocs) was roughly 100 min while the equivalent floc break-up time was roughly 200 min...

  4. Exploratory studies of element substitutions in synthetic tetrahedrite. Part II. Selenium and tellurium as anions in Zn-Fe tetrahedrites

    DEFF Research Database (Denmark)

    Karup-Møller, Sven; Makovicky, E.

    1999-01-01

    Composition limits of iron and/or zinc-bearing selenium tetrahedrite were explored by means of dry syntheses from pure elements at 450oC. Only the substituted compositions Cu10Zn2Sb4Se13 (a 10.833 Å) and Cu10Fe1.8Sb4Se13 (a 10.823 Å) are stable. All partly substituted and unsubstituted (i.e. Zn......-free) compositons do not materialize. The substituted Se tetrahedrite coexists with Cu3SbSe3, (iron-bearing) Cu2-xSe, Cu3SbSe4 plus/minus low Zn-sulfide melt. Selenium does not adopt the role of cation and tellurium that of anion in the tetrahedrite structure. The explanation of the severely restricted composition...... field of selenium tetrahedrite is based on the presumed electronic structure. The sp anionic valence band of Se and the d levels of Cu and Fe overlap, reducing the potentially present Cu+2 and Fe+3 to Cu+ and Fe+2. As the tetrahedrite structure apparently cannot tolelrate substantial amounts of electron...

  5. Heavy metals uptake by sonicated activated sludge: Relation with floc surface properties

    International Nuclear Information System (INIS)

    Laurent, Julien; Casellas, Magali; Dagot, Christophe

    2009-01-01

    The effects of sonication of activated sludge on heavy metal uptake were in a first time investigated in respect with potential modifications of floc surface properties. The treatment led to the simultaneous increase of specific surface area and of the availability of negative and/or hydrophilic sites. In parallel, organic matter was released in the soluble fraction. Sorption isotherms of cadmium and copper showed that uptake characteristics and mechanisms were highly dependent on both heavy metal species and specific energy supplied. The increase of both specific surface area and fixation sites availability led to the increase of Cd(II) uptake. For Cu(II), organic matter released in soluble phase during the treatment seemed to act as a ligand and to limit adsorption on flocs surface. Three different heavy metals uptake mechanisms have been identified: proton exchange, ion exchange and (co)precipitation

  6. Effect of C/N ratio on extracellular polymeric substances (EPS) and physicochemical properties of activated sludge flocs

    International Nuclear Information System (INIS)

    Ye Fenxia; Ye Yangfang; Li Ying

    2011-01-01

    The influences of C/N ratio on the extracellular polymeric substances (EPS) and physicochemical properties of the activated sludge flocs were investigated using laboratory-scale sequencing batch reactors (SBRs). Flocs sizes decreased when C/N ratio increased from 20 to 100 and decreased from 20 to 4. The amount of total EPS, TB-EPS, and the carbohydrate and protein contents in TB-EPS were independent of the C/N ratio. In LB-EPS, the protein content increased and the carbohydrate content decreased at decreased C/N ratio, whereas the protein content decreased and the carbohydrate content increased at increased C/N ratio. Effluent suspended solids (ESS) content, turbidity, sludge volume index (SVI), capillary suction time (CST), and specific resistance to filtration (SRF) increased when the C/N ratio decreased, indicating poor flocculation, settleability and dewaterability of the flocs. However, when the C/N ratio increased, only ESS content, SVI and CST value increased. These properties of the flocs were deteriorated greatly under decreased C/N ratio as compared to increased C/N ratio. The characteristics of the flocs could be recovered when C/N ratio returned to the original value. Only the content of protein in LB-EPS was positively correlated with the flocculation, settleability and dewaterability of the flocs.

  7. Characteristics of floc formation of anion and cation exchange resin in precoat filter using powdered ion exchange resin

    International Nuclear Information System (INIS)

    Adachi, Tetsurou; Sawa, Toshio; Shindoh, Toshikazu.

    1989-01-01

    The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of floc formation. The physical, chemical and electrochemical properties of powdered ion exchange resin were measured and the factors related to floc formation of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index. It was found that these factors were mixing ratio, nature of resins and particle size of resins. In addition, it was assumed on the bases of these results that the amount of resin floc was related to sum of the surface electric charges of both resins. The filling ratio of resin floc was related to their product by multiplication and an experimental expression was obtained. The specific settle volume of resin floc could then be simulated by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author)

  8. Characteristics of floc formation of anion and cation exchange resin in precoat filter using powdered ion exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Tetsurou (Nitto Denko Corp., Ibaraki, Osaka (Japan)); Sawa, Toshio; Shindoh, Toshikazu

    1989-09-01

    The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of floc formation. The physical, chemical and electrochemical properties of powdered ion exchange resin were measured and the factors related to floc formation of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index. It was found that these factors were mixing ratio, nature of resins and particle size of resins. In addition, it was assumed on the bases of these results that the amount of resin floc was related to sum of the surface electric charges of both resins. The filling ratio of resin floc was related to their product by multiplication and an experimental expression was obtained. The specific settle volume of resin floc could then be simulated by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author).

  9. Local adaptive approach toward segmentation of microscopic images of activated sludge flocs

    Science.gov (United States)

    Khan, Muhammad Burhan; Nisar, Humaira; Ng, Choon Aun; Lo, Po Kim; Yap, Vooi Voon

    2015-11-01

    Activated sludge process is a widely used method to treat domestic and industrial effluents. The conditions of activated sludge wastewater treatment plant (AS-WWTP) are related to the morphological properties of flocs (microbial aggregates) and filaments, and are required to be monitored for normal operation of the plant. Image processing and analysis is a potential time-efficient monitoring tool for AS-WWTPs. Local adaptive segmentation algorithms are proposed for bright-field microscopic images of activated sludge flocs. Two basic modules are suggested for Otsu thresholding-based local adaptive algorithms with irregular illumination compensation. The performance of the algorithms has been compared with state-of-the-art local adaptive algorithms of Sauvola, Bradley, Feng, and c-mean. The comparisons are done using a number of region- and nonregion-based metrics at different microscopic magnifications and quantification of flocs. The performance metrics show that the proposed algorithms performed better and, in some cases, were comparable to the state-of the-art algorithms. The performance metrics were also assessed subjectively for their suitability for segmentations of activated sludge images. The region-based metrics such as false negative ratio, sensitivity, and negative predictive value gave inconsistent results as compared to other segmentation assessment metrics.

  10. FE Modeling of Human Vocal Tract Acoustics. Part I: Production of Czech Vowels

    Czech Academy of Sciences Publication Activity Database

    Vampola, T.; Horáček, Jaromír; Švec, J. G.

    2008-01-01

    Roč. 94, č. 3 (2008), s. 433-447 ISSN 1610-1928 R&D Projects: GA ČR GA106/04/1025 Institutional research plan: CEZ:AV0Z20760514; CEZ:AV0Z10100502 Keywords : biomechanics of voice * FE models of human vocaltract * acoustic modal analysis Subject RIV: BI - Acoustics Impact factor: 0.538, year: 2008

  11. How do changes in suspended sediment concentration alone influence the size of mud flocs under steady turbulent shearing?

    Science.gov (United States)

    Tran, Duc; Kuprenas, Rachel; Strom, Kyle

    2018-04-01

    Modeling the size and settling velocity of sediment under the influence of flocculation is crucial for the accurate prediction of mud movement and deposition in sediment transport modeling of environments such as agricultural streams, large coastal rivers, estuaries, river plumes, and turbidity currents. Yet, collecting accurate and high resolution data on mud flocs is difficult. As a result, models that account for the influence of flocculation on mud settling velocity are based on sparse data that often present non-congruent relationship in floc properties with basic influencers of flocculations such as suspended sediment concentration. This study examines the influence of suspended sediment concentration on floc size populations within a turbulent suspension. Specifically, the work investigates: (1) the relationship between the equilibrium floc size and suspended sediment concentration under conditions of steady concentration and turbulent shearing; and (2) the speed at which mature flocs adapt to an unsteady drop in the concentration when turbulent shear is constant. Two sets of experiments were used to investigate the target processes. All work was conducted in laboratory mixing tanks using a floc camera and a newly developed image acquisition method. The new method allows for direct imaging and sizing of flocs within turbulent suspensions of clay in concentrations ranging from 15 to 400 mg/L, so that no transfer of the sample to another settling column or imaging tank is needed. The primary conclusions from the two sets of experiments are: (1) that the equilibrium floc size in an energetic turbulent suspension is linearly and positively related to concentration over the range of C = 50 to 400 mg/L, yet with a smaller-than-expected slope based on previous data and models from low-energy environments; and (2) that floc sizes decrease quickly (with a time lag on the order of 1-15 min) to time-varying decreases in concentration at turbulent shearing of G = 50s-1

  12. Observations of the Variability of Floc Sizes on the Louisiana Shelf

    Science.gov (United States)

    Sahin, Cihan; Sheremet, Alexandru

    2014-05-01

    The general principles of floc formation under variable turbulent stresses and sediment availability are well known, but the details of the dynamics are still unclear. Flocculation of primary particles occurs when these particles get close enough to collide, and a significant number of these collisions result in adhesion. Particle concentration, the intensity and number of collisions (turbulent shear) control the size of the flocs. However, aggregation transitions into fragmentation if the intensity of collisions or turbulent shear exceeds a certain threshold. In this case, a limiting maximum size might exist (Berhane et al., 1997; Dyer and Manning, 1999; Uncles et al., 2010). This study investigates the relation between SSC (suspended sediment concentration), turbulent stresses, and floc size using the high-resolution observations of suspended sediment concentration, flow and acoustic backscatter made for 2 weeks in Spring 2008 on the muddy Atchafalaya Shelf. During the experiment, pressure, near-bed current velocities, and acoustic backscatter profiles were sampled using a downward-pointing 1500-kHz PC-ADP (Pulse-Coherent Acoustic Doppler Profiler, Sontek/YSI). In addition, a downward-pointing single frequency ABS (Acoustic Backscatter Sensor, 700-kHz, Marine Electronics, Isle of Guernsey) measured the intensity of acoustic return in the first meter above bed. Thus, acoustic backscatter profiles were observed by two different frequencies (700 kHz for the ABS and 1500 kHz for the PC-ADP). Direct SSC observations were provided by two OBS-3s at 15 and 40-cm above the bed, which sampled synchronously with the PC-ADP. Simultaneous profiles of SSC and the mean floc size at cm-scale vertical resolution were obtained using acoustic backscatter intensity at the different acoustic frequencies. For the calibration of the instruments, which involves estimation of the instruments system constants, the algorithm described in Sahin et al. (2013) was followed. The mean floc size

  13. The Oxidation of Fe(II) in Acidic Sulfate Solutions with Air at Elevated Pressures : Part 2. Influence of H2SO4 and Fe(III)

    NARCIS (Netherlands)

    Wermink, Wouter N.; Versteeg, Geert F.

    2017-01-01

    The oxidation of ferrous ions in acidic sulfate solutions at elevated air pressures was investigated. The effect of the Fe2+ concentration, Fe3+ concentration H2SO4 concentration, and partial oxygen pressure on the reaction rate were determined at three different temperatures, that is, T = 90, 70,

  14. Cadmium biosorption by ozonized activated sludge: The role of bacterial flocs surface properties and mixed liquor composition

    International Nuclear Information System (INIS)

    Laurent, Julien; Casellas, Magali; Pons, Marie-Noelle; Dagot, Christophe

    2010-01-01

    Cadmium uptake by activated sludge was studied following modifications of sludge composition and surface properties induced by ozone treatment. Ozone leads to the solubilization of sludge compounds as well as their mineralization, especially humic like substances. Small particles were formed following floc disintegration, leading to a decrease of average floc size. The study of surface properties underlined the mineralization as the number of surface binding sites decreased with the increase of ozone dose. Depending on ozone dose, cadmium uptake by activated sludge flocs was either increased or decreased. Different mechanisms were involved: below 10 mg O 3 /g TS, the increase of floc specific surface area following floc size decrease as well as the release of phosphate ions yielded an increase by 75% of cadmium uptake, due to the better availability of biosorption sites and the increase of precipitation. Inversely, at higher ozone doses, the number of biosorption sites decreased due to oxidation by ozone. Moreover, dissolved organic matter concentration increased and provided ligands for metal complexation. Cadmium uptake was therefore limited for ozone doses ranging from 10 to 16.8 mg O 3 /g TS.

  15. Floc Performance Parameters during Water Treatment in a Micro-vortex Flocculation Process Determined by Machine Vision.

    Science.gov (United States)

    Dai, Hongling; Qiu, Zumin; Hu, Fengping; Gao, Chao; Chen, Y Frank; Zhou, Zheng

    2018-04-16

    The coagulant dosage of an existing water plant is mainly determined based on the experience of water treatment process and influent/efflenet water quality indexes that have time hysteresis effects. To solve this problem, the effect of coagulant dosage on a number of parameters used to evaluate the efficiency of flocculation in a setup was determined by using the micro-vortex flocculation technology in conjunction with the investigation of the relation between the equivalent diameter and the fractal dimension. By means of the machine vision system and computerized analysis, the effects of floc quantity, floc equivalent diameter and fractal dimension can be assessed. The correlations of these parameters with turbidity and ζ potential of the settling water, taken as measures for effluent quality, were explored. The study results show that the optimal flocculation effect with a turbidity removal rate of 97.9% is achieved at the PAC dosage of 20 mg/L. Meanwhile, a power exponential relation between the floc equivalent diameter and the fractal dimension was established with a correlation coefficient R 2 of 0.826; relations among the effluent turbidity and the floc quantity, equivalent diameter, fractal dimension were established with a correlation coefficient R 2 of 0.982, 0.851, and 0.875, respectively; equations between the ζ potential and the floc quantity, equivalent diameter, fractal dimension were also established where the correlation coefficient R 2 were 0.868, 0.879, and 0.942, respectively. These results may provide excellent reference data for water plants to feed back the coagulant by floc performance parameters, which could relieve the hysteresis effect efficiently.

  16. Floc size distributions of suspended kaolinite in an advection transport dominated tank: measurements and modeling

    Science.gov (United States)

    Shen, Xiaoteng; Maa, Jerome P.-Y.

    2017-11-01

    In estuaries and coastal waters, floc size and its statistical distributions of cohesive sediments are of primary importance, due to their effects on the settling velocity and thus deposition rates of cohesive aggregates. The development of a robust flocculation model that includes the predictions of floc size distributions (FSDs), however, is still in a research stage. In this study, a one-dimensional longitudinal (1-DL) flocculation model along a streamtube is developed. This model is based on solving the population balance equation to find the FSDs by using the quadrature method of moments. To validate this model, a laboratory experiment is carried out to produce an advection transport-dominant environment in a cylindrical tank. The flow field is generated by a marine pump mounted at the bottom center, with its outlet facing upward. This setup generates an axially symmetric flow which is measured by an acoustic Doppler velocimeter (ADV). The measurement results provide the hydrodynamic input data required for this 1-DL model. The other measurement results, the FSDs, are acquired by using an automatic underwater camera system and the resulting images are analyzed to validate the predicted FSDs. This study shows that the FSDs as well as their representative sizes can be efficiently and reasonably simulated by this 1-DL model.

  17. Thermodynamic study of sodium-iron oxides. Part 2. Ternary phase diagram of the Na-Fe-O system

    International Nuclear Information System (INIS)

    Huang, Jintao; Furukawa, Tomohiro; Aoto, Kazumi

    2003-01-01

    Studies on ternary phase diagrams of the Na-Fe-O system have been carried out from the thermodynamic point of view. Thermodynamic data of main ternary Na-Fe oxides Na 4 FeO 3 (s), Na 3 FeO 3 (s), Na 5 FeO 4 (s) and Na 8 Fe 2 O 7 (s) have been assessed. A user database has been created by reviewing literature data together with recent DSC and vapor pressure measurements by the present authors. New ternary phase diagrams of the Na-Fe-O system have been constructed from room temperature to 1000K. Stable conditions of the ternary oxides at 800K were presented in predominance diagram as functions of oxygen pressure and sodium pressure

  18. A method for evaluation of suspension quality easy applicable to practice. The effect of mixing on floc properties

    Czech Academy of Sciences Publication Activity Database

    Bubáková, Petra; Pivokonský, Martin; Pivokonská, Lenka

    2011-01-01

    Roč. 59, č. 3 (2011), s. 184-195 ISSN 0042-790X R&D Projects: GA ČR GAP105/11/0247 Institutional research plan: CEZ:AV0Z20600510 Keywords : aggregation * drinking water treatment * floc properties * flocculation * test of aggregation Subject RIV: BK - Fluid Dynamics Impact factor: 0.340, year: 2011

  19. Electrochemical Measurements of the Kinetics of Inhibition of Two FeFe Hydrogenases by O2 Demonstrate That the Reaction Is Partly Reversible.

    Science.gov (United States)

    Orain, Christophe; Saujet, Laure; Gauquelin, Charles; Soucaille, Philippe; Meynial-Salles, Isabelle; Baffert, Carole; Fourmond, Vincent; Bottin, Hervé; Léger, Christophe

    2015-10-07

    The mechanism of reaction of FeFe hydrogenases with oxygen has been debated. It is complex, apparently very dependent on the details of the protein structure, and difficult to study using conventional kinetic techniques. Here we build on our recent work on the anaerobic inactivation of the enzyme [Fourmond et al. Nat. Chem. 2014, 4, 336-342] to propose and apply a new method for studying this reaction. Using electrochemical measurements of the turnover rate of hydrogenase, we could resolve the first steps of the inhibition reaction and accurately determine their rates. We show that the two most studied FeFe hydrogenases, from Chlamydomonas reinhardtii and Clostridium acetobutylicum, react with O2 according to the same mechanism, despite the fact that the former is much more O2 sensitive than the latter. Unlike often assumed, both enzymes are reversibly inhibited by a short exposure to O2. This will have to be considered to elucidate the mechanism of inhibition, before any prediction can be made regarding which mutations will improve oxygen resistance. We hope that the approach described herein will prove useful in this respect.

  20. Magnetic Properties and Microstructure of FeOx/Fe/FePt and FeOx/FePt Films

    Directory of Open Access Journals (Sweden)

    Jai-Lin Tsai

    2013-01-01

    Full Text Available The Fe(6 nm/FePt film with perpendicular magnetization was deposited on the glass substrate. To study the oxygen diffusion effect on the coupling of Fe/FePt bilayer, the plasma oxidation with 0.5~7% oxygen flow ratio was performed during sputtered part of Fe layer and formed the FeOx(3 nm/Fe(3 nm/FePt trilayer. Two-step magnetic hysteresis loops were found in trilayer with oxygen flow ratio above 1%. The magnetization in FeOx and Fe/FePt layers was decoupled. The moments in FeOx layer were first reversed and followed by coupled Fe/FePt bilayer. The trilayer was annealed again at 500°C and 800°C for 3 minutes. When the FeOx(3 nm/Fe(3 nm/FePt trilayer was annealed at 500°C, the layers structure was changed to FeOx(6 nm/FePt bilayer due to oxygen diffusion. The hard-magnetic FeOx(6 nm/FePt film was coupled with single switching field. The FeOx/(disordered FePt layer structure was observed with further annealing at 800°C and presented soft-magnetic loop. In summary, the coupling between soft-magnetic Fe, FeOx layer, and hard-magnetic L10 FePt layer can be controlled by the oxygen diffusion behavior, and the oxidation of Fe layer was tuned by the annealing temperature. The ordered L10 FePt layer was deteriorated by oxygen and became disordered FePt when the annealed temperature was up to 800°C.

  1. Characterization of size, strength and structure of aluminum-polymer dual-coagulant flocs under different pH and hydraulic conditions.

    Science.gov (United States)

    Rong, Hongyan; Gao, Baoyu; Dong, Min; Zhao, Yanxia; Sun, Shenglei; Yanwang; Yue, Qinyan; Li, Qian

    2013-05-15

    The objectives of this study are to investigate the impact of papermaking sludge product (LA) on coagulation performance and floc properties under different solution pH and hydraulic conditions. LA was synthetized by grafting acrylamide onto the lignin that contained in papermaking sludge. Characterization of LA, such as FTIR, SEM, zeta potential and molecular weight, showed that target product was obtained successfully. LA was used in combination with aluminum sulfate or polyaluminum chloride, namely Al-LA (Al was dosed firstly) and LA-Al (LA was dosed firstly), in humic acid water treatment. Floc properties and coagulation behaviors of aluminum salts and the dual-coagulants were comparatively evaluated. Results showed that DOC removal was improved by LA at pH 4 ~ 9 and the removal variations caused by different pH were decreased. Flocs formed at pH 5 and pH 8 gave quite large floc size. Floc recoverability declined as initial pH increased. Floc size, growth rate and recoverability were in the order of Al-LA>LA-Al>Al. Furthermore, flocs formed at pH 7 showed the weakest resistance to increasing shear force. Fractal dimension was rather high at pH 7 and 8 and it was in the following order: Al>LA-Al>Al-LA. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Flocculation kinetics mechanism and floc formation prepared by poly aluminum chloride coupled with polyacrylamide for ship ballast water.

    Science.gov (United States)

    Zhou, Zhimin; Liu, Sha; Jia, Linan

    2016-01-01

    The performance of flocculants prepared by poly aluminum chloride (PAC) and polyacrylamide (PAM) on treating ballast water collected at the Dalian new port area, the evaluation depending on the values of reaction parameters, and kinetics mechanism of flocculation were investigated in this study. Accordingly, the flocculants of 0.1 g·L(-1), prepared by mixing PAC of 10% with PAM of 2.0‰, enabled the removal rate of zooplankton and phytoplankton to reach 91% in ballast water at 20 °C. Based on flocculation kinetics mechanism analysis, the efficient vortex size during stirring should be larger than the floc particles, and gradient of fluctuating velocity provide the impetus for turbulence flocculation. The results of this study could be relevant to understanding particle-floc interactions during developmental flocculation, and during application of ballast water treatment.

  3. Breakage and regrowth of flocs formed by sweep coagulation using additional coagulant of poly aluminium chloride and non-ionic polyacrylamide.

    Science.gov (United States)

    Nan, Jun; Yao, Meng; Chen, Ting; Li, Shengnan; Wang, Zhenbei; Feng, Gao

    2016-08-01

    The breakage and regrowth of flocs formed by sweep flocculation were investigated on different flocculation mechanisms using additional dosage coagulant of poly aluminium chloride (PACl) and non-ionic polyacrylamide (PAM) to explore the reversibility after floc breakage. The optimal dosage of PACl was 0.15 mM (as alum), and zeta potential exceeding 1 mV meant that sweep flocculation was dominant in the pre-flocculated process. Re-coagulation efficiency increased with additional coagulants dosing, and sedimentation rates of flocs re-formed by small additional dosage of non-ionic PAM are faster than that of flocs re-formed by additional PACl. For additional inorganic coagulant (PACl) during regrowth processes, few negatively charged particles that existed in water sample restricted the effect of charge neutralization. An amorphous aluminum hydroxide precipitation could re-activate the weaker points on the broken floc surface, but regrown flocs have loose structure indicating worse settleability. For additional non-ionic PAM dosing, lower dosage showed large values of fractal dimension and average size, probably due to that unfolded curly molecular chain and exposed amide groups of non-ionic PAM which provide superb conditions for amide group interacting with particles. The use of non-ionic PAM in flocculation has advantage of being more effective than the cationic PACl, probably because it may avoid the re-stabilization of broken flocs by polymer adsorption driven by electrostatic attraction. Hence, appropriate dosing of PAM after breakage could improve the flocs characteristics with large size and compact structure.

  4. Effect of layer thickness in selective laser melting on microstructure of Al/5 wt.%Fe2O3 powder consolidated parts.

    Science.gov (United States)

    Dadbakhsh, Sasan; Hao, Liang

    2014-01-01

    In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM) to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75  μm layer thickness, and 50  μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance) were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe) oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process.

  5. Effect of Layer Thickness in Selective Laser Melting on Microstructure of Al/5 wt.%Fe2O3 Powder Consolidated Parts

    Directory of Open Access Journals (Sweden)

    Sasan Dadbakhsh

    2014-01-01

    Full Text Available In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75 μm layer thickness, and 50 μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process.

  6. Sugarcane cells as origin of acid beverage floc in cane sugar.

    Science.gov (United States)

    Bergamin Lima, Roberta; Andreia Tessmer, Magda; Appezzato da Gloria, Beatriz; Neves Dos Santos, Fabio; Nogueira Eberlin, Marcos; Lima de Aguiar, Claudio

    2017-12-15

    Brazil stands out as the largest producer of crystal sugar in the world, exporting much of its production to the soft drinks industry. However, the chemical composition of sugar may contain numerous compounds that promote the formation of acid beverage flocs (ABF), reducing product acceptance. This study aimed to identify the chemical composition of ABF using different analytical techniques. We could observe the ABF are formed by several chemical classes. Regarding the histochemical analysis, we observed the presence of cellular sugarcane tissues, which are not fully removed in sugarcane processing. Mineral compounds, such as silicon, were found in great amounts by the Scanning electron microscopy and energy dispersive system (SEM/EDS) analysis. The mass spectrometry, high resolution mass by Q-ToF analysis and MALDI-MS allowed identification of compounds, such as p-hydroxybenzaldehyde, vanillin, triacontanoic acid, hexadecanoic acid, octadecanoic acid and n-octacosanoic acid, in the ABF composition. These compounds are widely found in vegetable tissues, confirming that the ABF are formed by tiny particles of plant cells of sugar cane. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. The effects of Fe-oxidizing microorganisms on post-biostimulation permeability reduction and oxidative processes at the Rifle IFRC site

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Clara Sze-Yue [Univ. of Delaware, Newark, DE (United States)

    2015-07-02

    Fe oxidation and biomineral formation is important in aquifers because the highly-reactive oxides can control the mobility of nutrients (e.g. phosphate, C) and metals (e.g. arsenic, uranium). Mineral formation also has the potential to affect hydrology, depending on the volume and distribution in pore spaces. In this exploratory study, we sought to understand how microbial Fe-oxidizers and their biominerals affect, and are affected by groundwater flow. As part of work at the Rifle aquifer in Colorado, we initially hypothesized that Fe-oxidizers were contributing to aquifer clogging problems associated with enhanced bioremediation. To demonstrate the presence of Fe-oxidizers in the Rifle aquifer, we enriched FeOM from groundwater samples, and isolated two novel chemolithotrophic, microaerophilic Fe-oxidizing Betaproteobacteria, Hydrogenophaga sp. P101 and Curvibacter sp. CD03. To image cells and biominerals in the context of pores, we developed a “micro-aquifer,” a sand-filled flow-through culture chamber that allows for imaging of sediment pore space with multiphoton confocal microscopy. Fe oxide biofilms formed on sand grains, demonstrating that FeOM produce Fe oxide sand coatings. Fe coatings are common on aquifer sands, and tend to sequester contaminants; however, it has never previously been shown that microbes are responsible for their formation. In contrast to our original hypothesis, the biominerals did not clog the mini-aquifer. Instead, Fe biofilm distribution was dynamic: they grew as coatings, then periodically sloughed off sand grains, with some flocs later caught in pore throats. This has implications for physical hydrology, including pore scale architecture, and element transport. The sloughing of coatings likely prevents the biominerals from clogging wells and aquifers, at least initially. Although attached biomineral coatings sequester Fe-associated elements (e.g. P, As, C, U), when biominerals detach, these elements are transported as particles

  8. Microbial dynamics of biofilm and suspended flocs in anammox membrane bioreactor: The effect of non-woven fabric membrane.

    Science.gov (United States)

    Ren, Long-Fei; Lv, Lu; Kang, Qi; Gao, Baoyu; Ni, Shou-Qing; Chen, Yi-Han; Xu, Shiping

    2018-01-01

    Membrane bioreactor with non-woven fabric membranes (NWMBR) is developing into a suitable method for anaerobic ammonium oxidation (anammox). As a carrier, non-woven fabric membrane divided total biomass into biofilm and suspended flocs gradually. Total nitrogen removal efficiency was maintained around 82.6% under nitrogen loading rate of 567.4mgN/L/d after 260days operation. Second-order substrate removal and Stover-Kincannon models were successfully used to simulate the nitrogen removal performance in NWMBR. High-throughput sequence was employed to elucidate the underlying microbial community dynamics. Candidatus Brocadia, Kuenenia, Jettenia were detected to affirm the dominant status of anammox microorganisms and 98.2% of anammox microorganisms distributed in biofilm. In addition, abundances of functional genes (hzs, nirK) in biofilm and suspended flocs were assessed by quantitative PCR to further investigate the coexistence of anammox and other microorganisms. Potential nitrogen removal pathways were established according to relevant nitrogen removal performance and microbial community. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Ultrasonic method for microscopic analysis of suspended particle aggregation and floc properties - new developments in the water industry

    Energy Technology Data Exchange (ETDEWEB)

    Spengler, J.F. [Gelsenwasser AG, Gelsenkirchen (Germany). Abt. PIA; Jekel, M. [Technische Univ. Berlin (Germany). Dept. of Water Quality Control; Coakley, W.T. [Cardiff Univ., Cardiff (United Kingdom). School of Biosciences

    2002-07-01

    This work reports the investigation, development and optimisation of methods employing MHz ultrasonic standing waves (USSW) for analytical applications in the water industry. The performance of large-scale processing methods for suspensions a significantly influenced by aggregate properties. Laboratory-scale studies on the aggregation efficiency and the settling behaviour of suspensions under varied suspension stability ('Jar-Test') is e.g. a common method to optimise focculation/sedimentation processes. A novel microscopic method, employing an acoustic 'mini-chamber', has been introduced here. The set-up facilitates the observation of aggregation processes under defined conditions in real-time and in-situ. It was successfully used with a number of suspensions to visualise floc growth, the final aggregate structure and other aggregate properties of practical importance (strength, settling velocity, density). Image analysis was employed for quantitative floc characterisation by e.g. the fractal dimension. The findings were consistent with the DLVO theory of suspension stability and qualitative models of particle aggregation dynamics. Aggregation kinetics has been quantitatively studied by particle image velocimetry (PIV) analysis. These novel investigations suggest the principal applicability of the mini-chamber/microscope system for various research fields and suspended particle investigations, which are of interest not only for water industry purposes but also for the processing of heterogeneous systems in general. Design studies of simple, low-cost and disposable ultrasonic devices for such studies have been developed and a prototype tested successfully. (orig.)

  10. Examining the Effect of Temperature, Pressure, Seismicity and Diffuse Fluid Flow on Floc Events at Axial Seamount

    Science.gov (United States)

    Rahman, M.; Crone, T. J.; Knuth, F.; Garcia, C.; Soule, D. C.; Fatland, R.

    2017-12-01

    Flocculation (floc) events are characterized by the ejection of bacterial material, possibly associated with thermophiles originating from warmer sub-seafloor habitats, into the water column. These events are anecdotally linked to magmatic and tectonic processes common in mid-ocean ridge seafloor environments. However, little is known about the relationship between flocculation events and other potentially triggering processes. The Cabled Array at Axial Seamount provides a suite of interdisciplinary real-time datasets to examine system-level processes governing the volcanic marine environment. The eruption at Axial Seamount in 2015 creates an opportunity to study this volcanic system as it evolves post eruption and identify the relationships between the temperature, pressure, seismicity and the biological response. The Diffuse Vent Fluid 3-D Temperature Array (TMPSF), located within the ASHES hydrothermal vent field at Axial Seamount, uses 24 separate sensors to provide a 3-dimensional distribution of diffuse flow temperatures near the Mushroom hydrothermal vent. Preliminary analysis suggests that the temperature signal is strongly influenced by tides observed using the ocean bottom pressure sensors, which may be related to either gradual shifts in tidal currents above the seafloor, or related to subsurface flux. CamHD, also located within the ASHES field, produces high definition video data, which we analyze to identify changes in water column floc concentration. These data streams allow us to examine the controls on the temperature signal and the associated correlations with microbial seafloor processes. We are currently examining the flocculation event identified in Crone (2016) to determine its relationship to changes in seawater temperatures near the seafloor, seismic activity and seafloor pressure. We will use this proxy to examine other CamHD data and determine if subsequent flocculation events have occurred and if they have a similar relationship to local

  11. The influence of floc size and hydraulic detention time on the performance of a dissolved air flotation (DAF) pilot unit in the light of a mathematical model.

    Science.gov (United States)

    Moruzzi, R B; Reali, M A P

    2014-12-01

    The influence of floc size and hydraulic detention time on the performance of a dissolved air flotation (DAF) pilot unit was investigated in the light of a known mathematical model. The following design and operational parameters were considered: the hydraulic detention time (tdcz) and hydraulic loading rate in the contact zone, the down-flow loading rate in the clarification zone, the particle size distribution (d F), and the recirculation rate (p). As a reference for DAF performance analysis, the proposed β.td parameter from the above mentioned mathematical model was employed. The results indicated that tdcz is an important factor in DAF performance and that d F and floc size are also determinants of DAF efficiency. Further, β.td was sensitive to both design and operational parameters, which were varied in the DAF pilot plant. The performance of the DAF unit decreases with increasing β.td values because a higher td (considering a fixed β) or a higher β (e.g., higher hydrophobicity of the flocs for a fixed td) would be necessary in the reaction zone to reach desired flotation efficiency.

  12. Theoretical Insight into the Spectral Characteristics of Fe(II-Based Complexes for Dye-Sensitized Solar Cells—Part I: Polypyridyl Ancillary Ligands

    Directory of Open Access Journals (Sweden)

    Xiaoqing Lu

    2011-01-01

    Full Text Available The design of light-absorbent dyes with cheaper, safer, and more sustainable materials is one of the key issues for the future development of dye-sensitized solar cells (DSSCs. We report herein a theoretical investigation on a series of polypyridyl Fe(II-based complexes of FeL2(SCN2, [FeL3]2+, [FeL′(SCN3]-, [FeL′2]2+, and FeL′′(SCN2 (L = 2,2′-bipyridyl-4,4′-dicarboxylic acid, L′ = 2,2′,2″-terpyridyl-4,4′,4″-tricarboxylic acid, L″ = 4,4‴-dimethyl-2,2′ : 6′,2″ :6″,2‴-quaterpyridyl-4′,4″-biscarboxylic acid by density functional theory (DFT and time-dependent DFT (TD-DFT. Molecular geometries, electronic structures, and optical absorption spectra are predicted in both the gas phase and methyl cyanide (MeCN solution. Our results show that polypyridyl Fe(II-based complexes display multitransition characters of Fe → polypyridine metal-to-ligand charge transfer and ligand-to-ligand charge transfer in the range of 350–800 nm. Structural optimizations by choosing different polypyridyl ancillary ligands lead to alterations of the molecular orbital energies, oscillator strength, and spectral response range. Compared with Ru(II sensitizers, Fe(II-based complexes show similar characteristics and improving trend of optical absorption spectra along with the introduction of different polypyridyl ancillary ligands.

  13. The Oxidation of Fe(II) in Acidic Sulfate Solutions with Air at Elevated Pressures : Part 1. Kinetics above 1 M H2SO4

    NARCIS (Netherlands)

    Wermink, Wouter N.; Versteeg, Geert F.

    2017-01-01

    The oxidation of ferrous ions in acidic sulfate solutions at elevated air pressures was investigated. The effect of the Fe2+ concentration, initial H2SO4 concentration and partial oxygen pressure on the reaction rate were determined at three different temperatures, that is, T = 90, 70, and 50

  14. Flocs in Focus

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard

    of particles and carbon. The studies have used a recently developed camera system and demonstrate how micrometer imagery gives new and important information about the particle dynamics. The general assumption of flocculation always causing increased deposition is challenged. Chemical and biological reaction...... to coastal and marine ecosystems. Additionally, inorganic particle interactions with biological particles are likely to increase export of carbon to the deep ocean. Thus, there is a continued need for interdisciplinary thinking and study design to comprehend the suspended particle dynamics...

  15. Spin-dependent scattering and the spin polarization of a diffusive current in partly disordered L10 epitaxial FePd

    International Nuclear Information System (INIS)

    Seemann, K M; Hickey, M C; Baltz, V; Hickey, B J; Marrows, C H

    2010-01-01

    We report magnetic domain wall (DW) resistance in epitaxial films of FePd. When equal numbers of Fe and Pd atoms are present, this material forms an ordered structure with alternating crystal planes of Fe and Pd. We prepared films enriched with Pd to varying degrees, gradually degrading this structure. As might be expected, this increased the electrical resistivity of the films by introducing extra defects that can scatter electrons. However, unexpectedly, the additional resistance arising from the ∼10 nm thick DWs rose as a proportion of the overall resistivity, roughly doubling when halving the degree of chemical ordering-as determined from x-ray diffraction measurements-within the films. These data can be used to infer a rise in the spin polarization of the current flowing in the layers when extra Pd atoms are introduced. On the other hand, a separate measurement of spin polarization using a superconducting point contact technique that is insensitive to electron scattering revealed no changes as extra Pd was introduced. We conclude that Pd atoms scatter electrons of one spin far more strongly than the other, suggesting a possible means of producing highly spin-polarized currents for use in spintronic devices.

  16. Guidebook of the Western United States: Part C - The Santa Fe Route, with a side trip to Grand Canyon of the Colorado

    Science.gov (United States)

    Darton, Nelson Horatio; ,

    1916-01-01

    country he looks out upon, not as so many square miles of territory represented on the map in a railroad folder by meaningless spaces, but rather as land - real estate, if you please - varying widely in present appearance because differing largely in its history and characterized by even greater variation in values because possessing diversified natural resources. One region may be such as to afford a livelihood for only a pastoral people; another may present opportunity for intensive agriculture; still another may contain hidden stores of mineral wealth that may attract large industrial development; and taken together these varied resources afford the promise of long-continued prosperity for this or that State. Items of interest in civic development or references to significant epochs in the record of discovery and settlement may be interspersed with explanations of mountain and valley or statements of geologic history. In a broad way, the story of the West is a unit, and every chapter should be told in order to meet fully the needs of the tourist who aims to understand all that he sees. To such a traveler-reader this series of guidebooks is addressed. To this interpretation of our own country the United States Geological Survey brings the accumulated data of decades of pioneering investigation, and the present contribution is only one type of return to the public which has supported this scientific work under the Federal Government. In preparing the description of the country traversed by the Santa Fe Route the geographic and geologic information already published as well as unpublished material in the possession of the Geological Survey has been utilized, but to supplement this material Mr. Darton made a field examination of the entire route in 1914. Information has been furnished by Erasmus Haworth, J. E. Todd, and R. T. Hill, as well as by others whose writings are listed in the bibliography at the end of the text. Cooperation has been rendered by the United States

  17. Development of a wear-resistant flux cored wire of Fe-C-Si-Mn-Cr-Ni-Mo-V system for deposit welding of mining equipment parts

    Science.gov (United States)

    Osetkovsky, I. V.; Kozyrev, N. A.; Kryukov, R. E.; Usoltsev, A. A.; Gusev, A. I.

    2017-09-01

    The effect of introduction of cobalt in the charge of the flux cored wire of Fe-C-Si-Mn-Cr-Ni-Mo-V system operating under abrasive and abrasive-shock loads is studied. In the laboratory conditions samples of flux cored wires were made, deposition was performed, the effect of cobalt on the hardness and the degree of wear was evaluated, metallographic studies were carried out. The influence of cobalt introduced into the charge of the flux cored wire of Fe-C-Si-Mn-Cr-Ni-Mo-V system on the structure, nature of nonmetallic inclusions, hardness and wear resistance of the weld metal was studied. In the laboratory conditions samples flux cored wire were made using appropriate powdered materials. As a carbon-fluorine-containing material dust from gas cleaning units of aluminum production was used. In the course of the study the chemical composition of the weld metal was determined, metallographic analysis was performed, mechanical properties were determined. As a result of the metallographic analysis the size of the former austenite grain, martensite dispersion in the structure of the weld metal, the level of contamination with its nonmetallic inclusions were established.

  18. Klimt artwork (Part II): material investigation by backscattering Fe-57 Mössbauer- and Raman- spectroscopy, SEM and p-XRF

    Energy Technology Data Exchange (ETDEWEB)

    Costa, B. F. O. [University of Coimbra, CFisUC, Physics Department (Portugal); Lehmann, R.; Wengerowsky, D. [Leibniz Universität Hannover, Institut für Anorganische Chemie (Germany); Blumers, M. [Joh. Gutenberg-Universität Mainz, Institut für Anorganische Chemie und Analytische Chemie (Germany); Sansano, A.; Rull, F. [Unidad Asociada UVA-CSIC Centro de Astrobiologia (Spain); Schmidt, H.-J. [Leibniz Universität Hannover, Institut für Anorganische Chemie (Germany); Dencker, F. [Hochschule Hannover, Fakultät II-Maschinenbau und Bioverfahrenstechnik (Germany); Niebur, A. [Technische Universität Dresden, Institut für Physikalische Chemie (Germany); Klingelhöfer, G. [Joh. Gutenberg-Universität Mainz, Institut für Anorganische Chemie und Analytische Chemie (Germany); Sindelar, R. [Hochschule Hannover, Fakultät II-Maschinenbau und Bioverfahrenstechnik (Germany); Renz, F., E-mail: renz@acd.uni-hannover.de [Leibniz Universität Hannover, Institut für Anorganische Chemie (Germany)

    2016-12-15

    In a rediscovered Klimt-artwork “Trompetender Putto” material tests have been conducted. We report studies on different points of the painting. The spots are of different colors, mainly taken in spots of the painting not restaurated. MIMOS II Fe-57 Mössbauer spectroscopy revealed mainly haematite and nano particle oxides in red and red/brown colors. Brown colors also contain crystallized goethite. In brown/ochre colors the same pigments as in brown colors are observed, but there is less quantity of goethite and more quantity of haematite. The green colors show Fe-rich clays, like celadonite or glauconite and or lepidocrocite as main component. Raman spectroscopy revealed cinnabar in red colors of the Scarf; and massicot in brown/ochre points, i.e. in the Left Wing of the “Putto”. With scanning electron microscopy, various layers of the original and of overpainting could be recognized. The investigations of sample 1 show three layers of colored materials, which were identified as zinc-white, cinnabar and galena as well as carbon compounds. In sample 2 four layers could be detected. These are identified (bottom to top) as gypsum and lead-white (layer 1), zinc-white (layer 2), lead-white and cinnabar (layer 3) and titanium-white (layer 4). The elementary composition was examined with the portable X-ray-fluorescence analysis for qualitative manner at different points.

  19. Wear Micro-Mechanisms of Composite WC-Co/Cr - NiCrFeBSiC Coatings. Part I: Dry Sliding

    Directory of Open Access Journals (Sweden)

    D. Kekes

    2014-12-01

    Full Text Available The influence of the cermet fraction in cermet/ metal composite coatings developed by High-Velocity Oxyfuel Flame (HVOF spraying on their tribological behaviour was studied. Five series of coatings, each one containing different proportion of cermet-metal components, prepared by premixing commercially available feedstocks of NiCrFeBSiC metallic and WC-Co/Cr cermet powders were deposited on AISI 304 stainless steel substrate. The microstructure of as-sprayed coatings was characterized by partial decomposition of the WC particles, lamellar morphology and micro-porosity among the solidified splats. Tribological behavior was studied under sliding friction conditions using a Si3N4 ball as counterbody and the friction coefficient and volume loss were determined as a function of the cermet fraction. Microscopic examinations of the wear tracks and relevant cross sections identified the wear mechanisms involved. Coatings containing only the metallic phase were worn out through a combination of ploughing, micro-cracking and splat exfoliation, whilst those containing only the cermet phase primarily by micro-cracking at the individual splat scale. The wear mechanisms of the composite coatings were strongly affected by their randomly stratified structure. In-depth cracks almost perpendicular to the coating/ substrate interface occurring at the wear track boundaries resulted in cermet trans-splat fracture.

  20. Magnetism of cyano-bridged Ln3+-M3+ complexes. Part II: one-dimensional complexes (Ln3+ = Eu, Tb, Dy, Ho, Er, Tm; M3+ = Fe or Co) with bpy as blocking ligand.

    Science.gov (United States)

    Figuerola, Albert; Ribas, Joan; Casanova, David; Maestro, Miguel; Alvarez, Santiago; Diaz, Carmen

    2005-10-03

    The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to 13 one-dimensional complexes: trans-[M(CN)4(mu-CN)2Ln(H2O)4(bpy)]n.4nH2O.1.5nbpy (Ln = Eu3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Lu3+; M = Fe3+, Co3+). The structures for [EuFe]n (1), [TbFe]n (2), [DyFe]n (3), [HoFe]n (4), [ErFe]n (5), [TmFe]n (6), [LuFe]n (7), [EuCo]n (8), [TbCo]n (9), [DyCo]n (10), [HoCo]n (11), [ErCo]n (12), and [TmCo]n (13) have been solved: they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular architecture created by the interplay of coordinative, hydrogen bonding, and pi-pi interactions. A stereochemical study of the eight-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. The Ln3+-Fe3+ interaction is antiferromagnetic in [DyFe]n and [TbFe]n. For [EuFe]n, [HoFe]n, [ErFe]n, and [TmFe]n, there is no sign of any significant interaction. The magnetic behavior of [DyFe]n suggests the onset of weak long-range ferromagnetic ordering at 2.5 K.

  1. Moessbauer-spectroscopic study of structure and magnetism of the exchange-coupled layer systems Fe/FeSn{sub 2}, and Fe/FeSi/Si and the ion-implanted diluted magnetic semiconductor SiC(Fe); Moessbauerspektroskopische Untersuchung von Struktur und Magnetismus der austauschgekoppelten Schichtsysteme Fe/FeSn{sub 2} und Fe/FeSi/Si und des ionenimplantierten verduennten magnetischen Halbleiters SiC(Fe)

    Energy Technology Data Exchange (ETDEWEB)

    Stromberg, Frank

    2009-07-07

    In line with this work the structural and magnetic properties of the exchange coupled layered systems Fe/FeSn{sub 2} and Fe/FeSi/Si and of the Fe ion implanted diluted magnetic semiconductor (DMS) SiC(Fe) were investigated. The main measuring method was the isotope selective {sup 57}Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the {sup 57}Fe tracer layer technique, in a temperature range from 4.2 K to 340 K. Further measurement techniques were X-ray diffraction (XRD), electron diffraction (LEED, RHEED), SQUID magnetometry and FMR (Ferromagnetic Resonance). In the first part of this work the properties of thin AF FeSn{sub 2}(001) films and of the exchange-bias system Fe/FeSn{sub 2}(001) on InSb(001) were investigated. With the application of {sup 57}Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (B{sub hf}) of FeSn{sub 2} could be examined. The evaporation of Fe films on the FeSn{sub 2} films produced in the latter ones a high perpendicular spin component at the Fe/FeSn{sub 2} interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore {sup 57}Fe-CEMS provided a correlation between the absolute value of the exchange field vertical stroke He vertical stroke and the amount of magnetic defects within the FeSn{sub 2}. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures T{sub B}{sup *}, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures T{sub B} of the exchange-bias effect, obtained with magnetometry measurements. The second part of this work deals with the indirect exchange coupling within Fe/FeSi/Si/FeSi/Fe multilayers and FeSi diffusion barriers. The goal was to achieve Fe free Si interlayers. The CEMS results show that starting from a thickness of t{sub FeSi}=10-12 A of the

  2. Lattice locations and properties of Fe in Co/Fe co-implanted ZnO

    DEFF Research Database (Denmark)

    Gunnlaugsson, H.P.; Johnston, K.; Mølholt, T.E.

    2012-01-01

    and the remaining fraction as Fe2+ in damage sites of interstitial character. After annealing at 773 K, ∼20% remain on crystalline sites, while the damage fraction has partly disappeared and instead a ∼30% fraction occurs as high‐spin Fe3+, presumably in precipitates. This suggests that precipitation of Co/Fe in Zn......The lattice locations and electronic configurations of Fe in 57Co/57Fe implanted ZnO (to (5‐6) × 1014 Fe/cm−2) have been studied by 57Fe Mössbauer emission spectroscopy. The spectra acquired upon room temperature implantation show ∼20% of the probe atoms as Fe2+ on perturbed Zn sites...

  3. Silicon induced Fe deficiency affects Fe, Mn, Cu and Zn distribution in rice (Oryza sativa L.) growth in calcareous conditions.

    Science.gov (United States)

    Carrasco-Gil, Sandra; Rodríguez-Menéndez, Sara; Fernández, Beatriz; Pereiro, Rosario; de la Fuente, Vicenta; Hernandez-Apaolaza, Lourdes

    2018-02-01

    A protective effect by silicon in the amelioration of iron chlorosis has recently been proved for Strategy 1 species, at acidic pH. However in calcareous conditions, the Si effect on Fe acquisition and distribution is still unknown. In this work, the effect of Si on Fe, Mn, Cu and Zn distribution was studied in rice (Strategy 2 species) under Fe sufficiency and deficiency. Plants (+Si or-Si) were grown initially with Fe, and then Fe was removed from the nutrient solution. The plants were then analysed using a combined approach including LA-ICP-MS images for each element of interest, the analysis of the Fe and Si concentration at different cell layers of root and leaf cross sections by SEM-EDX, and determining the apoplastic Fe, total micronutrient concentration and oxidative stress indexes. A different Si effect was observed depending on plant Fe status. Under Fe sufficiency, Si supply increased Fe root plaque formation, decreasing Fe concentration inside the root and increasing the oxidative stress in the plants. Therefore, Fe acquisition strategies were activated, and Fe translocation rate to the aerial parts was increased, even under an optimal Fe supply. Under Fe deficiency, +Si plants absorbed Fe from the plaque more rapidly than -Si plants, due to the previous activation of Fe deficiency strategies during the growing period (+Fe + Si). Higher Fe plaque formation due to Si supply during the growing period reduced Fe uptake and could activate Fe deficiency strategies in rice, making it more efficient against Fe chlorosis alterations. Silicon influenced Mn and Cu distribution in root. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  4. Understanding FE Mergers. Research Report

    Science.gov (United States)

    Calvert, Natasha

    2009-01-01

    This report presents research findings and discussion to help develop an understanding of what gives rise to mergers and, when they do happen, what makes them work. The research has focused on merger activity between further education (FE) colleges since incorporation in 1993. Mergers are highly contextual, and part of ensuring success is…

  5. Síntese de ferrita NiFe2O4 e sua incorporação em compósitos de poliamida 6: Parte 1: caracterização estrutural por drx e mev dos pós e dos compósitos Synthesis of NiFe2O4 ferrite and its incorporation in nylon 6: Part 1: structural characterization by xrd and sem of ferrite powders and its composites

    Directory of Open Access Journals (Sweden)

    Daniella C. Bezerra

    2010-01-01

    Full Text Available As ferritas geralmente são absorvedoras de radiação eletromagnética e apresentam a versatilidade de poderem ser manufaturadas com geometrias diferentes, e usadas na forma de ferritas policristalinas (corpo sinterizado ou de compósitos de ferrita (adição de pó em matriz apropriada. A poliamida 6, por sua vez, pertence a uma classe de polímeros atraentes para aplicações em engenharia devido à combinação de propriedades como: estabilidade dimensional, boa resistência ao impacto sem entalhe e excelente resistência química. O objetivo deste trabalho foi sintetizar pós de ferrita NiFe2O4, e avaliar a adição destes em concentrações de 10, 30, 50 e 60% em massa a uma matriz polimérica de poliamida 6 usando um misturador da Haake Blücher, para obter compósitos de poliamida 6/NiFe2O4. Os pós e os compósitos foram caracterizados por difração de raios X (DRX e microscopia eletrônica de varredura (MEV. Os difratogramas de raios X mostraram picos característicos da poliamida 6 e da ferrita. Por MEV foi observada a formação de aglomerados grandes para a concentração de 60% e, uma grande quantidade de poros. Para a concentração de 10%, as partículas ficaram mais dispersas, com menos aglomerados e menos poros no compósito.Ferrites normally absorb electromagnetic radiation, being versatile in that they can be manufactured in different geometries and used as polycrystalline ferrites (sintered body or composites of ferrite (with addition of the powder to an appropriate matrix. On the other hand, nylon 6 is an attractive polymer for engineering applications due to the combination of properties such as dimensional stability, good impact strength without notch indentation and excellent chemical resistance. The aim of this paper was to synthesize ferrite (NiFe2O4 powders and to evaluate their addition in concentrations of 10, 30, 50 and 60 wt% into a nylon 6 polymer matrix using a Haake Blücher mixer. The powders and the

  6. Magnetic properties of cyano-bridged Ln3+-M3+ complexes. Part I: trinuclear complexes (Ln3+ = La, Ce, Pr, Nd, Sm; M3+ = FeLS, Co) with bpy as blocking ligand.

    Science.gov (United States)

    Figuerola, Albert; Ribas, Joan; Llunell, Miquel; Casanova, David; Maestro, Miguel; Alvarez, Santiago; Diaz, Carmen

    2005-10-03

    The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to eight trinuclear complexes: trans-[M(CN)4(mu-CN)2{Ln(H2O)4(bpy)2}2][M(CN)6].8H2O (M = Fe3+ or Co3+, Ln = La3+, Ce3+, Pr3+, Nd3+, and Sm3+). The structures for the eight complexes [La2Fe] (1), [Ce2Fe] (2), [Pr2Fe] (3), [Nd2Fe] (4), [Ce2Co] (5), [Pr2Co] (6), [Nd2Co] (7), and [Sm2Co] (8) have been solved; they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular 3D architecture through hydrogen bonding and pi-pi stacking interactions. A stereochemical study of the nine-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. No significant magnetic interaction was found between the lanthanide(III) and the iron(III) ions.

  7. Flooding impairs Fe uptake and distribution in Citrus due to the strong down-regulation of genes involved in Strategy I responses to Fe deficiency in roots.

    Directory of Open Access Journals (Sweden)

    Mary-Rus Martínez-Cuenca

    Full Text Available This work determines the ffects of long-term anoxia conditions--21 days--on Strategy I responses to iron (Fe deficiency in Citrus and its impact on Fe uptake and distribution. The study was carried out in Citrus aurantium L. seedlings grown under flooding conditions (S and in both the presence (+Fe and absence of Fe (-Fe in nutritive solution. The results revealed a strong down-regulation (more than 65% of genes HA1 and FRO2 coding for enzymes proton-ATPase and Ferric-Chelate Reductase (FC-R, respectively, in -FeS plants when compared with -Fe ones. H+-extrusion and FC-R activity analyses confirmed the genetic results, indicating that flooding stress markedly repressed acidification and reduction responses to Fe deficiency (3.1- and 2.0-fold, respectively. Waterlogging reduced by half Fe concentration in +FeS roots, which led to 30% up-regulation of Fe transporter IRT1, although this effect was unable to improve Fe absorption. Consequently, flooding inhibited 57Fe uptake in +Fe and -Fe seedlings (29.8 and 66.2%, respectively and 57Fe distribution to aerial part (30.6 and 72.3%, respectively. This evidences that the synergistic action of both enzymes H+-ATPase and FC-R is the preferential regulator of the Fe acquisition system under flooding conditions and, hence, their inactivation implies a limiting factor of citrus in their Fe-deficiency tolerance in waterlogged soils.

  8. Phase relations in the Fe-Fe3C-Fe3N system at 7.8 GPa and 1350 °C: Implications for carbon and nitrogen hosts in Fe0-saturated upper mantle

    Science.gov (United States)

    Sokol, Alexander G.; Kruk, Alexey N.; Seryotkin, Yurii V.; Korablin, Alexander A.; Palyanov, Yury N.

    2017-04-01

    Phase relations in the Fe-Fe3C-Fe3N system are studied in high-pressure experiments at 7.8 GPa and 1350 °C using a split-sphere multi-anvil apparatus. The starting mixtures consisting of Fe, Fe3C and Fe3N are loaded into ceramic or graphite capsules. Contamination with trace amounts of oxygen leads to the appearance of wüstite in the system retaining oxygen fugacity (fO2) near the iron-wüstite (IW) buffer. The metal melt rich in carbon and nitrogen has a large stability field in the central part of the phase diagram, and this field at 1350 °C is tangent to the Fe-Fe3C side of the Fe-Fe3C-Fe3N triangle at the point of the Fe-Fe3C eutectics. Iron nitride ε-Fe3N (space group P6322 or P63/mmc) contains variable amounts of C and N: up to 2.0-2.5 wt% C and 6.0-7.3 wt% N in equilibrium with a C- and N-rich melt and as little as 1.0 wt% C and 3.2 wt% N in equilibrium with γ- Fe. The limit C and N contents in γ-Fe equilibrated with the C- and N-rich melt is about 1.0 wt%, while the N solubility in cementite (Fe3C) does not exceed 0.5 wt%. The obtained data make basis for the isothermal section of the Fe-Fe3C-Fe3N system. The metal melt phase is inferred to be the main host of carbon and nitrogen in the Fe0-saturated (0.1 wt%) mantle at a depth of ∼250 km. In particular, C- and N-bearing austenite (γ-Fe) and metal melts host carbon and nitrogen in the mantle depleted in volatiles (20 ppm C and 1 ppm N), whereas carbon and nitrogen in the mantle with high concentrations of volatiles (250 ppm C and 100 ppm N) reside in C- and N-rich melts with a minor amount of iron carbide (Fe3C). The presence of nickel and sulphur in metal are expected to inhibit the formation of iron carbide and increases the melt phase stability. Redox freezing of N-rich carbonate melts from subduction slabs in Fe0-saturated mantle may produce iron melts supersaturated with nitrogen and stable ε-Fe3N.

  9. Radiation leukemogenesis in mice: loss of PU.1 on chromosome 2 in CBA and C57BL/6 mice after irradiation with 1 GeV/nucleon 56Fe ions, X rays or gamma rays. Part I. Experimental observations.

    Science.gov (United States)

    Peng, Yuanlin; Brown, Natalie; Finnon, Rosemary; Warner, Christy L; Liu, Xianan; Genik, Paula C; Callan, Matthew A; Ray, F Andrew; Borak, Thomas B; Badie, Christophe; Bouffler, Simon D; Ullrich, Robert L; Bedford, Joel S; Weil, Michael M

    2009-04-01

    Since deletion of the PU.1 gene on chromosome 2 is a crucial acute myeloid leukemia (AML) initiating step in the mouse model, we quantified PU.1 deleted cells in the bone marrow of gamma-, X- and 56Fe-ion-irradiated mice at various times postirradiation. Although 56Fe ions were initially some two to three times more effective than X or gamma rays in inducing PU.1 deletions, by 1 month postirradiation, the proportions of cells with PU.1 deletions were similar for the HZE particles and the sparsely ionizing radiations. These results indicate that while 56Fe ions are more effective in inducing PU.1 deletions, they are also more effective in causing collateral damage that removes hit cells from the bone marrow. After X, gamma or 56Fe-ion irradiation, AML-resistant C57BL/6 mice have fewer cells with PU.1 deletions than CBA mice, and those cells do not persist in the bone marrow of the C57B6/6 mice. Our findings suggest that quantification of PU.1 deleted bone marrow cells 1 month postirradiation can be used as surrogate for the incidence of radiation-induced AML measured in large-scale mouse studies. If so, PU.1 loss could be used to systematically assess the potential leukemogenic effects of other ions and energies in the space radiation environment.

  10. Study of the reaction of astrophysical interest 60Fe(n,γ)61Fe via (d,pγ) transfer reaction

    International Nuclear Information System (INIS)

    Giron, S.

    2011-12-01

    60 Fe is of special interest in nuclear astrophysics. Indeed the recent observations of 60 Fe characteristic gamma-ray lines by the RHESSI and INTEGRAL spacecrafts allowed to measure the total flux of 60 Fe over the Galaxy. Moreover the observation in presolar grains of an excess of the daughter-nuclei of 60 Fe, 60 Ni, gives constraints on the conditions of formation of the early solar system. However, the cross-sections of some reactions involved in 60 Fe nucleosynthesis and included to stellar models are still uncertain. The destruction reaction of 60 Fe, 60 Fe(n, γ) 61 Fe, is one of them. The total cross-section can be separate into two contributions: the direct one, involving states below the neutron separation threshold of 61 Fe, and the resonant one.We improved 61 Fe spectroscopy in order to evaluate the direct capture part of the 60 Fe(n, γ) 61 Fe reaction cross-section. 60 Fe(n, γ) 61 Fe was thus studied via d( 60 Fe, pγ) 61 Fe transfer reaction with the CATS/MUST2/EXOGAM setup at LISE-GANIL. DWBA analysis of experimental proton differential cross-sections allowed to extract orbital angular momentum and spectroscopic factors of different populated states identified below the neutron threshold. A comparison of experimental results for 61 Fe with experimental results for similar nuclei and with shell-model calculations was also performed. (author) [fr

  11. High efficient removal of molybdenum from water by Fe2(SO4)3: Effects of pH and affecting factors in the presence of co-existing background constituents.

    Science.gov (United States)

    Zhang, Xiang; Ma, Jun; Lu, Xixin; Huangfu, Xiaoliu; Zou, Jing

    2015-12-30

    Comparatively investigated the different effects of Fe2(SO4)3 coagulation-filtration and FeCl3 coagulation-filtration on the removal of Mo (VI). And the influence of calcium, sulfate, silicate, phosphate and humic acid (HA) were also studied. The following conclusions can be obtained: (1) compared with the case of FeCl3, Fe2(SO4)3 showed a higher Mo (VI) removal efficiency at pH 4.00-5.00, but an equal removal efficiency at pH 6.00-9.00. (2) The optimum Mo (VI) removal by Fe2(SO4)3 was achieved at pH 5.00-6.00; (3) The presence of calcium can reduce the removal of Mo (VI) over the entire pH range in the present study; (4) The effect of co-existing background anions (including HA) was dominated by three factors: Firstly the influence of co-existing background anions on the content of Fe intercepted from water (intercepted Fe). Secondly the competition of co-existing anions with Mo (VI) for adsorption sites. Thirdly the influence of co-existing background anions on the Zeta potential of the iron flocs. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Can Biomass Burning Explain Isotopically Light Fe in Marine Aerosols?

    Science.gov (United States)

    Sherry, A. M.; Anbar, A. D.; Herckes, P.; Romaniello, S. J.

    2016-02-01

    Iron (Fe) is an important micronutrient that limits primary productivity in large parts of the ocean. In these regions, atmospheric aerosol deposition is an important source of Fe to the surface ocean and thus has a critical impact on ocean biogeochemistry. Fe-bearing aerosols originate from many sources with potentially distinct Fe isotopic compositions. Consequently, Fe isotopes may provide a new tool to trace the sources of aerosol Fe to the oceans. Mead et al. (2013) first discovered that Fe in the fine fraction of Bermuda aerosols is often isotopically lighter than Fe from known anthropogenic and crustal sources. 1 These authors suggested that this light isotopic signature was likely the result of biomass burning, since Fe in plants is the only known source of isotopically light Fe. More recently, Conway et al. found that Fe in the soluble fraction of aerosols collected during 2010-2011 North Atlantic GEOTRACES cruises also showed light isotope values, which they likewise attributed to biomass burning.2 These studies are further supported by new modeling work which suggests that biomass burning aerosols should contribute significant amounts of soluble Fe to tropical and southern oceans.3To test if biomass burning releases aerosols with a light Fe isotope composition, we are conducting lab-scale biomass burning experiments using natural samples of vegetation and leaf litter. Burn aerosols were collected on cellulose filters, then digested and analyzed for trace metal concentrations using inductively-coupled mass spectrometry (ICP-MS). Fe isotopes were determined by using multiple collector ICP-MS following separation and purification of Fe using anion exchange chromatography. We will discuss metal concentration and isotope data from these experiments with implications for the interpretation of Fe isotope signals in aerosol samples. 1Mead, C et al. GRL, 2013, 40, 5722-5727. 2 Conway, T et al. Goldschmidt Abs 2015 593. 3Ito, A. ES&T Lett, 2015, 2, 70-75.

  13. Enhanced dewaterability of sewage sludge in the presence of Fe(II)-activated persulfate oxidation.

    Science.gov (United States)

    Zhen, Guangyin; Lu, Xueqin; Zhao, Youcai; Chai, Xiaoli; Niu, Dongjie

    2012-07-01

    The potential benefits of Fe(II)-activated persulfate oxidation on sludge dewatering and its mechanisms were investigated in this study. Capillary suction time (CST) was used to evaluate sludge dewaterability. Both extracellular polymeric substances (EPS) and viscosity were determined in an attempt to explain the observed changes in sludge dewaterability. The optimal conditions to give preferable dewaterability characteristics were found to be persulfate (S(2)O(8)(2-)) 1.2 mmol/gVSS, Fe(II) 1.5 mmol/gVSS, and pH 3.0-8.5, which demonstrated a very high CST reduction efficiency (88.8% reduction within 1 min). It was further observed that both soluble EPS and viscosity played relatively negative roles in sludge dewatering, whereas no correlation was established between sludge dewaterability and bound EPS. Three-dimensional excitation-emission matrix (EEM) fluorescence spectra also revealed that soluble EPS of sludge were degraded and sludge flocs were ruptured by persulfate oxidation, which caused the release of water in the intracellular pace and subsequent improvement of its dewaterability. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. M = Mn, Fe, Co

    Indian Academy of Sciences (India)

    ment as a result of incomplete combustion of fossil fuels can lead to harmful health effects by reducing oxygen delivery to ... fuel cells, and oxygen sensors. The oxygen storage and release in ceria is favoured by its ...... tion of Fe2O3 → Fe3O4, the consumption of surface. CeO2 and overlapping of the reduction of Fe3O4 →.

