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Sample records for iron absorption conditioning

  1. Probing the structure of iron at extreme conditions by X-ray absorption near-edge structure calculations

    NASA Astrophysics Data System (ADS)

    Raji, A. T.; Scandolo, S.; Härting, M.; Britton, D. T.

    2013-03-01

    We present the K-edge X-ray absorption near edge spectra of hexagonal-closed packed iron at pressure and temperature conditions relevant to Earth's mantle conditions. The calculated spectra have been obtained using the first-principles scheme based on the continued-fraction approach and norm-conserving pseudopotentials. The atomic configurations used for the X-ray absorption near edge spectroscopy calculations were obtained from classical molecular dynamics simulations, using an optimized embedded-atom potential. We compare our calculated spectra to recently available experiment results (R. Boehler, H.G. Musshoff, R. Ditz, G. Aquilanti, and A. Trapananti, Rev. Sci. Instrum. 80 (2009), pp. 045103-045108) and identify the main features of the spectra that may indicate onset of melting in iron.

  2. The Regulation of Iron Absorption and Homeostasis

    PubMed Central

    Wallace, Daniel F

    2016-01-01

    Iron is an essential element in biology, required for numerous cellular processes. Either too much or too little iron can be detrimental, and organisms have developed mechanisms for balancing iron within safe limits. In mammals there are no controlled mechanisms for the excretion of excess iron, hence body iron homeostasis is regulated at the sites of absorption, utilisation and recycling. This review will discuss the discoveries that have been made in the past 20 years into advancing our understanding of iron homeostasis and its regulation. The study of iron-associated disorders, such as the iron overload condition hereditary haemochromatosis and various forms of anaemia have been instrumental in increasing our knowledge in this area, as have cellular and animal model studies. The liver has emerged as the major site of systemic iron regulation, being the location where the iron regulatory hormone hepcidin is produced. Hepcidin is a negative regulator of iron absorption and recycling, achieving this by binding to the only known cellular iron exporter ferroportin and causing its internalisation and degradation, thereby reducing iron efflux from target cells and reducing serum iron levels. Much of the research in the iron metabolism field has focussed on the regulation of hepcidin and its interaction with ferroportin. The advances in this area have greatly increased our knowledge of iron metabolism and its regulation and have led to the development of novel diagnostics and therapeutics for iron-associated disorders. PMID:28303071

  3. Determining the Effect of Environmental Conditions on Iron Corrosion by Atomic Absorption

    ERIC Educational Resources Information Center

    Malel, Esteban; Shalev, Deborah E.

    2013-01-01

    Iron corrosion is a complex process that occurs when iron is exposed to oxygen and humidity and is exacerbated by the presence of chloride ions. The deterioration of iron structures or other components can be costly to society and is usually evaluated by following the properties of the corroding material. Here, the iron ions released into solution…

  4. Iron Absorption in Drosophila melanogaster

    PubMed Central

    Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

    2013-01-01

    The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration. PMID:23686013

  5. Iron absorption in Drosophila melanogaster.

    PubMed

    Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

    2013-05-17

    The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration.

  6. The effect of tea on iron absorption.

    PubMed Central

    Disler, P B; Lynch, S R; Charlton, R W; Torrance, J D; Bothwell, T H; Walker, R B; Mayet, F

    1975-01-01

    The effect of tea on iron absorption was studied in human volunteers. Absorption from solutions of FeCl3 and FeSO4, bread, a meal of rice with potato and onion soup, and uncooked haemoglobin was inhibited whether ascorbic acid was present or not. No inhibition was noted if the haemoglobin was cooked. The effect on the absorption of non-haem iron was ascribed to the formation of insoluble iron tannate complexes. Drinking tannin-containing beverages such as tea with meals may contribute to the pathogenesis of iron deficiency if the diet consists largely of vegetable foodstuffs. PMID:1168162

  7. [Effect of altitude on iron absorption].

    PubMed

    Pizarro, F; Zavaleta, N; Hertrampf, E; Berlanga, R; Camborda, L; Olivares, M

    1998-03-01

    Iron bioavailability was evaluated in people living in high altitudes. Absorption was estimated from a reference dose of ferrous ascorbate and from a standard diet of wheat flour, using extrinsic tag radioisotope technique of 55Fe and 59Fe. Twenty four volunteers, healthy women, with ages ranging from 28 to 45 years, participated. Of those, eleven lived at 3450 meters above sea level (m.a.s.l.) in Huancayo city-Peru (study group), and 13 lived in Santiago de Chile at 630 m.a.s.l. (control group). Iron absorption from reference dose of ferrous ascorbate was 32.0% and 31.1% in the study and control groups respectively. The geometric mean of iron absorption from the standard diet, corrected to 40% of absorption of reference dose, was 9.0% and 6.9% in the study and control groups respectively (NS). The results suggest that altitude does not produce a high iron absorption in highlander residents.

  8. Iron absorption from intrinsically-labeled lentils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low iron (Fe) absorption from important staple foods may contribute to Fe deficiency in developing countries. To date, there are few studies examining the Fe bioavailability of pulse crops as commonly prepared and consumed by humans. The objectives of this study were to characterize the Fe absorpt...

  9. Measurement of iron absorption from meals contaminated with iron

    SciTech Connect

    Hallberg, L.; Bjoern-Rasmussen, E.

    1981-12-01

    A method is described to measure in vitro the extent of isotopic exchange between the native nonheme food iron and added inorganic reduction to radioiron tracer. The food is digested with pepsin and trypsin in the presence of radioiron. The exchangeability of food iron is calculated from the specific activity in the food and in an extract of bathophenantroline in isoamyl alcohol obtained after digesting this food. The precision and accuracy of the method is illustrated by two kinds of studies, those in which different amounts of contamination iron are added to a meal and those evaluating contamination iron in natural meals. The present method will make it possible to measure validly iron absorption from meals contaminated with unknown amounts of iron of unknown exchangeability with the extrinsic radioiron tracer.

  10. Regulation of Iron Absorption in Hemoglobinopathies

    PubMed Central

    Rechavi, Gideon; Rivella, Stefano

    2013-01-01

    Beta-thalassemia and sickle cell anemia (SCD) represent the most common hemoglobinopathies caused, respectively, by deficient production or alteration of the beta chain of hemoglobin (Hb). Patients affected by the most severe form of thalassemia suffer from profound anemia that requires chronic blood transfusions and chelation therapies to prevent iron overload. However, patients affected by beta-thalassemia intermedia, a milder form of the disease that does not require chronic blood transfusions, eventually also show elevated body iron content due to increased gastrointestinal iron absorption. Even SCD patients might require blood transfusions and iron chelation to prevent deleterious and painful vaso-occlusive crises and complications due to iron overload. Although definitive cures are presently available, such as bone marrow transplantation (BMT), or are in development, such as correction of the disease through hematopoietic stem cell beta-globin gene transfer, they are potentially hazardous procedures or too experimental to provide consistently safe and predictive clinical outcomes. Therefore, studies that aim to better understand the pathophysiology of the hemoglobinopathies might provide further insight and new drugs to dramatically improve the understanding and current treatment of these diseases. This review will describe how recent discoveries on iron metabolism and erythropoiesis could lead to new therapeutic strategies and better clinical care of these diseases, thereby yielding a much better quality of life for the patients. PMID:18991651

  11. Non-heme iron as ferrous sulfate does not interact with heme iron absorption in humans.

    PubMed

    Gaitán, Diego; Olivares, Manuel; Lönnerdal, Bo; Brito, Alex; Pizarro, Fernando

    2012-12-01

    The absorption of heme iron has been described as distinctly different from that of non-heme iron. Moreover, whether heme and non-heme iron compete for absorption has not been well established. Our objective was to investigate the potential competition between heme and non-heme iron as ferrous sulfate for absorption, when both iron forms are ingested on an empty stomach. Twenty-six healthy nonpregnant women were selected to participate in two iron absorption studies using iron radioactive tracers. We obtained the dose-response curve for absorption of 0.5, 10, 20, and 50 mg heme iron doses, as concentrated red blood cells. Then, we evaluated the absorption of the same doses, but additionally we added non-heme iron, as ferrous sulfate, at constant heme/non-heme iron molar ratio (1:1). Finally, we compare the two curves by a two-way ANOVA. Iron sources were administered on an empty stomach. One factor analysis showed that heme iron absorption was diminished just by increasing total heme iron (P < 0.0001). The addition of non-heme iron as ferrous sulfate did not have any effect on heme iron absorption (P = NS). We reported evidence that heme and non-heme iron as ferrous sulfate does not compete for absorption. The mechanism behind the absorption of these iron sources is not clear.

  12. Absorption and loss of iron in toddlers are highly correlated.

    PubMed

    Fomon, Samuel J; Nelson, Steven E; Serfass, Robert E; Ziegler, Ekhard E

    2005-04-01

    For estimating the requirements for dietary iron, it is important to know the amount of iron that is lost from the body. Inevitable losses of iron have been determined in adult humans but not in infants or children. We administered (58)Fe, the least abundant stable isotope of iron, to free-living infants at 168 d of age (5.6 mo) and followed them to age 26 mo. There was no dietary restriction after isotope administration. Blood was obtained at regular intervals for determination of isotopic enrichment and indices of iron status. We estimated the quantity of circulating iron, noncirculating active iron, and storage iron at each age. The administered isotope equilibrated with total body iron by 13 mo of age. From 13 to 26 mo of age, we estimated inevitable loss and absorption of iron from the change in tracer abundance in circulating iron. The rate of decrease of tracer abundance was proportional to addition of tracee, i.e., absorption of iron. Conversely, the rate of decrease in quantity of tracer was proportional to removal of tracee, i.e., loss of iron. From 13 to 26 mo of age, iron absorption was (mean +/- SD) 0.49 +/- 0.13 mg/d and inevitable iron loss was 0.25 +/- 0.12 mg/d. Intersubject variability of iron loss and iron absorption was high, and iron loss and absorption were highly correlated (r = 0.789, P < 0.001). Iron stores were low throughout the study and decreased significantly from 13 to 26 mo of age, suggesting that iron absorption from the diet was inadequate to maintain or increase iron nutritional status. The data suggest that, in this cohort, which may be representative, the intake of bioavailable iron from 13 to 26 mo of age was insufficient to maintain iron nutritional status.

  13. Iron absorption by small intestine of chickens.

    PubMed

    Sáiz, M P; Martí, M T; Mitjavila, M T; Planas, J

    1993-01-01

    Iron (Fe) absorption by three segments (duodenum, jejunum, and ileum) of the small intestine of chickens was studied by a perfusion technique in vivo in closed circuit using 59Fe Cl3 and was related to the histological characteristics of each segment. The serosal transfers of Fe for the duodenum and jejunum were the same (14%/cm), but significantly different (p < 0.05) from those of the ileum (9%/cm), which may be explained by the morphological and histological properties of the gut of chickens. However, the presence of Fe in blood and in liver was significantly lower after perfusion of the jejunum and ileum than after perfusion of the duodenum. It is concluded that chickens show an early adaptation of small intestine to Fe absorption in response to the considerable loss of Fe suffered during the laying process.

  14. Iron regulatory proteins control a mucosal block to intestinal iron absorption.

    PubMed

    Galy, Bruno; Ferring-Appel, Dunja; Becker, Christiane; Gretz, Norbert; Gröne, Hermann-Josef; Schümann, Klaus; Hentze, Matthias W

    2013-03-28

    Mammalian iron metabolism is regulated systemically by the hormone hepcidin and cellularly by iron regulatory proteins (IRPs) that orchestrate a posttranscriptional regulatory network. Through ligand-inducible genetic ablation of both IRPs in the gut epithelium of adult mice, we demonstrate that IRP deficiency impairs iron absorption and promotes mucosal iron retention via a ferritin-mediated "mucosal block." We show that IRP deficiency does not interfere with intestinal sensing of body iron loading and erythropoietic iron need, but rather alters the basal expression of the iron-absorption machinery. IRPs thus secure sufficient iron transport across absorptive enterocytes by restricting the ferritin "mucosal block" and define a basal set point for iron absorption upon which IRP-independent systemic regulatory inputs are overlaid.

  15. Meat protein fractions enhance nonheme iron absorption in humans.

    PubMed

    Hurrell, Richard F; Reddy, Manju B; Juillerat, Marcel; Cook, James D

    2006-11-01

    The nature of the enhancing effect of muscle tissue on nonheme iron absorption in humans is unclear but thought to be related to muscle proteins. We conducted radioiron absorption studies to compare iron absorption from proteins isolated from beef and chicken muscle with that from freeze-dried beef and chicken muscle and from egg albumin. All meals contained an equivalent amount of protein as part of a semisynthetic liquid formula. Freeze-dried beef and chicken muscle increased iron absorption 180% (P < 0.001) and 100% (P < 0.001), respectively, relative to egg albumin. When added to the meal at an equivalent protein level (15 g), the isolated beef protein and the isolated heme-free beef protein with 94 and 98% protein content, respectively, increased iron absorption to the same extent as the native beef muscle. Similarly, when added to the meal at an equivalent protein level (30 g), isolated chicken muscle protein (94% protein) increased iron absorption similarly to native chicken muscle. Iron absorption from the meal containing the isolated heme-free chicken protein, however, was 120% (P < 0.01) greater than from the meal containing freeze-dried chicken muscle, indicating that a nonprotein component of muscle tissue with iron-binding potential may have been removed or concentrated by the protein extraction and separation procedures. Our results support the hypothesis that the enhancing effect of muscle tissue on iron absorption is mainly protein related but indicate that other factors may also play a role.

  16. Contribution of ferric iron to the absorption by chromophoric dissolved matter

    NASA Astrophysics Data System (ADS)

    Xiao, Y. H.; Sara-aho, T.; Vähätalo, A. V.

    2012-04-01

    Chromophoric dissolved organic matter (CDOM) is a major absorber of ultraviolet and visible radiation in surface waters. CDOM consists primarily of humic substances (HS), which can adsorb inorganic cations such as ferric iron. Often more than 99% of dissolved iron is complexed by CDOM in natural waters. Our study assessed the contribution of ferric iron to the absorption of CDOM by mixing dissolved humic substance (HS) standards with iron(III) in acidic conditions and later adjusting the pH to 8. The maximum iron-binding capacities for Suwannee River humic acid, Suwannee River fulvic acid and Pony Lake fulvic acid were 13.0, 13.5 and 7.64 μmol iron [mg C]-1, respectively, suggesting higher iron-binding capacity for terrestrial- than microbial-derived CDOM. Iron(III) associated with HS increased the absorption coefficient by CDOM by 1.73-5.33 times (λ=254-550 nm). Inorganic iron, thus, contributed up to 4/5 of the absorption by CDOM (λ=550 nm). In other words, only less than 1/5 of the absorption by CDOM-iron mixture was generated by organic chromophores. The associated iron decreased spectral slope coefficients of HS. This finding indicates that changes of the spectral slope by CDOM can be solely caused by inorganic interference (e.g. iron). The increase of absorption by associated iron(III) was always spectrally similar among different HS standards. We calculated a specific absorption spectrum for iron associated with dissolved HS standards. This spectrum allows estimates for the absorption by iron associated with HS in circum neutral natural waters. For Löytynlähde spring water, iron contributed over 1/10 (ca. 0.108, λ=400 nm) to the total absorption. The contribution of iron to total absorption increased with wavelength. In typical CDOM absorption measurement, water samples are filtered for the removal of particulate constituents but no attempts are implemented for separating the organic chromophores from inorganic chromophores. Our findings show that

  17. Iron Deficiency and Obesity: The Contribution of Inflammation and Diminished Iron Absorption

    DTIC Science & Technology

    2008-01-01

    and iron absorption may be mediated by hepcidin , although further studies will be required to confinn this potential physiological explanation for...the increased prevalence of iron deficiency in the obese. 15. SUBJECT TERMS Hepcidin , inflammation, iron, obesity LIMITATION OF 18. NUMBER16. SECURITY...inflammation and iron absorption may be mediated by hepcidin , although further studies will be required to confirm this potential physiological

  18. Iron absorption from concentrated hemoglobin hydrolysate by rat.

    PubMed

    Vaghefi, Nikta; Nedjaoum, Fuzia; Guillochon, Didier; Bureau, François; Arhan, Pierre; Bouglé, Dominique

    2005-06-01

    Although heme iron is highly bioavailable, the low iron content of hemoglobin prevents its use for dietary fortification; on the other hand, purified heme has low solubility and absorption rate. The present study was designed to assess the interactions between concentrated heme iron and peptides released during globin hydrolysis and cysteine and their relation with iron absorption. Hemoglobin was hydrolyzed by pepsin or subtilisin, and then, heme iron was concentrated by ultrafiltration. Iron absorption was studied in a Ussing chamber; gluconate was used as control. Iron uptake from nonconcentrated pepsin hydrolysate and gluconate was lower than from other groups. Cysteine significantly enhanced iron uptake except from the concentrated subtilisin hydrolysate. There was no significant difference between cysteine-supplemented groups. According to the different hydrolysis pathways of enzymes, it is assumed that the presence of hydrophobic peptides and the strength of heme-peptide interactions are both determining factors of heme iron absorption. These interactions occur mainly before iron uptake, as emphasized by the effect of cysteine.

  19. Adaptation of iron requirement to hypoxic conditions at high altitude.

    PubMed

    Gassmann, Max; Muckenthaler, Martina U

    2015-12-15

    Adequate acclimatization time to enable adjustment to hypoxic conditions is one of the most important aspects for mountaineers ascending to high altitude. Accordingly, most reviews emphasize mechanisms that cope with reduced oxygen supply. However, during sojourns to high altitude adjustment to elevated iron demand is equally critical. Thus in this review we focus on the interaction between oxygen and iron homeostasis. We review the role of iron 1) in the oxygen sensing process and erythropoietin (Epo) synthesis, 2) in gene expression control mediated by the hypoxia-inducible factor-2 (HIF-2), and 3) as an oxygen carrier in hemoglobin, myoglobin, and cytochromes. The blood hormone Epo that is abundantly expressed by the kidney under hypoxic conditions stimulates erythropoiesis in the bone marrow, a process requiring high iron levels. To ensure that sufficient iron is provided, Epo-controlled erythroferrone that is expressed in erythroid precursor cells acts in the liver to reduce expression of the iron hormone hepcidin. Consequently, suppression of hepcidin allows for elevated iron release from storage organs and enhanced absorption of dietary iron by enterocytes. As recently observed in sojourners at high altitude, however, iron uptake may be hampered by reduced appetite and gastrointestinal bleeding. Reduced iron availability, as observed in a hypoxic mountaineer, enhances hypoxia-induced pulmonary hypertension and may contribute to other hypoxia-related diseases. Overall, adequate systemic iron availability is an important prerequisite to adjust to high-altitude hypoxia and may have additional implications for disease-related hypoxic conditions.

  20. Iron deficiency, but not anemia, upregulates iron absorption in breast-fed peruvian infants.

    PubMed

    Hicks, Penni D; Zavaleta, Nelly; Chen, Zhensheng; Abrams, Steven A; Lönnerdal, Bo

    2006-09-01

    Iron absorption in adults is regulated by homeostatic mechanisms that decrease absorption when iron status is high. There are few data, however, regarding the existence of a similar homeostatic regulation in infants. We studied 2 groups of human milk-fed infants using (57)Fe (given as ferrous sulfate without any milk) and (58)Fe (given at the time of a breast-milk feeding) stable isotopes to determine whether healthy infants at risk for iron deficiency would regulate their iron absorption based on their iron status. We studied 20 Peruvian infants at 5-6 mo of age and 18 infants at 9-10 mo of age. We found no effect of infant hemoglobin concentration on iron absorption with 5-6 mo-old infants absorbing 19.2 +/- 2.1% and 9- to 10-mo-old infants absorbing 25.8 +/- 2.6% of the (57)Fe dose. For (58)Fe, 5- to 6-mo-old infants absorbed 42.6 +/- 5.0% and 9 to 10-mo-old infants absorbed 51.9 +/- 10.3%. Following log transformation, iron absorption from (57)Fe (r = -0.61, P = < 0.001) and (58)Fe (r = -0.61, P = < 0.001) were inversely correlated to serum ferritin (S-Ft). For both the (57)Fe and (58)Fe doses, infants with S-Ft <12 mg/L (n = 11) had significantly higher iron absorption than those with S-Ft >12 mg/L. We concluded that iron absorption in infants is related to iron status as assessed by serum ferritin but not hemoglobin concentration. Infants with low iron status upregulate iron absorption from breast milk at both 5-6 and 9-10 mo of age.

  1. Oral exposure to polystyrene nanoparticles affects iron absorption

    NASA Astrophysics Data System (ADS)

    Mahler, Gretchen J.; Esch, Mandy B.; Tako, Elad; Southard, Teresa L.; Archer, Shivaun D.; Glahn, Raymond P.; Shuler, Michael L.

    2012-04-01

    The use of engineered nanoparticles in food and pharmaceuticals is expected to increase, but the impact of chronic oral exposure to nanoparticles on human health remains unknown. Here, we show that chronic and acute oral exposure to polystyrene nanoparticles can influence iron uptake and iron transport in an in vitro model of the intestinal epithelium and an in vivo chicken intestinal loop model. Intestinal cells that are exposed to high doses of nanoparticles showed increased iron transport due to nanoparticle disruption of the cell membrane. Chickens acutely exposed to carboxylated particles (50 nm in diameter) had a lower iron absorption than unexposed or chronically exposed birds. Chronic exposure caused remodelling of the intestinal villi, which increased the surface area available for iron absorption. The agreement between the in vitro and in vivo results suggests that our in vitro intestinal epithelium model is potentially useful for toxicology studies.

  2. Infant iron status affects iron absorption in Peruvian breastfed infants at 2 and 5 mo of age

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of prenatal iron supplementation on maternal postpartum iron status and early infant iron homeostasis remain largely unknown. We examined iron absorption and growth in exclusively breastfed infants in relation to fetal iron exposure and iron status during early infancy. Longitudinal, paired ...

  3. Effect of tea on iron absorption from the typical Tunisian meal 'couscous' fed to healthy rats.

    PubMed

    Hamdaoui, M; Hedhili, A; Doghri, T; Tritar, B

    1994-01-01

    Black and green tea decoctions are popular beverages in Tunisia, especially after eating. Our study was performed to examine the effect of graded amounts of black and green tea decoction prepared under realistic Tunisian conditions on nonheme iron absorption from a typical Tunisian meal, 'couscous', by extrinsic radioiron labeling in rats. Concentrations of 300, 200 and 100 micrograms/ml of black tea decreased dramatically nonheme iron bioavailability from couscous, but 50 micrograms/ml did not influence iron absorption. The inhibition of nonheme iron from couscous varied from 36 to 61% with black tea and 30.5% with green tea. Taken together, our findings show that the tea decoction in Tunisia has a great inhibitory power and may constitute an important factor for the development of iron deficiency anemia throughout Tunisia.

  4. Absorption of iron from ferritin is independent of heme iron and ferrous salts in women and rat intestinal segments.

    PubMed

    Theil, Elizabeth C; Chen, Huijun; Miranda, Constanza; Janser, Heinz; Elsenhans, Bernd; Núñez, Marco T; Pizarro, Fernando; Schümann, Klaus

    2012-03-01

    Ferritin iron from food is readily bioavailable to humans and has the potential for treating iron deficiency. Whether ferritin iron absorption is mechanistically different from iron absorption from small iron complexes/salts remains controversial. Here, we studied iron absorption (RBC (59)Fe) from radiolabeled ferritin iron (0.5 mg) in healthy women with or without non-ferritin iron competitors, ferrous sulfate, or hemoglobin. A 9-fold excess of non-ferritin iron competitor had no significant effect on ferritin iron absorption. Larger amounts of iron (50 mg and a 99-fold excess of either competitor) inhibited iron absorption. To measure transport rates of iron that was absorbed inside ferritin, rat intestinal segments ex vivo were perfused with radiolabeled ferritin and compared to perfusion with ferric nitrilotriacetic (Fe-NTA), a well-studied form of chelated iron. Intestinal transport of iron absorbed inside exogenous ferritin was 14.8% of the rate measured for iron absorbed from chelated iron. In the steady state, endogenous enterocyte ferritin contained >90% of the iron absorbed from Fe-NTA or ferritin. We found that ferritin is a slow release source of iron, readily available to humans or animals, based on RBC iron incorporation. Ferritin iron is absorbed by a different mechanism than iron salts/chelates or heme iron. Recognition of a second, nonheme iron absorption process, ferritin endocytosis, emphasizes the need for more mechanistic studies on ferritin iron absorption and highlights the potential of ferritin present in foods such as legumes to contribute to solutions for global iron deficiency.

  5. Iron Absorption from Two Milk Formulas Fortified with Iron Sulfate Stabilized with Maltodextrin and Citric Acid

    PubMed Central

    Pizarro, Fernando; Olivares, Manuel; Maciero, Eugenia; Krasnoff, Gustavo; Cócaro, Nicolas; Gaitan, Diego

    2015-01-01

    Background: Fortification of milk formulas with iron is a strategy widely used, but the absorption of non-heme iron is low. The purpose of this study was to measure the bioavailability of two iron fortified milk formulas designed to cover toddlers’ nutritional needs. These milks were fortified with iron sulfate stabilized with maltodextrin and citric acid. Methods: 15 women (33–47 years old) participated in study. They received on different days, after an overnight fast, 200 mL of Formula A; 200 mL of Formula B; 30 mL of a solution of iron and ascorbic acid as reference dose and 200 mL of full fat cow’s milk fortified with iron as ferrous sulfate. Milk formulas and reference dose were labeled with radioisotopes 59Fe or 55Fe, and the absorption of iron measured by erythrocyte incorporation of radioactive Fe. Results: The geometric mean iron absorption corrected to 40% of the reference dose was 20.6% for Formula A and 20.7% for Formula B, versus 7.5% of iron fortified cow’s milk (p < 0.001). The post hoc Sheffé indeed differences between the milk formulas and the cow’s milk (p < 0.001). Conclusion: Formulas A and B contain highly bioavailable iron, which contributes to covering toddlers’ requirements of this micronutrient. PMID:26529007

  6. Absorption of iron from ferric hydroxypyranone complexes.

    PubMed

    Maxton, D G; Thompson, R P; Hider, R C

    1994-02-01

    The absorption of 59Fe from preparations of FeSO4 and the ferric hydroxypyranone complexes maltol and ethyl maltol was studied by whole-body counting in normal subjects and patients with Fe deficiency. Fe in the Fe3+ complexes was in general absorbed almost as well as Fe2+. It is concluded that the absorption of Fe3+ from hydroxypyranone complexes is much greater than that from simple Fe3+ salts; this may prove an efficient and less toxic form of Fe for the treatment of deficiency.

  7. The multicopper ferroxidase hephaestin enhances intestinal iron absorption in mice.

    PubMed

    Fuqua, Brie K; Lu, Yan; Darshan, Deepak; Frazer, David M; Wilkins, Sarah J; Wolkow, Natalie; Bell, Austin G; Hsu, JoAnn; Yu, Catherine C; Chen, Huijun; Dunaief, Joshua L; Anderson, Gregory J; Vulpe, Chris D

    2014-01-01

    Hephaestin is a vertebrate multicopper ferroxidase important for the transfer of dietary iron from intestinal cells to the blood. Hephaestin is mutated in the sex-linked anemia mouse, resulting in iron deficiency. However, sex-linked anemia mice still retain some hephaestin ferroxidase activity. They survive, breed, and their anemia improves with age. To gain a better understanding of the role of hephaestin in iron homeostasis, we used the Cre-lox system to generate knockout mouse models with whole body or intestine-specific (Villin promoter) ablation of hephaestin. Both types of mice were viable, indicating that hephaestin is not essential and that other mechanisms, multicopper ferroxidase-dependent or not, must compensate for hephaestin deficiency. The knockout strains, however, both developed a microcytic, hypochromic anemia, suggesting severe iron deficiency and confirming that hephaestin plays an important role in body iron acquisition. Consistent with this, the knockout mice accumulated iron in duodenal enterocytes and had reduced intestinal iron absorption. In addition, the similarities of the phenotypes of the whole body and intestine-specific hephaestin knockout mice clarify the important role of hephaestin specifically in intestinal enterocytes in maintaining whole body iron homeostasis. These mouse models will serve as valuable tools to study the role of hephaestin and associated proteins in iron transport in the small intestine and other tissues.

  8. The Multicopper Ferroxidase Hephaestin Enhances Intestinal Iron Absorption in Mice

    PubMed Central

    Fuqua, Brie K.; Lu, Yan; Darshan, Deepak; Frazer, David M.; Wilkins, Sarah J.; Wolkow, Natalie; Bell, Austin G.; Hsu, JoAnn; Yu, Catherine C.; Chen, Huijun; Dunaief, Joshua L.; Anderson, Gregory J.; Vulpe, Chris D.

    2014-01-01

    Hephaestin is a vertebrate multicopper ferroxidase important for the transfer of dietary iron from intestinal cells to the blood. Hephaestin is mutated in the sex-linked anemia mouse, resulting in iron deficiency. However, sex-linked anemia mice still retain some hephaestin ferroxidase activity. They survive, breed, and their anemia improves with age. To gain a better understanding of the role of hephaestin in iron homeostasis, we used the Cre-lox system to generate knockout mouse models with whole body or intestine-specific (Villin promoter) ablation of hephaestin. Both types of mice were viable, indicating that hephaestin is not essential and that other mechanisms, multicopper ferroxidase-dependent or not, must compensate for hephaestin deficiency. The knockout strains, however, both developed a microcytic, hypochromic anemia, suggesting severe iron deficiency and confirming that hephaestin plays an important role in body iron acquisition. Consistent with this, the knockout mice accumulated iron in duodenal enterocytes and had reduced intestinal iron absorption. In addition, the similarities of the phenotypes of the whole body and intestine-specific hephaestin knockout mice clarify the important role of hephaestin specifically in intestinal enterocytes in maintaining whole body iron homeostasis. These mouse models will serve as valuable tools to study the role of hephaestin and associated proteins in iron transport in the small intestine and other tissues. PMID:24896847

  9. Room-temperature study of iron gall ink impregnated paper degradation under various oxygen and humidity conditions: time-dependent monitoring by viscosity and X-ray absorption near-edge spectrometry measurements.

    PubMed

    Rouchon, Véronique; Duranton, Maroussia; Burgaud, Cédric; Pellizzi, Eleonora; Lavédrine, Bertrand; Janssens, Koen; de Nolf, Wout; Nuyts, Gert; Vanmeert, Frederik; Hellemans, Kevin

    2011-04-01

    Many western manuscripts were written using iron gall inks. These inks can damage the paper via two major mechanisms: (a) acid hydrolysis, enhanced by humidity, and (b) oxidative depolymerization provoked by the presence of oxygen and free iron(II) ions. The degradation of unsized Whatman paper impregnated with different combinations of iron sulfate, gallic acid, and gum arabic was studied at room temperature in order to assess the relative importance of each mechanism. The samples were stored in various environments including a dry and/or an oxygen-free atmosphere. The cellulose depolymerization was monitored by viscometry and related to changes in the oxidation state of iron, determined by X-ray absorption near-edge spectrometry. The results indicate that residual amounts of oxygen (less than 0.1%) promote cellulose depolymerization, whereas the level of relative humidity has no impact. The cellulose depolymerization also appears closely correlated to oxidative mechanisms. Regarding the oxidation of iron, it only occurs in the simultaneous presence of oxygen and moisture, suggesting the occurrence of rustlike oxidative mechanisms. Finally, the presence of gallic acid has a strong influence, which is only partially explained by its capacity to reduce iron(III) to iron(II).

  10. Absorption of unlabeled reduced iron of small particle size from a commercial source. A method to predict absorption of unlabeled iron compounds in humans.

    PubMed

    González, H; Mendoza, C; Viteri, F E

    2001-09-01

    The absorption of a commercial brand of small-particle reduced iron was evaluated in 10 normal subjects. For each subject, the hemoglobin incorporation method was used to measure the true absorption of 60 mg of iron from either ferrous sulfate or ferric ammonium citrate. The iron tolerance test (ITT) was also studied for these two compounds and for reduced iron. This procedure consisted of measuring the area under the curve of plasma iron elevations at specified times for 6 hours, or the peak plasma iron, corrected by the plasma iron disappearance rate obtained from measuring plasma iron at specified times for 4 hours after the slow intravenous injection of 0.4 mg of iron as ferric citrate. Only the ITT was used to measure the absorption of 60 mg of reduced iron. Reference dose iron ascorbate absorption was measured in each subject. The absorption of ferric ammonium citrate and reduced iron was expressed as percent of dose and also as absorption percent of that of ferrous sulfate. Mean % geometric "true absorptions" were 39.0 for reference dose, 10.4 for FeSO4 and 2.4 for ferric ammonium citrate. The later was 23% that of FeSO4. By ITT the mean geometric % absorptions were 7.9, 3.7 and 3.2 for FeSO4, ferric ammonium citrate and reduced iron respectively, or 47 and 41% of that of FeSO4. We propose that the true absorption of the commercial brand of reduced iron tested was 20% that of FeSO4 based on the relation between the ITT results of reduced iron and the ITT and true absorption values of ferric ammonium citrate in relation to FeSO4. The use of this method for measuring absorption of unlabeled iron compounds is discussed.

  11. Influence of prenatal iron and zinc supplements on supplemental iron absorption, red blood cell iron incorporation, and iron status in pregnant Peruvian women.

    PubMed

    O'Brien, K O; Zavaleta, N; Caulfield, L E; Yang, D X; Abrams, S A

    1999-03-01

    The influence of iron status on iron absorption during pregnancy was examined among pregnant Peruvian women. This was done by measuring supplemental iron absorption, red blood cell iron incorporation and iron status. The subjects were 45 pregnant Peruvian women (33 +or- 1 week gestation) who were divided into 2 groups. The first group of 28 pregnant women received daily prenatal supplements containing 60 mg of iron and 250 mcg of folate with or without 15 mg of zinc, from week 10 to 24 of gestation until delivery. The second group of 17 women served as the control group. The control group was not given prenatal supplementation. The iron status indicators and isotopes were measured in maternal blood collected 2 weeks postdosing with oral iron-57 and intravenous iron-58 stable isotopes. The results showed that supplementation significantly influenced the maternal serum ferritin and folate concentrations (P 0.05). The serum iron of the iron group was significantly higher than that of the iron + zinc group (P 0.03) or control group (P 0.001). However, the serum zinc concentrations were lower in the supplemented group than in the control group. Even though the percentage of iron absorption was inversely related to maternal serum ferritin concentration, the effect was limited and the percentage of iron absorption did not differ significantly between the two groups. Considering that the absorption of nonheme iron was not substantially greater in pregnant women with depleted iron reserves, it was concluded that prenatal iron supplementation is essential for meeting iron requirements, especially during pregnancy.

  12. Effects of resistance exercise on iron absorption and balance in iron-deficient rats.

    PubMed

    Fujii, Takako; Matsuo, Tatsuhiro; Okamura, Koji

    2014-10-01

    We have previously reported that resistance exercise improved the iron status in iron-deficient rats. The current study investigated the mechanisms underlying this exercise-related effect. Male 4-week-old rats were divided into a group sacrificed at the start (week 0) (n = 7), a group maintained sedentary for 6 weeks (S) or a group that performed exercise for 6 weeks (E), and all rats in the latter groups were fed an iron-deficient diet (12 mg iron/kg) for 6 weeks. The rats in the E group performed climbing exercise (5 min × 6 sets/day, 3 days/week). Compared to the week 0 rats, the rats in the S and E groups showed lower tissue iron content, and the hematocrit, hemoglobin, plasma iron, and transferrin saturation values were all low. However, the tissue iron content and blood iron status parameters, and the whole body iron content measured using the whole body homogenates of the rats, did not differ between the S group and the E group. The messenger RNA (mRNA) expression levels of hepcidin, duodenal cytochrome b, divalent metal transporter 1, and ferroportin 1 did not differ between the S group and the E group. The apparent absorption of iron was significantly lower in the E group than in the S group. Therefore, it was concluded that resistance exercise decreases iron absorption, whereas the whole body iron content is not affected, and an increase in iron recycling in the body seems to be responsible for this effect.

  13. Duodenal Absorption and Tissue Utilization of Dietary Heme and Nonheme Iron Differ in Rats123

    PubMed Central

    Cao, Chang; Thomas, Carrie E.; Insogna, Karl L.; O'Brien, Kimberly O.

    2014-01-01

    Background: Dietary heme contributes to iron intake, yet regulation of heme absorption and tissue utilization of absorbed heme remains undefined. Objectives: In a rat model of iron overload, we used stable iron isotopes to examine heme- and nonheme-iron absorption in relation to liver hepcidin and to compare relative utilization of absorbed heme and nonheme iron by erythroid (RBC) and iron storage tissues (liver and spleen). Methods: Twelve male Sprague-Dawley rats were randomly assigned to groups for injections of either saline or iron dextran (16 or 48 mg Fe over 2 wk). After iron loading, rats were administered oral stable iron in the forms of 57Fe-ferrous sulfate and 58Fe-labeled hemoglobin. Expression of liver hepcidin and duodenal iron transporters and tissue stable iron enrichment was determined 10 d postdosing. Results: High iron loading increased hepatic hepcidin by 3-fold and reduced duodenal expression of divalent metal transporter 1 (DMT1) by 76%. Nonheme-iron absorption was 2.5 times higher than heme-iron absorption (P = 0.0008). Absorption of both forms of iron was inversely correlated with hepatic hepcidin expression (heme-iron absorption: r = −0.77, P = 0.003; nonheme-iron absorption: r = −0.80, P = 0.002), but hepcidin had a stronger impact on nonheme-iron absorption (P = 0.04). Significantly more 57Fe was recovered in RBCs (P = 0.02), and more 58Fe was recovered in the spleen (P = 0.01). Conclusions: Elevated hepcidin significantly decreased heme- and nonheme-iron absorption but had a greater impact on nonheme-iron absorption. Differential tissue utilization of heme vs. nonheme iron was evident between erythroid and iron storage tissues, suggesting that some heme may be exported into the circulation in a form different from that of nonheme iron. PMID:25332470

  14. Melting of iron determined by X-ray absorption spectroscopy to 100 GPa

    PubMed Central

    Aquilanti, Giuliana; Trapananti, Angela; Karandikar, Amol; Kantor, Innokenty; Marini, Carlo; Mathon, Olivier; Pascarelli, Sakura; Boehler, Reinhard

    2015-01-01

    Temperature, thermal history, and dynamics of Earth rely critically on the knowledge of the melting temperature of iron at the pressure conditions of the inner core boundary (ICB) where the geotherm crosses the melting curve. The literature on this subject is overwhelming, and no consensus has been reached, with a very large disagreement of the order of 2,000 K for the ICB temperature. Here we report new data on the melting temperature of iron in a laser-heated diamond anvil cell to 103 GPa obtained by X-ray absorption spectroscopy, a technique rarely used at such conditions. The modifications of the onset of the absorption spectra are used as a reliable melting criterion regardless of the solid phase from which the solid to liquid transition takes place. Our results show a melting temperature of iron in agreement with most previous studies up to 100 GPa, namely of 3,090 K at 103 GPa. PMID:26371317

  15. Iron absorption in raw and cooked bananas: A field study using stable isotopes in women

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Banana is a staple food in many regions with high iron deficiency and may be a potential vehicle for iron fortification. However, iron absorption from bananas is not known. The objective of this study was to evaluate total iron absorption from raw and cooked bananas. Thirty women (34.9 +/- 6.6 years...

  16. The role of terahertz polariton absorption in the characterization of crystalline iron sulfate hydrates.

    PubMed

    Ruggiero, Michael T; Bardon, Tiphaine; Strlič, Matija; Taday, Philip F; Korter, Timothy M

    2015-04-14

    Iron sulfate compounds have been used extensively to produce iron gall ink, a widely used writing ink in the western world from the 12th-20th centuries. Iron gall ink is well known to corrode writing supports, so detection of iron species is important for the preservation of historical artwork and documents. Iron(ii) sulfate readily changes hydration states and oxidizes in ambient conditions, forming compounds that contribute to this deterioration. In this study, five forms of iron sulfate are characterized by terahertz spectroscopy and solid-state density functional theory (DFT). The results have revealed that the room temperature spectra of FeSO4·7H2O and FeSO4·4H2O are remarkably similar, differing by only a single absorption feature. The identifying terahertz spectra provide an unambiguous metric to determine the relative concentrations of the most common hydrates FeSO4·7H2O and FeSO4·4H2O in a mixed sample. Complete spectral assignments of these species were accomplished by quantum mechanical simulations, with the exception being a single anomalous feature at approximately 40 cm(-1) in the heptahydrate. This peak is believed to be due to polariton absorption, brought about by the particular coordination structure of FeSO4·7H2O that results in a greater charge separation relative to the other iron sulfate crystals.

  17. Iron L-Edge Absorption Spectroscopy of Iron Pentacarbonyl and Ferrocene in the Gas Phase.

    PubMed

    Godehusen, Kai; Richter, Tobias; Zimmermann, Peter; Wernet, Philippe

    2017-01-12

    Fe L-edge X-ray absorption spectra of gas-phase iron pentacarbonyl and ferrocene measured in total-ion yield mode are reported. Comparison to previously published spectra of free iron atoms and gaseous iron chloride demonstrates how the interplay of local atomic multiplet effects and orbital interactions in the metal-ligand bonds varies for the different systems. We find changes in the degree of metal-ligand covalency to be reflected in the measured 2p absorption onset. Orbital- or state-specific fragmentation is furthermore investigated in iron pentacarbonyl and ferrocene by analyzing the partial-ion-yield spectra at the Fe L-edge. Strong dependence of the yields of different fragments is observed in ferrocene in contrast to iron pentacarbonyl. This difference is attributed to the different degrees to which the 2p core hole is screened in the two systems and to which charge is rearranged in the Auger final states. We provide experimental benchmark spectra for new ab initio approaches for calculating metal L-edge absorption spectra of metal complexes.

  18. Mathematical Modeling of Intestinal Iron Absorption Using Genetic Programming

    PubMed Central

    Colins, Andrea; Gerdtzen, Ziomara P.; Nuñez, Marco T.; Salgado, J. Cristian

    2017-01-01

    Iron is a trace metal, key for the development of living organisms. Its absorption process is complex and highly regulated at the transcriptional, translational and systemic levels. Recently, the internalization of the DMT1 transporter has been proposed as an additional regulatory mechanism at the intestinal level, associated to the mucosal block phenomenon. The short-term effect of iron exposure in apical uptake and initial absorption rates was studied in Caco-2 cells at different apical iron concentrations, using both an experimental approach and a mathematical modeling framework. This is the first report of short-term studies for this system. A non-linear behavior in the apical uptake dynamics was observed, which does not follow the classic saturation dynamics of traditional biochemical models. We propose a method for developing mathematical models for complex systems, based on a genetic programming algorithm. The algorithm is aimed at obtaining models with a high predictive capacity, and considers an additional parameter fitting stage and an additional Jackknife stage for estimating the generalization error. We developed a model for the iron uptake system with a higher predictive capacity than classic biochemical models. This was observed both with the apical uptake dataset used for generating the model and with an independent initial rates dataset used to test the predictive capacity of the model. The model obtained is a function of time and the initial apical iron concentration, with a linear component that captures the global tendency of the system, and a non-linear component that can be associated to the movement of DMT1 transporters. The model presented in this paper allows the detailed analysis, interpretation of experimental data, and identification of key relevant components for this complex biological process. This general method holds great potential for application to the elucidation of biological mechanisms and their key components in other complex

  19. Properties of iron under core conditions

    NASA Astrophysics Data System (ADS)

    Brown, J. M.

    2003-04-01

    Underlying an understanding of the geodynamo and evolution of the core is knowledge of the physical and chemical properties of iron and iron mixtures under high pressure and temperature conditions. Key properties include the viscosity of the fluid outer core, thermal diffusivity, equations-of-state, elastic properties of solid phases, and phase equilibria for iron and iron-dominated mixtures. As is expected for work that continues to tax technological and intellectual limits, controversy has followed both experimental and theoretical progress in this field. However, estimates for the melting temperature of the inner core show convergence and the equation-of-state for iron as determined in independent experiments and theories are in remarkable accord. Furthermore, although the structure and elastic properties of the solid inner-core phase remains uncertain, theoretical and experimental underpinnings are better understood and substantial progress is likely in the near future. This talk will focus on an identification of properties that are reasonably well known and those that merit further detailed study. In particular, both theoretical and experimental (static and shock wave) determinations of the density of iron under extreme conditions are in agreement at the 1% or better level. The behavior of the Gruneisen parameter (which determines the geothermal gradient and controls much of the outer core heat flux) is constrained by experiment and theory under core conditions for both solid and liquid phases. Recent experiments and theory are suggestive of structure or structures other than the high-pressure hexagonal close-packed (HCP) phase. Various theories and experiments for the elasticity of HCP iron remain in poor accord. Uncontroversial constraints on core chemistry will likely never be possible. However, reasonable bounds are possible on the basis of seismic profiles, geochemical arguments, and determinations of sound velocities and densities at high pressure and

  20. Probing iron spin state by optical absorption in laser-heated diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Lobanov, S.; Goncharov, A. F.; Holtgrewe, N.; Lin, J. F.

    2015-12-01

    Pressure-induced spin-pairing transitions in iron-bearing minerals have been in the focus of geophysical studies1. Modern consensus is that iron spin state in the lower mantle is a complex function of crystal structure, composition, pressure, and temperature. Discontinuities in physical properties of lower mantle minerals have been revealed over the spin transition pressure range, but at room temperature. In this work, we have used a supercontinuum laser source and an intensified CCD camera to probe optical properties of siderite, FeCO3, and post-perovskite, Mg0.9Fe0.1SiO3, across the spin transition in laser-heated diamond anvil cell. Synchronously gating the CCD with the supercontinuum pulses (Fig. 1A) allowed diminishing thermal background to ~8.3*10-4. Utilizing the experimental setup we infer the spin state of ferrous iron in siderite at high pressure and temperature conditions (Fig. 1B). Similar behavior is observed for low spin ferric iron in post-perovskite at 130 GPa indicating that all iron in post-perovskite is high spin at lower mantle conditions. Also, our experimental setup holds promise for measuring radiative thermal conductivity of mantle minerals at relevant mantle conditions. Figure 1. (A) Timing of the optical absorption measurements at high temperature. (B) High temperature siderite absorption spectra at 45 GPa. Before heating and quenched after 1300 K spectra are shown in light and dark blue, respectively. Green and red curves are absorption spectra at 1200 K and 1300 K, respectively. Spectra shown in black represent room temperature absorption data on HS (43 GPa) and LS (45.5 GPa) siderite after Lobanov et al., 2015, shown for comparison.

  1. Calcium does not inhibit iron absorption or alter iron status in infant piglets adapted to a high calcium diet.

    PubMed

    Wauben, I P; Atkinson, S A

    1999-03-01

    The purpose of this study was to investigate whether a dietary calcium:iron ratio similar to that often consumed by premature human infants inhibits iron absorption in infant piglets adapted to a high calcium diet. Male Yorkshire piglets were randomized at 3 to 4 d of age to a high calcium diet (4.67 g/L = HC) or a normal calcium diet (2.0 g/L = NC) and fed for 2 to 2.5 wk. An iron dextran injection was administered in amounts to achieve a marginal state of iron repletion to simulate iron status of premature infants. In vivo iron absorption from the diet was determined using the radiotracers 55Fe and 59Fe and whole body counting. Calcium:iron interactions at absorption sites in piglets fed HC and NC were investigated by measurements of time-dependent 59Fe uptake in response to different calcium:iron ratios in vitro in brush border membrane vesicles (BBMV). In vivo iron absorption from the diet did not differ between NC and HC diet groups [57 +/- 8% versus 55 +/- 17% (mean +/- SD), respectively]. Iron status and iron contencentrations in spleen, liver, intestine, kidney and heart did not differ between diet groups. Iron uptake in BBMV was significantly reduced by calcium in both HC and NC (P < 0.001); but there were no significant differences in iron uptake in response to different calcium:iron ratios between HC and NC. With feeding a HC diet for 2 wk there may be an adaptive response to counteract the inhibitory effects of calcium on iron absorption, thus resulting in similar in vivo iron absorption and iron status irrespective of the 1.3-fold difference in dietary calcium:iron ratio between piglet groups. However, future studies are needed to determine the specific sites of calcium:iron interactions and adaptation mechanisms. Since the calcium:iron ratios used in this study reflect the usual calcium:iron ratios in diets for premature infants, it is unlikely that interactive effects of calcium with iron will compromise iron status in this infant population when

  2. An iron absorption model of gamma-ray burst spectra

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.; Kargatis, Vincent E.

    1994-01-01

    Most gamma-ray bursts (GRBs) exhibit deficits of X-rays below approximately 200 keV. Here we consider a spectral model in which the burst source is shielded by an optically thick layer of circumburster material (CBM) rich in iron-group elements whose photoelectric absorption opacity exceeds the Thomson opacity below approximately 120 keV. For power-law distributions of absorption depths along the lines of sight the absorbed spectrum can indeed mimic the typial GRB spectrum. This model predicts that (a) the spectrum should evolve monotonically from hard to soft during each energy release, which is observed in most bursts, especially in fast rise exponential decay bursts; (b) Fe spectral features near 7 keV may be present in some bursts; and (c) the ratio of burst distances to the CBM and to Earth should be approximately 10(exp -11) if the spectral evolution is purely due to Fe stripping by the photons.

  3. Effect of different drinks on the absorption of non-heme iron from composite meals.

    PubMed

    Hallberg, L; Rossander, L

    1982-04-01

    A study was made on the effect of various drinks on the absorption on non-heme iron. The drinks were taken with standard meals composed of a hamburger, string beans and mashed potatoes. In each series identical meals were served to the same subject either with water or with the drink under study, labelling the meals with two different radio-iron isotopes. A reduction in iron absorption was seen when serving tea (62 per cent) or coffee (35 per cent) with the meals. Orange juice increased the iron absorption (85 per cent). Pure alcohol and wine increased only slightly the percentage absorbed. Wine often has a high iron content, which increased significantly the amount of iron absorbed (three times). Milk and beer have no significant effect. Coca-Cola increased only slightly the absorption. The present studies clearly shows that the choice of drink drunk with a meal can markedly affect the absorption of non-heme iron.

  4. Iron absorption after introducing and discontinuation of iron and zinc supplementation in rats.

    PubMed

    Januszko, Olga; Madej, Dawid; Brzozowska, Anna; Kaluza, Joanna

    2016-05-01

    The aim of this study was to investigate the changes in iron apparent absorption (IAA%) during and after iron and zinc supplementation in rats. The study was conducted on 6-week old male Wistar rats in 3 stages: 4-week period of adaptation to the control (C) and iron deficient (D) diets (stage I); 4-week period of supplementation with 10-time more iron (CSFe, DSFe), zinc (CSZn, DSZn) or both iron and zinc (CSFeZn, DSFeZn) compared to C diet (stage II); 2-week of post-supplementation period (rats were fed the same diets as in the adaptation period, stage III). IAA% was measured in five consecutive days directly after introducing and discontinuation of iron and zinc supplementation as well as in the end of stage II (days: 22-24th) and stage III (days: 8-10th). Overall in the second day after introducing and in the fifth day after discontinuation of iron or iron and zinc supplementation, the IAA% had undergone to the level compatible with the values in the end of each stage. At the end of stage II, IAA% in CSFeZn (54.1 ± 2.7%) rats was not different from the IAA% in CSFe rats (53.9 ± 1.9%), but in DSFeZn group IAA% (49.4 ± 2.1%) was significantly lower than in DSFe (57.4 ± 2.3%) group. Moreover, IAA% after stage II and stage III in DSZn group was significantly lower (39.2 ± 2.8% and 38.6 ± 2.6%, respectively) than in group D (60.7 ± 1.9% and 54.3 ± 3.0%, respectively). In conclusion, zinc administered simultaneously with iron (Zn:Fe weight ratio=1:1) decreased IAA% in adult rats fed on iron deficient diet, but not in rats fed on control diet. IAA% reduction by zinc supplementation has been extended to 10 days after discontinuation of the treatment. Adaptation of the rats to high doses of iron or iron and zinc and also to the cessation of these treatments was relatively fast. However, IAA% was stabilized faster after introducing the supplementation than it's discontinuation.

  5. Intestinal ferritin H is required for an accurate control of iron absorption.

    PubMed

    Vanoaica, Liviu; Darshan, Deepak; Richman, Larry; Schümann, Klaus; Kühn, Lukas C

    2010-09-08

    To maintain appropriate body iron levels, iron absorption by the proximal duodenum is thought to be controlled by hepcidin, a polypeptide secreted by hepatocytes in response to high serum iron. Hepcidin limits basolateral iron efflux from the duodenal epithelium by binding and downregulating the intestinal iron exporter ferroportin. Here, we found that mice with an intestinal ferritin H gene deletion show increased body iron stores and transferrin saturation. As expected for iron-loaded animals, the ferritin H-deleted mice showed induced liver hepcidin mRNA levels and reduced duodenal expression of DMT1 and DcytB mRNA. In spite of these feedback controls, intestinal ferroportin protein and (59)Fe absorption were increased more than 2-fold in the deleted mice. Our results demonstrate that hepcidin-mediated regulation alone is insufficient to restrict iron absorption and that intestinal ferritin H is also required to limit iron efflux from intestinal cells.

  6. Calcium and iron absorption--mechanisms and public health relevance.

    PubMed

    Lönnerdal, Bo

    2010-10-01

    Studies on human subjects have shown that calcium (Ca) can inhibit iron (Fe) absorption, regardless of whether it is given as Ca salts or in dairy products. This has caused concern as increased Ca intake commonly is recommended for children and women, the same populations that are at risk of Fe deficiency. However, a thorough review of studies on humans in which Ca intake was substantially increased for long periods shows no changes in hematological measures or indicators of iron status. Thus, the inhibitory effect may be of short duration and there also may be compensatory mechanisms. The interaction between Ca and Fe may be a lumenal event, affecting Fe uptake through DMT1 (divalent metal transporter 1) at the apical membrane. However, it is also possible that inhibition occurs during Fe transfer into circulation, suggesting roles for the serosal exporter ferroportin (FPN) and hephaestin. We explored these possibilities in human intestinal Caco-2 cells cultured in monolayers. Iron transport ((59)Fe) and expression of DMT1, FPN, and hephaestin were assessed after 1.5 and 4 hours with 0 or 100 µM CaCl(2.) Although Ca did not affect Fe uptake or DMT1 expression at 1.5 hours, FPN abundance at the basolateral membrane decreased, resulting in increased cellular Fe retention and decreased Fe efflux. After 4 hours, DMT1 and FPN expression increased and there was increased FPN at the membrane, suggesting a rebound effect. Thus, the effect of Ca on Fe absorption may be of short duration and adaptation may occur with time. This may explain why studies on long-term Ca supplementation of different groups fail to show any adverse effects on Fe status.

  7. Iron supplementation does not affect copper and zinc absorption in breastfed infants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iron supplements are commonly recommended for infants but were suggested to inhibit zinc and copper absorption. The objective of this study was to investigate potential effects of iron supplementation, infant age, and mineral status on zinc and copper absorption in infants at 6 and 9 mo of age. Twen...

  8. Calcium: effect of different amounts on nonheme- and heme-iron absorption in humans.

    PubMed

    Hallberg, L; Brune, M; Erlandsson, M; Sandberg, A S; Rossander-Hultén, L

    1991-01-01

    We investigated the effect of calcium on iron absorption in 126 human subjects. Addition of calcium chloride to wheat rolls significantly reduced iron absorption. Doses between 40 and 600 mg Ca were studied. The inhibition was clearly dose related up to 300 mg Ca. Calcium added to the dough when making the rolls reduced phytate degradation during fermentation and baking. As little as 40 mg Ca added to 80 g flour reduced phytate degradation by 50%, thus increasing the phytate content of the rolls to levels interfering with iron absorption. Calcium also had a direct dose-related inhibiting effect on iron absorption, noted by adding calcium to the rolls after they had been baked instead of to the dough. Iron absorption was reduced by 50-60% at doses of 300-600 mg Ca. Giving 165 mg Ca as milk, cheese, or calcium chloride reduced absorption by 50-60%. The same amount of calcium also significantly reduced heme-iron absorption, suggesting that the effect of calcium is related to the mucosal transfer of iron. The observed marked inhibitory effect on iron absorption of calcium in amounts frequently encountered in normal meals has important nutritional implications.

  9. Iron absorption in raw and cooked bananas: a field study using stable isotopes in women

    PubMed Central

    García, Olga P.; Martínez, Mara; Romano, Diana; Camacho, Mariela; de Moura, Fabiana F.; Abrams, Steve A.; Khanna, Harjeet K.; Dale, James L.; Rosado, Jorge L.

    2015-01-01

    Background Banana is a staple food in many regions with high iron deficiency and may be a potential vehicle for iron fortification. However, iron absorption from bananas is not known. Objective The objective of this study was to evaluate total iron absorption from raw and cooked bananas. Design Thirty women (34.9±6.6 years) from rural Mexico were randomly assigned to one of two groups each consuming: 1) 480 g/day of raw banana for 6 days, or 2) 500 g/day of cooked banana for 4 days. Iron absorption was measured after extrinsically labeling with 2 mg of 58Fe and a reference dose of 6 mg 57Fe; analysis was done using ICP-MS. Results Iron content in cooked bananas was significantly higher than raw bananas (0.53 mg/100 g bananas vs. 0.33 mg/100 mg bananas, respectively) (p<0.001). Percent iron absorption was significantly higher in raw bananas (49.3±21.3%) compared with cooked banana (33.9±16.2%) (p=0.035). Total amount of iron absorbed from raw and cooked bananas was similar (0.77±0.33 mg vs. 0.86±0.41 mg, respectively). Conclusion Total amount of absorbed iron is similar between cooked and raw bananas. The banana matrix does not affect iron absorption and is therefore a potential effective target for genetic modification for iron biofortification. PMID:25660254

  10. Dietary inulin supplementation does not promote colonic iron absorption in a porcine model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Prebiotics may enhance iron bioavailability by increasing iron absorption in the colon. Anemic pigs fitted with cecal cannulas were fed a low-iron diet with or without 4% inulin. Over 7 days, pigs were administered 1 mg 54 Fe in the morning feed followed by cannula infusion of 0.5 mg 58 Fe to measu...

  11. A complete diet-based algorithm for predicting nonheme iron absorption in adults.

    PubMed

    Armah, Seth M; Carriquiry, Alicia; Sullivan, Debra; Cook, James D; Reddy, Manju B

    2013-07-01

    Many algorithms have been developed in the past few decades to estimate nonheme iron absorption from the diet based on single meal absorption studies. Yet single meal studies exaggerate the effect of diet and other factors on absorption. Here, we propose a new algorithm based on complete diets for estimating nonheme iron absorption. We used data from 4 complete diet studies each with 12-14 participants for a total of 53 individuals (19 men and 34 women) aged 19-38 y. In each study, each participant was observed during three 1-wk periods during which they consumed different diets. The diets were typical, high, or low in meat, tea, calcium, or vitamin C. The total sample size was 159 (53 × 3) observations. We used multiple linear regression to quantify the effect of different factors on iron absorption. Serum ferritin was the most important factor in explaining differences in nonheme iron absorption, whereas the effect of dietary factors was small. When our algorithm was validated with single meal and complete diet data, the respective R(2) values were 0.57 (P < 0.001) and 0.84 (P < 0.0001). The results also suggest that between-person variations explain a large proportion of the differences in nonheme iron absorption. The algorithm based on complete diets we propose is useful for predicting nonheme iron absorption from the diets of different populations.

  12. Chili, but not turmeric, inhibits iron absorption in young women from an iron-fortified composite meal.

    PubMed

    Tuntipopipat, Siriporn; Judprasong, Kunchit; Zeder, Christophe; Wasantwisut, Emorn; Winichagoon, Pattanee; Charoenkiatkul, Somsri; Hurrell, Richard; Walczyk, Thomas

    2006-12-01

    Chili and turmeric are common spices in indigenous diets in tropical regions. Being rich in phenolic compounds, they would be expected to bind iron (Fe)(3) in the intestine and inhibit Fe absorption in humans. Three experiments were conducted in healthy young women (n = 10/study) to assess the effect of chili and turmeric on Fe absorption from a rice-based meal containing vegetables and iron fortified fish sauce in vivo. Iron absorption was determined by erythrocyte incorporation of stable isotope labels ((57)Fe/(58)Fe) using a randomized crossover design. Addition of freeze-dried chili (4.2 g dry powder, 25 mg polyphenols as gallic acid equivalents) reduced Fe absorption from the meal by 38% (6.0% with chili vs. 9.7% without chili, P = 0.0017). Turmeric (0.5 g dry powder, 50 mg polyphenols as gallic acid equivalents) did not inhibit iron absorption (P = 0.91). A possible effect of chili on gastric acid secretion was indirectly assessed by comparing Fe absorption from acid soluble [(57)Fe]-ferric pyrophosphate relative to water soluble [(58)Fe]-ferrous sulfate from the same meal in the presence and absence of chili. Chili did not enhance gastric acid secretion. Relative Fe bioavailability of ferric pyrophosphate was 5.4% in presence of chili and 6.4% in absence of chili (P = 0.47). Despite the much higher amount of phenolics in the turmeric meal, it did not affect iron absorption. We conclude that both phenol quality and quantity determine the inhibitory effect of phenolic compounds on iron absorption.

  13. Quercetin inhibits intestinal iron absorption and ferroportin transporter expression in vivo and in vitro.

    PubMed

    Lesjak, Marija; Hoque, Rukshana; Balesaria, Sara; Skinner, Vernon; Debnam, Edward S; Srai, Surjit K S; Sharp, Paul A

    2014-01-01

    Balancing systemic iron levels within narrow limits is critical for maintaining human health. There are no known pathways to eliminate excess iron from the body and therefore iron homeostasis is maintained by modifying dietary absorption so that it matches daily obligatory losses. Several dietary factors can modify iron absorption. Polyphenols are plentiful in human diet and many compounds, including quercetin--the most abundant dietary polyphenol--are potent iron chelators. The aim of this study was to investigate the acute and longer-term effects of quercetin on intestinal iron metabolism. Acute exposure of rat duodenal mucosa to quercetin increased apical iron uptake but decreased subsequent basolateral iron efflux into the circulation. Quercetin binds iron between its 3-hydroxyl and 4-carbonyl groups and methylation of the 3-hydroxyl group negated both the increase in apical uptake and the inhibition of basolateral iron release, suggesting that the acute effects of quercetin on iron transport were due to iron chelation. In longer-term studies, rats were administered quercetin by a single gavage and iron transporter expression measured 18 h later. Duodenal FPN expression was decreased in quercetin-treated rats. This effect was recapitulated in Caco-2 cells exposed to quercetin for 18 h. Reporter assays in Caco-2 cells indicated that repression of FPN by quercetin was not a transcriptional event but might be mediated by miRNA interaction with the FPN 3'UTR. Our study highlights a novel mechanism for the regulation of iron bioavailability by dietary polyphenols. Potentially, diets rich in polyphenols might be beneficial for patients groups at risk of iron loading by limiting the rate of intestinal iron absorption.

  14. Point defect absorption by grain boundaries in α -iron by atomic density function modeling

    NASA Astrophysics Data System (ADS)

    Kapikranian, O.; Zapolsky, H.; Patte, R.; Pareige, C.; Radiguet, B.; Pareige, P.

    2015-12-01

    Using the atomic density function theory (ADFT), we examine the point defect absorption at [110] symmetrical tilt grain boundaries in body-centered cubic iron. It is found that the sink strength strongly depends on misorientation angle. We also show that the ADFT is able to reproduce reasonably well the elastic properties and the point defect formation volume in α -iron.

  15. Effect of tannic acid on iron absorption in straw-colored fruit bats(Eidolon helvum)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excessive absorption and subsequent storage of dietary iron has been found in a variety of captively held birds and mammals, including fruit bats. It is thought that feeding a diet that is low in iron can prevent the onset of this disease; however, manufacturing a diet with commonly available foodst...

  16. Intestinal Absorption of Hemoglobin Iron-Heme Cleavage by Mucosal Heme Oxygenase

    PubMed Central

    Raffin, Steven B.; Woo, Choong H.; Roost, Kenneth T.; Price, David C.; Schmid, Rudi

    1974-01-01

    Hemoglobin and myoglobin are a major source of dietary iron in man. Heme, separated from these hemoproteins by intraluminal proteolysis, is absorbed intact by the intestinal mucosa. The absorbed heme is cleaved in the mucosal cell releasing inorganic iron. Although this mucosal heme-splitting activity initially was ascribed to xanthine oxidase, we investigated the possibility that it is catalyzed by microsomal heme oxygenase, an enzyme which converts heme to bilirubin, CO, and inorganic iron. Microsomes prepared from rat intestinal mucosa contain enzymatic activity similar to that of heme oxygenase in liver and spleen. The intestinal enzyme requires NADPH; is completely inhibited by 50% CO; and produces bilirubin IX-α, identified spectrophotometrically and chromatographically. Moreover, duodenal heme oxygenase was shown to release inorganic 55Fe from 55Fe-heme. Along the intestinal tract, enzyme activity was found to be highest in the duodenum where hemoglobin iron absorption is reported to be most active. Furthermore, when rats were made iron deficient, duodenal heme oxygenase activity and hemoglobin-iron absorption rose to a comparable extent. Upon iron repletion of iron-deficient animals, duodenal enzyme activity returned towards control values. In contrast to heme oxygenase, duodenal xanthine oxidase activity fell sharply in iron deficiency and rose towards base line upon iron repletion. Our findings suggest that mucosal heme oxygenase catalyzes the cleavage of heme absorbed in the intestinal mucosa and thus plays an important role in the absorption of hemoglobin iron. The mechanisms controlling this intestinal enzyme activity and the enzyme's role in the overall regulation of hemoglobin-iron absorption remain to be defined. PMID:4436436

  17. Activable enriched stable isotope iron-58 for monitoring absorption rate of juvenile athletes for iron: a case study.

    PubMed

    Qian, Qinfang; Chai, Zhifang; Feng, Weiyu; Chen, Jidi; Zhang, Peiqun; Pan, Jianxiang

    2002-09-01

    Activable enriched stable isotopes can play a unique role in studies of nutritional status, metabolism, absorption rates, and bioavailability of minerals. As a practical example, eight juvenile athletes were selected to test the absorption rates of iron during training and non-training periods by enriched stable isotope of Fe-58 (enriched degree: 51.1%) via activation analysis Fe-58 (n, gamma) Fe-59 of the collected feces samples. The results indicated that the average iron absorption rates of the juvenile athletes with and without training are 9.1 +/- 2.8 and 11.9 +/- 4.7%, respectively, which implies that the long-term endurance training with high intensity makes the iron absorption rate of athletes lower. In the meantime, the comparison of the activable enriched isotope technique with atomic absorption spectrometry was performed, which showed that the former was better than the latter in reliability and sensitivity. It is because this nuclear method can distinguish the exogenous and endogenous iron in the samples, but not for non-nuclear methods.

  18. Oral exposure to polystyrene nanoparticles effects iron absorption

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of engineered nanoparticles in food and pharmaceuticals is expected to increase, but the impact of chronic oral exposure to nanoparticles on human health remains unknown. Here, we show that chronic and acute oral exposure to polystyrene nanoparticles can influence iron uptake and iron trans...

  19. X-ray absorption spectroscopy of iron at multimegabar pressures in laser shock experiments

    NASA Astrophysics Data System (ADS)

    Harmand, M.; Ravasio, A.; Mazevet, S.; Bouchet, J.; Denoeud, A.; Dorchies, F.; Feng, Y.; Fourment, C.; Galtier, E.; Gaudin, J.; Guyot, F.; Kodama, R.; Koenig, M.; Lee, H. J.; Miyanishi, K.; Morard, G.; Musella, R.; Nagler, B.; Nakatsutsumi, M.; Ozaki, N.; Recoules, V.; Toleikis, S.; Vinci, T.; Zastrau, U.; Zhu, D.; Benuzzi-Mounaix, A.

    2015-07-01

    Taking advantage of the new opportunities provided by x-ray free electron laser (FEL) sources when coupled to a long laser pulse as available at the Linear Coherent Light Source (LCLS), we have performed x-ray absorption near-edge spectroscopy (XANES) of laser shock compressed iron up to 420 GPa (±50 ) and 10 800 K (±1390 ). Visible diagnostics coupled with hydrodynamic simulations were used to infer the thermodynamical conditions along the Hugoniot and the release adiabat. A modification of the pre-edge feature at 7.12 keV in the XANES spectra is observed above pressures of 260 GPa along the Hugoniot. Comparing with ab initio calculations and with previous laser-heated diamond cell data, we propose that such changes in the XANES pre-edge could be a signature of molten iron. This interpretation then suggests that iron is molten at pressures and temperatures higher than 260 GPa (±29 ) and 5680 K (±700 ) along the principal Fe Hugoniot.

  20. Serum hepcidin is significantly associated with iron absorption from food and supplemental sources in healthy young woman

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hepcidin is a key regulator of iron homeostasis, but to date no studies have examined the effect of hepcidin on iron absorption in humans. Our objective was to assess relations between both serum hepcidin and serum prohepcidin with nonheme-iron absorption in the presence and absence of food with the...

  1. Total Iron Absorption by Young Women from Iron-Biofortified Pearl Millet Composite Meals Is Double That from Regular Millet Meals but Less Than That from Post-Harvest Iron-Fortified Millet Meals123

    PubMed Central

    Cercamondi, Colin I.; Egli, Ines M.; Mitchikpe, Evariste; Tossou, Felicien; Zeder, Christophe; Hounhouigan, Joseph D.; Hurrell, Richard F.

    2013-01-01

    Iron biofortification of pearl millet (Pennisetum glaucum) is a promising approach to combat iron deficiency (ID) in the millet-consuming communities of developing countries. To evaluate the potential of iron-biofortified millet to provide additional bioavailable iron compared with regular millet and post-harvest iron-fortified millet, an iron absorption study was conducted in 20 Beninese women with marginal iron status. Composite test meals consisting of millet paste based on regular-iron, iron-biofortified, or post-harvest iron-fortified pearl millet flour accompanied by a leafy vegetable sauce or an okra sauce were fed as multiple meals for 5 d. Iron absorption was measured as erythrocyte incorporation of stable iron isotopes. Fractional iron absorption from test meals based on regular-iron millet (7.5%) did not differ from iron-biofortified millet meals (7.5%; P = 1.0), resulting in a higher quantity of total iron absorbed from the meals based on iron-biofortified millet (1125 vs. 527 μg; P < 0.0001). Fractional iron absorption from post-harvest iron-fortified millet meals (10.4%) was higher than from regular-iron and iron-biofortified millet meals (P < 0.05 and P < 0.01, respectively), resulting in a higher quantity of total iron absorbed from the post-harvest iron-fortified millet meals (1500 μg; P < 0.0001 and P < 0.05, respectively). Results indicate that consumption of iron-biofortified millet would double the amount of iron absorbed and, although fractional absorption of iron from biofortification is less than that from fortification, iron-biofortified millet should be highly effective in combatting ID in millet-consuming populations. PMID:23884388

  2. Effect of iron status in rats on the absorption of metal ions from plant ferritin.

    PubMed

    Zielińska-Dawidziak, Magdalena; Hertig, Iwona; Staniek, Halina; Piasecka-Kwiatkowska, Dorota; Nowak, Krzysztof W

    2014-06-01

    An isolate of lead-ferritin obtained from soybean seeds sprouted in 25 mM of PbNO3 was introduced into the diet of both iron-deficient and iron non-deficient male rats. After a 21-day administration period, statistical differences in the lead accumulation in the femurs of the rats were noted. Iron-deficient rats accumulated more than four times the amount of lead in their bones than rats without iron-deficiency. No further decrease was observed in haemoglobin concentrations in the groups of animals fed with lead isolates, either iron-deficient or iron non-deficient. Also, no differences in the mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV) were observed at the end of the experiment in the group of iron non-deficient rats fed with lead-ferritin isolate compared to the control group of iron non-deficient rats. In the iron-deficient group fed with lead-ferritin isolate, a small increase in haemoglobin concentrations, MCH, MCV and mean corpuscular haemoglobin concentrations (MCHC) was recorded. The results presented in this paper confirm that lead from the tested preparation-lead ferritin isolate-was better absorbed by those rats with induced iron deficiency anaemia. Additionally, we may also suspect based on the obtained results that absorption of ferritin-iron depends on iron status in the body.

