WorldWideScience

Sample records for iron absorption electronic

  1. Iron absorption studies

    International Nuclear Information System (INIS)

    Ekenved, G.

    1976-01-01

    The main objective of the present work was to study iron absorption from different iron preparations in different types of subjects and under varying therapeutic conditions. The studies were performed with different radioiron isotope techniques and with a serum iron technique. The preparations used were solutions of ferrous sulphate and rapidly-disintegrating tablets containing ferrous sulphate, ferrous fumarate and ferrous carbonate and a slow-release ferrous sulphate tablet of an insoluble matrix type (Duroferon Durules). The serum iron method was evaluated and good correlation was found between the serum iron response and the total amount of iron absorbed after an oral dose of iron given in solution or in tablet form. New technique for studying the in-vivo release properties of tablets was presented. Iron tablets labelled with a radio-isotope were given to healthy subjects. The decline of the radioactivity in the tablets was followed by a profile scanning technique applied to different types of iron tablets. The release of iron from the two types of tablets was shown to be slower in vivo than in vitro. It was found that co-administration of antacids and iron tablets led to a marked reduction in the iron absorption and that these drugs should not be administered sumultaneously. A standardized meal markedly decreased the absorbability of iron from iron tablets. The influence of the meal was more marked with rapidly-disintegrating than with slow-release ferrous sulphate tablets. The absorption from rapidly-disintegrating and slow-release ferrous sulphate tablets was compared under practical clinical conditions during an extended treatment period. The studies were performed in healthy subjects, blood donors and patients with iron deficiency anaemia and it was found that the absorption of iron from the slow-release tablets was significantly better than from the rapidly-disintegrating tablets in all three groups of subjects. (author)

  2. Iron absorption in relation to iron status

    International Nuclear Information System (INIS)

    Magnusson, B.; Bjoern-Rasmussen, E.; Hallberg, L.; Rossander, L.

    1981-01-01

    The absorption from a 3 mg dose of ferrous iron was measured in 250 male subjects. The absorption was related to the log concentration of serum ferritin in 186 subjects of whom 99 were regular blood donors (r= -0.76), and to bone marrow haemosiderin grading in 52 subjects with varying iron status. The purpose was to try and establish a percentage absorption from such a dose that is representative of subjects who are borderline iron deficient. This information is necessary for food iron absorption studies in order (1) to calculate the absorption of iron from the diet at a given iron status and (2) compare the absorption of iron from different meals studied in different groups of subjects by different investigarors. The results suggest that an absorption of about 40% of a 3 mg reference dose of ferrous iron is given in a fasting state, roughly corresponds to the absorption in borderline-iron-deficient subjects. The results indicate that this 40% absorption value corresponds to a serum ferritin level of 30 μg/l and that food iron absorption in a group of subjects should be expressed preferably as the absorption corresponding to a reference-dose absorption of 45%, or possibly a serum ferritin level of 30 μg/l. (author)

  3. Electron energy-loss spectroscopy characterization and microwave absorption of iron-filled carbon-nitrogen nanotubes

    International Nuclear Information System (INIS)

    Che Renchao; Liang Chongyun; Shi Honglong; Zhou Xingui; Yang Xinan

    2007-01-01

    Iron-filled carbon-nitrogen (Fe/CN x ) nanotubes and iron-filled carbon (Fe/C) nanotubes were synthesized at 900 deg. C through a pyrolysis reaction of ferrocene/acetonitrile and ferrocene/xylene, respectively. The differences of structure and composition between the Fe/CN x nanotubes and Fe/C nanotubes were investigated by transmission electron microscopy and electron energy-loss spectroscopy (EELS). It was found that the morphology of Fe/CN x nanotubes is more corrugated than that of the Fe/C nanotubes due to the incorporation of nitrogen. By comparing the Fe L 2,3 electron energy-loss spectra of Fe/CN x nanotubes to those of the Fe/C nanotubes, the electron states at the interface between Fe and the tubular wall of both Fe/CN x nanotubes and Fe/C nanotubes were investigated. At the boundary between Fe and the wall of a CN x nanotube, the additional electrons contributed from the doped 'pyridinic-like' nitrogen might transfer to the empty 3d orbital of the encapsulated iron, therefore leading to an intensity suppression of the iron L 2,3 edge and an intensity enhancement of the carbon K edge. However, such an effect could not be found in Fe/C nanotubes. Microwave absorption properties of both Fe/CN x and Fe/C nanocomposites at 2-18 GHz band were studied

  4. Phytases for Improved Iron Absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Nyffenegger, Christian; Meyer, Anne S.

    2014-01-01

    Microbial phytases (EC 3.1.3.8) catalyse dephosphorylation of phytic acid, which is the primary storage compound for phosphorous in cereal kernels. The negatively charged phosphates in phytic acid chelate iron (Fe3+) and thus retards iron bioavailability in humans 1. Supplementation of microbial...... phytase can improve iron absorption from cereal-based diets 2. In order for phytase to catalyse iron release in vivo the phytase must be robust to low pH and proteolysis in the gastric ventricle. Our work has compared the robustness of five different microbial phytases, evaluating thermal stability...

  5. Phytases for improved iron absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Meyer, Anne S.

    2016-01-01

    Phytase enzymes present an alternative to iron supplements, because they have been shown to improve iron absorption by means of catalysing the degradation of a potent iron absorption inhibitor: phytic acid. Phytic acid is a hexaphosphate of inositol and is particularly prevalent in cereal grains......, where it serves as a storage molecule for phosphorous. Phytic acid is also associated with minerals. The minerals are bound by chelation to the negatively charged phosphate groups in phytic acid. Phytases catalyse the dephosphorylation of phytic acid, thus releasing bound minerals to make them available...... for absorption. This article presents research on phytase catalysis in gastric conditions and considers potential benefits and drawbacks for using phytases as a food supplement....

  6. Absorption of medicamental iron and iron from food

    International Nuclear Information System (INIS)

    Reizenstein, P.; Carlmark, B.; Ehn, L.; Forsberg, K.; Hoeglund, S.; Terpstra, T.

    1976-01-01

    Methods are reviewed for the measurement of iron absorption. The chemical balance method has been almost entirely supplanted by radioisotope methods, which include notably whole-body counting and measurement of incorporation of radioiron into red cells. A survey is also given of the various conditions that influence iron absorption, including chemical form of iron, amount of iron, accompanying diet. Absorption tests must be conducted under relevant conditions. (author)

  7. Absorption of controlled-release iron

    International Nuclear Information System (INIS)

    Cook, J.D.; Lipschitz, D.A.; Skikne, B.S.

    1982-01-01

    A multiple-dose double radioiron technic was used to compare absorption of iron administered as a controlled release (CR) capsule and as an elixir; both formulations contained 50 mg elemental iron as ferrous sulfate. When taken by normal subjects in the fasting state, mean absorption from the elixir and CR capsule averaged 4.92% and 4.38%, which gave a CR capsule:elixir ratio of 0.89. This difference was not significant, but when taken with meals that inhibit absorption of dietary iron by different degrees, absorption of the CR formulation was superior. CR capsule:elixir absorption ratios averaged 1.70 from a meal that is mildly inhibitory and 3.13 from a meal that causes more marked inhibition. It is concluded that CR iron formulations may offer a therapeutic advantage to patients who take oral iron with meals to avoid gastrointestinal side effects

  8. Bioavailability & absorption of Iron and Anemia

    Directory of Open Access Journals (Sweden)

    Radhika Kapil

    2018-01-01

    Full Text Available Humans derive iron from their everyday diet, predominantly from plant foods and the rest from foods of animal origin. Iron is found in food as either haem or non-haem iron.  Haem iron, which is about up to 40 per cent of the iron in meat, poultry, and fish, is well absorbed.  All the iron in plants (fruits, vegetables, grains, nuts is in the form of non-haem iron and is relatively poorly absorbed. Non-haem iron contributes about 90-95 per cent of total daily iron in vegan diets. In western countries,the intake of haem iron from meat and meat products accounts for bulk of the dietary iron. The haem iron consumption is minimal in developing countries with majority obtaining non-haem iron from cereals, pulses, vegetables and fruits'. The diets is plagued by low iron content and poor absorption. Major sources of non-haem iron are plant foods. The iron is chemically diverse, ranging from simple iron oxides and salts to more complex organic chelates such as hydroxyphosphates in phytoferritin(1.

  9. Bioavailability & absorption of Iron and Anemia

    Directory of Open Access Journals (Sweden)

    Radhika Kapil

    2017-12-01

    Full Text Available Humans derive iron from their everyday diet, predominantly from plant foods and the rest from foods of animal origin. Iron is found in food as either haem or non-haem iron.  Haem iron, which is about up to 40 per cent of the iron in meat, poultry, and fish, is well absorbed.  All the iron in plants (fruits, vegetables, grains, nuts is in the form of non-haem iron and is relatively poorly absorbed. Non-haem iron contributes about 90-95 per cent of total daily iron in vegan diets. In western countries,the intake of haem iron from meat and meat products accounts for bulk of the dietary iron. The haem iron consumption is minimal in developing countries with majority obtaining non-haem iron from cereals, pulses, vegetables and fruits'. The diets is plagued by low iron content and poor absorption. Major sources of non-haem iron are plant foods. The iron is chemically diverse, ranging from simple iron oxides and salts to more complex organic chelates such as hydroxyphosphates in phytoferritin(1.

  10. Iron absorption from adequate Filipinos meals

    International Nuclear Information System (INIS)

    Trinidad, T.P.; Madriaga, J.R.; Valdez, D.H.; Cruz, E.M.; Mallillin, A.C.; Sison, C.C.; Kuizon, M.D.

    1989-01-01

    Iron absorption from adequate Filipino meals representing the three major island groups of the Philippines (Luzon, Visayas, and Mindanao) was studied using double isotope extrinsic tag method. Mean iron absorption of the one-day meal for Metro Manila was 6.6 +- 1.26%. Central Visayas, 6.3 +- 1.15% and Southern Mindanao, 6.4 +- 1.19%. Comparison between meals (breakfast, lunch, dinner) for each region as well as one-day meal for the three regions showed no significant differences (P>0.01). Correlation tests done between iron absorption and the following iron enhancers: ascorbic acid, amount of fish, meat or poultry; and inhibitors: phytic acid and tannic acid, did not give significant results. The overall average of 6.4 +- 1.20% may be used as the iron absorption level from an adequate Filipino meal. This value can be considered as one of the bases for arriving at recommended dietary allowances for iron among Filipinos instead of the 10% iron absorption assumed in 1976. (Auth.). 21 refs.; 3 tabs.; 3 annexes

  11. Iron absorption from adequate Filipino meals

    International Nuclear Information System (INIS)

    Trinidad, T.P.; Madriaga, J.R.; Valdez, D.H.; Cruz, E.M.; Mallillin, A.C.; Sison, C.C.; Kuizon, M.D.

    1991-01-01

    Iron absorption from adequate Filipino meals representing the three major island groups of the Philippines (Luzon, Visayas and Mindanao) was studied using double isotope extrinsic tag method. Mean iron absorption of the one-day meal for Metro Manila was 6.6 ± 1.26%, Central Visayas, 6.3 ± 1.15% and Southern Mindanao, 6.4 ± 1.19%. Comparison between meals (breakfast, lunch, dinner) for each region as well as one-day meal for the three regions showed no significant differences (P > .01). Correlation tests done between iron absorption and the following iron enhancers: ascorbic acid, amount of fish, meat or poultry and inhibitors: phytic acid and tannic acid did not give significant results. The overall bar x of 6.4 ± 1.20% may be used as the non-heme iron absorption level from an adequate Filipino meal. This value can be considered as one of the bases for arriving at recommended dietary allowances for iron among Filipinos instead of the 10% iron absorption assumed in 1976

  12. Iron absorption after antrectomy with gastroduodenostomy

    International Nuclear Information System (INIS)

    Magnusson, B.E.O.

    1976-01-01

    Haematological values were studied in 177 unselected patients 3-6 years after antrectomy with gastroduodenostomy. The majority (76%) had been operated upon for duodenal ulcer, 20% for gastric ulcer and the remaining patients had had both a duodenal and a gastric ulcer before the operation. In 65 patients a vagotomy had been added to the resection. 10% of the males and 15% of the females had a haemoglobin concentration below 13.0 or 12.0 g/100 ml, respectively. The corresponding frequencies for iron defifiency, defined as absence or only traces of haemosiderin in bone marrow smears, were 7% and 15%. The absorption of a small test dose of inorganic iron (0.56 mg Fe ++ as ferrous ascorbate) was studied in all the antrectomized patients. The absorption was also investigated in normal men and in patients who had had a Billroth II partial gastrectomy. No malabsorption of inorganic iron could be found in any of the groups. An inverse relationship between iron absorption and the grading of haemosiderin in bone marrow smears was found in normal subjects as well as in operated patients. Thus, an adequate increase of the absorption of ferrous iron was found even in operated patients with iron deficiency. Gastric acid secretion, measured as the peak acid output (PAO) after stimulation, was determined in all antrectomized patients. In patients having the same grading of haemosiderin (grade II) a slight but significant positive correlation was found between PAO and the absorption from the test dose (Fe ++ ). The absorption of food iron from a composite meal and the absorption from an iron salt (3.0 mg Fe ++ as ferrous ascorbate) was studied in 4 different groups: 1) normal males, 2) non-operated patients with peptic ulcer, 3) antrectomized patients with gastroduodenostomy and 4) patients operated upon with Billroth II partial gastrectomy. The range and mean absorption values from the test dose of inorganic iron were about the same in all groups. The absorption of food iron

  13. Protein Hydrolysates as Promoters of Non-Haem Iron Absorption

    Science.gov (United States)

    Li, Yanan; Jiang, Han; Huang, Guangrong

    2017-01-01

    Iron (Fe) is an essential micronutrient for human growth and health. Organic iron is an excellent iron supplement due to its bioavailability. Both amino acids and peptides improve iron bioavailability and absorption and are therefore valuable components of iron supplements. This review focuses on protein hydrolysates as potential promoters of iron absorption. The ability of protein hydrolysates to chelate iron is thought to be a key attribute for the promotion of iron absorption. Iron-chelatable protein hydrolysates are categorized by their absorption forms: amino acids, di- and tri-peptides and polypeptides. Their structural characteristics, including their size and amino acid sequence, as well as the presence of special amino acids, influence their iron chelation abilities and bioavailabilities. Protein hydrolysates promote iron absorption by keeping iron soluble, reducing ferric iron to ferrous iron, and promoting transport across cell membranes into the gut. We also discuss the use and relative merits of protein hydrolysates as iron supplements. PMID:28617327

  14. Protein Hydrolysates as Promoters of Non-Haem Iron Absorption

    Directory of Open Access Journals (Sweden)

    Yanan Li

    2017-06-01

    Full Text Available Iron (Fe is an essential micronutrient for human growth and health. Organic iron is an excellent iron supplement due to its bioavailability. Both amino acids and peptides improve iron bioavailability and absorption and are therefore valuable components of iron supplements. This review focuses on protein hydrolysates as potential promoters of iron absorption. The ability of protein hydrolysates to chelate iron is thought to be a key attribute for the promotion of iron absorption. Iron-chelatable protein hydrolysates are categorized by their absorption forms: amino acids, di- and tri-peptides and polypeptides. Their structural characteristics, including their size and amino acid sequence, as well as the presence of special amino acids, influence their iron chelation abilities and bioavailabilities. Protein hydrolysates promote iron absorption by keeping iron soluble, reducing ferric iron to ferrous iron, and promoting transport across cell membranes into the gut. We also discuss the use and relative merits of protein hydrolysates as iron supplements.

  15. Measurement of iron absorption from meals contaminated with iron

    International Nuclear Information System (INIS)

    Hallberg, L.; Bjoern-Rasmussen, E.

    1981-01-01

    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

  16. Electronic Structure from Iron L-edge Spectroscopy : An Example of Spin Transition Evidenced by Soft X-ray Absorption Spectroscopy

    NARCIS (Netherlands)

    Cartier dit Moulin, Ch.; Flank, A.M.; Rudolf, P.; Chen, C.T.

    1993-01-01

    Soft X-ray Absorption Spectroscopy at the transition metal L2,3 edges provides information about the 3d unoccupied states by dipole allowed transitions. We have recorded iron L2,3 edges in order to follow the reversible thermal spin interconversion (S=2 S=0) of the Fe(II)(o-phenantroline)2(NCS)2.

  17. Microanalysis of iron oxidation state in iron oxides using X Ray Absorption Near Edge Structure (XANES)

    Science.gov (United States)

    Sutton, S. R.; Delaney, J.; Bajt, S.; Rivers, M. L.; Smith, J. V.

    1993-01-01

    An exploratory application of x ray absorption near edge structure (XANES) analysis using the synchrotron x ray microprobe was undertaken to obtain Fe XANES spectra on individual sub-millimeter grains in conventional polished sections. The experiments concentrated on determinations of Fe valence in a suite of iron oxide minerals for which independent estimates of the iron speciation could be made by electron microprobe analysis and x ray diffraction.

  18. Iron, lead, and cobalt absorption: similarities and dissimilarities

    International Nuclear Information System (INIS)

    Barton, J.C.; Conrad, M.E.; Holland, R.

    1981-01-01

    Using isolated intestinal segments in rats, the absorption of iron, lead, and cobalt was increased in iron deficiency and decreased in iron loading. Similarly, the absorption of these metals was decreased in transfusional erythocytosis, after intravenous iron injection and after parenteral endotoxin injection. Acute bleeding or abbreviated intervals of dietary iron deprivation resulted in increased iron absorption from isolated intestinal segments and in intact animals, while the absorption of lead and cobalt was unaffected. These results suggest that the specificity of the mucosal metal absorptive mechanism is either selectively enhanced for iron absorption by phlebotomy or brief periods of dietary iron deprivation, or that two or more mucosal pathways for iron absorption may exist

  19. Absorption of plutonium in the iron-deficient rat

    International Nuclear Information System (INIS)

    Ragan, H.A.

    1977-01-01

    Iron deficiency did not enhance absorption of plutonium following intragastric gavage of rats. Absorption of plutonium citrate in both control and iron-deficient rats was about 0.03% of the administered dose

  20. Effects of divalent amino acids on iron absorption

    International Nuclear Information System (INIS)

    Christensen, J.M.; Ghannam, M.; Ayres, J.W.

    1984-01-01

    Solutions of each of 10 amino acids or ascorbic acid were mixed with iron and orally administered to rats. Iron was absorbed to a statistically significantly greater extent when mixed with asparagine, glycine, serine, or ascorbic acid as compared with a control solution of iron. The largest effects were for asparagine and glycine, which also increased iron absorption to a significantly greater extent than did serine or ascorbic acid. No statistically significant increase in iron absorption occurred when any of the other amino acids was mixed with iron. The extent of iron absorption from each test solution, as measured by area under the concentration of iron-59 in the blood-time curve (r2 . 0.0002), and the initial rate of iron absorption for each test solution (r2 . 0.01) showed no correlation with the stability constant of the amino acid-iron complex

  1. Iron metabolism in experimental rickets. Pt. 1. Intestinal absorption of iron in rat rickets

    International Nuclear Information System (INIS)

    Pronicka, E.

    1975-01-01

    Investigations were carried out on iron 59 Fe absorption in rats with experimental rickets. It was found that rats with rickets as compared with controls do not show any significant differences in the degree of iron absorption in fasting state. The percent of absorbed iron increases when it is administered after previous feeding of rats. A greater rise in iron absorption after feeding was shown also by rats with rickets. On the other hand, administration of a shock dose of vitamin D at the time of rickets development causes after 7 days a significant decrease in total iron absorption given to fed rats. An excess of calcium in the diet of rats does not seem to impair directly the absorption of iron. The possibility of the causative effect of vitamin D deficiency on the composition of intestinal contents on changes in the degree of iron absorption observed after feeding of rats with rickets, is discussed. (author)

  2. Iron metabolism in experimental rickets. I. Intestinal absorption of iron in rat rickets

    Energy Technology Data Exchange (ETDEWEB)

    Pronicka, E [Pomorska Akademia Medyczna, Szczecin (Poland)

    1975-01-01

    Investigations were carried out on iron /sup 59/Fe absorption in rats with experimental rickets. It was found that rats with rickets as compared with controls do not show any significant differences in the degree of iron absorption in fasting state. The percent of absorbed iron increases when it is administered after previous feeding of rats. A greater rise in iron absorption after feeding was shown also by rats with rickets. On the other hand, administration of a shock dose of vitamin D at the time of rickets development causes after 7 days a significant decrease in total iron absorption given to fed rats. An excess of calcium in the diet of rats does not seem to impair directly the absorption of iron. The possibility of the causative effect of vitamin D deficiency on the composition of intestinal contents on changes in the degree of iron absorption observed after feeding of rats with rickets, is discussed.

  3. Absorption from iron tablets given with different types of meals.

    Science.gov (United States)

    Hallberg, L; Björn-Rasmussen, E; Ekenved, G; Garby, L; Rossander, L; Pleehachinda, R; Suwanik, R; Arvidsson, B

    1978-09-01

    The absorption of iron from tablets given with 5 types of meals was studied in 153 subjects. The meals were: a hamburger meal with beans and potatoes, a simple breakfast meal, a Latin American meal composed of black beans, rice and maize and two Southeast Asian meals composed of rice, vegetables and spices served with and without fish. The groups were directly compared by relating the absorption from the iron tablets to the absorption from a standardized reference dose of iron given on an empty stomach. The composition of meals with respect to content of meat or fish or the presence of large amounts of phytates seemed to have no influence on the absorption of iron from tablets. The absorption from iron tablets was about 40% higher when they were given with rice meals than when they were given with the other meals studied. The average decrease in absorption by meals was about 50-60% based on a comparison when tablets were given on an empty stomach. When tablets from which the iron was released more slowly were used, the absorption increased by about 30% except when they were given with rice meals, where the absorption was unchanged. The differences among the meals in their effect on the absorption of iron from tablets thus disappeared when the slow-release tablets were given.

  4. Absorption from iron tablets given with different types of meals

    Energy Technology Data Exchange (ETDEWEB)

    Hallberg, L; Bjoern-Rasmussen, E; Ekenved, G; Garby, L; Rossander, L; Pleehachinda, R; Suwanik, R; Arvidsson, B

    1978-01-01

    The absorption from iron tablets given with 5 types of meals was studied in 153 subjects. The meals were: a hamburger meal with beans and potatoes, a simple breakfast meal, a Latin American meal composed of black beans, rice and maize and two Southeast Asian meals composed of rice, vegetables, and spices served with and without fish. The groups were directly compared by relating the absorption from the iron tablets to the absorption from a standardized reference dose of iron given on an empty stomach. The composition of meals with respect to content of meat or fish or the presence of large amounts of phytates seemed to have no influence on the absorption of iron from tablets. The absorption from iron tablets was about 40% higher when they were given with rice meals than when they were given with the other meals studied. The average decrease in absorption by meals was about 50-60% based on a comparison when tablets were given on an empty stomach. When tablets from which the iron was released more slowly were used, the absorption increased by about 30% except when they were given with rice meals, where the absorption was unchanged. The differences among the meals in their effect on the absorption of iron from tablets thus disappeared when the slow-release tablets were given.

  5. Absorption from iron tablets given with different types of meals

    International Nuclear Information System (INIS)

    Hallberg, L.; Bjoern-Rasmussen, E.; Ekenved, G.; Garby, L.; Rossander, L.; Pleehachinda, R.; Suwanik, R.; Arvidsson, B.

    1978-01-01

    The absorption from iron tablets given with 5 types of meals was studied in 153 subjects. The meals were: a hamburger meal with beans and potatoes, a simple breakfast meal, a Latin American meal composed of black beans, rice and maize and two Southeast Asian meals composed of rice, vegetables, and spices served with and without fish. The groups were directly compared by relating the absorption from the iron tablets to the absorption from a standardized reference dose of iron given on an empty stomach. The composition of meals with respect to content of meat or fish or the presence of large amounts of phytates seemed to have no influence on the absorption of iron from tablets. The absorption from iron tablets was about 40% higher when they were given with rice meals than when they were given with the other meals studied. The average decrease in absorption by meals was about 50-60% based on a comparison when tablets were given on an empty stomach. When tablets from which the iron was released more slowly were used, the absorption increased by about 30% except when they were given with rice meals, where the absorption was unchanged. The differences among the meals in their effect on the absorption of iron from tablets thus disappeared when the slow-release tablets were given. (author)

  6. Atomic absorption assessment of mineral iron quantity in ferritin

    International Nuclear Information System (INIS)

    Marinova, M.; Vladimirova, L.

    2009-01-01

    Possibilities for quantitative determination of the number of iron atoms in the mineral core of ferritin by atomic absorption spectroscopy (AAS) are investigated in the work. Different measurements with AAS show an iron content from 1000 up to 4500 atoms per molecule ferritin. This motivated us to investigate the amount of iron in the Horse Spleen Ferritin with atomic absorption spectroscopy under application of the Bulgarian standard BDS EN 14082/2003 Foodstuffs - Determination of trace elements - Determination of lead, cadmium, zinc, copper, iron and chromium by atomic absorption spectrometry (AAS) after dry ashing. The obtained results give approx. 1800 atoms per molecule Ferritin. It is in accordance with previous results, published by leading researchers. The investigation of the iron content with AAS under the use of the Bulgarian standard is a good opportunity to study many other objects of biological interest. (authors)

  7. Effects of Omeprazole on Iron Absorption: Preliminary Study

    Directory of Open Access Journals (Sweden)

    Mahmut Yaşar Çeliker

    2013-09-01

    Full Text Available Objective: Increasing numbers of pediatric and adult patients are being treated with proton pump inhibitors (PPIs. PPIs are known to inhibit gastric acid secretion. Nonheme iron requires gastric acid for conversion to the ferrous form for absorption. Ninety percent of dietary and 100% of oral iron therapy is in the nonheme form. To the best of our knowledge, the effect of PPIs on iron absorption has not been studied in humans. Our study assessed the relationship between omeprazole therapy and iron absorption in healthy subjects. Materials and Methods: We recruited 9 healthy volunteers between June 2010 and March 2011. Subjects with chronic illness, anemia, or use of PPI therapy were excluded. Serum iron concentrations were measured 1, 2, and 3 h after the ingestion of iron (control group. The measurements were repeated on a subsequent visit after 4 daily oral administrations of omeprazole at a dose of 40 mg (treatment group. Results: One female and 8 male volunteers were enrolled in the study with a mean age of 33 years. There was no statistical difference detected between baseline, 1-h, 2-h, and 3-h iron levels between control and treatment groups. Conclusion: Administration of omeprazole for a short duration does not affect absorption of orally administered iron in healthy individuals.

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

    Energy Technology Data Exchange (ETDEWEB)

    Westre, Tami E. [Stanford Univ., CA (United States)

    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.

  9. The effect of psychological stress on iron absorption in rats

    Directory of Open Access Journals (Sweden)

    Zhao Min

    2009-11-01

    Full Text Available Abstract Background Psychological stress (PS is recognized as an important pathogenic factor which leads to metabolism disorder in many diseases. Previous studies have shown that systemic iron homeostasis in mammalians was changed under specific stress conditions. Methods In present study, we used communication box to create psychological stress model and investigated the iron apparent absorption, iron accumulation in the apical poles of villous enterocytes and protein expressions of ferroportin 1 (FPN1, ferritin, divalent metal transporter 1 (DMT1. Results Our study showed that iron apparent absorption decreased and iron significantly accumulated in the apical poles of villous enterocytes in 3 d and 7 d PS groups. The expression of intestinal FPN1 in 3 d and 7 d PS groups was lower than that of control, while the change of intestinal ferritin was opposite. However, the expression of DMT1 did not change. Conclusion These results demonstrate that PS can decrease iron absorption in rats, which might be related to regulation expression of iron transporters.

  10. Iron absorption from beans with different contents of iron, evaluated by stable isotopes.

    Science.gov (United States)

    Junqueira-Franco, Márcia Varella Morandi; Dutra de Oliveira, José Eduardo; Nutti, Marilia Regini; Pereira, Helton Santos; Carvalho, José Luiz Vianna de; Abrams, Steven A; Brandão, Camila Fernanda Cunha; Marchini, Júlio Sérgio

    2018-06-01

    The introduction of biofortified foods such as beans with higher iron content may be a useful tool in preventing iron deficiency. The biofortification aims to reach the root of the problem of malnutrition, targets the neediest population, uses embedded distribution mechanisms, is scientifically feasible and effective in terms of cost, and complements other ongoing interventions to control micronutrient deficiency. However, to ensure effectiveness, measurement of the absorption of minerals is essential. The objective of this study was to evaluate the iron bioavailability of common bean BRS Pontal (PO), targeted for biofortification, compared with common bean BRS Estilo in man through reliable techniques that have not been previously used in Brazil. The study included 29 young adult volunteers divided into 2 groups: Group CB (13 subjects) received 100 g of common beans (BRS-Estilo) cooked labeled with iron-58 ( 58 Fe) and Group TBB (16 patients) received 100 g common bean target for iron biofortification (BRS-Pontal), cooked and labeled with iron58 ( 58 Fe). The next day they received the reference dose of ferrous sulfate enriched iron-57 ( 57 Fe). Isotopic evaluation of iron for measurement of iron incorporation into erythrocytes was performed 14 days after consumption. The beans used, were produced, through conventional breeding program, by EMBRAPA/Rice and Beans. The iron absorption was evaluated by assessing the isotopic enrichment of the stable isotope. Mean iron absorption from the meal with common beans was 0.409% (±0.040%) and mean iron incorporation from the meal with target beans for biofortification 0.407% (±0.038%) and did not differ between the groups. This study tested the iron absorption from a single bean meal in healthy volunteers or non anemics, In the present study the iron absorption ratio from common bean Pontal (PO), targeted for biofortification and compared with common bean BRS Estilo was not significantly different. The iron concentration

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

    Directory of Open Access Journals (Sweden)

    Fernando Pizarro

    2015-10-01

    Full Text Available 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.

  12. Nonradioisotopic method for measuring iron absorption from a Gambian meal

    International Nuclear Information System (INIS)

    Fairweather-Tait, S.J.; Minski, M.J.; Singh, J.

    1987-01-01

    Iron absorption from a typical Gambian meal of rice with groundnut sauce was measured by the fecal balance technique in nonanemic adult males with 58 Fe as an extrinsic label and neutron activation analysis and compared with ferrous sulfate. Gambian men had a higher efficiency of absorption than UK volunteers but the availability of the food Fe was approximately half that of ferrous sulfate in both groups of subjects

  13. Quantification of body iron and iron absorption in the REDS-II Donor Iron Status Evaluation (RISE) study.

    Science.gov (United States)

    Kiss, Joseph E; Birch, Rebecca J; Steele, Whitney R; Wright, David J; Cable, Ritchard G

    2017-07-01

    Repeated blood donation alters the iron balance of blood donors. We quantified these effects by analyzing changes in body iron as well as calculating iron absorbed per day for donors enrolled in a prospective study. For 1308 donors who completed a final study visit, we calculated total body iron at the enrollment and final visits and the change in total body iron over the course of the study. Taking into account iron lost from blood donations during the study and obligate losses, we also calculated the average amount of iron absorbed per day. First-time/reactivated donors at enrollment had iron stores comparable to previous general population estimates. Repeat donors had greater donation intensity and greater mean iron losses than first-time/reactivated donors, yet they had little change in total body iron over the study period, whereas first-time/reactivated donors had an average 35% drop. There was higher estimated iron absorption in the repeat donors (men: 4.49 mg/day [95% confidence interval [CI], 4.41-4.58 mg/day]; women: 3.75 mg/day [95% CI, 3.67-3.84 mg/day]) compared with estimated iron absorption in first-time/reactivated donors (men: 2.89 mg/day [95% CI, 2.75-3.04 mg/day]; women: 2.76 mg/day [95% CI, 2.64-2.87 mg/day]). The threshold for negative estimated iron stores (below "0" mg/kg stores) was correlated with the development of anemia at a plasma ferritin value of 10 ng/mL. These analyses provide quantitative data on changes in estimated total body iron for a broad spectrum of blood donors. In contrast to using ferritin alone, this model allows assessment of the iron content of red blood cells and the degree of both iron surplus and depletion over time. © 2017 AABB.

  14. Oral iron therapy in human subjects, comparative absorption between ferrous salts and iron polymaltose

    International Nuclear Information System (INIS)

    Jacobs, P.; Johnson, G.; Wood, L.

    1984-01-01

    Iron absorption was directly compared between equivalent doses of ferrous salts and a polymaltose complex using a twin-isotope technique in which each individual acts as his own control. In the first study, bioavailability of iron from ferrous sulfate and the complex was defined at physiologic doses of 5 mg (Group 1: n = 14) and therapeutic doses of 50 mg (Group 2: n = 13). In Group 1, mean absorption from salt was 47.77% (SD 14.58%) and from polymaltose, 46.56% SD 17.07%). In Group 2, mean absorption from salt was 32.92% (SD 13.42%) and from polymaltose, 27.07% (SD 6.50%). In a second study, 100 mg of iron in a chewable formulation was used to compare absorption between equal doses of ferrous fumarate and the polymaltose complex. Mean absorption from salt was 10.25% (SD 6.89%) and from polymaltose 10.68% (SD 4.68%). At all three dosage levels, iron is equally available from salt or polymaltose for hemoglobin synthesis (p greater than 0.20), and absorption negatively correlated with plasma ferritin (p less than 0.01). These two materials may be used interchangeably in the treatment of patients with absolute iron deficiency

  15. Adiposity in women and children from transition countries predicts decreased iron absorption, iron deficiency and a reduced response to iron fortification

    NARCIS (Netherlands)

    Zimmermann, M.B.; Zeder, C.; Muthayya, S.; Winichagoon, P.; Chaouki, N.; Aeberli, I.; Hurrell, R.F.

    2008-01-01

    Background: Overweight is increasing in transition countries, while iron deficiency remains common. In industrialized countries, greater adiposity increases risk of iron deficiency. Higher hepcidin levels in obesity may reduce dietary iron absorption. Therefore, we investigated the association

  16. Iron-59 absorption from soy hulls: intrinsic vs extrinsic labeling

    International Nuclear Information System (INIS)

    Lykken, G.I.; Mahalko, J.R.; Nielsen, E.J.; Dintzis, F.R.

    1986-01-01

    As part of an evaluation of the validity of the extrinsic labeling technique for measuring iron absorption, absorption from soy hulls extrinsically labeled ( 59 Fe added to bread dough) was compared with that from soy hulls intrinsically labeled ( 59 Fe incorporated into the soy plant during growth). Century soybeans were grown in a greenhouse. After pods had formed and were filling, each plant was stem injected twice, at 3 day intervals, with 22 μCi 59 Fe as FeCl 2 in 25 μl of 0.5 M HCl solution. After the plants had senesced, the soybeans were harvested, dried, shelled and the hulls removed. Standard meals containing 3.5 mg Fe/meal and up to 0.06 μCi 59 Fe in a soy hull bun were fed on 2 consecutive days to free-living volunteers in a crossover design. Absorption of 59 Fe was greater from intrinsically labeled soy hulls than from extrinsically labeled soy hulls, 20 +/- 20% vs 15 +/- 11% (n=14, p > 0.05 by paired t-test). Apparent absorption ranged from 1.3% to 77% from intrinsically labeled soy hulls and .5% to 29% from extrinsically labeled soy hulls with the highest absorption occurring in persons with low serum ferritin (S.F. < 8 ng/ml). These findings provide additional evidence that the extrinsic labeling method is a valid measure of iron bioavailability to humans

  17. Use of a standard meal to study iron absorption in humans

    International Nuclear Information System (INIS)

    Reddy, M.B.; Cook, J.D.

    1994-01-01

    Iron absorption varies widely between subjects and groups of subjects because of differences in iron status which markedly influence iron assimilation from the gastrointestinal tract. A small dose of isotopically labelled inorganic iron termed the reference dose (3 mg iron as FeSO 4 ) has been used extensively during the past two decades to standardize food iron absorption in human subjects and thereby eliminate the effect of differences in iron status. Recent studies from this laboratory have shown that because of the high variability of absorption from the reference dose, nonheme iron absorption from a standardized meal provides a more reliable means of standardizing absorption from regional diets. We therefore performed initial studies with a rice based meal but we found a relatively high variation in absorption from 2.0 to 4.7% that presumably reflects differences in the phytate content of rice fours. We then undertook the evaluation of meals prepared with farina, a wheat product that is available in most regions of the world. In six different studies from a farina based meal, iron absorption ranged from 3.4 to 6.5%. Nonheme iron absorption from the farina meal when evaluated in separate laboratories extensively engaged in human studies of iron absorption, ranged from 5.1 to 10.8% but when related to the FeSO 4 dose, a more consistent ratio between 0.21 to 0.26 was observed with the exception of one laboratory where a very low absorption of 1.1.% was observed. Percentage absorption from the farina based meal decreased when the iron content of the meal was increased and showed the expected facilitation of absorption when increasing amounts of ascorbic acid were added. By reducing variability and measuring iron absorption from food rather than inorganic iron, we believe that the use of this standard meal will facilitate comparison of iron absorption data obtained in laboratories throughout the world. 4 refs, 2 tabs

  18. Effect of iron status on iron absorption in different habitual meals in young south Indian women

    Directory of Open Access Journals (Sweden)

    Suneeta Kalasuramath

    2013-01-01

    Full Text Available Background & objectives: Iron deficiency (ID affects a large number of women in India. An inverse relationship exists between iron (Fe status and Fe absorption. Dietary inhibitory and enhancing factors exert a profound influence on bioavailability of Fe. Although the current recommended dietary allowance (RDA for Fe is based on 8 per cent bioavailability, it is not clear if this holds good for the usual highly inhibitory Indian diet matrix. This study was aimed to determine Fe absorption from several habitually consumed south Indian food and to evaluate the interaction of Fe status with absorption. Methods: Four Fe absorption studies were performed on 60 apparently healthy young women, aged 18-35 years. Based on blood biochemistry, 45 of them were ID and 15 were iron replete (IR. The habitual meals assessed were rice, millet and wheat based meals in the ID subjects and rice based meal alone in the IR subjects. Each subject received the test meal labelled with 3 mg of [57] Fe and Fe absorption was measured based on erythrocyte incorporation of isotope label 14 days following administration. Results: Mean fractional Fe absorption from the rice, wheat and millet based meals in the ID subjects were 8.3, 11.2 and 4.6 per cent, respectively. Fe absorption from the rice-based meals was 2.5 per cent in IR subjects. Interpretation & conclusions: Fe absorption is dictated by Fe status from low bioavailability meals. Millet based meals have the lowest bioavailability, while the rice and wheat based meals had moderate to good bioavailability. In millet based meals, it is prudent to consider ways to improve Fe absorption.

  19. Influence of iron on plutonium absorption by the adult and neonatal rat

    International Nuclear Information System (INIS)

    Sullivan, M.F.; Ruemmler, P.S.; Buschbom, R.L.

    1986-01-01

    To determine how iron affects plutonium absorption, adult rats were gavaged with 238 Pu nitrate (pH 2) after they had been fed an iron-deficient diet or treated with iron supplements. Neonatal rats born to dams on an iron-deficient diet were also gavaged with 238 Pu. An iron-deficient diet resulted in enhanced 238 Pu absorption both in the adults and in neonates born to iron-deficient dams. Ferric iron increased 238 Pu absorption 12-fold in adult rats; injected iron-dextran reduced that increase; gavaged ferrous iron reduced 238 Pu absorption to one-third of the control value. Rat neonates absorbed 30 to 40 times as much 238 Pu as adults; absorption was lowered in groups that received iron supplements: Iron-dextran caused a 50% reduction; ferric iron, 95%; and ferrous iron, greater than 95%. The results demonstrate an effect of the oxidation state of iron on plutonium absorption in adult rats different from that observed in suckling rats. The results suggest that the high rate of 238 Pu absorption by neonatal animals is due not only to the permeability of their intestines but also to their high demand for iron

  20. Epigallocatechin gallate (EGCG) (TEAVIGO™) does not impair nonhaem-iron absorption in man

    NARCIS (Netherlands)

    Ullmann, U.; Haller, J.; Bakker, G.C.M.; Brink, E.J.; Weber, P.