  15. The redox state of arc mantle using Zn/Fe systematics.

    Science.gov (United States)

    Lee, Cin-Ty A; Luffi, Peter; Le Roux, Véronique; Dasgupta, Rajdeep; Albaréde, Francis; Leeman, William P

    2010-12-02

    Many arc lavas are more oxidized than mid-ocean-ridge basalts and subduction introduces oxidized components into the mantle. As a consequence, the sub-arc mantle wedge is widely believed to be oxidized. The Fe oxidation state of sub-arc mantle is, however, difficult to determine directly, and debate persists as to whether this oxidation is intrinsic to the mantle source. Here we show that Zn/Fe(T) (where Fe(T) = Fe(2+) + Fe(3+)) is redox-sensitive and retains a memory of the valence state of Fe in primary arc basalts and their mantle sources. During melting of mantle peridotite, Fe(2+) and Zn behave similarly, but because Fe(3+) is more incompatible than Fe(2+), melts generated in oxidized environments have low Zn/Fe(T). Primitive arc magmas have identical Zn/Fe(T) to mid-ocean-ridge basalts, suggesting that primary mantle melts in arcs and ridges have similar Fe oxidation states. The constancy of Zn/Fe(T) during early differentiation involving olivine requires that Fe(3+)/Fe(T) remains low in the magma. Only after progressive fractionation does Fe(3+)/Fe(T) increase and stabilize magnetite as a fractionating phase. These results suggest that subduction of oxidized crustal material may not significantly alter the redox state of the mantle wedge. Thus, the higher oxidation states of arc lavas must be in part a consequence of shallow-level differentiation processes, though such processes remain poorly understood.

  16. Magnetic properties of Sm5Fe17 melt-spun ribbons and their borides

    Directory of Open Access Journals (Sweden)

    Tetsuji Saito

    2015-10-01

    Full Text Available Sm5Fe17 melt-spun ribbons exhibited low coercivity and partly or mostly consisted of the amorphous phase. Annealing of Sm5Fe17 melt-spun ribbon resulted in the formation of the Sm5Fe17 phase. The annealed Sm5Fe17 melt-spun ribbon exhibited a high coercivity. It was found that the addition of B to the Sm5Fe17 alloy resulted in the promotion of the Sm2Fe14B phase. Annealed Sm5Fe17Bx (x = 0.5 melt-spun ribbons consisted of the Sm5Fe17 phase together with the Sm2Fe14B and SmFe2 phases. On the other hand, annealed Sm5Fe17Bx (x = 1.0-1.5 melt-spun ribbons consisted of the Sm2Fe14B and SmFe2 phases without the Sm5Fe17 phase. The resultant Sm5Fe17Bx (x = 1.0-1.5 melt-spun ribbons still showed a coercivity of around 2 kOe. The annealed Sm5Fe17 melt-spun ribbon exhibited a high coercivity over 25 kOe and a remanence of 40 emu/g, whereas the annealed Sm5Fe17B1.0 melt-spun ribbon exhibited a high remanence of 65 emu/g and a coercivity of 2.0 kOe.

  17. Electrical studies of Fe-related defect complexes in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chi Kwong

    2012-09-15

    and thermal stability, measurements were performed around the projected range of Fe-implantations after rapid thermal annealing. A shallow acceptor is uncovered with an energy level position of EV +0.06 eV and a defect concentration closely following the calculated concentration of the Fe-implantation dose. However, chemical analysis with secondary ion-mass spectrometry shows out-diffusion of Fe from the region around the projected range after annealing. This suggests that the formation of the shallow acceptor is only assisted/promoted by Fe without Fe being a part of the final complex.(Author)

  18. Enhanced antibacterial performance of Fe3O4–Ag and MnFe2O4 ...

    Indian Academy of Sciences (India)

    In this work, we have described the antibacterial activities of Fe 3 O 4 nanoparticles with different organic parts, including Humic acid (HA), Nicotinic acid (Nico) and Histidine (His), and the antibacterial activity ofMnFe 2 O 4 nanoparticles coated with PANI and SiO 2 against different bacteria and some standard antibacterial ...

  19. Fe (III) complex of mefloquine hydrochloride: Synthesis ...

    African Journals Online (AJOL)

    As part of the ongoing research for more effective antimalarial drug, Fe (III) complex of mefloquine hydrochloride (antimalarial drug) was synthesized using template method. Mefloquine was tentatively found to have coordinated through the hydroxyl and the two nitrogen atoms in the quinoline and piperidine in the structure, ...

  20. Phosphorus Equilibrium Between Liquid Iron and CaO-SiO2-MgO-Al2O3-FeO-P2O5 Slag Part 1: Literature Review, Methodology, and BOF Slags

    Science.gov (United States)

    Assis, Andre N.; Tayeb, Mohammed A.; Sridhar, Seetharaman; Fruehan, Richard J.

    2015-10-01

    Although the phosphorus reaction in steelmaking has been extensively studied, it continues to be a relevant topic as low phosphorus iron sources become less available and more expensive, necessitating the need for more accurate predictions of the partitioning of phosphorous as function of slag composition and temperature. The current study revisits some of the relevant literature on the topic and details the methodology and experimental setup used in recent studies on phosphorus equilibrium between liquid iron and slags. New data for BOF-type slags are presented, where equilibrium was approached from both metal and slag sides i.e., phosphorus was transferred from metal to slag and vice versa. It was found that slags with basicities higher than 2.5 and FeO contents around 20 to 25 wt pct can promote extensive dephosphorization, and high L P, ((pct P)/[pct P]), values were observed i.e., greater than 500.

  1. Fe atom exchange between aqueous Fe2+ and magnetite.

    Science.gov (United States)

    Gorski, Christopher A; Handler, Robert M; Beard, Brian L; Pasakarnis, Timothy; Johnson, Clark M; Scherer, Michelle M

    2012-11-20

    The reaction between magnetite and aqueous Fe(2+) has been extensively studied due to its role in contaminant reduction, trace-metal sequestration, and microbial respiration. Previous work has demonstrated that the reaction of Fe(2+) with magnetite (Fe(3)O(4)) results in the structural incorporation of Fe(2+) and an increase in the bulk Fe(2+) content of magnetite. It is unclear, however, whether significant Fe atom exchange occurs between magnetite and aqueous Fe(2+), as has been observed for other Fe oxides. Here, we measured the extent of Fe atom exchange between aqueous Fe(2+) and magnetite by reacting isotopically "normal" magnetite with (57)Fe-enriched aqueous Fe(2+). The extent of Fe atom exchange between magnetite and aqueous Fe(2+) was significant (54-71%), and went well beyond the amount of Fe atoms found at the near surface. Mössbauer spectroscopy of magnetite reacted with (56)Fe(2+) indicate that no preferential exchange of octahedral or tetrahedral sites occurred. Exchange experiments conducted with Co-ferrite (Co(2+)Fe(2)(3+)O(4)) showed little impact of Co substitution on the rate or extent of atom exchange. Bulk electron conduction, as previously invoked to explain Fe atom exchange in goethite, is a possible mechanism, but if it is occurring, conduction does not appear to be the rate-limiting step. The lack of significant impact of Co substitution on the kinetics of Fe atom exchange, and the relatively high diffusion coefficients reported for magnetite suggest that for magnetite, unlike goethite, Fe atom diffusion is a plausible mechanism to explain the rapid rates of Fe atom exchange in magnetite.

  2. An iron complex with an unsupported Fe-Fe bond.

    Science.gov (United States)

    Murillo, Carlos A

    2009-01-01

    Full metal bonding: The reduction of a six-coordinate, mononuclear Werner-type iron(II) complex (see scheme) resulted in the isolation of a compound with an extraordinarily rare, unsupported Fe-Fe bond having an experimental Fe-Fe distance of 2.6869(6) A and a calculated bond order of 0.5.

  3. Development of Aircraft Sandwich Parts

    Directory of Open Access Journals (Sweden)

    J. Křena

    2000-01-01

    Full Text Available The presented paper shows the design and development process of sandwich parts. A spoiler plate and a main landing gear door are developed. Sandwich parts are made of C/E composite facings and a foam core. FE models have been used for optimization of structures. Emphasis has been placed on deformations of parts under a few load cases. Experimental tests have been used for a verification of structure parts loaded by concentrated forces.

  4. Mechanisms of Fe biofortification and mitigation of Cd accumulation in rice (Oryza sativa L.) grown hydroponically with Fe chelate fertilization.

    Science.gov (United States)

    Chen, Zhe; Tang, Ye-Tao; Zhou, Can; Xie, Shu-Ting; Xiao, Shi; Baker, Alan J M; Qiu, Rong-Liang

    2017-05-01

    Cadmium contaminated rice from China has become a global food safety issue. Some research has suggested that chelate addition to substrates can affect metal speciation and plant metal content. We investigated the mitigation of Cd accumulation in hydroponically-grown rice supplied with EDTANa 2 Fe(II) or EDDHAFe(III). A japonica rice variety (Nipponbare) was grown in modified Kimura B solution containing three concentrations (0, 10, 100 μΜ) of the iron chelates EDTANa 2 Fe(II) or EDDHAFe(III) and 1 μΜ Cd. Metal speciation in solution was simulated by Geochem-EZ; growth and photosynthetic efficiency of rice were evaluated, and accumulation of Cd and Fe in plant parts was determined. Net Cd fluxes in the meristematic zone, growth zone, and maturation zone of roots were monitored by a non-invasive micro-test technology. Expression of Fe- and Cd-related genes in Fe-sufficient or Fe-deficient roots and leaves were studied by QRT-PCR. Compared to Fe deficiency, a sufficient or excess supply of Fe chelates significantly enhanced rice growth by elevating photosynthetic efficiency. Both Fe chelates increased the Fe content and decreased the Cd content of rice organs, except for the Cd content of roots treated with excess EDDHAFe(III). Compared to EDDHAFe(III), EDTANa 2 Fe(II) exhibited better mitigation of Cd accumulation in rice by generating the EDTANa 2 Cd complex in solution, decreasing net Cd influx and increasing net Cd efflux in root micro-zones. Application of EDTANa 2 Fe(II) and EDDHAFe(III) also reduced Cd accumulation in rice by inhibiting expression of genes involved in transport of Fe and Cd in the xylem and phloem. The 'win-win' situation of Fe biofortification and Cd mitigation in rice was achieved by application of Fe chelates. Root-to-stem xylem transport of Cd and redistribution of Cd in leaves by phloem transport can be regulated in rice through the use of Fe chelates that influence Fe availability and Fe-related gene expression. Fe fertilization

  5. A physics-based fractional order model and state of energy estimation for lithium ion batteries. Part II: Parameter identification and state of energy estimation for LiFePO4 battery

    Science.gov (United States)

    Li, Xiaoyu; Pan, Ke; Fan, Guodong; Lu, Rengui; Zhu, Chunbo; Rizzoni, Giorgio; Canova, Marcello

    2017-11-01

    State of energy (SOE) is an important index for the electrochemical energy storage system in electric vehicles. In this paper, a robust state of energy estimation method in combination with a physical model parameter identification method is proposed to achieve accurate battery state estimation at different operating conditions and different aging stages. A physics-based fractional order model with variable solid-state diffusivity (FOM-VSSD) is used to characterize the dynamic performance of a LiFePO4/graphite battery. In order to update the model parameter automatically at different aging stages, a multi-step model parameter identification method based on the lexicographic optimization is especially designed for the electric vehicle operating conditions. As the battery available energy changes with different applied load current profiles, the relationship between the remaining energy loss and the state of charge, the average current as well as the average squared current is modeled. The SOE with different operating conditions and different aging stages are estimated based on an adaptive fractional order extended Kalman filter (AFEKF). Validation results show that the overall SOE estimation error is within ±5%. The proposed method is suitable for the electric vehicle online applications.

  6. Local structures and electronic band states of α-Fe2O3 polycrystalline particles included in the red-color overglazes and the transparent glazes of the Kakiemon-style porcelains by means of X-ray absorption spectra (i Estruturas locais e estados de banda eletrônica de partículas policristalinas de α-Fe2O3 inclusas em esmaltes vermelhos e transparentes de porcelanas do estilo Kakiemon por meio de espectros de absorção de raios X (II

    Directory of Open Access Journals (Sweden)

    M. Hidaka

    2009-09-01

    Full Text Available Kakiemon-style porcelain is mainly characterized by the porcelain body of white color or milky-white color and the elegant and bright patterns of the colored overglazes on its white body. The porcelains were first developed and completed by Kakiemon-kiln family in 1650-80's. The red-color overglazes and the transparent glazes of the present porcelain pieces, which were produced in the early 17th century to the middle 18th century, have been investigated by means of X-ray absorption spectrum using synchrotron radiation. The structure of α-Fe2O3 as red-color emission element is slightly deformed in the red-color overglazes by the other surrounding oxides (SiO2, Al2O3, K2O, Na2O, MgO, PbO, and/or the new complexes of (SiO2-Al2O3, systems constructed by the raw materials. The Fe ions in the transparent glazes are in the glass-state with the other oxides. However, the electronic valence, Fe3+, of Fe ions is the same with that of the α-Fe2O3 in the red-color overglazes. The lead oxides (PbO, Pb3O4 used in the Edo period to increase the brightness in the fritted red-color overglazes were perfectly decomposed, and Pb ions were in the glass-state of the porcelains.A porcelana do estilo Kakiemon e caracterizada principalmente pelo corpo de porcelana de cor branca ou branco-leitosa e os motivos elegantes e brilhantes dos esmaltes coloridos no seu corpo branco. As porcelanos foram primeiramente desenvolvidas e completadas em forno pela família Kakiemon em 1650-1680. Os esmaltes vermelhos e transparentes das peças de porcelana que foram produzidas no começo do século XVII até o meio do século XVIII foram analisadas em espectros de absorção de raios X com radiação síncrotron. A estrutura do α-Fe2O3 como elemento emissor de cor vermelha é levemente deformada nos esmaltes vermelhos por outros óxidos presentes (SiO2, Al2O3, K2O, Na2O, MgO, PbO, e/ou novos sistemas complexos de (SiO2-Al2O3, que fazem parte da matéria-prima. Os íons Fe nos

  7. Iron-based nanopowders containing α-Fe, Fe(3)C, and γ-Fe particles synthesised in microwave torch plasma and investigated with Mössbauer spectroscopy

    Czech Academy of Sciences Publication Activity Database

    David, Bohumil; Pizúrová, Naděžda; Schneeweiss, Oldřich; Kudrle, V.; Jašek, O.; Synek, P.

    2011-01-01

    Roč. 50, 8 PART 2 (2011), 08JF11/1-08JF1/5 ISSN 0021-4922 R&D Projects: GA ČR GA202/08/0178; GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : nanoparticles * microvawe plasma * gamma-Fe * gamma-Fe4N * Mossbauer spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.058, year: 2011

  8. Cementation of kerogen-rich marls by alkaline fluids released during weathering of thermally metamorphosed marly sediments. Part II: Organic matter evolution, magnetic susceptibility and metals (Ti, Cr, Fe) at the Khushaym Matruk natural analogue (Central Jordan)

    Energy Technology Data Exchange (ETDEWEB)

    Elie, M. [Univ Nancy 1, CNRS, F-54506 Vandoeuvre Les Nancy (France); Techer, I. [Univ Aix Marseille 3, CNRS, UMR 6635, CEREGE, F-30035 Nimes, (France); Trotignon, L. [CEN Cadarache, DTN SMTM LMTE, F-13108 St Paul Les Durance (France); Khoury, H.; Salameh, E. [Univ Jordan, Dept Geol, Amman 11942 (Jordan); Vandamme, D. [Univ Aix Marseille 3, CNRS, UMR 6635, CEREGE, F-13545 Aix En Provence (France); Boulvais, P.; Fourcade, S. [Univ Rennes 1, CNRS, UMR 6118, F-35042 Rennes (France)

    2007-07-15

    .05 m as revealed by the oxygen index and induced the generation of bitumen. The spatial correlation between the oxidation levels of organic matter and the metal contents (Fe, Ti and Cr) suggests that redox reactions were responsible for the immobilization of metals in the indurated bio-micrites. The intensity of these reactions is attributed to changes in the fluid flow regime within the sedimentary column. (authors)

  9. Santa Fe Linac Conference

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    The 1981 Linear Accelerator Conference, organized by Los Alamos National Laboratory, was held from 19-23 October in Santa Fe, New Mexico. The surroundings were superb and helped to ensure a successful meeting. There were more than two hundred and twenty participants, with good representation from Japan and Western Europe

  10. Santa Fe Accelerator Conference

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    The 10th USA National Particle Accelerator Conference was hosted this year by the Los Alamos National Laboratory in Santa Fe from 21-23 March. It was a resounding success in emphasizing the ferment of activity in the accelerator field. About 900 people registered and about 500 papers were presented in invited and contributed talks and poster sessions

  11. Thermodynamical properties of 56Fe

    International Nuclear Information System (INIS)

    Tavukcu, E.; Becker, J. A.; Bernstein, L. A.; Garrett, P. E.; Younes, W.; Guttormsen, M.; Rekstad, J.; Siem, S.; Mitchell, G. E.; Schiller, A.; Voinov, A.

    2003-01-01

    Average nuclear level densities close to the nuclear binding energy in 56Fe and 57Fe are extracted from primary γ-ray spectra. A step structure is observed in the level density for both isotopes, and is interpreted as breaking of Cooper pairs. Thermal properties of 56Fe are studied within the statistical canonical ensemble. The experimental heat capacity in 56Fe is compared with the theoretical heat capacity calculated within the shell model Monte Carlo approach

  12. The combined effects of Fe and H2 on the nitridation of silicon

    Science.gov (United States)

    Shaw, N. J.

    1982-01-01

    In view of the support offered by previous work for the suggestion that Fe may affect alpha-Si3N4 formation and microstructural development, a two-part study was conducted to differentiate the effects of H2 and Fe in, first, the nitridation of pure and of Fe-containing powder in N2 and N2-4% H2, and then the nitridation of (1 1 1) Si single crystal wafers with and without Fe powder on the surface. The degree of nitridation is most strongly affected by H2 at 1200 C, but by Fe at 1375 C, where Fe-containing samples in either atmosphere were almost completely nitrided. While neither H2 nor Fe alone changed the ratio of alpha-Si3N4 to beta-Si3N4, the combination of H2 and Fe increased it at both temperatures.

  13. Diffusion of Nb in Fe and in some Fe alloys

    International Nuclear Information System (INIS)

    Kurokawa, S.; Ruzzante, J.E.; Hey, A.M.; Dyment, F.

    1981-01-01

    Diffusion data of microalloying elements such as Nb, V, Ti, are required when analysing the transformation and recrystallization behaviour of HSLA steels in order to optimize grain refinement and precipitation hardening. The diffusion behaviour of Nb in pure Fe, Fe 1.5 Mn, Fe 0.6 Si and Fe 1.5 Mn 0.6 Si has been measured between 1080 and 1200 0 C. Results indicate that Si increases Nb diffusivity while Mn decreases it. The sequence of diffusion coeficients values is: D sup(Nb) sub(Fe 1.5 Mn) [pt

  14. Thermodynamical Properties of 56Fe

    International Nuclear Information System (INIS)

    Tavukcu, E.; Becker, J.A.; Bernstein, L.A.; Garrett, P.E.; Guttormsen, M.; Mitchell, G.E.; Rekstad, J.; Schiller, A.; Siem, S.; Voinov, A.; Younes, W.

    2002-01-01

    Average nuclear level densities close to the nuclear binding energy in 56 Fe and 57 Fe are extracted from primary γ-ray spectra. Thermal properties of 56 Fe are studied within the statistical canonical ensemble. The experimental heat capacity is compared with the theoretical heat capacity calculated within the shell model Monte Carlo approach

  15. FE Prediction of Hysteretic Component of Rubber Friction

    OpenAIRE

    L. Pálfi; T. Goda; K. Váradi; E. Garbayo; J. M. Bielsa; M. A. Jiménez

    2012-01-01

    The hysteretic part of the friction coefficient for rubber sliding on an ideal rigid, rough surface has been investigated by FE technique. The FE models were created by using two different FE softwares, ABAQUS and MSC.MARC. The surface roughness has been considered by using two different sine waves having a wavelength of 100 μm and 11.11 μm, as well as their superposition. Parameters of the viscoelastic material models of the rubber were gained, firstly from a fit to the measured storage modu...

  16. MFM study of NdFeB and NdFeB/Fe/NdFeB thin films

    International Nuclear Information System (INIS)

    Gouteff, P.C.; Folks, L.; Street, R.

    1998-01-01

    Domain structures of NdFeB thin films, ranging in thickness between 1500 and 29 nm, have been studied qualitatively by magnetic force microscopy (MFM). Samples were prepared using a range of sputtering conditions resulting in differences in properties such as texture, coercivity and magnetic saturation. MFM images of all the films showed extensive interaction domain structures, similar to those observed in nanocrystalline bulk NdFeB. An exchange-coupled NdFeB/Fe/NdFeB trilayer with layer thicknesses 18 nm/15 nm/18 nm, respectively, was also examined using MFM. (orig.)

  17. Negative cooperativity in the nitrogenase Fe protein electron delivery cycle

    Energy Technology Data Exchange (ETDEWEB)

    Danyal, Karamatullah; Shaw, Sudipta; Page, Taylor R.; Duval, Simon; Horitani, Masaki; Marts, Amy R.; Lukoyanov, Dmitriy; Dean, Dennis R.; Raugei, Simone; Hoffman, Brian M.; Seefeldt, Lance C.; Antony, Edwin

    2016-10-04

    Mo-dependent nitrogenase catalyzes the biological reduction of atmospheric dinitrogen (N2) to two ammonia (NH3) molecules, through the action of two component proteins, the MoFe protein and the Fe protein. The catalytic MoFe protein is a symmetric dimer of αβ units, each of which contains one active site FeMo-co (FeMo-co; [7Fe-9S-Mo-C-homocitrate]) and an electron-carrier P cluster. Each half of the nitrogenase ternary complex, in which one Fe protein with two bound ATP molecules has bound to each MoFe protein αβ unit, undergoes an electron transfer (ET) cycle with ET from a Fe protein [4Fe-4S] cluster into its αβ unit followed by the hydrolysis of the two ATP to two ADP and two Pi. The prevailing model holds that each αβ unit of the MoFe protein functions independently. We now report that the ET cycle exhibits negative cooperativity, with ET and ATP hydrolysis in one half of the ternary nitrogenase complex suppressing these processes in the other half. The observed ET, ATP hydrolysis, and Pi release behavior is captured in a global fit to a two-branch negative-cooperativity kinetic model. A possible mechanism for communication between the two halves of MoFe protein is suggested by normal mode analysis showing correlated and anti-correlated motions between the two nitrogenase αβ halves. EPR spectra furthermore show small differences between those of resting-state and singly-reduced MoFe protein that can be attributed to an intra-complex allosteric perturbation of the resting-state FeMo-co in one αβ unit by reduction of FeMo-co in the other. This work is supported as a part of the Biological and Electron Transfer and Catalysis (EFRC) program, an Energy Frontiers Research Center funded by the US Department of Energy (DOE), Office of Science (DE-SC0012518) to LCS, by National Institutes of Health (NIH) grants HL 63203 and GM 111097to BMH, and R15GM110671 to EA, and by the Division of Chemical Sciences, Geosciences, and Bio-Sciences, DOE to SR. The protein

  18. Effect of Chlorine precursor in surface and cataytic properties of Fe/TiO2 Catalysts

    OpenAIRE

    López, Tessi; Pecchi, Gina; Moreno, Abel; García Fierro, José Luis; Gómez, R.; Reyes, P.

    2002-01-01

    Titania-supported iron (1wt%) catalysts were prepared by the sol-gel method using different gelation pH (3 and 9), metal precursors (FeCl2 and FeCl3) and calcination temperatures (873 and 1073K). Characterization data of calcined catalysts revealed that in all samples the dominant iron species is Fe3+ and the crystalline phase of the TiO2 substrate depends on the gelation pH and the metal precursor used. It was found that in the Fe/TiO2 ex-FeCl3 samples an important part of the iron ions beca...

  19. Investigation of the Lattice Dynamics of α-Fe and Fe3al by Neutron Inelastic Scattering. RCN Report

    International Nuclear Information System (INIS)

    Dijk, C. van

    1970-09-01

    This report describes the study of the lattice dynamics of α-Fe and ordered Fe 3 Al by means of inelastic neutron scattering using a triple-axis crystal spectrometer. Detailed phonon dispersion relations both for α-Fe and Fe 3 Al are presented. A Born-von Kármán model is used to analyse the experimental data. For α-Fe interactions out to fifth neighbours are included, while for Fe 3 Al interactions out to third neighbours are taken into account. The obtained force constants are used for the calculation of the frequency distribution functions, from which related thermodynamic quantities and Debye temperatures are deduced. The analysis of the lattice dynamics of the more complex system of Fe 3 Al was facilitated by a group-theoretical treatment. The blocks for the different irreducible representations of the block-diagonalised dynamical matrix together with their symmetry adapted eigenvectors are presented. Reduced inelastic structure factors are given for normal modes in the symmetry directions. From the force constants for ordered FegAl values for those of partly disordered (CsCl-type) Fe 3 Al were estimated. The latter were used for the calculation of phonon dispersion relations, frequency distribution functions and some other related properties. (author)

  20. 44 CFR Appendix B to Part 18 - Disclosure Form To Report Lobbying

    Science.gov (United States)

    2010-10-01

    ... Lobbying B Appendix B to Part 18 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY GENERAL NEW RESTRICTIONS ON LOBBYING Pt. 18, App. B Appendix B to Part 18—Disclosure Form To Report Lobbying EC02FE91.075 EC02FE91.076 EC02FE91.077 ...

  1. On the existence of the Fe sub 2 Nb sub 3 phase in the Fe-Nb system

    Energy Technology Data Exchange (ETDEWEB)

    Zelaya Bejarano, J.M. (Centro de Tecnologia, Universidade Estadual de Campinas, SP (Brazil)); Gama, S.; Ribeiro, C.A. (Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, SP (Brazil)); Effenberg, G. (Max-Planck-Inst. fuer Metallforschung, Inst. fuer Werkstoffwissenschaften, PML, Stuttgart (Germany)); Santos, C.

    1991-08-01

    The niobium-rich part of the Fe-Nb system has been investigated using metallography, electron microprobe, differential thermal analysis and the examination of diffusion couples. The phase relations are partially presented in the niobium-rich composition range of the phase diagram. It is concluded that the Fe{sub 2}Nb{sub 3} phase is not an equilibrium phase of the system, but appears metastable during slow cooling processes. (orig.).

  2. Bottom and top AF/FM interfaces of NiFe/FeMn/NiFe trilayers

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, V.P. [Universidade Federal Rural do Rio de Janeiro, Instituto Multidisciplinar, Rua Professor Paris, s/n Centro, 26221-150 Nova Iguacu, RJ (Brazil)], E-mail: valberto@cbpf.br; Passamani, E.C. [Universidade Federal do Espirito Santo, Depto. Fisica, Avenida Fernando Ferrari, 514 Goiabeiras, 29075-910 Vitoria, ES (Brazil); Alvarenga, A.D. [Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial, Avenida Nossa Senhora das Gracas, 50 Duque de Caxias, 25250-020 Rio de Janeiro, RJ (Brazil); Biondo, A. [Universidade Federal do Espirito Santo, Depto. Fisica, Avenida Fernando Ferrari, 514 Goiabeiras, 29075-910 Vitoria, ES (Brazil); Pelegrini, F. [Universidade Federal de Goias, Instituto de Fisica, Campus Samambaia, 74001-970 Goiania, GO (Brazil); Saitovitch, E. Baggio [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud, 150 Urca, 22290-180 Rio de Janeiro, RJ (Brazil)

    2008-01-30

    X-ray reflectivity analyses were performed in the Si/WTi (7 nm)/NiFe (30 nm)/FeMn (13 nm)/NiFe (10 nm)/WTi (7 nm) exchange-biased system prepared by magnetron sputtering under three different argon working pressures. Layer-by-layer analyses were realized in order to obtain the interfacial roughness parameters quantitatively. For a fixed argon pressure, the root-mean-square roughness (including the atomic grading) of the upper (FeMn/NiFe) interface are greater than that for the lower one in all studied samples. Argon working pressure also has severe influence over the NiFe/FeMn interfaces, being more pronounced at the upper interfaces.

  3. How oxygen attacks [FeFe] hydrogenases from photosynthetic organisms

    Science.gov (United States)

    Stripp, Sven T.; Goldet, Gabrielle; Brandmayr, Caterina; Sanganas, Oliver; Vincent, Kylie A.; Haumann, Michael; Armstrong, Fraser A.; Happe, Thomas

    2009-01-01

    Green algae such as Chlamydomonas reinhardtii synthesize an [FeFe] hydrogenase that is highly active in hydrogen evolution. However, the extreme sensitivity of [FeFe] hydrogenases to oxygen presents a major challenge for exploiting these organisms to achieve sustainable photosynthetic hydrogen production. In this study, the mechanism of oxygen inactivation of the [FeFe] hydrogenase CrHydA1 from C. reinhardtii has been investigated. X-ray absorption spectroscopy shows that reaction with oxygen results in destruction of the [4Fe-4S] domain of the active site H-cluster while leaving the di-iron domain (2FeH) essentially intact. By protein film electrochemistry we were able to determine the order of events leading up to this destruction. Carbon monoxide, a competitive inhibitor of CrHydA1 which binds to an Fe atom of the 2FeH domain and is otherwise not known to attack FeS clusters in proteins, reacts nearly two orders of magnitude faster than oxygen and protects the enzyme against oxygen damage. These results therefore show that destruction of the [4Fe-4S] cluster is initiated by binding and reduction of oxygen at the di-iron domain—a key step that is blocked by carbon monoxide. The relatively slow attack by oxygen compared to carbon monoxide suggests that a very high level of discrimination can be achieved by subtle factors such as electronic effects (specific orbital overlap requirements) and steric constraints at the active site. PMID:19805068

  4. Brassinosteroids are involved in Fe homeostasis in rice (Oryza sativa L.).

    Science.gov (United States)

    Wang, Baolan; Li, Gen; Zhang, Wen-Hao

    2015-05-01

    Brassinosteroids (BRs) are steroid hormones that modulate numerous physiological processes in plants. However, few studies have focused on the involvement of BRs in sensing and responding to the stress of mineral nutrient deficiency. In the present study, we evaluated the roles of BRs in the response of rice (Oryza sativa) to iron (Fe) deficiency during Fe uptake, transport, and translocation. Exogenous application of 24-epibrassinolide (EBR) to wild-type (WT) plants exaggerated leaf symptoms of Fe deficiency and suppressed growth. EBR increased and decreased Fe concentrations in roots and shoots, respectively, under both Fe-deficient and Fe-sufficient conditions. Transcripts involved in Fe homeostasis, including OsIRT1, OsYSL15, OsYSL2, OsNAS1, and OsNAS2, were enhanced by EBR under Fe-deficient conditions. EBR depressed expression of OsNAS1, OsNAS2, and OsYSL2 in shoots, and inhibited Fe transport and translocation via the phloem. Rice mutant d2-1, which is defective in BR biosynthesis, was more tolerant to Fe deficiency than the WT, and accumulated greater amounts of Fe in roots than the WT under Fe-sufficient conditions. A greater upregulation of OsIRT1, OsYSL15, OsYSL2, OsNAS1, and OsNAS2 in the d2-1 mutant compared to the WT was found under Fe-sufficient conditions, while expression of these genes in the d2-1 mutant was lower than in the WT under Fe-deficient conditions. The greater tolerance of the d2-1 mutant could be partly mitigated by exogenous application of EBR. These novel findings highlight the important role of BR in mediating the response of strategy II plants to Fe deficiency by regulating Fe uptake and translocation in rice. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  5. Fe de Erratas

    Directory of Open Access Journals (Sweden)

    Perspectiva Geográfica

    2014-01-01

    Full Text Available La Magíster Sonia Jimena Murillo Munar, autora del artículo titulado “Transporte urbano sostenible: medidas desde la administración y transporte público como alternativa en Bogotá”, publicado en el Volumen No. 13 correspondiente al año 2008, solicita la inclusión de la siguiente FE DE ERRATAS con la enmienda de un error de exclusiva responsabilidad del Equipo Editorial de la Revista.

  6. Size, density and composition of cell-mineral aggregates formed during anoxygenic phototrophic Fe(II) oxidation: Impact on modern and ancient environments

    DEFF Research Database (Denmark)

    Posth, Nicole R.; Huelin, Sonia; Konhauser, Kurt O.

    2010-01-01

    Cell-Fe(III) mineral aggregates produced by anoxygenic Fe(II)-oxidizing photoautotrophic microorganisms (photoferrotrophs) may be influential in the modern Fe cycle and were likely an integral part of ancient biogeochemical cycles on early Earth. While studies have focused on the environmental...... iron phase depended on the composition of the medium: goethite formed in cultures grown by oxidation of dissolved Fe(II) medium in the presence of low phosphate concentrations, while poorly ordered ferrihydrite (or Fe(III) phosphates) formed when amorphous Fe(II) minerals (Fe(II)-phosphates) and high...

  7. Determination of localized Fe2+/Fe3+ ratios in inks of historic documents by means of μ-XANES

    International Nuclear Information System (INIS)

    Proost, K.; Janssens, K.; Wagner, B.; Bulska, E.; Schreiner, M.

    2004-01-01

    An important part of the European cultural heritage is composed of hand-written documents. Many of these documents were drawn up with iron-gall ink. This type of ink present a serious conservation problem, as it slowly oxidizes ('burns') the paper it is written on, thereby gradually disintegrating the historic document. Acid hydrolysis of the cellulose and/or the oxidation of organic compounds promoted by radical intermediates that are formed due to the presence of Fe 2+ ions are considered to be the cause of the disintegration. μ-XANES measurements were performed with a lateral resolution of 30-50 μm in order to determine the local Fe 2+ /Fe 3+ ratio in 19th C. documents from the Austrian National Archives and fragments of 16th C documents from the Polish National Library. In the 19th C documents, no significant amount of Fe 2+ was detected. On the other hand, in the 16th C fragments, significant amounts of Fe 2+ and appreciable differences in distribution of Fe 2+ and Fe 3+ within individual letters/ink stains were observed

  8. Magnetic structure of molecular magnet Fe[Fe(CN) 6

    Indian Academy of Sciences (India)

    We have studied the magnetic structure of Fe[Fe(CN)6]·4H2O, prepared by precipitation method, using neutron diffraction technique. Temperature dependent DC magnetization study down to 4.2 K shows that the compound undergoes from a high temperature disordered (paramagnetic) to an ordered magnetic phase ...

  9. Fe65-PTB2 Dimerization Mimics Fe65-APP Interaction

    Directory of Open Access Journals (Sweden)

    Lukas P. Feilen

    2017-05-01

    Full Text Available Physiological function and pathology of the Alzheimer’s disease causing amyloid precursor protein (APP are correlated with its cytosolic adaptor Fe65 encompassing a WW and two phosphotyrosine-binding domains (PTBs. The C-terminal Fe65-PTB2 binds a large portion of the APP intracellular domain (AICD including the GYENPTY internalization sequence fingerprint. AICD binding to Fe65-PTB2 opens an intra-molecular interaction causing a structural change and altering Fe65 activity. Here we show that in the absence of the AICD, Fe65-PTB2 forms a homodimer in solution and determine its crystal structure at 2.6 Å resolution. Dimerization involves the unwinding of a C-terminal α-helix that mimics binding of the AICD internalization sequence, thus shielding the hydrophobic binding pocket. Specific dimer formation is validated by nuclear magnetic resonance (NMR techniques and cell-based analyses reveal that Fe65-PTB2 together with the WW domain are necessary and sufficient for dimerization. Together, our data demonstrate that Fe65 dimerizes via its APP interaction site, suggesting that besides intra- also intermolecular interactions between Fe65 molecules contribute to homeostatic regulation of APP mediated signaling.

  10. Tunnel Magneto Resistance of Fe/Insulator/Fe

    Science.gov (United States)

    Aryee, Dennis; Seifu, Dereje

    Tri-layer thin films of Fe/Insulator/Fe were synthesized using magnetron DC/ RF sputtering with MgO insulator and Bi2Te3 topological insulators as middle buffer layer. The multi-layered samples thus produced were studied using in-house built magneto-optic Kerr effect (MOKE) instrument, vibrating sample magnetometer (VSM), torque magnetometer (TMM), AFM, MFM, and magneto-resistance (MR). This system, that is Fe/Insulator/Fe on MgO(100) substrate, is a well-known tunnel magneto resistance (TMR) structure often used in magnetic tunnel junction (MTJ) devices. TMR effect is a method by which MTJs are used in developing magneto-resistive random access memory (MRAM), magnetic sensors, and novel logic devices. The main purpose behind this research is to measure the magnetic anisotropy of Fe/Insulator /Fe structure and correlate it to magneto-resistance. In this presentation, we will present results from MOKE, VSM, TMM, AFM, MFM, and MR studies of Fe/Insulator/Fe on MgO(100). We would like to acknowledge support by NSF-MRI-DMR-1337339.

  11. Magnetic properties of Fe1-xMnx/Fe nanocomposites

    DEFF Research Database (Denmark)

    Anhøj, Thomas Aarøe; Jacobsen, Claus Schelde; Mørup, Steen

    2004-01-01

    We have prepared nanocomposites of mixtures of ferromagnetic alpha-Fe and antiferromagnetic gamma-Fe50Mn50 nanoparticles, and studied their magnetic and structural properties by magnetization measurements, Mössbauer spectroscopy, and x-ray diffraction. A sample consisting of a 1:1 mixture...

  12. THE CONNECTIONS BETWEEN THE UV AND OPTICAL Fe ii EMISSION LINES IN TYPE 1 AGNs

    Energy Technology Data Exchange (ETDEWEB)

    Kovacević-Dojcinović, Jelena; Popović, Luka Č., E-mail: jkovacevic@aob.bg.ac.rs, E-mail: lpopovic@aob.bg.ac.rs [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)

    2015-12-15

    We investigate the spectral properties of the UV (λλ2650–3050 Å) and optical (λλ4000–5500 Å) Fe ii emission features in a sample of 293 Type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey database. We explore different correlations between their emission line properties, as well as the correlations with other emission lines from the spectral range. We find several interesting correlations and outline the most interesting results as follows. (i) There is a kinematical connection between the UV and optical Fe ii lines, indicating that the UV and optical Fe ii lines originate from the outer part of the broad line region, the so-called intermediate line region. (ii) The unexplained anticorrelations of the optical Fe ii equivalent width (EW Fe ii{sub opt}) versus EW [O iii] 5007 Å and EW Fe ii{sub opt} versus FWHM Hβ have not been detected for the UV Fe ii lines. (iii) The significant averaged redshift in the UV Fe ii lines, which is not present in optical Fe ii, indicates an inflow in the UV Fe ii emitting clouds, and probably their asymmetric distribution. (iv) Also, we confirm the anticorrelation between the intensity ratio of the optical and UV Fe ii lines and the FWHM of Hβ, and we find the anticorrelations of this ratio with the widths of Mg ii 2800 Å, optical Fe ii, and UV Fe ii. This indicates a very important role for the column density and microturbulence in the emitting gas. We discuss the starburst activity in high-density regions of young AGNs as a possible explanation of the detected optical Fe ii correlations and intensity line ratios of the UV and optical Fe ii lines.

  13. Dolo y mala fe

    Directory of Open Access Journals (Sweden)

    Carlos Arturo Gómez Pavajeau

    2010-12-01

    Full Text Available Se ha dicho por grandes penalistas que las tesis en nuestra disciplina son una eterna vuelta al pasado. Empero, debe constatarse, que ello se ha dicho en un sentido de lo clásico: una vuelta a lo que resulta digno de admirar en cualquier época, toda vez que las experiencias históricas negativas nos previenen de repetir el pasado, razón fundamental por la cual debemos conocerlo. En este escrito pretendemos mostrar cómo algunas tendencias actuales nos indican que épocas nefastas ya superadas pueden repetirse, lo cual particularmente sucede tanto con la noción de dolo como con la de mala fe, concepto que de imponerse destruiría, a la manera como se derrumba un castillo de naipes, el sólido edificio dogmático construido por el Derecho penal liberal.

  14. Measurement of 54Fe(n,2n)53Fe cross section near threshold

    International Nuclear Information System (INIS)

    Smither, R.K.; Greenwood, L.R.

    1984-01-01

    A series of experiments were performed at the Princeton Plasma Physics Laboratory to measure the cross section of the 54 Fe(n,2n) 53 Fe reaction near threshold. Measurements were made at 6 different neutron energies and cover the 1 MeV energy range from threshold (13.64 MeV) to 14.64 MeV. The 54 Fe(n,2n) cross section was measured relative to the 27 Al(n,p) 27 Mg cross section to an accuracy of a few percent. These accurate cross-section measurements will be useful in calculating damage caused by 14 MeV D-T plasma neutrons in Fe and calculating the production of the long-lived 53 Mn nuclei that account for much of the buildup of long-lived radioactivity in steel structures and other ferrous materials used in the construction of fusion reactors. They will also play an important part in a new method for measuring the plasma ion temperature of a D-T plasma

  15. Exchange bias variations of the seed and top NiFe layers in NiFe/FeMn/NiFe trilayer as a function of seed layer thickness

    International Nuclear Information System (INIS)

    Sankaranarayanan, V.K.; Yoon, S.M.; Kim, C.G.; Kim, C.O.

    2005-01-01

    Development of exchange bias at the seed and top NiFe layers in the NiFe (t nm)/FeMn(10 nm)/NiFe(5 nm) trilayer structure is investigated as a function of seed layer thickness, in the range of 2-20 nm. The seed NiFe layer shows maximum exchange bias at 4 nm seed layer thickness. The bias shows inverse thickness dependence with increasing thickness. The top NiFe layer on the other hand shows only half the bias of the seed layer which is retained even after the sharp fall in seed layer bias. The much smaller bias for the top NiFe layer is related to the difference in crystalline texture and spin orientations at the top FeMn/NiFe interface, in comparison to the bottom NiFe/FeMn interface which grows on a saturated NiFe layer with (1 1 1) orientation

  16. Fe-C-S systematics in Bengal Fan sediments

    Science.gov (United States)

    Volvoikar, S. P.; Mazumdar, A.; Goswami, H.; Pujari, S.; Peketi, A.

    2017-12-01

    Global biogeochemical cycles of iron, carbon and sulfur (Fe-C-S) are interrelated. Sulfate reduction in marine sediments is the major factor controlling the cycling and burial of carbon, sulfur and iron. Organoclastic sulfate reduction and anaerobic oxidation of methane (AOM) are the two main processes responsible for sulfate reduction in marine sediments. The amount and reactivity of organic matter, iron minerals and concentrations of dissolved sulfide in pore water control the burial of iron sulfide and organic bound sulfur in marine sediments. Here we investigate the sulfidization process in a sediment core from the western part of upper Bay of Bengal fan characterized by efficient burial of organic matter with siliclastic load. A 30 m long sediment core (MD 161/29, Lat. 170 18.04' N, Long. 870 22.56' E, water depth: 2434m) was collected onboard Marion Dufresne (May, 2007) and studied for Fe-S speciation and organic matter characterization. Buffered dithionite extractable iron (FeD) varies from 0.71 to 1.43 wt % (Avg. 0.79 wt %). FeD represents Fe oxides and oxyhydroxides mainly, ferrihydrite, lepidocrocite, goethite and hematite. Acid volatile sulfur (AVS) varies from 0.0015 to 0.63 wt % (avg: 0.058 wt %), while chromium reducible sulfur (CRS) varies from 0.00047 to 0.29 wt % (avg. 0.054 wt %). Based on the vertical distribution patterns of FeD, AVS and CRS, the core is divided into three zones, the lower (3000 to 1833 cm), middle (1833 to 398 cm) and upper (398 cm to surface) zones. FeD shows higher concentration in the lower zone. FeTR (FeOx + FeD + FeCRS + FeAVS) also exhibit higher concentration in this zone, suggesting higher availability of reactive iron for iron sulfide precipitation. AVS, elemental sulfur, spikes of CRS and gradual enrichment of δ34SAVS and δ34SCRS with sharp peaks in-between is noted in the lower zone. The gradual enrichment of δ34SAVS and δ34SCRS is the outcome of late diagenetic pyritization with higher availability of sulfide

  17. Preparation and Mechanical Properties of TiC-Fe Cermets and TiC-Fe/Fe Bilayer Composites

    Science.gov (United States)

    Zheng, Yong; Zhou, Yang; Li, Runfeng; Wang, Jiaqi; Chen, Lulu; Li, Shibo

    2017-10-01

    TiC-Fe cermets and TiC-Fe/Fe bilayer composites consisting of a pure Fe layer and a TiC-Fe cermets layer were fabricated by hot-pressing sintering. The pure Fe layer contributes to the toughness of composites, and the TiC-Fe cermets layer endows the composites with an improved tensile strength and hardness. The effect of TiC contents (30-60 vol.%) on the mechanical properties of TiC-Fe cermets and TiC-Fe/Fe bilayer composites was investigated. Among the TiC-Fe cermets, the 40 vol.% TiC-Fe cermets possessed the highest tensile strength of 581 MPa and Vickers hardness of 5.1 GPa. The maximum fracture toughness of 17.0 MPa m1/2 was achieved for the TiC-Fe cermets with 30 vol.% TiC. For the TiC-Fe/Fe bilayer composites, the 40 vol.% TiC-Fe/Fe bilayer composite owns the maximum tensile strength of 588 MPa, which is higher than that of 40 vol.% TiC-Fe cermets. In addition, the 33.5% increment of tensile strength of 30 vol.% TiC-Fe/Fe bilayer composite comparing with the 30 vol.% TiC-Fe cermets, which is attributed to the 30 vol.% TiC-Fe/Fe bilayer composite exhibited the largest interlaminar shear strength of 335 MPa. The bilayer composites are expected to be used as wear resistance components in some heavy wear conditions.

  18. Fe (III) speciation in the high nutrient, low chlorophyll Pacific region of the Southern Ocean

    NARCIS (Netherlands)

    Nolting, R.F.; Gerringa, L.J.A.; Swagerman, M.J.W.; Timmermans, K.R.; Baar, H.J.W. de

    1998-01-01

    Fe speciation was measured with competitive ligand equilibration adsorptive cathodic stripping voltammetry in the Pacific part of the Southern Ocean between 58° and 68°30′S along the 90°W meridian. The conditional stability constant (K′ with respect to [Fe3+]) was between 10^20.6 and 10^21.6 when

  19. Aluminium base amorphous and crystalline alloys with Fe impurity

    International Nuclear Information System (INIS)

    Sitek, J.; Degmova, J.

    2006-01-01

    Aluminium base alloys show remarkable mechanical properties, however their low thermal stability still limits the technological applications. Further improvement of mechanical properties can be reached by partial crystallization of amorphous alloys, which gives rise to nanostructured composites. Our work was focused on aluminium based alloys with Fe, Nb and V additions. Samples of nominal composition Al 90 Fe 7 Nb 3 and Al 94 Fe 2 V 4 were studied in amorphous state and after annealing up to 873 K. From Moessbauer spectra taken on the samples in amorphous state the value of f-factor was determined as well as corresponding Debye temperatures were calculated. Annealing at higher temperatures induced nano and microcrystalline crystallization. Moessbauer spectra of samples annealed up to 573 K are fitted only by distribution of quadrupole doublets corresponding to the amorphous state. An increase of annealing temperature leads to the structural transformation, which consists in growth of nanometer sized aluminium nuclei. This is partly reflected in Moessbauer parameters. After annealing at 673 K intermetallic phase Al 3 Fe and other Al-Fe phases are created. In this case Moessbauer spectra are fitted by quadrupole doublets. During annealing up to 873 K large grains of Fe-Al phases are created. (authors)

  20. Mössbauer study of treated Nd2Fe14B

    Directory of Open Access Journals (Sweden)

    Budzyński Mieczysław

    2015-03-01

    Full Text Available The Nd2Fe14B cylindrical magnets were treated with water solutions of alkali, acid, and salt. Mössbauer spectroscopy was applied to study the composition and properties of the surface material of the treated magnets. It is shown that the main phase of the permanent Nd2Fe14B magnet partly decomposes. The released α-Nd at the grain boundaries interacts with water and forms neodymium hydroxide matrix, and the released Fe diffuses into it. The presence of Fe-Nd(OH3 is reflected in the paramagnet doublet in the Mössbauer spectra of treated neodymium magnets.

  1. Forest resources of the Santa Fe National Forest

    Science.gov (United States)

    Dana Lambert

    2004-01-01

    The Interior West Forest Inventory and Analysis (IWFIA) program of the USDA Forest Service, Rocky Mountain Research Station, as part of its national Forest Inventory and Analysis (FIA) duties, conducted forest resource inventories of the Southwestern Region (Region 3) National Forests. This report presents highlights of the Santa Fe National Forest 1998...

  2. Schwertmannite stability in anoxic Fe(II)-rich aqueous solution

    Science.gov (United States)

    Paikaray, Susanta; Schröder, Christian; Peiffer, Stefan

    2017-11-01

    Schwertmannite (SHM) is a powerful scavenger for As(III) leading to As(III)-enriched precipitates around acid mine drainage environments that may become exposed to aqueous Fe(II). In this study we have investigated the stability of pure SHM and SHM containing 0.92 wt% As(III) under Fe(II)aq-rich (0.4-1.0 mM) anoxic conditions using XRD, SEM, Mössbauer and FTIR spectroscopic techniques. Schwertmannite transformation proceeded through an alkalinity-driven pathway releasing sulfate and a Fe(II)-catalyzed pathway that generated lepidocrocite and goethite at pH 6 and 6.9 in the presence of 1 mM Fe(II)aq. Lepidocrocite was found to be needle shaped if the SHM contained As(III) and platy for pure SHM. Goethite had a poor degree of crystallinity in As(III) containing SHM. Pre-adsorption of As(III) inhibited the extent of SHM transformation. Fe(II) sorption onto SHM was pH dependent and reflected a sorption edge with complete consumption at pH 6.9, while only ∼20% were adsorbed at pH 5. Surface coverage with Fe(II) appears to be the key parameter controlling extent and products of the transformation process. As(III) concentrations in solution are controlled by two mechanisms: (1) exchange of As(III) for sulfate upon alkalinity-driven transformation of schwertmannite and (2) re-adsorption to new phases formed upon Fe(II)-catalyzed transformation. The adsorbed As(III) has inhibited the extent of transformation and was partly released with the maximum release at pH 5 (0.5%) in the absence of Fe(II)aq.

  3. Phase diagram for Zr-Fe(0-66,6 at.%Fe)

    International Nuclear Information System (INIS)

    Malakhova, T.O.; Kobylkin, A.N.

    1982-01-01

    The Zr-Fe alloy system is investigated by the methods of X-ray diffraction and microstructure analyses. The existence of Zr 3 Fe compound is confirmed which is resulted from a peritectic reaction β+Zr 2 Fe reversible Zr 3 Fe; the formation temperature (approximately 885 deg C) is determined for Zr 3 Fe. It is found that Zr 2 Fe compound (tetragonal structure, a=6.384 A, c=5.598 A, c/a=0.877) decomposes according to an eutectoid reaction Zr 2 Fe reversible Zr 3 Fe+ZrFe 3 at 775 deg C. Using differential thermal analysis α reversible β transformation temperatures are determined; temperatures of eutectic L reversible β+Zr 2 Fe and peritectic L+ZrFe 2 reversible Zr 2 Fe equilibria are found to be 928 and 974 deg C respectively. The Zr-Fe (0-66.6 at.%Fe) phase diagram is constructed [ru

  4. Mechanochemically synthesized Fe{sub 3}Al-Al{sub 2}O{sub 3} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Khodaei, M. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Enayati, M.H. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)], E-mail: ena78@cc.iut.ac.ir; Karimzadeh, F. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2009-01-07

    Fe{sub 3}Al-Al{sub 2}O{sub 3} nanocomposite powder was successfully synthesized by mechanochemical route starting from Fe{sub 2}O{sub 3} and Al powder mixture. The resulting nanocomposite powder was consolidated at 1400 deg. C for 1 h. The phase transformation and microstructural characterization during mechanochemical reaction and sintering were investigated by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results showed that during ball milling the Fe{sub 2}O{sub 3}-Al combustion reaction directly produces the Fe{sub 3}Al-Al{sub 2}O{sub 3} nanocomposite. The consolidated Fe{sub 3}Al-Al{sub 2}O{sub 3} part had an ultrafine uniform structure without 'core-rim' feature consisting of an interconnected network of Fe{sub 3}Al and Al{sub 2}O{sub 3} phases.

  5. Effectiveness of FeEDDHA, FeEDDHMA, and FeHBED in Preventing Iron-Deficiency Chlorosis in Soybean

    NARCIS (Netherlands)

    Bin, Levi M.; Weng, Liping; Bugter, Marcel H.J.

    2016-01-01

    The performance of FeHBED in preventing Fe deficiency chlorosis in soybean (Glycine max (L.) Merr.) in comparison to FeEDDHA and FeEDDHMA was studied, as well as the importance of the ortho-ortho and ortho-para/rest isomers in defining the performance. To this end, chlorophyll production (SPAD),

  6. Study of Nd-Fe-B alloys with nonstoichiometric Nd content in optimal magnetic state

    Directory of Open Access Journals (Sweden)

    Ćosović V.

    2009-01-01

    Full Text Available Characterization of two rapid-quenched Nd-Fe-B alloys with nonstoichiometric Nd content in the optimized magnetic state was carried out using the X-ray diffractometry (XRD, 57Fe Mössbauer spectroscopic phase analysis (MS, electron microscopy (TEM, high resolution TEM (HREM and Superconducting Quantum Interference Device (SQUID magnetometer. The experimental results demonstrate the fundamental difference in the structure and magnetic properties of the two investigated alloys in the optimized magnetic state. The Nd-Fe-B alloy with the reduced Nd content (Nd4.5Fe77B18.5 was found to have the nanocomposite structure of Fe3B/Nd2Fe14B and partly α-Fe/Nd2Fe14B, with mean grain size below 30 nm. On the other side, the overstoichiometric Nd14Fe79B7 alloy has almost a monophase structure with the dominant content of the hard magnetic phase Nd2Fe14B (up to 95 wt. % and a mean crystallite size about 60 nm, as determined by XRD and TEM analysis. The results of magnetic measurements on SQUID magnetometer also suggest the nanocomposite structure of the Nd-low alloy and nanocrystalline decoupled structure of the Nd-rich alloy after the optimal heat treatment.

  7. Effect of Fe-Content on the Mechanical Properties of Recycled Al Alloys during Hot Compression

    Directory of Open Access Journals (Sweden)

    Hongzhou Lu

    2017-07-01

    Full Text Available It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two Fe-containing Al alloys were carried out at elevated temperatures within a wide strain rate range from 0.01 s−1 to 10 s−1. The effect of Fe content on the peak stress of the stress vs. strain curves, strain rate sensitivity and activation energy for dynamic recrystallization are analyzed. Results show that the recycled Al alloy containing 0.5 wt % Fe exhibits higher peak stresses and larger activation energy than the recycled Al alloy containing 0.1 wt % Fe, which results from the fact that there are more dispersed AlMgFeSi and/or AlFeSi precipitates in the recycled Al alloy containing 0.5 wt % Fe as confirmed by SEM observation and energy spectrum analysis. It is also shown that the Fe content has little effect on the strain rate sensitivity of the recycled Al alloys.

  8. CoFeRh alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tabakovic, Ibro [Seagate Technology, Research and Development, Bloomington, MN 55435 (United States)], E-mail: ibro.m.tabakovic@seagate.com; Qiu Jiaoming; Riemer, Steve; Sun Ming; Vas' ko, Vlad; Kief, Mark [Seagate Technology, Research and Development, Bloomington, MN 55435 (United States)

    2008-01-01

    The electrochemical behavior of Rh(III) species in CoFe solution containing RhCl{sub 3}, NH{sub 4}Cl, H{sub 3}BO{sub 3}, CoSO{sub 4}, FeSO{sub 4}, saccharin, and NaLS (Na lauryl sulfate) has been investigated. The electrochemistry of Rh(III) species is influenced by each of the compounds present in CoFe plating solution, but especially by addition of saccharin and H{sub 3}BO{sub 3} to the RhCl{sub 3}-NH{sub 4}Cl solution. The nucleation and growth of Rh on GC (glassy carbon), Ru, and Cu electrodes from NH{sub 4}Cl solution was studied using the potentiostatic current-transient methods. The results support a predominantly progressive nucleation of Rh on all three-electrode surfaces. The nucleation kinetic parameters ANo (steady state nucleation rate) and Ns (saturation nuclear number density) were found to vary with potential and are electrode-dependent in order: GC > Ru{approx}Cu. The electrodeposited Rh films obtained from NH{sub 4}Cl solution and nonmagnetic CoFeRh film obtained from CoFe solution were characterized in terms of the following properties: morphology, surface roughness, crystal structure and chemical composition. The origin of light elements found in Rh and CoFeRh films (O, Cl, S, C, N) was discussed.

  9. CoFeRh alloys

    International Nuclear Information System (INIS)

    Tabakovic, Ibro; Qiu Jiaoming; Riemer, Steve; Sun Ming; Vas'ko, Vlad; Kief, Mark

    2008-01-01

    The electrochemical behavior of Rh(III) species in CoFe solution containing RhCl 3 , NH 4 Cl, H 3 BO 3 , CoSO 4 , FeSO 4 , saccharin, and NaLS (Na lauryl sulfate) has been investigated. The electrochemistry of Rh(III) species is influenced by each of the compounds present in CoFe plating solution, but especially by addition of saccharin and H 3 BO 3 to the RhCl 3 -NH 4 Cl solution. The nucleation and growth of Rh on GC (glassy carbon), Ru, and Cu electrodes from NH 4 Cl solution was studied using the potentiostatic current-transient methods. The results support a predominantly progressive nucleation of Rh on all three-electrode surfaces. The nucleation kinetic parameters ANo (steady state nucleation rate) and Ns (saturation nuclear number density) were found to vary with potential and are electrode-dependent in order: GC > Ru∼Cu. The electrodeposited Rh films obtained from NH 4 Cl solution and nonmagnetic CoFeRh film obtained from CoFe solution were characterized in terms of the following properties: morphology, surface roughness, crystal structure and chemical composition. The origin of light elements found in Rh and CoFeRh films (O, Cl, S, C, N) was discussed

  10. Metal Injection Molding (MIM) of NdFeB Magnets

    OpenAIRE

    Hartwig T.; Lopes L.; Wendhausen P.; Ünal N.

    2014-01-01

    Due to the increased and unstable prices for Rare Earth elements there are activities to develop alternative hard magnetic materials. Reducing the amount of material necessary to produce complex sintered NdFeB magnets can also help to reduce some of the supply problem. Metal Injection Molding (MIM) is able to produce near net shape parts and can reduce the amount of finishing to achieve final geometry. Although MIM of NdFeB has been patented and published fairly soon after the development of ...

  11. Thermodynamic modeling of the Co-Fe-O system

    DEFF Research Database (Denmark)

    Zhang, Weiwei; Chen, Ming

    2013-01-01

    As a part of the research project aimed at developing a thermodynamic database of the La-Sr-Co-Fe-O system for applications in Solid Oxide Fuel Cells (SOFCs), the Co-Fe-O subsystem was thermodynamically re-modeled in the present work using the CALPHAD methodology. The solid phases were described...... using the Compound Energy Formalism (CEF) and the ionized liquid was modeled with the ionic two-sublattice model based on CEF. A set of self-consistent thermodynamic parameters was obtained eventually. Calculated phase diagrams and thermodynamic properties are presented and compared with experimental...

  12. Environmental transmission electron microscopy investigations of Pt-Fe2O3 nanoparticles for nucleating carbon nanotubes

    DEFF Research Database (Denmark)

    He, Maoshuai; Jin, Hua; Zhang, Lili

    2016-01-01

    Elucidating the evolution of bimetallic catalyst for nucleating carbon nanotube has been challenging. In this work, acorn-like Pt-Fe2O3 nanoparticles are developed for the growth of single-walled carbon nanotubes (SWCNTs) by chemical vapor deposition. Using in situ environmental transmission...... electron microscopy, restructuring of the acorn-like Pt-Fe2O3 nanoparticles at reaction conditions is investigated. Upon heating to reaction temperature, ε-Fe2O3 is converted to β-Fe2O3, which can be subsequently reduced to metallic Fe once introducing CO. As Pt promotes the carburization of Fe, part...

  13. Natural variation for Fe-efficiency is associated with upregulation of Strategy I mechanisms and enhanced citrate and ethylene synthesis in Pisum sativum L.

    Science.gov (United States)

    Kabir, Ahmad H; Paltridge, Nicholas G; Able, Amanda J; Paull, Jeffrey G; Stangoulis, James C R

    2012-06-01

    Iron (Fe)-deficiency is a common abiotic stress in Pisum sativum L. grown in many parts of the world. The aim of the study was to investigate variation in tolerance to Fe deficiency in two pea genotypes, Santi (Fe-efficient) and Parafield (Fe-inefficient). Fe deficiency caused greater declines in chlorophyll score, leaf Fe concentration and root-shoot development in Parafield compared to Santi, suggesting greater Fe-efficiency in Santi. Fe chelate reductase activity and ethylene production were increased in the roots of Santi and to a lesser extent in Parafield under Fe deficiency, while proton extrusion was only occurred in Santi. Moreover, expression of the Fe chelate reductase gene, FRO1, and Fe transporter, RIT1 were upregulated in Fe-deficient roots of Santi. Expression of HA1 (proton extrusion) was also significantly higher in Santi when compared to Parafield grown in Fe-deficient conditions. Furthermore, the application of the ethylene biosynthesis inhibitor, 1-aminoisobutyric acid reduced the Fe chelate reductase activity, supporting a direct role for ethylene in its induction. A significant increase in root citrate was only observed in Santi under Fe deficiency indicating a role for citrate in the Fe-efficiency mechanism. Taken together, our physiological and molecular data indicate that genotypic variation in tolerance to Fe deficiency in Santi and Parafield plants is a result of variation in a number of Strategy I mechanisms and also suggest a direct role for ethylene in Fe reductase activity. The pea cultivar, Santi provides a new source of Fe-efficiency that can be exploited to breed more Fe-efficient peas.

  14. New Fe-56 Evaluation for the CIELO project

    Energy Technology Data Exchange (ETDEWEB)

    Nobre, G P [Brookhaven National Laboratory (BNL); Herman, Micheal W [Brookhaven National Laboratory (BNL); Brown, D A [Brookhaven National Laboratory (BNL); Capote, R. [International Atomic Energy Agency (IAEA), Vienna / Austria and Universidad de Sevilla, Spain; Trkov, A. [International Atomic Energy Agency (IAEA); Leal, Luiz C [ORNL; Plompen, A. [Institute for Reference Materials and Measurements (IRMM), Geel, Belgium; Danon, Y. [Rensselaer Polytechnic Institute (RPI); Qian, Jing [China Nuclear Data Center; Ge, Zhigang [China Nuclear Data Center; Liu, Tingjin [China Nuclear Data Center; Lu, Hnalin [China Institute of Atomic Energy (CIAE); Ruan, Xichao [China Institute of Atomic Energy (CIAE)

    2016-01-01

    The Collaborative International Evaluated Library Organisation (CIELO) aims to provide revised and updated evaluations for Pu-239, U-238,U-235, Fe-56, O-16, and H-1 through international collaboration. This work, which is part of the CIELO project, presents the initial results for the evaluation of the Fe-56 isotope, with neutron-incident energy ranging from 0 to 20 MeV. The Fe-56(n,p) cross sections were fitted to reproduce the ones from IRDFF dosimetry file. Our preliminary file provides good cross-section agreements for the main angle-integrated reactions, as well as a reasonable overall agreement for angular distributions and double-differential spectra, when compared to previous evaluations.