  3. The influence of high iron diet on rat lung manganese absorption

    SciTech Connect

    Thompson, Khristy; Molina, Ramon; Donaghey, Thomas; Brain, Joseph D.; Wessling-Resnick, Marianne . E-mail: wessling@hsph.harvard.edu

    2006-01-15

    Individuals chronically exposed to manganese are at high risk for neurotoxic effects of this metal. A primary route of exposure is through respiration, although little is known about pulmonary uptake of metals or factors that modify this process. High dietary iron levels inversely affect intestinal uptake of manganese, and a major goal of this study was to determine if dietary iron loading could increase lung non-heme iron levels and alter manganese absorption. Rats were fed a high iron (1% carbonyl iron) or control diet for 4 weeks. Lung non-heme iron levels increased {approx}2-fold in rats fed the high iron diet. To determine if iron-loading affected manganese uptake, {sup 54}Mn was administered by intratracheal (it) instillation or intravenous (iv) injection for pharmacokinetic studies. {sup 54}Mn absorption from the lungs to the blood was lower in it-instilled rats fed the 1% carbonyl iron diet. Pharmacokinetics of iv-injected {sup 54}Mn revealed that the isotope was cleared more rapidly from the blood of iron-loaded rats. In situ analysis of divalent metal transporter-1 (DMT1) expression in lung detected mRNA in airway epithelium and bronchus-associated lymphatic tissue (BALT). Staining of the latter was significantly reduced in rats fed the high iron diet. In situ analysis of transferrin receptor (TfR) mRNA showed staining in BALT alone. These data demonstrate that manganese absorption from the lungs to the blood can be modified by iron status and the route of administration.

  4. Effect of dietary pectin on iron absorption and turnover in the rat

    SciTech Connect

    Baig, M.M.; Burgin, C.W.; Cerda, J.J.

    1983-12-01

    The influence of dietary pectin on iron absorption and retention was studied in rats. Basal diet with low and normal iron levels were fed with and without addition of 2% citrus pectin. After 40 days rats were fasted for 24 hours and were given /sup 59/Fe in dilute HCl with or without 2% pectin by gavage. Whole-body counting techniques were employed to monitor /sup 59/Fe absorption and turnover. Rats maintained on low iron diet absorbed and retained a much higher proportion of /sup 59/Fe than rats maintained on normal level of iron. Dietary pectin at the level fed in this study had no influence on iron uptake and/or turnover in rats.

  5. X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

    SciTech Connect

    Westre, Tami E.

    1996-01-01

    Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s→3d pre-edge feature has been developed as a tool for investigating the oxidation state, spin state, and geometry of iron sites. Edge and EXAFS analyses have then been applied to the study of non-heme iron enzyme active sites.

  6. Alpha-lactalbumin and casein-glycomacropeptide do not affect iron absorption from formula in healthy term infants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iron absorption from infant formula is relatively low. Alpha-lactalbumin and casein-glycomacropeptide have been suggested to enhance mineral absorption. We therefore assessed the effect of alpha-lactalbumin and casein-glycomacropeptide on iron absorption from infant formula in healthy term infants. ...

  7. Microbial iron reduction under deep subsurface pressure conditions

    NASA Astrophysics Data System (ADS)

    Picard, A.; Daniel, I.; Testemale, D.; Hazemann, J.; Oger, P.

    2009-12-01

    The deep subsurface is characterized by hostile conditions in terms of temperature, pressure and nutrient availability. Our current view of the biosphere extension is restricted to depths shallower than the isotherm associated to the highest observed temperature for life, i.e. 122°C. At this temperature, depending on the geological setting, pressure varies between ambient pressure at geothermal springs and 350 MPa in cold subduction zones. In this high-pressure biosphere, biological iron reduction is an important process linked to carbon oxidation. Among the factors governing reaction rates and yields in the deep subsurface, pressure could be of importance due its effects on kinetic and equilibrium reactions. The understanding and modelling of Fe reduction in natural environments, especially in the subsurface, can be first comprehended thanks to studies of Fe reduction in pure cultures; indeed the study of the effects of high pressure on Fe-reducing bacteria in pure cultures can serve as a basic model for the effects of pressure on Fe reduction in the subsurface. We investigated the effects of pressure on the reduction of Fe(III) to Fe(II) by the bacterial model Shewanella oneidensis MR-1. This strain is a mesophilic and piezosensitive counterpart of the psychrophilic and piezophilic Shewanella representatives that have been frequently isolated from deep-sea environments. Kinetics of Fe(III) reduction to Fe(II) were monitored in situ by X-ray Absorption Spectroscopy (XAS) in an appropriate pressure vessel dedicated to in situ XAS measurements (Testemale et al. 2005). Measurements were performed at the BM30B beamline of the European Synchrotron Radiation Facilty (Grenoble, France). Experiments were conducted from 0.1 MPa to 100 MPa at MR-1 optimal temperature (30°C). Iron reduction was monitored until 100 MPa in cultures of MR-1 at a concentration of 10e8 cells/ml. This shows that the metabolic activity of a piezosensitive microbe extends far beyond its pressure

  8. Acupuncture Improves Intestinal Absorption of Iron in Iron-deficient Obese Patients: A Randomized Controlled Preliminary Trial

    PubMed Central

    Xie, Xin-Cai; Cao, Yan-Qiang; Gao, Qian; Wang, Chen; Li, Man; Wei, Shou-Gang

    2017-01-01

    Background: Obesity has an adverse effect on iron status. Hepcidin-mediated inhibition of iron absorption in the duodenum is a potential mechanism. Iron-deficient obese patients have diminished response to oral iron therapy. This study was designed to assess whether acupuncture could promote the efficacy of oral iron supplementation for the treatment of obesity-related iron deficiency (ID). Methods: Sixty ID or ID anemia (IDA) patients with obesity were screened at Beijing Hospital of Traditional Chinese Medicine and were randomly allocated to receive either oral iron replacement allied with acupuncture weight loss treatment (acupuncture group, n = 30) or oral iron combined with sham-acupuncture treatment (control group, n = 30). Anthropometric parameters were measured and blood samples were tested pre- and post-treatment. Differences in the treatment outcomes of ID/IDA were compared between the two groups. Results: After 8 weeks of acupuncture treatment, there was a significant decrease in body weight, body mass index, waist circumference, and waist/hip circumference ratio of patients in the acupuncture group, while no significant changes were observed in the control group. Oral iron supplementation brought more obvious improvements of iron status indicators including absolute increases in serum iron (11.08 ± 2.19 μmol/L vs. 4.43 ± 0.47 μmol/L), transferrin saturation (11.26 ± 1.65% vs. 1.01 ± 0.23%), and hemoglobin (31.47 ± 1.19 g/L vs. 21.00 ± 2.69 g/L) in the acupuncture group than control group (all P < 0.05). Meanwhile, serum leptin (2.26 ± 0.45 ng/ml vs. 8.13 ± 0.55 ng/ml, P < 0.05) and hepcidin (3.52 ± 1.23 ng/ml vs. 6.77 ± 0.84 ng/ml, P < 0.05) concentrations declined significantly in the acupuncture group than those in the control group. Conclusion: Acupuncture-based weight loss can enhance the therapeutic effects of iron replacement therapy for obesity-related ID/IDA through improving intestinal iron absorption, probably by downregulating the

  9. Removal of iron interferences by solvent extraction for geochemical analysis by atomic-absorption spectrophotometry

    USGS Publications Warehouse

    Zhou, L.; Chao, T.T.; Sanzolone, R.F.

    1985-01-01

    Iron is a common interferent in the determination of many elements in geochemical samples. Two approaches for its removal have been taken. The first involves removal of iron by extraction with methyl isobutyl ketone (MIBK) from hydrochloric acid medium, leaving the analytes in the aqueous phase. The second consists of reduction of iron(III) to iron(II) by ascorbic acid to minimize its extraction into MIBK, so that the analytes may be isolated by extraction. Elements of interest can then be determined using the aqueous solution or the organic extract, as appropriate. Operating factors such as the concentration of hydrochloric acid, amounts of iron present, number of extractions, the presence or absence of a salting-out agent, and the optimum ratio of ascorbic acid to iron have been determined. These factors have general applications in geochemical analysis by atomic-absorption spectrophotometry. ?? 1985.

  10. Zinc Absorption from Micronutrient Powder Is Low but Is not Affected by Iron in Kenyan Infants

    PubMed Central

    Esamai, Fabian; Liechty, Edward; Ikemeri, Justus; Westcott, Jamie; Kemp, Jennifer; Culbertson, Diana; Miller, Leland V.; Hambidge, K. Michael; Krebs, Nancy F.

    2014-01-01

    Interference with zinc absorption is a proposed explanation for adverse effects of supplemental iron in iron-replete children in malaria endemic settings. We examined the effects of iron in micronutrient powder (MNP) on zinc absorption after three months of home fortification with MNP in maize-based diets in rural Kenyan infants. In a double blind design, six-month-old, non-anemic infants were randomized to MNP containing 5 mg zinc, with or without 12.5 mg of iron (MNP + Fe and MNP − Fe, respectively); a control (C) group received placebo powder. After three months, duplicate diet collections and zinc stable isotopes were used to measure intake from MNP + non-breast milk foods and fractional absorption of zinc (FAZ) by dual isotope ratio method; total absorbed zinc (TAZ, mg/day) was calculated from intake × FAZ. Mean (SEM) TAZ was not different between MNP + Fe (n = 10) and MNP − Fe (n = 9) groups: 0.85 (0.22) and 0.72 (0.19), respectively, but both were higher than C (n = 9): 0.24 (0.03) (p = 0.04). Iron in MNP did not significantly alter zinc absorption, but despite intakes over double estimated dietary requirement, both MNP groups’ mean TAZ barely approximated the physiologic requirement for age. Impaired zinc absorption may dictate need for higher zinc doses in vulnerable populations. PMID:25493942

  11. Iron absorption in humans: bovine serum albumin compared with beef muscle and egg white

    SciTech Connect

    Hurrell, R.F.; Lynch, S.R.; Trinidad, T.P.; Dassenko, S.A.; Cook, J.D.

    1988-01-01

    We studied the influence of bovine serum albumin and beef meat on nonheme iron absorption in humans and on dialyzable iron in vitro. The addition of serum albumin to a maize gruel had no significant effect on nonheme Fe absorption whereas the addition of beef meat caused a threefold increase. When added to a bread meal, serum albumin caused a modest 60% increase in nonheme Fe absorption and beef meat had no effect. When added to a protein-free meal, serum albumin reduced Fe absorption by 47% compared with a 72% reduction on addition of egg white. The bioavailability of nonheme Fe from meals containing serum albumin was consistently overestimated by the in vitro technique. We conclude that the facilitation of nonheme Fe absorption by meat is not a general property of all animal protein but is better explained by the action of one or more specific animal tissues.

  12. Paenibacillus polymyxa BFKC01 enhances plant iron absorption via improved root systems and activated iron acquisition mechanisms.

    PubMed

    Zhou, Cheng; Guo, Jiansheng; Zhu, Lin; Xiao, Xin; Xie, Yue; Zhu, Jian; Ma, Zhongyou; Wang, Jianfei

    2016-08-01

    Despite the high abundance of iron (Fe) in most earth's soils, Fe is the major limiting factor for plant growth and development due to its low bioavailability. With an increasing recognition that soil microbes play important roles in plant growth, several strains of beneficial rhizobactria have been applied to improve plant nutrient absorption, biomass, and abiotic or biotic stress tolerance. In this study, we report the mechanisms of microbe-induced plant Fe assimilation, in which the plant growth promoting rhizobacteria (PGPR) Paenibacillus polymyxa BFKC01 stimulates plant's Fe acquisition machinery to enhance Fe uptake in Arabidopsis plants. Mechanistic studies show that BFKC01 transcriptionally activates the Fe-deficiency-induced transcription factor 1 (FIT1), thereby up-regulating the expression of IRT1 and FRO2. Furthermore, BFKC01 has been found to induce plant systemic responses with the increased transcription of MYB72, and the biosynthetic pathways of phenolic compounds are also activated. Our data reveal that abundant phenolic compounds are detected in root exudation of the BFKC01-inoculated plants, which efficiently facilitate Fe mobility under alkaline conditions. In addition, BFKC01 can secret auxin and further improved root systems, which enhances the ability of plants to acquire Fe from soils. As a result, BFKC01-inoculated plants have more endogenous Fe and increased photosynthetic capacity under alkaline conditions as compared to control plants. Our results demonstrate the potential roles of BFKC01 in promoting Fe acquisition in plants and underline the intricate integration of microbial signaling in controlling plant Fe acquisition.

  13. Citric acid mediates the iron absorption from low molecular weight human milk fractions.

    PubMed

    Palika, Ravindranadh; Mashurabad, Purna Chandra; Kilari, Sreenivasulu; Kasula, Sunanda; Nair, Krishnapillai Madhavan; Raghu, Pullakhandam

    2013-11-20

    Previously, we have demonstrated increased iron absorption from low molecular weight (LMW) human milk whey fractions. In the present study, we investigated the effect of heat denaturation, zinc (a competitor of iron), duodenal cytochrome b (DcytB) antibody neutralization and citrate lyase treatment on LMW human milk fraction (>5 kDa referred as 5kF) induced ferric iron reduction, solubilization, and uptake in Caco-2 cells. Heat denaturation and zinc inhibited the 5kF fraction induced ferric iron reduction. In contrast, zinc but not heat denaturation abrogated the ferric iron solubilization activity. Despite inhibition of ferric iron reduction, iron uptake in Caco-2 cells was similar from both native and heat denatured 5kF fractions. However, iron uptake was higher from native compared to heat denatured 5kF fractions in the cells preincubated with the DcytB antibody. Citrate lyase treatment inhibited the ferric iron reduction, solubilization, and uptake in Caco-2 cells. These findings demonstrate that citric acid present in human milk solubilizes the ferric iron which could be reduced by other heat labile components leading to increased uptake in intestinal cells.

  14. Local effects and mechanism of absorption of iron preparations administered intramuscularly

    PubMed Central

    Beresford, C. R.; Golberg, L.; Smith, J. P.

    1957-01-01

    An attempt has been made to correlate factors involved in the absorption of iron-polysaccharide complexes administered intramuscularly. Different complexes varied greatly in degree of retention in muscle and in diffusibility in agar; these two characteristics were not closely related. The local changes in the muscle produced by the iron complexes consisted of an acute inflammatory reaction at the site of injection, with degenerative changes. Subsequent regeneration was rapid and complete. The major proportion of the absorption occurred during the initial 72 hr. and appeared to be mediated partly by the inflammatory reaction evoked, with enhancement of lymphatic transport of the iron complex. Rapid fixation by tissue macrophages impeded absorption and, with some complexes, this factor may make much of the injection inaccessible. ImagesFIG. 4FIG. 5 PMID:13413161

  15. Study of the analytical methods for iron determination in complex organic liquids by atomic absorption spectrometry

    SciTech Connect

    Torre, M.; Gonzalez, M.C.; Jimenez, O.; Rodriquez, A.R. )

    1990-01-01

    In the determination of iron in complex organic liquids by atomic absorption spectrometry (A.A.S.), methods of sample preparation, such as dilution with an organic solvent and sample pretreatment to destroy organic material, are investigated. Moreover, methods of analysis using calibration curve and standard additions are presented. The possible cause of error associated with iron determination in organic samples by flame (F-A.A.S.) and graphite furnace (GF-A.A.S.) atomic absorption spectrometry are discussed. From all of these studies, the use of graphite furnace atomic absorption spectrometry after sample dilution with methyl isobutyl ketone, and the use of the method of standard additions are advised for iron determination.

  16. Identification of the key excreted molecule by Lactobacillus fermentum related to host iron absorption.

    PubMed

    González, Ana; Gálvez, Natividad; Martín, Jesús; Reyes, Fernando; Pérez-Victoria, Ignacio; Dominguez-Vera, Jose M

    2017-08-01

    We have taken a vital step towards understanding why probiotic bacteria increase iron absorption in the gastrointestinal tract. We show here that Lactobacillus fermentum, one of the main probiotics of the microbiota, exhibits an extraordinary ferric-reducing activity. This activity is predominantly due to an excreted molecule: p-hydroxyphenyllactic acid (HPLA). Reduction of Fe(III) to Fe(II) is essential for iron absorption in the gastrointestinal tract. By reducing Fe(III), HPLA boosts Fe(II) absorption through the DMT1 channels of enterocytes. An in vitro experiment tested and confirmed this hypothesis. This discovery opens new avenues for the treatment of iron deficiency in humans, one of the most common and widespread nutritional disorders in the world.

  17. Effects of the pyrones, maltol and ethyl maltol, on iron absorption from the rat small intestine.

    PubMed

    Barrand, M A; Callingham, B A; Hider, R C

    1987-03-01

    The pyrones, 3-hydroxy-2-methyl-4-pyrone (maltol) and 3-hydroxy-2-ethyl-4-pyrone (ethyl maltol) chelate iron with a high affinity and selectivity. The resulting 1:3 (metal-ligand) complexes, being neutral, are able to partition readily across cell membranes and thus may facilitate iron transport across the intestinal wall. Absorption of radioactive iron (59Fe) in the presence of these pyrones was investigated in male rats 1, 2, 4 and 6 h after intraduodenal administration of a 7 micrograms dose and compared with that of 59Fe given as the sulphate, gluconate, fumarate or complexed to EDTA. Total body absorption and distribution were calculated from the 59Fe content of various tissue samples. With all the iron preparations used, blood levels of 59Fe were highest 1 h after injection whilst the 59Fe content at the major site of deposition, i.e. the bone marrow, increased up to 6 h. No 59Fe was found in the urine. Total body absorption of 59Fe was significantly higher from the pyrones than from the other four preparations. Over the dose range 0.7-700 micrograms, the proportion of 59Fe absorbed from both iron maltol and iron sulphate decreased with increasing dose. Enhanced 59Fe uptake from maltol was evident at 0.7-70 micrograms but not at 700 micrograms suggesting that use of these pyrones will not result in iron overload. Absorption of 59Fe given into the stomach was slower in onset but was sustained longer presumably via a steady delivery of iron to the duodenum from the gastric reservoir.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Detection, identification and mapping of iron anomalies in brain tissue using X-ray absorption spectroscopy

    SciTech Connect

    Mikhaylova, A.; Davidson, M.; Toastmann, H.; Channell, J.E.T.; Guyodo, Y.; Batich, C.; Dobson, J.

    2008-06-16

    This work describes a novel method for the detection, identification and mapping of anomalous iron compounds in mammalian brain tissue using X-ray absorption spectroscopy. We have located and identified individual iron anomalies in an avian tissue model associated with ferritin, biogenic magnetite and haemoglobin with a pixel resolution of less than 5 {micro}m. This technique represents a breakthrough in the study of both intra- and extra-cellular iron compounds in brain tissue. The potential for high-resolution iron mapping using microfocused X-ray beams has direct application to investigations of the location and structural form of iron compounds associated with human neurodegenerative disorders - a problem which has vexed researchers for 50 years.

  19. Studies on different iron source absorption by in situ ligated intestinal loops of broilers.

    PubMed

    Jia, Y F; Jiang, M M; Sun, J; Shi, R B; Liu, D S

    2015-02-01

    The objective of this study was to investigate the iron source absorption in the small intestine of broiler. In situ ligated intestinal loops of 70 birds were poured into one of seven solutions, including inorganic iron (FeSO4, Fe2(SO4)3), organic Fe glycine chelate (Fe-Gly(II), Fe-Gly(III)), the mixtures (FeSO4 with glycine (Fe+Gly(II)), Fe2(SO4)3 with glycine (Fe+Gly(III)), and no Fe source (control). The total volume of 3-mL solution (containing 1 mg of elemental Fe) was injected into intestinal loops, and then 120-min incubation was performed. Compared with inorganic iron groups, in which higher FeSO4 absorption than Fe2(SO4)3 was observed, supplementation with organic Fe glycine chelate significantly increased the Fe concentration in the duodenum and jejunum (P < 0.05), however, decreased DMT1 and DcytB messenger RNA (mRNA) levels (P < 0.05). Organic Fe glycine chelate (Fe-Gly(II), Fe-Gly(III)) increased serum iron concentration (SI), compared with inorganic 3 valence iron groups (Fe2(SO4)3 and Fe+Gly(III)) (P < 0.05); moreover, lower TIBC value was observed for the chelate (P < 0.05); however, mixture of inorganic iron and glycine did not have a positive role at DMT1 and DcytB mRNA levels, SI and Fe concentrations in the small intestine. Those results indicated that the absorption of organic Fe glycine chelate was more effective than that of inorganic Fe, and the orders of iron absorption in the small intestine were: Fe-Gly(II), Fe-Gly(III) > FeSO4, Fe+Gly(II) > Fe2(SO4)3, Fe+Gly(III). Additionally, the simple mixture of inorganic iron and glycine could not increase Fe absorption, and the duodenum was the main site of Fe absorption in the intestines of broilers and the ileum absorbed iron rarely.

  20. Iron K-edge X-ray absorption spectroscopy of the iron-molybdenum cofactor of nitrogenase from Klebsiella pneumoniae.

    PubMed Central

    Arber, J M; Flood, A C; Garner, C D; Gormal, C A; Hasnain, S S; Smith, B E

    1988-01-01

    Iron K-edge X-ray absorption data for the iron-molybdenum cofactor ('FeMoco') from Klebsiella pneumoniae reported here provide the first evidence for long-range structural order in the cofactor [Fe...Fe(Mo) = 0.368 nm in addition to Fe...S = 0.22 nm and Fe...Fe(Mo) = 0.27 nm] and, in contrast with previously published data [Antonio, Teo, Orme-Johnson, Nelson, Groh, Lindahl, Kauzlarich & Averill (1982) J. Am. Chem. Soc. 104, 4703-4705], indicate that most of the iron centres are not co-ordinated to light (oxygen, nitrogen) atoms. This demonstrates that presently available chemical models for FeMoco are inadequate. PMID:3046607

  1. Egg yolk protein and egg yolk phosvitin inhibit calcium, magnesium, and iron absorptions in rats.

    PubMed

    Ishikawa, S-I; Tamaki, S; Arihara, K; Itoh, M

    2007-08-01

    Egg yolk decreases the absorption of iron. The effects of egg yolk protein and egg yolk phosvitin on the absorption of calcium, magnesium, and iron were investigated by in vivo studies. Male Wistar rats were fed purified diets containing casein, soy protein, or egg yolk protein for 14 d. The apparent absorptions of calcium, magnesium, and iron in the rats fed the yolk protein-based diet were lower than those in rats fed the casein- and soy protein-based diets. The apparent phosphorus absorption and the apparent protein digestibility in the yolk protein group were lower than those in the casein and soy protein groups. In the feces of the yolk protein group, serine comprised more than 30% of the amino acids. The addition of egg yolk phosvitin to the casein diets at levels of 1% and 2% (w/w) produced effects on calcium and magnesium absorptions similar to those produced by the diet containing yolk protein. The tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern suggested that phosphopeptide fragments having molecular masses of 28, 22, and 15 kDa were evident in the contents of the small intestine of the rats fed phosvitin diets. These results indicate that yolk protein, when compared with casein and soy protein, decreases calcium and magnesium absorption via the resistance of phosvitin to proteolytic action.

  2. Anemia and iron deficiency in gastrointestinal and liver conditions

    PubMed Central

    Stein, Jürgen; Connor, Susan; Virgin, Garth; Ong, David Eng Hui; Pereyra, Lisandro

    2016-01-01

    Iron deficiency anemia (IDA) is associated with a number of pathological gastrointestinal conditions other than inflammatory bowel disease, and also with liver disorders. Different factors such as chronic bleeding, malabsorption and inflammation may contribute to IDA. Although patients with symptoms of anemia are frequently referred to gastroenterologists, the approach to diagnosis and selection of treatment as well as follow-up measures is not standardized and suboptimal. Iron deficiency, even without anemia, can substantially impact physical and cognitive function and reduce quality of life. Therefore, regular iron status assessment and awareness of the clinical consequences of impaired iron status are critical. While the range of options for treatment of IDA is increasing due to the availability of effective and well-tolerated parenteral iron preparations, a comprehensive overview of IDA and its therapy in patients with gastrointestinal conditions is currently lacking. Furthermore, definitions and assessment of iron status lack harmonization and there is a paucity of expert guidelines on this topic. This review summarizes current thinking concerning IDA as a common co-morbidity in specific gastrointestinal and liver disorders, and thus encourages a more unified treatment approach to anemia and iron deficiency, while offering gastroenterologists guidance on treatment options for IDA in everyday clinical practice. PMID:27672287

  3. Probing iron at Super-Earth core conditions

    SciTech Connect

    Amadou, N.; Brambrink, E.; Vinci, T.; Benuzzi-Mounaix, A.; Huser, G.; Brygoo, S.; Morard, G.; Guyot, F.; Resseguier, T. de; Mazevet, S.; Miyanishi, K.; Ozaki, N.; Kodama, R.; Henry, O.; Raffestin, D.; Boehly, T.; and others

    2015-02-15

    In this paper, we report on the quasi-isentropic compression of an iron sample using ramp shaped laser irradiation. This technique allows us to quasi-isentropically compress iron up to 700 GPa and 8500 K. To our knowledge, these data are the highest pressures reached on iron in off-Hugoniot conditions and the closest to the thermodynamic states thought to exist in Earth-like planetary cores. The experiment was performed on the Ligne d'Intégration laser facility at CESTA, Bordeaux, France.

  4. Proanthocyanidins inhibit iron absorption from soybean (Glycine max) seed ferritin in rats with iron deficiency anemia.

    PubMed

    Yun, Shaojun; Zhang, Tuo; Li, Meiliang; Chen, Bin; Zhao, Guanghua

    2011-09-01

    The objective of this study was to evaluate the effect of proanthocyanidins (PAs) on iron uptake from soybean seed ferritin (SSF) crude by rats with iron deficiency anemia (IDA) for the first time. Six groups of Sprague-Dawley (SD) rats (n = 10) were used, which contain (1) SSF crude group; (2) SSF crude + PAs group; (3) PAs group; (4) FeSO(4) group; (5) iron deficiency control group; and (6) control group. The bioavailability of iron was examined by measuring hemoglobin (Hb) concentration value, red blood cell (RBC) numbers, and serum iron stores. After 8 weeks, Hb concentration was almost recovered to the normal level upon feeding SSF crude or FeSO(4) to rats. In contrast, Hb concentration was recovered to less extent when SSF crude plus PAs was used instead of SSF crude alone (P < 0.05). A similar profile was observed with these three sample groups when serum iron and RBC were used as parameters. All rats in PAs group died at the 8th week. Taken together, all these results demonstrated that PAs inhibited iron uptake of rats from SSF, and are toxic for rats with IDA.

  5. Mathematical model of zinc absorption: effects of dietary calcium, protein and iron on zinc absorption.

    PubMed

    Miller, Leland V; Krebs, Nancy F; Hambidge, K Michael

    2013-02-28

    A previously described mathematical model of Zn absorption as a function of total daily dietary Zn and phytate was fitted to data from studies in which dietary Ca, Fe and protein were also measured. An analysis of regression residuals indicated statistically significant positive relationships between the residuals and Ca, Fe and protein, suggesting that the presence of any of these dietary components enhances Zn absorption. Based on the hypotheses that (1) Ca and Fe both promote Zn absorption by binding with phytate and thereby making it unavailable for binding Zn and (2) protein enhances the availability of Zn for transporter binding, the model was modified to incorporate these effects. The new model of Zn absorption as a function of dietary Zn, phytate, Ca, Fe and protein was then fitted to the data. The proportion of variation in absorbed Zn explained by the new model was 0·88, an increase from 0·82 with the original model. A reduced version of the model without Fe produced an equally good fit to the data and an improved value for the model selection criterion, demonstrating that when dietary Ca and protein are controlled for, there is no evidence that dietary Fe influences Zn absorption. Regression residuals and testing with additional data supported the validity of the new model. It was concluded that dietary Ca and protein modestly enhanced Zn absorption and Fe had no statistically discernable effect. Furthermore, the model provides a meaningful foundation for efforts to model nutrient interactions in mineral absorption.

  6. Absorption of zinc and iron by rats fed meals containing sorghum food products

    SciTech Connect

    Stuart, S.M.A.; Johnson, P.E.; Hamaker, B.; Kirleis, A.

    1986-03-05

    Zinc and iron absorption from freeze-dried traditionally-prepared sorghum food products was studied in rats. After a period of marginal zinc or iron depletion, rats were fed test meals containing 1 of 4 sorghum foods cooked maize gruel or an inorganic mineral each of which was extrinsically labeled with either /sup 65/Zn or /sup 59/Fe before being added to the diets. Absorption was determined by whole body percent retention of the initial radioisotope dose over a period of 19 days. Iron was highly available from all products tested (75-83%) with no significant differences in absorption among groups (p>0.05). Zinc from fermented Aceta (97%) was more available than that from the other sorghum products (69-78%) or maize gruel (76%). Zinc from acid To (78%) and Aceta (97%) was as available as that from zinc oxide in the control diet (93%) (p>0.05). There were no significant differences in zinc absorption among groups fed Acid To (78%), neutral To (76), alkali To (69%) or maize gruel (76%) (p<0.05). Phytate in the fermented Aceta was 33% lower than in the other sorghum foods. Iron and zinc were highly available from all sorghum foods. Reduction phytate by fermentation increased Zn availability.

  7. Modeling of the Temperature Effect on Oxygen Absorption by Iron-Based Oxygen Scavengers.

    PubMed

    Polyakov, Vladimir A; Miltz, Joseph

    2016-01-01

    A new engineering-oriented model for prediction of the effect of temperature on the kinetics of oxygen absorption by iron-based oxygen scavengers (IOSs) was developed. The model is based on the physicochemical mechanism of the O2 scavenging process by the active component of the IOS (iron powder). The conclusions of this study are: (1) the iron deposits formed on the iron particles are composed of 2 different layers: an inner layer of Fe3 O4 and an outer layer of FeOOH that vanishes with the depletion of oxygen. (2) The model considers the chemical processes in the heterogeneous closed system "Fe-H2 O-NaCl-O2 " and describes the kinetics of oxygen absorption by the powder, depending on the characteristics of the system. (3) The nonlinear ordinary differential equation (ODE) of the O2 absorption kinetics was derived and a simple approximate solution to this ODE was obtained theoretically that is similar to the empirical exponential formula published in the relevant literature. (4) The temperature dependence of the oxygen absorption rate is more complicated than that described by the Arrhenius equation.

  8. The Effect of Plant Proteins Derived from Cereals and Legumes on Heme Iron Absorption.

    PubMed

    Weinborn, Valerie; Pizarro, Fernando; Olivares, Manuel; Brito, Alex; Arredondo, Miguel; Flores, Sebastián; Valenzuela, Carolina

    2015-10-30

    The aim of this study is to determine the effect of proteins from cereals and legumes on heme iron (Fe) absorption. The absorption of heme Fe without its native globin was measured. Thirty adult females participated in two experimental studies (15 per study). Study I focused on the effects of cereal proteins (zein, gliadin and glutelin) and study II on the effects of legume proteins (soy, pea and lentil) on heme Fe absorption. When heme was given alone (as a control), study I and II yielded 6.2% and 11.0% heme absorption (p > 0.05). In study I, heme Fe absorption was 7.2%, 7.5% and 5.9% when zein, gliadin and glutelin were added, respectively. From this, it was concluded that cereal proteins did not affect heme Fe absorption. In study II, heme Fe absorption was 7.3%, 8.1% and 9.1% with the addition of soy, pea and lentil proteins, respectively. Only soy proteins decreased heme Fe absorption (p < 0.05). These results suggest that with the exception of soy proteins, which decreased absorption, proteins derived from cereals and legumes do not affect heme Fe absorption.

  9. Iron and phosphorus speciation in Fe-conditioned membrane bioreactor activated sludge.

    PubMed

    Wu, Hao; Ikeda-Ohno, Atsushi; Wang, Yuan; Waite, T David

    2015-06-01

    Iron dosing of membrane bioreactors (MBRs) is widely used as a means of meeting effluent phosphorus targets but there is limited understanding of the nature of iron and phosphorus-containing solids that are formed within the bioreactor (an important issue in view of the increasing interest in recovering phosphorus from wastewaters). Of particular challenge is the complexity of the MBR system and the variety of reactions that can occur on addition of iron salts to a membrane bioreactor. In this study, the performances of bench scale MBRs with dosing of either ferrous or ferric salts were monitored for a period of four months. The distributions of Fe and P-species in the Fe-conditioned sludges were determined using X-ray absorption spectroscopy (XAS) at the Fe K-edge and the P K-edge. Regardless of whether iron was dosed to the anoxic or aerobic chambers and regardless of whether ferrous (Fe(II)) or ferric (Fe(III)) iron was dosed, iron present in the minerals in the conditioned sludges was consistently in the +III oxidation state. Fitting of the Fe K-edge EXAFS spectra revealed that an Fe(III)-phosphate species was the main Fe species present in all cases with the remaining fraction dominated by lepidocrocite (γ-FeOOH) in the Fe(II)-dosed case and ferrihydrite (am-FeOOH) in the Fe(III)-dosed case. Approximately half the phosphorus in the activated sludge samples was present as a distinct Fe-PO4 mineral (such as strengite or an amorphous ferric hydroxyl phosphate analogue of strengite) and half as phosphorus adsorbed to an iron oxyhydroxide mineral phase indicating that both co-precipitation and adsorption of phosphorus by iron contribute to removal of phosphorus from the MBR supernatant.

  10. Intestinal DMT1 is critical for iron absorption in the mouse but is not required for the absorption of copper or manganese.

    PubMed

    Shawki, Ali; Anthony, Sarah R; Nose, Yasuhiro; Engevik, Melinda A; Niespodzany, Eric J; Barrientos, Tomasa; Öhrvik, Helena; Worrell, Roger T; Thiele, Dennis J; Mackenzie, Bryan

    2015-10-15

    Divalent metal-ion transporter-1 (DMT1) is a widely expressed iron-preferring membrane-transport protein that serves a critical role in erythroid iron utilization. We have investigated its role in intestinal metal absorption by studying a mouse model lacking intestinal DMT1 (i.e., DMT1(int/int)). DMT1(int/int) mice exhibited a profound hypochromic-microcytic anemia, splenomegaly, and cardiomegaly. That the anemia was due to iron deficiency was demonstrated by the following observations in DMT1(int/int) mice: 1) blood iron and tissue nonheme-iron stores were depleted; 2) mRNA expression of liver hepcidin (Hamp1) was depressed; and 3) intraperitoneal iron injection corrected the anemia, and reversed the changes in blood iron, nonheme-iron stores, and hepcidin expression levels. We observed decreased total iron content in multiple tissues from DMT1(int/int) mice compared with DMT1(+/+) mice but no meaningful change in copper, manganese, or zinc. DMT1(int/int) mice absorbed (64)Cu and (54)Mn from an intragastric dose to the same extent as did DMT1(+/+) mice but the absorption of (59)Fe was virtually abolished in DMT1(int/int) mice. This study reveals a critical function for DMT1 in intestinal nonheme-iron absorption for normal growth and development. Further, this work demonstrates that intestinal DMT1 is not required for the intestinal transport of copper, manganese, or zinc.

  11. High-resolution X-ray absorption spectroscopy of iron carbonyl complexes.

    PubMed

    Atkins, Andrew J; Bauer, Matthias; Jacob, Christoph R

    2015-06-07

    We apply high-energy-resolution fluorescence-detected (HERFD) X-ray absorption near-edge spectroscopy (XANES) to study iron carbonyl complexes. Mono-, bi-, and tri-nuclear carbonyl complexes and pure carbonyl complexes as well as carbonyl complexes containing hydrocarbon ligands are considered. The HERFD-XANES spectra reveal multiple pre-edge peaks with individual signatures for each complex, which could not be detected previously with conventional XANES spectroscopy. These peaks are assigned and analysed with the help of TD-DFT calculations. We demonstrate that the pre-edge peaks can be used to distinguish the different types of iron-iron interactions in carbonyl complexes. This opens up new possibilities for applying HERFD-XANES spectroscopy to probe the electronic structure of iron catalysts.

  12. Iron absorption differs in piglets fed extrinsically and intrinsically 59Fe-labeled sow's milk.

    PubMed

    Gislason, J; Jones, B; Lönnerdal, B; Hambraeus, L

    1992-06-01

    Iron bioavailability from species-specific milk is assumed to be high for the offspring, possibly due to species-specific iron-binding proteins in the milk. To assess this bioavailability using radioisotopes, the validity of extrinsic labeling technique needs to be proven. Using the suckling piglet as an animal model, we have compared iron bioavailability from sow's milk labeled extrinsically and intrinsically. During intrinsic labeling transfer into milk of 59Fe given intramuscularly was slow and was found to be at maximum 14 h post-injection. Recovery of isotope in the milk was only 0.00014%. Extrinsic and intrinsic labels were distributed differently among milk fractions; intrinsic iron bound primarily to the fat fraction but the extrinsic iron bound primarily to the casein fraction. Iron retention from intrinsically labeled milk was considerably higher than from extrinsically labeled milk. These results show that the extrinsic tag method is not valid for studies on iron absorption from sow's milk and suggest that the situation may be the same for human milk.

  13. Ferroportin mediates the intestinal absorption of iron from a nanoparticulate ferritin core mimetic in mice.

    PubMed

    Aslam, Mohamad F; Frazer, David M; Faria, Nuno; Bruggraber, Sylvaine F A; Wilkins, Sarah J; Mirciov, Cornel; Powell, Jonathan J; Anderson, Greg J; Pereira, Dora I A

    2014-08-01

    The ferritin core is composed of fine nanoparticulate Fe(3+) oxohydroxide, and we have developed a synthetic mimetic, nanoparticulate Fe(3+) polyoxohydroxide (nanoFe(3+)). The aim of this study was to determine how dietary iron derived in this fashion is absorbed in the duodenum. Following a 4 wk run-in on an Fe-deficient diet, mice with intestinal-specific disruption of the Fpn-1 gene (Fpn-KO), or littermate wild-type (WT) controls, were supplemented with Fe(2+) sulfate (FeSO4), nanoFe(3+), or no added Fe for a further 4 wk. A control group was Fe sufficient throughout. Direct intestinal absorption of nanoFe(3+) was investigated using isolated duodenal loops. Our data show that FeSO4 and nanoFe(3+) are equally bioavailable in WT mice, and at wk 8 the mean ± SEM hemoglobin increase was 18 ± 7 g/L in the FeSO4 group and 30 ± 5 g/L in the nanoFe(3+) group. Oral iron failed to be utilized by Fpn-KO mice and was retained in enterocytes, irrespective of the iron source. In summary, although nanoFe(3+) is taken up directly by the duodenum its homeostasis is under the normal regulatory control of dietary iron absorption, namely via ferroportin-dependent efflux from enterocytes, and thus offers potential as a novel oral iron supplement.

  14. The determination of aluminum, copper, iron, and lead in glycol formulations by atomic absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Initial screening tests and the results obtained in developing procedures to determine Al, Cu, Fe, and Pb in glycol formulations are described. Atomic absorption completion was selected for Cu, Fe and Pb, and after comparison with emission spectroscopy, was selected for Al also. Before completion, carbon, iron, and lead are extracted with diethyl dithio carbamate (DDC) into methyl isobutyl ketone (MIBK). Aluminum was also extracted into MIBK using 8-hydroxyquinoline as a chelating agent. As little as 0.02 mg/l carbon and 0.06 mg/l lead or iron may be determined in glycol formulations. As little as 0.3 mg/l aluminum may be determined.

  15. Absorption and adsorption chillers applied to air conditioning systems

    NASA Astrophysics Data System (ADS)

    Kuczyńska, Agnieszka; Szaflik, Władysław

    2010-07-01

    This work presents an application possibility of sorption refrigerators driven by low temperature fluid for air conditioning of buildings. Thermodynamic models were formulated and absorption LiBr-water chiller with 10 kW cooling power as well as adsorption chiller with silica gel bed were investigated. Both of them are using water for desorption process with temperature Tdes = 80 °C. Coefficient of performance (COP) for both cooling cycles was analyzed in the same conditions of the driving heat source, cooling water Tc = 25 °C and temperature in evaporator Tevap = 5 °C. In this study, the computer software EES was used to investigate the performance of absorption heat pump system and its behaviour in configuration with geothermal heat source.

  16. The effect of haem biosynthesis inhibitors and inducers on intestinal iron absorption and liver haem biosynthetic enzyme activities

    SciTech Connect

    Laftah, A.H.; Simpson, R.J. Peters, T.J.; Raja, K.B.

    2008-06-15

    The relation between haem biosynthesis and intestinal iron absorption is not well understood, we therefore investigated the effect of compounds that alter haem metabolism on duodenal iron absorption. CD1 mice were treated with either an inhibitor (succinyl acetone (SA)) or stimulator (2-allyl-2-isopropylacetamide (AIA)) of haem biosynthesis. 5-Aminolaevulinic acid (ALA) dehydratase and urinary ALA and porphobilinogen (PBG) levels, were determined. Intestinal iron absorption was assayed with in vivo and in vitro techniques. Liver hepcidin (Hamp1) and duodenal iron transporter mRNA levels were measured using RT-PCR. AIA caused increased hepatic ALA synthase (1.6-fold) and ALA dehydratase (1.4-fold, both p < 0.005) activities and increased urinary ALA and PBG excretion (2.1- and 1.4-fold, p < 0.005, p < 0.05, respectively). In vivo intestinal iron absorption was reduced to 49% of control (p < 0.005). Mice treated with SA showed decreased urinary ALA and PBG levels (75 and 55% control, both p < 0.005) and reductions in both ALA synthase and ALA dehydratase activities (77 and 56% control, p < 0.05, p < 0.005, respectively) in the liver. Liver and duodenal haem and cytochrome oxidase levels were not significantly decreased. Iron absorption was enhanced (1.26-fold, p < 0.05) and hepatic Hamp1 mRNA was reduced (53% of control, p < 0.05). In vitro duodenal iron uptake after mice were injected with SA also demonstrated an increase in Fe(III) reduction and uptake (1.27- and 1.41-fold, p < 0.01 respectively). Simultaneous injections of SA and ALA blocked the enhancing effect on iron absorption seen with SA alone. We conclude that alterations in haem biosynthesis can influence iron absorption and in particular, the intermediate ALA seems to be an inhibitor of iron absorption.

  17. Dephytinisation with intrinsic wheat phytase and iron fortification significantly increase iron absorption from fonio (Digitaria exilis) meals in West African women.

    PubMed

    Koréissi-Dembélé, Yara; Fanou-Fogny, Nadia; Moretti, Diego; Schuth, Stephan; Dossa, Romain A M; Egli, Ines; Zimmermann, Michael B; Brouwer, Inge D

    2013-01-01

    Low iron and high phytic acid content make fonio based meals a poor source of bioavailable iron. Phytic acid degradation in fonio porridge using whole grain cereals as phytase source and effect on iron bioavailability when added to iron fortified fonio meals were investigated. Grains, nuts and seeds collected in Mali markets were screened for phytic acid and phytase activity. We performed an iron absorption study in Beninese women (n = 16), using non-dephytinised fonio porridge (FFP) and dephytinised fonio porridge (FWFP; 75% fonio-25% wheat), each fortified with (57)Fe or (58)Fe labeled FeSO4. Iron absorption was quantified by measuring the erythrocyte incorporation of stable iron isotopes. Phytic acid varied from 0.39 (bambara nut) to 4.26 g/100 g DM (pumpkin seed), with oilseeds values higher than grains and nuts. Phytase activity ranged from 0.17±1.61 (fonio) to 2.9±1.3 phytase unit (PU) per g (whole wheat). Phytic acid was almost completely degraded in FWFP after 60 min of incubation (pH≈5.0, 50°C). Phytate∶iron molar ratios decreased from 23.7∶1 in FFP to 2.7∶1 in FWFP. Iron fortification further reduced phytate∶iron molar ratio to 1.9∶1 in FFP and 0.3∶1 in FWFP, respectively. Geometric mean (95% CI) iron absorption significantly increased from 2.6% (0.8-7.8) in FFP to 8.3% (3.8-17.9) in FWFP (P<0.0001). Dephytinisation of fonio porridge with intrinsic wheat phytase increased fractional iron absorption 3.2 times, suggesting it could be a possible strategy to decrease PA in cereal-based porridges.

  18. Dephytinisation with Intrinsic Wheat Phytase and Iron Fortification Significantly Increase Iron Absorption from Fonio (Digitaria exilis) Meals in West African Women

    PubMed Central

    Moretti, Diego; Schuth, Stephan; Egli, Ines; Zimmermann, Michael B.; Brouwer, Inge D.

    2013-01-01

    Low iron and high phytic acid content make fonio based meals a poor source of bioavailable iron. Phytic acid degradation in fonio porridge using whole grain cereals as phytase source and effect on iron bioavailability when added to iron fortified fonio meals were investigated. Grains, nuts and seeds collected in Mali markets were screened for phytic acid and phytase activity. We performed an iron absorption study in Beninese women (n = 16), using non-dephytinised fonio porridge (FFP) and dephytinised fonio porridge (FWFP; 75% fonio-25% wheat), each fortified with 57Fe or 58Fe labeled FeSO4. Iron absorption was quantified by measuring the erythrocyte incorporation of stable iron isotopes. Phytic acid varied from 0.39 (bambara nut) to 4.26 g/100 g DM (pumpkin seed), with oilseeds values higher than grains and nuts. Phytase activity ranged from 0.17±1.61 (fonio) to 2.9±1.3 phytase unit (PU) per g (whole wheat). Phytic acid was almost completely degraded in FWFP after 60 min of incubation (pH≈5.0, 50°C). Phytate∶iron molar ratios decreased from 23.7∶1 in FFP to 2.7∶1 in FWFP. Iron fortification further reduced phytate∶iron molar ratio to 1.9∶1 in FFP and 0.3∶1 in FWFP, respectively. Geometric mean (95% CI) iron absorption significantly increased from 2.6% (0.8–7.8) in FFP to 8.3% (3.8–17.9) in FWFP (P<0.0001). Dephytinisation of fonio porridge with intrinsic wheat phytase increased fractional iron absorption 3.2 times, suggesting it could be a possible strategy to decrease PA in cereal-based porridges. PMID:24124445

  19. Flower-like carbonyl iron powder modified by nanoflakes: Preparation and microwave absorption properties

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Yang, Pingan; Fu, Jie; Liu, Shuzhi

    2015-04-01

    In this paper, flower-like carbonyl iron powder (CIP) is prepared under normal temperature and pressure by a simple method of chemical reduction. This flower-like morphology is conducive to forming discontinuous network, enhancing diffuse scattering of the incident microwave and polarizing more interface charges. Those are all in favor of electromagnetic wave penetration and absorption. The test results show that compared with the unmodified CIP, the electromagnetic wave absorbing property of flower-like CIP is significantly improved in X-band. It is concluded that this research paves a way to enhance the microwave absorption properties of spherical metal particles.

  20. Cucumis sativus secretes 4'-ketoriboflavin under iron-deficient conditions.

    PubMed

    Satoh, Junichi; Koshino, Hiroyuki; Sekino, Kouta; Ito, Shinsaku; Katsuta, Ryo; Takeda, Kouji; Yoshimura, Etsuro; Shinmachi, Fumie; Kawasaki, Shinji; Niimura, Youichi; Nukada, Tomoo

    2016-01-01

    A new compound in cucumber, Cucumis sativus, nutrient solution that appears under iron-deficient conditions, but not under ordinary culture conditions, has been revealed by HPLC analysis. The chemical structure of this compound was identified using LC-MS and NMR techniques as that of 4'-ketoriboflavin. This is the first report to show that 4'-ketoriboflavin can be found in metabolites from organisms.

  1. Acute Copper and Ascorbic Acid Supplementation Inhibits Non-heme Iron Absorption in Humans.

    PubMed

    Olivares, Manuel; Figueroa, Constanza; Pizarro, Fernando

    2016-08-01

    The objective of the study is to determine the effect of copper (Cu) plus the reducing agent ascorbic acid (AA) on the absorption of non-heme iron (Fe). Experimental study with block design in which each subject was his own control. After signing an informed consent, 14 adult women using an effective method of contraception and negative pregnancy test received 0.5 mg Fe, as ferrous sulfate, alone or with Cu, as copper sulfate, plus ascorbic acid (AA/Cu 2/1 molar ratio) at 4/1; 6/1 and 8/1 Cu/Fe molar ratios as an aqueous solution on days 1, 2, 14, and 15 of the study. Fe absorption was assessed by erythrocyte incorporation of iron radioisotopes (55)Fe and (59)Fe. Geometric mean (range ± SD) absorption of Fe at 4/1 and 6/1 Cu/Fe molar ratios (and AA/Cu 2/1 molar ratio) and Fe alone was 57.4 % (35.7-92.1 %), 64.2 % (45.8-89.9 %), and 38.8 % (20.4-73.8 %), respectively (ANOVA for repeated measures p < 0.001; post hoc test Scheffé, p < 0.05). This is attributable to the enhancing effect of AA on non-heme Fe absorption; however, Fe absorption at Cu/Fe 8/1 molar ratio was 47.3 % (27.7-80.8) (p = NS compared with Fe alone). It was expected that Fe absorption would have been equal or greater than at 4/1 and 6/1 molar ratios. Copper in the presence of ascorbic acid inhibits non-heme Fe absorption at Cu/Fe 8/1 molar ratio.

  2. Colorimetric and atomic absorption spectrometric determination of mucolytic drug ambroxol through ion-pair formation with iron and thiocyanate.

    PubMed

    Levent, Abdulkadir; Sentürk, Zühre

    2010-09-01

    Colorimetric and atomic absorption spectrometric methods have been developed for the determination of mucolytic drug Ambroxol. These procedures depend upon the reaction of iron(III) metal ion with the drug in the presence of thiocyanate ion to form stable ion-pair complex which extractable chloroform. The red-coloured complex was determined either colorimetrically at 510 nm or by indirect atomic absorption spectrometry (AAS) via the determination of the iron content in the formed complex. The optimum experimental conditions for pH, concentrations of Fe(3+) and SCN(-), shaking time, phase ratio, and the number of extractions were determined. Under the proposed conditions, linearity was obeyed in the concentration ranges 4.1x10(-6) - 5.7x10(-5) M (1.7-23.6 µg mL(-1)) using both methods, with detection limits of 4.6x10(-7) M (0.19 µg mL(-1)) for colorimetry and 1.1x10(-6) M (0.46 µg mL(-1)) for AAS. The proposed methods were applied for the determination of Ambroxol in tablet dosage forms. The results obtained were statistically analyzed and compared with those obtained by applying the high-performance liquid chromatographic method with diode-array detection.

  3. An evaluation of in vitro intestinal absorption of iron, calcium and potassium in chickens receiving gold nanoparticles.

    PubMed

    Sembratowicz, I; Ognik, K; Stępniowska, A

    2016-08-01

    This study evaluated the effect of oral administration of colloidal gold nanoparticles on accumulation of gold in the small intestine and intestinal absorption of iron, calcium and potassium under in vitro conditions. The gold nanoparticles are non-ionic, nanocrystalline, chemically pure particles 5 nm in size, produced in a physical process. In total, 126 one day-old Ross 308 chicks were assigned to 7 experimental groups of 18 birds each (3 replications of 6 individuals each). The control group (G-C) did not receive gold nanoparticles. Groups: Au-5(7), Au-10(7) and Au-15(7) received gold nanoparticles in their drinking water in the amounts of 5 mg l(-1) for group Au-5(7), 10 mg l(-1) for group Au-10(7) and 15 mg l(-1) for group Au-15(7) in 8-14, 22-28 and 36-42 d of life. The birds in groups Au-5(3), Au-10(3) and Au-15(3) received gold nanoparticles in the same amounts, but only in 8-10, 22-24 and 36-38 d of life. The study revealed that nanogold supplied via ingestion leads to dose- and time-dependent accumulation of gold in the intestinal walls. Nanogold present in the jejunum has a negative impact on the absorption of calcium, iron and potassium under in vitro conditions.

  4. Modelling iron clay interactions in deep geological disposal conditions

    NASA Astrophysics Data System (ADS)

    Bildstein, O.; Trotignon, L.; Perronnet, M.; Jullien, M.

    In the context of deep geological disposal of high level radioactive wastes, the interactions between iron and clay-rich materials may lead to adverse transformations of clay minerals with a potential loss of confining properties such as swelling and capacity to exchange cations. Such transformations have been experimentally observed at temperatures starting at ca. 80 °C, where smectites contained in a mixture of bentonite and iron powder are transformed into iron-rich serpentine-type minerals. The reaction-transport code CRUNCH is used to investigate the iron-clay interactions at 50 °C over a period of 10,000 years, which are the conditions considered here to represent the mean temperature value and the expected timescale for the corrosion stage. The aim is to predict the nature and quantity of corrosion product, calculate the chemistry of water (essentially the pH) and the mineralogical transformation in the system containing the canister, an optional engineered barrier (bentonite) and the host-rock (argillite). The results of the calculations show that at the interface with the canister, where steel corrosion occurs, the iron is partly immobilized by the precipitation of iron oxides (essentially magnetite) and small amounts of siderite. The pH stabilizes at high values, between 10 and 11, at this location. In the bentonite or the argillite in contact with the container, the primary clay minerals are destabilized and iron-rich serpentine-like minerals precipitate as observed in the experiments (cronstedtite and berthierine). These minerals show low cation exchange and swelling capacities. The results also show that the interactions between iron and clay may lead to significant porosity changes in the system. A reduction of the porosity is predicted at the surface of the steel canister, due to the precipitation of iron oxides. Porosity increase is predicted in the clay material due to the dissolution of the primary clay minerals. The effect of these porosity

  5. Influence of the extent of hemoglobin hydrolysis on the digestive absorption of heme iron. An in vitro study.

    PubMed

    Vaghefi, Nikta; Nedjaoum, Fouzia; Guillochon, Didier; Bureau, François; Arhan, Pierre; Bouglé, Dominique

    2002-08-14

    This study was designed to assess the interactions of heme with peptides produced by enzyme hydrolysis of hemoglobin, and their relationship with heme iron absorption. Bovine hemoglobin was hydrolyzed by pepsin or by subtilisin, which differ in their hydrolysis processes. The hydrolysis rate ranged from 0 (native hemoglobin) to 15%. Heme solubility and heme-peptides interactions were compared to iron absorption by the Ussing chamber model, at intestinal pH (7.5). Increasing hemoglobin hydrolysis enhanced iron absorption; the highest value was reached between 8 and 11% hydrolysis, whatever the enzyme used. Comparing the products of hydrolysis of the two enzymes showed that heme iron absorption depends not only on its solubility, but relies mainly on the balance between the strength of heme-peptides and the polymerization rate of heme.

  6. [Microanalysis of serum iron by atomatic absorption spectrophotometry in a graphite oven: improvement and evaluation of this method].

    PubMed

    Favier, A; Maljournal, B; Decoux, G; Ruffieux, D

    1983-01-01

    We describe a method of micro-assay of serum iron by atomic absorption without flame, after deproteinisation of the serum by molar hydrochloric acid. In this way, we can assay the serum iron in 10 microliters of serum by injection of the supernatant into a graphite oven. The results show a good correlation with those obtained by conventional techniques of atomic absorption and colorimetric assays using ferrozine and bathophenanthroline. However, great care must be taken in the cleaning of plastic test tubes.

  7. Distinguishing iron-reducing from sulfate-reducing conditions

    USGS Publications Warehouse

    Chapelle, F.H.; Bradley, P.M.; Thomas, M.A.; McMahon, P.B.

    2009-01-01

    Ground water systems dominated by iron- or sulfate-reducing conditions may be distinguished by observing concentrations of dissolved iron (Fe2+) and sulfide (sum of H2S, HS-, and S= species and denoted here as "H2S"). This approach is based on the observation that concentrations of Fe2+ and H2S in ground water systems tend to be inversely related according to a hyperbolic function. That is, when Fe2+ concentrations are high, H2S concentrations tend to be low and vice versa. This relation partly reflects the rapid reaction kinetics of Fe2+ with H2S to produce relatively insoluble ferrous sulfides (FeS). This relation also reflects competition for organic substrates between the iron- and the sulfate-reducing microorganisms that catalyze the production of Fe2+ and H 2S. These solubility and microbial constraints operate in tandem, resulting in the observed hyperbolic relation between Fe2+ and H 2S concentrations. Concentrations of redox indicators, including dissolved hydrogen (H2) measured in a shallow aquifer in Hanahan, South Carolina, suggest that if the Fe2+/H2S mass ratio (units of mg/L) exceeded 10, the screened interval being tapped was consistently iron reducing (H2 ???0.2 to 0.8 nM). Conversely, if the Fe 2+/H2S ratio was less than 0.30, consistent sulfate-reducing (H2 ???1 to 5 nM) conditions were observed over time. Concomitantly high Fe2+ and H2S concentrations were associated with H2 concentrations that varied between 0.2 and 5.0 nM over time, suggesting mixing of water from adjacent iron- and sulfate-reducing zones or concomitant iron and sulfate reduction under nonelectron donor-limited conditions. These observations suggest that Fe2+/H2S mass ratios may provide useful information concerning the occurrence and distribution of iron and sulfate reduction in ground water systems. ?? 2009 National Ground Water Association.

  8. Microwave absorption properties of double-layer absorber based on carbonyl iron/barium hexaferrite composites

    NASA Astrophysics Data System (ADS)

    Ren, Xiaohu; Fan, Huiqing; Cheng, Yankui

    2016-05-01

    The microwave absorption properties of BaCo0.4Zn1.6Fe16O27 ferrite and carbonyl iron powder with single-layer and double-layer composite absorbers were investigated based on the electromagnetic transmission line theory in the frequency range from 1 to 14 GHz. XRD was used to characterize the structure of prepared absorbing particles. SEM was used to examine the micromorphology of the particles and composites. The complex permittivity and permeability of composites were measured by using a vector network analyzer. The reflection loss of the single-layer and double-layer absorbers with different thicknesses and orders was investigated. The results show that double-layer absorbers have better microwave absorption properties than single-layer absorbers. The microwave absorption properties of the double-layer structure are influenced by the coupling interactions between the matching and absorption layers. As the pure ferrite used as matching layer and the composite of BF-5CI used as absorption, the minimum RL of absorber can achieve to -55.4 dB and the bandwidth of RL <-10 dB ranged from 5.6 to 10.8 GHz when the thicknesses of matching layer and absorption layer were 0.9 and 1.4 mm, respectively.

  9. X-ray absorption spectroscopic studies of iron framework-substituted and exchanged zeolites: Characterization and quantification of incorporated iron species

    NASA Astrophysics Data System (ADS)

    Stanfel, Christine Marie

    X-ray absorption spectroscopic (XAS) analysis methods were derived which allowed iron species within iron substituted and exchanged zeolites to be characterized, and the fractional contribution of each species to the zeolite iron population to be quantified. Framework (T-site occupant) and non-framework iron species simultaneously present within zeolites were differentiated. Non-framework iron was segregated further into phases respectively exhibiting and lacking long range order. The former was described as precipitate iron. Zeolitic precipitate iron was found to occur either as an ordered Goethite-type phase, or a disordered aggregate. Iron species lacking long range order were found to be approximated by hydrated ferric ions (Fe(Hsb2O)sb6sp{3+}). XAS methods allowed determination of the fractional contribution of each iron phase; framework, precipitate, and low long range order, to the zeolite. XAS analysis methods were applied to an iron framework-substituted LTL zeolite (Fe LTL2) and two ferric exchanged analogs of Fe LTL2 (Fesp{3+} exchanged Fe LTL2). Fesp{3+} exchanged Fe LTL2 zeolites differed according to ferric salt and acid exposure length. Fe LTL2 was found to contain 20% disordered aggregate precipitate iron, and 80% framework iron. Fesp{3+} exchanged Fe LTL2 zeolites contained three iron species; framework, precipitate, and low long range order. Exchange left Fe LTL2 precipitate type and quantity unchanged, while framework iron decreased. Elemental analysis indicated composition changes arose from framework iron removal by acid exposure. Iron lacking long range order served a charge-balancing function as increased levels correlated with decreased Ksp+/(Al + Fesbframework) ratios. XAS methods were additionally applied to six iron framework-substituted faujasites (Fe FAU) with Si/Al ratios consistent with zeolites X, Y, and ECR-32. Two iron substitution levels, low and high, were synthesized for each isotype. Iron within each faujasite partitioned into

  10. Energy absorption characteristics of lightweight structural member by stacking conditions

    NASA Astrophysics Data System (ADS)

    Choi, Juho; Yang, Yongjun; Hwang, Woochae; Pyeon, Seokbeom; Min, Hanki; Yeo, Ingoo; Yang, Inyoung

    2012-04-01

    The recent trend in vehicle design is aimed at improving crash safety and environmental-friendliness. To solve these issues, the needs for lighter vehicle to limit exhaust gas and improve fuel economy has been requested for environmental-friendliness. Automobile design should be made for reduced weight once the safety of vehicle is maintained. In this study, composite structural members were manufactured using carbon fiber reinforced plastic (CFRP) which are representative lightweight structural materials. Carbon fiber has been researched as alternative to metals for lightweight vehicle and better fuel economy. CFRP is an anisotropic material which is the most widely adapted lightweight structural member because of their inherent design flexibility and high specific strength and stiffness. Also, variation of CFRP interface number is important to increase the energy absorption capacity. In this study, one type of circular shaped composite tube was used, combined with reinforcing foam. The stacking condition was selected to investigate the effect of the fiber orientation angle and interface number. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported. The axial static collapse tests were carried out for each section member. The collapse modes and the energy absorption capability of the members were analyzed.

  11. Energy absorption characteristics of lightweight structural member by stacking conditions

    NASA Astrophysics Data System (ADS)

    Choi, Juho; Yang, Yongjun; Hwang, Woochae; Pyeon, Seokbeom; Min, Hanki; Yeo, Ingoo; Yang, Inyoung

    2011-11-01

    The recent trend in vehicle design is aimed at improving crash safety and environmental-friendliness. To solve these issues, the needs for lighter vehicle to limit exhaust gas and improve fuel economy has been requested for environmental-friendliness. Automobile design should be made for reduced weight once the safety of vehicle is maintained. In this study, composite structural members were manufactured using carbon fiber reinforced plastic (CFRP) which are representative lightweight structural materials. Carbon fiber has been researched as alternative to metals for lightweight vehicle and better fuel economy. CFRP is an anisotropic material which is the most widely adapted lightweight structural member because of their inherent design flexibility and high specific strength and stiffness. Also, variation of CFRP interface number is important to increase the energy absorption capacity. In this study, one type of circular shaped composite tube was used, combined with reinforcing foam. The stacking condition was selected to investigate the effect of the fiber orientation angle and interface number. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported. The axial static collapse tests were carried out for each section member. The collapse modes and the energy absorption capability of the members were analyzed.

  12. The effects of fruit juices and fruits on the absorption of iron from a rice meal.

    PubMed

    Ballot, D; Baynes, R D; Bothwell, T H; Gillooly, M; MacFarlane, B J; MacPhail, A P; Lyons, G; Derman, D P; Bezwoda, W R; Torrance, J D

    1987-05-01

    The effects of the chemical composition of fruit juices and fruit on the absorption of iron from a rice (Oryza sativa) meal were measured in 234 parous Indian women, using the erythrocyte utilization of radioactive Fe method. The corrected geometric mean Fe absorptions with different juices varied between 0.040 and 0.129, with the variation correlating closely with the ascorbic acid contents of the juices (rs 0.838, P less than 0.01). Ascorbic acid was not the only organic acid responsible for the promoting effects of citrus fruit juices on Fe absorption. Fe absorption from laboratory 'orange juice' (100 ml water, 33 mg ascorbic acid and 750 mg citric acid) was significantly better than that from 100 ml water and 33 mg ascorbic acid alone (0.097 and 0.059 respectively), while Fe absorption from 100 ml orange juice (28 mg ascorbic acid) was better than that from 100 ml water containing the same amount of ascorbic acid (0.139 and 0.098 respectively). Finally, Fe absorption from laboratory 'lemon juice' (100 ml orange juice and 4 g citric acid) was significantly better than that from 100 ml orange juice (0.226 and 0.166 respectively). The corrected geometric mean Fe absorption from the rice meal was 0.025. Several fruits had little or no effect on Fe absorption from the meal (0.013-0.024). These included grape (Vitis vinifera), peach (Prunus persica), apple (Malus sylvestris) and avocado pear (Persea americana). Fruit with a mild to moderate enhancing effect on Fe absorption (0.031-0.088) included strawberry (Fragaria sp.) (uncorrected values), plum (Prunus domestica), rhubarb (Rheum rhaponticum), banana (Musa cavendishii), mango (Mangifera indica), pear (Pyrus communis), cantaloup (Cucumis melo) and pineapple (Ananas comosus) (uncorrected values). Guava (Psidium guajava) and pawpaw (Carica papaya) markedly increased Fe absorption (0.126-0.293). There was a close correlation between Fe absorption and the ascorbic acid content of the fruits tested (rs 0.738, P less

  13. Dielectronic Recombination Of Iron M-shell Ions Motivated By Absorption Features In AGN Spectra

    NASA Astrophysics Data System (ADS)

    Lukic, Dragan; Schnell, M.; Savin, D. W.; Brandau, C.; Schmidt, E. W.; Yu, D.; Bernhardt, D.; Schippers, S.; Müller, A.; Lestinsky, M.; Orlov, D.; Sprenger, F.; Grieser, M.; Repnow, R.; Hoffmann, J.; Wolf, A.

    2006-09-01

    XMM-Newton and Chandra observations of active galactic nuclei (AGN) show spectra rich with X-ray absorption features. These observations have detected a broad unresolved transition array (UTA) between 15-17 Å. This is attributed to inner-shell photoexcitation of M-shell iron ions. Modeling these UTA features is currently limited by uncertainties in the low-temperature dielectronic recombination (DR) data for M-shell iron. In order to resolve this issue, and to provide reliable iron M-shell DR data for plasma modeling, we are carrying out a series of laboratory measurements using the heavy-ion Test Storage Ring (TSR) at the Max-Plank-Institute for Nuclear Physics in Heidelberg, Germany. We use the DR data obtained at TSR, to calculate rate coefficients for plasma modeling. We are also providing our data to atomic theorist to benchmark their DR calculations. Here we report our recent experimental results for DR for several iron M-shell ions and plans for future work. This work has been supported in part by NASA, the German Federal Ministry for Education and Research, and the German Research Council

  14. Thermal and electrical conductivity of iron at Earth's core conditions.

    PubMed

    Pozzo, Monica; Davies, Chris; Gubbins, David; Alfè, Dario

    2012-04-11

    The Earth acts as a gigantic heat engine driven by the decay of radiogenic isotopes and slow cooling, which gives rise to plate tectonics, volcanoes and mountain building. Another key product is the geomagnetic field, generated in the liquid iron core by a dynamo running on heat released by cooling and freezing (as the solid inner core grows), and on chemical convection (due to light elements expelled from the liquid on freezing). The power supplied to the geodynamo, measured by the heat flux across the core-mantle boundary (CMB), places constraints on Earth's evolution. Estimates of CMB heat flux depend on properties of iron mixtures under the extreme pressure and temperature conditions in the core, most critically on the thermal and electrical conductivities. These quantities remain poorly known because of inherent experimental and theoretical difficulties. Here we use density functional theory to compute these conductivities in liquid iron mixtures at core conditions from first principles--unlike previous estimates, which relied on extrapolations. The mixtures of iron, oxygen, sulphur and silicon are taken from earlier work and fit the seismologically determined core density and inner-core boundary density jump. We find both conductivities to be two to three times higher than estimates in current use. The changes are so large that core thermal histories and power requirements need to be reassessed. New estimates indicate that the adiabatic heat flux is 15 to 16 terawatts at the CMB, higher than present estimates of CMB heat flux based on mantle convection; the top of the core must be thermally stratified and any convection in the upper core must be driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMB heat flow. Power for the geodynamo is greatly restricted, and future models of mantle evolution will need to incorporate a high CMB heat flux and explain the recent formation of the inner core.

  15. Iron analysis in atmospheric water samples by atomic absorption spectroscopy (AAS) in water-methanol.

    PubMed

    Sofikitis, A M; Colin, J L; Desboeufs, K V; Losno, R

    2004-01-01

    To distinguish between Fe(II) and Fe(III) species in atmospheric water samples, we have adapted an analytical procedure based on the formation of a specific complex between Fe(II) and ferrozine (FZ) on a chromatographic column. After elution of Fe(III), the Fe(II) complex is recovered with water-methanol (4:1). The possibility of trace iron measurements in this complex medium by graphite-furnace atomic-absorption spectrometry has been investigated. A simplex optimization routine was required to complete the development of the analytical method.

  16. Solvent-dependent absorption and electronic relaxation dynamics of iron (III) tetra-4-N-methylpyridylporphine

    NASA Astrophysics Data System (ADS)

    Williams, Lenzi J.; Knappenberger, Kenneth L.

    2017-03-01

    Solvent-dependent excited-state relaxation dynamics of iron (III) tetra-4-N-methylpyridylporphine (FeTMPyP) were investigated using steady-state and femtosecond spectroscopies. Soret absorption for water-dispersed FeTMPyP consisted of two spectrally broad components centered at 3.12 eV and 2.92 eV, corresponding to π → π∗ and charge-transfer (C-T) transitions. The C-T transition exhibited inverse-dielectric-dependent energy shifts. Following 400-nm excitation, dynamics proceeded by femtosecond internal conversion from the initially prepared π∗ state to the C-T state, followed by solvent-dependent C-T relaxation. The C-T energy shifts and relaxation rates exhibited correlated dielectric dependences. C-T absorption energy and relaxation dynamics of FeTMPyP are sensitive indicators of surrounding dielectric environments.

  17. A theoretical and experimental study of calcium, iron, zinc, cadmium, and sodium ions absorption by aspartame.

    PubMed

    Mahnam, Karim; Raisi, Fatame

    2017-03-01

    Aspartame (L-Aspartyl-L-phenylalanine methyl ester) is a sweet dipeptide used in some foods and beverages. Experimental studies show that aspartame causes osteoporosis and some illnesses, which are similar to those of copper and calcium deficiency. This raises the issue that aspartame in food may interact with cations and excrete them from the body. This study aimed to study aspartame interaction with calcium, zinc, iron, sodium, and cadmium ions via molecular dynamics simulation (MD) and spectroscopy. Following a 480-ns molecular dynamics simulation, it became clear that the aspartame is able to sequester Fe(2+), Ca(2+), Cd(2+), and Zn(2+) ions for a long time. Complexation led to increasing UV-Vis absorption spectra and emission spectra of the complexes. This study suggests a potential risk of cationic absorption of aspartame. This study suggests that purification of cadmium-polluted water by aspartame needs a more general risk assessment.

  18. Impact of silica-coating on the microwave absorption properties of carbonyl iron powder

    NASA Astrophysics Data System (ADS)

    Li, J.; Feng, W. J.; Wang, J. S.; Zhao, X.; Zheng, W. Q.; Yang, H.

    2015-11-01

    Microwave absorption properties, especially the band width and depth of reflection loss are highlighted as key measurement in studies of microwave absorber. In order to improve the band width and depth of reflection loss of carbonyl iron powder (CIP), we prepared SiO2 layers on the surface of CIP by using tetraethyl orthosilicate (TEOS) as a SiO2 source and 3-aminopropyl triethoxysilane (APTES) as a surface modifier. SiO2 layer was formed by the hydrolysis of TEOS. The results show that after treatment the CIP is covered by a 5-10 nm coating layer. Contrast to uncoated samples, coated samples show improved absorption properties. The minimum of reflection loss is -38.8 dB at 11 GHz and the band width of reflection loss exceeding -10 dB is from 8 GHz to 14 GHz.