    2005-01-01

    A number of studies have shown that tea catechins can inhibit intestinal iron absorption, mostly iron in the nonhaem form. This randomized, double-blind, placebo-controlled, 3-periods cross-over study examined the degree of inhibition of nonhaem iron absorption by pure crystalline epigallocatechin

  1. Does lead use the intestinal absorptive pathways of iron? Impact of iron status on murine 210Pb and 59Fe absorption in duodenum and ileum in vivo

    International Nuclear Information System (INIS)

    Elsenhans, Bernd; Janser, Heinz; Windisch, Wilhelm; Schuemann, Klaus

    2011-01-01

    Highlights: → Absorption of 210 Pb increases much less than that of 59 Fe in murine duodena. → 210 Pb-absorption is almost equally high in murine duodenal and ileal segments. → 59 Fe absorption is much lower in ileal than in duodenal segments. → There must be an additional DMT1-independet pathway for intestinal Pb absorption. -- Abstract: Background: Human isotope studies and epidemiological trials are controversial as to whether lead absorption shares the absorptive pathways of iron and whether body lead content can be reduced by iron supplementation. Aim: To compare the impact of iron-deficiency on 59 Fe- and 210 Pb-absorption rates in duodenal and ileal segments. Methods: 59 Fe- and 210 Pb-absorption was determined in ligated duodenal and ileal segments from juvenile and adult iron-deficient and iron-adequate C57Bl6 wild-type mice (n = 6) in vivo at luminal concentrations corresponding to human exposure (Fe: 1 and 100 μmol/L; Pb: 1 μmol/L). Results and discussion: 59 Fe-absorption increased 10-15-fold in iron-deficient duodena from adult and adolescent mice. Ileal 59 Fe-absorption was 4-6 times lower than in iron-adequate duodena showing no adaptation to iron-deficiency. This in accordance to expectation as the divalent metal transport 1 (DMT1) shows low ileal expression levels. Juvenile 59 Fe-absorption was about twice as high as in adult mice. In contrast, duodenal 210 Pb-absorption was increased only 1.5-1.8-fold in iron-deficiency in juvenile and adult mice and, again in contrast to 59 Fe, ileal 210 Pb-absorption was as high as in iron-adequate duodena. Conclusions: The findings suggest a DMT1-independent pathway to mediate lead absorption along the entire small intestine in addition to DMT1-mediated duodenal uptake. Ileal lead absorption appears substantial, due the much longer residence of ingesta in the distal small intestine. Differences in lead-solubility and -binding to luminal ligands can, thus, explain the conflicting findings regarding the

  2. Radioisotope investigation of iron absorption in humans. Part of a WHO/IAEA coordinated programme on iron nutrition

    International Nuclear Information System (INIS)

    Bothwell, T.H.

    1975-08-01

    The gastrointestinal absorption of iron was investigated in a number of multiparous women living under low socio-economic conditions which are known to lead commonly to iron deficiency. The percentage absorption was deduced by comparing the concentration of 55 Fe and/or 59 Fe in blood with the activity of the corresponding isotope(s) administered orally about two weeks earlier. It was confirmed or established that: (1) food or supplemental iron, if available at all, tends to be absorbed from the intestines as if present there in one of two alternative pools: heme and non-heme, (2) vitamin C substantially increases absorption of food or supplemental non-heme iron, (3) it is technically possible to use common salt or sugar as a carrier for supplemental iron and vitamin C, but practical difficulties of using such systems in a public health prophylactic programme are severe, and (4) tea, presumably because of its tannin content, inhibits absorption of accompanying iron

  3. Heated electron distributions from resonant absorption

    International Nuclear Information System (INIS)

    DeGroot, J.S.; Tull, J.E.

    1975-01-01

    A simplified model of resonant absorption of obliquely incident laser light has been developed. Using a 1.5 dimensional electrostatic simulation computer code, it is shown that the inclusion of ion motion is critically important in determining the heated electron distributions from resonant absorption. The electromagnetic wave drives up an electron plasma wave. For long density scale lengths (Lapprox. =10 3 lambda/subD//sube/), the phase velocity of this wave is very large (ω/kapproximately-greater-than10V/sub th/) so that if heating does occur, a suprathermal tail of very energetic electrons is produced. However, the pressure due to this wave steepens the density profile until the density gradient scale length near the critical density (where the local plasma frequency equals the laser frequency) is of order 20lambda/subD//sube/. The electrostatic wave is thus forced to have a much lower phase velocity (ω/kapprox. =2.5V/sub th/). In this case, more electrons are heated to much lower velocities. The heated electron distributions are exponential in velocity space. Using a simple theory it is shown that this property of profile steepening applies to most of a typical laser fusion pulse. This steepening raises the threshold for parametric instabilities near the critical surface. Thus, the extensive suprathermal electron distributions typically produced by these parametric instabilities can be drastically reduced

  4. Effects of iron, tin, and copper on zinc absorption in humans

    International Nuclear Information System (INIS)

    Valberg, L.S.; Flanagan, P.R.; Chamberlain, M.J.

    1984-01-01

    Zinc absorption as measured by body retention of [65Zn]zinc chloride or a turkey test meal extrinsically labeled with 65Zn was determined in human subjects by whole body counting after 7 days. Average 65Zn absorption from zinc chloride in persons with a high iron-absorbing capacity was similar to persons with a low capacity to absorb iron. Inorganic iron, 920 mumol (51 mg), or HB iron, 480 mumol (26 mg), inhibited 65Zn absorption from 92 mumol (6 mg) of zinc chloride. When 610 mumol of iron (34 mg) was added to a turkey test meal containing 61 mumol of zinc (4 mg), 65Zn absorption was not inhibited. Tin, 306 mumol (36 mg), given with zinc chloride or turkey test meals (61 mumol, 4 mg, of Zn) significantly reduced 65Zn absorption. Copper, 79 mumol (5 mg), had no significant effect on the 65Zn absorption from 7.9 mumol (0.5 mg) of zinc chloride. In summary, the capacity to absorb iron did not influence 65Zn absorption, but both inorganic iron and heme-iron inhibited 65Zn absorption from zinc chloride. Inorganic iron had no effect, however, on 65Zn absorption from the turkey test meal. Tin in a large dose also inhibited 65Zn absorption from both zinc chloride and the turkey test meal

  5. Determination of iron absorption and excretion by whole-body counting

    International Nuclear Information System (INIS)

    Hollard, D.; Benabid, Y.; Berard, M.; Bonnin, J.; Darnault, J.; Millet, M.

    1969-01-01

    Using a whole-body counter, the authors have studied 59 Fe absorption and loss in 8 normal subjects and in 30 iron deficient patients. Results showed that whole-body counting provided an excellent and simple method for iron retention measurements, obviating many inaccuracies of previous technic. Normal absorption of radio iron with this procedure has ranged from 9 per cent to 20 per cent of the administered tracer in normal subjects, with a mean of 15 per cent. A significant increase in 59 Fe absorption was noted in 21 iron-deficient patients in whom the retention ranged from 40 to 100 per cent. However, 3 iron-deficient patients were found to have low absorption, and their severe iron deficiency could be correlated with this defect in absorption. This method permits also the determination of the rate of iron excretion during the following months and therefore the study of the mechanism of some pathological loss. (authors) [fr

  6. A preliminary study of iron absorption by whole body counting and correlation with DFO excretion

    International Nuclear Information System (INIS)

    Gupta, M.M.; Bhattacharyya, L.; Gupta, N.K.; Bhola, G.C.; Nagaratnam, A.; Manchanda, R.; Bhargva, M.; Kumar, S.

    1975-01-01

    A preliminary study of iron absorption by oral administration of 59 Fe and whole body counting was carried on a group of 16 women. The cases included 8 patients suffering from iron deficiency anaemia and various infections as well as 8 healthy controls. High iron absorption is associated with iron deficiency, these changes being more marked in iron deficient controls than in those with infection or malignancy. In iron deficient controls results of whole body counting correlate very well with other haematological investigations. (orig.) [de

  7. Experimental study of absorption of iron in foods using whole-body counter

    International Nuclear Information System (INIS)

    Nakamura, Tadamitsu

    1978-01-01

    Male rats of Wistar strain which showed normal hematological picture were given 59 Fe-labeled foods orally, and the iron absorption rate was determined by an animal whole body counter. When 59 Fe was given in a mixture with each of gruel, spinach, cow's milk, the yolk, and the yolk with orange juice, the iron absorption rates in each food were 9.4%, 8.9%, 6.6%, 10.8% and 7.2% respectively. None of these foods seemed to inhibit the 59 Fe absorption. When 59 Fe was given in a mixture with chicken, the iron absorption rate was 35.8%. This result suggested that the chicken promoted the 59 Fe absorption. When the yolk labeled in vivo with 59 Fe was given, the iron absorption rate was 4.9%. If the yolk labeled in vitro was used, the absorption rate was 10.8%. When the yolk labeled in vivo with 59 Fe was given with orange juice, the iron absorption rate was 13.3%. If the yolk labeled in vivo with 59 Fe was given, the absorption rate was 7.2%. Orange juice had no effect on the iron absorption when the yolk labeled in vitro was used. After chicken eggs labeled in vivo with 59 Fe was given to children, the iron absorption was determined by a whole body counter; the rate averaged 5.4 in the children without anemia and 24.7 in those with anemia. (Ueda, J.)

  8. Ultrafast electron and energy transfer in dye-sensitized iron oxide and oxyhydroxide nanoparticles

    DEFF Research Database (Denmark)

    Gilbert, Benjamin; Katz, Jordan E.; Huse, Nils

    2013-01-01

    photo-initiated interfacial electron transfer. This approach enables time-resolved study of the fate and mobility of electrons within the solid phase. However, complete analysis of the ultrafast processes following dye photoexcitation of the sensitized iron(iii) oxide nanoparticles has not been reported....... We addressed this topic by performing femtosecond transient absorption (TA) measurements of aqueous suspensions of uncoated and DCF-sensitized iron oxide and oxyhydroxide nanoparticles, and an aqueous iron(iii)–dye complex. Following light absorption, excited state relaxation times of the dye of 115...... a four-state model of the dye-sensitized system, finding electron and energy transfer to occur on the same ultrafast timescale. The interfacial electron transfer rates for iron oxides are very close to those previously reported for DCF-sensitized titanium dioxide (for which dye–oxide energy transfer...

  9. Bioavailable iron in typical Thai meals: Comparative studies between radioactive in vitro and in vivo food iron absorption measurements

    International Nuclear Information System (INIS)

    Sritongkul, N.

    1989-03-01

    Presently available in vivo methods for assessing iron absorption in human subjects, although physiologically acceptable and accurate, are not practical for screening large numbers of food and diet samples. A simple in vitro method for determining the amount of iron available for absorption was therefore investigated. It is based on the common pool concept of food iron absorption using radioactive Fe-59 as a marker of the iron present in the bioavailable iron pool. The ionizable iron was measured after an initial peptic digestion by using pepsin/HCl at pH 1.35 followed by an increase of the pH to 6.0 to simulate duodenal alkalinity. The method was proved to be simple, reproducible and applicable either to single food items or whole meals of varying composition. It is able to detect known enhancers or inhibitors of food iron absorption. The percent ionizable iron among 5 different meals with the inclusion of inhibitor or enhancer was shown to correlate closely with the percentage of iron absorbed in human subjects (r=0.9197, p<0.001). A high correlation between the in vivo and in vitro methods was also observed when the results were expressed as absorption ratios and ionizable ratios (r=0.9192, p<0.001). The method is expected to be useful for improving diet composition to increase the iron availability of some typical meals in developing countries, including those which are known to contain considerable amounts of inhibitors of iron absorption. 39 refs, 1 fig., 13 tabs

  10. Femtosecond X-ray Absorption Spectroscopy at a Hard X-ray Free Electron Laser

    DEFF Research Database (Denmark)

    Lemke, Henrik T.; Bressler, Christian; Chen, Lin X.

    2013-01-01

    X-ray free electron lasers (XFELs) deliver short (current (SASE based) XFELs, they can be used for measuring high......-quality X-ray absorption data and we report femtosecond time-resolved X-ray absorption near-edge spectroscopy (XANES) measurements of a spin-crossover system, iron(II) tris(2,2'-bipyridine) in water. The data indicate that the low-spin to high-spin transition can be modeled by single-exponential kinetics...

  11. Iron absorption by roots of fruit plants : some characteristics of the phenomena

    International Nuclear Information System (INIS)

    Bindra, A.S.

    1979-01-01

    Using young plants of peach, plum and almond growing in water culture, study was undertaken on the absorption and translocation of labelled iron. When peach plants deficient in this element were supplied with it, they tended to absorb it very rapidly, especially during the first 30 minutes. This absorption was not a superficial adsorption. Iron absorption was found to be linked to the length of non-lignified roots. Of the three species, almond absorbed more iron than peach but less than olum. No significant varietal difference was found regarding the iron absorption capacity of roots of different varieties of peach. Removal of foliage did not influence the absorption of iron by roots of peach plants in the early stages. (auth.)

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

    Science.gov (United States)

    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...

  13. Studies on the absorption of iron after oral administration in piglets

    International Nuclear Information System (INIS)

    Thoren-Tolling, K.

    1975-01-01

    72 newborn piglets from 9 litters were used to determinate the retention and distribution in the body of labelled iron given either orally as ferrous fumarate (100 mg Fe 2+ ) or iron dextran (200 mg Fe 3+ ), or by injection as iron dextran (100 mg Fe 3+ ). About 25-30 % of the radioiron from a single oral dose of labelled ferrous fumarate (100 mg Fe 2+ ), and about 55-60 % from a single oral dose of labelled iron dextran (200 mg Fe 3+ ) were absorbed by the body. As iron is excreted throughout the experiment, only about 20% and 40-50% respectively of the radio-iron from these iron compounds were recovered 3 weeks after treatment. The total amounts of labelled iron retained in the body after oral administration of the same doses of these iron compounds, alone or in combination, were compared. A slight retardation of the absorption of ferrous iron was observed when iron dextran was administered simultaneeously. The absorption of iron dextran was not influenced by the simultaneous administration of ferrous fumarate. The importance of the liver as the main iron storage site was shown, and the rapid utilization of iron from storage sites, about 2-3 weeks after treatment was demonstrated. The concentration of labelled iron in urine and some lymphglands was measured. Only minute quantities of radio-iron were excreted in the urine throughout the entire experiment. The lymph nodes seem to act as iron stones after administration of iron dextran. The importance of the lymphatic tissue in absorption and storage of labelled iron is discussed. (author)

  14. Dietary hemoglobin rescues young piglets from severe iron deficiency anemia: Duodenal expression profile of genes involved in heme iron absorption.

    Directory of Open Access Journals (Sweden)

    Robert Staroń

    Full Text Available Heme is an efficient source of iron in the diet, and heme preparations are used to prevent and cure iron deficiency anemia in humans and animals. However, the molecular mechanisms responsible for heme absorption remain only partially characterized. Here, we employed young iron-deficient piglets as a convenient animal model to determine the efficacy of oral heme iron supplementation and investigate the pathways of heme iron absorption. The use of bovine hemoglobin as a dietary source of heme iron was found to efficiently counteract the development of iron deficiency anemia in piglets, although it did not fully rebalance their iron status. Our results revealed a concerted increase in the expression of genes responsible for apical and basolateral heme transport in the duodenum of piglets fed a heme-enriched diet. In these animals the catalytic activity of heme oxygenase 1 contributed to the release of elemental iron from the protoporphyrin ring of heme within enterocytes, which may then be transported by the strongly expressed ferroportin across the basolateral membrane to the circulation. We hypothesize that the well-recognized high bioavailability of heme iron may depend on a split pathway mediating the transport of heme-derived elemental iron and intact heme from the interior of duodenal enterocytes to the bloodstream.

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

    International Nuclear Information System (INIS)

    Thompson, Khristy; Molina, Ramon; Donaghey, Thomas; Brain, Joseph D.; Wessling-Resnick, Marianne

    2006-01-01

    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 ∼2-fold in rats fed the high iron diet. To determine if iron-loading affected manganese uptake, 54 Mn was administered by intratracheal (it) instillation or intravenous (iv) injection for pharmacokinetic studies. 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 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

  16. Serum-ferritin and iron absorption for the study of body iron stored in the Thai population

    International Nuclear Information System (INIS)

    Plehachinda, R.

    1984-05-01

    Measurements of serum ferritin by an ''in-house'' immunoradiometric assay (IRMA) method were used in conjunction with estimations of gastro-intestinal iron absorption from a standard test dose of ferrous ascorbate, measurements of blood haemoglobin and measurements of other haematological parameters to study body iron status in various population groups and to assess changes in body iron status after food-iron fortification. The IRMA method particularly covered the lower range of serum ferritin levels from 0.5 to 10 μg/litre, corresponding to iron deficiency. Quality control indicated satisfactory assay performance. In preliminary studies, serum ferritin level was found to be well correlated with gastro-intestinal iron absorption as an indicator of body iron status. Normal adult male subjects in Bangkok showed levels of 21-314 μg/litre and normal adult female levels of 13-173 μg/litre, in general agreement with values reported by other authors. Measurements were then extended to subjects in an area of north-eastern Thailand where iron-deficiency was common, to assess the effectiveness of food-iron fortification programmes. Measurements were also made on male blood donors in Bangkok, pregnant female subjects in Bangkok and north-eastern Thailand, school children in an area of southern Thailand where hookworm infestation was common and schoolchildren and adult female subjects in an area of northern Thailand where goitre was endemic. The results of all these studies are presented

  17. Molecular absorption spectra of beryllium, cerium, lanthanum, iron, and platinum salts

    International Nuclear Information System (INIS)

    Daidoji, Hidehiro

    1980-01-01

    The absorption spectra of some salts of beryllium, cerium, lanthanum, iron and platinum in air-acetylene flame were measured in the wavelength range from 200 to 400 nm. A Hitachi 207 type atomic absorption spectrophotometer was used. A deuterium lamp, a home-made continuous radiation lamp and some hollow cathode lamps were used as light sources. The new molecular absorption spectra of cerium, lanthanum and platinum and the absorption spectra due to Be(OH) 2 , LaO, PtH, FeO and FeCl in 200-400 nm region were obtained. Emission spectra of CeO, LaO and FeOH were also obtained. These molecular absorption bands were estimated as absorption errors of maximum 15 times to the sensitivity of each elements in atomic absorption spectrometry. In addition, spectral line interferences of iron were observed in atomic absorption spectrometry of Zn, Cd, Ni, Cu and Cr. (author)

  18. [Iron absorption of the habitual diet in a population of low socioeconomic level].

    Science.gov (United States)

    Morón, C; Kremenchuzky, S; Passamai, M I; D'Andrea de Rivero, S; Pérez de Galíndez, G; Gerschcovich, C

    1985-06-01

    Iron absorption using the extrinsic double-tag method was determined in the habitual diet consumed by a group of 32 volunteers of both sexes, pertaining to the low socioeconomic strata. The diet was made up of bread, spaghetti, vegetables and meat, totalling 2,022 kcal, 65.0 g protein, 17.57 mg iron, and 28.75 mg ascorbic acid. According to our findings, men were found to be neither anemic nor iron-deficient. Among the women, however, 4.8% had anemia and 57.1% suffered from iron deficiency. The non-heme iron absorption was very low: 1.35% at breakfast, 3.29% at lunch, and 3.82% at dinner. Among those subjects found to be normal, the absorption was half the above figures, whereas among those with iron deficiency it was threefold, the differences being highly significant. The absorption of heme-iron for lunch and dinner was 17.53%. The iron deficient group had an absorption value four times greater than the normal group, the differences also being highly significant. The daily availability of non-heme, heme and total iron was 0.44, 1.13 and 1.57 mg, respectively. In the subjects who formed the normal group, total iron available was 1.14 mg, barely covering a man's daily requirements, but not those of a woman. In the iron-deficient group, it was 4.31 mg, that is, four times greater than in the normal group; while this value improves the balance, it does not prevent deficiency in women, with great blood losses. Bearing these results in mind, it is suggested that measures tending to improve dietary iron content and bio-availability, be enforced.

  19. Diagnostic relevance of radioiron-absorption-measurements and immunoradiometric serum-ferritin-assay in the evaluation of iron stores

    International Nuclear Information System (INIS)

    Heinrich, H.C.

    1978-01-01

    Negative iron balance and enhanced iron demand respectively causes deficient iron stores (prelatent iron deficiency) with increased iron absorption, later on decrease of serum iron and increase of transferrin (latent Fe deficiency) and at least iron deficient anemia (manifest iron deficiency). In prelatend iron deficiency diagnostic 59 Fe 2+ absorption is increased and the RES cells do not show storage iron cytochemically. In latent iron deficiency in addition serum iron, transferrin iron saturation and serum ferritin is decreased and hypochromic mikrocytic anemia completes the signs of manifest iron deficiency. Besides rare cases of primary hemochromatosis and marked hyperdasia of ineffective erythropoiesis in homocygotic beta-thalassemia, hereditary non-spherocytic hemolytic anemia caused by pyruvate kinase deficiency and some sideroblastic anemias increased 59 Fe 2+ absorption is a reliable measure of exhausted iron stores. In these exceptional cases differential diagnosis between sideroachrestic and siderosensitive iron deficiency anemia can be made by measurement of serum iron and serum ferritin respectively. The etiology of iron deficiency is to be cleared by measurement of 59 Fe absorption from 59 Fe 2+ and 59 Fe-marked meat with consecutive estimation of whole body 59 Fe elimination. Shortly after completion or during oral iron therapy serum ferritin concentration is not suitable to evaluate the content of iron stores. (orig.) [de

  20. Iron and zinc absorption from weaning foods prepared from germinated cereals and legumes

    International Nuclear Information System (INIS)

    Kuizon, M.D.

    1992-01-01

    Iron deficiency anaemia is a public health problem in the Philippines especially in infants, children and pregnant women. The immediate cause is inadequate intake of available iron to meet increased iron requirements. Iron supplementation studies on pregnant women showed improvement in haemoglobin level and reduction of prevalence of anaemia. A project on iron fortification of rice with ferrous sulphate is going on. It is proposed to study iron and zinc absorption from weaning food prepared from germinated rice: mungbean, germinated rice: cowpea, and germinated corn:mungbean to support the finding that these formulations will alleviate not only protein-energy malnutrition but contribute to improvement of iron status as well since iron contents are higher and anti-nutritional factors (phytates and tannin) are either reduced or eliminated. This study aims to measure the iron and zinc absorption from weaning foods prepared from germinated rice-mungbean, germinated rice-cowpea, and germinated corn-mungbean and to indicate usefullness of modifying local foods to improve iron absorption. 24 refs, 4 figs

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

    Science.gov (United States)

    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...

  2. The effects of fat loss after bariatric surgery on inflammation, serum hepcidin, and iron absorption

    NARCIS (Netherlands)

    Cepeda-Lopez, Ana C.; Allende-Labastida, Javier; Melse-Boonstra, Alida; Osendarp, Saskia J.M.; Herter-Aeberli, Isabelle; Moretti, Diego; Rodriguez-Lastra, Ramiro; Gonzalez-Salazar, Francisco; Villalpando, Salvador; Zimmermann, Michael B.

    2016-01-01

    Background: Iron deficiency is common in obese subjects. This may be due to an increase in serum hepcidin and a decrease in iron absorption from adiposity-related inflammation. Objective: We evaluated whether weight and fat loss in obese subjects would decrease inflammation and serum hepcidin and

  3. Effect of the carbonyl iron particles on acoustic absorption properties of magnetic polyurethane foam

    Science.gov (United States)

    Geng, Jialu; Wang, Caiping; Zhu, Honglang; Wang, Xiaojie

    2018-03-01

    Elastomeric matrix embedded with magnetic micro-sized particles has magnetically controllable properties, which has been investigated extensively in the last decades. In this study we develop a new magnetically controllable elastomeric material for acoustic applications at lower frequencies. The soft polyurethane foam is used as matrix material due to its extraordinary elastic and acoustic absorption properties. One-step method is used to synthesize polyurethane foam, in which all components including polyether polyols 330N, MDI, deionized water, silicone oil, carbonyl iron particle (CIP) and catalyst are put into one container for curing. Changing any component can induce the change of polyurethane foam's properties, such as physical and acoustic properties. The effect of the content of MDI on acoustic absorption is studied. The CIPs are aligned under extra magnetic field during the foaming process. And the property of polyurethane foam with aligned CIPs is also investigated. Scanning electron microscope (SEM) is used to observe the structure of pore and particle-chain. The two-microphone impedance tube and the transfer function method are used to test acoustic absorption property of the magnetic foams.

  4. Electron Spectroscopy Studies of Iron, Iron Sulfides and Supported Iron Surfaces: Chemisorption of Simple Gases.

    Science.gov (United States)

    Lee, Yiu Chung

    EELS was used to investigate the chemisorption of oxygen and carbon on iron. The EELS spectra of oxidized iron show characteristic features with strong enhancement of the interband transitions involving the Fe 3d band (4.6 and 7.5 eV) and moderate enhancement of the M(,2,3) transition doublet (54.4 and 58.2 eV). The changes in the electron energy loss structures with an overlayer of graphitic or carbidic carbon were investigated. The adsorption and growth of iron on Ni(100) has been studied using the combined techniques of LEED and EELS. Initially iron grows by a layer-by-layer mechanism for the first few layers. High iron coverages result in the observation of complex LEED patterns with satellites around the main (1 x 1) diffraction sports. This is due to the formation of b.c.c. Fe(110) crystallites arranged in domains with different orientations. EELS studies show the presence of three stages in the growth of iron on Ni(100): low-coverage, film-like and bulk-like. Auger and EELS were used to study the iron sulfide (FeS(,2), Fe(,7)S(,8) and FeS) surfaces. A characteristic M(,2,3) VV Auger doublet with a separation of 5.0 eV was observed on the sulfides. An assignment of the electron energy loss peaks was made based on the energy dependence of the loss peaks and previous photoemission results. The effect of argon ion bombardment was studied. Peaks with strong iron and sulfur character were observed. Heating the damaged sulfides results in reconstruction of the sulfide surfaces. The reactions of the sulfides with simple gases, such as H(,2), CO, CH(,4), C(,2)H(,4), NH(,3) and O(,2) were also studied. Using XPS, the chemisorption of SO(,2) on CaO(100) has been studied. The chemical state of sulfur has been identified as that of sulfate. The kinetics of SO(,2) chemisorption on CaO are discussed. The binding states of Fe and Na on CaO were determined to be Fe('2+) and Na('+) respectively. At low Fe or Na coverages (< 0.5 ML), there is a large increase in the rate of

  5. The Relationship Between Intestinal Iron Absorption and Hepatic Parenchymal Cell Damage

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Mok Hyun; Hahn, Shin Suck [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1971-09-15

    Since the iron balance is maintained by regulated intestinal absorption rather than regulated excretion, there have been many reports concerning the factors which may influence the intestinal iron absorption. As the liver is the largest iron storage organ of the body, any hepatocellular damage may result in disturbances in iron metabolism, e,g., frequent co-existence of haemochromatosis and liver cirrhosis, or elevated serum iron level and increased iron absorption rate in patients with infectious hepatitis or cirrhosis. In one effort to demonstrate the influence of hepatocellular damage on intestinal iron absorption, the iron absorption rate was measured in the rabbits whose livers were injured by a single subcutaneous injection of carbon tetrachloride (doses ranging from 0.15 to 0.5 cc per kg of body weight) or by a single irradiation of 2, 000 to 16, 000 rads with Co on the liver locally. A single oral dose of 1muCi of Fe-citrate with 0.5 mg of ferrous citrate was fed in the fasting state, 24 hours after hepatic damage had been induced, without any reducing or chelating agents, and stool was collected for one week thereafter. Serum iron levels, together with conventional liver function teats, were measured at 24, 48, 72, 120 and 168 hours after liver damage had been induced. All animals were sacrificed upon the completing of the one week's test period and tissue specimens were prepared for H-E and Gomori's iron stain. Following are the results. 1. Normal iron absorption rate of the rabbit was 41.72+-3.61% when 0.5 mg of iron was given in the fasting state, as measured by subtracting the amount recovered in stool collected for 7 days from the amount given. The test period of 7 days is adequate, for only 1% of the iron given was excreted thereafter. 2. The intestinal iron absorption rate and serum iron level were significantly increased when the animal was poisoned by a single subcutaneous injection of 0.15 cc, per kg. of body weight of carbon tetrachloride or

  6. The Relationship Between Intestinal Iron Absorption and Hepatic Parenchymal Cell Damage

    International Nuclear Information System (INIS)

    Kim, Mok Hyun; Hahn, Shin Suck

    1971-01-01

    Since the iron balance is maintained by regulated intestinal absorption rather than regulated excretion, there have been many reports concerning the factors which may influence the intestinal iron absorption. As the liver is the largest iron storage organ of the body, any hepatocellular damage may result in disturbances in iron metabolism, e,g., frequent co-existence of haemochromatosis and liver cirrhosis, or elevated serum iron level and increased iron absorption rate in patients with infectious hepatitis or cirrhosis. In one effort to demonstrate the influence of hepatocellular damage on intestinal iron absorption, the iron absorption rate was measured in the rabbits whose livers were injured by a single subcutaneous injection of carbon tetrachloride (doses ranging from 0.15 to 0.5 cc per kg of body weight) or by a single irradiation of 2, 000 to 16, 000 rads with Co on the liver locally. A single oral dose of 1μCi of Fe-citrate with 0.5 mg of ferrous citrate was fed in the fasting state, 24 hours after hepatic damage had been induced, without any reducing or chelating agents, and stool was collected for one week thereafter. Serum iron levels, together with conventional liver function teats, were measured at 24, 48, 72, 120 and 168 hours after liver damage had been induced. All animals were sacrificed upon the completing of the one week's test period and tissue specimens were prepared for H-E and Gomori's iron stain. Following are the results. 1. Normal iron absorption rate of the rabbit was 41.72±3.61% when 0.5 mg of iron was given in the fasting state, as measured by subtracting the amount recovered in stool collected for 7 days from the amount given. The test period of 7 days is adequate, for only 1% of the iron given was excreted thereafter. 2. The intestinal iron absorption rate and serum iron level were significantly increased when the animal was poisoned by a single subcutaneous injection of 0.15 cc, per kg. of body weight of carbon tetrachloride or

  7. Effect of sodium iron ethylenediaminetetraacetic acid on the absorption of various trace elements in anemic rats

    International Nuclear Information System (INIS)

    Igarashi, Kaori; Sasaki, Ayako; Yoda, Yoko; Inage, Hiroko; Nakanishi, Yukiko; Kimura, Shuichi; Yanagiya, Takahiro; Hirunuma, Rieko; Enomoto, Shuichi

    2001-01-01

    Iron deficiency in developing countries is attributed to the bioavailability of iron derived from staple food such as grains, vegetables and legumes. Sodium iron ethylenediaminetetraacetic acid (NaFeEDTA), a strong metal chelator, is one of the food additives for iron fortification and it has been for improvement of iron deficiency in the world. However, the effect of NaFeEDTA on the absorption of trace elements other than Fe has been poorly understood. In the present study, to investigate the effect of NaFeEDTA on the absorption of trace elements, we determined the uptake rate of various metals using a multitracer technique. The uptake rates of Zn, Co, and Na in rats fed with NaFeEDTA diet were significantly lower than those in rats fed with ferrous sulfate (FS) diet, suggesting that iron fortification by NaFeEDTA lowers the bioavailability of various elements compared with FS. On the other hand, iron fortification using the FS diet in the presence of tannic acid decreased the bioavailability of Zn and Rb. However, no effect of tannic acid on the uptake rate of metal was observed in NaFeEDTA diet, suggesting that iron fortification using NaFeEDTA is less affected by tannic acid than that using the FS diet. These results indicate that iron fortification using NaFeEDTA is an effective method for improving iron deficiency. (author)

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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. ...

  10. Absorption of manganese and iron in a mouse model of hemochromatosis.

    Directory of Open Access Journals (Sweden)

    Jonghan Kim

    Full Text Available Hereditary hemochromatosis, an iron overload disease associated with excessive intestinal iron absorption, is commonly caused by loss of HFE gene function. Both iron and manganese absorption are regulated by iron status, but the relationships between the transport pathways of these metals and how they are affected by HFE-associated hemochromatosis remain poorly understood. Loss of HFE function is known to alter the intestinal expression of DMT1 (divalent metal transporter-1 and Fpn (ferroportin, transporters that have been implicated in absorption of both iron and manganese. Although the influence of HFE deficiency on dietary iron absorption has been characterized, potential effects on manganese metabolism have yet to be explored. To investigate the role of HFE in manganese absorption, we characterized the uptake and distribution of the metal in Hfe (-/- knockout mice after intravenous, intragastric, and intranasal administration of (54Mn. These values were compared to intravenous and intragastric administration of (59Fe. Intestinal absorption of (59Fe was increased and clearance of injected (59Fe was also increased in Hfe(-/- mice compared to controls. Hfe (-/- mice displayed greater intestinal absorption of (54Mn compared to wild-type Hfe(+/+ control mice. After intravenous injection, the distribution of (59Fe to heart and liver was greater in Hfe (-/- mice but no remarkable differences were observed for (54Mn. Although olfactory absorption of (54Mn into blood was unchanged in Hfe (-/- mice, higher levels of intranasally-instilled (54Mn were associated with Hfe(-/- brain compared to controls. These results show that manganese transport and metabolism can be modified by HFE deficiency.

  11. Absorption of Manganese and Iron in a Mouse Model of Hemochromatosis

    Science.gov (United States)

    Kim, Jonghan; Buckett, Peter D.; Wessling-Resnick, Marianne

    2013-01-01

    Hereditary hemochromatosis, an iron overload disease associated with excessive intestinal iron absorption, is commonly caused by loss of HFE gene function. Both iron and manganese absorption are regulated by iron status, but the relationships between the transport pathways of these metals and how they are affected by HFE-associated hemochromatosis remain poorly understood. Loss of HFE function is known to alter the intestinal expression of DMT1 (divalent metal transporter-1) and Fpn (ferroportin), transporters that have been implicated in absorption of both iron and manganese. Although the influence of HFE deficiency on dietary iron absorption has been characterized, potential effects on manganese metabolism have yet to be explored. To investigate the role of HFE in manganese absorption, we characterized the uptake and distribution of the metal in Hfe −/− knockout mice after intravenous, intragastric, and intranasal administration of 54Mn. These values were compared to intravenous and intragastric administration of 59Fe. Intestinal absorption of 59Fe was increased and clearance of injected 59Fe was also increased in Hfe−/− mice compared to controls. Hfe −/− mice displayed greater intestinal absorption of 54Mn compared to wild-type Hfe+/+ control mice. After intravenous injection, the distribution of 59Fe to heart and liver was greater in Hfe −/− mice but no remarkable differences were observed for 54Mn. Although olfactory absorption of 54Mn into blood was unchanged in Hfe −/− mice, higher levels of intranasally-instilled 54Mn were associated with Hfe−/− brain compared to controls. These results show that manganese transport and metabolism can be modified by HFE deficiency. PMID:23705020

  12. Detection of the electronic structure of iron-(iii)-oxo oligomers forming in aqueous solutions.

    Science.gov (United States)

    Seidel, Robert; Kraffert, Katrin; Kabelitz, Anke; Pohl, Marvin N; Kraehnert, Ralph; Emmerling, Franziska; Winter, Bernd

    2017-12-13

    The nature of the small iron-oxo oligomers in iron-(iii) aqueous solutions has a determining effect on the chemical processes that govern the formation of nanoparticles in aqueous phase. Here we report on a liquid-jet photoelectron-spectroscopy experiment for the investigation of the electronic structure of the occurring iron-oxo oligomers in FeCl 3 aqueous solutions. The only iron species in the as-prepared 0.75 M solution are Fe 3+ monomers. Addition of NaOH initiates Fe 3+ hydrolysis which is followed by the formation of iron-oxo oligomers. At small enough NaOH concentrations, corresponding to approximately [OH]/[Fe] = 0.2-0.25 ratio, the iron oligomers can be stabilized for several hours without engaging in further aggregation. Here, we apply a combination of non-resonant as well as iron 2p and oxygen 1s resonant photoelectron spectroscopy from a liquid microjet to detect the electronic structure of the occurring species. Specifically, the oxygen 1s partial electron yield X-ray absorption (PEY-XA) spectra are found to exhibit a peak well below the onset of liquid water and OH - (aq) absorption. The iron 2p absorption gives rise to signal centered between the main absorption bands typical for aqueous Fe 3+ . Absorption bands in both PEY-XA spectra are found to correlate with an enhanced photoelectron peak near 20 eV binding energy, which demonstrates the sensitivity of resonant photoelectron (RPE) spectroscopy to mixing between iron and ligand orbitals. These various signals from the iron-oxo oligomers exhibit maximum intensity at [OH]/[Fe] = 0.25 ratio. For the same ratio, we observe changes in the pH as well as in complementary Raman spectra, which can be assigned to the transition from monomeric to oligomeric species. At approximately [OH]/[Fe] = 0.3 we begin to observe particles larger than 1 nm in radius, detected by small-angle X-ray scattering.

  13. Enhanced microwave absorption in ZnO/carbonyl iron nano-composites by coating dielectric material

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Chang [School of Physics and Material Science, Anhui University, Hefei 230036 (China); Key Laboratory of Opto-electronic Information Acquisition and Manipulation Ministry of Education, Anhui University, Hefei 230039 (China); Fang Qingqing, E-mail: physfangqq@126.com [School of Physics and Material Science, Anhui University, Hefei 230036 (China) and Key Laboratory of Opto-electronic Information Acquisition and Manipulation Ministry of Education, Anhui University, Hefei 230039 (China); Yan Fangliang; Wang Weina; Wu Keyue; Liu Yanmei; Lv Qingrong; Zhang Hanming; Zhang Qiping; Li Jinguang; Ding Qiongqiong [School of Physics and Material Science, Anhui University, Hefei 230036 (China); Key Laboratory of Opto-electronic Information Acquisition and Manipulation Ministry of Education, Anhui University, Hefei 230039 (China)

    2012-05-15

    The microwave absorption properties of zinc oxide/carbonyl iron composite nanoparticles fabricated by high energy ball milling were studied at 0-20 GHz. Experiments showed that ZnO as a kind of dielectric material coating carbonyl iron particles made the bandwidth of reflection loss (RL)<-5 dB expanding to the low frequency, and enhanced absorption effect obviously. For a 3 mm thickness absorber of ZnO/carbonyl iron after 30 h milling, the values of RL<-5 dB and RL<-8 dB were obtained in the frequency range from 7.0 GHz to 17.8 GHz and from 9.8 dB to 14.9 dB, respectively, and its strongest RL peak was -29.34 dB at 13.59 GHz. The magnetic loss of carbonyl iron particles and the dielectric loss of ZnO particles were the main mechanisms of microwave absorption for the composites. - Highlights: Black-Right-Pointing-Pointer We fabricated zinc oxide/carbonyl iron composites by high energy ball milling. Black-Right-Pointing-Pointer ZnO dielectric property increased absorption effect and absorption bandwidth. Black-Right-Pointing-Pointer Absorbing frequence of composites is expanding to low frequency direction. Black-Right-Pointing-Pointer The craft of high energy ball milling is easy to realize commerce production.

  14. Enhanced microwave absorption in ZnO/carbonyl iron nano-composites by coating dielectric material

    International Nuclear Information System (INIS)

    Zhou Chang; Fang Qingqing; Yan Fangliang; Wang Weina; Wu Keyue; Liu Yanmei; Lv Qingrong; Zhang Hanming; Zhang Qiping; Li Jinguang; Ding Qiongqiong

    2012-01-01

    The microwave absorption properties of zinc oxide/carbonyl iron composite nanoparticles fabricated by high energy ball milling were studied at 0–20 GHz. Experiments showed that ZnO as a kind of dielectric material coating carbonyl iron particles made the bandwidth of reflection loss (RL)<−5 dB expanding to the low frequency, and enhanced absorption effect obviously. For a 3 mm thickness absorber of ZnO/carbonyl iron after 30 h milling, the values of RL<−5 dB and RL<−8 dB were obtained in the frequency range from 7.0 GHz to 17.8 GHz and from 9.8 dB to 14.9 dB, respectively, and its strongest RL peak was −29.34 dB at 13.59 GHz. The magnetic loss of carbonyl iron particles and the dielectric loss of ZnO particles were the main mechanisms of microwave absorption for the composites. - Highlights: ► We fabricated zinc oxide/carbonyl iron composites by high energy ball milling. ► ZnO dielectric property increased absorption effect and absorption bandwidth. ► Absorbing frequence of composites is expanding to low frequency direction. ► The craft of high energy ball milling is easy to realize commerce production.