  15. Interstellar ^{60}Fe on the Surface of the Moon.

    Science.gov (United States)

    Fimiani, L; Cook, D L; Faestermann, T; Gómez-Guzmán, J M; Hain, K; Herzog, G; Knie, K; Korschinek, G; Ludwig, P; Park, J; Reedy, R C; Rugel, G

    2016-04-15

    A dying massive star ends in a supernova explosion ejecting a large fraction of its mass into the interstellar medium. If this happens nearby, part of the ejecta might end on Solar System bodies and, in fact, radioactive ^{60}Fe has been detected on the Pacific ocean floor in about 2 Ma old layers. Here, we report on the detection of this isotope also in lunar samples, originating presumably from the same event. The concentration of the cosmic ray produced isotope ^{53}Mn, measured in the same samples, proves the supernova origin of the ^{60}Fe. From the ^{60}Fe concentrations found we deduce a reliable value for the local interstellar fluence in the range of 1×10^{8}  at/cm^{2}. Thus, we obtain constraints on the recent and nearby supernova(e).

  16. Spin-Lattice Coupling and Superconductivity in Fe Pnictides

    Directory of Open Access Journals (Sweden)

    T. Egami

    2010-01-01

    Full Text Available We consider strong spin-lattice and spin-phonon coupling in iron pnictides and discuss its implications on superconductivity. Strong magneto-volume effect in iron compounds has long been known as the Invar effect. Fe pnictides also exhibit this effect, reflected in particular on the dependence of the magnetic moment on the atomic volume of Fe defined by the positions of the nearest neighbor atoms. Through the phenomenological Landau theory, developed on the basis of the calculations by the density functional theory (DFT and the experimental results, we quantify the strength of the spin-lattice interaction as it relates to the Stoner criterion for the onset of magnetism. We suggest that the coupling between electrons and phonons through the spin channel may be sufficiently strong to be an important part of the superconductivity mechanism in Fe pnictides.

  17. Equilibrium Fe isotope fractionation between inorganic aqueous Fe(III) and the siderophore complex, Fe(III)-desferrioxamine B

    DEFF Research Database (Denmark)

    Dideriksen, Knud; Baker, Joel A.; Stipp, Susan Louise Svane

    2008-01-01

    In oxic oceans, most of the dissolved iron (Fe) exists as complexes with siderophore-like, strongly coordinating organic ligands. Thus, the isotope composition of the little amount of free inorganic Fe that is available for precipitation and preservation in the geological record may largely...... be controlled by isotope fractionation between the free and complexed iron.We have determined the equilibrium Fe isotope fractionation induced by organic ligand activity in experiments with solutions having co-existing inorganic Fe(III) species and siderophore complexes, Fedesferrioxamine B (at pH 2). The two...... differently complexed Fe(III) pools were separated by addition of Na2CO3, which led to immediate precipitation of the inorganic Fe without causing significant dissociation of Fe-desferrioxamine complexes. Experiments using enriched 57Fe tracer showed that isotopic equilibration between the 57Fe...

  18. The Moessbauer effect in Fe(III) HEDTA, Fe(III) EDTA, and Fe(III) CDTA compounds

    International Nuclear Information System (INIS)

    Prado, F.R.

    1989-01-01

    The dependence of Moessbauer spectra with pH value of Fe(III)HEDTA and Fe(III)CDTA compounds is studied. Informations on formation processes of LFe-O-FeL (L=ligand) type dimers by the relation of titration curves of Fe(III)EDTA, Fe(III)HEDTA and Fe(III)CDTA compounds with the series of Moessbauer spectra, are obtained. Some informations on Fe-O-Fe bond structure are also obtained. Comparing the titration curves with the series of Moessbauer spectra, it is concluded that the dimerization process begins when a specie of the form FeXOH α (X = EDTA, HEDTA, CDTA; α = -1, -2) arises. (M.C.K.) [pt

  19. MIL-100-Fe derived N-doped Fe/Fe3C@C electrocatalysts for efficient oxygen reduction reaction

    Science.gov (United States)

    Guo, Dakai; Han, Sancan; Wang, Jiacheng; Zhu, Yufang

    2018-03-01

    N-doped porous Fe/Fe3C@C electrocatalysts were prepared by the pyrolysis of the hexamethylenetetramine (HMT)-incorporated MIL-100-Fe at different temperatures (700-1000 °C) under N2 atmosphere. Rotary evaporation of MIL-100-Fe and HMT solution could make more N-enriched HMT molecules enter into the pores of MIL-100-Fe, thus improving nitrogen contents of the final pyrolyzed samples. All pyrolyzed samples show porous textures with middle specific surface areas. The X-ray photoelectron spectroscopy (XPS) results demonstrate the successful introduction of N atoms into carbon framework. Sample Fe-N2-800 prepared by annealing the precursors with the HMT/MIL-100-Fe weight ratio of 2 at 800 °C exhibits the best electrocatalytic activity towards the oxygen reduction reaction (ORR) in terms of onset potential and current density because of high graphitic N and pyridinic N content. The enwrapped Fe/Fe3C nanoparticles and Fe-Nx active sites in these samples could also boost the ORR activity synergistically. Moreover, sample Fe-N2-800 demonstrates a dominant four electron reduction process, as well as excellent long-term operation stability and methanol crossover resistance. Thus, the N-doped Fe/Fe3C@C composites derived from the HMT-incorporated MIL-100-Fe are promising electrocatalysts to replace Pt/C for ORR in practical applications.

  20. Motorcycle Parts

    Science.gov (United States)

    1993-01-01

    An article in NASA Tech Briefs describing a vacuum bagging process for forming composite parts helped a small Oklahoma Company to improve its manufacturing process. President of Performance Extremes, Larry Ortega, and his partners make motorcycle parts from carbon/epoxy to reduce weight. Using vacuum bags, parts have a better surface and fewer voids inside. When heat used in the vacuum bag process caused deformation upon cooling, a solution found in another tech brief solved the problem. A metal plate inside the vacuum bag made for more even heat transfer. A third article described a simple procedure for repairing loose connector pins, which the company has also utilized.

  1. Ligand-controlled Fe mobilization catalyzed by adsorbed Fe(II) on Fe(hydr)oxides

    Science.gov (United States)

    Kang, Kyounglim; Biswakarma, Jagannath; Borowski, Susan C.; Hug, Stephan J.; Hering, Janet G.; Schenkeveld, Walter D. C.; Kraemer, Stephan M.

    2017-04-01

    Dissolution of Fe(hydr)oxides is a key process in biological iron acquisition. Due to the low solubility of iron oxides in environments with a circumneutral pH, organisms may exude organic compounds catalyzing iron mobilization by reductive and ligand controlled dissolution mechanisms. Recently, we have shown synergistic effects between reductive dissolution and ligand-controlled dissolution that may operate in biological iron acquisition. The synergistic effects were observed in Fe mobilization from single goethite suspensions as well as in suspensions containing calcareous soil[1],[2]. However, how the redox reaction accelerates Fe(hydr)oxide dissolution by ligands is not studied intensively. In our study, we hypothesized that electron transfer to structural Fe(III) labilizes the Fe(hydr)oxide structure, and that this can accelerate ligand controlled dissolution. Systematical batch dissolution experiments were carried out under anoxic conditions at environmentally relevant pH values in which various Fe(hydr)oxides (goethite, hematite, lepidocrocite) interacted with two different types of ligand (desferrioxamine B (DFOB) and N,N'-Di(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid monohydrochloride (HBED)). Electron transfer to the structure was induced by adsorbing Fe(II) to the mineral surface at various Fe(II) concentrations. Our results show a distinct catalytic effect of adsorbed Fe(II) on ligand controlled dissolution, even at submicromolar Fe(II) concentrations. We observed the effect for a range of iron oxides, but it was strongest in lepidocrocite, most likely due to anisotropy in conductivity leading to higher near-surface concentration of reduced iron. Our results demonstrate that the catalytic effect of reductive processes on ligand controlled dissolution require a very low degree of reduction making this an efficient process for biological iron acquisition and a potentially important effect in natural iron cycling. References 1. Wang, Z. M

  2. Synthesis, characterization and magnetic properties of Fe-Al nanopins

    International Nuclear Information System (INIS)

    Zhang, W.S.; Brueck, E.; Li, W.F.; Si, P.Z.; Geng, D.Y.; Zhang, Z.D.

    2005-01-01

    We report the synthesis of Fe-Al nanopins using arc discharge. The morphology and chemical composition of the Fe-Al nanopins were studied by means of X-ray diffraction, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). The nanopins are composed of a spherical base of about 20-100 nm and a needle-like tip of about several hundred nanometers. EDX and HRTEM studies indicate that the spherical base is mainly composed of α-Fe and FeAl core coated with a thin Al 2 O 3 layer, while the needle-like part contains only Al and O and corresponds to Al 2 O 3 . The formation mechanism of the nanopins is suggestive of a vapor-liquid-solid (VLS) growth process. The as-prepared Fe-Al nanopins show ferromagnetic properties. The temperature dependence of the magnetization at high temperatures indicates the existence of some phase transformations

  3. Strong 3D and 1D magnetism in hexagonal Fe-chalcogenides FeS and FeSe vs. weak magnetism in hexagonal FeTe

    Energy Technology Data Exchange (ETDEWEB)

    Parker, David S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-06-13

    We present a comparative theoretical study of the hexagonal forms of the Fe-chalcogenides FeS, FeSe and FeTe with their better known tetragonal forms. While the tetragonal forms exhibit only an incipient antiferromagnetism and experimentally show superconductivity when doped, the hexagonal forms of FeS and FeSe display a robust magnetism. We show that this strong magnetism arises from a van Hove singularity associated with the direct Fe-Fe c-axis chains in the generally more three-dimensional NiAs structure. We also find that hexagonal FeTe is much less magnetic than the other two hexagonal materials, so that unconventional magnetically-mediated superconductivity is possible, although a large Tc value is unlikely.

  4. Strong 3D and 1D magnetism in hexagonal Fe-chalcogenides FeS and FeSe vs. weak magnetism in hexagonal FeTe.

    Science.gov (United States)

    Parker, David S

    2017-06-13

    We present a comparative theoretical study of the hexagonal forms of the Fe-chalcogenides FeS, FeSe and FeTe with their better known tetragonal forms. While the tetragonal forms exhibit only an incipient antiferromagnetism and experimentally show superconductivity when doped, the hexagonal forms of FeS and FeSe display a robust magnetism. We show that this strong magnetism arises from a van Hove singularity associated with the direct Fe-Fe c-axis chains in the generally more three-dimensional NiAs structure. We also find that hexagonal FeTe is much less magnetic than the other two hexagonal materials, so that unconventional magnetically-mediated superconductivity is possible, although a large T c value is unlikely.

  5. Influence of an Fe cap layer on the structural and magnetic properties of Fe49Pt51/Fe bi-layers

    International Nuclear Information System (INIS)

    Chao-Yang, Duan; Bin, Ma; Zong-Zhi, Zhang; Qing-Yuan, Jin; Fu-Lin, Wei

    2009-01-01

    The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated. Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and improve the chemical ordering of L1 0 FePt films. Moreover, the coercivity increases when a thin Fe layer covers the FePt layer. Beyond a critical thickness, however, the Fe cover layer quickens the magnetization reversal of Fe 49 Pt 51 /Fe bi-layers by their exchange coupling

  6. 49 CFR Appendix B to Part 20 - Disclosure Form To Report Lobbying

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Disclosure Form To Report Lobbying B Appendix B to Part 20 Transportation Office of the Secretary of Transportation NEW RESTRICTIONS ON LOBBYING Pt. 20, App. B Appendix B to Part 20—Disclosure Form To Report Lobbying EC02FE91.097 EC02FE91.098 EC02FE91.099 ...

  7. 57Fe Mossbauer spectroscopy of U6Fe

    International Nuclear Information System (INIS)

    Lemon, G.; Boolchand, P.; Stevens, M.; DeLong, L.E.; Huber, J.G.; Marcuso, M.

    1986-04-01

    Samples of U 6 Fe were prepared by arc melting U and enriched 57 Fe. The samples display superconducting transitions which are sensitive to long-term exposure to air. Room temperature spectra of U 6 Fe typically display a majority site A (quadrupole splitting Δ = 0.749(3) mm/s, isomer shift delta = 0.482(6) mm/s relative to Cu) and a minority site B (Δ = 0.55(3) mm/s, sigma = 0.12(3) mm/s) with the site intensity ratio (I/sub B//I/sub A/) typically 0.05 to 0.10. The I/sub B//I/sub A/ intensity ratio increases upon air exposure of the samples. We have studied Moessbauer spectra as a function of temperature T in the range 15 0 K less than or equal to T less than or equal to 310 0 K paying particular attention to the T-variation of the isomer-shift and recoil-free-fraction of the majority site A. Results indicate a consistent softening of lattice vibrations of U 6 Fe at T approx. = 170 0 K

  8. Fe3Si surface coating on SiFe steel

    International Nuclear Information System (INIS)

    Schneeweiss, O.; Pizurova, N.; Jiraskova, Y.; Zak, T.; Cornut, B.

    2000-01-01

    Fe 3 Si layers were prepared using chemical vapor deposition of Si on the surface of Go steel and its subsequent heat treatment. The changes in the structure and phase composition after different heat treatment conditions have been analyzed. The coating is characterized by high hardness, good corrosion resistance, high electrical resistivity, and the spin texture which differs from the steel substrate

  9. FE-Simulation Of Hemming In The Automotive Industry

    International Nuclear Information System (INIS)

    Sigvant, Mats; Mattiasson, Kjell

    2005-01-01

    This paper summarizes and presents the most important results from a research project on FE simulation of hemming carried out at Volvo Cars Body Components and Chalmers University of Technology. In the automotive industry, hemming is used to join two sheet metal panels by bending the flange of the outer panel over the inner one. The final goal of the project was to simulate all of the hemming steps of production parts. In order to make three-dimensional simulations of hemming possible within reasonable simulation times, it is necessary to use shell elements and not solid elements. On the other hand, the radius of curvature of the outer part in the folded area is very small, normally of the same order of magnitude as the sheet thickness. This fact raises the question if shell elements are applicable in FE simulation of hemming. One part of the project was therefore a thorough investigation of the order of magnitude of the errors resulting from the use of shell elements in FE simulation of hemming. Another part of the project was devoted to three-dimensional simulations of the hemming of an automotive hood. The influence on the roll-in from several parameters, such as shell element formulation, adhesives, and anisotropy was studied. Finally, results from a forming simulation were also mapped to the flanging and hemming models in order to study the influence from the stamping of the outer panel on the roll-in

  10. Enhanced and broadband microwave absorption of flake-shaped Fe and FeNi composite with Ba ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wangchang [Research Center of Magnetic and Electronic Materials, College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310000 (China); Lv, Junjun, E-mail: LyuJunJun@caep.cn [Institute of Chemical Material, CAEP, Mianyang 621900 (China); Zhou, Xiang; Zheng, Jingwu; Ying, Yao; Qiao, Liang; Yu, Jing [Research Center of Magnetic and Electronic Materials, College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310000 (China); Che, Shenglei, E-mail: cheshenglei@zjut.edu.cn [Research Center of Magnetic and Electronic Materials, College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310000 (China)

    2017-03-15

    In order to achieve a broad bandwidth absorber at high frequency, the composites of M-type ferrite BaCo{sub 1.0}Ti{sub 1.0}Fe{sub 10}O{sub 19} (BaM) with flaked carbonyl iron powders (CIP) and flaked Fe{sub 50}Ni{sub 50} were prepared to optimize the surface impedance in broadband frequency, respectively. The diameter of the flaked carbonyl iron powders (CIP) and Fe{sub 50}Ni{sub 50} is in the range of 5–10 µm and 10–20 µm and the thickness of the CIP and Fe{sub 50}Ni{sub 50} is close to 200 nm and 400 nm, respectively. The complex permeability and permittivity show that the addition of BaM obviously reduces the values of real part of permittivity and imaginary part of the permeability which can enhance the matched-wave-impedance. The absorption bands less than −10 dB of CIP-BaM and FeNi-BaM absorber approach to 5.5 GHz (5.7–11.2 GHz) and 7 GHz (11–18 GHz) at 1.5 mm. However, the bands of CIP and FeNi are only 1.9 GHz (4.7–6.6 GHz) and 2.1 GHz (4.0–6.1 GHz). Hence, the electromagnetic match property is greatly improved by BaM ferrites, and this composite shows a broaden absorption band. - Highlights: • In order to achieve a broad bandwidth absorber at high frequency, the composites of M-type ferrite with flaked carbonyl iron powdersand Fe{sub 50}Ni{sub 50} were prepared to optimize the surface impedance. • The complex permeability and permittivity show that the addition of BaM obviously reduces the real part of permittivity and imaginary part of the permeability enhancing the matched-wave-impedance. • The structure, morphology and electromagnetic properties are studied in detail. The optimized properties are ascribed to the strength of dipolar polarization and high frequency magnetic resonance.

  11. Giant magnetoimpedance effect in sputtered single layered NiFe film and meander NiFe/Cu/NiFe film

    International Nuclear Information System (INIS)

    Chen, L.; Zhou, Y.; Lei, C.; Zhou, Z.M.; Ding, W.

    2010-01-01

    Giant magnetoimpedance (GMI) effect on NiFe thin film is very promising due to its application in developing the magnetic field sensors with highly sensitivity and low cost. In this paper, the single layered NiFe thin film and NiFe/Cu/NiFe thin film with a meander structure are prepared by the MEMS technology. The influences of sputtering parameters, film structure and conductor layer width on GMI effect in NiFe single layer and meander NiFe/Cu/NiFe film are investigated. Maximum of the GMI ratio in single layer and sandwich film is 5% and 64%, respectively. The results obtained are useful for developing the high-performance magnetic sensors based on NiFe thin film.

  12. Equilibrium Fe isotope fractionation between inorganic aqueous Fe(III) and the siderophore complex, Fe(III)-desferrioxamine B

    DEFF Research Database (Denmark)

    Dideriksen, Knud; Baker, Joel A.; Stipp, Susan Louise Svane

    2008-01-01

    be controlled by isotope fractionation between the free and complexed iron.We have determined the equilibrium Fe isotope fractionation induced by organic ligand activity in experiments with solutions having co-existing inorganic Fe(III) species and siderophore complexes, Fedesferrioxamine B (at pH 2). The two......-type fractionation during precipitation, this experiment yielded an isotope fractionation factor of a56Fesolution-solid=1.00027. Calculations based on these results indicate that isotopic re-equilibration is unlikely to significantly affect our determined equilibrium Fe isotope fractionation between inorganically...... and organically complexed Fe. To determine the equilibrium Fe isotope fractionation between inorganically and organically bound Fe(III), experiments with variable proportions of inorganic Fe were carried out at 25 °C. Irrespective of the proportion of inorganic Fe, equilibrium fractionation factors were within...

  13. Thermodynamics of Fe(II)Fe(III) oxide systems I. Hydrothermal Fe3O4

    Science.gov (United States)

    Bartel, J.J.; Westrum, E.F.; Haas, J.L.

    1976-01-01

    The heat capacity of a hydrothermally-prepared polycrystalline sample of Fe3O4 was measured from 53 to 350 K, primarily to study the thermophysics of the Verwey transitions. Although the bifurcation of the transition was confirmed, the sample was found to contain traces of manganese. The observed transition temperatures of 117.0 and 123.0 K are 3.7 and 4.2 K higher respectively than those found in pure Fe3O4. Ancillary analytical results are consistent and indicate a stoichiometry of Mn0.008Fe2.992O4 for this material. Characteristics in the transition region are ascribed to dopant effects. ?? 1976.

  14. Structural and magnetic properties of NdFeB and NdFeB/Fe films with Mo addition

    Energy Technology Data Exchange (ETDEWEB)

    Urse, M; Grigoras, M; Lupu, N; Chiriac, H, E-mail: urse@phys-iasi.ro [National Institute of R and D for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania)

    2011-07-06

    The influence of the Mo addition on the microstructure and magnetic properties of Nd-Fe-B and Nd-Fe-B/Fe films was studied. The coercivity is a key parameter in the control of technical performances of Nd-Fe-B films. A small amount of about 1 at.% Mo can enhance the coercivity of Nd-Fe-B film by controlling the growth of soft and hard magnetic grains. A coercivity of 22.1 kOe, a remanence ratio, M{sub r}/M{sub s}, of 0.83 and a maximum energy product of 8 MGOe were obtained for Ta/[NdFeBMo(1at.%)(540nm)/Ta films annealed at 650{sup 0}C for 20 minutes due to Mo precipitates formed at the Nd{sub 2}Fe{sub 14}B phase boundaries which prevent the nucleation and expansion of the magnetic domains. Simultaneous use of Mo as addition and the stratification of Nd-Fe-B-Mo films using Fe as spacer layer are important tools for the improvement of the hard magnetic properties of Nd-Fe-B films. The Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta multilayer film annealed at 620{sup 0}C exhibits an increase in the coercivity from 12.1 kOe to 22.8 kOe, in the remanence ratio from 0.77 to 0.80, and in the maximum energy product from 4.5 to 7.1 MGOe in comparison with Ta/Nd-Fe-B/Ta film. As compared to Ta/Nd-Fe-B/Ta film, the Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta film presents a decrease in the crystallization temperature of about 30{sup 0}C.

  15. Spin structure of exchange biased heterostructures. Fe/MnF{sub 2} and Fe/FeF{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, B.

    2006-12-18

    In this work, the {sup 57}Fe probe layer technique is used in order to investigate the depth- and temperature-dependent Fe-layer spin structure of exchange biased Fe/MnF{sub 2} and Fe/FeF{sub 2} (pseudo-twinned) antiferromagnetic (AFM) systems by conversion electron Moessbauer spectroscopy (CEMS) and nuclear resonant scattering (NRS) of synchrotron radiation. Two kinds of samples with a 10 A {sup 57}Fe probe layer directly at or 35 A away from the interface, labeled as interface and center sample, respectively, were studied in this work. The results obtained by CEMS for Fe/MnF{sub 2} suggests that, at 80 K, i.e., above T{sub N}=67 K of MnF{sub 2}, the remanent state Fe-layer spin structure of the two studied samples are slightly different due to their different microstructure. In the temperature range from 300 K to 80 K, the Fe-layer spin structure does not change just by zero-field cooling the sample in remanence. For Fe/FeF{sub 2}, a continuous non-monotonic change of the remanent-state Fe spin structure was observed by cooling from 300 K to 18 K. NRS of synchrotron radiation was used to investigate the temperature- and depth-dependent Fe-layer spin structure during magnetization reversal in pseudo-twinned Fe/MnF{sub 2}. A depthdependent Fe spin structure in an applied magnetic field (applied along the bisector of the twin domains) was observed at 10 K, where the Fe spins closer to the interface are not aligned along the field direction. The depth-dependence disappears at 150 K. (orig.)

  16. Self organization of FeGe/FeSi/FeGe layered structures on Ge and their electrical conduction properties

    Science.gov (United States)

    Matsukura, B.; Hiraiwa, Y.; Nakajima, T.; Narumi, K.; Sakai, S.; Sadoh, T.; Miyao, M.; Maeda, Y.

    We have investigated self organization of novel FeGe/FeSi/FeGe layered structures on Ge(111) and their electrical conduction properties. From analyses of compositional change, diffusion dynamics analyses and microstructure observations, it was revealed that the self organization of the layered structures was enhanced by spinodal decomposition which may be induced by pronounced compositional changes associating to inhomogeneous interdiffusion. The electrical conduction showed singular temperature dependence which obviously reflected natureof Kondo insulator FeSi.

  17. Effects of Fe fine powders doping on hot deformed NdFeB magnets

    International Nuclear Information System (INIS)

    Lin, Min; Wang, Huijie; Zheng, Jingwu; Yan, Aru

    2015-01-01

    The composite NdFeB magnets with blending melt-spun flakes and Fe fine powders were prepared by the hot-pressed and hot-deformed route. Characterizations of the hot-deformed NdFeB magnets affected by the doped Fe powders were tested. The doped Fe powders decrease the hot-deformed pressure when the strain is between 15 and 50%. XRD patterns show that the doped Fe powders have little influence on the c-axis alignment of hot-deformed NdFeB magnets in the press direction. The B r and the (BH) max get improved when the doped Fe powders are less than 3 wt%. The doped Fe of hot-deformed NdFeB magnets exists in the elongated state and the spherical state surrounded by the Nd-rich phase. With the Fe fraction increasing, the potential of magnet moves to the positive direction and the diameter of the Nyquist arc becomes larger, which indicate that the corrosion resistance improved effectively. The bending strength was enhanced by the elongated α-Fe phase embedded in the matrix 2:14:1 phase. - Highlights: • The doped Fe powders have little influence on the c-axis alignment of magnets. • The elongated Fe powders are more than the spherical Fe powders in the magnets. • The corrosion resistance is improved effectively with the increasing Fe fraction. • The bending strength is enhanced by the elongated α-Fe phase embedded in the matrix

  18. Iron allocation in leaves of Fe-deficient cucumber plants fed with natural Fe complexes.

    Science.gov (United States)

    Zanin, Laura; Tomasi, Nicola; Rizzardo, Cecilia; Gottardi, Stefano; Terzano, Roberto; Alfeld, Matthias; Janssens, Koen; De Nobili, Maria; Mimmo, Tanja; Cesco, Stefano

    2015-05-01

    Iron (Fe) sources available for plants in the rhizospheric solution are mainly a mixture of complexes between Fe and organic ligands, including phytosiderophores (PS) and water-extractable humic substances (WEHS). In comparison with the other Fe sources, Fe-WEHS are more efficiently used by plants, and experimental evidences show that Fe translocation contributes to this better response. On the other hand, very little is known on the mechanisms involved in Fe allocation in leaves. In this work, physiological and molecular processes involved in Fe distribution in leaves of Fe-deficient Cucumis sativus supplied with Fe-PS or Fe-WEHS up to 5 days were studied combining different techniques, such as radiochemical experiments, synchrotron micro X-ray fluorescence, real-time reverse transcription polymerase chain reaction and in situ hybridization. In Fe-WEHS-fed plants, Fe was rapidly (1 day) allocated into the leaf veins, and after 5 days, Fe was completely transferred into interveinal cells; moreover, the amount of accumulated Fe was much higher than with Fe-PS. This redistribution in Fe-WEHS plants was associated with an upregulation of genes encoding a ferric(III) -chelate reductase (FRO), a Fe(2+) transporter (IRT1) and a natural resistance-associated macrophage protein (NRAMP). The localization of FRO and IRT1 transcripts next to the midveins, beside that of NRAMP in the interveinal area, may suggest a rapid and efficient response induced by the presence of Fe-WEHS in the extra-radical solution for the allocation in leaves of high amounts of Fe. In conclusion, Fe is more efficiently used when chelated to WEHS than PS and seems to involve Fe distribution and gene regulation of Fe acquisition mechanisms operating in leaves. © 2014 Scandinavian Plant Physiology Society.

  19. Nano-stuctured Pt-Fe/C as cathode catalyst in direct methanol fuel cell

    International Nuclear Information System (INIS)

    Li Wenzhen; Zhou Weijiang; Li Huanqiao; Zhou Zhenhua; Zhou Bing; Sun Gongquan; Xin Qin

    2004-01-01

    Pt-Fe/C catalysts were prepared by a modified polyol synthesis method in an ethylene glycol (EG) solution, and then were heat-treated under H 2 /Ar (10 vol.%) at moderate temperature (300 deg. C, Pt-Fe/C300) or high temperature (900 deg. C, Pt-Fe/C900). As comparison, Pt-Fe/C alloy catalyst was prepared by a two-step method (Pt-Fe/C900B). X-ray diffraction (XRD) and transmission electron microscopy (TEM) images show that particles size of the catalyst increases with the increase of treatment temperatures. Pt-Fe/C300 catalyst has a mean particle size of 2.8 nm (XRD), 3.6 nm (TEM) and some Pt-Fe alloy was partly formed in this sample. Pt-Fe/C900B catalyst has the biggest particle size of 6.2 nm (XRD) and the best Pt-Fe alloy form. Cyclicvoltammetry (CV) shows that Pt-Fe/C300 has larger electrochemical surface area than other Pt-Fe/C and the highest utilization ratio of 76% among these Pt-based catalysts. Rotating disk electrode (RDE) cathodic curves show that Pt-Fe/C300 has the highest oxygen reduction reaction (ORR) mass activity (MA) and specific activity (SA), as compared with Pt/C catalyst in 1.0 M HClO 4 . However, Pt-Fe/C catalyst does not appears to be a more active catalyst than Pt/C for ORR in 1.0 M HClO 4 + 0.1 M CH 3 OH. Pt-Fe/C300 exhibits higher ORR activity and better performance than other Pt-Fe/C or Pt/C catalysts when employed for cathode in direct methanol single cell test, the enhancement of the cell performance is logically attributed to its higher ORR activity, which is probably attributed to more Pt 0 species existing and Fe ion corrosion from the catalyst

  20. 57Fe Moessbauer studies on natural chromites

    International Nuclear Information System (INIS)

    Das, D.; Sudarshan, M.; Chintalapudi, S.N.; Chakravorty, K.L.

    1996-01-01

    Five chromite samples procured from two different belts of India have been studied by 57 Fe Moessbauer spectroscopy. It is shown that four symmetric doublets are sufficient to fit the chromite spectrum; the Moessbauer parameters and Fe 3+ /Fe 2+ ratio are computed. For fully oxidized chromite with only Fe 3+ , two doublets are needed and the parameters are computed. (author). 19 refs., 4 figs., 4 tabs

  1. Local smoke-free policy development in Santa Fe, Argentina.

    Science.gov (United States)

    Sebrié, Ernesto M; Glantz, Stanton A

    2010-04-01

    To describe the process of approval and implementation of a comprehensive smoke-free law in the province of Santa Fe, Argentina, between 2005 and 2009. Review of the Santa Fe smoke-free legislation, articles published in local newspapers and documentation on two lawsuits filed against the law, and interviews with key individuals in Santa Fe. Efforts to implement smoke-free policies in Santa Fe began during the 1990s without success, and resumed in 2005 when the provincial Legislature approved the first 100% smoke-free subnational law in Argentina. There was no strong opposition during the discussions within the legislature. As in other parts of the world, pro-tobacco industry interests attempted to block the implementation of the law using well known strategies. These efforts included a controversy media campaign set up, the creation of a hospitality industry association and a virtual smokers' rights group, the introduction of a counterproposal seeking modification of the law, the challenge of the law in the Supreme Court, and the proposal of a weak national bill that would 'conflict' with the subnational law. Tobacco control advocates sought media attention as a strategy to protect the law. Santa Fe is the first subnational jurisdiction in Latin America to have enacted a comprehensive smoke-free policy following the recommendations of the World Health Organization (WHO) Framework Convention on Tobacco Control. After 3 years of implementation, pro-tobacco industry forces failed to undermine the law. Other subnational jurisdictions in Argentina, as well as in Mexico and Brazil are following the Santa Fe example.

  2. Atom exchange between aqueous Fe(II) and structural Fe in clay minerals.

    Science.gov (United States)

    Neumann, Anke; Wu, Lingling; Li, Weiqiang; Beard, Brian L; Johnson, Clark M; Rosso, Kevin M; Frierdich, Andrew J; Scherer, Michelle M

    2015-03-03

    Due to their stability toward reductive dissolution, Fe-bearing clay minerals are viewed as a renewable source of Fe redox activity in diverse environments. Recent findings of interfacial electron transfer between aqueous Fe(II) and structural Fe in clay minerals and electron conduction in octahedral sheets of nontronite, however, raise the question whether Fe interaction with clay minerals is more dynamic than previously thought. Here, we use an enriched isotope tracer approach to simultaneously trace Fe atom movement from the aqueous phase to the solid ((57)Fe) and from the solid into the aqueous phase ((56)Fe). Over 6 months, we observed a significant decrease in aqueous (57)Fe isotope fraction, with a fast initial decrease which slowed after 3 days and stabilized after about 50 days. For the aqueous (56)Fe isotope fraction, we observed a similar but opposite trend, indicating that Fe atom movement had occurred in both directions: from the aqueous phase into the solid and from the solid into aqueous phase. We calculated that 5-20% of structural Fe in clay minerals NAu-1, NAu-2, and SWa-1 exchanged with aqueous Fe(II), which significantly exceeds the Fe atom layer exposed directly to solution. Calculations based on electron-hopping rates in nontronite suggest that the bulk conduction mechanism previously demonstrated for hematite1 and suggested as an explanation for the significant Fe atom exchange observed in goethite2 may be a plausible mechanism for Fe atom exchange in Fe-bearing clay minerals. Our finding of 5-20% Fe atom exchange in clay minerals indicates that we need to rethink how Fe mobility affects the macroscopic properties of Fe-bearing phyllosilicates and its role in Fe biogeochemical cycling, as well as its use in a variety of engineered applications, such as landfill liners and nuclear repositories.

  3. Moessbauer spectroscopic investigations of Fe/Mn-Fischer-Tropsch-catalysts

    International Nuclear Information System (INIS)

    Deppe, P.; Papp, H.; Rosenberg, M.

    1986-01-01

    The phase composition of Fe/Mn oxide catalysts of different compositions after 200 h of Fischer-Tropsch synthesis have been investigated by Moessbauer spectroscopy at room temperature, 77 K and 5 K. The final composition of the bulk catalysts depends strongly on the Mn content and the temperature of reduction before the synthesis. Catalytic activity and selectivity are partly correlated to this phase composition. (Auth.)

  4. Modeling the active site of [FeFe]-hydrogenase: Electro-catalytic ...

    Indian Academy of Sciences (India)

    dithiolate-bridged di-iron com- plexes have been investigated in modelling the active sites of [FeFe]-H2ases. However, the reports of elec- trochemical data on ene-1,2-dithiolate-bridged-{Fe2S2} complexes are scarce. In this study, compound [Fe2{µ-.

  5. Laser alloyed Al-Ni-Fe coatings

    CSIR Research Space (South Africa)

    Pityana, SL

    2008-10-01

    Full Text Available The aim of this work was to produce crack-free thin surface layers consisting of binary (Al-Ni, Al-Fe) and ternary (Al-Ni-Fe) intermetallic phases by means of a high power laser beam. The laser surface alloying was carried out by melting Fe and Ni...

  6. Biogeochemical speciation of Fe in ocean water

    NARCIS (Netherlands)

    Hiemstra, T.; Riemsdijk, van W.H.

    2006-01-01

    The biogeochemical speciation of Fe in seawater has been evaluated using the consistent Non-Ideal Competitive Adsorption model (NICA¿Donnan model). Two types of data sets were used, i.e. Fe-hydroxide solubility data and competitive ligand equilibration/cathodic stripping voltammetry (CLE/CSV) Fe

  7. Mechanical alloying of Hf and Fe powders

    International Nuclear Information System (INIS)

    Mendoza Zelis, L.; Crespo, E.; Creus, M.; Damonte, L.C.; Sanchez, F.H.; Punte, G.

    1994-01-01

    Pure crystalline Hf and Fe powders were mixed and milled under an argon atmosphere. The evolution of the system with milling time was followed with Moessbauer effect spectroscopy and X-ray diffraction. The results indicate that in the first stages an amorphous Fe-rich alloy was gradually formed together with a solid solution of Hf in Fe beyond the solubility limit. (orig.)

  8. Point defects in B.C.C. Fe-Al, Fe-Co, and Fe-Co-V ordered alloys

    International Nuclear Information System (INIS)

    Riviere, J.P.; Dinhut, J.F.

    1982-01-01

    Radiation damage produced at 20 K by 2.5 MeV electrons is studied in three B 2 type Fe-40 at % Al, Fe-Co, Fe-Co-V ordered alloys. The resistivity damage in Fe-40 at % Al ordered single crystals is found less effective in the directions. The results suggest that replacement collision chains are difficult to propagate along the direction. Frenkel pair creation superimposed with disordering can account for the resistivity damage in the initially ordered Fe-Co alloy. Informations concerning replacement collision sequences in direction are derived. During the recovery of all the alloys, three main stages are observed and an ordering enhancement occurs. (author)

  9. Electrical resistivity surface for FeO-Fe2O3-P2O5 glasses

    Science.gov (United States)

    Vaughan, J. G.; Kinser, D. L.

    1975-01-01

    The dc electrical properties and microstructure of x(FeO-Fe2O3)-(100-x)P2O5 glasses were investigated up to a maximum of x = 75 mol %. Results indicate that, in general, the minimum resistivity of the glass does not occur at equal Fe(2+) and Fe(3+) concentrations, although for the special case where x = 55 mol % the minimum does occur at Fe(2+)/Fe total = 0.5, as reported by other investigators. Evidence presented shows that the position of the minimum resistivity is a function of total iron content. The minimum shifts to glasses richer in Fe(2+) at higher total iron concentrations.

  10. Interactions between 59Fe(14C)EDTA and soils containing calcium carbonate

    International Nuclear Information System (INIS)

    Hargitai-Toth, A.; Konya, J.

    1991-01-01

    Interaction between FeEDTA and calcareous soils was followed over a period of four weeks using a radiotracer technique, and a kinetic evaluation of the results was performed. 59 Fe served to determine the quantity of iron, 14 C to assay for EDTA and 45 Ca to measure calcium. During the experiment, i.e. within four weeks in case of the chernozem soil 61% and in case of the clayey meadow soil 51% of the iron chelate disappeared from the solution. The loss in soluble iron was partly due to a rapid sorption process of about an hour and partly due to the slow decomposition of FeEDTA to Fe(OH) 3 . The two processes could be separated using the Christiansen equation. (author) 9 refs.; 1 figs.; 2 tabs

  11. Effect of irradiation temperature on crystallization of {alpha}-Fe induced by He irradiations in Fe{sub 80}B{sub 20} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    San-noo, Toshimasa; Toriyama, Tamotsu; Wakabayashi, Hidehiko; Iijima, Hiroshi [Musashi Inst. of Tech., Tokyo (Japan); Hayashi, Nobuyuki; Sakamoto, Isao

    1997-03-01

    Since amorphous alloys are generally highly resistant to irradiation and their critical radiation dose is an order of magnitude higher for Fe-B amorphous alloy than Mo-methods, these alloys are expected to become applicable as for fusion reactor materials. The authors investigated {alpha}-Fe crystallization in an amorphous alloy, Fe{sub 80}B{sub 20} using internal conversion electron Moessbauer spectroscopy. The amount of {alpha}-Fe component was found to increase by raising the He-irradiation dose. The target part was modified to enable He ion radiation at a lower temperature (below 400 K) by cooling with Peltier element. Fe{sub 80}B{sub 20} amorphous alloy was cooled to keep the temperature at 300 K and exposed to 40 keV He ion at 1-3 x 10{sup 8} ions/cm{sup 2}. The amount of {alpha}-Fe crystal in each sample was determined. The crystal formation was not observed for He ion radiation below 2 x 10{sup 18} ions/cm{sup 2}, but that at 3 x 10{sup 8} ions/ cm{sup 2} produced a new phase ({delta} +0.40 mm/sec, {Delta} = 0.89 mm/sec). The decrease in the radiation temperature from 430 to 300 K resulted to extremely repress the production of {alpha}-Fe crystal, suggesting that the crystallization induced by He-radiation cascade is highly depending on the radiation temperature. (M.N.)

  12. Process and genes for expression and overexpression of active [FeFe] hydrogenases

    Science.gov (United States)

    Seibert, Michael; King, Paul W; Ghirardi, Maria Lucia; Posewitz, Matthew C; Smolinski, Sharon L

    2014-09-16

    A process for expression of active [FeFe]-hydrogenase in a host organism that does not contain either the structural gene(s) for [FeFe]-hydrogenases and/or homologues for the maturation genes HydE, HydF and HyG, comprising: cloning the structural hydrogenase gene(s) and/or the maturation genes HydE, HydF and HydG from an organisms that contains these genes into expression plasmids; transferring the plasmids into an organism that lacks a native [FeFe]-hydrogenase or that has a disrupted [FeFe]-hydrogenase and culturing it aerobically; and inducing anaerobiosis to provide [FeFe] hydrogenase biosynthesis and H?2#191 production.

  13. Zn and Fe biofortification: the right chemical environment for human bioavailability.

    Science.gov (United States)

    Clemens, Stephan

    2014-08-01

    A considerable fraction of global disease burden and child mortality is attributed to Fe and Zn deficiencies. Biofortification, i.e. the development of plants with more bioavailable Zn and Fe, is widely seen as the most sustainable solution, provided suitable crops can be generated. In a cereal-dominated diet availability of Fe and Zn for absorption by the human gut is generally low and influenced by a highly complex chemistry. This complexity has mostly been attributed to the inhibitory effect of Fe and Zn binding by phytate, the principal phosphorus storage compound in cereal and legume seeds. However, phytate is only part of the answer to the multifaceted bioavailability question, albeit an important one. Recent analyses addressing elemental distribution and micronutrient speciation in seeds strongly suggest the existence of different Fe and Zn pools. Exploration of natural variation in maize showed partial separation of phytate levels and Fe bioavailability. Observations made with transgenic plants engineered for biofortification lend further support to this view. From a series of studies the metal chelator nicotianamine is emerging as a key molecule. Importantly, nicotianamine levels have been found to not only increase the loading of Fe and Zn into grains. Bioavailability assays indicate a strong activity of nicotianamine also as an enhancer of intestinal Fe and Zn absorption. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  14. Sustained magnetization oscillations in polyaniline-Fe{sub 3}O{sub 4} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Araújo, A. C. V. de [Unidade Acadêmica de Garanhuns, Universidade Federal Rural de Pernambuco, Recife, Pernambuco (Brazil); Rodrigues, A. R., E-mail: ricalde@df.ufpe.br; Machado, F. L. A.; Rezende, S. M. [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco (Brazil); Azevedo, W. M. de [Departamento de Química Fundamental, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco (Brazil)

    2015-09-28

    We report experiments with polyaniline-Fe{sub 3}O{sub 4} (PANI-Fe{sub 3}O{sub 4}) nanocomposites synthesized under several different conditions. With a reaction carried out at room temperature and assisted by intense ultra-violet (UV) irradiation, we observe sustained oscillations in the magnetization with a period of about 25 min. The oscillations are interpreted as the result of an oscillatory chemical reaction in which part of the Fe{sup +2} ions of magnetite, Fe{sub 3}O{sub 4}, are oxidized by the UV irradiation to form Fe{sup +3} so that a fraction of the magnetite content transforms into maghemite, γ-Fe{sub 2}O{sub 3}. Then, Fe{sup +3} ions at the nanoparticle surfaces are reduced and transformed back into Fe{sup +2}, when acting as an oxidizing agent for polyaniline in the polymerization process. Since maghemite has smaller magnetization than magnetite, the oscillating chemical reaction results in the oscillatory magnetization. The observations are interpreted with the Lotka-Volterra nonlinear coupled equations with parameters that can be adjusted to fit very well the experimental data.

  15. The iron chelating agent, deferoxamine detoxifies Fe(Salen-induced cytotoxicity

    Directory of Open Access Journals (Sweden)

    Masanari Umemura

    2017-08-01

    Full Text Available Iron-salen, i.e., μ-oxo-N,N′-bis(salicylideneethylenediamine iron (Fe(Salen was a recently identified as a new anti-cancer compound with intrinsic magnetic properties. Chelation therapy has been widely used in management of metallic poisoning, because an administration of agents that bind metals can prevent potential lethal effects of particular metal. In this study, we confirmed the therapeutic effect of deferoxamine mesylate (DFO chelation against Fe(Salen as part of the chelator antidote efficacy. DFO administration resulted in reduced cytotoxicity and ROS generation by Fe(Salen in cancer cells. DFO (25 mg/kg reduced the onset of Fe(Salen (25 mg/kg-induced acute liver and renal dysfunction. DFO (300 mg/kg improves survival rate after systematic injection of a fatal dose of Fe(Salen (200 mg/kg in mice. DFO enables the use of higher Fe(Salen doses to treat progressive states of cancer, and it also appears to decrease the acute side effects of Fe(Salen. This makes DFO a potential antidote candidate for Fe(Salen-based cancer treatments, and this novel strategy could be widely used in minimally-invasive clinical settings.

  16. Magnetic properties of ND Rich Melt-Spun ND-FE-B alloy

    Directory of Open Access Journals (Sweden)

    Grujić Aleksandar

    2005-01-01

    Full Text Available As a part of these experimental investigations of melt-spun Nd-Fe-B alloy with Nd rich content in relation to Nd2Fe14B prepared by rapid quenching process for optimally selected cooling rate and heat treatment, the influence of the chosen chemical composition on magnetic properties was observed. The results of X-ray diffraction, Mössbauer spectroscopy phase analysis and magnetic measurement of investigated melt-spun Nd14.5Fe78.5B7 alloy are presented to bring some new information concerning the relation between their structure and magnetic properties.

  17. Mechanochemical synthesis of Fe-S materials

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Larsen, R.K.; Lin, R.

    1998-01-01

    Powder mixtures of metallic iron and sulfur have been milled in a high-energy planetary ball mill and the formation of iron sulfides has been studied by x-ray diffraction, Mossbauer spectroscopy, and scanning electron microscopy. For Fe:S ratios of 1:1 and 1:2 the final products are FeS with the ......S with the modified NiAs structure and FeS2 (pyrite), respectively. No other iron sulfides were formed for any of the Fe:S ratios studied. The FeS phase has been tested as an electrode material in lithium batteries....

  18. Body parts

    Science.gov (United States)

    Ayiter, Elif

    2010-01-01

    In this project, the artist wishes to examine corporeality in the virtual realm, through the usage of the (non)-physical body of the avatar. An art installation created in the virtual world of Second Life, which is meant to be accessed with site specific avatars, will provide the creative platform whereby this investigation is undertaken. Thus, "body parts" seeks to challenge the residents of virtual environments into connecting with the virtual manifestations, i.e., avatars of others in an emotionally expressive/intimate manner.

  19. Rapid degradation of dyes in water by magnetic Fe(0)/Fe3O4/graphene composites.

    Science.gov (United States)

    Chong, Shan; Zhang, Guangming; Tian, Huifang; Zhao, He

    2016-06-01

    Magnetic Fe(0)/Fe3O4/graphene has been successfully synthesized by a one-step reduction method and investigated in rapid degradation of dyes in this work. The material was characterized by N2 sorption-desorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), vibrating-sample magnetometer (VSM) measurements and X-ray photoelectron spectroscopy (XPS). The results indicated that Fe(0)/Fe3O4/graphene had a layered structure with Fe crystals highly dispersed in the interlayers of graphene, which could enhance the mass transfer process between Fe(0)/Fe3O4/graphene and pollutants. Fe(0)/Fe3O4/graphene exhibited ferromagnetism and could be easily separated and re-dispersed for reuse in water. Typical dyes, such as Methyl Orange, Methylene Blue and Crystal Violet, could be decolorized by Fe(0)/Fe3O4/graphene rapidly. After 20min, the decolorization efficiencies of methyl orange, methylene blue and crystal violet were 94.78%, 91.60% and 89.07%, respectively. The reaction mechanism of Fe(0)/Fe3O4/graphene with dyes mainly included adsorption and enhanced reduction by the composite. Thus, Fe(0)/Fe3O4/graphene prepared by the one-step reduction method has excellent performance in removal of dyes in water. Copyright © 2016. Published by Elsevier B.V.

  20. FE Prediction of Hysteretic Component of Rubber Friction

    Directory of Open Access Journals (Sweden)

    L. Pálfi

    2012-01-01

    Full Text Available The hysteretic part of the friction coefficient for rubber sliding on an ideal rigid, rough surface has been investigated by FE technique. The FE models were created by using two different FE softwares, ABAQUS and MSC.MARC. The surface roughness has been considered by using two different sine waves having a wavelength of 100 μm and 11.11 μm, as well as their superposition. Parameters of the viscoelastic material models of the rubber were gained, firstly from a fit to the measured storage modulus, secondly from a fit to the measured loss factor master curve of the rubber. The effect of viscoelastic material models, comparing 10-term and 40-term generalized Maxwell models was also considered together with the temperature effect between −50 and 150°C. According to the results, both postprocessing methods, namely, the reaction force and the energy-based approach, show very similar coefficients of friction. The 40-term Maxwell model fitted to both the storage modulus and loss factor curve provided the most realistic results. The tendency of the FE results has been explained by semianalytical theory.

  1. Magnetostriction of FM/TbFe (FM=Fe, Py-permalloy, FeCo) coupled bilayer

    International Nuclear Information System (INIS)

    Li Jianjun

    2012-01-01

    Choosing TbFe as the magnetostrictive layer and using soft ferromagnetic materials (FM=Fe, Py-permalloy, FeCo) as the inductive layer, we report the magnetization and magnetostriction of the S/FM(10 nm)/TbFe(10 nm) coupled bilayer (S-glass substrate). The magnetization of the coupled bilayer is attributed to the soft ferromagnetic layer and there is no contribution from the TbFe layer. Interfacial exchange interaction plays an important role in determining the magnetostriction of the coupled bilayer. The effect coming from the deposition Argon pressure on the magnetostriction of the coupled bilayer was also investigated. - Highlights: ► Choosing TbFe as magnetostrictive layer and with soft ferromagnetic material (FM=Fe, Py-permalloy, FeCo) as inductive layer. ► We report the magnetization and magnetostriction of the S/FM(10 nm)/TbFe(10 nm) coupled bilayer (S-glass substrate). ► The magnetization of coupled bilayer is attributed to soft ferromagnetic layer and there is no contribution from TbFe layer. ► Interfacial exchange interaction plays an important role in determining the magnetostriction of the coupled bilayer.

  2. Dissolved Fe in the Deep and Upper Arctic Ocean With a Focus on Fe Limitation in the Nansen Basin

    Directory of Open Access Journals (Sweden)

    Micha J. A. Rijkenberg

    2018-03-01

    Full Text Available Global warming resulting from the release of anthropogenic carbon dioxide is rapidly changing the Arctic Ocean. Over the last decade sea ice declined in extent and thickness. As a result, improved light availability has increased Arctic net primary production, including in under-ice phytoplankton blooms. During the GEOTRACES cruise PS94 in the summer of 2015 we measured dissolved iron (DFe, nitrate and phosphate throughout the central part of the Eurasian Arctic. In the deeper waters concentrations of DFe were higher, which we relate to resuspension on the continental slope in the Nansen Basin and hydrothermal activity at the Gakkel Ridge. The main source of DFe in the surface was the Trans Polar Drift (TPD, resulting in concentrations up to 4.42 nM. Nevertheless, using nutrient ratios we show that a large under-ice bloom in the Nansen basin was limited by Fe. Fe limitation potentially prevented up to 54% of the available nitrate and nitrite from being used for primary production. In the Barents Sea, Fe is expected to be the first nutrient to be depleted as well. Changes in the Arctic biogeochemical cycle of Fe due to retreating ice may therefore have large consequences for primary production, the Arctic ecosystem and the subsequent drawdown of carbon dioxide.

  3. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Luping [Key Laboratory of Magnetic Materials and Devices & Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Zhan, Qingfeng, E-mail: zhanqf@nimte.ac.cn, E-mail: runweili@nimte.ac.cn; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Li, Run-Wei, E-mail: zhanqf@nimte.ac.cn, E-mail: runweili@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices & Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Tan, Xiaohua [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China)

    2016-03-15

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  4. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    International Nuclear Information System (INIS)

    Liu, Luping; Zhan, Qingfeng; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Li, Run-Wei; Tan, Xiaohua

    2016-01-01

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  5. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    Science.gov (United States)

    Liu, Luping; Zhan, Qingfeng; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Tan, Xiaohua; Li, Run-Wei

    2016-03-01

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  6. Variations of moisture and organics in activated sludge during Fe0/S2O82-conditioning-horizontal electro-dewatering process.

    Science.gov (United States)

    Li, Haoxuan; Wang, Yili; Zheng, Huaili

    2018-02-01

    The feasibility of using Fe 0 /S 2 O 8 2- conditioning (zero valence iron (ZVI)/persulfate (ps)) integrated with horizontal electro-dewatering (HED) to improve the dewaterability of activated sludge (AS) was evaluated. The removal and migration of free and bound water in the ZVI/ps-HED process were determined, along with the organic matter migration between the solid and liquid phases of AS biosolids. Results showed that the optimum conditioning dosages were determined as 0.35 g ZVI/g dry solids (DS) and 0.15 g ps/g DS on the basis of capillary suction time variation. The lowest final water content (WC) of 83.67% in AS occurred after the HED treatment at 40 V and 120 min as determined using the response surface methodology. Despite the disruption of AS flocs and microbial cells through SO 4 -· oxidation during the ZVI/ps conditioning, the particle size and mass fractal dimension of the AS flocs remained relatively stable as the zeta potential increased from -8.5 mV to -4.6 mV. The coagulation of Fe 3+ from the oxidation of Fe 2+ by ps contributed to the relatively stable condition, which favored the subsequent momentum of the electroosmotic flow. Moreover, the ZVI/ps conditioning decreased the bound water content (BWC, from 1.83 g/g DS to 1.38 g/g DS) and increased the free water content (FWC, from 60.27 g/g DS to 60.91 g/g DS), indicating a transformation from free water to bound water. After the ZVI/ps-HED process, the FWC and BWC were removed significantly with ratios of 96.32% and 79.78%, respectively. Along with water removal through the ZVI/ps-HED process, the organic matter in the supernatant/filtrate initially increased and further rose at the HED stage. The analysis of the extracellular polymeric substance (EPS) content showed that the proteins (PNs) and polysaccharides (PSs) at the liquid and solid phases decreased due to oxidative degradation. Furthermore, the ZVI/ps stage significantly reduced the PNs content of slime to 57.22%, the PSs

  7. The influence of P solutes on an irradiated α-Fe matrix

    International Nuclear Information System (INIS)

    Hurchand, H.; Kenny, S.D.; Sanz-Navarro, C.F.; Smith, R.; Flewitt, P.E.J.

    2005-01-01

    Atomistic simulations of collision cascades in a Fe-0.04at.%P matrix and a pure Fe matrix are compared to investigate the interaction of the phosphorus atoms with the radiation. The simulations were performed for a primary knock-on atom having an energy in the range 1-16 keV. It is observed that the P atom in the Fe matrix does not increase significantly the damage induced to the lattice post irradiation. The density of vacancies and the morphology of the clusters formed in the Fe-0.04at.%P system are indistinguishable from residual defects produced in a pure irradiated Fe matrix. There are two mechanisms by which the Fe interstitials interact with the P atoms. The first occurs when a P atom is dislodged from its substitutional position by a recoil atom and combines with an Fe interstitial to form a mixed dumbbell. The second is one in which the Fe interstitial is attracted to a substitutional P atom due to the lattice strain region in the vicinity of the P atom. In this case the P atom acts as an attractive centre for interstitial Fe atoms and stabilises them into Fe-P nano-clusters. Nearly 35% of the atoms which are ejected from the core region of the cascade during the ballistic phase form such solute-defect clusters which remain pinned over the period of several hundred picoseconds. Finally, the radiation induced mobility of the P atom is reported. Substitutional P atoms whether isolated or as part of the larger defect clusters have a high energy barrier for diffusion but the P atoms displaced from substitutional sites can diffuse through the lattice by hopping between dumbbell and tetrahedral sites

  8. Buena fe subjetiva y buena fe objetiva. Equívocos a los que conduce la falta de claridad en la distinción de tales conceptos

    Directory of Open Access Journals (Sweden)

    Martha Lucía Neme Villarreal

    2009-12-01

    Full Text Available El presente escrito tiene por objeto dejar en evidencia la confusión que en cierto sector de la jurisprudencia colombiana existe entre el concepto de buena fe objetiva y el concepto de buena fe subjetiva, que ha trascendido, por demás, a una parte de la doctrina y la legislación (C. Co., art. 863, pero, sobre todo, busca advertir sobre los graves equívocos a los que dicha confusión conduce, entre los que se cuentan: asumir que la buena objetiva comprende tanto una buena fe exenta de culpa como una buena fe en la que la diligencia no resulta exigible; pretender que la regla que prohíbe el ir contra los actos propios está regida por la buena fe subjetiva y que es una manifestación de la teoría de la apariencia; pretender proteger a nombre del principio de buena fe la representación mental del deudor que cree haber cumplido, desconociendo la exigencia de la buena fe objetiva que impone desplegar un comportamiento efectivo; y apreciar de manera errónea los alcances de la presunción de buena fe; equívocos que llevan a plantear la necesidad de retomar los senderos del derecho romano, en el que el concepto originario de buena fe estuvo siempre atado al deber de comportamiento probo y leal frente a la otra parte en el contrato, es decir, a lo que hoy entendemos como buena fe objetiva y donde la exigencia de buena fe en la posesión del comprador (convicción o creencia debió ser una utilización particular de la bona fides contractual adaptada en función de la problemática posesoria, que luego se extendería a otras situaciones que se engloban hoy bajo el nombre de la teoría de la apariencia.

  9. 15 CFR Supplement 1 to Part 732 - Decision Tree

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Decision Tree 1 Supplement 1 to Part 732 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade (Continued) BUREAU... THE EAR Pt. 732, Supp. 1 Supplement 1 to Part 732—Decision Tree ER06FE04.000 ...

  10. Effect of Iron Fe (II and Fe (III in a Binary System Evaluated Bioluminescent Method

    Directory of Open Access Journals (Sweden)

    Elena Sorokina

    2013-01-01

    Full Text Available The effect of iron ions Fe2+ and Fe3+ on the bioluminescent recombinant strain of Escherichia coli in a single-component and binary system. Found that for the bacteria E. coli Fe3+ ions are more toxic than Fe2+. Under the combined effect of iron toxicity increases, the percentage of luminescence quenching increases, but the value is much less than the sum of the indicator for the Fe2+ and Fe3+. The biological effect of insertion of iron is not proportional to their content in the mixture.

  11. Low Temperature Transformation of Fe-Pd and Fe-Pt Invar Alloys

    OpenAIRE

    Masaaki, Matsui; Kengo, Adachi; Hidefumi, Asano; Department of Iron and Steel Engineering, Faculty of Engineering Nagoya University; Department of Iron and Steel Engineering, Faculty of Engineering Nagoya University; Department of Iron and Steel Engineering, Faculty of Engineering Nagoya University

    1981-01-01

    Low temperature structures of Fe-Pd and Fe-Pt alloys in the Invar region have been determined by means of low temperature X-ray diffraction experiment. The phase diagrams are obtained. A new fct phase is found in the ordered and disordered Fe-Pt and the disordered Fe-Pd systems. An effect of the degree of order for Fe_3Pt to the structural transformations are examined. The lattice instability of Fe-based fcc Invar alloys are discussed from the low temperature structures with the lattice softe...

  12. (segunda parte

    Directory of Open Access Journals (Sweden)

    José María Oliva-Martínez

    2004-01-01

    Full Text Available Este trabajo es la continuación de otro anterior (Oliva, 2004, ambos dedicados al estudio de la importancia del pensamiento analógico en la construcción histórica de la noción de fuerza gravitatoria y del modelo de Sistema Solar. En aquella ocasión analizamos dicho papel durante el período comprendido desde las antiguas civilizaciones hasta llegar a la revolución copernicana con científicos como Copérnico, Gilbert, Kepler o el propio Galileo. En esta segunda parte, se continúa con algunos de los razonamientos analógicos proporcionados desde la vertiente mecanicista, capitaneada por Descartes y desde la tradición subsiguiente que se desarrolló en línea con la utilización del método de la analogía como criterio argumentativo (Huyghens, Hooke, Bernoulli, etc.. Dedicamos asimismo un capítulo aparte a la figura de Newton, quien continúa con dicha tradición en su intento de explicar la naturaleza de la gravitación. Finalmente se procede, a modo de síntesis, a realizar una clasificación de distintos tipos de razonamientos analógicos aportados en el desarrollo histórico en torno a estos temas, estudiando el papel científico y divulgativo de cada uno

  13. La fe de Jesús, fundamento de la fe en Cristo

    Directory of Open Access Journals (Sweden)

    Jorge Costadoat

    2007-01-01

    Full Text Available Lo que la Iglesia cree de Cristo, hunde sus raíces en el modo que tuvo Jesús de creer en Dios. Pero, a la vez, la fe de la Iglesia permite inferir cómo ha podido ser la experiencia espiritual de Jesús. Esta referencia recíproca entre Cristo y la Iglesia invita a indagar en los en los fundamentos antropológicos y teológicos de la fe "de" Jesús, en las dificultades y posibilidades que Jesús ha podido tener para creer en su Padre, puesto que así él enseña por qué y cómo han de creer también los hombres. Por esta vía descubrimos que el Padre, al resucitar a Jesús, triunfa sobre el Mysterium iniquitatis y, contra toda sospecha de indiferencia ante el sufrimiento humano que pudiera recaer sobre Él mismo, da pruebas de ser un Dios que merece fe. El Padre merece fe, pero no la merecería si Él no "creyera" también en la humanidad como "creyó" en su Hijo Jesús. Es el amor del Padre que en última instancia produce confianza en Él y entre los hombresWhat the Church believes of Christ finds its roots in Jesus' manner of believing in God. However, at the same time, the faith of the Church allows one to infer how the spiritual experience of Jesus came about. This reciprocal reference between Christ and the Church invites one to investigate the anthropological and theological tenets of the faith "of" Jesus, in the difficulties and possibilities that Jesus could have had in order to believe in his Father, given that he teaches us accordingly why and how to believe as well. In this way we discover that the Father, upon raising up Jesus, triumphs over the Mysterium iniquitatis and, against every suspicion of a possible indifference on the God's part in the face of human suffering, gives proof of being a God who deserves faith. The Father deserves faith, but he wouldn't if He did not also "believe" in humanity, just as He "believed" in his Son, Jesus. It is the love of the Father that, in the final analysis, brings about trust in Him and

  14. Effects of Fe fine powders doping on hot deformed NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Min, E-mail: linm@nimte.ac.cn [Ningbo Institute of Material Technology & Engineering Chinese Academy of Science, Ningbo 315201 (China); Wang, Huijie [Ningbo Jinji Strong Magnetic Material Company, Ningbo 315041 (China); Zheng, Jingwu [Zhejiang University of Technology, Hangzhou 310014 (China); Yan, Aru [Ningbo Institute of Material Technology & Engineering Chinese Academy of Science, Ningbo 315201 (China)

    2015-04-01

    The composite NdFeB magnets with blending melt-spun flakes and Fe fine powders were prepared by the hot-pressed and hot-deformed route. Characterizations of the hot-deformed NdFeB magnets affected by the doped Fe powders were tested. The doped Fe powders decrease the hot-deformed pressure when the strain is between 15 and 50%. XRD patterns show that the doped Fe powders have little influence on the c-axis alignment of hot-deformed NdFeB magnets in the press direction. The B{sub r} and the (BH){sub max} get improved when the doped Fe powders are less than 3 wt%. The doped Fe of hot-deformed NdFeB magnets exists in the elongated state and the spherical state surrounded by the Nd-rich phase. With the Fe fraction increasing, the potential of magnet moves to the positive direction and the diameter of the Nyquist arc becomes larger, which indicate that the corrosion resistance improved effectively. The bending strength was enhanced by the elongated α-Fe phase embedded in the matrix 2:14:1 phase. - Highlights: • The doped Fe powders have little influence on the c-axis alignment of magnets. • The elongated Fe powders are more than the spherical Fe powders in the magnets. • The corrosion resistance is improved effectively with the increasing Fe fraction. • The bending strength is enhanced by the elongated α-Fe phase embedded in the matrix.

  15. Effect of Fe state on electrocatalytic activity of Pd-Fe/C catalyst for oxygen reduction

    International Nuclear Information System (INIS)

    Tang Yawen; Cao Shuang; Chen Yu; Lu Tianhong; Zhou Yiming; Lu Lude; Bao Jianchun

    2010-01-01

    The carbon-supported Pd-Fe catalyst (Pd-Fe/C) is prepared in the H 2 O/tetrahydrofuran (THF) mixture solvent under the low temperature. The homemade Pd-Fe/C catalyst contains two forms of iron species, alloying and non-alloying Fe. The alloying Fe species is hardly dissolved in 0.5 M H 2 SO 4 solution, while the non-alloying Fe species is easily dissolved in 0.5 M H 2 SO 4 solution. The electrochemical measurements show the electrocatalytic activity of the Pd-Fe/C catalyst with the acid treatment for the oxygen reduction is higher than that of the Pd-Fe/C catalyst without the acid treatment, illustrating that the non-alloying Fe species suppresses the electrocatalytic activity of the Pd-Fe/C catalyst. In contrast, the alloying Fe species promotes the electrocatalytic activity of the Pd-Fe/C catalyst for the oxygen reduction, which is likely attributed to the change of the electron structure of Pd atom and/or bond length of Pd-Pd in the Pd-Fe/C catalyst.