  19. Reassignment of the Iron (3) Absorption Bands in the Spectra of Mars

    NASA Technical Reports Server (NTRS)

    Sherman, D. M.

    1985-01-01

    Absorption features in the near-infrared and visible region reflectance spectra of Mars have been assigned to specific Fe (3+) crystal-field and o(2-) yields Fe(3+) charge transfer transitions. Recently, near-ultraviolet absorption spectra of iron oxides were obtained and the energies of o(2-) yields Fe(3+) charge-transfer (LMCT) transitions were determined from accurate SCF-X # alpha-SW molecular orbital calculations on (FeO6)(9-) and (FeO4)(5-) clusters. Both the theoretical and experimental results, together with existing data in the literature, show that some of the previous Fe(3+) band assignments in the spectra of Mars need to be revised. The theory of Fe(3+) spectra in minerals is discussed and applied to the spectrum of Mars.

  20. Copper, iron and zinc absorption, retention and status of young women fed vitamin B-6 deficient diets

    SciTech Connect

    Turnlund, J.R.; Keyes, W.R.; Hudson, C.A.; Betschart, A.A.; Kretsch, M.J.; Sauberlich, H.E. Western Regional Research Center, Albany, CA )

    1991-03-11

    A study was conducted in young women to determine the effect of vitamin B-6 deficient diets on copper, iron and zinc metabolism. Young women were confined to a metabolic research unit for 84 and 98 days. They were fed a vitamin B-6 deficient formula diet initially, followed by food diet containing four increasing levels of vitamin B-6. Copper, iron and zinc absorption, retention and status were determined at intervals throughout the study. Absorption was determined using the stable isotopes {sup 65}Cu, {sup 54}Fe, and {sup 67}Zn. Status was based on serum copper and zinc, hemoglobin, hematocrit and mean corpuscular volume. Copper absorption averaged 18 {plus minus} 1% during vitamin B-6 depletion, significantly lower than 24 {plus minus} 1% during repletion, but serum copper was not affected and balance was positive. Iron absorption was not impaired significantly by vitamin B-6 deficient diets, but status declined during the depletion period. Zinc absorption averaged 40 {plus minus} 2% during depletion and 27 {plus minus} 2% during repletion. Zinc absorption and retention were significantly greater during vitamin B-6 depletion, but serum zinc declined suggesting the absorbed zinc was not available for utilization. The results suggest that vitamin B-6 depletion of young women may inhibit copper absorption, affect iron status and alter zinc metabolism. The effects of vitamin B-6 depletion differ markedly among these elements.

  1. A flow-batch internal standard procedure for iron determination in hydrated ethanol fuel by flame atomic absorption spectrometry.

    PubMed

    da Silva, José Edson; da Silva, Fábio André; Pimentel, M Fernanda; Honorato, Ricardo Saldanha; da Silva, Valdinete Lins; Montenegro, Maria da Conceição B S M; Araújo, Alberto N

    2006-10-15

    A flow-batch manifold coupled to a flame atomic absorption spectrometer was evaluated to assess the iron content by the internal standard method in hydrated ethanol used as fuel in automotive industry. For this assessment official methods require calibration procedures with matrix matching, making it difficult to obtain accurate results for samples adulterated by the addition of water. Nickel was selected as the internal standard since it is usually absent in samples and because it requires similar conditions of atomization. After procedure optimization, which requires about 4.25mL of sample and standard per measurement, it was possible to get linear analytical response for iron concentrations between 0.12 and 1.40mgL(-1) and a detection limit of 0.04mgL(-1). Eighteen samples were collected randomly from fuel stations in Pernambuco (Brazil) and iron concentration was determined using the proposed procedure. Comparison of results obtained (0.20-1.50mgL(-1)) showed a mean standard error of 3.9%, with 3.8% and 2.3% calculated for the mean variation coefficients of the proposed method and the reference procedure, respectively. For adulterated samples (0.12-0.64mgL(-1)), the mean standard error was 4.8% when compared with the standard addition method. These results allowed concluding that the proposed procedure is adequate to accomplish the determination of iron in ethanol fuel in a large scale basis with a sampling rate of about 10h(-1).

  2. A search for the iron absorption edge in the tail of an X-ray burst from X1636 - 53

    NASA Technical Reports Server (NTRS)

    Day, C. S. R.; Fabian, A. C.; Ross, R. R.

    1992-01-01

    Model atmosphere calculations of the spectrum of a neutron star cooling after an X-ray burst show that the photoelectric edge of iron should be prominent. No clear evidence for such a redshifted feature in the spectrum of a burst from X1636 - 53 is found, and it is concluded that the iron abundance there must be less than 0.3 solar. Unless the iron abundance of the surface matter on the neutron star is highly time-dependent, the present result argues against the 4.1-keV absorption line seen in some bursts from X1636 - 53 by Waki et al. (1984) being due to iron. The iron edge will be a powerful diagnostic of the surface redshift of the neutron star in burst sources where the iron abundance is more nearly solar.

  3. Evaluation of iron-containing carbon nanotubes by near edge X-ray absorption technique

    NASA Astrophysics Data System (ADS)

    Osorio, A. G.; Bergmann, C. P.

    2015-10-01

    The synthesis of carbon nanotubes (CNTs) via Chemical Vapor Deposition method with ferrocene results in CNTs filled with Fe-containing nanoparticles. The present work proposes a novel route to characterize the Fe phases in CNTs inherent to the synthesis process. CNTs were synthesized and, afterwards, the CNTs were heat treated at 1000 °C for 20 min in an inert atmosphere during a thermogravimetric experiment. X-Ray Absorption Spectroscopy (XAS) experiments were performed on the CNTs before and after the heat treatment and, also, during the heat treatment, e.g., in situ tests were performed while several Near-Edge X-Ray Absorption (XANES) spectra were collected during the heating of the samples. The XAS technique was successfully applied to evaluate the phases encapsulated by CNTs. Phase transformations of the Fe-based nanoparticles were also observed from iron carbide to metallic iron when the in situ experiments were performed. Results also indicated that the applied synthesis method guarantees that Fe phases are not oxidize. In addition, the results show that heat treatment under inert atmosphere can control which phase remains encapsulated by the CNTs.

  4. Phytoestrogens modulate hepcidin expression by Nrf2: Implications for dietary control of iron absorption.

    PubMed

    Bayele, Henry K; Balesaria, Sara; Srai, Surjit K S

    2015-12-01

    Hepcidin is a liver-derived antimicrobial peptide that regulates iron absorption and is also an integral part of the acute phase response. In a previous report, we found evidence that this peptide could also be induced by toxic heavy metals and xenobiotics, thus broadening its teleological role as a defensin. However it remained unclear how its sensing of disparate biotic and abiotic stressors might be integrated at the transcriptional level. We hypothesized that its function in cytoprotection may be regulated by NFE2-related factor 2 (Nrf2), the master transcriptional controller of cellular stress defenses. In this report, we show that hepcidin regulation is inextricably linked to the acute stress response through Nrf2 signaling. Nrf2 regulates hepcidin expression from a prototypical antioxidant response element in its promoter, and by synergizing with other basic leucine-zipper transcription factors. We also show that polyphenolic small molecules or phytoestrogens commonly found in fruits and vegetables including the red wine constituent resveratrol can induce hepcidin expression in vitro and post-prandially, with concomitant reductions in circulating iron levels and transferrin saturation by one such polyphenol quercetin. Furthermore, these molecules derepress hepcidin promoter activity when its transcription by Nrf2 is repressed by Keap1. Taken together, the data show that hepcidin is a prototypical antioxidant response or cytoprotective gene within the Nrf2 transcriptional circuitry. The ability of phytoestrogens to modulate hepcidin expression in vivo suggests a novel mechanism by which diet may impact iron homeostasis.

  5. Genetic reduction of phytate in common bean (Phaseolus vulgaris L.) seeds increases iron absorption in young women.

    PubMed

    Petry, Nicolai; Egli, Ines; Campion, Bruno; Nielsen, Erik; Hurrell, Richard

    2013-08-01

    Iron bioavailability from common beans is negatively influenced by phytic acid (PA) and polyphenols (PPs). Newly developed low-PA (lpa) beans with 90% less PA and variable PPs might improve iron bioavailability. The aim of this study was to evaluate the influence of lpa beans on iron bioavailability in women (n = 20). We compared iron absorption from 4 different beans using a paired, double meal, crossover design. Iron absorption was measured as erythrocyte incorporation of stable iron isotopes (Fe(57), Fe(58)) from 2 lpa bean lines, one high in PPs (means ± SDs; PA = 124 ± 10 mg/100 g; PPs = 462 ± 25 mg/100 g) and one low in PPs (PA = 70 ± 10 mg/100 g; PPs = 54 ± 2 mg/100 g). The other 2 beans used were their parents with a normal PA concentration, one high in PPs (PA = 1030 ± 30 mg/100 g; PPs = 676 ± 19 mg/100 g) and one low in PPs (PA = 1360 ± 10 mg/100 g; PPs = 58 ± 1 mg/100 g). Fractional iron absorption from the lpa bean high in PPs was 6.1% (95% CI: 2.6, 14.7), which was 60 and 130% higher compared with the parent high in PPs (P < 0.001) and low in PPs (P < 0.001), respectively. The total amount of iron absorbed per test meal from the lpa bean high in PPs (372 μg; 95% CI: 160, 890) was 60 and 163% higher compared with the parent high in PPs (P < 0.001) and low in PPs (P < 0.001), respectively. Fractional iron absorption from the lpa line low in PPs (4%; 95% CI: 1.8, 8.7) was 50% higher and the total amount of iron absorbed per test meal (261 μg; 95% CI: 120, 570) was 85% higher than iron from the parent low in PPs (P < 0.001). There was no difference between the lpa beans high or low in PPs or between the parents high or low in PPs. A 90% reduction in PA leads to an increase in bioavailable iron from beans, independent of the PP concentration. The lpa mutation could be a key tool for improving iron bioavailability from beans.

  6. Bioavailability of iron in geophagic earths and clay minerals, and their effect on dietary iron absorption using an in vitro digestion/Caco-2 cell model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophagy, the deliberate consumption of earth, is strongly associated with iron (Fe) deficiency. It has been proposed that geophagy may be practiced as a means to improve Fe status by increasing Fe intakes and, conversely, that geophagy may cause Fe deficiency by inhibiting Fe absorption. We tested ...

  7. Ligand discrimination of myoglobin in solution: an iron L-edge X-ray absorption study of the active centre.

    PubMed

    Lange, Kathrin M; Golnak, Ronny; Bonhommeau, Sébastien; Aziz, Emad F

    2013-05-14

    Iron L-edge X-ray absorption spectra of the active centre of myoglobin in the met-form, in the reduced form and upon ligation to O2, CO, NO and CN are presented. The strength of ligation with the iron centre is finger-printed through the variation of the L3 : L2 intensity ratio. Charge Transfer Multiplet calculations are performed and give qualitative information about oxidation states as well as charge transfer.

  8. Vesicular transport and apotransferrin in intestinal iron absorption, as shown in the Caco-2 cell model.

    PubMed

    Moriya, Mizue; Linder, Maria C

    2006-02-01

    The potential roles of vesicular transport and apotransferrin (entering from the blood) in intestinal Fe absorption were investigated using Caco-2 cell monolayers with tight junctions in bicameral chambers as a model. As shown previously, addition of 39 microM apotransferrin (apoTf) to the basolateral fluid during absorption studies markedly stimulated overall transport of 1 microM (59)Fe from the apical to the basal chamber and stimulated its basolateral release from prelabeled cells, implicating endo- and exocytosis. Rates of transport more than doubled. Uptake was also stimulated, but only 20%. Specific inhibitors of aspects of vesicular trafficking were applied to determine their potential effects on uptake, retention, and basolateral (overall) transport of (59)Fe. Nocodazole and 5'-(4-fluorosulfonylbenzoyl)-adenosine each reduced uptake and basolateral transport up to 50%. Brefeldin A inhibited about 10%. Tyrphostin A8 (AG10) reduced uptake 35% but markedly stimulated basolateral efflux, particularly that dependent on apoTf. Cooling of cells to 4 degrees C (which causes depolymerization of microtubules and lowers energy availability) profoundly inhibited uptake and basolateral transfer of Fe (7- to 12-fold). Apical efflux (which was substantial) was not temperature affected. Our results support the involvement of apoTf cycling in intestinal Fe absorption and indicate that as much as half of the iron uses apoTf and non-apoTf-dependent vesicular pathways to cross the basolateral membrane and brush border of enterocytes.

  9. Optimization of absorption air-conditioning for solar energy applications

    NASA Technical Reports Server (NTRS)

    Perry, E. H.

    1976-01-01

    Improved performance of solar cooling systems using the lithium bromide water absorption cycle is investigated. Included are computer simulations of a solar-cooled house, analyses and measurements of heat transfer rates in absorption system components, and design and fabrication of various system components. A survey of solar collector convection suppression methods is presented.

  10. Parenteral iron dextran therapy.

    PubMed

    Kumpf, V J; Holland, E G

    1990-02-01

    Parenteral iron therapy is indicated in patients with iron-deficiency anemia associated with conditions that interfere with the ingestion or absorption of oral iron. Replacement doses of iron required to replenish iron stores are based on body weight and the observed hemoglobin value. Methods of administering iron dextran are reviewed, including intramuscular and intravenous injections of the undiluted drug, intravenous infusion of a diluted preparation, and as an addition to parenteral nutrition solutions. The overall incidence of adverse reactions associated with the parenteral administration of iron is low, but the potential for an anaphylactic reaction requires that an initial test dose be given followed by careful patient observation.

  11. Effect of increasing levels of zinc fortificant on the iron absorption of bread co-fortified with iron and zinc consumed with a black tea.

    PubMed

    Olivares, Manuel; Castro, Carla; Pizarro, Fernando; de Romaña, Daniel López

    2013-09-01

    Iron (Fe) and zinc's (Zn) interaction at the absorptive level can have an effect on the success of co-fortification of wheat flour with both minerals on iron deficiency prevention. The aim of the study was to determine the effect of increasing levels of zinc fortificant on the iron absorption of bread co-fortified with iron and zinc consumed with a black tea. Twelve women aged 33-42 years participated in the study. They received on four different days 200 mL of black tea and 100 g of bread made with wheat flour (70% extraction) fortified with either 30 mg Fe/kg alone, as ferrous sulfate (A), or with the same Fe-fortified flour, but with graded levels of Zn, as zinc sulfate: 30 mg/kg (B), 60 mg/kg (C), or 90 mg/kg (D). Fe radioisotopes ((59)Fe and (55)Fe) of high specific activity were used as tracers, and Fe absorption iron was measured by the incorporation of radioactive Fe into erythrocytes. The geometric mean and range of ±1 SD of Fe absorption were as follows: A = 6.5% (2.2-19.3%), B = 4.6% (1.0-21.0%), C = 2.1% (0.9-4.9%), and D = 2.2% (0.7-6.6%), respectively; ANOVA for repeated measures F = 10.9, p < 0.001 (Scheffè's post hoc test: A vs. C, A vs. D, B vs. C, and B vs. D; p < 0.05). We can conclude that Fe absorption of bread made from low-extraction flour fortified with 30 mg/kg of Fe, as ferrous sulfate, and co-fortified with zinc, as zinc sulfate consumed with black tea is significantly decreased at a zinc fortification level of ≥60 mg/kg flour.

  12. Low temperature charge transport and microwave absorption of carbon coated iron nanoparticles–polymer composite films

    SciTech Connect

    Prasad, V.

    2012-06-15

    Highlights: ► Carbon coated Fe nanoparticle–PVC composite films were prepared by solution casting method. ► A low electrical percolation threshold of 2.2 was achieved. ► The low temperature electrical conductivity follows variable range hopping type conduction. ► An EMI shielding of 18 dB was achieved in 200 micron thick film. -- Abstract: In this paper, the low temperature electrical conductivity and microwave absorption properties of carbon coated iron nanoparticles–polyvinyl chloride composite films are investigated for different filler fractions. The filler particles are prepared by the pyrolysis of ferrocene at 980 °C and embedded in polyvinyl chloride matrix. The high resolution transmission electron micrographs of the filler material have shown a 5 nm thin layer graphitic carbon covering over iron particles. The room temperature electrical conductivity of the composite film changes by 10 orders of magnitude with the increase of filler concentration. A percolation threshold of 2.2 and an electromagnetic interference shielding efficiency (EMI SE) of ∼18.6 dB in 26.5–40 GHz range are observed for 50 wt% loading. The charge transport follows three dimensional variable range hopping conduction.

  13. Effects of proteins on absorption by the rat of iron from polymeric and low-molecular-weight iron species

    SciTech Connect

    Berner, L.; Miller, D.

    1986-03-05

    To examine effects of proteins on Fe absorption from polymeric ferric hydroxides (polys) or low-molecular-weight complexes (LMW Fe), 2 studies were conducted. First, anemic rats were given /sup 59/Fe-labeled polys or LMW Fe in the presence and absence of pepsin-digested soy protein isolate, casein, and BSA. The doses were introduced into ligated duodenal segments for 1 hr. Uptake into the carcass of /sup 59/Fe from polys was doubled in the presence of BSA (7.8 vs 16.1%, p < .05) while casein and soy had no effect (5.5 and 6.5%). Absorption of /sup 59/Fe from LMW Fe was 7X greater than from polys; BSA and casein had no effect but soy depressed Fe uptake by almost 50% (57.4 vs 35.5%, p < .05). The second experiment repeated the first except that the proteins were not pepsin-digested and the doses were given by gastric intubation. All Fe, whether from polys or LMW Fe, was highly available (although in vitro digestions reveal that polys are not depolymerized to a large degree under simulated stomach conditions). Soy depressed Fe uptake from both sources (92.9 vs. 81.6%, LMW Fe and 85.4 vs 73.7%, polys) while casein and BSA had no effect. These results show: (1) BSA can depolymerize polys in the rat duodenum, thus enhancing absorption; (2) soy isolate generally depressed Fe uptake; and (3) the rat stomach appears to have an exceptional capacity for equalizing Fe sources.

  14. Removing nitric oxide from flue gas using iron(II) citrate chelate absorption with microbial regeneration.

    PubMed

    Xu, Xinhua; Chang, Shih Ger

    2007-04-01

    The addition of metal chelates such as Fe(II)EDTA or Fe(II)Cit to wet flue gas desulfurization systems has been shown to increase the amount of NO(x) absorption from gas streams containing SO(2). This paper attempts to demonstrate the advantage of not only using Fe(II)Cit chelate to absorb nitrogen oxides from flue gas but also the advantage gained from adding microorganisms to the system. Two distinct classes of microorganisms are needed: denitrifying and iron-reducing bacteria. The presence of oxygen in flue gas will affect the absorption efficiency of NO by Fe(II)Cit chelate. The oxidation of Fe(II) can be slowed with the help of bacteria in two ways: bacteria can serve to directly reduce Fe(III) to Fe(II) or they can serve to keep levels of dissolved oxygen in the solution low. As a result, after NO absorption, Fe(II)(Cit)NO will be reduced by denitrifying bacteria to Fe(II)Cit while Fe(III) is reduced by anaerobic bacteria back to Fe(II). Our experiments have shown that the implementation of our protocol allowed for an NO reduction rate constant increase from standard levels of 0.0222-0.100 m Mh(-1) with inlet NO changed from 250 to 1000 ppm. We have also found that total Fe concentration tends to decrease after prolonged periods of operation due to the loss of some Fe to the formation of Fe(OH)(3) that settles together with the sludge at the bottom of bioreactor tank.

  15. Probiotic strain Lactobacillus plantarum 299v increases iron absorption from an iron-supplemented fruit drink: a double-isotope cross-over single-blind study in women of reproductive age.

    PubMed

    Hoppe, Michael; Önning, Gunilla; Berggren, Anna; Hulthén, Lena

    2015-10-28

    Iron deficiency is common, especially among young women. Adding probiotics to foods could be one way to increase iron absorption. The aim of this study was to test the hypothesis that non-haem iron absorption from a fruit drink is improved by adding Lactobacillus plantarum 299v (Lp299v). Iron absorption was studied in healthy women of reproductive age using a single-blind cross-over design in two trials applying the double-isotope (55Fe and 59Fe) technique. In Trial 1, iron absorption from a fruit drink containing 109 colony-forming units (CFU) Lp299v was compared with that from a control drink without Lp299v. Trial 2 had the same design but 1010 CFU were used. The test and control drinks contained approximately 5 mg of iron as ferrous lactate and were labelled with 59Fe (B) and 55Fe (A), respectively, and consumed on 4 consecutive days in the order AABB. Retention of the isotopes was measured with whole-body counting and in blood. Mean iron absorption from the drink containing 109 CFU Lp299v (28·6(sd 12·5) %) was significantly higher than from the control drink (18·5(sd 5·8) %), n 10, P<0·028). The fruit drink with 1010 CFU Lp299v gave a mean iron absorption of 29·1(sd 17·0) %, whereas the control drink gave an absorption of (20·1(sd 6·4) %) (n 11, P<0·080). The difference in iron absorption between the 109 CFU Lp299v and the 1010 CFU Lp299v drinks was not significant (P=0·941). In conclusion, intake of probiotics can increase iron absorption by approximately 50 % from a fruit drink having an already relatively high iron bioavailability.

  16. Enigmatic photon absorption in plasmas near solar interior conditions

    NASA Astrophysics Data System (ADS)

    Iglesias, Carlos A.

    2015-06-01

    Large systematic discrepancies between theoretical and experimental photon absorption of Fe plasmas applicable to the solar interior were reported [Bailey et al., Nature 517, 56 (2015)]. The disagreement is examined in the context of the Thomas-Reiche-Kuhn f-sum rule. The analysis identifies several anomalies in the experimental results.

  17. Influence of external magnetic field on the microwave absorption properties of carbonyl iron and polychloroprene composites film

    NASA Astrophysics Data System (ADS)

    Wang, Haiyan; Li, Mingjie; Li, Xueai

    2016-12-01

    The carbonyl iron particles were dispersed in a polychloroprene rubber (CR) matrix under a magnetic field for a practical application as microwave absorption composites film. In comparison with the carbonyl iron particles (CIP)/CR composites film prepared by general route, such films made with external magnetic field exhibit excellent microwave absorption properties, strongly depending on the increment of anisotropy and rearrangement of magnetic particles. The film made under external magnetic field with a thickness of only 0.54 mm shows least reflection loss of -15.98 dB and the reflection loss value less than -10.0 dB over the frequency range of 11.4˜14.8 GHz. The results indicated the composite film made under external magnetic field have excellent microwave absorption properties, which suggest that the composites thin film could be used as a thinner and lighter microwave absorber.

  18. Ineffective erythropoiesis in β-thalassemia is characterized by increased iron absorption mediated by down-regulation of hepcidin and up-regulation of ferroportin

    PubMed Central

    Gardenghi, Sara; Marongiu, Maria F.; Ramos, Pedro; Guy, Ella; Breda, Laura; Chadburn, Amy; Liu, YiFang; Amariglio, Ninette; Rechavi, Gideon; Rachmilewitz, Eliezer A.; Breuer, William; Cabantchik, Z. Ioav; Wrighting, Diedra M.; Andrews, Nancy C.; de Sousa, Maria; Giardina, Patricia J.; Grady, Robert W.

    2007-01-01

    Progressive iron overload is the most salient and ultimately fatal complication of β-thalassemia. However, little is known about the relationship among ineffective erythropoiesis (IE), the role of iron-regulatory genes, and tissue iron distribution in β-thalassemia. We analyzed tissue iron content and iron-regulatory gene expression in the liver, duodenum, spleen, bone marrow, kidney, and heart of mice up to 1 year old that exhibit levels of iron overload and anemia consistent with both β-thalassemia intermedia (th3/+) and major (th3/th3). Here we show, for the first time, that tissue and cellular iron distribution are abnormal and different in th3/+ and th3/th3 mice, and that transfusion therapy can rescue mice affected by β-thalassemia major and modify both the absorption and distribution of iron. Our study reveals that the degree of IE dictates tissue iron distribution and that IE and iron content regulate hepcidin (Hamp1) and other iron-regulatory genes such as Hfe and Cebpa. In young th3/+ and th3/th3 mice, low Hamp1 levels are responsible for increased iron absorption. However, in 1-year-old th3/+ animals, Hamp1 levels rise and it is rather the increase of ferroportin (Fpn1) that sustains iron accumulation, thus revealing a fundamental role of this iron transporter in the iron overload of β-thalassemia. PMID:17299088

  19. Dual-band microwave absorption properties of metamaterial absorber composed of split ring resonator on carbonyl iron powder composites

    NASA Astrophysics Data System (ADS)

    Lim, Jun-Hee; Ryu, Yo-Han; Kim, Sung-Soo

    2015-05-01

    This study investigated the dual-band absorption properties of metamaterial absorbers composed of a split ring resonator (SRR) on a grounded magnetic substrate. Polymer composites of carbonyl iron powders (CIP) of high permeability and magnetic loss were used as the substrate material. Computational tools were used to model the interaction between electromagnetic waves and materials with the SRR structure. For perpendicular polarization with an electric field (E) perpendicular to the SRR gap, dualband absorption peaks are predicted in the simulation result of reflection loss. Magnetic resonance resulting from antiparallel currents between the SRR and the ground plane is observed at the frequencies of two absorption peaks. The first strong absorption peak at the lower frequency (3.3 GHz) is due to magnetic resonance at the wire part of the SRR. The second absorption peak at the higher frequency (7.2 GHz) is due to magnetic resonance at the SRR split gap. The decreased capacitance with increased gap spacing moves the second absorption frequency to higher frequencies, while the first absorption peak is invariant with gap spacing. In the case of dual gaps at the opposite sides of the SRR, a single absorption peak is predicted due to the elimination of low-frequency resonance. For parallel polarization with the E-field parallel to the SRR gap, a single absorption peak is predicted, corresponding to magnetic resonance at the SRR wire.[Figure not available: see fulltext.

  20. Local environment of iron in heavy ion-irradiated amorphous magnetic oxides by Moessbauer and x-ray absorption spectroscopy

    SciTech Connect

    Studer, F.; Houpert Ch. ); Toulemonde, M. ) Dartyge E. )

    1991-04-01

    Moessbauer and X-ray absorption spectroscopies of some crystallized iron oxides, Fe{sub 2}O{sub 3}, FePO{sub 4}, Fe{sub 3}PO{sub 7}, and SrMn{sub 1.85}Fe{sub 0.15}O{sub 2.5}, the garnet Y{sub 3}Fe{sub 5}O{sub 12}, and the barium hexaferrite BaFe{sub 12}O{sub 19} have been undertaken in order to look at the local order around iron in Y{sub 3}Fe{sub 5}O{sub 12} and BaFe{sub 12}O{sub 19} materials amorphized by irradiation with high energy (27 MeV/n) xenon ions accelerated by GANIL. Simulations of the Moessbauer spectra suggested the presence of fivefold coordinated iron in the amorphous irradiated compounds with a distribution of magnetic interactions due to the variations of the number of iron second neighbors. The XANES spectra at the Fe-K edge confirmed the fivefold coordination of iron in the amorphous ferrites, show that the local structure around iron appears to be similar although the original structures were different, and appear close to the one observed in the Fe{sub 3}PO{sub 7} compound in which iron stands in a trigonal bipyramidal environment.

  1. Simultaneous and direct determination of iron and nickel in biological solid samples by high-resolution continuum source graphite furnace atomic absorption spectrometry.

    PubMed

    Gómez-Nieto, Beatriz; Gismera, Ma Jesús; Sevilla, Ma Teresa; Procopio, Jesús R

    2013-11-15

    The simultaneous and direct determination of nickel and iron in plants and lichens has been investigated using high-resolution continuum source graphite furnace atomic absorption spectrometry. The primary resonance line for nickel at 232.003 nm and the adjacent secondary line for iron at 232.036 nm have been used for this purpose. The optimization of the experimental conditions was performed using a pine needles certified reference material (SRM 1575a). The influence of pyrolysis and atomization temperatures, the amount of solid sample introduced into the graphite furnace and the use of aqueous or solid standard for calibration were studied. The spectral interferences caused by absorption of the concomitants of the solid sample were detected and corrected using a least square algorithm. Aliquots of 0.1-1mg of the solid samples were weighed onto the solid sampling platforms and analyzed directly, without addition of any reagents. The limits of detection were 25 µg kg(-1) for nickel and 0.40 mg kg(-1) for iron and the precision, expressed as the relative standard deviation, ranged from 7% to 12%. The proposed method was used to determine both metals in different bioindicator samples with successful results.

  2. The influences of iron characteristics, operating conditions and solution chemistry on contaminants removal by zero-valent iron: A review.

    PubMed

    Sun, Yuankui; Li, Jinxiang; Huang, Tinglin; Guan, Xiaohong

    2016-09-01

    For successful application of a zero-valent iron (ZVI) system, of particular interest is the performance of ZVI under various conditions. The current review comprehensively summarizes the potential effects of the major influencing factors, such as iron intrinsic characteristics (e.g., surface area, iron impurities and oxide films), operating conditions (e.g., pH, dissolved oxygen, iron dosage, iron pretreatment, mixing conditions and temperature) and solution chemistry (e.g., anions, cations and natural organic matter) on the performance of ZVI reported in literature. It was demonstrated that all of the factors could exert significant effects on the ZVI performance toward contaminants removal, negatively or positively. Depending on the removal mechanisms of the respective contaminants and other environmental conditions, an individual variable may exhibit different effects. On the other hand, many of these influences have not been well understood or cannot be individually isolated in experimental or natural systems. Thus, more research is required in order to elucidate the exact roles and mechanisms of each factor in affecting the performance of ZVI. Furthermore, based on these understandings, future research may attempt to establish some feasible strategies to minimize the deteriorating effects and utilize the positive effects so as to improve the performance of ZVI.

  3. Pork meat increases iron absorption from a 5-day fully controlled diet when compared to a vegetarian diet with similar vitamin C and phytic acid content.

    PubMed

    Bach Kristensen, Mette; Hels, Ole; Morberg, Catrine; Marving, Jens; Bügel, Susanne; Tetens, Inge

    2005-07-01

    Meat increases absorption of non-haem iron in single-meal studies. The aim of the present study was to investigate, over a 5 d period, the potential increasing effect of consumption of pork meat in a whole diet on the fractional absorption of non-haem iron and the total absorption of iron, when compared to a vegetarian diet. A randomised cross-over design with 3 x 5 d whole-diet periods with diets containing Danish-produced meat, Polish-produced meat or a vegetarian diet was conducted. Nineteen healthy female subjects completed the study. All main meals in the meat diets contained 60 g of pork meat and all diets had high phytic acid content (1250 mumol/d). All main meals were extrinsically labelled with the radioactive isotope (59)Fe and absorption of iron was measured in a whole body counter. The non-haem iron absorption from the Danish meat diet was significantly higher compared to the vegetarian diet (P=0.031). The mean fractional absorption of non-haem iron was 7.9 (se1.1), 6.8 (se 1.0) and 5.3 (se 0.6) % for the Danish and Polish meat diets and vegetarian diet, respectively. Total absorption of iron was higher for both meat diets compared to the vegetarian diet (Danish meat diet: P=0.006, Polish meat diet: P=0.003). The absorption ratios of the present study were well in accordance with absorption ratios estimated using algorithms on iron bioavailability. Neither the meat diets nor the vegetarian diets fulfilled the estimated daily requirements of absorbed iron in spite of a meat intake of 180 g/d in the meat diets.

  4. Measurements of Electrical and Thermal Conductivity of Iron Under Earth's Core Conditions

    NASA Astrophysics Data System (ADS)

    Ohta, K.; Kuwayama, Y.; Shimizu, K.; Yagi, T.; Hirose, K.; Ohishi, Y.

    2014-12-01

    Secular cooling of the Earth's core induces the convection of the conductive liquid outer core, which generates the geomagnetic field, and the growth of the solid inner core. Since iron is the primary component of the Earth's core, the electrical and thermal conductivity of iron in both solid and liquid states are key pieces of information for estimating the transport properties of the core. We performed electrical and thermal conductivity measurements on iron under core conditions in a laser-heated diamond anvil cell. Our electrical conductivity measurements on iron clearly show resistivity saturation phenomena in iron under high pressure and high temperature conditions as predicted in a recent laboratory-based model for the core conductivity (Gomi et al., 2013). Direct measurements of thermal diffusivity of iron have been also preformed at high pressures by using the pulsed light heating thermoreflectance technique, which enable us to confirm the validity of the Wiedemann-Franz law toward transition metal under high pressure.

  5. Improvements in absorption systems for solar air conditioning

    SciTech Connect

    Grossman, G.; Bourne, J.R.; Ben-Dror, J.; Kimchi, Y.; Vardi, I.

    1981-01-01

    A theoretical evaluation is described of two design improvements made in a lithium bromide absorption chiller which increase its efficiency and operating range in solar applications. One is the addition of a solution preheater which allows for a considerable reduction in generator size and cost, and improves performance at part load. The other is the addition of an auxiliary generator which enables the chiller to operate at nominal capacity or higher at all times, while utilizing to a maximum the solar radiation available at the time, however small. This is an effective solution to the problem of back-up required in all solar powered systems. The evaluation has been performed by computer simulation and results are presented for the performance of the unit with different configurations of the above systems.

  6. Efficiency of inorganic and organic iron sources under iron depleted conditions in broilers.

    PubMed

    Shinde, P L; Ingale, S L; Choi, J Y; Kim, J S; Pak, S I; Chae, B J

    2011-10-01

    A total of 240 d-old male Ross chicks (average BW 37·15 ± 0·49 g) were fed on an iron (Fe)-deficient semi-synthetic diet (45 mg Fe/kg) from d 1-7 post hatching. At d 7, all 240 chicks (average BW 140·15 ± 1·4 g) with depleted Fe-stores were randomly assigned to three treatments on the basis of BW to study the efficiency of dietary inorganic and organic iron (Fe) utilisation. Each treatment had 4 replicates with 20 birds in each. Dietary treatments were: maize-soyabean meal-based basal diet, containing 103 to 106 mg Fe/kg (control); and basal diets supplemented with an additional 80 mg/kg Fe either from an inorganic (FeSO₄ · H₂O, 28% Fe) or organic (ferrous methionine chelate, 10% Fe) source. The starter and finisher diets were fed from d 7 to 21 and d 21 to 35, respectively. Improved body weight gain and FCR during finisher phase and overall study period; and greater DM and CP retention, and excreta Fe excretion, at d 20 to 21 and d 34 to 35; were observed in birds fed on Fe supplemented diets when compared with birds fed on control diet. At d 35, the RBC, Hb, haematocrit, and Fe concentration in plasma, tibia and liver were higher in birds fed on Fe supplemented diets than birds fed on the control diet. Supplementation of Fe in organic form resulted in greater Fe concentration in the tibia and liver and less Fe excretion at d 34 to 35, when compared with birds receiving inorganic Fe. These results indicate the necessity to supplement Fe in the commercial diets of broilers; however, organic and inorganic sources of Fe supplementation at 80 mg/kg were equally effective in improving performance, nutrient retention and haematological indices. In addition, Fe supplementation through an organic source seems to be more efficient in depositing Fe in the haemopoietic organs (liver and tibia) of birds under Fe depleted conditions.

  7. Morphology of biogenic iron oxides records microbial physiology and environmental conditions: toward interpreting iron microfossils.

    PubMed

    Krepski, S T; Emerson, D; Hredzak-Showalter, P L; Luther, G W; Chan, C S

    2013-09-01

    Despite the abundance of Fe and its significance in Earth history, there are no established robust biosignatures for Fe(II)-oxidizing micro-organisms. This limits our ability to piece together the history of Fe biogeochemical cycling and, in particular, to determine whether Fe(II)-oxidizers played a role in depositing ancient iron formations. A promising candidate for Fe(II)-oxidizer biosignatures is the distinctive morphology and texture of extracellular Fe(III)-oxyhydroxide stalks produced by mat-forming microaerophilic Fe(II)-oxidizing micro-organisms. To establish the stalk morphology as a biosignature, morphologic parameters must be quantified and linked to the microaerophilic Fe(II)-oxidizing metabolism and environmental conditions. Toward this end, we studied an extant model organism, the marine stalk-forming Fe(II)-oxidizing bacterium, Mariprofundus ferrooxydans PV-1. We grew cultures in flat glass microslide chambers, with FeS substrate, creating opposing oxygen/Fe(II) concentration gradients. We used solid-state voltammetric microelectrodes to measure chemical gradients in situ while using light microscopy to image microbial growth, motility, and mineral formation. In low-oxygen (2.7-28 μm) zones of redox gradients, the bacteria converge into a narrow (100 μm-1 mm) growth band. As cells oxidize Fe(II), they deposit Fe(III)-oxyhydroxide stalks in this band; the stalks orient directionally, elongating toward higher oxygen concentrations. M. ferrooxydans stalks display a narrow range of widths and uniquely biogenic branching patterns, which result from cell division. Together with filament composition, these features (width, branching, and directional orientation) form a physical record unique to microaerophilic Fe(II)-oxidizer physiology; therefore, stalk morphology is a biosignature, as well as an indicator of local oxygen concentration at the time of formation. Observations of filamentous Fe(III)-oxyhydroxide microfossils from a ~170 Ma marine Fe

  8. Viable, lyophilized lactobacilli do not increase iron absorption from a lactic acid-fermented meal in healthy young women, and no iron absorption occurs in the distal intestine.

    PubMed

    Bering, Stine; Sjøltov, Laila; Wrisberg, Seema S; Berggren, Anna; Alenfall, Jan; Jensen, Mikael; Højgaard, Liselotte; Tetens, Inge; Bukhave, Klaus

    2007-11-01

    Lactic acid-fermented foods have been shown to increase Fe absorption in human subjects, possibly by lowering pH, activation of phytases, production of organic acids, or by the viable lactic acid bacteria. In this study the effect of a heat-inactivated lactic acid-fermented oat gruel with and without added viable, lyophilized Lactobacillus plantarum 299v on non-haem Fe absorption was investigated. Furthermore, Fe absorption in the distal intestine was determined. In a randomized, double-blinded crossover trial eighteen healthy young women aged 22 (SD 3) years with low Fe status (serum ferritin < 30 microg/l) were served the two test gruels, extrinsically labelled with 59Fe and served with two enterocoated capsules (containing 55Fe(II) and 55Fe(III), respectively) designed to disintegrate in the ileum. The meals were consumed on two consecutive days, e.g. in the order AA followed by BB in a second period. Non-haem Fe absorption was determined from 59Fe whole-body retention and isotope activities in blood samples. The concentrations of Fe, lactate, phytate, and polyphenols, and the pH were similar in the heat-inactivated lactic acid-fermented oat gruels with and without added L. plantarum 299v, and no difference in Fe absorption was observed between the test gruels (1.4 and 1.3%, respectively). Furthermore, no absorption of Fe in the distal intestine was observed. In conclusion, addition of viable, lyophilized lactobacillus to a heat-inactivated lactic acid-fermented oat gruel does not affect Fe absorption, and no absorption seems to occur in the distal part of the intestine from low Fe bioavailability meals in these women.

  9. Simultaneous determination of cadmium, iron and tin in canned foods using high-resolution continuum source graphite furnace atomic absorption spectrometry.

    PubMed

    Leao, Danilo J; Junior, Mario M S; Brandao, Geovani C; Ferreira, Sergio L C

    2016-06-01

    A method was established to simultaneously determine cadmium, iron and tin in canned-food samples using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The quantification step has been performed using the primary line (228.802nm) for cadmium and the adjacent secondary lines (228.725nm and 228.668nm) for iron and tin, respectively. The selected chemical modifier was an acid solution that contained a mixture of 0.1% (w/v) Pd and 0.05% (w/v) Mg. The absorbance signals were measured based on the peak area using 3 pixels for cadmium and 5 pixels for iron and tin. Under these conditions, cadmium, iron and tin have been determined in canned-food samples using the external calibration technique based on aqueous standards, where the limits of quantification were 2.10ngg(-1) for cadmium, 1.95mgkg(-1) for iron and 3.00mgkg(-1) for tin, and the characteristic masses were 1.0pg for cadmium, 0.9ng for iron and 1.1ng for tin. The precision was evaluated using two solutions of each metal ion, and the results, which were expressed as the relative standard deviation (RSD%), were 3.4-6.8%. The method accuracy for cadmium and iron was confirmed by analyzing a certified reference material of apple leaves (NIST 1515), which was supplied by NIST. However, for tin, the accuracy was confirmed by comparing the results of the proposed method and another analytical technique (inductively coupled plasma optical emission spectrometry). The proposed procedure was applied to determine cadmium, iron and tin in canned samples of peeled tomato and sardine. Eleven samples were analyzed, and the analyte concentrations were 3.57-62.9ngg(-1), 2.68-31.48mgkg(-1) and 4.06-122.0mgkg(-1) for cadmium, iron and tin, respectively. In all analyzed samples, the cadmium and tin contents were lower than the permissible maximum levels for these metals in canned foods in the Brazilian legislation.

  10. Green tea ingestion by rats does not affect iron absorption but does alter the composition of the saliva proteome.

    PubMed

    Beverly, Ariel B; Zhu, Le; Fish, Tara L; Thannhauser, Theodore; Rutzke, Mike A; Miller, Dennis D

    2012-05-01

    We tested the hypothesis that rats adapt to the iron absorption inhibitory effects of tea by modifying the expression of salivary proteins. Thirty-six weanling rats were allocated into 6 groups. Two control groups were fed a semipurified diet containing 20 mg Fe(2+)/kg diet. Two groups were fed spray dried green tea infusion mixed into the diet (28.6 g tea/kg diet) and 2 groups were fed the control diet with a twice daily gavage of a tea solution (0.25 g tea/mL). Saliva samples were collected in 3 groups (control, gavage, and oral) on day 8 (acute) and in the remaining groups on day 31 (chronic). Iron absorption was assessed using a (58)Fe(3+) tracer administered on day 1 (acute) and day 24 (chronic). 2D gel electrophoresis and mass spectrometry were used to assess the composition of the saliva proteome. There was no significant difference in iron absorption between the 3 groups on either day 1 or day 24. Salivary proline-rich proteins and submandibular gland secretory protein increased to a greater extent in the oral group than in the gavage group, when compared to control, within the same exposure time period. Amylase, chitinase, deoxyribonuclease, cysteine-rich secretory protein 1, and parotid secretory protein all decreased to a greater extent in the oral tea group, compared to the control, within the same exposure time period. Our results show that green tea did not decrease iron absorption in rats but it did have a marked effect on the saliva proteome when given orally.

  11. Determination of the total iron content of used lubricating oils by atomic-absorption with use of emulsions.

    PubMed

    Salvador, A; de la Guardia, M; Berenguer, V

    1983-12-01

    A new method is proposed for the determination of the total iron content of used lubricating oils. It is based on treatment of the samples with a mixture of hydrofluoric and nitric acids (without destruction of the organic matter) and emulsification, followed by atomic-absorption measurement. This allows the use of aqueous standards and provides a simple, rapid, inexpensive and accurate method, that is not affected by the particle size of the solids in the oil.

  12. Biological iron oxidation by Gallionella spp. in drinking water production under fully aerated conditions.

    PubMed

    de Vet, W W J M; Dinkla, I J T; Rietveld, L C; van Loosdrecht, M C M

    2011-11-01

    Iron oxidation under neutral conditions (pH 6.5-8) may be a homo- or heterogeneous chemically- or a biologically-mediated process. The chemical oxidation is supposed to outpace the biological process under slightly alkaline conditions (pH 7-8). The iron oxidation kinetics and growth of Gallionella spp. - obligatory chemolithotrophic iron oxidizers - were assessed in natural, organic carbon-containing water, in continuous lab-scale reactors and full-scale groundwater trickling filters in the Netherlands. From Gallionella cell numbers determined by qPCR, balances were made for all systems. The homogeneous chemical iron oxidation occurred in accordance with the literature, but was retarded by a low water temperature (13 °C). The contribution of the heterogeneous chemical oxidation was, despite the presence of freshly formed iron oxyhydroxides, much lower than in previous studies in ultrapure water. This could be caused by the adsorption of natural organic matter (NOM) on the iron oxide surfaces. In the oxygen-saturated natural water with a pH ranging from 6.5 to 7.7, Gallionella spp. grew uninhibited and biological iron oxidation was an important, and probably the dominant, process. Gallionella growth was not even inhibited in a full-scale filter after plate aeration. From this we conclude that Gallionella spp. can grow under neutral pH and fully aerated conditions when the chemical iron oxidation is retarded by low water temperature and inhibition of the autocatalytic iron oxidation.

  13. Copper Deficiency Leads to Anemia, Duodenal Hypoxia, Upregulation of HIF-2α and Altered Expression of Iron Absorption Genes in Mice

    PubMed Central

    Matak, Pavle; Zumerle, Sara; Mastrogiannaki, Maria; El Balkhi, Souleiman; Delga, Stephanie; Mathieu, Jacques R. R.; Canonne-Hergaux, François; Poupon, Joel; Sharp, Paul A.; Vaulont, Sophie; Peyssonnaux, Carole

    2013-01-01

    Iron and copper are essential trace metals, actively absorbed from the proximal gut in a regulated fashion. Depletion of either metal can lead to anemia. In the gut, copper deficiency can affect iron absorption through modulating the activity of hephaestin - a multi-copper oxidase required for optimal iron export from enterocytes. How systemic copper status regulates iron absorption is unknown. Mice were subjected to a nutritional copper deficiency-induced anemia regime from birth and injected with copper sulphate intraperitoneally to correct the anemia. Copper deficiency resulted in anemia, increased duodenal hypoxia and Hypoxia inducible factor 2α (HIF-2α) levels, a regulator of iron absorption. HIF-2α upregulation in copper deficiency appeared to be independent of duodenal iron or copper levels and correlated with the expression of iron transporters (Ferroportin - Fpn, Divalent Metal transporter – Dmt1) and ferric reductase – Dcytb. Alleviation of copper-dependent anemia with intraperitoneal copper injection resulted in down regulation of HIF-2α-regulated iron absorption genes in the gut. Our work identifies HIF-2α as an important regulator of iron transport machinery in copper deficiency. PMID:23555700

  14. Selective hydrogen production from methanol with a defined iron pincer catalyst under mild conditions.

    PubMed

    Alberico, Elisabetta; Sponholz, Peter; Cordes, Christoph; Nielsen, Martin; Drexler, Hans-Joachim; Baumann, Wolfgang; Junge, Henrik; Beller, Matthias

    2013-12-23

    Molecularly well-defined iron pincer complexes promote the aqueous-phase reforming of methanol to carbon dioxide and hydrogen, which is of interest in the context of a methanol and hydrogen economy. For the first time, the use of earth-abundant iron complexes under mild conditions for efficient hydrogen generation from alcohols is demonstrated.

  15. Iron

    MedlinePlus

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  16. Absorption and impedance boundary conditions for phased geometrical-acoustics methods.

    PubMed

    Jeong, Cheol-Ho

    2012-10-01

    Defining accurate acoustical boundary conditions is of crucial importance for room acoustic simulations. In predicting sound fields using phased geometrical acoustics methods, both absorption coefficients and surface impedances of the boundary surfaces can be used, but no guideline has been developed on which boundary condition produces accurate results. In this study, various boundary conditions in terms of normal, random, and field incidence absorption coefficients and normal incidence surface impedance are used in a phased beam tracing model, and the simulated results are validated with boundary element solutions. Two rectangular rooms with uniform and non-uniform absorption distributions are tested. Effects of the neglect of reflection phase shift are also investigated. It is concluded that the impedance, random incidence, and field incidence absorption boundary conditions produce reasonable results with some exceptions at low frequencies for acoustically soft materials.

  17. [THE DIFFERENTIAL DIAGNOSTIC POSSIBILITIES IN EVALUATION OF IRON-DEFICIENT CONDITION UNDER ANEMIAS].

    PubMed

    Zubrikhina, G N; Blindar, V N; Matveeva, I I

    2016-03-01

    The article presents data concerning differential diagnostic possibilities of evaluation of genuine iron-deficient anemia and anemia of chronic diseases. The variety of mechanisms of development of anemia of chronic diseases is demonstrated, including effect of humoral inhibitors of erythropoiesis, disorder of iron metabolism at the expense of its redistribution into cells of macrophage system, suppression of erythropoiesis resulted in redistributed or functional iron deficiency. The data is presented concerning significance in diagnostic of anemia of chronic diseases of such factors as content of ferritin, dissolving receptors of transferrin and role of hepcidin protein in pathogenesis of anemia of chronic diseases. The analysis of scientific publications demonstrated that hepcidin is a negative regulator of iron metabolism. Under iron-deficient anemia its level in blood decreases that contribute to extensive absorption of iron in gastrointestinal tract. On the contrary, under anemia of chronic diseases its content drastically increases and results in blocking of iron transport everywhere, including internal epithelium, macrophages, placenta and other types of cells. The hyper-production of hepcidin during infection and inflammation is responsible for anemia of chronic diseases. The perspectives of development of pharmaceuticals decreasing level of hepcidin for treatment of anemia of chronic diseases is demonstrated.

  18. Structural determination of a short-lived excited iron(II) complex by picosecond x-ray absorption spectroscopy.

    PubMed

    Gawelda, Wojciech; Pham, Van-Thai; Benfatto, Maurizio; Zaushitsyn, Yuri; Kaiser, Maik; Grolimund, Daniel; Johnson, Steven L; Abela, Rafael; Hauser, Andreas; Bressler, Christian; Chergui, Majed

    2007-02-02

    Structural changes of the iron(II)-tris-bipyridine ([Fe(II)(bpy)(3)](2+)) complex induced by ultrashort pulse excitation and population of its short-lived (< or =0.6 ns) quintet high spin state have been detected by picosecond x-ray absorption spectroscopy. The structural relaxation from the high spin to the low spin state was followed over the entire lifetime of the excited state. A combined analysis of the x-ray-absorption near-edge structure and extended x-ray-absorption fine structure spectroscopy features delivers an Fe-N bond elongation of 0.2 A in the quintet state compared to the singlet ground state.

  19. MYB10 and MYB72 Are Required for Growth under Iron-Limiting Conditions

    PubMed Central

    Palmer, Christine M.; Hindt, Maria N.; Schmidt, Holger; Clemens, Stephan; Guerinot, Mary Lou

    2013-01-01

    Iron is essential for photosynthesis and is often a limiting nutrient for plant productivity. Plants respond to conditions of iron deficiency by increasing transcript abundance of key genes involved in iron homeostasis, but only a few regulators of these genes have been identified. Using genome-wide expression analysis, we searched for transcription factors that are induced within 24 hours after transferring plants to iron-deficient growth conditions. Out of nearly 100 transcription factors shown to be up-regulated, we identified MYB10 and MYB72 as the most highly induced transcription factors. Here, we show that MYB10 and MYB72 are functionally redundant and are required for plant survival in alkaline soil where iron availability is greatly restricted. myb10myb72 double mutants fail to induce transcript accumulation of the nicotianamine synthase gene NAS4. Both myb10myb72 mutants and nas4-1 mutants have reduced iron concentrations, chlorophyll levels, and shoot mass under iron-limiting conditions, indicating that these genes are essential for proper plant growth. The double myb10myb72 mutant also showed nickel and zinc sensitivity, similar to the nas4 mutant. Ectopic expression of NAS4 rescues myb10myb72 plants, suggesting that loss of NAS4 is the primary defect in these plants and emphasizes the importance of nicotianamine, an iron chelator, in iron homeostasis. Overall, our results provide evidence that MYB10 and MYB72 act early in the iron-deficiency regulatory cascade to drive gene expression of NAS4 and are essential for plant survival under iron deficiency. PMID:24278034

  20. Structural differences of oxidized iron-sulfur and nickel-iron cofactors in O2-tolerant and O2-sensitive hydrogenases studied by X-ray absorption spectroscopy.

    PubMed

    Sigfridsson, Kajsa G V; Leidel, Nils; Sanganas, Oliver; Chernev, Petko; Lenz, Oliver; Yoon, Ki-Seok; Nishihara, Hirofumi; Parkin, Alison; Armstrong, Fraser A; Dementin, Sébastien; Rousset, Marc; De Lacey, Antonio L; Haumann, Michael

    2015-02-01

    The class of [NiFe]-hydrogenases comprises oxygen-sensitive periplasmic (PH) and oxygen-tolerant membrane-bound (MBH) enzymes. For three PHs and four MBHs from six bacterial species, structural features of the nickel-iron active site of hydrogen turnover and of the iron-sulfur clusters functioning in electron transfer were determined using X-ray absorption spectroscopy (XAS). Fe-XAS indicated surplus oxidized iron and a lower number of ~2.7 Å Fe-Fe distances plus additional shorter and longer distances in the oxidized MBHs compared to the oxidized PHs. This supported a double-oxidized and modified proximal FeS cluster in all MBHs with an apparent trimer-plus-monomer arrangement of its four iron atoms, in agreement with crystal data showing a [4Fe3S] cluster instead of a [4Fe4S] cubane as in the PHs. Ni-XAS indicated coordination of the nickel by the thiol group sulfurs of four conserved cysteines and at least one iron-oxygen bond in both MBH and PH proteins. Structural differences of the oxidized inactive [NiFe] cofactor of MBHs in the Ni-B state compared to PHs in the Ni-A state included a ~0.05 Å longer Ni-O bond, a two times larger spread of the Ni-S bond lengths, and a ~0.1 Å shorter Ni-Fe distance. The modified proximal [4Fe3S] cluster, weaker binding of the Ni-Fe bridging oxygen species, and an altered localization of reduced oxygen species at the active site may each contribute to O2 tolerance.

  1. Absorption band III kinetics probe the picosecond heme iron motion triggered by nitric oxide binding to hemoglobin and myoglobin.

    PubMed

    Yoo, Byung-Kuk; Kruglik, Sergei G; Lamarre, Isabelle; Martin, Jean-Louis; Negrerie, Michel

    2012-04-05

    To study the ultrafast movement of the heme iron induced by nitric oxide (NO) binding to hemoglobin (Hb) and myoglobin (Mb), we probed the picosecond spectral evolution of absorption band III (∼760 nm) and vibrational modes (iron-histidine stretching, ν(4) and ν(7) in-plane modes) in time-resolved resonance Raman spectra. The time constants of band III intensity kinetics induced by NO rebinding (25 ps for hemoglobin and 40 ps for myoglobin) are larger than in Soret bands and Q-bands. Band III intensity kinetics is retarded with respect to NO rebinding to Hb and to Mb. Similarly, the ν((Fe-His)) stretching intensity kinetics are retarded with respect to the ν(4) and ν(7) heme modes and to Soret absorption. In contrast, band III spectral shift kinetics do not coincide with band III intensity kinetics but follows Soret kinetics. We concluded that, namely, the band III intensity depends on the heme iron out-of-plane position, as theoretically predicted ( Stavrov , S. S. Biopolymers 2004 , 74 , 37 - 40 ).

  2. Decoupling of arsenic and iron release from ferrihydrite suspension under reducing conditions: a biogeochemical model

    PubMed Central

    Burnol, André; Garrido, Francis; Baranger, Philippe; Joulian, Catherine; Dictor, Marie-Christine; Bodénan, Françoise; Morin, Guillaume; Charlet, Laurent

    2007-01-01

    High levels of arsenic in groundwater and drinking water are a major health problem. Although the processes controlling the release of As are still not well known, the reductive dissolution of As-rich Fe oxyhydroxides has so far been a favorite hypothesis. Decoupling between arsenic and iron redox transformations has been experimentally demonstrated, but not quantitatively interpreted. Here, we report on incubation batch experiments run with As(V) sorbed on, or co-precipitated with, 2-line ferrihydrite. The biotic and abiotic processes of As release were investigated by using wet chemistry, X-ray diffraction, X-ray absorption and genomic techniques. The incubation experiments were carried out with a phosphate-rich growth medium and a community of Fe(III)-reducing bacteria under strict anoxic conditions for two months. During the first month, the release of Fe(II) in the aqueous phase amounted to only 3% to 10% of the total initial solid Fe concentration, whilst the total aqueous As remained almost constant after an initial exchange with phosphate ions. During the second month, the aqueous Fe(II) concentration remained constant, or even decreased, whereas the total quantity of As released to the solution accounted for 14% to 45% of the total initial solid As concentration. At the end of the incubation, the aqueous-phase arsenic was present predominately as As(III) whilst X-ray absorption spectroscopy indicated that more than 70% of the solid-phase arsenic was present as As(V). X-ray diffraction revealed vivianite Fe(II)3(PO4)2.8H2O in some of the experiments. A biogeochemical model was then developed to simulate these aqueous- and solid-phase results. The two main conclusions drawn from the model are that (1) As(V) is not reduced during the first incubation month with high Eh values, but rather re-adsorbed onto the ferrihydrite surface, and this state remains until arsenic reduction is energetically more favorable than iron reduction, and (2) the release of As

  3. Preparation and characterization of novel glass-ceramic tile with microwave absorption properties from iron ore tailings

    NASA Astrophysics Data System (ADS)

    Yao, Rui; Liao, SongYi; Dai, ChangLu; Liu, YuChen; Chen, XiaoYu; Zheng, Feng

    2015-03-01

    A novel glass-ceramic tile consisting of one glass-ceramic layer (GC) attaining microwave absorption properties atop ceramic substrate was prepared through quench-heat treatment route derived from iron ore tailings (IOTs) and commercial raw materials (purity range 73-99%). X-ray diffraction (XRD), SEM, Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Physical property measurement system (PPMS) and Vector network analyzer (VNA) measurements were carried out to investigate phase, microstructure, magnetic and microwave absorption aspects of the glass-ceramic layer. Roughly 80.6±1.7 wt% borosilicate glass and 19.4±1.7 wt% spinel ferrite with chemical formula of (Zn2+0.17Fe3+0.83)[Fe3+1.17Fe2+0.06Ni2+0.77]O4 were found among the tested samples. Absorption of Electromagnetic wave by 3 mm thick glass-ceramic layer at frequency of 2-18 GHz reached peak reflection loss (RL) of -17.61 dB (98.27% microwave absorption) at 10.31 GHz. Altering the thickness of the glass-ceramic layer can meet the requirements of different level of microwave absorption.

  4. The chemical environment of iron in mineral fibres. A combined X-ray absorption and Mössbauer spectroscopic study.

    PubMed

    Pollastri, Simone; D'Acapito, Francesco; Trapananti, Angela; Colantoni, Ivan; Andreozzi, Giovanni B; Gualtieri, Alessandro F

    2015-11-15

    Although asbestos represents today one of the most harmful contaminant on Earth, in 72% of the countries worldwide only amphiboles are banned while controlled use of chrysotile is allowed. Uncertainty on the potential toxicity of chrysotile is due to the fact that the mechanisms by which mineral fibres induces cyto- and geno-toxic damage are still unclear. We have recently started a long term project aimed at the systematic investigation of the crystal-chemistry, bio-interaction and toxicity of the mineral fibres. This work presents a systematic structural investigation of iron in asbestos and erionite (considered the most relevant mineral fibres of social and/or economic-industrial importance) using synchrotron X-ray absorption and Mössbauer spectroscopy. In all investigated mineral fibres, iron in the bulk structure is found in octahedral sites and can be made available at the surface via fibre dissolution. We postulate that the amount of hydroxyl radicals released by the fibers depends, among other factors, upon their dissolution rate; in relation to this, a ranking of ability of asbestos fibres to generate hydroxyl radicals, resulting from available surface iron, is advanced: amosite > crocidolite ≈ chrysotile > anthophyllite > tremolite. Erionite, with a fairly high toxicity potential, contains only octahedrally coordinated Fe(3+). Although it needs further experimental evidence, such available surface iron may be present as oxide nanoparticles coating and can be a direct cause of generation of hydroxyl radicals when such coating dissolves.

  5. Formation Sequences of Iron Minerals in the Acidic Alteration Products and Variation of Hydrothermal Fluid Conditions

    NASA Astrophysics Data System (ADS)

    Isobe, H.; Yoshizawa, M.

    2008-12-01

    Iron minerals have important role in environmental issues not only on the Earth but also other terrestrial planets. Iron mineral species related to alteration products of primary minerals with surface or subsurface fluids are characterized by temperature, acidity and redox conditions of the fluids. We can see various iron- bearing alteration products in alteration products around fumaroles in geothermal/volcanic areas. In this study, zonal structures of iron minerals in alteration products of the geothermal area are observed to elucidate temporal and spatial variation of hydrothermal fluids. Alteration of the pyroxene-amphibole andesite of Garan-dake volcano, Oita, Japan occurs by the acidic hydrothermal fluid to form cristobalite leaching out elements other than Si. Hand specimens with unaltered or weakly altered core and cristobalite crust show various sequences of layers. XRD analysis revealed that the alteration degree is represented by abundance of cristobalite. Intermediately altered layers are characterized by occurrence including alunite, pyrite, kaolinite, goethite and hematite. A specimen with reddish brown core surrounded by cristobalite-rich white crust has brown colored layers at the boundary of core and the crust. Reddish core is characterized by occurrence of crystalline hematite by XRD. Another hand specimen has light gray core, which represents reduced conditions, and white cristobalite crust with light brown and reddish brown layers of ferric iron minerals between the core and the crust. On the other hand, hornblende crystals, typical ferrous iron-bearing mineral of the host rock, are well preserved in some samples with strongly decolorized cristobalite-rich groundmass. Hydrothermal alteration experiments of iron-rich basaltic material shows iron mineral species depend on acidity and temperature of the fluid. Oxidation states of the iron-bearing mineral species are strongly influenced by the acidity and redox conditions. Variations of alteration

  6. Is iron at the Earth's core conditions hcp-structured?

    SciTech Connect

    Dubrovinsky, L; Dubrovinskaia, N; Prakapenka, V

    2012-02-07

    Iron is the main component of the Earth's core and its structure and properties are important for interpretation of geophysical observations and modeling dynamics of the core. We argue that the diffraction lines in the high temperature high pressure X-ray diffraction pattern, presented by Tateno et al., 2010 and interpreted as those of solely hot hcp-Fe, correspond indeed to the insufficiently heated part of the sample. We show that observed diffraction spots are either due to bcc-Fe or carbides.

  7. Iron distances in hemoglobin: comparison of x-ray crystallographic and extended x-ray absorption fine structure studies

    SciTech Connect

    Fermi, G.; Perutz, M.F.; Shulman, R.G.

    1987-09-01

    A comparison is presented of the structures obtained around the iron atom in deoxyhemoglobin (Hb). The data come from extended x-ray absorption fine structure (EXAFS) studies of the iron, which gave Fe-porphyrin nitrogen distances of 2.06 +- 0.01 A, and from the most recent high-resolution x-ray crystallographic study, which gave exactly the same distance-2.06 +- 0.02 A. The distance of Fe above the plane of the porphyrin nitrogens was 0.38 +- 0.04 A from the crystallographic study; this value is not far from the upper limit of the distances 0.20 +- /sub 0.20//sup 0.10/ A calculated from the EXAFS experiment by triangulation. These distances above the nitrogen plane are shorter than those estimated in the earliest x-ray structures

  8. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1987-01-01

    Laboratory measurements were conducted to evaluate properties of atmospheric gases under simulated conditions for the outer planets. A significant addition to this effort was the capability to make such measurements at millimeter wavelengths. Measurements should soon be completed on the millimeter wave absorption from ammonia under Jovian conditions. Also studied will be the feasibility of measuring the microwave and millimeter wave properties of phosphine (PH3) under simulated Jovian conditions. Further analysis and application of the laboratory results to microwave and millimeter wave absorption data for the outer planet, such as Voyager Radio Occultation experiments, will be pursued.

  9. X-Ray absorption in homogeneous catalysis research: the iron-catalyzed Michael addition reaction by XAS, RIXS and multi-dimensional spectroscopy.

    PubMed

    Bauer, Matthias; Gastl, Christoph

    2010-06-07

    A survey over X-ray absorption methods in homogeneous catalysis research is given with the example of the iron-catalyzed Michael addition reaction. A thorough investigation of the catalytic cycle was possible by combination of conventional X-ray absorption spectroscopy (XAS), resonant inelastic X-ray scattering (RIXS) and multi-dimensional spectroscopy. The catalytically active compound formed in the first step of the Michael reaction of methyl vinyl ketone with 2-oxocyclopentanecarboxylate (1) could be elucidated in situ by RIXS spectroscopy, and the reduced catalytic activity of FeCl(3) x 6 H(2)O (2) compared to Fe(ClO(4))(3) x 9 H(2)O (3) could be further explained by the formation of a [Fe(III)Cl(4)(-)](3)[Fe(III)(1-H)(2)(H(2)O)(2)(+)][H(+)](2) complex. Chloride was identified as catalyst poison with a combined XAS-UV/vis study, which revealed that Cl(-) binds quantitatively to the available iron centers that are deactivated by formation of [FeCl(4)(-)]. Operando studies in the course of the reaction of methyl vinyl ketone with 1 by combined XAS-Raman spectroscopy allowed the exclusion of changes in the oxidation state and the octahedral geometry at the iron site; a reaction order of two with respect to methyl vinyl ketone and a rate constant of k = 1.413 min(-2) were determined by analysis of the C=C and C=O vibration band. Finally, a dedicated experimental set-up for three-dimensional spectroscopic studies (XAS, UV/vis and Raman) of homogeneous catalytic reactions under laboratory conditions, which emerged from the discussed investigations, is presented.

  10. Near infrared iron absorption bands: Applications to geologic mapping and mineral exploration

    NASA Technical Reports Server (NTRS)

    Rowan, L. C.

    1972-01-01

    A spectroscopic analysis of the difference in reflectance of iron-rich and iron-poor minerals was made. Attempts were made to use these minima contrast in geological mapping and metallic mineral exploration of large areas from near infrared and visible satellite images. Data cover pertinent laboratory spectroscopic investigations, applications of spectral differences to the discrimination of two important metamorphic rock types, and mineral exploration by aircraft in Beartooth Mountains, Montana.

  11. Threading on ADI Cast Iron, Developing Tools and Conditions

    NASA Astrophysics Data System (ADS)

    Elósegui, I.; de Lacalle, L. N. López

    2011-01-01

    The present work is focussed on the improvement of the design and performance of the taps used for making threaded holes in ADI (Austempered Ductile Iron). It is divided in two steps: a) The development of a method valid to compare the taps wear without reaching the end of their life, measuring the required torque to make one threaded hole, after having made previously a significant number of threaded holes. The tap wear causes some teeth geometrical changes, that supposes an increase in the required torque and axial force. b) The taps wear comparison method is open to apply on different PVD coated taps, AlTiN, AlCrSiN, AlTiSiN, , and to different geometries.

  12. Low-potential iron-sulfur centers in photosystem I: an X-ray absorption spectroscopy study.

    PubMed

    McDermott, A E; Yachandra, V K; Guiles, R D; Britt, R D; Dexheimer, S L; Sauer, K; Klein, M P

    1988-05-31

    We have measured the X-ray absorption spectra of Fe in photosystem I (PS I) preparations from spinach and a thermophilic cyanobacterium, Synechococcus sp., to characterize structures of the Fe complexes that function as electron acceptors in PS I. These acceptors include centers A and B, which are probably typical [4Fe-4S] ferredoxins, and X. The structure of X is not known, but its electron paramagnetic resonance (EPR) spectrum has generated the suggestions that it is either a [2Fe-2S] or [4Fe-4S] ferredoxin or an Fe-quinone species. The iron X-ray absorption K-edge and iron extended X-ray absorption fine structure (EXAFS) spectra reveal that essentially all of the 11-14 Fe atoms present in the reaction center are present in the form of Fe-S centers and that not more than 1 atom out of 12 could be octahedral or oxygen-coordinated Fe. This suggests that, besides A and B, additional Fe-S clusters are present which are likely to be X. Our EXAFS spectra cannot be simulated adequately by a mixture of [4Fe-4S] ferredoxins with typical bond lengths and disorder parameters because the amplitude of Fe backscattering is small; however, excellent simulations of the data are consistent with a mixture of [2Fe-2S] ferredoxins and [4Fe-4S] ferredoxins, or with unusually distorted [4Fe-4S] clusters. We presume that the [2Fe-2S] or distorted [4Fe-4S] centers are X. The X-ray absorption spectra of PS I preparations from Synechococcus and spinach are essentially indistinguishable.

  13. Comparison of colorimetry and electrothermal atomic absorption spectroscopy for the quantification of non-transferrin bound iron in human sera.

    PubMed

    Jittangprasert, Piyada; Wilairat, Prapin; Pootrakul, Pensri

    2004-12-01

    This paper describes a comparison of two analytical techniques, one employing bathophenanthrolinedisulfonate (BPT), a most commonly-used reagent for Fe (II) determination, as chromogen and an electrothermal atomic absorption spectroscopy (ETAAS) for the quantification of non-transferrin bound iron (NTBI) in sera from thalassemic patients. Nitrilotriacetic acid (NTA) was employed as the ligand for binding iron from low molecular weight iron complexes present in the serum but without removing iron from the transferrin protein. After ultrafiltration the Fe (III)-NTA complex was then quantified by both methods. Kinetic study of the rate of the Fe (II)-BPT complex formation for various excess amounts of NTA ligand was also carried out. The kinetic data show that a minimum time duration (> 60 minutes) is necessary for complete complex formation when large excess of NTA is used. Calibration curves given by colorimetric and ETAAS methods were linear over the range of 0.15-20 microM iron (III). The colorimetric and ETAAS methods exhibited detection limit (3sigma) of 0.13 and 0.14 microM, respectively. The NTBI concentrations from 55 thalassemic serum samples measured employing BPT as chromogen were statistically compared with the results determined by ETAAS. No significant disagreement at 95% confidence level was observed. It is, therefore, possible to select any one of these two techniques for determination of NTBI in serum samples of thalassemic patients. However, the colorimetric procedure requires a longer analysis time because of a slow rate of exchange of NTA ligand with BPT, leading to the slow rate of formation of the colored complex.

  14. Photooxidation and photoaquation of iron hexacyanide in aqueous solution: A picosecond X-ray absorption study.

    PubMed

    Reinhard, M; Penfold, T J; Lima, F A; Rittmann, J; Rittmann-Frank, M H; Abela, R; Tavernelli, I; Rothlisberger, U; Milne, C J; Chergui, M

    2014-03-01

    We present a picosecond Fe K-edge absorption study of photoexcited ferrous and ferric hexacyanide in water under 355 and 266 nm excitation. Following 355 nm excitation, the transient spectra for the ferrous and ferric complexes exhibit a red shift of the edge reflecting an increased electron density at the Fe atom. For the former, an enhanced pre-edge transition is also observed. These observations are attributed to the aquated [Fe(CN)5OH2](3-) species, based on quantum chemical calculations which also provide structural parameters. Upon 266 nm excitation of the ferric complex, a transient reminiscent of the aquated species is observed (appearance of a pre-edge feature and red shift of the edge) but it is different from that obtained under 355 nm excitation. This points to a new reaction channel occurring through an intermediate state lying between these two excitation energies. Finally, 266 nm excitation of the ferrous species is dominated by the photooxidation channel with formation of the ferric complex as main photoproduct. However, we observe an additional minor photoproduct, which is identical to the 266 nm generated photoproduct of the ferric species, suggesting that under our experimental conditions, the pump pulse photooxidises the ferrous complex and re-excites the primary ferric photoproduct.

  15. Photooxidation and photoaquation of iron hexacyanide in aqueous solution: A picosecond X-ray absorption study

    PubMed Central

    Reinhard, M.; Penfold, T. J.; Lima, F. A.; Rittmann, J.; Rittmann-Frank, M. H.; Abela, R.; Tavernelli, I.; Rothlisberger, U.; Milne, C. J.; Chergui, M.