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

    Directory of Open Access Journals (Sweden)

    Fabian Esamai

    2014-12-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  17. Effects of iron deficiency on the absorption and distribution of lead and cadmium in rats

    International Nuclear Information System (INIS)

    Ragan, H.A.

    1977-01-01

    In order to evaluate the effects of iron deficiency on the absorption of pollutant metals, an iron-deficient diet was fed to young rats until their tissue-iron stores were depleted. Prior to the development of anemia, the iron-deficient rats and littermate controls were administered an intragastric gavage of lead-210 or cadmium-109 and were killed 48 hr later. The body burden of lead was approximately 6 times greater, and that of cadmium approximately 7 times greater, in iron-deficient rats than in the controls. No consistent effects were observed on concentrations of serum total lipids or serum proteins nor on protein electrophoretic patterns in rats with a deficit in iron stores

  18. Iron in Alzheimer's and Control Hippocampi - Moessbauer, Atomic Absorption and ELISA Studies

    International Nuclear Information System (INIS)

    Galazka-Friedman, J.; Szlachta, K.; Bauminger, E.R.; Koziorowski, D.; Friedman, A.; Tomasiuk, R.; Jaklewicz, A.; Wszolek, Z.K.; Dickson, D.; Kaplinska, K.

    2011-01-01

    Alzheimer disease is a neurodegenerative process of unknown mechanism taking place in a part of the brain - hippocampus. Oxidative stress and the role of iron in it is one of the suggested mechanisms of cells death. In this study several methods were used to assess iron and iron binding compounds in human hippocampus tissues. Moessbauer spectroscopy was used for identification of the iron binding compound and determination of total iron concentration in 12 control and one Alzheimer disease sample of hippocampus. Moessbauer parameters obtained for all samples suggest that most of the iron is ferritin-like iron. The average concentration of iron determined by Moessbauer spectroscopy in control hippocampus was 45 ± 10 ng/mg wet tissue. The average concentration of iron in 10 Alzheimer disease samples determined by atomic absorption was 66 ± 13 ng/mg wet tissue. The concentration of H and L chains of ferritin in 20 control and 10 AD hippocampi was assessed with enzyme-linked immuno-absorbent assay. The concentration of H and L ferritin was higher in Alzheimer disease compared to control (19.36 ± 1.51 vs. 5.84 ± 0.55 ng/μg protein for H, and 1.39 ± 0.25 vs. 0.55 ± 0.10 for L). This 3-fold increase of the concentration of ferritin is accompanied by a small increase of the total iron concentration. (authors)

  19. Green tea or rosemary extract added to foods reduces nonheme- iron absorption

    DEFF Research Database (Denmark)

    Samman, S.; Sandstrøm, B.; Toft, M.B.

    2001-01-01

    the effect of phenolic-rich extracts obtained from green tea or rosemary on nonheme-iron absorption. Design: Young women aged 19-39 y consumed test meals on 4 separate occasions. The meals were identical except for the absence (meal A) or presence (meal B) of a phenolic-rich extract from green tea (study 1......-body retention of 59Fe and the ratio of Fe-55 to 59Fe activity in blood samples. Results: The presence of the phenolic-rich extracts resulted in decreased nonheme-iron absorption. Mean (+/-SD) iron absorption decreased from 12.1 +/- 4.5% to 8.9 +/- 5.2% (P tea extract and from 7...

  20. The effect of water on the stability of iron oxide and iron carbide nanoparticles in hydrogen and syngas followed by in situ X-ray absorption spectroscopy

    NARCIS (Netherlands)

    Thuene, P.C.; Moodley - Gengan, P.; Scheijen, F.J.E.; Fredriksson, H.O.A.; Lancee, R.J.; Kropf, J.; Miller, J.T.; Niemantsverdriet, J.W.

    2012-01-01

    The effect of water on iron-based nanoparticles under hydrogen and syngas was investigated by in situ X-ray absorption spectroscopy. The iron oxide (¿-Fe2O3) nanoparticles, dispersed as a monolayer on flat silica surfaces, were readily converted into metallic iron in dry hydrogen at 350 °C and into

  1. Ultrafast transient-absorption of the solvated electron in water

    International Nuclear Information System (INIS)

    Kimura, Y.; Alfano, J.C.; Walhout, P.K.; Barbara, P.F.

    1994-01-01

    Ultrafast near infrared (NIR)-pump/variable wavelength probe transient-absorption spectroscopy has been performed on the aqueous solvated electron. The photodynamics of the solvated electron excited to its p-state are qualitatively similar to previous measurements of the dynamics of photoinjected electrons at high energy. This result confirms the previous interpretation of photoinjected electron dynamics as having a rate-limiting bottleneck at low energies presumably involving the p-state

  2. Iron interference in arsenic absorption by different plant species, analysed by neutron activation, k0-method

    International Nuclear Information System (INIS)

    Uemura, George; Matos, Ludmila Vieira da Silva; Silva, Maria Aparecida da; Menezes, Maria Angela de Barros Correia

    2009-01-01

    Natural arsenic contamination is a cause for concern in many countries of the world including Argentina, Bangladesh, Chile, China, India, Mexico, Thailand, United States of America and also in Brazil, specially in the Iron Quadrangle area, where mining activities have been contributing to aggravate natural contamination. Among other elements, iron is capable to interfere with the arsenic absorption by plants; iron ore has been proposed to remediate areas contaminated by the mentioned metalloid. In order to verify if iron can interfere with arsenic absorption by different taxa of plants, specimens of Brassicacea and Equisetaceae were kept in a 1/4 Murashige and Skoog basal salt solution (M and S), with 10 μgL -1 of arsenic acid. And varying concentrations of iron. The specimens were analysed by neutron activation analysis, k 0 -method, a routine technique in CDTN, and also very appropriate for arsenic studies. The preliminary results were quite surprising, showing that iron can interfere with arsenic absorption by plants, but in different ways, according to the species studied. (author)

  3. A study of phosphate absorption by magnesium iron hydroxycarbonate.

    Science.gov (United States)

    Du, Yi; Rees, Nicholas; O'Hare, Dermot

    2009-10-21

    A study of the mechanism of phosphate adsorption by magnesium iron hydroxycarbonate, [Mg(2.25)Fe(0.75)(OH)(6)](CO(3))(0.37).0.65H(2)O over a range of pH has been carried out. The efficiency of the phosphate removal from aqueous solution has been investigated between pH 3-9 and the resulting solid phases have been studied by elemental analysis, XRD, FT-IR, Raman, HRTEM, EDX and solid-state MAS (31)P NMR. The analytical and spectroscopic data suggest that phosphate removal from solution occurs not by anion intercalation of the relevant phosphorous oxyanion (H(2)PO(4)(-) or HPO(4)(2-)) into the LDH but by the precipitation of either an insoluble iron hydrogen phosphate hydrate and/or a magnesium phosphate hydrate.

  4. The Effects of Dietary Calcium and/or Iron Deficiency upon Murine Intestinal Calcium Binding Protein Activity and Calcium Absorption

    OpenAIRE

    McDonald, Catherine M.

    1980-01-01

    Iron deficiency has been shown to impair calcium absorption, leading to decreased bone mass. Vitamin D3-dependent calcium binding protein (CaBP) has been demonstrated to be necessary for the active transport of calcium in the intestine of numerous species. Iron deficiency might affect the activity of the calcium binding protein. Four experimental diets were formulated as follows: Diet 1, iron adequate, calcium adequate; Diet 2, iron deficient, calcium adequate; Diet 3, iron adequate, calci...

  5. In overweight and obese women, dietary iron absorption is reduced and the enhancement of iron absorption by ascorbic acid is one-half that in normal-weight women

    NARCIS (Netherlands)

    Cepeda-Lopez, A.C.; Melse, A.; Zimmermann, M.B.; Herter-Aeberli, I.

    2015-01-01

    Background: Iron deficiency is common in overweight and obese individuals. This deficiency may be due to adiposity-related inflammation that increases serum hepcidin and decreases dietary iron absorption. Because hepcidin reduces iron efflux from the basolateral enterocyte, it is uncertain whether

  6. Ferrous and hemoglobin-59Fe absorption from supplemented cow milk in infants with normal and depleted iron stores

    International Nuclear Information System (INIS)

    Heinrich, H.C.; Gabbe, E.E.; Whang, D.H.; Bender-Goetze, C.; Schaefer, K.H.; Hamburg Univ.

    1975-01-01

    Small amounts of milk do inhibit ferrous iron absorption from a 5 mg 59 Fe 2+ dose in 1- to 18-month-old infants. Only 50 ml of 2/3 cow milk reduced the absorption from 18 to 3.8% in infants with normal iron stores (inhibition index 0.21) and from 26 to 8.5% in [de

  7. Iron and zinc absorption from weaning foods prepared from germinated cereals and legumes using isotope tracers

    Energy Technology Data Exchange (ETDEWEB)

    Valdez, D H; Kuizon, M D; Marero, L M; Mallillin, A C; Cruz, E M; Madriaga, J R [Department of Science and Technology, Manila (Philippines). Food and Nutrition Research Inst.

    1994-12-31

    Iron bioavailability from weaning foods prepared from 70:30 combination of germinated rice:mungbean (GRM); germinated rice: cowpea (GRC) and germinated corn:mungbean (GCM) was determined by radioisotopic measurements of iron absorption in human subjects. The gruels were prepared as plain with sugar and flavoring labeled by the extrinsic tag method, and served as hot porridge. It was estimated that iron-deficient infants would absorb 3.5% from GRM, 4.9% from GRC and 5.6% from GCM. Differences between absorption among the weaning foods were not statistically significant. Planning of diets for these age group should include other sources of iron especially heme. Zinc absorption from the weaning food formulations will be studied by the in vitro and in vivo methods. For the in vivo method on human subjects, the absorption of zinc will be determined from the measurement of the whole body retention of the isotope 14 days after intake of the labeled mean. Serum zinc level will be determined to assess the zinc status of the subjects. (author). 23 refs, 1 fig., 4 tabs.

  8. Iron and zinc absorption from weaning foods prepared from germinated cereals and legumes using isotope tracers

    International Nuclear Information System (INIS)

    Valdez, D.H.; Kuizon, M.D.; Marero, L.M.; Mallillin, A.C.; Cruz, E.M.; Madriaga, J.R.

    1994-01-01

    Iron bioavailability from weaning foods prepared from 70:30 combination of germinated rice:mungbean (GRM); germinated rice: cowpea (GRC) and germinated corn:mungbean (GCM) was determined by radioisotopic measurements of iron absorption in human subjects. The gruels were prepared as plain with sugar and flavoring labeled by the extrinsic tag method, and served as hot porridge. It was estimated that iron-deficient infants would absorb 3.5% from GRM, 4.9% from GRC and 5.6% from GCM. Differences between absorption among the weaning foods were not statistically significant. Planning of diets for these age group should include other sources of iron especially heme. Zinc absorption from the weaning food formulations will be studied by the in vitro and in vivo methods. For the in vivo method on human subjects, the absorption of zinc will be determined from the measurement of the whole body retention of the isotope 14 days after intake of the labeled mean. Serum zinc level will be determined to assess the zinc status of the subjects. (author). 23 refs, 1 fig., 4 tabs

  9. Absorption of resonant electromagnetic radiation in electron-atom collisions

    International Nuclear Information System (INIS)

    Arslanbekov, T.U.; Pazdzerskii, V.A.; Usachenko, V.I.

    1986-01-01

    Nonrelativistic quantum theory is used to study the possibility of amplification of electromagnetic radiation in forced braking scattering of an electron beam on atoms. The interaction of the atom with the electromagnetic field is considered in the resonant approximation. Cases of large and small detuning from resonance are considered. It is shown that for any orientation of the electron beam relative to the field polarization vector, absorption of radiation occurs, with the major contribution being produced by atomic electrons

  10. Effect of excess supply of heavy metals on the absorption and translocation of iron (/sup 59/Fe) in barley

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, C P; Bisht, S S; Agarwala, S C [Lucknow Univ. (India). Dept. of Botany

    1978-03-01

    The effects of an excess supply of manganese, copper, zinc, cobalt, and nickel on the absorption and translocation of iron tagged with /sup 59/Fe were xamined in 15 days old barley seedlings raised in solution culture. Excess heavy metal treatments and /sup 59/Fe were administered in three different ways: (i) both excess heavy metals and iron supplied through roots- Series A; (ii) excess heavy metal supplied as foliar spray and iron through roots- Series B; and (iii) excess heavy metal supplied through roots and iron as foliar spray-Series C. Results obtained revealed that excess concentrations of manganese, zinc, cobalt, and a to a lesser extent copper interfered with the absorption of iron from the rooting medium, but excess nickel enhanced the absorption and translocation of iron. Thus, unlike other metals, a toxic supply of nickel does not induce iron deficiency.

  11. Electron localization and optical absorption of polygonal quantum rings

    Science.gov (United States)

    Sitek, Anna; Serra, Llorenç; Gudmundsson, Vidar; Manolescu, Andrei

    2015-06-01

    We investigate theoretically polygonal quantum rings and focus mostly on the triangular geometry where the corner effects are maximal. Such rings can be seen as short core-shell nanowires, a generation of semiconductor heterostructures with multiple applications. We show how the geometry of the sample determines the electronic energy spectrum, and also the localization of electrons, with effects on the optical absorption. In particular, we show that irrespective of the ring shape low-energy electrons are always attracted by corners and are localized in their vicinity. The absorption spectrum in the presence of a magnetic field shows only two peaks within the corner-localized state domain, each associated with different circular polarization. This picture may be changed by an external electric field which allows previously forbidden transitions, and thus enables the number of corners to be determined. We show that polygonal quantum rings allow absorption of waves from distant ranges of the electromagnetic spectrum within one sample.

  12. Absorption distances in the dynamical theory of electron diffraction

    International Nuclear Information System (INIS)

    Kamiya, Yoshihiko; Goto, Toshiaki.

    1982-01-01

    The contrast effect of the electron microscopic image at crystal defects is characterized by two parameters; extincion distance and absorption distance. Both quantities are orginally defined for the elastic scattering. Since the inelastic scattering contributes to the electron microscopic image, parameters used for the interpretation of the images are not the same as those for the elastic scattering. It is shown that the difference of absorption distance beteen the theoretical estimation and that used for interpretation is due to the contrst effect of the small angle inelastic scattering. (author)

  13. Liquid-Liquid Extraction and Determination of Trace Elements in Iron Minerals by Atomic Absorption Spectrometry

    International Nuclear Information System (INIS)

    Taseska, Milena; Stafilov, Trajche; Makreski, Petre; Jacimovic, Radojko; Jovanovski, Gligor

    2006-01-01

    Various trace elements (cadmium, chromium, cobalt, nickel, manganese) in some iron minerals were determined by flame (FAAS) and electrothermal atomic absorption spectrometry (ETAAS). The studied minerals were chalcopyrite (CuFeS 2 ), hematite (Fe 2 O 3 ) and pyrite (FeS 2 ). To avoid the interference of iron, a method for liquid-liquid extraction of iron and determination of investigated elements in the inorganic phase was proposed. Iron was extracted by diisopropyl ether in hydrochloride acid solution and the extraction method was optimized. Some parameters were obtained to be significantly important: Fe mass in the sample should not exceed 0.3 g, the optimal concentration of HCI should be 7.8 mol 1 -1 and ratio of the inorganic and organic phase should be 1: 1. The procedure was verified by the method of standard additions and by its applications to reference standard samples. The investigated minerals originate from various mines in the Republic of Macedonia. (Author)

  14. New perspectives on the regulation of iron absorption via cellular zinc concentrations in humans.

    Science.gov (United States)

    Knez, Marija; Graham, Robin D; Welch, Ross M; Stangoulis, James C R

    2017-07-03

    Iron deficiency is the most prevalent nutritional deficiency, affecting more than 30% of the total world's population. It is a major public health problem in many countries around the world. Over the years various methods have been used with an effort to try and control iron-deficiency anemia. However, there has only been a marginal reduction in the global prevalence of anemia. Why is this so? Iron and zinc are essential trace elements for humans. These metals influence the transport and absorption of one another across the enterocytes and hepatocytes, due to similar ionic properties. This paper describes the structure and roles of major iron and zinc transport proteins, clarifies iron-zinc interactions at these sites, and provides a model for the mechanism of these interactions both at the local and systemic level. This review provides evidence that much of the massive extent of iron deficiency anemia in the world may be due to an underlying deficiency of zinc. It explains the reasons for predominance of cellular zinc status in determination of iron/zinc interactions and for the first time thoroughly explains mechanisms by which zinc brings about these changes.

  15. Absorptive form factors for high-energy electron diffraction

    International Nuclear Information System (INIS)

    Bird, D.M.; King, Q.A.

    1990-01-01

    The thermal diffuse scattering contribution to the absorptive potential in high-energy electron diffraction is calculated in the form of an absorptive contribution to the atomic form factor. To do this, the Einstein model of lattice vibrations is used, with isotropic Debye-Waller factors. The absorptive form factors are calculated as a function of scattering vector s and temperature factor M on a grid which enables polynomial interpolation of the results to be accurate to better than 2% for much of the ranges 0≤Ms 2 ≤6 and 0≤M≤2 A 2 . The computed values, together with an interpolation routine, have been incorporated into a Fortran subroutine which calculates both the real and absorptive form factors for 54 atomic species. (orig.)

  16. Study of the pattern of iron absorption and utilization in anaemias associated with malnutrition

    International Nuclear Information System (INIS)

    Ahmed, K.

    1976-06-01

    The objective of this investigation was to observe in poor populations, generally malnourished and anemic, the effect on hemoglobin level and percentage iron absorption of (1) an improved diet and (2) vitamin C supplementation alone. Percentage iron absorption was measured, after consumption of a meal into which 3-5 μCi 59 Fe as ferrous sulphate had been homogeneously mixed, by whole-body counting and also by measuring the concentration of the isotope in the blood at about two weeks. As subjects of the investigation were used adult males and females, from poor local population groups, who had no hookworm or other problems causing bleeding. A total of 236 subjects, subsequent to a preliminary screening and performance of appropriate laboratory tests, were placed on an improved diet containing about 300 g/d protein in the form of fish, meat, and pulses, plus leafy vegetables. It could not be assured, however, that all continued to take this diet during most of the 90-180 d test period during which they lived at home. Measurements were made of hemoglobin level and percentage absorption of iron from a test meal, before and after the test period of improved nutrition. In females the hemoglobin level (g/100 ml blood) rose from 10.2+-0.5 to 12.4+-0.4, and in males from 9.8+-0.4 to 12.3+-0.5, where errors quoted are standard errors of the mean. In females the percentage iron absorption rose from 18.8%+-1.8% to 24.5%+-2.5%, and in males from 14.4%+-1.6% to 19.2%+-2.2%. All the increases were judged to be statistically significant. Another group of 220 subjects, after preliminary screening, were told to take vitamin C supplements of 100 mg/d with their two principal meals over a period of 90-120 days. Hemoglobin levels, but not iron absorption from a test meal containing no supplement of vitamin C, was found to be statistically significantly improved at the end of the test period. This confirms the potential of vitamin C as a supplement for improving absorption of dietary

  17. Electrochemical permeation tests on the kinetics of the hydrogen absorption of palladium and iron

    International Nuclear Information System (INIS)

    Dafft, E.G.

    1977-01-01

    Electrochemical permeation tests were performed to investigate the kinetics of the hydrogen development and hydrogen absorption. The cathode side of the samples was galvanostatically cathodically polarized in different electrolyte solutions with and without additions. THe hydrogen atoms diffusing out of the opposite side for iron and α-palladium were oxidized with potentiostatic, sufficiently anodic polarization. The thus registered stationary current is proportional to the hydrogen activity on the cathode side. Test apparatus and conditions are described. The measurements on iron are discussed. (orig./HPOE) [de

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

    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

  20. Absorption and luminescence of crystalline quartz under electron nanosecond irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Gritsenko, B P; Lisitsyn, V M; Stepanchuk, V N [Tomskij Politekhnicheskij Inst. (USSR)

    1981-02-01

    The purpose of the study is continuation of investigations of principal regularities of production and destruction of short-lived defects in quartz and accompanying luminescence under electron pulse irradiation. For investigation purposes samples of crystalline synthetic quartz have been used. The irradiation has been performed at 80-400 K temperatures by means of an electron pulse accelerator with parameters: electron flow pulse duration 10 ns, pulse current density up to 1000 A/cm/sup 2/, electron mean energy 200 keV. Temperature-time characteristics of absorption and luminescence spectrum are studied. It has been found that quartz irradiation by electron pulses of nanosecond duration leads to appearance of short-lived bands of optical absorption at 4.1 and 5.15 eV to which by kinetic parameters correspond luminescence bands at 2.6 and 3.1 eV, respectively. The enumerated absorption bands are induced by quartz irradiation independently of the prehistory and phase state of the sample and are caused obviously by intrinsic radiation defects. Possible models of such defects are suggested.

  1. Stochasticity of the energy absorption in the electron cyclotron resonance

    International Nuclear Information System (INIS)

    Gutierrez T, C.; Hernandez A, O.

    1998-01-01

    The energy absorption mechanism in cyclotron resonance of the electrons is a present problem, since it could be considered from the stochastic point of view or this related with a non-homogeneous but periodical of plasma spatial structure. In this work using the Bogoliubov average method for a multi periodical system in presence of resonances, the drift equations were obtained in presence of a RF field for the case of electron cyclotron resonance until first order terms with respect to inverse of its cyclotron frequency. The absorbed energy equation is obtained on part of electrons in a simple model and by drift method. It is showed the stochastic character of the energy absorption. (Author)

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

    Science.gov (United States)

    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 (Pphytase increased fractional iron absorption 3.2 times, suggesting it could be a possible strategy to decrease PA in cereal-based porridges. PMID:24124445

  3. Consumption of galacto-oligosaccharides increases iron absorption from a micronutrient powder containing ferrous fumarate and sodium iron EDTA: a stable-isotope study in Kenyan infants.

    Science.gov (United States)

    Paganini, Daniela; Uyoga, Mary A; Cercamondi, Colin I; Moretti, Diego; Mwasi, Edith; Schwab, Clarissa; Bechtler, Salome; Mutuku, Francis M; Galetti, Valeria; Lacroix, Christophe; Karanja, Simon; Zimmermann, Michael B

    2017-10-01

    Background: Whether consumption of prebiotics increases iron absorption in infants is unclear. Objective: We set out to determine whether prebiotic consumption affects iron absorption from a micronutrient powder (MNP) containing a mixture of ferrous fumarate and sodium iron EDTA (FeFum+NaFeEDTA) in Kenyan infants. Design: Infants ( n = 50; aged 6-14 mo) consumed maize porridge that was fortified with an MNP containing FeFum+NaFeEDTA and 7.5 g galacto-oligosaccharides (GOSs) (Fe+GOS group, n = 22) or the same MNP without GOSs (Fe group, n = 28) each day for 3 wk. Then, on 2 consecutive days, we fed all infants isotopically labeled maize porridge and MNP test meals containing 5 mg Fe as 57 FeFum+Na 58 FeEDTA or ferrous sulfate ( 54 FeSO 4 ). Iron absorption was measured as the erythrocyte incorporation of stable isotopes. Iron markers, fecal pH, and bacterial groups were assessed at baseline and 3 wk. Comparisons within and between groups were done with the use of mixed-effects models. Results: There was a significant group-by-compound interaction on iron absorption ( P = 0.011). The median percentages of fractional iron absorption from FeFum+NaFeEDTA and from FeSO 4 in the Fe group were 11.6% (IQR: 6.9-19.9%) and 20.3% (IQR: 14.2-25.7%), respectively, ( P iron absorption was greater from the FeFum+NaFeEDTA ( P = 0.047) in the Fe+GOS group but not from the FeSO 4 ( P = 0.653). The relative iron bioavailability from FeFum+NaFeEDTA compared with FeSO 4 was higher in the Fe+GOS group than in the Fe group (88% compared with 63%; P = 0.006). There was a significant time-by-group interaction on Bifidobacterium spp. ( P = 0.008) and Lactobacillus / Pediococcus / Leuconostoc spp. ( P = 0.018); Lactobacillus / Pediococcus / Leuconostoc spp. decreased in the Fe group ( P = 0.013), and there was a nonsignificant trend toward higher Bifidobacterium spp. in the Fe+GOS group ( P = 0.099). At 3 wk, iron absorption was negatively correlated with fecal pH ( P iron absorption by 62

  4. Kinetics of iron redox reactions in silicate liquids: A high-temperature X-ray absorption and Raman spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Magnien, V. [Physique des Mineraux et Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France); CEA VALRHO Marcoule, SCDV, LEBV, BP 17171, 30207 Bagnols/Ceze (France); Neuville, D.R. [Physique des Mineraux et Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France)]. E-mail: neuville@ipgp.jussieu.fr; Cormier, L. [IMPMC, CNRS UMR 7590, Universites Paris 6 and 7 and IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France); Roux, J. [Physique des Mineraux et Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France); Hazemann, J.-L. [Laboratoire de cristallographie, UPR 5031, CNRS, 38043 Grenoble (France); Pinet, O. [CEA VALRHO Marcoule, SCDV, LEBV, BP 17171, 30207 Bagnols/Ceze (France); Richet, P. [Physique des Mineraux et Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France)

    2006-06-30

    The oxidation kinetics of a Fe-bearing supercooled liquid of the system SiO{sub 2}-CaO-MgO-Na{sub 2}O-FeO has been determined near the glass transition range by X-ray absorption near edge structure (XANES) and Raman spectroscopies. Both techniques yield room-temperature iron redox ratios in accord with wet chemical, Moessbauer and electron microprobe analyses. Similar oxidation kinetics have also been observed with both methods. At constant temperature, the kinetics obey an exponential law with a characteristic time that follows an Arrhenian temperature dependence. As redox changes are too fast to be accounted for in terms of diffusion of either ionic or molecular oxygen, these results lend further support to the idea that the rate-limiting factor for oxidation near the glass transition is diffusion of network-modifying cations along with a flux of electron holes.

  5. Robust parameterization of elastic and absorptive electron atomic scattering factors

    International Nuclear Information System (INIS)

    Peng, L.M.; Ren, G.; Dudarev, S.L.; Whelan, M.J.

    1996-01-01

    A robust algorithm and computer program have been developed for the parameterization of elastic and absorptive electron atomic scattering factors. The algorithm is based on a combined modified simulated-annealing and least-squares method, and the computer program works well for fitting both elastic and absorptive atomic scattering factors with five Gaussians. As an application of this program, the elastic electron atomic scattering factors have been parameterized for all neutral atoms and for s up to 6 A -1 . Error analysis shows that the present results are considerably more accurate than the previous analytical fits in terms of the mean square value of the deviation between the numerical and fitted scattering factors. Parameterization for absorptive atomic scattering factors has been made for 17 important materials with the zinc blende structure over the temperature range 1 to 1000 K, where appropriate, and for temperature ranges for which accurate Debye-Waller factors are available. For other materials, the parameterization of the absorptive electron atomic scattering factors can be made using the program by supplying the atomic number of the element, the Debye-Waller factor and the acceleration voltage. For ions or when more accurate numerical results for neutral atoms are available, the program can read in the numerical values of the elastic scattering factors and return the parameters for both the elastic and absorptive scattering factors. The computer routines developed have been tested both on computer workstations and desktop PC computers, and will be made freely available via electronic mail or on floppy disk upon request. (orig.)

  6. Microwave absorption properties of a wave-absorbing coating employing carbonyl-iron powder and carbon black

    International Nuclear Information System (INIS)

    Liu Lidong; Duan Yuping; Ma Lixin; Liu Shunhua; Yu Zhen

    2010-01-01

    To prevent serious electromagnetic interference, a single-layer wave-absorbing coating employing complex absorbents composed of carbonyl-iron powder (CIP) and carbon black (CB) with epoxy resin as matrix was prepared. The morphologies of CIP and CB were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The electromagnetic parameters of CIP and CB were measured in the frequency range of 2-18 GHz by transmission/reflection technology, and the electromagnetic loss mechanisms of the two particles were discussed, respectively. The microwave absorption properties of the coatings were investigated by measuring reflection loss (RL) using arch method. The effects of CIP ratio, CB content and thickness on the microwave absorption properties were discussed, respectively. The results showed that the higher thickness, CIP or CB content could make the absorption band shift towards the lower frequency range. Significantly, the wave-absorbing coating could be applied in different frequency ranges according to actual demand by controlling the content of CIP or CB in composites.

  7. Microwave absorption properties of a wave-absorbing coating employing carbonyl-iron powder and carbon black

    Science.gov (United States)

    Liu, Lidong; Duan, Yuping; Ma, Lixin; Liu, Shunhua; Yu, Zhen

    2010-11-01

    To prevent serious electromagnetic interference, a single-layer wave-absorbing coating employing complex absorbents composed of carbonyl-iron powder (CIP) and carbon black (CB) with epoxy resin as matrix was prepared. The morphologies of CIP and CB were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The electromagnetic parameters of CIP and CB were measured in the frequency range of 2-18 GHz by transmission/reflection technology, and the electromagnetic loss mechanisms of the two particles were discussed, respectively. The microwave absorption properties of the coatings were investigated by measuring reflection loss (RL) using arch method. The effects of CIP ratio, CB content and thickness on the microwave absorption properties were discussed, respectively. The results showed that the higher thickness, CIP or CB content could make the absorption band shift towards the lower frequency range. Significantly, the wave-absorbing coating could be applied in different frequency ranges according to actual demand by controlling the content of CIP or CB in composites.

  8. The role of iron and black carbon in aerosol light absorption

    Directory of Open Access Journals (Sweden)

    Y. Derimian

    2008-07-01

    Full Text Available Iron is a major component of atmospheric aerosols, influencing the light absorption ability of mineral dust, and an important micronutrient that affects oceanic biogeochemistry. The regional distribution of the iron concentration in dust is important for climate studies; however, this is difficult to obtain since it requires in-situ aerosol sampling or simulation of complex natural processes. Simultaneous studies of aerosol chemical composition and radiometric measurements of aerosol optical properties, which were performed in the Negev desert of Israel continuously for about eight years, suggest a potential for deriving a relationship between chemical composition and light absorption properties, in particular the spectral single-scattering albedo.

    The two main data sets of the present study were obtained by a sun/sky radiometer and a stacked filter unit sampler that collects particles in coarse and fine size fractions. Analysis of chemical and optical data showed the presence of mixed dust and pollution aerosol in the study area, although their sources appear to be different. Spectral SSA showed an evident response to increased concentrations of iron, black carbon equivalent matter, and their mixing state. A relationship that relates the spectral SSA, the percentage of iron in total particulate mass, and the pollution components was derived. Results calculated, using this relationship, were compared with measurements from dust episodes in several locations around the globe. The comparison showed reasonable agreement between the calculated and the observed iron concentrations, and supported the validity of the suggested approach for the estimation of iron concentrations in mineral dust.

  9. Influence of food tannins on certain aspects of iron metabolism : Part 1 -- Absorption and excretion in normal and anemic rats

    Energy Technology Data Exchange (ETDEWEB)

    Roy, S N [Albert Einstein Coll. of Medicine, Bronx, NY (USA); Mukher ee, S [Calcutta Univ. (India). Dept. of Applied Chemistry

    1979-04-01

    Studies on absorption and excretion of iron by isotopic and non-isotopic methods in normal and hemolytic anemic rats indicate that dietary food tannins at a dose of 0.5 mg/kg body wt/day tend to increase iron excretion in normal rats but more iron is absorbed or retained in tannin-fed anemic rats and absorption of iron is comparable to that in normal control. Both in vivo and in vitro tannin at a high dose (2.0 mg/kg body wt/day) inhibits the iron absorption in experimental animals. The interference of food tannins (0.5 kg/mg body wt/day) with absorption of iron (/sup 59/Fe) varies with plant species from which tannin has been prepared. Normal iron balance in tannin-fed (0.5 mg/kg body wt/day) anemic rats may result from increased assimilation of tannin-bound iron in intestinal mucosa, and absorbed tannin appears to remove unabsorbed iron.

  10. Electron uptake by iron-oxidizing phototrophic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Bose, A; Gardel, EJ; Vidoudez, C; Parra, EA; Girguis, PR

    2014-02-26

    Oxidation-reduction reactions underlie energy generation in nearly all life forms. Although most organisms use soluble oxidants and reductants, some microbes can access solid-phase materials as electron-acceptors or -donors via extracellular electron transfer. Many studies have focused on the reduction of solid-phase oxidants. Far less is known about electron uptake via microbial extracellular electron transfer, and almost nothing is known about the associated mechanisms. Here we show that the iron-oxidizing photoautotroph Rhodopseudomonas palustris TIE-1 accepts electrons from a poised electrode, with carbon dioxide as the sole carbon source/electron acceptor. Both electron uptake and ruBisCo form I expression are stimulated by light. Electron uptake also occurs in the dark, uncoupled from photosynthesis. Notably, the pioABC operon, which encodes a protein system essential for photoautotrophic growth by ferrous iron oxidation, influences electron uptake. These data reveal a previously unknown metabolic versatility of photoferrotrophs to use extracellular electron transfer for electron uptake.

  11. Determination of copper and iron in the human aqueous humor by atomic absorption spectrometer with graphite furnace

    International Nuclear Information System (INIS)

    Iqbal, Z.; Mohammad, Z.; Shah, M.T.; Saeed, M.; Imdadullah

    1999-01-01

    The concentration of copper and iron was determined in human aqueous humor using atomic absorption spectrophotometer equipped with graphite furnace. The mean (+- SEM) concentrations of copper (n=16) and iron (n=14) were 0.0234 -+ 0.0045 mu g.ml/sup -1/ and 0.045 -+ 0.0092 mu.ml/sup -1/ respectively. In male and female, the concentrations of copper (p< 0.82) and iron (p<0.38) were not significantly different. (author)

  12. Redox behaviors of iron by absorption spectroscopy and redox potential measurement

    International Nuclear Information System (INIS)

    Oh, Jae Yong

    2010-02-01

    This work is performed to study the redox (reduction/oxidation) behaviors of iron in aqueous system by a combination of absorption spectroscopy and redox potential measurements. There are many doubts on redox potential measurements generally showing low accuracies and high uncertainties. In the present study, redox potentials are measured by utilizing various redox electrodes such as Pt, Au, Ag, and glassy carbon (GC) electrodes. Measured redox potentials are compared with calculated redox potentials based on the chemical oxidation speciation of iron and thermodynamic data by absorption spectroscopy, which provides one of the sensitive and selective spectroscopic methods for the chemical speciation of Fe(II/III). From the comparison analyses, redox potential values measured by the Ag redox electrode are fairly consistent with those calculated by the chemical aqueous speciation of iron in the whole system. In summary, the uncertainties of measured redox potentials are closely related with the total Fe concentration and affected by the formation of mixed potentials due to Fe(III) precipitates in the pH range of 6 ∼ 9 beyond the solubility of Fe(III), whilst being independent of the initially prepared concentration ratios between Fe(II) and Fe(III)

  13. Determination of iron in natural and mineral waters by flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    ROLANDAS KAZLAUSKAS

    2004-05-01

    Full Text Available Simple methods for the determination of Fe in natural and mineral waters by flame atomic absorption spectrometry (AAS are suggested. The results of the investigation of selectivity of the proposed AAS method proved that this procedure is not affected by high concentrations of other metals. The calibration graph for iron was linear at levels near the detection limit up to at least 0.10 mg ml-1. For the determination of microamounts of iron in mineral waters, an extraction AAS technique was developed. Iron was retained as Fe-8-oxyquinoline complex and extracted into chloroform. The optimal conditions for the extraction of the iron complex were determined. The AAS method was applied to the determination of Fe in mineral waters and natural waters from different areas of Lithuania. The accuracy of the developed method was sufficient and evaluated in comparison with a photometric method. The obtained results demonstrated that the procedure could be successfully applied for the analysis of water samples with satisfactory accuracy.

  14. Quasilinear analysis of absorption of ion Bernstein waves by electrons

    International Nuclear Information System (INIS)

    Cardinali, A.; Paoletti, F.; Bernabei, S.; Ono, M.

    1995-01-01

    The effects induced on plasma electrons by an externally launched ion Bernstein wave (IBW), in the presence of a lower hybrid wave (LHW) in the current drive regime, are studied by analytical integration of the IBW ray-tracing equations along with the amplitude transport equation (Poynting theorem). The electric field amplitude parallel and perpendicular to the external magnetic field, the quasilinear diffusion coefficient, and the modified electron distribution function are analytically calculated in the case of IBW. The analytical calculation is compared to the numerical solution obtained by using a 2-D Fokker-Planck code for the distribution function, without any approximation for the collision operator. The synergy between the IBW and LHW can be accounted for, and the absorption of the IBW power when the electron distribution function presents a tail generated by the LHW in the current drive regime can be calculated

  15. Using electron irradiation to probe iron-based superconductors

    Science.gov (United States)

    Cho, Kyuil; Kończykowski, M.; Teknowijoyo, S.; Tanatar, M. A.; Prozorov, R.

    2018-06-01

    High-energy electron irradiation at low temperatures is an efficient and controlled way to create vacancy–interstitial Frenkel pairs in a crystal lattice, thereby inducing nonmagnetic point-like scattering centers. In combination with London penetration depth and resistivity measurements, the electron irradiation was used as a phase-sensitive probe to study the superconducting order parameter in iron-based superconductors (FeSCs), lending strong support to sign-changing s ± pairing. Here, we review the key results of the effect of electron irradiation in FeSCs.

  16. Speciation of water soluble iron in size segregated airborne particulate matter using LED based liquid waveguide with a novel dispersive absorption spectroscopic measurement technique

    International Nuclear Information System (INIS)

    Chan, K.L.; Jiang, S.Y.N.; Ning, Z.

    2016-01-01

    In this study, we present the development and evaluation of a dispersive absorption spectroscopic technique for trace level soluble ferrous detection. The technique makes use of the broadband absorption spectra of the ferrous-ferrozine complex with a novel spectral fitting algorithm to determine soluble ferrous concentrations in samples and achieves much improved measurement precision compared to conventional methods. The developed method was evaluated by both model simulations and experimental investigations. The results demonstrated the robustness of the method against the spectral fluctuation, wavelength drift and electronic noise, while achieving excellent linearity (R 2  > 0.999) and low detection limit (0.06 μg L −1 ) for soluble ferrous detection. The developed method was also used for the speciation of soluble iron in size segregated atmospheric aerosols. The measurement was carried out during Spring and Summer in typical urban environment in Hong Kong. The measured total iron concentrations are in good agreement compared to conventional Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) measurements. Investigation on ambient particulate matter samples shows the size dependent characteristic of iron speciation in the atmosphere with a more active role of fine particles in transforming between ferrous and ferric. The method demonstrated in this study provides a cost and time effective approach for the speciation of iron in ambient aerosols. - Highlights: • Dispersive absorption spectroscopic technique for trace level ferrous detection. • The spectral fitting retrieval improved the measurement precision and stability. • Extremely low detection limit was achieved for aqueous ferrous measurement. • Iron in size segregated particulate matters shows seasonal characteristic. • More active role of iron was found in fine particles compared to coarse particles.