  16. Part 5: Experimental periods using a ferrous-ferric chloride blend

    African Journals Online (AJOL)

    drinie

    anaerobic (AN) or first aerobic (AE1) zone of the test unit. For consistency with earlier work (Parts 3 and 4), a small amount of acid was added to the Fe solution before dilution with tap water to preclude iron hydroxide precipitation. For this reason, 10 mmol/d of HCl was added to the diluted solution of FeCl2/FeCl3 dosed to.

  17. A double Fe-Ti oxide and Fe-sulphide liquid immiscibility in the Itsindro Gabbro Complex, Madagascar

    Science.gov (United States)

    Augé, Thierry; Bailly, Laurent; Roig, Jean-Yves

    2017-11-01

    main mineralized zone is located in the upper part of this unit, about 70 m above this discontinuity. The highly differentiated Fe-Ti-P facies of the Lanjanina series in the Itsindro Gabbro Complex have been interpreted as corresponding to the Fe-Ti-P rich, Si-poor member remaining after an immiscible segregation of an evolved mafic magma. The granite dykes and the overlying granite unit represent the second, Si-rich member of the immiscibility process. The presence of large amounts of sulphide is attributed to sulphur contamination of the Fe-Ti-rich liquid. Fe-Ti oxides will tend to crystallize on the sulphide droplets and the accumulation of dense Fe-sulphides (liquid) and associated Fe-Ti oxides (solid) will result in this complex and unusual association taking the form of a net texture.

  18. The effects of local correlations on the electronic structure of FeSe

    Science.gov (United States)

    Watson, Matthew; Kim, Timur; Haghighirad, Amir; Coldea, Amalia

    FeSe is structurally the simplest of Fe-based superconductors, but its complex and unique properties pose important theoretical questions. One important aspect of the physics of FeSe is the understanding of the strength and effects of electronic correlations. In order to explore this, we have performed angle-resolved photo-emission spectroscopy (ARPES) measurements on high quality bulk single crystals of FeSe over a wide range of binding energies, in different scattering geometries and with varying incident photon energies, analysing the quasiparticle renormalisations, scattering rates and degree of coherence. We find that FeSe exhibits moderately strong, orbital-dependent correlation effects which are understood to arise primarily due to local electron-electron interactions on the Fe sites. We conclude that electronic correlations constitute a key ingredient in understanding the electronic structure of FeSe. Part of this work was supported by EPSRC, UK (EP/I004475/1, EP/I017836/1). We thank Diamond Light Source for access to Beamline I05.

  19. Magnetic excitations in Ho2Co17 and Ho2Fe17

    International Nuclear Information System (INIS)

    Clausen, K.N.

    1981-01-01

    The low energy part ( 2 Co 17 and Ho 2 Fe 17 have been measured along the three high symmetry directions at a temperature of 4.2 K, using the inelastic neutron scattering technique. The resulting magnon dispersion relations have been interpreted using linear spin wave theory with a Hamiltonian including single ion crystal field anisotropy and isotropic exchange between spatially well localized spins. The R 2 T 17 structure contains two different Ho sites, with the same point symmetry, and from the spin wave results it was concluded that the crystal field anisotropy of the two Ho sites in both Ho 2 Co 17 and Ho 2 Fe 17 were identical. The deduced crystal field parameters for Ho 2 Fe 17 were slightly larger than for Ho 2 Co 17 , and the parameters were of the same order of magnitude as for pure Ho. For Ho 2 Fe 17 the Fe-Fe exchange was found to be anisotropic, and for both compounds the magnetic ordering temperatures of 1178 K for Ho 2 Co 17 and 335 K for Ho 2 Fe 17 were determined by the strong positive 3d-3d exchange. (Auth.)

  20. Suppression of superconductivity and structural phase transitions under pressure in tetragonal FeS.

    Science.gov (United States)

    Lai, Xiaofang; Liu, Ying; Lü, Xujie; Zhang, Sijia; Bu, Kejun; Jin, Changqing; Zhang, Hui; Lin, Jianhua; Huang, Fuqiang

    2016-08-08

    Pressure is a powerful tool to study iron-based superconductors. Here, we report systematic high-pressure transport and structural characterizations of the newly discovered superconductor FeS. It is found that superconductor FeS (tetragonal) partly transforms to a hexagonal structure at 0.4 GPa, and then completely transforms to an orthorhombic phase at 7.4 GPa and finally to a monoclinic phase above 9.0 GPa. The superconducting transition temperature of tetragonal FeS was gradually depressed by pressure, different from the case in tetragonal FeSe. With pressure increasing, the S-Fe-S angles only slightly change but the anion height deviates farther from 1.38 Å. This change of anion height, together with the structural instability under pressure, should be closely related to the suppression of superconductivity. We also observed an anomalous metal-semiconductor transition at 6.0 GPa and an unusual increased resistance with further compression above 9.6 GPa. The former can be ascribed to the tetragonal-orthorhombic structural phase transition, and the latter to the electronic structure changes of the high-pressure monoclinic phase. Finally, a phase diagram of tetragonal FeS as functions of pressure and temperature was mapped out for the first time, which will shed new light on understanding of the structure and physics of the superconducting FeS.

  1. Effects of energetic ion irradiation on the magnetism of Fe-Ni Invar alloy

    Science.gov (United States)

    Matsushita, M.; Akamatsu, S.; Matsushima, Y.; Iwase, A.

    2013-11-01

    The magnetic properties of Fe-Ni Invar alloys are significantly affected by ion irradiation. Au3+ with the energy of 16 MeV irradiation effects on the magnetism of Fe66Ni34 have been reported in this paper. Considering from the temperature variations of AC susceptibility of irradiated Fe66Ni34, Curie temperature of a part of sample increase with increasing incident ion fluence, and the magnetization of irradiated Fe66Ni34 is also increase. The FCC structure of Fe66Ni34 is not changed by ion irradiation; however peaks become broader with increasing ion fluence. It means that lattice fluctuations are generated owing to ion irradiation. However it cannot be considered that lattice fluctuations observed X-ray diffraction measurements are enough to increase the Curie temperature observed in AC susceptibility measurements. Then, we suggest as the considerable origin of increasing TC, atomic mixing effects owing to the ion irradiation. It might change the chemical ordering reported in the diffused scattering, such as Fe-Fe coupling.

  2. Elastic softening in Fe7C3 with implications for Earth's deep carbon reservoirs

    Science.gov (United States)

    Liu, Jiachao; Li, Jie; Ikuta, Daijo

    2016-03-01

    Iron carbide Fe7C3 has recently emerged as a potential host of reduced carbon in Earth's mantle and a candidate component of the inner core, but the equation of state of Fe7C3 is still uncertain, partly because the nature of pressure-induced magnetic transitions in Fe7C3 and their elastic effects remain controversial. Here we report the compression curve of hexagonal Fe7C3 in neon medium with dense pressure sampling and in comparison with pure iron in the same loading. The results revealed elastic softening between 7 GPa and 20 GPa, which can be attributed to noncollinear alignment of spin moments in a state between the ferromagnetic and paramagnetic phases, as expected for Invar-type alloys. The volume reduction associated with the softening would enhance the stability of Fe7C3 in the deeper part of the upper mantle and transition zone. As a result of subsequent spin crossover at higher pressures, Fe7C3 at inner core conditions likely occurs as the nonmagnetic phase, which remains a candidate for the major component of the Earth's central sphere.

  3. Biomimetic peptide-based models of [FeFe]-hydrogenases: utilization of phosphine-containing peptides

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Souvik [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA; Nguyen, Thuy-Ai D. [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA; Gan, Lu [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA; Jones, Anne K. [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA

    2015-01-01

    Peptide based models for [FeFe]-hydrogenase were synthesized utilizing unnatural phosphine-amino acids and their electrocatalytic properties were investigated in mixed aqueous-organic solvents.

  4. Synthesis of high magnetization Fe and FeCo nanoparticles by high temperature chemical reduction

    International Nuclear Information System (INIS)

    Kandapallil, Binil; Colborn, Robert E.; Bonitatibus, Peter J.; Johnson, Francis

    2015-01-01

    Fe and FeCo ferromagnetic nanoparticles in the 5–10 nm size regimes featuring high magnetization were synthesized using a modified chemical reduction method. The structure and morphology of these nanoparticles were confirmed by XRD and TEM analysis. These small, monodisperse and phase pure nanoparticles exhibited magnetic saturation of 210 emu/g (Fe) and 220 emu/g (Fe+Co) for Fe and FeCo nanoparticles respectively. The magnetization was found to be dependent on the temperature at which the reducing agent was introduced. - Highlights: • A high temperature synthetic route for Fe and FeCo nanoparticles is developed. • These 5–10 nm nanoparticles exhibit high quality magnetic properties. • The saturation magnetization values were dependent on the reduction temperature. • This chemical reduction route has been demonstrated to be scalable in the gram scale

  5. Growth kinetics of thin oxide layers; oxidation of Fe and Fe-N phases at room temperature

    NARCIS (Netherlands)

    Kooi, Bart J.; Somers, Marcel A.J.; Mittemeijer, Eric J.

    1996-01-01

    The evolution of iron-oxide layers at room temperature on pure polycrystalline α-Fe and on the Fe-N phases γ-Fe[N], γ'-Fe4N1-x and ε-Fe2N1-z was followed in situ with Auger-Electron Spectroscopy. The observed oxidation kinetics of the Fe and Fe-N phases were interpreted using a model considering

  6. Behaviour of Fe4O5-Mg2Fe2O5 solid solutions and their relation to coexisting Mg-Fe silicates and oxide phases

    Science.gov (United States)

    Uenver-Thiele, Laura; Woodland, Alan B.; Miyajima, Nobuyoshi; Ballaran, Tiziana Boffa; Frost, Daniel J.

    2018-03-01

    Experiments at high pressures and temperatures were carried out (1) to investigate the crystal-chemical behaviour of Fe4O5-Mg2Fe2O5 solid solutions and (2) to explore the phase relations involving (Mg,Fe)2Fe2O5 (denoted as O5-phase) and Mg-Fe silicates. Multi-anvil experiments were performed at 11-20 GPa and 1100-1600 °C using different starting compositions including two that were Si-bearing. In Si-free experiments the O5-phase coexists with Fe2O3, hp-(Mg,Fe)Fe2O4, (Mg,Fe)3Fe4O9 or an unquenchable phase of different stoichiometry. Si-bearing experiments yielded phase assemblages consisting of the O5-phase together with olivine, wadsleyite or ringwoodite, majoritic garnet or Fe3+-bearing phase B. However, (Mg,Fe)2Fe2O5 does not incorporate Si. Electron microprobe analyses revealed that phase B incorporates significant amounts of Fe2+ and Fe3+ (at least 1.0 cations Fe per formula unit). Fe-L2,3-edge energy-loss near-edge structure spectra confirm the presence of ferric iron [Fe3+/Fetot = 0.41(4)] and indicate substitution according to the following charge-balanced exchange: [4]Si4+ + [6]Mg2+ = 2Fe3+. The ability to accommodate Fe2+ and Fe3+ makes this potential "water-storing" mineral interesting since such substitutions should enlarge its stability field. The thermodynamic properties of Mg2Fe2O5 have been refined, yielding H°1bar,298 = - 1981.5 kJ mol- 1. Solid solution is complete across the Fe4O5-Mg2Fe2O5 binary. Molar volume decreases essentially linearly with increasing Mg content, consistent with ideal mixing behaviour. The partitioning of Mg and Fe2+ with silicates indicates that (Mg,Fe)2Fe2O5 has a strong preference for Fe2+. Modelling of partitioning with olivine is consistent with the O5-phase exhibiting ideal mixing behaviour. Mg-Fe2+ partitioning between (Mg,Fe)2Fe2O5 and ringwoodite or wadsleyite is influenced by the presence of Fe3+ and OH incorporation in the silicate phases.

  7. Local structures and electronic band states of α−Fe2O3 polycrystalline particles in the glazes of the HIZEN celadons produced in the Edo period of Japan, by means of X-ray absorption spectra (II Estruturas locais e estados de banda de partículas policristalinas nos esmaltes de celadons Hizen produzidos no período Edo do Japão, por meio de espectros de absorção de raios X (II

    Directory of Open Access Journals (Sweden)

    M. Hidaka

    2011-06-01

    Full Text Available HIZEN celadon glazes produced in 1630's to 1790's (Edo period, Japan have been investigated by means of X-ray absorption spectra (XAS near a Fe-K edge by using synchrotron radiation and a Mössbauer spectrum. The XAS suggest that the local structure around Fe2O3 fine powders is slightly different between the Izumiyama ceramics of mainly the Quartz-SiO2 and Ohkawachi ceramics of mainly the feldspar of (K,NaSi3O8 (Sanidine, and that the glazes of the HIZEN celadons include the Fe2O3 fine powders in the glassy state, though the X-ray diffraction patterns of the glassy celadon glazes do not show any peaks of the Fe2O3 structure. The Mössbauer spectrum suggests that the celadon glaze of Seiji (m includes only Fe3+ ions, but not Fe2+ ions. This indicates the existence of Fe2O3 in the celadon glaze. It is interpreted that the colored brightness of the HIZEN celadons is induced by the structural properties of the used raw celadon ceramics and the other transition-metal ions of Cr, Cu, Zn in the celadon glazes, but not by the chemical reaction from Fe2O3 to FeO under the deoxidizing thermal treatment at higher temperature in a kiln.Esmaltes de celadon Hizen produzidos dos anos 1630 a 1790 (período Edo, Japão foram investigados por meio de espectros de absorção de raios X (XAS próximos da linha Fe-K usando radiação síncrotron e espectro Mossbaues. Os resultados de XAS sugerem que a estrutura local em pós finos de Fe2O3 é levemente diferente entre as cerâmicas Izumiyama principalmente o quartzo e cerâmicas Ohkawachi principalmente do feldspato (K,NaSi3O8 (Sanidine, e que os esmaltes dos celadons Hizen incluem finos pós de Fe2O3 no estado vítreo, embora os difratogramas de raios X dos esmaltes celadon não mostrem picos da estrutura do Fe2O3. O espectro Mossbauer sugere que os esmaltes celadon de Seiji (m incluem somente íons Fe3+, mas não Fe2+. Isto indica a existência de Fe2O3 no esmalte celadon. É feita a interpretação que o brilho

  8. Effect of Fe-Mn addition on microstructure and magnetic properties of NdFeB magnetic powders

    Science.gov (United States)

    Kurniawan, C.; Purba, A. S.; Setiadi, E. A.; Simbolon, S.; Warman, A.; Sebayang, P.

    2018-03-01

    In this paper, the effect of Fe-Mn alloy addition on microstructures and magnetic properties of NdFeB magnetic powders was investigated. Varied Fe-Mn compositions of 1, 5, and 10 wt% were mixed with commercial NdFeB type MQA powders for 15 minutes using shaker mill. The characterizations were performed by powder density, PSA, XRD, SEM, and VSM. The Fe-Mn addition increased the powder density of NdFeB/Fe-Mn powders. On the other side, particle size distribution slightly decreased as the Fe-Mn composition increases. Magnetic properties of NdFeB/Fe-Mn powders changed with the increasing of Fe-Mn content. SEM analysis showed the particle size of NdFeB/Fe-Mn powder was smaller as the Fe-Mn composition increases. It showed that NdFeB/Fe-Mn particles have different size and shape for NdFeB and Fe-Mn particles separately. The optimum magnetic properties of NdFeB/Fe-Mn powder was achieved on the 5 wt% Fe-Mn composition with remanence M r = 49.45 emu/g, coercivity H c = 2.201 kOe, and energy product, BH max = 2.15 MGOe.

  9. Cataloguing Emission Line Spectra from Fe VII-Fe XXIV in the Extreme Ultraviolet

    Science.gov (United States)

    Lepson, J. K.; Beiersdorfer, P.; Brown, G. V.; Kahn, D. A.; Liedahl, D. A.; Mauche, C. W.; Utter, S. B.

    2000-01-01

    Detailed laboratory astrophysics measurements are, in progress to produce spectral tables for the Fe VII Fe XXIV line emission in the EUV wavelength band. Results for Fe XIII are presented that update line lists used in the Chandra Emission Line Project.

  10. Properties of porous FeAlOy/FeAlx ceramic matrix composite ...

    Indian Academy of Sciences (India)

    Abstract. Porous ceramic matrix composites FeAlOy/FeAlx with incorporated metal inclusions (cermets) were synthesized by pressureless method, which includes hydrothermal treatment of mechanically alloyed FeAl powder followed by calcination. Their main structural, textural and mechanical features are described.

  11. Properties of porous FeAlOy/FeAlx ceramic matrix composite ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 7. Properties of porous FeAlO/FeAl ceramic matrix composite influenced by mechanical activation of FeAl powder. V Usoltsev S Tikhov A Salanov V Sadykov G Golubkova O Lomovskii. Volume 36 Issue 7 December 2013 pp 1195-1200 ...

  12. Variation of mineral composition in different parts of taro (Colocasia esculenta) corms.

    Science.gov (United States)

    Mergedus, Andrej; Kristl, Janja; Ivancic, Anton; Sober, Andreja; Sustar, Vilma; Krizan, Tomaz; Lebot, Vincent

    2015-03-01

    Taro (Colocasia esculenta) is an important root crop in the humid tropics and a valuable source of essential mineral nutrients. In the presented study, we compared the mineral compositions of four main parts of taro corm: the upper, marginal, central and lower (basal) parts. The freeze-dried taro samples were analysed for eleven minerals (K, P, Mg, Ca, Zn, Fe, Mn, Cu, Cd, Pb and Cr). The upper part, which plays a critical role in vegetative propagation based on headsets, contained high levels of P, Mg, Zn, Fe, Mn, Cu and Cd. The central part, which is essential for human nutrition, was characterised by higher concentrations of K, P, Mg, Zn, Fe, Cu and Cd. Ca was concentrated in the lower and marginal parts. The effect of the genotype was significant for more than half of the analysed minerals (i.e., Mg, Ca, Zn, Fe, Mn). Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. A subsurface Fe-silicate weathering microbiome

    Science.gov (United States)

    Napieralski, S. A.; Buss, H. L.; Roden, E. E.

    2017-12-01

    Traditional models of microbially mediated weathering of primary Fe-bearing minerals often invoke organic ligands (e.g. siderophores) used for nutrient acquisition. However, it is well known that the oxidation of Fe(II) governs the overall rate of Fe-silicate mineral dissolution. Recent work has demonstrated the ability of lithtrophic iron oxidizing bacteria (FeOB) to grow via the oxidation of structural Fe(II) in biotite as a source of metabolic energy with evidence suggesting a direct enzymatic attack on the mineral surface. This process necessitates the involvement of dedicated outer membrane proteins that interact with insoluble mineral phases in a process known as extracellular electron transfer (EET). To investigate the potential role FeOB in a terrestrial subsurface weathering system, samples were obtained from the bedrock-saprolite interface (785 cm depth) within the Rio Icacos Watershed of the Luquillo Mountains in Puerto Rico. Prior geochemical evidence suggests the flux of Fe(II) from the weathering bedrock supports a robust lithotrophic microbial community at depth. Current work confirms the activity of microorganism in situ, with a marked increase in ATP near the bedrock-saprolite interface. Regolith recovered from the interface was used as inoculum to establish enrichment cultures with powderized Fe(II)-bearing minerals serving as the sole energy source. Monitoring of the Fe(II)/Fe(total) ratio and ATP generation suggests growth of microorganisms coupled to the oxidation of mineral bound Fe(II). Analysis of 16S rRNA gene and shotgun metagenomic libraries from in situ and enrichment culture samples lends further support to FeOB involvement in the weathering process. Multiple metagenomic bins related to known FeOB, including Betaproteobacteria genera, contain homologs to model EET systems, including Cyc2 and MtoAB. Our approach combining geochemistry and metagenomics with ongoing microbiological and genomic characterization of novel isolates obtained

  14. Exchange biased FeNi/FeMn bilayers with coercivity and switching field enhanced by FeMn surface oxidation

    Directory of Open Access Journals (Sweden)

    A. V. Svalov

    2013-09-01

    Full Text Available FeNi/FeMn bilayers were grown in a magnetic field and subjected to heat treatments at temperatures of 50 to 350 °C in vacuum or in a gas mixture containing oxygen. In the as-deposited state, the hysteresis loop of 30 nm FeNi layer was shifted. Low temperature annealing leads to a decrease of the exchange bias field. Heat treatments at higher temperatures in gas mixture result in partial oxidation of 20 nm thick FeMn layer leading to a nonlinear dependence of coercivity and a switching field of FeNi layer on annealing temperature. The maximum of coercivity and switching field were observed after annealing at 300 °C.

  15. Interface structures in FePt/Fe3Pt hard-soft exchange-coupled magnetic nanocomposites

    International Nuclear Information System (INIS)

    Li Jing; Wang Zhonglin; Zeng Hao; Sun Shouheng; Ping Liu, J.

    2003-01-01

    Self-assembly of FePt and Fe 3 O 4 nanoparticles of different sizes led to various FePt-Fe 3 O 4 nanocomposites. Annealing the composite under reducing atmosphere at 650 and 700 deg. C induced magnetically hard FePt phase and magnetically soft Fe 3 Pt phase. The FePt and Fe 3 Pt phases were either linked by a common interface or coexisted within one grain as domains with sizes <10 nm. This ensures the effective exchange coupling of magnetically hard and soft phases. High-resolution transmission electron microscopy studies provide detailed structural characterization for the FePt based nanocomposites

  16. Cysteine as a ligand platform in the biosynthesis of the FeFe hydrogenase H cluster.

    Science.gov (United States)

    Suess, Daniel L M; Bürstel, Ingmar; De La Paz, Liliana; Kuchenreuther, Jon M; Pham, Cindy C; Cramer, Stephen P; Swartz, James R; Britt, R David

    2015-09-15

    Hydrogenases catalyze the redox interconversion of protons and H2, an important reaction for a number of metabolic processes and for solar fuel production. In FeFe hydrogenases, catalysis occurs at the H cluster, a metallocofactor comprising a [4Fe-4S]H subcluster coupled to a [2Fe]H subcluster bound by CO, CN(-), and azadithiolate ligands. The [2Fe]H subcluster is assembled by the maturases HydE, HydF, and HydG. HydG is a member of the radical S-adenosyl-L-methionine family of enzymes that transforms Fe and L-tyrosine into an [Fe(CO)2(CN)] synthon that is incorporated into the H cluster. Although it is thought that the site of synthon formation in HydG is the "dangler" Fe of a [5Fe] cluster, many mechanistic aspects of this chemistry remain unresolved including the full ligand set of the synthon, how the dangler Fe initially binds to HydG, and how the synthon is released at the end of the reaction. To address these questions, we herein show that L-cysteine (Cys) binds the auxiliary [4Fe-4S] cluster of HydG and further chelates the dangler Fe. We also demonstrate that a [4Fe-4S]aux[CN] species is generated during HydG catalysis, a process that entails the loss of Cys and the [Fe(CO)2(CN)] fragment; on this basis, we suggest that Cys likely completes the coordination sphere of the synthon. Thus, through spectroscopic analysis of HydG before and after the synthon is formed, we conclude that Cys serves as the ligand platform on which the synthon is built and plays a role in both Fe(2+) binding and synthon release.

  17. Low-valent iron: an Fe(I) ate compound as a building block for a linear trinuclear Fe cluster

    NARCIS (Netherlands)

    Lichtenberg, C.; Viciu, L.; Vogt, M.; Rodríguez-Lugo, R.E.; Adelhardt, M.; Sutter, J.; Khusniyarov, M.M.; Meyer, K.; de Bruin, B.; Bill, E.; Grützmacher, H.

    2015-01-01

    A low-valent trinuclear iron complex with an unusual linear Fe(I)-Fe(II)-Fe(I) unit is presented. It is accessed in a rational approach using a salt metathesis reaction between a new anionic Fe(I) containing heterocycle and FeCl2. Its electronic structure was studied by single crystal XRD analysis,

  18. Hydroforming of flanged tubular part

    International Nuclear Information System (INIS)

    Joo, B. D.; Jang, J. H.; Choi, M. K.; Moon, Y. H.

    2010-01-01

    Tube hydroforming is the technology that utilizes hydraulic pressure to form a tube into desired shapes inside die cavities. Recently, tube hydroforming technology draws attentions of automotive industries due to its advantages such as weight reduction, increased strength, improved quality and reduced tooling cost. Hydroformed automotive parts used as structural components in vehicle body frame or subframe often have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. In this study, a tube hydroformed product which has flange has been formed at various processing conditions. To accomplish successful flange hydroforming process, thorough investigation on proper combination of process parameters such as internal hydraulic pressure and tool geometry has been performed. For the process design FE analysis was performed with Dynaform 5.5. With optimized die parting angle and circumferential expansion ratio, hydroforming experiments to form flange were performed and forming characteristics at various process conditions were analyzed. The results show that flanged parts can be successfully produced by tube hydroforming process.

  19. Nanophase Fe0 in lunar soils

    Indian Academy of Sciences (India)

    of lunar breccias (Clanton et al 1973), trains of. Fe. 0 beads splashed (?) on surfaces of agglutinates ... BSE image (74121-139) of a polished thin sec- tion of an agglutinate especially emphasizing trains of very ..... of excess Fe metal in the lunar fines by magnetic separa- tion, Mossbauer spectroscopy, and microscopic ...

  20. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    2015-05-29

    May 29, 2015 ... Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the ...

  1. Nanophase Fe 0 in lunar soils

    Indian Academy of Sciences (India)

    Grain rinds are amorphous silicates that were deposited on grains exposed at the lunar surface from transient vapors produced by hypervelocity micrometeorite impacts. Fe0 may have dissociated from Fe-compounds in a high temperature (< 3000°C) vapor phase and then condensed as globules on grain surfaces.

  2. Characterization of Fe -doped silver phosphate glasses

    Indian Academy of Sciences (India)

    tures of the glass and at lower concentration of dopant, a nanostructure is obtained. Electrical ... striking features of ion-conducting glasses is compositional .... ions. Thus the dopant metal ions form a P–O. − ....Fe3+ bond in the glass structure and Fe3+ ions serve as ionic cross-links between the non-bridging oxygen.

  3. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    Abstract. Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the dominant ...

  4. Influence of FeEDDS, FeEDTA, FeDTPA, FeEDDHA, and FeSO4 on Marigold Growth and Nutrition, and Substrate and Runoff Chemistry

    Science.gov (United States)

    Objectives of the study were to determine effects of Fe source on plant growth, plant nutrition, substrate chemistry and runoff chemistry. Iron source (FS) treatments consisted of Fe-aminopolycarboxylic acid (APCA) complexones iron ethylenediaminetetraacetic acid (FeEDTA), iron [S, S']-ethylenediam...

  5. Spectral distribution of Fe2+ photoionization cross section in InP:Fe

    International Nuclear Information System (INIS)

    Iikawa, F.

    1985-01-01

    Measurements of Fe 2+ ( 5 E) photoionization cross section in InP at 80 0 K, using constant current photoconductivity technique, were done. The spectrum presents a threshold energy of ∼ 0,65 eV due to the transition from Fe 2+ charge state, in the ground state, to Fe 3+ with an electron emission for the minimum conduction band. In the measurement of photoluminescence at ∼ 2 0 K, a wide emission of Fe complexe with the strong lattice interaction. In order to analyse the experimental data of Fe 2+ cross section in InP, a theoretical model was used. (M.C.K.) [pt

  6. Room temperature exchange bias in BiFeO3 / Co-Fe bilayers

    OpenAIRE

    Sterwerf, Christian; Meinert, Markus; Arenholz, Elke; Schmalhorst, Jan-Michael; Reiss, Günter

    2015-01-01

    Thin highly epitaxial BiFeO$_3$ films were prepared on SrTiO$_3$ (100) substrates by reactive magnetron co-sputtering. Detailed MOKE measurements on BiFeO$_3$/Co-Fe bilayers were performed to investigate the exchange bias as a function of the films thicknesses and Co-Fe stoichiometries. We found a maximum exchange bias of H$_{\\mathrm{eb}}$=92 Oe and a coercive field of H$_{\\mathrm{c}}$=89 Oe for a 12.5 nm thick BiFeO$_3$ film with a 2 nm thick Co layer. The unidirectional anisotropy is clearl...

  7. Ethylbenzene dehydrogenation over Mg3Fe0.5−xCoxAl0.5 catalysts derived from hydrotalcites: Comparison with Mg3Fe0.5−yNiyAl0.5 catalysts

    KAUST Repository

    Atanda, Luqman A.

    2011-04-01

    A series of Mg3Fe0.5-xCoxAl0.5 (x = 0-0.5) catalysts were prepared from hydrotalcite precursors and their activities in the dehydrogenation of ethylbenzene were compared with those of a series of Mg3Fe0.5-yNiyAl0.5 (y = 0-0.5) catalysts also derived from hydrotalcite. The hydrotalcites prepared by co-precipitation were calcined at 550 °C to the mixed oxides with a high surface area of 150-240m2gcat-1; they were composed of Mg(Fe,Me,Al)O periclase and Mg(Me)(Fe,Al)2O4 spinel (Me = Co or Ni). Bimetallic Fe3+-Co2+ system showed a synergy, i.e., an increase in the activity, whereas Fe3+-Ni2+ bimetallic system showed no synergy. The high styrene yield was obtained on Mg 3Fe0.1Co0.4Al0.5; however, a large substitution of Fe3+ with Co2+ caused a decrease in styrene selectivity along with coking on the catalysts, due to an isolation of CoOx on the catalyst surface. The highest yield as well as the highest selectivity for styrene production was obtained at x = 0.25 at time on stream of 30 min. The coprecipitation at pH = 10.0 and the composition of Mg3Fe0.25Co0.25Al0.5 were the best for preparing the active catalyst. This is partly due to the formation of a good hydrotalcite structure. On this catalyst, the active Fe3+ species was reduced at a low temperature by the Fe3+-Co2+ bimetal formation, leading to a high activity. Simultaneously, the amount of reducible Fe3+ was the smallest, resulting in a high stability of the active Fe3+ species. It is likely that the dehydrogenation was catalyzed by the reduction-oxidation between Fe3+ and Fe2+ and that Co2+ assisted the reduction-oxidation by forming Fe 3+-Co2+ (1/1) bimetallic active species. © 2011 Elsevier B.V. All rights reserved.

  8. Microstructure and mechanical properties of ion-beam-produced Fe-Ti-(N), Fe-Ti-(C), and Fe-Ti-(C,N) surface films

    Science.gov (United States)

    Hirvonen, J.-P.; Nastasi, M.; Zocco, T. G.; Jervis, T. R.

    1990-06-01

    Ion-mixed films of Fe53 Ti47 were produced by ion irradiating a Fe-Ti multilayer structure on AISI 304 stainless steel. The ion-mixed films were subsequently implanted with nitrogen, carbon, or both carbon and nitrogen. The microstructure following nitrogen implantation consisted of a bcc solid solution of iron and titanium and finely dispersed TiN precipitates. In the cases of carbon or carbon and nitrogen implantation, a two-phase structure consisting of an amorphous matrix with TiC or Ti(C,N) precipitates was found. All these films initially possessed improved tribological properties as revealed by lowered friction and increased wear resistance. However, after an extended test of 1000 wear cycles, a reduced friction was only observed for the carbon or carbon and nitrogen implanted samples. The wear track on the dual implanted surface was extremely smooth, while the surface of the nitrogen-implanted sample was partly worn through, causing the friction to increase to the level of the untreated sample. The improved tribological properties of the implanted films are attributed to an increase in surface hardness. However, the surface hardness is unable to explain differences between different implantations. In the case of the dual carbon and nitrogen implantation, improvements appear to be in part the result from an increased capability to accommodate plastic deformation. These conclusions are supported by transmission electron microscope studies of the wear tracks as well as by nanoindentation measurements.

  9. Anodic oxidation of Ta/Fe alloys

    International Nuclear Information System (INIS)

    Mato, S.; Alcala, G.; Thompson, G.E.; Skeldon, P.; Shimizu, K.; Habazaki, H.; Quance, T.; Graham, M.J.; Masheder, D.

    2003-01-01

    The behaviour of iron during anodizing of sputter-deposited Ta/Fe alloys in ammonium pentaborate electrolyte has been examined by transmission electron microscopy, Rutherford backscattering spectroscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy. Anodic films on Ta/1.5 at.% Fe, Ta/3 at.% Fe and Ta/7 at.% Fe alloys are amorphous and featureless and develop at high current efficiency with respective formation ratios of 1.67, 1.60 and 1.55 nm V -1 . Anodic oxidation of the alloys proceeds without significant enrichment of iron in the alloy in the vicinity of the alloy/film interface and without oxygen generation during film growth, unlike the behaviour of Al/Fe alloys containing similar concentrations of iron. The higher migration rate of iron species relative to that of tantalum ions leads to the formation of an outer iron-rich layer at the film surface

  10. Removal combined with reduction of hexavalent chromium from aqueous solution by Fe-ethylene glycol complex microspheres

    Science.gov (United States)

    Zhang, Yong-Xing; Jia, Yong

    2016-12-01

    Three-dimensional Fe-ethylene glycol (Fe-EG) complex microspheres were synthesized by a facile hydrothermal method, and were characterized by field emission scanning electron microscopy and transmission electron microscopy. The adsorption as well as reduction properties of the obtained Fe-EG complex microspheres towards Cr(VI) ions were studied. The experiment data of adsorption kinetic and isotherm were fitted by nonlinear regression approach. In neutral condition, the maximum adsorption capacity was 49.78 mg g-1 at room temperature, and was increased with the increasing of temperature. Thermodynamic parameters including the Gibbs free energy, standard enthalpy and standard entropy revealed that adsorption of Cr(VI) was a feasible, spontaneous and endothermic process. Spectroscopic analysis revealed the adsorption of Cr(VI) was a physical adsorption process. The adsorbed CrO42- ions were partly reduced to Cr(OH)3 by Fe(II) ions and the organic groups in the Fe-EG complex.

  11. Cooking and Fe fortification have different effects on Fe bioavailability of bread and tortillas.

    Science.gov (United States)

    Hernández, Miguel; Sousa, Virginia; Villalpando, Salvador; Moreno, Ambar; Montalvo, Irene; López-Alarcón, Mardya

    2006-02-01

    To identify iron sources for wheat- (WF) and corn-flour (CF) fortification taking into account the effect of cooking. Sixty-six Fe-depleted rats were replete with various Fe sources. Fe bioavailability and utilization in wheat bread (WB) and corn tortillas (CT) fortified with various Fe sources was assessed after the depletion and repletion periods. Baking decreased the phytates content of WF by 97%. Improvements in Hb and FeHb were greater in rats fed unfortified WB than in those fed unfortified WF. Fe fortification had no benefit. In contrast, phytates content was unchanged by tortilla preparation, but fortification improved iron availability. Iron bioavailability indicators were best in rats fed CT fortified with ferrous sulfate and NaFe(III)EDTA than in those fed unfortified CT or CT plus reduced Fe. We concluded that baking WF bread improved the bioavailability of native Fe with no further effect of fortification. Pan-cooking of lime-treated CF did not improve Fe bioavailability, but addition of Ferrous sulfate or NaFe(III)EDTA did it, despite the high phytate and calcium content of tortillas.

  12. Antiferromagnetic interlayer coupling in Fe/V and Fe/Cr

    International Nuclear Information System (INIS)

    Vega, A.; Rubio, A.; Balbas, L.C.; Dorantes-Davila, J.; Bouarab, S.; Demangeat, C.; Mokrani, A.; Dreysse, H.

    1991-01-01

    Antiferromagnetic (AF) coupling between Fe and V atoms is observed experimentally at the Fe/V and Fe/Cr interfaces. In the self-consistent tight-binding derivation of the unrestricted approximation of the Hubbard Hamiltonian, we have investigated Fe 3 V n (n=1--5) superlattices and Fe 3 V n (n=1--5) films. In all cases one finds an AF coupling between Fe and V together with a decreasing oscillation of the induced magnetic moment on the V atoms when the distance from Fe increases. The distributions of local magnetic moments on Fe and Cr layers in Fe 3 Cr n (n=3--5) superlattices have been determined self-consistently. Both AF and ferromagnetic (F) coupling between Fe layers separated by Cr have been studied. In all cases one finds strong AF couplings between Fe and Cr nearest neighbors with an important increase of the Cr magnetic moment at the interface as compared to the Cr bulk value

  13. Antiferromagnetic interlayer coupling in Fe/V and Fe/Cr

    Energy Technology Data Exchange (ETDEWEB)

    Vega, A.; Rubio, A.; Balbas, L.C. (Departamento de Fisica Teorica, Universidad de Valladolid, Spain (ES)); Dorantes-Davila, J. (Departamento de Fisica Teorica, CINVESTAN-IPN, Apdo. 14-740, Mexico, (Mexico)); Bouarab, S.; Demangeat, C. (IPCMS, Universite Louis Pasteur, 4 rue Blaise Pascal, 67070 Strasbourg, (France)); Mokrani, A.; Dreysse, H. (Laboratoire de Physique des Solides, BP 239, 54506 Vandoeuvre-les Nancy, (France))

    1991-04-15

    Antiferromagnetic (AF) coupling between Fe and V atoms is observed experimentally at the Fe/V and Fe/Cr interfaces. In the self-consistent tight-binding derivation of the unrestricted approximation of the Hubbard Hamiltonian, we have investigated Fe{sub 3}V{sub {ital n}} ({ital n}=1--5) superlattices and Fe{sub 3}V{sub {ital n}} ({ital n}=1--5) films. In all cases one finds an AF coupling between Fe and V together with a decreasing oscillation of the induced magnetic moment on the V atoms when the distance from Fe increases. The distributions of local magnetic moments on Fe and Cr layers in Fe{sub 3}Cr{sub {ital n}} ({ital n}=3--5) superlattices have been determined self-consistently. Both AF and ferromagnetic ({ital F}) coupling between Fe layers separated by Cr have been studied. In all cases one finds strong AF couplings between Fe and Cr nearest neighbors with an important increase of the Cr magnetic moment at the interface as compared to the Cr bulk value.

  14. Neutron irradiation effects in Fe and Fe-Cr at 300 °C

    International Nuclear Information System (INIS)

    Chen, Wei-Ying; Miao, Yinbin; Gan, Jian; Okuniewski, Maria A.; Maloy, Stuart A.; Stubbins, James F.

    2016-01-01

    Fe and Fe-Cr (Cr = 10–16 at.%) specimens were neutron-irradiated at 300 °C to 0.01, 0.1 and 1 dpa. The TEM observations indicated that the Cr significantly reduced the mobility of dislocation loops and suppressed vacancy clustering, leading to distinct damage microstructures between Fe and Fe-Cr. Irradiation-induced dislocation loops in Fe were heterogeneously observed in the vicinity of grown-in dislocations, whereas the loop distribution observed in Fe-Cr is much more uniform. Voids were observed in the irradiated Fe samples, but not in irradiated Fe-Cr samples. Increasing Cr content in Fe-Cr results in a higher density, and a smaller size of irradiation-induced dislocation loops. Orowan mechanism was used to correlate the observed microstructure and hardening, which showed that the hardening in Fe-Cr can be attributed to the formation of dislocation loops and α′ precipitates. -- Graphical abstract: Addition of Cr in Fe suppressed the mobility of mobile 1/2<111> dislocation loops and increased the proportion of immobile <100> dislocation loops, leading to a transition of loop distribution from highly heterogeneous to uniform. Display Omitted

  15. Metal Injection Molding (MIM of NdFeB Magnets

    Directory of Open Access Journals (Sweden)

    Hartwig T.

    2014-07-01

    Full Text Available Due to the increased and unstable prices for Rare Earth elements there are activities to develop alternative hard magnetic materials. Reducing the amount of material necessary to produce complex sintered NdFeB magnets can also help to reduce some of the supply problem. Metal Injection Molding (MIM is able to produce near net shape parts and can reduce the amount of finishing to achieve final geometry. Although MIM of NdFeB has been patented and published fairly soon after the development of the NdFeB magnets there has never been an industrial production. This could be due to the fact that MIM was very young at that time and hardly developed. Thus, the feasibility of the process needs to be revaluated. This paper presents results of our work on determining the process parameters influencing the magnetic properties of the sintered magnets as well as the shrinkage during processing. The role of binder and powder loading on the alignment of the particles as well as on the carbon and oxygen contamination was examined.

  16. Injection moulding of low expansion Fe-Ni-Co alloys

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, R.M. do; Justino, J.G.; Fredel, M.C.; Wendhausen, P.A.P.; Klein, A.N.; Almeida Buschinelli, A.J. de [Dept. of Mechanical Engineering, Univ. Federal de Santa Catarina Florianopolis (Brazil)

    2001-07-01

    Low-expansion alloys (Fe-Ni-Co) are used in specific applications that require accurate dimensional control, such as standards for length measurement, radar resonant cavities, components for nuclear reactors and parts for ceramic-metal joining. This work investigates the production of the Fe-28%Ni-18%Co and Fe-28%Ni-23%Co alloys by powder injection moulding. The mixtures were characterised in the capillar rheometer. The microstructure was characterised with a scanning electron microscope and X-ray diffraction and the coefficient of thermal expansion determined with a linear dilatometer. The mixtures presented a pseudoplastic rheological behaviour and a viscosity level adequate to the injection moulding. The microstructure of the two alloys was constituted of an austenitic phase and the residual porosity (8.5%). Dilatometric behaviour of two alloys is characterised by two distinct regions, demonstrating the presence of the Invar effect and different transition temperature depending on the cobalt content. Coefficients of thermal expansion for both alloys can be considered adequate for brazing with alumina. (orig.)

  17. Hybrid materials based on polymethylsilsesquioxanes containing Fe, Pt, and Fe-Pt metallic nanoparticles

    Science.gov (United States)

    Vasil'kov, A. Yu.; Migulin, D. A.; Naumkin, A. V.; Zubavichus, Ya. V.; Budnikov, A. V.; Ellert, O. G.; Maksimov, Yu. V.; Muzafarov, A. M.

    2017-11-01

    New hybrid materials based on Pt, Fe, and Pt-Fe nanoparticles stabilized in a matrix of polymethylsilsesquioxane nanogel and ultrahigh molecular weight polyethylene (UHMWPE) were prepared. Metal vapor synthesis was used to produce mono- and bimetallic nanoparticles. It was shown that organosilicon nanogel effectively stabilizes Pt nanoparticles with an average size of 0.9 nm. Using the nanogel results in the formation of superparamagnetic Fe particles 3-5 nm in size that consist of ferromagnetic Fe0 core and antiferromagnetic shells of Fe oxides. It is established that using an organosilicon matrix in the formation of Pt-Fe/UHMWPE systems helps reduce the average particle size of Fe in the material from 6.5 to 4.5 nm and narrow their particle size distribution. The composition, magnetic and electronic characteristics of the nanocomposites are studied via transmission electron microscopy, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, XANES, and EXAFS.

  18. Fe/V and Fe/Co (0 0 1) superlattices: growth, anisotropy, magnetisation and magnetoresistance

    International Nuclear Information System (INIS)

    Nordblad, P.; Broddefalk, A.; Mathieu, R.; Blomqvist, P.; Eriksson, O.; Waeppling, R.

    2003-01-01

    Some physical properties of BCC Fe/V and Fe/Co (0 0 1) superlattices are reviewed. The dependence of the magnetic anisotropy on the in-plane strain introduced by the lattice mismatch between Fe and V is measured and compared to a theoretical derivation. The dependence of the magnetic anisotropy (and saturation magnetisation) on the layer thickness ratio Fe/Co is measured and a value for the anisotropy of BCC Co is derived from extrapolation. The interlayer exchange coupling of Fe/V superlattices is studied as a function of the V layer thickness (constant Fe thickness) and layer thickness of Fe (constant V thickness). A region of antiferromagnetic coupling and GMR is found for V thicknesses 12-14 monolayers. However, surprisingly, a 'cutoff' of the antiferromagnetic coupling and GMR is found when the iron layer thickness exceeds about 10 monolayers

  19. Raman spectroscopic features of Al- Fe3+- poor magnesiochromite and Fe2+- Fe3+- rich ferrian chromite solid solutions

    Science.gov (United States)

    Kharbish, Sherif

    2017-08-01

    Naturally occurring Al- Fe3 +- poor magnesiochromite and Fe2+- Fe3 +- rich ferrian chromite solid solutions have been analyzed by micro-Raman spectroscopy. The results reflect a strong positive correlation between the Fe3 + # [Fe3+/(Fe3 ++Cr + Al)] and the positions of all Raman bands. A positive correlation of the Raman band positions with Mg# [Mg/(Mg + Fe2 +)] is less stringent. Raman spectra of magnesiochromite and ferrian chromite show seven and six bands, respectively, in the spectral region of 800 - 100 cm- 1. The most intense band in both minerals is identified as symmetric stretching vibrational mode, ν 1(A 1g ). In the intermediate Raman-shift region (400-600 cm- 1), the significant bands are attributed to the ν 3(F 2g ) > ν 4(F 2g ) > ν 2(E g ) modes. The bands with the lowest Raman shifts (< 200 cm- 1) are assigned to F 2g (trans) translatory lattice modes. Extra bands in magnesiochromite (two bands) and in ferrian chromite (one weak band) are attributed to lowering in local symmetry and order/disorder effects.

  20. Hyperfine fields of Fe in Nd2Fe14BandSm2Fe17N3

    Science.gov (United States)

    Akai, Hisazumi; Ogura, Masako

    2015-03-01

    High saturation magnetization of rare-earth magnets originates from Fe and the strong magnetic anisotropy stems from f-states of rare-earth elements such as Nd and Sm. Therefore the hyperfine fields of both Fe and rare-earth provide us with important pieces of information: Fe NMR enable us to detect site dependence of the local magnetic moment and magnetic anisotropy (Fe sites also contribute to the magnetic anisotropy) while rare-earth NQR directly give the information of electric field gradients (EFG) that are related to the shape of the f-electron cloud as well as the EFG produced by ligands. In this study we focus on the hyperfine fields of materials used as permanent magnets, Nd2Fe14BandSm2Fe17N3 from theoretical points of view. The detailed electronic structure together with the hyperfine interactions are discussed on the basis of the first-principles calculation. In particular, the relations between the observed hyperfine fields and the magnetic properties are studies in detail. The effects of doping of those materials by other elements such as Dy and the effects of N adding in Sm2Fe17N3 will be discussed. This work was supported by Elements Strategy Initiative Center for Magnetic Materials Project, the Ministry of Education, Culture, Sports, Science and Technology, Japan.

  1. A method for determination of [Fe3+]/[Fe2+] ratio in superparamagnetic iron oxide

    Science.gov (United States)

    Jiang, Changzhao; Yang, Siyu; Gan, Neng; Pan, Hongchun; Liu, Hong

    2017-10-01

    Superparamagnetic iron oxide nanoparticles (SPION), as a kind of nanophase materials, are widely used in biomedical application, such as magnetic resonance imaging (MRI), drug delivery, and magnetic field assisted therapy. The magnetic property of SPION has close connection with its crystal structure, namely it is related to the ratio of Fe3+ and Fe2+ which form the SPION. So a simple way to determine the content of the Fe3+ and Fe2+ is important for researching the property of SPION. This review covers a method for determination of the Fe3+ and Fe2+ ratio in SPION by UV-vis spectrophotometry based the reaction of Fe2+ and 1,10-phenanthroline. The standard curve of Fe with R2 = 0.9999 is used for determination the content of Fe2+ and total iron with 2.5 mL 0.01% (w/v) SPION digested by HCl, pH = 4.30 HOAc-NaAc buffer 10 mL, 0.01% (w/v) 1,10-phenanthroline 5 mL and 10% (w/v) ascorbic acid 1 mL for total iron determine independently. But the presence of Fe3+ interfere with obtaining the actual value of Fe2+ (the error close to 9%). We designed a calibration curve to eliminate the error by devising a series of solution of different ratio of [Fe3+]/[Fe2+], and obtain the calibration curve. Through the calibration curve, the error between the measured value and the actual value can be reduced to 0.4%. The R2 of linearity of the method is 0.99441 and 0.99929 for Fe2+ and total iron respectively. The error of accuracy of recovery and precision of inter-day and intra-day are both lower than 2%, which can prove the reliability of the determination method.

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

    Science.gov (United States)

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

    2012-01-01

    As an effort to better utilize the microbial fuel cell (MFC) technology, we previously proposed an innovative MFC system named M2FC consisting of ferric-based MFC part and ferrous-based fuel cell (FC) part. In this reactor, ferric ion, the catholyte in the MFC part, was efficiently regenerated by the FC part with the generation of additional electricity. When both units were operated separately, the ferric-based MFC part produced approximately 1360 mW m(-2) of power density with FeCl(3) as catholyte and Fe-citrate as anolyte. The ferrous-based FC part with FeCl(3) as catholyte and Fe-EDTA as anolyte displayed the highest power density (1500 mW m(-2)), while that with ferricyanide as catholyte and Fe-noligand as anolyte had the lowest power density (380 mW m(-2)). The types of catholytes and chelating complexes as anolyte were found to play important roles in the reduction of ferric ions and oxidation of ferrous ion. Linear sweep voltammetry results supported that the cathode electrolytes were electrically active and these agreed well with the M2FC reactor performance. These results clearly showed that ligands played critical role in the efficiency and rate for recycling iron ion and thus the M2FC performance. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. The thermal evolution of Mercury's Fe-Si core

    Science.gov (United States)

    Knibbe, Jurriën Sebastiaan; van Westrenen, Wim

    2018-01-01

    We have studied the thermal and magnetic field evolution of planet Mercury with a core of Fe-Si alloy to assess whether an Fe-Si core matches its present-day partially molten state, Mercury's magnetic field strength, and the observed ancient crustal magnetization. The main advantages of an Fe-Si core, opposed to a previously assumed Fe-S core, are that a Si-bearing core is consistent with the highly reduced nature of Mercury and that no compositional convection is generated upon core solidification, in agreement with magnetic field indications of a stable layer at the top of Mercury's core. This study also present the first implementation of a conductive temperature profile in the core where heat fluxes are sub-adiabatic in a global thermal evolution model. We show that heat migrates from the deep core to the outer part of the core as soon as heat fluxes at the outer core become sub-adiabatic. As a result, the deep core cools throughout Mercury's evolution independent of the temperature evolution at the core-mantle boundary, causing an early start of inner core solidification and magnetic field generation. The conductive layer at the outer core suppresses the rate of core growth after temperature differences between the deep and shallow core are relaxed, such that a magnetic field can be generated until the present. Also, the outer core and mantle operate at higher temperatures than previously thought, which prolongs mantle melting and mantle convection. The results indicate that S is not a necessary ingredient of Mercury's core, bringing bulk compositional models of Mercury more in line with reduced meteorite analogues.

  4. Enhancement of magnetoresistance using CoFe/Ru/CoFe synthetic ferrimagnetic pinned layer in BiFeO3 based spin-valves

    Science.gov (United States)

    Naganuma, Hiroshi; Bae, In-Tae; Miyazaki, Takamichi; Kubota, Miho; Inami, Nobuhito; Kawada, Yuki; Oogane, Mikihiko; Mizukami, Shigemi; Han, X. F.; Ando, Yasuo

    2012-08-01

    SrTiO3 (100) sub/BiFeO3/CoFe/Ru/CoFe/Cu/CoFe/Ta structure was prepared by a combination of chemical solution deposition and sputtering method, and followed by a systematical investigation for the structural, magnetic and magnetoresistance properties at room temperature (RT) as a function of CoFe and Ru thicknesses. It was revealed that introduction of synthetic CoFe/Ru/CoFe as a pinning layer increased the giant magentoresistance (MR) ratio to 8.3% at RT. This enhancement of MR ratio might be attributed to (i) the increase of pinning field, and (ii) suppression of the influence of the surface roughness of BiFeO3 by inserting the synthetic CoFe/Ru/CoFe layer.

  5. Magnetic nanowires (Fe, Fe-Co, Fe-Ni – magnetic moment reorientation in respect of wires composition

    Directory of Open Access Journals (Sweden)

    Kalska-Szostko Beata

    2015-03-01

    Full Text Available Magnetic nanowires of Fe, Fe-Co, and Fe-Ni alloy and layered structure were prepared by electrochemical alternating current (AC deposition method. The morphology of the nanowires in and without the matrix was studied by energy dispersive X-ray spectroscopy (EDX, scanning electron microscopy (SEM, and X-ray diffraction (XRD, respectively. The wires either show strong dependence on the combination of elements deposition (alloy or layered or chemical composition (Co or Ni. The magnetic properties of the nanostructures were determined on the basis of Mössbauer spectroscopy (MS.

  6. Mecanosíntese do composto BiFeO3 Mechanosynthesis of the BiFeO3 compound

    Directory of Open Access Journals (Sweden)

    V. F. Freitas

    2008-09-01

    Full Text Available Os compostos cerâmicos BiFeO3 puro e modificado (Bi0,95R0,05FeO3, com terras raras R = Gd ou Eu, foram sintetizados por moagem em altas energias. As amostras foram analisadas por difração de raios X, microscopia eletrônica de varredura e espectroscopia por energia dispersiva de raios X. A difração de raios X indicou que as amostras modificadas com Eu são monofásicas, enquanto que as amostras puras e modificadas com Gd apresentaram majoritariamente a fase BiFeO3, com uma pequena quantidade de outras fases. A espectroscopia por energia dispersiva de raios X revelou a presença dos átomos modificantes na amostra e o mapeamento destes átomos indicou uma distribuição homogênea deles em toda a amostra. A microscopia eletrônica de varredura mostrou uma significante diminuição no tamanho das partículas, estando estas com dimensões sub-micrométricas e com diâmetro médio em torno de 500 nm. Estudos de densificação dos corpos cerâmicos indicaram compostos altamente densos, com densidades relativas acima de 0,9 sendo que o composto modificado com Eu alcançou a densidade relativa ρ/ρ0 = 0,98.The, pure and rare earth modified (Bi0.95R0.05FeO3 / R = Gd or Eu BiFeO3 compounds were synthesized by high-energy ball milling. The samples were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The X-ray diffraction results indicated single phase Eu modified samples, while the pure and Gd modified ones presented the BiFeO3 as majority phase, and small amount of the spurious phase. The energy dispersive spectroscopy revealed the presence of the modifiers atoms in the sample and the mapping of these atoms indicated the homogeneous distribution of them in the whole samples. The scanning electron microscopy showed a decrease significant on the particle size, with medium diameter around 500 nm. Densification studies indicated high-dense ceramics body, with relative density above of 0.9, were Eu

  7. Electric-field tunable perpendicular magnetic anisotropy in tetragonal Fe4N/BiFeO3 heterostructures

    Science.gov (United States)

    Yin, Li; Wang, Xiaocha; Mi, Wenbo

    2017-07-01

    Electric field control on perpendicular magnetic anisotropy (PMA) is indispensable for spintronic devices. Herewith, in tetragonal Fe4N/BiFeO3 heterostructures with the FeAFeB/Fe-O2 interface, PMA in each Fe4N layer, not merely interfacial layers, is modulated by the electric field, which is attributed to the broken spin screening of the electric field in highly spin-polarized Fe4N. Moreover, the periodical dx y+dy z+dz2 and dx y+dx2-y2 orbital-PMA oscillation enhances the interactions between adjacent FeAFeB and (FeB)2N atomic layers, which benefits the electric field modulation on PMA in the whole Fe4N atomic layers. The electric-field control on PMA in Fe4N/BiFeO3 heterostructures is favored by the electric-field-lifted potential in Fe4N.

  8. Influence of ruthenium ions on the precipitation of α-FeOOH, α-Fe2O3 and Fe3O4 in highly alkaline media

    International Nuclear Information System (INIS)

    Krehula, Stjepko; Music, Svetozar

    2006-01-01

    The influence of ruthenium ions on the precipitation of goethite (α-FeOOH), α-Fe 2 O 3 and Fe 3 O 4 in highly alkaline media was investigated by 57 Fe Moessbauer and FT-IR spectroscopies, thermal field emission scanning electron microscope (FE SEM) and EDS. The presence of Ru-dopant strongly affected the precipitation of α-FeOOH at highly alkaline pH, i.e. the formation of α-Fe 2 O 3 was also noticed. A decrease of hyperfine magnetic field (HMF) at RT from 35.1 T (undoped α-FeOOH) to 31.3 T for sample with [Ru]/([Ru] + [Fe]) = 0.0196 was assigned to the incorporation of ruthenium ions into the α-FeOOH structure. Moessbauer spectroscopy showed the formation of stoichiometric Fe 3 O 4 for [Ru]/([Ru] + [Fe]) = 0.0291-0.0909. α-Fe 2 O 3 and Fe 3 O 4 did not show a tendency to the formation of solid solutions with ruthenium ions. FE SEM observations of the samples showed that reference α-FeOOH sample contained acicular particles of good uniformity, which increased the length up to ∼5 times with increase of concentration of ruthenium ions. On the other hand, large octahedral Fe 3 O 4 crystals (particles) were associated with small particles of ruthenium (hydrous) oxide with a size in the range ∼100 nm or less. A possible catalytic action of ruthenium that created reduction conditions for Fe 3+ ions and formation of Fe 2+ ions for precipitation of Fe 3 O 4 was discussed

  9. Fe and Co NMR studies of magnetoelectric Co2 Y-type hexaferrite BSCFAO

    Science.gov (United States)

    Choi, Baeksoon; Kwon, Sangil; Lee, Soonchil; Park, Chang Bae; Shin, Kwang Woo; Kim, Keehoon

    2018-02-01

    The Fe3+ and Co2+ NMR spectra for Ba0.3Sr1.7Co2(Fe0.96Al0.04)12O22 (BSCFAO) and Ba0.3Sr1.7Co2Fe12O22 (BSCFO) were obtained in a zero magnetic field at a low temperature. We observed change in the enhancement effect of the NMR signals depending on the setting field, which was varied when applied along the b-axis and then turned off before the measurement was taken. The experimental results indicate that the magnetic structure changes from an alternating longitudinal cone to a transverse cone when the setting field is 250 mT. They also show that the spins of Co2+ ions together with those of Fe3+ ions constitute a part of the overall magnetic structure and that the substitution of Al3+ for Fe3+ weakens the magnetic anisotropy within the easy plane. From a comparison of the enhancement factors of the Fe3+ NMR obtained with the RF pulse applied along the a-axis and the c-axis, we found that the magnetic easy plane anisotropy is approximately 16 times greater than the anisotropy within the easy plane. No changes of the NMR spectra were observed under an electric field of 1.2 MV m‑1.

  10. Strain tuned magnetocrystalline anisotropy in ferromagnetic H-FeCl2 monolayer

    Science.gov (United States)

    Zheng, Huiling; Han, Hecheng; Zheng, Jun; Yan, Yu

    2018-03-01

    For the utilization of two-dimensional materials with ferromagnetism in high density storage, it is very important to find an effective method to enhance their perpendicular magnetocrystalline anisotropy. In this paper, we investigated the impact of strain on structure and magnetism of the H-FeCl2 monolayer by employing first-principles calculations. Our results show that stressless H-FeCl2 monolayer not only is dynamically stable, but also has intrinsic ferromagnetism and perpendicular magnetocrystalline anisotropy. Under the strains ranging from -3% to 3%, the structure of the H-FeCl2 monolayer is always dynamically stable and its ground state is always ferromagnetic (FM) configuration. Interestingly, applying compressive strain can enhance the FM. More importantly, we found the compressive strain can enhance the perpendicular magnetocrystalline anisotropy of H-FeCl2 monolayer by 20.9%. Contrarily, tensile strian can make the perpendicular magnetocrystalline anisotropy decrease by 14.5%. The analysis of density of state (DOS) and the dedications to magnetocrystalline anisotropy energy (MAE) of 3d orbitals of Fe atom demonstrate that the comepressive (tensile) strain influence depends on the decrease (increase) of the negative part to MAE from the hybridization between 3dyz and 3dz2 states through spin-orbit coupling interaction. Our study indicates that applying compressive strain can effectively enhance the ferromagnetism and perpendicular magnetocrystalline anisotropy of H-FeCl2 monolayer for its application in high density data storage.

  11. REGULARITIES OF QUANTITATIVE DISTRIBUTION FOR FE(III-REDUCING BACTERIA IN NATURAL ECOSYSTEMS

    Directory of Open Access Journals (Sweden)

    Govorukha V. M.

    2015-08-01

    Full Text Available The aim of the work was quantitative determination of Fe(III-reducing bacteria in natural ecosystems of the Antarctic, the Arctic, the Dead and the Black Sea, middle latitude (Ukraine, Abkhazia and the equatorial zone (Ecuador. It was used the method of quantitative determination of microorganisms by McCready and the colorimetric method for determination of Fe(II compounds . Results. The systemic study of the number of Fe(III-reducing bacteria of both hemispheres in the ecosystems of six geographic regions was carried out for the first time. High number of Fe(III-reducing bacteria in natural ecosystems was experimentally shown. The number of Fe(III-reducing bacteria ranged from 1.1•102 to 2.8•107 cells/g of absolutely dry sample. Conclusions. The presented data showed that Fe(III-reducing bacteria are an integral part of natural ecosystems and can significantly affect the biogeochemical cycles of iron and carbon compounds transformation.

  12. Magnetic hardening of Fe{sub 50}Co{sub 50} by rotary swaging

    Energy Technology Data Exchange (ETDEWEB)

    Gröb, T., E-mail: t.groeb@phm.tu-darmstadt.de [Division Physical Metallurgy, Alarich-Weiß-Str. 2, 64287 Darmstadt (Germany); Wießner, L. [Institute for Production Engineering and Forming Machines, Otto-Berndt-Str. 2, 64287 Darmstadt (Germany); Bruder, E. [Division Physical Metallurgy, Alarich-Weiß-Str. 2, 64287 Darmstadt (Germany); Faske, T.; Donner, W. [Divison Structure Research, Alarich-Weiß-Str. 2, 64287 Darmstadt (Germany); Groche, P. [Institute for Production Engineering and Forming Machines, Otto-Berndt-Str. 2, 64287 Darmstadt (Germany); Müller, C. [Division Physical Metallurgy, Alarich-Weiß-Str. 2, 64287 Darmstadt (Germany)

    2017-04-15

    Fe{sub 50}Co{sub 50} was subjected to incremental forming by rotary swaging with the aim of tailoring the coercivity by changing the microstructure. The challenging part of a deformation of Fe{sub 50}Co{sub 50} is an ordering phase present at room temperature, leading to low formability. To increase the formability of the alloy the presence of the ordering phase was supressed by two different concepts. The first concept consists of a heat treatment above the phase transition followed by rapid cooling and deformation at room temperature. The second concept was rotary swaging at temperatures above the phase transition temperature. A comparison in terms of resulting microstructure and magnetic properties shows that both concepts have a potential for tailoring the coercivity of Fe{sub 50}Co{sub 50}. - Highlights: • Magnetic hardening of Fe{sub 50}Co{sub 50} was achieved by rotary swaging with two different concepts. • The influences of the microstructural changes during the rotary swaging process have been linked to magnetic hardening. • Increase in coercivity for Fe{sub 50}Co{sub 50} by rotary swaging at elevated temperature is limited by the dynamic restoration. • Coercivity of Fe{sub 50}Co{sub 50} can be tailored by the induced plastic strain.

  13. Ordering phenomena in FeCo-films and Fe/Cr-multilayers: an X-ray and neutron scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Nickel, B.

    2001-07-01

    The following topics are covered: critical phenomena in thin films, critical adsorption, finite size scaling, FeCo Ising model, kinematical scattering theory for thin films, FeCo thin films, growth and characterisation of single crystal FeCo thin films, X-ray study of ordering in FeCo films, antiferromagnetic coupling in Fe/Cr multilayers, neutron scattering on Fe/Cr multilayers (WL)

  14. Molecular [(Fe3)–(Fe3)] and [(Fe4)–(Fe4)] coordination cluster pairs as single or composite arrays.

    Science.gov (United States)

    Sañudo, E Carolina; Uber, Jorge Salinas; Pons Balagué, Alba; Roubeau, Olivier; Aromí, Guillem

    2012-08-06

    The synthesis of molecular cluster pairs is a challenge for coordination chemists due to the potential applications of these species in molecular spintronics or quantum computing. The ligand H(4)L, 1,3-bis-(3-oxo-3-(2-hydroxyphenyl)-propionyl)-2-methoxybenzene, has been successfully used to obtain a series of such complexes using the basic Fe(III) trinuclear carboxylates as starting materials. Synthetic control has allowed the isolation of the two molecular cluster pairs that form the composite [Fe(4)O(2)(PhCO(2))(6)(H(2)L)(pz)](2)[Fe(3)O(PhCO(2))(5)(py)(H(2)L)](2) (1). The dimers of trinuclear units, [Fe(3)O(PhCO(2))(5)(H(2)O)(H(2)L)](2) (2) and [Fe(3)O(o-MePhCO(2))(5)(H(2)L)(py)](2) (3), and the dimers of tetranuclear units, [Fe(4)O(2)(PhCO(2))(6)(H(2)L)(pz)](2) (4) and [Fe(4)O(2)(o-MePhCO(2))(6)(H(2)L)(pz)](2) (5), are presented here. The magnetic properties of the reported aggregates show that they are pairs of semi-independent clusters weakly interacting magnetically as required for two-qubit quantum gates.