    2014-01-01

    We present a picosecond Fe K-edge absorption study of photoexcited ferrous and ferric hexacyanide in water under 355 and 266 nm excitation. Following 355 nm excitation, the transient spectra for the ferrous and ferric complexes exhibit a red shift of the edge reflecting an increased electron density at the Fe atom. For the former, an enhanced pre-edge transition is also observed. These observations are attributed to the aquated [Fe(CN)5OH2]3− species, based on quantum chemical calculations which also provide structural parameters. Upon 266 nm excitation of the ferric complex, a transient reminiscent of the aquated species is observed (appearance of a pre-edge feature and red shift of the edge) but it is different from that obtained under 355 nm excitation. This points to a new reaction channel occurring through an intermediate state lying between these two excitation energies. Finally, 266 nm excitation of the ferrous species is dominated by the photooxidation channel with formation of the ferric complex as main photoproduct. However, we observe an additional minor photoproduct, which is identical to the 266 nm generated photoproduct of the ferric species, suggesting that under our experimental conditions, the pump pulse photooxidises the ferrous complex and re-excites the primary ferric photoproduct. PMID:26798775

  16. Hydroxypropyl-distarch phosphate from Tapioca starch reduces zinc and iron absorption, but not calcium and magnesium absorption, in rats.

    PubMed

    Kishida, T; Nakai, Y; Ebihara, K

    2001-02-01

    Male rats were fed a fiber-free, purified diet containing either gelatinized tapioca starch that was not modified chemically (TS, 50 g/kg diet) or gelatinized chemically modified tapioca starch (CMS, 50 g/kg) for 21 d. TS was used as the control. The six kinds of gelatinized hydroxypropyl distarch phosphate (HDP) from tapioca with two different degrees of substitution (DS) and three different degrees of cross-linking (DC) were used as CMS sources. The wet weight and moisture of fecal output of the rats fed HDP with higher DS were 100 and 20% greater than that in the control rats, respectively. The weights of cecal wall and cecal contents were also 30 and 50% higher in the rats fed HDP with higher DS than those in the control rats. The pH of the cecal contents was more acidic in the rats fed HDP with higher DS than that in the control rats. Fecal excretion of bile acids was 40% higher in the rats fed HDP with higher DS than in the control rats. These effects of HDP were only slightly affected by the DC. The plasma cholesterol concentration was 16% lower in the rats fed HDP with higher DS and highest DC than in the control rats. The concentrations of liver lipids and plasma triglycerides and the cecal pool of organic acids were not affected by diet. The apparent absorptions of Ca and Mg were not affected by diet, but those of Zn and Fe were 75 and 70% lower in the rats fed HDP with higher DS than in the control rats. These results suggest that the physiological effects of HDP depend on the DS but not on the DC.

  17. Experimental determination of the electrical resistivity of iron at Earth's core conditions.

    PubMed

    Ohta, Kenji; Kuwayama, Yasuhiro; Hirose, Kei; Shimizu, Katsuya; Ohishi, Yasuo

    2016-06-02

    Earth continuously generates a dipole magnetic field in its convecting liquid outer core by a self-sustained dynamo action. Metallic iron is a dominant component of the outer core, so its electrical and thermal conductivity controls the dynamics and thermal evolution of Earth's core. However, in spite of extensive research, the transport properties of iron under core conditions are still controversial. Since free electrons are a primary carrier of both electric current and heat, the electron scattering mechanism in iron under high pressure and temperature holds the key to understanding the transport properties of planetary cores. Here we measure the electrical resistivity (the reciprocal of electrical conductivity) of iron at the high temperatures (up to 4,500 kelvin) and pressures (megabars) of Earth's core in a laser-heated diamond-anvil cell. The value measured for the resistivity of iron is even lower than the value extrapolated from high-pressure, low-temperature data using the Bloch-Grüneisen law, which considers only the electron-phonon scattering. This shows that the iron resistivity is strongly suppressed by the resistivity saturation effect at high temperatures. The low electrical resistivity of iron indicates the high thermal conductivity of Earth's core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old. Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core.

  18. Experimental determination of the electrical resistivity of iron at Earth’s core conditions

    NASA Astrophysics Data System (ADS)

    Ohta, Kenji; Kuwayama, Yasuhiro; Hirose, Kei; Shimizu, Katsuya; Ohishi, Yasuo

    2016-06-01

    Earth continuously generates a dipole magnetic field in its convecting liquid outer core by a self-sustained dynamo action. Metallic iron is a dominant component of the outer core, so its electrical and thermal conductivity controls the dynamics and thermal evolution of Earth’s core. However, in spite of extensive research, the transport properties of iron under core conditions are still controversial. Since free electrons are a primary carrier of both electric current and heat, the electron scattering mechanism in iron under high pressure and temperature holds the key to understanding the transport properties of planetary cores. Here we measure the electrical resistivity (the reciprocal of electrical conductivity) of iron at the high temperatures (up to 4,500 kelvin) and pressures (megabars) of Earth’s core in a laser-heated diamond-anvil cell. The value measured for the resistivity of iron is even lower than the value extrapolated from high-pressure, low-temperature data using the Bloch-Grüneisen law, which considers only the electron-phonon scattering. This shows that the iron resistivity is strongly suppressed by the resistivity saturation effect at high temperatures. The low electrical resistivity of iron indicates the high thermal conductivity of Earth’s core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old. Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core.

  19. Microwave Absorption Properties of Iron Nanoparticles Prepared by Ball-Milling

    NASA Astrophysics Data System (ADS)

    Chu, Xuan T. A.; Ta, Bach N.; Ngo, Le T. H.; Do, Manh H.; Nguyen, Phuc X.; Nam, Dao N. H.

    2016-05-01

    A nanopowder of iron was prepared using a high-energy ball milling method, which is capable of producing nanoparticles at a reasonably larger scale compared to conventional chemical methods. Analyses using x-ray diffraction and magnetic measurements indicate that the iron nanoparticles are a single phase of a body-centered cubic structure and have quite stable magnetic characteristics in the air. The iron nanoparticles were then mixed with paraffin and pressed into flat square plates for free-space microwave transmission and reflection measurements in the 4-8 GHz range. Without an Al backing plate, the Fe nanoparticles seem to only weakly absorb microwave radiation. The reflected signal S 11 drops to zero and a very large negative value of reflection loss ( RL) are observed for Al-backed samples, suggesting the existence of a phase matching resonance near frequency f ˜ 6 GHz.

  20. Dielectronic recombination measurements of iron M-shell ions motivated by active galactic nuclei X-ray absorption features

    NASA Astrophysics Data System (ADS)

    Lukic, V. D.; Schnell, M.; Savin, D. W.; Brandau, C.; Schmidt, E. W.; Bohm, S.; Muller, A.; Schippers, S.; Lestinsky, M.; Sprenger, F.; Wolf, A.; Altun, Z.; Badnell, N. R.

    2008-07-01

    XMM-Newton and Chandra observations of active galactic nuclei (AGN) show rich spectra of X-ray absorption lines. These observations have detected a broad unresolved transition array (UTA) between 15-17 A. This is attributed to inner-shell photoexcitation of M-shell iron ions. Modeling these UTA features is currently limited by uncertainties in the low-temperature dielectronic recombination (DR) data for M-shell iron. In order to resolve this issue, and to provide reliable iron M-shell DR data for plasma modeling, we are carrying out a series of laboratory measurements using the heavy-ion Test Storage Ring (TSR) at the Max-Plank-Institute for Nuclear Physics in Heidelberg, Germany. Currently, laboratory measurements of low temperature DR can only be performed at storage rings. We use the DR data obtained at TSR, to calculate rate coefficients for plasma modeling and to benchmark theoretical DR calculations. At temperatures where these ions are predicted to form in photoionized gas, we find a significant discrepancy between our experimental results and previously recommended DR rate coefficients. Here we report our recent experimental results for DR of Mg-like Fe XV forming Al-like Fe XIV.

  1. EPO-dependent induction of erythroferrone drives hepcidin suppression and systematic iron absorption under phenylhydrazine-induced hemolytic anemia.

    PubMed

    Jiang, Xingkang; Gao, Ming; Chen, Yue; Liu, Jing; Qi, Shiyong; Ma, Juan; Zhang, Zhihong; Xu, Yong

    2016-05-01

    Hemolytic anemia is a common form of anemia due to hemolysis, resulting in disordered iron homeostasis. In this study, a dose of 40mg/kg phenylhydrazine (PHZ) was injected into mice to successfully establish a pronounced anemia animal model, which resulted in stress erythropoiesis and iron absorption. We found that serum erythropoietin (EPO) concentration was dramatically elevated by nearly 5000-fold for the first 2days, and then drop to the basal level on day 6 after PHZ injection. Mirrored with serum EPO concentration, the mRNA expression of erythroferrone (ERFE) was rapidly increased in the bone marrow and spleen 3days after injection of PHZ, and then gradually decreased but was still higher than baseline on day 6. In addition, we also found that the hepcidin mRNA levels were gradually reduced almost up to 8-fold on day 5, and then was ameliorated compared to the untreated control. Mechanistic investigation manifested that the increase of serum EPO essentially determined the induction of ERFE expression particular at the first 3days after PHZ treatment. Lentiviral mediated ERFE knockdown significantly restrained hepcidin suppression under PHZ treatment. Thus, our data unearthed EPO-dependent ERFE expression acts as an erythropoiesis-driven regulator of iron metabolism under PHZ-induced hemolytic anemia.

  2. Moisture Absorption of Plant Fiber under Annealed, Bleached and Mercerized Condition

    SciTech Connect

    Saikia, Dip

    2010-06-29

    The water absorptions behaviors of the okra fibers, which are available in north east India, were studied under ambient, annealed, bleached and mercerized conditions by using ordinary gravimetric absorption method. The gains in moisture content in the fibers due to water absorption as well as their capillarity at constant relative humidity were measured as a function of exposure time. In order to ascertain the environment factor of utility of the fibers, the moisture regain of the fibers were determined at different relative air humidity. The water yielding capacity of okra fibers was also determined in order to understand their drying properties. The diffusion coefficients of the sorption process of the fibers under ambient, annealed, bleached and mercerized conditions were estimated.

  3. Moisture Absorption of Plant Fiber under Annealed, Bleached and Mercerized Condition

    NASA Astrophysics Data System (ADS)

    Saikia, Dip

    2010-06-01

    The water absorptions behaviors of the okra fibers, which are available in north east India, were studied under ambient, annealed, bleached and mercerized conditions by using ordinary gravimetric absorption method. The gains in moisture content in the fibers due to water absorption as well as their capillarity at constant relative humidity were measured as a function of exposure time. In order to ascertain the environment factor of utility of the fibers, the moisture regain of the fibers were determined at different relative air humidity. The water yielding capacity of okra fibers was also determined in order to understand their drying properties. The diffusion coefficients of the sorption process of the fibers under ambient, annealed, bleached and mercerized conditions were estimated.

  4. Saturation of electrical resistivity of solid iron at Earth's core conditions.

    PubMed

    Pozzo, Monica; Alfè, Dario

    2016-01-01

    We report on the temperature dependence of the electrical resistivity of solid iron at high pressure, up to and including conditions likely to be found at the centre of the Earth. We have extended some of the calculations of the resistivities of pure solid iron we recently performed at Earth's core conditions (Pozzo et al. in Earth Planet Sci Lett 393:159-164, 2014) to lower temperature. We show that at low temperature the resistivity increases linearly with temperature, and saturates at high temperature. This saturation effect is well known as the Mott-Ioffe-Regel limit in metals, but has been largely ignored to estimate the resistivity of iron at Earth's core conditions. Recent experiments (Gomi et al. in Phys Earth Planet Int 224:88-103, 2013) coupled new high pressure data and saturation to predict the resitivity of iron and iron alloys at Earth's core conditions, and reported values up to three times lower than previous estimates, confirming recent first principles calculations (de Koker et al. in Proc Natl Acad Sci 109:4070-4073, 2012; Pozzo et al. in Nature 485:355-358, 2012, Phys Rev B 87:014110-10, 2013, Earth Planet Sci Lett 393:159-164, 2014; Davies et al. in Nat Geosci 8:678-685, 2015). The present results support the saturation effect idea.

  5. Photochemical decomposition of perfluorooctanoic acid mediated by iron in strongly acidic conditions.

    PubMed

    Ohno, Masaki; Ito, Masataka; Ohkura, Ryouichi; Mino A, Esteban R; Kose, Tomohiro; Okuda, Tetsuji; Nakai, Satoshi; Kawata, Kuniaki; Nishijima, Wataru

    2014-03-15

    The performance of a ferric ion mediated photochemical process for perfluorooctanoic acid (PFOA) decomposition in strongly acidic conditions of pH 2.0 was evaluated in comparison with those in weakly acidic conditions, pH 3.7 or pH 5.0, based on iron species composition and ferric ion regeneration. Complete decomposition of PFOA under UV irradiation was confirmed at pH 2.0, whereas perfluoroheptanoic acid (PFHpA) and other intermediates were accumulated in weakly acidic conditions. Iron states at each pH were evaluated using a chemical equilibrium model, Visual MINTEQ. The main iron species at pH 2.0 is Fe(3+) ion. Although Fe(3+) ion is consumed and is transformed to Fe(2+) ion by photochemical decomposition of PFOA and its intermediates, the produced Fe(2+) ion will change to Fe(3+) ion to restore chemical equilibrium. Continuous decomposition will occur at pH 2.0. However, half of the iron cannot be dissolved at pH 3.7. The main species of dissolved iron is Fe(OH)(2+). At pH 3.7 or higher pH, Fe(3+) ion will only be produced from the oxidation of Fe(2+) ion by hydroxyl radical produced by Fe(OH)(2+) under UV irradiation. These different mechanisms of Fe(3+) regeneration that prevail in strongly and weakly acidic conditions will engender different performances of the ferric ion.

  6. Next-Generation Biomarkers for Iron Status.

    PubMed

    Drakesmith, Hal

    2016-01-01

    Iron is needed for oxygen transport, muscle activity, mitochondrial function, DNA synthesis, and sensing of hypoxia. The hierarchical master determinant of dietary iron absorption and iron distribution within the body is the peptide hormone hepcidin. Hepcidin itself is regulated by a combination of signals derived from iron stores, inflammation, and erythropoietic expansion. Iron deficiency and iron deficiency anemia are common and important conditions that can be treated with iron preparations. However, other factors besides iron deficiency can cause anemia, especially inflammation, which responds poorly to iron treatment, and inherited disorders of red blood cells, which are associated with accumulation of excess pathogenic iron. Assessment of iron status is challenging, and indices such as serum ferritin, soluble transferrin receptor, and zinc protoporphyrin have specific weaknesses. Moreover, a diagnosis of iron deficiency or iron deficiency anemia is most useful if the diagnosis also leads to effective treatment. Low levels of hepcidin allow iron absorption and effective iron incorporation into red blood cells. The best 'biomarker' to guide treatment may therefore be the physiological 'determinant' of iron utilization. Iron is also important in transplantation medicine and influences clinical outcome of arterial pulmonary hypertension; here too, biomarkers including hepcidin may be useful to actively and beneficially manage iron status.

  7. Lithocholic acid: a new emergent protector of intestinal calcium absorption under oxidant conditions.

    PubMed

    Marchionatti, Ana M; Pérez, Adriana; Rivoira, María A; Rodríguez, Valeria A; Tolosa de Talamoni, Nori G

    2017-04-01

    LCA and 1,25(OH)2D3 are vitamin D receptor ligands with different binding affinity. The secosteroid stimulates intestinal Ca(2+) absorption. Whether LCA alters this process remains unknown. The aim of our work was to determine the effect of LCA on intestinal Ca(2+) absorption in the absence or presence of NaDOC, bile acid that inhibits the cation transport. The data show that LCA by itself did not alter intestinal Ca(2+) absorption, but prevented the inhibitory effect of NaDOC. The concomitant administration of LCA avoided the reduction of intestinal alkaline phosphatase activity caused by NaDOC. In addition, LCA blocked a decrease caused by NaDOC on gene and protein expression of molecules involved in the transcellular pathway of intestinal Ca(2+) absorption. The oxidative stress and apoptosis triggered by NaDOC were abrogated by LCA co-treatment. In conclusion, LCA placed in the intestinal lumen protects intestinal Ca(2+) absorption against the inhibitory effects caused by NaDOC. LCA avoids the reduction of the transcellular Ca(2+) movement, apparently by blocking the oxidative stress and apoptosis triggered by NaDOC, normalizing the gene and protein expression of molecules involved in Ca(2+) movement. Therefore, LCA might become a possible treatment to improve intestinal calcium absorption under oxidant conditions.

  8. Environmental Factors Affecting Ammonium Oxidation Under Iron Reducing Conditions

    NASA Astrophysics Data System (ADS)

    Jaffe, P. R.; Huang, S.; Ruiz-Urigüen, M.

    2014-12-01

    Ammonium (NH4+) oxidation coupled to iron (Fe) reduction in the absence of oxygen and nitrate/nitrite (NO3-/NO2-) has been reported by several investigators and referred to as Feammox. Feammox is a biological reaction, where Fe(III) is the electron acceptor, which is reduced to Fe(II), and NH4+ is the electron donor, which is oxidized to NO2-. Through a 180-day anaerobic incubation experiment, and using PCR-DGGE, 454-pyosequecing and qPCR analysis, we have shown that an Acidimicrobiaceae bacterium A6, a previously unreported species in the Acidimicrobiaceae family, might be either responsible or plays a key role in the Feammox process, We have enriched these Feammox bacteria (65.8% in terms of cell numbers) in a membrane reactor, and isolated the pure Acidimicrobiaceae bacterium A6 strain in an autotrophic medium. In samples collected and then incubated from a series of local wetland-, upland-, as well as storm-water detention pond-sediments, Feammox activity was only detected in acidic soil environments that contain Fe oxides. Using primers we developed for this purpose, Acidimicrobiaceae bacterium A6 was detected in all incubations where Feammox was observed. Anaerobic incubations of Feammox enrichment cultures adjusted to different pH, revealed that the optimal pH for Feammox is 4 ~ 5, and the reaction does not proceed when pH > 7. Feammox was still proceeding at pH as low as 2. In Feammox culture amended with different Fe(III) sources, Feammox reaction proceeded only when Fe oxides (ferrihydrite or goethite ) were supplied, whereas samples incubated with ferric chloride or ferric citrate showed no measurable NH4+ oxidation. Furthermore, we have also determined from incubation experiments conducted with a temperature gradient (10 ~ 35℃), that the Feammox process was active when the temperature is above 15℃, and the optimal temperature is 20℃. Incubations of enrichment culture with 79% Feammox bacteria appeared to remove circa 8% more NH4+ at 20ºC than at

  9. Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Lili; Yu, Xinxin; Hu, Hongrui; Li, Yang; Wu, Mingzai; Wang, Zhongzhu; Li, Guang; Sun, Zhaoqi; Chen, Changle

    2015-03-01

    Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4.7H2O. By adjusting reaction temperature, α-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from α-Fe2O3 to Fe3O4 via γ-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide sheets and H2 gas generated during the annealing of graphene oxide are believed to play an important role during these phase transformations. These samples showed good electromagnetic wave absorption performance due to their electromagnetic complementary effect. These samples possess much better electromagnetic wave absorption properties than the mixture of separately prepared Fe3O4 with rGO, suggesting the crucial role of synthetic method in determining the product properties. Also, these samples perform much better than commercial absorbers. Most importantly, the great stability of these composites is highly advantageous for applications as electromagnetic wave absorption materials at high temperatures.

  10. Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature.

    PubMed

    Zhang, Lili; Yu, Xinxin; Hu, Hongrui; Li, Yang; Wu, Mingzai; Wang, Zhongzhu; Li, Guang; Sun, Zhaoqi; Chen, Changle

    2015-03-19

    Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4 · 7H2O. By adjusting reaction temperature, α-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from α-Fe2O3 to Fe3O4 via γ-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide sheets and H2 gas generated during the annealing of graphene oxide are believed to play an important role during these phase transformations. These samples showed good electromagnetic wave absorption performance due to their electromagnetic complementary effect. These samples possess much better electromagnetic wave absorption properties than the mixture of separately prepared Fe3O4 with rGO, suggesting the crucial role of synthetic method in determining the product properties. Also, these samples perform much better than commercial absorbers. Most importantly, the great stability of these composites is highly advantageous for applications as electromagnetic wave absorption materials at high temperatures.

  11. Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature

    PubMed Central

    Zhang, Lili; Yu, Xinxin; Hu, Hongrui; Li, Yang; Wu, Mingzai; Wang, Zhongzhu; Li, Guang; Sun, Zhaoqi; Chen, Changle

    2015-01-01

    Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4·7H2O. By adjusting reaction temperature, α-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from α-Fe2O3 to Fe3O4 via γ-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide sheets and H2 gas generated during the annealing of graphene oxide are believed to play an important role during these phase transformations. These samples showed good electromagnetic wave absorption performance due to their electromagnetic complementary effect. These samples possess much better electromagnetic wave absorption properties than the mixture of separately prepared Fe3O4 with rGO, suggesting the crucial role of synthetic method in determining the product properties. Also, these samples perform much better than commercial absorbers. Most importantly, the great stability of these composites is highly advantageous for applications as electromagnetic wave absorption materials at high temperatures. PMID:25788158

  12. Metadynamics study of iron phases at the Earth's inner core conditions

    NASA Astrophysics Data System (ADS)

    Zhang, F.; Oganov, A. R.

    2007-12-01

    Iron is the main element in the Earth core and the stable phase of iron in the Earth's solid inner core is still highly controversial (Sambridge, 2003). In order to predict the properties of iron at high pressures and temperatures, here, we use a novel simulation technique, first-principles metadynamics (Martonak et al., 2003, see also Oganov et al., 2005 ), to unveil the stepwise mechanism of the pressure-induced (350 GPa) transformations between bcc, fcc and hcp iron at the temperatures of 2000 K and 6000 K respectively. We predicted the bcc \\{110\\}, fcc \\{111\\} and hcp \\{111\\} slip planes at the Earth inner core conditions. We also predicted some metastable iron phases (e.g. R-3M and P-6M2 structures) on the pathway of the phase transition. The c/a ratios of the iron structures are also calculated at the simulated conditions. Implications of these results for seismic anisotropy in the Earth inner core will be discussed (Zhang, 2007). References: [1] Sambridge M., (2003) An Ensemble View of Earth's Inner Core. Science, 299, 529-530; [2] Martonak R., Laio A., and Parrinello M., (2003). Predicting crystal structures: The Parrinello-Rahman method revisited. Phys. Rev. Lett. 90, 075503; [3] Oganov A.R., Martonak R., Laio A., Raiteri P., Parrinello M. (2005). Anisotropy of Earth's D" layer and stacking faults in the MgSiO3 post-perovskite phase. Nature 438, 1142-1144; [4] Zhang F. & Oganov A.R., (2007) Metadynamics study of iron phases at the Earth's inner core conditions. (in prep.)

  13. Formation of an interconnected network of iron melt at Earth’s lower mantle conditions

    SciTech Connect

    Shi, Crystal Y.; Zhang, Li; Yang, Wenge; Liu, Yijin; Wang, Junyue; Meng, Yue; Andrews, Joy C.; Mao, Wendy L.

    2013-10-06

    Core formation represents the most significant differentiation event in Earth’s history. Our planet’s present layered structure with a metallic core and an overlying mantle implies that there must be a mechanism to separate iron alloy from silicates in the initially accreted material. At upper mantle conditions, percolation has been ruled out as an efficient mechanism because of the tendency of molten iron to form isolated pockets at these pressures and temperatures. Here we present experimental evidence of a liquid iron alloy forming an interconnected melt network within a silicate perovskite matrix under pressure and temperature conditions of the Earth’s lower mantle. Using nanoscale synchrotron X-ray computed tomography, we image a marked transition in the shape of the iron-rich melt in three-dimensional reconstructions of samples prepared at varying pressures and temperatures using a laser-heated diamond-anvil cell. We find that, as the pressure increases from 25 to 64GPa, the iron distribution changes from isolated pockets to an interconnected network. Our results indicate that percolation could be a viable mechanism of core formation at Earth’s lower mantle conditions.

  14. Kinetics and corrosion products of aqueous nitrate reduction by iron powder without reaction conditions control.

    PubMed

    Fan, Xiaomeng; Guan, Xiaohong; Ma, Jun; Ai, Hengyu

    2009-01-01

    Although considerable research has been conducted on nitrate reduction by zero-valent iron powder (Fe0), these studies were mostly operated under anaerobic conditions with invariable pH that was unsuitable for practical application. Without reaction conditions (dissolved oxygen or reaction pH) control, this work aimed at subjecting the kinetics of denitrification by microscale Fe0 (160-200 mesh) to analysis the factors affecting the denitrification of nitrate and the composition of iron reductive products coating upon the iron surface. Results of the kinetics study have indicated that a higher initial concentration of nitrate would yield a greater reaction rate constant. The reduction rate of nitrate increased with increasing Fe0 dosage. The reaction can be described as a pseudo-first order reaction with respect to nitrate concentration or Fe0 dosage. Experimental results also suggested that nitrate reduction by microscale Fe0 without reaction condition control primarily was an acid-driven surface-mediated process, and the reaction order was 0.65 with respect to hydrogen ion concentration. The analyses of X-ray diffractometry and X-ray photoelectron spectroscopy indicated that a black coating, consisted of Fe2O3, Fe3O4 and FeO(OH), was formed on the surface of iron grains as an iron corrosion product when the system initial pH was lower than 5. The proportion of FeO(OH) increased as reaction time went on, whereas the proportion of Fe3O4 decreased.

  15. Nearest-neighbor nitrogen and oxygen distances in the iron(II)-DNA complex studied by extended X-ray absorption fine structure.

    PubMed

    Bertoncini, Clelia R A; Meneghini, Rogerio; Tolentino, Helio

    2010-11-01

    In mammalian cells, DNA-bound Fe(II) reacts with H₂O₂ producing the highly reactive hydroxyl radical (OH) in situ. Since ·OH attacks nearby DNA residue generating oxidative DNA damage, many questions have arisen regarding iron-DNA complex formations and their implication in pre-malignant mutations and aging. In this work, a solid sample of Fe(II)-DNA complex containing one Fe(II) per 10 nucleotides was analyzed from extended X-ray absorption fine structure (EXAFS) spectra collected in a synchrotron radiation light source. Best fitting parameters of the EXAFS signal for the first two shells provide evidence of five oxygen atoms at 1.99 ± 0.02 Å and one nitrogen atom at 2.20 ± 0.02 Å in the inner coordination sphere of the Fe(II)-DNA complex. Considering that both purine base moieties bearing nitrogen atoms are prone to chelate iron, these results are consistent with the previously observed lower levels of DNA damage in cytosine nucleotides relative to adenine and guanine sites in cells under more physiological conditions of Fe(II) Fenton reaction.

  16. Environmental embrittlement of iron aluminides under cyclic loading conditions

    SciTech Connect

    Castagna, A.; Alven, D.A.; Stoloff, N.S.

    1995-08-01

    The tensile and fatigue crack growth behavior in air in hydrogen and in oxygen of an Fe-Al-Cr-Zr alloy is described. The results are compared to data for FA-129. A detailed analysis of frequency effects on fatigue crack growth rates of FA-129, tested in the B2 condition, shows that dislocation transport of hydrogen from the surface is the rate limiting step in fatigue crack growth.

  17. Iron K Features in the Quasar E 1821+643: Evidence for Gravitationally Redshifted Absorption?

    NASA Technical Reports Server (NTRS)

    Yaqoob, Tahir; Serlemitsos, Peter

    2005-01-01

    We report a Chandra high-energy grating detection of a narrow, redshifted absorption line superimposed on the red wing of a broad Fe K line in the z = 0.297 quasar E 1821+643. The absorption line is detected at a confidence level, estimated by two different methods, in the range approx. 2 - 3 sigma. Although the detection significance is not high enough to exclude a non-astrophysical origin, accounting for the absorption feature when modeling the X-ray spectrum implies that the Fe-K emission line is broad, and consistent with an origin in a relativistic accretion disk. Ignoring the apparent absorption feature leads to the conclusion that the Fe-K emission line is narrower, and also affects the inferred peak energy of the line (and hence the inferred ionization state of Fe). If the absorption line (at approx. 6.2 keV in the quasar frame) is real, we argue that it could be due to gravitationally redshifted Fe XXV or Fe XXVI resonance absorption within approx. 10 - 20 gravitational radii of the putative central black hole. The absorption line is not detected in earlier ASCA and Chandra low-energy grating observations, but the absorption line is not unequivocally ruled out by these data. The Chandra high-energy grating Fe-K emission line is consistent with an origin predominantly in Fe I-XVII or so. In an ASCA observation eight years earlier, the Fe-K line peaked at approx. 6.6 keV, closer to the energies of He-like Fe triplet lines. Further, in a Chandra low-energy grating observation the Fe-K line profile was double-peaked, one peak corresponding to Fe I-XVII or so, the other peak to Fe XXVI Ly alpha. Such a wide range in ionization state of Fe is not ruled out by the HEG and ASCA data either, and is suggestive of a complex structure for the line-emitter.

  18. Impacts of Combustion Conditions and Photochemical Processing on the Light Absorption of Biomass Combustion Aerosol.

    PubMed

    Martinsson, J; Eriksson, A C; Nielsen, I Elbæk; Malmborg, V Berg; Ahlberg, E; Andersen, C; Lindgren, R; Nyström, R; Nordin, E Z; Brune, W H; Svenningsson, B; Swietlicki, E; Boman, C; Pagels, J H

    2015-12-15

    The aim was to identify relationships between combustion conditions, particle characteristics, and optical properties of fresh and photochemically processed emissions from biomass combustion. The combustion conditions included nominal and high burn rate operation and individual combustion phases from a conventional wood stove. Low temperature pyrolysis upon fuel addition resulted in "tar-ball" type particles dominated by organic aerosol with an absorption Ångström exponent (AAE) of 2.5-2.7 and estimated Brown Carbon contributions of 50-70% to absorption at the climate relevant aethalometer-wavelength (520 nm). High temperature combustion during the intermediate (flaming) phase was dominated by soot agglomerates with AAE 1.0-1.2 and 85-100% of absorption at 520 nm attributed to Black Carbon. Intense photochemical processing of high burn rate flaming combustion emissions in an oxidation flow reactor led to strong formation of Secondary Organic Aerosol, with no or weak absorption. PM1 mass emission factors (mg/kg) of fresh emissions were about an order of magnitude higher for low temperature pyrolysis compared to high temperature combustion. However, emission factors describing the absorption cross section emitted per kg of fuel consumed (m(2)/kg) were of similar magnitude at 520 nm for the diverse combustion conditions investigated in this study. These results provide a link between biomass combustion conditions, emitted particle types, and their optical properties in fresh and processed plumes which can be of value for source apportionment and balanced mitigation of biomass combustion emissions from a climate and health perspective.

  19. LiCl Dehumidifier LiBr absorption chiller hybrid air conditioning system with energy recovery

    DOEpatents

    Ko, Suk M.

    1980-01-01

    This invention relates to a hybrid air conditioning system that combines a solar powered LiCl dehumidifier with a LiBr absorption chiller. The desiccant dehumidifier removes the latent load by absorbing moisture from the air, and the sensible load is removed by the absorption chiller. The desiccant dehumidifier is coupled to a regenerator and the desiccant in the regenerator is heated by solar heated hot water to drive the moisture therefrom before being fed back to the dehumidifier. The heat of vaporization expended in the desiccant regenerator is recovered and used to partially preheat the driving fluid of the absorption chiller, thus substantially improving the overall COP of the hybrid system.

  20. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1986-01-01

    After long arduous work with the simulator, measurements of the refractivity and absorptivity of nitrogen under conditions similar to those for Titan were completed. The most significant measurements, however, were those of the microwave absorption from gaseous ammonia under simulated conditions for the Jovian atmospheres over wavelengths from 1.3 to 22 cm. The results of these measurements are critical in that they confirm the theoretical calculation of the ammonia opacity using the Ben-Reuven lineshape. The application of both these results, and results obtained previously, to planetary observations at microwave frequencies were especially rewarding. Applications of the results for ammonia to radio astronomical observations of Jupiter in the 1.3 to 20 cm wavelength range and the application of results for gaseous H2SO4 under simulated Venus conditions are discussed.

  1. Effects of iron concentration level in extracting solutions from contaminated soils on the determination of zinc by flame atomic absorption spectrometry with two background correctors.

    PubMed

    Waterlot, Christophe; Pelfrêne, Aurélie; Douay, Francis

    2012-01-01

    Zinc and iron concentrations were determined after digestion, water, and three-step sequential extractions of contaminated soils. Analyses were carried out using flame absorption spectrometry with two background correctors: a deuterium lamp used as the continuum light source (D(2) method) and the high-speed self-reversal method (HSSR method). Regarding the preliminary results obtained with synthetic solutions, the D(2) method often emerged as an unsuitable configuration for compensating iron spectral interferences. In contrast, the HSSR method appeared as a convenient and powerful configuration and was tested for the determination of zinc in contaminated soils containing high amounts of iron. Simple, fast, and interference-free method, the HSSR method allows zinc determination at the ppb level in the presence of large amounts of iron with high stability, sensitivity, and reproducibility of results. Therefore, the HSSR method is described here as a promising approach for monitoring zinc concentrations in various iron-containing samples without any pretreatment.

  2. Iron plaque formed under aerobic conditions efficiently immobilizes arsenic in Lupinus albus L roots.

    PubMed

    Fresno, Teresa; Peñalosa, Jesús M; Santner, Jakob; Puschenreiter, Markus; Prohaska, Thomas; Moreno-Jiménez, Eduardo

    2016-09-01

    Arsenic is a non-threshold carcinogenic metalloid. Thus, human exposure should be minimised, e.g. by chemically stabilizing As in soil. Since iron is a potential As immobiliser, it was investigated whether root iron plaque, formed under aerobic conditions, affects As uptake, metabolism and distribution in Lupinus albus plants. White lupin plants were cultivated in a continuously aerated hydroponic culture containing Fe/EDDHA or FeSO4 and exposed to arsenate (5 or 20 μM). Only FeSO4 induced surficial iron plaque in roots. LA-ICP-MS analysis accomplished on root sections corroborated the association of As to this surficial Fe. Additionally, As(V) was the predominant species in FeSO4-treated roots, suggesting less efficient As uptake in the presence of iron plaque. Fe/EDDHA-exposed roots neither showed such surficial FeAs co-localisation nor As(V) accumulation; in contrast As(III) was the predominant species in root tissue. Furthermore, FeSO4-treated plants showed reduced shoot-to-root As ratios, which were >10-fold lower compared to Fe/EDDHA treatment. Our results highlight the role of an iron plaque formed in roots of white lupin under aerobic conditions on As immobilisation. These findings, to our knowledge, have not been addressed before for this plant and have potential implications on soil remediation (phytostabilisation) and food security (minimising As in crops).

  3. Relativistic Iron K Emission and Absorption in the Seyfert 1.9 Galaxy MCG-05-23-16

    NASA Technical Reports Server (NTRS)

    Braito, V.; Reeves, J. N.; Dewangan, G. C.; George, I.; Griffiths, R.; Markowitz, A.; Nandra, K.; Porquet, D.; Ptak, A.; Turner, T. J.; Yaqoob, T.; Weaver, K.

    2007-01-01

    We present the results of the simultaneous deep XMM-Newton and Chandra observations of the bright Seyfert 1.9 galaxy MCG-5-23-16, which is thought to have one of the best known examples of a relativistically broadened iron Kalpha line. We detected a narrow sporadic absorption line at 7.7 keV which appears to be variable on a time-scale of 20 ksec. If associated with FeXXVI this absorption is indicative of a possible variable high ionization, high velocity outflow. The time averaged spectral analysis shows that the iron K-shell complex is best modeled with an unresolved narrow emission component (FWHM less than 5000 kilometers per second, EW approx. 60 eV) plus a broad component. This latter component has FWHM approx. 44000 kilometers per second, an EW approx. 50 eV and its profile is well described with an emission line originating from the accretion disk viewed with an inclination angle approx. 40 deg. and with the emission arising from within a few tens of gravitational radii of the central black hole. The time-resolved spectral analysis of the XMM-Newton EPIC-pn spectrum shows that both the narrow and broad components of the Fe K emission line appear to be constant within the errors. The analysis of the XMM-Newton/RGS spectrum reveals that the soft X-ray emission of MCG-5-23-16 is likely dominated by several emission lines superimposed on an unabsorbed scattered power-law continuum. The lack of strong Fe L shell emission together with the detection of a strong forbidden line in the O VII triplet supports a scenario where the soft X ray emission lines are produced in a plasma photoionized by the nuclear emission.

  4. Absorption of Nickel, Chromium, and Iron by the Root Surface of Primary Molars Covered with Stainless Steel Crowns

    PubMed Central

    Keinan, David; Mass, Eliyahu; Zilberman, Uri

    2010-01-01

    Objective. The purpose of this study was to analyze the absorption of metal ions released from stainless steel crowns by root surface of primary molars. Study Design. Laboratory research: The study included 34 primary molars, exfoliated or extracted during routine dental treatment. 17 molars were covered with stainless-steel crowns for more than two years and compared to 17 intact primary molars. Chemical content of the mesial or distal root surface, 1 mm apically to the crown or the cemento-enamel junction (CEJ), was analyzed. An energy dispersive X-ray spectrometer (EDS) was used for chemical analysis. Results. Higher amounts of nickel, chromium, and iron (5-6 times) were found in the cementum of molars covered with stainless-steel crowns compared to intact molars. The differences between groups were highly significant (P < .001). Significance. Stainless-steel crowns release nickel, chromium, and iron in oral environment, and the ions are absorbed by the primary molars roots. The additional burden of allergenic metals should be reduced if possible. PMID:21274429

  5. Prediction of High-Valent Iron K-edge Absorption Spectra by Time-Dependent Density Functional Theory

    PubMed Central

    Chandrasekaran, P.; Stieber, S. Chantal E.; Collins, Terrence J.; Que, Lawrence; Neese, Frank; DeBeer, Serena

    2011-01-01

    In recent years a number of high-valent iron intermediates have been identified as reactive species in iron-containing metalloproteins. Inspired by the interest in these highly reactive species, chemists have synthesized Fe(IV) and Fe(V) model complexes with terminal oxo or nitrido groups, as well as a rare example of an Fe(VI)-nitrido species. In all these cases, X-ray absorption spectroscopy has played a key role in the identification and characterization of these species, with both the energy and intensity of the pre-edge features providing spectroscopic signatures for both the oxidation state and the local site geometry. Here we build on a time-dependent DFT methodology for the prediction of Fe K- pre-edge features, previously applied to ferrous and ferric complexes, and extend it to a range of Fe(IV), Fe(V) and Fe(VI) complexes. The contributions of oxidation state, coordination environment and spin state to the spectral features are discussed. These methods are then extended to calculate the spectra of the heme active site of P450 Compound II and the non-heme active site of TauD. The potential for using these methods in a predictive manner is highlighted. PMID:21956429

  6. Genetic defects of iron transport.

    PubMed

    Bannerman, R M

    1976-09-01

    Five genetic traits in man and laboratory animals have major effects on iron transport. The heterogeneous condition, hemochromatosis, in some families appears to segregate as a Mendelian trait, and is associated with defective control of intestinal iron absorption. In the very rare human autosomal recessive trait, atransferrinemia, there is an almost total lack of transferrin and gross maldistribution of iron through the body. In mice, sex-linked anemia (an X-linked recessive trait) causes iron deficiency through defective iron absorption, at the "exit" step; a similar defect probably exists in placental iron transfer. In microcytic anemia of mice, an autosomal recessive trait, iron absorption is also impaired because of a defect of iron entry into cells, which is probably generalized. Belgrade rat anemia, less understood at present, also may involve a major disorder of iron metabolism. Study of these mutations has provided new knowledge of iron metabolism and its genetic control Their phenotypic interaction with nutritional factors, especially the form and quantity of iron in the diet, may provide new insights for the study of nutrition.

  7. Growth of the acidophilic iron-sulfur bacterium Acidithiobacillus ferrooxidans under Mars-like geochemical conditions

    NASA Astrophysics Data System (ADS)

    Bauermeister, Anja; Rettberg, Petra; Flemming, Hans-Curt

    2014-08-01

    The question of life on Mars has been in focus of astrobiological research for several decades, and recent missions in orbit or on the surface of the planet are constantly expanding our knowledge on Martian geochemistry. For example, massive stratified deposits have been identified on Mars containing sulfate minerals and iron oxides, which suggest the existence of acidic aqueous conditions in the past, similar to acidic iron- and sulfur-rich environments on Earth. Acidophilic organisms thriving in such habitats could have been an integral part of a possibly widely extinct Martian ecosystem, but remains might possibly even exist today in protected subsurface niches. The chemolithoautotrophic strain Acidithiobacillus ferrooxidans was selected as a model organism to study the metabolic capacities of acidophilic iron-sulfur bacteria, especially regarding their ability to grow with in situ resources that could be expected on Mars. The experiments were not designed to accurately simulate Martian physical conditions (except when certain single parameters such as oxygen partial pressure were considered), but rather the geochemical environment that can be found on Mars. A. ferrooxidans could grow solely on the minerals contained in synthetic Mars regolith mixtures with no added nutrients, using either O2 as an external electron acceptor for iron oxidation, or H2 as an external electron donor for iron reduction, and thus might play important roles in the redox cycling of iron on Mars. Though the oxygen partial pressure of the Martian atmosphere at the surface was not sufficient for detectable iron oxidation and growth of A. ferrooxidans during short-term incubation (7 days), alternative chemical O2-generating processes in the subsurface might yield microhabitats enriched in oxygen, which principally are possible under such conditions. The bacteria might also contribute to the reductive dissolution of Fe3+-containing minerals like goethite and hematite, which are

  8. Oxygen, Neon, and Iron X-Ray Absorption in the Local Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Gatuzz, Efrain; Garcia, Javier; Kallman, Timothy R.; Mendoza, Claudio

    2016-01-01

    We present a detailed study of X-ray absorption in the local interstellar medium by analyzing the X-ray spectra of 24 galactic sources obtained with the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer. Methods. By modeling the continuum with a simple broken power-law and by implementing the new ISMabs X-ray absorption model, we have estimated the total H, O, Ne, and Fe column densities towards the observed sources. Results. We have determined the absorbing material distribution as a function of source distance and galactic latitude longitude. Conclusions. Direct estimates of the fractions of neutrally, singly, and doubly ionized species of O, Ne, and Fe reveal the dominance of the cold component, thus indicating an overall low degree of ionization. Our results are expected to be sensitive to the model used to describe the continuum in all sources.

  9. Oxygen, neon, and iron X-ray absorption in the local interstellar medium

    NASA Astrophysics Data System (ADS)

    Gatuzz, Efraín; García, Javier A.; Kallman, Timothy R.; Mendoza, Claudio

    2016-04-01

    Aims: We present a detailed study of X-ray absorption in the local interstellar medium by analyzing the X-ray spectra of 24 galactic sources obtained with the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer. Methods: By modeling the continuum with a simple broken power-law and by implementing the new ISMabs X-ray absorption model, we have estimated the total H, O, Ne, and Fe column densities towards the observed sources. Results: We have determined the absorbing material distribution as a function of source distance and galactic latitude-longitude. Conclusions: Direct estimates of the fractions of neutrally, singly, and doubly ionized species of O, Ne, and Fe reveal the dominance of the cold component, thus indicating an overall low degree of ionization. Our results are expected to be sensitive to the model used to describe the continuum in all sources.

  10. Determination of copper, zinc and iron in broncho-alveolar lavages by atomic absorption spectroscopy.

    PubMed

    Harlyk, C; Mccourt, J; Bordin, G; Rodriguez, A R; van der Eeckhout, A

    1997-11-01

    Concentrations of Zn, Cu and Fe were measured in 157 broncho-alveolar lavages (BAL), before and after centrifugation, collected at the Leuven University Hospital (Belgium). Zn was measured by flame-atomic absorption spectroscopy, using direct calibration, while Cu and Fe were determined by electrothermal atomic absorption spectroscopy, using the method of standard additions. For Fe only 56 samples were measured. Most of the studied elements are present in the liquid phase (supernatant). About 90% of Cu concentrations lie between 0 and 15 micrograms/kg, while 90% of Zn concentrations are lower than 230 micrograms/kg, with 30% between 30 and 70 micrograms/kg, and 50% between 100 and 200 micrograms/kg. There seems to be a reverse relationship between Cu and Zn levels with high Cu going along with low Zn and vice versa.

  11. Liquid iron-sulfur alloys at outer core conditions by first-principles calculations

    NASA Astrophysics Data System (ADS)

    Umemoto, Koichiro; Hirose, Kei; Imada, Saori; Nakajima, Yoichi; Komabayashi, Tetsuya; Tsutsui, Satoshi; Baron, Alfred Q. R.

    2014-10-01

    We perform first-principles calculations to investigate liquid iron-sulfur alloys (Fe, Fe56S8, Fe52S12, and Fe48S16) under high-pressure and high-temperature (150-300 GPa and 4000-6000 K) conditions corresponding to the Earth's outer core. Considering only the density profile, the best match with the preliminary reference Earth model is by liquid Fe-14 wt % S (Fe50S14), assuming sulfur is the only light element. However, its bulk sound velocity is too high, in particular in the deep outer core, suggesting that another light component such as oxygen is required. An experimental check using inelastic X-ray scattering shows good agreement with the calculations. In addition, a present study demonstrates that the Birch's law does not hold for liquid iron-sulfur alloy, consistent with a previous report on pure liquid iron.

  12. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

    Radio absorptivity data for the Venus middle atmosphere (1 to 6 atm, temperatures from 500 to 575K) obtained from spacecraft radio occultation experiments (at 3.6 to 13.4 cm wavelengths) and earth-based radio astronomical observations (1 to 3 cm wavelength range) are compared to laboratory observations at the latter wavelength range under simulated Venus conditions to infer abundances of microwave-absorbing atmospheric constituents, i.e. H2SO4 in a CO2 atmosphere.

  13. Solar Absorption Refrigeration System for Air-Conditioning of a Classroom Building in Northern India

    NASA Astrophysics Data System (ADS)

    Agrawal, Tanmay; Varun; Kumar, Anoop

    2015-10-01

    Air-conditioning is a basic tool to provide human thermal comfort in a building space. The primary aim of the present work is to design an air-conditioning system based on vapour absorption cycle that utilizes a renewable energy source for its operation. The building under consideration is a classroom of dimensions 18.5 m × 13 m × 4.5 m located in Hamirpur district of Himachal Pradesh in India. For this purpose, cooling load of the building was calculated first by using cooling load temperature difference method to estimate cooling capacity of the air-conditioning system. Coefficient of performance of the refrigeration system was computed for various values of strong and weak solution concentration. In this work, a solar collector is also designed to provide required amount of heat energy by the absorption system. This heat energy is taken from solar energy which makes this system eco-friendly and sustainable. A computer program was written in MATLAB to calculate the design parameters. Results were obtained for various values of solution concentrations throughout the year. Cost analysis has also been carried out to compare absorption refrigeration system with conventional vapour compression cycle based air-conditioners.

  14. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and Earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often lead to significant misinterpretation of available opacity data. Steffes and Eshleman showed that under environmental conditions corresponding to the middle atmosphere of Venus, the microwave absorption due to atmospheric SO2 was 50 percent greater than that calculated from Van Vleck-Weiskopff theory. Similarly, the opacity from gaseous H2SO4 was found to be a factor of 7 greater than theoretically predicted for conditions of the Venus middle atmosphere. The recognition of the need to make such measurements over a range of temperatures and pressures which correspond to the periapsis altitudes of radio occultation experiments, and over a range of frequencies which correspond to both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements.

  15. Non-Heme Iron Absorption and Utilization from Typical Whole Chinese Diets in Young Chinese Urban Men Measured by a Double-Labeled Stable Isotope Technique

    PubMed Central

    Yang, Lichen; Zhang, Yuhui; Wang, Jun; Huang, Zhengwu; Gou, Lingyan; Wang, Zhilin; Ren, Tongxiang; Piao, Jianhua; Yang, Xiaoguang

    2016-01-01

    Background This study was to observe the non-heme iron absorption and biological utilization from typical whole Chinese diets in young Chinese healthy urban men, and to observe if the iron absorption and utilization could be affected by the staple food patterns of Southern and Northern China. Materials and Methods Twenty-two young urban men aged 18–24 years were recruited and randomly assigned to two groups in which the staple food was rice and steamed buns, respectively. Each subject received 3 meals containing approximately 3.25 mg stable 57FeSO4 (the ratio of 57Fe content in breakfast, lunch and dinner was 1:2:2) daily for 2 consecutive days. In addition, approximately 2.4 mg 58FeSO4 was administered intravenously to each subject at 30–60 min after dinner each day. Blood samples were collected from each subject to measure the enrichment of the 57Fe and 58Fe. Fourteen days after the experimental diet, non-heme iron absorption was assessed by measuring 57Fe incorporation into red blood cells, and absorbed iron utilization was determined according to the red blood cell incorporation of intravenously infused 58Fe SO4. Results Non-heme iron intake values overall, and in the rice and steamed buns groups were 12.8 ±2.1, 11.3±1.3 and 14.3±1.5 mg, respectively; the mean 57Fe absorption rates were 11±7%, 13±7%, and 8±4%, respectively; and the mean infused 58Fe utilization rates were 85±8%, 84±6%, and 85±10%, respectively. There was no significantly difference in the iron intakes, and 57Fe absorption and infused 58Fe utilization rates between rice and steamed buns groups (all P>0.05). Conclusion We present the non-heme iron absorption and utilization rates from typical whole Chinese diets among young Chinese healthy urban men, which was not affected by the representative staple food patterns of Southern and Northern China. This study will provide a basis for the setting of Chinese iron DRIs. PMID:27099954

  16. Tunable Diode Laser Atomic Absorption Spectroscopy for Detection of Potassium under Optically Thick Conditions.

    PubMed

    Qu, Zhechao; Steinvall, Erik; Ghorbani, Ramin; Schmidt, Florian M

    2016-04-05

    Potassium (K) is an important element related to ash and fine-particle formation in biomass combustion processes. In situ measurements of gaseous atomic potassium, K(g), using robust optical absorption techniques can provide valuable insight into the K chemistry. However, for typical parts per billion K(g) concentrations in biomass flames and reactor gases, the product of atomic line strength and absorption path length can give rise to such high absorbance that the sample becomes opaque around the transition line center. We present a tunable diode laser atomic absorption spectroscopy (TDLAAS) methodology that enables accurate, calibration-free species quantification even under optically thick conditions, given that Beer-Lambert's law is valid. Analyte concentration and collisional line shape broadening are simultaneously determined by a least-squares fit of simulated to measured absorption profiles. Method validation measurements of K(g) concentrations in saturated potassium hydroxide vapor in the temperature range 950-1200 K showed excellent agreement with equilibrium calculations, and a dynamic range from 40 pptv cm to 40 ppmv cm. The applicability of the compact TDLAAS sensor is demonstrated by real-time detection of K(g) concentrations close to biomass pellets during atmospheric combustion in a laboratory reactor.

  17. Bioavailability of iron in geophagic earths and clay minerals, and their effect on dietary iron absorption using an in vitro digestion/Caco-2 cell model.

    PubMed

    Seim, Gretchen L; Ahn, Cedric I; Bodis, Mary S; Luwedde, Flavia; Miller, Dennis D; Hillier, Stephen; Tako, Elad; Glahn, Raymond P; Young, Sera L

    2013-08-01

    Geophagy, the deliberate consumption of earth, is strongly associated with iron (Fe) deficiency. It has been proposed that geophagy may be practiced as a means to improve Fe status by increasing Fe intakes and, conversely, that geophagy may cause Fe deficiency by inhibiting Fe absorption. We tested these hypotheses by measuring Fe concentration and relative bioavailable Fe content of 12 samples of geophagic earth and 4 samples of pure clay minerals. Further, we assessed the impact of these samples on the bioavailability of Fe from an Fe-rich test meal (cooked white beans, WB). Fe concentrations were measured with inductively coupled plasma atomic emission spectroscopy. Fe bioavailability was determined using an in vitro digestion/Caco-2 cell model in which ferritin formation was used as an index of Fe bioavailability. Geophagic earth and clay mineral samples were evaluated with this model, both alone and in combination with WB (1 : 16 ratio, sample : WB). Median Fe concentration of the geophagic earth was 3485 (IQR 2462, 14 ,571) μg g⁻¹ and mean Fe concentration in the clay minerals was 2791 (±1782) μg g⁻¹. All specimens had Fe concentrations significantly higher (p ≤ 0.005) than the Fe concentration of WB (77 μg g⁻¹). Ferritin formation (i.e. Fe uptake) in cells exposed to geophagic earths and clay minerals was significantly lower than in cells exposed to WB (p ≤ 0.05) and Fe uptake responses of 11 of the 16 samples were not significantly different from the blank, indicating no bioavailable Fe. When samples were combined with WB, 5 of 16 had mean ferritin levels that were significantly lower (p ≤ 0.05, one tail) than the WB alone, indicating that the samples inhibited Fe uptake from the WB. None of the ferritin responses of cells exposed to both WB and earth/clay were significantly higher than WB alone. Thus, although geophagic earths and mineral clays are high in total Fe, very little of this Fe is bioavailable. Further, some

  18. Structural differences of prebiotic oligosaccharides influence their capability to enhance iron absorption in deficient rats.

    PubMed

    Laparra, José Moisés; Díez-Municio, Marina; Herrero, Miguel; Moreno, F Javier

    2014-10-01

    This study evaluates the influence of novel galacto-oligosaccharides derived from lactulose (GOS-Lu), kojibiose or 4'-galactosyl-kojibiose in hematological parameters of Fe homeostasis using Fe-deficient animals. Liver TfR-2, IL-6, NFκB and PPAR-γ expression (mRNA) were also determined by RT-qPCR analyses, and active hepcidin peptide production and short chain fatty acids by LC coupled to MS/MS or UV detection. Feeding animals with GOS-Lu or kojibiose together with FeCl3 increased hemoglobin (Hb) production (by 17%) and mean Hb concentration into erythrocytes relative to animals administered with FeCl3 alone (14.1% and 19.7%, respectively). Animals administered with prebiotics showed decreased plasmatic hepcidin levels, contributing to a higher intestinal absorption of the micronutrient. These data indicate that concurrent administration of these potentially prebiotic oligosaccharides together with a supplement of Fe ameliorates inflammation-mediated perturbations in the liver, according to the particular structure of the prebiotic compound, and result an attractive strategy to improve Fe absorption.

  19. Transcriptional Characterization of a Widely-Used Grapevine Rootstock Genotype under Different Iron-Limited Conditions.

    PubMed

    Vannozzi, Alessandro; Donnini, Silvia; Vigani, Gianpiero; Corso, Massimiliano; Valle, Giorgio; Vitulo, Nicola; Bonghi, Claudio; Zocchi, Graziano; Lucchin, Margherita

    2016-01-01

    Iron chlorosis is a serious deficiency that affects orchards and vineyards reducing quality and yield production. Chlorotic plants show abnormal photosynthesis and yellowing shoots. In grapevine iron uptake and homeostasis are most likely controlled by a mechanism known as "Strategy I," characteristic of non-graminaceous plants and based on a system of soil acidification, iron reduction and transporter-mediated uptake. Nowadays, grafting of varieties of economic interest on tolerant rootstocks is widely used practice against many biotic and abiotic stresses. Nevertheless, many interspecific rootstocks, and in particular those obtained by crossing exclusively non-vinifera genotypes, can show limited nutrient uptake and transport, in particular for what concerns iron. In the present study, 101.14, a commonly used rootstock characterized by susceptibility to iron chlorosis was subjected to both Fe-absence and Fe-limiting conditions. Grapevine plantlets were grown in control, Fe-deprived, and bicarbonate-supplemented hydroponic solutions. Whole transcriptome analyses, via mRNA-Seq, were performed on root apices of stressed and unstressed plants. Analysis of differentially expressed genes (DEGs) confirmed that Strategy I is the mechanism responsible for iron uptake in grapevine, since many orthologs genes to the Arabidopsis "ferrome" were differentially regulated in stressed plant. Molecular differences in the plant responses to Fe absence and presence of bicarbonate were also identified indicating the two treatments are able to induce response-mechanisms only partially overlapping. Finally, we measured the expression of a subset of genes differentially expressed in 101.14 (such as IRT1, FERRITIN1, bHLH38/39) or known to be fundamental in the "strategy I" mechanism (AHA2 and FRO2) also in a tolerant rootstock (M1) finding important differences which could be responsible for the different degrees of tolerance observed.

  20. Transcriptional Characterization of a Widely-Used Grapevine Rootstock Genotype under Different Iron-Limited Conditions

    PubMed Central

    Vannozzi, Alessandro; Donnini, Silvia; Vigani, Gianpiero; Corso, Massimiliano; Valle, Giorgio; Vitulo, Nicola; Bonghi, Claudio; Zocchi, Graziano; Lucchin, Margherita

    2017-01-01

    Iron chlorosis is a serious deficiency that affects orchards and vineyards reducing quality and yield production. Chlorotic plants show abnormal photosynthesis and yellowing shoots. In grapevine iron uptake and homeostasis are most likely controlled by a mechanism known as “Strategy I,” characteristic of non-graminaceous plants and based on a system of soil acidification, iron reduction and transporter-mediated uptake. Nowadays, grafting of varieties of economic interest on tolerant rootstocks is widely used practice against many biotic and abiotic stresses. Nevertheless, many interspecific rootstocks, and in particular those obtained by crossing exclusively non-vinifera genotypes, can show limited nutrient uptake and transport, in particular for what concerns iron. In the present study, 101.14, a commonly used rootstock characterized by susceptibility to iron chlorosis was subjected to both Fe-absence and Fe-limiting conditions. Grapevine plantlets were grown in control, Fe-deprived, and bicarbonate-supplemented hydroponic solutions. Whole transcriptome analyses, via mRNA-Seq, were performed on root apices of stressed and unstressed plants. Analysis of differentially expressed genes (DEGs) confirmed that Strategy I is the mechanism responsible for iron uptake in grapevine, since many orthologs genes to the Arabidopsis “ferrome” were differentially regulated in stressed plant. Molecular differences in the plant responses to Fe absence and presence of bicarbonate were also identified indicating the two treatments are able to induce response-mechanisms only partially overlapping. Finally, we measured the expression of a subset of genes differentially expressed in 101.14 (such as IRT1, FERRITIN1, bHLH38/39) or known to be fundamental in the “strategy I” mechanism (AHA2 and FRO2) also in a tolerant rootstock (M1) finding important differences which could be responsible for the different degrees of tolerance observed. PMID:28105035

  1. Specific absorption rate determination of magnetic nanoparticles through hyperthermia measurements in non-adiabatic conditions

    NASA Astrophysics Data System (ADS)

    Coïsson, M.; Barrera, G.; Celegato, F.; Martino, L.; Vinai, F.; Martino, P.; Ferraro, G.; Tiberto, P.

    2016-10-01

    An experimental setup for magnetic hyperthermia operating in non-adiabatic conditions is described. A thermodynamic model that takes into account the heat exchanged by the sample with the surrounding environment is developed. A suitable calibration procedure is proposed that allows the experimental validation of the model. Specific absorption rate can then be accurately determined just from the measurement of the sample temperature at the equilibrium steady state. The setup and the measurement procedure represent a simplification with respect to other systems requiring calorimeters or crucial corrections for heat flow. Two families of magnetic nanoparticles, one superparamagnetic and one characterised by larger sizes and static hysteresis, have been characterised as a function of field intensity, and specific absorption rate and intrinsic loss power have been obtained.

  2. Cascade Reverse Osmosis Air Conditioning System: Cascade Reverse Osmosis and the Absorption Osmosis Cycle

    SciTech Connect

    2010-09-01

    BEETIT Project: Battelle is developing a new air conditioning system that uses a cascade reverse osmosis (RO)-based absorption cycle. Analyses show that this new cycle can be as much as 60% more efficient than vapor compression, which is used in 90% of air conditioners. Traditional vapor-compression systems use polluting liquids for a cooling effect. Absorption cycles use benign refrigerants such as water, which is absorbed in a salt solution and pumped as liquid—replacing compression of vapor. The refrigerant is subsequently separated from absorbing salt using heat for re-use in the cooling cycle. Battelle is replacing thermal separation of refrigerant with a more efficient reverse osmosis process. Research has shown that the cycle is possible, but further investment will be needed to reduce the number of cascade reverse osmosis stages and therefore cost.

  3. Selenate removal by zero-valent iron in oxic condition: the role of Fe(II) and selenate removal mechanism.

    PubMed

    Yoon, In-Ho; Bang, Sunbaek; Kim, Kyoung-Woong; Kim, Min Gyu; Park, Sang Yoon; Choi, Wang-Kyu

    2016-01-01

    In this study, batch experiments were conducted to investigate the effect of the concentration of ferrous [Fe(II)] ions on selenate [Se(VI)] removal using zero-valent iron (ZVI). The mechanism of removal was investigated using spectroscopic and image analyses of the ZVI-Fe(II)-Se(VI) system. The test to remove 50 mg/L of Se(VI) by 1 g/L of ZVI resulted in about 60% removal of Se(VI) in the case with absence of Fe(II), but other tests with the addition of 50 and 100 mg/L of the Fe(II) had increased the removal efficiencies about 93 and 100% of the Se(VI), respectively. In other batch tests with the absence of ZVI, there were little changes on the Se(VI) removal by the varied concentration of the Fe(II). From these results, we found that Fe(II) ion plays an accelerator for the reduction of Se(VI) by ZVI with the stoichiometric balance of 1.4 (=nFe(2+)/nSe(6+)). Under anoxic conditions, the batch test revealed about 10% removal of the Se(VI), indicating that the presence of dissolved oxygen increased the kinetics of Se(VI) removal due to the Fe(II)-containing oxides on the ZVI, as analyzed by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). The X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectra also showed that the reductive process of Se(VI) to Se(0)/Se(-II) occurred in the presence of the both ZVI and Fe(II). The final product of iron corrosion was lepidocrocite (γ-FeOOH), which acts as an electron transfer barrier from Fe(0) core to Se(VI). Therefore, the addition of Fe(II) enhanced the reactivity of ZVI through the formation of iron oxides (magnetite) favoring electron transfer during the removal of Se(VI), which was through the exhaustion of the Fe(0) core reacted with Se(VI).

  4. Inhibitory effect of calcium on non-heme iron absorption may be related to translocation of DMT-1 at the apical membrane of enterocytes.

    PubMed

    Thompson, Ben A V; Sharp, Paul A; Elliott, Ruan; Fairweather-Tait, Susan J

    2010-07-28

    Many studies show that calcium reduces iron absorption from single meals, but the underlying mechanism is not known. We tested the hypothesis that calcium alters the expression and/or functionality of iron transport proteins. Differentiated Caco-2 cells were treated with ferric ammonium citrate and calcium chloride, and ferritin, DMT-1, and ferroportin were quantified in whole-cell lysate and cell-membrane fractions. Calcium attenuated the iron-induced increase in cell ferritin levels in a dose-dependent manner; a significant decrease was seen at calcium concentrations of 1.25 and 2.5 mM but was only evident after a 16-24 h incubation period. Calcium and iron treatments decreased DMT-1 protein in Caco-2 cell membranes, although total DMT-1 in whole cell lysates was unchanged by either iron or calcium. No change was seen in ferroportin expression. Our data suggest that calcium reduces iron bioavailability by decreasing DMT-1 expression at the apical cell membrane, thereby downregulating iron transport into the cell.

  5. Bread supplemented with amaranth (Amaranthus cruentus): effect of phytates on in vitro iron absorption.

    PubMed

    Mario Sanz-Penella, Juan; Laparra, José Moisés; Sanz, Yolanda; Haros, Monika

    2012-03-01

    The objective of the present study was to evaluate the effect of the bread supplemented with whole amaranth flour (0, 20 and 40%) on iron bioavailability using Caco-2 cells model. The phytate and lower myo-inositol phosphates content in in vitro bread digests were measured by high pressure liquid chromatography. The breads made with amaranth showed significant increase of soluble phytates levels (up to 1.20 μmol/g in dry matter for the 40% of substitution) in comparison with controls, which have not detectable values. A negative correlation among phytate and Fe availability was found when increased levels of amaranth.Ferritin concentration was found 2.7- and 2.0-fold higher (P<0.05) in cultures exposed to 20% and 40% of amaranth formulated bread samples, respectively, compared to control bread. The soluble phytate/Fe molar ratio explained the whole amaranth flour-mediated inhibitory effect associated to the limitation of available Fe; however, the use up to 20% of amaranth in bread formulation appears as a promising strategy to improve the nutritional value of bread, as indicated by the ferritin concentrations quantified in cell cultures. Higher proportion of amaranth flour increased Fe concentration although there was not detected any increase in Fe uptake.

  6. Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism.

    PubMed

    Horniblow, Richard D; Dowle, Miriam; Iqbal, Tariq H; Latunde-Dada, Gladys O; Palmer, Richard E; Pikramenou, Zoe; Tselepis, Chris

    2015-01-01

    Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05) and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron, especially in the context of inflammatory bowel disease and colorectal cancer where excess unabsorbed luminal iron is thought to be a driver of disease.

  7. Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism

    PubMed Central

    Horniblow, Richard D.; Dowle, Miriam; Iqbal, Tariq H.; Latunde-Dada, Gladys O.; Palmer, Richard E.

    2015-01-01

    Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05) and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron, especially in the context of inflammatory bowel disease and colorectal cancer where excess unabsorbed luminal iron is thought to be a driver of disease. PMID:26378798

  8. Zero-valent iron removal rates of aqueous Cr(VI) measured under flow conditions

    SciTech Connect

    Kaplan, Daniel I.; Gilmore, Tyler J.

    2004-06-30

    The rates of Cr(VI) removal from the aqueous phase by zero-valent iron Fe(0) was measured under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a gournwater remediation technology that replaces the sand in a filter pack of a conventioanl well with a reactive material, such as Fe(0).

  9. Calcite precipitation dominates the electrical signatures of zero valent iron columns under simulated field conditions.

    PubMed

    Wu, Yuxin; Versteeg, Roelof; Slater, Lee; LaBrecque, Douglas

    2009-05-12

    Calcium carbonate is a secondary mineral precipitate influencing zero valent iron (ZVI) barrier reactivity and hydraulic performance. We conducted column experiments to investigate electrical signatures resulting from concurrent CaCO(3) and iron oxides precipitation under simulated field geochemical conditions. We identified CaCO(3) as a major mineral phase throughout the columns, with magnetite present primarily close to the influent based on XRD analysis. Electrical measurements revealed decreases in conductivity and polarization of both columns, suggesting that electrically insulating CaCO(3) dominates the electrical response despite the presence of electrically conductive iron oxides. SEM/EDX imaging suggests that the electrical signal reflects the geometrical arrangement of the mineral phases. CaCO(3) forms insulating films on ZVI/magnetite surfaces, restricting charge transfer between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions via charge transfer, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss due to CaCO(3) precipitation. Comparison between laboratory and field data shows consistent changes in electrical signatures due to iron corrosion and secondary mineral precipitation.

  10. Calcite precipitation dominates the electrical signatures of zero valent iron columns under simulated field conditions

    SciTech Connect

    Wu, Yuxin; Versteeg, R.; Slater, L.; LaBrecque, D.

    2009-06-01

    Calcium carbonate is a secondary mineral precipitate influencing zero valent iron (ZVI) barrier reactivity and hydraulic performance. We conducted column experiments to investigate electrical signatures resulting from concurrent CaCO{sub 3} and iron oxides precipitation under simulated field geochemical conditions. We identified CaCO{sub 3} as a major mineral phase throughout the columns, with magnetite present primarily close to the influent based on XRD analysis. Electrical measurements revealed decreases in conductivity and polarization of both columns, suggesting that electrically insulating CaCO{sub 3} dominates the electrical response despite the presence of electrically conductive iron oxides. SEM/EDX imaging suggests that the electrical signal reflects the geometrical arrangement of the mineral phases. CaCO{sub 3} forms insulating films on ZVI/magnetite surfaces, restricting charge transfer between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions via charge transfer, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss due to CaCO{sub 3} precipitation. Comparison between laboratory and field data shows consistent changes in electrical signatures due to iron corrosion and secondary mineral precipitation.

  11. The interactive biotic and abiotic processes of DDT transformation under dissimilatory iron-reducing conditions.

    PubMed

    Jin, Xin; Wang, Fang; Gu, Chenggang; Yang, Xinglun; Kengara, Fredrick O; Bian, Yongrong; Song, Yang; Jiang, Xin

    2015-11-01

    The objective of the study was to elucidate the biotic and abiotic processes under dissimilatory iron reducing conditions involved in reductive dechlorination and iron reduction. DDT transformation was investigated in cultures of Shewanella putrefaciens 200 with/without α-FeOOH. A modified first-order kinetics model was developed and described DDT transformation well. Both the α-FeOOH reduction rate and the dechlorination rate of DDT were positively correlated to the biomass. Addition of α-FeOOH enhanced reductive dechlorination of DDT by favoring the cell survival and generating Fe(II) which was absorbed on the surface of bacteria and iron oxide. 92% of the absorbed Fe(II) was Na-acetate (1M) extractable. However, α-FeOOH also played a negative role of competing for electrons as reflected by the dechlorination rate of DDT was inhibited when increasing the α-FeOOH from 1 g L(-1) to 5 g L(-1). DDT was measured to be toxic to S. putrefaciens 200. The metabolites DDD, DDE and DDMU were recalcitrant to S. putrefaciens 200. The results suggested that iron oxide was not the key factor to promote the dissipation of DDX (DDT and the metabolites), whereas the one-electron reduction potential (E1) of certain organochlorines is the main factor and that the E1 higher than the threshold of the reductive driving forces of DIRB probably ensures the occur of reductive dechlorination.

  12. Effect of different levels of an ascorbic acid and tea mixture on nonheme iron absorption from a typical Tunisian meal fed to healthy rats.

    PubMed

    Hamdauoui, M; Doghri, T; Tritar, B

    1995-01-01

    The aim of our study was to evaluate the bioavailability of iron from a typical Tunisian meal 'couscous' provided to healthy rats with or without appropriate mixtures of tea plus ascorbic acid and to search for the optimal amount of ascorbic acid able to overcome the inhibitory effect of tea prepared under realistic Tunisian circumstances. Our findings show that a tea decoction (100 mg/ml) reduced nonheme iron absorption from couscous by 50% (16.5 vs. 33.1%; p < 0.01). In contrast, administration of 20 mg ascorbic acid increased nonheme iron absorption from couscous by more than 100% (66.8 vs. 33.1%; p < 0.001). Administration of ascorbic acid (20 mg) in a tea decoction (100 mg/ml) completely counteracted the inhibiting effect of tea and significantly improved the nonheme iron absorption from couscous (34 vs. 33% in the control group; NS). The same effect was shown when 10 mg ascorbic acid was added to the tea decoction; however, 5 mg ascorbic acid was not able to overcome the inhibitory effect of tea on nonheme iron absorption from couscous (33.1 vs. 19.4%; p < 0.01). Our findings demonstrate that a molar ratio of ascorbic acid and tea equal or superior to 0.25 or 0.50 is necessary to overcome the inhibitory effect in rats of tea prepared under Tunisian circumstances. In relation to human nutrition, for Tunisians who regularly drink tea, we suggest a much greater amount of ascorbic acid than that normally recommended for normal subjects.

  13. Redox State of Iron in Lunar Glasses using X-ray Absorption Spectroscopy and Multivariate Analysis

    NASA Astrophysics Data System (ADS)

    Dyar, M. D.; McCanta, M. C.; Lanzirotti, A.; Sutton, S. R.; Carey, C. J.; Mahadevan, S.; Rutherford, M. J.