  17. Speciation of water soluble iron in size segregated airborne particulate matter using LED based liquid waveguide with a novel dispersive absorption spectroscopic measurement technique

    Energy Technology Data Exchange (ETDEWEB)

    Chan, K.L. [Meteorological Institute, Ludwig Maximilian University of Munich, Munich (Germany); School of Energy and Environment, City University of Hong Kong (Hong Kong); Jiang, S.Y.N. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Ning, Z., E-mail: zhining@cityu.edu.hk [School of Energy and Environment, City University of Hong Kong (Hong Kong); Guy Carpenter Climate Change Centre, City University of Hong Kong (Hong Kong)

    2016-03-31

    In this study, we present the development and evaluation of a dispersive absorption spectroscopic technique for trace level soluble ferrous detection. The technique makes use of the broadband absorption spectra of the ferrous-ferrozine complex with a novel spectral fitting algorithm to determine soluble ferrous concentrations in samples and achieves much improved measurement precision compared to conventional methods. The developed method was evaluated by both model simulations and experimental investigations. The results demonstrated the robustness of the method against the spectral fluctuation, wavelength drift and electronic noise, while achieving excellent linearity (R{sup 2} > 0.999) and low detection limit (0.06 μg L{sup −1}) for soluble ferrous detection. The developed method was also used for the speciation of soluble iron in size segregated atmospheric aerosols. The measurement was carried out during Spring and Summer in typical urban environment in Hong Kong. The measured total iron concentrations are in good agreement compared to conventional Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) measurements. Investigation on ambient particulate matter samples shows the size dependent characteristic of iron speciation in the atmosphere with a more active role of fine particles in transforming between ferrous and ferric. The method demonstrated in this study provides a cost and time effective approach for the speciation of iron in ambient aerosols. - Highlights: • Dispersive absorption spectroscopic technique for trace level ferrous detection. • The spectral fitting retrieval improved the measurement precision and stability. • Extremely low detection limit was achieved for aqueous ferrous measurement. • Iron in size segregated particulate matters shows seasonal characteristic. • More active role of iron was found in fine particles compared to coarse particles.

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

    Science.gov (United States)

    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.

  19. A 1-h time interval between a meal containing iron and consumption of tea attenuates the inhibitory effects on iron absorption: a controlled trial in a cohort of healthy UK women using a stable iron isotope.

    Science.gov (United States)

    Ahmad Fuzi, Salma F; Koller, Dagmar; Bruggraber, Sylvaine; Pereira, Dora Ia; Dainty, Jack R; Mushtaq, Sohail

    2017-12-01

    Background: Tea has been shown to be a potent inhibitor of nonheme iron absorption, but it remains unclear whether the timing of tea consumption relative to a meal influences iron bioavailability. Objective: The aim of the study was to investigate the effect of a 1-h time interval of tea consumption on nonheme iron absorption in an iron-containing meal in a cohort of iron-replete, nonanemic female subjects with the use of a stable isotope ( 57 Fe). Design: Twelve women (mean ± SD age: 24.8 ± 6.9 y) were administered a standardized porridge meal extrinsically labeled with 4 mg 57 Fe as FeSO 4 on 3 separate occasions, with a 14-d time interval between each test meal (TM). The TM was administered with water (TM-1), with tea administered simultaneously (TM-2), and with tea administered 1 h postmeal (TM-3). Fasted venous blood samples were collected for iron isotopic analysis and measurement of iron status biomarkers. Fractional iron absorption was estimated by the erythrocyte iron incorporation method. Results: Iron absorption was 5.7% ± 8.5% (TM-1), 3.6% ± 4.2% (TM-2), and 5.7% ± 5.4% (TM-3). Mean fractional iron absorption was found to be significantly higher (2.2%) when tea was administered 1 h postmeal (TM-3) than when tea was administered simultaneously with the meal (TM-2) ( P = 0.046). An ∼50% reduction in the inhibitory effect of tea (relative to water) was observed, from 37.2% (TM-2) to 18.1% (TM-3). Conclusions: This study shows that tea consumed simultaneously with an iron-containing porridge meal leads to decreased nonheme iron absorption and that a 1-h time interval between a meal and tea consumption attenuates the inhibitory effect, resulting in increased nonheme iron absorption. These findings are not only important in relation to the management of iron deficiency but should also inform dietary advice, especially that given to those at risk of deficiency. This trial was registered at clinicaltrials.gov as NCT02365103. © 2017 American Society for

  20. Absorption effects in electron-sulfur-dioxide collisions

    Energy Technology Data Exchange (ETDEWEB)

    Machado, L. E.; Sugohara, R. T.; Santos, A. S. dos [Departamento de Fisica, UFSCar, 13565-905 Sao Carlos-SP (Brazil); Lee, M.-T.; Iga, I.; Souza, G. L. C. de [Departamento de Quimica, UFSCar, 13565-905 Sao Carlos-SP (Brazil); Homem, M. G. P.; Michelin, S. E. [Departamento de Fisica, UFSC, 88040-970 Florianopolis-SC (Brazil); Brescansin, L. M. [Instituto de Fisica ' ' Gleb Wataghin' ' , UNICAMP, 13083-970 Campinas-SP (Brazil)

    2011-09-15

    A joint experimental-theoretical study on electron-SO{sub 2} collisions in the low and intermediate energy range is reported. More specifically, experimental elastic differential, integral, and momentum transfer cross sections in absolute scale are measured in the 100-1000 eV energy range using the relative-flow technique. Calculated elastic differential, integral, and momentum transfer cross sections as well as grand-total and total absorption cross sections are also presented in the 1-1000 eV energy range. A complex optical potential is used to represent the electron-molecule interaction dynamics, whereas the Schwinger variational iterative method combined with the distorted-wave approximation is used to solve the scattering equations. Comparison of the present results is made with the theoretical and experimental results available in the literature.

  1. The expression of the soluble HFE corresponding transcript is up-regulated by intracellular iron and inhibits iron absorption in a duodenal cell model

    OpenAIRE

    Silva, Bruno; Ferreira, Joana; Santos, Vera; Baldaia, Cilénia; Serejo, Fátima; Faustino, Paula

    2014-01-01

    Background and aims: Dietary iron absorption regulation is a key-step for the maintenance of body iron homeostasis. Besides the HFE full-length protein, the HFE gene codes for alternative splicing variants responsible for the synthesis of a soluble form of HFE protein (sHFE). Here we aimed to determine whether sHFE transcript levels respond to different iron conditions in duodenal, macrophage and hepatic cell models, as well, in vivo, in the liver. Furthermore, we determined the functional ef...

  2. Studies on iron absorption and retention in malnourished Indian subjects, using Fe-59 and whole-body counting

    International Nuclear Information System (INIS)

    Gopalan, C.; Srikantia, S.G.

    1975-12-01

    The gastrointestinal absorption of iron under various conditions in representatives of the Indian population, and several related matters, have been investigated. Percentage absorption was determined by whole-body counting of 59Fe, or by measuring the concentration of 55Fe in the blood, at about two weeks after administration of the respective tracer. It was confirmed or established that: (1) food or supplemental iron, if available at all, tends to be absorbed from the intestines as if present there in one of two alternative pools: heme and non heme; (2) 30%-50% of iron measured chemically in Indian foods appears to be in an unavailable form, for example as a contaminant in adventitiously present dust; (3) fortification of the diet with iron may be feasible by adding FePO 4 + 2 molar NaHSO 4 to common salt under suitable conditions; (4) monkeys appear to be sufficiently similar to humans in their iron absorption characteristics that they may be the best available non-human model for preliminary experimental investigations of iron absorption; and (5) a promising preparative method for liquid scintillation counting of 55Fe present in blood is to extract it into toluene in the presence of di (2-ethyl-hexyl) phosphate (HDEHP)

  3. Increasing the cooking temperature of meat does not affect nonheme iron absorption from a phytate-rich meal in women

    DEFF Research Database (Denmark)

    Baech, S.B.; Hansen, M.; Bukhave, Klaus

    2003-01-01

    The effect of increasing cooking temperatures of meat on nonheme iron absorption from a composite meal was investigated. Cysteine-containing peptides may have a role in the iron absorption enhancing effect of muscle proteins. Heat treatment can change the content of sulfhydryl groups produced from...... cysteine and thereby affect iron absorption. Twenty-one women (25 +/- 3 y) were served a basic meal without meat and two other meals consisting of the basic meal plus 75 g of pork meat cooked at 70, 95 or 120degreesC. The meals were extrinsically labeled with Fe-55 or Fe-59. Iron absorption was determined...... from measurements of wholebody Fe-59 retention and the activity of Fe-55 and Fe-59 in blood samples. Nonheme iron absorptions were 0.9 (0.5-4.0)% (P = 0.06), 0.7 (0.4-3.9)% (P = 0.1) and 2.0 (1.3-3.1)% (P cooked at 70, 95 or 120degreesC, respectively, was added to the basic...

  4. Partial electron beam hardening of cast iron camshafts

    Energy Technology Data Exchange (ETDEWEB)

    Csizmazia, A.; Reti, T. [Szechenyi Istvan Univ., Gyoer (Hungary); Horvath, M.; Olah, I. [Audi Hungaria Motor Kft., Gyoer (Hungary)

    2005-07-01

    In order to improve the local surface properties (hardness, wear and contact fatigue resistance) of cast iron camshafts, detailed experiments with partial electron beam hardening have been performed. It was found that the required case depth of 0.3-0.5 mm and surface hardness of 600-700 HV can be achieved by using appropriately selected, computer-controlled processing parameters (angular speed, specific energy input, beam deflection). (orig.)

  5. Transport Measurements and Synchrotron-Based X-Ray Absorption Spectroscopy of Iron Silicon Germanide Grown by Molecular Beam Epitaxy

    Science.gov (United States)

    Elmarhoumi, Nader; Cottier, Ryan; Merchan, Greg; Roy, Amitava; Lohn, Chris; Geisler, Heike; Ventrice, Carl, Jr.; Golding, Terry

    2009-03-01

    Some of the iron-based metal silicide and germanide phases have been predicted to be direct band gap semiconductors. Therefore, they show promise for use as optoelectronic materials. We have used synchrotron-based x-ray absorption spectroscopy to study the structure of iron silicon germanide films grown by molecular beam epitaxy. A series of Fe(Si1-xGex)2 thin films (2000 -- 8000å) with a nominal Ge concentration of up to x = 0.04 have been grown. X-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) measurements have been performed on the films. The nearest neighbor co-ordination corresponding to the β-FeSi2 phase of iron silicide provides the best fit with the EXAFS data. Temperature dependent (20 coefficient was calculated. Results suggest semiconducting behavior of the films which is consistent with the EXAFS results.

  6. Natural selection on HFE in Asian populations contributes to enhanced non-heme iron absorption.

    Science.gov (United States)

    Ye, Kaixiong; Cao, Chang; Lin, Xu; O'Brien, Kimberly O; Gu, Zhenglong

    2015-06-10

    HFE, a major regulator of iron (Fe) homeostasis, has been suggested to be under positive selection in both European and Asian populations. While the genetic variant under selection in Europeans (a non-synonymous mutation, C282Y) has been relatively well-studied, the adaptive variant in Asians and its functional consequences are still unknown. Identifying the adaptive HFE variants in Asians will not only elucidate the evolutionary history and the genetic basis of population difference in Fe status, but also assist the future practice of genome-informed dietary recommendation. Using data from the International HapMap Project, we confirmed the signatures of positive selection on HFE in Asian populations and identified a candidate adaptive haplotype that is common in Asians (52.35-54.71%) but rare in Europeans (5.98%) and Africans (4.35%). The T allele at tag SNP rs9366637 (C/T) captured 95.8% of this Asian-common haplotype. A significantly reduced HFE expression was observed in individuals carrying T/T at rs9366637 compared to C/C and C/T, indicating a possible role of gene regulation in adaptation. We recruited 57 women of Asian descent and measured Fe absorption using stable isotopes in those homozygous at rs9366637. We observed a 22% higher absorption in women homozygous for the Asian-common haplotype (T/T) compared to the control genotype (C/C). Additionally, compared with a group of age-matched Caucasian women, Asian women exhibited significantly elevated Fe absorption. Our results indicate parallel adaptation of HFE gene in Europeans and Asians with different genetic variants. Moreover, natural selection on HFE may have contributed to elevated Fe absorption in Asians. This study regarding population differences in Fe homeostasis has significant medical impact as high Fe level has been linked to an increased disease risk of metabolic syndromes.

  7. Atomic absorption determination of iron and copper impurities in rare earth compounds

    International Nuclear Information System (INIS)

    Zelyukova, Yu.V.; Kravchenko, J.B.; Kucher, A.A.

    1978-01-01

    An extraction atomic absorption method for the determination of copper and iron impurities in rare earth compounds has been developed. The extraction separation of determined elements as hydroxy quinolinates with isobuthyl alcohol was used. It increased the sensitivity of these element determination and excluded the effect of the analysed sample. Cu, Te, Zn, Bi, Sn, In, Ga, Tl and the some other elements can be determined at pH 2.0-3.0 but rare earths are remained in an aqueous phase. The condition of the flame combustion does not change during the introduction of isobutyl extract but the sensitivity of the determination of the elements increased 2-3 times. The limit of Fe determination is 0.01 mg/ml and the limit of Cu determination is 0.014 mg/ml

  8. Large specific absorption rates in the magnetic hyperthermia properties of metallic iron nanocubes

    Energy Technology Data Exchange (ETDEWEB)

    Mehdaoui, B.; Meffre, A.; Lacroix, L.-M. [Universite de Toulouse, INSA, UPS, LPCNO (Laboratoire de Physique et Chimie des Nano-Objets), 135 avenue de Rangueil, F-31077 Toulouse (France); CNRS, UMR 5215, LPCNO, F-31077 Toulouse (France); Carrey, J., E-mail: julian.carrey@insa-toulouse.f [Universite de Toulouse, INSA, UPS, LPCNO (Laboratoire de Physique et Chimie des Nano-Objets), 135 avenue de Rangueil, F-31077 Toulouse (France); CNRS, UMR 5215, LPCNO, F-31077 Toulouse (France); Lachaize, S. [Universite de Toulouse, INSA, UPS, LPCNO (Laboratoire de Physique et Chimie des Nano-Objets), 135 avenue de Rangueil, F-31077 Toulouse (France); CNRS, UMR 5215, LPCNO, F-31077 Toulouse (France); Gougeon, M. [Institut CARNOT-CIRIMAT-UMR 5085, Batiment 2R1, 118 route de Narbonne, F-31062 Toulouse (France); Respaud, M. [Universite de Toulouse, INSA, UPS, LPCNO (Laboratoire de Physique et Chimie des Nano-Objets), 135 avenue de Rangueil, F-31077 Toulouse (France); CNRS, UMR 5215, LPCNO, F-31077 Toulouse (France); Chaudret, B. [Laboratoire de Chimie de Coordination-CNRS, 205 rte de Narbonne, 31077 Toulouse cedex 4 (France)

    2010-10-15

    We report on the magnetic hyperthermia properties of chemically synthesized ferromagnetic 11 and 16 nm Fe(0) nanoparticles of cubic shape displaying the saturation magnetization of bulk iron. The specific absorption rate measured on 16 nm nanocubes is 1690{+-}160 W/g at 300 kHz and 66 mT. This corresponds to specific losses-per-cycle of 5.6 mJ/g, largely exceeding the ones reported in other systems. A way to quantify the degree of optimization of any system with respect to hyperthermia applications is proposed. Applied here, this method shows that our nanoparticles are not fully optimized, probably due to the strong influence of magnetic interactions on their magnetic response. Once protected from oxidation and further optimized, such nano-objects could constitute efficient magnetic cores for biomedical applications requiring very large heating power.

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

    Energy Technology Data Exchange (ETDEWEB)

    Khani, Omid, E-mail: omidkhani@mut-es.ac.ir; Shoushtari, Morteza Zargar; Farbod, Mansoor

    2015-11-15

    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 (M{sub S}) 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.

  10. Facile preparation and enhanced microwave absorption properties of flake carbonyl iron/Fe3O4 composite

    International Nuclear Information System (INIS)

    Min, Dandan; Zhou, Wancheng; Luo, Fa; Zhu, Dongmei

    2017-01-01

    Highlights: • Flake carbonyl iron/Fe 3 O 4 composites were prepared by surface oxidation technique. • Lower permittivity and modest permeability was obtained by the FCI/Fe 3 O 4 composites. • Enhanced absorption efficiency and broader absorption band were obtained. - Abstract: Flake carbonyl iron/Fe 3 O 4 (FCI/Fe 3 O 4 ) composites with enhanced microwave absorption properties were prepared by a direct and flexible surface oxidation technique. The phase structures, morphology, magnetic properties, frequency-dependent electromagnetic and microwave absorption properties of the composites were investigated. The measurement results showed that lower permittivity as well as modest permeability was obtained by the FCI/Fe 3 O 4 composites. The calculated microwave absorption properties indicated that enhanced absorption efficiency and broader absorption band were obtained by the FCI/Fe 3 O 4 composite comparing with the FCI composite. The absorption frequency range with reflection loss (RL) below −5 dB of FCI/Fe 3 O 4 composites at reaction time of 90 min at thickness of 1.5 mm is 13.3 GHz from 4.7 to 18 GHz, while the bandwidth of the FCI composite is only 5.9 GHz from 2.6 to 8.5 GHz at the same thickness. Thus, such absorbers could act as effective and wide broadband microwave absorbers in the GHz range.

  11. Electronic excitation induced modifications in elongated iron nanoparticle encapsulated multiwalled carbon nanotubes under ion irradiation

    Science.gov (United States)

    Saikiran, V.; Bazylewski, P.; Sameera, I.; Bhatia, Ravi; Pathak, A. P.; Prasad, V.; Chang, G. S.

    2018-05-01

    Multi-wall carbon nanotubes (MWCNT) filled with Fe nanorods were shown to have contracted and deformed under heavy ion irradiation. In this study, 120 MeV Ag and 80 MeV Ni ion irradiation was performed to study the deformation and defects induced in iron filled MWCNT under heavy ion irradiation. The structural modifications induced due to electronic excitation by ion irradiation were investigated employing high-resolution transmission electron microscopy, micro-Raman scattering experiments, and synchrotron-based X-ray absorption and emission spectroscopy. We understand that the ion irradiation causes modifications in the Fe nanorods which result in compressions and expansions of the nanotubes, and in turn leads to the buckling of MWCNT. The G band of the Raman spectra shifts slightly towards higher wavenumber and the shoulder G‧ band enhances with the increase of ion irradiation fluence, where the buckling wavelength depends on the radius 'r' of the nanotubes as exp[(r)0.5]. The intensity ratio of the D to G Raman modes initially decreases at the lowest fluence, and then it increases with the increase in ion fluence. The electron diffraction pattern and the high resolution images clearly show the presence of ion induced defects on the walls of the tube and encapsulated iron nanorods.

  12. Diurnal variations in iron concentrations and expression of genes involved in iron absorption and metabolism in pigs.

    Science.gov (United States)

    Zhang, Yiming; Wan, Dan; Zhou, Xihong; Long, Ciming; Wu, Xin; Li, Lan; He, Liuqin; Huang, Pan; Chen, Shuai; Tan, Bie; Yin, Yulong

    2017-09-02

    Diurnal variations in serum iron levels have been well documented in clinical studies, and serum iron is an important diagnostic index for iron-deficiency anemia. However, the underlying mechanism of dynamic iron regulation in response to the circadian rhythm is still unclear. In this study, we investigated daily variations in iron status in the plasma and liver of pigs. The transcripts encoding key factors involved in iron uptake and homeostasis were evaluated. The results showed that iron levels in the plasma and liver exhibited diurnal rhythms. Diurnal variations were also observed in transcript levels of divalent metal transporter 1 (DMT1), membrane-associated ferric reductase 1 (DCYTB), and transferrin receptor (TfR) in the duodenum and jejunum, as well as hepcidin (HAMP) and TfR in the liver. Moreover, the results showed a network in which diurnal variations in systemic iron levels were tightly regulated by hepcidin and Tf/TfR via DCYTB and DMT1. These findings provide new insights into circadian iron homeostasis regulation. The diurnal variations in serum iron levels may also have pathophysiological implications for clinical diagnostics related to iron deficiency anemia in pigs. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Bioavailability and the mechanisms of intestinal absorption of iron from ferrous ascorbate and ferric polymaltose in experimental animals

    International Nuclear Information System (INIS)

    Johnson, G.; Jacobs, P.

    1990-01-01

    The comparative bioavailability from matching quantities of iron in the form of ferrous ascorbate or ferric polymaltose was defined in rats. Studies were carried out in the intact animals under basal conditions and also when requirements for this metal were either increased or decreased by manipulating stores or erythropoietic activity. No significant difference was found in the total quantity of iron absorbed from either salt or complex under any of these circumstances, suggesting that the mucosal mechanism regulating the overall process was common to both. However, the rate of transfer from the lumen into portal blood was distinctive, reaching a maximum with salt at 30 min compared to 24 h for the complex. To explore the possibility that iron from the two sources was initially handled by different subcellular pathways, the radiolabeled compounds were instilled into loops of bowel that had been isolated between ligatures in vivo. Enterocytes were harvested and fractionated, and incorporation into ferritin and transferrin was determined using RIA. From salt, iron appeared rapidly in duodenal but not ileal ferritin, whereas mucosal transferrin increased under conditions of stimulated absorption, suggesting that this protein may act as a shuttle for the metal. In contrast, iron from polymaltose showed a cumulative incorporation into duodenal ferritin over time that correlated with iron absorption, defined by the appearance of radiolabel in the serum and in the carcass; a similar pattern was demonstrable in ileal mucosal cells. Conversely, binding of iron to transferrin was minimal. No iron polymaltose was found within the mucosal cells. It is suggested that the low rate of iron transfer from this ferric complex may reflect its extracellular breakdown in the lumen of the gastrointestinal tract

  14. Electron exchange between neutral and ionized impurity iron centers in vitreous arsenic selenide

    Energy Technology Data Exchange (ETDEWEB)

    Marchenko, A. V. [Herzen State Pedagogical University of Russia (Russian Federation); Terukov, E. I. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Egorova, A. Yu. [St.-Petersburg Mining University (Russian Federation); Kiselev, V. S.; Seregin, P. P., E-mail: ppseregin@mail.ru [Herzen State Pedagogical University of Russia (Russian Federation)

    2017-04-15

    Impurity iron atoms in vitreous arsenic-selenide As{sub 2}Se{sub 3} films modified by iron form one-electron donor centers with an ionization energy of 0.24 (3) eV (the energy is counted from the conduction-band bottom). The Fermi level is shifted with an increase in the iron concentration from the mid-gap to the donorlevel position of iron due to the filling of one-electron states of the acceptor type lying below the Fermi level. At an iron concentration of ≥3 at %, the electron-exchange process is observed between neutral and ionized iron centers resulting in a change both in the electron density and in the tensor of the electric-field gradient at iron-atom nuclei with increasing temperature above 350 K.

  15. A system to measure suprathermal electron distribution functions in toroidal plasmas by electron cyclotron wave absorption

    International Nuclear Information System (INIS)

    Boyd, D.A.; Skiff, F.; Gulick, S.

    1997-01-01

    A two-chord, four-beam suprathermal electron diagnostic has been installed on TdeV (B>1.5 T, R=0.86 m, a=0.25 m). Resonant absorption of extraordinary mode electron cyclotron waves is measured to deduce the chordal averaged suprathermal electron distribution function amplitude at the resonant momentum. Simultaneously counterpropagating beams permit good refractive loss cancellation. A nonlinear frequency sweep leads to a concentration of appropriately propagating power in a narrow range of time of flight, thus increasing the signal-to-noise ratio and facilitating the rejection of spurious reflections. Numerous measurements of electron distribution functions have been obtained during lower-hybrid current-drive experiments. copyright 1997 American Institute of Physics

  16. Electronic properties and optical absorption of a phosphorene quantum dot

    Science.gov (United States)

    Liang, F. X.; Ren, Y. H.; Zhang, X. D.; Jiang, Z. T.

    2018-03-01

    Using the tight-binding Hamiltonian approach, we theoretically study the electronic and optical properties of a triangular phosphorene quantum dot (PQD) including one normal zigzag edge and two skewed armchair edges (ZAA-PQD). It is shown that the energy spectrum can be classified into the filled band (FB), the zero-energy band (ZB), and the unfilled band (UB). Numerical calculations of the FB, ZB, and UB probability distributions show that the FB and the UB correspond to the bulk states, while the ZB corresponds to the edge states, which appear on all of the three edges of the ZAA-PQD sharply different from the other PQDs. We also find that the strains and the electric fields can affect the energy levels inhomogeneously. Then the optical properties of the ZAA-PQD are investigated. There appear some strong low-energy optical absorption peaks indicating its sensitive low-energy optical response that is absent in other PQDs. Moreover, the strains and the electric fields can make inhomogeneous influences on the optical spectrum of the ZAA-PQD. This work may provide a useful reference for designing the electrical, mechanical, and optical PQD devices.

  17. High Pressure X-ray Absorption Studies on Correlated-Electron Systems

    International Nuclear Information System (INIS)

    Cornelius, Andrew L.

    2016-01-01

    This project used high pressure to alter the electron-electron and electron-lattice interactions in rare earth and actinide compounds. Knowledge of these properties is the starting points for a first-principles understanding of electronic and electronically related macroscopic properties. The research focused on a systematic study of x-ray absorption measurements on rare earth and actinide compounds.

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

    Science.gov (United States)

    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…

  19. Electron density profiles in the background of LF absorption during Forbush-decrease and PSE

    International Nuclear Information System (INIS)

    Satori, G.

    1989-01-01

    Based on the simulation of different Forbush decrease and particle precipitation effects in the D region, electron density profiles in the mid-latitudes the ionospheric absorption of low frequency (LF) radio waves was determined. The absorption variations at different frequenceis are strongly affected by the shape of the electron density profile. A structure appears which sometimes resembles the letter S (in a sloping form). Both the height (around 70 to 72 km) and the depth of the local minimum in the electron density contribute to the computed absorption changes of various degree at different frequencies. In this way several observed special absorption events can be interpreted

  20. Electron cyclotron absorption in Tokamak plasmas in the presence of radial transport of particles

    International Nuclear Information System (INIS)

    Rosa, Paulo R. da S.; Ziebell, Luiz F.

    1998-01-01

    We use quasilinear theory to study effects of particle radial transport on the electron cyclotron absorption coefficient by a current carrying plasma, in a tokamak modelated as a plasma slab. Our numerical results indicate significant modification in the profile of the electron cyclotron absorption coefficient when transport is taken into account relative to the situation without transport. (author)

  1. Normal iron absorption determined by means of whole body counting and red cell incorporation of 59Fe

    International Nuclear Information System (INIS)

    Larsen, L.; Milman, N.

    1977-01-01

    Gastrointestinal iron absorption was measured in 27 normal subjects (19 females and 8 males) by means of whole body counting. Whole body retention 14 days after oral administration of 10μCi 59 Fe together with a carrier dose of 9.9 mg Fe 2+ (as sulphate), was used as an expression of absorption. The percentage incorporation in the total erythrocyte mass of administered 59 Fe (erythrocyte incorporation) and of absorbed 59 Fe (red cell utilization) was also estimated. Geometric mean iron absorption was 8.3+-2.1 (SD% in females, 9.1+-2.2 % in males and 8.5+-2.1 % in the entire series. The difference between males and females was not significant. Erythrocyte incorporation was 7.7+-2.2 (SD) % (geometric mean) in the entire series and the correlation between iron absorption and erythrocyte incorporation was highly significant (r = 0.96,P < 0.001). Red cell utilization averaged 92.9 +- 4.0 (SEM)% (arithmetic mean) in the entire series. (author)

  2. Different behaviour of 63Ni and 59Fe during absorption in iron-deficient and iron-adequate jejunal rat segments ex vivo

    International Nuclear Information System (INIS)

    Mueller-Fassbender, M.; Elsenhans, B.; McKie, A.T.; Schuemann, K.

    2003-01-01

    Nickel exhibits low oral toxicity. It shares the absorptive pathways for iron, though there are substantial quantitative differences in handling of both metals. To analyse these differences more closely, jejunal segments from iron-deficient and iron-adequate rats were luminally perfused ex vivo with 59 Fe and 63 Ni at six different concentrations (1-500 μmo1/l) under steady state conditions. 59 Fe over-all absorption increased 2.0-4.6-fold in iron-deficiency at luminal concentrations between 1 and 100 μmol/l, while 63 Ni absorption increased to a much lower extent (2.6-fold at 1 μmol/l and 1.5-fold at higher luminal concentrations). Moreover, there was a 5-7-fold higher concentration for 63 Ni in the jejunal tissue than in the absorbate at luminal concentrations above 50 μmol/l which was not observed at 1 μmol 63 Ni/l and not for 59 Fe. 63 Ni tissue load showed a linear and a saturable fraction. In iron-deficiency the saturable 63 Ni fraction increased 4-fold as compared to only 1.5-fold increments for 59 Fe. Moreover, a substantially higher share of 63 Ni was retained in the jejunal tissue at high as compare to low luminal concentrations after perfusion had been continued without luminal radioactivity. This was not found for 59 Fe and suggests a concentration-dependent block of 63 Ni export across the enterocytes' basolateral membrane. To explain these results one may speculate that 63 Ni may bind more tightly to tissue ligands than 59 Fe due to the higher thermodynamic and kinetic stability of nickel complexes. In particular, nickel may bind to a basolateral population of metal carriers and block its own basolateral transfer in a concentration-dependent manner. Tight 63 Ni binding to non-specific jejunal ligands is responsible for the unaltered high linear fraction of jejunal 63 Ni load in iron-deficient and iron-adequate segments. Binding of 63 Ni to food and tissue ligands in the small intestine may, thus, be a likely explanation for the low oral nickel

  3. Microwave absorption properties of the core/shell-type iron and nickel nanoparticles

    International Nuclear Information System (INIS)

    Lu, B.; Dong, X.L.; Huang, H.; Zhang, X.F.; Zhu, X.G.; Lei, J.P.; Sun, J.P.

    2008-01-01

    Iron (Fe) and nickel (Ni) nanoparticles were prepared by the DC arc-discharge method in a mixture of hydrogen and argon gases, using bulk metals as the raw materials. The microstructure of core/shell (metal/metal oxide) in nanoparticle formed after in situ passivation process. The complex electromagnetic parameters (permittivity ε r =ε r ' +iε r '' and permeability μ r =μ r ' +iμ r '' ) of the paraffin-mixed nanocomposite samples (paraffin:nanoparticles=1:1 in mass ratio) were measured in the frequency range of 2-18 GHz. The polarization mechanisms of the space charge and dipole coexist in both the Fe and Ni nanoparticles. The orientational polarization is a particular polarization for Fe nanoparticles and brings a relatively higher dielectric loss. Natural resonance is the main reason for magnetic loss and the corresponding frequencies are 11.6 and 5.2 GHz for the Fe and Ni nanoparticles, respectively. The paraffin composite with Fe nanoparticles provided excellent microwave absorption properties (reflection loss <-20 dB) in the range 6.8-16.6 GHz over the absorber thickness of 1.1-2.3 mm

  4. Speciation of iron (II) and (III) by using solvent extraction and flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Yaman, Mehmet; Kaya, Gokce

    2005-01-01

    A method for speciation, preconcentration and separation of Fe 2+ and Fe 3+ in different matrices was developed using solvent extraction and flame atomic absorption spectrometry. PAN as complexing reagent for Fe 2+ and chloroform as organic solvent were used. The complex of Fe 2+ -PAN was extracted into chloroform phase in the pH range of 0.75-4.0 and Fe 3+ remains in water phase in the pH range 0.75-1.25. The optimum conditions for maximum recovery of Fe 2+ and minimum recovery of Fe 3+ were determined as pH = 1, the stirring time of 20 min, the PAN amount of 0.5 mg and chloroform volume of 8 mL. The developed method was applied to the determination of Fe 2+ and Fe 3+ in tea infusion, fruit juice, cola and pekmez. It is seen that there is high bioavailable iron (Fe 2+ ) in pekmez. The developed method is sensitive, simple and need the shorter time in comparison with other similar studies

  5. Observation of electromagnetically induced transparency and absorption in Yttrium Iron Garnet loaded split ring resonator

    Science.gov (United States)

    Tay, Z. J.; Soh, W. T.; Ong, C. K.

    2018-04-01

    In this paper, we propose a new method of controlling microwave transmission from Electromagnetically Induced Absorption (EIA) to Electromagnetically Induced Transparency (EIT). EIA describes the state where the system strongly absorbs microwaves, whereas EIT describes the state in which the system is transparent to microwaves. Control is achieved via coupling of the 3 GHz photon mode of a metamaterial Split Ring Resonator (SRR) to the spin wave magnon modes of a Yttrium Iron Garnet (YIG) bulk. The system is described by a 2-body interaction matrix with an additional fitting parameter τ which takes into account the fact that the microstrip feed line could excite the SRR as well as the YIG. The parameter τ reveals the effect of geometry and shielding on the coupling behaviour and gives rise to unique physics. In low τ (τ ⩽ 2) configurations, only EIT is reported. However, in high τ (τ ≈ 10) configurations, EIA is reported. Furthermore, we report that the system can be easily changed from a low τ to high τ configuration by shielding the SRR from the microstrip with a thin metal piece. Varying the τ parameter through shielding is thus proposed as a new method of controlling the microwave transmission at the coupling region.

  6. Microwave absorption properties of the core/shell-type iron and nickel nanoparticles

    Science.gov (United States)

    Lu, B.; Dong, X. L.; Huang, H.; Zhang, X. F.; Zhu, X. G.; Lei, J. P.; Sun, J. P.

    Iron (Fe) and nickel (Ni) nanoparticles were prepared by the DC arc-discharge method in a mixture of hydrogen and argon gases, using bulk metals as the raw materials. The microstructure of core/shell (metal/metal oxide) in nanoparticle formed after in situ passivation process. The complex electromagnetic parameters (permittivity ɛ=ɛr'+iɛr″ and permeability μ=μr'+iμr″) of the paraffin-mixed nanocomposite samples (paraffin:nanoparticles=1:1 in mass ratio) were measured in the frequency range of 2-18 GHz. The polarization mechanisms of the space charge and dipole coexist in both the Fe and Ni nanoparticles. The orientational polarization is a particular polarization for Fe nanoparticles and brings a relatively higher dielectric loss. Natural resonance is the main reason for magnetic loss and the corresponding frequencies are 11.6 and 5.2 GHz for the Fe and Ni nanoparticles, respectively. The paraffin composite with Fe nanoparticles provided excellent microwave absorption properties (reflection loss <-20 dB) in the range 6.8-16.6 GHz over the absorber thickness of 1.1-2.3 mm.

  7. Facile preparation and enhanced microwave absorption properties of flake carbonyl iron/Fe{sub 3}O{sub 4} composite

    Energy Technology Data Exchange (ETDEWEB)

    Min, Dandan, E-mail: mdd4776@126.com; Zhou, Wancheng; Luo, Fa; Zhu, Dongmei

    2017-08-01

    Highlights: • Flake carbonyl iron/Fe{sub 3}O{sub 4} composites were prepared by surface oxidation technique. • Lower permittivity and modest permeability was obtained by the FCI/Fe{sub 3}O{sub 4} composites. • Enhanced absorption efficiency and broader absorption band were obtained. - Abstract: Flake carbonyl iron/Fe{sub 3}O{sub 4} (FCI/Fe{sub 3}O{sub 4}) composites with enhanced microwave absorption properties were prepared by a direct and flexible surface oxidation technique. The phase structures, morphology, magnetic properties, frequency-dependent electromagnetic and microwave absorption properties of the composites were investigated. The measurement results showed that lower permittivity as well as modest permeability was obtained by the FCI/Fe{sub 3}O{sub 4} composites. The calculated microwave absorption properties indicated that enhanced absorption efficiency and broader absorption band were obtained by the FCI/Fe{sub 3}O{sub 4} composite comparing with the FCI composite. The absorption frequency range with reflection loss (RL) below −5 dB of FCI/Fe{sub 3}O{sub 4} composites at reaction time of 90 min at thickness of 1.5 mm is 13.3 GHz from 4.7 to 18 GHz, while the bandwidth of the FCI composite is only 5.9 GHz from 2.6 to 8.5 GHz at the same thickness. Thus, such absorbers could act as effective and wide broadband microwave absorbers in the GHz range.

  8. Changing of the electron structure of dispersed iron oxide during interaction with amines and borofluoride

    International Nuclear Information System (INIS)

    Hobert, H.; Arnold, D.

    1975-01-01

    The mechanism of chemisorption on the surface of iron oxide was studied by Moessbauer spectroscopy performed on samples of iron oxide finely dispersed in SiO 2 . It was found from Moessbauer spectra that the interaction of the oxide with amines resulted in a reversible electron transition from the amine to the adsorbent. The interaction with BF 3 brought about an irreversible electron transition from iron to boron. (A.K.)

  9. Hot Electron Photoemission from Plasmonic Nanostructures: The Role of Surface Photoemission and Transition Absorption

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Ikhsanov, Renat Sh

    2015-01-01

    We study mechanisms of photoemission of hot electrons from plasmonic nanoparticles. We analyze the contribution of "transition absorption", i.e., loss of energy of electrons passing through the boundary between different materials, to the surface mechanism of photoemission. We calculate photoemis......We study mechanisms of photoemission of hot electrons from plasmonic nanoparticles. We analyze the contribution of "transition absorption", i.e., loss of energy of electrons passing through the boundary between different materials, to the surface mechanism of photoemission. We calculate...... photoemission rate and transition absorption for nanoparticles surrounded by various media with a broad range of permittivities and show that photoemission rate and transition absorption follow the same dependence on the permittivity. Thus, we conclude that transition absorption is responsible...

  10. Effect of Gamma Radiation on Absorption of Light in Potassium-Aluminoborate Glasses with Additions of Iron Oxide

    Science.gov (United States)

    Ibragimova, E. M.; Salakhitdinov, A. N.; Salakhitdinova, M. K.; Yusupov, A. A.

    2018-05-01

    The effect of radiation on the absorption of light by potassium-alumina-borate glasses with various concentrations of iron additions and various thicknesses was investigated. It was shown that in contrast to samples of small thickness (1 mm) a bleaching effect was observed in the samples with a thickness of 8 mm. A possible mechanism involving the formation of nanostructured units is proposed for the observed effect.

  11. Determination of calcium, copper, chromium, iron, magnesium, manganese, potassium, sodium and zinc in ethanol by atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Fernandes, E.A.N.