  15. Laboratory Study of the Diagnostic Utility of the 3C/3D Line Ratio in Fe XVII

    Science.gov (United States)

    Brown, G. V.; Beiersdorfer, P.; Chen, H.; Chen, M., II; Reed, K. J.

    2002-01-01

    Fe XVII X-ray emission is present in a multitude of sources, such as the corona of the Sun, Capella, and Procyon. Two of the strongest lines observed in these spectra are the resonance and intercombination lines located at 15.01 and 15.26 A, respectively. As part of the laboratory astrophysics program at the electron beam ion traps EBIT-I & EBIT-II located at the Lawrence Livermore National Laboratory we have measured this line ratio for the case where the relative abundance of Fe XVI to Fe XVII is approx. 1. Our results show that an Fe XVI innershell satellite line coincides with the intercombination line and can significantly reduce the relative intensity, R, of the resonance to intercombination line. The fact that the apparent relative intensity of the resonance and intercombination line in Fe XVII is sensitive to the strength of an Fe XVI innershell satellite, and therefore, tho relative abundance of Fe XVI to Fe XVII, makes the line ratio a diagnostic of temperature, and explains the anomalously low ratios observed in the solar and stellar coronae.

  16. Impedance spectroscopy study of polycrystalline Bi6Fe2Ti3O18

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The electrical properties of polycrystalline Bi6Fe2Ti3O18 are investigated by impedance spectroscopy in the temperature range 30–550°C. The imaginary part of impedance as a function of frequency shows Debye like relaxation. Impedance data are presented in the Nyquist plot which is used to identify an ...

  17. Fe-aminoclay-entrapping electrospun polyacrylonitrile nanofibers (FeAC-PAN NFs) for environmental engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Young [Korea Railroad Research Institute, Uiwang (Korea, Republic of); Choi, Saehae [Korea Research Institute of Bioscience and Biotechnology, Daejeon (Korea, Republic of); Park, Seung Bin [KAIST, Daejeon (Korea, Republic of); Kim, Mooon Il; Lee, Young Chul [Gachon Univ., Seongnam (Korea, Republic of); Lee, Go Woon [KIER, Daejeon (Korea, Republic of); Lee, Hyun Uk [Korea Basic Science Institute, Daejeon (Korea, Republic of)

    2015-09-15

    Electrospun polyacrylonitrile nanofibers (PAN NFs) with entrapped water-soluble Fe-aminoclay (FeAC) [FeAC-PAN NFs] were prepared. Slow dropwise addition of water-soluble FeAC into a PAN solution, less aggregated of FeAC into electrospun PAN NFs was one-pot evolved without FeAC post-decoration onto as-prepared PAN NFs. Taking into consideration both the Fe{sup 3+} source in FeAC and the improved surface hydrophilicity, the feasibility of Fentonlike reaction for decolorization of cationic model dye methylene blue (MB) under 6 hrs UV-light irradiation was established. In the case where FeAC-PAN NFs were enhanced by hydrogen peroxide (H{sub 2}O{sub 2}) injection, the apparent kinetic reaction rates were increased relative to those for the PAN NFs. Thus, our flexible FeAC-PAN NF mats can be effectively utilized in water/waste treatment and other environmental engineering applications.

  18. Biomineralization associated with microbial reduction of Fe3+ and oxidation of Fe2+ in solid minerals

    Science.gov (United States)

    Zhang, G.; Dong, H.; Jiang, H.; Kukkadapu, R.K.; Kim, J.; Eberl, D.; Xu, Z.

    2009-01-01

    Iron-reducing and oxidizing microorganisms gain energy through reduction or oxidation of iron, and by doing so play an important role in the geochemical cycling of iron. This study was undertaken to investigate mineral transformations associated with microbial reduction of Fe3+ and oxidation of Fe2+ in solid minerals. A fluid sample from the 2450 m depth of the Chinese Continental Scientific Drilling project was collected, and Fe3+-reducing and Fe2+-oxidizing microorganisms were enriched. The enrichment cultures displayed reduction of Fe3+ in nontronite and ferric citrate, and oxidation of Fe2+ in vivianite, siderite, and monosulfide (FeS). Additional experiments verified that the iron reduction and oxidation was biological. Oxidation of FeS resulted in the formation of goethite, lepidocrocite, and ferrihydrite as products. Although our molecular microbiological analyses detected Thermoan-aerobacter ethanolicus as a predominant organism in the enrichment culture, Fe3+ reduction and Fe2+ oxidation may be accomplished by a consortia of organisms. Our results have important environmental and ecological implications for iron redox cycling in solid minerals in natural environments, where iron mineral transformations may be related to the mobility and solubility of inorganic and organic contaminants.

  19. Pr2Fe14B/α-Fe nanocomposites for thermal applications

    International Nuclear Information System (INIS)

    Silva, Suelanny Carvalho da

    2012-01-01

    In this work, Pr x Fe 94 - x B 6 (x = 6, 8, 10 and 12) nanostructured powders were prepared by a combination of hydrogenation, disproportionation, desorption and recombination (HDDR) process with high energy milling applied to the mixture of an as-cast alloy (Pr 14 Fe 80 B 6 ) and α-Fe. The produced nanoparticles showed magnetic properties comparable to those reported in hyperthermia studies. The optimal time to obtain the magnetic nanoparticles is 5 hours (at 900 rpm). It was verified that longer milling times cause an increase in carbon percentage on the particles. The carbon is derived from oleic acid added as a surfactant in the milling step. The nanocomposites exhibit coercive force ranging from 80 Oe (6.5 kAm -1 ) to 170 Oe (13.5 kAm -1 ) and magnetic moments in the range of 81 129 Am2kg -1 . From the X-ray diffraction analyses, only two phases were found in all samples: α-Fe and the magnetic phase Pr 2 Fe 14 B. Individual nanoparticles with diameter of about 20 nm were verified. The samples studied presented heating when exposed to an alternating magnetic field (f = 222 kHz e H max ∼3.7 kAm -1 ) comparable to reported in literature. Temperature variations (ΔT) of the powders were: 51 K for Pr 6 Fe 88 B 6 , 41 K for Pr 8 Fe 86 B 6 , 38 K for Pr 10 Fe 8 4 B 6 and T = 34 K for Pr 12 Fe 82 B 6 . The specific absorption rates (SARs) of the powders were 201 Wkg -1 for Pr 6 Fe 88 B 6 composition, 158 Wkg -1 on the composition Pr 8 Fe 86 B 6 , and 114 Wkg -1 for Pr 10 Fe 84 B 6 and Pr 12 Fe 82 B 6 compositions. (author)

  20. Comparison of Ab initio low-energy models for LaFePO, LaFeAsO, BaFe2As2, LiFeAs, FeSe, and FeTe. Electron correlation and covalency

    International Nuclear Information System (INIS)

    Miyake, Takashi; Nakamura, Kazuma; Arita, Ryotaro; Imada, Masatoshi

    2010-01-01

    Effective low-energy Hamiltonians for several different families of iron-based superconductors are compared after deriving them from the downfolding scheme based on first-principles calculations. Systematic dependences of the derived model parameters on the families are elucidated, many of which are understood from the systematic variation of the covalency between Fe-3d and pnictogen-/chalcogen-p orbitals. First, LaFePO, LaFeAsO (1111), BaFe 2 As 2 (122), LiFeAs (111), FeSe, and FeTe (11) have overall similar band structures near the Fermi level, where the total widths of 10-fold Fe-3d bands are mostly around 4.5 eV. However, the derived effective models of the 10-fold Fe-3d bands (d model) for FeSe and FeTe have substantially larger effective onsite Coulomb interactions U - 4.2 and 3.4 eV, respectively, after the screening by electrons on other bands and after averaging over orbitals, as compared to ∼2.5 eV for LaFeAsO. The difference is similar in the effective models containing p orbitals of As, Se or Te (dp or dpp model), where U ranges from ∼4 eV for the 1111 family to ∼7 eV for the 11 family. The exchange interaction J has a similar tendency. The family dependence of models indicates a wide variation ranging from weak correlation regime (LaFePO) to substantially strong correlation regime (FeSe). The origin of the larger effective interaction in the 11 family is ascribed to smaller spread of the Wannier orbitals generating larger bare interaction, and to fewer screening channels by the other bands. This variation is primarily derived from the distance h between the pnictogen/chalcogen position and the Fe layer: The longer h for the 11 family generates more ionic character of the bonding between iron and anion atoms, while the shorter h for the 1111 family leads to more covalent-bonding character, the larger spread of the Wannier orbitals, and more efficient screening by the anion p orbitals. The screened interaction of the d model is strongly orbital

  1. Directed Self-Assembly of Epitaxial CoFe2O4-BiFeO3 Multiferroic Nanocomposites

    Science.gov (United States)

    2012-04-09

    REPORT Directed Self-Assembly of Epitaxial CoFe 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: CoFe2O4 (CFO)? BiFeO3 (BFO) nanocomposites are an intriguing...Prescribed by ANSI Std. Z39.18 - CoFe2O4- BiFeO3 Multiferroic Nanocomposites Directed Self-Assembly of Epitaxial CoFe Report Title ABSTRACT CoFe2O4...CFO)? BiFeO3 (BFO) nanocomposites are an intriguing option for future memory and logic technologies due to the magnetoelectric properties of the system

  2. Sulfidation behavior of Fe20Cr alloys

    International Nuclear Information System (INIS)

    Pillis, Marina Fuser

    2001-01-01

    Alloys for use in high temperature environments rely on the formation of an oxide layer for their protection. Normally, these protective oxides are Cr 2 O 3 , Al 2 O 3 and, some times, SiO 2 . Many industrial gaseous environments contain sulfur. Sulfides, formed in the presence of sulfur are thermodynamically less stable, have lower melting points and deviate much more stoichiometrically, compared to the corresponding oxides. The mechanism of sulfidation of various metals is as yet not clear, in spite of the concerted efforts during the last decade. To help address this situation, the sulfidation behavior of Fe20Cr has been studied as a function of compositional modifications and surface state of the alloy. The alloys Fe20Cr, Fe20Cr0.7Y, Fe20Cr5Al and Fe20Cr5Al0.6Y were prepared and three sets of sulfidation tests were carried out. In the first set, the alloys were sulfidized at 700 deg C and 800 deg C for 10h. In the second set, the alloys were pre-oxidized at 1000 deg C and then sulfidized at 800 deg C for up to 45h. In the third set of tests, the initial stages of sulfidation of the alloys was studied. All the tests were carried out in a thermobalance, in flowing H 2 /2%H 2 S, and the sulfidation behavior determined as mass change per unit area. Scanning electron microscopy coupled to energy dispersive spectroscopy and X-ray diffraction analysis were used to characterize the reaction products. The addition of Y and Al increased sulfidation resistance of Fe20Cr. The addition of Y altered the species that diffused predominantly during sulfide growth. It changed from predominant cationic diffusion to predominant anionic diffusion. The addition of Al caused an even greater increase in sulfidation resistance of Fe20Cr, with the parabolic rate constant decreasing by three orders of magnitude. Y addition to the FeCrAl alloy did not cause any appreciable alteration in sulfidation resistance. Pre-oxidation of the FeCrAl and FeCrAlY alloys resulted in an extended

  3. Structural and magnetic study of mechanically deformed Fe rich FeAlSi ternary alloys

    International Nuclear Information System (INIS)

    Legarra, E.; Apiñaniz, E.; Plazaola, F.

    2012-01-01

    Highlights: ► Addition of Si to binary Fe–Al alloys makes the disordering more difficult. ► Si addition opposes the large volume increase found in FeAl alloys with deformation. ► Disordering induces a redistribution of non-ferrous atoms around Fe atoms in Fe 75 Al 25−x Si x and Fe 70 Al 30−x Si x . ► Addition of Si to binary Fe 75 Al 25 and Fe 70 Al 30 alloys opposes the magnetic behavior induced by Al in the magnetism of Fe. ► Si inhibits the para-ferro transition found in Fe 60 Al 40 alloy with disordering. - Abstract: In this work we study systematically the influence of different Al/Si ratios on the magnetic and structural properties of mechanically disordered powder Fe 75 Al 25−x Si x , Fe 70 Al 30−x Si x and Fe 60 Al 40−x Si x alloys by means of Mössbauer spectroscopy, X-ray diffraction and magnetic measurements. In order to obtain different stages of disorder the alloys were deformed by different methods: crushing induction melted alloys and ball milling annealed (ordered) alloys using different number of balls and speed. X-ray and Mössbauer data show that mechanical deformation induces the disordered A2 structure in these alloys. The results indicate that addition of Si to binary Fe–Al alloys makes the disordering more difficult. In addition, X-ray diffraction patterns show that the normalized lattice parameter variation of the disordered alloys of each composition decreases monotonically with Si content, indicating clearly that Si addition opposes the large volume increase found in FeAl alloys with deformation. The study of the hyperfine fields indicates that there is a redistribution of non-ferrous atoms around Fe atoms with the disordering; indeed, there is an inversion of the behavior of the hyperfine field of the Fe atoms. On the other hand, the magnetic measurements indicate that addition of Si to binary Fe 75 Al 25 and Fe 70 Al 30 alloys opposes the magnetic behavior induced by Al in the magnetism of Fe.

  4. Fe-N and (Fe, Ni)-N Fine Powders for Magnetic Recording

    International Nuclear Information System (INIS)

    Chen Ziyu; Li Fashen

    1998-01-01

    Combining Moessbauer spectroscopy with magnetic property measurement, we have studied Fe-N and (Fe, Ni)-N powders for magnetic recording. The typical particles of the core (α-Fe)/shell (γ'-Fe 4 N) structure have been successfully prepared. All the products are stabilized in a multi-organic solution. It has been found that the coercivity can be changed from 300 to 800 Oe by adjusting the shape of the particles. The special saturation magnetization of the particles can be adjusted from 120 to 180emu/g and their chemical stability is improved by substituting nickel for iron in γ'-Fe 4 N. Following experiments for corrosion resistance, it is expected that (Fe, Ni)-N and the core/shell particles will be applied as recording media in the near future

  5. Fe-N and (Fe, Ni)-N Fine Powders for Magnetic Recording

    Energy Technology Data Exchange (ETDEWEB)

    Chen Ziyu; Li Fashen [Lanzhou University, Department of Physics (China)

    1998-12-15

    Combining Moessbauer spectroscopy with magnetic property measurement, we have studied Fe-N and (Fe, Ni)-N powders for magnetic recording. The typical particles of the core ({alpha}-Fe)/shell ({gamma}'-Fe{sub 4}N) structure have been successfully prepared. All the products are stabilized in a multi-organic solution. It has been found that the coercivity can be changed from 300 to 800 Oe by adjusting the shape of the particles. The special saturation magnetization of the particles can be adjusted from 120 to 180emu/g and their chemical stability is improved by substituting nickel for iron in {gamma}'-Fe{sub 4}N. Following experiments for corrosion resistance, it is expected that (Fe, Ni)-N and the core/shell particles will be applied as recording media in the near future.

  6. Origin of (0 0 1) orientation and superlattice structure identification in L10-FePt/B4C multilayer thin films

    Science.gov (United States)

    Zhang, Jun; Xie, Jian; Wang, Yi; Wang, Hanbin; Liu, Xiang; Ye, Cong; Wang, Hao

    2015-12-01

    (0 0 1) textured L10 FePt/B4C multilayer thin films have been prepared on amorphous substrates by magnetron sputtering. High resolution transmission electron microscopy investigation indicates that the Fe and Pt atoms stacked alternately along the c-axis of L10 FePt, confirming the formation of the superlattice structure of L10-ordered FePt. The internal stress calculation and geometrical phase analysis confirm the existence of the in-plane tensile strain in the L10 FePt thin films. The diffusion of the B and C atoms into the FePt layers results in expansion of the FePt unit cells in the interfaces, which induces an in-plane tensile strain in the adjacent deep parts of FePt layer. Such an in-plane tensile strain creates a favorable condition for the FePt films to stabilize the (0 0 1) texture because it relaxes the ordering strain energy of FePt during phase transformation.

  7. Managing Asthma in Pregnancy (MAP) trial: FeNO levels and childhood asthma.

    Science.gov (United States)

    Morten, Matthew; Collison, Adam; Murphy, Vanessa E; Barker, Daniel; Oldmeadow, Christopher; Attia, John; Meredith, Joseph; Powell, Heather; Robinson, Paul D; Sly, Peter D; Gibson, Peter G; Mattes, Joerg

    2018-03-07

    .03, respectively). FeNO-guided asthma management during pregnancy prevented doctor diagnosed asthma in the offspring at preschool age, in part mediated through changes in use and dosing of inhaled corticosteroids during the MAP trial. Copyright © 2018. Published by Elsevier Inc.

  8. Observation by Moessbauer effect and X-ray diffraction of the presence of the ordered alloy Fe-Ni 50-50 in the Santa-Catharina meteorite

    International Nuclear Information System (INIS)

    Danon, Jacques; Scorzelli, Rosa; Souza Azevedo, Isabel; Albertsen, J.F.; Knudsen, J.M.

    1978-01-01

    Electron microprobe analysis, Moessbauer spectra and X-ray diffraction on polished slices reveal that the major part of the Santa-Catharina meteorite is constituted by the ordered alloy (superstructure) Fe-Ni 50-50 [fr

  9. Observation by Moessbauer effect and x-ray diffraction of the presence of the ordered alloy Fe-Ni 50-50 in the Santa Catharina Meteorite

    International Nuclear Information System (INIS)

    Danon, J.; Scorzelli, R.; Azevedo, I.S.; Curvello, W.; Albertsen, J.F.; Knudsen, J.M.

    1978-11-01

    Electron microprobe analysis, Moessbauer spectra and X-ray diffraction on polished slices reveal that the major part of the Santa Catharina Meteorite is constituted by ordered alloy (superstructure) Fe-Ni 50-50

  10. Two-proton radioactivity of 45Fe

    International Nuclear Information System (INIS)

    Miernik, K.; Dominik, W.; Janas, Z.; Pfutzner, M.; Grigorenko, L.; Bingham, C.R.; Czyrkowski, H.; Cwiok, Mikolaj; Darby, Iain; Dabrowski, Ryszard; Ginter, T.N.; Grzywacz, R.; Karny, M.; Korgul, A.; Kusmierz, W.; Liddick, Sean; Rajabali, Mustafa; Rykaczewski, Krzysztof Piotr; Stolz, A.

    2009-01-01

    In an experiment at the SISSI-LISE3 facility of GANIL, the decay of the proton drip line nucleus 45Fe has been studied. Fragment-implantation events have been correlated with radioactive decay events in a 16x16 pixel silicon-strip detector. The decay-energy spectrum of 45Fe implants shows a distinct peak at (1.14+/-0.04) MeV with a half-life of T(1/2)=(4.7(+3.4)(-1.4)) ms. None of the events in this peak is in coincidence with beta particles. For a longer correlation interval, daughter decays of the two-proton daughter 43Cr can be observed after 45Fe implantation. The decay energy for 45Fe agrees nicely with several theoretical predictions for two-proton radioactivity.

  11. Two-proton radioactivity of 45Fe

    International Nuclear Information System (INIS)

    Giovinazzo, J.; Blank, B.; Chartier, M.; Czajkowski, S.; Fleury, A.; Lopez Jimenez, M.J.; Pravikoff, M.S.; Thomas, J.-C.; Oliveira Santos, F. de; Lewitowicz, M.; Maslov, V.; Stanoiu, M.; Grzywacz, R.; Pfuetzner, M.; Borcea, C.; Brown, B.A.

    2002-01-01

    In an experiment at the SISSI-LISE3 facility of GANIL, the decay of the proton drip line nucleus 45 Fe has been studied. Fragment-implantation events have been correlated with radioactive decay events in a 16x16 pixel silicon-strip detector. The decay-energy spectrum of 45 Fe implants shows a distinct peak at (1.14±0.04) MeV with a half-life of T 1/2 =(4.7 -1.4 +3.4 ) ms. None of the events in this peak is in coincidence with β particles. For a longer correlation interval, daughter decays of the two-proton daughter 43 Cr can be observed after 45 Fe implantation. The decay energy for 45 Fe agrees nicely with several theoretical predictions for two-proton radioactivity

  12. Summary of Fe opacity measurement platform

    Energy Technology Data Exchange (ETDEWEB)

    Nagayama, Taisuke

    2016-05-01

    This powerpoint presentation goes over the Fe opacity measurement platform, including how the experiment works, what can be gathered from the measurements, what can be gathered from the simulations, and the limitations of the experiment.

  13. Anisotropic magnetization of Fe8 molecular nanomagnet

    International Nuclear Information System (INIS)

    Ueda, Miki; Maegawa, Satoru

    2002-01-01

    The magnetization of the single crystal of a molecular magnet [(C 6 H 15 N 3 ) 6 Fe 8 O 2 (OH) 12 ] Br 7 (H 2 O) Br·8H 2 O, Fe8, has been measured in the temperature down to 1.8 K and the field up to 5 T. The molecule Fe8 consists of eight Fe 3+ ions with spins s=5/2. The magnetization at low temperatures shows large anisotropy depending on the orientation of the external magnetic field. The temperature and magnetic field dependences of the magnetization are well explained by the Hamiltonian for the isolated molecules with total spins S=10. The anisotropies of D and E are estimated to be -0.276 K and -0.035 K, respectively. (author)

  14. Lattice sites of implanted Fe in Si

    CERN Document Server

    Wahl, Ulrich; Rita, E; Araújo, João Pedro; Carvalho-Soares, José

    2005-01-01

    The angular distribution of $\\beta^{-}$-particles emitted by the radioactive isotope $^{59}$Fe was monitored following implantation into Si single crystals at fluences from $1.4 \\times 10^{12}$ cm$^{-2}$ to $1 \\times 10^{14}$ cm$^{-2}$. We identified Fe on three distinct sites: ideal substitutional, displaced substitutional and displaced tetrahedral interstitial. Whereas displaced substitutional Fe was dominating for annealing temperatures below 500 °C, annealing between 500-700 °C caused the majority of Fe to occupy displaced tetrahedral interstitial sites. Ideal substitutional positions were increasingly populated following annealing at 800 °C and above. A comparison of the emission channeling results to Mössbauer and electron paramagnetic resonance experiments is given.

  15. Swelling of Fe-Mn and Fe-Cr-Mn alloys at high neutron fluence

    International Nuclear Information System (INIS)

    Garner, F.A.; Brager, H.R.

    1986-06-01

    Swelling data on neutron-irradiated simple Fe-Cr-Mn and Fe-Mn alloys, as well as commercial Fe-Cr-Mn base alloys are now becoming available at exposure levels approaching 50 dpa. The swelling rate decreases from the ∼1%/dpa found at lower exposures, probably due to the extensive formation of ferritic phases. As expected, commercial alloys swell less than the simple alloys

  16. High Temperature Magnetic Properties of Indirect Exchange Spring FePt/M(Cu,C/Fe Trilayer Thin Films

    Directory of Open Access Journals (Sweden)

    Anabil Gayen

    2013-01-01

    Full Text Available We report the investigation of temperature dependent magnetic properties of FePt and FePt(30/M(Cu,C/Fe(5 trilayer thin films prepared by using magnetron sputtering technique at ambient temperature and postannealed at different temperatures. L10 ordering, hard magnetic properties, and thermal stability of FePt films are improved with increasing postannealing temperature. In FePt/M/Fe trilayer, the formation of interlayer exchange coupling between magnetic layers depends on interlayer materials and interface morphology. In FePt/C/Fe trilayer, when the C interlayer thickness was about 0.5 nm, a strong interlayer exchange coupling between hard and soft layers was achieved, and saturation magnetization was enhanced considerably after using interlayer exchange coupling with Fe. In addition, incoherent magnetization reversal process observed in FePt/Fe films changes into coherent switching process in FePt/C/Fe films giving rise to a single hysteresis loop. High temperature magnetic studies up to 573 K reveal that the effective reduction in the coercivity decreases largely from 34 Oe/K for FePt/Fe film to 13 Oe/K for FePt/C(0.5/Fe film demonstrating that the interlayer exchange coupling seems to be a promising approach to improve the stability of hard magnetic properties at high temperatures, which is suitable for high-performance magnets and thermally assisted magnetic recording media.

  17. FE-based long range ordered alloys

    International Nuclear Information System (INIS)

    Liu, C.-T.; Inouye, H.; Schaffhauser, A.C.

    1981-01-01

    Malleable long range ordered alloys having high critical ordering temperatures exist in the V(Co,Fe) 3 and V(Co,Fe,Ni) 3 system having a specified composition with an electron density no greater than 8.00. Excellent high temperature properties occur in alloys in this system, having specified compositions. The alloys are fabricable by casting, deforming and annealing for sufficient time to provide ordered structure. (author)

  18. Fe-Cr-Ni system alloys

    International Nuclear Information System (INIS)

    Levin, F.L.

    1986-01-01

    Phase diagram of Fe-Cr-Ni system, which is the basic one for production of corrosion resistant alloys, is considered. Data on corrosion resistance of such alloys are correlated depending on a number of factors: quality and composition of modifying elements, corrosion medium, temperature, alloy structure, mechanical and thermal treatment. Grades of Fe-Ni-Cr alloys are presented, and fields of their application are pointed out

  19. Modification of interlayer exchange coupling in Fe/V/Fe trilayers using hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Skoryna, J., E-mail: jskoryna@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 St., 60-179 Poznań (Poland); Marczyńska, A. [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 St., 60-179 Poznań (Poland); Lewandowski, M. [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85 St., 61-614 Poznań (Poland); Smardz, L. [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17 St., 60-179 Poznań (Poland)

    2015-10-05

    Highlights: • Magnetic films and multilayers. • Thin films. • Hydrogen absorbing materials. • Magnetic measurements. • Exchange coupling. - Abstract: Fe/V/Fe trilayers with constant-thickness Fe and step-like wedged V sublayers were prepared at room temperature using UHV magnetron sputtering. The bottom Fe layer grows onto oxidised Si(1 0 0) substrate and shows relatively high coercivity. The top Fe layer grows on vanadium spacer and shows considerably lower coercivity. The planar growth of the Fe and V sublayers was confirmed in-situ by X-ray photoelectron spectroscopy. Results show that the Fe sublayers are weakly exchange coupled for d{sub V} > 1.4 nm. Results on the coercivity studies as a function of the V interlayer thickness show near d{sub V} ∼ 1.95 nm (∼2.45 nm) weak antiferromagnetic (ferromagnetic) coupling, respectively. The hydrogenation of the Fe/V/Fe trilayers leads to increase of the strength of the ferromagnetic interlayer exchange coupling.

  20. Electronic structures and magnetism of CaFeAsH and CaFeAsF

    International Nuclear Information System (INIS)

    Wang Guangtao; Shi Xianbiao; Liu Haipeng; Liu Qingbo

    2015-01-01

    We studied the electronic structures, magnetism, and Fermi surface (FS) nesting of CaFeAsH and CaFeAsF by first-principles calculations. In the nonmagnetic (NM) states, we found strong FS nesting, which induces magnetic instability and a spin density wave (SDW). Our calculations indicate that the ground state of CaFeAsH and CaFeAsF is the stripe antiferromagnetic state. The calculated bare susceptibility χ 0 (q) peaked at the M-point and was clearly suppressed and became slightly incommensurate with both electron doping and hole doping for both materials. (author)

  1. Laser pyrolysis fabrication of ferromagnetic gamma'-Fe4N and FeC nanoparticles

    Science.gov (United States)

    Grimes, C. A.; Qian, D.; Dickey, E. C.; Allen, J. L.; Eklund, P. C.

    2000-01-01

    Using the laser pyrolysis method, single phase gamma'-Fe4N nanoparticles were prepared by a two step method involving preparation of nanoscale iron oxide and a subsequent gas-solid nitridation reaction. Single phase Fe3C and Fe7C3 could be prepared by laser pyrolysis from Fe(CO)5 and 3C2H4 directly. Characterization techniques such as XRD, TEM and vibrating sample magnetometer were used to measure phase structure, particle size and magnetic properties of these nanoscale nitride and carbide particles. c2000 American Journal of Physics.

  2. Magnetic and structural characterizations on nanoparticles of FePt, FeRh and their composites

    International Nuclear Information System (INIS)

    Ko, Hnin Yu Yu; Suzuki, Takao; Nam, Nguyen T.; Phuoc, Nguyen N.; Cao Jiangwei; Hirotsu, Yoshihiko

    2008-01-01

    The various compositions of FePt and FeRh nanoparticles, and their composite particles have been fabricated by the solution-phase chemical method and their magnetic properties characterized. High-resolution transmission electron microscopic observations indicate that mono-dispersed FeRh and FePt/FeRh nanoparticles are fabricated with the average size of 3-5 nm. However, larger size particles are distributed in the annealed state. From X-ray diffraction results, the as-deposited FeRh nanoparticles reveal a chemically disordered fcc structure which can be transformed into CsCl-type structure through thermal annealing. Similarly, the annealed FePt nanoparticles show the L1 0 -phase fct structure although the fcc structure is apparent in the as-deposited state. It is also found that the first time in the exchange bias effect in the composite of ferromagnetic (FePt) and anti-ferromagnetic (FeRh) nanoparticles; result in a shift of the hysteresis loop after field cooling process

  3. Magnetic properties of Fe-oxide and (Fe, Co) oxide nanoparticles synthesized in polystyrene resin matrix

    Science.gov (United States)

    Rodak, D.; Kroll, E.; Tsoi, G. M.; Vaishnava, P. P.; Naik, R.; Wenger, L. E.; Suryanarayanan, R.; Naik, V. M.; Boolchand, P.

    2003-03-01

    Magnetic nanoparticles have potential applications ranging from drug delivery and imaging in the medical field to sensing and memory storage in technology. The preparation, structure, and physical properties of iron oxide-based nanoparticles synthesized by ion exchange in a polystyrene resin matrix have been investigated. Employing a synthesis method developed originally by Ziolo, et. al^1, nanoparticles were prepared in a sulfonated divinyl benzene polystyrene resin matrix using various aqueous solutions of (1) FeCl_2, (2) FeCl_3, (3) FeCl2 : 2FeCl3 , (4) 9FeCl2 : CoCl_2, and (5) 4FeCl2 : CoCl_2. Powder x-ray diffraction measurements were used to identify the phases present while transmission electron microscopy was used for particle size distribution determinations. SQUID magnetization measurements (field-cooled and zero-field-cooled) and Fe^57 Mössbauer effect measurements indicate the presence of ferromagnetic iron oxide phases and a superparamagnetic behavior with blocking temperatures (T_B) varying from 50 K to room temperature. Nanoparticles synthesized using a stoichiometric mixture of FeCl2 and FeCl3 exhibit the lowest TB and smallest particle size distribution. The Mössbauer effect measurements have also been used to identify the iron oxides phases present and their relative amounts in the nanoparticles ^1R.F. Ziolo, et al., Science 207, 219 (1992). *Permanent address: Kettering University, Flint, MI 48504

  4. Synthesis, characterization, and comparative gas-sensing properties of Fe2O3 prepared from Fe3O4 and Fe3O4-chitosan

    International Nuclear Information System (INIS)

    Cuong, Nguyen Duc; Hoa, Tran Thai; Khieu, Dinh Quang; Lam, Tran Dai; Hoa, Nguyen Duc; Van Hieu, Nguyen

    2012-01-01

    Highlights: ► We have demonstrated a facile method to prepare Fe 3 O 4 nanoparticles and chitosan-coated Fe 3 O 4 nanoparticles. ► α-Fe 2 O 3 sensors prepared from those Fe 3 O 4 materials have been investigated and compared. ► The results show potential application of α-Fe 2 O 3 for CO sensors in environmental monitoring. - Abstract: In this paper, Fe 3 O 4 and chitosan (CS)-coated Fe 3 O 4 nanoparticles were synthesized via co-precipitation method and subsequent covalent binding of CS onto the surface for functionalization, respectively. Characterization of the crystal structures and morphologies of as-synthesized nanoparticles by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy demonstrated that Fe 3 O 4 had a cubic spinal structure with irregular shapes and average diameters of 10–20 nm. The surface states and magnetic properties of Fe 3 O 4 -CS nanoparticles were characterized by Fourier transform infrared spectra and vibrating sample magnetometry. Results showed that Fe 3 O 4 -CS nanoparticles possessed super-paramagnetic properties, with saturated magnetization up to 60 emu/g. In addition, Fe 3 O 4 and CS-coated Fe 3 O 4 nanoparticles were used in the fabrication of α-Fe 2 O 3 based gas sensors. Gas sensing measurements revealed that the α-Fe 2 O 3 gas sensor prepared from Fe 3 O 4 -CS had a better response to H 2 , CO, C 2 H 5 OH, and NH 3 compared with the device prepared from pristine Fe 3 O 4 . Furthermore, the α-Fe 2 O 3 sensor prepared from Fe 3 O 4 -CS nanoparticles exhibited the highest response to CO among the test gases, suggesting that it has great potential for practical applications in environmental monitoring.

  5. Studies of an Fe9 tridiminished icosahedron.

    Science.gov (United States)

    Tolis, Evangelos I; Engelhardt, Larry P; Mason, Pamela V; Rajaraman, Gopalan; Kindo, Koichi; Luban, Marshall; Matsuo, Akira; Nojiri, Hiroyuki; Raftery, James; Schröder, Christian; Timco, Grigore A; Tuna, Floriana; Wernsdorfer, Wolfgang; Winpenny, Richard E P

    2006-12-04

    The synthesis and structural characterization of a nonanuclear FeIII cage complex is reported. The nine iron centers in [Fe9(mu3-O)4(O3PPh)3(O2CCMe3)13] lie on the vertices of an incomplete icosahedron, with the P atoms of triphenylphosphonate at the other three vertices. The paramagnetic core therefore describes a tridiminished icosahedron. Magnetic studies suggest an S=1/2 ground state for the molecule. Analysis of exchange paths and the susceptibility data point to the interpretation that the cluster can be divided into two nearly decoupled sections: an {Fe6O3} section, with an S=0 ground state, in which three oxo-centered triangles bound a central triangle that is not oxo-centered; and an {Fe3O} triangle with S=1/2. The analysis of the susceptibility data leads to a Heisenberg model based on three significant antiferromagnetic exchange interactions, with values of 173.7 cm-1 in the {Fe3O} triangle, and 30.9 and 19.1 cm-1 within the {Fe6O3} section, while the exchange between them is <1 cm-1. With these assignments, the theoretical low-temperature differential susceptibility is also in very good agreement with measurements up to 50 T. Magnetic measurements in the milli-kelvin range reveal striking hysteresis loops and magnetization reversals associated with a Landau-Zener-Stückelberg (LZS) transition as enhanced by the occurrence of a phonon bottleneck.

  6. In situ study on the formation of FeTe

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Wulff, Anders Christian; Yue, Zhao

    2011-01-01

    The formation of the FeTe compound from a mixture of Fe and Te powders was studied in situ by means of high-energy synchrotron X-ray diffraction. FeTe does not form directly from the starting elements; instead, FeTe2 forms as an intermediate product. During a 2 °C/min heating ramp, Te first reacts...

  7. Surface magnetism of Fe(001)

    International Nuclear Information System (INIS)

    Ohnishi, S.; Freeman, A.J.; Weinert, M.

    1983-01-01

    Results of all-electron self-consistent semirelativistic full-potential linearized augmented-plane-wave local-density and local-spin-density studies are reported for a seven-layer Fe(001) thin film. The calculated work function for the ferromagnetic state is found to be in excellent agreement with experiment, whereas that calculated for the paramagnetic state is significantly worse (namely, 0.5 eV too large), indicating the importance of spin polarization on this electrostatic property. For both states, partial densities of states (projected by layer and by orbital angular momentum), surface states, and charge (and spin) densities are presented and their differences employed to discuss the origin of surface magnetism. No Friedel oscillation is found in the layer-by-layer charge density. The surface-layer magnetic moment is found to have been increased by 0.73μ/sub B/ from the center layer to 2.98μ/sub B//atom; a very small Friedel oscillation is obtained for the spin density, which indicates possible size effects in this seven-layer film. Layer-by-layer Fermi contact hyperfine fields are presented: While the core-polarization contributions are proportional to the magnetic moment, the conduction-electron contribution shows a pronounced Friedel oscillation in the central layer and, significantly, a change of sign and increase in the magnitude for the surface-layer contribution. The hyperfine field at the nucleus of the center-layer atoms is found to be in excellent agreement with experiment

  8. Physical conditions in CaFe interstellar clouds

    OpenAIRE

    Gnacinski, P.; Krogulec, M.

    2007-01-01

    Interstellar clouds that exhibit strong Ca I and Fe I lines were called CaFe clouds. The ionisation equilibrium equations were used to model the column densities of Ca II, Ca I, K I, Na I, Fe I and Ti II in CaFe clouds. The chemical composition of CaFe clouds is that of the Solar System and no depletion of elements onto dust grains is seen. The CaFe clouds have high electron densities n=1 cm^-3 that leads to high column densities of neutral Ca and Fe.

  9. Binder Jetting: A Novel NdFeB Bonded Magnet Fabrication Process

    Science.gov (United States)

    Paranthaman, M. Parans; Shafer, Christopher S.; Elliott, Amy M.; Siddel, Derek H.; McGuire, Michael A.; Springfield, Robert M.; Martin, Josh; Fredette, Robert; Ormerod, John

    2016-07-01

    The goal of this research is to fabricate near-net-shape isotropic (Nd)2Fe14B-based (NdFeB) bonded magnets using a three dimensional printing process to compete with conventional injection molding techniques used for bonded magnets. Additive manufacturing minimizes the waste of critical materials and allows for the creation of complex shapes and sizes. The binder jetting process works similarly to an inkjet printer. A print-head passes over a bed of NdFeB powder and deposits a polymer binding agent to bind the layer of particles together. The bound powder is then coated with another layer of powder, building the desired shape in successive layers of bonded powder. Upon completion, the green part and surrounding powders are placed in an oven at temperatures between 100°C and 150°C for 4-6 h to cure the binder. After curing, the excess powder can be brushed away to reveal the completed "green" part. Green magnet parts were then infiltrated with a clear urethane resin to achieve the measured density of the magnet of 3.47 g/cm3 close to 46% relative to the NdFeB single crystal density of 7.6 g/cm3. Magnetic measurements indicate that there is no degradation in the magnetic properties. This study provides a new pathway for preparing near-net-shape bonded magnets for various magnetic applications.

  10. Fe-Impregnated Mineral Colloids for Peroxide Activation: Effects of Mineral Substrate and Fe Precursor.

    Science.gov (United States)

    Li, Yue; Machala, Libor; Yan, Weile

    2016-02-02

    Heterogeneous iron species at the mineral/water interface are important catalysts for the generation of reactive oxygen species at circumneutral pH. One significant pathway leading to the formation of such species arises from deposition of dissolved iron onto mineral colloids due to changes in redox conditions. This study investigates the catalytic properties of Fe impregnated on silica, alumina, and titania nanoparticles (as prototypical mineral colloids). Fe impregnation was carried out by immersing the mineral nanoparticles in dilute Fe(II) or Fe(III) solutions at pH 6 and 3, respectively, in an aerobic environment. The uptake of iron per unit surface area follows the order of nTiO2 > nAl2O3 > nSiO2 for both types of Fe precursors. Impregnation of mineral particles in Fe(II) solutions results in predominantly Fe(III) species due to efficient surface-mediated oxidation. The catalytic activity of the impregnated solids to produce hydroxyl radical (·OH) from H2O2 decomposition was evaluated using benzoic acid as a probe compound under dark conditions. Invariably, the rates of benzoic acid oxidation with different Fe-laden particles increase with the surface density of Fe until a critical density above which the catalytic activity approaches a plateau, suggesting active Fe species are formed predominantly at low surface loadings. The critical surface density of Fe varies with the mineral substrate as well as the aqueous Fe precursor. Fe impregnated on TiO2 exhibits markedly higher activity than its Al2O3 and SiO2 counterparts. The speciation of interfacial Fe is analyzed with diffuse reflectance UV-vis analysis and interpretation of the data in the context of benzoic oxidation rates suggests that the surface activity of the solids for ·OH generation correlates strongly with the isolated (i.e., mononuclear) Fe species. Therefore, iron dispersed on mineral colloids is a significant form of reactive iron surfaces in the aquatic environment.

  11. Fe biomineralization mirrors individual metabolic activity in a nitrate-dependent Fe(II-oxidizer

    Directory of Open Access Journals (Sweden)

    Jennyfer eMIOT

    2015-09-01

    Full Text Available Microbial biomineralization sometimes leads to periplasmic encrustation, which is predicted to enhance microorganism preservation in the fossil record. Mineral precipitation within the periplasm is however thought to induce death, as a result of permeability loss preventing nutrient and waste transit across the cell wall. This hypothesis had however never been investigated down to the single cell level. Here, we cultured the nitrate reducing Fe(II oxidizing bacteria Acidovorax sp. strain BoFeN1 that have been previously shown to promote the precipitation of a diversity of Fe minerals (lepidocrocite, goethite, Fe phosphate encrusting the periplasm. We investigated the connection of Fe biomineralization with carbon assimilation at the single cell level, using a combination of electron microscopy and Nano-Secondary Ion Mass Spectrometry (NanoSIMS. Our analyses revealed strong individual heterogeneities of Fe biomineralization. Noteworthy, a small proportion of cells remaining free of any precipitate persisted even at advanced stages of biomineralization. Using pulse chase experiments with 13C-acetate, we provide evidences of individual phenotypic heterogeneities of carbon assimilation, correlated with the level of Fe biomineralization. Whereas non- and moderately encrusted cells were able to assimilate acetate, higher levels of periplasm encrustation prevented any carbon incorporation. Carbon assimilation only depended on the level of Fe encrustation and not on the nature of Fe minerals precipitated in the cell wall. Carbon assimilation decreased exponentially with increasing cell-associated Fe content. Persistence of a small proportion of non-mineralized and metabolically active cells might constitute a strategy of survival in highly ferruginous environments. Eventually, our results suggest that periplasmic Fe biomineralization may provide a signature of individual metabolic status, which could be looked for in the fossil record and in modern

  12. Comparison of Microstructural and Morphological Properties of Electrodeposited Fe-Cu Thin Films with Low and High Fe : Cu Ratio

    Directory of Open Access Journals (Sweden)

    Umut Sarac

    2013-01-01

    Full Text Available Fe-Cu films with low and high Fe : Cu ratio have been produced from the electrolytes with different Fe ion concentrations at a constant deposition potential of −1400 mV versus saturated calomel electrode (SCE by electrodeposition technique onto indium tin oxide (ITO coated conducting glass substrates. It was observed that the variation of Fe ion concentration in the electrolyte had a very strong influence on the compositional, surface morphological, and microstructural properties of the Fe-Cu films. An increase in the Fe ion concentration within the plating bath increased the Fe content, consequently Fe : Cu ratio within the films. The crystallographic structure analysis showed that the Fe-Cu films had a mixture of face-centered cubic (fcc Cu and body centered cubic (bcc α-Fe phases. The average crystallite size decreased with the Fe ion concentration. The film electrodeposited from the electrolyte with low Fe ion concentration exhibited a morphology consisting of dendritic structures. However, the film morphology changed from dendritic structure to cauliflower-like structure at high Fe ion concentration. The surface roughness and grain size were found to decrease significantly with increasing Fe ion concentration in the electrolyte. The significant differences observed in the microstructural and morphological properties caused by the change of Fe ion concentration in the electrolyte were ascribed to the change of Fe : Cu ratio within the films.

  13. Defect chemistry and oxygen transport of (La0.6Sr0.4 − xMx)0.99Co0.2Fe0.8O3 − δ, M = Ca (x = 0.05, 0.1), Ba (x = 0.1, 0.2), Sr: Part II: Oxygen transport

    DEFF Research Database (Denmark)

    Dalslet, Bjarke Thomas; Søgaard, Martin; Hendriksen, Peter Vang

    2009-01-01

    , the findings on the defect chemistry were reported, while the oxygen transport properties are reported here in part II. In the investigated material series, the amount of divalent dopant has been kept constant, while Sr ions have been substituted with Ca ions (smaller ionic radius) or Ba ions (larger ionic...... radius). The size difference induces different strains into the crystal structure in each composition. The possibility of simple relationships between various crystal strain parameters and the transport properties were analyzed. Oxygen pump controlled permeation experiments and a surface sensitive...

  14. Chemically abrupt interface between Ce oxide and Fe films

    International Nuclear Information System (INIS)

    Lee, H.G.; Lee, D.; Kim, S.; Kim, S.G.; Hwang, Chanyong

    2005-01-01

    A chemically abrupt Fe/Ce oxide interface can be formed by initial oxidation of an Fe film followed by deposition of Ce metal. Once a Ce oxide layer is formed on top of Fe, it acts a passivation barrier for oxygen diffusion. Further deposition of Ce metal followed by its oxidation preserve the abrupt interface between Ce oxide and Fe films. The Fe and Ce oxidation states have been monitored at each stage using X-ray photoelectron spectroscopy

  15. In situ observation of the formation of FeSe

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Wulff, Anders Christian; Yue, Zhao

    2011-01-01

    The formation of the FeSe compound from a mixture of Fe and Se powders encased in a composite Cu/Nb sheath was studied in situ by means of high-energy synchrotron x-ray diffraction. Tetragonal beta-FeSe does not seem to form directly from the starting elements. Instead, a sequence of FeSe2, Fe3Se4...

  16. Soft magnetic properties of hybrid ferromagnetic films with CoFe, NiFe, and NiFeCuMo layers

    International Nuclear Information System (INIS)

    Choi, Jong-Gu; Hwang, Do-Guwn; Rhee, Jang-Roh; Lee, Sang-Suk

    2011-01-01

    Two-layered ferromagnetic alloy films (NiFe and CoFe) with intermediate NiFeCuMo soft magnetic layers of different thicknesses were investigated to understand the relationship between coercivity and magnetization process by taking into account the strength of hard-axis saturation field. The thickness dependence of H EC (easy-axis coercivity), H HS (hard-axis saturation field), and χ (susceptibility) of the NiFeCuMo thin films in glass/Ta(5 nm)/[CoFe or NiFe(5 nm-t/2)]/NiFeCuMo(t = 0, 4, 6, 8, 10 nm)/[CoFe or NiFe(5 nm-t/2)]/Ta(5 nm) films prepared using the ion beam deposition method was determined. The magnetic properties (H EC , H HS , and χ) of the ferromagnetic CoFe, NiFe three-layers with an intermediate NiFeCuMo super-soft magnetic layer were strongly dependent on the thickness of the NiFeCuMo layer.

  17. Connecting [NiFe]- and [FeFe]-hydrogenases: mixed-valence nickel-iron dithiolates with rotated structures.

    Science.gov (United States)

    Schilter, David; Rauchfuss, Thomas B; Stein, Matthias

    2012-08-20

    New mixed-valence iron-nickel dithiolates are described that exhibit structures similar to those of mixed-valence diiron dithiolates. The interaction of tricarbonyl salt [(dppe)Ni(pdt)Fe(CO)(3)]BF(4) ([1]BF(4), where dppe = Ph(2)PCH(2)CH(2)PPh(2) and pdt(2-) = -SCH(2)CH(2)CH(2)S-) with P-donor ligands (L) afforded the substituted derivatives [(dppe)Ni(pdt)Fe(CO)(2)L]BF(4) incorporating L = PHCy(2) ([1a]BF(4)), PPh(NEt(2))(2) ([1b]BF(4)), P(NMe(2))(3) ([1c]BF(4)), P(i-Pr)(3) ([1d]BF(4)), and PCy(3) ([1e]BF(4)). The related precursor [(dcpe)Ni(pdt)Fe(CO)(3)]BF(4) ([2]BF(4), where dcpe = Cy(2)PCH(2)CH(2)PCy(2)) gave the more electron-rich family of compounds [(dcpe)Ni(pdt)Fe(CO)(2)L]BF(4) for L = PPh(2)(2-pyridyl) ([2a]BF(4)), PPh(3) ([2b]BF(4)), and PCy(3) ([2c]BF(4)). For bulky and strongly basic monophosphorus ligands, the salts feature distorted coordination geometries at iron: crystallographic analyses of [1e]BF(4) and [2c]BF(4) showed that they adopt "rotated" Fe(I) centers, in which PCy(3) occupies a basal site and one CO ligand partially bridges the Ni and Fe centers. Like the undistorted mixed-valence derivatives, members of the new class of complexes are described as Ni(II)Fe(I) (S = ½) systems according to electron paramagnetic resonance spectroscopy, although with attenuated (31)P hyperfine interactions. Density functional theory calculations using the BP86, B3LYP, and PBE0 exchange-correlation functionals agree with the structural and spectroscopic data, suggesting that the spin for [1e](+) is mostly localized in a Fe(I)-centered d(z(2)) orbital, orthogonal to the Fe-P bond. The PCy(3) complexes, rare examples of species featuring "rotated" Fe centers, both structurally and spectroscopically incorporate features from homobimetallic mixed-valence diiron dithiolates. Also, when the NiS(2)Fe core of the [NiFe]-hydrogenase active site is reproduced, the "hybrid models" incorporate key features of the two major classes of hydrogenase. Furthermore, cyclic

  18. Electronic Properties of LiFePO4 and Li doped LiFePO4

    International Nuclear Information System (INIS)

    Zhuang, G.V.; Allen, J.L.; Ross, P.N.; Guo, J.-H.; Jow, T.R.

    2005-01-01

    The potential use of different iron phosphates as cathode materials in lithium-ion batteries has recently been investigated.1 One of the promising candidates is LiFePO4. This compound has several advantages in comparison to the state-of-the-art cathode material in commercial rechargeable lithium batteries. Firstly, it has a high theoretical capacity (170 mAh/g). Secondly, it occurs as mineral triphylite in nature and is inexpensive, thermally stable, non-toxic and non-hygroscopic. However, its low electronic conductivity (∼10-9 S/cm) results in low power capability. There has been intense worldwide research activity to find methods to increase the electronic conductivity of LiFePO4, including supervalent ion doping,2 introducing non-carbonaceous network conduction3 and carbon coating, and the optimization of the carbon coating on LiFePO4 particle surfaces.4 Recently, the Li doped LiFePO4 (Li1+xFe1-xPO4) synthesized at ARL has yield electronic conductivity increase up to 106.5 We studied electronic structure of LiFePO4 and Li doped LiFePO4 by synchrotron based soft X-ray emission (XES) and X-ray absorption (XAS) spectroscopies. XAS probes the unoccupied partial density of states, while XES the occupied partial density of states. By combining XAS and XES measurements, we obtained information on band gap and orbital character of both LiFePO4 and Li doped LiFePO4. The occupied and unoccupied oxygen partial density of states (DOS) of LiFePO4 and 5 percent Li doped LiFePO4 are presented in Fig. 1. Our experimental results clearly indicate that LiFePO4 has wideband gap (∼ 4 eV). This value is much larger than what is predicted by DFT calculation. For 5 percent Li doped LiFePO4, a new doping state was created closer to the Fermi level, imparting p-type conductivity, consistent with thermopower measurement. Such observation substantiates the suggestion that high electronic conductivity in Li1.05Fe0.95 PO4 is due to available number of charge carriers in the material

  19. In situ QXAFS observation of the reduction of Fe2O3 and CaFe2O4

    International Nuclear Information System (INIS)

    Kimura, Masao; Takayama, Toru; Murao, Reiko; Nomura, Masaharu; Uemura, Yohei; Asakura, Kiyotaka

    2013-01-01

    In situ QXAFS studies of the reduction of α-Fe 2 O 3 and CaFe 2 O 4 were conducted to determine their reduction kinetics and mechanisms. The reduction of α-Fe 2 O 3 involved two steps, the first being a very fast process in which Fe 3+ was reduced to Fe 2+ and the second being the reduction of Fe 2+ to Fe metal over a longer period. In contrast, the reduction of Fe in CaFe 2 O 4 was a single first-order reaction, although an induction period was clearly observed at the beginning of the reduction process. The reduction processes were successfully studied using a combination of in situ QXAFS spectra at the Ca and Fe K-edges.

  20. Discovery of Suprathermal Fe+ in and near Earth's Magnetosphere

    Science.gov (United States)

    Christon, S. P.; Hamilton, D. C.; Plane, J. M. C.; Mitchell, D. G.; Grebowsky, J. M.; Spjeldvik, W. N.; Nylund, S. R.

    2017-12-01

    Suprathermal (87-212 keV/e) singly charged iron, Fe+, has been observed in and near Earth's equatorial magnetosphere using long-term ( 21 years) Geotail/STICS ion composition data. Fe+ is rare compared to dominant suprathermal solar wind and ionospheric origin heavy ions. Earth's suprathermal Fe+ appears to be positively associated with both geomagnetic and solar activity. Three candidate lower-energy sources are examined for relevance: ionospheric outflow of Fe+ escaped from ion layers altitude, charge exchange of nominal solar wind Fe+≥7, and/or solar wind transported inner source pickup Fe+ (likely formed by solar wind Fe+≥7 interaction with near sun interplanetary dust particles, IDPs). Semi-permanent ionospheric Fe+ layers form near 100 km altitude from the tons of IDPs entering Earth's atmosphere daily. Fe+ scattered from these layers is observed up to 1000 km altitude, likely escaping in strong ionospheric outflows. Using 26% of STICS's magnetosphere-dominated data at low-to-moderate geomagnetic activity levels, we demonstrate that solar wind Fe charge exchange secondaries are not an obvious Fe+ source then. Earth flyby and cruise data from Cassini/CHEMS, a nearly identical instrument, show that inner source pickup Fe+ is likely not important at suprathermal energies. Therefore, lacking any other candidate sources, it appears that ionospheric Fe+ constitutes at least an important portion of Earth's suprathermal Fe+, comparable to observations at Saturn where ionospheric origin suprathermal Fe+ has also been observed.

  1. Abiotic Deposition of Fe Complexes onto Leptothrix Sheaths

    Science.gov (United States)

    Kunoh, Tatsuki; Hashimoto, Hideki; McFarlane, Ian R.; Hayashi, Naoaki; Suzuki, Tomoko; Taketa, Eisuke; Tamura, Katsunori; Takano, Mikio; El-Naggar, Mohamed Y.; Kunoh, Hitoshi; Takada, Jun

    2016-01-01

    Bacteria classified in species of the genus Leptothrix produce extracellular, microtubular, Fe-encrusted sheaths. The encrustation has been previously linked to bacterial Fe oxidases, which oxidize Fe(II) to Fe(III) and/or active groups of bacterial exopolymers within sheaths to attract and bind aqueous-phase inorganics. When L. cholodnii SP-6 cells were cultured in media amended with high Fe(II) concentrations, Fe(III) precipitates visibly formed immediately after addition of Fe(II) to the medium, suggesting prompt abiotic oxidation of Fe(II) to Fe(III). Intriguingly, these precipitates were deposited onto the sheath surface of bacterial cells as the population was actively growing. When Fe(III) was added to the medium, similar precipitates formed in the medium first and were abiotically deposited onto the sheath surfaces. The precipitates in the Fe(II) medium were composed of assemblies of globular, amorphous particles (ca. 50 nm diameter), while those in the Fe(III) medium were composed of large, aggregated particles (≥3 µm diameter) with a similar amorphous structure. These precipitates also adhered to cell-free sheaths. We thus concluded that direct abiotic deposition of Fe complexes onto the sheath surface occurs independently of cellular activity in liquid media containing Fe salts, although it remains unclear how this deposition is associated with the previously proposed mechanisms (oxidation enzyme- and/or active group of organic components-involved) of Fe encrustation of the Leptothrix sheaths. PMID:27271677

  2. Abiotic Deposition of Fe Complexes onto Leptothrix Sheaths

    Directory of Open Access Journals (Sweden)

    Tatsuki Kunoh

    2016-06-01

    Full Text Available Bacteria classified in species of the genus Leptothrix produce extracellular, microtubular, Fe-encrusted sheaths. The encrustation has been previously linked to bacterial Fe oxidases, which oxidize Fe(II to Fe(III and/or active groups of bacterial exopolymers within sheaths to attract and bind aqueous-phase inorganics. When L. cholodnii SP-6 cells were cultured in media amended with high Fe(II concentrations, Fe(III precipitates visibly formed immediately after addition of Fe(II to the medium, suggesting prompt abiotic oxidation of Fe(II to Fe(III. Intriguingly, these precipitates were deposited onto the sheath surface of bacterial cells as the population was actively growing. When Fe(III was added to the medium, similar precipitates formed in the medium first and were abiotically deposited onto the sheath surfaces. The precipitates in the Fe(II medium were composed of assemblies of globular, amorphous particles (ca. 50 nm diameter, while those in the Fe(III medium were composed of large, aggregated particles (≥3 µm diameter with a similar amorphous structure. These precipitates also adhered to cell-free sheaths. We thus concluded that direct abiotic deposition of Fe complexes onto the sheath surface occurs independently of cellular activity in liquid media containing Fe salts, although it remains unclear how this deposition is associated with the previously proposed mechanisms (oxidation enzyme- and/or active group of organic components-involved of Fe encrustation of the Leptothrix sheaths.

  3. Effect of High Velocity Arc Spraying Parameters on Properties of FeNiCrAl Coating

    Directory of Open Access Journals (Sweden)

    TIAN Haoliang

    2016-12-01

    Full Text Available FeNiCrAl coating is a kind of surface wear resistant material for shaft parts. Microstructure, adhesive strength, phase composition and microhardness were analyzed in order to study the influence mechanism of spraying parameters on coating properties. The relation among the spraying current, coating microstructure and cohesive strength was studied in detail. The results shown that the spraying current is very important to obtain the dense coating (porosity of 8.76% with cohesive strength of 52.3 MPa and an excellent coating is prepared by spraying current 200 A, spraying voltage 34 V and spraying distance 160 mm. The hardness of coating is 626 HV0.1 and about 1.6 times as that of the matrix. The effective mechanism is relevant to the scatter distribution of the Fe-Al intermetallic compound and Cr0.19Fe0.1Ni0.11 solution in the coating.

  4. Nb-Based Nb-Al-Fe Alloys: Solidification Behavior and High-Temperature Phase Equilibria

    Science.gov (United States)

    Stein, Frank; Philips, Noah

    2018-03-01

    High-melting Nb-based alloys hold significant promise for the development of novel high-temperature materials for structural applications. In order to understand the effect of alloying elements Al and Fe, the Nb-rich part of the ternary Nb-Al-Fe system was investigated. A series of Nb-rich ternary alloys were synthesized from high-purity Nb, Al, and Fe metals by arc melting. Solidification paths were identified and the liquidus surface of the Nb corner of the ternary system was established by analysis of the as-melted microstructures and thermal analysis. Complementary analysis of heat-treated samples yielded isothermal sections at 1723 K and 1873 K (1450 °C and 1600 °C).

  5. Magnetic structure of molecular magnet Fe[Fe(CN)6]·4H2O

    Indian Academy of Sciences (India)

    Abstract. We have studied the magnetic structure of Fe[Fe(CN)6]·4H2O, prepared by precipitation method, using neutron diffraction technique. Temperature dependent DC magnetization study down to 4.2 K shows that the compound undergoes from a high tem- perature disordered (paramagnetic) to an ordered magnetic ...

  6. Magnetic structure of molecular magnet Fe [Fe (CN) 6]· 4H2O

    Indian Academy of Sciences (India)

    We have studied the magnetic structure of Fe[Fe(CN)6]·4H2O, prepared by precipitation method, using neutron diffraction technique. Temperature dependent DC magnetization study down to 4.2 K shows that the compound undergoes from a high temperature disordered (paramagnetic) to an ordered magnetic phase ...

  7. Adhesive and Cohesive Strength in FeB/Fe2B Systems

    Science.gov (United States)

    Meneses-Amador, A.; Blancas-Pérez, D.; Corpus-Mejía, R.; Rodríguez-Castro, G. A.; Martínez-Trinidad, J.; Jiménez-Tinoco, L. F.

    2018-01-01

    In this work, FeB/Fe2B systems were evaluated by the scratch test. The powder-pack boriding process was performed on the surface of AISI M2 steel. The mechanical parameters, such as yield stress and Young's modulus of the boride layer, were obtained by the instrumented indentation technique. Residual stresses produced on the boride layer were estimated by using the x-ray diffraction (XRD) technique. The scratch test was performed in order to evaluate the cohesive/adhesive strength of the FeB/Fe2B coating. In addition, a numerical evaluation of the scratch test on boride layers was performed by the finite element method. Maximum principal stresses were related to the failure mechanisms observed by the experimental scratch test. Shear stresses at the interfaces of the FeB/Fe2B/substrate system were also evaluated. Finally, the results obtained provide essential information about the effect of the layer thickness, the residual stresses, and the resilience modulus on the cohesive/adhesive strength in FeB/Fe2B systems.

  8. Role of aluminium addition on structure of Fe substituted Fe73·5 ...

    Indian Academy of Sciences (India)

    Of many elements added to Finemet, substitution of small amount of Al in place of Fe/Si was found to reduce magne- .... A straight line is drawn by regression analysis and extrapolated up to zero value of N–R function. .... of replacement of Si with Al. The decrease in magnetization beyond 4 at% Al may be attributed to the Fe ...

  9. Photocatalytic degradation of methylene blue by nanostructured Fe/FeS powder under visible light

    Science.gov (United States)

    Esmaili, Hassan; Kotobi, Amir; Sheibani, Saeed; Rashchi, Fereshteh

    2018-02-01

    The photocatalytic performance of mechano-thermally synthesized Fe/FeS nanostructures formed from micron-sized starting materials was compared with that of a thermally synthesized nanostructure with nano-sized precursors in this paper. The properties of as-synthesized materials were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), diffuse reflectance spectroscopy (DRS), and ultraviolet-visible (UV-Vis) spectroscopy. The effects of irradiation time, methylene blue (MB) concentration, catalyst dosage, and pH value upon the degradation of MB were studied. Magnetic properties of the samples showed that both as-synthesized Fe/FeS photocatalysts are magnetically recoverable, eliminating the need for conventional filtration steps. Degradation of 5 ppm of the MB solution by mechano-thermally synthesized Fe/FeS with a photocatalyst dosage of 1 kg/m3 at pH 11 can reach 96% after 12 ks irradiation under visible light. The photocatalytic efficiency is higher in alkaline solution. The kinetics of photocatalytic degradation in both samples is controlled by a first-order reaction. However, the rate-constant value in the thermally synthesized Fe/FeS photocatalyst sample is only 1.5 times greater than that of the mechano-thermally synthesized one.

  10. 57Fe Moessbauer study of (Er1-xYx)2Fe14B spin reorientation

    International Nuclear Information System (INIS)

    Garitaonandia, J.S.; Barandiaran, J.M.; Orue, I.; Plazaola, F.; Ibarra, M.R.; Moral, A. del

    1995-01-01

    The 57 Fe Moessbauer spectra for (Er 1-x Y x ) 2 Fe 14 B compounds have been measured around the spin reorientation temperature and at reference temperature of 331 K, where all the samples have the same easy magnetization direction. This allows us to study the Y dilution and spin reorientation influence on the hyperfine parameters. ((orig.))

  11. 57Fe Mössbauer study of new multiferroic AgFeO2

    Science.gov (United States)

    Presniakov, I.; Rusakov, V.; Sobolev, A.; Gapochka, A.; Matsnev, M.; Belik, A. A.

    2014-04-01

    The present work reports results of the 57Fe Mössbauer measurements on AgFeO2 powder sample recorded at various temperatures including the points of both magnetic phase transitions. The 57Fe Mössbauer spectra of AgFeO2 measured in the paramagnetic range ( T > T N1) consist of one quadrupole doublet with rather high quadrupole splitting of Δ300 K = 0.66 ± 0.01 mm/s for Fe3+ ions. In order to predict the sign of electric field gradient (EFG) at 57Fe nuclei, we calculated the lattice contribution to the electric field gradient (EFG) at 57Fe nuclei, which emphasized the importance of the dipolar contributions, with resultant oxygen polarizabilities in the range of α O = 0.83 Å3, in agreement with the results obtained previously for other delafossite-like oxides. In the temperature range of T N2 AgFeO2 at T < T N2. The obtained data were analysed in comparison with published data on Mössbauer studies of oxide multiferroics.