    2014-12-01

    The oxidation state of igneous materials on a planet is a critically-important variable in understanding magma evolution on bodies in our solar system. However, direct and indirect methods for quantifying redox states are challenging, especially across the broad spectrum of silicate glass compositions found on airless bodies. On the Moon, early Mössbauer studies of bulk samples suggested the presence of significant Fe3+ (>10%) in lunar glasses (green, orange, brown); lunar analog glasses synthesized at fO2 <10-11 have similar Fe3+. All these Mössbauer spectra are challenging to interpret due to the presence of multiple coordination environments in the glasses. X-ray absorption spectroscopy (XAS) allows pico- and nano-scale interrogation of primitive planetary materials using the pre-edge, main edge, and EXAFS regions of absorption edge spectra. Current uses of XAS require availability of standards with compositions similar to those of unknowns and complex procedures for curve-fitting of pre-edge features that produce results with poorly constrained accuracy. A new approach to accurate and quantitative redox measurements with XAS is to couple use of spectra from synthetic glass standards covering a broad compositional range with multivariate analysis (MVA) techniques. Mössbauer and XAS spectra from a suite of 33 synthetic glass standards covering a wide range of compositions and fO2(Dyar et al., this meeting) were used to develop a MVA model that utilizes valuable predictive information not only in the major spectral peaks/features, but in all channels of the XAS region. Algorithms for multivariate analysis t were used to "learn" the characteristics of a data set as a function of varying spectral characteristics. These models were applied to the study of lunar glasses, which provide a challenging test case for these newly-developed techniques due to their very low fO2. Application of the new XAS calibration model to Apollo 15 green (15426, 15427 and 15425

  14. Electromagnetic Energy Absorption and Its Distribution for Man and Animals at Different Frequencies under Various Conditions.

    DTIC Science & Technology

    1978-11-01

    whole-body absorption for the other t ~o configurations (major length oriented along the direction of propagation (kil ) or along the (continued over) D...IFO1473 EDITION OF I NOV GS IS OBSOLETE SECURITY CLASSIFICATION Ol T IS DAGE (WhIn Data Antered) • L .. . . ... |R -.L..jITY CLASSIFICATION OF THIS...Gandhi, "Conditions of Strongest Electromagnetic Power Deposi- tion in Man and Animals", IE T !’ 7Ia’ract~nc on .ioraoe ,heoro and Techniques, Vol. MTT

  15. Inclusion of guava enhances non-heme iron bioavailability but not fractional zinc absorption from a rice-based meal in adolescents.

    PubMed

    Nair, Krishnapillai Madhavan; Brahmam, Ginnela N V; Radhika, Madhari S; Dripta, Roy Choudhury; Ravinder, Punjal; Balakrishna, Nagalla; Chen, Zhensheng; Hawthorne, Keli M; Abrams, Steven A

    2013-06-01

    Assessing the bioavailability of non-heme iron and zinc is essential for recommending diets that meet the increased growth-related demand for these nutrients. We studied the bioavailability of iron and zinc from a rice-based meal in 16 adolescent boys and girls, 13-15 y of age, from 2 government-run residential schools. Participants were given a standardized rice meal (regular) and the same meal with 100 g of guava fruit (modified) with (57)Fe on 2 consecutive days. A single oral dose of (58)Fe in orange juice was given at a separate time as a reference dose. Zinc absorption was assessed by using (70)Zn, administered intravenously, and (67)Zn given orally with meals. The mean hemoglobin concentration was similar in girls (129 ± 7.8 g/L) and boys (126 ± 7.1 g/L). There were no sex differences in the indicators of iron and zinc status except for a higher hepcidin concentration in boys (P < 0.05). The regular and modified meals were similar in total iron (10-13 mg/meal) and zinc (2.7 mg/meal) content. The molar ratio of iron to phytic acid was >1:1, but the modified diet had 20 times greater ascorbic acid content. The absorption of (57)Fe from the modified meal, compared with regular meal, was significantly (P < 0.05) greater in both girls (23.9 ± 11.2 vs. 9.7 ± 6.5%) and boys (19.2 ± 8.4 vs. 8.6 ± 4.1%). Fractional zinc absorption was similar between the regular and modified meals in both sexes. Hepcidin was found to be a significant predictor of iron absorption (standardized β = -0.63, P = 0.001, R(2) = 0.40) from the reference dose. There was no significant effect of sex on iron and zinc bioavailability from meals. We conclude that simultaneous ingestion of guava fruit with a habitual rice-based meal enhances iron bioavailability in adolescents.

  16. Experimental versus ab initio x-ray absorption of iron-doped zirconia: Trends in O K -edge spectra as a function of iron doping

    NASA Astrophysics Data System (ADS)

    Douma, D. H.; Ciprian, R.; Lamperti, A.; Lupo, P.; Cianci, E.; Sangalli, D.; Casoli, F.; Nasi, L.; Albertini, F.; Torelli, P.; Debernardi, A.

    2014-11-01

    We present an experimental study of x-ray absorption near edge structure (XANES) at L2 ,3,M2 ,3, and K edges of, respectively, Fe, Zr, and O in iron-doped zirconia (ZrO2:Fe ) for different Fe dopant concentrations x (from x ˜6 % to x ˜25 % at.) and make the comparison with ab initio simulations at the O K -edge. The x-ray magnetic circular dichroism (XMCD) measurements show no evidence of ferromagnetic (FM) order for all the analyzed samples in agreement with our ab initio simulations, which show an antiferromagnetic (AFM) order. We found that substituting Zr with Fe atoms leads to a radical change in the O K -edge XANES spectrum, especially in the pre-edge region where a pre-edge peak appears. This pre-edge peak is ascribed to dipole transitions from O 1 s to O 2 p states that are hybridized with the unoccupied Fe 3 d states. Both theoretical and experimental results reveal that the intensity of the pre-edge peak increases with Fe concentration, suggesting the increase of unoccupied Fe 3 d states. The increase of Fe concentration increases oxygen vacancies as required for charge neutrality and consequently improves AFM ordering. According to our first-principles calculations, the effect of one Fe atom is mostly localized in the first oxygen shell and vanishes as one moves far from it. Thus the increase of the O K -pre-edge peak with increasing Fe concentration is due to the increase of percentage of oxygen atoms that are near neighbors to Fe atoms.

  17. Anaerobic Biodegradation Of Methyl tert-Butyl Ether Under Iron-Reducing Conditions In Batch And Continuous-Flow Cultures

    EPA Science Inventory

    The feasibility of biodegradation of the fuel oxygenate methyl tert-butyl ether (MTBE) under iron-reducing conditions was explored in batch and continuous-flow systems. A porous pot completely-mixed reactor was seeded with diverse cultures and operated under iron-reducing...

  18. Biofortification of pearl millet with iron and zinc in a randomized controlled trial increases absorption of these minerals above physiologic requirements in young children.

    PubMed

    Kodkany, Bhalchandra S; Bellad, Roopa M; Mahantshetti, Niranjana S; Westcott, Jamie E; Krebs, Nancy F; Kemp, Jennifer F; Hambidge, K Michael

    2013-09-01

    Millet is unusually drought resistant and consequently there is a progressive increase in the use of these grains as a human food staple, especially in large areas of India and sub-Saharan Africa. The purpose of this study was to determine the absorption of iron and zinc from pearl millet biofortified with 2 micronutrients that are typically deficient in nonfortified, plant-based diets globally. The study was undertaken in 40 children aged 2 y in Karnataka, India (n = 21 test/19 controls). Three test meals providing ∼84 ± 17 g dry pearl millet flour were fed on a single day for zinc and 2 d for iron between 0900 and 1600 h. The quantities of zinc and iron absorbed were measured with established stable isotope extrinsic labeling techniques and analyses of duplicate diets. The mean (± SD) quantities of iron absorbed from test and control groups were 0.67 ± 0.48 and 0.23 ± 0.15 mg/d, respectively (P < 0.001). The quantities of zinc absorbed were 0.95 ± 0.47 and 0.67 ± 0.24 mg/d, respectively (P = 0.03). These data did not include absorption of the modest quantities of iron and zinc contained in snacks eaten before and after the 3 test meals. In conclusion, quantities of both iron and zinc absorbed when iron and zinc biofortified pearl millet is fed to children aged 2 y as the major food staple is more than adequate to meet the physiological requirements for these micronutrients.

  19. A Variable Energy, Redshifted, Iron Absorption Line in a recoiling Black Hole

    NASA Astrophysics Data System (ADS)

    Civano, Francesca

    The aim of this proposal is to maximize the scientific return of a medium deep (123 ksec) XMM-Newton observation, awarded during the AO10 call for proposal, to obtain a high quality X-ray spectrum of CID-42, a very peculiar source discovered in the COSMOS survey. CID-42 is exceptional in many respects showing a redshifted, variable energy absorption line plus an emission line at ~ 6 keV forming an inverted P-Cygni profile. These features were never observed before in the X-rays. The peculiar nature of CID-42 extends well beyond the X-ray spectrum. First, two optical sources in a common envelope are clearly seen in the HST data. They are separated by about 2.45 kpc. Thanks to the unrivaled Chandra HRC resolution it was possible to unambiguously associate the X-ray emission to only one of the two optical sources. Second, a high velocity (1100 km/s) offset, between the broad and narrow component of the H-beta line is measured in the VLT/Magellan/Keck optical spectra. The velocity offset observed is unlikely to be due to a ongoing merger because too high. Third, the above mentioned inverted P-Cygni profile in the hard X-ray spectrum would be naturally explained by an high velocity (v~0.02-0.14c) gas infall in the innermost region of the accreting Black Hole. All together the observed properties support the interpretation of a Black Hole kicked from the center of the galaxy by asymmetric emission of gravitational waves produced during a major merger. The Black Hole is caught while still active, at ~10^6 yrs after the kick and at a substantial distance from the center of the galaxy. The theoretical expectations suggest that they are extremely rare and just 1 or 2 gravitational wave recoiling Black Holes are expected in a survey like COSMOS. CID- 42 thus represents a ``Rosetta stone'' for the study of SMBH mergers that are believed to occur during galaxy-galaxy mergers, and their fate after the merging. The detailed study of the hard X-ray XMM-Newton spectrum, in the

  20. [Development of the iron supply in suckling pigs under variable iron supplementation with regard to environmental conditions].

    PubMed

    Lemacher, S; Bostedt, H

    1995-10-01

    In this research the effect of different methods of iron supplementation, injection of Fe(III) dextran six or 70 hours post natum, oral Fe(III) dextran treatment or oral application of Fe(II)-Humat, each six hours post natum, was examined for the evaluation of hemoglobin, plasma iron and weight of suckling piglets within the first 24 days of life in different systems of stalling. The oral and parenteral iron dextran application resulted in a remarkable increase of the hemoglobin levels after the third day of life. On day eight the hemoglobin concentrations obtained by early postnatal iron administration were higher than the values after the usual iron injection on the third day of life. The iron incorporation by Fe-Humat was not sufficient for obtaining a rise in hemoglobin values. No significant differences were seen between the oral or parenteral iron dextran treated groups reared on iron containing floor. In the farrowing on plastic grates the piglets supplemented orally with iron dextran showed a decrease of hemoglobin level starting at day 14. At day 24 the values were significantly lower than after iron injection. In all treatment groups there were more anaemic piglets in the group farrowing system than in the separate farrowing system. Weight gain was remarkably worse too. The immediately postnatal treated piglets had significantly higher PI levels on day three than the animals treated at the third day of life. The plasma iron concentration decreased in all treatment groups from day eight, but the decrease was more important in the orally supplemented groups.

  1. Opacity of iron, nickel, and copper plasmas in the x-ray wavelength range: Theoretical interpretation of 2p-3d absorption spectra

    SciTech Connect

    Blenski, T.; Loisel, G.; Poirier, M.; Thais, F.; Arnault, P.; Caillaud, T.; Fariaut, J.; Gilleron, F.; Pain, J.-C.; Porcherot, Q.; Reverdin, C.; Silvert, V.; Villette, B.; Bastiani-Ceccotti, S.; Turck-Chieze, S.; Foelsner, W.; Gaufridy de Dortan, F. de

    2011-09-15

    This paper deals with theoretical studies on the 2p-3d absorption in iron, nickel, and copper plasmas related to LULI2000 (Laboratoire pour l'Utilisation des Lasers Intenses, 2000J facility) measurements in which target temperatures were of the order of 20 eV and plasma densities were in the range 0.004-0.01 g/cm{sup 3}. The radiatively heated targets were close to local thermodynamic equilibrium (LTE). The structure of 2p-3d transitions has been studied with the help of the statistical superconfiguration opacity code sco and with the fine-structure atomic physics codes hullac and fac. A new mixed version of the sco code allowing one to treat part of the configurations by detailed calculation based on the Cowan's code rcg has been also used in these comparisons. Special attention was paid to comparisons between theory and experiment concerning the term features which cannot be reproduced by sco. The differences in the spin-orbit splitting and the statistical (thermal) broadening of the 2p-3d transitions have been investigated as a function of the atomic number Z. It appears that at the conditions of the experiment the role of the term and configuration broadening was different in the three analyzed elements, this broadening being sensitive to the atomic number. Some effects of the temperature gradients and possible non-LTE effects have been studied with the help of the radiative-collisional code scric. The sensitivity of the 2p-3d structures with respect to temperature and density in medium-Z plasmas may be helpful for diagnostics of LTE plasmas especially in future experiments on the {Delta}n=0 absorption in medium-Z plasmas for astrophysical applications.

  2. Inclusion of ancient Latin-American crops in bread formulation improves intestinal iron absorption and modulates inflammatory markers.

    PubMed

    Laparra, José Moisés; Haros, Monika

    2016-02-01

    This study compares iron (Fe) absorption in Fe-deficient animals from bread formulations prepared by substitution of white wheat flour (WB) by whole wheat flour (WWB), amaranth flour (Amaranthus hypochondriacus, 25%) (AB) and quinoa flour (Chenopodium quinoa, 25%) (QB), or chia flour (Salvia hispanica L, 5%) (ChB). Hematological parameters of Fe homeostasis, plasmatic active hepcidin peptide production (LC coupled to Ms/Ms), and liver TfR-2 and IL-6 expression (RT-qPCR) were determined. The different bread formulations increased Fe content between 14% and 83% relative to white bread. Only animals fed with WWB, AB and ChB increased haemoglobin concentrations significantly. Feeding the different bread formulations did not increase hepcidin levels, but down-regulated transferrin receptor 2 (TfR2) (apart from WWB) and IL-6 (apart from QB) expression levels. Only AB and ChB had a significant influence on Fe bioavailability at the investigated level of substitution. The potential contribution of these flours would not differ considerably from that of WWB.

  3. Excellent improvement in the static and dynamic magnetic properties of carbon coated iron nanoparticles for microwave absorption

    NASA Astrophysics Data System (ADS)

    Khani, Omid; Shoushtari, Morteza Zargar; Farbod, Mansoor

    2015-11-01

    Carbon coated iron nanoparticles were synthesized, using a simple arc-discharge method. The morphology and the internal structure of the core/shell nanoparticles were studied, using field emission scanning electron microscopy and transmission electron microscopy. X-ray diffraction analysis showed that both magnetic α-Fe and nonmagnetic γ-Fe phases existed in the as-prepared particles. In order to improve the static and dynamic magnetic properties of the core/shell nanoparticles, the produced nanocapsules were annealed in argon atmosphere at two different temperatures. Hysteresis loops revealed that the value of the saturation magnetization (MS) increased more than 4.1 times of its original value by annealing and this led to 70% increase in the imaginary part of the permeability. Phase analysis showed that heat treatment eliminated the nonmagnetic γ-Fe phase completely. The reflection loss plots were studied for composite layers containing 20 vol% of the annealed and not annealed nanocapsules. One of the absorber layers which contained annealed nanocapsules showed at least -10 dB loss in the whole G, C, X and Ku frequency bands and the optimal absorption exceeded -37 dB at 5.8 GHz for the as-prepared sample with a thickness of 3.2 mm. The results revealed that the magnetic properties of the arc-made Fe/C core/shell nanoparticle can be improved significantly by annealing in argon.

  4. Laboratory Evaluation and Application of Microwave Absorption Properties Under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1998-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties taken under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. For example, laboratory measurements completed recently by Kolodner and Steffes (ICARUS 132, pp. 151-169, March 1998, attached as Appendix A) under this grant (NAGS-4190), have shown that the opacity from gaseous H2SO4 under simulated Venus conditions is best described by a different formalism than was previously used. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both spacecraft entry probe and orbiter radio occultation experiments and by radio astronomical observations, and over a range of frequencies which correspond to those used in such experiments, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  5. Laboratory Evaluation and Application of Microwave Absorption Properties under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    2002-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth-based or spacecraft-based radio astronomical (emission) observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or the use of laboratory measurements of such properties taken under environmental conditions that are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurements have shown that the centimeter-wavelength opacity from gaseous phosphine (PH3) under simulated conditions for the outer planets far exceeds that predicted from theory over a wide range of temperatures and pressures. This fundamentally changed the resulting interpretation of Voyager radio occultation data at Saturn and Neptune. It also directly impacts planning and scientific goals for study of Saturn's atmosphere with the Cassini Radio Science Experiment and the Rossini RADAR instrument. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both spacecraft entry probe and orbiter (or flyby) radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations

  6. New insights into iron deficiency and iron deficiency anemia.

    PubMed

    Camaschella, Clara

    2017-02-13

    Recent advances in iron metabolism have stimulated new interest in iron deficiency (ID) and its anemia (IDA), common conditions worldwide. Absolute ID/IDA, i.e. the decrease of total body iron, is easily diagnosed based on decreased levels of serum ferritin and transferrin saturation. Relative lack of iron in specific organs/tissues, and IDA in the context of inflammatory disorders, are diagnosed based on arbitrary cut offs of ferritin and transferrin saturation and/or marker combination (as the soluble transferrin receptor/ferritin index) in an appropriate clinical context. Most ID patients are candidate to traditional treatment with oral iron salts, while high hepcidin levels block their absorption in inflammatory disorders. New iron preparations and new treatment modalities are available: high-dose intravenous iron compounds are becoming popular and indications to their use are increasing, although long-term side effects remain to be evaluated.

  7. A photo-oxidation procedure using UV radiation/H 2O 2 for decomposition of wine samples — Determination of iron and manganese content by flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    dos Santos, Walter N. L.; Brandão, Geovani C.; Portugal, Lindomar A.; David, Jorge M.; Ferreira, Sérgio L. C.

    2009-06-01

    This paper proposes the use of photo-oxidation with UV radiation/H 2O 2 as sample pretreatment for the determination of iron and manganese in wines by flame atomic absorption spectrometry (FAAS). The optimization involved the study of the following variables: pH and concentration of buffer solution, concentrated hydrogen peroxide volume and irradiation time. The evaluation of sample degradation was monitored by measuring the absorbance at the maximum wavelength of red wine (530 nm). Using the experimental conditions established during the optimization (irradiation time of 30 min, oxidant volume of 2.5 mL, pH 10, and a buffer concentration of 0.15 mol L - 1 ), this procedure allows the determination of iron and manganese with limits of detection of 30 and 22 μg L - 1 , respectively, for a 5 mL volume of digested sample. The precision levels, expressed as relative standard deviation (RSD), were 2.8% and 0.65% for iron and 2.7% and 0.54% for manganese for concentrations of 0.5 and 2.0 mg L - 1 , respectively. Addition/recovery tests for evaluation of the accuracy were in the ranges of 90%-111% and 95%-107% for iron and manganese, respectively. This digestion procedure has been applied for the determination of iron and manganese in six wine samples. The concentrations varied from 1.58 to 2.77 mg L - 1 for iron and from 1.30 to 1.91 mg L - 1 for manganese. The results were compared with those obtained by an acid digestion procedure and determination of the elements by FAAS. There was no significant difference between the results obtained by the two methods based on a paired t-test (at 95% confidence level).

  8. Fretting wear of iron, nickel, and titanium under varied environmental conditions

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1978-01-01

    Fretting wear experiments were conducted on high purity iron, nickel and titanium in air under conditions of varied humidity and temperature, and in nitrogen. For iron and titanium, maximum fretting occurred at 10 and 30 percent relative humidity respectively. Nickel showed a minimum in fretting wear at about 10 percent relative humidity. With increasing temperature, all three metals initially showed reduced fretting wear, with increasing wear observed as temperatures increased beyond 200-300 C. For titanium, dramatically reduced fretting wear was observed at temperatures above 500 C, relatable to a change in oxidation kinetics. All three metals showed much less fretting wear in N2 with the presence of moisture in N2 having a proportionally stronger effect than in air.

  9. Rapid determination of zinc and iron in foods by flow-injection analysis with flame atomic-absorption spectrophotometry and slurry nebulization.

    PubMed

    de Andrade, J C; Strong, F C; Martin, N J

    1990-07-01

    A rapid method of determining zinc and iron in food by flame atomic-absorption spectrophotometry with slurry nebulization into an air-acetylene flame has been developed. A V-groove, clog-free Babington-type nebulizer, coupled to a single-line flow-injection analysis (FIA) system, was employed to introduce the slurry into the spray chamber. Under the FIA conditions described, an injection frequency of 120/hr is possible, with negligible carry-over and memory effects. The calibration graphs were obtained by using various concentrations (up to 0.1 g/ml) of white bean homogenate as standards, rather than solutions. The method has been applied to various kinds of foods, including grains, vegetables, fruits and sausage. Homogenization of semi-prepared samples to form slurries took only 4 min. Relative deviations between results by the slurry and solution methods for both elements averaged 2-3%. Detection limits by the slurry method were 0.3 mug/ml Zn and 0.6 mug/ml Fe.

  10. Ligandless dispersive liquid--liquid microextraction of iron in biological and foodstuff samples and its determination by Electrothermal atomic absorption spectrometry.

    PubMed

    Madadizadeh, Mohadeseh; Taher, Mohammad Ali; Ashkenani, Hamid

    2013-01-01

    A new, simple, and efficient method comprising ligandless dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry is reported for the preconcentration and determination of ultratrace amounts of Fe(III). Carbon tetrachloride and acetone were used as the extraction and disperser solvents, respectively. Some effective parameters of the microextraction such as choice of extraction and disperser solvents, their volume, extraction time and temperature, salt and surfactant effect, and pH were optimized. Under the optimum conditions, the calibration curve was linear in the range of 0.02 to 0.46 microg/L of Fe(III), with LOD and LOQ of 5.2 and 17.4 ng/L, respectively. The RSD for seven replicated determinations of Fe(IIl) ion at 0.1 microg/L concentration level was 5.2%. Operational simplicity, rapidity, low cost, good repeatability, and low consumption of extraction solvent are the main advantages of the proposed method. The method was successfully applied to the determination of iron in biological, food, and certified reference samples.

  11. Influence of iron precipitated condition and light intensity on microalgae activated sludge based wastewater remediation.

    PubMed

    Anbalagan, Anbarasan; Schwede, Sebastian; Lindberg, Carl-Fredrik; Nehrenheim, Emma

    2017-02-01

    The indigenous microalgae-activated sludge (MAAS) process during remediation of municipal wastewater was investigated by studying the influence of iron flocculation step and light intensity. In addition, availability of total phosphorous (P) and photosynthetic activity was examined in fed-batch and batch mode under northern climatic conditions and limited lighting. This was followed by a semi-continuous operation with 4 d of hydraulic retention time and mean cell residence time of 6.75 d in a photo-bioreactor (PBR) with varying P availability. The fed-batch condition showed that P concentrations of 3-4 mg L(-1) were effective for photosynthetic chl. a development in iron flocculated conditions. In the PBR, the oxygen evolution rate increased with increase in the concentration of MAAS (from 258 to 573 mg TSS L(-1)) at higher surface photosynthetic active radiation (250 and 500 μmol m(-2) s(-1)). Additionally, the rate approached a saturation phase at low MAAS (110 mg L(-1)) with higher light intensities. Semi-continuous operation with luxury P uptake and effective P condition showed stable average total nitrogen removal of 88 and 92% respectively, with residual concentrations of 3.77 and 2.21 mg L(-1). The corresponding average P removal was 68 and 59% with residual concentrations of 2.32 and 1.75 mg L(-1). The semi-continuous operation produced a rapidly settleable MAAS under iron flocculated condition with a settling velocity of 92-106 m h(-1) and sludge volume index of 31-43 ml g(-1) in the studied cases.

  12. THE PHYSICAL CONDITIONS OF THE INTRINSIC N V NARROW ABSORPTION LINE SYSTEMS OF THREE QUASARS

    SciTech Connect

    Wu Jian; Charlton, Jane C.; Misawa, Toru; Eracleous, Michael; Ganguly, Rajib E-mail: misawatr@shinshu-u.ac.j

    2010-10-20

    We employ detailed photoionization models to infer the physical conditions of intrinsic narrow absorption line systems found in high-resolution spectra of three quasars at z = 2.6-3.0. We focus on a family of intrinsic absorbers characterized by N V lines that are strong relative to the Ly{alpha} lines. The inferred physical conditions are similar for the three intrinsic N V absorbers, with metallicities greater than 10 times the solar value (assuming a solar abundance pattern), and with high ionization parameters (log U {approx} 0). Thus, we conclude that the unusual strength of the N V lines results from a combination of partial coverage, a high ionization state, and high metallicity. We consider whether dilution of the absorption lines by flux from the broad emission line region can lead us to overestimate the metallicities and we find that this is an unlikely possibility. The high abundances that we infer are not surprising in the context of scenarios in which metal enrichment takes place very early on in massive galaxies. We estimate that the mass outflow rate in the absorbing gas (which is likely to have a filamentary structure) is less than a few M{sub sun} yr{sup -1} under the most optimistic assumptions, although it may be embedded in a much hotter, more massive outflow.

  13. Laboratory Evaluation and Application of Microwave Absorption Properties Under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1997-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurements completed under this grant (NAGW-533), have shown that the opacity from, SO2 under simulated Venus conditions is best described by a different lineshape than was previously used in theoretical predictions. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  14. Thermo-economic approach for absorption air condition onboard high-speed crafts

    NASA Astrophysics Data System (ADS)

    Seddiek, Ibrahim S.; Mosleh, Mosaad; Banawan, Adel A.

    2012-12-01

    High-speed crafts suffer from losing a huge amount of their machinery energy in the form of heat loss with the exhaust gases. This will surely increase the annual operating cost of this type of ships and an adverse effect on the environment. This paper introduces a suggestion that may contribute to overcoming such problems. It presents the possibility of reusing the energy lost by the ships' exhaust gases as heating source for an absorption air condition unit onboard high-speed crafts. As a numerical example; the proposed method was investigated at a high-speed craft operating in Red Sea between Egypt and the Kingdom of Saudi Arabia. The results obtained are very satisfactory. It showed the possibility of providing the required ship's air condition cooling load during sailing and in port. Economically, this will reduce the annual ship's operating cost. Moreover, it will achieve a valuable reduction of ship's emissions.

  15. A revised model for Jeffrey nanofluid subject to convective condition and heat generation/absorption

    PubMed Central

    Hayat, Tasawar; Aziz, Arsalan; Muhammad, Taseer; Alsaedi, Ahmed

    2017-01-01

    Here magnetohydrodynamic (MHD) boundary layer flow of Jeffrey nanofluid by a nonlinear stretching surface is addressed. Heat generation/absorption and convective surface condition effects are considered. Novel features of Brownian motion and thermophoresis are present. A non-uniform applied magnetic field is employed. Boundary layer and small magnetic Reynolds number assumptions are employed in the formulation. A newly developed condition with zero nanoparticles mass flux is imposed. The resulting nonlinear systems are solved. Convergence domains are explicitly identified. Graphs are analyzed for the outcome of sundry variables. Further local Nusselt number is computed and discussed. It is observed that the effects of Hartman number on the temperature and concentration distributions are qualitatively similar. Both temperature and concentration distributions are enhanced for larger Hartman number. PMID:28231298

  16. A revised model for Jeffrey nanofluid subject to convective condition and heat generation/absorption.

    PubMed

    Hayat, Tasawar; Aziz, Arsalan; Muhammad, Taseer; Alsaedi, Ahmed

    2017-01-01

    Here magnetohydrodynamic (MHD) boundary layer flow of Jeffrey nanofluid by a nonlinear stretching surface is addressed. Heat generation/absorption and convective surface condition effects are considered. Novel features of Brownian motion and thermophoresis are present. A non-uniform applied magnetic field is employed. Boundary layer and small magnetic Reynolds number assumptions are employed in the formulation. A newly developed condition with zero nanoparticles mass flux is imposed. The resulting nonlinear systems are solved. Convergence domains are explicitly identified. Graphs are analyzed for the outcome of sundry variables. Further local Nusselt number is computed and discussed. It is observed that the effects of Hartman number on the temperature and concentration distributions are qualitatively similar. Both temperature and concentration distributions are enhanced for larger Hartman number.

  17. Theoretical interpretation for 2p - nd absorption spectra of iron, nickel, and copper in X-ray range measured at the LULI2000 facility

    NASA Astrophysics Data System (ADS)

    Poirier, M.; Arnault, P.; Bastiani-Ceccotti, S.; Blenski, T.; de Gaufridy de Dortan, F.; Gilleron, F.; Loisel, G.; Pain, J.-C.; Porcherot, Q.; Reverdin, C.; Silvert, V.; Thais, F.; Turck-Chièze, S.

    2013-11-01

    The 2p - nd absorption structures in medium Z elements present a valuable benchmark for atomic models since they exhibit a complex dependence on temperature and density. For these transitions lying in the X-ray range, one observes a competition between the spin-orbit splitting and the broadening associated to the excitation of complex structures. Detailed opacity codes based on the HULLAC or FAC suites agree with the statistical code SCO; but in iron computations predict higher peak absorption than measured. An addition procedure on opacities calculated with detailed codes is proposed and successfully tested.

  18. Absorption of Sunlight by Water Vapor in Cloudy Conditions: A Partial Explanation for the Cloud Absorption Anomaly

    NASA Technical Reports Server (NTRS)

    Crisp, D.

    1997-01-01

    The atmospheric radiative transfer algorithms used in most global general circulation models underestimate the globally-averaged solar energy absorbed by cloudy atmospheres by up to 25 W/sq m. The origin of this anomalous absorption is not yet known, but it has been attributed to a variety of sources including oversimplified or missing physical processes in these models, uncertainties in the input data, and even measurement errors. Here, a sophisticated atmospheric radiative transfer model was used to provide a more comprehensive description of the physical processes that contribute to the absorption of solar radiation by the Earth's atmosphere. We found that the amount of sunlight absorbed by a cloudy atmosphere is inversely proportional to the solar zenith angle and the cloud top height, and directly proportional to the cloud optical depth and the water vapor concentration within the clouds. Atmospheres with saturated, optically-thick, low clouds absorbed about 12 W/sq m more than clear atmospheres. This accounts for about 1/2 to 1/3 of the anomalous ab- sorption. Atmospheres with optically thick middle and high clouds usually absorb less than clear atmospheres. Because water vapor is concentrated within and below the cloud tops, this absorber is most effective at small solar zenith angles. An additional absorber that is distributed at or above the cloud tops is needed to produce the amplitude and zenith angle dependence of the observed anomalous absorption.

  19. Conditions for making direct reduced iron, transition direct reduced iron and pig iron nuggets in a laboratory furnace - Temperature-time transformations

    SciTech Connect

    Anameric, B.; Kawatra, S.K.

    2007-02-15

    The pig iron nugget process is gaining in importance as an alternative to the traditional blast furnace. Throughout the process, self-reducing-fluxing dried greenballs composed of iron ore concentrate, reducing-carburizing agent (coal), flux (limestone) and binder (bentonite) are heat-treated. During the heat treatment, dried greenballs are first transformed into direct reduced iron (DRI), then to transition direct reduced iron (TDRI) and finally to pig iron nuggets. The furnace temperature and/or residence time and the corresponding levels of carburization, reduction and metallization dictate these transformations. This study involved the determination of threshold furnace temperatures and residence times for completion of all of the transformation reactions and pig iron nugget production. The experiments involved the heat treatment of self-reducing-fluxing dried greenballs at various furnace temperatures and residence times. The products of these heat treatments were identified by utilizing optical microscopy, apparent density and microhardness measurements.

  20. Climatic thresholds for pedogenic iron oxides under aerobic conditions: Processes and their significance in paleoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Long, Xiaoyong; Ji, Junfeng; Barrón, Vidal; Torrent, José

    2016-10-01

    Iron oxides are widely distributed across the surface of the Earth as a result of the aerobic weathering of primary Fe-bearing minerals. Pedogenic iron oxides which consist mainly of hematite (Hm), goethite (Gt), maghemite (Mgh), are often concentrated synchronously in aerobic soils under low to moderate rainfall regimes. Magnetic susceptibility (χ) and redness, which respectively reflect the content of Mgh and Hm in soils, are considered reasonable pedogenic and climatic indicators in soil taxonomy and paleorainfall reconstruction. However, under high rainfall regimes, the grain growth of Mgh and transformation to Hm, combined with the prior formation of Gt under conditions of high relative humidity (RH), can result in magnetic reduction and dramatic yellowing of soils and sediments, which explains the existence of rainfall thresholds for Mgh and Hm at a large scale even before the pedogenic environment turns anaerobic. In order to capture the rainfall thresholds for Mgh and Hm occurring under aerobic conditions, we explored a tropical transect across a granitic region where the soil color turned from red to yellow under a wide rainfall range of 900-2200 mm/yr and a corresponding mean annual RH range of 77%-85%. We observed a lower rainfall threshold of ∼1500 mm/yr and a corresponding RH ∼80% for Mgh and Hm along this transect, as well as a higher rainfall threshold of ∼1700 mm/yr and a corresponding RH of ∼81% for Gt and total pedogenic iron oxides (citrate/bicarbonate/dithionite-extractable Fe, Fed). Cross-referencing with comparable studies in temperate and subtropical regions, we noted that the rainfall or RH thresholds for Fed and Hm or Mgh likewise increase with temperature. Moreover, the different thresholds for total and individual iron oxide phase indicates that a negative correlation between chemical weathering intensity and redness or χ in sediment sequences can occur under the prevalent climate regime just between their thresholds. Finally

  1. Thermal and magnetic anomalies of α-iron: an exploration by extended x-ray absorption fine structure spectroscopy and synchrotron x-ray diffraction.

    PubMed

    Boccato, Silvia; Sanson, Andrea; Kantor, Innokenty; Mathon, Olivier; Dyadkin, Vadim; Chernyshov, Dmitry; Carnera, Alberto; Pascarelli, Sakura

    2016-09-07

    The local structure and dynamics of α-iron have been investigated by extended x-ray absorption fine structure (EXAFS) spectroscopy and x-ray diffraction (XRD) in order to shed light on some thermal and magnetic anomalies observed in the last decades. The quantitative EXAFS analysis of the first two coordination shells reveals a peculiar local vibrational dynamics of α-iron: the second neighbor distance exhibits anharmonicity and vibrational anisotropy larger than the first neighbor distance. We search for possible distortions of the bcc structure to justify the unexplained magnetostriction anomalies of α-iron and provide a value for the maximum dislocation of the central Fe atom. No thermal anomalies have been detected from the current XRD data. On the contrary, an intriguing thermal anomaly at about 150 K, ascribed to a stiffening of the Fe-Fe bonds, was found by EXAFS.

  2. Thermal and magnetic anomalies of α-iron: an exploration by extended x-ray absorption fine structure spectroscopy and synchrotron x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Boccato, Silvia; Sanson, Andrea; Kantor, Innokenty; Mathon, Olivier; Dyadkin, Vadim; Chernyshov, Dmitry; Carnera, Alberto; Pascarelli, Sakura

    2016-09-01

    The local structure and dynamics of α-iron have been investigated by extended x-ray absorption fine structure (EXAFS) spectroscopy and x-ray diffraction (XRD) in order to shed light on some thermal and magnetic anomalies observed in the last decades. The quantitative EXAFS analysis of the first two coordination shells reveals a peculiar local vibrational dynamics of α-iron: the second neighbor distance exhibits anharmonicity and vibrational anisotropy larger than the first neighbor distance. We search for possible distortions of the bcc structure to justify the unexplained magnetostriction anomalies of α-iron and provide a value for the maximum dislocation of the central Fe atom. No thermal anomalies have been detected from the current XRD data. On the contrary, an intriguing thermal anomaly at about 150 K, ascribed to a stiffening of the Fe-Fe bonds, was found by EXAFS.

  3. X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

    SciTech Connect

    DeWitt, J.G.

    1992-12-01

    The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 [Angstrom]. The Fe-Fe distance was determined to be 3.4 [Angstrom]. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

  4. X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

    SciTech Connect

    DeWitt, Jane G.

    1992-12-01

    The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 Å. The Fe-Fe distance was determined to be 3.4 Å. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

  5. Understanding Sulfur Poisoning and Regeneration of Nickel Biomass Conditioning Catalysts using X-Ray Absorption Spectroscopy

    SciTech Connect

    Yung, M. M.; Cheah, S.; Kuhn, J. N.

    2013-01-01

    The production of biofuels can proceed via a biomass gasification to produce syngas, which can then undergo catalytic conditioning and reforming reactions prior to being sent to a fuel synthesis reactor. Catalysts used for biomass conditioning are plagued by short lifetimes which are a result of, among other things, poisoning. Syngas produced from biomass gasification may contain between 30-300 ppm H2S, depending on the feedstock and gasification conditions, and H2S is a key catalyst poison. In order to overcome catalyst poisoning, either an H2S-tolerant catalyst or an efficient regeneration protocol should be employed. In this study, sulfur K-edge X-ray absorption near edge spectroscopy (XANES) was used to monitor sulfur species on spent catalyst samples and the transformation of these species from sulfides to sulfates during steam and air regeneration on a Ni/Mg/K/Al2O3 catalyst used to condition biomass-derived syngas. Additionally, nickel K-edge EXAFS and XANES are used to examine the state of nickel species on the catalysts. Post-reaction samples showed the presence of sulfides on the H2S-poisoned nickel catalyst and although some gaseous sulfur species were observed to leave the catalyst bed during regeneration, sulfur remained on the catalyst and a transformation from sulfides to sulfates was observed. The subsequent H2 reduction led to a partial reduction of sulfates back to sulfides. A proposed reaction sequence is presented and recommended regeneration strategies are discussed.

  6. Condition for unity absorption in an ultrathin and highly lossy film in a Gires-Tournois interferometer configuration.

    PubMed

    Park, Junghyun; Kim, Soo Jin; Brongersma, Mark L

    2015-05-01

    We present a condition for unity absorption for a Gires-Tournois interferometer configuration constructed from an ultrathin and highly lossy film on top of metallic mirror. From the impedance matching condition in the transmission line theory, we identify a solution space for the required complex refractive index of the lossy film in various film thickness and dielectric constants of the metallic mirror. It is shown that strong absorption requires the imaginary part of the refractive index of the ultrathin lossy film be larger than 0.64, and the physical origin of this condition is elucidated. The proposed method is useful in identifying candidate semiconductor materials that can be used as the lossy film in a unity-absorption Gires-Tournois interferometer configuration and designing the thickness of this film to maximize absorption.

  7. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1992-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. The goal of this investigation was to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  8. Liquid Iron Alloys with Hydrogen at Outer Core Conditions by First Principles

    NASA Astrophysics Data System (ADS)

    Umemoto, K.; Hirose, K.

    2015-12-01

    Since the density of the outer core deduced from seismic data is about 10% lower than that of pure iron at core pressures and temperatures (P-T), it is widely believed that the outer core includes one or more light elements. Although intensive experimental and theoretical studies have been performed so far, the light element in the core has not yet been identified. Comparison of the density and sound velocity of liquid iron alloys with observations, such as the PREM, is a promising way to determine the species and quantity of light alloying component(s) in the outer core. Here we report the results of a first-principles molecular dynamics study on liquid iron alloyed with hydrogen, one of candidates of the light elements. Hydrogen had been much less studied than other candidates. However, hydrogen has been known to reduce the melting temperature of Fe-H solid [1]. Furthermore, very recently, Nomura et al. argued that the outer core may include 24 at.% H in order to be molten under relatively low temperature (< 3600 K) [2]. Since then hydrogen has attracted strong interests. We clarify the effects of hydrogen on density and sound velocity of liquid iron alloys under outer core P-T conditions. It is shown that ~1 wt% hydrogen can reproduce PREM density and sound velocity simultaneously very well. In addition, we show the presence of hydrogen rather reduces Gruneisen parameters. It indicates that, if hydrogen exists in the outer core, temperature profile of the outer core could be changed considerably from one estimated so far. [1] Sakamaki, K., E. Takahashi, Y. Nakajima, Y. Nishihara, K. Funakoshi, T. Suzuki, and Y. Fukai, Phys. Earth Planet. Inter., 174, 192-201 (2009). [2] Nomura, R., K. Hirose, K. Uesugi, Y. Ohishi, A. Tsuchiyama, A. Miyake, and Y. Ueno, Science 31, 522-525 (2014).

  9. Iron deficiency: new insights into diagnosis and treatment.

    PubMed

    Camaschella, Clara

    2015-01-01

    Iron deficiency and iron deficiency anemia are common conditions worldwide affecting especially children and young women. In developing countries, iron deficiency is caused by poor iron intake and/or parasitic infection, whereas vegetarian dietary choices, poor iron absorption, and chronic blood loss are common causes in high-income countries. Erythropoiesis stimulating agents can result in functional iron deficiency for erythropoiesis even when stores are iron-replete. Diagnosis of iron deficiency is straightforward, except when it occurs in the context of inflammatory disorders. Oral iron salts correct absolute iron deficiency in most patients, because low hepcidin levels facilitate iron absorption. Unfortunately frequent side effects limit oral iron efficacy. Intravenous iron is increasingly utilized, because currently available preparations allow rapid normalization of total body iron even with a single infusion and are effective also in functional iron deficiency and in iron deficiency associated with inflammatory disorders. The evidence is accumulating that these preparations are safe and effective. However, long-term safety issues of high doses of iron need to be further explored.

  10. Electronic properties and magnetism of iron at the Earth's inner core conditions

    NASA Astrophysics Data System (ADS)

    Pourovskii, L. V.; Miyake, T.; Simak, S. I.; Ruban, A. V.; Dubrovinsky, L.; Abrikosov, I. A.

    2013-03-01

    We employ state-of-the-art ab initio simulations within the dynamical mean-field theory to study three likely phases of iron (hcp, fcc, and bcc) at the Earth's core conditions. We demonstrate that the correction to the electronic free energy due to correlations can be significant for the relative stability of the phases. The strongest effect is observed in bcc Fe, which shows a non-Fermi-liquid behavior, and where a Curie-Weiss behavior of the uniform susceptibility hints at a local magnetic moment still existing at 5800 K and 300 GPa. We predict that all three structures have sufficiently high magnetic susceptibility to stabilize the geodynamo.

  11. Erosive Wear Behavior of High-Alloy Cast Iron and Duplex Stainless Steel under Mining Conditions

    NASA Astrophysics Data System (ADS)

    Yoganandh, J.; Natarajan, S.; Kumaresh Babu, S. P.

    2015-09-01

    Centrifugal pumps used in the lignite mines encounter erosive wear problems, leading to a disastrous failure of the pump casings. This paper attempts to evaluate the erosive wear resistance of Ni-Hard 4, high-chromium iron, and Cast CD4MCu duplex stainless steel (DSS), for mining conditions. The prepared test coupons were subjected to an erosion test by varying the impingement velocity and the angle of impingement, under two different pH conditions of 3 and 7, which pertained to the mining conditions. XRD analysis was carried out to confirm the phases present in the alloy. The eroded surface was subjected to SEM analysis to identify the erosion mechanisms. The surface degradation of Ni-Hard 4 and high-chromium iron came from a low-angle abrasion with a grooving and plowing mechanism at a low angle of impingement. At normal impingement, deep indentations resulted in lips and crater formations, leading to degradation of the surface in a brittle manner. A combined extrusion-forging mechanism is observed in the CD4MCu DSS surface at all the impingement angles.

  12. Velocity measurements of the liquid - gas flow using gamma absorption and modified conditional averaging

    NASA Astrophysics Data System (ADS)

    Hanus, Robert; Zych, Marcin; Kowalczyk, Adam; Petryka, Leszek

    2015-05-01

    The paper presents idea and an exemplary application of gamma-absorption in the measurement of gas bubbles transportation in a gas-liquid mixture flow through a horizontal pipeline. In the tests on laboratory installation two 241Am radioactive sources and probes with NaI(Tl) scintillation crystals have been used. For analysis of electrical signals obtained from detectors the modified conditional averaging of the absolute value of delayed signal (CAAV) is proposed. The proposed method is based on the quotient of classical cross-correlation (CCF) and CAAV. Results of the time delay estimation and gas-phase velocity measurements are compared with one obtained using CCF. The combined uncertainties of the mean velocity of air bubbles evaluation in the presented experiment did not exceed 2.1% (CCF) and 1.7% (CCF/CAAV), which is a satisfactory result in industrial applications.

  13. Ionic liquid-based extraction followed by graphite-furnace atomic absorption spectrometry for the determination of trace heavy metals in high-purity iron metal.

    PubMed

    Matsumiya, Hiroaki; Kato, Tatsuya; Hiraide, Masataka

    2014-02-01

    The analysis of high-purity materials for trace impurities is an important and challenging task. The present paper describes a facile and sensitive method for the determination of trace heavy metals in high-purity iron metal. Trace heavy metals in an iron sample solution were rapidly and selectively preconcentrated by the extraction into a tiny volume of an ionic liquid [1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide] for the determination by graphite-furnace atomic absorption spectrometry (GFAAS). A nitrogen-donating neutral ligand, 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ), was found to be effective in the ionic liquid-based selective extraction, allowing the nearly complete (~99.8%) elimination of the iron matrix. The combination with the optimized GFAAS was successful. The detectability reached sub-μg g(-1) levels in iron metal. The novel use of TPTZ in ionic liquid-based extraction followed by GFAAS was successfully applied to the determination of traces of Co, Ni, Cu, Cd, and Pb in certified reference materials for high-purity iron metal.

  14. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1992-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. For example, laboratory measurements performed by Fahd and Steffes have shown that the opacity from gaseous SO2 under simulated Venus conditions can be well described by the Van Vleck-Weisskopf lineshape at wavelengths shortward of 2 cm, but that the opacity of wavelengths greater than 2 cm is best described by a different lineshape that was previously used in theoretical predictions. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  15. Effect of bionic coupling units' forms on wear resistance of gray cast iron under dry linear reciprocating sliding condition

    NASA Astrophysics Data System (ADS)

    Pang, Zuobo; Zhou, Hong; Xie, Guofeng; Cong, Dalong; Meng, Chao; Ren, Luquan

    2015-07-01

    In order to get close to the wear form of guide rails, the homemade linear reciprocating wear testing machine was used for the wear test. In order to improve the wear-resistance of gray cast iron guide rail, bionic coupling units of different forms were manufactured by a laser. Wear behavior of gray-cast-iron with bionic-coupling units has been studied under dry sliding condition at room temperature using the wear testing machine. The wear resistance was evaluated by means of weight loss measurement and wear morphology. The results indicated that bionic coupling unit could improve the wear resistance of gray cast iron. The wear resistance of gray cast iron with reticulation bionic coupling unit is the best. When the load and speed changed, reticulation bionic coupling unit still has excellent performance in improving the wear resistance of gray cast iron.

  16. Different physiological responses of cyanobacteria to ultraviolet-B radiation under iron-replete and iron-deficient conditions: Implications for underestimating the negative effects of UV-B radiation.

    PubMed

    Li, Zheng-Ke; Dai, Guo-Zheng; Juneau, Philippe; Qiu, Bao-Sheng

    2017-02-06

    Iron deficiency has been considered one of the main limiting factors of phytoplankton productivity in some aquatic systems including oceans and lakes. Concomitantly, solar ultraviolet-B radiation has been shown to have both deleterious and positive impacts on phytoplankton productivity. However, how iron-deficient cyanobacteria respond to UV-B radiation has been largely overlooked in aquatic systems. In this study, physiological responses of four cyanobacterial strains (Microcystis and Synechococcus), which are widely distributed in freshwater or marine systems, were investigated under different UV-B irradiances and iron conditions. The growth, photosynthetic pigment composition, photosynthetic activity, and nonphotochemical quenching of the different cyanobacterial strains were drastically altered by enhanced UV-B radiation under iron-deficient conditions, but were less affected under iron-replete conditions. Intracellular reactive oxygen species (ROS) and iron content increased and decreased, respectively, with increased UV-B radiation under iron-deficient conditions for both Microcystis aeruginosa FACHB 912 and Synechococcus sp. WH8102. On the contrary, intracellular ROS and iron content of these two strains remained constant and increased, respectively, with increased UV-B radiation under iron-replete conditions. These results indicate that iron-deficient cyanobacteria are more susceptible to enhanced UV-B radiation. Therefore, UV-B radiation probably plays an important role in influencing primary productivity in iron-deficient aquatic systems, suggesting that its effects on the phytoplankton productivity may be underestimated in iron-deficient regions around the world.

  17. The effect of administration of copper nanoparticles to chickens in drinking water on estimated intestinal absorption of iron, zinc, and calcium.

    PubMed

    Ognik, Katarzyna; Stępniowska, Anna; Cholewińska, Ewelina; Kozłowski, Krzysztof

    2016-09-01

    Copper nanoparticles used as a dietary supplement for poultry could affect the absorption of mineral elements. Hence the aim of the study was to determine the effect of administration of copper nanoparticles to chickens in drinking water on intestinal absorption of iron, zinc, and calcium. The experiment was carried out on 126 chicks assigned to seven experimental groups of 18 birds each (3 replications of 6 individuals each). The control group (G-C) did not receive copper nanoparticles. Groups: Cu-5(7), Cu-10(7), and Cu-15(7) received gold nanoparticles in their drinking water in the amounts of 5 mg/L for group Cu-5(7), 10 mg/L for group Cu-10(7), and 15 mg/L for group Cu-15(7) during 8 to 14, 22 to 28, and 36 of 42 days of the life of the chicks. The birds in groups Cu-5(3), Cu-10(3), and Cu-15(3) received copper nanoparticles in the same amounts, but only during 8 to 10, 22 to 24, and 36 to 38 days of life. Blood for analysis was collected from the wing vein of all chicks at the age of 42 days. After the rearing period (day 42), six birds from each experimental group with body weight similar to the group average were slaughtered. The carcasses were dissected and samples of the jejunum were collected for analysis of absorption of selected minerals. Mineral absorption was tested using the in vitro gastrointestinal sac technique. Oral administration of copper nanoparticles to chickens in the amount of 5, 10, and 15 mg/L led to accumulation of this element in the intestinal walls. The highest level of copper nanoparticles applied increased Cu content in the blood plasma of the birds. The in vitro study suggests that copper accumulated in the intestines reduces absorption of calcium and zinc, but does not affect iron absorption.

  18. Effects of surface condition on aqueous corrosion and environmental embrittlement of iron aluminides

    SciTech Connect

    Perrin, R.L.; Buchanan, R.A.

    1996-08-01

    Effects of retained high-temperature surface oxides, produced during thermomechanical processing and/or heat treatment, on the aqueous-corrosion and environmental-embrittlement characteristics of Fe{sub 3}Al-based iron aluminides (FA-84, FA-129 and FAL-Mo), a FeAl-based iron aluminide (FA-385), and a disordered low-aluminum Fe-Al alloy (FAPY) were evaluated. All tests were conducted at room temperature in a mild acid-chloride solution. In cyclic-anodic-polarization testing for aqueous-corrosion behavior, the surface conditions examined were: as-received (i.e., with the retained high-temperature oxides), mechanically cleaned and chemically cleaned. For all materials, the polarization tests showed the critical pitting potentials to be significantly lower in the as-received condition than in the mechanically-cleaned and chemically-cleaned conditions. These results indicate detrimental effects of the retained high-temperature oxides in terms of increased susceptibilities to localized corrosion. In 200-hour U-bend stress-corrosion-cracking tests for environmental-embrittlement behavior, conducted at open-circuit corrosion potentials and at a hydrogen-charging potential of {minus}1500 mV (SHE), the above materials (except FA-385) were examined with retained oxides and with mechanically cleaned surfaces. At the open-circuit corrosion potentials, none of the materials in either surface condition underwent cracking. At the hydrogen-charging potential, none of the materials with retained oxides underwent cracking, but FA-84, FA-129 and FAL-Mo in the mechanically cleaned condition did undergo cracking. These results suggest beneficial effects of the retained high-temperature oxides in terms of increased resistance to environmental hydrogen embrittlement.

  19. Effect of growth conditions on microbial activity and iron-sulfide production by Desulfovibrio vulgaris.

    PubMed

    Zhou, Chen; Vannela, Raveender; Hayes, Kim F; Rittmann, Bruce E

    2014-05-15

    Sulfate-reducing bacteria (SRB) can produce iron sulfide (FeS) solids with mineralogical characteristics that may be beneficial for a variety of biogeochemical applications, such as long-term immobilization of uranium. In this study, the growth and metabolism of Desulfovibrio vulgaris, one of the best-studied SRB species, were comprehensively monitored in batch studies, and the biogenic FeS solids were characterized by X-ray diffraction. Controlling the pH by varying the initial pH, the iron-to-sulfate ratio, or the electron donor - affected the growth of D. vulgaris and strongly influenced the formation and growth of FeS solids. In particular, lower pH (from initial conditions or a decrease caused by less sulfate reduction, FeS precipitation, or using pyruvate as the electron donor) produced larger-sized mackinawite (Fe1+xS). Greater accumulation of free sulfide, from more sulfate reduction by D. vulgaris, also led to larger-sized mackinawite and particularly stimulated mackinawite transformation to greigite (Fe3S4) when the free sulfide concentration was 29.3mM. Furthermore, sufficient free Fe(2+) led to the additional formation of vivianite [Fe3(PO4)2·8(H2O)]. Thus, microbially relevant conditions (initial pH, choice of electron donor, and excess or deficiency of sulfide) are tools to generate biogenic FeS solids of different characteristics.

  20. Ineffective erythropoiesis and regulation of iron status in iron loading anaemias.

    PubMed

    Camaschella, Clara; Nai, Antonella

    2016-02-01

    The definition 'iron loading anaemias' encompasses a group of inherited and acquired anaemias characterized by ineffective erythropoiesis, low hepcidin levels, excessive iron absorption and secondary iron overload. Non-transfusion-dependent β-thalassaemia is the paradigmatic example of these conditions that include dyserythropoietic and sideroblastic anaemias and some forms of myelodysplasia. Interrupting the vicious cycle between ineffective erythropoiesis and iron overload may be of therapeutic benefit in all these diseases. Induction of iron restriction by means of transferrin infusions, minihepcidins or manipulation of the hepcidin pathway prevents iron overload, redistributes iron from parenchymal cells to macrophage stores and partially controls anaemia in β-thalassaemic mice. Inhibition of ineffective erythropoiesis by activin ligand traps improves anaemia and iron overload in the same models. Targeting iron loading or ineffective erythropoiesis shows promise in preclinical studies; activin ligand traps are in clinical trials with promising results and may be useful in patients with ineffective erythropoiesis.

  1. Column chromatographic pre-concentration of iron(III) in alloys and biological samples with 1-nitroso-2-naphthol-3,6-disulphonate and benzyldimethyltetradecylammonium-perchlorate adsorbent supported on naphthalene using atomic absorption spectrometry.

    PubMed

    Miura, J; Arima, S; Satake, M

    1990-09-01

    The solid ion-pair material produced from the reaction between benzyldimethyltetradecylammonium chloride (BDTA) and sodium perchlorate on naphthalene provides the basis for a simple, rapid and selective technique for pre-concentrating iron from up to 500 ml of aqueous solution. Iron reacts with disodium 1-nitroso-2-naphthol-3,6-disulphonate (Nitroso-R salt) to form a water-soluble coloured chelate anion. The iron chelate anion forms a water-insoluble, stable iron-Nitroso-R-BDTA complex on naphthalene packed in a column. Trace amounts of iron are quantitatively retained on naphthalene in the pH range 3.5-7.5 and at a flow-rate of 1-2 ml min-1. The solid mass is dissolved out from the column with 5 ml of N,N-dimethylformamide and iron is determined by means of an atomic absorption spectrometer at 248 nm. The calibration graph is linear for concentrations of iron over the range of 0.5-20 micrograms in 5 ml of final solution. The standard deviation and relative standard deviation were calculated. The detection limit of the method was 0.0196 micrograms ml-1 of iron. The sensitivity for 1% absorption was 0.072 microgram ml-1 (0.165 microgram ml-1 by direct atomic absorption spectrometry of aqueous solution). The proposed method was applied to the determination of iron in standard alloys and biological samples.

  2. Microbial Anaerobic Ammonium Oxidation Under Iron Reducing Conditions, Alternative Electron Acceptors

    NASA Astrophysics Data System (ADS)

    Ruiz-Urigüen, M.; Jaffe, P. R.

    2015-12-01

    Autotrophic Acidimicrobiaceae-bacterium named A6 (A6), part of the Actinobacteria phylum have been linked to anaerobic ammonium (NH4+) oxidation under iron reducing conditions. These organisms obtain their energy by oxidizing NH4+ and transferring the electrons to a terminal electron acceptor (TEA). Under environmental conditions, the TEAs are iron oxides [Fe(III)], which are reduced to Fe(II), this process is known as Feammox. Our studies indicate that alternative forms of TEAs can be used by A6, e.g. iron rich clays (i.e. nontronite) and electrodes in bioelectrochemical systems such as Microbial Electrolysis Cells (MECs), which can sustain NH4+removal and A6 biomass production. Our results show that nontronite can support Feammox and promote bacterial cell production. A6 biomass increased from 4.7 x 104 to 3.9 x 105 cells/ml in 10 days. Incubations of A6 in nontronite resulted in up to 10 times more NH4+ removal and 3 times more biomass production than when ferrihydrite is used as the Fe(III) source. Additionally, Fe in nontronite can be reoxidized by aeration and A6 can reutilize it; however, Fe is still finite in the clay. In contrast, in MECs, A6 harvest electrons from NH4+ and use an anode as an unlimited TEA, as a result current is produced. We operated multiple MECs in parallel using a single external power source, as described by Call & Logan (2011). MECs were run with an applied voltage of 0.7V and different growing mediums always containing initial 5mM NH4+. Results show that current production is favored when anthraquinone-2,6-disulfonate (AQDS), an electron shuttled, is present in the medium as it facilitates the transfer of electrons from the bacterial cell to the anode. Additionally, A6 biomass increased from 1 x 104 to 9.77 x 105cells/ml in 14 days of operation. Due to Acidimicrobiaceae-bacterium A6's ability to use various TEAs, MECs represent an alternative, iron-free form, for optimized biomass production of A6 and its application in NH4

  3. A Nanoparticulate Ferritin-Core Mimetic Is Well Taken Up by HuTu 80 Duodenal Cells and Its Absorption in Mice Is Regulated by Body Iron12

    PubMed Central

    Latunde-Dada, Gladys O; Pereira, Dora IA; Tempest, Bethan; Ilyas, Hibah; Flynn, Angela C; Aslam, Mohamad F; Simpson, Robert J; Powell, Jonathan J

    2014-01-01

    Background: Iron (Fe) deficiency anemia remains the largest nutritional deficiency disorder worldwide. How the gut acquires iron from nano Fe(III), especially at the apical surface, is incompletely understood. Objective: We developed a novel Fe supplement consisting of nanoparticulate tartrate-modified Fe(III) poly oxo-hydroxide [here termed nano Fe(III)], which mimics the Fe oxide core of ferritin and effectively treats iron deficiency anemia in rats. Methods: We determined transfer to the systemic circulation of nano Fe(III) in iron-deficient and iron-sufficient outbread Swiss mouse strain (CD1) mice with use of 59Fe-labeled material. Iron deficiency was induced before starting the Fe-supplementation period through reduction of Fe concentrations in the rodent diet. A control group of iron-sufficient mice were fed a diet with adequate Fe concentrations throughout the study. Furthermore, we conducted a hemoglobin repletion study in which iron-deficient CD1 mice were fed for 7 d a diet supplemented with ferrous sulfate (FeSO4) or nano Fe(III). Finally, we further probed the mechanism of cellular acquisition of nano Fe(III) by assessing ferritin formation, as a measure of Fe uptake and utilization, in HuTu 80 duodenal cancer cells with targeted inhibition of divalent metal transporter 1 (DMT1) and duodenal cytochrome b (DCYTB) before exposure to the supplemented iron sources. Differences in gene expression were assessed by quantitative polymerase chain reaction. Results: Absorption (means ± SEMs) of nano Fe(III) was significantly increased in iron-deficient mice (58 ± 19%) compared to iron-sufficient mice (18 ± 17%) (P = 0.0001). Supplementation of the diet with nano Fe(III) or FeSO4 significantly increased hemoglobin concentrations in iron-deficient mice (170 ± 20 g/L, P = 0.01 and 180 ± 20 g/L, P = 0.002, respectively). Hepatic hepcidin mRNA expression reflected the nonheme-iron concentrations of the liver and was also comparable for both nano Fe(III)– and

  4. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1991-01-01

    Laboratory measurements of microwave and millimeter wave properties of the simulated atmosphere of the outer planets and their satellites has continued. One of the focuses is on the development of a radiative transfer model of the Jovian atmosphere at wavelengths from 1 mm to 10 cm. This modeling effort led to laboratory measurements of the millimeter wave opacity of hydrogen sulfide (H2S) under simulated Jovian conditions. Descriptions of the modeling effort, the Laboratory experiment, and the observations are presented. Correlative studies of measurements with Pioneer-Venus radio occultation measurements with longer wavelength emission measurements have provided new ways for characterizing temporal and spatial variations in the abundance of both gases H2SO4 and SO2, and for modeling their roles in the subcloud atmosphere. Laboratory measurements were conducted on 1.35 cm (and 13 cm) opacity of gaseous SO2 and absorptivity of gaseous SO2 at the 3.2 mm wavelength under simulated Venus conditions. Laboratory measurements were completed on millimeter wave dielectric properties of liquid H2SO4, in order to model the effects of the opacity of the clouds of Venus onto millimeter wave emission spectrum.

  5. Significance of ambient conditions in uranium absorption and emission features of laser ablation plasmas

    SciTech Connect

    Skrodzki, P. J.; Shah, N. P.; Taylor, N.; Hartig, K. C.; LaHaye, N. L.; Brumfield, B. E.; Jovanovic, I.; Phillips, M. C.; Harilal, S. S.

    2016-11-01

    This study employs laser ablation (LA) to investigate mechanisms for U optical signal variation under various environmental conditions during laser absorption spectroscopy (LAS) and optical emission spectroscopy (OES). Potential explored mechanisms for signal quenching related to ambient conditions include plasma chemistry (e.g., uranium oxide formation), ambient gas confinement effects, and other collisional interactions between plasma constituents and the ambient gas. LA-LAS studies show that the persistence of the U ground state population is significantly reduced in the presence of air ambient compared to nitrogen. LA-OES results yield congested spectra from which the U I 356.18 nm transition is prominent and serves as the basis for signal tracking. LA-OES signal and persistence vary negligibly between the test gases (air and N2), unlike the LA-LAS results. The plume hydrodynamic features and plume fundamental properties showed similar results in both air and nitrogen ambient. Investigation of U oxide formation in the laser-produced plasma suggests that low U concentration in a sample hinders consistent detection of UO molecular spectra.

  6. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1988-01-01

    In the first half of this grant year, laboratory measurements were conducted on the millimeter-wave properties of atmospheric gases under simulated conditions for the outer planet. Significant improvements in the current system have made it possible to accurately characterize the opacity from gaseous NH3 at longer millimeter wavelengths (7 to 10 mm) under simulated Jovian conditions. In the second half of the grant year, it is hoped to extend such measurements to even shorter millimeter-wavelengths. Further analysis and application of the laboratory results to microwave and millimeter-wave absorption data for the outer planets, such as results from Voyager Radio Occultation experiments and earth-based radio astronomical observations will be continued. The analysis of available multispectral microwave opacity data from Venus, including data from the most recent radio astronomical ovservations in the 1.3 to 3.6 cm wavelength range and newly obtained Pioneer-Venus Radio Occulatation measurements at 13 cm, using the laboratory measurements as an interpretative tool will be pursued.

  7. Significance of ambient conditions in uranium absorption and emission features of laser ablation plasmas

    NASA Astrophysics Data System (ADS)

    Skrodzki, P. J.; Shah, N. P.; Taylor, N.; Hartig, K. C.; LaHaye, N. L.; Brumfield, B. E.; Jovanovic, I.; Phillips, M. C.; Harilal, S. S.

    2016-11-01

    This study employs laser ablation (LA) to investigate mechanisms for U optical signal variation under various environmental conditions during laser absorption spectroscopy (LAS) and optical emission spectroscopy (OES). Potential mechanisms explored for signal quenching related to ambient conditions include plasma chemistry (e.g., uranium oxide formation), ambient gas confinement effects, and other collisional interactions between plasma constituents and the ambient gas. LA-LAS studies show that the persistence of the U ground state population is significantly reduced in the presence of air ambient compared to nitrogen. LA-OES yields congested spectra from which the U I 356.18 nm transition is prominent and serves as the basis for signal tracking. LA-OES signal and persistence vary negligibly between the test gases (air and N2), unlike the LA-LAS results. The plume hydrodynamic features and plume fundamental properties showed similar results in both air and nitrogen ambient. Investigation of U oxide formation in the laser-produced plasma suggests that low U concentration in a sample hinders consistent detection of UO molecular spectra.

  8. Structural characterization of poorly-crystalline scorodite, iron(III)-arsenate co-precipitates and uranium mill neutralized raffinate solids using X-ray absorption fine structure spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, N.; Jiang, D. T.; Cutler, J.; Kotzer, T.; Jia, Y. F.; Demopoulos, G. P.; Rowson, J. W.

    2009-06-01

    X-ray absorption fine structure (XAFS) is used to characterize the mineralogy of the iron(III)-arsenate(V) precipitates produced during the raffinate (aqueous effluent) neutralization process at the McClean Lake uranium mill in northern Saskatchewan, Canada. To facilitate the structural characterization of the precipitated solids derived from the neutralized raffinate, a set of reference compounds were synthesized and analyzed. The reference compounds include crystalline scorodite, poorly-crystalline scorodite, iron(III)-arsenate co-precipitates obtained under different pH conditions, and arsenate-adsorbed on goethite. The poorly-crystalline scorodite (prepared at pH 4 with Fe/As = 1) has similar As local structure as that of crystalline scorodite. Both As and Fe K-edge XAFS of poorly-crystalline scorodite yield consistent results on As-Fe (or Fe-As) shell. From As K-edge analysis the As-Fe shell has an inter-atomic distance of 3.33 ± 0.02 Å and coordination number of 3.2; while from Fe K-edge analysis the Fe-As distance and coordination number are 3.31 ± 0.02 Å and 3.8, respectively. These are in contrast with the typical arsenate adsorption on bidentate binuclear sites on goethite surfaces, where the As-Fe distance is 3.26 ± 0.03 Å and coordination number is close to 2. A similar local structure identified in the poorly-crystalline scorodite is also found in co-precipitation solids (Fe(III)/As(V) = 3) when precipitated at the same pH (pH = 4): As-Fe distance 3.30 ± 0.03 Å and coordination number 3.9; while at pH = 8 the co-precipitate has As-Fe distance of 3.27 ± 0.03 Å and coordination number about 2, resembling more closely the adsorption case. The As local structure in the two neutralized raffinate solid series (precipitated at pH values up to 7) closely resembles that in the poorly-crystalline scorodite. All of the raffinate solids have the same As-Fe inter-atomic distance as that in the poorly-crystalline scorodite, and a systematic decrease in the

  9. METABOLISM OF IRON STORES

    PubMed Central

    SAITO, HIROSHI

    2014-01-01

    ABSTRACT Remarkable progress was recently achieved in the studies on molecular regulators of iron metabolism. Among the main regulators, storage iron, iron absorption, erythropoiesis and hepcidin interact in keeping iron homeostasis. Diseases with gene-mutations resulting in iron overload, iron deficiency, and local iron deposition have been introduced in relation to the regulators of storage iron metabolism. On the other hand, the research on storage iron metabolism has not advanced since the pioneering research by Shoden in 1953. However, we recently developed a new method for determining ferritin iron and hemosiderin iron by computer-assisted serum ferritin kinetics. Serum ferritin increase or decrease curves were measured in patients with normal storage iron levels (chronic hepatitis C and iron deficiency anemia treated by intravenous iron injection), and iron overload (hereditary hemochromatosis and transfusion dependent anemia). We thereby confirmed the existence of two iron pathways where iron flows followed the numbered order (1) labile iron, (2) ferritin and (3) hemosiderin in iron deposition and mobilization among many previously proposed but mostly unproven routes. We also demonstrated the increasing and decreasing phases of ferritin iron and hemosiderin iron in iron deposition and mobilization. The author first demonstrated here the change in proportion between pre-existing ferritin iron and new ferritin iron synthesized by removing iron from hemosiderin in the course of iron removal. In addition, the author disclosed the cause of underestimation of storage iron turnover rate which had been reported by previous investigators in estimating storage iron turnover rate of normal subjects. PMID:25741033

  10. Impaired growth under iron-limiting conditions associated with the acquisition of colistin resistance in Acinetobacter baumannii.

    PubMed

    López-Rojas, Rafael; García-Quintanilla, Meritxell; Labrador-Herrera, Gema; Pachón, Jerónimo; McConnell, Michael J

    2016-06-01

    Acquisition of colistin resistance in Acinetobacter baumannii has been associated with reduced bacterial fitness and virulence, although the mechanisms underlying this fitness loss have not been well characterised. In this study, the role played by environmental iron levels on the growth and survival of colistin-resistant strains of A. baumannii was assessed. Growth assays with the colistin-susceptible ATCC 19606 strain and its colistin-resistant derivative RC64 [colistin minimum inhibitory concentration (MIC) of 64 mg/L] demonstrated that the strains grew similarly in rich laboratory medium (Mueller-Hinton broth), whereas RC64 demonstrated impaired growth compared with ATCC 19606 in human serum (>100-fold at 24 h). Compared with RC64, ATCC 19606 grew in the presence of higher concentrations of the iron-specific chelator 2,2'-bipyridine and grew more readily under iron-limiting conditions in solid and liquid media. In addition, iron supplementation of human serum increased the growth of RC64 compared with unsupplemented human serum to a greater extent than ATCC 19606. The ability of 11 colistin-resistant clinical isolates with mutations in the pmrB gene to grow in iron-replete and iron-limiting conditions was assessed, demonstrating that eight of the strains showed reduced growth under iron limitation. Individual mutations in the pmrB gene did not directly correlate with a decreased capacity for growth under iron limitation, suggesting that mutations in pmrB may not directly produce this phenotype. Together these results indicate that acquisition of colistin resistance in A. baumannii can be associated with a decreased ability to grow in low-iron environments.

  11. The capacity of Porphyromonas gingivalis to multiply under iron-limiting conditions correlates with its pathogenicity in an animal model.

    PubMed

    Grenier, D; Goulet, V; Mayrand, D

    2001-07-01

    Isolates of Porphyromonas gingivalis have various abilities to induce infections in an animal model. The hypothesis of this study was that pathogenic strains of P. gingivalis could multiply under iron-limiting conditions, while non-pathogenic strains could not. Three pathogenic strains (W50, W83, and ATCC 49417) grew to a final optical density (660 nm) > 2 in horse serum, while the growth of the 3 non-pathogenic strains (ATCC 33277, LB13D-2, and HW24D-1) was negligible. When an excess of hemin or ferric chloride was added to the serum, significant growth of the non-pathogenic strains occurred. Under iron-limiting conditions, the pathogenic strains of P. gingivalis had a much lower requirement for human iron-loaded transferrin and hemin than the non-pathogenic strains. Proteolytic degradation of transferrin, which may be associated with the release of iron, was not markedly different for pathogenic and non-pathogenic strains. In addition, no relationship could be established between the level of 55Fe uptake from 55Fe-transferrin and the pathogenicity of strains. Our study provided evidence that the ability of P. gingivalis to multiply in vitro under iron-limiting conditions may be correlated with its ability to induce infections in an animal model. Isolates of P. gingivalis possessing a low requirement for iron are likely to have a higher potential for initiating periodontal infections.

  12. Iron overload in thalassemia and related conditions: therapeutic goals and assessment of response to chelation therapies.