    1981-01-01

    The direct determinacao of calcium, copper, chomium, iron, magnesium, manganese, potassium, sodium and zinc in ethanol by atomic absorption spectrometry with, air-acetylene flame is proposed. Effects of fuel/oxidant ratio, burner height and water content in the samples were investigated in detail. The method allows the determition of the elements with good precision (r.s.d. -1 for the elements tested. (author) [pt

  12. Alternating magnetic field energy absorption in the dispersion of iron oxide nanoparticles in a viscous medium

    Energy Technology Data Exchange (ETDEWEB)

    Smolkova, Ilona S. [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, T.G. Masaryk Sq. 275, 762 72 Zlin (Czech Republic); Kazantseva, Natalia E., E-mail: nekazan@yahoo.com [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Babayan, Vladimir; Smolka, Petr; Parmar, Harshida; Vilcakova, Jarmila [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Schneeweiss, Oldrich; Pizurova, Nadezda [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno (Czech Republic)

    2015-01-15

    Magnetic iron oxide nanoparticles were obtained by a coprecipitation method in a controlled growth process leading to the formation of uniform highly crystalline nanoparticles with average size of 13 nm, which corresponds to the superparamagnetic state. Nanoparticles obtained are a mixture of single-phase nanoparticles of magnetite and maghemite as well as nanoparticles of non-stoichiometric magnetite. The subsequent annealing of nanoparticles at 300 °C in air during 6 h leads to the full transformation to maghemite. It results in reduced value of the saturation magnetization (from 56 emu g{sup −1} to 48 emu g{sup −1}) but does not affect the heating ability of nanoparticles. A 2–7 wt% dispersion of as-prepared and annealed nanoparticles in glycerol provides high heating rate in alternating magnetic fields allowed for application in magnetic hyperthermia; however the value of specific loss power does not exceed 30 W g{sup −1}. This feature of heat output is explained by the combined effect of magnetic interparticle interactions and the properties of the carrier medium. Nanoparticles coalesce during the synthesis and form aggregates showing ferromagnetic-like behavior with magnetization hysteresis, distinct sextets on Mössbauer spectrum, blocking temperature well about room temperature, which accounts for the higher energy barrier for magnetization reversal. At the same time, low specific heat capacity of glycerol intensifies heat transfer in the magnetic dispersion. However, high viscosity of glycerol limits the specific loss power value, since predominantly the Neel relaxation accounts for the absorption of AC magnetic field energy. - Highlights: • Mixed phase iron oxide magnetic nanoparticles were obtained by coprecipitation. • A part of nanoparticles was annealed at 300 °C to achieve the single-phase γ-Fe{sub 2}O{sub 3}. • Nanoparticles revealed ferromagnetic-like behavior due to interparticle interactions. • Nanoparticles glycerol

  13. Electron impact ionisation cross sections of iron oxides

    Science.gov (United States)

    Huber, Stefan E.; Mauracher, Andreas; Sukuba, Ivan; Urban, Jan; Maihom, Thana; Probst, Michael

    2017-12-01

    We report electron impact ionisation cross sections (EICSs) of iron oxide molecules, FexOx and FexOx+1 with x = 1, 2, 3, from the ionisation threshold to 10 keV, obtained with the Deutsch-Märk (DM) and binary-encounter-Bethe (BEB) methods. The maxima of the EICSs range from 3.10 to 9 . 96 × 10-16 cm2 located at 59-72 eV and 5.06 to 14.32 × 10-16 cm2 located at 85-108 eV for the DM and BEB approaches, respectively. The orbital and kinetic energies required for the BEB method are obtained by employing effective core potentials for the inner core electrons in the quantum chemical calculations. The BEB cross sections are 1.4-1.7 times larger than the DM cross sections which can be related to the decreasing population of the Fe 4s orbitals upon addition of oxygen atoms, together with the different methodological foundations of the two methods. Both the DM and BEB cross sections can be fitted excellently to a simple analytical expression used in modelling and simulation codes employed in the framework of nuclear fusion research. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80308-2.

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

    Science.gov (United States)

    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

  15. Determination of iron absorption and excretion by whole-body counting; Determination de l'absorption et de l'excretion du fer par la methode de comptage global humain

    Energy Technology Data Exchange (ETDEWEB)

    Hollard, D; Benabid, Y; Berard, M; Bonnin, J; Darnault, J; Millet, M [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Using a whole-body counter, the authors have studied {sup 59}Fe absorption and loss in 8 normal subjects and in 30 iron deficient patients. Results showed that whole-body counting provided an excellent and simple method for iron retention measurements, obviating many inaccuracies of previous technic. Normal absorption of radio iron with this procedure has ranged from 9 per cent to 20 per cent of the administered tracer in normal subjects, with a mean of 15 per cent. A significant increase in {sup 59}Fe absorption was noted in 21 iron-deficient patients in whom the retention ranged from 40 to 100 per cent. However, 3 iron-deficient patients were found to have low absorption, and their severe iron deficiency could be correlated with this defect in absorption. This method permits also the determination of the rate of iron excretion during the following months and therefore the study of the mechanism of some pathological loss. (authors) [French] L'utilisation de la methode de comptage humain global a permis aux auteurs d'etudier l'absorption et l'excretion du fer-59 chez 8 sujets temoins et 30 sujets hyposideremiques. Les resultats montrent que cette technique simple et directe offre de nombreux avantages sur les methodes employees jusqu'a maintenant pour cette determination. La valeur normale de l'absorption du fer chez les temoins est d'environ 15 pour cent de la dose ingeree. Ce chiffre est tres fortement augmente chez 21 sujets hyposideremiques, pouvant atteindre 100 pour cent de la dose ingeree. Par contre, pour 3 malades, cette absorption est si faible qu'elle suggere une carence par defaut d'absorption. Cette methode permet egalement de suivre l'excretion du fer au cours des mois qui suivent l'examen et de determiner le mecanisme de fuites anormales. (auteurs)

  16. Effect of microplastic deformation on the electron ultrasonic absorption in high-purity molybdenum monocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Pal' -Val' , P.P.; Kaufmann, Kh.J.

    1983-03-01

    The low temperature (100-6 K) linear absorption of ultrasound (88 kHz) by high purity molybdenum single crystals have been studied. Both unstrained samples and samples sub ected to microplastic deformation (epsilon<=0.45%) were used. Unstrained samples displayed at T<30 K a rapid increase in the absorption with lowering temperature which is interpreted as an indication of electron viscosity due to electron-phonon collisions. After deformation this part of absorption disappeared. This seems to suggest that microplastic deformation brings about in the crystal a sufficiently large number of defects that can compete with phonons in restricting the electron mean free path. A low temperature dynamic annealing has been revealed in strained samples, that is almost complete recovery of the absorption nature under irradiation with high amplitude sound, epsilon/sub 0/ approximately 10/sup -4/, during 10 min, at 6 K. A new relaxation peak of absorption at 10 K has been found in strained samples.

  17. Iron

    Science.gov (United States)

    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 ...

  18. Calculated electronic structure of chromium surfaces and chromium monolayers on iron

    International Nuclear Information System (INIS)

    Victora, R.H.; Falicov, L.M.

    1985-01-01

    A self-consistent calculation of the magnetic and electronic properties of the chromium (100) and (110) surfaces and of a chromium monolayer on the (100) and (110) iron surfaces is presented. It is found that (i) the (100) chromium surface is ferromagnetic with a greatly enhanced spin polarization (3.00 electrons); (ii) a substantial enhancement of the spin imbalance exists several (>5) layers into the bulk; (iii) the (110) chromium surface is antiferromagnetic with a large (2.31) spin imbalance; (iv) the (100) chromium monolayer on ferromagnetic iron is ferromagnetic, with a huge spin imbalance (3.63), and aligned antiferromagnetically with respect to the bulk iron; (v) the (110) chromium monolayer on ferromagnetic iron is also ferromagnetic, with a spin imbalance of 2.25 and antiferromagnetically aligned to the iron. The spin imbalance of chromium on iron (100) is possibly the largest of any transition-metal system

  19. Nonheme-iron absorption from a phytate-rich meal is increased by the addition of small amounts of pork meat

    DEFF Research Database (Denmark)

    Boech, S.B.; Hansen, M.; Bukhave, Klaus

    2003-01-01

    of small amounts of meat on nonheme-iron absorption from a meal presumed to have low iron bioavailability. Design: Forty-five healthy women with a mean (+/-SD) age of 24 +/- 3 y were randomly assigned to I of 3 groups, each of which was served (A) a basic meal (rice, tomato sauce, pea puree, and a wheat...

  20. Optical absorption and electron spin resonance studies of Cu in ...

    Indian Academy of Sciences (India)

    Unknown

    Na2O–50B2O3–10As2O3 glasses. In this paper, we report the ESR and optical absorption spectra of Cu2+ ions in xLi2O–(40 – x)Na2O–50B2O3–. 10As2O3 glasses. The values of x were adjusted so that the compositional parameter defined as ...

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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 (Zn 2+ 0.17 Fe 3+ 0.83 )[Fe 3+ 1.17 Fe 2+ 0.06 Ni 2+ 0.77 ]O 4 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. - Highlights: • Iron ore tailings (IOTs) have been used as one of the main raw materials. • Glass–ceramic tile contains spinel ferrite has been prepared. • The cation distribution of the spinel ferrite has been calculated. • The intrinsic complex permeability and permittivity have been evaluated

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

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Rui; Liao, SongYi [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Dai, ChangLu [Guangdong Bode Fine Building Material Co. Ltd., Foshan 528000 (China); Liu, YuChen; Chen, XiaoYu [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Zheng, Feng, E-mail: fzheng@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Phase diagrams and materials design center, Central South University, Changsha 410083 (China)

    2015-03-15

    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 (Zn{sup 2+}{sub 0.17}Fe{sup 3+}{sub 0.83})[Fe{sup 3+}{sub 1.17}Fe{sup 2+}{sub 0.06}Ni{sup 2+}{sub 0.77}]O{sub 4} 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. - Highlights: • Iron ore tailings (IOTs) have been used as one of the main raw materials. • Glass–ceramic tile contains spinel ferrite has been prepared. • The cation distribution of the spinel ferrite has been calculated. • The intrinsic complex permeability and permittivity have been evaluated.

  3. Effect of three Electron Shuttles on Bioreduction of Ferric Iron in two Acidic and Calcareous soils

    Directory of Open Access Journals (Sweden)

    Setareh Sharifi

    2017-01-01

    Full Text Available Introduction: Iron cycle is one of the most important biogeochemical processes which affect the availability of iron in soils. Ferric iron oxides are the most abundant forms of iron in soils and sediments. Ferric iron is highly insoluble at circumneutral pH. Present investigations have shown that the structural ferric iron bound in clay minerals is reduced by some microorganisms. Anaerobic bacteria reduce ferric iron which bound to soil clay minerals under anaerobic conditions. They have the ability to use ferric iron as a terminal electron acceptor. Many studies presented that dissimilatory iron reducing bacteria (DIRB mediate the transfer of electrons from small organic molecules like acetate and glucose to various humic materials (electron shuttles which then pass electrons abiotically to ferric iron oxyhydroxide and phyllosilicate minerals. Electron shuttles like AQDS, a tricyclic quinone, increase the rate of iron reduction by iron reducing bacteria on sites of iron oxides and oxyhydroxides. By increasing the rate of bioreduction of ferric iron, the solubility and availability of iron enhanced meaningfully. Royer et al. (2002 showed that bioreduction of hematite (common iron mineral in soils increased more than three times in the presence of AQDS and Shewanella putrefaciens comparedto control treatments. Previous works have mostly used synthetic minerals as electron acceptor in bioreduction process. Furthermore, the effect of quinones as electron acceptor for microorganisms were studied with poorly crystalline ferric iron oxides . The main objective of this study was to study the effect of AQS, humic acid and fulvic acid (as electron shuttle and Shewanella sp. and Pseudomonas aeruginosa, on bioreduction of native ferric iron in two acidic and calcareous soils. Materials and Methods: An experiment was conducted in a completely randomized design with factorial arrangement and three replications in vitro condition. The soil samples collected

  4. Determination of silver in fresh water by atomic absorption spectrometry following flotation preconcentration by iron(III) collectors

    Energy Technology Data Exchange (ETDEWEB)

    Cundeva, K.; Stafilov, T. [Institute of Chemistry, Faculty of Science, St. Cyril and Methodius University, Skopje (Yugoslavia)

    1997-08-01

    Colloid precipitate flotation of silver from fresh water is applied for preconcentration and separation. Optimal conditions using hydrated iron(III) oxide and iron(III) tetramethylenedithiocarbamate as collectors were investigated. Various factors affecting the silver recovery, including collector mass, nature of the supporting electrolyte, pH of the working medium, electrokinetic potential of the collector particle surfaces, type of surfactant, induction time etc., were checked. Within the optimal pH range (5.5-6.5) silver was separated quantitatively (94.9- 100.0%) with 30 mg Fe(III) as collector. The content of silver was determined by electrothermal atomic absorption spectrometry and compared to that from inductively coupled plasma-atomic emission spectrometry. The detection limit of silver by the method described is 0.01 {mu}g/L. (orig.) With 2 figs., 3 tabs.

  5. Absorption mechanisms for cationic and anionic mineral species on ferric iron polymer hydroxides and oxidation products of ferrous iron in aqueous media

    International Nuclear Information System (INIS)

    Gandon, Remi

    1982-01-01

    Adsorbents obtained by hydrolysing the Fe 3+ , 6H 2 O ion are made of polymers with aquo (H 2 O), hydroxo (-OH...) and oxo (...O...) ligands. Radioactive tracers reveal the importance of chemical mechanisms in adsorption phenomena on ferric oxide in aqueous media. Zn 2+ , Co 2+ and Mn 2+ cations are exchanged with hydrogen from hydroxo groups. CrO 4 2- , SeO 3 2- and Sb(OH) 6 - anions form covalent associations in place of iron ligands. The adsorption of hydrolyzed ions results in strong oxygen bridge bonds. In fresh water, Co and Mn participate alone in physical electrostatic adsorption. Iron II oxidation products generate chemical adsorptions. Zn 2+ and Sb(OH) 6 - associate with ferric hydroxides from oxidized Fe 2+ . 60 Co, 54 Mn and 51 Cr form covalent associations between unpaired 3d iron electrons and the adsorbed element. This process is not predominant with selenium IV or VI reduced to the metallic state or fixed on ferric hydroxide in the selenite form. These conclusions can be applied to pollutant analysis and to water purification and contribute to our understanding of the role of iron in the distribution of oligo-elements in aqueous media. (author) [fr

  6. Profile modification and hot electron temperature from resonant absorption at modest intensity

    International Nuclear Information System (INIS)

    Albritton, J.R.; Langdon, A.B.

    1980-01-01

    Resonant absorption is investigated in expanding plasmas. The momentum deposition associated with the ejection of hot electrons toward low density via wavebreaking readily exceeds that of the incident laser radiation and results in significant modification of the density profile at critical. New scaling of hot electron temperature with laser and plasma parameters is presented

  7. Long distance electron transmission couples sulphur, iron, calcium and oxygen cycling in marine sediment

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Nielsen, Lars Peter

    sulfide oxidation leads to electric field formation, sulfide depletion and acidification of the upper centimeters of the sediment. This promoted ion migration and dissolution of carbonates and iron sulfides. Sulfide released from iron sulfides was the major e-donor in the system. Ferrous iron released...... from iron sulfides was to a large extend deposited in the oxic zone as iron oxides and Ca2+ eventually precipitates at the surface as due to high pH caused by cathodic oxygen reduction. The result show how long distance electron transmission allows oxygen to drive the allocation of important minerals...... geochemical alterations in the upper centimetres of the anoxic sediment: Sulphides were oxidized to sulphate in anoxic sediment layers. Electrons from this half-reaction were passed to the oxic layers cm above. In this way the domain of oxygen was extended far beyond it’s physically presence. Bioelectrical...

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    Berner, L.; Miller, D.

    1986-01-01

    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 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 59 Fe from polys was doubled in the presence of BSA (7.8 vs 16.1%, p 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

  10. Electronic properties of iron impurity in hcp metals from Moessbauer studies

    International Nuclear Information System (INIS)

    Janot, C.; Delcroix, P.

    1975-01-01

    Moessbauer spectroscopy was used in quantitative investigating the electronic properties of iron impurities in hexagonal close-packed metals. Beryllium of the highest commercially obtainable purity containing about 300 ppm residual impurities was used as a host element. Experimental evidence is given for the existence of localized electronic states which have non-spherical distribution and obviously contribute especially to the electric field gradient. Iron impurity seems to retain the same electronic behaviour as long as the host hcp metal is a normal one (Mg, Cd, Zn), but the localized electronic states seem to disappear when the host is a transition hcp metal (Co, Ti, Sc, Zr, etc.). (Z.S.)

  11. Diffraction and absorption of inelastically scattered electrons for K-shell ionization

    International Nuclear Information System (INIS)

    Josefsson, T.W.; Allen, L.J.

    1995-01-01

    An expression for the nonlocal inelastic scattering cross section for fast electrons in a crystalline environment, which explicitly includes diffraction as well as absorption for the inelastically scattered electrons, is used to carry out realistic calculations of K-shell electron energy loss spectroscopy (EELS) and energy dispersive x-ray (EDX) analysis cross sections. The calculations demonstrate quantitatively why, in EDX spectroscopy, integration over the dynamical states of the inelastically scattered electron averages in such a way that an effective plane wave representation of the scattered electrons is a good approximation. This is only the case for large enough acceptance angles of the detector in an EELS experiment. For EELS with smaller detector apertures, explicit integration over the dynamical final states is necessary and inclusion of absorption for the scattered electrons is important, particularly for thicker crystals. 50 refs., 7 figs

  12. In Rwandese Women with Low Iron Status, Iron Absorption from Low-Phytic Acid Beans and Biofortified Beans Is Comparable, but Low-Phytic Acid Beans Cause Adverse Gastrointestinal Symptoms.

    Science.gov (United States)

    Petry, Nicolai; Rohner, Fabian; Gahutu, Jean Bosco; Campion, Bruno; Boy, Erick; Tugirimana, Pierrot L; Zimmerman, Michael Bruce; Zwahlen, Christian; Wirth, James P; Moretti, Diego

    2016-05-01

    Phytic acid (PA) is a major inhibitor of iron bioavailability from beans, and high PA concentrations might limit the positive effect of biofortified beans (BBs) on iron status. Low-phytic acid (lpa) bean varieties could increase iron bioavailability. We set out to test whether lpa beans provide more bioavailable iron than a BB variety when served as part of a composite meal in a bean-consuming population with low iron status. Dietary iron absorption from lpa, iron-biofortified, and control beans (CBs) (regular iron and PA concentrations) was compared in 25 nonpregnant young women with low iron status with the use of a multiple-meal crossover design. Iron absorption was measured with stable iron isotopes. PA concentration in lpa beans was ∼10% of BBs and CBs, and iron concentration in BBs was ∼2- and 1.5-fold compared with CBs and lpa beans, respectively. Fractional iron absorption from lpa beans [8.6% (95% CI: 4.8%, 15.5%)], BBs [7.3% (95% CI: 4.0%, 13.4%)], and CBs [8.0% (95% CI: 4.4%, 14.6%)] did not significantly differ. The total amount of iron absorbed from lpa beans and BBs was 421 μg (95% CI: 234, 756 μg) and 431 μg (95% CI: 237, 786 μg), respectively, and did not significantly differ, but was >50% higher (P beans were hard to cook, and their consumption caused transient adverse digestive side effects in ∼95% of participants. Gel electrophoresis analysis showed phytohemagglutinin L (PHA-L) residues in cooked lpa beans. BBs and lpa beans provided more bioavailable iron than control beans and could reduce dietary iron deficiency. Digestive side effects of lpa beans were likely caused by PHA-L, but it is unclear to what extent the associated digestive problems reduced iron bioavailability. This trial was registered at clinicaltrials.gov as NCT02215278. © 2016 American Society for Nutrition.

  13. Two-step milling on the carbonyl iron particles and optimizing on the composite absorption

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai 200438 (China); Yuan, Liming; Wang, Xiaobing [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai 200438 (China); Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2016-08-15

    The flaky carbonyl iron particles (CIPs) were prepared using a two-step milling process. The surface morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2–18 GHz. Then Hermite interpolation based on the calculated scattering parameters of the tested composite was used to derive the permittivity and permeability of the composite with random volume content. The results showed that the saturation magnetization value of the flaky CIPs decreased as the CIPs was changed to the flakes by high and low speeding milling. The diffraction peaks of the single α-Fe existed in the XRD pattern of CIPs, and the characteristic peaks was broad and the intensity of the diffraction pattern was lower as the high-speeding milling time increased. The sample H2L20 had the largest particle size, the average diameter was 8.64 μm, the thickness was 0.59 μm according to the fitted aspect ratio 14.65. The derived permittivity and permeability using the Hermite interpolation was accurate compared with the tested result, the deviation was about 0.39 + j0.45 and 2.5 + j0.51. Finally, the genetic algorithm was used to optimize the thickness of the CIPs composite of a wide absorbing band of 8–18 GHz. The optimized reflection loss (RL) result showed that the absorbing composites with thickness 1.47 mm had an excellent absorbing property (RL < −10 dB) in 8–18 GHz. - Graphical abstract: The property of absorber added two speeding milling CIPs could be enhanced using the genetic algorithm. - Highlights: • Flaky CIPs were prepared using a two-step milling process. • The permeability increased during the low speeding milling. • The aspect ratio of flaky CIPs increased in the optimized process

  14. Extraordinary mode absorption at the electron cyclotron harmonic frequencies as a Tokamak plasma diagnostic

    International Nuclear Information System (INIS)

    Pachtman, A.

    1986-09-01

    Measurements of Extraordinary mode absorption at the electron cyclotron harmonic frequencies are of unique value in high temperature, high density Tokamak plasma diagnostic applications. An experimental study of Extraordinary mode absorption at the semi-opaque second and third harmonics has been performed on the ALCATOR C Tokamak. A narrow beam of submillimeter laser radiation was used to illuminate the plasma in a horizontal plane, providing a continuous measurement of the one-pass, quasi-perpendicular transmission

  15. The effect of electron irradiation on the structure and iron speciation in sodium aluminum (iron) phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Stefanovsky, S.V., E-mail: serge.stefanovsky@yandex.ru [Frumkin Institute of Physical Chemistry and Electrochemistry RAS (Russian Federation); Presniakov, I.A.; Sobolev, A.V.; Glazkova, I.S. [Lomonosov Moscow State University, Department of Chemistry (Russian Federation); Kadyko, M.I.; Stefanovsky, O.I. [Frumkin Institute of Physical Chemistry and Electrochemistry RAS (Russian Federation)

    2016-08-01

    The effect of 8 MeV electron irradiation on the structure of glasses in the series 40 Na{sub 2}O, (20-x) Al{sub 2}O{sub 3}, x Fe{sub 2}O{sub 3}, 40 P{sub 2}O{sub 5} (mol.%) and on the iron speciation in these samples was studied by FTIR and Mössbauer spectroscopic techniques. Irradiation up to a dose of 1.0 MGy has no appreciable effects on the character of the bonds within anionic motif of the glass network. Electron irradiation increases the fraction of aluminum in octahedral coordination. Iron in both unirradiated and irradiated glasses is present mainly as Fe(III) (60–75% of the total amount) in the glasses and partly as Fe(II) and the ratio of two forms remains constant up to a dose of 1.0 MGy.

  16. Absorption and Flux Density Measurements in an Iron Plug in R1

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Ragnar; Braun, Josef

    1958-11-15

    Thermal, epithermal and fast neutron fluxes have been measured in a 60 cm long, 'sliced' iron plug, which has been placed in the lower iron lid of the Swedish reactor R1. Au foils, Cu foils, Mn foils, P packets, Cu wires and small Fe cylinders have been used. The gamma flux has been determined with film dosimeters. The measurements have shown that only in the first centimeters of the iron is the activation determined by the thermal flux, which decreases with a relaxation length {lambda}= (1.51 {+-} 0.02) cm. The epithermal flux is entirely predominant already after 10 cm ( {lambda} = 16 cm). The epithermal neutron flux decreases even more slowly than the fast flux ({lambda} = 6.2 cm)

  17. Absorption and Flux Density Measurements in an Iron Plug in R1

    International Nuclear Information System (INIS)

    Nilsson, Ragnar; Braun, Josef

    1958-11-01

    Thermal, epithermal and fast neutron fluxes have been measured in a 60 cm long, 'sliced' iron plug, which has been placed in the lower iron lid of the Swedish reactor R1. Au foils, Cu foils, Mn foils, P packets, Cu wires and small Fe cylinders have been used. The gamma flux has been determined with film dosimeters. The measurements have shown that only in the first centimeters of the iron is the activation determined by the thermal flux, which decreases with a relaxation length λ= (1.51 ± 0.02) cm. The epithermal flux is entirely predominant already after 10 cm ( λ = 16 cm). The epithermal neutron flux decreases even more slowly than the fast flux (λ = 6.2 cm)

  18. Observation of soft x-ray radiation from Heliotron E plasmas by the absorption method for the measurement of electron temperatures

    International Nuclear Information System (INIS)

    Kaneko, H.; Tohda, T.; Iiyoshi, A.

    1989-01-01

    An absorption method of soft x ray is applied to Heliotron E plasmas for measurement of the electron temperature. Nitrogen gas is used as an absorber for convenience, owing to its accurate, uniform, and easily controllable density. The general feature of the absorption method for measurement of the electron temperature is discussed using a model with two parameters: the generalized thickness of the absorber and the electron temperature. The energy resolution of this method is not sufficient as a general method for spectral analysis. Hence, it is necessary to assume in advance such a model spectrum as consists of bremsstrahlung, recombination radiation, and impurity line radiation. Since the spectrum is always assumed before the analysis, we should try to find the origins of deformation of the energy spectrum and to correct the contribution. The effect of line emission from impurity ions to the estimated electron temperature is evaluated as a function of the electron temperature and the energy of the line relative to the generalized absorber thickness used in the measurement. An actual spectrum is measured by a pulse-height analysis (PHA) of the soft x ray. The one clear line, from chlorine, is not significant in the present determination of the electron temperature by the absorption method. Another possible line from iron at energy less than 1 keV is included in the analysis. Using a convenient method for determination of local emissivity from a chord-integrated emissivity, the electron temperature is determined from the local emissivity. The observed broad electron-temperature profile might be an artifact due to recombination radiation of the highly ionized ion diffused out of the hot core of the plasma. It is confirmed that the absorption method gives absolute measurement of the electron temperature at the plasma center, when additional information on impurity lines are given by PHA

  19. Calculation of optical and K pre-edge absorption spectra for ferrous iron of distorted sites in oxide crystals

    Science.gov (United States)

    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.

  20. Study of electron-beam-evaporated MgO films using electron diffraction, optical absorption and cathodoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Aboelfotoh, M.O.; Ramsey, J.N.

    1982-05-21

    Reflection high energy electron diffraction, optical absorption and cathodoluminescence were used to study MgO films deposited onto fused silica, single-crystal silicon and LiF substrates at various temperatures. Results showed that some of the same optical absorption and emission bands observed in X- or UV-irradiated, additively colored or mechanically deformed MgO crystals were observed in evaporated MgO films. The peak positions and the relative peak intensities of the optical absorption and emission bands depended on the substrate temperature during film deposition as well as on the structure of the film. The effect of heating the films in air and vacuum on the optical absorption and emission bands is also discussed.

  1. Uranium,Radium and Iron Absorption from Liquid Waste Uranium Ore Processing by Zeolite

    International Nuclear Information System (INIS)

    Wismawati, T; Sorot sudiro, A; Herjati, T

    1998-01-01

    The aim of this work is to determine zeolites sorption capacity and the distribution coefficient of uranium, radium, and iron in zeolite-liquid waste system. Mineralogical composition of zeolite used in the experiment has been determine by examining the thin sections of zeolite grains under a microscope. Zeolite has ben activated by the dilute sulfuric acid or sodium hydroxide solution. The results show that the use of 0.25 N sodium hydroxide solution could be optimizing the zeolite for uranium and iron ions sorption and that of 0.1 N sulfuric acid solution is for radium sorption. The re-activation process has been carried out in three hours. Under such a condition, the sorption efficiency of zeolite to those ions have been known to be 45.85% for uranium, 96.63 % for iron and 87.80 % for radium. The distribution coefficients of uranium, radium and iron ion in zeolite-liquid waste system have been calculated 0.85, 7.02, and 28.65 ml/g respectively

  2. Alternating magnetic field energy absorption in the dispersion of iron oxide nanoparticles in a viscous medium

    Czech Academy of Sciences Publication Activity Database

    Smolkova, I.S.; Kazantseva, N.E.; Babayan, V.; Smolka, P.; Parmar, H.; Vilcakova, J.; Schneeweiss, Oldřich; Pizúrová, Naděžda

    2015-01-01

    Roč. 374, JAN (2015), s. 508-515 ISSN 0304-8853 Institutional support: RVO:68081723 Keywords : Iron oxide nanoparticles * Coprecipitation * Magnetic interactions * Specific loss power * Hyperthermia Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.357, year: 2015

  3. Content of zinc, iron, calcium and their absorption inhibitors in foods commonly consumed in Ethiopia

    NARCIS (Netherlands)

    Umeta, M.; West, C.E.; Fufa, H.

    2005-01-01

    The zinc, iron, calcium, phosphorus, phytate, tannin and moisture content of 36 foods consumed in rural Ethiopia were analysed. The foods analysed included those based on cereals, starchy tubers and roots, and legumes and vegetables as well as some fruits. Although many foods were relatively rich in

  4. Extraction of Iron and Manganese from Pyrolusite Absorption Residue by Ammonium Sulphate Roasting–Leaching Process

    Directory of Open Access Journals (Sweden)

    Lin Deng

    2018-01-01

    Full Text Available The residue from desulfurization and denitrification of exhaust gas treatment process with pyrolusite ore as absorbent is regarded as a potential source of iron and manganese. In this study, an extraction process is proposed for recovery of iron and manganese with ammonium sulphate roasting followed by sulphuric acid leaching. Firstly, the conversion mechanism was analyzed through mineral phase analysis of roasting products at different roasting temperature by means of X-ray diffraction (XRD technology. Then, the parameters of the roasting procedure such as roasting temperature and time, ammonium sulphate dosage, leaching temperature, leaching time, and sulphuric acid concentration are examined. The results implicate that the iron oxide and manganese dioxide in the residue are firstly converted into the water-soluble ( NH 4 3 Fe ( SO 4 3 and ( NH 4 2 Mn 2 ( SO 4 3 at 200–350 °C, and then the more stable NH 4 Fe ( SO 4 2 and MnSO 4 are formed, at temperature higher than 350 °C. Under optimum conditions, 95.2% Fe and 97.0% Mn can be extracted. Reactant diffusion through inert layer of silicon dioxide was considered as the rate-limiting step for iron extraction with an activation energy of 20.56 kJ/mol, while, the recovery process of Mn was controlled by both reactant diffusion and chemical reaction with an activation energy of 29.52 kJ/mol.

  5. Electron small polarons and their mobility in iron (oxyhydr)oxide nanoparticles

    DEFF Research Database (Denmark)

    Katz, Jordan E; Zhang, Xiaoyi; Attenkofer, Klaus

    2012-01-01

    Electron mobility within iron (oxyhydr)oxides enables charge transfer between widely separated surface sites. There is increasing evidence that this internal conduction influences the rates of interfacial reactions and the outcomes of redox-driven phase transformations of environmental interest....... To determine the links between crystal structure and charge-transport efficiency, we used pump-probe spectroscopy to study the dynamics of electrons introduced into iron(III) (oxyhydr)oxide nanoparticles via ultrafast interfacial electron transfer. Using time-resolved x-ray spectroscopy and ab initio...

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

    Science.gov (United States)

    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.

  7. Ab initio calculation of the electronic absorption spectrum of liquid water

    International Nuclear Information System (INIS)

    Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

    2014-01-01

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O–H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase

  8. Extraction and atomic absorption spectrophotometric determination of iron and ruthenium by using potassium xanthates

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, M; Kiboku, M [Kinki Univ., Higashi-Osaka, Osaka (Japan)

    1981-06-01

    Potassium xanthates (potassium o-alkyl dithiocarbonate; KRX) react with many metal ions, and so the complex formation with iron (II, III) ion and the extraction of their complexes has been studied to some extent, but those of ruthenium (III) have not been. Iron-xanthate and ruthenium-xanthate complexes can be extracted into methyl isobutyl ketone (MIBK) from weakly acidic solution to weakly alkaline solution. For quantitative extraction of iron (20 ..mu..g/40 ml), KRX concentration should be above 2.0 x 10/sup -2/ mol dm/sup -3/ of KEtX, 1.0 x 10/sup -2/ mol dm/sup -3/ of KPrX, and 5.0 x 10/sup -3/ mol dm/sup -3/ of KBtX and KPeX, and for that of ruthenium (202 ..mu..g/40 ml), it should be above 2.0 x 10/sup -1/ mol dm/sup -3/ of KEtX and KPrX. Formation constant of ruthenium-xanthate complexes is presumed to be small. A 100-fold excess of Ni(II), Co(II), Cu(II), WO/sub 4//sup 2 -/, PO/sub 4//sup 3 -/, CrO/sub 4//sup 2 -/, and Cr/sub 2/O/sub 7//sup 2 -/ interfered with the determination of iron, however, the interferences are eliminated by adding 5 ml of 0.1 mol dm/sup -3/ ascorbic acid solution. For the determination of ruthenium, a 50-fold excess of Ag(I), Hg(II), Pb(II), Zn(II), Mn(II), Cr(III), and Pt(II), or a 100-fold excess of NO/sub 2//sup -/, S/sub 2/O/sub 3//sup 2 -/, CrO/sub 4//sup 2 -/ and Cr/sub 2/O/sub 7//sup 2 -/, respectively, interfered. The coefficient of variation after each ten runs, ranges from 0.9% to 3.2% in the determination of 10 ..mu..g, 20 ..mu..g, and 30 ..mu..g of iron, and from 1.4% to 4.3% in the determination of 100 ..mu..g, 200 ..mu..g, and 300 ..mu..g of ruthenium. The determination limit in aqueous samples is 0.02 ppm for iron and 0.2 ppm for ruthenium, when the volume ratio of aqueous phase to organic phase (MIBK) is 10:1.

  9. Effect of microplastic deformation on the electron ultrasonic absorption in high-purity molybdenum monocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Pal' -Val' , P.P. (AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur); Kaufmann, Kh.J. (Akademie der Wissenschaften der DDR, Berlin)

    1983-03-01

    The low temperature (100-6 K) linear absorption of ultrasound (88 kHz) by high purity molybdenum single crystals have been studied. Both unstrained samples and samples subjected to microplastic deformation (epsilon<=0.45%) were used. Unstrained samples displayed at T<30 K a rapid increase in the absorption with lowering temperature which is interpreted as an indication of electron viscosity due to electron-phonon collisions. After deformation this part of absorption disappeared. This seems to suggest that microplastic deformation brings about in the crystal a sufficiently large number of defects that can compete with phonons in restricting the electron mean free path. A low temperature ''dynamic annealing'' has been revealed in strained samples, that is, almost complete recovery of the absorption nature under irradiation with high amplitude sound, epsilon/sub 0/ approximately 10/sup -4/, during 10 min, at 6 K. A new relaxation peak of absorption at 10 K has been found in strained samples.

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

    Science.gov (United States)

    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.

  11. Solvated electron: criticism of a suggested correlation of chemical potential with optical absorption energy

    International Nuclear Information System (INIS)

    Farhataziz, M.

    1984-01-01

    A recent theoretical treatment of the absorption spectrum of the solvated electron, e - sub(s), maintains that rigorously μ 0 >= -0.75 Esub(av), which gives empirical relationship, μ 0 >= -(0.93 +- 0.02)Esub(max). For e - sub(s) in a particular solvent at a temperature and pressure, μ 0 , Esub(av) and Esub(max) are standard chemical potential, average energy of the absorption spectrum and the energy at the absorption maximum respectively. The temperature and pressure effects on the absorption spectrum of e - sub(s) in water and liquid ammonia do not support the equality sign in the above cited relationships. The implications of inequality expressed above are discussed for e - sub(s) in water and liquid ammonia. (author)

  12. Continuous registration of optical absorption spectra of periodically produced solvated electrons

    International Nuclear Information System (INIS)

    Krebs, P.

    1975-01-01

    Absorption spectra of unstable intermediates, such as solvated electrons, were usually taken point by point, recording the time-dependent light absorption after their production by a flash. The experimental arrangement for continuous recording of the spectra consists of a conventional one beam spectral photometer with a stabilized white light source, a monochromator, and a light detector. By periodic production of light absorbing intermediates such as solvated electrons, e.g., by ac uv light, a small ac signal is modulated on the light detector output which after amplification can be continuously recorded as a function of wavelength. This method allows the detection of absorption spectra when disturbances from the outside provide a signal-to-noise ratio smaller than 1

  13. X-ray absorption study of the electronic structure of Mn-doped amorphous Si

    Energy Technology Data Exchange (ETDEWEB)

    Arenholz, Elke; Zeng, Li; Huegel, A.; Helgren, E.; Hellman, F.; Piamonteze, C.; Arenholz, E.

    2008-03-08

    The electronic structure of Mn in amorphous Si (a-Mn{sub x}Si{sub 1?x}) is studied by X-ray absorption spectroscopy at the Mn L{sub 3,2} edges for x = 0.005-0.18. Except the x = 0.005 sample, which shows a slight signature of Mn{sup 2+} atomic multiplets associated with a local Mn moment, all samples have broad and featureless L{sub 3,2} absorption peaks, corresponding to an itinerant state for all 3d electrons. The broad X-ray absorption spectra exclude the possibility of a localized 3d moment and explain the unexpectedly quenched Mn moment in this magnetically-doped amorphous semiconductor. Such a fully delocalized d state of Mn dopant in Si has not been previously suggested.

  14. Modification of the Absorption Edge of GaAs Arising from Hot-Electron Effects

    DEFF Research Database (Denmark)

    McGroddy, J. C.; Christensen, Ove

    1973-01-01

    We have observed a large enhancement of the electric-field-induced optical absorption arising from hot-electron effects in n-type GaAs at 77 K. The magnitude and field dependence of the enhancement can be approximately accounted for by a theory attributing the effect to broadening of the final...... states of the optical transitions by interaction with the nonequilibrium optical phonons produced by the hot electrons....

  15. Tuning of few-electron states and optical absorption anisotropy in GaAs quantum rings.

    Science.gov (United States)

    Wu, Zhenhua; Li, Jian; Li, Jun; Yin, Huaxiang; Liu, Yu

    2017-11-15

    The electronic and optical properties of a GaAs quantum ring (QR) with few electrons in the presence of the Rashba spin-orbit interaction (RSOI) and the Dresselhaus spin-orbit interaction (DSOI) have been investigated theoretically. The configuration interaction (CI) method is employed to calculate the eigenvalues and eigenstates of the multiple-electron QR accurately. Our numerical results demonstrate that the symmetry breaking induced by the RSOI and DSOI leads to an anisotropic distribution of multi-electron states. The Coulomb interaction offers additional modulation of the electron distribution and thus the optical absorption indices in the quantum rings. By tuning the magnetic/electric fields and/or electron numbers in a quantum ring, one can change its optical properties significantly. Our theory provides a new way to control the multi-electron states and optical properties of a QR by hybrid modulations or by electrical means only.

  16. Electronic properties and optical absorption of graphene-polyvinylidene fluoride nanocomposites: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, Siddheshwar, E-mail: schopra1@amity.edu

    2017-01-15

    Graphene/polyvinylidene fluoride (graphene/PVDF) nanocomposites were studied using Density functional theory (DFT)/Time dependent density functional theory (TDDFT) calculations. Five nanocomposite configurations were constructed. Electronic properties like binding energy, electronic gap and work function were calculated. The most stable structure was determined. The electronic gap of graphene shifts from semiconducting to conducting, on nanocomposite formation. Workfunction of the most stable nanocomposite was 4.34eV ± 0.05eV, close to that of the pristine graphene (4.33eV ± 0.05eV). Thermochemical analysis showed that the adsorption is spontaneous above ∼870 K, and endothermic in nature. TDDFT calculations were performed for B3LYP, LSDA, BHHLYP and PBE0 functionals. B3LYP and PBE0 are suitable in describing optical absorption. Optical gap of graphene shrinks, and light absorption gets enhanced on nanocomposite formation. - Highlights: • Various properties of graphene-PVDF nanocomposites were studied theoretically. • Electronic gap of graphene shifts to conducting nature, on composite formation. • Adsorption is spontaneous above ∼870 K, and endothermic in nature. • B3LYP and PBE0 functionals are suitable in describing absorption. • Optical absorption gets enhanced on nanocomposite formation.

  17. Complexes of uranyl with N-oxides of heterocyclic amines. Electron-vibrational absorption spectra

    International Nuclear Information System (INIS)

    Jezowska-Trzebiatowska, B.; Wieczorek, M.

    1977-01-01

    A number of coordination compounds formed by uranyl chloride and nitrate with N-oxides of heterocyclic amines have been prepared and characterized by spectral measurements in the absorption region 20000-50000 cm -1 . The electrons and vibronic transitions have been determined and discussed. (author)

  18. Electronic properties and optical absorption of graphene-polyvinylidene fluoride nanocomposites: A theoretical study

    International Nuclear Information System (INIS)

    Chopra, Siddheshwar

    2017-01-01

    Graphene/polyvinylidene fluoride (graphene/PVDF) nanocomposites were studied using Density functional theory (DFT)/Time dependent density functional theory (TDDFT) calculations. Five nanocomposite configurations were constructed. Electronic properties like binding energy, electronic gap and work function were calculated. The most stable structure was determined. The electronic gap of graphene shifts from semiconducting to conducting, on nanocomposite formation. Workfunction of the most stable nanocomposite was 4.34eV ± 0.05eV, close to that of the pristine graphene (4.33eV ± 0.05eV). Thermochemical analysis showed that the adsorption is spontaneous above ∼870 K, and endothermic in nature. TDDFT calculations were performed for B3LYP, LSDA, BHHLYP and PBE0 functionals. B3LYP and PBE0 are suitable in describing optical absorption. Optical gap of graphene shrinks, and light absorption gets enhanced on nanocomposite formation. - Highlights: • Various properties of graphene-PVDF nanocomposites were studied theoretically. • Electronic gap of graphene shifts to conducting nature, on composite formation. • Adsorption is spontaneous above ∼870 K, and endothermic in nature. • B3LYP and PBE0 functionals are suitable in describing absorption. • Optical absorption gets enhanced on nanocomposite formation.