  12. Diffusivity of Al and Fe near the diffusion bonding interface of Fe3Al ...

    Indian Academy of Sciences (India)

    Unknown

    Diffusivity of Al and Fe near the diffusion bonding interface of Fe3Al with low carbon steel. LI YAJIANG*†, WANG JUAN†, YIN YANSHENG† and MA HAIJUN†. *Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, China. †National Key Lab of Advanced Welding ...

  13. Fe(II) oxidation kinetics and Fe hydroxyphosphate precipitation upon aeration of anaerobic (ground)water

    NARCIS (Netherlands)

    van der Grift, B.|info:eu-repo/dai/nl/373433484; Griffioen, J.|info:eu-repo/dai/nl/091129265; Behrends, T.|info:eu-repo/dai/nl/30484358X; Wassen, M.J.|info:eu-repo/dai/nl/07165710X; Schot, P.P.|info:eu-repo/dai/nl/08071563X; Osté, Leonard

    2015-01-01

    Exfiltration of anaerobic Fe-rich groundwater into surface water plays an important role in controlling the transport of phosphate (P) from agricultural areas to the sea. Previous laboratory and field studies showed that Fe(II) oxidation upon aeration leads to effective immobilization of dissolved P

  14. Green synthesis of Fe0 and bimetallic Fe0 for oxidative catalysis and reduction applications

    Science.gov (United States)

    A single-step green approach to the synthesis of nanoscale zero valent iron (nZVI) and nanoscale bimetallic (Fe0/Pd) particles using tea (Camellia sinensis) polyphenols is described. The expedient reaction between polyphenols and ferric chloride (FeCl3) occurs within a minute at ...

  15. Role of aluminium addition on structure of Fe substituted Fe73·5 ...

    Indian Academy of Sciences (India)

    4, August 2013, pp. 613–618. c Indian Academy of Sciences. Role of aluminium addition on structure of Fe substituted. Fe73·5−xSi13·5B9Nb3Cu1Alx alloy ribbons. GAUTAM AGARWAL, HIMANSHU AGRAWAL, M SRINIVAS†, B MAJUMDAR. ∗,†† and. N K MUKHOPADHYAY. Department of Metallurgical Engineering, ...

  16. A synthetic system links FeFe-hydrogenases to essential E. coli sulfur metabolism

    Directory of Open Access Journals (Sweden)

    Grandl Gerald

    2011-05-01

    Full Text Available Abstract Background FeFe-hydrogenases are the most active class of H2-producing enzymes known in nature and may have important applications in clean H2 energy production. Many potential uses are currently complicated by a crucial weakness: the active sites of all known FeFe-hydrogenases are irreversibly inactivated by O2. Results We have developed a synthetic metabolic pathway in E. coli that links FeFe-hydrogenase activity to the production of the essential amino acid cysteine. Our design includes a complementary host strain whose endogenous redox pool is insulated from the synthetic metabolic pathway. Host viability on a selective medium requires hydrogenase expression, and moderate O2 levels eliminate growth. This pathway forms the basis for a genetic selection for O2 tolerance. Genetically selected hydrogenases did not show improved stability in O2 and in many cases had lost H2 production activity. The isolated mutations cluster significantly on charged surface residues, suggesting the evolution of binding surfaces that may accelerate hydrogenase electron transfer. Conclusions Rational design can optimize a fully heterologous three-component pathway to provide an essential metabolic flux while remaining insulated from the endogenous redox pool. We have developed a number of convenient in vivo assays to aid in the engineering of synthetic H2 metabolism. Our results also indicate a H2-independent redox activity in three different FeFe-hydrogenases, with implications for the future directed evolution of H2-activating catalysts.

  17. Role of aluminium addition on structure of Fe substituted Fe73· 5 ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Home; Journals; Bulletin of Materials Science; Volume 36; Issue 4. Role of aluminium addition on structure of Fe substituted Fe73.5−Si13.5B9Nb3Cu1Al alloy ribbons. Gautam Agarwal Himanshu Agrawal M Srinivas B Majumdar N K Mukhopadhyay. Volume 36 Issue 4 August 2013 pp 613-618 ...

  18. Fe hydroxyphosphate precipitation and Fe(II) oxidation kinetics upon aeration of Fe(II) and phosphate-containing synthetic and natural solutions

    Science.gov (United States)

    van der Grift, B.; Behrends, T.; Osté, L. A.; Schot, P. P.; Wassen, M. J.; Griffioen, J.

    2016-08-01

    Exfiltration of anoxic Fe-rich groundwater into surface water and the concomitant oxidative precipitation of Fe are important processes controlling the transport of phosphate (PO4) from agricultural areas to aquatic systems. Here, we explored the relationship between solution composition, reaction kinetics, and the characteristics of the produced Fe hydroxyphosphate precipitates in a series of aeration experiments with anoxic synthetic water and natural groundwater. A pH stat device was used to maintain constant pH and to record the H+ production during Fe(II) oxidation in the aeration experiments in which the initial aqueous P/Fe ratios ((P/Fe)ini), oxygen concentration and pH were varied. In general, Fe(II) oxidation proceeded slower in the presence of PO4 but the decrease of the PO4 concentration during Fe(II) oxidation due to the formation of Fe hydroxyphosphates caused additional deceleration of the reaction rate. The progress of the reaction could be described using a pseudo-second-order rate law with first-order dependencies on PO4 and Fe(II) concentrations. After PO4 depletion, the Fe(II) oxidation rates increased again and the kinetics followed a pseudo-first-order rate law. The first-order rate constants after PO4 depletion, however, were lower compared to the Fe(II) oxidation in a PO4-free solution. Hence, the initially formed Fe hydroxyphosphates also affect the kinetics of continuing Fe(II) oxidation after PO4 depletion. Presence of aqueous PO4 during oxidation of Fe(II) led to the formation of Fe hydroxyphosphates. The P/Fe ratios of the precipitates ((P/Fe)ppt) and the recorded ratio of H+ production over decrease in dissolved Fe(II) did not change detectably throughout the reaction despite a changing P/Fe ratio in the solution. When (P/Fe)ini was 0.9, precipitates with a (P/Fe)ppt ratio of about 0.6 were formed. In experiments with (P/Fe)ini ratios below 0.6, the (P/Fe)ppt decreased with decreasing (P/Fe)ini and pH value. Aeration experiments with

  19. Study the microstructure of three and four component phases in Al-Ni-Fe-La alloys

    KAUST Repository

    Kolobylina, Natalia

    2016-12-21

    ones have a form of a δ -layers and they are Al3.2Fe1–Ni ternary compound with a Al3.2Fe structure type. Second ones were point defects, which are La vacancies. The experimental part of this work was partially done on the equipment of the Resource Center of Probe and Electron Microscopy (Kurchatov Complex of NBICS-Technologies, NRC “Kurchatov Institute”)

  20. Accumulation of Fe oxyhydroxides in the Peruvian oxygen deficient zone implies non-oxygen dependent Fe oxidation

    Science.gov (United States)

    Heller, Maija I.; Lam, Phoebe J.; Moffett, James W.; Till, Claire P.; Lee, Jong-Mi; Toner, Brandy M.; Marcus, Matthew A.

    2017-08-01

    Oxygen minimum zones (OMZs) have been proposed to be an important source of dissolved iron (Fe) into the interior ocean. However, previous studies in OMZs have shown a sharp decrease in total dissolved Fe (dFe) and/or dissolved Fe(II) (dFe(II)) concentrations at the shelf-break, despite constant temperature, salinity and continued lack of oxygen across the shelf-break. The loss of both total dFe and dFe(II) suggests a conversion of the dFe to particulate form, but studies that have coupled the reduction-oxidation (redox) speciation of both dissolved and particulate phases have not previously been done. Here we have measured the redox speciation and concentrations of both dissolved and particulate forms of Fe in samples collected during the U.S. GEOTRACES Eastern tropical Pacific Zonal Transect (EPZT) cruise in 2013 (GP16). This complete data set allows us to assess possible mechanisms for loss of dFe. We observed an offshore loss of dFe(II) within the oxygen deficient zone (ODZ), where dissolved oxygen is undetectable, accompanied by an increase in total particulate Fe (pFe). Total pFe concentrations were highest in the upper ODZ. X-ray absorption spectroscopy revealed that the pFe maximum was primarily in the Fe(III) form as Fe(III) oxyhydroxides. The remarkable similarity in the distributions of total particulate iron and nitrite suggests a role for nitrite in the oxidation of dFe(II) to pFe(III). We present a conceptual model for the rapid redox cycling of Fe that occurs in ODZs, despite the absence of oxygen.

  1. [{sup 18}F]FE-SUPPY and [{sup 18}F]FE-SUPPY:2 - metabolic considerations

    Energy Technology Data Exchange (ETDEWEB)

    Haeusler, Daniela [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna, A-1090 Vienna (Austria); Nics, Lukas [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Dept. of Nutritional Sciences, Univ. of Vienna, A-1090 Vienna (Austria); Mien, Leonhard-Key [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna, A-1090 Vienna (Austria); Ungersboeck, Johanna [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Dept. of Inorganic Chemistry, Univ. of Vienna, A-1090 Vienna (Austria); Lanzenberger, Rupert R. [Dept. of Psychiatry and Psychotherapy, Medical Univ. of Vienna, A-1090 Vienna (Austria); Shanab, Karem [Dept. of Drug and Natural Product Synthesis, Univ. of Vienna, A-1090 Vienna (Austria); Sindelar, Karoline M. [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Viernstein, Helmut [Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna, A-1090 Vienna (Austria); Wagner, Karl-Heinz [Dept. of Nutritional Sciences, Univ. of Vienna, A-1090 Vienna (Austria); Dudczak, Robert; Kletter, Kurt [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Wadsak, Wolfgang [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Dept. of Inorganic Chemistry, Univ. of Vienna, A-1090 Vienna (Austria); Mitterhauser, Markus [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna, A-1090 Vienna (Austria); Hospital Pharmacy of the General Hospital of Vienna, A-1090 Vienna (Austria)], E-mail: markus.mitterhauser@meduniwien.ac.at

    2010-05-15

    Introduction: Recently, [{sup 18}F]FE-SUPPY and [{sup 18}F]FE-SUPPY:2 were introduced as the first positron emission tomography (PET) tracers for the adenosine A{sub 3} receptor. Thus, aim of the present study was the metabolic characterization of the two adenosine A{sub 3} receptor PET tracers. Methods: In vitro carboxylesterase (CES) experiments were conducted using incubation mixtures containing different concentrations of the two substrates, porcine CES and phosphate-buffered saline. Enzymatic reactions were stopped by adding acetonitrile/methanol (10:1) after various time points and analyzed by a high-performance liquid chromatography (HPLC) standard protocol. In vivo experiments were conducted in male wild-type rats; tracers were injected through a tail vein. Rats were sacrificed after various time points (n=3), and blood and brain samples were collected. Sample cleanup was performed by an HPLC standard protocol. Results: The rate of enzymatic hydrolysis by CES demonstrated Michaelis-Menten constants in a micromolar range (FE-SUPPY, 20.15 {mu}M, and FE-SUPPY:2, 13.11 {mu}M) and limiting velocities of 0.035 and 0.015 {mu}M/min for FE-SUPPY and FE-SUPPY:2, respectively. Degree of metabolism in blood showed the following: 15 min pi 47.7% of [{sup 18}F]FE-SUPPY was intact compared to 33.1% of [{sup 18}F]FE-SUPPY:2; 30 min pi 30.3% intact [{sup 18}F]FE-SUPPY was found compared to 15.6% [{sup 18}F]FE-SUPPY:2. In brain, [{sup 18}F]FE-SUPPY:2 formed an early hydrophilic metabolite, whereas metabolism of [{sup 18}F]FE-SUPPY was not observed before 30 min pi Conclusion: Knowing that metabolism in rats is several times faster than in human, we conclude that [{sup 18}F]FE-SUPPY should be stable for the typical time span of a clinical investigation. As a consequence, from a metabolic point of view, one would tend to decide in favor of [{sup 18}F]FE-SUPPY.

  2. Secondary Fe and Al in Antarctic paleosols: Correlation to Mars with prospect for the presence of life

    Science.gov (United States)

    Mahaney, William C.; Dohm, James; Kapran, Barbara; Hancock, Ronald G. V.; Milner, Michael W.

    2009-09-01

    Middle-Miocene age paleosols in the Antarctic Dry Valleys were studied for their compositional variation and concentrations of secondary oxides/coatings in progression of release of secondary oxides of Fe and Al shows variable percentages of individual oxihydrites relative to chemical element totals, and thus, to consume total Fe and Al would require tens of millions of additional years. The slow progression of Fe d/Fe t, used as a measure of relative age in other warmer alpine and Arctic climates, is shown here to amount to arithmetic functions argue for extremely slow but sustainable release of oxides in a cold, polar desert climate, in which temperatures prohibit the formation of clay minerals. The secondary mineral species present likely amount to residue from past climates that were more conducive to clay mineral genesis and aerosolic input over time. The presence of microbial life in Antarctic paleosols, with minor amounts of Fe available for physiological processes to function, argues for the potential existence of microorganisms in ice-enriched paleosols of Mars, particularly given its watery and dynamic geologic past and relatively high concentration of total Fe in subaerial paleosols. The distribution of Fe over a large part of the northern plains of Mars as determined by the GRS instrument is invoked as a comparison with the Antarctic.

  3. Experimental and theoretical study of magnetic ordering and local atomic polarization in Ru-substituted Lu2Fe17

    Science.gov (United States)

    Tereshina, E. A.; Isnard, O.; Smekhova, A.; Andreev, A. V.; Rogalev, A.; Khmelevskyi, S.

    2014-03-01

    The distribution of magnetic moments in the iron-rich intermetallic compound Lu2Fe17 with Fe partly substituted by Ru has been investigated on Lu2Fe16.5Ru0.5 by using several techniques. The crystal structure and temperature evolution of the magnetic structure was studied using high resolution and high flux neutron powder diffractometers. In contrast to the parent Lu2Fe17, which transforms on cooling from an antiferromagnetic to a ferromagnetic state, Lu2Fe16.5Ru0.5 is an antiferromagnet (Néel temperature TN = 208 K) down to the lowest temperatures. The magnetic polarization at the lutetium L2,3 absorption edges, iron K and ruthenium L2 edges was studied by x-ray magnetic circular dichroism (XMCD) on a single crystal of Lu2Fe16.5Ru0.5 in a magnetic field of 3 T, i.e., above the field-induced metamagnetic transition. The Ru XMCD signal proves the existence of induced magnetic polarization parallel to the dominant Fe sublattice magnetization. A corresponding theoretical analysis in the framework of the local spin density formalism is provided in order to discern the structural disorder effects and magnetism in the system.

  4. Plasma Measurements of the Fe xvii L-shell Emission and Blending with F viii and F ix

    Science.gov (United States)

    Beiersdorfer, P.; Lepson, J. K.; Gu, M. F.; Bitter, M.

    2017-11-01

    We measured the L-shell emission spectrum of Fe xvii in a low-density, low-gradient magnetically confined laboratory plasma that contains predominately C, O, Fe, and Ni as trace elements and found excellent agreement with the relative spectral emission obtained in solar and astrophysical observations. However, we obtained spectra that appear to have an usually large 1{s}22{s}22{p}1/253{d}3/2\\to 1{s}22{s}22{p}6 Fe xvii resonance transition, which is commonly labeled 3C, from hot plasmas that also contain fluorine. The wavelength of the Lyα feature of F ix is coincident with the wavelength of the Fe xvii line 3C within one part in 538, and its flux, therefore, enhances the Fe xvii resonance line. Moreover, the resonance and forbidden lines of F viii are close to the 3s\\to 2p transitions in Fe xvii and may further alter the inferred apparent Fe xvii line ratios, particularly in spectrometers with moderate spectral resolution. The enhanced emission of line 3C can thus serve as a new spectral diagnostic for the detection of fluorine in astrophysical plasmas.

  5. Sulfide phase in the Fe-Ti-S and Fe-C-Ti-S alloys

    International Nuclear Information System (INIS)

    Malinochka, Ya.N.; Balakina, N.A.; Shmelev, Yu.S.

    1976-01-01

    The nature of the sulfide phases in Fe-Ti-S and Fe-C-Ti-S alloys was studied. The carbide and the sulfide phase were identified the aid of X-ray spectral microanalysis. It was established that for a small content of titanium and sulfur in ternary Fe-Ti-S alloys the solidification of the γ-solution on the boundaries of dendritic branches is accompanied, along with the precipitation of a sulfide rich in iron of the (Fe, Ti) S type where a small quantity of titanium is dissolved, by the formation of a titanium-bearing sulfide eutectic γ + TiS. The amount of the sulfide eutectic increases with the contents of titanium and sulfur until a purely eutectic alloy is formed. Both carbides and sulfides may be formed in the solidification of quaternary alloys Fe-C-Ti-S

  6. Condutividade da Polianilina e Poliacrilonitrila Dopadas com Fe(II e Fe(III

    Directory of Open Access Journals (Sweden)

    Yonis Fornazier Filho

    2015-01-01

    Full Text Available In this work we report O estudo da interação de íons Fe(II com a polianilina foi feito através da obtenção deste polímero na forma de salthe studies on Polyaniline Emeraldine (PANI-ES and Polyacrilonitrile (PAN doped with salt of Fe (II and Fe(III. We used the techniques of conductivity measurements with aplicação de pressão.application of pressure.  The results showed that conductivity of PANI-ES increase with pressure of range of 1.73 MPa until 20.0 MPa and PAN also increase with maximum of 6.0 mPa except to samples PAN-2-TT-FeIII and PAN-2-TTAA-FeIII.

  7. Coercivity enhancement of (Nd,Ce-Fe-B sintered magnets by doping Nd-Fe additives

    Directory of Open Access Journals (Sweden)

    K. Chen

    2017-02-01

    Full Text Available The effect of Nd-Fe additives on magnetic properties and microstructure in (Nd,Ce-Fe-B sintered magnet has been investigated. By doping 3wt% Nd-Fe additives, the coercivity of the magnet increases from 10.56kOe to 12.69kOe with slight remanence decrease. Microstructure observation reveals that the volume fraction of the grain boundary phase increases accompanying with the thickening of the thin grain boundary between the adjacent grains. The RE6Fe13Cu phase which has low melting temperature develops at the triple junction position and the out shell of the matrix grains get magnetically hardened with 3wt% Nd-Fe additives. The results of the dynamic magnetic domains between the original magnet and processed magnet elucidate that the formation of reversed magnetic domains are more difficult for the processed magnet which is the direct evidence to clarify the coercivity enhancement.

  8. Chemical consequences of the nuclear reactions 58Fe(n,γ)59Fe and 57Co(EC)57Fe in soluble Prussian Blue

    DEFF Research Database (Denmark)

    Fenger, Jes; Maddock, A. G.; Siekierska, K. E.

    1970-01-01

    KFe[Fe(CN)6],H2O was prepared with 58Fe in either the cation or the complex, and both samples were neutron-irradiated and analysed for free and complexed 59Fe. Parallel experiments were performed on K4[Fe(CN)6],3H2O. In Prussian Blue the retention in the hexacyano-complex is ca. 5% and can be inc...

  9. Parts, Axial Parts, and Next Parts in Kannada

    Directory of Open Access Journals (Sweden)

    R. Amritavalli

    2007-12-01

    Full Text Available Nouns meaning ‘place, region’ and ‘part’ are compounded in Kannada with a `bleached’ noun (a putative postposition to form AxPart and Part readings. As in other languages, the AxPart or ‘region’ reading does not pluralize, does not permit adjectival modification, and allows for MeasureP modification (unlike the part reading. AxParts may also be formed out of nouns by the fusion of a dative marker or a genitive marker with the N; these case markers introduce the Place element. The dative case may be optionally overt (e.g. pakka-kke ‘side-dative,’ ‘to a side’, or covert (in AxParts like munde ‘front’. The genitive marker gives a sense of immediate adjacency that we designate the NextPart reading. Interestingly, the dative and genitive cases in Kannada also allow nouns to assume the function of predicative and attributive adjectives.

  10. Moessbauer study of Fe-Co nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Chen Ziyu [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou (China)]. E-mail: chenzy@lzu.edu.cn; Zhan Qingfeng; Xue Desheng; Li Fashen [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou (China); Zhou Xuezhi; Kunkel, Henry; Williams, Gwyn [Department of Physics and Astronomy, the University of Manitoba (Canada)

    2002-01-28

    Arrays of Fe{sub 1-x}Co{sub x} (0.0{<=}x{<=}0.92) nanowires have been prepared by an electrochemical process, co-depositing Fe and Co atoms into the pores of anodic aluminium; their compositions were determined by atomic absorption spectroscopy. Transmission electron microscope results show that the nanowires are regularly spaced and uniform in shape with lengths of about 7.5 {mu}m and diameters of 20 nm. The x-ray diffraction indicates a texture in the deposited nanowires. For the composition below 82 at.% cobalt, the nanowires had a body-centred-cubic structure with a [110] preferred orientation. For the 92 at.% cobalt sample, the alloy exhibited a mixture of bcc and face-centred-cubic structure. The room temperature {sup 57}Fe Moessbauer spectra of the arrays of Fe{sub 1-x}Co{sub x} nanowires have second and fifth absorption lines of the six-line pattern with almost zero intensity, indicating that the internal magnetic field in the nanowires lies along the long axis of the nanowire. The maximum values of the hyperfine field (B{sub hf} 36.6{+-}0.1 T) and isomer shift (IS=0.06{+-}0.01 mm s-1) occur for 44 at.% cobalt. The variations of the isomer shift and the linewidths with composition indicate that the Fe{sub 1-x}Co{sub x} alloy nanowires around the equiatomic composition are in an atomistic disordered state. (author)

  11. Layer magnetization canting in {sup 57}Fe/FeSi multilayer observed by synchrotron Moessbauer reflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Bottyan, L. [KFKI Research Institute for Particle and Nuclear Physics (Hungary); Dekoster, J. [University of Leuven, Instituut voor Kern- en Stralingsfysica (Belgium); Deak, L. [KFKI Research Institute for Particle and Nuclear Physics (Hungary); Baron, A.Q.R. [European Synchrotron Radiation Facility (France); Degroote, S.; Moons, R. [University of Leuven, Instituut voor Kern- en Stralingsfysica (Belgium); Nagy, D.L. [KFKI Research Institute for Particle and Nuclear Physics (Hungary); Langouche, G. [University of Leuven, Instituut voor Kern- en Stralingsfysica (Belgium)

    1998-08-15

    Synchrotron Moessbauer reflectometry and CEMS results on a [{sup 57}Fe(2.55 nm)/FeSi(1.57 nm)]{sub 10} multilayer (ML) on a Zerodur substrate are reported. CEMS spectra are satisfactorily fitted by {alpha}-Fe and an interface layer of random {alpha}-(Fe, Si) alloy of 20% of the {sup 57}Fe layer thickness on both sides of the individual Fe layers. Kerr loops show a fully compensated AF magnetic layer structure. Prompt X-ray reflectivity curves show the structural ML Bragg peak and Kiessig oscillations corresponding to a bilayer period and total film thickness of 4.12 and 41.2 nm, respectively. Grazing incidence nuclear resonant {theta}-2{theta} scans and time spectra (E = 14.413 keV, {lambda} = 0.0860 nm) were recorded in different external magnetic fields (0 < B{sup ext} < 0.95 T) perpendicular to the scattering plane. The time integral delayed nuclear {theta}-2{theta} scans reveal the magnetic ML period doubling. With increasing transversal external magnetic field, the antiferromagnetic ML Bragg peak disappears due to Fe layer magnetization canting, the extent of which is calculated from the fit of the time spectra and the {theta}-2{theta} scans using an optical approach. In a weak external field the Fe layer magnetization directions are neither parallel with nor perpendicular to the external field. We suggest that the interlayer coupling in [Fe/FeSi]{sub 10} varies with the distance from the substrate and the ML consists of two magnetically distinct regions, being of ferromagnetic character near substrate and antiferromagnetic closer to the surface.

  12. Structure and magnetic properties of Fe2CoGe synthesized by ball-milling

    International Nuclear Information System (INIS)

    Ren, Z.; Li, S.T.; Luo, H.Z.

    2010-01-01

    A Heusler alloy Fe 2 CoGe has been synthesized by the ball-milling method. Its structure and magnetic properties have been studied. The results suggest that ball-milling can be a possible way to produce new Heusler alloys. Both X-ray diffraction and DTA measurement evidenced the formation of a partly amorphous phase after milling for 25 h. It is found that highly ordered Fe 2 CoGe can be obtained by annealing the as-milled powder at 1073 K, while a disordered A2 phase is resulted by annealing at 773 K. The magnetic properties of Fe 2 CoGe are not very sensitive to the atomic disorder. Electronic structure calculation suggests a ferromagnetic ground state in highly ordered Fe 2 CoGe and the total spin moment is 5.03μ B /f.u., which agrees well with the experimental value of 5.06μ B for the sample annealed at 1073 K. It is also found that the atomic disorder does not strongly change the ferromagnetic coupling between Fe and Co moments and also the general structure of the DOS. So the total spin moment only slightly increases when atomic disorder occurs.

  13. Low temperature study of mechanically alloyed Fe67.5Ni32.5 Invar sample

    Science.gov (United States)

    Valenzuela, J. L.; Valderruten, J. F.; Pérez Alcázar, G. A.; Colorado, H. D.; Romero, J. J.; González, J. M.; Greneche, J. M.; Marco, J. F.

    2015-07-01

    The study at low temperatures of powder of the Invar alloy, Fe67.5Ni32.5, produced by mechanical alloying, shows that the sample presents two structural phases, the Fe-Ni BCC and the Fe-Ni FCC. The 57Fe Mössbauer spectra obtained in this sample at different temperatures were fitted considering two hyperfine magnetic field distributions. The first one having the larger mean field and only one peak (at ca. 35 T, varying with T), is associated with the BCC phase, and the second one, presenting several broad peaks (distributed between 10 and 35 T), is associated to the FCC phase. A singlet, which is associated to low spin Fe sites of the FCC phase, was also considered. The mean hyperfine magnetic field of the BCC phase increases monotonically as temperature decreases, while that of the FCC phase presents an anomaly near 75 K. The real part of the ac magnetic susceptibility temperature scans presents a peak whose position increases from 31 to 39 K, when the ac field frequency increases from 100 to 5000 Hz. These results permit to associate the detected anomaly to the occurrence of a reentrant spin glass transition.

  14. Magnetocaloric effect and H gradient in bulk La(Fe,Si)13Hy magnetic refrigerants obtained by HDSH

    DEFF Research Database (Denmark)

    Neves Bez, Henrique; Eggert, Bruno G.F.; Lozano, Jaime

    2015-01-01

    the conventional ingot homogenization heat treatment of 7 days. The samples produced by HDSH showed higher amounts of hydrogen than the parts hydrogenated by the conventional method of thermal homogenization (20 h at 1423 K), milling to fine powder and subsequent hydrogenation. Hydrogenation parameters play...... an important role for the stability of the desired La(Fe,Si)13 phase during the process. Hydrogen desorption was seen to occur at two temperature ranges as a result of internal gradients. Dissimilar amounts of α-Fe were precipitated for different hydrogenation times. As a result, parts produced via HDSH with 2...

  15. Tailoring Mg(x)Mn(1-x)Fe(2)O(4) superparamagnetic nanoferrites for magnetic fluid hyperthermia applications.

    Science.gov (United States)

    Jeun, Minhong; Park, Sungwook; Jang, Gun Hyuk; Lee, Kwan Hyi

    2014-10-08

    A superparamagnetic nanoferrite (SPNF) with high magnetic moment, AC magnetically induced heating (AC-heating) capacity, and good biocompatibility is the most vital part of magnetic fluid hyperthermia for utilizing it in the clinics. Herein, we precisely tune magnetic properties and AC-heating characteristics of MgxMn1-xFe2O4 SPNF via chemically controlling the cations' concentration and distribution to develop a tailored MgxMn1-xFe2O4 SPNF as a potential magnetic fluid hyperthermia agent. The magnetic and AC-heating characteristics of the tailored MgxMn1-xFe2O4 SPNF are strongly dependent on the Mg/Mn cations' concentration and distribution, and Mg0.285Mn0.715Fe2O4 SPNF exhibits the highest saturation magnetization and AC-heating capacity as well as high biocompatibility.

  16. A physics-based crystallographic modeling framework for describing the thermal creep behavior of Fe-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Wei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Capolungo, Laurent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Patra, Anirban [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-02

    This Report addresses the Milestone M2MS-16LA0501032 of NEAMS Program (“Develop hardening model for FeCrAl cladding), with a deadline of 09/30/2016. Here we report a constitutive law for thermal creep of FeCrAl. This Report adds to and complements the one for Milestone M3MS-16LA0501034 (“Interface hardening models with MOOSE-BISON”), where we presented a hardening law for irradiated FeCrAl. The last component of our polycrystal-based constitutive behavior, namely, an irradiation creep model for FeCrAl, will be developed as part of the FY17 Milestones, and the three regimes will be coupled and interfaced with MOOSE-BISON.

  17. The growth of Fe clusters over graphene/Cu(111)

    International Nuclear Information System (INIS)

    Takahashi, Keisuke

    2015-01-01

    The growth of Fe clusters up to nine atoms over graphene/Cu(111) is investigated within the density functional theory. Graphene is weakly physisorbed on Cu(111) through van der Waals force. The structures of Fe clusters over graphene/Cu(111) grow differently compared to gas-phase Fe clusters where Fe clusters are predicted to form towards a pyramid-like structure on graphene/Cu(111). The graphene is negatively charged upon the adsorption of Fe clusters as a result of charge transfer from Fe to graphene. Despite the fact that the electronic structure of graphene is affected by Fe clusters, magnetic moment of Fe clusters over graphene/Cu(111) remains relatively high. This suggests that graphene can be a potential substrate for supporting Fe clusters towards applications in magnetism and catalysis. (paper)

  18. Mechanical alloying of the FeNi-Ag system

    International Nuclear Information System (INIS)

    Gonzalez, G.; Ibarra, D.; Ochoa, J.; Villalba, R.; Sagarzazu, A.

    2007-01-01

    The Fe-Ni-Ag system is of particular interest for its potential applications as soft magnetic granular material with small magnetic grains embedded in a non-magnetic metal matrix. Under equilibrium conditions: Fe-Ag and Ni-Ag are immiscible and Fe-Ni shows complete solubility. These materials are particularly important for magnetoresistivity properties. The properties of these alloys are closely related to their microstructure; therefore, a detailed study of the transformations occurring during milling was undertaken using pre-alloyed Fe x Ni 100-x (x = 30, 50 and 70) further milled with different Ag content to give the following alloys compositions (Fe x -Ni 100-x ) 100-y Ag y (y = 5, 20, 60). Consolidation of the mechanically alloyed powders by sintering at 950 o C was performed. Morphological and structural characterization of the sintered powders was carried out by scanning and transmission electron microscopy and X-ray diffraction. Fe 30 Ni 70 and Fe 50 Ni 50 formed ordered FeNi 3 compound. Fe 70 Ni 30 showed the formation of a mixture of γ-(Fe,Ni) and α-Fe(Ni) solid solutions. The mixture of these systems with Ag showed the metal solid solutions surrounded by Ag islands of Fe x Ni y -Ag, There was also evidence of Ag diffusing into the γ-(Fe,Ni). High Ag content (60%) shows formation of islands of FeNi surrounded by Ag. Sintering is always improved with the Ag content

  19. Determination of Fe Deficiency Tolerance in Sunflower Genotypes

    Directory of Open Access Journals (Sweden)

    Ayfer Alkan Torun

    2017-10-01

    Full Text Available Iron deficiency (Fe is an important nutritional disorder of plants and humans worldwide including Turkey. Sunflower is known as a Fe sensitive crop and its deficiency leads to severe yield and quality losses. In this study, the sensitivity of different sunflower genotypes to Fe deficiency was determined. For this purpose, sunflower genotypes TR-6149-SA, TR-3080 and 6480 were grown either without Fe (0 µmol or with Fe (100 µmol hydroponically. At the end of experiment symptom grade, SPAD value, chlorophyll concentration, shoot dry matter yield, Fe-reductase activity, shoot Fe concentration and pH value of growth medium were measured. It was found out that Fe uptake and Fe reductase activity were the most important factors determining the Fe-deficiency tolerance of a genotype. In the deficiency of Fe conditions, the activity of Fe reductase enzyme in the roots was found higher in the genotype of TR-3080 compared to the other genotypes. The results revealed that the genotypic responses to the different Fe concentrations applied are significantly different and Fe reductase enzyme activity may play an important role in amelioration of iron deficiency.

  20. Monothiol glutaredoxin Grx5 interacts with Fe-S scaffold proteins Isa1 and Isa2 and supports Fe-S assembly and DNA integrity in mitochondria of fission yeast

    International Nuclear Information System (INIS)

    Kim, Kyoung-Dong; Chung, Woo-Hyun; Kim, Hyo-Jin; Lee, Kyung-Chang; Roe, Jung-Hye

    2010-01-01

    Mitochondrial monothiol glutaredoxins that bind Fe-S cluster are known to participate in Fe-S cluster assembly. However, their precise role has not been well understood. Among three monothiol glutaredoxins (Grx3, 4, and 5) in Schizosaccharomyces pombe only Grx5 resides in mitochondria. The Δgrx5 mutant requires cysteine on minimal media, and does not grow on non-fermentable carbon source such as glycerol. We found that the mutant is low in the activity of Fe-S enzymes in mitochondria as well as in the cytoplasm. Screening of multi-copy suppressor of growth defects of the mutant identified isa1 + gene encoding a putative A-type Fe-S scaffold, in addition to mas5 + and hsc1 + genes encoding putative chaperones for Fe-S assembly process. Examination of other scaffold and chaperone genes revealed that isa2 + , but not isu1 + and ssc1 + , complemented the growth phenotype of Δgrx5 mutant as isa1 + did, partly through restoration of Fe-S enzyme activities. The mutant also showed a significant decrease in the amount of mitochondrial DNA. We demonstrated that Grx5 interacts in vivo with Isa1 and Isa2 proteins in mitochondria by observing bimolecular fluorescence complementation. These results indicate that Grx5 plays a central role in Fe-S assembly process through interaction with A-type Fe-S scaffold proteins Isa1 and Isa2, each of which is an essential protein in S. pombe, and supports mitochondrial genome integrity as well as Fe-S assembly.

  1. Monothiol glutaredoxin Grx5 interacts with Fe-S scaffold proteins Isa1 and Isa2 and supports Fe-S assembly and DNA integrity in mitochondria of fission yeast

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyoung-Dong; Chung, Woo-Hyun; Kim, Hyo-Jin; Lee, Kyung-Chang [Laboratory of Molecular Microbiology, School of Biological Sciences, Institute of Microbiology, Seoul National University, Seoul 151-742 (Korea, Republic of); Roe, Jung-Hye, E-mail: jhroe@snu.ac.kr [Laboratory of Molecular Microbiology, School of Biological Sciences, Institute of Microbiology, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2010-02-12

    Mitochondrial monothiol glutaredoxins that bind Fe-S cluster are known to participate in Fe-S cluster assembly. However, their precise role has not been well understood. Among three monothiol glutaredoxins (Grx3, 4, and 5) in Schizosaccharomyces pombe only Grx5 resides in mitochondria. The {Delta}grx5 mutant requires cysteine on minimal media, and does not grow on non-fermentable carbon source such as glycerol. We found that the mutant is low in the activity of Fe-S enzymes in mitochondria as well as in the cytoplasm. Screening of multi-copy suppressor of growth defects of the mutant identified isa1{sup +} gene encoding a putative A-type Fe-S scaffold, in addition to mas5{sup +} and hsc1{sup +} genes encoding putative chaperones for Fe-S assembly process. Examination of other scaffold and chaperone genes revealed that isa2{sup +}, but not isu1{sup +} and ssc1{sup +}, complemented the growth phenotype of {Delta}grx5 mutant as isa1{sup +} did, partly through restoration of Fe-S enzyme activities. The mutant also showed a significant decrease in the amount of mitochondrial DNA. We demonstrated that Grx5 interacts in vivo with Isa1 and Isa2 proteins in mitochondria by observing bimolecular fluorescence complementation. These results indicate that Grx5 plays a central role in Fe-S assembly process through interaction with A-type Fe-S scaffold proteins Isa1 and Isa2, each of which is an essential protein in S. pombe, and supports mitochondrial genome integrity as well as Fe-S assembly.

  2. Fe-oxide fracture fillings as a palæo-redox indicator

    DEFF Research Database (Denmark)

    Dideriksen, Knud; Christiansen, Bo C.; Baker, J.A.

    2007-01-01

    ) Intermediate grain-size crystalline Fe-oxides, that are interpreted to have formed naturally at low-temperatures (~ 10 °C). Fe isotope composition of the Fe-oxides was determined by multiple-collector inductively coupled plasma mass spectrometry using a 58Fe-54Fe double-spike. d56Fe of the Fe-oxides ranges...

  3. 57Fe Moessbauer effect in borosilicate glasses

    International Nuclear Information System (INIS)

    Music, S.

    1989-01-01

    The present study was carried out to elucidate the valence state of iron and its co-ordination in borosilicate glasses, which are being investigated as possible solidification matrices for the immobilization of a simulated nuclear waste. 57 Fe Mossbauer spectroscopy was used as the experimental technique. The chemical compositions of glass samples and the experimental conditions for the preparation of these samples are given. Iron in the form of haematite (α-Fe 2 O 3 ) was used as doping material. Details of the experimental procedure have previously been described. Isomer shifts are calculated relative to α-iron. The results indicate a strong dependence of the valency of the iron and its coordination on the chemical composition of the glass and the Fe 2 O 3 content. The method of preparing the glasses also influences the state of the iron in oxide glasses. (Author)

  4. Magnetostatic Interaction in Fe-Co Nanowires

    Directory of Open Access Journals (Sweden)

    Laura Elbaile

    2012-01-01

    Full Text Available Arrays of Fe-Co alloy nanowires with diameter around 35 nm and several micrometers in length have been synthesized by codepositing Fe and Co into porous anodic alumina. The morphology, structure, and magnetic properties of the nanowires (hysteresis loops and remanence curves were characterized by SEM, TEM, X-ray diffraction (XRD, and VSM, respectively. The XRD patterns indicate that the Fe-Co nanowires present a body-centered cubic (bcc structure and a preferred (110 orientation perpendicular to the template surface. From the hysteresis loops obtained with the magnetic field applied in the axis direction of the nanowires, we can observe that the coercive field slightly decreases when the nanowire length increases. This magnetic behaviour is analyzed considering the shape anisotropy and the dipolar interactions among nanowires.

  5. Fe K-edge XANES of Maya blue pigment

    International Nuclear Information System (INIS)

    Rio, M. Sanchez del; Sodo, A.; Eeckhout, S.G.; Neisius, T.; Martinetto, P.; Dooryhee, E.; Reyes-Valerio, C.

    2005-01-01

    The utilization of techniques used in Materials Science for the characterization of artefacts of interest for cultural heritage is getting more and more attention nowadays. One of the products of the ancient Maya chemistry is the 'Maya blue' pigment, made with natural indigo and palygorskite. This pigment is different from any other pigment used in other parts of the world. It is durable and acid-resistant, and still keeps many secrets to scientists even though it has been studied for more than 50 years. Although the pigment is basically made of palygorskite Si 8 (Mg 2 Al 2 )O 20 (OH) 2 (OH 2 ) 4 .4H 2 O and an organic colourant (indigo: C 16 H 10 N 2 O 2 ), a number of other compounds have been found in previous studies on archaeological samples, like other clays and minerals, iron nanoparticles, iron oxides, impurities of transition metals (Cr, Mn, Ti, V), etc. We measured at the ESRF ID26 beamline the Fe K-edge XANES spectra of the blue pigment in ancient samples. They are compared to XANES spectra of Maya blue samples synthesized under controlled conditions, and iron oxides usually employed as pigments (hematite and goethite). Our results show that the iron found in ancient Maya blue pigment is related to the Fe exchanged in the palygorskite clay. We did not find iron in metallic form or goethite in archaeological Maya blue

  6. Electronic structure of Fe1.08Te bulk crystals and epitaxial FeTe thin films on Bi2Te3

    Science.gov (United States)

    Arnold, Fabian; Warmuth, Jonas; Michiardi, Matteo; Fikáček, Jan; Bianchi, Marco; Hu, Jin; Mao, Zhiqiang; Miwa, Jill; Singh, Udai Raj; Bremholm, Martin; Wiesendanger, Roland; Honolka, Jan; Wehling, Tim; Wiebe, Jens; Hofmann, Philip

    2018-02-01

    The electronic structure of thin films of FeTe grown on Bi2Te3 is investigated using angle-resolved photoemission spectroscopy, scanning tunneling microscopy and first principles calculations. As a comparison, data from cleaved bulk Fe1.08Te taken under the same experimental conditions is also presented. Due to the substrate and thin film symmetry, FeTe thin films grow on Bi2Te3 in three domains, rotated by 0°, 120°, and 240°. This results in a superposition of photoemission intensity from the domains, complicating the analysis. However, by combining bulk and thin film data, it is possible to partly disentangle the contributions from three domains. We find a close similarity between thin film and bulk electronic structure and an overall good agreement with first principles calculations, assuming a p-doping shift of 65 meV for the bulk and a renormalization factor of around two. By tracking the change of substrate electronic structure upon film growth, we find indications of an electron transfer from the FeTe film to the substrate. No significant change of the film’s electronic structure or doping is observed when alkali atoms are dosed onto the surface. This is ascribed to the film’s high density of states at the Fermi energy. This behavior is also supported by the ab initio calculations.

  7. Origin of magnetostriction in Fe-Ga

    DEFF Research Database (Denmark)

    Mudivarthi, Chaitanya; Laver, Mark; Cullen, James

    2010-01-01

    This paper investigates the origin of large magnetostriction in Fe-Ga alloys using small-angle neutron scattering (SANS) and Kerr microscopy. The SANS data for a single-crystal, electron irradiated, and quenched Fe81Ga19 sample under externally applied magnetic and elastic fields revealed...... the existence of magnetostrictive nanoclusters spaced at similar to 15 nm apart that have a different magnetization than the A2 matrix. Combining the SANS results and the magnetization orientation obtained from the magnetic domain images using a Kerr microscope, it appears that the nanoclusters contribute...

  8. Catalytic Methane Decomposition over Fe-Al2O3

    KAUST Repository

    Zhou, Lu

    2016-05-09

    The presence of a Fe-FeAl2O4 structure over an Fe-Al2O3 catalysts is demonstrated to be vital for the catalytic methane decomposition (CMD) activity. After H2 reduction at 750°C, Fe-Al2O3 prepared by means of a fusion method, containing 86.5wt% FeAl2O4 and 13.5wt% Fe0, showed a stable CMD activity at 750°C for as long as 10h. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Evidence for weak electronic correlations in Fe-Pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W. L.; Sorini, A. P.; Chen, C-C.; Moritz, B.; Lee, W.-S.; Vernay, F.; Olalde-Velasco, P.; Denlinger, J. D.; Delley, B.; Chu, J.-H.; Analytis, J.G.; Fisher, I. R.; Ren, Z. A.; Yang, J.; Lu, W.; Zhao, Z. X.; van den Brink, J.; Hussain, Z.; Shen, Z.-X.; Devereaux, T. P.

    2009-06-11

    Using x-ray absorption and resonant inelastic x-ray scattering, charge dynamics at and near the Fe L edges is investigated in Fe pnictide materials, and contrasted tothat measured in other Fe compounds. It is shown that the XAS and RIXS spectra for 122 and 1111 Fe pnictides are each qualitatively similar to Fe metal. Cluster diagonalization, multiplet, and density-functional calculations show that Coulomb correlations are much smaller than in the cuprates, highlighting the role of Fe metallicity and strong covalency in these materials. Best agreement with experiment is obtained using Hubbard parameters U<~;; 2eV and J ~;; 0.8eV.

  10. Evidence for weak electronic correlations in Fe-pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.L.

    2010-04-29

    Using x-ray absorption and resonant inelastic x-ray scattering, charge dynamics at and near the Fe L edges is investigated in Fe pnictide materials, and contrasted to that measured in other Fe compounds. It is shown that the XAS and RIXS spectra for 122 and 1111 Fe pnictides are each qualitatively similar to Fe metal. Cluster diagonalization, multiplet, and density-functional calculations show that Coulomb correlations are much smaller than in the cuprates, highlighting the role of Fe metallicity and strong covalency in these materials. Best agreement with experiment is obtained using Hubbard parameters U {approx}< 2eV and J {approx} 0.8eV.

  11. Anomalous phase change characteristics in Fe-Te materials

    International Nuclear Information System (INIS)

    Fu, X. T.; Song, W. D.; Ji, R.; Ho, H. W.; Wang, L.; Hong, M. H.

    2012-01-01

    Phase change materials have become significantly attractive due to its unique characteristics for its extensive applications. In this paper, a kind of phase change material, which consists of Fe and Te components, is developed. The crystallization temperature of the Fe-Te materials is 180 deg. C for Fe 1.19 Te and can be adjusted by the Fe/Te ratio. High-speed phase change in the Fe-Te materials has been demonstrated by nanosecond laser irradiation. Comparing to conventional phase change materials, the Fe-Te materials exhibit an anomalous optical property that has higher reflectivity at amorphous than crystalline state, which is useful for data storage design.

  12. Shape anisotropy and hybridization enhanced magnetization in nanowires of Fe/MgO/Fe encapsulated in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Aryee, Dennis; Seifu, Dereje

    2017-05-01

    Arrays of tunneling magnetoresistance (TMR) nanowires were synthesized for the first time by filling Fe/MgO/Fe inside vertically grown and substrate supported carbon nanotubes. The magnetic properties of nanowires and planar nanoscale thin films of Fe/MgO/Fe showed several similarities, such as two-fold magnetic symmetry and ratio of orbital moment to spin moment. Nanowires of Fe/MgO/Fe showed higher saturation magnetization by a factor of 2.7 compared to planar thin films of Fe/MgO/Fe at 1.5 kOe. The enhanced magnetic properties likely resulted from shape anisotropy of the nanowires and as well as the hybridization that occur between the π- electronic states of carbon and 3d-bands of the Fe-surface.

  13. Optimization of Fe2+ supplement in anaerobic digestion accounting for the Fe-bioavailability.

    Science.gov (United States)

    Cai, Yafan; Zhao, Xiaoling; Zhao, Yubin; Wang, Hongliang; Yuan, Xufeng; Zhu, Wanbin; Cui, Zongjun; Wang, Xiaofen

    2018-02-01

    Fe is widely used as an additive in anaerobic digestion, but its bioavailability and the mechanism by which it enhances digestion are unclear. In this study, sequential extraction was used to measure Fe bioavailability, while biochemical parameters, kinetics model and Q-PCR (fluorescence quantitative PCR) were used to explore its mechanism of stimulation. The results showed that sequential extraction is a suitable method to assess the anaerobic system bioavailability of Fe, which is low and fluctuates to a limited extent (1.7 to -3.1wt%), indicating that it would be easy for Fe levels to be insufficient. Methane yield increased when the added Fe 2+ was 10-500mg/L. Appropriate amounts of Fe 2+ accelerated the decomposition of rice straw and facilitated methanogen metabolism, thereby improving reactor performance. The modified Gompertz model better fitted the results than the first-order kinetic model. Feasibility analysis showed that addition of Fe 2+ at ≤50mg/L was suitable. Copyright © 2017. Published by Elsevier Ltd.

  14. Texturing for bulk α-Fe/Nd2Fe14B nanocomposites with enhanced magnetic properties

    International Nuclear Information System (INIS)

    Lou, L.; Hou, F.C.; Wang, Y.N.; Cheng, Y.; Li, H.L.; Li, W.; Guo, D.F.; Li, X.H.; Zhang, X.Y.

    2014-01-01

    In the present study, the texturing of bulk α-Fe/Nd 2 Fe 14 B nanocomposites produced from Nd-lean amorphous Nd x Fe 92.5−x Cu 1.5 B 6 (x=9 to 11.5 at%) via a hot deformation under a uniaxial stress of ∼350 MPa at 973 K has been studied. An enhanced (00l) texture of the hard phase is observed with increasing Nd content, which results in an increase in the magnetic anisotropy of the nanocomposite magnets. As a result, both the coercivity and the remanence of the magnets increase simultaneously with increasing Nd content from x=9–11.5 at%, yielding a significant enhancement of the maximum energy product from (BH) max =13.2 to 17.5 MGOe in the direction parallel to stress axis. - Highlights: • Textured bulk α-Fe/Nd 2 Fe 14 B nanocomposites have been produced from Nd-lean alloys. • Nd content has an effect on the texturing of α-Fe/Nd 2 Fe 14 B nanocomposite magnets. • An enhanced (00l) texture of hard phase is observed with increasing Nd content. • Both the coercivity and remanence increase simultaneously with Nd content

  15. Fe++/Fe+++ concentration relationship and mechanical properties of phosphate glasses useful for wastes immobilization

    International Nuclear Information System (INIS)

    Garcia, D.A.; Prado, Miguel O.

    2007-01-01

    Under different melting conditions, glasses with different Fe(II)/Fe(III) concentration relationship were prepared within each type of glass 43Fe 2 O 3 -57P 2 O 5 and 33,33Fe 2 O 3 - 66,67P 2 O 5 . Using Moessbauer spectroscopy Fe(II)/Fe(III) concentration values were determined. Vickers and Knoop indentations were used for determining their hardness, toughness, Young modulus and brittleness. The same measurements were carried on some silicate and aluminosilicate glasses. Also Weibull statistics was done to determine the characteristics (Weibull modulus and and fracture probability) of glass fracture. We found that silicate glasses (SG) are harder than phosphate glasses (PG). Toughness values for PG, are in the same range than for SG, although for the same density exhibit larger values or smaller brittleness than silicate glasses. For one of the glasses it was found that the mechanical load P 0 needed for a fracture probability of 63% increases with the Fe(II) content. (author)

  16. Mössbauer investigations of Fe and Fe3O4 magnetic nanoparticles for hyperthermia applications

    Science.gov (United States)

    Kamzin, A. S.

    2016-03-01

    Magnetic nanoparticles of magnetite Fe3O4 and Fe synthesized by physical vapor deposition with a fast highly effective method using a solar energy have been studied. Targets have been prepared from tablets pressed from Fe3O4 or Fe powders. Relationships between the structure of nanoparticles and their magnetic properties have been investigated in order to understand principles of the control of the parameters of magnetic nanoparticles. Mössbauer investigations have revealed that the nanoparticles synthesized from tablets of both pure iron and Fe3O4 consist of two phases: pure iron and iron oxides (γ-Fe2O3 and Fe3O4). The high iron oxidability suggests that the synthesized nanoparticles have a core/shell structure, where the core is pure iron and the shell is an oxidized iron layer. Magnetite nanoparticles synthesized at a pressure of 80 Torr have the best parameters for hyperthermia due to their core/shell structure and core-to-shell volume ratio.

  17. First principles calculations of interlayer exchange coupling in bcc Fe/Cu/Fe structures

    Energy Technology Data Exchange (ETDEWEB)

    Kowalewski, M.; Heninrich, B. [Simon Fraser Univ., Burnaby, British Columbia (Canada); Schulthess, T.C.; Butler, W.H. [Oak Ridge National Lab., TN (United States)

    1998-01-01

    The authors report on theoretical calculations of interlayer exchange coupling between two Fe layers separated by a modified Cu spacer. These calculations were motivated by experimental investigations of similar structures by the SFU group. The multilayer structures of interest have the general form: Fe/Cu(k)/Fe and Fe/Cu(m)/X(1)/Cu(n)/Fe where X indicates one AL (atomic layer) of foreign atoms X (Cr, Ag, or Fe) and k, m, n represent the number of atomic layers of Cu. The purpose of the experimental and theoretical work was to determine the effect of modifying the pure Cu spacer by replacing the central Cu atomic layer with the atomic layer of foreign atoms X. The first principles calculation were performed using the Layer Korringa-Kohn-Rostoker (LKKR) method. The theoretical thickness dependence of the exchange coupling between two semi-infinite Fe layers was calculated for pure Cu spacer thicknesses in the range of 0 < k < 16. The effect of the foreign atoms X on the exchange coupling was investigated using the structure with 9 AL Cu spacer as a reference sample. The calculated changes in the exchange coupling are in qualitative agreement with experiment.

  18. Anomalous magnetic moments in Fe-Pt and Fe-Pd Invar alloys under high pressure

    CERN Document Server

    Matsushita, M; Endo, S; Ishizuka, M; Kindo, K; Ono, F

    2002-01-01

    Magnetization measurements have been carried out for disordered Fe sub 7 sub 2 Pt sub 2 sub 8 , Fe sub 6 sub 6 Pd sub 3 sub 4 , and Fe sub 6 sub 8 Pd sub 3 sub 2 Invar alloys under high pressure using a technique combining a pressure-clamp-type Drickamer cell and a pulse magnet. In Fe sub 7 sub 2 Pt sub 2 sub 8 at room temperature, the magnetization decreased rapidly with increasing pressure up to 2.5 GPa, but above 2.5 GPa the rate of decrease became small and remained at a small value up to 5.6 GPa. In Fe-Pd Invar alloys at room temperature, the magnetization decreased linearly with increasing pressure. But, at 4.2 K, the change of magnetization with pressure was small in Fe sub 6 sub 6 Pd sub 3 sub 4 , which means that Fe sub 6 sub 6 Pd sub 3 sub 4 behaves as a strong ferromagnet.

  19. Solid FeS lubricant: a possible alternative to MoS2 for Cu-Fe-based friction materials

    Science.gov (United States)

    Peng, Tao; Yan, Qing-zhi; Zhan, Xiao-lu; Shi, Xiao-jiao

    2017-11-01

    Molybdenum disulfide (MoS2) is one of the most commonly used solid lubricants for Cu-Fe-based friction materials. Nevertheless, MoS2 reacts with metal matrices to produce metal sulfides (e.g., FeS) and Mo during sintering, and the lubricity of the composite may be related to the generation of FeS. Herein, the use of FeS as an alternative to MoS2 for producing Cu-Fe-based friction materials was investigated. According to the reaction principle of thermodynamics, two composites—one with MoS2 (Fe-Cu-MoS2 sample) and the other with FeS (FeS-Cu2S-Cu-Fe-Mo sample), were prepared and their friction behaviors and mechanical properties were compared. The results showed that MoS2 reacted with the Cu-Fe matrix to produce FeS, metallic ternary sulfides, and Mo when sintered at 1050°C. The MoS2-Cu-Fe and FeS-Cu2S-Cu-Fe-Mo samples thereby exhibited similar characteristics with respect to phase composition, density, hardness, and tribological behaviors. Micrographs of the worn surfaces revealed that the stable friction regime for both composites stemmed from the iron sulfides friction layers rather than from the molybdenum sulfides layers.

  20. Nepheloid Layer Measurements and Floc Model for OASIS

    Science.gov (United States)

    2012-09-30

    TERM GOALS The long-term goal of our research is to improve fundamental understanding and numerical representation of coastal bottom-boundary layer...including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson...Several more instruments were mounted on the profiling arm, including a laser particle sizer (LISST 100-X), a prototype holographic particle imager

  1. FLoc: Dependable Link Access for Legitimate Traffic in Flooding Attacks

    Science.gov (United States)

    2011-11-23

    IPD , Si,KRj ). The router writes the capability in the client’s connection request packet (e.g., TCP - SYN ) to the server. Thus, a router issues an...acknowledgement (e.g., TCP - SYN /ACK). In Fig. 1, the flow identifier fi at Rj is the capability Cj since Cj can only be authenticated by the Rj . These capabilities...access in flooding attacks. A. Token-Bucket Model Revisited We first review the standard TCP congestion-control mech- anism and the aggregate traffic

  2. Does a Heavy Fe-Isotope Composition of Akilia Quartz-Amphibole-Pyroxene Rocks Necessitate a BIF Origin?

    Science.gov (United States)

    Whitehouse, M J; Schoenberg, R; Fedo, C M; Kamber, B S

    2015-10-01

    The age and origin of the quartz-amphibole-pyroxene (qap) gneiss from the island of Akilia, southern West Greenland, have been the subject of intense debate since the light C-isotope composition of graphite inclusions in apatite was interpreted to indicate the presence of Earth's earliest biological activity. Although this claim for biogenic relicts has been vigorously challenged, the possibility that the rocks might represent some of Earth's earliest water-lain sediments and, hence, a suitable repository for life remains an open question. While some workers have suggested that the entire sequence represents an originally mafic-ultramafic igneous precursor subsequently modified by metasomatism, quartz injection, high-grade metamorphism, and extreme ductile deformation, others maintain that at least a small part of the sequence retains geochemical characteristics indicative of a chemical sedimentary origin. Fractionated Fe isotopes with δ(56)Fe values similar to those observed in Isua BIF have been reported from high-SiO2 units of qap and used to support a chemical sedimentary protolith for the qap unit. Here, we present new Fe isotope data from all lithologic variants in the qap gneiss on Akilia, including layers of undisputed ultramafic igneous origin. Since the latter require introduction of fractionated Fe into at least part of the qap unit, we argue that Fe isotopes must therefore be treated with considerable caution when used to infer BIF for part or all of the qap protolith.

  3. Cermet Fuel Element (FE) on the basis of micro fuel - FE prototype for future power engineering

    International Nuclear Information System (INIS)

    Fedik, I.; Deniskin, V.; Nalivaev, V.; Gavrilin, S.

    2006-01-01

    The FE with ceramic fuel and cladding of E110 alloy under average burnup depth of 43-45MW day/kg U with providing of 3 and 4 year operation periods are used successfully in WWER. The program had been developed for improving of the fuel cycles economical indexes and for further increasing the WWER operational characteristics. In this program the reactor safety increasing has been foreseen and also the coefficient of capacity using (KIUM) at the expense of the average implement of 55-60 MW day/kg U has been achieved. The program foresees also the integration of 5-6 year fuel cycle and other developments. It is planning to solve the pointed problems with help of traditional technical solution, directed to the improving of FE with ceramic fuel. In the present paper the design-engineering and experimental development results have been presented for creation of cermet FE on the basis of micro-fuel with matrix structure (in the further -the cermet FE) for WWER. The works have been carried out over period of the last 10 years in SRI SIA 'Luch' jointly with OKB 'Gidropress', VSRINM Bochvar name, RNTs 'Kurchatovsky institute', FEI and other. During the cermet FE introduction on the basis micro fuel at the NPP, external FE construction constant is kept. That allows installation of the new active zones without any sufficient changing of reactor installations constructions. Using of cermet FE in a new generation of WWER will allow to realize its quality in large volume, in particular, to create the first hermetic contour, to simplify and to reduce the price of safety systems, automatic adjustment, radiation protection, heat transfer purity, etc. The using of cermet FE, for example, in WWER may attach to the installation the exceeded operational properties of safety in different operation conditions, manoeuvrability, vibration strength, FA life time and FE geometrical stability

  4. Electronic and magnetic properties of AlFe3 and AlFe3N nitride

    International Nuclear Information System (INIS)

    Kuhnen, C.A.; Santos, A.V. dos

    2004-01-01

    Self-consistent band structure calculations were performed for the metal aluminide AlFe 3 (in the fcc structure) and the nitride AlFe 3 N (perovskite-like nitride) at several lattice parameters in order to obtain the electronic structure and magnetic properties of these compounds. In this study we have employed the full potential linear augmented plane wave (FPLAPW) and the linear muffin-tin orbital (LMTO-ASA) methods. Our results show that the modeled AlFe 3 is ferromagnetic (FM) with 2.07μ B as the magnetic moment at Fe sites. On the other hand, AlFe 3 N is non-magnetic (NM) contrary to other perovskite nitrides that show magnetic order. Hence as the stable phase of AlFe 3 is magnetic with DO 3 structure a crystallographic transformation occurs accompanied by a magnetic transition from a non-magnetic perovskite structure to a magnetic DO 3 structure as AlFe 3 N lose nitrogen atoms. The LMTO and FPLAPW total energy calculations give the equilibrium volume for both compounds. For AlFe 3 N, the FPLAPW calculations give the equilibrium volume that agrees well with the experimental lattice spacing, which is not achieved by LMTO calculations within the same accuracy. The calculated magnetic moment as function of the lattice parameter for the AlFe 3 shows a collapse of the magnetism at certain critical lattice parameter whose FPLAPW value (2.962 A) differs only slightly from the LMTO value (3.041 A)

  5. Regulation of brain copper homeostasis by the brain barrier systems: Effects of Fe-overload and Fe-deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Monnot, Andrew D.; Behl, Mamta; Ho, Sanna; Zheng, Wei, E-mail: wzheng@purdue.edu

    2011-11-15

    Maintaining brain Cu homeostasis is vital for normal brain function. The role of systemic Fe deficiency (FeD) or overload (FeO) due to metabolic diseases or environmental insults in Cu homeostasis in the cerebrospinal fluid (CSF) and brain tissues remains unknown. This study was designed to investigate how blood-brain barrier (BBB) and blood-SCF barrier (BCB) regulated Cu transport and how FeO or FeD altered brain Cu homeostasis. Rats received an Fe-enriched or Fe-depleted diet for 4 weeks. FeD and FeO treatment resulted in a significant increase (+ 55%) and decrease (- 56%) in CSF Cu levels (p < 0.05), respectively; however, neither treatment had any effect on CSF Fe levels. The FeD, but not FeO, led to significant increases in Cu levels in brain parenchyma and the choroid plexus. In situ brain perfusion studies demonstrated that the rate of Cu transport into the brain parenchyma was significantly faster in FeD rats (+ 92%) and significantly slower (- 53%) in FeO rats than in controls. In vitro two chamber Transwell transepithelial transport studies using primary choroidal epithelial cells revealed a predominant efflux of Cu from the CSF to blood compartment by the BCB. Further ventriculo-cisternal perfusion studies showed that Cu clearance by the choroid plexus in FeD animals was significantly greater than control (p < 0.05). Taken together, our results demonstrate that both the BBB and BCB contribute to maintain a stable Cu homeostasis in the brain and CSF. Cu appears to enter the brain primarily via the BBB and is subsequently removed from the CSF by the BCB. FeD has a more profound effect on brain Cu levels than FeO. FeD increases Cu transport at the brain barriers and prompts Cu overload in the CNS. The BCB plays a key role in removing the excess Cu from the CSF.