    PubMed

    Porter, John B; Shah, Farrukh T

    2010-12-01

    Transfusional iron loading inevitably results in hepatic iron accumulation, with variable extrahepatic distribution that is typically less pronounced in sickle cell disease than in thalassemia disorders. Iron chelation therapy has the goal of preventing iron-mediated tissue damage through controlling tissue iron levels, without incurring chelator-mediated toxicity. Historically, target levels for tissue iron control have been limited by the increased frequency of deferoxamine-mediated toxicity and low levels of iron loading. With newer chelation regimes, these limitations are less evident. The reporting of responses to chelation therapies has typically focused on average changes in serum ferritin in patient populations. This approach has three limitations. First, changes in serum ferritin may not reflect trends in iron balance equally in all patients or for all chelation regimens. Second, this provides no information about the proportion of patients likely respond. Third, this gives insufficient information about iron trends in tissues such as the heart. Monitoring of iron overload has advanced with the increasing use of MRI techniques to estimate iron balance (changes in liver iron concentration) and extrahepatic iron distribution (myocardial T2*). The term nonresponder has been increasingly used to describe individuals who fail to show a downward trend in one or more of these variables. Lack of a response of an individual may result from inadequate dosing, high transfusion requirement, poor treatment adherence, or unfavorable pharmacology of the chelation regime. This article scrutinizes evidence for response rates to deferoxamine, deferiprone (and combinations), and deferasirox.

  13. Introducing a new histologic scoring system for iron deposition in liver of thalassemic patients, compared with atomic absorption spectrometry.

    PubMed

    Tavassoli, Habib; Mahjoub, Fatemeh; Jahanzad, Eesa; Farahmand, Fatemeh; Izadyar, Mina; Sani, Mehri Najafi; Rashti, Mohammad Lamei; Aramli, Mohammad Sadegh

    2015-01-01

    Iron deposition in liver is a major finding in thalassemic patients and because of direct iron toxicity to liver it is associated with several consequences for example liver fibrosis. Liver biopsies from 63 patients were evaluated, 40 (63.5%) were male and 20 (36.5%) were female. The mean age of the patients was 8.01 ± 3.7 and the age range was from 1.8 to 15 years. Histologic grading and staging was performed for each case according to modified HAI (Hepatitis Activity Index) system. Iron scoring was performed according to Sindram & Marx and MTK1-3 scoring systems. The mean (SD) dry weight (dw) of liver specimens was 1.34 (0.11) mg (range 0.20 to 3.80 mg). The mean (SD) of hepatic iron concentration was 230.9 (121.2)μmol/g dry weight. The relationship between the variables HIC, HII (hepatic iron index) and all histological gradings of iron (S&M and MTK1-3) was very strong. The relationship between the HIC and staging by HAI method was good. Significant differences were identified between the mean HIC in scores 1&2 of all histological iron scorings (S&M and MTK1-3), but no significant differences identified between mean HIC in other adjacent scores in all histological iron scorings (S&M and MTK1, 2 and 3). New scoring system introduced by us in this study which considered size and density of iron granules as well as zone of iron deposition was very much the same as simple Sindram and Marx classification.

  14. Effect of surface condition on the aqueous corrosion behavior of iron aluminies

    SciTech Connect

    Buchanan, R.A.; Perrin, R.L.

    1995-08-01

    The effects of retained high-temperature surface oxides, produced during thermomechanical processing and/or heat treatment, on the aqueous-corrosion characteristics of Fe-Al-based alloys were evaluated by electrochemical methods. Cyclic anodic polarization evaluations were conducted at room temperature in a mild acid-chloride solution (pH = 4,200 ppm Cl{sup {minus}}) on the Fe{sub 3}Al-based iron aluminides, FA-84 (Fe-28Al-2Cr-0.05B, at %), FA-129 (Fe-28Al-5Cr-0.5Nb-0.2C, at %), and FAL-Mo (Fe-28Al-5Cr-1Mo-0.04B-0.08Zr, at %), on the FeAl-based iron aluminide, FA-385 (Fe-35.65Al-0.20Mo-0.05Zr-0.11C, at %). The surface conditions evaluated were: As received (i.e. with the retained high-temperature oxides), mechanically cleaned (ground through 600-grit SiC paper), and chemically cleaned (10% HNO{sub 3}, 2%HF, at 43 {degree}C). The principal electrochemical parameter of interest was the critical putting potential with lower values indicating less resistance to chloride-induced localized corrosion. For all materials evaluated, the critical pitting potential was found to be significantly lower in the as-received condition than in the mechanically-cleaned and chemically-cleaned conditions. Mechanisms responsible for the detrimental high-temperature-oxide effect are under study.

  15. Evaluating the bonding condition of NASA spray on foam insulation (SOFI) using audio frequency sound absorption measurements

    NASA Astrophysics Data System (ADS)

    Thompson, Todd A.; Mann, J. Adin

    2005-09-01

    The bonding condition of the spray on foam insulation (SOFI) used to insulate the external tank of the NASA space shuttle can be found by using the audio frequency sound absorption coefficient. The ASTM E1050 standard method for sound absorption measurements was used with an open-ended 1-in-diam cast acrylic impedance tube sealed to the SOFI with closed cell PVC foam. Two artificially disbonded locations, measuring 1.0 in. by 5.5 in. by 0.0625 in. and 2.0 in. by 8.0 in. by 0.0625 in., were detected by peaks in the sound absorption coefficient spectrum. The peaks in the sound absorption spectrum between 1000 and 4000 Hz were 25% to 50% higher over disbonded areas when compared to bonded locations. The maximum and minimum sound absorption levels for the foam ranged between approximately 0.1 and 0.3. The entire sample was scanned using the sound absorption peaks as indicators. Samples of 2-in.-thick polystyrene foam were used with different sized defects at different locations in the foam to relate defect size and location to peaks in absorption coeffi-cient spectrum. [Work supported by NASA under Award No. NAG102098.

  16. Widespread iron-rich conditions in the mid-Proterozoic ocean.

    PubMed

    Planavsky, Noah J; McGoldrick, Peter; Scott, Clinton T; Li, Chao; Reinhard, Christopher T; Kelly, Amy E; Chu, Xuelei; Bekker, Andrey; Love, Gordon D; Lyons, Timothy W

    2011-09-07

    The chemical composition of the ocean changed markedly with the oxidation of the Earth's surface, and this process has profoundly influenced the evolutionary and ecological history of life. The early Earth was characterized by a reducing ocean-atmosphere system, whereas the Phanerozoic eon (less than 542 million years ago) is known for a stable and oxygenated biosphere conducive to the radiation of animals. The redox characteristics of surface environments during Earth's middle age (1.8-1 billion years ago) are less well known, but it is generally assumed that the mid-Proterozoic was home to a globally sulphidic (euxinic) deep ocean. Here we present iron data from a suite of mid-Proterozoic marine mudstones. Contrary to the popular model, our results indicate that ferruginous (anoxic and Fe(2+)-rich) conditions were both spatially and temporally extensive across diverse palaeogeographic settings in the mid-Proterozoic ocean, inviting new models for the temporal distribution of iron formations and the availability of bioessential trace elements during a critical window for eukaryotic evolution.

  17. Reduction of the Temperature Sensitivity of Halomonas hydrothermalis by Iron Starvation Combined with Microaerobic Conditions

    PubMed Central

    Hallsworth, John E.; Cockell, Charles S.

    2015-01-01

    The limits to biological processes on Earth are determined by physicochemical parameters, such as extremes of temperature and low water availability. Research into microbial extremophiles has enhanced our understanding of the biophysical boundaries which define the biosphere. However, there remains a paucity of information on the degree to which rates of microbial multiplication within extreme environments are determined by the availability of specific chemical elements. Here, we show that iron availability and the composition of the gaseous phase (aerobic versus microaerobic) determine the susceptibility of a marine bacterium, Halomonas hydrothermalis, to suboptimal and elevated temperature and salinity by impacting rates of cell division (but not viability). In particular, iron starvation combined with microaerobic conditions (5% [vol/vol] O2, 10% [vol/vol] CO2, reduced pH) reduced sensitivity to temperature across the 13°C range tested. These data demonstrate that nutrient limitation interacts with physicochemical parameters to determine biological permissiveness for extreme environments. The interplay between resource availability and stress tolerance, therefore, may shape the distribution and ecology of microorganisms within Earth's biosphere. PMID:25595757

  18. Iron-mediated microbial oxidation and abiotic reduction of organic contaminants under anoxic conditions.

    PubMed

    Tobler, Nicole B; Hofstetter, Thomas B; Straub, Kristina L; Fontana, Daniela; Schwarzenbach, René P

    2007-11-15

    In anoxic environments, the oxidation of organic compounds, such as BTEX fuel components, by dissimilatory Fe(III) reduction can generate reactive mineral-bound Fe(II) species, which in turn are able to reduce other classes of organic and inorganic groundwater contaminants. In this study, we designed and evaluated an anaerobic batch reactor that mimicks iron-reducing conditions to investigate the factors that favor the coupling of microbial toluene oxidation and abiotic reduction of nitroaromatic contaminants. We investigated the influence of different Fe(III)-bearing minerals and combinations thereof on the coupling of these two processes. Results from laboratory model systems show that complete oxidation of toluene to CO2 by Geobacter metallireducens in the presence of Fe(III)-bearing minerals leads to the formation of mineral-bound Fe(II) species capable of the reduction of 4-nitroacetophenone. Whereas significant microbial toluene oxidation was only observed in the presence of amorphous Fe(III) phases, reduction of nitroaromatic compounds only proceeded with Fe(II) species bound to crystalline Fe(III) oxides. Our results suggest that in anoxic soils and sediments containing amorphous and crystalline iron phases simultaneously, coupling of microbial oxidation and abiotic reduction of organic compounds may allow for concurrent natural attenuation of different contaminant classes.

  19. Direct measurement of thermal conductivity in solid iron at planetary core conditions

    NASA Astrophysics Data System (ADS)

    Konôpková, Zuzana; McWilliams, R. Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F.

    2016-06-01

    The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth’s core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth’s magnetic field via dynamo action. Attempts to describe thermal transport in Earth’s core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth’s core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth’s geodynamo has persisted since the beginning of Earth’s history, and allows for a solid inner core as old as the dynamo.

  20. Synthesis of iron oxide nanorods via chemical scavenging and phase transformations of intermediates at ambient conditions

    NASA Astrophysics Data System (ADS)

    Deshmukh, Ruchi; Mehra, Anurag; Thaokar, Rochish

    2017-01-01

    Chemically induced shape transformations of isotropic seeds, comprised of iron oxyhydroxides and iron oxide borate into nanorods, is reported. Transient growth studies show that the nanorods are formed via phase transformation and aggregation of various metastable species. Addition of tetra- methyl-ammonium hydroxide (TMAH) to the in situ synthesized seeds ensures a typical reaction pathway that favors formation of magnetite (Fe 3 O 4) via the steps of chemical etching, phase transformation of intermediates, and crystal consolidation. Whereas, with addition of sodium hydroxide (NaOH), either magnetite (Fe 3 O 4) or a mixture of ( γ-Fe 2 O 3 + α-FeOOH) is obtained. The shape with both the additives is always that of nanorods. When the seeds treated with TMAH were aged in an ultrasonication bath, rods with almost twice the length and diameter (length = 2800 nm, diameter = 345 nm) are obtained as compared to the sample aged without ultrasonication (length = 1535 nm, diameter = 172 nm). The morphology of nanostructures depending upon other experimental conditions such as, aging the sample at 60 ∘C, seeds synthesized under ultrasonication/ stirring or externally added are also examined and discussed in detail. All the samples show high coercivity and strong ferromagnetic behavior at room temperature and should be promising candidates as ferro-fluids for various applications.

  1. Direct measurement of thermal conductivity in solid iron at planetary core conditions.

    PubMed

    Konôpková, Zuzana; McWilliams, R Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F

    2016-06-02

    The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth's core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth's magnetic field via dynamo action. Attempts to describe thermal transport in Earth's core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth's core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth's geodynamo has persisted since the beginning of Earth's history, and allows for a solid inner core as old as the dynamo.

  2. Dehalogenation and biodegradation of brominated phenols and benzoic acids under iron-reducing, sulfidogenic, and methanogenic conditions.

    PubMed Central

    Monserrate, E; Häggblom, M M

    1997-01-01

    The anaerobic biodegradation of monobrominated phenols and benzoic acids by microorganisms enriched from marine and estuarine sediments was determined in the presence of different electron acceptors [i.e., Fe(III), SO4(2-), or HCO3-]. Under all conditions tested, the bromophenol isomers were utilized without a lengthy lag period whereas the bromobenzoate isomers were utilized only after a lag period of 23 to 64 days. 2-Bromophenol was debrominated to phenol, with the subsequent utilization of phenol under all three reducing conditions. Debromination of 3-bromophenol and 4-bromophenol was also observed under sulfidogenic and methanogenic conditions but not under iron-reducing conditions. In the bromobenzoate-degrading cultures, no intermediates were observed under any of the conditions tested. Debromination rates were higher under methanogenic conditions than under sulfate-reducing or iron-reducing conditions. The stoichiometric reduction of sulfate or Fe(III) and the utilization of bromophenols and phenol indicated that biodegradation was coupled to sulfate or iron reduction, respectively. The production of phenol as a transient intermediate demonstrates that reductive dehalogenation is the initial step in the biodegradation of bromophenols under iron- and sulfate-reducing conditions. PMID:9480645

  3. Iron-induced oxidation of (all-E)-β-carotene under model gastric conditions: kinetics, products, and mechanism.

    PubMed

    Sy, Charlotte; Dangles, Olivier; Borel, Patrick; Caris-Veyrat, Catherine

    2013-10-01

    The stability of (all-E)-β-carotene toward dietary iron was studied in a mildly acidic (pH 4) micellar solution as a simple model of the postprandial gastric conditions. The oxidation was initiated by free iron (Fe(II), Fe(III)) or by heme iron (metmyoglobin, MbFe(III)). Fe(II) and metmyoglobin were much more efficient than Fe(III) at initiating β-carotene oxidation. Whatever the initiator, hydrogen peroxide did not accumulate. Moreover, β-carotene markedly inhibited the conversion of Fe(II) into Fe(III). β-Carotene oxidation induced by Fe(II) or MbFe(III) was maximal with 5-10 eq Fe(II) or 0.05-0.1 eq MbFe(III) and was inhibited at higher iron concentrations, especially with Fe(II). UPLC/DAD/MS and GC/MS analyses revealed a complex distribution of β-carotene-derived products including Z-isomers, epoxides, and cleavage products of various chain lengths. Finally, the mechanism of iron-induced β-carotene oxidation is discussed. Altogether, our results suggest that dietary iron, especially free (loosely bound) Fe(II) and heme iron, may efficiently induce β-carotene autoxidation within the upper digestive tract, thereby limiting its supply to tissues (bioavailability) and consequently its biological activity.

  4. Ingestion of insoluble dietary fibre increased zinc and iron absorption and restored growth rate and zinc absorption suppressed by dietary phytate in rats.

    PubMed

    Hayashi, K; Hara, H; Asvarujanon, P; Aoyama, Y; Luangpituksa, P

    2001-10-01

    We examined the effects of ingestion of five types of insoluble fibre on growth and Zn absorption in rats fed a marginally Zn-deficient diet (6.75 mg (0.103 mmol) Zn/kg diet) with or without added sodium phytate (12.6 mmol/kg diet). The types of insoluble fibre tested were corn husks, watermelon skin, yam-bean root (Pachyrhizus erosus) and pineapple core, and cellulose was used as a control (100 g/kg diet). Body-weight gain in the cellulose groups was suppressed by 57 % by feeding phytate. Body-weight gain in phytate-fed rats was 80 % greater in the watermelon skin fibre and yam-bean root fibre group than that in the cellulose group. Zn absorption ratio in the cellulose groups was lowered by 46 and 70 % in the first (days 7-10) and second (days 16-19) measurement periods with feeding phytate. In the rats fed the phytate-containing diets, Zn absorption ratio in the watermelon skin, yam-bean root and pineapple core fibre groups was 140, 80 and 54 % higher respectively than that in the cellulose group, in the second period. Fe absorption was not suppressed by phytate, however, feeding of these three types of fibre promoted Fe absorption in rats fed phytate-free diets. The concentration of soluble Zn in the caecal contents in the watermelon skin fibre or yam-bean root fibre groups was identical to that in the control group in spite of a higher short-chain fatty acid concentration and lower pH in the caecum. These findings indicate that ingestion of these types of insoluble fibre recovered the growth and Zn absorption suppressed by feeding a high level of phytate, and factors other than caecal fermentation may also be involved in this effect of insoluble fibre.

  5. How do operating conditions affect As(III) removal by iron electrocoagulation?

    PubMed

    Delaire, Caroline; Amrose, Susan; Zhang, Minghui; Hake, James; Gadgil, Ashok

    2017-04-01

    Iron electrocoagulation (Fe-EC) has been shown to effectively remove arsenic from contaminated groundwater at low cost and has the potential to improve access to safe drinking water for millions of people. Understanding how operating conditions, such as the Fe dosage rate and the O2 recharge rate, affect arsenic removal at different pH values is crucial to maximize the performance of Fe-EC under economic constraints. In this work, we improved upon an existing computational model to investigate the combined effects of pH, Fe dosage rate, and O2 recharge rate on arsenic removal in Fe-EC. We showed that the impact of the Fe dosage rate strongly depends on pH and on the O2 recharge rate, which has important practical implications. We identified the process limiting arsenic removal (As(III) oxidation versus As(V) adsorption) at different pH values, which allowed us to interpret the effect of operating conditions on Fe-EC performance. Finally, we assessed the robustness of the trends predicted by the model, which assumes a constant pH, against lab experiments reproducing more realistic conditions where pH is allowed to drift during treatment as a result of equilibration with atmospheric CO2. Our results provide a nuanced understanding of how operating conditions impact arsenic removal by Fe-EC and can inform decisions regarding the operation of this technology in a range of groundwaters.

  6. Abiotic stress growth conditions induce different responses in kernel iron concentration across genotypically distinct maize inbred varieties.

    PubMed

    Kandianis, Catherine B; Michenfelder, Abigail S; Simmons, Susan J; Grusak, Michael A; Stapleton, Ann E

    2013-01-01

    The improvement of grain nutrient profiles for essential minerals and vitamins through breeding strategies is a target important for agricultural regions where nutrient poor crops like maize contribute a large proportion of the daily caloric intake. Kernel iron concentration in maize exhibits a broad range. However, the magnitude of genotype by environment (GxE) effects on this trait reduces the efficacy and predictability of selection programs, particularly when challenged with abiotic stress such as water and nitrogen limitations. Selection has also been limited by an inverse correlation between kernel iron concentration and the yield component of kernel size in target environments. Using 25 maize inbred lines for which extensive genome sequence data is publicly available, we evaluated the response of kernel iron density and kernel mass to water and nitrogen limitation in a managed field stress experiment using a factorial design. To further understand GxE interactions we used partition analysis to characterize response of kernel iron and weight to abiotic stressors among all genotypes, and observed two patterns: one characterized by higher kernel iron concentrations in control over stress conditions, and another with higher kernel iron concentration under drought and combined stress conditions. Breeding efforts for this nutritional trait could exploit these complementary responses through combinations of favorable allelic variation from these already well-characterized genetic stocks.

  7. Abiotic stress growth conditions induce different responses in kernel iron concentration across genotypically distinct maize inbred varieties

    PubMed Central

    Kandianis, Catherine B.; Michenfelder, Abigail S.; Simmons, Susan J.; Grusak, Michael A.; Stapleton, Ann E.

    2013-01-01

    The improvement of grain nutrient profiles for essential minerals and vitamins through breeding strategies is a target important for agricultural regions where nutrient poor crops like maize contribute a large proportion of the daily caloric intake. Kernel iron concentration in maize exhibits a broad range. However, the magnitude of genotype by environment (GxE) effects on this trait reduces the efficacy and predictability of selection programs, particularly when challenged with abiotic stress such as water and nitrogen limitations. Selection has also been limited by an inverse correlation between kernel iron concentration and the yield component of kernel size in target environments. Using 25 maize inbred lines for which extensive genome sequence data is publicly available, we evaluated the response of kernel iron density and kernel mass to water and nitrogen limitation in a managed field stress experiment using a factorial design. To further understand GxE interactions we used partition analysis to characterize response of kernel iron and weight to abiotic stressors among all genotypes, and observed two patterns: one characterized by higher kernel iron concentrations in control over stress conditions, and another with higher kernel iron concentration under drought and combined stress conditions. Breeding efforts for this nutritional trait could exploit these complementary responses through combinations of favorable allelic variation from these already well-characterized genetic stocks. PMID:24363659

  8. Absorption of calcium, magnesium, phosphorus, iron and zinc in growing male rats fed diets containing either phytate-free soybean protein or soybean protein isolate or casein.

    PubMed

    Kamao, M; Tsugawa, N; Nakagawa, K; Kawamoto, Y; Fukui, K; Takamatsu, K; Kuwata, G; Imai, M; Okano, T

    2000-02-01

    The effect of dietary phytate-free soybean protein (PFS) on intestinal mineral absorption and retention was examined in growing male rats using a three-day mineral balance technique. The rats were fed diets containing PFS, soybean protein isolate (SPI) or casein at a 20% level for 5 wk. Total calcium (Ca), magnesium (Mg), phosphorus (P), iron (Fe) and zinc (Zn) contents in diets were adjusted to 0.35, 0.05, 0.7, 0.0035 and 0.003%, respectively, by supplementation of the diet with their salts. Mineral absorption and retention ratios in rats fed the PFS diet were significantly higher than those in rats fed either the SPI or casein diet. These results suggest that PFS may be a promising dietary protein source for improving the mineral bioavailability in humans.

  9. Electromagnetic properties and microwave absorption properties of BaTiO 3-carbonyl iron composite in S and C bands

    NASA Astrophysics Data System (ADS)

    Rui-gang, Yang

    2011-07-01

    BaTiO3 powders are prepared by sol-gel method. The carbonyl iron powder is prepared via thermal decomposition of iron pentacarbonyl. Then BaTiO3-carbonyl iron composite with different mixture ratios was prepared using the as-prepared material. The structure, morphology, and properties of the composites are characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, scanning electron microscopy (SEM), and a network analyzer. The complex permittivity and reflection loss of the composites have been measured at different microwave frequencies in S- and C-bands employing vector network analyzer model PNA 3629D vector. The effect of the mass ratio of BaTiO3/carbonyl iron on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of BaTiO3-carbonyl iron composite has been proposed. The BaTiO3-carbonyl iron composite can find applications in suppression of electromagnetic interference, and reduction of radar signature.

  10. Hydroquinone-Mediated Redox Cycling of Iron and Concomitant Oxidation of Hydroquinone in Oxic Waters under Acidic Conditions: Comparison with Iron-Natural Organic Matter Interactions.

    PubMed

    Jiang, Chao; Garg, Shikha; Waite, T David

    2015-12-15

    Interactions of 1,4-hydroquinone with soluble iron species over a pH range of 3-5 in the air-saturated and partially deoxygenated solution are examined here. Our results show that 1,4-hydroquinone reduces Fe(III) in acidic conditions, generating semiquinone radicals (Q(•-)) that can oxidize Fe(II) back to Fe(III). The oxidation rate of Fe(II) by Q(•-)increases with increase in pH due to the speciation change of Q(•-) with its deprotonated form (Q(•-)) oxidizing Fe(II) more rapidly than the protonated form (HQ(•)). Although the oxygenation of Fe(II) is negligible at pH < 5, O2 still plays an important role in iron redox transformation by rapidly oxidizing Q(•-) to form benzoquinone (Q). A kinetic model is developed to describe the transformation of quinone and iron under all experimental conditions. The results obtained here are compared with those obtained in our previous studies of iron-Suwannee River fulvic acid (SRFA) interactions in acidic solutions and support the hypothesis that hydroquinone moieties can reduce Fe(III) in natural waters. However, the semiquinone radicals generated in pure hydroquinone solution are rapidly oxidized by dioxygen, while the semiquinone radicals generated in SRFA solution are resistant to oxidation by dioxygen, with the result that steady-state semiquinone concentrations in SRFA solutions are 2-3 orders of magnitude greater than in solutions of 1,4-hydroquinone. As a result, semiquinone moieties in SRFA play a much more important role in iron redox transformations than is the case in solutions of simple quinones such as 1,4-hydroquinone. This difference in the steady-state concentration of semiquinone species has a dramatic effect on the cycling of iron between the +II and +III oxidation states, with iron turnover frequencies in solutions containing SRFA being 10-20 times higher than those observed in solutions of 1,4-hydroquinone.

  11. Simultaneous determination of iron and nickel in fluoropolymers by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry.

    PubMed

    Soares, Bruno M; Santos, Rafael F; Bolzan, Rodrigo C; Muller, Edson I; Primel, Ednei G; Duarte, Fabio A

    2016-11-01

    This paper reports the development of a method of simultaneous determination of iron and nickel in fluoropolymers by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) with direct solid sampling. In order to carry out simultaneous measurements, both the main resonance line of nickel (232.003nm) and the adjacent secondary line of iron (232.036nm) were monitored in the same spectral window. The proposed method was optimized with a perfluoroalkoxy (PFA) sample and was applied to the determination of iron and nickel in fluorinated ethylene propylene (FEP) and modified polytetrafluoroethylene (PTFE-TFM) samples. Pyrolysis and atomization temperatures, as well as the use of Pd and H2 (during pyrolysis) as chemical modifiers, were carefully investigated. Compromise temperatures for pyrolysis and atomization of both analytes were achieved at 800 and 2300°C, respectively, using only 0.5Lmin(-1) H2 as chemical modifier during pyrolysis. Calibration curves were performed with aqueous standards by using a single solution which contained both analytes. Limits of detection were 221 and 9.6ngg(-1) for iron and nickel, respectively. Analyte concentrations in all samples ranged from 3.53 to 12.4µgg(-1) for iron and from 37 to 78ngg(-1) for nickel, with relative standard deviation less than 19%. Accuracy was evaluated by comparing these results with those obtained by inductively coupled plasma mass spectrometry after sample digestion by microwave-induced combustion and no significant statistical difference was observed.

  12. Removal Rates of Aqueous Cr(VI) by Zero-Valent Iron Measured Under Flow Conditions

    SciTech Connect

    Kaplan, D.I.

    2002-05-10

    Studies were undertaken to measure the rate of Cr(VI) removal from the aqueous phase by zero-valent iron, Fe(0), under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a groundwater remediation technology that replaces the sand in a filter pack of a conventional well with a reactive material, such as Fe(0). The pseudo-first-order rate coefficients measured under flow conditions were comparable to those previously measured under batch conditions that had significantly greater ratios of solution volume to Fe(0) surface area. Between the range of 20 and 100 weight percent Fe(0), there was little measurable change in the reaction kinetics. Thus, it may be possible to include sand into the reactive filter packs in the event it is necessary to increase filter pack porosity or to decrease the accumulation of secondary reaction products that may lead to filter pack plugging. Background water chemistry had only marginal effects on reaction rate coefficients. The reaction rates measured in this study indicated that an Fe(0) filter pack could be used to lower Cr(VI) concentrations by several orders of magnitude in a once-through mode of operation of the Reactive Well Technology.

  13. Changing the zinc:iron ratio in a cereal-based nutritional supplement has no effect on percent absorption of iron and zinc in Sri Lankan children.

    PubMed

    Hettiarachchi, Manjula; Liyanage, Chandrani; Hilmers, David; Griffin, Ian; Abrams, Steven A

    2010-04-01

    The Thriposha programme is a community-level nutrition intervention in Sri Lanka that provides a combination of energy, protein and micronutrients as a 'ready-to-eat' cereal-based food. We measured the bioavailability of Fe and Zn from Thriposha formula at two different molar ratios of Zn:Fe in order to determine the effect on Fe and Zn absorption. Children 4-7 years (n 53) were given a meal prepared with 50 g Thriposha containing 1.5 mg Zn as zinc sulphate and either 9 mg (high Fe concentration (HiFe)) or 4.5 mg (low Fe concentration (LoFe)) Fe as ferrous fumarate. Zn and Fe percent absorption were measured using stable isotopes by tracer:tracee ratio and by incorporation of erythrocytes, respectively. Percent Fe absorption from the two meals was similar (6.6 % (4.8) v. 4.8 % (2.6); P = 0.15), but total Fe absorption was significantly higher from the HiFe meal (0.59 (0.43) mg) than the LoFe meal (0.20 (0.12) mg; P = 0.01). There was no significant difference between the two groups in Zn absorption (10.7 % (0.9) v. 8.8 % (1.4), P = 0.13, respectively). Decreasing the amount of Fe in Thriposha did not cause a significant change in the percent absorption of Fe and Zn, but significantly lowered the total amount of absorbed Fe. These results demonstrate the utility of maintaining a higher Fe content in this supplement. Further studies to increase Zn content are warranted while maintaining a HiFe.

  14. Oxygen produced by cyanobacteria in simulated Archaean conditions partly oxidizes ferrous iron but mostly escapes-conclusions about early evolution.

    PubMed

    Rantamäki, Susanne; Meriluoto, Jussi; Spoof, Lisa; Puputti, Eeva-Maija; Tyystjärvi, Taina; Tyystjärvi, Esa

    2016-12-01

    The Earth has had a permanently oxic atmosphere only since the great oxygenation event (GOE) 2.3-2.4 billion years ago but recent geochemical research has revealed short periods of oxygen in the atmosphere up to a billion years earlier before the permanent oxygenation. If these "whiffs" of oxygen truly occurred, then oxygen-evolving (proto)cyanobacteria must have existed throughout the Archaean aeon. Trapping of oxygen by ferrous iron and other reduced substances present in Archaean oceans has often been suggested to explain why the oxygen content of the atmosphere remained negligible before the GOE although cyanobacteria produced oxygen. We tested this hypothesis by growing cyanobacteria in anaerobic high-CO2 atmosphere in a medium with a high concentration of ferrous iron. Microcystins are known to chelate iron, which prompted us also to test the effects of microcystins and nodularins on iron tolerance. The results show that all tested cyanobacteria, especially nitrogen-fixing species grown in the absence of nitrate, and irrespective of the ability to produce cyanotoxins, were iron sensitive in aerobic conditions but tolerated high concentrations of iron in anaerobicity. This result suggests that current cyanobacteria would have tolerated the high-iron content of Archaean oceans. However, only 1 % of the oxygen produced by the cyanobacterial culture was trapped by iron, suggesting that large-scale cyanobacterial photosynthesis would have oxygenated the atmosphere even if cyanobacteria grew in a reducing ocean. Recent genomic analysis suggesting that ability to colonize seawater is a secondary trait in cyanobacteria may offer a partial explanation for the sustained inefficiency of cyanobacterial photosynthesis during the Archaean aeon, as fresh water has always covered a very small fraction of the Earth's surface. If oxygenic photosynthesis originated in fresh water, then the GOE marks the adaptation of cyanobacteria to seawater, and the late-Proterozoic increase

  15. Computational modeling and preliminary iroN, fepA, and cirA gene expression in Salmonella Enteritidis under iron-deficiency-induced conditions.

    PubMed

    Zárate-Bonilla, Lina J; Del Portillo, Patricia; Sáenz-Suárez, Homero; Gonzáles-Santos, Janneth; Barreto-Sampaio, George E; Poutou-Piñales, Raúl A; Rey, Andrés Felipe; Rey, Jairo Guillermo

    2014-01-01

    Salmonellosis outbreaks in Europe, the United States, and Latin America have been associated with contaminated food derivatives including meat from the poultry industry. Salmonella grown under iron-limiting conditions has the capability to increase concentration of several iron-regulated outer-membrane proteins to augment the acquisition of the metal. These proteins have been proved to have immunogenic properties. Our aim was to increase the relative expression of iroN, fepA, and cirA in Salmonella Enteritidis domestic strain. Furthermore, we proposed a 3-dimensional structure model for each protein to predict and locate antigenic peptides. Our eventual objective is to produce an effective vaccine against regional avian salmonellosis. Two simple factorial designs were carried out to discriminate between 2 nitrogen sources and determine chelating-agent addition timing to augment relative gene expression. Two antigenic peptides located at the external face of each protein and 2 typical domains of iron-regulated outer-membrane proteins, plug and TonB-dep-Rec, were identified from the 3-dimensional models. Tryptone was selected as the best nitrogen source based on growth rate (μx = 0.36 h(-1)) and biomass productivity (Px = 0.9 g•h(-1)•L(-1)) as determined by a general factorial design. Optimum timing for chelating agent addition was in the middle of the log phase, which allowed relative expressions at 4 h of culture. Increase in iroN, fepA, and cirA relative expression was favored by the length of log phase and the addition of chelating agent, which decreased chelating toxicity and enhanced cell growth rate.

  16. Subsurface Conditions Controlling Uranium Incorporation in Iron Oxides: A Redox Stable Sink

    SciTech Connect

    Fendorf, Scott

    2016-04-05

    Toxic metals and radionuclides throughout the U.S. Department of Energy Complex pose a serious threat to ecosystems and to human health. Of particular concern is the redox-sensitive radionuclide uranium, which is classified as a priority pollutant in soils and groundwaters at most DOE sites owing to its large inventory, its health risks, and its mobility with respect to primary waste sources. The goal of this research was to contribute to the long-term mission of the Subsurface Biogeochemistry Program by determining reactions of uranium with iron (hydr)oxides that lead to long-term stabilization of this pervasive contaminant. The research objectives of this project were thus to (1) identify the (bio)geochemical conditions, including those of the solid-phase, promoting uranium incorporation in Fe (hydr)oxides, (2) determine the magnitude of uranium incorporation under a variety of relevant subsurface conditions in order to quantify the importance of this pathway when in competition with reduction or adsorption; (3) identify the mechanism(s) of U(VI/V) incorporation in Fe (hydr)oxides; and (4) determine the stability of these phases under different biogeochemical (inclusive of redox) conditions. Our research demonstrates that redox transformations are capable of achieving U incorporation into goethite at ambient temperatures, and that this transformation occurs within days at U and Fe(II) concentrations that are common in subsurface geochemical environments with natural ferrihydrites—inclusive of those with natural impurities. Increasing Fe(II) or U concentration, or initial pH, made U(VI) reduction to U(IV) a more competitive sequestration pathway in this system, presumably by increasing the relative rate of U reduction. Uranium concentrations commonly found in contaminated subsurface environments are often on the order of 1-10 μM, and groundwater Fe(II) concentrations can reach exceed 1 mM in reduced zones of the subsurface. The redox-driven U(V) incorporation

  17. The plasma membrane proteome of maize roots grown under low and high iron conditions.

    PubMed

    Hopff, David; Wienkoop, Stefanie; Lüthje, Sabine

    2013-10-08

    Iron (Fe) homeostasis is essential for life and has been intensively investigated for dicots, while our knowledge for species in the Poaceae is fragmentary. This study presents the first proteome analysis (LC-MS/MS) of plasma membranes isolated from roots of 18-day old maize (Zea mays L.). Plants were grown under low and high Fe conditions in hydroponic culture. In total, 227 proteins were identified in control plants, whereas 204 proteins were identified in Fe deficient plants and 251 proteins in plants grown under high Fe conditions. Proteins were sorted by functional classes, and most of the identified proteins were classified as signaling proteins. A significant number of PM-bound redox proteins could be identified including quinone reductases, heme and copper-containing proteins. Most of these components were constitutive, and others could hint at an involvement of redox signaling and redox homeostasis by change in abundance. Energy metabolism and translation seem to be crucial in Fe homeostasis. The response to Fe deficiency includes proteins involved in development, whereas membrane remodeling and assembly and/or repair of Fe-S clusters is discussed for Fe toxicity. The general stress response appears to involve proteins related to oxidative stress, growth regulation, an increased rigidity and synthesis of cell walls and adaption of nutrient uptake and/or translocation. This article is part of a Special Issue entitled: Plant Proteomics in Europe.

  18. Different Storage Conditions Influence Biocompatibility and Physicochemical Properties of Iron Oxide Nanoparticles

    PubMed Central

    Zaloga, Jan; Janko, Christina; Agarwal, Rohit; Nowak, Johannes; Müller, Robert; Boccaccini, Aldo R.; Lee, Geoffrey; Odenbach, Stefan; Lyer, Stefan; Alexiou, Christoph

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted increasing attention in many biomedical fields. In magnetic drug targeting SPIONs are injected into a tumour supplying artery and accumulated inside the tumour with a magnet. The effectiveness of this therapy is thus dependent on magnetic properties, stability and biocompatibility of the particles. A good knowledge of the effect of storage conditions on those parameters is of utmost importance for the translation of the therapy concept into the clinic and for reproducibility in preclinical studies. Here, core shell SPIONs with a hybrid coating consisting of lauric acid and albumin were stored at different temperatures from 4 to 45 °C over twelve weeks and periodically tested for their physicochemical properties over time. Surprisingly, even at the highest storage temperature we did not observe denaturation of the protein or colloidal instability. However, the saturation magnetisation decreased by maximally 28.8% with clear correlation to time and storage temperature. Furthermore, the biocompatibility was clearly affected, as cellular uptake of the SPIONs into human T-lymphoma cells was crucially dependent on the storage conditions. Taken together, the results show that the particle properties undergo significant changes over time depending on the way they are stored. PMID:25918940

  19. The impact of changing surface ocean conditions on the dissolution of aerosol iron

    NASA Astrophysics Data System (ADS)

    Fishwick, Matthew P.; Sedwick, Peter N.; Lohan, Maeve C.; Worsfold, Paul J.; Buck, Kristen N.; Church, Thomas M.; Ussher, Simon J.

    2014-11-01

    The proportion of aerosol iron (Fe) that dissolves in seawater varies greatly and is dependent on aerosol composition and the physicochemical conditions of seawater, which may change depending on location or be altered by global environmental change. Aerosol and surface seawater samples were collected in the Sargasso Sea and used to investigate the impact of these changing conditions on aerosol Fe dissolution in seawater. Our data show that seawater temperature, pH, and oxygen concentration, within the range of current and projected future values, had no significant effect on the dissolution of aerosol Fe. However, the source and composition of aerosols had the most significant effect on the aerosol Fe solubility, with the most anthropogenically influenced samples having the highest fractional solubility (up to 3.2%). The impact of ocean warming and acidification on aerosol Fe dissolution is therefore unlikely to be as important as changes in land usage and fossil fuel combustion. Our experimental results also reveal important changes in the size distribution of soluble aerosol Fe in solution, depending on the chemical conditions of seawater. Under typical conditions, the majority (77-100%) of Fe released from aerosols into ambient seawater existed in the colloidal (0.02-0.4 µm) size fraction. However, in the presence of a sufficient concentration of strong Fe-binding organic ligands (10 nM) most of the aerosol-derived colloidal Fe was converted to soluble Fe (<0.02 µm). This finding highlights the potential importance of organic ligands in retaining aerosol Fe in a biologically available form in the surface ocean.

  20. Alcanivorax borkumensis produces an extracellular siderophore in iron-limitation condition maintaining the hydrocarbon-degradation efficiency.

    PubMed

    Denaro, R; Crisafi, F; Russo, D; Genovese, M; Messina, E; Genovese, L; Carbone, M; Ciavatta, M L; Ferrer, M; Golyshin, P; Yakimov, M M

    2014-10-01

    Obligate marine hydrocarbonoclastic bacteria possess genetic and physiological features to use hydrocarbons as sole source of carbon and to compete for the uptake of nutrients in usually nutrient-depleted marine habitats. In the present work we have studied the siderophore-based iron uptake systems in Alcanivorax borkumensis SK2 and their functioning during biodegradation of an aliphatic hydrocarbon, tetradecane, under iron limitation conditions. The antiSMASH analysis of SK2 genome revealed the presence of two different putative operons of siderophore synthetases. Search for the predicted core structures indicated that one siderophore is clearly affiliated to the family of complex oligopeptidic siderophores possessing an Orn-Ser-Orn carboxyl motif whereas the second one is likely to belong to the family of SA (salicylic acid)-based siderophores. Analyzing the supernatant of SK2 culture, an extracellular siderophore was identified and its structure was resolved. Thus, along with the recently described membrane-associated amphiphilic tetrapeptidic siderophore amphibactin, strain SK2 additionally produces an extracellular type of iron-chelating molecule with structural similarity to pseudomonins. Comparative Q-PCR analysis of siderophore synthetases demonstrated their significant up-regulation in iron-depleted medium. Different expression patterns were recorded for two operons during the early and late exponential phases of growth, suggesting a different function of these two siderophores under iron-depleted conditions.

  1. Receptor-mediated binding of milk lactoferrin to nursing piglet enterocytes: a model for studies on absorption of lactoferrin-bound iron.

    PubMed

    Gíslason, J; Douglas, G C; Hutchens, T W; Lönnerdal, B

    1995-07-01

    Lactoferrin, an iron-binding glycoprotein that is abundant in milk of some species, has been suggested to play a key role in the absorption of iron in human infants. This hypothesis is based on the dominant role of lactoferrin as an iron-binding component in human milk and on the occurrence of lactoferrin receptors in brush-border membranes in infants' intestines. The piglet may be a useful model to evaluate the biological activity of lactoferrin because we have previously found the presence of a lactoferrin receptor in brush-border membranes from suckling piglets. In this study, viable enterocytes were isolated from 6- to 20-day-old suckling piglets. Binding studies were performed at 4 degrees C using 125I-labeled porcine lactoferrin. Scatchard analysis of equilibrium binding data showed an apparent binding constant (Kd) of 2 x 10(-6) M (SD = 0.6 x 10(-6)). This affinity is in close agreement with previous results obtained using isolated brush-border membrane vesicles. Bovine lactoferrin inhibited the binding of porcine lactoferrin. Porcine transferrin, however, did not affect porcine lactoferrin binding significantly. Thus, lactoferrin binding is highly specific. When enterocytes were incubated with 125I-labeled lactoferrin at 37 degrees C, the amount of cell-associated radioactivity exceeded the surface binding capacity of the cells by almost fivefold. This finding agrees with the continuous binding and subsequent internalization of 125I-labeled lactoferrin. The isolated piglet enterocyte seems to provide a useful model for further studies of the mechanism of receptor-mediated absorption of lactoferrin.

  2. Calculation of optical and K pre-edge absorption spectra for ferrous iron of distorted sites in oxide crystals

    NASA Astrophysics Data System (ADS)

    Vercamer, Vincent; Hunault, Myrtille O. J. Y.; Lelong, Gérald; Haverkort, Maurits W.; Calas, Georges; Arai, Yusuke; Hijiya, Hiroyuki; Paulatto, Lorenzo; Brouder, Christian; Arrio, Marie-Anne; Juhin, Amélie

    2016-12-01

    Advanced semiempirical calculations have been performed to compute simultaneously optical absorption and K pre-edge x-ray absorption spectra of Fe2 + in four distinct site symmetries found in minerals. The four symmetries, i.e., a distorted octahedron, a distorted tetrahedron, a square planar site, and a trigonal bipyramidal site, are representative of the Fe2 + sites found in crystals and glasses. A particular attention has been paid to the definition of the p -d hybridization Hamiltonian which occurs for noncentrosymmetric symmetries in order to account for electric dipole transitions. For the different sites under study, an excellent agreement between calculations and experiments was found for both optical and x-ray absorption spectra, in particular in terms of relative intensities and energy positions of electronic transitions. To our knowledge, these are the first calculations of optical absorption spectra on Fe2 + placed in such diverse site symmetries, including centrosymmetric sites. The proposed theoretical model should help to interpret the features of both the optical absorption and the K pre-edge absorption spectra of 3 d transition metal ions and to go beyond the usual fingerprint interpretation.

  3. ZERO-VALENT IRON REMOVAL RATES OF AQUEOUS Cr(VI) MEASURED UNDER FLOW CONDITIONS

    SciTech Connect

    Kaplan, Daniel I.; Gilmore, Tyler J.

    2004-06-01

    The rates of Cr(VI) removal from the aqueous phase by zero-valent iron, Fe(0), was measured under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a groundwater remediation technology that replaces the sand in a filter pack of a conventional well with a reactive material, such as Fe(0). Dissolved Cr(VI) concentration, dissolved O2 concentration, and Eh data indicated that Cr(VI) removal from the aqueous phase was mass-transfer limited. All pseudo-first-order regression fits to the data were significant (P≤0.05), however, they did not capture many of the salient aspects of the data, including that the removal rate often decreased as contact time increased. As such, application of these rate coefficients to predict long-term Cr(VI) removal were compromised. The rate coefficients measured under flow conditions were comparable to those measured previously under batch conditions with significantly greater solution:solid ratios. Between the range of 20 and 100 wt-% Fe(0) in the column, there was little measurable change in the reaction kinetics. Thus, it may be possible to include sand into the reactive filter packs in the event it is necessary to increase filter pack porosity or to decrease the accumulation of secondary reaction products that may lead to filter pack plugging. Background water chemistry (0.2 M NaHCO3, distilled water, and a carbonate-dominated groundwater) had only marginal, if any, effects on reaction rate coefficients. The reaction rates measured in this study indicated that an Fe(0) filter pack could be used to lower Cr(VI) concentrations by several orders of magnitude in a once-through mode of operation of the Reactive Well Technology.

  4. Studies on a Novel Actinobacteria Species Capable of Oxidizing Ammonium under Iron Reduction Conditions

    NASA Astrophysics Data System (ADS)

    Huanh, Shan; Ruiz-Urigüen, Melany; Jaffe, Peter R.

    2014-05-01

    Ammonium (NH4+) oxidation coupled to iron reduction in the absence of oxygen and nitrate/nitrite (NO3-/NO2-) was noted in a forested riparian wetland in New Jersey (1,2), and in tropical rainforest soils (3), and was coined Feammox (4). Through a 180-days anaerobic incubation of soil samples collected at the New Jersey site, and using 16S rDNA PCR-DGGE, 454-pyosequecing, and qPCR analysis, we have shown that an Acidimicrobiaceae bacterium A6, belonging to the phylum Actinobacteria, is responsible for this Feammox process, described previously (1,2). We have enriched these Feammox bacteria in a high efficiency Feammox membrane reactor (with 85% NH4+removal per 48h), and isolated the pure Acidimicrobiaceae bacterium A6 strain 5, in an autotrophic medium. To determine if the Feammox bacteria found in this study are common, at least at the regional scale, we analyzed a series of local wetland-, upland-, as well as storm-water detention pond-sediments. Through anaerobic incubations and molecular biology analysis, the Feammox reaction and Acidimicrobiaceae bacterium A6 were found in three of twenty soil samples collected, indicating that the Feammox pathway might be widespread in selected soil environments. Results show that soil pH and Fe(III) content are key environmental factors controlling the distributions of Feammox bacteria, which require acidic conditions and the presence of iron oxides. Results from incubation experiments conducted at different temperatures have shown that, in contrast to another anaerobic ammonium oxidation pathways (e.g., anammox), the optimal temperature of the Feammox process is ~ 20° and that the organisms are still active when the temperature is around 10°. An incubation experiment amended with acetylene gas (C2H2) as a selected inhibitor showed that in the Feammox reaction, Fe(III) is the electron acceptor, which is reduced to Fe(II), and NH4+is the electron donor, which is oxidized to NO2-. After this process, NO2- is converted to

  5. Gold and iron oxide associations under supergene conditions: An experimental approach

    NASA Astrophysics Data System (ADS)

    Greffié, Catherine; Benedetti, Marc F.; Parron, Claude; Amouric, Marc

    1996-05-01

    Abstract-The interaction of gold hydroxo-chloro complexes with iron oxides (ferrihydrites, goethites) during coprecipitation experiments is investigated. Chemical analyses of solids and solutions are coupled with a detailed characterization of the iron oxides with various methods, including X-ray diffraction, High Resolution Transmission Electron Microscopy (HRTEM), and Mössbauer spectroscopy. HCl solutions containing varying amounts of AuCl 4- and ferric nitrate were titrated to neutral or alkaline pH, resulting in the coprecipitation of gold and iron oxide phases (ferrihydrite or goethite). Reference titrations were performed in the absence of iron. Most of the gold was removed from solution in the presence of iron oxides whereas gold remained dissolved in the reference samples. In association with iron oxides two forms of gold have been identified by HRTEM and 197Au Mössbauer spectroscopy: metallic gold as well as chloro and/or hydroxo combined gold. This combined gold is in a trivalent state as the primary product which means that a reduction process is not a necessary step for the adsorption of gold species on iron oxides. Metallic gold characterized in these products by means of HRTEM consists mainly of colloids ranging from 3-60 nm in diameter embedded in the ferrihydrite matrix, as isolated particles or as particles associated with goethite laths. The smallest metallic gold particles detected would be almost invisible to classical observation techniques used for solid phases. In our experiments, oxidation-reduction reactions between Fe 2+ and Au 3+ are responsible for the presence of metallic gold observed on the iron phases. Photochemical reactions may also take part in the reduction process. Colloidal gold and gold complexes could be associated to the iron oxides by strong electrostatic interactions. Our results suggest that poorly ordered iron oxides are highly efficient in trapping gold from solutions thanks to their high surface area, and favor gold

  6. Iron and hepcidin: a story of recycling and balance.

    PubMed

    Camaschella, Clara

    2013-01-01

    To avoid iron deficiency and overload, iron availability is tightly regulated at both the cellular and systemic levels. The liver peptide hepcidin controls iron flux to plasma from enterocytes and macrophages through degradation of the cellular iron exporter ferroportin. The hepcidin-ferroportin axis is essential to maintaining iron homeostasis. Genetic inactivation of proteins of the hepcidin-activating pathway causes iron overload of varying severity in human and mice. Hepcidin insufficiency and increased iron absorption are also characteristic of anemia due to ineffective erythropoiesis in which, despite high total body iron, hepcidin is suppressed by the high erythropoietic activity, worsening both iron overload and anemia in a vicious cycle. Hepcidin excess resulting from genetic inactivation of a hepcidin inhibitor, the transmembrane protease serine 6 (TMPRSS6) leads to a form of iron deficiency refractory to oral iron. Increased hepcidin explains the iron sequestration and iron-restricted erythropoiesis of anemia associated with chronic inflammatory diseases. In mice, deletion of TMPRSS6 in vivo has profound effects on the iron phenotype of hemochromatosis and beta-thalassemia. Hepcidin manipulation to restrict iron is a successful strategy to improve erythropoiesis in thalassemia, as shown clearly in preclinical studies targeting TMPRSS6; attempts to control anemia of chronic diseases by antagonizing the hepcidin effect are ongoing. Finally, the metabolic pathways identified from iron disorders are now being explored in other human pathologic conditions, including cancer.

  7. Performance of Uncoated Carbide Cutting Tool when Machining Cast Iron in Dry Cutting Condition

    NASA Astrophysics Data System (ADS)

    Jaharah, A. G.; Che Hassan, C. H.; Ghazali, M. J.; Sulong, A. B.; Omar, M. Z.; Nuawi, M. Z.; Ismail, A. R.

    This paper presents the performance of uncoated carbide cutting tool when machining cast iron in dry cutting conditions. Experiments were conducted at various cutting speeds, feed rates, and depths of cut according to Taguchi method design of experiment using a standard orthogonal array L9(34). The effects of cutting speeds (100-146 m/min), feed rates (0.20-0.35 mm/tooth) and depths of cut (1.0-2.0 mm) on the tool life, surface roughness and cutting forces were evaluated using ANOVA. Results showed that the effects of cutting speed, depth of cut and the feed rate were similar affecting the failure of the carbide cutting tools within the range of tested machining parameters. The contribution of cutting speed, feed rate, and depth of cut in controlling the tool life were 32.12%, 38.56% and 29.32% respectively. Whereas, the cutting speed was the main factor influencing the average surface roughness (Ra) value followed by feed rate. These factors contribute 60.53% and 35.59% respectively to the Ra value. On the other hand, cutting forces generated were greatly influenced by the depth of cut (66.52%) and the feed rate (32.6%). Cutting speed was found insignificant in controlling the generated cutting forces.

  8. Redox transformations of iron in the presence of exudate from the cyanobacterium Microcystis aeruginosa under conditions typical of natural waters.

    PubMed

    Wang, Kai; Garg, Shikha; Waite, T David

    2017-02-24

    Interaction of the exudate secreted by a toxic strain of the cyanobacterium Microcystis aeruginosa with Fe(II) and Fe(III) was investigated here under both acidic (pH 4) and alkaline (pH 8) conditions. At the concentrations of iron and exudate used, iron was present as dissolved iron (< 0.025 µm) at pH 4 but principally as small (< 0.45 µm) iron oxyhydroxide particles at pH 8 with only ~3-27% present in the dissolved form as a result of iron binding by the organic exudate. The formation of strong Fe(III)-exudate and relatively weak Fe(II)-exudate complexes alters the reduction potential of the Fe(III)/Fe(II) redox couple facilitating more rapid oxidation of Fe(II) at pH 4 and 8 than was the case in the absence of exudate. Our results further show that the organic exudate contains Fe(III) reducing moieties resulting in production of measureable concentrations of Fe(II). However, these reducing moieties are short-lived (with a half-life of 1.9 hours) and easily oxidized in air-saturated environments. A kinetic model was developed that adequately describes the redox transformation of Fe in the presence of exudate both at pH 4 and pH 8.

  9. High-performance inulin and oligofructose prebiotics increase the intestinal absorption of iron in rats with iron deficiency anaemia during the growth phase.

    PubMed

    Freitas, Karine de Cássia; Amancio, Olga Maria Silvério; de Morais, Mauro Batista

    2012-09-28

    Considering the high frequency of anaemia due to Fe deficiency, it is important to evaluate the effects of prebiotics on the absorption of Fe. The aim of the present study was to evaluate the effects of high-performance (HP) inulin, oligofructose and synergy1 during recovery from anaemia in rats through the intestinal absorption of Fe, food intake, body growth, caecal pH and weight of the intestine. Wistar rats (n 47) were fed with rations of AIN93-G with no Fe to induce Fe deficiency anaemia. At 36 d of life, anaemic rats were divided into four groups: (1) the HP inulin group; (2) the synergy1 group; and (3) the oligofructose group, all with 100 g of the respective prebiotic per kg of ration; and (4) a control group, in which the prebiotic was replaced by maize starch. Then, 25 mg of elemental Fe/kg of ration was added to all rations to allow recovery from anaemia. The final values of Hb in the HP inulin, synergy1, oligofructose and control groups were, respectively: 98 (94-99); 83 (81-92); 100 (90-114); 77 (72-81) g/l, with a statistically significant difference (P ≤ 0·001) between the oligofructose and control groups and the HP inulin and control groups. The four groups had an increase in weight and body length and had similar consumption of rations. The intestinal weight and caecal pH were significantly different between the groups that consumed prebiotics and the control group. HP inulin and oligofructose increased the intestinal absorption of Fe in rats.

  10. Enhancement of iron(II)-dependent reduction of nitrite to nitric oxide by thiocyanate and accumulation of iron(II)/thiocyanate/nitric oxide complex under conditions simulating the mixture of saliva and gastric juice.

    PubMed

    Takahama, Umeo; Hirota, Sachiko

    2012-01-13

    Iron(III) ingested as a food component or supplement for iron deficiencies can react with salivary SCN(-) to produce Fe(SCN)(2+) and can be reduced to iron(II) by ascorbic acid in the stomach. Iron(II) generated in the stomach can react with salivary nitrite and SCN(-) to produce nitric oxide (NO) and FeSCN(+), respectively. The purpose of this investigation is to make clear the reactions among nitrite, SCN(-), iron ions, and ascorbic acid under conditions simulating the mixture of saliva and gastric juice. Iron(II)-dependent reduction of nitrite to NO was enhanced by SCN(-) in acidic buffer solutions, and the oxidation product of iron(II) reacted with SCN(-) to produce Fe(SCN)(2+). Almost all of the NO produced was autoxidized to N(2)O(3) under aerobic conditions. Iron(II)-dependent production of NO was also observed in acidified saliva. Under anaerobic conditions, NO transformed Fe(SCN)(2+) and FeSCN(+) to Fe(SCN)NO(+) in acidic buffer solutions. Fe(SCN)NO(+) was also formed under aerobic conditions when excess ascorbic acid was added to iron(II)/nitrite/SCN(-) systems in acidic buffer solutions and acidified saliva. The Fe(SCN)NO(+) formed was transformed to Fe(SCN)(2+) and iron(III) at pH 2.0 and pH 7.4, respectively, by O(2). Salivary glycoproteins could complex with iron(III) in the stomach preventing the formation of Fe(SCN)(2+). Ascorbic acid reduced iron(III) to iron(II) to react with nitrite and SCN(-) as described above. The above results suggest (i) that iron(II) can have toxic effects on the stomach through the formation of reactive nitrogen oxide species from NO when supplemented without ascorbic acid and through the formation of both reactive nitrogen oxide species and Fe(SCN)NO(+) when supplemented with ascorbic acid, and (ii) that the toxic effects of iron(III) seemed to be smaller than and similar to those of iron(II) when supplemented without and with ascorbic acid, respectively. Possible mechanisms that cause oxidative stress on the stomach

  11. Solid / Liquid Partitioning of Iron in (Mg0.9Fe0.1)2SiO4 Bulk Composition under Lower Mantle Conditions

    NASA Astrophysics Data System (ADS)

    Nomura, R.; Hirose, K.; Tateno, S.

    2009-12-01

    Melting causes strong chemical differentiation in the Earth’s interior. It is generally believed that ultra-low velocity zone (ULVZ) observed in the lowermost mantle represents the partially molten zone, but the nature of partial melting is not known yet. Is the partial melt enriched in iron? Is it denser than coexisting solid? Here we investigate the partitioning of iron between partial melt and solid residue in (Mg0.9Fe0.1)2SiO4 bulk composition up to 61 GPa using laser-heated diamond-anvil cell (LHDAC). We used the olivine from KLB-1 peridotite as starting material and loaded its powder between the argon pressure medium. The sample was heated from double side using the Nd:YLF laser. Melting was confirmed by a sudden increase in the absorption of the laser light by the sample. A recovered sample was processed to a thin film by Ar ion using the Ion Slicer, and subsequently examined under field emission-type microprobe (FE-EPMA). The X-ray mapping of the sample showed the extensive segregation of each phase under the temperature gradient. The center of the laser-heated hot spot had non-stoichiometric composition, indicating a quenched liquid. Liquidus phase was found to be ferropericlase (Fp) up to ~26 GPa and changed into Mg-silicate perovskite (MgPv) at about 31GPa, consistent with the results obtained by previous melting experiments in multi-anvil apparatus (Ohtani et al., 1998 PEPI; Ito et al., 2004 PEPI). MgPv remains the liquidus phase up to 61 GPa, the highest pressure condition examined so far in this study. We determined the iron partitioning between MgPv and melt (D= FeO (in crystal, wt.%) / FeO (in liquid, wt.%)) from the results of chemical analyses. The partition coefficient D increased weakly with increasing pressure from 31 to 61 GPa, though partial melt remains more iron-rich than perovskite up to 61GPa. The results up to the lowermost mantle condition will be discussed in the presentation.

  12. Transdermal iron replenishment therapy.

    PubMed

    Modepalli, Naresh; Shivakumar, H N; Kanni, K L Paranjothy; Murthy, S Narasimha

    2015-01-01

    Iron deficiency anemia is one of the major nutritional deficiency disorders. Iron deficiency anemia occurs due to decreased absorption of iron from diet, chronic blood loss and other associated diseases. The importance of iron and deleterious effects of iron deficiency anemia are discussed briefly in this review followed by the transdermal approaches to deliver iron. Transdermal delivery of iron would be able to overcome the side effects associated with conventional oral and parenteral iron therapy and improves the patient compliance. During preliminary investigations, ferric pyrophosphate and iron dextran were selected as iron sources for transdermal delivery. Different biophysical techniques were explored to assess their efficiency in delivering iron across the skin, and in vivo studies were carried out using anemic rat model. Transdermal iron delivery is a promising approach that could make a huge positive impact on patients suffering with iron deficiency.

  13. Determination of molybdenum in ores, iron and steel by atomic-absorption spectrophotometry after separation by alpha-benzoinoxime extraction or further xanthate extraction.

    PubMed

    Donaldson, E M

    1980-02-01

    A simple and moderately rapid method for determining 0.001% or more of molybdenum in ores, iron and steel is described. After sample decomposition, molybdenum is separated from the matrix elements, except tungsten, by chloroform extraction of its alpha-benzoinoxime complex from a 1.75 M hydrochloric-0.13 M tartaric acid medium. Depending on the amount of tungsten present, molybdenum, if necessary, is back-extracted into concentrated ammonia solution and subsequently separated from coextracted tungsten by chloroform extraction of its xanthate complex from a 1.5M hydrochloric-0.13M tartaric acid medium. It is ultimately determined by atomic-absorption spectrophotometry, at 313.3 nm, in a 15% v/v hydrochloric acid medium containing 1,000 microg/ml of aluminium as the chloride, after evaporation of either extract to dryness with nitric, perchloric and sulphuric acids and dissolution of the salts in dilute ammonia solution.

  14. Low-field microwave absorption and magnetoresistance in iron nanostructures grown by electrodeposition on n-type lightly doped silicon substrates

    NASA Astrophysics Data System (ADS)

    Felix, J. F.; Figueiredo, L. C.; Mendes, J. B. S.; Morais, P. C.; Araujo, C. I. L. de.

    2015-12-01

    In this study we investigate magnetic properties, surface morphology and crystal structure in iron nanoclusters electrodeposited on lightly doped (100) n-type silicon substrates. Our goal is to investigate the spin injection and detection in the Fe/Si lateral structures. The samples obtained under electric percolation were characterized by magnetoresistive and magnetic resonance measurements with cycling the sweeping applied field in order to understand the spin dynamics in the as-produced samples. The observed hysteresis in the magnetic resonance spectra, plus the presence of a broad peak in the non-saturated regime confirming the low field microwave absorption (LFMA), were correlated to the peaks and slopes found in the magnetoresistance curves. The results suggest long range spin injection and detection in low resistive silicon and the magnetic resonance technique is herein introduced as a promising tool for analysis of electric contactless magnetoresistive samples.

  15. Determination of tin, vanadium, iron, and molybdenum in various matrices by atomic absorption spectrometry using a simultaneous liquid-liquid extraction procedure.

    PubMed

    Sánchez-Viñas, M; Bagur, G M; Gázquez, D; Camino, M; Romero, R

    1999-01-01

    An atomic-absorption spectrometric method is described for the determination of tin, vanadium, iron, and molybdenum in two certified reference materials, food samples, and petroleum crude. After treatment with acids, these elements are separated from matrix elements by simultaneous solvent extraction of 5,5'-methylenedisalicylohydroxamic acid complexes from HCl/NaClO4 solution into an isobutyl methyl ketone/tributyl phosphate solution. The detection limits range from 0.018 to 0.19 microg/mL (n = 3), and the relative standard deviations do not exceed 2.0% at levels of 0.5, 0.6, 2.0, and 7.0 microg/mL of Fe, Mo, V, and Sn, respectively. The method is selective and suffers only from interference by Zr(IV), Ti(IV), Th(IV), W(VI), PO4(3-), and F-.

  16. Al-hijamah and oral honey for treating thalassemia, conditions of iron overload, and hyperferremia: toward improving the therapeutic outcomes.

    PubMed

    El Sayed, Salah Mohamed; Baghdadi, Hussam; Abou-Taleb, Ashraf; Mahmoud, Hany Salah; Maria, Reham A; Ahmed, Nagwa S; Helmy Nabo, Manal Mohamed

    2014-01-01

    Iron overload causes iron deposition and accumulation in the liver, heart, skin, and other tissues resulting in serious tissue damages. Significant blood clearance from iron and ferritin using wet cupping therapy (WCT) has been reported. WCT is an excretory form of treatment that needs more research efforts. WCT is an available, safe, simple, economic, and time-saving outpatient modality of treatment that has no serious side effects. There are no serious limitations or precautions to discontinue WCT. Interestingly, WCT has solid scientific and medical bases (Taibah mechanism) that explain its effectiveness in treating many disease conditions differing in etiology and pathogenesis. WCT utilizes an excretory physiological principle (pressure-dependent excretion) that resembles excretion through renal glomerular filtration and abscess evacuation. WCT exhibits a percutaneous excretory function that clears blood (through fenestrated skin capillaries) and interstitial fluids from pathological substances without adding a metabolic or detoxification burden on the liver and the kidneys. Interestingly, WCT was reported to decrease serum ferritin (circulating iron stores) significantly by about 22.25% in healthy subjects (in one session) and to decrease serum iron significantly to the level of causing iron deficiency (in multiple sessions). WCT was reported to clear blood significantly of triglycerides, low-density lipoprotein (LDL) cholesterol, total cholesterol, uric acid, inflammatory mediators, and immunoglobulin antibodies (rheumatoid factor). Moreover, WCT was reported to enhance the natural immunity, potentiate pharmacological treatments, and to treat many different disease conditions. There are two distinct methods of WCT: traditional WCT and Al-hijamah (WCT of prophetic medicine). Both start and end with skin sterilization. In traditional WCT, there are two steps, skin scarification followed by suction using plastic cups (double S technique); Al-hijamah is a three

  17. Al-hijamah and oral honey for treating thalassemia, conditions of iron overload, and hyperferremia: toward improving the therapeutic outcomes

    PubMed Central

    El Sayed, Salah Mohamed; Baghdadi, Hussam; Abou-Taleb, Ashraf; Mahmoud, Hany Salah; Maria, Reham A; Ahmed, Nagwa S; Helmy Nabo, Manal Mohamed

    2014-01-01

    Iron overload causes iron deposition and accumulation in the liver, heart, skin, and other tissues resulting in serious tissue damages. Significant blood clearance from iron and ferritin using wet cupping therapy (WCT) has been reported. WCT is an excretory form of treatment that needs more research efforts. WCT is an available, safe, simple, economic, and time-saving outpatient modality of treatment that has no serious side effects. There are no serious limitations or precautions to discontinue WCT. Interestingly, WCT has solid scientific and medical bases (Taibah mechanism) that explain its effectiveness in treating many disease conditions differing in etiology and pathogenesis. WCT utilizes an excretory physiological principle (pressure-dependent excretion) that resembles excretion through renal glomerular filtration and abscess evacuation. WCT exhibits a percutaneous excretory function that clears blood (through fenestrated skin capillaries) and interstitial fluids from pathological substances without adding a metabolic or detoxification burden on the liver and the kidneys. Interestingly, WCT was reported to decrease serum ferritin (circulating iron stores) significantly by about 22.25% in healthy subjects (in one session) and to decrease serum iron significantly to the level of causing iron deficiency (in multiple sessions). WCT was reported to clear blood significantly of triglycerides, low-density lipoprotein (LDL) cholesterol, total cholesterol, uric acid, inflammatory mediators, and immunoglobulin antibodies (rheumatoid factor). Moreover, WCT was reported to enhance the natural immunity, potentiate pharmacological treatments, and to treat many different disease conditions. There are two distinct methods of WCT: traditional WCT and Al-hijamah (WCT of prophetic medicine). Both start and end with skin sterilization. In traditional WCT, there are two steps, skin scarification followed by suction using plastic cups (double S technique); Al-hijamah is a three

  18. Redox speciation analysis of dissolved iron in estuarine and coastal waters with on-line solid phase extraction and graphite furnace atomic absorption spectrometry detection.

    PubMed

    Chen, Yaojin; Feng, Sichao; Huang, Yongming; Yuan, Dongxing

    2015-05-01

    An automatic on-line solid phase extraction (SPE) system employing the flow injection (FI) technique directly coupled to a graphite furnace atomic absorption spectrometer (GFAAS) was established for speciation and determination of dissolved iron in estuarine and coastal waters. Fe(II) was mixed with ferrozine solution in a sample stream to form the Fe(II)-ferrozine complex which was extracted onto a C18 SPE cartridge, eluted with eluent and detected with GFAAS. In a parallel flow channel, Fe(III) was reduced to Fe(II) with ascorbic acid and then detected in the same way as Fe(II). The home-made interface between FI-SPE and GFAAS efficiently realized the sample introduction to the furnace in a semi-automated way. Parameters of the FI-SPE system and graphite furnace program were optimized based on a univariate experimental design and an orthogonal array design. The salinity effect on the method sensitivity was investigated. The proposed method provided a detection limit of 1.38 nmol L(-1) for Fe(II) and 1.87 nmol L(-1) for Fe(II+III). With variation of the sample loading volume, a broadened determination range of 2.5-200 nmol L(-1) iron could be obtained. The proposed method was successfully applied to analyze iron species in samples collected from the Jiulongjiang Estuary, Fujian, China. With the 2-cartridge FI-SPE system developed, on-line simultaneous determination of Fe species with GFAAS was achieved for the first time.

  19. Kinetic study for phenol degradation by ZVI-assisted Fenton reaction and related iron corrosion investigated by X-ray absorption spectroscopy.

    PubMed

    Yoon, In-Ho; Yoo, Gursong; Hong, Hye-Jin; Kim, Jungmin; Kim, Min Gyu; Choi, Wang-Kyu; Yang, Ji-Won

    2016-02-01

    In this study, we investigated phenol degradation via zero-valent iron (ZVI)-assisted Fenton reaction through kinetic and spectroscopic analysis. In batch experiments, 100 mg/L of phenol was completely degraded, and 75% of TOC was removed within 3 min under an optimal hydrogen peroxide (H2O2) concentration (50 mM) via the Fenton reaction. In the absence of H2O2, oxygen (O2) was dissolved into the solution and produced H2O2, which resulted in phenol degradation. However, phenol removal efficiency was not very high compared to external H2O2 input. The Fenton reaction rapidly occurred at the surface of ZVI, and then phenol mobility from the solution to the ZVI surface was the rate determining step of the whole reaction. The pseudo-second order adsorption kinetic model well describes phenol removal, and its rate increased according to the H2O2 concentration. X-ray absorption spectroscopic analysis revealed that iron oxide (Fe-O bonding) was formed on ZVI with [H2O2] > 50 mM. A high concentration of H2O2 led to rapid degradation of phenol and caused corrosion on the ZVI surface, indicating that Fe(2+) ions were rapidly oxidized to Fe(3+) ions due to the Fenton reaction and that Fe(3+) was precipitated as iron oxide on the ZVI surface. However, ZVI did not show corroded characteristics in the absence of H2O2 due to the insufficient ZVI-assisted Fenton reaction and oxidation of Fe(2+) to Fe(3+).

  20. Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

    USGS Publications Warehouse

    Henneberry, Yumiko K.; Kraus, Tamara E.C.; Nico, Peter S.; Horwath, William R.

    2012-01-01

    The objective was to assess the interaction of Fe coprecipitated with dissolved organic matter (DOM) and its effect on Fe (hydr)oxide crystallinity and DOM retention under abiotic reducing conditions. A Fe-based coagulant was reacted with DOM from an agricultural drain and the resulting precipitate (floc) was exposed to S(-II) and Fe(II). Solution concentrations of Fe(II/III) and DOM were monitored, floc crystallinity was determined using X-ray diffraction, and the composition and distribution of functional groups were assessed using scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Results indicate coprecipitation of Fe(III) with DOM forms a non-crystalline floc that withstands crystallization regardless of change in pH, Fe:DOM ratio and type of reductant added. There was no evidence that exposure to reducing conditions led to release of DOM from the floc, indicating that coprecipitation with complex natural DOM in aquatic environments may stabilize Fe (hydr)oxides against crystallization upon reaction with reduced species and lead to long term sequestration of the DOM. STXM analysis identified spatially distinct regions with remarkable functional group purity, contrary to the model of DOM as a relatively uniform complex polymer lacking identifiable organic compounds. Polysaccharide-like OM was strongly and directly correlated with the presence of Fe but showed different Fe binding strength depending on the presence of carboxylic acid functional groups, whereas amide and aromatic functional groups were inversely correlated with Fe content.