  19. Optical absorption of BaF2 crystals with different prehistory when irradiated by high-energy electrons

    International Nuclear Information System (INIS)

    Chinkov, E P; Stepanov, S A; Shtan'ko, V F; Ivanova, T S

    2016-01-01

    The spectra of stable optical absorption of BaF 2 crystals containing uncontrollable impurities after irradiation with 3 MeV electrons are studied at room temperature. The dependence of the efficiency of stable color accumulation in the region of emerging crossluminescence on the absorption coefficients measured near the fundamental absorption edge in unirradiated crystals of various prehistory is traced. (paper)

  20. Iron in diet

    Science.gov (United States)

    ... Reasonable amounts of iron are also found in lamb, pork, and shellfish. Iron from vegetables, fruits, grains, ... strawberries, tomatoes, and potatoes) also increase iron absorption. Cooking foods in a cast-iron skillet can also ...

  1. Damping effect of the inner band electrons on the optical absorption and bandwidth of metal nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ochoo, Lawrence, E-mail: lawijapuonj@yahoo.com; Migwi, Charles; Okumu, John [Kenyatta University, Physics Department (Kenya)

    2012-12-15

    Conflicts and discrepancies around nanoparticle (NP) size effect on the optical properties of metal NPs of sizes below the mean free path of electron can be traced to the internal damping effect of the hybrid resonance of the inner band (IB) and the conduction band (CB) electrons of the noble metals. We present a scheme to show how alternative mathematical formulation of the physics of interaction between the CB and the IB electrons of NP sizes <50 nm justifies this and resolves the conflicts. While a number of controversies exist between classical and quantum theories over the phenomenological factors to attribute to the NP size effect on the absorption bandwidth, this article shows that the bandwidth behavior can be well predicted from a different treatment of the IB damping effect, without invoking any of the controversial phenomenological factors. It finds that the IB damping effect is mainly frequency dependent and only partly size dependent and shows how its influence on the surface plasmon resonance can be modeled to show the influence of NP size on the absorption properties. Through the model, it is revealed that strong coupling of IB and CB electrons drastically alters the absorption spectra, splitting it into distinctive dipole and quadrupole modes and even introduce a behavioral switch. It finds a strong overlap between the IB and the CB absorptions for Au and Cu but not Ag, which is sensitive to the NP environment. The CB modes shift with the changing refractive index of the medium in a way that can allow their independent excitation, free of influence of the IB electrons. Through a hybrid of parameters, the model further finds that metal NP sizes can be established not only by their spectral absorption peak locations but also from a proper correlation of the peak location and the bandwidth (FWHM).

  2. Experimental studies on the electronic structure of pyrite FeS2 films prepared by thermally sulfurizing iron films

    International Nuclear Information System (INIS)

    Zhang Hui; Wang Baoyi; Zhang Rengang; Zhang Zhe; Wei Long; Qian Haijie; Su Run; Kui Rexi

    2006-01-01

    Pyrite FeS 2 films have been prepared by thermally sulfurizing iron films deposited by magnetron sputtering. The electronic structures were studies by X-ray absorption near edge structure and X-ray photoemission spectrum. The results show that an S 3p valence band with relatively higher intensity compared to the calculation exists in 2-10 eV range and a high density below the Fermi level of Fe 3d states were detected. A second gap of 2.8 eV in the unoccupied density of states was found above the conduction band which was 2.4 eV by experimentally calculation. The difference between t 2g and e g which were formed in an octahedral crystal field was computed to be 2.1 eV. (authors)

  3. Electronic origin of strain effects on solute stabilities in iron

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei; Li, Xiangyan; Xu, Yichun, E-mail: xuyichun@issp.ac.cn, E-mail: csliu@issp.ac.cn; Liu, C. S., E-mail: xuyichun@issp.ac.cn, E-mail: csliu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China); Liang, Yunfeng [Environment and Resource System Engineering, Kyoto University, Kyoto 615-8540 (Japan); Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031 (China)

    2016-08-21

    Nonuniform strain fields might induce the segregation of alloying solutes and ultimately lead to the mechanical performance degradation of body-centered-cubic (bcc) Fe based steels serving in extreme environments, which is worthy of investigation. In this paper, two typical volume-conserving strains, shear strain (SS) and normal strain (NS), are proposed to investigate the strain effects on solute stabilities in bcc iron by first-principles calculations. For solutes in each transition metal group, the calculated substitution energy change due to SS exhibits a linear dependence on the valence d radius of the solutes, and the slope decreases in an exponential manner as a function of the absolute difference between the Watson's electronegativity of iron and the averaged value of each transition metal group. This regularity is attributed to the Pauli repulsion between the solutes and the nearest neighboring Fe ions modulated by the hybridization of valence d bands and concluded to be originated from the characteristics of valence d bonding between the transition-metal solutes and Fe ions under SS. For main-group and post transition-metal solutes, the considerable drop of substitution energy change due to NS is concluded to be originated from the low-energy side shift of the widened valence s and p bands of the solutes. Our results indicate that the stabilities of substitutional solutes in iron under volume-conserving strain directly correlate with the intrinsic properties of the alloying elements, such as the valence d radius and occupancy, having or not having valence s and p bands.

  4. Temperature dependence of the electromagnetic properties and microwave absorption of carbonyl iron particles/silicone resin composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yingying; Zhou, Wancheng; Qing, Yuchang; Luo, Fa; Zhu, Dongmei

    2015-01-15

    Microwave absorbing composites with thin thickness and wideband absorption were successfully prepared by a spraying method using carbonyl iron particles (CIPs) as absorbers and silicone resin as the matrix. The value of reflection loss (RL) below −5 dB can be obtained in the frequency range of 5.76–18 GHz for the composite with 0.8 mm thickness. The temperature dependence of electromagnetic properties and RL of the composites were investigated. The RL of the composite showed a slight variation when the temperature reached up to 200 °C while decreased at 300 °C. The room temperature RL of the composite did not display significant difference before and after the heat treatment at 300 °C for 10 h; the mechanism was also discussed. - Highlights: • Carbonyl iron particles/silicone resin composites are prepared by a spraying method. • Reflection loss values exceed −5 dB at 5.76–18 GHz for an absorber of 0.8 mm thickness. • The variation of reflection loss was studied from room temperature to 300 °C.

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

    Directory of Open Access Journals (Sweden)

    David Keinan

    2010-01-01

    Full Text Available 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 (<.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.

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

    Science.gov (United States)

    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.

  7. Time dependent density functional theory of light absorption in dense plasmas: application to iron-plasma

    International Nuclear Information System (INIS)

    Grimaldi, F.; Grimaldi-Lecourt, A.; Dharma-Wardana, M.W.C.

    1986-10-01

    The objective of this paper is to present a simple time-dependent calculation of the light absorption cross section for a strongly coupled partially degenerate plasma so as to transcend the usual single-particle picture. This is achieved within the density functional theory (DFT) of plasmas by generalizing the method given by Zangwill and Soven for atomic calculations at zero temperature. The essential feature of the time dependent DFT is the correct treatment of the relaxation of the system under the external field. Exploratory calculations for a Fe-plasma at 100 eV show new features in the absorption cross section which are absent in the usual single particle theory. These arise from inter-shell correlations, channel mixing and self-energy effects. These many-body effects introduce significant modifications to the radiative properties of plasmas and are shown to be efficiently calculable by time dependent density functional theory (TD-DFT)

  8. Time dependent density functional theory of light absorption in dense plasmas: application to iron-plasma

    International Nuclear Information System (INIS)

    Grimaldi, F.; Grimaldi-Lecourt, A.; Dharma-Wardana, M.W.C.

    1985-02-01

    The objective of this paper is to present a simple time-dependent calculation of the light absorption cross section for a strongly coupled partially degenerate plasma so as to transcend the usual single-particle picture. This is achieved within the density functional theory (DFT) of plasmas by generalizing the method given by Zangwill and Soven for atomic calculations at zero temperature. The essential feature of the time dependent DFT is the correct treatment of the relaxation of the system under the external field. Exploratory calculations for an Fe-plasma at 100 eV show new features in the absorption cross section which are absent in the usual single particle theory. These arise from inter-shell correlations, channel mixing and self-energy effects. These many-body effects introduce significant modifications to the radiative properties of plasma and are shown to be efficiently calculable by time dependent density functional theory (TD-DFT)

  9. Imaging Plasmon Hybridization of Fano Resonances via Hot-Electron-Mediated Absorption Mapping.

    Science.gov (United States)

    Simoncelli, Sabrina; Li, Yi; Cortés, Emiliano; Maier, Stefan A

    2018-05-04

    The inhibition of radiative losses in dark plasmon modes allows storing electromagnetic energy more efficiently than in far-field excitable bright-plasmon modes. As such, processes benefiting from the enhanced absorption of light in plasmonic materials could also take profit of dark plasmon modes to boost and control nanoscale energy collection, storage, and transfer. We experimentally probe this process by imaging with nanoscale precision the hot-electron driven desorption of thiolated molecules from the surface of gold Fano nanostructures, investigating the effect of wavelength and polarization of the incident light. Spatially resolved absorption maps allow us to show the contribution of each element of the nanoantenna in the hot-electron driven process and their interplay in exciting a dark plasmon mode. Plasmon-mode engineering allows control of nanoscale reactivity and offers a route to further enhance and manipulate hot-electron driven chemical reactions and energy-conversion and transfer at the nanoscale.

  10. Optical Absorption and Electron Injection of 4-(Cyanomethylbenzoic Acid Based Dyes: A DFT Study

    Directory of Open Access Journals (Sweden)

    Yuehua Zhang

    2015-01-01

    Full Text Available Density functional theory (DFT and time-dependent density functional theory (TDDFT calculations were carried out to study the ground state geometries, electronic structures, and absorption spectra of 4-(cyanomethylbenzoic acid based dyes (AG1 and AG2 used for dye-sensitized solar cells (DSSCs. The excited states properties and the thermodynamical parameters of electron injection were studied. The results showed that (a two dyes have uncoplanar structures along the donor unit and conjugated bridge space, (b two sensitizers exhibited intense absorption in the UV-Vis region, and (c the excited state oxidation potential was higher than the conduction band edge of TiO2 photoanode. As a result, a solar cell based on the 4-(cyanomethylbenzoic acid based dyes exhibited well photovoltaic performance. Furthermore, nine dyes were designed on the basis of AG1 and AG2 to improve optical response and electron injection.

  11. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...... of transcription factors, activation of the mitochondrial apoptotic machinery or of other cell death mechanisms. The pro-inflammatory cytokine IL-1β facilitates divalent metal transporter 1 (DMT1)-induced β-cell iron uptake and consequently ROS formation and apoptosis, and we propose that this mechanism provides...

  12. Synchrotron radiation and absorption at electron cyclotron harmonics in inhomogeneous plasmas

    International Nuclear Information System (INIS)

    Hu, Jian-Long.

    1993-01-01

    In order to understand fully the absorption, emission and conversion phenomena for any electron cyclotron harmonic, one must include all relevant mode conversion processes and a finite parallel wave number k parallel . Relativistic plasma mode conversion and tunneling equations at the second and third electron cyclotron harmonics have been derived analytically. A finite k parallel has been introduced which keeps the coupling between the O-mode, the X-mode and the Bernstein wave in the mode conversion problems without absorption have been obtained, and the connection formulas between different wave branches have been established. The corresponding transmission, reflection and conversion coefficients have also been given. Mode conversion problem at any harmonic has been generalized to either a three branch or a five branch problem. A comparison between the coupled equation and the uncoupled equation has been made. The effort has been directed at the third harmonic since the adsorption at ω = 2ω ce is known to be very strong in virtually every fusion case. Both the low density limit and the high density limit cases have been studied separately. The relativistic effects on the mode conversion and absorption problem has been analyzed. The mode conversion equation with absorption has been solved by using the Green function method. The electron cyclotron emission experiments have already begun at 3ω ce , and the third harmonic is the first nontrivial case of importance

  13. The Impact of Iron Adsorption on the Electronic and Photocatalytic Properties of the Zinc Oxide (0001 Surface: A First-Principles Study

    Directory of Open Access Journals (Sweden)

    Jingsi Cheng

    2018-03-01

    Full Text Available The structural stability, electronic structure, and optical properties of an iron-adsorbed ZnO (0001 surface with three high-symmetry adsorption sites are investigated with first-principle calculations on the basis of density functional theory and the Hubbard-U method. It is found that the iron adatom in the H3 adsorption site of ZnO (0001 surface has the lowest adsorption energy of −5.665 eV compared with T4 and Top sites. For the Top site, compared with the pristine ZnO (0001 surface, the absorption peak located at 1.17 eV has a red shift, and the elevation of the absorption coefficient is more pronounced in the visible-light region, because the Fe-related levels are introduced in the forbidden band and near the Fermi level. The electrostatic potential computation reveals that the work function of the ZnO (0001 surface is significantly decreased from 2.340 to 1.768 eV when iron is adsorbed on the Top site. Furthermore, the degradation mechanism based on the band structure is analyzed. It can be concluded that the adsorption of iron will promote the separation of photoinduced carriers, thus improving the photocatalytic activity of ZnO (0001 surface. Our study benefits research on the photocatalytic activity of ZnO and the utilization rate of solar energy.

  14. The Impact of Iron Adsorption on the Electronic and Photocatalytic Properties of the Zinc Oxide (0001) Surface: A First-Principles Study.

    Science.gov (United States)

    Cheng, Jingsi; Wang, Ping; Hua, Chao; Yang, Yintang; Zhang, Zhiyong

    2018-03-12

    The structural stability, electronic structure, and optical properties of an iron-adsorbed ZnO (0001) surface with three high-symmetry adsorption sites are investigated with first-principle calculations on the basis of density functional theory and the Hubbard-U method. It is found that the iron adatom in the H₃ adsorption site of ZnO (0001) surface has the lowest adsorption energy of -5.665 eV compared with T₄ and Top sites. For the Top site, compared with the pristine ZnO (0001) surface, the absorption peak located at 1.17 eV has a red shift, and the elevation of the absorption coefficient is more pronounced in the visible-light region, because the Fe-related levels are introduced in the forbidden band and near the Fermi level. The electrostatic potential computation reveals that the work function of the ZnO (0001) surface is significantly decreased from 2.340 to 1.768 eV when iron is adsorbed on the Top site. Furthermore, the degradation mechanism based on the band structure is analyzed. It can be concluded that the adsorption of iron will promote the separation of photoinduced carriers, thus improving the photocatalytic activity of ZnO (0001) surface. Our study benefits research on the photocatalytic activity of ZnO and the utilization rate of solar energy.

  15. Non-uniform absorption of terahertz radiation on superconducting hot electron bolometer microbridges

    International Nuclear Information System (INIS)

    Miao, W.; Zhang, W.; Zhong, J. Q.; Shi, S. C.; Delorme, Y.; Lefevre, R.; Feret, A.; Vacelet, T.

    2014-01-01

    We interpret the experimental observation of a frequency-dependence of superconducting hot electron bolometer (HEB) mixers by taking into account the non-uniform absorption of the terahertz radiation on the superconducting HEB microbridge. The radiation absorption is assumed to be proportional to the local surface resistance of the HEB microbridge, which is computed using the Mattis-Bardeen theory. With this assumption the dc and mixing characteristics of a superconducting niobium-nitride (NbN) HEB device have been modeled at frequencies below and above the equilibrium gap frequency of the NbN film

  16. Transmission electron microscope study of fusion-environment radiation damage in iron and iron-chromium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Horton, L.L.S.

    1982-07-01

    A transmission electron microscopy study of radiation damage microstructures in iron and iron-chromium alloys has been performed. This study consisted of both qualitative and quantitative characterization of the dislocation and cavity microstructures, including determination of vacancy/interstitial character and Burgers vectors for dislocation loops and analysis of the cavity morphology. The effects of irradiation temperature, fluence, helium implantation, and chromium content were investigated. Neutron irradiation (iron specimens, 1 dpa, 455 to 1000 K) and triple-beam ion irradiation (Fe-10% Cr specimens, 10 dpa, 725 to 950 K; Fe-10% Cr specimens, 850 K, 0.3 to 100 dpa; and Fe, Fe-5% Cr, Fe-10% Cr specimens, 850 K, 10 dpa) were employed. In the triple-beam ion irradiation procedure, simultaneous bombardment with 4 MeV Fe/sup + +/ ions and energetic He/sup +/ and D/sub 2//sup +/ ions was used to simulate the fusion environment (10 at. ppM He/dpa and 41 at. ppM D/dpa). In addition, single-beam 4 MeV Fe/sup + +/ ion irradiations of Fe-10% Cr both with and without pre-injection of helium and deuterium were performed.

  17. Transmission electron microscope study of fusion-environment radiation damage in iron and iron-chromium alloys

    International Nuclear Information System (INIS)

    Horton, L.L.S.

    1982-07-01

    A transmission electron microscopy study of radiation damage microstructures in iron and iron-chromium alloys has been performed. This study consisted of both qualitative and quantitative characterization of the dislocation and cavity microstructures, including determination of vacancy/interstitial character and Burgers vectors for dislocation loops and analysis of the cavity morphology. The effects of irradiation temperature, fluence, helium implantation, and chromium content were investigated. Neutron irradiation (iron specimens, 1 dpa, 455 to 1000 K) and triple-beam ion irradiation (Fe-10% Cr specimens, 10 dpa, 725 to 950 K; Fe-10% Cr specimens, 850 K, 0.3 to 100 dpa; and Fe, Fe-5% Cr, Fe-10% Cr specimens, 850 K, 10 dpa) were employed. In the triple-beam ion irradiation procedure, simultaneous bombardment with 4 MeV Fe ++ ions and energetic He + and D 2 + ions was used to simulate the fusion environment (10 at. ppM He/dpa and 41 at. ppM D/dpa). In addition, single-beam 4 MeV Fe ++ ion irradiations of Fe-10% Cr both with and without pre-injection of helium and deuterium were performed

  18. X-ray absorption spectroscopy of soybean lipoxygenase-1 : Influence of lipid hydroperoxide activation and lyophilization on the structure of the non-heme iron active site

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Heijdt, L.M. van der; Feiters, M.C.; Navaratnam, S.; Nolting, H.-F.; Hermes, C.; Veldink, G.A.

    1992-01-01

    X-ray absorption spectra at the Fe K-edge of the non-heme iron site in Fe(II) as well as Fe(III) soybean lipoxygenase-1, in frozen solution or lyophilized, are presented; the latter spectra were obtained by incubation of the Fe(II) enzyme with its product hydroperoxide. An edge shift of about 23 eV

  19. Iron

    Science.gov (United States)

    ... Share: Search the ODS website Submit Search NIH Office of Dietary Supplements Consumer Datos en español Health ... eating a variety of foods, including the following: Lean meat, seafood, and poultry. Iron-fortified breakfast cereals ...

  20. Experimental observation of microwave absorption and electron heating due to the two plasmon decay instability and resonance absorption

    International Nuclear Information System (INIS)

    Rasmussen, D.A.

    1981-01-01

    The interaction of intense microwaves with an inhomogeneous plasma is studied in two experimental devices. In the first device an investigation was made of microwave absorption and electron heating due to the parametric decay of microwaves into electron plasma waves (Two Plasmon Decay instability, TPDI), modeling a process which can occur near the quarter critical surface in laser driven pellets. P-polarized microwave (f = 1.2 GHz, P 0 less than or equal to 12 kW) are applied to an essentially collisionless, inhomogeneous plasma, in an oversized waveguide, in the U.C. Davis Prometheus III device. The initial density scale length near the quarter critical surface is quite long (L/lambda/sub De/ approx. = 3000 or k 0 L approx. = 15). The observed threshold power for the TPDI is quite low (P/sub T/approx. = 0.1 kW or v/sub os//v/sub e/ approx. = 0.1). Near the threshold the decay waves only occur near the quarter critical surface. As the incident power is increased above threshold, the decay waves spread to lower densities, and for P 0 greater than or equal to lkW, (v/sub os//v/sub e/ greater than or equal to 0.3) suprathermal electron heating is strong for high powers (T/sub H/ less than or equal to 12 T/sub e/ for P 0 less than or equal to 8 kW or v/sub os//v/sub e/ less than or equal to 0.9)

  1. Effect of capping ligands on the optical properties and electronic energies of iron pyrite FeS{sub 2} nanocrystals and solid thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Guangmei, E-mail: zhaiguangmei@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education of the People' s Republic of China, Research Centre of Advanced Materials Science and Technology of Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Jiangsu Key Laboratory for Solar Cell Materials and Technology, Changzhou University, Changzhou, Jiangsu 213164 (China); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Xie, Rongwei; Wang, Heng; Zhang, Jitao; Yang, Yongzhen; Wang, Hua; Li, Xuemin [Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education of the People' s Republic of China, Research Centre of Advanced Materials Science and Technology of Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Liu, Xuguang [Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education of the People' s Republic of China, Research Centre of Advanced Materials Science and Technology of Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Xu, Bingshe [Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education of the People' s Republic of China, Research Centre of Advanced Materials Science and Technology of Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China)

    2016-07-25

    In this work, the optical and electronic properties of iron pyrite FeS{sub 2} nanocrystals and solid thin films with various capping ligands were systematically investigated by UV–Vis–NIR absorption spectroscopy, cyclic voltammetry and current density–voltage characteristic measurements. The iron pyrite nanocrystals with various ligands have an indirect band gap of around 1.05 eV and broad absorption spanning into the near-infrared region, exhibiting favorable optical properties for their photovoltaic applications. The electron affinities and ionization potentials of FeS{sub 2} nanocrystals determined through cyclic voltammetry measurements show strong ligand dependence. An energy level shift of up to 190 meV was obtained among the pyrite nanocrystals capped with the ligands employed in this work. The iron pyrite nanocrystal films capped with iodide and 1,2-ethanedithiol exhibit the largest band edge energy shift and conductivity, respectively. Our results not only provide several useful optical and electronic parameters of pyrite nanocrystals for their further use in optoelectronic devices as active layers and/or infrared optical absorption materials, but also highlight the relationship between their surface chemistry and electronic energies. - Highlights: • The energy levels of FeS{sub 2} nanocrystals with various ligands were determined via electrochemical measurements. • The energy levels of FeS{sub 2} nanocrystals showed strong ligand-dependence. • An energy level shift of up to 190 meV was obtained for the pyrite nanocrystals studied in the work. • The conductivities of FeS{sub 2} nanocrystals with different ligands were obtained by current density–voltage measurements.

  2. Effect of capping ligands on the optical properties and electronic energies of iron pyrite FeS2 nanocrystals and solid thin films

    International Nuclear Information System (INIS)

    Zhai, Guangmei; Xie, Rongwei; Wang, Heng; Zhang, Jitao; Yang, Yongzhen; Wang, Hua; Li, Xuemin; Liu, Xuguang; Xu, Bingshe

    2016-01-01

    In this work, the optical and electronic properties of iron pyrite FeS 2 nanocrystals and solid thin films with various capping ligands were systematically investigated by UV–Vis–NIR absorption spectroscopy, cyclic voltammetry and current density–voltage characteristic measurements. The iron pyrite nanocrystals with various ligands have an indirect band gap of around 1.05 eV and broad absorption spanning into the near-infrared region, exhibiting favorable optical properties for their photovoltaic applications. The electron affinities and ionization potentials of FeS 2 nanocrystals determined through cyclic voltammetry measurements show strong ligand dependence. An energy level shift of up to 190 meV was obtained among the pyrite nanocrystals capped with the ligands employed in this work. The iron pyrite nanocrystal films capped with iodide and 1,2-ethanedithiol exhibit the largest band edge energy shift and conductivity, respectively. Our results not only provide several useful optical and electronic parameters of pyrite nanocrystals for their further use in optoelectronic devices as active layers and/or infrared optical absorption materials, but also highlight the relationship between their surface chemistry and electronic energies. - Highlights: • The energy levels of FeS 2 nanocrystals with various ligands were determined via electrochemical measurements. • The energy levels of FeS 2 nanocrystals showed strong ligand-dependence. • An energy level shift of up to 190 meV was obtained for the pyrite nanocrystals studied in the work. • The conductivities of FeS 2 nanocrystals with different ligands were obtained by current density–voltage measurements.

  3. Absorption and translocation of 59Fe and 14C-rhodotorulate in iron-stressed tomato

    International Nuclear Information System (INIS)

    Miller, G.W.; Shigematsu, A.; Motoji, N.; Shibabe, S.

    1990-01-01

    Tomato plants, cultivars FER and Earlygirl (both iron efficient and able to use rhodotorulate- 59 Fe), were grown under low Fe conditions for 9 days. Rhodotorulate- 14 C, isolated from Rhodotorula pilimanae cultured with 14 C-sucrose, and rhodotorulate- 59 Fe were added to the Fe-stressed plants for 6-, 24- or 48-h periods. It was evident from autoradiograms and tissue sampling that 59 Fe and 14 C were abundant in roots, stems and leaves. The 14 C autoradiograms showed especially high density in the small, younger leaves, as was found also with 59 Fe. Unlike synthetic chelates, rhodotorulate (or metabolised derivatives) was readily absorbed by the roots and translocated to the leaves. (author)

  4. Antiferroic electronic structure in the nonmagnetic superconducting state of the iron-based superconductors.

    Science.gov (United States)

    Shimojima, Takahiro; Malaeb, Walid; Nakamura, Asuka; Kondo, Takeshi; Kihou, Kunihiro; Lee, Chul-Ho; Iyo, Akira; Eisaki, Hiroshi; Ishida, Shigeyuki; Nakajima, Masamichi; Uchida, Shin-Ichi; Ohgushi, Kenya; Ishizaka, Kyoko; Shin, Shik

    2017-08-01

    A major problem in the field of high-transition temperature ( T c ) superconductivity is the identification of the electronic instabilities near superconductivity. It is known that the iron-based superconductors exhibit antiferromagnetic order, which competes with the superconductivity. However, in the nonmagnetic state, there are many aspects of the electronic instabilities that remain unclarified, as represented by the orbital instability and several in-plane anisotropic physical properties. We report a new aspect of the electronic state of the optimally doped iron-based superconductors by using high-energy resolution angle-resolved photoemission spectroscopy. We find spectral evidence for the folded electronic structure suggestive of an antiferroic electronic instability, coexisting with the superconductivity in the nonmagnetic state of Ba 1- x K x Fe 2 As 2 . We further establish a phase diagram showing that the antiferroic electronic structure persists in a large portion of the nonmagnetic phase covering the superconducting dome. These results motivate consideration of a key unknown electronic instability, which is necessary for the achievement of high- T c superconductivity in the iron-based superconductors.

  5. Alcohol-catalyzed photoreduction of iron-porphyrin complexes revealed by resonance raman and absorption spectroscopies

    Science.gov (United States)

    Ogura, T.; Fidler, V.; Ozaki, Y.; Kitagawa, T.

    1990-06-01

    Photoreduction of Fe III(OEP) (2-MeIm) (OEP is octaethylporphyrin; 2-MeIm is 2-methylimidazole) was found to be catalyzed by a trace amount of MeOH present in Ch 2Cl 2 as a stabilizer. The absence of either 2-MeIm or MeOH in the CH 2Cl 2 solution of Fe III(OEP) X (X is Cl -, Br - or I -) leads to no photoreduction. The presence of MeOH in the Fe III(OEP) (2-MeIm) solution results in the appearance of a new absorption band at 585 nm, and when Raman scattering was excited at 590 nm, a new Raman band appeared at 524 cm -. This band exhibited an upshift by 4 cm - with 54Fe(OEP) (2-MeIm)(CH 3OH) and a downshift by 12 cm -1 with 56Fe(OEP)(2-MeIm) (CD 3OD) and was therefore assigned to the Fe III-MeOH stretching vibration. The excitation profile of this band gave a peak around 585 nm and accordingly, the new absorption band at 584 nm was assigned to a charge-transfer (CT) band from MeOH to the Fe III ion. It was most unexpected that the photoreduction did not occur upon laser illumination within the CT band.

  6. Photoelectron and UV absorption spectroscopy for determination of electronic configurations of negative molecular ions: Chlorophenols

    International Nuclear Information System (INIS)

    Tseplin, E.E.; Tseplina, S.N.; Tuimedov, G.M.; Khvostenko, O.G.

    2009-01-01

    The photoelectron and UV absorption spectra of p-, m-, and o-chlorophenols in the gas phase have been obtained. On the basis of DFT B3LYP/6-311++G(d, p) calculations, the photoelectron bands have been assigned to occupied molecular orbitals. From the TDDFT B3LYP/6-311++G(d, p) calculation results, the UV absorption bands have been assigned to excited singlet states of the molecules under investigation. For each excited state a dominant transition was found. It has been shown that the energies of these singlet transitions correlate with the energy differences between the ground-state molecular orbitals participating in them. Using the UV spectra interpretation, the electronic states of molecular anions detected earlier for the same compounds by means of the resonant electron capture mass-spectrometry have been determined.

  7. Wall effects on the absorption of electron cyclotron waves in an EBT plasma

    International Nuclear Information System (INIS)

    Uckan, T.

    1979-03-01

    The absorption of electron cyclotron waves propagating along an externally applied magnetic field in a uniform plasma surrounded by a cylindrical metallic cavity wall is studied. In the model, the cavity wall, the vacuum-plasma interface, and the effects of finite electron temperature are considered, and the dispersion relation for the wave propagation is derived. The results are then applied to the ELMO Bumpy Torus (EBT-I) plasma, and the propagation characteristics are computed. The wave absorption in the ordinary mode is found to be a result of the wall effects, which cannot be predicted with the infinite plasma theory. The loaded quality factor, Q/sub L/, is also estimated from the model to be about 12, which is in good agreement with the experimentally observed value

  8. One electron reduction and absorption characteristics of Cresyl violet in micellar medium

    International Nuclear Information System (INIS)

    Gawandi, Vijay B.; Guha, S.N.; Hari Mohan

    2000-01-01

    Effect of surfactant micelles on absorption characteristics of Cresyl violet (CV) and on its redox reactions have been studied. Among the various surfactants investigated anionic surfactants particularly sodium lauryl sulfate (SLS) and sodium dodecyl benzene sulfonate (SDDBS) showed marked effect on these properties. Reactions of hydrated electron in these micellar media were studied using the technique of nanosecond pulse radiolysis. Results of other surfactants, viz.BSS, CTAB and TritonX-100 have also been presented. (author)

  9. Convenient determination of luminescence quantum yield using a combined electronic absorption and emission spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, John; Mishra, Ashok Kumar [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India)

    2016-01-15

    It is possible to measure luminescence quantum yield in a facile way, by designing an optical spectrometer capable of obtaining electronic absorption as well as luminescence spectra, with a setup that uses the same light source and detector for both the spectral measurements. Employment of a single light source and single detector enables use of the same correction factor profile for spectral corrections. A suitable instrumental scaling factor is used for adjusting spectral losses.

  10. Observation of auto-oscillations and chaos in subsidiary absorption in yttrium iron garnet

    International Nuclear Information System (INIS)

    Srinivasan, G.; Chen, M.; Patton, C.E.

    1988-01-01

    Auto-oscillations of the dynamic magnetization and routes to chaos for the first-order transverse pump spin-wave instability have been studied in single-crystal yttrium-iron-garnet (YIG) films. The measurements reported here were made on a 20.8-μm-thick YIG film at 9.4 GHz with the static and microwave fields in the plane of the film. Auto-oscillations at 100--400 kHz were observed in the power absorbed by the film over a relatively narrow static field range of 1100--1460 Oe, compared to the first-order instability (FOI) range of 0--1630 Oe. The auto-oscillation frequency and threshold microwave field amplitude were both strongly field dependent. The threshold amplitudes were about a factor of 2 larger than the FOI threshold amplitudes. At even higher power levels and for an even narrower field range of 1300--1380 Oe, the auto-oscillations showed frequency changes indicative of chaotic behavior. Several different subharmonic bifurcation routes to chaos were observed for different fields within the chaotic region

  11. Characterization and structural properties of iron in plants.

    Science.gov (United States)

    Dewanamuni, Udya; Dehipawala, Sunil; Gafney, Harry

    Iron is one of the most abundant metals in the soil and occurs in a wide range of chemical forms. Humans receive iron through either meat products or plants. Non meat eaters depend on plant product for their daily iron requirement. The iron absorption by plants depends on other minerals present in the soil and soil pH value. The amount of iron present in plants grown with different soil compositions were investigated using X-ray absorption spectroscopy (XAS) and Mossbauer spectroscopy. Based on the X-ray absorption data, the amount of iron in plants vary significantly with soil pH value. The Mossbauer spectroscopy reveals that iron present in the samples has the form Fe3+ or electron density at the site of the iron nucleus similar to that of Fe3+. CUNY Research Scholar Program, MSEIP.

  12. Effect of nonlinear wave-particle interaction on electron-cyclotron absorption

    Energy Technology Data Exchange (ETDEWEB)

    Tsironis, C; Vlahos, L [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2006-09-15

    We perform a self-consistent analysis of the nonlinear interaction of magnetized plasmas with electron-cyclotron (EC) waves. A closed set of equations is derived, which consists of the relativistic equations of motion under the wave field and the wave equation for the vector potential. The plasma is described in terms of ensembles of electrons which collectively determine the evolution of the wave amplitude and frequency through the current response. This description allows for effects of the electron motions on the efficiency of the wave absorption, for example, the asynchrony between the wave phase and the gyroperiod. As an application, we study the absorption of an EC wave beam in a simplified tokamak geometry, for plasma parameters relevant to current and future fusion experiments. We conclude that, within the limits of our model, there are cases where the linear theory for the absorption of EC waves, used widely in the current literature, may overestimate the energy deposition. In such cases, nonlinear effects are essential for the accurate estimation of the plasma-wave coupling and their inclusion should be considered, especially when the wave power is dramatically increased as in the case of ITER.

  13. Effect of nonlinear wave-particle interaction on electron-cyclotron absorption

    International Nuclear Information System (INIS)

    Tsironis, C; Vlahos, L

    2006-01-01

    We perform a self-consistent analysis of the nonlinear interaction of magnetized plasmas with electron-cyclotron (EC) waves. A closed set of equations is derived, which consists of the relativistic equations of motion under the wave field and the wave equation for the vector potential. The plasma is described in terms of ensembles of electrons which collectively determine the evolution of the wave amplitude and frequency through the current response. This description allows for effects of the electron motions on the efficiency of the wave absorption, for example, the asynchrony between the wave phase and the gyroperiod. As an application, we study the absorption of an EC wave beam in a simplified tokamak geometry, for plasma parameters relevant to current and future fusion experiments. We conclude that, within the limits of our model, there are cases where the linear theory for the absorption of EC waves, used widely in the current literature, may overestimate the energy deposition. In such cases, nonlinear effects are essential for the accurate estimation of the plasma-wave coupling and their inclusion should be considered, especially when the wave power is dramatically increased as in the case of ITER

  14. Calculation of Vibrational and Electronic Excited-State Absorption Spectra of Arsenic-Water Complexes Using Density Functional Theory

    Science.gov (United States)

    2016-06-03

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6390--16-9681 Calculation of Vibrational and Electronic Excited -State Absorption Spectra...NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Calculation of Vibrational and Electronic Excited -State Absorption Spectra of Arsenic-Water Complexes Using...Unclassified Unlimited Unclassified Unlimited 59 Samuel G. Lambrakos (202) 767-2601 Calculations are presented of vibrational and electronic excited -state

  15. Electronic structure analysis of UO2 by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Ozkendir, O.M.

    2009-01-01

    Full text: Due to the essential role of Actinides in nuclear science and technology, electronic and structural investigations of actinide compounds attract major interest in science. Electronic structure of actinide compounds have important properties due to narrow 5f states which play key role in bonding with anions. The properties of Uranium has been a subject of enduring interest due to its being a major importance as a nuclear fuel and is the highest numbered element which can be found naturally on earth. UO 2 forms as a secondary uranyl group occurred during metamictization of uranium oxide compounds [1].Uranium oxide thin films have been investigated by X-ray Absorption Fine Structure spectroscopy (XAFS) [2]. The full multiple scattering approach has been applied to the calculation of U L3 edge spectra of UO 2 . The calculations are based on different choices of one electron potentials according to Uranium coordinations by using the real space multiple scattering method FEFF 8.2 code [3,4]. U L3-edge absorption spectrum in UO 2 is compared with U L3-edges in USiO 4 and UTe which are chosen due to their different electronic and chemical structures.We have found prominent changes in the XANES spectra of Uranium oxide thin films due to valency properties. Such observed changes are explained by considering the structural, electronic and spectroscopic properties. (author)

  16. Experimental investigation on electron cyclotron absorption at down-shifted frequency in the PLT tokamak

    International Nuclear Information System (INIS)

    Mazzucato, E.; Fidone, I.; Cavallo, A.; von Goeler, S.; Hsuan, H.

    1986-05-01

    The absorption of 60 GHz electron cyclotron waves, with the extraordinary mode and an oblique angle of propagation, has been investigated in the PLT tokamak in the regime of down-shifted frequencies. The production of energetic electrons, with energies of up to 300 to 400 keV, peaks at values of toroidal field (approx. =29 kG) for which the wave frequency is significantly smaller than the electron cyclotron frequency in the whole plasma region. The observations are consistent with the predictions of the relativistic theory of electron cyclotron damping at down-shifted frequency. Existing rf sources make this process a viable method for assisting the current ramp-up, and for heating the plasma of present large tokamaks

  17. Studies on solvatochromic behavior of some monoazo derivatives using electronic absorption spectra

    Energy Technology Data Exchange (ETDEWEB)

    Sidir, Isa; Tasal, Erol; Guelseven, Yadigar [Department of Physics, Faculty of Arts and Sciences, Eskisehir Osmangazi University, 26480 Eskisehir (Turkey); Guengoer, Tayyar [Department of Physics, Faculty of Arts and Sciences, Akdeniz University, Antalya (Turkey); Berber, Halil [Department of Chemistry, Faculty of Sciences, Anadolu University, Eskisehir (Turkey); Oegretir, Cemil [Department of Chemistry, Faculty of Arts and Sciences, Eskisehir Osmangazi University, Eskisehir (Turkey)

    2009-06-15

    The electronic absorption spectra of 2',4'-dihydroxy-2-methoxyazobenzene and 4,2',4'-trihydroxyazobenzene molecules have been investigated in solvents with different polarities. The solvent dependent UV-vis spectral shifts, {nu}{sub max}, were analysed using some physical parameters such as refractive index, dielectric constant, Kamlet-Taft parameters, {alpha} (hydrogen bond donating ability) and {beta} (hydrogen bond accepting ability). The electronic transitions are assigned and the solvent induced spectral shifts have been analysed in relation to different solute-solvent interaction mechanisms using linear regression analysis. The results of fitting coefficients obtained from the analysis helped us to estimate the contribution of each type of interaction to the spectral shift in the molecule under consideration. It is concluded that the electronic character of the chemical nature of the solvent and the electronic character of substituents are the important factor for the observed solvatochromism. (author)

  18. Electronic topological transition in zinc under pressure: An x-ray absorption spectroscopy study

    International Nuclear Information System (INIS)

    Aquilanti, G.; Trapananti, A.; Pascarelli, S.; Minicucci, M.; Principi, E.; Liscio, F.; Twarog, A.