  6. Fast defluorination and removal of norfloxacin by alginate/Fe@Fe3O4 core/shell structured nanoparticles.

    Science.gov (United States)

    Niu, Hongyun; Dizhang; Meng, Zhaofu; Cai, Yaqi

    2012-08-15

    Alginate-Fe(2+)/Fe(3+) polymer coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)@ALG/Fe MNPs) with core/shell structure are prepared and used as heterogeneous Fenton nanocatalyst to degrade norfloxacin (NOF). The Fenton-like process based on Fe(3)O(4)@ALG/Fe shows much higher efficiency on NOF degradation. Compared with Fe(3)O(4) nanoparticle-H(2)O(2) system, NOF degradation in Fe(3)O(4)@AlG/Fe-H(2)O(2) system can be conducted in a wide pH range (pH 3.5-6.5) and independent on temperature. With 0.98 mM H(2)O(2) and 0.4 g L(-1) Fe(3)O(4)@ALG/Fe, 100% of NOF and 90% of TOC is removed within 60 min, and the fluorine element in NOF molecule changes into F(-) ions within 1 min, indicating that NOF degradation in this Fenton-like reaction is performed through direct defluorination pathway. XPS analysis shows that TOC removal in reaction solution mainly results from the adsorption of NOF degradation intermediates on catalyst. Due to the paramagneticity and high saturation magnetization of Fe(3)O(4)@ALG/Fe, the used catalyst with adsorbed NOF intermediate is collected from aqueous solution by applying an external magnetic field, leading to complete removal of NOF from water samples. As being composed of inorganic materials and biopolymer, Fe(3)O(4)@ALG/Fe MNPs are robust, thermo-stable, nontoxic and environmentally friendly. These attractive features endow Fe(3)O(4)@ALG/Fe as a potent Fenton-like catalyst for fluoroquinolones degradation. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Ferromagnetic resonance on oxideless magnetic Fe and FeRh nanoparticles; Ferromagnetische Resonanz an oxidfreien magnetischen Fe und FeRh Nanopartikeln

    Energy Technology Data Exchange (ETDEWEB)

    Trunova, Anastasia

    2009-05-25

    This work is dedicated to investigations of structural and magnetic properties of the colloidal Fe/Fe{sub x}O{sub y} nanocubes (13 nm) and the Fe{sub x}Rh{sub 100-x} core/shell nanoparticles (2 nm). As compared with other works, where the measurements on oxidized nanoparticles were carried out, we additionally performed investigations on nanoparticles in an oxide free state. In order to make the measurements on oxide free particles possible, oxygen- and hydrogenplasma was used to remove the ligands and reduce the oxide shell of the Fe nanocubes. The oxide free Fe nanocubes were covered with a Ag/Pt protective coating to prevent them from new oxidation. This method allowed carrying out the magnetic measurements on oxide free Fe nanocubes. Micromagnetic simulations as well as simulations of the high frequency susceptibility were used for the data analysing. It was found that both the g-factor g=2.09{+-}0.01 and the anisotropy constant K{sub 4}=(4.8{+-}0.5).10{sup 4} J/m{sup 3} coincide with that of bulk iron. However, the saturation magnetization M{sub S}(5 K)=(1.2{+-}0.12).10{sup 6} A/m differs from the bulk value by 30%. The reduction by 30% compared to the bulk value in the case of nanoparticles may be caused by the following possible reasons: a) the presence of inner oxide layer (approx. 10 at.%) that cannot be reduced; b) the anti-parallel order between magnetic moments of iron core and magnetic moments of antiferomagnetic iron oxide; c) some structural changes of the surface after plasma treatment. The obtained damping parameter {alpha}=0.03{+-}0.005 is ten times larger than that of the Fe layers as it is known for nanoparticles systems in general. The core/shell Fe{sub x}Rh{sub 100-x} nanoparticles (x=80,50) were produced under Ar-atmosphere and were sealed into a quartz tube to prevent oxidation. The analysis of g-factors shows that the value for the FePh nanoparticles with Fe-rich core is larger (g=2.08{+-}0.01) than that for the nanoparticles with Rh

  8. Ageing and memory effects in the weak random anisotropy magnets amorphous NdGdFe and HoGdFe

    International Nuclear Information System (INIS)

    Saito, Toshiaki; Emura, Ai; Hanashima, Koji

    2007-01-01

    We experimentally examined the ageing phenomena in typical weak random anisotropy magnets (weak RAMs), amorphous NdGdFe and HoGdFe, with a small ratio of the random anisotropy (D) to the ferromagnetic exchange (J) (D/J). These weak RAMs have very long average relaxation time, two or three orders longer than that of spin glasses (SGs) around the transition temperature, and also have a very large ac excitation field (h 0 ) dependence of the ac susceptibility. Measuring the imaginary part of the ac susceptibility at frequency of 0.5 Hz and h 0 of 0.3 Oe by using two temperature-change protocols, we observed the memory and rejuvenation effects as reported in SGs, but the effects are weaker in the present weak RAMs, suggesting that the picture of the hierarchical structure of the free energy space is also effective in weak RAMs as in SGs, but it may have smaller barrier heights than those of SGs

  9. Insights into Resistance to Fe Deficiency Stress from a Comparative Study of In Vitro-Selected Novel Fe-Efficient and Fe-Inefficient Potato Plants

    Directory of Open Access Journals (Sweden)

    Georgina A. Boamponsem

    2017-09-01

    Full Text Available Iron (Fe deficiency induces chlorosis (IDC in plants and can result in reduced plant productivity. Therefore, development of Fe-efficient plants is of great interest. To gain a better understanding of the physiology of Fe-efficient plants, putative novel plant variants were regenerated from potato (Solanum tubersosum L. var. ‘Iwa’ callus cultures selected under Fe deficient or low Fe supply (0–5 μM Fe. Based on visual chlorosis rating (VCR, 23% of callus-derived regenerants were classified as Fe-efficient (EF and 77% as Fe-inefficient (IFN plant lines when they were grown under Fe deficiency conditions. Stem height was found to be highly correlated with internodal distance, leaf and root lengths in the EF plant lines grown under Fe deficiency conditions. In addition, compared to the IFN plant lines and control parental biotype, the EF plants including the lines named A1, B2, and B9, exhibited enhanced formation of lateral roots and root hairs as well as increased expression of ferritin (fer3 in the leaf and iron-regulated transporter (irt1 in the root. These morphological adaptations and changes in expression the fer3 and irt1 genes of the selected EF potato lines suggest that they are associated with resistance to low Fe supply stress.

  10. Ammonia synthesis on Au modified Fe(111) and Ag and Cu modified Fe(100) surfaces

    DEFF Research Database (Denmark)

    Lytken, Ole; Waltenburg, Hanne Neergaard; Chorkendorff, Ib

    2003-01-01

    In order to investigate any influence of steps and possible positive effects of making surface alloys the ammonia synthesis has been investigated over Au modified Fe(111) and Ag and Cu modified Fe(100) single crystals in the temperature range 603-773 K, using a system combining ultra-high vacuum...... and a high-pressure cell. Ammonia was synthesized from a stoichiometric (N-2:3H(2)) gas mixture at a pressure of 2 bar. By deposition of small amounts of An, the ammonia production activity of the Fe(1 1 1) surface can be enhanced. More important, for the gold modified surface, the reaction order in ammonia...

  11. Annealing temperature dependence of exchange bias in BiFeO3/CoFe bilayers

    Science.gov (United States)

    Yu, T.; Naganuma, H.; Wang, W. X.; Ando, Y.; Han, X. F.

    2012-04-01

    BiFeO3/CoFe bilayers with different BiFeO3 (BFO) crystalities were fabricated by chemical solution deposition and sputtering method. Exchange bias has been successfully induced in these bilayers by post-annealing. The annealing temperature dependence of exchange bias as well as coercivity was investigated. Two kinds of annealing temperature dependence behaviors were observed. It is found that, similar to the conventional antiferromagnet/ferromagnet system, the temperature dependence of exchange bias is dominated by direct interface coupling, and the crystality of BFO has no profound effect on exchange bias.

  12. Spin-dependent electronic transport characteristics in Fe4N/BiFeO3/Fe4N perpendicular magnetic tunnel junctions

    Science.gov (United States)

    Yin, Li; Wang, Xiaocha; Mi, Wenbo

    2018-01-01

    Perpendicular magnetic tunnel junctions (MTJs) have attracted increasing attention owing to the low energy consumption and wide application prospects. Herewith, against Julliere's formula, an inverse tunnel magnetoresistance (TMR) appears in tetragonal Fe4N/BiFeO3/Fe4N perpendicular MTJs, which is attributed to the binding between the interface resonant tunneling state and central (bordered) hot spots. Especially, antiferromagnetic BiFeO3 shows an extra spin-polarized resonant state in the barrier, which provides a magnetic-barrier factor to affect the tunneling transport in MTJs. Meanwhile, due to the spin-polarized transport in Fe4N/BiFeO3/Fe4N MTJs, the sign of TMR can be tuned by the applied bias. The tunable TMR and resonant magnetic barrier effect pave the way for clarifying the tunneling transport in other junctions and spintronic devices.

  13. Spectrophotometric speciation of Fe(II) and Fe(III) using hydrazone-micelle systems and flow injections

    International Nuclear Information System (INIS)

    Khojali, Inas Osman

    1999-04-01

    Two hydrazones were synthesised, namely salicylhyrazone (SH) and trihydroxyacetophenone (THAPH) were synthesised with the objective of developing a method for determining of Fe(II) and Fe(III) in the presence of each other and hence the total iron.those hydrazones were selected so as to combine the ability of phenolic compounds to complex Fe(III) ions and the complexing characteristics of hydrazones. The complexes of Fe(II) S H and Fe(III) S H as well those of Fe(II)-THAPH and Fe(III)-THAPH had shown maximum absorbance at λ=412 nm which was not not modified by presence of micelles i.e. sodium n-dodecyl sulphate (SDS) and n-hexa dodecyl pyridinium bromide. The maximum absorbance for all complexes takes place around a neutral pH. Generally, in addition, of n-hexa dodecylpyridinium bromide to fe(II)-SH and Fe(III)-SH absorbance of the complexes increases with increasing the concentration of the micelle. The effects of the addition of sodium n-dodecyle sulphate (SDS) to Fe(III)-SH is also studied. Generally, increasing the concentration of the micelle decrease the absorbance of the complexes. To study the effect of the presence of Fe(II) and Fe(III) on the determination of each other,mixtures of Fe(II)-SH and Fe(III)-SH are studied. However, the use of ascorbic acid as a reducing reagent for Fe(III) did not produce the needed results but non reducible results, which may be due to the masking effect of ascorbic acid and thus making the metal not available to the ligand. However, conversion of Fe(II) to Fe(III) prior to the determination was avoided as this requires the use of oxidant, which will oxidise the ligand as well. To establish the condition for the maximum absorbance of THAPH complexes, the effect of the base was investigated by using sodium and ammonium hydroxide. Generally, increasing the concentration of the base decreases the abosrbance. as expected, ammonium hydroxide produced positive results than sodium hydroxide. After establishing the optimum Fi

  14. Torsion-induced magnetoimpedance in nanocrystalline Fe-based wires

    International Nuclear Information System (INIS)

    Santos, J.D.; Olivera, J.; Alvarez, P.; Sanchez, T.; Perez, M.J.; Sanchez, M.L.; Gorria, P.; Hernando, B.

    2007-01-01

    The magnetic field influence on the real and imaginary parts of axial-diagonal (ζ zz ) and off-diagonal (ζ φz ) components of the surface magnetoimpedance (MI) tensor has been studied in amorphous and nanocrystalline Fe 73.5 Si 13.5 B 9 Cu 1 Nb 3 wires. Twisted and untwisted wires were annealed at a temperature near to that of primary crystallization. The MI response has been measured at 1MHz and 5mA rms drive current in all the samples. Even though the higher values for both components of the MI tensor are achieved for the untwisted annealed wire, the most interesting features are observed in the torsion annealed wire

  15. Superparamagnetic relaxation in alpha-Fe particles

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Pedersen, Michael Stanley

    1998-01-01

    The superparamagnetic relaxation time of carbon-supported alpha-Fe particles with an average size of 3.0 Mm has been studied over a large temperature range by the use of Mossbauer spectroscopy combined with AC and DC magnetization measurements. It is found that the relaxation time varies with tem...

  16. Phonon density of states in nanocrystalline Fe

    Indian Academy of Sciences (India)

    Abstract. The Born–von Karman model is used to calculate phonon density of states (DOS) of nanocrystalline bcc Fe. It is found that there is an anisotropic stiffening in the interatomic force constants and hence there is shrinking in the nearest-neighbour distances in the nanophase. This leads to additional vibrational modes ...

  17. Magnetic ground state of FeSe

    Science.gov (United States)

    Wang, Qisi; Shen, Yao; Pan, Bingying; Zhang, Xiaowen; Ikeuchi, K.; Iida, K.; Christianson, A. D.; Walker, H. C.; Adroja, D. T.; Abdel-Hafiez, M.; Chen, Xiaojia; Chareev, D. A.; Vasiliev, A. N.; Zhao, Jun

    2016-01-01

    Elucidating the nature of the magnetism of a high-temperature superconductor is crucial for establishing its pairing mechanism. The parent compounds of the cuprate and iron-pnictide superconductors exhibit Néel and stripe magnetic order, respectively. However, FeSe, the structurally simplest iron-based superconductor, shows nematic order (Ts=90 K), but not magnetic order in the parent phase, and its magnetic ground state is intensely debated. Here we report inelastic neutron-scattering experiments that reveal both stripe and Néel spin fluctuations over a wide energy range at 110 K. On entering the nematic phase, a substantial amount of spectral weight is transferred from the Néel to the stripe spin fluctuations. Moreover, the total fluctuating magnetic moment of FeSe is ∼60% larger than that in the iron pnictide BaFe2As2. Our results suggest that FeSe is a novel S=1 nematic quantum-disordered paramagnet interpolating between the Néel and stripe magnetic instabilities. PMID:27431986

  18. Absorber transmissivities in 57Fe Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Ballet, O.

    1985-01-01

    Some useful relations are derived for the polarization dependent optical index of 57 Fe Moessbauer absorbers. Real rotation matrices are extensively used and, besides wave-direction dependence, their properties simplify also the treatment of texture and f-anisotropy. The derivation of absorber transmissivities from the optical index is discussed with a special emphasis on line overlapping. (Auth.)

  19. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    pounds [2,3] renewed great interest in the study of high-temperature superconductivity. Fe-based systems are significantly different from the cuprates. The parent compounds in cuprates are antiferromagnetic Mott insulators, where the insulating property arises due to strong electron correlation compared to the width of their ...

  20. Multiepoch Spectropolarimetry of SN 2011fe

    Energy Technology Data Exchange (ETDEWEB)

    Milne, Peter A.; Williams, G. Grant; Smith, Paul S.; Smith, Nathan; Jannuzi, Buell T.; Green, E. M. [University of Arizona, Steward Observatory, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Porter, Amber; Leising, Mark D. [118 Kinard Laboratory, Clemson University, Clemson, SC 29634 (United States)

    2017-01-20

    We present multiple spectropolarimetric observations of the nearby Type Ia supernova (SN) 2011fe in M101, obtained before, during, and after the time of maximum apparent visual brightness. The excellent time coverage of our spectropolarimetry has allowed better monitoring of the evolution of polarization features than is typical, which has allowed us new insight into the nature of normal SNe Ia. SN 2011fe exhibits time-dependent polarization in both the continuum and strong absorption lines. At early epochs, red wavelengths exhibit a degree of continuum polarization of up to 0.4%, likely indicative of a mild asymmetry in the electron-scattering photosphere. This behavior is more common in subluminous SNe Ia than in normal events, such as SN 2011fe. The degree of polarization across a collection of absorption lines varies dramatically from epoch to epoch. During the earliest epoch, a λ 4600–5000 Å complex of absorption lines shows enhanced polarization at a different position angle than the continuum. We explore the origin of these features, presenting a few possible interpretations, without arriving at a single favored ion. During two epochs near maximum, the dominant polarization feature is associated with the Si ii λ 6355 Å absorption line. This is common for SNe Ia, but for SN 2011fe the polarization of this feature increases after maximum light, whereas for other SNe Ia, that polarization feature was strongest before maximum light.

  1. Hydrodynamic Modelling and Experimental Analysis of FE-DMFC Stacks

    Science.gov (United States)

    Kablou, Yashar

    Direct methanol fuel cells (DMFCs) present some unique features such as having liquid fuel, quick refueling process, compact design and high energy density. These characteristics make them incredibly suitable as a promising power source for portable electronic applications, such as cell phones or laptop computers. Despite of these positive aspects, the commercial development of DMFCs has nevertheless been hindered by some important issues such as, carbon dioxide formation at the anode compartment and, methanol crossover through the membrane. Many researchers have tried to model the two-phase flow behavior inside the DMFC anode compartment using the "homogenous flow modelling" approach, which has proven to be inaccurate specially when dealing with DMFC stacks. On the other hand, several strategies to prevent methanol crossover have been suggested in the literature, including the use of a flowing electrolyte between the DMFC anode and cathode compartments. Preliminary tests on flowing electrolyte direct methanol fuel cells (FE-DMFCs) have shown promising results; however, further investigation should be carried out on the stack level. In the first part of this study, a quasi two-dimensional numerical model was developed, to predict the two-phase flow behavior within the DMFC anode compartment, both in single cell and stack levels. Various types of flow modelling approaches and void fraction correlations were utilized to estimate the pressure drop across the anode compartment. It was found that the "separated flow modelling" approach, as well as CISE correlation for void fraction (developed at the CISE labs in Milan), yield the best results. In the second part, a five-cell FE-DMFC stack unit with a parallel serpentine flow bed design and U-type manifold configuration, was developed and tested at various operating conditions. It was found that, the flowing electrolyte effectively reduced methanol crossover and, improved the stack performance.

  2. Dielectric properties of layered FeGaInS{sub 4} single crystals in an alternating electric field

    Energy Technology Data Exchange (ETDEWEB)

    Mammadov, F. M. [Azerbaijan National Academy of Sciences, Nagiyev Institute of Catalysis and Inorganic Chemistry (Azerbaijan); Niftiyev, N. N., E-mail: namiq7@bk.ru [Azerbaijan State Pedagogical University (Azerbaijan)

    2016-09-15

    The results of investigations of the frequency and temperature dependences of dielectric losses and the imaginary part of the dielectric permittivity in FeGaInS{sub 4} single crystals are presented. Their experimental values are determined. It is established that the loss tangent and the imaginary part of the permittivity of FeGaInS{sub 4} single crystals in a field with frequencies of 10{sup 4}–10{sup 6} Hz decrease inversely proportional to the frequency (tanδ ~ 1/ω), and the conductivity is characterized by the band–hopping mechanism. For FeGaInS{sub 4}, the relaxation time is calculated, and it is established that there is a mechanism of electron polarization caused by thermal motion in this crystal.

  3. Magnetic depth profiling of Fe/Au multilayer using neutron ...

    Indian Academy of Sciences (India)

    Au multilayer sample for characterizing the layer structure and magnetic moment density profile. Fe/Au multilayer shows strong spin-dependent scattering at interfaces, making it a prospective GMR material. Fe/Au multilayer with bilayer ...

  4. X-ray fluorescence analysis of Fe - Ni - Mo systems

    International Nuclear Information System (INIS)

    Belyaev, E.E.; Ershov, A.V.; Mashin, A.I.; Mashin, N.I.; Rudnevskij, N.K.

    1998-01-01

    Procedures for the X-ray fluorescence determination of the composition and thickness of Fe - Ni - Mo thin films and the concentration of elements in thick films of the Fe - Ni - Mo alloy are developed [ru

  5. Uranium and Iron XRF distribution and Fe speciation results

    Data.gov (United States)

    U.S. Environmental Protection Agency — Dataset 1: XRF image of U and Fe distribution Dataset 2: Fe linear combination fitting data. This dataset is associated with the following publication: Koster van...

  6. Exchange bias in sputtered FeNi/FeMn systems: Effect of short low-temperature heat treatments

    Energy Technology Data Exchange (ETDEWEB)

    Savin, Peter, E-mail: peter.savin@urfu.ru [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Guzmán, Jorge [Instituto de Ciencia de Materiales de Madrid-CSIC, 28049 Madrid (Spain); Lepalovskij, Vladimir [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Svalov, Andrey; Kurlyandskaya, Galina [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48940 Leioa, Vizcaya (Spain); Asenjo, Agustina [Instituto de Ciencia de Materiales de Madrid-CSIC, 28049 Madrid (Spain); Vas’kovskiy, Vladimir [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Vazquez, Manuel [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Instituto de Ciencia de Materiales de Madrid-CSIC, 28049 Madrid (Spain)

    2016-03-15

    Short (5 min) post-deposition thermal treatments under magnetic field at low temperature (up to 200 °C) performed in exchange-coupled FeNi(40 nm)/FeMn(20 nm) bilayer thin films prepared by magnetron sputtering are shown to be effective to significantly modify their exchange field (from around 40 Oe down to 27 Oe) between FeNi and FeMn layers. A similar exchange field decrease was observed for the first deposited FeNi layer of the FeNi(40 nm)/FeMn(20 nm)/FeNi(40 nm) trilayer films after the same thermal treatments. The exchange field value for the second FeNi layer was not substantially changed. The X-ray diffraction patterns indicates that such a heat treatment has no effect on the grain size and crystalline texture of the films, while atomic force microscope studies reveal an increase of the surface roughness after the treatment which is more noticeable in the case of the trilayer film. Analysis of the experimental results leads us to conclude that the variations of the exchange field after heat treatment are likely caused by a modification of interfacial roughness and/or interfacial magnetic structure, but unlikely by the changes in the microstructure and/or changes of composition of the antiferromagnetic FeMn layer. - Highlights: • FeNi/FeMn bilayers and FeNi/FeMn/FeNi trilayers were prepared by magnetron sputtering. • Post-deposition heat treatments at the temperatures below 200 °C during 5 min were made. • Annealing reduces the exchange field for the first FeNi layer in trilayers. • The exchange field value for the second FeNi layer was not substantially changed. • Exchange field changes are most likely caused by a modification of interface roughness.

  7. Regulation of brain copper homeostasis by the brain barrier systems: effects of Fe-overload and Fe-deficiency.

    Science.gov (United States)

    Monnot, Andrew D; Behl, Mamta; Ho, Sanna; Zheng, Wei

    2011-11-01

    Maintaining brain Cu homeostasis is vital for normal brain function. The role of systemic Fe deficiency (FeD) or overload (FeO) due to metabolic diseases or environmental insults in Cu homeostasis in the cerebrospinal fluid (CSF) and brain tissues remains unknown. This study was designed to investigate how blood-brain barrier (BBB) and blood-SCF barrier (BCB) regulated Cu transport and how FeO or FeD altered brain Cu homeostasis. Rats received an Fe-enriched or Fe-depleted diet for 4 weeks. FeD and FeO treatment resulted in a significant increase (+55%) and decrease (-56%) in CSF Cu levels (pBCB. Further ventriculo-cisternal perfusion studies showed that Cu clearance by the choroid plexus in FeD animals was significantly greater than control (pBCB contribute to maintain a stable Cu homeostasis in the brain and CSF. Cu appears to enter the brain primarily via the BBB and is subsequently removed from the CSF by the BCB. FeD has a more profound effect on brain Cu levels than FeO. FeD increases Cu transport at the brain barriers and prompts Cu overload in the CNS. The BCB plays a key role in removing the excess Cu from the CSF. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Intramolecular stabilization of a catalytic [FeFe]-hydrogenase mimic investigated by experiment and theory.

    Science.gov (United States)

    Pandey, Indresh Kumar; Natarajan, Mookan; Faujdar, Hemlata; Hussain, Firasat; Stein, Matthias; Kaur-Ghumaan, Sandeep

    2018-04-03

    The mono-substituted complex [Fe2(CO)5(μ-naphthalene-2-thiolate)2(P(PhOMe-p)3)] was prepared taking after the structural principles from both [NiFe] and [FeFe]-hydrogenase enzymes. Crystal structures are reported for this complex and the all carbonyl analogue. The bridging naphthalene thiolates resemble μ-bridging cysteine amino acids. One of the naphthyl moieties forms π-π stacking interactions with the terminal bulky phosphine ligand in the crystal structure and in calculations. This interaction stabilizes the reduced and protonated forms during electrocatalytic proton reduction in the presence of acetic acid and hinders the rotation of the phosphine ligand. The intramolecular π-π stabilization, the electrochemistry and the mechanism of the hydrogen evolution reaction were investigated using computational approaches.

  9. Fe{sub 3}C/Fe nanoparticles with urea: Synthesis, structure and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaobai [College of Chemistry, Jilin University, Changchun, 130012 (China); School of Chemical and Pharmaceutical Engineering, Jilin Institute of Chemical Technology, Jilin, 132022 (China); Zhang, Daguang [Department of Orthopaedic Surgery, the First Hospital of Jilin University, Changchun, 130021 China (China); Ren, Xiaozhen; Gao, Jiajia [College of Chemistry, Jilin University, Changchun, 130012 (China); Han, Yu [Department of Chemistry, College of Science, Yanbian University, Yanji, 133002 China (China); Chen, Xiaodong [College of Chemistry, Jilin University, Changchun, 130012 (China); Shi, Zhan [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, 130012 (China); Yang, Hua [College of Chemistry, Jilin University, Changchun, 130012 (China)

    2016-12-15

    Fe{sub 3}C/Fe nanocomposites were synthesized by a sol–gel method. Using urea as carbon source and reduce agent in the reaction process. The CTAB works as the surfactant and the bromine contained in CTAB plays a catalytic role. Appropriate choices of the amount of urea and CTAB, reaction temperature and time are very important to obtain high-quality of products. Above 650 °C, the precursor gel turned into the nanocomposites composed of iron carbide and iron. Their structures and magnetic properties are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The possible formation mechanism of as-prepared nanostructures is discussed. - Highlights: • The Fe{sub 3}C/Fe composites were synthetized by sol–gel method. • Their structure, magnetic properties are researched by XRD, VSM and TEM. • The possible formation mechanisms of the composites is discussed.

  10. Effects of strong network modifiers on Fe3+/Fe2+ in silicate melts: an experimental study

    Science.gov (United States)

    Borisov, Alexander; Behrens, Harald; Holtz, Francois

    2017-05-01

    The effect of CaO, Na2O, and K2O on ferric/ferrous ratio in model multicomponent silicate melts was investigated in the temperature range 1450-1550 °C at 1-atm total pressure in air. It is demonstrated that the addition of these network modifier cations results in an increase of Fe3+/Fe2+ ratio. The influence of network modifier cations on the ferric/ferrous ratio increases in the order Ca SiO2-TiO2-Al2O3-FeO-Fe2O3-MgO-CaO-Na2O-K2O-P2O5 melts at air conditions.

  11. Efficient spin injection and giant magnetoresistance in Fe / MoS 2 / Fe junctions

    KAUST Repository

    Dolui, Kapildeb

    2014-07-02

    We demonstrate giant magnetoresistance in Fe/MoS2/Fe junctions by means of ab initio transport calculations. We show that junctions incorporating either a monolayer or a bilayer of MoS2 are metallic and that Fe acts as an efficient spin injector into MoS2 with an efficiency of about 45%. This is the result of the strong coupling between the Fe and S atoms at the interface. For junctions of greater thickness, a maximum magnetoresistance of ∼300% is obtained, which remains robust with the applied bias as long as transport is in the tunneling limit. A general recipe for improving the magnetoresistance in spin valves incorporating layered transition metal dichalcogenides is proposed. © 2014 American Physical Society.

  12. Incommensurate magnetism in FeAs strips: neutron scattering from CaFe(4)As(3).

    Science.gov (United States)

    Nambu, Yusuke; Zhao, Liang L; Morosan, Emilia; Kim, Kyoo; Kotliar, Gabriel; Zajdel, Pawel; Green, Mark A; Ratcliff, William; Rodriguez-Rivera, Jose A; Broholm, Collin

    2011-01-21

    Magnetism in the orthorhombic metal CaFe(4)As(3) was examined through neutron diffraction for powder and single crystalline samples. Incommensurate [q(m) ≈ (0.37-0.39) × b*] and predominantly longitudinally (|| b) modulated order develops through a 2nd order phase transition at TN = 89.63(6) K with a 3D Heisenberg-like critical exponent β = 0.365(6). A 1st order transition at T2 = 25.6(9)  K is associated with the development of a transverse component, locking q(m) to 0.375(2)b*, and increasing the moments from 2.1(1) to 2.2(3)  μ B for Fe2+ and from 1.3(3) to 2.4(4)  μB for Fe+. The ab initio Fermi surface is consistent with a nesting instability in cross-linked FeAs strips.

  13. Part C and Part D Compliance Actions

    Data.gov (United States)

    U.S. Department of Health & Human Services — This page includes results from CMSs Past Performance Review. The report called Spring 2014 Past Performance Review Outlier Results lists MA organizations and Part D...

  14. Rapid thermal annealing of FePt and FePt/Cu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Brombacher, Christoph

    2011-01-10

    Chemically ordered FePt is one of the most promising materials to reach the ultimate limitations in storage density of future magnetic recording devices due to its high uniaxial magnetocrystalline anisotropy and a corrosion resistance superior to rare-earth based magnets. In this study, FePt and FePt/Cu bilayers have been sputter deposited at room temperature onto thermally oxidized silicon wafers, glass substrates and self-assembled arrays of spherical SiO{sub 2} particles with diameters down to 10 nm. Millisecond flash lamp annealing, as well as conventional rapid thermal annealing was employed to induce the phase transformation from the chemically disordered A1 phase into the chemically ordered L1{sub 0} phase. The influence of the annealing temperature, annealing time and the film thickness on the ordering transformation and (001) texture evolution of FePt films with near equiatomic composition was studied. Whereas flash lamp annealed FePt films exhibit a polycrystalline morphology with high chemical L1{sub 0} order, rapid thermal annealing can lead to the formation of chemically ordered FePt films with (001) texture on amorphous SiO{sub 2}/Si substrates. The resultant high perpendicular magnetic anisotropy and large coercivities up to 40 kOe are demonstrated. Simultaneously to the ordering transformation, rapid thermal annealing to temperatures exceeding 600 C leads to a break up of the continuous FePt film into separated islands. This dewetting behavior was utilized to create regular arrays of FePt nanostructures on SiO{sub 2} particle templates with periods down to 50 nm. The addition of Cu improves the (001) texture formation and chemical ordering for annealing temperatures T{sub a} {<=}600 C. In addition, the magnetic anisotropy and the coercivity of the ternary FePtCu alloy can be effectively tailored by adjusting the Cu content. The prospects of FePtCu based exchange spring media, as well as the magnetic properties of FePtCu nanostructures fabricated

  15. 50 CFR Figure 15 to Part 223 - Weedless TED Brace Bar Description

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Weedless TED Brace Bar Description 15 Figure 15 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND.... 223, Fig. 15 Figure 15 to Part 223—Weedless TED Brace Bar Description ER21FE03.003 [68 FR 8469, Feb...

  16. Fe-catalyzed thermal conversion of sodium lignosulfonate to graphene

    Science.gov (United States)

    Sung Phil Mun; Zhiyong Cai; Jilei Zhang

    2013-01-01

    Sodium lignosulfonate (LS) from sulfite pulping processing was used as a carbon source to synthesize graphene. LS was mixed with Fe nanoparticles (FeNPs) as a catalyst and thermally treated at 1000 °C for 1 h. The Raman spectrum and X-ray diffraction pattern suggested that graphene sheets were formed in LS thermally treated with FeNPs (Fe-HTLS). Scanning...

  17. Ground state magnetic properties of Fe nanoislands on Cu(111)

    International Nuclear Information System (INIS)

    Kishi, Tomoya; David, Melanie; Nakanishi, Hiroshi; Kasai, Hideaki; Dino, Wilson Agerico; Komori, Fumio

    2005-01-01

    We investigate magnetic properties of Fe nanoislands on Cu(111) in the relaxed structure within the density functional theory. We observe that the nanoislands exhibit the ferromagnetic properties with large magnetic moment. We find that the change in the magnetic moment of each Fe atom is induced by deposition on Cu(111) and structure relaxation of Fe nanoislands. Moreover, we examine the stability of ferromagnetic states of Fe nanoislands by performing the total energy calculations. (author)

  18. Removal of indigo blue using clinoptilolite-Fe; Remocion de azul indigo utilizando clinoptilolita-Fe

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez S, E. E.; Colin C, A. [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Paseo Tollocan esquina Paseo Colon s/n, Toluca 50180, Estado de Mexico (Mexico); Solache R, M. J. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico)], e-mail: edithgs77@yahoo.com.mx

    2008-07-01

    The removal of indigo blue from aqueous solutions was evaluated using modified clinoptilolite with Fe (Z-Fe) which was characterized by SEM, EDS analysis and specific area (BET). The process followed the kinetics of pseudo-second order and Langmuir isotherm. Sorption capacity obtained was 18 mg g{sup -1} and a solid-liquid ratio 10 g L{sup -1}. (Author)

  19. The Characterization of FeZSM-5 by 57Fe Moessbauer Spectroscopy: Sensitivity Towards Nitrogen

    International Nuclear Information System (INIS)

    Overweg, A. R.; Craje, M. W. J.; Arends, I. W. C. E.; Kraan, A. M. van der

    2002-01-01

    Moessbauer spectra were recorded at 4.2 K of an FeZSM-5 zeolite that has been treated with nitrogen at 623 K. Changes in the sample environment clearly show the affinity of nitrogen for some of the iron centers in the material. Additionally, structural similarities have been found between this FeZSM-5 zeolite and that activated by a high-temperature vacuum treatment.

  20. Comprehensive Phylogenetic Diversity of [FeFe]-Hydrogenase Genes in Termite Gut Microbiota

    OpenAIRE

    Zheng, Hao; Bodington, Dylan; Zhang, Chong; Miyanaga, Kazuhiko; Tanji, Yasunori; Hongoh, Yuichi; Xing, Xin-Hui

    2013-01-01

    Phylogenetic diversity of [FeFe]-hydrogenase (HydA) in termite guts was assessed by pyrosequencing PCR amplicons obtained using newly designed primers. Of 8,066 reads, 776 hydA phylotypes, defined with 97% nucleotide sequence identity, were recovered from the gut homogenates of three termite species, Hodotermopsis sjoestedti, Reticulitermes speratus, and Nasutitermes takasagoensis. The phylotype coverage was 92–98%, and the majority shared only low identity with database sequences. It was est...

  1. Ferroelectric control of magnetization in BiFeO3/CoFe heterostructures.

    Science.gov (United States)

    Gajek, Martin; Martin, Lane; Heron, John; Seidel, Jan; Ramesh, Ramamoorthy

    2009-03-01

    The cross coupling between ferroic order parameters in multiferroics opens an alternative for the control of magnetism in magnetoelectric devices by purely electrical means. We first report on the exchange coupling between BiFeO3, an antiferromagnetic ferroelectric , and CoFe. We then show that the domain structure of the ferromagnet can be changed by poling the ferroelectric layer. Finally, we will discuss the implementation of our findings into possible device schemes.

  2. Research on high rate capabilities B-substituted LiFePO4.

    Science.gov (United States)

    Wang, Fu; Zhang, Yun; Chen, Chao

    2013-02-01

    LiFePO4 is currently recognized as one of the most promising electrode materials for large-scale application of lithium ion batteries. However, the limitation of rate capability is believed to be intrinsic to this family of compounds due to the existence of larger tetrahedral (PO4)3- unit and quasi-hexagonal close-packed oxygen array. This paper report here a systematic investigation of the enhancement of rate performance by partly substitution of light small triangle oxyanion, (BO3)3-, for the larger tetrahedral (PO4)3- units in LiFePO4. Cathode electrode materials LiFeB(x)P(1_x)O(4-delta), in which X = 0, 3, 6 and 9, mol%, were synthesized by solid-state method. The as-synthesized products were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Electrochemical Measurements. The results showed that 6 mol% of boron substitution had no effect on the structure of LiFePO4 material, but significantly improved its rate performance. The initial discharge capacity of the LiFeB0.06P0.94O(4-delta) sample was 145.62 mAh/g at 0.1 C, and the capacity retention ratios of 81% at 2 C and 76% at 5 C were obtained, demonstrating that a proper amount of boron substitution (lower than 6 mol%) could significantly improve the rate performance of LiFePO4 cathode material.

  3. Molecular adsorption of hydrogen peroxide on N- and Fe-doped titania nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Mohajeri, Afshan, E-mail: amohajeri@shirazu.ac.ir; Dashti, Nasimeh Lari

    2017-06-15

    Highlights: • The stability and electronic properties of N/Fe-doped (TiO{sub 2}){sub n} clusters with n = 5,6 were studied. • The adsorption H{sub 2}O{sub 2} on the surface of doped clusters has been investigated. • This is the first report of H{sub 2}O{sub 2} adsorption onto the (TiO{sub 2}){sub n} cluster in the presence of metal and non-metal dopants. • The effect of N and Fe dopants on interaction strength was studied. - Abstract: Titanium dioxide (titania) nanoparticles have been extensively investigated for photocatalytic applications such as the decomposition and adsorption of pollutant and undesirable compound in air and waste water. In this context, the present article reports the molecular adsorption of hydrogen peroxide on the surface of doped titania clusters. Density functional theory calculations were performed to investigate the structures and electronic properties of two nanoscale (TiO{sub 2}){sub n} clusters (n = 5,6) modified by nitrogen and iron dopants. The relative stability of all possible N-doped and Fe-doped isomers has been compared with each other and with the parent cluster. It was found that the Fe-doped clusters are in general more stable than the N-doped counterparts. Moreover, after N/Fe doping an enhanced in the magnetization of the clusters is observed. In the second part, we have investigated different modes of H{sub 2}O{sub 2} adsorption on the lowest-energy isomers of doped clusters. In almost all the cases, the adsorptions on the doped clusters are found to be less exothermic than on the corresponding undoped parent cluster. Our results highlight the essential role of charge transfer into the interaction between H{sub 2}O{sub 2} and doped (TiO{sub 2}){sub n} clusters, especially for Fe-doped clusters.

  4. Ab-initio electronic and magnetic properties of Fe-Al alloys

    Directory of Open Access Journals (Sweden)

    Apiñaniz, E.

    2000-06-01

    Full Text Available This work presents ab-initio self-consistent calculations performed with the TB-LMTO code to study the different phases of the Fe-Al phase diagram, corresponding to the ordered structures B2, DO3 and B32 and for Fe50Al50 and Fe3Al compositions. Both, unpolarized and spin-polarized calculations have been performed to deduce the energetic difference between the paramagnetic and ferromagnetic state of the corresponding structure. Calculations for the disordered structures have also been performed for the previously mentioned compositions. These results show that by disordering the alloy magnetism is enhanced and that the equilibrium lattice parameter increases.

    En este trabajo se presentan cálculos autoconsistentes ab-initio realizados con el método TB-LMTO (Tight Binding Linear Muffin Tin Orbital con el fin de estudiar las diferentes estructuras que se presentan en el diagrama de fases de las aleaciones Fe-Al. Se han estudiado las estructuras ordenadas B2, DO3 y B32 para las siguientes concentraciones: Fe50Al50 y Fe3Al. Asimismo, se han realizado cálculos teniendo y sin tener en cuenta la polarización de spin con el fin de poder deducir la diferencia energética entre los estados ferromágneticos y paramágneticos de la misma estructura. Por otra parte se han realizado estos mismos cálculos para estructuras desordenadas y las mismas concentraciones. Los resultados muestran que mediante el desorden aumenta el magnetismo de estas aleaciones y crece el parámetro de red.

  5. Measurements of the Fe3+ diffusion coefficient in Fricke Xylenol gel using optical density measurements

    International Nuclear Information System (INIS)

    Nonato de Oliveira, Lucas; Sampaio, Francisco Glaildo Almeida; Moreira, Marcos Vasques; Almeida, Adelaide de

    2014-01-01

    In Fricke dosimetry, optical density measurements are performed some time after dosimeter irradiation. Values of the diffusion coefficient of Fe 3+ in Fricke Xylenol gel (FXG) are necessary for determining the spatial distribution of the absorbed dose from measurements of the optical density. Five sets of FXG dosimeters, kept at different constant temperatures, were exposed to collimated 6 MV photons. The optical density profile, proportional to the Fe 3+ concentration, at the boundary between irradiated and non-irradiated parts of each dosimeter was measured periodically over a period of 60 h. By comparing the experimental data with a function that accounts for the unobserved initial concentration profile of Fe 3+ in the FXG, we obtained diffusion coefficients 0.30±0.05, 0.40±0.05, 0.50±0.05, 0.60±0.05 and 0.80±0.05 mm 2 /h for the temperatures 283.0±0.5, 286.0±0.5, 289.0±0.5, 292.0±0.5, and 296.0±0.5 K, respectively. The activation energy of Fe 3+ diffusion in the gel, 0.54±0.06 eV, was determined from the temperature dependence of the diffusion coefficients. - Highlights: • A new analytical method to determine diffusion coefficients of ions in gels is proposed. • The method is applied for measurements of the diffusion coefficients of Fe 3+ ions in a Fricke gel dosimeter. • Activation energy of the Fe 3+ ions in the gel was found to be 0.54 ±0.06 eV

  6. Parameters measurement transport hydrogen in Fe alloys with low contents of C through the technique of permeation; Medida de los Parametros de Transporte de Hidrogeno en Aleaciones de Fe con Bajo Contenidos de C mediante la Tecnica de Permeacion

    Energy Technology Data Exchange (ETDEWEB)

    Penalva, I.; Alberro, G.; Legarda, F.; Vila, R.; Ortiz, C. J.

    2012-07-01

    The characterization of the candidates materials to be part of a fusion reactor implies interaction with hydrogen isotopes. Their transport parameters will affect the inventory of hydrogen retained in components of the fusion reactor and permeation of these isotopes through the materials structure can affect areas of human work. Therefore, the analysis of any concept related to fusion reactors, the plasma stability or radiation safety, lies in the knowledge of these parameters. The main objective of this work was to determine the influence of the C content of the iron alloys in the transport parameters of hydrogen using the technique of permeation. Six samples were analyzed experimentally by EFDA (European Fusion Development Agreement) with microstructure and chemical content of alloys controlled. Three of them, Fe pure, FeP y Fe10%Cr, contained insignificant amounts of C, while the other three, FeC, FePC y Fe10%CrC, had the same metallurgical composition as its corresponding pair, with the exception of the content of C.

  7. Magnetization reversal in textured NdFeB-Fe composites observed by domain imaging

    Energy Technology Data Exchange (ETDEWEB)

    Thielsch, Juliane, E-mail: j.thielsch@ifw-dresden.d [IFW Dresden, Institute for Metallic Materials, P.O. Box 27 01 16, D-01171 Dresden (Germany); Hinz, Dietrich; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden, Institute for Metallic Materials, P.O. Box 27 01 16, D-01171 Dresden (Germany)

    2010-10-15

    Textured composite samples consisting of Nd{sub 13.6}Fe{sub 73.6}Ga{sub 0.6}Co{sub 6.6}B{sub 5.6} (MQU-F{sup TM}) and micron-sized Fe particles with weight ratios from 100:0 to 70:30 have been prepared by hot deformation. Microstructure studies revealed a layered structure of both phases with the layer normal parallel to the pressing direction. Magnetic measurements showed single-phase hysteresis curves for all samples when measured along the pressing direction, which is also the easy axis of magnetization. Coercivity decreased drastically from 1.32 T for pure NdFeB samples to 0.154 T for a sample with 30 wt% Fe. Magneto-optical Kerr microscopy with a digitally enhanced imaging technique has been used to examine the evolution of magnetic domains in the hard and soft phase during demagnetizing a sample consisting of 70 wt% NdFeB and 30 wt% Fe. It is shown that demagnetization takes place via domain rearrangements within the soft phase, which lead to and support the nucleation of reversed interaction domains at phase boundaries. Also nucleation of interaction domains within the hard magnetic phase could be revealed.

  8. Magnetization reversal in textured NdFeB-Fe composites observed by domain imaging

    International Nuclear Information System (INIS)

    Thielsch, Juliane; Hinz, Dietrich; Schultz, Ludwig; Gutfleisch, Oliver

    2010-01-01

    Textured composite samples consisting of Nd 13.6 Fe 73.6 Ga 0.6 Co 6.6 B 5.6 (MQU-F TM ) and micron-sized Fe particles with weight ratios from 100:0 to 70:30 have been prepared by hot deformation. Microstructure studies revealed a layered structure of both phases with the layer normal parallel to the pressing direction. Magnetic measurements showed single-phase hysteresis curves for all samples when measured along the pressing direction, which is also the easy axis of magnetization. Coercivity decreased drastically from 1.32 T for pure NdFeB samples to 0.154 T for a sample with 30 wt% Fe. Magneto-optical Kerr microscopy with a digitally enhanced imaging technique has been used to examine the evolution of magnetic domains in the hard and soft phase during demagnetizing a sample consisting of 70 wt% NdFeB and 30 wt% Fe. It is shown that demagnetization takes place via domain rearrangements within the soft phase, which lead to and support the nucleation of reversed interaction domains at phase boundaries. Also nucleation of interaction domains within the hard magnetic phase could be revealed.

  9. Origins of giant biquadratic coupling in CoFe/Mn/CoFe sandwich structures (abstract)

    Science.gov (United States)

    Koon, Norman C.

    1996-04-01

    Recently Filipkowski et al. reported extremely strong, near 90 degree coupling of 2.5 erg/cm2 for epitaxial sandwiches of CoFe/Mn/CoFe, where the CoFe composition was chosen to be a good lattice match to Mn. Both CoFe and Mn have the bcc structure, but Mn is antiferromagnetic while CoFe is ferromagnetic. It was found that the data were very well described by a simple model due to Slonczewski, in which the interlayer coupling is given by Fc=C+(φ1-φ2)2+C-(φ1-φ2-π)2. While this model describes the data much better than the usual biquadratic form, it still does not connect directly to the microscopic origins of the effect. In the present work we seek to explain the results in terms of normal bilinear exchange and magnetocrystalline anisotropy, together with reasonable assumptions about the structure of the interfaces. We obtain excellent agreement with both the experimental results and the Slonczewski model under the assumptions that at least one of the two CoFe/Mn interfaces is smooth (i.e., atomically flat) on a length scale comparable to or greater than the thickness of the Mn layer and at least one interface is rough on a scale less than approximately a domain wall thickness.

  10. New method for simultaneous determination of 55Fe and 59Fe in blood serum samples

    International Nuclear Information System (INIS)

    Saukkonen, H.; Uhlenius, R.

    1978-01-01

    Routine methods for the measurement of 55 Fe and 59 Fe activities in biological samples are frequently required in metabolic studies of iron. A new simple method for the simultaneous determination of 59 Fe and 55 Fe concentration in 5 cm 3 samples of blood is described and carefully evaluated. Before the measurement of the activity, organic matter was eliminated by HNO 3 -HClO 4 wet ashing and iron was electroplated onto a copper plate. The accuracy of results was studied by assessing samples, which contained known amounts of radioactivity and determining the counts per nanocurie in each case. The accuracy of the results of 59 Fe and 55 Fe determinations was found to be about 5%. The method has been routinely used to determine iron resorption in patients using the double isotope method. The determination proved to be satisfactory and not too laborious. When performing the yield determination there is a way of detecting and correcting mistakes or incompleteness in different stages of the measurement, thus leading to a high degree of reliability. (T.G.)

  11. Accumulating the hydride state in the catalytic cycle of [FeFe]-hydrogenases

    Science.gov (United States)

    Winkler, Martin; Senger, Moritz; Duan, Jifu; Esselborn, Julian; Wittkamp, Florian; Hofmann, Eckhard; Apfel, Ulf-Peter; Stripp, Sven Timo; Happe, Thomas

    2017-07-01

    H2 turnover at the [FeFe]-hydrogenase cofactor (H-cluster) is assumed to follow a reversible heterolytic mechanism, first yielding a proton and a hydrido-species which again is double-oxidized to release another proton. Three of the four presumed catalytic intermediates (Hox, Hred/Hred and Hsred) were characterized, using various spectroscopic techniques. However, in catalytically active enzyme, the state containing the hydrido-species, which is eponymous for the proposed heterolytic mechanism, has yet only been speculated about. We use different strategies to trap and spectroscopically characterize this transient hydride state (Hhyd) for three wild-type [FeFe]-hydrogenases. Applying a novel set-up for real-time attenuated total-reflection Fourier-transform infrared spectroscopy, we monitor compositional changes in the state-specific infrared signatures of [FeFe]-hydrogenases, varying buffer pH and gas composition. We selectively enrich the equilibrium concentration of Hhyd, applying Le Chatelier's principle by simultaneously increasing substrate and product concentrations (H2/H+). Site-directed manipulation, targeting either the proton-transfer pathway or the adt ligand, significantly enhances Hhyd accumulation independent of pH.

  12. Adsorption characteristics of Fe(III) and Fe(III)-NTA complex on granular activated carbon.

    Science.gov (United States)

    Kim, D S

    2004-01-02

    The adsorption of Fe(3+) ion on granular activated carbon has been studied in kinetic and equilibrium conditions taking into account the adsorbate concentration, temperature and solution pH as major influential factors. In addition, the effect of nitrilotriacetic acid on adsorption reaction as a complexing agent has been examined. Kinetic studies showed that the adsorption rate was increased as the initial Fe(3+) concentration was raised. The adsorption reaction was estimated to be first-order at room temperature. The adsorption rate and equilibrium adsorption of Fe(3+) increased as the temperature rose. The activation energy for adsorption was approximately 2.23 kJ mol(-1), which implied that Fe(3+) mainly physically adsorbed on activated carbon. Coexistence of nitrilotriacetic acid with Fe(3+) resulted in a decrease of equilibrium adsorption and the extent of decrease was proportional to the concentration of nitrilotriacetic acid. In the presence of nitrilotriacetic acid, the adsorbability of Fe(3+) decreased with pH. However, the trend was reversed in the absence of nitrilotriacetic acid. When activated carbon was swelled by acetic acid, the specific surface area was increased and maximum swelling was achieved at approximately 48 h of swelling time. Thermodynamic parameters such as DeltaG(o), DeltaH(o) and DeltaS(o) for adsorption reaction were estimated based on equilibrium data and in connection with these results the thermodynamic aspects of adsorption reaction were discussed.

  13. Tuning high frequency magnetic properties and damping of FeGa, FeGaN and FeGaB thin films

    Directory of Open Access Journals (Sweden)

    Derang Cao

    2017-11-01

    Full Text Available A series of FeGa, FeGaN and FeGaB films with varied oblique angles were deposited by sputtering method on silicon substrates, respectively. The microstructure, soft magnetism, microwave properties, and damping factor for the films were investigated. The FeGa films showed a poor high frequency magnetic property due to the large stress itself. The grain size of FeGa films was reduced by the additional N element, while the structure of FeGa films was changed from the polycrystalline to amorphous phase by the involved B element. As a result, N content can effectively improve the magnetic softness of FeGa film, but their high frequency magnetic properties were still poor both when the N2/Ar flow rate ratio is 2% and 5% during the deposition. The additional B content significantly led to the excellent magnetic softness and the self-biased ferromagnetic resonance frequency of 1.83 GHz for FeGaB film. The dampings of FeGa films were adjusted by the additional N and B contents from 0.218 to 0.139 and 0.023, respectively. The combination of these properties for FeGa films are helpful for the development of magnetostrictive microwave devices.

  14. Fe(z+) (z = 1-6) generation from ferrocene.

    Science.gov (United States)

    Yatsuhashi, Tomoyuki; Murakami, Eri; Nakashima, Nobuaki

    2011-03-14

    Multiply charged iron atoms up to Fe(6+) with few carbon ions were produced from ferrocene under intense femtosecond laser fields. The production of Fe(4+) and Fe(5+) from ferrocene requires much less laser intensity than theoretically expected for iron atoms. The dissociation of ferrocene and the generation mechanism of multiply charged iron atoms are discussed.

  15. Magnetic depth profiling of Fe/Au multilayer using neutron ...

    Indian Academy of Sciences (India)

    We present unpolarized and polarized neutron reflectometry data on Fe/Au multilayer sample for characterizing the layer structure and magnetic moment density profile. Fe/Au multilayer shows strong spin-dependent scattering at interfaces, making it a prospective GMR material. Fe/Au multilayer with bilayer thickness of 130 ...

  16. Electron spin resonance of Fe4+ in amethyst quartz

    International Nuclear Information System (INIS)

    Cox, R.T.

    1975-01-01

    The ESR spectrum of Fe 4+ was looked for in amethyst quartz. Besides saturated Fe 3+ lines, ESR lines of a new paramagnetic center whose spin-lattice relaxation time is relatively short were observed. They could be attributed to Fe 4+ [fr

  17. Magnetism of substitutional Fe impurities in graphene nanoribbons.

    Science.gov (United States)

    Longo, R C; Carrete, J; Gallego, L J

    2011-01-14

    Using the generalized gradient approximation to exchange and correlation, we perform density functional calculations on an Fe atom at a single vacancy of graphene nanoribbons. Our results show that, after relaxation, the Fe atom is magnetic, in contrast to the behavior recently found for Fe at a single vacancy of the graphene sheet.

  18. Evolutionary analysis of iron (Fe) acquisition system in Marchantia polymorpha.

    Science.gov (United States)

    Lo, Jing-Chi; Tsednee, Munkhtsetseg; Lo, Ying-Chu; Yang, Shun-Chung; Hu, Jer-Ming; Ishizaki, Kimitsune; Kohchi, Takayuki; Lee, Der-Chuen; Yeh, Kuo-Chen

    2016-07-01

    To acquire appropriate iron (Fe), vascular plants have developed two unique strategies, the reduction-based strategy I of nongraminaceous plants for Fe(2+) and the chelation-based strategy II of graminaceous plants for Fe(3+) . However, the mechanism of Fe uptake in bryophytes, the earliest diverging branch of land plants and dominant in gametophyte generation is less clear. Fe isotope fractionation analysis demonstrated that the liverwort Marchantia polymorpha uses reduction-based Fe acquisition. Enhanced activities of ferric chelate reductase and proton ATPase were detected under Fe-deficient conditions. However, M. polymorpha did not show mugineic acid family phytosiderophores, the key components of strategy II, or the precursor nicotianamine. Five ZIP (ZRT/IRT-like protein) homologs were identified and speculated to be involved in Fe uptake in M. polymorpha. MpZIP3 knockdown conferred reduced growth under Fe-deficient conditions, and MpZIP3 overexpression increased Fe content under excess Fe. Thus, a nonvascular liverwort, M. polymorpha, uses strategy I for Fe acquisition. This system may have been acquired in the common ancestor of land plants and coopted from the gametophyte to sporophyte generation in the evolution of land plants. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  19. Selective uptake of 55Fe from seawater by zooplankton

    International Nuclear Information System (INIS)

    Jennings, C.D.

    1978-01-01

    Iron-55 was measured in water and mixed zooplankton collected in the South Pacific Ocean. The ratios of the specific activity of 55 Fe (pCi/g Fe) between plankton and water from the same locations appear to be about 100, which suggests that zooplankton took up 55 Fe in preference to stable iron in the South Pacific Ocean

  20. Thermodynamic assessment of the La-Fe-O system

    DEFF Research Database (Denmark)

    Povoden-Karadeniz, E.; Grundy, A.N.; Chen, Ming

    2009-01-01

    The La-Fe and the La-Fe-O systems are assessed using the Calphad approach, and the Gibbs energy functions of ternary oxides are presented. Oxygen and mutual La and Fe solubilities in body-centered cubic (bcc) and face-centered cubic (fcc) structured metallic phases are considered in the modeling....

  1. Characterization of α-Fe-Free Heteroepitaxial NdFe12- x Ti x Thin-Film Materials with a Novel Cubic Laves Fe2Ti Phase

    Science.gov (United States)

    Hadorn, Jason Paul; Hirayama, Yusuke; Ohkubo, Tadakatsu

    2018-01-01

    Thin films with compositions of NdFe12 and NdFe11Ti1 were fabricated on W-buffered MgO(001) substrates of varying roughness. In this study, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the films microstructurally, chemically, and crystallographically. This study revealed successful heteroepitaxial synthesis of the tetragonal NdFe12 and NdFe12- x Ti x phases in the Ti-free and Ti-containing films, respectively, both with surface-normal c-axis orientation. It also revealed the presence of other phases within the magnetic layer. The NdFe12 films contained many α-Fe particles, which preferentially precipitated at locally rough regions of the W-buffer interface. The NdFe11Ti1 film showed the ubiquitous presence of an Fe2Ti phase, which covered most of the buffer thereby preventing the formation of α-Fe. This phase was determined to have a novel Cu2Mg-type cubic Laves ( C15) crystal structure with fourfold interfacial symmetry, good coherency, and a low mismatch with the W-buffer, thus rendering itself as being an ideal interface for the heteroepitaxial synthesis of NdFe12- x Ti x crystals. It is proposed that successful application of a cubic Fe2Ti underlayer on W can contribute to the development of a fabrication strategy for NdFe12 thin films without the presence of soft magnetic α-Fe.

  2. Perpendicular exchange coupling effects in ferrimagnetic TbFeCo/GdFeCo hard/soft structures

    Science.gov (United States)

    Wang, Ke; Wang, Yahong; Ling, Fujin; Xu, Zhan

    2018-04-01

    Bilayers consisting of magnetically hard TbFeCo and soft GdFeCo alloy were fabricated. Exchange-spring and sharp switching in a step-by-step fashion were observed in the TbFeCo/GdFeCo hard/soft bilayers with increasing GdFeCo thickness. A perpendicular exchange bias field of several hundred Oersteds is observed from the shift of minor loops pinned by TbFeCo layer. The perpendicular exchange energy is derived to be in the range of 0.18-0.30 erg/cm2. The exchange energy is shown to increase with the thickness of GdFeCo layer in the bilayers, which can be attributed to the enhanced perpendicular anisotropy of GdFeCo layer in our experimental range.

  3. Magnetism and site exchange in CuFeAs and CuFeSb: A microscopic and theoretical investigation

    Science.gov (United States)

    Kamusella, Sirko; Klauss, Hans-Henning; Thakur, Gohil S.; Haque, Zeba; Gupta, Laxmi C.; Ganguli, Ashok K.; Kraft, Inga; Burkhardt, Ulrich; Rosner, Helge; Luetkens, Hubertus; Lynn, Jeffrey W.; Zhao, Yang

    2017-03-01

    We have investigated the magnetic ground state of CuFeAs and CuFeSb by means of 57Fe-Mössbauer spectroscopy, muon spin rotation/relaxation (μ SR ), neutron diffraction, and electronic structure calculations. Both materials share the 111-LiFeAs crystal structure and are closely related to the class of iron-based superconductors. In both materials there is a considerable occupancy of the Cu site by Fe, which leads to ferromagnetic moments, which are magnetically strongly coupled to the regular Fe site magnetism. Our study shows that CuFeAs is close to an antiferromagnetic instability, whereas a ferromagnetic ground state is observed in CuFeSb, supporting theoretical models of anion height driven magnetism.

  4. Improvement of magnetic properties of Fe-50mass%Ni in MIM process; MIM process ni okeru Fe-50mass%Ni no jiki tokusei kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Miura, H. [Kumamoto University, Kumamoto (Japan). Faculty of Engineering; Fujita, S. [Kumamoto University, Kumamoto (Japan); Fujita, M.; Ninomiya, R. [Mitsuikinzoku Co. Ltd., Tokyo (Japan)

    2000-12-15

    Metal injection molding (MIM) process is hoped to be one of processing for required to more complicated parts of magnetic components. In this study, the effect of different types of powders (prealloyed and mixed elemental powders) on the magnetic properties of permalloy (Fe-50mass%Ni) through the MIM technique was investigated. Approximately 94% of theoretical density was obtained by using the prealloyed powder, and the retained carbon and oxygen contents were controlled to be low. On the other hand, 96% of theoretical density was obtained by using the mixed elemental powder, but the magnetic properties were inferior to that of prealloyed powder's because of high retained oxygen content. By using the carbonyl Fe powder with high carbon, the retained oxygen and carbon content could be controlled to be low, resulting in the improved magnetic properties. (author)

  5. NMR of proteins (4Fe-4S): structural properties and intramolecular electron transfer; RMN de proteines (4Fe-4S): proprietes structurales et transfert electronique intramoleculaire

    Energy Technology Data Exchange (ETDEWEB)

    Huber, J.G.

    1996-10-17

    NMR started to be applied to Fe-S proteins in the seventies. Its use has recently been enlarged as the problems arising from the paramagnetic polymetallic clusters ware overcome. Applications to [4Fe-4S] are presented herein. The information derived thereof deepens the understanding of the redox properties of these proteins which play a central role in the metabolism of bacterial cells. The secondary structure elements and the overall folding of Chromatium vinosum ferredoxin (Cv Fd) in solution have been established by NMR. The unique features of this sequence have been shown to fold as an {alpha} helix at the C-terminus and as a loop between two cysteines ligand of one cluster: these two parts localize in close proximity from one another. The interaction between nuclear and electronic spins is a source of additional structural information for (4Fe-AS] proteins. The conformation of the cysteine-ligands, as revealed by the Fe-(S{sub {gamma}}-C{sub {beta}}-H{sub {beta}})Cys dihedral angles, is related to the chemical shifts of the signals associated with the protons of these residues. The longitudinal relaxation times of the protons depend on their distance to the cluster. A quantitative relationship has been established and used to show that the solution structure of the high-potential ferredoxin from Cv differs significantly from the crystal structure around Phe-48. Both parameters (chemical shifts and longitudinal relaxation times) give also insight into the electronic and magnetic properties of the [4Fe-4S] clusters. The rate of intramolecular electron transfer between the two [4FE-4S] clusters of ferredoxins has been measured by NMR. It is far slower in the case of Cv Fd than for shorter ferredoxins. The difference may be associated with changes in the magnetic and/or electronic properties of one cluster. The strong paramagnetism of the [4Fe-4S] clusters, which originally limited the applicability of NMR to proteins containing these cofactors, has been proven

  6. Mechanisms for Fe(III) oxide reduction in sedimentary environments

    Science.gov (United States)

    Nevin, Kelly P.; Lovely, Derek R.

    2002-01-01

    Although it was previously considered that Fe(III)-reducing microorganisms must come into direct contact with Fe(III) oxides in order to reduce them, recent studies have suggested that electron-shuttling compounds and/or Fe(III) chelators, either naturally present or produced by the Fe(III)-reducing microorganisms themselves, may alleviate the need for the Fe(III) reducers to establish direct contact with Fe(III) oxides. Studies with Shewanella alga strain BrY and Fe(III) oxides sequestered within microporous beads demonstrated for the first time that this organism releases a compound(s) that permits electron transfer to Fe(III) oxides which the organism cannot directly contact. Furthermore, as much as 450 w M dissolved Fe(III) was detected in cultures of S. alga growing in Fe(III) oxide medium, suggesting that this organism releases compounds that can solublize Fe(III) from Fe(III) oxide. These results contrast with previous studies, which demonstrated that Geobacter metallireducens does not produce electron-shuttles or Fe(III) chelators. Some freshwater aquatic sediments and groundwaters contained compounds, which could act as electron shuttles by accepting electrons from G. metallireducens and then transferring the electrons to Fe(III). However, other samples lacked significant electron-shuttling capacity. Spectroscopic studies indicated that the electron-shuttling capacity of the waters was not only associated with the presence of humic substances, but water extracts of walnut, oak, and maple leaves contained electron-shuttling compounds did not appear to be humic substances. Porewater from a freshwater aquatic sediment and groundwater from a petroleum-contaminated aquifer contained dissolved Fe(III) (4-16 w M), suggesting that soluble Fe(III) may be available as an electron acceptor in some sedimentary environments. These results demonstrate that in order to accurately model the mechanisms for Fe(III) reduction in sedimentary environments it will be necessary

  7. Removal combined with reduction of hexavalent chromium from aqueous solution by Fe-ethylene glycol complex microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yong-Xing [School of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Jia, Yong, E-mail: yjiaahedu@163.com [School of Pharmacy, Anhui University of Chinese Medicine, Hefei 230012 (China)

    2016-12-15

    Highlights: • Fe-EG complex microspheres were synthesized by a hydrothermal method. • The removal properties towards Cr(VI) ions were investigated. • The adsorption and reduction mechanism was revealed by FTIR and XPS. - Abstract: Three-dimensional Fe-ethylene glycol (Fe-EG) complex microspheres were synthesized by a facile hydrothermal method, and were characterized by field emission scanning electron microscopy and transmission electron microscopy. The adsorption as well as reduction properties of the obtained Fe-EG complex microspheres towards Cr(VI) ions were studied. The experiment data of adsorption kinetic and isotherm were fitted by nonlinear regression approach. In neutral condition, the maximum adsorption capacity was 49.78 mg g{sup −1} at room temperature, and was increased with the increasing of temperature. Thermodynamic parameters including the Gibbs free energy, standard enthalpy and standard entropy revealed that adsorption of Cr(VI) was a feasible, spontaneous and endothermic process. Spectroscopic analysis revealed the adsorption of Cr(VI) was a physical adsorption process. The adsorbed CrO{sub 4}{sup 2−} ions were partly reduced to Cr(OH){sub 3} by Fe(II) ions and the organic groups in the Fe-EG complex.

  8. Identification of residues of FpvA involved in the different steps of Pvd-Fe uptake in Pseudomonas aeruginosa.

    Science.gov (United States)

    Nader, Mirella; Dobbelaere, Wim; Vincent, Michel; Journet, Laure; Adams, Hendrik; Cobessi, David; Gallay, Jacques; Schalk, Isabelle J

    2007-10-23

    FpvA is an outer membrane transporter involved in iron uptake by the siderophore pyoverdine (Pvd) in Pseudomonas aeruginosa. This transporter, like all other proteins of the same family, consists of a transmembrane 22 beta-stranded barrel occluded by a plug domain. The beta-strands of the barrel are connected by large extracellular loops and short periplasmic turns. Site-directed mutagenesis was carried out on FpvA to identify the extracellular loops or parts of these loops involved in the various stages of Pvd-Fe uptake. The G286C, W362C, and W434C mutations in loops L1, L3, and L4, respectively, disturbed the binding of the apo siderophore, as shown by time-resolved fluorescence spectroscopy. Iron uptake experiments followed by fluorescence resonance energy transfer (FRET) or using 55Fe indicated that residues W434 and G701 and, therefore, loops L4 and L9 must be involved in Pvd-Fe uptake by FpvA. The two corresponding mutants incorporated smaller than normal amounts of 55Fe into cells, and no Pvd recycling on FpvA was observed after iron release. Surprisingly, the S603C mutation in loop L7 increased the amount of Pvd-Fe transported. Our results suggest that W434 (L4), S603 (L7), and G701 (L9) are involved in the mechanism of Pvd-Fe uptake.