  1. Equimolar carbon absorption by potassium phthalimide and in situ catalytic conversion under mild conditions.

    PubMed

    Zhang, Shuai; Li, Yu-Nong; Zhang, Ya-Wei; He, Liang-Nian; Yu, Bing; Song, Qing-Wen; Lang, Xian-Dong

    2014-05-01

    Potassium phthalimide, with weak basicity, is an excellent absorbent for rapid carbon dioxide capture with almost equimolar absorption. This process is assumed to proceed through the potassium carbamate formation pathway, as supported by NMR spectroscopy, an in situ FTIR study, and computational calculations. Both the basicity and nucleophilicity of phthalimide salts have a crucial effect on the capture process. Furthermore, the captured carbon dioxide could more easily be converted in situ into value-added chemicals and fuel-related products through carbon capture and utilization, rather than going through a desorption process.

  2. Perspectives on nutritional iron deficiency.

    PubMed

    Hallberg, L

    2001-01-01

    Nutritional iron deficiency (ID) is caused by an intake of dietary iron insufficient to cover physiological iron requirements. Studies on iron absorption from whole diets have examined relationships between dietary iron bioavailability/absorption, iron losses, and amounts of stored iron. New insights have been obtained into regulation of iron absorption and expected rates of changes of iron stores or hemoglobin iron deficits when bioavailability or iron content of the diet has been modified and when losses of iron occur. Negative effects of ID are probably related to age, up to about 20 years, explaining some of earlier controversies. Difficulties in establishing the prevalence of mild ID are outlined. The degree of underestimation of the prevalence of mild ID when using multiple diagnostic criteria is discussed. It is suggested that current low-energy lifestyles are a common denominator for the current high prevalence not only of ID but also of obesity, diabetes, and osteoporosis.

  3. Changes of the corrosion potential of iron in stagnation and flow conditions and their relationship with metal release.

    PubMed

    Fabbricino, Massimiliano; Korshin, Gregory V

    2014-10-01

    This study examined the behavior of corrosion potential (Ecorr) of iron exposed to drinking water during episodes of stagnation and flow. These measurements showed that during stagnation episodes, Ecorr values decrease prominently and consistently. This decrease is initially rapid but it becomes slower as the stagnation time increases. During flow episodes, the Ecorr values increase and reach a quasi-steady state. Experiments with varying concentrations of dissolved oxygen showed that the decrease of Ecorr values characteristic for stagnation is likely to be associated with the consumption of dissolved oxygen by the exposed metal. The corrosion potential of iron and its changes during stagnation were sensitive to the concentrations of sulfate and chloride ions. Measurements of iron release showed that both the absolute values of Ecorr measured prior to or after stagnation episodes were well correlated with the logarithms of concentrations of total iron. The slope of this dependence showed that the observed correlations between Ecorr values and Fe concentrations corresponded to the coupling between the oxidant consumption and changes of Fe redox status. These results demonstrate that in situ Ecorr measurements can be a sensitive method with which to ascertain effects of hydrodynamic conditions and short-term variations of water chemistry on metal release and corrosion in drinking water. This approach is valuable practically because Ecorr measurements are precise, can be carried out in situ with any desired time resolution, do not affect the state of exposed surface in any extent and can be carried out with readily available equipment.

  4. Iron speciation in human cancer cells by K-edge total reflection X-ray fluorescence-X-ray absorption near edge structure analysis

    NASA Astrophysics Data System (ADS)

    Polgári, Zs.; Meirer, F.; Sasamori, S.; Ingerle, D.; Pepponi, G.; Streli, C.; Rickers, K.; Réti, A.; Budai, B.; Szoboszlai, N.; Záray, G.

    2011-03-01

    X-ray absorption near edge structure (XANES) analysis in combination with synchrotron radiation induced total reflection X-ray fluorescence (SR-TXRF) acquisition was used to determine the oxidation state of Fe in human cancer cells and simultaneously their elemental composition by applying a simple sample preparation procedure consisting of pipetting the cell suspension onto the quartz reflectors. XANES spectra of several inorganic and organic iron compounds were recorded and compared to that of different cell lines. The XANES spectra of cells, independently from the phase of cell growth and cell type were very similar to that of ferritin, the main Fe store within the cell. The spectra obtained after CoCl 2 or NiCl 2 treatment, which could mimic a hypoxic state of cells, did not differ noticeably from that of the ferritin standard. After 5-fluorouracil administration, which could also induce an oxidative-stress in cells, the absorption edge position was shifted toward higher energies representing a higher oxidation state of Fe. Intense treatment with antimycin A, which inhibits electron transfer in the respiratory chain, resulted in minor changes in the spectrum, resembling rather the N-donor Fe-α,α'-dipyridyl complex at the oxidation energy of Fe(III), than ferritin. The incorporation of Co and Ni in the cells was followed by SR-TXRF measurements.

  5. The first promoter for conditional gene expression in Acremonium chrysogenum: iron starvation-inducible mir1(P).

    PubMed

    Gsaller, Fabio; Blatzer, Michael; Abt, Beate; Schrettl, Markus; Lindner, Herbert; Haas, Hubertus

    2013-01-10

    The filamentous fungus Acremonium chrysogenum is of enormous biotechnological importance as it represents the natural producer of the beta-lactam antibiotic cephalosporin C. However, a limitation in genetic tools, e.g. promoters for conditional gene expression, impedes genetic engineering of this fungus. Here we demonstrate that in A. chrysogenum iron starvation induces the production of the extracellular siderophores dimerumic acid, coprogen B, 2-N-methylcoprogen B and dimethylcoprogen as well as expression of the putative siderophore transporter gene, mir1. Moreover, we show that the promoter of mir1, mir1(P), is suitable for conditional expression of target genes in A. chrysogenum as shown by mir1(P)-driven and iron starvation-induced expression of genes encoding green fluorescence protein and phleomycin resistance. The obtained iron-starvation dependent phleomycin resistance indicates the potential use of this promoter for selection marker recycling. Together with easy scorable siderophore production, the co-regulation of mir1 expression and siderophore production facilitates the optimization of the inducing conditions of this expression system.

  6. A novel conditioning process for enhancing dewaterability of waste activated sludge by combination of zero-valent iron and persulfate.

    PubMed

    Zhou, Xu; Wang, Qilin; Jiang, Guangming; Liu, Peng; Yuan, Zhiguo

    2015-06-01

    Improvement of sludge dewaterability is crucial for reducing the costs of sludge disposal in wastewater treatment plants. This study presents a novel conditioning method for improving waste activated sludge dewaterability by combination of persulfate and zero-valent iron. The combination of zero-valent iron (0-30g/L) and persulfate (0-6g/L) under neutral pH substantially enhanced the sludge dewaterability due to the advanced oxidization reactions. The highest enhancement of sludge dewaterability was achieved at 4g persulfate/L and 15g zero-valent iron/L, with which the capillary suction time was reduced by over 50%. The release of soluble chemical oxygen demand during the conditioning process implied the decomposition of sludge structure and microorganisms, which facilitated the improvement of dewaterability due to the release of bound water that was included in sludge structure and microorganism. Economic analysis showed that the proposed conditioning process with persulfate and ZVI is more economically favorable for improving WAS dewaterability than classical Fenton reagent.

  7. A greenhouse trial to investigate the ameliorative properties of biosolids and plants on physicochemical conditions of iron ore tailings: Implications for an iron ore mine site remediation.

    PubMed

    Cele, Emmanuel Nkosinathi; Maboeta, Mark

    2016-01-01

    An iron ore mine site in Swaziland is currently (2015) in a derelict state as a consequence of past (1964-1988) and present (2011 - current) iron ore mining operations. In order to control problems associated with mine wastes, the Swaziland Water Services Corporation (SWSC) recently (2013) proposed the application of biosolids in sites degraded by mining operations. It is thought that this practice could generally improve soil conditions and enhance plant reestablishment. More importantly, the SWSC foresees this as a potential solution to the biosolids disposal problems. In order to investigate the effects of biosolids and plants in soil physicochemical conditions of iron mine soils, we conducted two plant growth trials. Trial 1 consisted of tailings that received biosolids and topsoil (TUSB mix) while in trial 2, tailings received biosolids only (TB mix). In the two trials, the application rates of 0 (control), 10, 25, 50, 75 and 100 t ha(-1) were used. After 30 days of equilibration, 25 seeds of Cynodon dactylon were sown in each pot and thinned to 10 plants after 4 weeks. Plants were watered twice weekly and remained under greenhouse conditions for 12 weeks, subsequent to which soils were subjected to chemical analysis. According to the results obtained, there were significant improvements in soil parameters related to fertility such as organic matter (OM), water holding capacity (WHC), cation exchange capacity (CEC), ammonium [Formula: see text] , magnesium (Mg(2+)), calcium (Ca(2+)) and phosphorus ( [Formula: see text] ). With regard to heavy metals, biosolids led to significant increases in soil total concentrations of Cu, Zn, Cd, Hg and Pb. The higher concentrations of Zn and Cu in treated tailings compared to undisturbed adjacent soils are a cause for concern because in the field, this might work against the broader objectives of mine soil remediation, which include the recolonization of reclaimed sites by soil-dwelling organisms. Therefore, while

  8. Comparison Study of Oral Iron Preparations Using a Human Intestinal Model

    PubMed Central

    Zariwala, Mohammed Gulrez; Somavarapu, Satyanarayana; Farnaud, Sebastien; Renshaw, Derek

    2013-01-01

    Iron deficiency and related iron deficiency anaemia (IDA) are the most prevalent nutritional disorders worldwide. The standard treatment involves supplementation with solid or liquid iron supplement preparations, usually based on a ferrous salt such as ferrous sulphate, ferrous fumarate, or ferrous gluconate. In the present study, we compared iron uptake and absorption from various solid and liquid iron supplement preparations currently available in the United Kingdom using the well-characterised human epithelial adenocarcinoma cell line Caco-2. Intracellular ferritin protein formation by the Caco-2 cell was considered an indicator of cellular iron uptake and absorption. We investigated the effects of formulation ingredients at a defined pH on iron uptake and absorption, and designed a novel two-stage dissolution-absorption protocol that mimicked physiological conditions. Our experiments revealed wide variations in the rate of dissolution between the various solid iron preparations. Conventional-release ferrous iron tablets dissolved rapidly (48 ± 4 mins to 64 ± 4 mins), whereas modified-released tablets and capsules took significantly longer to undergo complete dissolution (274 ± 8 to 256 ± 8 mins). Among the solid iron preparations, ferrous sulphate conventional-release tablets demonstrated the highest iron absorption, whereas modified-release ferrous preparations demonstrated uniformly low iron absorption, as compared to the control (P < 0.05). Taken together, our results demonstrate that there are wide-ranging variations in dissolution times and iron uptake from oral iron preparations, with the physical characteristics of the preparation as well as the form of iron playing a key role. PMID:24482777

  9. Uranium Immobilization in an Iron-Rich Rhizosphere of a Native Wetland Plant from the Savannah River Site under Reducing Conditions

    EPA Science Inventory

    The hypothesis of this study was that iron plaque formed on the roots of wetland plants and their rhizospheres create environmental conditions favorable for iron reducing bacteria that promote the in situ immobilization of uranium. Greenhouse microcosm studies were conducted usin...

  10. Iron Supplementation in Suckling Piglets: How to Correct Iron Deficiency Anemia without Affecting Plasma Hepcidin Levels

    PubMed Central

    Starzyński, Rafał R.; Laarakkers, Coby M. M.; Tjalsma, Harold; Swinkels, Dorine W.; Pieszka, Marek; Styś, Agnieszka; Mickiewicz, Michał; Lipiński, Paweł

    2013-01-01

    The aim of the study was to establish an optimized protocol of iron dextran administration to pig neonates, which better meets the iron demand for erythropoiesis. Here, we monitored development of red blood cell indices, plasma iron parameters during a 28-day period after birth (till the weaning), following intramuscular administration of different concentrations of iron dextran to suckling piglets. To better assess the iron status we developed a novel mass spectrometry assay to quantify pig plasma levels of the iron-regulatory peptide hormone hepcidin-25. This hormone is predominantly secreted by the liver and acts as a negative regulator of iron absorption and reutilization. The routinely used protocol with high amount of iron resulted in the recovery of piglets from iron deficiency but also in strongly elevated plasma hepcidin-25 levels. A similar protocol with reduced amounts of iron improved hematological status of piglets to the same level while plasma hepcidin-25 levels remained low. These data show that plasma hepcidin-25 levels can guide optimal dosing of iron treatment and pave the way for mixed supplementation of piglets starting with intramuscular injection of iron dextran followed by dietary supplementation, which could be efficient under condition of very low plasma hepcidin-25 level. PMID:23737963

  11. Iron supplementation in suckling piglets: how to correct iron deficiency anemia without affecting plasma hepcidin levels.

    PubMed

    Starzyński, Rafał R; Laarakkers, Coby M M; Tjalsma, Harold; Swinkels, Dorine W; Pieszka, Marek; Styś, Agnieszka; Mickiewicz, Michał; Lipiński, Paweł

    2013-01-01

    The aim of the study was to establish an optimized protocol of iron dextran administration to pig neonates, which better meets the iron demand for erythropoiesis. Here, we monitored development of red blood cell indices, plasma iron parameters during a 28-day period after birth (till the weaning), following intramuscular administration of different concentrations of iron dextran to suckling piglets. To better assess the iron status we developed a novel mass spectrometry assay to quantify pig plasma levels of the iron-regulatory peptide hormone hepcidin-25. This hormone is predominantly secreted by the liver and acts as a negative regulator of iron absorption and reutilization. The routinely used protocol with high amount of iron resulted in the recovery of piglets from iron deficiency but also in strongly elevated plasma hepcidin-25 levels. A similar protocol with reduced amounts of iron improved hematological status of piglets to the same level while plasma hepcidin-25 levels remained low. These data show that plasma hepcidin-25 levels can guide optimal dosing of iron treatment and pave the way for mixed supplementation of piglets starting with intramuscular injection of iron dextran followed by dietary supplementation, which could be efficient under condition of very low plasma hepcidin-25 level.

  12. Oxidative stress induced by pure and iron-doped amorphous silica nanoparticles in subtoxic conditions.

    PubMed

    Napierska, Dorota; Rabolli, Virginie; Thomassen, Leen C J; Dinsdale, David; Princen, Catherine; Gonzalez, Laetitia; Poels, Katrien L C; Kirsch-Volders, Micheline; Lison, Dominique; Martens, Johan A; Hoet, Peter H

    2012-04-16

    Amorphous silica nanoparticles (SiO₂-NPs) have found broad applications in industry and are currently intensively studied for potential uses in medical and biomedical fields. Several studies have reported cytotoxic and inflammatory responses induced by SiO₂-NPs in different cell types. The present study was designed to examine the association of oxidative stress markers with SiO₂-NP induced cytotoxicity in human endothelial cells. We used pure monodisperse amorphous silica nanoparticles of two sizes (16 and 60 nm; S16 and S60) and a positive control, iron-doped nanosilica (16 nm; SFe), to study the generation of hydroxyl radicals (HO·) in cellular-free conditions and oxidative stress in cellular systems. We investigated whether SiO₂-NPs could influence intracellular reduced glutathione (GSH) and oxidized glutathione (GSSG) levels, increase lipid peroxidation (malondialdehyde (MDA) and 4-hydroxyalkenal (HAE) concentrations), and up-regulate heme oxygenase-1 (HO-1) mRNA expression in the studied cells. None of the particles, except SFe, produced ROS in cell-free systems. We found significant modifications for all parameters in cells treated with SFe nanoparticles. At cytotoxic doses of S16 (40-50 μg/mL), we detected weak alterations of intracellular glutathione (4 h) and a marked induction of HO-1 mRNA (6 h). Cytotoxic doses of S60 elicited similar responses. Preincubation of cells being exposed to SiO₂-NPs with an antioxidant (5 mM N-acetylcysteine, NAC) significantly reduced the cytotoxic activity of S16 and SFe (when exposed up to 25 and 50 μg/mL, respectively) but did not protect cells treated with S60. Preincubation with NAC significantly reduced HO-1 mRNA expression in cells treated with SFe but did not have any effect on HO-1 mRNA level in cell exposed to S16 and S60. Our study demonstrates that the chemical composition of the silica nanoparticles is a dominant factor in inducing oxidative stress.

  13. The power absorption and the penetration depth of electromagnetic radiation in lead telluride under cyclotron resonance conditions

    NASA Astrophysics Data System (ADS)

    Özalp, S.; Güngör, A.

    1999-10-01

    Cyclotron resonance absorption in n- and p-type PbTe was observed by Nii and was analysed under classical skin effect conditions. When the values of DC magnetic field corresponding to peaks are plotted against the field directions, a close fit is obtained between the calculated and observed results based on the assumption of a <1 1 1> ellipsoids of revolution model for the both conduction and valance band extrema. From the best fit mt=0.024 m0 and 0.03 m0 for the transverse effective masses and K= ml/ mt=9.8 and 12.2 for the anisotropic mass rations are obtained for the conduction and valance band, respectively. The observed absorption curve shows weak structures at low magnetic field. They are supposed to be due to second harmonics of Azbel'-Kaner cyclotron resonance. However, it turns out to be unnecessary to introduce other bands to explain the experimental results. The applicability of the classical magneto-optical theory is examined by calculating the power absorption coefficient and penetration depth as a function of DC magnetic field.

  14. Highly Ionized Iron Absorption Lines from Outflowing Gases in the X-ray Spectrum of NGC 1365

    NASA Technical Reports Server (NTRS)

    Risaliti, G.; Bianchi, S.; Matt, G.; Baldi, A.; Elvis, M.; Fabbiano, G.; Zezas, A.

    2006-01-01

    We present the discovery of four absorption lines in the X-ray spectrum of the Seyfert galaxy NGC 1365, at energies between 6.7 and 8.3 keV. The lines are detected with high statistical confidence (from >20 sigma for the strongest to -4 sigma for the weakest) in two XMM-Newton observations 60 ks long. We also detect the same lines, with a lower signal-to-noise ratio (but still >2 sigma for each line), in two previous shorter (-10 ks) XMM-Newton observations. The spectral analysis identifies these features as Fe XXV and Fe XXVI Kalpha and Kbeta lines, outflowing with velocities varying between -1000 and -5000 km/s among the observations. These are the highest quality detections of such lines so far. The high equivalent widths [EW (Kalpha) approximately 100 eV] and the Kalpha/Kbeta ratios imply that the lines are due to absorption of the AGN continuum by a highly ionized gas with column density NH-5?1023 cm(exp -2) at a distance of -(50-100)RS from the continuum source.

  15. In situ synthesis of hydroxyapatite nanocomposites using iron oxide nanofluids at ambient conditions.

    PubMed

    Sheikh, Lubna; Mahto, Neha; Nayar, Suprabha

    2015-01-01

    This paper describes a simple method for the room temperature synthesis of magnetite/hydroxyapatite composite nanocomposites using ferrofluids. The in situ synthesis of magnetic-hydroxyapatite results in a homogenous distribution of the two phases as seen both in transmission electron micrographs and assembled to a micron range in the confocal micrographs. The selected area diffraction pattern analysis shows the presence of both phases of iron oxide and hydroxyapatite. To the dialyzed ferrofluid, the constituents of hydroxyapatite synthesis was added, the presence of the superparamagnetic iron oxide particles imparts directionality to the hydroxyapatite crystal growth. Electron probe microanalysis confirms the co-existence of both iron and calcium atoms. Vibrating Sample magnetometer data shows magnetization three times more than the parent ferrofluid, the local concentration of iron oxide nanoparticles affects the strength of dipolar interparticle interactions changing the energy barrier for determining the collective magnetic behavior of the sample. The limitations inherent to the use of external magnetic fields which can be circumvented by the introduction of internal magnets located in the proximity of the target by a minimal surgery or by using a superparamagnetic scaffold under the influence of externally applied magnetic field inspires us to increase the magnetization of our samples. The composite in addition shows anti-bacterial properties against the two gram (-ve) bacteria tested. This work is significant as magnetite-hydroxyapatite composites are attracting a lot of attention as adsorbents, catalysts, hyperthermia agents and even as regenerative medicine.

  16. Does complex absorption behavior leading to conditioning and damage in KDP/DKDP reflect the electronic structure of initiators?

    SciTech Connect

    Feit, M D; DeMange, P P; Negres, R A; Rubenchik, A M; Demos, S G

    2007-10-24

    Currently, most of our thinking about the defects responsible for initiating laser damage considers them as featureless absorbers. However, an increasing body of evidence, particularly involving multi-wavelength irradiation, suggests electronic structure of damage initiators is important in determining both initiation and conditioning behaviors in KDP. The effective absorption coefficient of energy under multi-wavelength irradiation cannot be accounted for by a structureless absorber, but is consistent with an initiator with a multi-level structure. We outline the evidence and assess the ability of such a simple multi-level model to explain these and other experimentally observed behaviors.

  17. A comparison of simultaneous plasma, atomic absorption, and iron colorimetric determinations of major and trace constituents in acid mine waters

    USGS Publications Warehouse

    Ball, J.W.; Nordstrom, D.K.

    1994-01-01

    Sixty-three water samples collected during June to October 1982 from the Leviathan/Bryant Creek drainage basin were originally analyzed by simultaneous multielement direct-current plasma (DCP) atomic-emission spectrometry, flame atomic-absorption spectrometry, graphite-furnace atomic-absorption spectrometry (GFAAS) (thallium only), ultraviolet-visible spectrometry, and hydride-generation atomic-absorption spectrometry.Determinations were made for the following metallic and semi-metallic constituents: AI, As, B, Ba, Be, Bi, Cd, Ca, Cr, Co, Cu, Fe(11), Fe(total), Li, Pb, Mg, Mn, Mo, Ni, K, Sb, Se, Si, Na, Sr, TI, V, and Zn. These samples were re-analyzed later by simultaneous multielement inductively coupled plasma (ICP) atomic-emission spectrometry and Zeeman-corrected GFAAS to determine the concentrations of many of the same constituents with improved accuracy, precision, and sensitivity. The result of this analysis has been the generation of comparative concentration values for a significant subset of the solute constituents. Many of the more recently determined values replace less-than-detection values for the trace metals; others constitute duplicate analyses for the major constituents. The multiple determinations have yielded a more complete, accurate, and precise set of analytical data. They also have resulted in an opportunity to compare the performance of the plasma-emission instruments operated in their respective simultaneous multielement modes. Flame atomic-absorption spectrometry was judged best for Na and K and hydride-generation atomic-absorption spectrometry was judged best for As because of their lower detection limit and relative freedom from interelement spectral effects. Colorimetric determination using ferrozine as the color agent was judged most accurate, precise, and sensitive for Fe. Cadmium, lead, and vanadium concentrations were too low in this set of samples to enable a determination of whether ICP or DCP is a more suitable technique. Of

  18. Oxidation of dissolved iron under warmer, wetter conditions on Mars: Transitions to present-day arid environments

    NASA Technical Reports Server (NTRS)

    Burns, R. G.

    1993-01-01

    The copious deposits of ferric-iron assemblages littering the surface of bright regions of Mars indicate that efficient oxidative weathering reactions have taken place during the evolution of the planet. Because the kinetics of atmosphere-surface (gas-solid) reactions are considerably slower than chemical weathering reactions involving an aqueous medium, most of the oxidation products now present in the martian regolith probably formed when groundwater flowed near the surface. This paper examines how chemical weathering reactions were effected by climatic variations when warm, wet environments became arid on Mars. Analogies are drawn with hydrogeochemical and weathering environments on the Australian continent where present-day oxidation of iron is occurring in acidic ground water under arid conditions.

  19. The evaluation of iron-base hardfacing alloys on gate valves after cycling under simulated PWR conditions for one year

    SciTech Connect

    Murphy, E.V.; Inglis, I.; Ocken, H.

    1992-12-31

    Gate valves hardfaced with iron-base alloys were exposed for about one year to simulated PWR conditions. The hardfacing alloys tested were EB 5183, EVERIT 50, NOREM 01 and NOREM 04. A gate valve with Satellite 6 was included in the test program as a control standard. During the test period the valves were opened and closed 2000 times. The performance of the valves was assessed by periodic leak tests and visual and profilometric characterisation of sealing surfaces. At the end of the test program, the seats and discs were destructively examined. The various examinations indicated all the iron-base alloys were superior to Satellite 6. Based on the results of hot leakage tests, one valve with EB 5183 and the valve with NOREM 04 were the best performers.

  20. Effects of Surfactants and Synthetic Conditions on the Sizes and Self-Assembly of Monodisperse Iron Oxide Nanoparticles

    SciTech Connect

    Teng, X.; Yang, H.

    2004-02-17

    (B204)Monodisperse iron oxide nanoparticles made from the thermal decomposition of iron carbonyl in octyl ether in the presence of oleic and stearic acids have been examined under various reaction conditions. Monodisperse particles with diameters of 3, 5, 10, 16 and 25 nm have been made. Ostwald ripening could be the key reason for making monodisperse nanoparticles with diameters of up to 25 nm, above the largest sizes that have been reported so far for this class of materials. When stearic acid was used as surfactant, the reaction mixtures can reflux at a lower temperature than the reaction using oleic acid, and monodisperse 3 nm Fe2O3 particles can be made. By controlling the temperatures during the drop casting, different superstructures and superlattices can be created. The nanoparticles and their assembly have been characterized by transmission electron microscopy, electron diffraction, powder X-ray diffraction, and X-ray photoemission spectroscopy.

  1. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1989-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. Work performed has shown that laboratory measurements of the millimeter-wave opacity of ammonia between 7.5 mm and 9.3 mm and also at the 3.2 mm wavelength require a different lineshape to be used in the theoretical prediction for millimeter-wave ammonia opacity than was previously used. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  2. Efficacy and safety of iron-chelation therapy with deferoxamine, deferiprone, and deferasirox for the treatment of iron-loaded patients with non-transfusion-dependent thalassemia syndromes

    PubMed Central

    Kontoghiorghe, Christina N; Kontoghiorghes, George J

    2016-01-01

    The prevalence rate of thalassemia, which is endemic in Southeast Asia, the Middle East, and the Mediterranean, exceeds 100,000 live births per year. There are many genetic variants in thalassemia with different pathological severity, ranging from a mild and asymptomatic anemia to life-threatening clinical effects, requiring lifelong treatment, such as regular transfusions in thalassemia major (TM). Some of the thalassemias are non-transfusion-dependent, including many thalassemia intermedia (TI) variants, where iron overload is caused by chronic increase in iron absorption due to ineffective erythropoiesis. Many TI patients receive occasional transfusions. The rate of iron overloading in TI is much slower in comparison to TM patients. Iron toxicity in TI is usually manifested by the age of 30–40 years, and in TM by the age of 10 years. Subcutaneous deferoxamine (DFO), oral deferiprone (L1), and DFO–L1 combinations have been effectively used for more than 20 years for the treatment of iron overload in TM and TI patients, causing a significant reduction in morbidity and mortality. Selected protocols using DFO, L1, and their combination can be designed for personalized chelation therapy in TI, which can effectively and safely remove all the excess toxic iron and prevent cardiac, liver, and other organ damage. Both L1 and DF could also prevent iron absorption. The new oral chelator deferasirox (DFX) increases iron excretion and decreases liver iron in TM and TI. There are drawbacks in the use of DFX in TI, such as limitations related to dose, toxicity, and cost, iron load of the patients, and ineffective removal of excess iron from the heart. Furthermore, DFX appears to increase iron and other toxic metal absorption. Future treatments of TI and related iron-loading conditions could involve the use of the iron-chelating drugs and other drug combinations not only for increasing iron excretion but also for preventing iron absorption. PMID:26893541

  3. On the enzymatic activity of catalase: an iron L-edge X-ray absorption study of the active centre.

    PubMed

    Bergmann, Nora; Bonhommeau, Sébastien; Lange, Kathrin M; Greil, Stefanie M; Eisebitt, Stefan; de Groot, Frank; Chergui, Majed; Aziz, Emad F

    2010-05-14

    Catalase and methaemoglobin have very similar haem groups, which are both ferric, yet catalase decomposes hydrogen peroxide to water and oxygen very efficiently, while methaemoglobin does not. Structural studies have attributed this behaviour to their different distal environments. Here we present Fe L(2,3)-edge X-ray absorption spectra of these proteins in physiological solutions, which reveal clear differences in their electronic structures, in that pi back-donation of the Fe atom occurs in catalase, which confers on it a partial ferryl (Fe(4+)) character, while this is not the case in methaemoglobin. The origin of the Fe(4+) character stems from the proximal tyrosine residue. We also find that both systems are in a high spin state. Temperature effects influence the spectra of catalase only weakly, in agreement with previous studies of its chemical activity. We conclude that the high activity of catalase is not only determined by its distal environment but also by its partial ferryl character.

  4. Iron deficiency up-regulates iron absorption from ferrous sulphate but not ferric pyrophosphate and consequently food fortification with ferrous sulphate has relatively greater efficacy in iron-deficient individuals.

    PubMed

    Zimmermann, Michael B; Biebinger, Ralf; Egli, Ines; Zeder, Christophe; Hurrell, Richard F

    2011-04-01

    Fe absorption from water-soluble forms of Fe is inversely proportional to Fe status in humans. Whether this is true for poorly soluble Fe compounds is uncertain. Our objectives were therefore (1) to compare the up-regulation of Fe absorption at low Fe status from ferrous sulphate (FS) and ferric pyrophosphate (FPP) and (2) to compare the efficacy of FS with FPP in a fortification trial to increase body Fe stores in Fe-deficient children v. Fe-sufficient children. Using stable isotopes in test meals in young women (n 49) selected for low and high Fe status, we compared the absorption of FPP with FS. We analysed data from previous efficacy trials in children (n 258) to determine whether Fe status at baseline predicted response to FS v. FPP as salt fortificants. Plasma ferritin was a strong negative predictor of Fe bioavailability from FS (P < 0·0001) but not from FPP. In the efficacy trials, body Fe at baseline was a negative predictor of the change in body Fe for both FPP and FS, but the effect was significantly greater with FS (P < 0·01). Because Fe deficiency up-regulates Fe absorption from FS but not from FPP, food fortification with FS may have relatively greater impact in Fe-deficient children. Thus, more soluble Fe compounds not only demonstrate better overall absorption and can be used at lower fortification levels, but they also have the added advantage that, because their absorption is up-regulated in Fe deficiency, they innately 'target' Fe-deficient individuals in a population.

  5. Hard X-ray photoelectron and X-ray absorption spectroscopy characterization of oxidized surfaces of iron sulfides

    NASA Astrophysics Data System (ADS)

    Mikhlin, Yuri; Tomashevich, Yevgeny; Vorobyev, Sergey; Saikova, Svetlana; Romanchenko, Alexander; Félix, Roberto

    2016-11-01

    Hard X-ray photoelectron spectroscopy (HAXPES) using an excitation energy range of 2 keV to 6 keV in combination with Fe K- and S K-edge XANES, measured simultaneously in total electron (TEY) and partial fluorescence yield (PFY) modes, have been applied to study near-surface regions of natural polycrystalline pyrite FeS2 and pyrrhotite Fe1-xS before and after etching treatments in an acidic ferric chloride solution. It was found that the following near-surface regions are formed owing to the preferential release of iron from oxidized metal sulfide lattices: (i) a thin, no more than 1-4 nm in depth, outer layer containing polysulfide species, (ii) a layer exhibiting less pronounced stoichiometry deviations and low, if any, concentrations of polysulfide, the composition and dimensions of which vary for pyrite and pyrrhotite and depend on the chemical treatment, and (iii) an extended almost stoichiometric underlayer yielding modified TEY XANES spectra, probably, due to a higher content of defects. We suggest that the extended layered structure should heavily affect the near-surface electronic properties, and processes involving the surface and interfacial charge transfer.

  6. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - II: Experimental verification

    NASA Astrophysics Data System (ADS)

    Hausmaninger, Thomas; Silander, Isak; Ma, Weiguang; Axner, Ove

    2016-01-01

    Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is normally described by an expression, here termed the conventional (CONV) description, that is restricted to the conventional cavity-limited weak absorption condition (CCLWA), i.e. when the single pass absorbance is significantly smaller than the empty cavity losses, i.e. when α0 L < < π / F. To describe NICE-OHMS signals beyond this limit two simplified extended descriptions (termed the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT), which are assumed to be valid under the relaxed cavity-limited weak absorption condition (RCLWA), i.e. when α0 L < π / F, and a full description (denoted FULL), presumed to be valid also when the α0 L < π / F condition does not hold, have recently been derived in an accompanying work (Ma W, et al. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - I. Theoretical Description. J Quant Spectrosc Radiat Transfer, 2015, http://dx.doi.org/10.1016/j.jqsrt.2015.09.007). The present work constitutes an experimental verification and assessment of the validity of these, performed in the Doppler limit for a set of Fα0 L / π values (up to 3.5); it is shown under which conditions the various descriptions are valid. It is concluded that for samples with Fα0 L / π up to 0.01, all descriptions replicate the data well. It is shown that the CONV description is adequate and provides accurate assessments of the signal strength (and thereby the analyte concentration) up to Fα0 L / π of around 0.1, while the ELET is accurate for Fα0 L / π up to around 0.3. The ELFT description mimics the Db NICE-OHMS signal well for Fα0 L / π up to around unity, while the FULL description is adequate for all Fα0 L / π values investigated. Access to these descriptions both increases considerably the dynamic range of the technique and

  7. Applicability of DLVO Approach to Predict Trends in Iron Oxide Colloid Mobility Under Various Physical And Chemical Soil Conditions

    NASA Astrophysics Data System (ADS)

    Florian Carstens, Jannis; Bachmann, Jörg; Neuweiler, Insa

    2014-05-01

    In soil and groundwater, highly mobile iron oxide colloids can act as "shuttles" for transport of adsorbed contaminants such as heavy metals and radionuclides. Artificial iron oxide colloids are injected into polluted porous media to accelerate bacterial degradation of pollutants in the context of bioremediation purposes. The mobility of iron oxide colloids is strongly affected by the hydraulic, physical and chemical conditions of the pore space, the solid particle surface properties, the fluid phase, and the colloids themselves. Most pioneering studies focused on iron oxide colloid transport and retention in simplified model systems. The aim of this study is to investigate iron oxide colloid mobility under more complex, soil-typical conditions that have as yet only been applied for model microspheres, i.e. functionalized latex colloids. Among these conditions is the pivotal impact of organic matter, either dissolved or adsorbed onto solid particles, modifying wettability properties. Of particular importance was to determine if effective chemical surface parameters derived from contact angle and zeta potential measurements can be used as a tool to predict general tendencies for iron oxide colloid mobility in porous media. In column breakthrough experiments, goethite colloids (particle size: 200-900 nm) were percolated through quartz sand (grain size: 100-300 µm) at pH 5. The impact of a multitude of conditions on colloid mobility was determined: dissolved organic matter (DOM) concentration, ionic strength, flow velocity, flow interruption, partial saturation, and drying with subsequent re-wetting. The solid matrix consisted of either clean sand, organic matter-coated sand, goethite-coated sand, or sand hydrophobized with dichlorodimethylsilane. Additionally, contact angles and zeta potentials of the materials applied in the column experiments were measured. By means of these surface parameters, traditional DLVO interaction energies based on zeta potential as well

  8. Effects of electron correlations on transport properties of iron at Earth's core conditions.

    PubMed

    Zhang, Peng; Cohen, R E; Haule, K

    2015-01-29

    Earth's magnetic field has been thought to arise from thermal convection of molten iron alloy in the outer core, but recent density functional theory calculations have suggested that the conductivity of iron is too high to support thermal convection, resulting in the investigation of chemically driven convection. These calculations for resistivity were based on electron-phonon scattering. Here we apply self-consistent density functional theory plus dynamical mean-field theory (DFT + DMFT) to iron and find that at high temperatures electron-electron scattering is comparable to the electron-phonon scattering, bringing theory into agreement with experiments and solving the transport problem in Earth's core. The conventional thermal dynamo picture is safe. We find that electron-electron scattering of d electrons is important at high temperatures in transition metals, in contrast to textbook analyses since Mott, and that 4s electron contributions to transport are negligible, in contrast to numerous models used for over fifty years. The DFT+DMFT method should be applicable to other high-temperature systems where electron correlations are important.

  9. Status of neurocognitive and oxidative stress conditions in iron-steel workers.

    PubMed

    Malekirad, Ali Akbar; Mirabdollahi, Mansuoreh; Pilehvarian, Ali Asghar; Nassajpour, Ali Reza; Abdollahi, Mohammad

    2015-07-01

    The aim of this study was to determine oxidative stress status as well as ferrous (Fe) and Copper (Cu) levels in blood, neurocognitive impairment, and clinical markers in iron-steel workers. A comparative cross-sectional analysis was performed in 50 iron-steel workers who have been in contact with Fe and Cu in comparison with a control group containing 50 healthy subjects in the same age group and sex. Blood levels of lipid peroxidation, total antioxidant capacity, Fe, and Cu along with neurocognitive impairment were measured in workers and controls. Clinical examination was accomplished to record any abnormal sign or symptoms. Comparing with controls, the workers showed higher blood levels of lipid peroxidation and Cu and also a lower total antioxidant capacity. There was a positive correlation between work history and interstitial lung disease that strengths the presumption to progress to chronic obstructive lung disease in future. The results indicate that exposure to a combination of Fe and Cu in iron-steel workers induces oxidative stress. Especially, in the present case, toxic effect of Cu has been more than positive effects of Fe, but the combined exposure resulted in no such critical toxicity.

  10. Effect of Experimental Conditions on Cementite Formation During Reduction of Iron Ore Pellets

    NASA Astrophysics Data System (ADS)

    Kazemi, Mania; Sichen, Du

    2016-12-01

    Experiments have been carried out to study the effect of temperature, gas composition, residence time, and type of iron ore pellets on formation of cementite during gaseous reduction of hematite. Industrial iron ore pellets have been reduced isothermally in a gas mixture with H2 and CO as main components. The presence of Fe3C in the partially reduced pellets shows that reduction and cementite formation take place at the same time. The maximum content of cementite is identified in the samples reduced by H2-CO at 1123 K (850 °C). The decrease in the carbide content due to addition of 1 pct CO2 to the initial gas mixture reveals the major influence of carbon potential in the gas atmosphere. Further increase of CO2 content increases the Fe3C. The variations of the amount of cementite with the CO2 content suggest that both the thermodynamics and kinetics of cementite formation are affected by the gas composition. Cementite decomposes to graphite and iron particles in reducing and inert atmospheres as the residence time of pellets at high temperature is increased above 60 minutes.

  11. Nutrient absorption.

    PubMed

    Rubin, Deborah C

    2004-03-01

    Our understanding of nutrient absorption continues to grow, from the development of unique animal models and from studies in which cutting-edge molecular and cellular biologic approaches have been used to analyze the structure and function of relevant molecules. Studies of the molecular genetics of inherited disorders have also provided many new insights into these processes. A major advance in lipid absorption has been the cloning and characterization of several intestinal acyl CoA:monoacylglycerol acyltransferases; these may provide new targets for antiobesity drug therapy. Studies of intestinal cholesterol absorption and reverse cholesterol transport have encouraged the development of novel potential treatments for hyperlipidemia. Observations in genetically modified mice and in humans with mutations in glucose transporter 2 suggest the importance of a separate microsomal membrane transport pathway for glucose transport. The study of iron metabolism has advanced greatly with the identification of the hemochromatosis gene and the continued examination of the genetic regulation of iron absorptive pathways. Several human thiamine transporters have been identified, and their specific roles in different tissues are being explored.

  12. Simulations of iron K pre-edge X-ray absorption spectra using the restricted active space method.

    PubMed

    Guo, Meiyuan; Sørensen, Lasse Kragh; Delcey, Mickaël G; Pinjari, Rahul V; Lundberg, Marcus

    2016-01-28

    The intensities and relative energies of metal K pre-edge features are sensitive to both geometric and electronic structures. With the possibility to collect high-resolution spectral data it is important to find theoretical methods that include all important spectral effects: ligand-field splitting, multiplet structures, 3d-4p orbital hybridization, and charge-transfer excitations. Here the restricted active space (RAS) method is used for the first time to calculate metal K pre-edge spectra of open-shell systems, and its performance is tested against on six iron complexes: [FeCl6](n-), [FeCl4](n-), and [Fe(CN)6](n-) in ferrous and ferric oxidation states. The method gives good descriptions of the spectral shapes for all six systems. The mean absolute deviation for the relative energies of different peaks is only 0.1 eV. For the two systems that lack centrosymmetry [FeCl4](2-/1-), the ratios between dipole and quadrupole intensity contributions are reproduced with an error of 10%, which leads to good descriptions of the integrated pre-edge intensities. To gain further chemical insight, the origins of the pre-edge features have been analyzed with a chemically intuitive molecular orbital picture that serves as a bridge between the spectra and the electronic structures. The pre-edges contain information about both ligand-field strengths and orbital covalencies, which can be understood by analyzing the RAS wavefunction. The RAS method can thus be used to predict and rationalize the effects of changes in both the oxidation state and ligand environment in a number of hard X-ray studies of small and medium-sized molecular systems.

  13. Effect of molybdenum, vanadium, boron on mechanical properties of high chromium white cast iron in as-cast condition

    NASA Astrophysics Data System (ADS)

    Nurjaman, F.; Sumardi, S.; Shofi, A.; Aryati, M.; Suharno, B.

    2016-02-01

    In this experiment, the effect of the addition carbide forming elements on high chromium white cast iron, such as molybdenum, vanadium and boron on its mechanical properties and microstructure was investigated. The high chromium white cast iron was produced by casting process and formed in 50 mm size of grinding balls with several compositions. Characterization of these grinding balls was conducted by using some testing methods, such as: chemical and microstructure analysis, hardness, and impact test. From the results, the addition of molybdenum, vanadium, and boron on high chromium white cast iron provided a significant improvement on its hardness, but reduced its toughness. Molybdenum induced fully austenitic matrix and Mo2C formation among eutectic M7C3 carbide. Vanadium was dissolved in the matrix and carbide. While boron was played a role to form fine eutectic carbide. Grinding balls with 1.89 C-13.1 Cr-1.32 Mo-1.36 V-0.00051 B in as-cast condition had the highest hardness, which was caused by finer structure of eutectic carbide, needle like structure (upper bainite) matrix, and martensite on its carbide boundary.

  14. The impact of engineered cobalt, iron, nickel and silver nanoparticles on soil bacterial diversity under field conditions

    NASA Astrophysics Data System (ADS)

    Shah, Vishal; Collins, Daniel; Walker, Virginia K.; Shah, Shreya

    2014-01-01

    Our understanding of how engineered nanoparticles (NPs) migrate through soil and affect microbial communities is scarce. In the current study we examined how metal NPs, including those from the iron triad (iron, cobalt and nickel), moved through pots of soil maintained under winter field conditions for 50 days, when mesophilic bacteria may not be dividing. Based on total metal analysis, cobalt and nickel were localized in the top layer of soil, even after exposure to high precipitation and freeze-thaw cycles. In contrast, a bimodal distribution of silver was observed. Due to high endogenous levels of iron, the migration pattern of these NPs could not be determined. Pyrosequence analysis of the bacterial communities revealed that there was no significant engineered NP-mediated decline in microbial richness. However, analysis of individual genera showed that Sphingomonas and Lysobacter were represented by fewer sequences in horizons containing elevated metal levels whereas there was an increase in the numbers of Flavobacterium and Niastella. Collectively, the results indicate that along with the differential migration behavior of NPs in the soil matrix, their impact on soil bacterial diversity appears to be dependent on environmental parameters.

  15. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M. Kothari; Gerard T. Pittard

    2004-04-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints that connect pipe sections together tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast-iron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1--Program Management and Task 2--were completed in prior quarters while Task 3--Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves has progressed to installing prototype sleeves in cast iron test pipe segments. Efforts in this quarter continued to focus on Tasks 4--8, with significant progress made in each. Task 4 (Design, Fabricate and Test Patch Setting Robotic Train) progressed to the design of the control electronics and pneumatic system to inflate the bladder robotic patch setting module. Task 5 (Design & Fabricate Pipe-Wall Cleaning Robot Train with Pan/Zoom/Tilt Camera) continued with additional in-pipe testing required to

  16. Vibrational, X-ray absorption, and Mössbauer spectra of sulfate minerals from the weathered massive sulfide deposit at Iron Mountain, California

    USGS Publications Warehouse

    Majzlan, Juraj; Alpers, Charles N.; Bender Koch, Christian; McCleskey, R. Blaine; Myneni, Satish B.C.; Neil, John M.

    2011-01-01

    The Iron Mountain Mine Superfund site in California is a prime example of an acid mine drainage (AMD) system with well developed assemblages of sulfate minerals typical for such settings. Here we present and discuss the vibrational (infrared), X-ray absorption, and M??ssbauer spectra of a number of these phases, augmented by spectra of a few synthetic sulfates related to the AMD phases. The minerals and related phases studied in this work are (in order of increasing Fe2O3/FeO): szomolnokite, rozenite, siderotil, halotrichite, r??merite, voltaite, copiapite, monoclinic Fe2(SO4)3, Fe2(SO4)3??5H2O, kornelite, coquimbite, Fe(SO4)(OH), jarosite and rhomboclase. Fourier transform infrared spectra in the region 750-4000cm-1 are presented for all studied phases. Position of the FTIR bands is discussed in terms of the vibrations of sulfate ions, hydroxyl groups, and water molecules. Sulfur K-edge X-ray absorption near-edge structure (XANES) spectra were collected for selected samples. The feature of greatest interest is a series of weak pre-edge peaks whose position is determined by the number of bridging oxygen atoms between Fe3+ octahedra and sulfate tetrahedra. M??ssbauer spectra of selected samples were obtained at room temperature and 80K for ferric minerals jarosite and rhomboclase and mixed ferric-ferrous minerals r??merite, voltaite, and copiapite. Values of Fe2+/[Fe2++Fe3+] determined by M??ssbauer spectroscopy agree well with those determined by wet chemical analysis. The data presented here can be used as standards in spectroscopic work where spectra of well-characterized compounds are required to identify complex mixtures of minerals and related phases. ?? 2011 Elsevier B.V.

  17. Vibrational, X-ray absorption, and Mössbauer spectra of sulfate minerals from the weathered massive sulfide deposit at Iron Mountain, California

    USGS Publications Warehouse

    Majzlan, Juraj; Alpers, Charles N.; Bender Koch, Christian; McCleskey, R. Blaine; Myneni, Satish B.C.; Neil, John M.

    2014-01-01

    The Iron Mountain Mine Superfund site in California is a prime example of an acid mine drainage (AMD) system with well developed assemblages of sulfate minerals typical for such settings. Here we present and discuss the vibrational (infrared), X-ray absorption, and Mössbauer spectra of a number of these phases, augmented by spectra of a few synthetic sulfates related to the AMD phases. The minerals and related phases studied in this work are (in order of increasing Fe2O3/FeO): szomolnokite, rozenite, siderotil, halotrichite, römerite, voltaite, copiapite, monoclinic Fe2(SO4)3, Fe2(SO4)3·5H2O, kornelite, coquimbite, Fe(SO4)(OH), jarosite and rhomboclase. Fourier transform infrared spectra in the region 750–4000 cm−1 are presented for all studied phases. Position of the FTIR bands is discussed in terms of the vibrations of sulfate ions, hydroxyl groups, and water molecules. Sulfur K-edge X-ray absorption near-edge structure (XANES) spectra were collected for selected samples. The feature of greatest interest is a series of weak pre-edge peaks whose position is determined by the number of bridging oxygen atoms between Fe3+ octahedra and sulfate tetrahedra. Mössbauer spectra of selected samples were obtained at room temperature and 80 K for ferric minerals jarosite and rhomboclase and mixed ferric–ferrous minerals römerite, voltaite, and copiapite. Values of Fe2+/[Fe2+ + Fe3+] determined by Mössbauer spectroscopy agree well with those determined by wet chemical analysis. The data presented here can be used as standards in spectroscopic work where spectra of well-characterized compounds are required to identify complex mixtures of minerals and related phases.

  18. Real-time X-ray absorption spectroscopy of uranium, iron, and manganese in contaminated sediments during bioreduction.

    PubMed

    Tokunag, Tetsu K; Wan, Jiamin; Kim, Yongman; Sutton, Steve R; Newville, Matthew; Lanzirotti, Antonio; Rao, William

    2008-04-15

    The oxidation status of uranium in sediments is important because the solubility of this toxic and radioactive element is much greater for U(VI) than for U(IV) species. Thus, redox manipulation to promote precipitation of UO2 is receiving interest as a method to remediate U-contaminated sediments. Presence of Fe and Mn oxides in sediments at much higher concentrations than U requires an understanding of their redox status as well. This study was conducted to determine changes in oxidation states of U, Fe, and Mn in U-contaminated sediments from Oak Ridge National Laboratory. Oxidation states of these elements were measured in real-time and nondestructively using X-ray absorption spectroscopy on sediment columns supplied with synthetic groundwater containing organic carbon (OC, 0, 3, 10, 30, and 100 mM OC as lactate) for over 400 days. In sediments supplied with OC > or = 30 mM, 80% of the U was reduced to U(IV), with transient reoxidation at about 150 days. Mn(III,IV) oxides were completely reduced to Mn(II) in sediments infused with OC > or = 3 mM. However, Fe remained largely unreduced in all sediment columns, showing that Fe(III) can persist as an electron acceptor in reducing sediments over long times. This result in combination with the complete reduction of all other potential electron acceptors supports the hypothesis that the reactive Fe(III) fraction was responsible for reoxidizing U(IV).

  19. Real-time x-ray absorption spectroscopy of uranium, iron, and manganese in contaminated sediments during bioreduction

    SciTech Connect

    Tokunaga, Tetsu; Tokunaga, T.K.; Wan, J.; Kim, Y.; Sutton, S.R.; Newville, M.; Lanzirotti, A.; Rao, W.

    2008-01-15

    The oxidation status of uranium in sediments is important because the solubility of this toxic and radioactive element is much greater for U(VI) than for U(IV) species. Thus, redox manipulation to promote precipitation of UO{sub 2} is receiving interest as a method to remediate U-contaminated sediments. Presence of Fe and Mn oxides in sediments at much higher concentrations than U requires understanding of their redox status as well. This study was conducted to determine changes in oxidation states of U, Fe, and Mn in U-contaminated sediments from Oak Ridge National Laboratory. Oxidation states of these elements were measured in real-time and nondestructively using X-ray absorption spectroscopy, on sediment columns supplied with synthetic groundwater containing organic carbon (OC, 0, 3, 10, 30 and 100 mM OC as lactate) for over 400 days. In sediments supplied with OC {ge} 30 mM, 80% of the U was reduced to U(IV), with transient reoxidation at about 150 days. Mn(III,IV) oxides were completely reduced to Mn(II) in sediments infused with OC {ge} 3 mM. However, Fe remained largely unreduced in all sediment columns, showing that Fe(III) can persist as an electron acceptor in reducing sediments over long times. This result in combination with the complete reduction of all other potential electron acceptors supports the hypothesis that the reactive Fe(III) fraction was responsible for reoxidizing U(IV).

  20. Evidence for Anaerobic Methane Oxidation Under Iron-Reducing Conditions in a Crude-Oil Contaminated Aquifer

    NASA Astrophysics Data System (ADS)

    Bekins, B. A.; Amos, R. T.; Cozzarelli, I. M.; Voytek, M. A.; Kirshtein, J.; Jones, E. J.; Delin, G. N.

    2008-12-01

    Although anaerobic methane oxidation (AMO) under iron reducing conditions is energetically feasible, its existence is still an open question. At a crude oil spill site near the town of Bemidji, MN, methanogenic degradation of entrapped oil floating at the water table has been occurring for more than 20 years. In the anaerobic portion of the hydrocarbon plume there is evidence for AMO under iron-reducing conditions between 75 m and 120 m downgradient of the oil body. In this zone, dissolved methane concentrations decrease steadily from over 0.6 mmol/L to less than 0.06 mmol/L. Decreases in dissolved methane are accompanied by an increase in δ13C-CH4 indicating that methane attenuation occurs through microbially mediated oxidation. The dissolved methane decrease of ~0.5 mmol/L occurs where dissolved sulfate is below 0.06 mmol/L, dissolved oxygen is below 3 μmol/L, and nitrate is below 0.02 mmol/L. Together these electron acceptors can account for degradation of only 0.07 mmol/L of methane. Moreover, hydrocarbon contaminants contribute an additional ~1 mmol/L total organic carbon in this area. Active iron- reduction is indicated by dissolved iron concentrations exceeding 0.15 mmol/L. To investigate the sediment bioavailable iron and microbial populations, 2-m-long cores were collected at four locations spaced 15 m horizontally and sampled at 50-cm-depth intervals. Values of bioavailable Fe(III) averaged 8 mmol/kg (n=16), which is over eight times the amount required to degrade 0.5 mmol/L methane. Geobacter detected by qPCR averaged over 2,600/g, while sulfate reducing bacteria were detected in only four samples with 100/g being the highest abundance measured. Laboratory incubations were performed with eight sediment samples from these cores. For each location, 1 g of sediment was added to 10 mL anaerobic medium and amended with amorphous FeOOH, Fe(III)NTA, sulfate, or nitrate. Loss of methane occurred in 33% of the iron-amended treatments, 25% of the nitrate

  1. Lack of Plasma Protein Hemopexin Results in Increased Duodenal Iron Uptake

    PubMed Central

    Fiorito, Veronica; Geninatti Crich, Simonetta; Silengo, Lorenzo; Aime, Silvio; Altruda, Fiorella; Tolosano, Emanuela

    2013-01-01

    Purpose The body concentration of iron is regulated by a fine equilibrium between absorption and losses of iron. Iron can be absorbed from diet as inorganic iron or as heme. Hemopexin is an acute phase protein that limits iron access to microorganisms. Moreover, it is the plasma protein with the highest binding affinity for heme and thus it mediates heme-iron recycling. Considering its involvement in iron homeostasis, it was postulated that hemopexin may play a role in the physiological absorption of inorganic iron. Methods and Results Hemopexin-null mice showed elevated iron deposits in enterocytes, associated with higher duodenal H-Ferritin levels and a significant increase in duodenal expression and activity of heme oxygenase. The expression of heme-iron and inorganic iron transporters was normal. The rate of iron absorption was assessed by measuring the amount of 57Fe retained in tissues from hemopexin-null and wild-type animals after administration of an oral dose of 57FeSO4 or of 57Fe-labelled heme. Higher iron retention in the duodenum of hemopexin-null mice was observed as compared with normal mice. Conversely, iron transfer from enterocytes to liver and bone marrow was unaffected in hemopexin-null mice. Conclusions The increased iron level in hemopexin-null duodenum can be accounted for by an increased iron uptake by enterocytes and storage in ferritins. These data indicate that the lack of hemopexin under physiological conditions leads to an enhanced duodenal iron uptake thus providing new insights to our understanding of body iron homeostasis. PMID:23826373

  2. Effects of low iron conditions on the repair of DNA lesions induced by Cumene hydroperoxide in Escherichia coli cells.

    PubMed

    Asad, L M; Medeiros, D C; Felzenszwalb, I; Leitão, A C; Asad, N R

    2001-05-10

    In the present study, we evaluated the sensitivity of different Escherichia coli strains to Cumene hydroperoxide (CHP) treatment under distinct conditions of Fe2+ availability. Our results showed that the pretreatment with an iron chelator (dipyridyl) protects all the tested strains against CHP toxic effects, but it was not sufficient to abolish the CHP induced mutagenesis. On the other hand, simultaneous pretreatment with both dipyridyl and neocuproine (copper chelator) leads to a complete protection against CHP mutagenic effects. Our data suggest the participation of copper ion in the CHP mutagenesis induced in E. coli.

  3. Determination of tin in ores, iron, steel and non-ferrous alloys by atomic-absorption spectrophotometry after separation by extraction as the iodide.

    PubMed

    Donaldson, E M

    1980-06-01

    A simple and moderately rapid method for determining 0.001% or more of tin in ores, concentrates and tailings, iron, steel and copper-, zinc-, aluminium-, titanium- and zirconium-base alloys is described. After sample decomposition, tin is separated from the matrix elements, except arsenic, by toluene extraction of its iodide from a 3M sulphuric acid-1.5M potassium iodide medium containing tartaric and ascorbic acids. It is finally back-extracted into a nitric-sulphuric acid solution containing hydrochloric acid to prevent the formation of an insoluble tin-arsenic compound and the resultant solution is evaporated to dryness. Tin is subsequently determined by atomic-absorption spectrophotometry in a nitrous oxide-acetylene flame, at 235.4 nm in a 10% hydrochloric-0.5% tartaric acid medium containing 250 mug of potassium per ml. Co-extracted arsenic does not interfere. Results obtained by this method are compared with those obtained spectrophotometrically with gallein after the separation of tin by iodide extraction.

  4. Determination of chromium in ores, rocks and related materials, iron, steel and non-ferrous alloys by atomic-absorption spectrophotometry after separation by tribenzylamine-chloroform extraction.

    PubMed

    Donaldson, E M

    1980-10-01

    A method for determining trace and moderate amounts of chromium in ores, concentrates, rocks, soils and clays is described. After fusion of the sample with sodium peroxide, the melt is dissolved in dilute sulphuric acid. The chromium(III) produced by the hydrogen peroxide formed is co-precipitated with hydrous ferric oxide. The precipitate is dissolved in 0.7M sulphuric acid and chromium oxidized to chromium(VI) with ceric ammonium sulphate. The chromium(VI) is extracted as an ion-association complex into chloroform containing tribenzylamine and stripped with ammoniacal hydrogen peroxide. This solution is acidified with perchloric acid and chromium determined by atomic-absorption spectrophotometry in an air-acetylene flame, at 357.9 nm. Barium and strontium do not interfere. The procedure is also applicable to iron and steel, and nickel-copper, aluminium and zirconium alloys. Up to 5 mg of manganese and 10 mg each of molybdenum and vanadium will not interfere. In the absence of vanadium, up to 10 mg of tungsten will not interfere. In the presence of 1 mg of vanadium, up to 1 mg of tungsten will not interfere.

  5. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M. Kothari, Gerard T. Pittard

    2004-01-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints that connect pipe sections together tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast iron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1--Program Management and Task 2--were completed in prior quarters while Task 3--Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves has progressed to installing prototype sleeves in cast iron test pipe segments. Efforts in this quarter continued to focus on Tasks 4--8, with significant progress made in each. Task 4 (Design, Fabricate and Test Patch Setting Robotic Train) progressed to the design of the control electronics and pneumatic system to inflate the bladder robotic patch setting module. Task 5 (Design & Fabricate Pipe-Wall Cleaning Robot Train with Pan/Zoom/Tilt Camera) continued with additional in-pipe testing required to

  6. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M Kothari; Gerard T. Pittard

    2004-07-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints that connect pipe sections together tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple castiron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1 (Program Management) and Task 2 (Establishment of Detailed Design Specifications) were completed in prior quarters while Task 3 (Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves) has progressed to installing prototype sleeves in cast iron test pipe segments. Efforts in this quarter continued to focus on Tasks 4-8, with significant progress made in each. Task 4 (Design, Fabricate and Test Patch Setting Robotic Train) progressed to the design of the control electronics and pneumatic system to inflate the bladder robotic patch setting module. Task 5 (Design & Fabricate Pipe-Wall Cleaning Robot Train with Pan/Zoom/Tilt Camera

  7. [Iron deficiency and digestive disorders].

    PubMed

    Cozon, G J N

    2014-11-01

    Iron deficiency anemia still remains problematic worldwide. Iron deficiency without anemia is often undiagnosed. We reviewed, in this study, symptoms and syndromes associated with iron deficiency with or without anemia: fatigue, cognitive functions, restless legs syndrome, hair loss, and chronic heart failure. Iron is absorbed through the digestive tract. Hepcidin and ferroportin are the main proteins of iron regulation. Pathogenic micro-organisms or intestinal dysbiosis are suspected to influence iron absorption.

  8. Conditional knockout of the Slc5a6 gene in mouse intestine impairs biotin absorption.

    PubMed

    Ghosal, Abhisek; Lambrecht, Nils; Subramanya, Sandeep B; Kapadia, Rubina; Said, Hamid M

    2013-01-01

    The Slc5a6 gene expresses a plasma membrane protein involved in the transport of the water-soluble vitamin biotin; the transporter is commonly referred to as the sodium-dependent multivitamin transporter (SMVT) because it also transports pantothenic acid and lipoic acid. The relative contribution of the SMVT system toward carrier-mediated biotin uptake in the native intestine in vivo has not been established. We used a Cre/lox technology to generate an intestine-specific (conditional) SMVT knockout (KO) mouse model to address this issue. The KO mice exhibited absence of expression of SMVT in the intestine compared with sex-matched littermates as well as the expected normal SMVT expression in other tissues. About two-thirds of the KO mice died prematurely between the age of 6 and 10 wk. Growth retardation, decreased bone density, decreased bone length, and decreased biotin status were observed in the KO mice. Microscopic analysis showed histological abnormalities in the small bowel (shortened villi, dysplasia) and cecum (chronic active inflammation, dysplasia) of the KO mice. In vivo (and in vitro) transport studies showed complete inhibition in carrier-mediated biotin uptake in the intestine of the KO mice compared with their control littermates. These studies provide the first in vivo confirmation in native intestine that SMVT is solely responsible for intestinal biotin uptake. These studies also provide evidence for a casual association between SMVT function and normal intestinal health.

  9. Characterization of iron ore pellets with dextrin added organic binders under different time and temperature conditions

    NASA Astrophysics Data System (ADS)

    babu kotta, Anand; karak, Swapan kumar; Kumar, M.

    2017-02-01

    In the present work, Dextrin is used as a binder for iron ore pelletization, as it’s free from Silica and Alumina. Green pellets were prepared by mixing of iron ore particles (-75 μm) with varying binder percentage (1 wt. % bentonite, 0.5 and 1 wt. % of dextrin) separately. The green pellets were first dried in air for 24 h and then in an electric oven at 383 K for 4 h. The dried pellets were fired at varying temperatures (1173, 1273, 1373, and 1473 K) and indurated for 1 and 2 h. The samples were characterized for physical (pellet size) and mechanical (compressive strengths, porosity and hardness) properties. Good quality pellets were prepared with organic binder, and which increases the compressive strength of dry and fired pellets. Strength results are matching with the bentonite binder pellets and it is well above the industrially acceptable limit (250 kg/pellet). Porosity of the fired pellets decreases with increasing temperature and induration time. The hardness of the pellet varies from surface to core of the pellet. Moreover, the influence of wear mechanism (based on collisions) on pellets and its characteristics of generated particle size distribution (PSD) have been investigated. It was noticed that the material loss during wear test decreases with increasing strength of the pellet. From PSD analysis, the coarse particles were revealed that the collisions are dominating during wear.

  10. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M. Kothari; Gerard T. Pittard

    2005-07-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. Bell-and-spigot joints that connect pipe sections together tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple castiron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs with the pipe in service by traveling through the pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, minimize excavation, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of old cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct safe repair operations on live mains.

  11. Calcite precipitation dominates the electrical signatures of zero valent iron columns under simulated field conditions

    SciTech Connect

    Yuxin Wu; Roelof Versteeg; Lee Slater; Doug Labrecque

    2009-05-01

    Calcium carbonate is a major secondary mineral precipitate that influences PRB reactivity and hydraulic performance. In this study, we conducted column experiments to investigate electrical signatures resulting from concurrent CaCO3 and iron oxides precipitation in two simulated PRB media. Solid phase analysis identified CaCO3 (calcite and aragonite) as a major mineral phase throughout the columns, with magnetite being another major phase present close to the influent. Electrical measurements revealed a consistent decrease in conductivity and polarization magnitude of both columns, suggesting that the electrically insulating CaCO3 dominates the electrical response despite the presence of both electrically conductive iron oxides and CaCO3 precipitates. SEM/EDX imaging suggests that the electrical properties result from the geometrical arrangement of the mineral phases. The CaCO3 forms an insulating film on ZVI/magnetite surfaces, which we assume restricts redox-driven transfer of electric charge between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss.

  12. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M. Kothari; Gerard T. Pittard

    2005-01-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints that connect pipe sections together tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast-iron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1 (Program Management) and Task 2 (Establishment of Detailed Design Specifications) were completed in prior quarters while Task 3 (Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves) has progressed to installing prototype sleeves in cast-iron test pipe segments. Efforts in the current quarter continued to focus on Tasks 4-8. Highly valuable lessons were learned from field tests of the 4-inch gas pipe repair robot in cast-iron pipe at Public Service Electric & Gas. (These field tests were conducted and reported last quarter.) These tests identified several design issues which need to be implemented in both the small- and large

  13. Micro-Structure of Iron in Petroselinum crispum and its dependence with the chemical nature of the soil

    NASA Astrophysics Data System (ADS)

    Dehipawala, Sunil; Samarasekara, Pubudu; Dahanayake, Rasika; Edmund, Leung

    The micro structure of the iron Iron in Petroselinum crispum is investigated using synchrotron X-ray Absorption and Mossbauer spectroscopy. Plants were grown under controlled soil conditions with different pH, and iron concentrations. The correlation between the micro structure of the iron in Petroselinum crispum plants and the soil conditions were studied. Most of the iron present in the plants has the form Fe3+ or electron density at the site of the iron nucleus similar to that of Fe3+. But the amount of iron absorbed by the plants depends on the soil conditions. These findings will help establish soil conditions necessary to increase Fe2+ intake by plants similar to the form of iron present in most supplements. Support for this project was provided by a PSC-CUNY Award, jointly funded by The Professional Staff Congress and The City University of New York.

  14. Uranium immobilization in an iron-rich rhizosphere of a native wetland plant from the Savannah River Site under reducing conditions.

    PubMed

    Chang, Hyun-shik; Buettner, Shea W; Seaman, John C; Jaffé, Peter R; van Groos, Paul G Koster; Li, Dien; Peacock, Aaron D; Scheckel, Kirk G; Kaplan, Daniel I

    2014-08-19

    The hypothesis of this study was that iron plaques formed on the roots of wetland plants and their rhizospheres create environmental conditions favorable for iron reducing bacteria that promote the in situ immobilization of uranium. Greenhouse microcosm studies were conducted using native plants (Sparganium americanum) from a wetland located on the Savannah River Site, Aiken, SC. After iron plaques were established during a 73-day period by using an anoxic Fe(II)-rich nutrient solution, a U(VI) amended nutrient solution was added to the system for an additional two months. Compared to plant-free control microcosms, microcosms containing iron plaques successfully stimulated the growth of targeted iron reducing bacteria, Geobacter spp. Their population continuously increased after the introduction of the U(VI) nutrient solution. The reduction of some of the U(VI) to U(IV) by iron reducing bacteria was deduced based on the observations that the aqueous Fe(II) concentrations increased while the U(VI) concentrations decreased. The Fe(II) produced by the iron reducing bacteria was assumed to be reoxidized by the oxygen released from the roots. Advanced spectroscopic analyses revealed that a significant fraction of the U(VI) had been reduced to U(IV) and they were commonly deposited in association with phosphorus on the iron plaque.

  15. Increased iron supplied through Fet3p results in replicative life span extension of Saccharomyces cerevisiae under conditions requiring respiratory metabolism.

    PubMed

    Botta, Gabriela; Turn, Christina S; Quintyne, Nicholas J; Kirchman, Paul A

    2011-10-01

    We have previously shown that copper supplementation extends the replicative life span of Saccharomyces cerevisiae when grown under conditions forcing cells to respire. We now show that copper's effect on life span is through Fet3p, a copper containing enzyme responsible for high affinity transport of iron into yeast cells. Life span extensions can also be obtained by supplementing the growth medium with 1mM ferric chloride. Extension by high iron levels is still dependent on the presence of Fet3p. Life span extension by iron or copper requires growth on media containing glycerol as the sole carbon source, which forces yeast to respire. Yeast grown on glucose containing media supplemented with iron show no extension of life span. The iron associated with cells grown in media supplemented with copper or iron is 1.4-1.8 times that of cells grown without copper or iron supplementation. As with copper supplementation, iron supplementation partially rescues the life span of superoxide dismutase mutants. Cells grown with copper supplementation display decreased production of superoxide as measured by dihydroethidium staining.

  16. Conditional (intestinal-specific) knockout of the riboflavin transporter-3 (RFVT-3) impairs riboflavin absorption.

    PubMed

    Subramanian, Veedamali S; Lambrecht, Nils; Lytle, Christian; Said, Hamid M

    2016-02-15

    Riboflavin (RF) is indispensable for normal cell metabolism, proliferation, and growth. The RFVT-3 protein (product of the Slc52a3 gene) is expressed in the gut with the expression being restricted to the apical membrane domain of the polarized intestinal epithelial cells. The relative contribution of RFVT-3 to total carrier-mediated RF uptake in the native intestine, however, is not clear. We addressed this issue in the current investigation using a conditional (intestinal-specific) RFVT-3 knockout (cKO) mouse model developed by the Cre/Lox approach. All RFVT-3 cKO mice were found to be RF deficient and showed a significant growth and development retardation; also, nearly two-thirds of them died prematurely between the age of 6 and 12 wk. In vivo (intestinal and colonic loops) and in vitro (native isolated intestinal epithelial cells) uptake studies showed a severe inhibition in carrier-mediated RF uptake in the cKO mice compared with control littermates. We also observed a significant increase in the level of expression of oxidative stress-responsive genes in the intestine of the cKO mice compared with control littermates. Supplementation of the RFVT-3 cKO mice with pharmacological doses of RF led to a complete correction of the growth retardation and to normalization in the level of expression of the oxidative stress-responsive genes in the gut. These results show, for the first time, that the RFVT-3 system is the main transporter involved in carrier-mediated RF uptake in the native mouse small and large intestine, and that its dysfunction impairs normal RF body homeostasis.

  17. Controlled hydrodynamic conditions on the formation of iron oxide nanostructures synthesized by electrochemical anodization: Effect of the electrode rotation speed

    NASA Astrophysics Data System (ADS)

    Lucas-Granados, Bianca; Sánchez-Tovar, Rita; Fernández-Domene, Ramón M.; García-Antón, Jose

    2017-01-01

    Iron oxide nanostructures are of particular interest because they can be used as photocatalysts in water splitting due to their advantageous properties. Electrochemical anodization is one of the best techniques to synthesize nanostructures directly on the metal substrate (direct back contact). In the present study, a novel methodology consisting of the anodization of iron under hydrodynamic conditions is carried out in order to obtain mainly hematite (α-Fe2O3) nanostructures to be used as photocatalysts for photoelectrochemical water splitting applications. Different rotation speeds were studied with the aim of evaluating the obtained nanostructures and determining the most attractive operational conditions. The synthesized nanostructures were characterized by means of Raman spectroscopy, Field Emission Scanning Electron Microscopy, photoelectrochemical water splitting, stability against photocorrosion tests, Mott-Schottky analysis, Electrochemical Impedance Spectroscopy (EIS) and band gap measurements. The results showed that the highest photocurrent densities for photoelectrochemical water splitting were achieved for the nanostructure synthesized at 1000 rpm which corresponds to a nanotubular structure reaching ∼0.130 mA cm-2 at 0.54 V (vs. Ag/AgCl). This is in agreement with the EIS measurements and Mott-Schottky analysis which showed the lowest resistances and the corresponding donor density values, respectively, for the nanostructure anodized at 1000 rpm.

  18. pH-dependent degradation of p-nitrophenol by sulfidated nanoscale zerovalent iron under aerobic or anoxic conditions.

    PubMed

    Tang, Jing; Tang, Lin; Feng, Haopeng; Zeng, Guangming; Dong, Haoran; Zhang, Chang; Huang, Binbin; Deng, Yaocheng; Wang, Jiajia; Zhou, Yaoyu

    2016-12-15

    Sulfidated nanoscale zerovalent iron (S-NZVI) is attracting considerable attention due to its easy production and high reactivity to pollutants. We studied the reactivity of optimized S-NZVI (Fe/S molar ratio 6.9), comparing with pristine nanoscale zerovalent iron (NZVI), at various pH solutions (6.77-9.11) towards p-nitrophenol (PNP) under aerobic and anoxic conditions. Studies showed that the optimized extent of sulfidation could utterly enhance PNP degradation compared to NZVI. Batch experiments indicated that in anoxic S-NZVI systems the degradation rate constant increased with increasing pH up to 7.60, and then declined. However, in aerobic S-NZVI, and in anoxic or aerobic NZVI systems, it decreased as pH increased. It was manifested that anoxic S-NZVI systems preferred to weaker alkaline solutions, whereas aerobic S-NZVI systems performed better in acidic solutions. The highest TOC removal efficiency of PNP (17.59%) was achieved in the aerobic S-NZVI system at pH 6.77, revealing that oxygen improved the degradation of PNP by excessive amounts of hydroxyl radicals in slightly acidic conditions, and the TOC removal efficiency was supposed to be further improved in moderate acidic solutions. Acetic acid, a nontoxic ring opening by-product, confirms that the S-NZVI system could be a promising process for industrial wastewater containing sulfide ions.