    2007-01-01

    Zinc metal has been studied at high pressure using x-ray absorption spectroscopy. In order to investigate the role of the different degrees of hydrostaticity on the occurrence of structural anomalies following the electronic topological transition, two pressure transmitting media have been used. Results show that the electronic topological transition, if it exists, does not induce an anomaly in the local environment of compressed Zn as a function of hydrostatic pressure and any anomaly must be related to a loss of hydrostaticity of the pressure transmitting medium. The near-edge structures of the spectra, sensitive to variations in the electronic density of states above the Fermi level, do not show any evidence of electronic transition whatever pressure transmitting medium is used

  19. Electron impact excitation of the iron peak element Fe II

    International Nuclear Information System (INIS)

    Ramsbottom, C.A.; Scott, M.P.; Bell, K.L.; McLaughlin, B.M.; Burke, P.G.; Keenan, F.P.; Sunderland, A.G.; Burke, V.M.; Noble, C.J.

    2002-01-01

    Effective collision strengths for electron-impact excitation of Fe II are presented for all sextet-to-quartet transitions among the 38 LS states formed from the basis configurations 3d 6 4s, 3d 7 and 3d 6 4p. A total of 112 individual transitions are considered at electron temperatures in the range 30-100,000 K, encompassing values of importance for applications in astrophysics as well as laboratory plasmas. A limited comparison is made with earlier theoretical work and large differences are found to occur at the temperatures considered. In particular, it is found that the inclusion or omission of some (N+1)-bound configurations in the Hamiltonian matrices describing the collision process can have a huge effect on the resulting effective collision strengths, by up to a factor of four in some cases. (author)

  20. Monte Carlo simulations of the detailed iron absorption line profiles from thermal winds in X-ray binaries

    Science.gov (United States)

    Tomaru, Ryota; Done, Chris; Odaka, Hirokazu; Watanabe, Shin; Takahashi, Tadayuki

    2018-05-01

    Blueshifted absorption lines from highly ionized iron are seen in some high inclination X-ray binary systems, indicating the presence of an equatorial disc wind. This launch mechanism is under debate, but thermal driving should be ubiquitous. X-ray irradiation from the central source heats disc surface, forming a wind from the outer disc where the local escape velocity is lower than the sound speed. The mass-loss rate from each part of the disc is determined by the luminosity and spectral shape of the central source. We use these together with an assumed density and velocity structure of the wind to predict the column density and ionization state, then combine this with a Monte Carlo radiation transfer to predict the detailed shape of the absorption (and emission) line profiles. We test this on the persistent wind seen in the bright neutron star binary GX 13+1, with luminosity L/LEdd ˜ 0.5. We approximately include the effect of radiation pressure because of high luminosity, and compute line features. We compare these to the highest resolution data, the Chandra third-order grating spectra, which we show here for the first time. This is the first physical model for the wind in this system, and it succeeds in reproducing many of the features seen in the data, showing that the wind in GX13+1 is most likely a thermal-radiation driven wind. This approach, combined with better streamline structures derived from full radiation hydrodynamic simulations, will allow future calorimeter data to explore the detail wind structure.

  1. Substituent effects on geometric and electronic properties of iron tetraphenylporphyrin: a DFT investigation.

    Science.gov (United States)

    Wei, Lu; She, Yuanbin; Yu, Yanmin; Yao, Xiaoqian; Zhang, Suojiang

    2012-06-01

    To investigate the effects of the substituents, substituent positions and axial chloride ligand on the geometric and electronic properties of the iron tetraphenylporphyrin (FeTPP), a series of the substituented iron tetraphenylporphyrins and their chlorides, FeT(o/p-R)PP and FeT(o/p-R)PPCl (R = -H, -Cl, -NO(2), -OH, -OCH(3)), were systematically calculated without any symmetry constraint by using DFT method. For geometric structure, the substituent position and axial Cl ligand change the configuration of the iron porphyrin obviously. The ortho-substituents prefer making the phenyls perpendicular to the porphyrin ring; the axial chloride draws the central Fe ion ~0.500 Å out of the porphyrin plane toward the ligand. With regard to electronic properties, it is found that E(LUMO) could be related to the catalytic activity. The electron-withdrawing group always lowers the energies of both frontier orbitals, while the electron-donating one heightens them simultaneously, but they affect the E(HOMO) and E(LUMO) in the same sequence, -NO(2) < -Cl < -H < -OH < -OCH(3). The substituent effects on the central Fe ion were explored by calculating NBO charge distribution, spin density and natural electron configuration.

  2. Isolation of acetogenic bacteria that induce biocorrosion by utilizing metallic iron as the sole electron donor.

    Science.gov (United States)

    Kato, Souichiro; Yumoto, Isao; Kamagata, Yoichi

    2015-01-01

    Corrosion of iron occurring under anoxic conditions, which is termed microbiologically influenced corrosion (MIC) or biocorrosion, is mostly caused by microbial activities. Microbial activity that enhances corrosion via uptake of electrons from metallic iron [Fe(0)] has been regarded as one of the major causative factors. In addition to sulfate-reducing bacteria and methanogenic archaea in marine environments, acetogenic bacteria in freshwater environments have recently been suggested to cause MIC under anoxic conditions. However, no microorganisms that perform acetogenesis-dependent MIC have been isolated or had their MIC-inducing mechanisms characterized. Here, we enriched and isolated acetogenic bacteria that induce iron corrosion by utilizing Fe(0) as the sole electron donor under freshwater, sulfate-free, and anoxic conditions. The enriched communities produced significantly larger amounts of Fe(II) than the abiotic controls and produced acetate coupled with Fe(0) oxidation prior to CH4 production. Microbial community analysis revealed that Sporomusa sp. and Desulfovibrio sp. dominated in the enrichments. Strain GT1, which is closely related to the acetogen Sporomusa sphaeroides, was eventually isolated from the enrichment. Strain GT1 grew acetogenetically with Fe(0) as the sole electron donor and enhanced iron corrosion, which is the first demonstration of MIC mediated by a pure culture of an acetogen. Other well-known acetogenic bacteria, including Sporomusa ovata and Acetobacterium spp., did not grow well on Fe(0). These results indicate that very few species of acetogens have specific mechanisms to efficiently utilize cathodic electrons derived from Fe(0) oxidation and induce iron corrosion. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  3. Comparison between experimental and predicted specific absorption rate of functionalized iron oxide nanoparticle suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Yuan [Mechanical, Aerospace and Nuclear Engineering Department Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Tasciuc, Diana-Andra Borca, E-mail: borcad@rpi.edu [Mechanical, Aerospace and Nuclear Engineering Department Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2011-10-15

    Radio-frequency heated magnetic nanoaparticle suspensions have potential applications in cancer hyperthermia. To optimize these systems for hyperthermia applications it is important to be able to predict how their heat generation or specific absorption rate (SAR) is influenced by various factors, including nanoparticle coating or functionalization and aggregation. However, at present it is unclear how well-existing models predict experimental SAR results. Direct comparisons between predicted and measured SAR are scarce, despite an abundance of works reporting on heat generation rate of various magnetic nanoparticles suspensions. The main objective of this paper is to experimentally assess the validity of current models for SAR and extract information on the effects of coating and aggregation on heat generation rate. In this context, AC susceptibility and magnetization of suspensions of uncoated particles, as well as particles with aminosilane and carboxymethyl-dextran functionalizations, were measured. These properties were then used to predict the heat generation rate in alternating magnetic field starting from first principles, which was then compared to measured SAR. It was found that experimental SAR agrees relatively well with predictions (by a factor of two) when using experimental susceptibility values for the SAR calculation. However, for uncoated and amine-functionalized particles poor agreement (more than an order of magnitude difference) was found when the experimental susceptibility was substituted with predictions based on the Debye model. This apparent discrepancy is attributed to dipolar interactions between nanoparticles within aggregates in these samples, which enhances the imaginary part of the susceptibility and, consequently, the SAR values. The results also suggest that the thermal resistance effect of the coating has little influence on the SAR. - Highlights: > Thermal resistance of nanoparticle coating has little impact on heat dissipation

  4. Determination of caesium in river and sea waters by electrothermal atomic-absorption spectrometry. Interference of cobalt and iron

    International Nuclear Information System (INIS)

    Frigieri, P.; Trucco, R.; Ciaccolini, I.; Pampurini, G.

    1980-01-01

    For the enrichment or the simple recovery of caesium from river and sea waters, selective inorganic exchangers were considered. Ammonium hexacyanocobalt ferrate (NCFC) was chosen because it can be used in strongly acidic solutions (with the exception of concentrated sulphuric acid). Caesium is fully retained by the NCFC chromatographic column and can then be recovered by dissolution in hot sulphuric acid. The solution is then diluted and analysed, either directly or following caesium separation, by atomic-absorption spectrometry. To check the reliability of the analytical procedure, a series of experiments were carried out in which the possible interfering species were added to the aqueous caesium solution prior to analysis. The well known ionic interference in flame atomisation processes caused by magnesium, calcium, strontium and metals was investigated by electrothermal atomisation measurements. The experimental data showed that this effect does not occur even when these elements are present in concentrations of the order of thousands of parts per million. However, strong interferences from iron and cobalt were observed. (author)

  5. Study of radiation-thermal effect of electron beam on steel and cast iron

    International Nuclear Information System (INIS)

    Machurin, E.S.; Lonchin, G.M.

    1980-01-01

    Studied is the influence of radiation-heat treatment by high energy (3-4.5 MeV) electron beam on the structure and properties of carbon steels (65G, 90KhF) and cast iron. Metallography and electron microscopy methods are used to study microstructure. It is shown that after the treatment by the electron beam there is observed noticeable structure grinding, sample fracture viscosity (even in a quenched state), increase of hardness and impact strength. The mechanism of metal heating process by electron beam is calculated and temperature field is defined in a heating region accounting for electron beam characteristics, medium and geometric factor. Theoretical data are close to experimental ones obtained in a course of determining the microhardness of irradiated samples for the cases of electron treatment duration up to 10 s

  6. Galvanomagnetic properties and electronic structure of iron-doped PbTe

    Energy Technology Data Exchange (ETDEWEB)

    Skipetrov, E. P., E-mail: skip@mig.phys.msu.ru [Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Faculty of Materials Science, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Kruleveckaya, O. V.; Skipetrova, L. A. [Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Knotko, A. V. [Faculty of Materials Science, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Slynko, E. I.; Slynko, V. E. [Institute of Materials Science Problems, National Academy of Sciences of Ukraine, Chernivtsy 58001 (Ukraine)

    2015-11-21

    We synthesize an iron-doped PbTe single-crystal ingot and investigate the phase composition and distribution of the iron impurity along the ingot as well as galvanomagnetic properties in weak magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) of Pb{sub 1−y}Fe{sub y}Te alloys. We find microscopic inclusions enriched with iron and regions with a chemical composition close to FeTe in the heavily doped samples, while the iron impurity content in the main phase rises only slightly along the length of the ingot reaching the impurity solubility limit at approximately 0.6 mol. %. Samples from the initial and the middle parts of the ingot are characterized by p-type metal conductivity. An increase of the iron impurity content leads to a decrease in the free hole concentration and to a stabilization of galvanomagnetic parameters due to the pinning of the Fermi level by the iron resonant impurity level E{sub Fe} lying under the bottom of the valence band (E{sub v} − E{sub Fe} ≈ 16 meV). In the samples from the end of the ingot, a p-n inversion of the conductivity type and an increase of the free electron concentration along the ingot are revealed despite the impurity solubility limit being reached. The kinetics of changes of charge carrier concentration and of the Fermi energy along the ingot is analyzed in the framework of the six-band Dimmock dispersion relation. A model is proposed for the electronic structure rearrangement of Pb{sub 1−y}Fe{sub y}Te with doping, which may also be used for PbTe doped with other transition metals.

  7. Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

    Energy Technology Data Exchange (ETDEWEB)

    Isomura, Noritake, E-mail: isomura@mosk.tytlabs.co.jp [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Soejima, Narumasa; Iwasaki, Shiro [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Nomoto, Toyokazu; Murai, Takaaki [Aichi Synchrotron Radiation Center (AichiSR), 250-3 Minamiyamaguchi-cho, Seto, Aichi 489-0965 (Japan); Kimoto, Yasuji [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

    2015-11-15

    Graphical abstract: - Highlights: • A unique XAS method is proposed for depth profiling of chemical states. • PEY mode detecting energy-loss electrons enables a variation in the probe depth. • Si K-edge XAS spectra of the Si{sub 3}N{sub 4}/SiO{sub 2}/Si multilayer films have been investigated. • Deeper information was obtained in the spectra measured at larger energy loss. • Probe depth could be changed by the selection of the energy of detected electrons. - Abstract: A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si{sub 3}N{sub 4}/SiO{sub 2}/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

  8. Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

    International Nuclear Information System (INIS)

    Isomura, Noritake; Soejima, Narumasa; Iwasaki, Shiro; Nomoto, Toyokazu; Murai, Takaaki; Kimoto, Yasuji

    2015-01-01

    Graphical abstract: - Highlights: • A unique XAS method is proposed for depth profiling of chemical states. • PEY mode detecting energy-loss electrons enables a variation in the probe depth. • Si K-edge XAS spectra of the Si_3N_4/SiO_2/Si multilayer films have been investigated. • Deeper information was obtained in the spectra measured at larger energy loss. • Probe depth could be changed by the selection of the energy of detected electrons. - Abstract: A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si_3N_4/SiO_2/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

  9. Absorption of iron in the aged; investigation of mucosal-uptake, mucosal-transfer and retention of a physiological dose of inorganic iron

    International Nuclear Information System (INIS)

    Marx, J.J.M.

    1976-01-01

    Iron (II) and iron (III) uptake by the mucosal cells, the retention in the body, and the mucosal-transport fraction were studied in 40 healthy people over 65 years old, in 30 young adults and in 20 patients with iron-deficiency. The study was performed with 59 Fe as a tracer and 51 Cr as an inert indicator. The radioactivity was measured with a whole body scanner 24 hours and 24 days after ingestion

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

    Directory of Open Access Journals (Sweden)

    Poirier M.

    2013-11-01

    Full Text Available 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.

  11. Electronic properties of thermally formed thin iron oxide films

    International Nuclear Information System (INIS)

    Wielant, J.; Goossens, V.; Hausbrand, R.; Terryn, H.

    2007-01-01

    The oxide layer, present between an organic coating and the substrate, guarantees adhesion of the coating and plays a determinating role in the delamination rate of the organic coating. The purpose of this study is to compare the resistive and semiconducting properties of thermal oxides formed on steel in two different atmospheres at 250 deg. C: an oxygen rich atmosphere, air, and an oxygen deficient atmosphere, N 2 . In N 2 , a magnetite layer grows while in air a duplex oxide film forms composed by an inner magnetite layer and a thin outer hematite scale. The heat treatment for different amounts of time at high temperature was used as method to sample the thickness variation and change in electronic and semiconducting properties of the thermal oxide layers. Firstly, linear voltammetric measurements were performed to have a first insight in the electrochemical behavior of the thermal oxides in a borate buffer solution. Electrochemical impedance spectroscopy in the same buffer combined with the Mott-Schottky analysis were used to determine the semiconducting properties of the thermal oxides. By spectroscopic ellipsometry (SE) and atomic force microscopy (AFM), respectively, the thickness and roughness of the oxide layers were determined supporting the physical interpretation of the voltammetric and EIS data. These measurements clearly showed that oxide layers with different constitution, oxide resistance, flatband potential and doping concentration can be grown by changing the atmosphere

  12. Electronic structure of some adenosine receptor antagonists. III. Quantitative investigation of the electronic absorption spectra of alkyl xanthines

    Science.gov (United States)

    Moustafa, H.; Shalaby, Samia H.; El-sawy, K. M.; Hilal, Rifaat

    2002-07-01

    Quantitative and comparative investigation of the electronic absorption spectra of theophylline, caffeine and their derivatives is reported. The spectra of theophylline, caffeine and theobromine were compared to establish the predominant tautomeric species in solution. This comparison, analysis of solvent effects and assignments of the observed transitions via MO computations indicate the exits of only one tautomeric species in solution that is the N7 form. A low-lying triplet state was identified which corresponds to a HOMO-LUMO transition. This relatively long-lived T 1 state is always less polar than the ground state and may very well underlie the photochemical reactivity of alkyl xanthines. Substituents of different electron donating or withdrawing strengths and solvent effects are investigated and analyzed. The present analysis is facilitated via computer deconvolution of the observed spectra and MO computation.

  13. Stability, electrochemical behaviors and electronic structures of iron hydroxyl-phosphate

    International Nuclear Information System (INIS)

    Wang Zhongli; Sun Shaorui; Li Fan; Chen Ge; Xia Dingguo; Zhao Ting; Chu Wangsheng; Wu Ziyu

    2010-01-01

    Iron hydroxyl-phosphate with a uniform spherical particle size of around 1 μm, a compound of the type Fe 2-y □ y (PO 4 )(OH) 3-3y (H 2 O) 3y-2 (where □ represents a vacancy), has been synthesized by hydrothermal methods. The particles are composed of spheres of diameter -1 and 120 mAh g -1 at current densities of 170 mA g -1 and 680 mA g -1 , respectively. The stability of crystal structure of this material was studied by TGA and XRD which show that the material remains stable at least up to the temperature 200 deg. C. Investigation of the electronic structure of the iron hydroxyl-phosphate by GGA + U calculation has indicated that it has a better electronic conductivity than LiFePO 4 .

  14. Effect of spin fluctuations on the electronic structure in iron-based superconductors

    Science.gov (United States)

    Heimes, Andreas; Grein, Roland; Eschrig, Matthias

    2012-08-01

    Magnetic inelastic neutron scattering studies of iron-based superconductors reveal a strongly temperature-dependent spin-fluctuation spectrum in the normal conducting state, which develops a prominent low-energy resonance feature when entering the superconducting state. Angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling spectroscopy (STS) allow us to study the fingerprints of fluctuation modes via their interactions with electronic quasiparticles. We calculate such fingerprints in 122 iron pnictides using an experimentally motivated spin-fluctuation spectrum and make a number of predictions that can be tested in ARPES and STS experiments. This includes discussions of the quasiparticle scattering rate and the superconducting order parameter. In quantitative agreement with experiment we reproduce the quasiparticle dispersions obtained from momentum distribution curves as well as energy distribution curves. We discuss the relevance of the coupling between spin fluctuations and electronic excitations for the superconducting mechanism.

  15. Elimination of the inter-element interferences of iron, gold, molybdenum, tin and antimony when determined in organic solvents by flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Aneva, Zara; Arpadjan, Sonja

    1988-01-01

    The mutual interferences in the flame atomic absorption spectrometric determination of iron, gold, molybdenum, tin and antimony after their extraction - pre-concentration as chloride complexes from platinum solutions into isobutyl methyl ketone are investigated. It is suggested that the interferences are caused by chemical reactions in the flame and are influenced by the flame characteristics. The possibility of eliminating the interferences by addition of long-chain quaternary ammonium salts is discussed. (author)

  16. Electronic structure of barium strontium titanate by soft-x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Uehara, Y.; Underwood, J.H.; Gullikson, E.M.; Perera, R.C.C.

    1997-01-01

    Perovskite-type titanates, such as Strontium Titanate (STO), Barium Titanate (BTO), and Lead Titanate (PTO) have been widely studied because they show good electric and optical properties. In recent years, thin films of Barium Strontium Titanate (BST) have been paid much attention as dielectrics of dynamic random access memory (DRAM) capacitors. BST is a better insulator with a higher dielectric constant than STO and can be controlled in a paraelectric phase with an appropriate ratio of Ba/Sr composition, however, few studies have been done on the electronic structure of the material. Studies of the electronic structure of such materials can be beneficial, both for fundamental physics research and for improving technological applications. BTO is a famous ferroelectric material with a tetragonal structure, in which Ti and Ba atoms are slightly displaced from the lattice points. On the other hand, BST keeps a paraelectric phase, which means that the atoms are still at the cubic lattice points. It should be of great interest to see how this difference of the local structure around Ti atoms between BTO and BST effects the electronic structure of these two materials. In this report, the authors present the Ti L 2,3 absorption spectra of STO, BTO, and BST measured with very high accuracy in energy of the absorption features

  17. Electronic structure of barium strontium titanate by soft-x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Uehara, Y. [Mitsubishi Electric Co., Hyogo (Japan); Underwood, J.H.; Gullikson, E.M.; Perera, R.C.C. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    Perovskite-type titanates, such as Strontium Titanate (STO), Barium Titanate (BTO), and Lead Titanate (PTO) have been widely studied because they show good electric and optical properties. In recent years, thin films of Barium Strontium Titanate (BST) have been paid much attention as dielectrics of dynamic random access memory (DRAM) capacitors. BST is a better insulator with a higher dielectric constant than STO and can be controlled in a paraelectric phase with an appropriate ratio of Ba/Sr composition, however, few studies have been done on the electronic structure of the material. Studies of the electronic structure of such materials can be beneficial, both for fundamental physics research and for improving technological applications. BTO is a famous ferroelectric material with a tetragonal structure, in which Ti and Ba atoms are slightly displaced from the lattice points. On the other hand, BST keeps a paraelectric phase, which means that the atoms are still at the cubic lattice points. It should be of great interest to see how this difference of the local structure around Ti atoms between BTO and BST effects the electronic structure of these two materials. In this report, the authors present the Ti L{sub 2,3} absorption spectra of STO, BTO, and BST measured with very high accuracy in energy of the absorption features.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    DeWitt, Jane G. [Stanford Univ., CA (United States)

    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.

  20. Preconcentration and atomic absorption spectrometric determination of cadmium, cobalt, copper, iron, lead, manganese, nickel and zinc in water samples using 6-methyl-2-pyridinecarboxaldehyde-4-phenyl-3-thiosemicarbazone

    International Nuclear Information System (INIS)

    Khuhawar, M.Y.; Das, P.; Dewani, V.K.

    2005-01-01

    The reagent 6-methyl-2-pyridinecarboxaldehyde-4-phenyl-3-thiosemicarbazone (MPAPT) has been examined for the pre-concentration of metal ions and determination using air acetylene flame atomic absorption spectrometer. The method is based on the complexation and extraction of cadmium (II), cobalt(III), copper(II), lead(II), nickel(II), iron(II), iron(II), manganese(II) and zinc(II) in chloroform. The metal iron are back extracted in nitric acid (1:1) or after evaporation of solvent the residue is digested in nitric acid. After necessary adjustment of volume the metal ions were determined in aqueous solution. Pre-concentration is obtained 10-25 times. Metal ions recovery was 95.4-100.8% with coefficient of variation 0.2-7.5%. The method used for the determination of metals in canal and sewerage waters, within 2-6433 mu g/L with C. V 0.-5.2%. (author)

  1. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... deficiency anemia. Proton pump inhibitors interfere with iron absorption, and blood thinners increase the likelihood of bleeding ... oranges, strawberries, and tomatoes, may help increase your absorption of iron. If you are pregnant, talk to ...

  2. Spatial distribution of bremsstrahlung in water and water-iron by 22-MeV electron bombardment measured with activation detectors

    International Nuclear Information System (INIS)

    Nakamura, Takashi; Nishimoto, Takanao; Hirayama, Hideo.

    1977-01-01

    The spatial distributions of bremsstrahlung in water (1 m thick) and water (60 cm thick)-iron (6.3 cm thick) bombarded by 22-MeV electrons were measured by using a new activation method which we developed. These informations are useful for studying shielding, residual activity and radiation damage of accelerator and target materials. From the measured activities, the bremsstrahlung spectra in water were evaluated with the LYRA and the SAND-II unfolding codes. The evaluated spectra were in good agreement with the analytical calculation by the DIBRE code, except for the higher energy ends. The longitudinal and the lateral distributions of bremsstrahlung flux in water were obtained by integrating the evaluated spectra above 8 MeV. The agreement of the experimental and the calculated flux distributions was very good except for a large angle to beam direction. The total photon number crossing a plane normal to the beam axis attenuates exponentially along the axial depth. The iso-flux contour of bremsstrahlung flux was given by interpolating the flux distribution curves. Only the saturated activities of gold detectors were obtained for water-iron in good experimental accuracy. The spatial distribution of gold saturated activities in water-iron clearly shows the attenuating effect due to strong absorption in iron. (auth.)

  3. Wave propagation and absorption in the electron cyclotron frequency range for TCA and TCV machines

    International Nuclear Information System (INIS)

    Cardinali, A.

    1990-01-01

    The main theoretical aspects of the propagation and absorption of electron cyclotron frequency waves are reviewed and applied to TCA and TCV tokamak plasmas. In particular the electromagnetic cold dispersion relation is solved analytically and numerically in order to recall the basic properties of mode propagation and to calculate the ray-trajectories by means of geometric optics. A numerical code which integrates the coupled first order differential ray-equations, has been developed and applied to the cases of interest. (author) 4 figs., 23 refs

  4. Optical absorption and electron spin resonance in natural, irradiated and heated spodumene

    International Nuclear Information System (INIS)

    Ito, A.S.; Isotani, S.

    1983-09-01

    Heat treatment and X and γ-Rays irradiation of lylac and colorless natural spodumene, LiAlSi 2 O 6 , have been studied. Irradiation produces a color change, from lylac or colorless to green. Irradiated samples heated at 200 0 C turn lylac and bleach at 400 0 C. Optical absorption spectra were decomposed into gaussian line shape bands and it is observed that green and lylac centers are simultaneously created by irradiation. These centers are independent from each other. Optical absorption, EPR and X-Ray fluorescence results show the spectra of impurities, responsible by the presence of the created centers and indicated Mn participation in the process of centers creation and destruction. Decay Kinetics of green and lylac centers have been studied and it is observed that simple Kinetic models do not apply to these cases. An empirical fit allowed the calculation of activation energies of the lylac and green centers decays. Discussions about the present results led us to propose a new model where the green and lylac centers are due to Mn 3+ ions in two different Al 3+ sites, whose absorption are intensified by the interaction with an electron trapped in a neighbour oxygen. (Author) [pt

  5. Valence electron structure of cast iron and graphltization behaviour criterion of elements

    Institute of Scientific and Technical Information of China (English)

    刘志林; 李志林; 孙振国; 杨晓平; 陈敏

    1995-01-01

    The valence electron structure of common alloy elements in phases of cast iron is calculated- The relationship between the electron structure of alloy elements and equilibrium, non-equilibrium solidification and graphitization is revealed by defining the bond energy of the strongest bond in a phase as structure formation factor S. A criterion of graphitization behaviour of elements is advanced with the critical value of the structure formation factor of graphite and the n of the strongest covalent bond in cementite. It is found that this theory conforms to practice very well when the criterion is applied to the common alloy elements.

  6. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... drinking black tea, which reduces iron absorption. Other treatments If you have chronic kidney disease and iron- ... and lifestyle changes to avoid complications. Follow your treatment plan Do not stop taking your prescribed iron ...

  7. Electronic structure and optical absorption spectra of Y2 and Zr2 dimers

    International Nuclear Information System (INIS)

    Gutsev, G.L.

    1989-01-01

    The electron structure, ionization potentials from valent levels and energies of optic transitions of Y 2 and Zr 2 dimers are calculated within the framework of discrete-variatin X α -method. It is shown that the symmetry state 1 Σ g + is the main state of Y 2 and Zr 2 dimers, and the atoms in dimers have high-spin 4d n+1 5s 1 configuration. The chemical binding in Y 2 has the dominating 5s-5s nature which is revealed in a considerable interatomic distance; binding of 4d-electrons brings about a significant decrease in the bond length in Zr 2 dimer. The theoretical spectrum of optical absorption of Zr 2 agrees well with the obtained experimental spectrum of this molecule isolated in the organ matrix

  8. The effect of lipids, a lipid-rich ready-to-use therapeutic food, or a phytase on iron absorption from maize-based meals fortified with micronutrient powders.

    Science.gov (United States)

    Monnard, Arnaud; Moretti, Diego; Zeder, Christophe; Steingötter, Andreas; Zimmermann, Michael B

    2017-06-01

    Background: Ready-to-use-therapeutic foods (RUTFs) high in lipid, protein, and iron are used to treat malnutrition. Lipids increase gastric residence time, which could increase iron absorption, particularly from poorly soluble iron compounds and in combination with phytase. Objectives: The objectives were to 1 ) assess the effect on iron absorption of a lipid emulsion given 20 min before or together with an iron-fortified maize meal and 2 ) assess iron absorption from a micronutrient powder (MNP) given with a nutrient-dense RUTF and/or a microbial phytase. Design: A total of 41 women participated in 3 studies. They consumed a maize meal fortified with isotopically labeled ferrous sulfate (FeSO 4 ; study 1) or ferric pyrophosphate (FePP; study 2). In studies 1 and 2, a lipid emulsion was given with or 20 min before the meal. In study 3, with the use of a 2 × 2 factorial design, subjects consumed a maize meal fortified with an MNP containing labeled FeSO 4 (MNP) given with an RUTF (MNP+RUTF), with a phytase (MNP+phytase), or both (MNP+RUTF+phytase). Iron absorption was assessed by isotope incorporation in erythrocytes 14 d after the test meals. Results: The lipid emulsion given either before or with the meal significantly increased iron absorption from FePP by 2.55-fold (95% CI: 1.48-, 4.37-fold; P = 0.001) but not from FeSO 4 There was a trend to increase iron absorption with the MNP+RUTF meal, which did not reach significance (1.21-fold; 95% CI: 0.92-, 1.61-fold; P = 0.060). The addition of phytase to MNP and MNP+RUTF significantly increased iron absorption by 1.85-fold (95% CI: 1.49-, 2.29-fold; P phytase and RUTF. Conclusions: In iron-fortified maize-based meals, the addition of lipids more than doubles iron absorption from FePP. Our results suggest the possibility of an enhancing effect on iron absorption of lipid-rich RUTFs, but more research is needed to determine this. This trial was registered at clinicaltrials.gov as NCT01991626. © 2017 American Society

  9. Towards a Mechanistic Understanding of Anaerobic Nitrate Dependent Iron Oxidation: Balancing Electron Uptake and Detoxification

    Directory of Open Access Journals (Sweden)

    Hans Karl Carlson

    2012-02-01

    Full Text Available The anaerobic oxidation of Fe(II by subsurface microorganisms is an important part of biogeochemical cycling in the environment, but the biochemical mechanisms used to couple iron oxidation to nitrate respiration are not well understood. Based on our own work and the evidence available in the literature, we propose a mechanistic model for anaerobic nitrate dependent iron oxidation. We suggest that anaerobic iron oxidizing microorganisms likely exist along a continuum including: 1 bacteria that inadvertently oxidize Fe(II by abiotic or biotic reactions with enzymes or chemical intermediates in their metabolic pathways (e.g. denitrification and suffer from toxicity or energetic penalty, 2 Fe(II tolerant bacteria that gain little or no growth benefit from iron oxidation but can manage the toxic reactions, and 3 bacteria that efficiently accept electrons from Fe(II to gain a growth advantage while preventing or mitigating the toxic reactions. Predictions of the proposed model are highlighted and experimental approaches are discussed.

  10. 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

    Directory of Open Access Journals (Sweden)

    Christophe Waterlot

    2012-01-01

    Full Text Available 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 (D2 method and the high-speed self-reversal method (HSSR method. Regarding the preliminary results obtained with synthetic solutions, the D2 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.

  11. Determination of antimony by electrochemical hydride generation atomic absorption spectrometry in samples with high iron content using chelating resins as on-line removal system

    International Nuclear Information System (INIS)

    Bolea, E.; Arroyo, D.; Laborda, F.; Castillo, J.R.

    2006-01-01

    A method for the removal of the interference caused by iron on electrochemical generation of stibine is proposed. It consists of a chelating resin Chelex 100 column integrated into a flow injection system and coupled to the electrochemical hydride generator quartz tube atomic absorption spectrometer (EcHG-QT-AAS). Iron, as Fe(II), is retained in the column with high efficiency, close to 99.9% under optimal conditions. No significant retention was observed for Sb(III) under same conditions and a 97 ± 5% signal recovery was achieved. An electrochemical hydride generator with a concentric configuration and a reticulated vitreous carbon cathode was employed. The system is able to determine antimony concentrations in the range of ng ml -1 in presence of iron concentrations up to 400 mg l -1 . The procedure was validated by analyzing PACS-2 marine sediments reference material with a 4% (w/w) iron content and a [Fe]:[Sb] ratio of 4000:1, which caused total antimony signal suppression on the electrochemical hydride generation system. A compost sample with high iron content (0.7%, w/w), was also analyzed. A good agreement was found on both samples with the certified value and the antimony concentration determined by ICP-MS, respectively

  12. A pre-concentration procedure using coprecipitation for determination of lead and iron in several samples using flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Saracoglu, S.; Soylak, M.; Peker, D.S. Kacar; Elci, L.; Santos, W.N.L. dos; Lemos, V.A.; Ferreira, S.L.C.

    2006-01-01

    The present paper proposes a pre-concentration procedure for determination of lead and iron in several samples by flame atomic absorption spectrometry. In it, lead(II) and iron(III) ions are coprecipitated using the violuric acid-copper(II) system as collector. Afterwards, the precipitate is dissolved with 1 M HNO 3 solution and the metal ions are determined. The optimization step was performed using factorial design involving the variables: pH, violuric acid mass (VA) and copper concentration (Cu). Using the optimized experimental conditions, the proposed procedure allows the determination these metals with detection limits of 0.18 μg L -1 for iron and 0.16 μg L -1 for lead. The effects of foreign ions on the pre-concentration procedure were also evaluated and the results demonstrated that this method could be applied for determination of iron and lead in several real samples. The proposed method was successfully applied to the analysis of seawater, urine, mineral water, soil and physiological solution samples. The concentrations of lead and iron achieved in these samples agree well with others data reported in the literature

  13. Comprehensive study of the effects of age, iron deficiency, diabetes mellitus, and cadmium burden on dietary cadmium absorption in cadmium-exposed female Japanese farmers

    International Nuclear Information System (INIS)

    Horiguchi, Hyogo; Oguma, Etsuko; Sasaki, Satoshi; Miyamoto, Kayoko; Ikeda, Yoko; Machida, Munehito; Kayama, Fujio

    2004-01-01

    The absorption rate of dietary cadmium (Cd) was investigated among 38 female farmers who had been exposed to Cd at levels close to the current provisional tolerable weekly intake (PTWI); these levels were much higher than those examined in previous studies. The study group composed of 7 diabetics and their 13 age-matched controls and 6 anemic subjects and their 12 controls. With their informed consent, the study participants were confined in an inn for 7 nights and 8 days to collect all feces and urine and duplicates of all food consumed. The dietary Cd absorption rate was calculated for each subject from her total Cd intake and fecal excretion. The means and 95% confidence intervals (CI) of the diabetic group and the anemic group did not differ significantly from those of their respective controls. By individual analysis using all 38 subjects, however, significant Pearson's correlation coefficients were observed between Cd absorption rate and age, serum ferritin, serum iron, and blood and urine Cd levels. Among these, multiple regression analysis revealed that only age was a significant factor contributing to Cd absorption rate. The actual Cd absorption rate in the youngest age group (20-39 years) was 44.0%, which was highly accelerated compared with the rate in the total subject group of 6.5%, while zero to negative balance was observed in the older subjects. These results demonstrate that age, rather than iron deficiency, diabetes mellitus (DM), or Cd burden, is the only independent factor affecting the Cd absorption rate, suggesting that young women are always at high risk

  14. Effects of soluble flavin on heterogeneous electron transfer between surface-exposed bacterial cytochromes and iron oxides

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zheming; Shi, Zhi; Shi, Liang; White, Gaye F.; Richardson, David J.; Clarke, Thomas A.; Fredrickson, Jim K.; Zachara, John M.

    2015-08-25

    Dissimilatory iron-reducing bacteria can utilize insoluble Fe(Mn)-oxides as a terminal electron acceptor under anaerobic conditions. For Shewanella species specifically, some evidence suggests that iron reduction is associated with the secretion of flavin mononucleotide (FMN) and riboflavin that are proposed to mediate electron transfer (Marsili et al., 2008). In this work, we used methyl viologen (MV•+)-encapsulated, porin-cytochrome complex (MtrCAB) embedded liposomes (MELs) as a synthetic model of the Shewanella outer membrane to investigate the proposed mediating behavior of secreted flavins. The reduction kinetics of goethite, hematite and lepidocrocite (200 µM) by MELs ([MV•+] ~ 42 µM and MtrABC ≤ 1 nM) were determined in the presence FMN at pH 7.0 in N2 atmosphere by monitoring the concentrations of MV•+ and FMN through their characteristic UV-visible absorption spectra. Experiments were performed where i) FMN and Fe(III)-oxide were mixed and then reacted with the reduced MELs and ii) FMN was reacted with the reduced MELs followed by addition of Fe(III)-oxide. The redox reactions proceeded in two steps: a fast step that was completed in a few seconds, and a slower one lasting over 400 seconds. For all three Fe(III)-oxides, the initial reaction rate in the presence of a low concentration of FMN (≤ 1 µM) was at least a factor of five faster than those with MELs alone, and orders of magnitude faster than those by FMNH2, suggesting that FMN may serve as a co-factor that enhances electron transfer from outer-membrane c-cytochromes to Fe(III)-oxides. The rate and extent of the initial reaction followed the order of lepidocrocite > hematite > goethite, the same as their reduction potentials, implying thermodynamic control on reaction rate. However, at higher FMN concentrations (> 1 µM), the reaction rates for both steps decreased and varied inversely with FMN concentration, indicating that FMN inhibited the MEL to Fe(III)-oxide electron transfer

  15. Influence of interstitial solutions (H, N) on cerium electronic state in Ce-Fe intermetallic compounds: X-ray Absorption Spectroscopy (XAS) study

    International Nuclear Information System (INIS)

    Chaboy, J.; Marcelli, A.; Bozukov, L.

    1995-03-01

    It is presented an x-ray absorption spectroscopy (XAS) investigation performed at the L-edges of the rare-earth and at the K-edge of iron in the R-Fe intermetallic compounds (La, Ce) 2 Fe 14 BH χ and Ce 2 Fe 17 (H,N) χ , to elucidate the role of the interstitial doping into the electronic and magnetic properties of these systems. Comparison with x-ray circular magnetic dichroism (XCMD) experiments has been carried out to clarify the localization of 4f magnetic moment at the Ce sites upon hydriding. Both XAS and XCMD results evidence the interplay between the structural and magnetic changes, that are associated to the modification of the hybridization between the Fe(3d) and Ce(5d) bands

  16. Simulations of iron K pre-edge X-ray absorption spectra using the restricted active space method.

    Science.gov (United States)

    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.

  17. Determination of anisotropy constants of protein encapsulated iron oxide nanoparticles by electron magnetic resonance

    International Nuclear Information System (INIS)

    Li Hongyan; Klem, Michael T.; Sebby, Karl B.; Singel, David J.; Young, Mark; Douglas, Trevor; Idzerda, Yves U.

    2009-01-01

    Angle-dependent electron magnetic resonance was performed on 4.9, 8.0, and 19 nm iron oxide nanoparticles encapsulated within protein capsids and suspended in water. Measurements were taken at liquid nitrogen temperature after cooling in a 1 T field to partially align the particles. The angle dependence of the shifts in the resonance field for the iron oxide nanoparticles (synthesized within Listeria-Dps, horse spleen ferritin, and cowpea chlorotic mottle virus) all show evidence of a uniaxial anisotropy. Using a Boltzmann distribution for the particles' easy-axis direction, we are able to use the resonance field shifts to extract a value for the anisotropy energy, showing that the anisotropy energy density increases with decreasing particle size. This suggests that surface anisotropy plays a significant role in magnetic nanoparticles of this size

  18. Determination of anisotropy constants of protein encapsulated iron oxide nanoparticles by electron magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongyan [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Klem, Michael T.; Sebby, Karl B.; Singel, David J. [Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Young, Mark [Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Douglas, Trevor [Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States); Idzerda, Yves U. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Center for Bio-Inspired Nanomaterials, Montana State University, Bozeman, MT 59717 (United States)], E-mail: Idzerda@montana.edu

    2009-02-15

    Angle-dependent electron magnetic resonance was performed on 4.9, 8.0, and 19 nm iron oxide nanoparticles encapsulated within protein capsids and suspended in water. Measurements were taken at liquid nitrogen temperature after cooling in a 1 T field to partially align the particles. The angle dependence of the shifts in the resonance field for the iron oxide nanoparticles (synthesized within Listeria-Dps, horse spleen ferritin, and cowpea chlorotic mottle virus) all show evidence of a uniaxial anisotropy. Using a Boltzmann distribution for the particles' easy-axis direction, we are able to use the resonance field shifts to extract a value for the anisotropy energy, showing that the anisotropy energy density increases with decreasing particle size. This suggests that surface anisotropy plays a significant role in magnetic nanoparticles of this size.