  9. Geologic map of the Tetilla Peak Quadrangle, Santa Fe and Sandoval counties, New Mexico

    Science.gov (United States)

    Sawyer, D.A.; Shroba, R.R.; Minor, S.A.; Thompson, R.A.

    2002-01-01

    This digital geologic map summarizes all available geologic information for the Tetilla Peak quadrangle located immediately southwest of Santa Fe, New Mexico. The geologic map consists of new polygon (geologic map units) and line (contact, fault, fold axis, dike, flow contact, hachure) data, as well as point data (locations for structural measurements, geochemical and geochronologic data, geophysical soundings, and water wells). The map database has been generated at 1:24,000 scale, and provides significant new geologic information for an area of the southern Cerros del Rio volcanic field, which sits astride the boundary of the Espanola and Santo Domingo basins of the Rio Grande rift. The quadrangle includes the west part of the village of La Cienega along its eastern border and includes the southeasternmost part of the Cochiti Pueblo reservation along its northwest side. The central part of the quadrangle consists of Santa Fe National Forest and Bureau of Land Management lands, and parts of several Spanish-era land grants. Interstate 25 cuts through the southern half of the quadrangle between Santa Fe and Santo Domingo Pueblo. Canada de Santa Fe, a major river tributary to the Rio Grande, cuts through the quadrangle, but there is no dirt or paved road along the canyon bottom. A small abandoned uranium mine (the La Bajada mine) is found in the bottom of the Canada de Santa Fe about 3 km east of the La Bajada fault zone; it has been partially reclaimed. The surface geology of the Tetilla Peak quadrangle consists predominantly of a thin (1-2 m generally, locally as thick as 10? m) layer of windblown surficial deposits that has been reworked colluvially. Locally, landslide, fluvial, and pediment deposits are also important. These colluvial deposits mantle the principal bedrocks units, which are (from most to least common): (1) basalts, basanites, andesite, and trachyte of the Pliocene (2.7-2.2 Ma) Cerros del Rio volcanic field; (2) unconsolidated deposits of the Santa

  10. Modes of planetary-scale Fe isotope fractionation

    Science.gov (United States)

    Schoenberg, Ronny; von Blanckenburg, Friedhelm

    2006-12-01

    A comprehensive set of high-precision Fe isotope data for the principle meteorite types and silicate reservoirs of the Earth is used to investigate iron isotope fractionation at inter- and intra-planetary scales. 14 chondrite analyses yield a homogeneous Fe isotope composition with an average δ56Fe/ 54Fe value of - 0.015 ± 0.020‰ (2 SE) relative to the international iron standard IRMM-014. Eight non-cumulate and polymict eucrite meteorites that sample the silicate portion of the HED (howardite-eucrite-diogenite) parent body yield an average δ56Fe/ 54Fe value of - 0.001 ± 0.017‰, indistinguishable to the chondritic Fe isotope composition. Fe isotope ratios that are indistinguishable to the chondritic value have also been published for SNC meteorites. This inner-solar system homogeneity in Fe isotopes suggests that planetary accretion itself did not significantly fractionate iron. Nine mantle xenoliths yield a 2 σ envelope of - 0.13‰ to + 0.09‰ in δ56Fe/ 54Fe. Using this range as proxy for the bulk silicate Earth in a mass balance model places the Fe isotope composition of the outer liquid core that contains ca. 83% of Earth's total iron to within ± 0.020‰ of the chondritic δ56Fe/ 54Fe value. These calculations allow to interprete magmatic iron meteorites ( δ56Fe/ 54Fe = + 0.047 ± 0.016‰; N = 8) to be representative for the Earth's inner metallic core. Eight terrestrial basalt samples yield a homogeneous Fe isotope composition with an average δ56Fe/ 54Fe value of + 0.072 ± 0.016‰. The observation that terrestrial basalts appear to be slightly heavier than mantle xenoliths and that thus partial mantle melting preferentially transfers heavy iron into the melt [S. Weyer, A.D. Anbar, G.P. Brey, C. Munker, K. Mezger and A.B. Woodland, Iron isotope fractionation during planetary differentiation, Earth and Planetary Science Letters 240(2), 251-264, 2005.] is intriguing, but also raises some important questions: first it is questionable whether the

  11. Magnetic properties of sintered high energy sm-co and nd-fe-b magnets

    Directory of Open Access Journals (Sweden)

    Talijan Nadežda M.

    2006-01-01

    Full Text Available Magnetic properties of permanent magnetic materials based on intermetallic compounds of Sm-Co and Nd-Fe-B are in direct dependence on the microstructure. In the first part of this paper, having in mind the importance of the regime of sintering and heat treatment to obtain the optimal magnetic structure, yet another approach in defining the most adequate technological parameters of the sintering process for applied heat treatment conditions was made. The goal of these investigations was to use the correlation that exists between sintering conditions (temperature and time and intensity of the diffraction peak of the (111 plane of the SmCo5 phase to optimize. In the second part a brief overview of high energy magnetic materials based on Nd-Fe-B is presented with special emphasis to the current research and development of high remanent nanocomposite magnetic materials based on Nd-Fe-B alloys with a reduced Nd content. Part of experimental results gained during research of the sintering process of SmCo5 magnetic materials were realized and published earlier. The scientific meeting devoted to the 60th anniversary of Frankel’s theory of sintering was an opportunity to show once more the importance and role of sintering in optimization of the magnetic microstructure of sintered Sm Co5 magnetic materials.

  12. Moessbauer analysis and magnetic properties of Invar Fe-Ni-C and Fe-Ni-Mn-C alloys

    International Nuclear Information System (INIS)

    Nadutov, V. M.; Svystunov, Ye. O.; Kosintsev, S. G.; Tatarenko, V. A.

    2006-01-01

    The saturation magnetization and the hyperfine magnetic field of different f.c.c. Fe-Ni based alloys containing nearby 29 at .% Ni were studied as a function of temperature and for different Carbon and Manganese contents. We have observed abnormal behaviors that are explained in terms of mixed exchange interactions between atomic spins: J NiNi (r i ) FeFe (r i ) > 0, J NiFe (r i ) < 0.

  13. Mixed ligand complex formation of Fe with boric acid and typical N ...

    Indian Academy of Sciences (India)

    Unknown

    (b) Formation constants of FeIII – H3BO3 complexes. (i) Overall formation constants. Fe. ) BO. Fe(H. 4. 2 logβ. 3⋅67. Fe. ) BO. Fe(OH)(H. 4. 2 logβ. 1⋅16. Fe. ) BO. (H. Fe(OH). 4. 2. 2 logβ. –1⋅72. (ii) Effect of coordination with Fe(aq)3+, Fe(OH)2+ and Fe(OH). +. 2 on ionisation of. H3BO3. 3H. O]. H. BO. H. [Fe. 2. 3. 3 log. +. +.

  14. Structural and magnetic properties of evaporated Fe thin films on Si(1 1 1), Si(1 0 0) and glass substrates

    International Nuclear Information System (INIS)

    Ghebouli, B.; Cherif, S.-M.; Layadi, A.; Helifa, B.; Boudissa, M.

    2007-01-01

    We present experimental results on the structural and magnetic properties of series of Fe thin films evaporated onto Si(1 1 1), Si(1 0 0) and glass substrates. The Fe thickness, t, ranges from 6 to110 nm. X-ray diffraction (XRD) and atomic force microscopy (AFM) have been used to study the structure and surface morphology of these films. The magnetic properties were investigated by means of the Brillouin light scattering (BLS) and magnetic force microscopy (MFM) techniques. The Fe films grow with (1 1 0) texture; as t increases, this (1 1 0) texture becomes weaker for Fe/Si, while for Fe/glass, the texture changes from (1 1 0) to (2 1 1). Grains are larger in Fe/Si than in Fe/glass. The effective magnetization, 4πM eff , inferred from BLS was found to be lower than the 4πM S bulk value. Stress induced anisotropy might be in part responsible for this difference. MFM images reveal stripe domain structure for the 110 nm thick Fe/Si(1 0 0) only

  15. XMM–Newton and Suzaku analysis of the Fe K complex in the type 1 Seyfert galaxy Mrk 509

    NARCIS (Netherlands)

    Ponti, G.; Cappi, M.; Vignali, C.; Miniutti, G.; Tombesi, F.; Dadina, M.; Fabian, A.C.; Grandi, P.; Kaastra, J.S.; Petrucci, P.O.; Bianchi, S.; Matt, G.; Maraschi, L.; Malaguti, G.

    2009-01-01

    We report on partially overlapping XMM–Newton (∼~260 ks) and Suzaku (∼~100 ks) observations of the iron K band in the nearby, bright type 1 Seyfert galaxy Mrk 509. The source shows a resolved neutral Fe K line, most probably produced in the outer part of the accretion disc. Moreover, the source

  16. Efficient EBE treatment of the dynamic far-field in non-linear FE soil-structure interaction analyses

    NARCIS (Netherlands)

    Crouch, R.S.; Bennett, T.

    2000-01-01

    This paper presents results and observations from the use of a rigorous method of treating the dynamic far-field as part of a non-linear FE analysis. The technique de-veloped by Wolf and Song (referred to as the Scaled Boundary Finite-Element Method) is incorporated into a 3-D time-domain analysis

  17. Fusion of 48Ti+58Fe and 58Ni+54Fe below the Coulomb barrier

    Science.gov (United States)

    Stefanini, A. M.; Montagnoli, G.; Corradi, L.; Courtin, S.; Bourgin, D.; Fioretto, E.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Mijatović, T.; Montanari, D.; Pagliaroli, M.; Parascandolo, C.; Scarlassara, F.; Strano, E.; Szilner, S.; Toniolo, N.; Torresi, D.

    2015-12-01

    Background: No data on the fusion excitation function of 48Ti+58Fe in the energy region near the Coulomb barrier existed prior to the present work, while fusion of 58Ni+54Fe was investigated in detail some years ago, down to very low energies, and clear evidence of fusion hindrance was noticed at relatively high cross sections. 48Ti and 58Fe are soft and have a low-lying quadrupole excitation lying at ≈800 -900 keV only. Instead, 58Ni and 54Fe have a closed shell (protons and neutrons, respectively) and are rather rigid. Purpose: We aim to investigate (1) the possible influence of the different structures of the involved nuclei on the fusion excitation functions far below the barrier and, in particular, (2) whether hindrance is observed in 48Ti+58Fe , and to compare the results with current coupled-channels models. Methods: 48Ti beams from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro were used. The experimental setup was based on an electrostatic beam separator, and fusion-evaporation residues (ERs) were detected at very forward angles. Angular distributions of ERs were measured. Results: Fusion cross sections of 48Ti+58Fe have been obtained in a range of nearly six orders of magnitude around the Coulomb barrier, down to σ ≃2 μ b . The sub-barrier cross sections of 48Ti+58Fe are much larger than those of 58Ni+54Fe . Significant differences are also observed in the logarithmic derivatives and astrophysical S factors. No evidence of hindrance is observed, because coupled-channels calculations using a standard Woods-Saxon potential are able to reproduce the data in the whole measured energy range. Analogous calculations for 58Ni+54Fe predict clearly too large cross sections at low energies. The two fusion barrier distributions are wide and display a complex structure that is only qualitatively fit by calculations. Conclusions: It is pointed out that all these different trends originate from the dissimilar low-energy nuclear structures of

  18. Low 60Fe Abundance in Semarkona and Sahara 99555

    Science.gov (United States)

    Tang, Haolan; Dauphas, Nicolas

    2015-03-01

    Iron-60 (t1/2 = 2.62 Myr) is a short-lived nuclide that can help constrain the astrophysical context of Solar System formation and date early Solar System events. A high abundance of 60Fe(60Fe/56Fe ≈ 4 × 10-7) was reported by in situ techniques in some chondrules from the LL3.00 Semarkona meteorite, which was taken as evidence that a supernova exploded in the vicinity of the birthplace of the Sun. However, our previous multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) measurements of a wide range of meteoritic materials, including chondrules, showed that 60Fe was present in the early Solar System at a much lower level (60Fe/56Fe ≈ 10-8). The reason for the discrepancy is unknown but only two Semarkona chondrules were measured by MC-ICPMS and these had Fe/Ni ratios below ˜2× chondritic. Here, we show that the initial 60Fe/56Fe ratio in Semarkona chondrules with Fe/Ni ratios up to ˜24× chondritic is (5.39 ± 3.27) × 10-9. We also establish the initial 60Fe/56Fe ratio at the time of crystallization of the Sahara 99555 angrite, a chronological anchor, to be (1.97 ± 0.77) × 10-9. These results demonstrate that the initial abundance of 60Fe at Solar System birth was low, corresponding to an initial 60Fe/56Fe ratio of (1.01 ± 0.27) × 10-8.

  19. LOW {sup 60}FE ABUNDANCE IN SEMARKONA AND SAHARA 99555

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Haolan; Dauphas, Nicolas, E-mail: haolantang@ucla.edu [Origins Lab, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago IL 60637 (United States)

    2015-03-20

    Iron-60 (t{sub 1/2} = 2.62 Myr) is a short-lived nuclide that can help constrain the astrophysical context of Solar System formation and date early Solar System events. A high abundance of {sup 60}Fe({sup 60}Fe/{sup 56}Fe ≈ 4 × 10{sup −7}) was reported by in situ techniques in some chondrules from the LL3.00 Semarkona meteorite, which was taken as evidence that a supernova exploded in the vicinity of the birthplace of the Sun. However, our previous multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) measurements of a wide range of meteoritic materials, including chondrules, showed that {sup 60}Fe was present in the early Solar System at a much lower level ({sup 60}Fe/{sup 56}Fe ≈ 10{sup −8}). The reason for the discrepancy is unknown but only two Semarkona chondrules were measured by MC-ICPMS and these had Fe/Ni ratios below ∼2× chondritic. Here, we show that the initial {sup 60}Fe/{sup 56}Fe ratio in Semarkona chondrules with Fe/Ni ratios up to ∼24× chondritic is (5.39 ± 3.27) × 10{sup −9}. We also establish the initial {sup 60}Fe/{sup 56}Fe ratio at the time of crystallization of the Sahara 99555 angrite, a chronological anchor, to be (1.97 ± 0.77) × 10{sup −9}. These results demonstrate that the initial abundance of {sup 60}Fe at Solar System birth was low, corresponding to an initial {sup 60}Fe/{sup 56}Fe ratio of (1.01 ± 0.27) × 10{sup −8}.

  20. Fe-Ti/Fe (II)-loading on ceramic filter materials for residual chlorine removal from drinking water.

    Science.gov (United States)

    Man, Kexin; Zhu, Qi; Guo, Zheng; Xing, Zipeng

    2018-06-01

    Ceramic filter material was prepared with silicon dioxide (SiO 2 ), which was recovered from red mud and then modified with Fe (II) and Fe-Ti bimetal oxide. Ceramic filter material can be used to reduce the content of residual chlorine from drinking water. The results showed that after a two-step leaching process with 3 M hydrochloric acid (HCl) and 90% sulfuric acid (H 2 SO 4 ), the recovery of SiO 2 exceeded 80%. Fe (II)/Fe-Ti bimetal oxide, with a high adsorption capacity of residual chlorine, was prepared using a 3:1 M ratio of Fe/Ti and a concentration of 0.4 mol/L Fe 2+ . According to the zeta-potential, scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis, Fe (II) and Fe-Ti bimetal oxide altered the zeta potential and structural properties of the ceramic filter material. There was a synergistic interaction between Fe and Ti in which FeOTi bonds on the material surface and hydroxyl groups provided the active sites for adsorption. Through a redox reaction, Fe (II) transfers hypochlorite to chloride, and FeOTiCl bonds were formed after adsorption. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Using in vitro maturation and cell-free expression to explore [FeFe] hydrogenase activation and protein scaffolding requirements

    Energy Technology Data Exchange (ETDEWEB)

    Swartz, James [Stanford Univ., CA (United States)

    2017-01-25

    Final Project Report describing work to elucidate mechanisms for the activation of [FeFe]-hydrogenases and to explore the impact of the polypeptide scaffolding on the function of the Fe-S redox and catalytic centers with emphasis on improving oxygen tolerance.

  2. Influence of Fe content on the structural and optical properties of ZnFeS thin films

    International Nuclear Information System (INIS)

    Feng, Q.J.; Shen, D.Z.; Zhang, J.Y.; Lu, Y.M.; Liu, Y.C.; Fan, X.W.

    2006-01-01

    ZnFeS thin films have been grown on c-plane sapphire substrate using low-pressure metalorganic chemical vapor deposition (LP-MOCVD) equipment. The X-ray diffraction (XRD) patterns indicated that the diffraction peaks positions of ZnFeS thin films shifts gradually towards the lower angle side due to substitution of Zn by Fe atoms in the crystal lattice with increasing Fe content. When gas flow rates of Fe (CO) 5 varied from 1 to 6 ml min -1 , crystalline phase of the ZnFeS thin film changed from the hexagonal to cubic structure. And when gas flow rates of Fe (CO) 5 was less than 6 ml min -1 , ZnFeS single-crystal structure was obtained. From the measurements of optical absorption spectrum, the energy gaps of the samples were evidently narrowed with increasing Fe component. The electronic states of ZnFeS were investigated by X-ray photoelectron spectroscopy (XPS). It was found that the S 2p shifted towards higher binding energies side due to the larger bond strength of Fe-S than that of Zn-S, but the Fe incorporated into the ZnS lattice did not affect the Zn 2p core levels

  3. Uptake and Release of Cerium During Fe-Oxide Formation and Transformation in Fe(II) Solutions

    DEFF Research Database (Denmark)

    Nedel, Sorin; Dideriksen, Knud; Christiansen, Bo C.

    2010-01-01

    Fe-oxides are ubiquitous in soils and sediments and form during Fe(0) corrosion. Depending on redox conditions and solution composition, Fe-oxides such as ferrihydrite, goethite, magnetite, and green rust (GR) may form. These phases typically have high surface area and large affinity for adsorpti...

  4. Determination of element distribution between the symplasm and apoplasm of cucumber plant parts by total reflection X-ray fluorescence spectrometry.

    Science.gov (United States)

    Varga, Anita; Záray, Gyula; Fodor, Ferenc

    2002-04-10

    The distribution of Cd, Ni, Pb and Fe between the symplasm (cytoplasm) and apoplasm (cell wall) of cucumber roots and leaves was determined by total reflection X-ray fluorescence spectrometry following a special sample preparation procedure. The plants were grown in modified Hoagland nutrient solution containing Fe in chemical form of Fe(III)-citrate or Fe(III)-EDTA, as well as the heavy metal contaminants, each in concentration of 10 microM. In the roots the larger part of Pb was found in the apoplasm, while Ni and Cd were mostly in the symplasm. In the leaves however, about 50-60% of the Pb content and practically the total amount of Cd were detected in the symplasm. About 30-40% of the translocated Ni remained in the apoplasm of the leaves. The Cd-, Ni- and Pb-treatments resulted in higher total concentration of Fe in the roots, however, the relative amount of Fe in the symplasm decreased in all cases. In the leaves of the control plants the larger part (60-80%) of Fe occurs in the symplasm. Due to the heavy metal effects, the relative amount of Fe in the symplasm decreased except in the Pb-contaminated plants, where in the presence of Fe(III)-EDTA, the Pb treatment resulted in a moderate increment of Fe concentration in the symplasm.

  5. Correlation between impurities in Fe-Si amorphous layers synthesized by Fe implantation and photoluminescence property of {beta}-FeSi{sub 2} precipitates in Si

    Energy Technology Data Exchange (ETDEWEB)

    Sun, C.M. [Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, N.T., Hong Kong (China)], E-mail: cmsun@ee.cuhk.edu.hk; Tsang, H.K.; Wong, S.P.; Ke, N. [Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, N.T., Hong Kong (China); Hark, S.K. [Department of Physics, Chinese University of Hong Kong, Shatin, N.T., Hong Kong (China)

    2008-11-15

    Completely amorphous Fe-Si layers are formed by Fe implantation into Si substrate at a dosage of 5x10{sup 15} cm{sup -2} using a metal vapor vacuum arc (MEVVA) ion source under 80 kV extraction voltage and cryogenic temperature. After thermal annealing, {beta}-FeSi{sub 2} precipitates are formed in Si matrix. The influence of impurities in these amorphous Fe-Si layers on the photoluminescence (PL) from {beta}-FeSi{sub 2} precipitates is investigated. PL is found to be significantly enhanced by optimizing the impurity concentration and annealing scheme. After 60 s of rapid thermal annealing (RTA) at 900 deg. C, {beta}-FeSi{sub 2} precipitates in medium boron-doped Si substrate give the strongest PL intensity without boron out-diffusion from them.

  6. Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

    Energy Technology Data Exchange (ETDEWEB)

    Gueneau, C. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Procedes d`Enrichissement]|[Paris-11 Univ., 91 - Orsay (France)]|[Compagnie de Produits Chimiques et Electrometallurgiques Pechiney, 74 - Passy-Chedde (France). Lab. Graphitation; Servant, C. [Paris-11 Univ., 91 - Orsay (France); Ansara, I. [Ecole Nationale Superieure d`Electrochimie et d`Electrometallurgie, 38 - Grenoble (France)

    1994-12-31

    The substitutions of Al <-> Si, Fe <-> Mn and Fe <-> Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil`s model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs.

  7. Kinetics of FeII-polyaminocarboxylate oxidation by molecular oxygen

    Science.gov (United States)

    Wilson, Jessica M.; Farley, Kevin J.; Carbonaro, Richard F.

    2018-03-01

    Complexation of iron by naturally-occurring and synthetic organic ligands has a large effect on iron oxidation and reduction rates which in turn affect the aqueous geochemistry of many other chemical constituents. In this study, the kinetics of FeII oxidation in the presence of the polyaminocarboxylate synthetic chelating agents ethylene glycol tetraacetic acid (EGTA) and trimethylenediamine-N,N,N‧,N‧-tetraacetic acid (TMDTA) was investigated over the pH range 5.50-8.53. Batch oxidation experiments in the presence of molecular oxygen were conducted using a 2:1 M concentration ratio of polyaminocarboxylate (ligand, L) to FeII. The experimental data resembled first order kinetics for the oxidation of FeII-L to FeIII-L and observed rate constants at pH 6.0 were comparable to rate constants for the oxidation of inorganic FeII. Similar to other structurally-similar FeII-polyaminocarboxylate complexes, oxidation rates of FeII-EGTA and FeII-TMDTA decrease with increasing pH, which is the opposite trend for the oxidation of FeII complexed with inorganic ligands. However, the oxidation rates of FeII complexed with EGTA and TMDTA were considerably lower (4-5 orders of magnitude) than FeII complexed to ethylenediaminetetraacetic acid (EDTA). The distinguishing feature of the slower-reacting complexes is that they have a longer backbone between diamine functional groups. An analytical equilibrium model was developed to determine the contributions of the species FeIIL2- and FeII(H)L- to the overall oxidation rate of FeII-L. Application of this model indicated that the protonated FeII(H)L species are more than three orders of magnitude more reactive than FeIIL2-. These rate constants were used in a coupled kinetic equilibrium numerical model where the ligand to iron ratio (TOTL:TOTFe) and pH were varied to evaluate the effect on the FeII oxidation rate. Overall, increasing TOTL:TOTFe for EGTA and TMDTA enhances FeII oxidation rates at lower pH and inhibits FeII oxidation

  8. The activation mechanism of Fe-based olefin metathesis catalysts

    Science.gov (United States)

    Poater, Albert; Pump, Eva; Vummaleti, Sai Vikrama Chaitanya; Cavallo, Luigi

    2014-08-01

    Density functional theory calculations have been used to describe the first turnover for olefin metathesis reaction of a homogenous Fe-based catalyst bearing a N-heterocyclic carbene ligand with methoxyethene as a substrate. Equal to conventional Ru-based catalysts, the activation of its Fe congener occurs through a dissociative mechanism, however with a more exothermic reaction energy profile. Predicted upper energy barriers were calculated to be on average ∼2 kcal/mol more beneficial for Fe catalyzed metathesis. Overall, this present computational study emphasises on advantages of Fe-based metathesis and gives a potential recipe for the design of an efficient Fe-based olefin metathesis catalysts.

  9. INAA analysis of rocks: A routine method using Fe as an internal flux monitor

    International Nuclear Information System (INIS)

    Kay, R.W.; Kay, S. Mahlburg

    1992-01-01

    Over the past decade at Cornell, trace elements in over 2500 rocks have been analyzed by INAA. The samples, mainly volcanic rocks, have known concentrations of major elements (e.g. Si, Ti, Al, Mg, Ca, K, Fe, Na) and the last two of these (Fe and Na) are also determined by activation, using rock standards (e.g. USGS standards BCRl, BHVO, etc.). Differences between Fe determined by INAA and that determined as a part of the major element analysis are mainly attributed to volatile (H 2 O, CO 2 ) loss (especially when major element analyses were done by electron microprobe on fused powders, whereas the INAA analyses were done on the powders), and to flux variability during irradiation. Instead of reporting two values for Fe we use Fe as an internal flux monitor, with Na and the trace elements being reported relative to the given Fe value. The ratio Na/Fe is used as a sensitive check on the identity of the sample and as a monitor of alkali loss affecting the major element analysis. Other than this modification (Kay et aL 1987, also reported in Chappell and Hergt, 1989) we use an INAA method similar to mat practiced by many labs. Powdered samples (about 0.5 g) are sealed in high-purity silica tubes and irradiated in the Cornell Triga reactor. Samples are counted for a minimum of 2 hours (up to 10 hours) 7 and 40 days after irradiation. Data are reduced using a program written at Cornell, with peak and background regions that have been checked for interferences. Corrections are routinely applied for Ce (Fe), Nd (Br), Tb (Th), Eu (Ba), Lu (U), and Yb (Th) (interference is from element in parentheses). A U fission yield correction is applied to La, Ce, Nd, and Ba. A correction for Ta introduced by grinding in WC containers can be made using known Ta/W ratios in the grinding containers. The correction amounted to 10-20% of the Ta gross peak. Recently, samples have been prepared in a ceramic grinding containers; for these, no Ta correction is needed. Trace elements determined

  10. Characterization of Bi and Fe co-doped PZT capacitors for FeRAM

    Directory of Open Access Journals (Sweden)

    Jeffrey S Cross, Seung-Hyun Kim, Satoshi Wada and Abhijit Chatterjee

    2010-01-01

    Full Text Available Ferroelectric random access memory (FeRAM has been in mass production for over 15 years. Higher polarization ferroelectric materials are needed for future devices which can operate above about 100 °C. With this goal in mind, co-doping of thin Pb(Zr40,Ti60O3 (PZT films with 1 at.% Bi and 1 at.% Fe was examined in order to enhance the ferroelectric properties as well as characterize the doped material. The XRD patterns of PZT-5% BiFeO3 (BF and PZT 140-nm thick films showed (111 orientation on (111 platinized Si wafers and a 30 °C increase in the tetragonal to cubic phase transition temperature, often called the Curie temperature, from 350 to 380 °C with co-doping, indicating that Bi and Fe are substituting into the PZT lattice. Raman spectra revealed decreased band intensity with Bi and Fe co-doping of PZT compared to PZT. Polarization hysteresis loops show similar values of remanent polarization, but square-shaped voltage pulse-measured net polarization values of PZT-BF were higher and showed higher endurance to repeated cycling up to 1010 cycles. It is proposed that Bi and Fe are both in the +3 oxidation state and substituting into the perovskite A and B sites, respectively. Substitution of Bi and Fe into the PZT lattice likely creates defect dipoles, which increase the net polarization when measured by the short voltage pulse positive-up-negative-down (PUND method.

  11. Protonation/reduction dynamics at the [4Fe-4S] cluster of the hydrogen-forming cofactor in [FeFe]-hydrogenases.

    Science.gov (United States)

    Senger, Moritz; Mebs, Stefan; Duan, Jifu; Shulenina, Olga; Laun, Konstantin; Kertess, Leonie; Wittkamp, Florian; Apfel, Ulf-Peter; Happe, Thomas; Winkler, Martin; Haumann, Michael; Stripp, Sven T

    2018-01-31

    The [FeFe]-hydrogenases of bacteria and algae are the most efficient hydrogen conversion catalysts in nature. Their active-site cofactor (H-cluster) comprises a [4Fe-4S] cluster linked to a unique diiron site that binds three carbon monoxide (CO) and two cyanide (CN - ) ligands. Understanding microbial hydrogen conversion requires elucidation of the interplay of proton and electron transfer events at the H-cluster. We performed real-time spectroscopy on [FeFe]-hydrogenase protein films under controlled variation of atmospheric gas composition, sample pH, and reductant concentration. Attenuated total reflection Fourier-transform infrared spectroscopy was used to monitor shifts of the CO/CN - vibrational bands in response to redox and protonation changes. Three different [FeFe]-hydrogenases and several protein and cofactor variants were compared, including element and isotopic exchange studies. A protonated equivalent (HoxH) of the oxidized state (Hox) was found, which preferentially accumulated at acidic pH and under reducing conditions. We show that the one-electron reduced state Hred' represents an intrinsically protonated species. Interestingly, the formation of HoxH and Hred' was independent of the established proton pathway to the diiron site. Quantum chemical calculations of the respective CO/CN - infrared band patterns favored a cysteine ligand of the [4Fe-4S] cluster as the protonation site in HoxH and Hred'. We propose that proton-coupled electron transfer facilitates reduction of the [4Fe-4S] cluster and prevents premature formation of a hydride at the catalytic diiron site. Our findings imply that protonation events both at the [4Fe-4S] cluster and at the diiron site of the H-cluster are important in the hydrogen conversion reaction of [FeFe]-hydrogenases.

  12. Synthesis, Electromagnetic and Wave-Absorbing Properties of a FeNi Alloy Nano-Whisker/Particle Mixture

    Science.gov (United States)

    Zhou, Jia; Zhu, Zheng-Hou; Xiong, Chao

    2018-02-01

    A Fe20Ni80 alloy nano-whisker/particle mixture was synthesized by a hydrazine hydrate reduction method at 60°C. Electromagnetic parameters of the alloy nano-whisker/particle mixture after a 0.3-T magnetic treatment were measured in the 1.0-8.0 GHz range using an E5063A vector network analyzer. The results showed that the real part ( ɛ') of the complex permittivity of the Fe20Ni80 alloy nano-whisker/particle mixture in the 1.0-8.0 GHz range was between 23 and 18, and the imaginary part ( ɛ″) was approximately 4. The real part ( μ') of the complex permeability in 1.0-5.0 GHz range decreased greatly with increasing frequency, from a maximum of 2.5 to a minimum of 1. The imaginary part ( μ″) presented a parabolic shape change; when the frequency was 4.0 GHz, there was a maximum of 1.5. After the 0.3-T magnetic treatment, both the real part ( ɛ') and the imaginary part ( ɛ″) of the complex permittivity decreased: the real part ( μ') of the complex permeability increased sharply, and the imaginary part ( μ″) decreased slightly. The dissipation factor ( tgδ) of the Fe20Ni80 alloy nano-whisker/particle mixture in the 4.0-7.0 GHz range was approximately 1.0, which shows it has excellent wave-absorbing properties. The thickness of interference-absorbing was approximately 11 mm at 1.0 GHz; it decreased with increasing frequency. The thickness of interference-absorbing was 2.5-2 mm in the 4.0-8.0 GHz range, which shows that the Fe20Ni80 alloy nano-whisker/particle mixture has good interference-absorbing properties when the thickness is 2 mm.

  13. Forging of FeAl intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Flores, O.; Juarez, J.; Campillo, B.; Martinez, L. [UNAM, Cuernavaca (Mexico). Lab. de Cuernavaca; Schneibel, J.H. [Oak Ridge National Lab., TN (United States)

    1994-09-01

    Much activity has been concentrated on the development of intermetallic compounds with the aim of improving tensile ductility, fracture toughness and high notch sensitivity in order to develop an attractive combination of properties for high and low temperature applications. This paper reports experience in processing and forging of FeAl intermetallic of B2 type. During the experiments two different temperatures were employed, and the specimens were forged after annealing in air, 10{sup {minus}2} torr vacuum and argon. From the results it was learned that annealing FeAl in argon atmosphere prior to forging resulted in better deformation behavior than for the other two environments. For the higher forging temperature used in the experiments (700C), the as-cast microstructure becomes partially recrystallized.

  14. 3D Computer Models of T- x- y Diagrams, Forming the Fe-Ni-Co-FeS-NiS-CoS Subsystem

    Science.gov (United States)

    Lutsyk, V. I.; Vorob'eva, V. P.

    2017-12-01

    3D computer models of Fe-Ni-Co, Fe-Ni-FeS-NiS, Fe-Co-FeS-CoS, Ni-Co-NiS-CoS T- x- y diagrams have been designed. The geometric structure (35 surfaces, two-phase surface of the reaction type change, 17 phase regions) of the Fe-Ni-FeS-NiS T- x- y diagram is investigated in detail. The liquidus hypersurfaces prediction of the Fe-Ni-Co-FeS-NiS-CoS subsystem is represented.

  15. Fe2O3 magnetic nanoparticles to enhance S. lycopersicum (tomato) plant growth and their biomineralization

    Science.gov (United States)

    Shankramma, K.; Yallappa, S.; Shivanna, M. B.; Manjanna, J.

    2016-10-01

    In the present study, we demonstrate magnetic iron (III) oxide nanoparticles (Fe2O3 NPs) uptake by the Solanum lycopersicum ( S. lycopersicum) plant. The S. lycopersicum seeds were coated with Fe2O3 NPs and allowed to germinate in moistened sand bed. The seedlings are observed for 20 days, and then, it was post-treated using different amounts of Fe2O3 NPs in hydroponic solution for 10 days. The plant was allowed to grow in green house for 3 months, and uptake of NPs through roots and translocation into different parts was studied. For this, we have segmented the plants and incubated with 10 % NaOH solution. It is found that the NPs are deposited preferentially in root hairs, root tips followed by nodal and middle zone of plant. The iron present in the whole plant was quantitatively estimated by treating dry biomass of the plant in acid. The Fe2+/Fetotal increased with increasing concentration of NPs and >45 % ferrous iron suggests the biomineralization of NPs due to rich phytochemicals in plants. We believe that the present study is useful to build a base line data for novel applications in agri-nanotechnology.

  16. Molecular adsorption of hydrogen peroxide on N- and Fe-doped titania nanoclusters

    Science.gov (United States)

    Mohajeri, Afshan; Dashti, Nasimeh Lari

    2017-06-01

    Titanium dioxide (titania) nanoparticles have been extensively investigated for photocatalytic applications such as the decomposition and adsorption of pollutant and undesirable compound in air and waste water. In this context, the present article reports the molecular adsorption of hydrogen peroxide on the surface of doped titania clusters. Density functional theory calculations were performed to investigate the structures and electronic properties of two nanoscale (TiO2)n clusters (n = 5,6) modified by nitrogen and iron dopants. The relative stability of all possible N-doped and Fe-doped isomers has been compared with each other and with the parent cluster. It was found that the Fe-doped clusters are in general more stable than the N-doped counterparts. Moreover, after N/Fe doping an enhanced in the magnetization of the clusters is observed. In the second part, we have investigated different modes of H2O2 adsorption on the lowest-energy isomers of doped clusters. In almost all the cases, the adsorptions on the doped clusters are found to be less exothermic than on the corresponding undoped parent cluster. Our results highlight the essential role of charge transfer into the interaction between H2O2 and doped (TiO2)n clusters, especially for Fe-doped clusters.

  17. FeNO levels increase with degree of sensitisation in apprentices at risk of occupational asthma.

    Science.gov (United States)

    Wild, P; Mével, H; Penven, E; Zmirou-Navier, D; Barbaud, A; Bohadana, A; Paris, C

    2017-11-01

    Atopy has emerged as a major determinant of airway inflammation. To examine whether early markers of occupational asthma increase with degree of sensitisation. This study was a prospective follow-up study of apprentices in baking, pastry-cooking and hairdressing during their 2-year apprenticeship. Four visits were conducted to administer a standardised questionnaire, a methacholine challenge test to assess bronchial hyperresponsiveness (BHR) and to measure fractional exhaled nitric oxide (FeNO). Degree of sensitisation was estimated based on the number of positive skin prick tests (SPTs) for 12 common allergens. Mixed-effect models were applied to examine the association between the degree of sensitisation and FeNO levels, BHR and eosinophilic status (more than 3% of cells in nasal lavage fluid). Of the 441 apprentices who agreed to take part in the study, 417 had at least one SPT session providing usable results. Degree of sensitization was related to BHR and FeNO levels. Compared to non-sensitised subjects, FeNO levels were 83% higher (P < 0.01) in highly sensitised subjects and 30% higher (P < 0.01) in weakly sensitised subjects. However, the degree of sensitisation was not predictive of the evolution of these markers. Degree of sensitisation is related to early markers of airway inflammation.

  18. Experimental investigation of the stability of Fe-rich carbonates in the lower mantle

    Science.gov (United States)

    Boulard, E.; Menguy, N.; Auzende, A.; Benzerara, K.; Bureau, H.; Antonangeli, D.; Corgne, A.; Morard, G.; Siebert, J.; Perrillat, J.; Guyot, F. J.; Fiquet, G.

    2011-12-01

    Carbonates are the main C-bearing minerals that are transported deep in the Earth's mantle via subduction of the oceanic lithosphere [1]. The fate of carbonates at mantle conditions plays a key role in the deep carbon cycle. Decarbonation, melting or reduction of carbonates will affect the extent and the way carbon is recycled into the deep Earth. To clarify the fate of carbonates in the deep mantle, high-pressure high-temperature experiments were carried out up to 105 GPa and 2850 K on oxide assemblages of (Mg,Fe)O + CO2. The presence of Fe(II) in starting materials induces redox reactions from which Fe(II) is oxidized and a part of the carbon is reduced. This leads to an assemblage of magnetite, diamonds, and carbonates or, pressure depending, their newly discovered Fe(III)-bearing high-pressure polymorphs based on a silicate-like chemistry with tetrahedrally coordinated carbon [2]. Our results show the possibility for carbon to be recycled in the lowermost mantle and provide evidence of a possible coexistence of reduced and oxidized carbon at lower mantle conditions. [1] Sleep, N. H., and K. Zahnle (2001) J. Geophys. Res.-Planets 106(E1), 1373-1399. [2] Boulard et al. (2011) PNAS, 108, 5184-5187.

  19. Physiology, Fe(II oxidation, and Fe mineral formation by a marine planktonic cyanobacterium grown under ferruginous conditions

    Directory of Open Access Journals (Sweden)

    Elizabeth D. Swanner

    2015-10-01

    Full Text Available Evidence for Fe(II oxidation and deposition of Fe(III-bearing minerals from anoxic or redox-stratified Precambrian oceans has received support from decades of sedimentological and geochemical investigation of Banded Iron Formations (BIF. While the exact mechanisms of Fe(II oxidation remains equivocal, reaction with O2 in the marine water column, produced by cyanobacteria or early oxygenic phototrophs, was likely. In order to understand the role of cyanobacteria in the deposition of Fe(III minerals to BIF, we must first know how planktonic marine cyanobacteria respond to ferruginous (anoxic and Fe(II-rich waters in terms of growth, Fe uptake and homeostasis, and Fe mineral formation. We therefore grew the common marine cyanobacterium Synechococcus PCC 7002 in closed bottles that began anoxic, and contained Fe(II concentrations that span the range of possible concentrations in Precambrian seawater. These results, along with cell suspension experiments, indicate that Fe(II is likely oxidized by this strain via chemical oxidation with oxygen produced during photosynthesis, and not via any direct enzymatic or photosynthetic pathway. Imaging of the cell-mineral aggregates with scanning electron microscopy (SEM and confocal laser scanning microscopy (CLSM are consistent with extracellular precipitation of Fe(III (oxyhydroxide minerals, but that >10% of Fe(III sorbs to cell surfaces rather than precipitating. Proteomic experiments support the role of reactive oxygen species (ROS in Fe(II toxicity to Synechococcus PCC 7002. The proteome expressed under low Fe conditions included multiple siderophore biosynthesis and siderophore and Fe transporter proteins, but most siderophores are not expressed during growth with Fe(II. These results provide a mechanistic and quantitative framework for evaluating the geochemical consequences of perhaps life’s greatest metabolic innovation, i.e. the evolution and activity of oxygenic photosynthesis, in ferruginous

  20. Electrochemical and theoretical studies of the interactions of a pyridyl-based corrosion inhibitor with iron clusters (Fe15, Fe30, Fe45, and Fe60).

    Science.gov (United States)

    Cruz-Borbolla, Julian; Garcia-Ochoa, Esteban; Narayanan, Jayanthi; Maldonado-Rivas, Pablo; Pandiyan, Thangarasu; Vásquez-Pérez, José M

    2017-11-15

    The capacity of 2,6-bis[((2-pyridylmethyl)oxy)methyl)]pyridine (BPMMP) to inhibit the corrosion of mild carbon steel in HCl was analyzed. In a polarization study, both the cathodic and anodic currents were appreciably decreased in the presence of BPMMP, suggesting that this ligand is effective at inhibiting corrosion at the metal surface. This conclusion is consistent with the results of impedance analysis, where only one time constant corresponding to one depressed capacitive loop was detected, and the diameter of the impedance plot was directly related to the concentration of BPMMP. Furthermore, when recurrence analysis was performed, a decrease in regular noise was observed due to the change of Shannon entropy when the inhibitor was present in the corrosive medium, showing that a high degree of recurrence increases the entropy of the system. Electrochemical data on some pyridyl-based inhibitors were collected from the literature and used to plot (i) I corr (A/cm 2 ) vs. inhibition efficiency (η%) and (ii) ΔG° ads vs. inhibition efficiency (ƞ%) in order to examine the general relationships between these parameters. Furthermore, the interactions of the ligand BPMMP with different iron clusters (Fe 15 , Fe 30 , Fe 45 , and Fe 60 ) were analyzed theoretically using density functional theory (DFT). The structural and electronic properties of BPMMP and its protonated form BPMMPH + were studied before and after the interactions of BPMMP with the iron clusters. The first protonation was found to occur at pyridine nitrogen atom N1, resulting in a Gibbs free energy ΔG of -10.2 kcal/mol, with an energy difference of 5.3 kcal/mol between the two possible protonated conformers. Graphical abstract Recurrence and Noise signal performance of BPMMP as corrosion inhibitor.

  1. First 3- excited state of 56Fe

    International Nuclear Information System (INIS)

    Fotiades, N.; Nelson, R. O.; Devlin, M.

    2010-01-01

    There is no reliable evidence for the existence of the 3.076 MeV (3 - ) level adopted in the ENSDF evaluation for 56 Fe although it has been reported in a few experiments. Previous reports of the observation of this level appear to be based on an incorrect assignment in early (e,e ' ) work. Recent neutron inelastic scattering measurements by Demidov et al. [Phys. At. Nucl. 67, 1884, (2004)] show that the assigned γ-ray decay of this state does not occur at a level consistent with known properties of inelastic scattering. In the present work the 56 Fe(n,n ' γ) reaction was used to populate excited states in 56 Fe. Neutrons in the energy range from 1 to 250 MeV were provided by the pulsed neutron source of the Los Alamos Neutron Science Center's WNR facility. Deexciting γ rays were detected with the GEANIE spectrometer, a Compton suppressed array of 26 Ge detectors. The γ-γ data obtained with GEANIE were used to establish coincidence relations between transitions. All previously reported levels up to E x =3.6 MeV excitation energy were observed except for the 3.076 MeV (3 - ) level. The 991- and 2229-keV transitions, previously reported to deexcite this level, were not observed in the γ-γ coincidence data obtained in the present experiment. The present work supports the assignment of the 4509.6 keV level as the first 3 - excited state in 56 Fe by observation of two previously known transitions deexciting this state.

  2. Corroded microstructure of HDDR-NdFeB magnetic powders

    International Nuclear Information System (INIS)

    Zhu, L.Y.; Itakura, M.; Tomokiyo, Y.; Kuwano, N.; Machida, K.

    2004-01-01

    The microstructure of corroded HDDR-NdFeB magnetic powders in bonded magnet has been investigated by transmission electron microscopy. Following an exposure time of 300 h at 398 K in air, the HDDR-NdFeB magnetic powders are found covered with an altered layer about 300 nm thick on the surface. The layer is composed of α-Fe grains 5-10 nm in diameter and h-Nd 2 O 3 grains smaller than 5 nm. Under the altered layer, corrosion has proceeded along the Nd 2 (Fe,Co) 14 B grain boundaries to leave a wetting layer composed of a dense mixture of α-Fe and h-Nd 2 O 3 phase. The appearance of α-Fe grains in both of the altered layer wetting layer leads to the high magnetic flux loss of the corroded HDDR-NdFeB bonded magnet

  3. Theoretical calculations of valence states in Fe-Mo compounds

    International Nuclear Information System (INIS)

    Estrada, F; Navarro, O; Noverola, H; Suárez, J R; Avignon, M

    2014-01-01

    The half-metallic ferromagnetic double perovskite compound Sr 2 FeMoO 6 is considered as an important material for spintronic applications. It appears to be fundamental to understand the role of electronic parameters controlling the half-metallic ground state. Fe-Mo double perovskites usually present some degree of Fe/Mo disorder which generally increases with doping. In this work, we study the valence states of Fe-Mo cations in the off-stoichiometric system Sr 2 Fe 1+x Mo 1−x O 6 (−1 ≤ x ≤ 1/3) with disorder. Our results for Fe and Mo valence states are obtained using the Green functions and the renormalization perturbation expansion method. The model is based on a correlated electron picture with localized Fe-spins and conduction Mo-electrons interacting with the local spins via a double-exchange-type mechanism

  4. Micro-PIXE evaluation of Fe distribution in barley roots

    International Nuclear Information System (INIS)

    Schneider, T.; Povh, B.; Strasser, O.; Gierth, M.; Przybylowicz, W.; Mesjasz-Przybylowicz, J.; Churms, C.; Schuessler, A.

    1999-01-01

    High Fe concentrations were reported from roots of plants grown in soil. This has been discussed as a possible Fe source for plants, since the concentrations shown in the roots were much higher than in the shoots. There are, however, also some indications that soil contamination at the root surface of soil grown plants could have led to an overestimation of the Fe concentration in roots. Fe distribution in root cross sections of barley (Hordeum vulgare L. cv. Alexis) has been studied to investigate this hypothesis. Micro-PIXE analyses in point and mapping mode were complemented by the STIM technique. Based on the correlation between Fe and soil-related elements (Ti, Al and Si), most of Fe located at the root surface could be attributed to soil contamination. It could also be shown that this soil contamination leads to an overestimation of Fe concentration in roots. (author)

  5. Speciation of Fe in ambient aerosol and cloudwater

    Energy Technology Data Exchange (ETDEWEB)

    Siefert, Ronald Lyn [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    1996-08-15

    Atmospheric iron (Fe) is thought to play an important role in cloudwater chemistry (e.g., S(IV) oxidation, oxidant production, etc.), and is also an important source of Fe to certain regions of the worlds oceans where Fe is believed to be a rate-limiting nutrient for primary productivity. This thesis focuses on understanding the chemistry, speciation and abundance of Fe in cloudwater and aerosol in the troposphere, through observations of Fe speciation in the cloudwater and aerosol samples collected over the continental United States and the Arabian Sea. Different chemical species of atmospheric Fe were measured in aerosol and cloudwater samples to help assess the role of Fe in cloudwater chemistry.

  6. Chemistry of the Fe2O3/BiFeO3 Interface in BiFeO3 Thin Film Heterostructures

    Directory of Open Access Journals (Sweden)

    Valanoor Nagarajan

    2010-12-01

    Full Text Available We investigate the interfacial chemistry of secondary Fe2O3 phases formed in a BiFeO3 (BFO layer in BFO/ La0.67Sr0.33MnO3 (LSMO/SrTiO3 (STO heterostructures. A combination of high-resolution spherical aberration corrected scanning TEM and spectroscopy results, reveals that specific chemical and crystallographic similarities between Fe2O3 and BFO, enable the BFO layer to form a facile host for Fe2O3.

  7. VERY LATE PHOTOMETRY OF SN 2011fe

    Energy Technology Data Exchange (ETDEWEB)

    Kerzendorf, W. E. [Department of Astronomy and Astrophysics, University of Toronto, 50 Saint George Street, Toronto, ON M5S 3H4 (Canada); Taubenberger, S.; Seitenzahl, I. R.; Ruiter, A. J., E-mail: wkerzendorf@gmail.com [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, D-85748 Garching (Germany)

    2014-12-01

    The Type Ia supernova SN 2011fe is one of the closest supernovae of the past decades. Due to its proximity and low dust extinction, this object provides a very rare opportunity to study the extremely late time evolution (>900 days) of thermonuclear supernovae. In this Letter, we present our photometric data of SN 2011fe taken at an unprecedented late epoch of ≈930 days with GMOS-N mounted on the Gemini North telescope (g = 23.43 ± 0.28, r = 24.14 ± 0.14, i = 23.91 ± 0.18, and z = 23.90 ± 0.17) to study the energy production and retention in the ejecta of SN 2011fe. Together with previous measurements by other groups, our result suggests that the optical supernova light curve can still be explained by the full thermalization of the decay positrons of {sup 56}Co. This is in spite of theoretical predicted effects (e.g., infrared catastrophe, positron escape, and dust) that advocate a substantial energy redistribution and/or loss via various processes that result in a more rapid dimming at these very late epochs.

  8. Spectromicroscopy of Fe distributions in clay microcrystals

    Energy Technology Data Exchange (ETDEWEB)

    Grundl, T. [Univ. of Wisconsin, Milwaukee, WI (United States); Cerasari, S.; Garcia, A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Clays are ubiquitous crystalline particles found in nature that are responsible for contributing to a wide range of chemical reactions in soils. The structure of these mineral particles changes when the particle is hydrated ({open_quotes}wet{close_quotes}), from that when it is dry. This makes a study of the microscopic distribution of chemical content of these nanocrystals difficult using standard techniques that require vacuum. In addition to large structural changes, it is likely that chemical changes accompany the drying process. As a result, spectroscopic measurements on dried clay particles may not accurately reflect the actual composition of the material as found in the environment. In this work, the authors extend the use of the ALS Spectromicroscopy Facility STXM to high spectral and spatial resolution studies of transition metal L-edges in environmental materials. The authors are studying mineral particles of montmorillonite, which is an Fe bearing clay which can be prepared with a wide distribution of Fe concentrations, and with Fe occupying different substitutional sites.

  9. Thermodynamic properties of Heusler Fe2VSi

    Science.gov (United States)

    Ito, Masakazu; Kai, Keita; Furuta, Tatsuya; Manaka, Hirotaka; Terada, Norio; Hiroi, Masahiko; Kondo, Akihiro; Kindo, Koichi

    2018-05-01

    We investigated temperature, T, dependence of magnetization, M(T), electrical resistivity, ρ(T), and specific heat, Cp(T), for the Heusler compound Fe2VSi. M(T) shows anomalies at TN1 ˜ 115 K and at TN2 ˜ 35 K. The anomaly at TN1 is caused by the magnetic transition with a crystal structural change. On the other hand, ρ(T) and Cp(T) show only anomaly at TN1, and no trace of anomaly at TN2 is observed. Because of the irreversibility of M(T), which is the characteristic of spin-glass freezing, appears below TN2, a spin-glass freezing may occur at TN2. From the analogy of the Heusler compound (Fe1-xVx ) 3Si with the cubic D03 crystal structure, (0 ≤ x ≤ 0.2), we suggested that the atomic disorder of V site by the Fe atoms gives rise to the magnetic frustration. This could be cause for the spin-glass freezing. By the Clausius-Clapeyron relation, pressure, P, derivative of TN1, (d/TN 1 d P ), is estimated to be ˜-10 K/Gpa.

  10. Fe-Oxides in Water Remediation Technologies

    Science.gov (United States)

    Vaclavikova, M.; Stefusova, K.; Gallios, G. P.

    Water is essential for life, a strategic resource for every country and population. Its availability and sanitary safety is highly connected with the health and economic status of a population. The burden of disease due to polluted water is a major public health problem throughout the world. Many pollutants in water streams have been identified as toxic and harmful to the environment and human health, and among them arsenic, mercury and cadmium are considered those with the highest priority. Iron is the fourth most abundant element in the Earth's crust, and reactions involving iron play a major role in the environmental cycling of a range of important contaminants. Our earlier research has shown that Fe oxides/oxyhydroxides are particularly effective adsorbents of a range of contaminants (toxic metals), due to their high (reactive) specific surface area. It has been proven that Fe is particularly effective in As removal as a chemical bond is created on Fe surface and As is stabilised and can be safely deposited. Removal of contaminants from waste streams through precipitation with (hydrous) ferric oxides is an established methodology in a number of industrial processes (high density sludge systems for arsenic control in effluents from the mining industry, and in the treatment of textile dye effluent).

  11. Magnetism of FePt Thin Films

    Science.gov (United States)

    Alqhtany, Norah H.

    Materials with large magnetic anisotropy have received significant attention from the scientific community due to its advantages in technological applications. Equiatomic FePt has been identified as such a material which could possibly be a potential candidate for ultra- high density magnetic recording and other applications like permanent magnets. FePt thin films exhibit ordered L10 texture with high magnetocrystalline anisotropy and high saturation magnetization which seem lucrative for technological applications. This thesis presents an investigation of structural and magnetic properties of granular and epitaxial FePt films with L10 phase prepared by DC sputtering on different substrates (SrTiO3 and glass). X-ray Diffraction (XRD), Atomic Force Microscopy/Magnetic Force Microscopy (AFM/MFM) and Vibrating Sample Magnetometer (VSM) were employed in characterization process. The measurements obtained from these equipment were significant in establishing the relationship between the microstructure and the magnetic properties of these films. The symmetry and magnitude of magnetic anisotropy has also been analyzed and discussed in detail.

  12. VERY LATE PHOTOMETRY OF SN 2011fe

    International Nuclear Information System (INIS)

    Kerzendorf, W. E.; Taubenberger, S.; Seitenzahl, I. R.; Ruiter, A. J.

    2014-01-01

    The Type Ia supernova SN 2011fe is one of the closest supernovae of the past decades. Due to its proximity and low dust extinction, this object provides a very rare opportunity to study the extremely late time evolution (>900 days) of thermonuclear supernovae. In this Letter, we present our photometric data of SN 2011fe taken at an unprecedented late epoch of ≈930 days with GMOS-N mounted on the Gemini North telescope (g = 23.43 ± 0.28, r = 24.14 ± 0.14, i = 23.91 ± 0.18, and z = 23.90 ± 0.17) to study the energy production and retention in the ejecta of SN 2011fe. Together with previous measurements by other groups, our result suggests that the optical supernova light curve can still be explained by the full thermalization of the decay positrons of 56 Co. This is in spite of theoretical predicted effects (e.g., infrared catastrophe, positron escape, and dust) that advocate a substantial energy redistribution and/or loss via various processes that result in a more rapid dimming at these very late epochs

  13. Mixed hyperfine interaction in amorphous Fe-Zr sputtered films in external magnetic field - a 57Fe Moessbauer study

    International Nuclear Information System (INIS)

    Fries, S.M.; Crummenauer, J.; Wagner, H.-G.; Gonser, U.; Chien, C.L.

    1986-01-01

    Conventional 57 Fe-Moessbauer spectroscopy provides only information about the magnitude of the splitting QS in the case of electric quadrupole hyperfine interaction, but not on the sign of the main component of the electric field gradient (EFG) or the asymmetry parameter which are sensitive to the local environment of the 57 Fe nuclei. This kind of information is obtained by measurements in external magnetic fields. In the case of amorphous Fe-Zr sputtered films mixed hyperfine interaction leads to a clear change in the behaviour of the Zr-rich and the Fe-rich alloys, indicating the existence of magnetic clusters in the Fe-rich samples. (Auth.)

  14. Pillar shape modulation in epitaxial BiFeO3–CoFe2O4 vertical nanocomposite films

    OpenAIRE

    Dong Hun Kim; Nicolas M. Aimon; C. A. Ross

    2014-01-01

    Self-assembled epitaxial CoFe2O4-BiFeO3 nanocomposite films, in which pillars of CoFe2O4 grow within a single crystal BiFeO3 matrix, show both ferrimagnetism and ferroelectricity. The pillars typically have a uniform cross-section, but here two methods are demonstrated to produce a width modulation during growth by pulsed laser deposition. This was achieved by growing a blocking layer of BiFeO3 to produce layers of separated pillars or pillars with constrictions, or by changing the temperatur...

  15. Light controlled magnetoresistance and magnetic field controlled photoresistance in CoFe film deposited on BiFeO3

    OpenAIRE

    Kundys, B.; Meny, C.; Gibbs, M. R. J.; Da Costa, V.; Viret, M.; Acosta, M.; Colson, D.; Doudin, B.

    2012-01-01

    We present a magnetoresistive-photoresistive device based on the interaction of a piezomagnetic CoFe thin film with a photostrictive BiFeO3 substrate that undergoes light-induced strain. The magnitude of the resistance and magnetoresistance in the CoFe film can be controlled by the wavelength of the incident light on the BiFeO3. Moreover, a light-induced decrease in anisotropic magnetoresistance is detected due to an additional magnetoelastic contribution to magnetic anisotropy of the CoFe fi...

  16. Influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers, Fe/Cr/Fe- and Fe/MgO/Fe multilayers; Untersuchung der Morphologie und magnetische Eigenschaften von ionenstrahl-gesputterten Eisen-Einzelschichten, Fe/Cr/Fe- und Fe/MgO/Fe-Schichtsystemen

    Energy Technology Data Exchange (ETDEWEB)

    Steeb, Alexandra

    2007-04-05

    In this PhD Thesis, the influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers on GaAs is examined. To analyze the structure of the produced iron films, low energy electron diffraction and scanning tunneling microscopy is employed. The utilized methods to investigate the magnetic properties are Kerr- and SQUID-magnetometry and ferromagnetic resonance. It is demonstrated that on untreated as well as on presputtered and heated GaAs substrates the sputtered iron films grow epitaxially. The least surface roughness of 1 A exhibit iron films grown on untreated GaAs, while iron films on heated GaAs have the highest roughness of 30 A. The largest crystal anisotropy constant is found for the presputtered GaAs/Fe-System. For this preparation method, two monolayers of iron are determined to be magnetically dead layers. At a film thickness of 100 A, 83% of the value for saturation magnetization of bulk iron are achieved. The small observed FMR-linewidths confirm the good bulk properties of the ion beam sputtered iron. Furthermore, an antiferromagnetic interlayer exchange coupling in sputtered Fe/Cr/Fe-films was achieved. For a thickness of 12 to 17 A of the chrome interlayer, a coupling strength up to 0.2 mJ/m{sup 2} is found. To account for the small coupling strength, a strong intermixing at the interface is assumed. Finally, epitaxial Fe/MgO/Fe/FeMn multilayers are deposited on GaAs. After the structuring, it is possible to detect tunneling processes in the tunneling contacts with current-voltage measurements. The tunnel magneto resistance values of 2% are small, which can be explained by the absence of sharp, well-defined interfaces between the Fe/FeMn and the Fe/MgO interfaces. These results demonstrate, that analog to MBE the ion beam sputtering method realizes good magnetic bulk properties. However, interface sensitive phenomena are weakened because of a strong intermixing at the interfaces. (orig.)

  17. Influence of roughness at interfaces on tunneling magnetoresistance in Fe/MgO/Fe

    Energy Technology Data Exchange (ETDEWEB)

    Edalati Boostan, Saeideh [I. Physikalisches Institut, Justus Liebig University Giessen, D-35392 (Germany); Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Moradi, Hosein [Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Heiliger, Christian [I. Physikalisches Institut, Justus Liebig University Giessen, D-35392 (Germany)

    2010-07-01

    We propose a theoretical model for magnetic tunnel junction devices with rough interfaces based on a single-band tight-binding approximation. The high tunneling magnetoresistance (TMR) for crystalline MgO barrier was observed at room temperature which is desirable for magnetic random access memory (MRAM) applications. In real junctions the Fe and MgO atoms are interdiffused at interfaces and the numbers of diffused Fe and MgO atoms are not the same. The interface disorder is modeled by considering replacement of MgO sites by Fe atoms with a probability of n>0.5. The non-equilibrium Green's function formalism is used to calculate transport in Fe/MgO/Fe junctions. We investigate the voltage dependencies of TMR and current densities for parallel and anti-parallel configurations for majority and minority spins. The results show that the roughness decreases the TMR. The current density for the parallel (antiparallel) orientations of magnetizations decreases (increases) by including roughness at the interface.

  18. Low Gilbert damping in Co2FeSi and Fe2CoSi films

    Science.gov (United States)

    Sterwerf, Christian; Paul, Soumalya; Khodadadi, Behrouz; Meinert, Markus; Schmalhorst, Jan-Michael; Buchmeier, Mathias; Mewes, Claudia K. A.; Mewes, Tim; Reiss, Günter

    2016-08-01

    Thin highly textured Fe1+xCo2-xSi (0 ≤ x ≤ 1) films were prepared on MgO (001) substrates by magnetron co-sputtering. Magneto-optic Kerr effect (MOKE) and ferromagnetic resonance (FMR) measurements were used to investigate the composition dependence of the magnetization, the magnetic anisotropy, the gyromagnetic ratio, and the relaxation of the films. Both MOKE and FMR measurements reveal a pronounced fourfold anisotropy for all films. In addition, we found a strong influence of the stoichiometry on the anisotropy as the cubic anisotropy strongly increases with increasing Fe concentration. The gyromagnetic ratio is only weakly dependent on the composition. We find low Gilbert damping parameters for all films with values down to 0.0012 ±0.00010.0007 for Fe1.75Co1.25Si. The effective damping parameter for Co2FeSi is found to be 0.0018 ±0.00040.0034 . We also find a pronounced anisotropic relaxation, which indicates significant contributions of two-magnon scattering processes that is strongest along the easy axes of the films. This makes thin Fe1+xCo2-xSi films ideal materials for the application in spin transfer-torque magnetic RAM (STT-MRAM) devices.

  19. Modeling thermodynamics of Fe-N phases; characterisation of e-Fe2N1-z

    DEFF Research Database (Denmark)

    Pekelharing, M.I.; Böttger, A.; Somers, Marcel A.J.

    1999-01-01

    In order to arrive at modeling the thermodynamics of Fe-N phases, including long-range (LRO) and short-range ordering (SRO) of the N atoms, it is important to understand the role of N interstitially dissolved in an Fe-host lattice. The crystal structure of -Fe2N1-z consists of an h.c.p. iron...... sublattice and a hexagonal nitrogen sublattice formed by octahedral interstices of the Fe sublattice [1]. Two ground-state structures have been proposed for the ordered arrangement of the N atoms on their own sublattice [1], which were shown to be thermodynamically favourable [2]: configuration A for Fe2N1...... investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two configurations of LRO of the N atoms [2,3] was fitted to the N-absorption isotherm at 723 K and resulted in the occupancies of the sites of the nitrogen sublattice. A miscibility gap between...

  20. Magnetostrictive properties of FeAl/polyester and FeAl/silicone composites

    Energy Technology Data Exchange (ETDEWEB)

    Riesgo, G. [Dpto. de Ciencias y Técnicas de la Navegación, Universidad de Oviedo, Campus universitario de Gijón, 33203 Gijón (Spain); Carrizo, J. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Elbaile, L., E-mail: elbaile@uniovi.es [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Crespo, R.D. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Sepúlveda, R. [Dpto. de Ingeniería Mecánica y de los Materiales, Universidad de Sevilla, Isla Cartuja, 41092 Sevilla (Spain); García, J.A. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain)

    2017-01-15

    Highlights: • Nanocrystalline powders of FeAl have been obtained from the Fe{sub 81}Al{sub 19} ribbon produced by melt spinning. • The method allows the obtainment of a FeAl solid solution from the starting process. • The microstructure and magnetic properties of the powders were investigated. • Composites with a magnetostriction of 45 ppm have been obtained. - Abstract: Ribbons of composition Fe{sub 81}Al{sub 19} obtained by the melt spinning method have been used to yield powder by mechanical milling. Using this method, a rapid nanocrystallization and a FeAl solid solution phase was obtained from the start of the process. The microstructural and magnetic properties as well as the XRD patterns of the powders were studied in function of the milling time. Grain refinement and an increase of the coercive field were the main transformations resulting from increasing the milling time. Two sets of magnetostrictive composites were produced from the 100 h-milled powder. In one of them polyester was used as matrix and in the other one silicone. In the case of the silicone composites cured in a magnetic field of 140 mT in the longitudinal direction a saturation magnetostriction as high as 45 ppm was obtained.