  19. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M. Kothari; Gerard T. Pittard

    2004-11-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints that connect pipe sections together tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple castiron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1 (Program Management) and Task 2 (Establishment of Detailed Design Specifications) were completed in prior quarters while Task 3 (Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves) has progressed to installing prototype sleeves in cast iron test pipe segments. Efforts in this quarter continued to focus on Tasks 4-8, with significant progress made in each as well as field testing of the 4-inch gas pipe repair robot in cast iron pipe at Public Service Electric & Gas. The field tests were conducted August 23-26, 2004 in Oradell, New Jersey. The field tests identified several design issues which need to be implemented in both the small

  20. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M. Kothari; Gerard T. Pittard

    2005-04-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints that connect pipe sections together tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast-iron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and installing a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service to customers (which would result in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of old cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1 (Program Management) and Task 2 (Establishment of Detailed Design Specifications) were completed previously. Task 3 (Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves) has progressed to installing prototype sleeves in test cast-iron pipe segments. Efforts in the current quarter continued to be focused on Tasks 4-8. Highly valuable lessons were learned from field tests of the 4-inch gas pipe repair robot in cast-iron pipe at Public Service Electric & Gas. (These field tests were conducted and reported previously.) Several design issues were identified which need to be implemented in both the small- and large-diameter repair

  1. The basic leucine zipper stress response regulator Yap5 senses high-iron conditions by coordination of [2Fe-2S] clusters.

    PubMed

    Rietzschel, Nicole; Pierik, Antonio J; Bill, Eckhard; Lill, Roland; Mühlenhoff, Ulrich

    2015-01-01

    Iron is an essential, yet at elevated concentrations toxic trace element. To date, the mechanisms of iron sensing by eukaryotic iron-responsive transcription factors are poorly understood. The Saccharomyces cerevisiae transcription factor Yap5, a member of the Yap family of bZIP stress response regulators, administrates the adaptive response to high-iron conditions. Despite the central role of the iron-sensing process for cell viability, the molecule perceived by Yap5 and the underlying regulatory mechanisms are unknown. Here, we show that Yap5 senses high-iron conditions by two Fe/S clusters bound to its activator domain (Yap5-AD). The more stable iron-regulatory Fe/S cluster at the N-terminal cysteine-rich domain (n-CRD) of Yap5 is detected in vivo and in vitro. The second cluster coordinated by the C-terminal CRD can only be shown after chemical reconstitution, since it is bound in a labile fashion. Both clusters are of the [2Fe-2S] type as characterized by UV/visible (UV/Vis), circular dichroism, electron paramagnetic resonance (EPR), and Mössbauer spectroscopy. Fe/S cluster binding to Yap5-AD induces a conformational change that may activate transcription. The cluster-binding motif of the n-CRD domain is highly conserved in HapX-like transcription factors of pathogenic fungi and thus may represent a general sensor module common to many eukaryotic stress response regulators.

  2. The Basic Leucine Zipper Stress Response Regulator Yap5 Senses High-Iron Conditions by Coordination of [2Fe-2S] Clusters

    PubMed Central

    Rietzschel, Nicole; Pierik, Antonio J.; Bill, Eckhard; Mühlenhoff, Ulrich

    2014-01-01

    Iron is an essential, yet at elevated concentrations toxic trace element. To date, the mechanisms of iron sensing by eukaryotic iron-responsive transcription factors are poorly understood. The Saccharomyces cerevisiae transcription factor Yap5, a member of the Yap family of bZIP stress response regulators, administrates the adaptive response to high-iron conditions. Despite the central role of the iron-sensing process for cell viability, the molecule perceived by Yap5 and the underlying regulatory mechanisms are unknown. Here, we show that Yap5 senses high-iron conditions by two Fe/S clusters bound to its activator domain (Yap5-AD). The more stable iron-regulatory Fe/S cluster at the N-terminal cysteine-rich domain (n-CRD) of Yap5 is detected in vivo and in vitro. The second cluster coordinated by the C-terminal CRD can only be shown after chemical reconstitution, since it is bound in a labile fashion. Both clusters are of the [2Fe-2S] type as characterized by UV/visible (UV/Vis), circular dichroism, electron paramagnetic resonance (EPR), and Mössbauer spectroscopy. Fe/S cluster binding to Yap5-AD induces a conformational change that may activate transcription. The cluster-binding motif of the n-CRD domain is highly conserved in HapX-like transcription factors of pathogenic fungi and thus may represent a general sensor module common to many eukaryotic stress response regulators. PMID:25368382

  3. New developments and controversies in iron metabolism and iron chelation therapy.

    PubMed

    Kontoghiorghe, Christina N; Kontoghiorghes, George J

    2016-03-26

    Iron is essential for all organisms including microbial, cancer and human cells. More than a quarter of the human population is affected by abnormalities of iron metabolism, mainly from iron deficiency and iron overload. Iron also plays an important role in free radical pathology and oxidative damage which is observed in almost all major diseases, cancer and ageing. New developments include the complete treatment of iron overload and reduction of morbidity and mortality in thalassaemia using deferiprone and selected deferiprone/deferoxamine combinations and also the use of the maltol iron complex in the treatment of iron deficiency anaemia. There is also a prospect of using deferiprone as a universal antioxidant in non iron overloaded diseases such as neurodegenerative, cardiovascular, renal, infectious diseases and cancer. New regulatory molecules of iron metabolism such as endogenous and dietary chelating molecules, hepcidin, mitochondrial ferritin and their role in health and disease is under evaluation. Similarly, new mechanisms of iron deposition, removal, distribution and toxicity have been identified using new techniques such as magnetic resonance imaging increasing our understanding of iron metabolic processes and the targeted treatment of related diseases. The uniform distribution of iron in iron overload between organs and within each organ is no longer valid. Several other controversies such as the toxicity impact of non transferrin bound iron vs injected iron, the excess levels of iron in tissues causing toxicity and the role of chelation on iron absorption need further investigation. Commercial interests of pharmaceutical companies and connections to leading journals are playing a crucial role in shaping worldwide medical opinion on drug sales and use but also patients' therapeutic outcome and safety. Major controversies include the selection criteria and risk/benefit assessment in the use of deferasirox in thalassaemia and more so in idiopathic

  4. New developments and controversies in iron metabolism and iron chelation therapy

    PubMed Central

    Kontoghiorghe, Christina N; Kontoghiorghes, George J

    2016-01-01

    Iron is essential for all organisms including microbial, cancer and human cells. More than a quarter of the human population is affected by abnormalities of iron metabolism, mainly from iron deficiency and iron overload. Iron also plays an important role in free radical pathology and oxidative damage which is observed in almost all major diseases, cancer and ageing. New developments include the complete treatment of iron overload and reduction of morbidity and mortality in thalassaemia using deferiprone and selected deferiprone/deferoxamine combinations and also the use of the maltol iron complex in the treatment of iron deficiency anaemia. There is also a prospect of using deferiprone as a universal antioxidant in non iron overloaded diseases such as neurodegenerative, cardiovascular, renal, infectious diseases and cancer. New regulatory molecules of iron metabolism such as endogenous and dietary chelating molecules, hepcidin, mitochondrial ferritin and their role in health and disease is under evaluation. Similarly, new mechanisms of iron deposition, removal, distribution and toxicity have been identified using new techniques such as magnetic resonance imaging increasing our understanding of iron metabolic processes and the targeted treatment of related diseases. The uniform distribution of iron in iron overload between organs and within each organ is no longer valid. Several other controversies such as the toxicity impact of non transferrin bound iron vs injected iron, the excess levels of iron in tissues causing toxicity and the role of chelation on iron absorption need further investigation. Commercial interests of pharmaceutical companies and connections to leading journals are playing a crucial role in shaping worldwide medical opinion on drug sales and use but also patients’ therapeutic outcome and safety. Major controversies include the selection criteria and risk/benefit assessment in the use of deferasirox in thalassaemia and more so in idiopathic

  5. [Iron dysregulation and anemias].

    PubMed

    Ikuta, Katsuya

    2015-10-01

    Most iron in the body is utilized as a component of hemoglobin that delivers oxygen to the entire body. Under normal conditions, the iron balance is tightly regulated. However, iron dysregulation does occasionally occur; total iron content reductions cause iron deficiency anemia and overexpression of the iron regulatory peptide hepcidin disturbs iron utilization resulting in anemia of chronic disease. Conversely, the presence of anemia may ultimately lead to iron overload; for example, thalassemia, a common hereditary anemia worldwide, often requires transfusion, but long-term transfusions cause iron accumulation that leads to organ damage and other poor outcomes. On the other hand, there is a possibility that iron overload itself can cause anemia; iron chelation therapy for the post-transfusion iron overload observed in myelodysplastic syndrome or aplastic anemia improves dependency on transfusions in some cases. These observations reflect the extremely close relationship between anemias and iron metabolism.

  6. Definition of a parameter for a typical specific absorption rate under real boundary conditions of cellular phones in a GSM networkd

    NASA Astrophysics Data System (ADS)

    Gerhardt, D.

    2003-05-01

    Using cellular phones the specific absorption rate (SAR) as a physical value must observe established and internationally defined levels to guarantee human protection. To assess human protection it is necessary to guarantee safety under worst-case conditions (especially maximum transmitting power) using cellular phones. To evaluate the exposure to electromagnetic fields under normal terms of use of cellular phones the limitations of the specific absorption rate must be pointed out. In a mobile radio network normal terms of use of cellular phones, i.e. in interconnection with a fixed radio transmitter of a mobile radio network, power control of the cellular phone as well as the antenna diagram regarding a head phantom are also significant for the real exposure. Based on the specific absorption rate, the antenna diagram regarding a head phantom and taking into consideration the power control a new parameter, the typical absorption rate (SARtyp), is defined in this contribution. This parameter indicates the specific absorption rate under average normal conditions of use. Constant radio link attenuation between a cellular phone and a fixed radio transmitter for all mobile models tested was assumed in order to achieve constant field strength at the receiving antenna of the fixed radio transmitter as a result of power control. The typical specific absorption rate is a characteristic physical value of every mobile model. The typical absorption rate was calculated for 16 different mobile models and compared with the absorption rate at maximum transmitting power. The results confirm the relevance of the definition of this parameter (SARtyp) as opposed to the specific absorption rate as a competent and applicable method to establish the real mean exposure from a cellular phone in a mobile radio network. The typical absorption rate provides a parameter to assess electromagnetic fields of a cellular phone that is more relevant to the consumer.

  7. First-principles Exploration of Crystal Structures of Pure Iron at Earth’s Inner Core Conditions

    NASA Astrophysics Data System (ADS)

    Ishikawa, T.; Tsuchiya, T.; Tsuchiya, J.

    2009-12-01

    Determining the structure of Earth’s inner core has been a long standing challenge for geoscience. Iron has been considered as a main composition of the inner core and expected to exist as an iron-nickel-light elements alloy there. In order to get some information about the structure of the inner core, pure iron has been also investigated by many experimental and ab-initio studies. Pure iron has been expected to take the hexagonal close-packed (hcp) structure at the inner core conditions (Jephcoat and Olson, Nature 325, 332-335, 1987.; Mao et al., Nature 396, 741-743, 1998.; Fiquet et al., Science 291, 468-471, 2001.; Uchida et al., J. Geophys. Res. 106, 21799-21810, 2001.). On the other hand, the face-centered cubic (fcc) structure (Mikhaylushkin et al., Phys. Rev. Lett. 99, 165505-165508, 2007.) and the body-centered cubic structure (Vocadlo et al., Phys. Earth Planet In. 170, 52-59, 2008.) have been also considered as the candidate structures. In this study, first we explored the crystal structures of pure iron at 400 GPa by our originally developing algorithm for the structure exploration, Free Energy Surface Trekking (FEST). In FEST, using a minus sign of driving force acting on a simulation cell, we force a system to climb up to a ridge of a free energy surface (ascent-run). Then, flipping the negative driving force to an original one, we make the system go down to a neighboring potential well (descent-run). The more different directions we examine in the ascent-run, the more accurate topography we capture of free energy surface. For the exploration of the ultrahigh-pressure structures of pure iron, we used 16 atoms supercell and explored 64 pathways around the initial local minimum corresponding to hcp. As the result, 30 pathways lead to a complex hcp (chcp) structure, which has ABCACABCBCAB stacking with 12 layers. Other 33 pathways lead to hcp and 1 pathway fcc. The enthalpy of chcp was found higher than that of hcp but only by 4 mRy/atom and lower than

  8. S K-edge X-ray absorption studies of tetranuclear iron-sulfur clusters: mu-sulfide bonding and its contribution to electron delocalization.

    PubMed

    Glaser, T; Rose, K; Shadle, S E; Hedman, B; Hodgson, K O; Solomon, E I

    2001-01-24

    X-ray absorption spectroscopy (XAS) at the sulfur ( approximately 2470 eV) and chlorine ( approximately 2822 eV) K-edges has been applied to a series of 4Fe-4S model complexes. These are compared to 2Fe-2S model complexes to obtain insight into the localized ground state in the mixed-valence dimer versus the delocalized ground state in the mixed-valence tetramer. The preedges of hypothetical delocalized mixed-valence dimers [Fe(2)S(2)](+) are estimated using trends from experimental data and density functional calculations, for comparison to the delocalized mixed-valence tetramer [Fe(4)S(4)](2+). The differences between these two mixed-valence sites are due to the change of the sulfide-bridging mode from micro(2) to micro(3). The terminal chloride and thiolate ligands are used as spectator ligands for the electron density of the iron center. From the intensity of the preedge, the covalency of the terminal ligands is found to increase in the tetramer as compared to the dimer. This is associated with a higher effective nuclear charge on the iron in the tetramer (derived from the energies of the preedge). The micro(3)-bridging sulfide in the tetramer has a reduced covalency per bond (39%) as compared to the micro(2)-bridging sulfide in the dimer (51%). A simple perturbation model is used to derive a quadratic dependence of the superexchange coupling constant J on the covalency of the metal ions with the bridging ligands. This relationship is used to estimate the superexchange contribution in the tetramer (J = -156 cm(-)(1)) as compared to the mixed-valence dimer (J = -360 cm(-)(1)). These results, combined with estimates for the double exchange and the vibronic coupling contributions of the dimer sub-site of the tetramer, lead to a delocalized S(t) = (9)/(2) spin ground state for the mixed-valence dimer in the tetramer. Thus, the decrease in the covalency, hence the superexchange pathway associated with changing the bridging mode of the sulfides from micro(2) to micro

  9. Electrolytic iron or ferrous sulfate increase body iron in women with moderate to low iron stores.

    PubMed

    Swain, James H; Johnson, LuAnn K; Hunt, Janet R

    2007-03-01

    Commercial elemental iron powders (electrolytic and reduced iron), as well as heme iron supplements, were tested for efficacy in improving the iron status of women. In a randomized, double-blind trial, 51 women with moderate to low iron stores received daily for 12 wk: 1) placebo, 2) 5 mg iron as heme iron or 50 mg iron as 3) electrolytic iron, 4) reduced iron, or 5) FeSO(4). Treatments were provided in 2 capsules (heme carrier) and 3 wheat rolls (other iron sources). Differences in iron status, food nonheme iron absorption, and fecal properties were evaluated. Body iron, assessed from the serum transferrin receptor:ferritin ratio, increased significantly more in subjects administered FeSO(4) (127 +/- 29 mg; mean +/- SEM) and electrolytic (115 +/- 37 mg), but not the reduced (74 +/- 32 mg) or heme (65 +/- 26 mg) iron forms, compared with those given placebo (2 +/- 19 mg). Based on body iron determinations, retention of the added iron was estimated as 3.0, 2.7, 1.8, and 15.5%, in the 4 iron-treated groups, respectively. Iron treatments did not affect food iron absorption. The 50 mg/d iron treatments increased fecal iron and free radical-generating capacity in vitro, but did not affect fecal water cytotoxicity. In subjects administered FeSO(4), fecal water content was increased slightly but significantly more than in the placebo group. In conclusion, electrolytic iron was approximately 86% as efficacious as FeSO(4) for improving body iron, but the power of this study was insufficient to detect any efficacy of the reduced or heme iron within 12 wk. With modification, this methodology of testing higher levels of food fortification for several weeks in healthy women with low iron stores has the potential for economically assessing the efficiency of iron compounds to improve iron status.

  10. Gene expression by the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough grown on an iron electrode under cathodic protection conditions.

    PubMed

    Caffrey, Sean M; Park, Hyung Soo; Been, Jenny; Gordon, Paul; Sensen, Christoph W; Voordouw, Gerrit

    2008-04-01

    The genome sequence of the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough was reanalyzed to design unique 70-mer oligonucleotide probes against 2,824 probable protein-coding regions. These included three genes not previously annotated, including one that encodes a c-type cytochrome. Using microarrays printed with these 70-mer probes, we analyzed the gene expression profile of wild-type D. vulgaris grown on cathodic hydrogen, generated at an iron electrode surface with an imposed negative potential of -1.1 V (cathodic protection conditions). The gene expression profile of cells grown on cathodic hydrogen was compared to that of cells grown with gaseous hydrogen bubbling through the culture. Relative to the latter, the electrode-grown cells overexpressed two hydrogenases, the hyn-1 genes for [NiFe] hydrogenase 1 and the hyd genes, encoding [Fe] hydrogenase. The hmc genes for the high-molecular-weight cytochrome complex, which allows electron flow from the hydrogenases across the cytoplasmic membrane, were also overexpressed. In contrast, cells grown on gaseous hydrogen overexpressed the hys genes for [NiFeSe] hydrogenase. Cells growing on the electrode also overexpressed genes encoding proteins which promote biofilm formation. Although the gene expression profiles for these two modes of growth were distinct, they were more closely related to each other than to that for cells grown in a lactate- and sulfate-containing medium. Electrochemically measured corrosion rates were lower for iron electrodes covered with hyn-1, hyd, and hmc mutant biofilms than for wild-type biofilms. This confirms the importance, suggested by the gene expression studies, of the corresponding gene products in D. vulgaris-mediated iron corrosion.

  11. Structural diversity of the 3-micron absorption band in Enceladus’ plume from Cassini VIMS: Insights into subsurface environmental conditions

    NASA Astrophysics Data System (ADS)

    Dhingra, Deepak; Hedman, Matthew M.; Clark, Roger N.

    2015-11-01

    Water ice particles in Enceladus’ plume display their diagnostic 3-micron absorption band in Cassini VIMS data. These near infrared measurements of the plume also exhibit noticeable variations in the character of this band. Mie theory calculations reveal that the shape and location of the 3-micron band are controlled by a number of environmental and structural parameters. Hence, this band provides important insights into the properties of the water ice grains and about the subsurface environmental conditions under which they formed. For example, the position of the 3-micron absorption band minimum can be used to distinguish between crystalline and amorphous forms of water ice and to constrain the formation temperature of the ice grains. VIMS data indicates that the water ice grains in the plume are dominantly crystalline which could indicate formation temperatures above 113 K [e.g. 1, 2]. However, there are slight (but observable) variations in the band minimum position and band shape that may hint at the possibility of varying abundance of amorphous ice particles within the plume. The modeling results further indicate that there are systematic shifts in band minimum position with temperature for any given form of ice but the crystalline and amorphous forms of water ice are still distinguishable at VIMS spectral resolution. Analysis of the eruptions from individual source fissures (tiger stripes) using selected VIMS observations reveal differences in the 3-micron band shape that may reflect differences in the size distributions of the water ice particles along individual fissures. Mie theory models suggest that big ice particles (>3 micron) may be an important component of the plume.[1] Kouchi, A., T. Yamamoto, T. Kozasa, T. Kuroda, and J. M. Greenberg (1994) A&A, 290, 1009-1018 [2] Mastrapa, R. M. E., W. M. Grundy, and M. S. Gudipati (2013) in M. S. Gudipati and J. Castillo-Rogez (Eds.), The Science of Solar System Ices, pp. 371.

  12. [Iron deficiency anemia and anemia of chronic disorders].

    PubMed

    Metzgeroth, G; Hastka, J

    2015-09-01

    Hypochromic-microcytic anemias are characterized by a hemoglobin deficiency of the erythrocytes. The main reason for the insufficient hemoglobin synthesis is, with exception of thalassemia and a few other rare conditions, primarily a disorder of iron metabolism. Differential diagnostic considerations are focused on iron deficiency anemia, with approximately 80% the most common form of anemia worldwide. Iron deficiency anemia shows a particularly high prevalence in developing countries, but is also in industrialized Western countries the most common cause of anemia. Infants, toddlers, premenopausal or pregnant women, and elderly people are at particularly high risk of iron deficiency anemia. The most important differential diagnosis for iron deficiency anemia is the anemia of chronic disorders (ACD). This anemia is caused by a disturbance of iron utilization (functional iron deficiency), in which iron absorption and iron release, as a nonspecific defense mechanism, is blocked to restrict iron availability for the inflammatory process but also withhold iron from the erythropoiesis. ACD is not rare, but plays a significant role in hospitalized patients and in the elderly. The differentiation between ACD and iron deficiency anemia is highly important from a clinical point of view, due to different types of further management. The cause for iron deficiency should be clarified in each case, whereas the etiology for ACD is often obvious. The standard treatment of iron deficiency anemia is oral iron supplementation. Intravenous iron application is reserved for problem patients. The best treatment for ACD is the elimination of the underlying chronic disorder. In case of persistent ACD, red blood cell transfusions, erythropoietin, and intravenous iron are used therapeutically.

  13. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M. Kothari; Gerard T. Pittard

    2003-06-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast-iron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and attaching a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service (which results in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1-Program Management was previously completed. Two reports, one describing the program management plan and the other consisting of the technology assessment, were submitted to the DOE COR in the first quarter. Task 2-Establishment of Detailed Design Specifications and Task 3-Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves are now well underway. First-quarter activities included conducting detailed analyses to determine the capabilities of coiled-tubing locomotion for entering and repairing gas mains and the first design iteration of the joint-sealing sleeve. The maximum horizontal reach of coiled tubing inside a pipeline before buckling prevents further access was calculated for a wide

  14. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M. Kothari; Gerard T. Pittard

    2003-01-01

    Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast-iron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and attaching a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service (which results in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1--Program Management was previously completed. Two reports, one describing the program management plan and the other consisting of the technology assessment, were submitted to the DOE COR in the first quarter. Task 2--Establishment of Detailed Design Specifications and Task 3--Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves are now well underway. First-quarter activities included conducting detailed analyses to determine the capabilities of coiled-tubing locomotion for entering and repairing gas mains and the first design iteration of the joint-sealing sleeve. The maximum horizontal reach of coiled tubing inside a pipeline before buckling prevents further access was calculated for a

  15. Measuring brain manganese and iron accumulation in rats following 14 weeks of low-dose manganese treatment using atomic absorption spectroscopy and magnetic resonance imaging.

    PubMed

    Fitsanakis, Vanessa A; Zhang, Na; Anderson, Joel G; Erikson, Keith M; Avison, Malcolm J; Gore, John C; Aschner, Michael

    2008-05-01

    Chronic exposure to manganese (Mn) may lead to a movement disorder due to preferential Mn accumulation in the globus pallidus and other basal ganglia nuclei. Iron (Fe) deficiency also results in increased brain Mn levels, as well as dysregulation of other trace metals. The relationship between Mn and Fe transport has been attributed to the fact that both metals can be transported via the same molecular mechanisms. It is not known, however, whether brain Mn distribution patterns due to increased Mn exposure vs. Fe deficiency are the same, or whether Fe supplementation would reverse or inhibit Mn deposition. To address these questions, we utilized four distinct experimental populations. Three separate groups of male Sprague-Dawley rats on different diets (control diet [MnT], Fe deficient [FeD], or Fe supplemented [FeS]) were given weekly intravenous Mn injections (3 mg Mn/kg body mass) for 14 weeks, whereas control (CN) rats were fed the control diet and received sterile saline injections. At the conclusion of the study, both blood and brain Mn and Fe levels were determined by atomic absorption spectroscopy and magnetic resonance imaging. The data indicate that changes in dietary Fe levels (either increased or decreased) result in regionally specific increases in brain Mn levels compared with CN or MnT animals. Furthermore, there was no difference in either Fe or Mn accumulation between FeS or FeD animals. These data suggest that dietary Fe manipulation, whether increased or decreased, may contribute to brain Mn deposition in populations vulnerable to increased Mn exposure.

  16. Failure Mechanisms and Damage Model of Ductile Cast Iron Under Low-Cycle Fatigue Conditions

    NASA Astrophysics Data System (ADS)

    Wu, Xijia; Quan, Guangchun; MacNeil, Ryan; Zhang, Zhong; Sloss, Clayton

    2014-10-01

    Strain-controlled low-cycle fatigue (LCF) tests were conducted on ductile cast iron (DCI) at strain rates of 0.02, 0.002, and 0.0002/s in the temperature range from room temperature to 1073 K (800 °C). A constitutive-damage model was developed within the integrated creep-fatigue theory (ICFT) framework on the premise of strain decomposition into rate-independent plasticity and time-dependent creep. Four major damage mechanisms: (i) plasticity-induced fatigue, (ii) intergranular embrittlement (IE), (iii) creep, and (iv) oxidation were considered in a nonlinear creep-fatigue interaction model which represents the overall damage accumulation process consisting of oxidation-assisted fatigue crack nucleation and propagation in coalescence with internally distributed damage ( e.g., IE and creep), leading to final fracture. The model was found to agree with the experimental observations of the complex DCI-LCF phenomena, for which the linear damage summation rule would fail.

  17. Predicting laser-induced bulk damage and conditioning for deuterated potassium di-hydrogen phosphate crystals using ADM (absorption distribution model)

    SciTech Connect

    Liao, Z M; Spaeth, M L; Manes, K; Adams, J J; Carr, C W

    2010-02-26

    We present an empirical model that describes the experimentally observed laser-induced bulk damage and conditioning behavior in deuterated Potassium dihydrogen Phosphate (DKDP) crystals in a self-consistent way. The model expands on an existing nanoabsorber precursor model and the multi-step absorption mechanism to include two populations of absorbing defects, one with linear absorption and another with nonlinear absorption. We show that this model connects previously uncorrelated small-beam damage initiation probability data to large-beam damage density measurements over a range of ns pulse widths relevant to ICF lasers such as the National Ignition Facility (NIF). In addition, this work predicts the damage behavior of laser-conditioned DKDP and explains the upper limit to the laser conditioning effect. The ADM model has been successfully used during the commissioning and early operation of the NIF.

  18. Impact of microbial activities on the mineralogy and performance of column-scale permeable reactive iron barriers operated under two different redox conditions.

    PubMed

    Van Nooten, Thomas; Lieben, François; Dries, Jan; Pirard, Eric; Springael, Dirk; Bastiaens, Leen

    2007-08-15

    The present study focuses on the impact of microbial activities on the performance of various long-term operated laboratory-scale permeable reactive barriers. The barriers contained both aquifer and Fe0 compartments and had received either sulfate or iron(III)-EDTA to promote sulfate-reducing and iron(III)-reducing bacteria, respectively. After dismantlement of the compartments after almost 3 years of operation, DNA-based PCR-DGGE analysis revealed the presence of methanogenic, sulfate-reducing, metal-reducing, and denitrifying bacteria within as well as up- and downgradient of the Fe0 matrix. Under all imposed conditions, the main secondary phases were vivianite, siderite, ferrous hydroxy carbonate, and carbonate green rust as found by scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). Under sulfate-reduction promoting conditions, iron sulfides were formed in addition, resulting in 7 and 10 times higher degradation rates for PCE and TCE, respectively, compared to unreacted iron. These results indicate that the presence of sulfate-reducing bacteria in or around iron barriers and the subsequent formation of iron sulfides might increase the barrier reactivity.

  19. PERITONEAL ABSORPTION

    PubMed Central

    Hahn, P. F.; Miller, L. L.; Robscheit-Robbins, F. S.; Bale, W. F.; Whipple, G. H.

    1944-01-01

    The absorption of red cells from the normal peritoneum of the dog can be demonstrated by means of red cells labeled with radio-iron incorporated in the hemoglobin of these red cells. Absorption in normal dogs runs from 20 to 100 per cent of the amount given within 24 hours. Dogs rendered anemic by bleeding absorb red cells a little less rapidly—ranging from 5 to 80 per cent of the injected red cells. Doubly depleted dogs (anemic and hypoproteinemic) absorb even less in the three experiments recorded. This peritoneal absorption varies widely in different dogs and even in the same dog at different times. We do not know the factors responsible for these variations but there is no question about active peritoneal absorption. The intact red cells pass readily from the peritoneal cavity into lymph spaces in diaphragm and other areas of the peritoneum. The red cells move along the lymphatics and through the lymph glands with little or no phagocytosis and eventually into the large veins through the thoracic ducts. PMID:19871404

  20. Ammonium Oxidation Under Iron Reducing Conditions: Environmental Factors Characterization and Process Optimization

    NASA Astrophysics Data System (ADS)

    Huang, Shan; Ruiz, Melany; Jaffe, Peter

    2015-04-01

    Ammonium (NH4+) oxidation coupled to iron (Fe) reduction in the absence of oxygen and nitrate/nitrite (NO3-/NO2-) has been reported by several investigators and is referred to as Feammox. Feammox is a biological reaction, where Fe(III) is the electron acceptor, which is reduced to Fe(II), and NH4+ is the electron donor, which is oxidized to NO2-. An Acidimicrobiaceae bacterium named A6, a previously unreported species in the Acidimicrobiaceae family, has been identified as being responsible for the Feammox process(1, 2) Feammox process was noted in riparian wetland soils in New Jersey(1,3), in tropical rainforest soils in Puerto Rico (4) and in paddy soils in China (5). In addition to these published locations, Feammox process was also found in samples collected from a series of local wetland-, upland-, as well as storm-water detention pond-sediments in New Jersey, river sediments from South Carolina, and forested soils near an acid mine drainage (Dabaoshan, Guangdong province) in China. Using primers acm342f - 439r (2), Acidimicrobiaceae bacterium A6 was detected in samples where Feammox was observed, after strictly anaerobic incubations. According to a canonical correspondence analysis with environmental characteristics and soil microbial communities, the species-environment relationship indicated that pH and Fe oxides content were the primary factors controlling Feammox process. Anaerobic incubations of Feammox enrichment cultures adjusted to different pH, revealed that the optimal pH for Feammox is 4 ~ 5, and the reaction does not proceed when pH > 7. No correlation was found between the distributions of Feammox bacteria and other NH4+ oxidation bacteria. Pure Acidimicrobiaceae bacterium A6 strain was isolated in an autotrophic medium, from an active Feammox membrane reactor (A6 was enriched to 65.8% of the total bacteria). A 13C labeled CO2 amendment was conducted, and the 13C in cells of A6 increased from 1.80% to 10.3% after 14 days incubation. In a separate

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

    PubMed

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

    2013-11-19

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

  2. Solubility and speciation of atmospheric iron in buffer systems simulating cloud conditions

    NASA Astrophysics Data System (ADS)

    Upadhyay, Nabin; Majestic, Brian J.; Herckes, Pierre

    2011-04-01

    The solubility of iron (Fe) in atmospheric particulate matter (PM) is important to understand its chemistry and potential bioavailability to ocean phytoplankton. However, current studies on Fe solubility and its speciation are highly uncertain partly due to inconsistencies in analytical protocols. In this study, cloud-processing of atmospheric PM was simulated in acetate, formate, and oxalate buffers (pH = 4.30 ± 0.05) at 0.5, 1, 5, and 20 mM. Colorimetric analysis of Fe(II)-ferrozine complex showed that Fe solubility increased by an order of magnitude when acetate and formate concentrations increased from 0.5 mM to 5 mM, with a higher fraction of soluble Fe in acetate than in formate at lower buffer concentration (0.5 mM). Measured pH of sample extracts revealed that weak buffers are unable to maintain pH, presumably due to acidic or alkaline components of PM, requiring an optimum concentration (5 mM in this study) of acetate and formate for Fe solubility measurements. Similar extraction procedures revealed that oxalate buffer inhibits the formation of Fe(II)-ferrozine complex, especially with Fe(III)-containing solutions, rendering it unsuitable for Fe solubility measurements by Ferrozine method. Application of the optimized analytical method to PM samples from different environments showed quite variable Fe solubility, with the lowest (<1%) in dust-impacted samples and the highest (5%) in urban samples. The highest solubility (6.8%) was observed in ambient PM2.5 samples influenced by anthropogenic sources (car emissions) with more than 90% of soluble Fe in the form of Fe(II). Results from this study highlight the importance of the type and strength of buffer at a given pH for Fe solubility and provide further evidence of a higher Fe solubility in urban PM samples compared to desert dust.

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

    PubMed Central

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

    2013-01-01

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

  4. Constraints on Earth's inner core composition inferred from measurements of the sound velocity of hcp-iron in extreme conditions.

    PubMed

    Sakamaki, Tatsuya; Ohtani, Eiji; Fukui, Hiroshi; Kamada, Seiji; Takahashi, Suguru; Sakairi, Takanori; Takahata, Akihiro; Sakai, Takeshi; Tsutsui, Satoshi; Ishikawa, Daisuke; Shiraishi, Rei; Seto, Yusuke; Tsuchiya, Taku; Baron, Alfred Q R

    2016-02-01

    Hexagonal close-packed iron (hcp-Fe) is a main component of Earth's inner core. The difference in density between hcp-Fe and the inner core in the Preliminary Reference Earth Model (PREM) shows a density deficit, which implies an existence of light elements in the core. Sound velocities then provide an important constraint on the amount and kind of light elements in the core. Although seismological observations provide density-sound velocity data of Earth's core, there are few measurements in controlled laboratory conditions for comparison. We report the compressional sound velocity (V P) of hcp-Fe up to 163 GPa and 3000 K using inelastic x-ray scattering from a laser-heated sample in a diamond anvil cell. We propose a new high-temperature Birch's law for hcp-Fe, which gives us the V P of pure hcp-Fe up to core conditions. We find that Earth's inner core has a 4 to 5% smaller density and a 4 to 10% smaller V P than hcp-Fe. Our results demonstrate that components other than Fe in Earth's core are required to explain Earth's core density and velocity deficits compared to hcp-Fe. Assuming that the temperature effects on iron alloys are the same as those on hcp-Fe, we narrow down light elements in the inner core in terms of the velocity deficit. Hydrogen is a good candidate; thus, Earth's core may be a hidden hydrogen reservoir. Silicon and sulfur are also possible candidates and could show good agreement with PREM if we consider the presence of some melt in the inner core, anelasticity, and/or a premelting effect.

  5. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - I. Theoretical description

    NASA Astrophysics Data System (ADS)

    Ma, Weiguang; Silander, Isak; Hausmaninger, Thomas; Axner, Ove

    2016-01-01

    Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is conventionally described by an expression (here referred to as the CONV expression) that is restricted to the case when the single-pass absorbance, α0L, is much smaller than the empty cavity losses, π/F [here termed the conventional cavity-limited weak absorption (CCLWA) condition]. This limits the applicability of the technique, primarily its dynamic range and calibration capability. To remedy this, this work derives extended descriptions of Db NICE-OHMS that are not restricted to the CCLWA condition. First, the general principles of Db NICE-OHMS are scrutinized in some detail. Based solely upon a set of general assumptions, predominantly that it is appropriate to linearize the Beer-Lambert law, that the light is modulated to a triplet, and that the Pound-Drever-Hall sidebands are fully reflected, a general description of Db NICE-OHMS that is not limited to any specific restriction on α0L vs. π/F, here referred to as the FULL description, is derived. However, this description constitutes a set of equations to which no closed form solution has been found. Hence, it needs to be solved numerically (by iterations), which is inconvenient. To circumvent this, for the cases when α0L<π/F but without the requirement that the stronger CCLWA condition needs to be fulfilled, a couple of simplified extended expressions that are expressible in closed analytical form, referred to as the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT, have been derived. An analysis based on simulations validates the various descriptions and assesses to which extent they agree. It is shown that in the CCLWA limit, all extended descriptions revert to the CONV expression. The latter one deviates though from the extended ones for α0L around and above 0.1π/F. The two simplified extended descriptions agree

  6. Meal conditions affect the absorption of supplemental vitamin D3 but not the plasma 25-hydroxyvitamin D response to supplementation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is sometimes assumed that dietary fat is required for vitamin D absorption, although the impact of different amounts of dietary fat on vitamin D absorption is not established. This study was conducted to determine whether the presence of a meal and the fat content of the meal influences vitamin D...

  7. Conditional iron and pH-dependent activity of a non-enzymatic glycolysis and pentose phosphate pathway.

    PubMed

    Keller, Markus A; Zylstra, Andre; Castro, Cecilia; Turchyn, Alexandra V; Griffin, Julian L; Ralser, Markus

    2016-01-01

    Little is known about the evolutionary origins of metabolism. However, key biochemical reactions of glycolysis and the pentose phosphate pathway (PPP), ancient metabolic pathways central to the metabolic network, have non-enzymatic pendants that occur in a prebiotically plausible reaction milieu reconstituted to contain Archean sediment metal components. These non-enzymatic reactions could have given rise to the origin of glycolysis and the PPP during early evolution. Using nuclear magnetic resonance spectroscopy and high-content metabolomics that allowed us to measure several thousand reaction mixtures, we experimentally address the chemical logic of a metabolism-like network constituted from these non-enzymatic reactions. Fe(II), the dominant transition metal component of Archean oceanic sediments, has binding affinity toward metabolic sugar phosphates and drives metabolism-like reactivity acting as both catalyst and cosubstrate. Iron and pH dependencies determine a metabolism-like network topology and comediate reaction rates over several orders of magnitude so that the network adopts conditional activity. Alkaline pH triggered the activity of the non-enzymatic PPP pendant, whereas gentle acidic or neutral conditions favored non-enzymatic glycolytic reactions. Fe(II)-sensitive glycolytic and PPP-like reactions thus form a chemical network mimicking structural features of extant carbon metabolism, including topology, pH dependency, and conditional reactivity. Chemical networks that obtain structure and catalysis on the basis of transition metals found in Archean sediments are hence plausible direct precursors of cellular metabolic networks.

  8. Improving dewaterability of waste activated sludge by combined conditioning with zero-valent iron and hydrogen peroxide.

    PubMed

    Zhou, Xu; Wang, Qilin; Jiang, Guangming; Zhang, Xiwang; Yuan, Zhiguo

    2014-12-01

    Improvement of sludge dewaterability is crucial for reducing the costs of sludge disposal in wastewater treatment plants. This study presents a novel method based on combined conditioning with zero-valent iron (ZVI) and hydrogen peroxide (HP) at pH 2.0 to improve dewaterability of a full-scale waste activated sludge (WAS). The combination of ZVI (0-750mg/L) and HP (0-750mg/L) at pH 2.0 substantially improved the WAS dewaterability due to Fenton-like reactions. The highest improvement in WAS dewaterability was attained at 500mg ZVI/L and 250mg HP/L, when the capillary suction time of the WAS was reduced by approximately 50%. Particle size distribution indicated that the sludge flocs were decomposed after conditioning. Economic analysis showed that combined conditioning with ZVI and HP was a more economically favorable method for improving WAS dewaterability than the classical Fenton reaction based method initiated by ferrous salts and HP.

  9. Conditional iron and pH-dependent activity of a non-enzymatic glycolysis and pentose phosphate pathway

    PubMed Central

    Keller, Markus A.; Zylstra, Andre; Castro, Cecilia; Turchyn, Alexandra V.; Griffin, Julian L.; Ralser, Markus

    2016-01-01

    Little is known about the evolutionary origins of metabolism. However, key biochemical reactions of glycolysis and the pentose phosphate pathway (PPP), ancient metabolic pathways central to the metabolic network, have non-enzymatic pendants that occur in a prebiotically plausible reaction milieu reconstituted to contain Archean sediment metal components. These non-enzymatic reactions could have given rise to the origin of glycolysis and the PPP during early evolution. Using nuclear magnetic resonance spectroscopy and high-content metabolomics that allowed us to measure several thousand reaction mixtures, we experimentally address the chemical logic of a metabolism-like network constituted from these non-enzymatic reactions. Fe(II), the dominant transition metal component of Archean oceanic sediments, has binding affinity toward metabolic sugar phosphates and drives metabolism-like reactivity acting as both catalyst and cosubstrate. Iron and pH dependencies determine a metabolism-like network topology and comediate reaction rates over several orders of magnitude so that the network adopts conditional activity. Alkaline pH triggered the activity of the non-enzymatic PPP pendant, whereas gentle acidic or neutral conditions favored non-enzymatic glycolytic reactions. Fe(II)-sensitive glycolytic and PPP-like reactions thus form a chemical network mimicking structural features of extant carbon metabolism, including topology, pH dependency, and conditional reactivity. Chemical networks that obtain structure and catalysis on the basis of transition metals found in Archean sediments are hence plausible direct precursors of cellular metabolic networks. PMID:26824074

  10. Pulsed HF radiowave absorption measurements at 2.1 MHZ. over Delhi under quiet and solar flare conditions and related electron density height profiles

    NASA Astrophysics Data System (ADS)

    Balachandra Swamy, A. C.

    EXTENDED ABSTRACT Pulsed HF radiowave absorption measurements at 2.1 MHZ. over Delhi under quiet and solar flare conditions and related electron density height profiles A.C.Balachandra swmay & Late C.S.G.K. Setty Absorption of radio waves in the ionosphere is of great practical importance for radio communication and navigation systems. The first attempt to measure the absolute magnitude of the radiowave absorption were made by appletion and Ratcliffe (1930) using the frequency change method for medium frequency waves reflected from the E-region. They concluded from their experiment that the main part of the attenuation occurred below the reflection level and named the absorption region, D-region of the ionosphere. One of the basic properties of the ionosphere is the absorption of high Frequency Radiowaves. HF radiowave absorption results mainly from collisions between electrons (which are set into forced oscillations by the electric field of the wave) and neutral air particles, the RF energy abstracted from the wave being converted into thermal energy. The radiowave absorption in the ionosphere depends on electron density and collision frequency. The most important absorbing regions are the D-region and the lower E-region (50-100 Km.) The regular diurnal variation of the electron density in this height range is caused mainly by the changes in the depth of penetration of solar XUV radiations with solar zenith angle under quiet solar conditions. In 1937 Dellinger J.H.identified fade outs in high frequency radio circuits as due to abnormal ionospheric absorption associated with solar flares. The onset of the fade out was usually rapid and the duration was typically tens of minutes like that of the visible flare, because of the sudden onset, the immediate effects of solar flares are known collectively as sudden Ionospheric Disturbances (STD). The phenomenon discovered by Dellinger is usually called a short Wave Fadeout(SWF). Since the SWF is due to abnormal absorption

  11. Design Criteria, Operating Conditions, and Nickel-Iron Hydroxide Catalyst Materials for Selective Seawater Electrolysis.

    PubMed

    Dionigi, Fabio; Reier, Tobias; Pawolek, Zarina; Gliech, Manuel; Strasser, Peter

    2016-05-10

    Seawater is an abundant water resource on our planet and its direct electrolysis has the advantage that it would not compete with activities demanding fresh water. Oxygen selectivity is challenging when performing seawater electrolysis owing to competing chloride oxidation reactions. In this work we propose a design criterion based on thermodynamic and kinetic considerations that identifies alkaline conditions as preferable to obtain high selectivity for the oxygen evolution reaction. The criterion states that catalysts sustaining the desired operating current with an overpotential <480 mV in alkaline pH possess the best chance to achieve 100 % oxygen/hydrogen selectivity. NiFe layered double hydroxide is shown to satisfy this criterion at pH 13 in seawater-mimicking electrolyte. The catalyst was synthesized by a solvothermal method and the activity, surface redox chemistry, and stability were tested electrochemically in alkaline and near-neutral conditions (borate buffer at pH 9.2) and under both fresh seawater conditions. The Tafel slope at low current densities is not influenced by pH or presence of chloride. On the other hand, the addition of chloride ions has an influence in the temporal evolution of the nickel reduction peak and on both the activity and stability at high current densities at pH 9.2. Faradaic efficiency close to 100 % under the operating conditions predicted by our design criteria was proven using in situ electrochemical mass spectrometry.

  12. Structure of Iron at Giant-Planet and Exoplanet Interior Conditions

    NASA Astrophysics Data System (ADS)

    Godwal, B. K.; Jeanloz, R.

    2015-12-01

    Ab-initio molecular-dynamics (AIMD) and electronic-structure calculations using the density-functional approach show that the body-centered cubic (bcc) phase of Fe is mechanically unstable at conditions ranging from Earth's inner-core conditions (P ~ 360 GPa and T ~ 5500 K) up to pressures and temperatures of at least 1.5 TPa and 7000 K, conditions relevant to giant- and to many extrasolar-planet interiors. AIMD calculations for tetragonal distortions of Fe along the isochoric Bain path for densities of 18 and 20 g/cc at temperatures of 6000 and 7000 K indicate stresses becoming anisotropic for tetragonal distortions on either side of the lattice-parameter ratio c/a = 1, resulting in anisotropy in longitudinal stress, SL: SL > 0 for c/a < 1 and SL < 0 for c/a > 1, with SL ~ 0 within uncertainties for c/a = 1. The shear modulus BS becomes negative, violating the Born stability criterion. Variation of the longitudinal stress SL with free energy for the static lattice shows the same mechanical instability seen in the AIMD calculations, revealing the role of mechanical instability in causing the anomalies in SL. Also, based on free-energy calculations with temperature-dependent phonon and electron contributions, the hexagonal close-packed (hcp) phase of Fe is found to be the most stable for pressure-temperature conditions extending beyond those of Earth's inner core to the 1.5 TPa range.

  13. Inclusion of guava enhances non-heme iron bioavailability but not fractional zinc absorption from a rice-based meal in adolescents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Assessing the bioavailability of non-heme iron and zinc is essential for recommending diets that meet the increased growth-related demand for these nutrients. We studied the bioavailability of iron and zinc from a rice-based meal in 16 adolescent boys and girls, 13–15 y of age, from 2 government-run...

  14. Roles of iron species and pH optimization on sewage sludge conditioning with Fenton's reagent and lime.

    PubMed

    Yu, Wenbo; Yang, Jiakuan; Shi, Yafei; Song, Jian; Shi, Yao; Xiao, Jun; Li, Chao; Xu, Xinyu; He, Shu; Liang, Sha; Wu, Xu; Hu, Jingping

    2016-05-15

    Conditioning sewage sludge with Fenton's reagent could effectively improve its dewaterability. However, drawbacks of conditioning with Fenton's reagent are requirement of acidic conditions to prevent iron precipitation and subsequent neutralization with alkaline additive to obtain the pH of the filtrate close to neutrality. In this study, roles of pH were thoroughly investigated in the acidification pretreatment, Fenton reaction, and the final filtrate after conditioning. Through the response surface methodology (RSM), the optimal dosages of H2SO4, Fe(2+), H2O2, and lime acted as a neutralizer were found to be 0 (no acidification), 47.9, 34.3 and 43.2 mg/g DS (dry solids). With those optimal doses, water content of the dewatered sludge cakes could be reduced to 55.8 ± 0.6 wt%, and pH of the final filtrate was 6.6 ± 0.2. Fenton conditioning without initial acidification can simplify the conditioning process and reduce the usage of lime. The Fe(3+) content in the sludge cakes showed a close correlation with the dewaterability of conditioned sludge, i.e., the water content of sludge cakes, SRF (specific resistance to filtration), CST (capillary suction time), bound water content, and specific surface area. It indicated that the coagulation by Fe(3+) species in Fenton reaction could play an important role, compared to traditional Fenton oxidation effect on sludge conditioning. Thus, a two-step mechanism of Fenton oxidation and Fe(III) coagulation was proposed in sewage sludge conditioning. The mechanisms include the following: (1) extracellular polymeric substances (EPS) were firstly degraded into dissolved organics by Fenton oxidation; (2) bound water was converted to free water due to degradation of EPS; (3) the sludge particles were disintegrated into small ones by oxidation; (4) Fe(3+) generated from Fenton reaction acted as a coagulant to agglomerate smaller sludge particles into larger dense particles with less bond water; (5) finally, the dewatered

  15. Solid state diffusion in the lubricious film formation on iron by mixed tertiary butyl phenyl phosphates under static conditions

    NASA Astrophysics Data System (ADS)

    Shaeffer, Steven Kent

    The reaction between vaporous aryl phosphate esters and iron is known to yield a lubricious product film at high temperatures. The rate law exhibited in the growth of this film is consistent with a diffusion controlled process. In this work the actual movement of elements during this growth process was characterized using laminated metal foil samples consisting of a 1,000 A iron film deposited on a platinum substrate. The interface between the platinum and iron served as a reference datum against which the movement of the elements was observed. Iron was found to be the lone mobile element that diffuses through the product layer where it reacts with the vapor at the exposed surface generating more product. The change in the concentration profiles of the iron within the product served as a means to evaluate the diffusivity of the iron during the product growth. In this case the diffusivity of iron was found to be greater than its self diffusivity and within the range of values typical of iron oxide. This data in combination with the estimated activation energy for the process suggested that the diffusion was of a nature similar to the vacancy diffusion displayed in the oxidation of iron. The data suggests that the diffusion of iron through the product is the rate controlling step in the product growth process.

  16. Corrosion behavior of iron and nickel base alloys under solid oxide fuel cell exposure conditions

    SciTech Connect

    Ziomek-Moroz, M.; Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.

    2006-03-01

    Topography and phase composition of the scales formed on commercial ferritic stainless steels and experimental low CTE nickel-based alloys were studied in atmospheres simulating solid oxide fuel cell (SOFC) environments. The materials were studied under dual environment conditions with air on one side of the sample and carbon monoxide on the other side at 750°C. Surface characterization techniques, such as scanning electron microscopy and X-ray diffraction analysis were used in this study.

  17. Improved extraction method for the determination of iron, copper, and nickel in new varieties of sunflower oil by atomic absorption spectroscopy.

    PubMed

    Ansari, Rehana; Kazi, Tasneem G; Jamali, Mohammad K; Arain, Mohammad B; Sherazi, Syed T; Jalbani, Nusrat; Afridi, Hassan I

    2008-01-01

    A simple and fast procedure is proposed for the extraction of iron (Fe), copper (Cu), and nickel (Ni) in 16 varieties of sunflower seed oil samples using an ultrasonic bath. The experimental parameters of the ultrasonic-assisted extraction (UAE) method were optimized to improve the sensitivity and detect the metals at trace levels in minimum time. Conventional wet acid digestion method was used for comparative purposes. The optimum recovery of all 3 metals was obtained by UAE for 7 min, while the separation of aqueous and organic phases after extraction using centrifugation (UAE-2) required 3 min, as compared to the conventional equilibration method (UAE-1) that required 90 min. The respective recoveries of Cu, Fe, and Ni obtained with UAE-2 were in the range of 95.8-97.5, 93.5-98.3, and 95.6-98.2%, respectively, for different varieties of sunflower oil samples. Accuracy was determined by the standard addition method. Under the optimum operating conditions, the limits of detection obtained from the standard addition curves were 21.7, 20.4, and 35.6 ng/mL for Fe, Cu, and Ni, respectively. The fact that all varieties of sunflower oil contain significant amounts of Fe, Cu, and Ni indicates the deterioration of sunflower oil quality immediately after extraction from seeds, which poses a threat to oil quality and human health.

  18. Analysis of an Air Conditioning Coolant Solution for Metal Contamination Using Atomic Absorption Spectroscopy: An Undergraduate Instrumental Analysis Exercise Simulating an Industrial Assignment

    ERIC Educational Resources Information Center

    Baird, Michael J.

    2004-01-01

    A real-life analytical assignment is presented to students, who had to examine an air conditioning coolant solution for metal contamination using an atomic absorption spectroscopy (AAS). This hands-on access to a real problem exposed the undergraduate students to the mechanism of AAS, and promoted participation in a simulated industrial activity.

  19. Mediator subunit 16 functions in the regulation of iron uptake gene expression in Arabidopsis.

    PubMed

    Zhang, Yue; Wu, Huilan; Wang, Ning; Fan, Huajie; Chen, Chunlin; Cui, Yan; Liu, Hongfei; Ling, Hong-Qing

    2014-08-01

    Iron is an essential nutrient for plant growth and development, and its absorption is tightly controlled. Under iron limitation, FIT dimerizes with the four Ib bHLH proteins and activates the expression of iron uptake genes. However, how the dimerized complex activates downstream genes remains unclear. Using forward genetics, a low-iron-sensitive mutant was screened. The corresponding gene (MED16) was isolated, and its biological functions in iron homeostasis were characterized using approaches such as gene expression, protein subcellular localization, protein-protein interaction and chromatin immunoprecipitation assay. Lesion of MED16 significantly reduced FRO2 and IRT1 expression in Arabidopsis roots. The MED16 mutants showed a low shoot iron concentration and severe leaf chlorosis under iron limitation, whereas it grew normally as wild-type under iron sufficiency. Furthermore, we showed that MED16 interacted with FIT and improved the binding of the FIT/Ib bHLH complex to FRO2 and IRT1 promoters under iron-deficient conditions. Additionally, we found that many iron-deficient response genes, which are regulated by FIT, were also controlled by MED16. In conclusion, MED16 is involved in the iron deficiency response, and modulates the iron uptake gene expression under iron limitation. Our results increase the understanding of the molecular regulation mechanisms underlying iron uptake and homeostasis in plants.

  20. Formation conditions, chloride content, and stability of passive films on an iron-chromium alloy

    SciTech Connect

    Hubschmid, C.; Landolt, D. . Dept. des Materiaux)

    1993-07-01

    Passive films were formed on a high purity Fe-23 Cr alloy in acid sulfate solutions in the presence and absence of chloride ion. The resulting film composition was investigated by Auger depth profiling. The passivated samples were exposed to a 1M NaCl solution at a constant potential slightly above the critical pitting potential, and the current-time transient was measured in order to compare the relative stability of the different films. The results obtained suggest that the formation conditions influence the chloride content of the passive film and the breakdown behavior. Passive films formed in the presence of chloride contain and are slightly less stable towards breakdown. No chloride was found in films formed in sulfate and subsequently exposed to chloride well below the pitting potential.

  1. WATER-GAS SHIFT KINETICS OVER IRON OXIDE CATALYSTS AT MEMBRANE REACTOR CONDITIONS

    SciTech Connect

    Carl R.F. Lund

    2002-08-02

    The kinetics of water-gas shift were studied over ferrochrome catalysts under conditions with high carbon dioxide partial pressures, such as would be expected in a membrane reactor. The catalyst activity is inhibited by increasing carbon dioxide partial pressure. A microkinetic model of the reaction kinetics was developed. The model indicated that catalyst performance could be improved by decreasing the strength of surface oxygen bonds. Literature data indicated that adding either ceria or copper to the catalyst as a promoter might impart this desired effect. Ceria-promoted ferrochrome catalysts did not perform any better than unpromoted catalyst at the conditions tested, but copper-promoted ferrochrome catalysts did offer an improvement over the base ferrochrome material. A different class of water-gas shift catalyst, sulfided CoMo/Al{sub 2}O{sub 3} is not affected by carbon dioxide and may be a good alternative to the ferrochrome system, provided other constraints, notably the requisite sulfur level and maximum temperature, are not too limiting. A model was developed for an adiabatic, high-temperature water-gas shift membrane reactor. Simulation results indicate that an excess of steam in the feed (three moles of water per mole of CO) is beneficial even in a membrane reactor as it reduces the rate of adiabatic temperature rise. The simulations also indicate that much greater improvement can be attained by improving the catalyst as opposed to improving the membrane. Further, eliminating the inhibition by carbon dioxide will have a greater impact than will increasing the catalyst activity (assuming inhibition is still operative). Follow-up research into the use of sulfide catalysts with continued kinetic and reactor modeling is suggested.

  2. Relativistic Effects Around Black Holes: Smearing Absorption Edges

    NASA Technical Reports Server (NTRS)

    Zhang, X. L.; Feng, Y. X.; Zhang, S. N.; Yao, Y.

    2002-01-01

    Broad iron absorption structures have been observed in the X-ray spectra of both AGNs and black hole X-ray binaries (BHXBs). A correctly modeled absorption structure can reveal the physical condition of the source, help to determine the continuum spectra and thus help to estimate other spectral lifes more accurately. The absorption structures are usually thought to be caused by the reflection of X-rays by the accretion disks around the central black holes, and the broadening can be a ttributed to the ionization states of the disk and relativistic effects.

  3. A new method for evaluation of the resistance to rice kernel cracking based on moisture absorption in brown rice under controlled conditions

    PubMed Central

    Hayashi, Takeshi; Kobayashi, Asako; Tomita, Katsura; Shimizu, Toyohiro

    2015-01-01

    We developed and evaluated the effectiveness of a new method to detect differences among rice cultivars in their resistance to kernel cracking. The method induces kernel cracking under laboratory controlled condition by moisture absorption to brown rice. The optimal moisture absorption conditions were determined using two japonica cultivars, ‘Nipponbare’ as a cracking-resistant cultivar and ‘Yamahikari’ as a cracking-susceptible cultivar: 12% initial moisture content of the brown rice, a temperature of 25°C, a duration of 5 h, and only a single absorption treatment. We then evaluated the effectiveness of these conditions using 12 japonica cultivars. The proportion of cracked kernels was significantly correlated with the mean 10-day maximum temperature after heading. In addition, the correlation between the proportions of cracked kernels in the 2 years of the study was higher than that for values obtained using the traditional late harvest method. The new moisture absorption method could stably evaluate the resistance to kernel cracking, and will help breeders to develop future cultivars with less cracking of the kernels. PMID:26719740

  4. Mini-Column Ion-Exchange Separation and Atomic Absorption Quantitation of Nickel, Cobalt, and Iron: An Undergraduate Quantitative Analysis Experiment.

    ERIC Educational Resources Information Center

    Anderson, James L.; And Others

    1980-01-01

    Presents an undergraduate quantitative analysis experiment, describing an atomic absorption quantitation scheme that is fast, sensitive and comparatively simple relative to other titration experiments. (CS)

  5. Degradation of Monochlorinated and Nonchlorinated Aromatic Compounds under Iron-Reducing Conditions

    PubMed Central

    Kazumi, J.; Haggblom, M. M.; Young, L. Y.

    1995-01-01

    The capacity for Fe(sup3+) to serve as an electron acceptor in the microbial degradation of monochlorinated and nonchlorinated aromatic compounds was investigated in anoxic sediment enrichments. The substrates tested included phenol, benzoate, aniline, their respective monochlorinated isomers, o-, m-, and p-cresol, and all six dimethylphenol isomers. Phenol and 2-, 3-, and 4-chlorophenol were utilized by anaerobic microorganisms, with the concomitant reduction of Fe(sup3+) to Fe(sup2+). The amount of Fe(sup2+) produced in the enrichments was 89 to 138% of that expected for the stoichiometric degradation of these substrates to CO(inf2), suggesting complete mineralization at the expense of Fe reduction. Under Fe-reducing conditions, there was initial loss of benzoate and 3-chlorobenzoate but not of 2- or 4-chlorobenzoate. In addition, there was initial microbial utilization of aniline but not of the chloroaniline isomers. There was also initial loss of o-, m-, and p-cresol in our enrichments. None of the dimethylphenol isomers, however, was degraded within 300 days. Furthermore, we tested the capacity of an Fe-reducing, benzoate-grown culture of Geobacter metallireducens GS-15 to utilize monochlorinated benzoates and phenols. G. metallireducens was able to degrade benzoate and phenol but none of their chlorinated isomers, suggesting that the degradation of chlorophenols in our sediment enrichments may be due to novel Fe-reducing organisms that have yet to be isolated. PMID:16535169

  6. Iron and Nickel spectral opacity calculations in conditions relevant for pulsating stellar envelopes and experiments

    NASA Astrophysics Data System (ADS)

    Gilles, D.; Turck-Chièze, S.; Busquet, M.; Thais, F.; Loisel, G.; Piau, L.; Ducret, J. E.; Blenski, T.; Blancard, C.; Cossé, P.; Faussurier, G.; Gilleron, F.; Pain, J. C.; Porcherot, Q.; Guzik, J. A.; Kilcrease, D. P.; Magee, N. H.; Harris, J.; Bastiani-Ceccotti, S.; Delahaye, F.; Zeippen, C. J.

    2013-11-01

    Seismology of stars is strongly developing. To address this question we have formed an international collaboration, OPAC, to perform specific experimental measurements, compare opacity calculations, and improve the opacity calculations in stellar codes [1]. We consider the following opacity codes: SCO, CASSANDRA, STA, OPAS, LEDCOP, OP, SCO-RCG. Their comparison has shown large differences for Fe and Ni in equivalent conditions of envelopes of type II supernova precursors, temperatures between 15 and 40 eV and densities of a few mg/cm3 [2-4]. LEDCOP, OPAS, SCO-RCG structure codes and STA give similar results and differ from OP ones for the lower temperatures and for spectral interval values [3]. In this work we discuss the role of Configuration Interaction (CI) and the influence of the number of used configurations. We present and include in the opacity code comparisons new HULLAC-v9 calculations [5, 6] that include full CI. To illustrate the importance of this effect we compare different CI approximations (modes) available in HULLAC-v9 [7]. These results are compared to previous predictions and to experimental data. Differences with OP results are discussed.

  7. Results of microwave transmission and FMR absorption studies in iron-rich Metglas Fe/sub 82/B/sub 12/Si/sub 6/ at 9, 24, and 73 GHz

    SciTech Connect

    Cochran, J.F.; Myrtle, K.; Heinrich, B.

    1982-03-01

    We have carried out microwave measurements on an iron-rich Metglas at 9, 24, and 73 GHz. Two different techniques were used. FMR absorption measurements were made at 9, 24, and 73 GHz which allowed us to study the magnetic properties within a thin surface layer. FMAR transmission measurements at 73 GHz were also made which revealed some of the bulk properties of this material. It was found that the values of magnetic damping obtained from the FMR absorption measurements were significantly different from those obtained by FMAR transmission. We believe this difference is due to the insensitivity of the FMAR transmission measurements to microscopic inhomogeneities. The role of specimen treatment (annealing, polishing) was also investigated.

  8. Increasing concentrations of iron in surface waters as a consequence of reducing conditions in the catchment area

    NASA Astrophysics Data System (ADS)

    Ekström, Sara M.; Regnell, Olof; Reader, Heather E.; Nilsson, P. Anders; Löfgren, Stefan; Kritzberg, Emma S.

    2016-02-01

    Recent studies report trends of strongly increasing iron (Fe) concentrations in freshwaters. Since Fe is a key element with a decisive role in the biogeochemical cycling of major elements, it is important to understand the mechanisms behind these trends. We hypothesized that variations in Fe concentration are driven mainly by redox dynamics in hydraulically connected soils. Notably, Fe(III), which is the favored oxidation state except in environments where microbial activity provide strong reducing intensity, has several orders of magnitude lower water solubility than Fe(II). To test our hypothesis, seasonal variation in water chemistry, discharge, and air temperature was studied in three Swedish rivers. Methylmercury and sulfate were used as indicators of seasonal redox changes. Seasonal variability in water chemistry, discharge, and air temperature in the Emån and Lyckeby Rivers implied that the variation in Fe was primarily driven by the prevalence of reducing conditions in the catchment. In general, high Fe concentrations were observed when methylmercury was high and sulfate was low, indicative of reducing conditions. The Fe concentrations showed no or weak relationships with variations in dissolved organic matter concentration and aromaticity. The seasonal variation in Fe concentration of the Ume river was primarily dependent on timing of the snowmelt in high- versus low-altitude areas of the catchment. There were long-term trends of increasing temperature in all catchments and also trends of increasing discharge in the southern rivers, which should increase the probability for anaerobic conditions in space and time and thereby increase Fe transport to the aquatic systems.

  9. Comparison of experimental and modeled absorption enhancement by black carbon (BC) cored polydisperse aerosols under hygroscopic conditions.

    PubMed

    Shamjad, P M; Tripathi, S N; Aggarwal, S G; Mishra, S K; Joshi, Manish; Khan, Arshad; Sapra, B K; Ram, Kirpa

    2012-08-07

    The quantification of the radiative impacts of light absorbing ambient black carbon (BC) particles strongly depends on accurate measurements of BC mass concentration and absorption coefficient (β(abs)). In this study, an experiment has been conducted to quantify the influence of hygroscopic growth of ambient particles on light absorption. Using the hygroscopic growth factor (i.e., Zdanovskii-Stokes-Robinson (ZSR) approach), a model has been developed to predict the chemical composition of particles based on measurements, and the absorption and scattering coefficients are derived using a core-shell assumption with light extinction estimates based on Mie theory. The estimated optical properties agree within 7% for absorption coefficient and 30% for scattering coefficient with that of measured values. The enhancement of absorption is found to vary according to the thickness of the shell and BC mass, with a maximum of 2.3 for a shell thickness of 18 nm for the particles. The findings of this study underline the importance of considering aerosol-mixing states while calculating their radiative forcing.

  10. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds under Lap Shear Loading Conditions

    SciTech Connect

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2008-06-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS) under lap shear loading condition. DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. Static weld strength tests using lap shear samples were performed on the joint populations with various fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with conventionally required fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 welds under lap shear loading. Moreover, failure mode has strong influence on weld peak load and energy absorption for all the DP800 welds and the TRIP800 small welds: welds failed in pullout mode have statistically higher strength and energy absorption than those failed in interfacial fracture mode. For TRIP800 welds above the critical fusion zone level, the influence of weld failure modes on peak load and energy absorption diminishes. Scatter plots of peak load and energy absorption versus weld fusion zone size were then constructed, and the results indicate that fusion zone size is the most critical factor in weld quality in terms of peak load and energy absorption for both DP800 and TRIP800 spot welds.

  11. Conditions and mechanism for the formation of iron-rich Montmorillonite in deep sea sediments (Costa Rica margin): Coupling high resolution mineralogical characterization and geochemical modeling

    NASA Astrophysics Data System (ADS)

    Charpentier, D.; Buatier, M. D.; Jacquot, E.; Gaudin, A.; Wheat, C. G.

    2011-03-01

    Iron-rich smectite is commonly described in the diagenetic fraction of deep-sea sediment, as millimeter to centimeter aggregates dispersed in the sediment, or as a coating on sedimentary particles or nodules. This study examines several factors to elucidate formation mechanisms of a particular iron-rich smectite and its potential transformation to glauconite. The study combines a detailed mineralogical investigation on natural samples and a chemical modeling approach to assess mineralogical reactions and pathways. Transmission electron microscopy (TEM) observations and analytical electron microscopy (TEM-AEM) analyses were conducted on microtomed samples of millimeter- to centimeter-long green grains. These grains are widespread in pelagic calcareous sediment from the Costa Rica margin. They are composed of pyrites that are partially dissolved and are surrounded by amorphous or very poorly crystallized iron-rich particles. Iron-rich montmorillonite grows from an amorphous precursor and its formation requires the input of Si, O, Mg, K, Na and Ca; our results suggest that these inputs are supported by the dissolution of sedimentary phases such as volcanic glasses, siliceous fossils and silicates. Thermodynamic modeling of fluid-sediment interactions was conducted with the geochemical computer code PhreeqC, using mineralogical and pore fluid compositions from sediment samples and calculated estimates for thermodynamic constants of smectites that are not maintained by the computer code. Simulations confirm the possibility that the green grains are the product of pyrite alteration by seawater under oxidizing conditions. The extent of smectite production is controlled by the kinetics of pyrite dissolution and fluid migration. The absence of aluminum in the Costa Rica margin system explains the formation of an iron-rich montmorillonite instead of glauconite, whereas the presence of calcite that buffers the system explains the formation of an iron-rich montmorillonite

  12. Reduced mass absorption cross section of black carbon under an extremely polluted condition in southern suburb of Beijing, China

    NASA Astrophysics Data System (ADS)

    Wang, J.; Wang, S.; Hua, Y.; Jiang, J.; Zhao, B.; Xing, J.; Jiang, S.; Cai, R.; Hao, J.

    2015-12-01

    Black carbon (BC), as one of the most important climate-warming agent, has been the focus of extensive studies in recent years. Mass absorption cross section (MAC) is a key parameter to assess the radiative forcing by linking the mass concentration with the radiation effect. In this study, we conducted a two-month field campaign in Beijing, the capital city of China, in a October and November, a period that severe PM2.5 pollution occurred. PM2.5 offline samples were collected daily onto quartz fiber filters by a Partisol 2300 Speciation Sampler. Size-segregated aerosol samples of the size ranged from 0.056 - 10 µm with 11 bins were collected onto quartz fiber filters by a cascade impactor developed by National Chiao Tung University (NCTU). A DRI Model 2001 thermal/optical carbon analyzer were used to analyze the samples. The MAC of BC is measured by a thermal-optical carbon analyzer. In contrast to previous studies, we found that after "shadow effect" has been corrected, the MAC is reduced from 14 m2/g to 5 m2/g with the increase of BC concentrations. There was no significant correlation between MAC with secondary inorganic aerosols. Such unexpected reduction in MAC of BC is possibly associated with the microphysical property of BC modulated under serious pollution condition. The study of size-segregated species concentrations shows that the size distribution of BC is unimodal, with the peak around 0.56-1.8 µm. The results also show the proportion of BC larger than 0.56 µm is significant increased. Additionally, "soot superaggregate", as distinct from conventional sub-micron aggregates, was found in the bins of BC with size ranged from 1 to1.8 µm. Such high carbon aerosol proportion and large BC size distribution suggests that emissions from residential biomass burning is dominant during this episode. This study suggests that the optical property for BC from different emission sectors should be considered in the estimation of radiative forcing.

  13. Impact of iron-reducing bacteria on the corrosion rate of carbon steel under simulated geological disposal conditions.

    PubMed

    Schütz, Marta K; Schlegel, Michel L; Libert, Marie; Bildstein, Olivier

    2015-06-16

    The current projects for the disposal of high-level radioactive waste rely on underground burial and confinement by metallic envelopes that are susceptible to corrosion processes. The impact of microbial activity must be fully clarified in order to provide biological parameters for predictive reactive transport models. This study investigates the impact of hydrogenotrophic iron-reducing bacteria (Shewanella oneidensis strain MR-1) on the corrosion rate of carbon steel under simulated geological disposal conditions by using a geochemical approach. It was found that corrosion damage changes mostly according to the experimental solution (i.e., chemical composition). Magnetite and vivianite were identified as the main corrosion products. In the presence of bacteria, the corrosion rate increased by a factor of 1.3 (according to weight loss analysis) to 1.8 (according to H2 measurements), and the detected amount of magnetite diminished. The mechanism likely to enhance corrosion is the destabilization and dissolution of the passivating magnetite layer by reduction of structural Fe(III) coupled to H2 oxidation.

  14. Erosive Wear Behavior of Nickel-Based High Alloy White Cast Iron Under Mining Conditions Using Orthogonal Array

    NASA Astrophysics Data System (ADS)

    Yoganandh, J.; Natarajan, S.; Babu, S. P. Kumaresh

    2013-09-01

    Nihard Grade-4, a nickel-bearing cast iron widely used in slurry pumps and hydrodynamic components, is evaluated for its erosive wear response under mining conditions using a statistical approach. Experiments were conducted by varying the factors namely velocity, slurry concentration, angle of impingement, and pH in three levels, using L9 orthogonal array. Analysis of variance was used to rank the factors influencing erosive wear. The results indicate that velocity is the most influencing factor followed by the angle of impingement, slurry concentration, and pH. Interaction effects of velocity, slurry concentr