  19. Proton and Electron Additions to Iron (II) Dinitrogen Complexes Containing Pendant Amines

    Energy Technology Data Exchange (ETDEWEB)

    Heiden, Zachariah M.; Chen, Shentan; Labios, Liezel AN; Bullock, R. Morris; Walter, Eric D.; Tyson, Elizabeth L.; Mock, Michael T.

    2014-03-10

    We describe a single site cis-(H)FeII-N2 complex, generated by the protonation of an iron-carbon bond of a "reduced" iron complex, that models key aspects of proposed protonated intermediates of the E4 state of nitrogenase. The influence on N2 binding from the addition of protons to the pendant amine sites in the second coordination sphere is described. Furthermore, the addition of electrons to the protonated complexes results in H2 loss. The mechanism of H2 loss is explored to draw a parallel to the origin of H2 loss (homolytic or heterolytic) and the nature of N2 coordination in intermediates of the E4 state of nitrogenase.

  20. Interband optical absorption in the Wannier-Stark ladder under the electron-LO-phonon resonance condition

    International Nuclear Information System (INIS)

    Govorov, A.O.

    1993-08-01

    Interband optical absorption in the Wannier-Stark ladder in the presence of the electron-LO-phonon resonance is investigated theoretically. The electron-LO-phonon resonance occurs when the energy spacing between adjacent Stark-ladder levels coincides with the LO-phonon energy. We propose a model describing the polaron effect in a superlattice. Calculations show that the absorption line shape is strongly modified due to the polaron effect under the electron-LO-phonon resonance condition. We consider optical phenomena in a normal magnetic field that leads to enhancement of polaron effects. (author). 17 refs, 5 figs

  1. Systematic ab initio study of the electronic and magnetic properties of different pure and mixed iron systems

    International Nuclear Information System (INIS)

    Izquierdo, J.; Vega, A.; Balbas, L. C.; Sanchez-Portal, Daniel; Junquera, Javier; Artacho, Emilio; Soler, Jose M.; Ordejon, Pablo

    2000-01-01

    We present a theoretical study of the electronic and magnetic properties of iron systems in different environments: pure iron systems [dimer, bcc bulk, (100) surface, and free-standing iron monolayer], and low-dimensional iron systems deposited on Ag (100) surface (monoatomic linear wires, iron monolayer, planar, and three-dimensional clusters). Electronic and magnetic properties have been calculated using a recently developed total-energy first-principles method based on density-functional theory with numerical atomic orbitals as a basis set for the description of valence electrons and nonlocal pseudopotentials for the atomic core. The Kohn-Sham equations are solved self-consistently within the generalized gradient approximation for the exchange-correlation potential. Tests on the pseudopotential, the basis set, grid spacing, and k sampling are carefully performed. This technique, which has been proved to be very efficient for large nonmagnetic systems, is applied in this paper to calculate electronic and magnetic properties of different iron nanostructures. The results compare well with previous ab initio all-electron calculations and with experimental data. The method predicts the correct trends in the magnetic moments of Fe systems for a great variety of environments and requires a smaller computational effort than other ab initio methods. (c) 2000 The American Physical Society

  2. Systematic ab initio study of the electronic and magnetic properties of different pure and mixed iron systems

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo, J. [Departamento de Fisica Teorica, Universidad de Valladolid, E-47011 Valladolid, (Spain); Vega, A. [Departamento de Fisica Teorica, Universidad de Valladolid, E-47011 Valladolid, (Spain); Balbas, L. C. [Departamento de Fisica Teorica, Universidad de Valladolid, E-47011 Valladolid, (Spain); Sanchez-Portal, Daniel [Department of Physics and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States); Junquera, Javier [Departamento de Fisica de la Materia Condensada, C-III, and Institut Nicolas Cabrera, Universidad Autonoma de Madrid, 28049 Madrid, (Spain); Artacho, Emilio [Departamento de Fisica de la Materia Condensada, C-III, and Institut Nicolas Cabrera, Universidad Autonoma de Madrid, 28049 Madrid, (Spain); Soler, Jose M. [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Ordejon, Pablo [Institut de Ciencia de Materials de Barcelona (CSIC), Campus de la U.A.B., Bellaterra, E-08193 Barcelona, (Spain)

    2000-05-15

    We present a theoretical study of the electronic and magnetic properties of iron systems in different environments: pure iron systems [dimer, bcc bulk, (100) surface, and free-standing iron monolayer], and low-dimensional iron systems deposited on Ag (100) surface (monoatomic linear wires, iron monolayer, planar, and three-dimensional clusters). Electronic and magnetic properties have been calculated using a recently developed total-energy first-principles method based on density-functional theory with numerical atomic orbitals as a basis set for the description of valence electrons and nonlocal pseudopotentials for the atomic core. The Kohn-Sham equations are solved self-consistently within the generalized gradient approximation for the exchange-correlation potential. Tests on the pseudopotential, the basis set, grid spacing, and k sampling are carefully performed. This technique, which has been proved to be very efficient for large nonmagnetic systems, is applied in this paper to calculate electronic and magnetic properties of different iron nanostructures. The results compare well with previous ab initio all-electron calculations and with experimental data. The method predicts the correct trends in the magnetic moments of Fe systems for a great variety of environments and requires a smaller computational effort than other ab initio methods. (c) 2000 The American Physical Society.

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

    Science.gov (United States)

    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

  4. Electronic Raman spectra in iron-based superconductors with two-orbital model

    International Nuclear Information System (INIS)

    Lu Hongyan; Wang Da; Chen San; Wang Wei; Gong Pifeng

    2011-01-01

    Electronic Raman spectra were calculated in orbital space in a microscopic theory. Both Raman spectra and spectra weight were presented. Raman spectra for the gap symmetries are different from each other. The results can help decide the gap symmetry by comparing with experiments. Electronic Raman spectra in iron-based superconductors with two-orbital model is discussed. In the orbital space, some possible pairing symmetries of the gap are selected. To further discriminate them, electronic Raman spectra and spectra weight at Fermi surface (FS) which helps understand the Raman spectra are calculated in each case. From the low energy threshold, the number of Raman peaks, and the low frequency power law behavior, we can judge whether it is full gap or nodal gap, and even one gap or multi-gaps. The results provide useful predictions for comparison with experiments.

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

    Science.gov (United States)

    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. Copyright © 2016. Published by Elsevier B.V.

  6. Atomic-scale Visualization of Electronic Nematicity and Cooper Pairing in Iron-based Superconductors

    Science.gov (United States)

    Allan, Milan P.

    2013-03-01

    The mechanism of high-temperature superconductivity in the relatively novel iron-based high-Tc superconductors is unresolved, both in terms of how the phases evolve with doping, and in terms of the actual Cooper pairing process. To explore these issues, we used spectroscopic-imaging scanning tunneling microscopy to study the electronic structure of CaFe2As2 in the antiferromagnetic-orthorhombic `parent' state from which the superconductivity emerges. We discovered and visualized the now widely studied electronic `nematicity' of this phase, whose suppression is associated with the emergence of superconductivity (Science 327, 181, 2010). As subsequent transport experiments discovered a related anisotropic conductance which increases with dopant concentration, the interplay between the electronic structure surrounding each dopant atom, quasiparticle scattering therefrom, and the transport nematicity has become a pivotal focus of research. We find that substituting Co for Fe atoms in underdoped Ca(Fe1-xCox)2As2 generates a dense population of identical and strongly anisotropic impurity states that are distributed randomly but aligned with the antiferromagnetic a-axis. We also demonstrate, by imaging their surrounding interference patterns, that these impurity states scatter quasiparticles and thus influence transport in a highly anisotropic manner (M.P. Allan et al., 2013). Next, we studied the momentum dependence of the energy gaps of iron-based superconductivity, now focusing on LiFeAs. If strong electron-electron interactions mediate the Cooper pairing, then momentum-space anisotropic superconducting energy gaps Δi (k) were predicted by multiple techniques to appear on the different electronic bands i. We introduced intraband Bogoliubov quasiparticle scattering interference (QPI) techniques for the determination of anisotropic energy gaps to test these hypotheses and discovered the anisotropy, magnitude, and relative orientations of the energy gaps on multiple

  7. Characterization of the Electronic Structure of Silicon Nanoparticles Using X-ray Absorption and Emission

    Energy Technology Data Exchange (ETDEWEB)

    Vaverka, April Susan Montoya [Univ.of California, Davis, CA (United States)

    2008-01-01

    Resolving open questions regarding transport in nanostructures can have a huge impact on a broad range of future technologies such as light harvesting for energy. Silicon has potential to be used in many of these applications. Understanding how the band edges of nanostructures move as a function of size, surface termination and assembly is of fundamental importance in understanding the transport properties of these materials. In this thesis work I have investigated the change in the electronic structure of silicon nanoparticle assemblies as the surface termination is changed. Nanoparticles are synthesized using a thermal evaporation technique and sizes are determined using atomic force microscopy (AFM). By passivating the particles with molecules containing alcohol groups we are able to modify the size dependent band edge shifts. Both the valence and conduction bands are measured using synchrotron based x-ray absorption spectroscopy (XAS) and soft x-ray fluorescence (SXF) techniques. Particles synthesized via recrystallization of amorphous silicon/SiO2 multilayers of thicknesses below 10 nm are also investigated using the synchrotron techniques. These samples also show quantum confinement effects but the electronic structure is different from those synthesized via evaporation methods. The total bandgap is determined for all samples measured. The origins of these differences in the electronic structures are discussed.

  8. Electronic structure of titania aerogels: Soft x-ray absorption study

    International Nuclear Information System (INIS)

    Kucheyev, S.O.; Van Buuren, T.V.; Baumann, T.F.; Satcher, J.H.; Willey, T.M.; Muelenberg, R.W.; Felter, T.E.; Poco, J.E.; Gammon, S.A.; Terminello, L.J.

    2004-01-01

    Full text: Titania aerogels - a somewhat extreme form of nanoporous TiO 2 - are open-cell solid foams derived from highly crosslinked gels by drying them under supercritical conditions. In this presentation, the unoccupied electronic states of TiO 2 aerogels are studied by soft x-ray absorption near-edge structure (XANES) spectroscopy. High-resolution O K-edge and Ti L 2,3 -edge XANES spectra of aerogels are compared with those of rutile, anatase, and unrelaxed amorphous phases of full- density TiO 2 . Results show that all the main spectroscopic features of aerogels, reflecting the element-specific partial density of empty electronic states and correlation effects, can be attributed to the absence of long-range order in stoichiometric amorphous TiO 2 . Based on these results, we discuss the effects of short- and long-range order on the electronic structure of TiO 2 . This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48

  9. Electron-cyclotron wave propagation, absorption and current drive in the presence of neoclassical tearing modes

    Science.gov (United States)

    Isliker, Heinz; Chatziantonaki, Ioanna; Tsironis, Christos; Vlahos, Loukas

    2012-09-01

    We analyze the propagation of electron-cyclotron waves, their absorption and current drive when neoclassical tearing modes (NTMs), in the form of magnetic islands, are present in a tokamak plasma. So far, the analysis of the wave propagation and power deposition in the presence of NTMs has been performed mainly in the frame of an axisymmetric magnetic field, ignoring any effects from the island topology. Our analysis starts from an axisymmetric magnetic equilibrium, which is perturbed such as to exhibit magnetic islands. In this geometry, we compute the wave evolution with a ray-tracing code, focusing on the effect of the island topology on the efficiency of the absorption and current drive. To increase the precision in the calculation of the power deposition, the standard analytical flux-surface labeling for the island region has been adjusted from the usual cylindrical to toroidal geometry. The propagation up to the O-point is found to be little affected by the island topology, whereas the power absorbed and the driven current are significantly enhanced, because the resonant particles are bound to the small volumes in between the flux surfaces of the island. The consequences of these effects on the NTM evolution are investigated in terms of the modified Rutherford equation.

  10. Electron-cyclotron wave propagation, absorption and current drive in the presence of neoclassical tearing modes

    International Nuclear Information System (INIS)

    Isliker, Heinz; Chatziantonaki, Ioanna; Tsironis, Christos; Vlahos, Loukas

    2012-01-01

    We analyze the propagation of electron-cyclotron waves, their absorption and current drive when neoclassical tearing modes (NTMs), in the form of magnetic islands, are present in a tokamak plasma. So far, the analysis of the wave propagation and power deposition in the presence of NTMs has been performed mainly in the frame of an axisymmetric magnetic field, ignoring any effects from the island topology. Our analysis starts from an axisymmetric magnetic equilibrium, which is perturbed such as to exhibit magnetic islands. In this geometry, we compute the wave evolution with a ray-tracing code, focusing on the effect of the island topology on the efficiency of the absorption and current drive. To increase the precision in the calculation of the power deposition, the standard analytical flux-surface labeling for the island region has been adjusted from the usual cylindrical to toroidal geometry. The propagation up to the O-point is found to be little affected by the island topology, whereas the power absorbed and the driven current are significantly enhanced, because the resonant particles are bound to the small volumes in between the flux surfaces of the island. The consequences of these effects on the NTM evolution are investigated in terms of the modified Rutherford equation. (paper)

  11. Electronic decay cascades in media initiated by resonant absorption of X-ray photons

    Energy Technology Data Exchange (ETDEWEB)

    Miteva, Tsveta

    2015-07-16

    The resonant-Auger - interatomic Coulombic decay (RA-ICD) cascade was recently proposed as a very efficient means of controlling the generation site and energies of slow ICD electrons. The control mechanism was verified in a series of experiments where both the energy of the photons producing the initial core excitation, and the neighbouring species were varied. The aim of this thesis is to provide a detailed theoretical investigation of the RA-ICD cascade in rare-gas dimers and give a first insight into the course of the cascade in aqueous medium. The potential energy curves (PECs) of ionisation satellites are key ingredients in the theoretical description of electronic decay cascades. In the first chapter, we conducted a study on the PECs of the ionisation satellites of the ArHe dimer with a view to modelling such PECs in heavier dimers. Our results show that the complex valence structure in the rare-gas atom leads to the mixing of different electronic configurations of the dimer, which prevents one from assigning a single dicationic parent state to some of the ionisation satellites. In the second part of the thesis, we present and analyse the ICD-electron and kinetic-energy-release (KER) spectra following different resonant core excitations of Ar in the rare-gas dimers Ar{sub 2} and ArKr. We demonstrate that the manifold of ICD states populated in the resonant Auger process consists of fast- and slow-decaying ionisation satellites, and that the accurate description of nuclear dynamics in the latter ICD states is crucial for obtaining theoretical electron and KER spectra in good agreement with the experiment. We also show that by varying the neighbouring atom one can tune the energies of the emitted ICD electrons and even control the ICD yield. Finally, as a first step towards the investigation of the RA-ICD cascade in aqueous medium, we present and discuss the X-Ray absorption spectra of microsolvated clusters of Na{sup +} and Mg{sup 2+} at the metal 1s

  12. Polynuclear water-soluble dinitrosyl iron complexes with cysteine or glutathione ligands: electron paramagnetic resonance and optical studies.

    Science.gov (United States)

    Vanin, Anatoly F; Poltorakov, Alexander P; Mikoyan, Vasak D; Kubrina, Lyudmila N; Burbaev, Dosymzhan S

    2010-09-15

    Electron paramagnetic resonance and optical spectrophotometric studies have demonstrated that low-molecular dinitrosyl iron complexes (DNICs) with cysteine or glutathione exist in aqueous solutions in the form of paramagnetic mononuclear (capital EM, Cyrillic-DNICs) and diamagnetic binuclear complexes (B-DNICs). The latter represent Roussin's red salt esters and can be prepared by treatment of aqueous solutions of Fe(2+) and thiols (small er, Cyrilliccapital EN, Cyrillic 7.4) with gaseous nitric oxide (NO) at the thiol:Fe(2+) ratio 1:1. capital EM, Cyrillic-DNICs are synthesized under identical conditions at the thiol:Fe(2+) ratios above 20 and produce an EPR signal with an electronic configuration {Fe(NO)(2)}(7) at g(aver.)=2.03. At neutral pH, aqueous solutions contain both M-DNICs and B-DNICs (the content of the latter makes up to 50% of the total DNIC pool). The concentration of B-DNICs decreases with a rise in pH; at small er, Cyrilliccapital EN, Cyrillic 9-10, the solutions contain predominantly M-DNICs. The addition of thiol excess to aqueous solutions of B-DNICs synthesized at the thiol:Fe(2+) ratio 1:2 results in their conversion into capital EM, Cyrillic-DNICs, the total amount of iron incorporated into M-DNICs not exceeding 50% of the total iron pool in B-DNICs. Air bubbling of cys-capital EM, Cyrillic-DNIC solutions results in cysteine oxidation-controlled conversion of capital EM, Cyrillic-DNICs first into cys-B-DNICs and then into the EPR-silent compound capital HA, Cyrillic able to generate a strong absorption band at 278 nm. In the presence of glutathione or cysteine excess, compound capital HA, Cyrillic is converted into B-DNIC/M-DNIC and is completely decomposed under effect of the Fe(2+) chelator small o, Cyrillic-phenanthroline or N-methyl-d-glucamine dithiocarbamate (MGD). Moreover, MGD initiates the synthesis of paramagnetic mononitrosyl iron complexes with MGD. It is hypothesized that compound capital HA, Cyrillic represents a polynuclear

  13. Preconcentration and determination of iron and copper in spice samples by cloud point extraction and flow injection flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Sahin, Cigdem Arpa, E-mail: carpa@hacettepe.edu.tr [Hacettepe University, Chemistry Department, 06800 Beytepe, Ankara (Turkey); Tokgoez, Ilknur; Bektas, Sema [Hacettepe University, Chemistry Department, 06800 Beytepe, Ankara (Turkey)

    2010-09-15

    A flow injection (FI) cloud point extraction (CPE) method for the determination of iron and copper by flame atomic absorption spectrometer (FAAS) has been improved. The analytes were complexed with 3-amino-7-dimethylamino-2-methylphenazine (Neutral Red, NR) and octylphenoxypolyethoxyethanol (Triton X-114) was added as a surfactant. The micellar solution was heated above 50 {sup o}C and loaded through a column packed with cotton for phase separation. Then the surfactant-rich phase was eluted using 0.05 mol L{sup -1} H{sub 2}SO{sub 4} and the analytes were determined by FAAS. Chemical and flow variables influencing the instrumental and extraction conditions were optimized. Under optimized conditions for 25 mL of preconcentrated solution, the enrichment factors were 98 and 69, the limits of detection (3s) were 0.7 and 0.3 ng mL{sup -1}, the limits of quantification (10s) were 2.2 and 1.0 ng mL{sup -1} for iron and copper, respectively. The relative standard deviation (RSD) for ten replicate measurements of 10 ng mL{sup -1} iron and copper were 2.1% and 1.8%, respectively. The proposed method was successfully applied to determination of iron and copper in spice samples.

  14. Electron-beam-induced reduction of Fe3+ in iron phosphate dihydrate, ferrihydrite, haemosiderin and ferritin as revealed by electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Pan, Ying-Hsi; Vaughan, Gareth; Brydson, Rik; Bleloch, Andrew; Gass, Mhairi; Sader, Kasim; Brown, Andy

    2010-01-01

    The effect of high-energy electron irradiation on ferritin/haemosiderin cores (in an iron-overloaded human liver biopsy), its mineral analogue; six-line ferrihydrite (6LFh), and iron phosphate dihydrate (which has similar octahedral ferric iron to oxygen coordination to that in ferrihydrite and ferritin/haemosiderin cores) has been investigated using electron energy-loss spectroscopy (EELS). Fe L 2,3 -ionisation edges were recorded on two types of electron microscope: a 200 keV transmission electron microscope (TEM) and a 100 keV scanning transmission electron microscope (STEM), in order to investigate the damage mechanisms in operation and to establish a methodology for minimum specimen alteration during analytical electron microscopic characterisation. A specimen damage mechanism dominated by radiolysis that results in the preferential loss of iron co-ordinating ligands (O, OH and H 2 O) is discussed. The net result of irradiation is structural re-organisation and reduction of iron within the iron hydroxides. At sufficiently low electron fluence and particularly in the lower incident energy, finer probe diameter STEM, the alteration is shown to be minimal. All the materials examined exhibit damage which as a function of cumulative fluence is best fitted by an inverse power-law, implying that several chemical and structural changes occur in response to the electron beam and we suggest that these are governed by secondary processes arising from the primary ionisation event. This work affirms that electron fluence and current density should be considered when measuring mixed valence ratios with EELS.

  15. Electron-beam-induced reduction of Fe{sup 3+} in iron phosphate dihydrate, ferrihydrite, haemosiderin and ferritin as revealed by electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Ying-Hsi; Vaughan, Gareth; Brydson, Rik [Institute for Materials Research, SPEME, University of Leeds, Leeds LS2 9JT (United Kingdom); Bleloch, Andrew; Gass, Mhairi [SuperSTEM, Daresbury Laboratories, Warrington WA4 4AD (United Kingdom); Sader, Kasim [Institute for Materials Research, SPEME, University of Leeds, Leeds LS2 9JT (United Kingdom); SuperSTEM, Daresbury Laboratories, Warrington WA4 4AD (United Kingdom); Brown, Andy, E-mail: a.p.brown@leeds.ac.uk [Institute for Materials Research, SPEME, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2010-07-15

    The effect of high-energy electron irradiation on ferritin/haemosiderin cores (in an iron-overloaded human liver biopsy), its mineral analogue; six-line ferrihydrite (6LFh), and iron phosphate dihydrate (which has similar octahedral ferric iron to oxygen coordination to that in ferrihydrite and ferritin/haemosiderin cores) has been investigated using electron energy-loss spectroscopy (EELS). Fe L{sub 2,3}-ionisation edges were recorded on two types of electron microscope: a 200 keV transmission electron microscope (TEM) and a 100 keV scanning transmission electron microscope (STEM), in order to investigate the damage mechanisms in operation and to establish a methodology for minimum specimen alteration during analytical electron microscopic characterisation. A specimen damage mechanism dominated by radiolysis that results in the preferential loss of iron co-ordinating ligands (O, OH and H{sub 2}O) is discussed. The net result of irradiation is structural re-organisation and reduction of iron within the iron hydroxides. At sufficiently low electron fluence and particularly in the lower incident energy, finer probe diameter STEM, the alteration is shown to be minimal. All the materials examined exhibit damage which as a function of cumulative fluence is best fitted by an inverse power-law, implying that several chemical and structural changes occur in response to the electron beam and we suggest that these are governed by secondary processes arising from the primary ionisation event. This work affirms that electron fluence and current density should be considered when measuring mixed valence ratios with EELS.

  16. Optical Analysis of Iron-Doped Lead Sulfide Thin Films for Opto-Electronic Applications

    Science.gov (United States)

    Chidambara Kumar, K. N.; Khadeer Pasha, S. K.; Deshmukh, Kalim; Chidambaram, K.; Shakil Muhammad, G.

    Iron-doped lead sulfide thin films were deposited on glass substrates using successive ionic layer adsorption and reaction method (SILAR) at room temperature. The X-ray diffraction pattern of the film shows a well formed crystalline thin film with face-centered cubic structure along the preferential orientation (1 1 1). The lattice constant is determined using Nelson Riley plots. Using X-ray broadening, the crystallite size is determined by Scherrer formula. Morphology of the thin film was studied using a scanning electron microscope. The optical properties of the film were investigated using a UV-vis spectrophotometer. We observed an increase in the optical band gap from 2.45 to 3.03eV after doping iron in the lead sulfide thin film. The cutoff wavelength lies in the visible region, and hence the grown thin films can be used for optoelectronic and sensor applications. The results from the photoluminescence study show the emission at 500-720nm. The vibrating sample magnetometer measurements confirmed that the lead sulfide thin film becomes weakly ferromagnetic material after doping with iron.

  17. Detection of fatigue fracture in pearlitic flake graphite cast iron with the help of scanning and transmission electron microscopy

    International Nuclear Information System (INIS)

    Dunger, B.; Hunger, J.

    1976-01-01

    To prove the existence of the characteristic features of fatigue fracture in a pearlitic flake graphite cast iron, its fracture surface topography revealed by scanning electron microscopy has been compared with that of a pearlitic steel, the fractures having been caused by static tensile and by cyclic bending tests. The characteristic features of fatigue fracture were visible in the pearlitic matrix of the steel and of the flake graphite cast iron as well. These features differ characteristically from the lamellar structure of the pearlite, particularly after etching the surface area of the fractures. The graphite structures as viewed on the electron scanning and the electron transmission microscope are described. (orig.) [de

  18. Electron phonon couplings in 2D perovskite probed by ultrafast photoinduced absorption spectroscopy

    Science.gov (United States)

    Huynh, Uyen; Ni, Limeng; Rao, Akshay

    We use the time-resolved photoinduced absorption (PIA) spectroscopy with 20fs time resolution to investigate the electron phonon coupling in the self-assembled hybrid organic layered perovskite, the hexyl ammonium lead iodide compound (C6H13NH3)2 (PbI4) . The coupling results in the broadening and asymmetry of its temperature-dependence photoluminescence spectra. The exact time scale of this coupling, however, wasn't reported experimentally. Here we show that using an ultrashort excitation pulse allows us to resolve from PIA kinetics the oscillation of coherent longitudinal optical phonons that relaxes and self-traps electrons to lower energy states within 200 fs. The 200fs relaxation time is equivalent to a coupling strength of 40meV. Two coupled phonon modes are also identified as about 100 cm-1 and 300 cm-1 from the FFT spectrum of the PIA kinetics. The lower energy mode is consistent with previous reports and Raman spectrum but the higher energy one hasn't been observed before.

  19. Electron beam test of an iron/gas calorimeter based on ceramic parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Herve, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Maggi, F.; Malinin, A.; Meschini, M.; Pojidaev, V.; Radermacher, E.; Salicio, J.M.

    1995-01-01

    The baseline option for the very forward calorimetry in the CMS experiment is an iron/gas calorimeter based on parallel plate chambers. A small prototype module of such a calorimeter, has been tested using electrons of 5 to 100 GeV/c momentum with various high voltages and two gases: CO2 (100%) and CF4/CO2 (80/20), at atmospheric pressure. The collected charge has been measured as a function of the high voltage and of the electron energy. The energy resolution has also been measured. Comparisons have been made with Monte-Carlo predictions. Agreement between data an simulation allows to make and estimation of the expected performance of a full size calorimeter. (Author) 23 refs

  20. Electron beam test of an iron/gas calorimeter based on ceramic parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, G.L.; Bizzeti, A.; choumilov, E.; Civinini, C.; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Herve, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Maggi, F.; Malininin, A.; Meschini, M.; Pojidaev, V.; Radermacher, E.; Salicio, J.M.

    1995-12-01

    The baseline option for the very forward calorimetry in the CMS experiment is an iron/gas calorimeter based on parallel plate chambers. A small prototype module of such a calorimeter, has been tested using electrons of 5 to 100 GeV/c momentum with various high voltages and two gases: CO 2 (100%) and CF 4 /CO 2 (80/20), at atmospheric pressure. The collected charge has been measured as a function of the high voltage and of the electron energy. The energy resolution has also been measured. Comparisons have been made with Monte-Carlo predictions. Agreement between data an simulation allows to make and estimation of the expected performance of a full size calorimeter. (Author)

  1. Stability, electrochemical behaviors and electronic structures of iron hydroxyl-phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zhongli; Sun Shaorui; Li Fan; Chen Ge [College of Environmental and Energy Engineering, Beijing University of Technology, Pingleyuan 100, Chaoyang District, Beijing 100022 (China); Xia Dingguo, E-mail: dgxia@bjut.edu.cn [College of Environmental and Energy Engineering, Beijing University of Technology, Pingleyuan 100, Chaoyang District, Beijing 100022 (China); Zhao Ting; Chu Wangsheng [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); University of Science and Technology of China, Hefei 230026 (China); Wu Ziyu, E-mail: wuzy@ihep.ac.cn [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); University of Science and Technology of China, Hefei 230026 (China)

    2010-09-01

    Iron hydroxyl-phosphate with a uniform spherical particle size of around 1 {mu}m, a compound of the type Fe{sub 2-y}{open_square}{sub y}(PO{sub 4})(OH){sub 3-3y}(H{sub 2}O){sub 3y-2} (where {open_square} represents a vacancy), has been synthesized by hydrothermal methods. The particles are composed of spheres of diameter <100 nm. The compound exhibits good electrochemical performance, with reversible capacities of around 150 mAh g{sup -1} and 120 mAh g{sup -1} at current densities of 170 mA g{sup -1} and 680 mA g{sup -1}, respectively. The stability of crystal structure of this material was studied by TGA and XRD which show that the material remains stable at least up to the temperature 200 deg. C. Investigation of the electronic structure of the iron hydroxyl-phosphate by GGA + U calculation has indicated that it has a better electronic conductivity than LiFePO{sub 4}.

  2. An analytical electron microscopy characterization of melt-spun iron/rare-earth/boron magnetic materials

    International Nuclear Information System (INIS)

    Dickenson, R.C.; Lawless, K.R.; Hadjipanayis, G.C.

    1986-01-01

    Iron/rare-earth/boron permanent magnet materials have recently been developed to reduce the need for the strategic element cobalt, which was previously the primary component of high-energy magnets. These materials are generally produced by annealing rapidly solidified ribbons or by conventional powder metallurgy techniques. This paper reports results from an analytical electron microscopy characterization undertaken to establish the relationship between the magnetic properties and the microstructure of two iron/rare-earth/boron (Fe/RE/B) alloys. Ribbons of Fe 75 Pr 15 B 10 and Fe 77 Tb 15 B 8 were produced by melt-spinning. To obtain optimum magnetic properties, both alloys were then annealed at 700 0 C, the FePrB ribbons for 6 minutes and the FeTbB ribbons for 90 minutes. Foils for transmission electron microscopy were prepared by ion-milling the ribbons on a cold stage and examined using a Philips 400T TEM/STEM equipped with an energy dispersive x-ray unit

  3. Anomalous Behavior of Electronic Heat Capacity of Strongly Correlated Iron Monosilicide

    Science.gov (United States)

    Povzner, A. A.; Volkov, A. G.; Nogovitsyna, T. A.

    2018-04-01

    The paper deals with the electronic heat capacity of iron monosilicide FeSi subjected to semiconductor-metal thermal transition during which the formation of its spintronic properties is observed. The proposed model which considers pd-hybridization of strongly correlated d-electrons with non-correlated p-electrons, demonstrates a connection of their contribution to heat capacity in the insulator phase with paramagnon effects and fluctuations of occupation numbers for p- and d-states. In a slitless state, the temperature curve of heat capacity is characterized by a maximum appeared due to normalization of the electron density of states using fluctuating exchange fields. At higher temperatures, a linear growth in heat capacity occurs due to paramagnon effects. The correlation between the model parameters and the first-principles calculation provides the electron contribution to heat capacity, which is obtained from the experimental results on phonon heat capacity. Anharmonicity of phonons is connected merely with the thermal expansion of the crystal lattice.

  4. Molecular Computational Investigation of Electron Transfer Kinetics across Cytochrome-Iron Oxide Interfaces

    International Nuclear Information System (INIS)

    Kerisit, Sebastien N.; Rosso, Kevin M.; Dupuis, Michel; Valiev, Marat

    2007-01-01

    The interface between electron transfer proteins such as cytochromes and solid phase mineral oxides is central to the activity of dissimilatory-metal reducing bacteria. A combination of potential-based molecular dynamics simulations and ab initio electronic structure calculations are used in the framework of Marcus' electron transfer theory to compute elementary electron transfer rates from a well-defined cytochrome model, namely the small tetraheme cytochrome (STC) from Shewanella oneidensis, to surfaces of the iron oxide mineral hematite (a-Fe2O3). Room temperature molecular dynamics simulations show that an isolated STC molecule favors surface attachment via direct contact of hemes I and IV at the poles of the elongated axis, with electron transfer distances as small as 9 Angstroms. The cytochrome remains attached to the mineral surface in the presence of water and shows limited surface diffusion at the interface. Ab initio electronic coupling matrix element (VAB) calculations of configurations excised from the molecular dynamics simulations reveal VAB values ranging from 1 to 20 cm-1, consistent with nonadiabaticity. Using these results, together with experimental data on the redox potential of hematite and hemes in relevant cytochromes and calculations of the reorganization energy from cluster models, we estimate the rate of electron transfer across this model interface to range from 1 to 1000 s-1 for the most exothermic driving force considered in this work, and from 0.01 to 20 s-1 for the most endothermic. This fairly large range of electron transfer rates highlights the sensitivity of the rate upon the electronic coupling matrix element, which is in turn dependent on the fluctuations of the heme configuration at the interface. We characterize this dependence using an idealized bis-imidazole heme to compute from first principles the VAB variation due to porphyrin ring orientation, electron transfer distance, and mineral surface termination. The electronic

  5. Molecular evidence and physiological characterization of iron absorption in isolated enterocytes of rainbow trout (Oncorhynchus mykiss): Implications for dietary cadmium and lead absorption

    International Nuclear Information System (INIS)

    Kwong, Raymond W.M.; Andres, Jose A.; Niyogi, Som

    2010-01-01

    Recent studies suggested the probable involvement of an apical iron (Fe 2+ ) transporter, the divalent metal transporter-1 (DMT1), in the uptake of several divalent metals in fish. The present study examined the gastrointestinal expression of the DMT1 gene, and investigated the kinetics of Fe 2+ uptake and its interactions with cadmium and lead in isolated enterocytes of freshwater rainbow trout (Oncorhynchus mykiss). The expressions of two DMT1 isoforms (Nramp-β and -γ) were recorded along the entire gastrointestinal tract of fish as well as in the enterocytes. Fe 2+ uptake in isolated enterocytes was saturable and sensitive to the proton gradient and membrane potential, suggesting DMT1-mediated transport. Both cadmium and lead inhibited Fe 2+ uptake in isolated enterocytes in a concentration-dependent manner, and lead appeared to be a stronger inhibitor than cadmium. The kinetic characterization of Fe 2+ uptake revealed that the apparent affinity of uptake was significantly decreased (increased K m ) in the presence of either cadmium or lead, whereas the maximum uptake rate (J max ) remained unchanged-indicating that the interaction between Fe 2+ and cadmium or lead is competitive in nature. Overall, our study suggests that the uptake of dietary cadmium and lead may occur via the iron-transporting pathway in fish.

  6. Molecular evidence and physiological characterization of iron absorption in isolated enterocytes of rainbow trout (Oncorhynchus mykiss): Implications for dietary cadmium and lead absorption

    Energy Technology Data Exchange (ETDEWEB)

    Kwong, Raymond W.M. [Toxicology Centre, University of Saskatchewan, Saskatoon, SK., S7N 5B3 (Canada); Andres, Jose A. [Department of Biology, University of Saskatchewan, Saskatoon, SK., S7N 5E2 (Canada); Niyogi, Som, E-mail: som.niyogi@usask.ca [Department of Biology, University of Saskatchewan, Saskatoon, SK., S7N 5E2 (Canada)

    2010-09-01

    Recent studies suggested the probable involvement of an apical iron (Fe{sup 2+}) transporter, the divalent metal transporter-1 (DMT1), in the uptake of several divalent metals in fish. The present study examined the gastrointestinal expression of the DMT1 gene, and investigated the kinetics of Fe{sup 2+} uptake and its interactions with cadmium and lead in isolated enterocytes of freshwater rainbow trout (Oncorhynchus mykiss). The expressions of two DMT1 isoforms (Nramp-{beta} and -{gamma}) were recorded along the entire gastrointestinal tract of fish as well as in the enterocytes. Fe{sup 2+} uptake in isolated enterocytes was saturable and sensitive to the proton gradient and membrane potential, suggesting DMT1-mediated transport. Both cadmium and lead inhibited Fe{sup 2+} uptake in isolated enterocytes in a concentration-dependent manner, and lead appeared to be a stronger inhibitor than cadmium. The kinetic characterization of Fe{sup 2+} uptake revealed that the apparent affinity of uptake was significantly decreased (increased K{sub m}) in the presence of either cadmium or lead, whereas the maximum uptake rate (J{sub max}) remained unchanged-indicating that the interaction between Fe{sup 2+} and cadmium or lead is competitive in nature. Overall, our study suggests that the uptake of dietary cadmium and lead may occur via the iron-transporting pathway in fish.

  7. The effects of solvents and structure on the electronic absorption spectra of the isomeric pyridine carboxylic acid N-oxides

    Directory of Open Access Journals (Sweden)

    Drmanić Saša Ž.

    2013-01-01

    Full Text Available The ultraviolet absorption spectra of the carboxyl group of three isomeric pyridine carboxylic acids N-oxides (picolinic acid N-oxide, nicotinic acid N-oxide and isonicotinic acid N-oxide were determined in fourteen solvents in the wavelength range from 200 to 400 nm. The position of the absorption maxima (λmax of the examined acids showed that the ultraviolet absorption maximum wavelengths of picolinic acid N-oxide are the shortest, and those of isonicotinic acid N-oxide acid are the longest. In order to analyze the solvent effect on the obtained absorption spectra, the ultraviolet absorption frequencies of the electronic transitions in the carboxylic group of the examined acids were correlated using a total solvatochromic equation of the form max = v0 + sπ + aα+ bβ, where υmax is the absorption frequency (1/λmax, p is a measure of the solvent polarity, β represents the scale of solvent hydrogen bond acceptor basicities and α represent the scale of solvent hydrogen bond donor acidities. The correlation of the spectroscopic data was carried out by means of multiple linear regression analysis. The solvent effects on the ultraviolet absorption maximums of the examined acids were discussed.

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

    Science.gov (United States)

    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. © 2016 Poultry Science Association Inc.

  9. Environmental Transmission Electron Microscopy (ETEM) Studies of Single Iron Nanoparticle Carburization in Synthesis Gas

    DEFF Research Database (Denmark)

    Liu, Xi; Zhang, Chenghua; Li, Yongwang

    2017-01-01

    Structuralevolution of iron nanoparticles involving the formationand growth of iron carbide nuclei in the iron nanoparticle was directlyvisualized at the atomic level, using environmental transmission electronmicroscopy (TEM) under reactive conditions mimicking Fischer–Tropschsynthesis. Formation...... and electronenergy-loss spectra provides a detailed picture from initial activationto final degradation of iron under synthesis gas....

  10. Helium, iron and electron particle transport and energy transport studies on the TFTR tokamak

    International Nuclear Information System (INIS)

    Synakowski, E.J.; Efthimion, P.C.; Rewoldt, G.; Stratton, B.C.; Tang, W.M.; Grek, B.; Hill, K.W.; Hulse, R.A.; Johnson, D.W.; Mansfield, D.K.; McCune, D.; Mikkelsen, D.R.; Park, H.K.; Ramsey, A.T.; Redi, M.H.; Scott, S.D.; Taylor, G.; Timberlake, J.; Zarnstorff, M.C.

    1993-03-01

    Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor

  11. Helium, Iron and Electron Particle Transport and Energy Transport Studies on the TFTR Tokamak

    Science.gov (United States)

    Synakowski, E. J.; Efthimion, P. C.; Rewoldt, G.; Stratton, B. C.; Tang, W. M.; Grek, B.; Hill, K. W.; Hulse, R. A.; Johnson, D .W.; Mansfield, D. K.; McCune, D.; Mikkelsen, D. R.; Park, H. K.; Ramsey, A. T.; Redi, M. H.; Scott, S. D.; Taylor, G.; Timberlake, J.; Zarnstorff, M. C. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kissick, M. W. (Wisconsin Univ., Madison, WI (United States))

    1993-03-01

    Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.

  12. Electronic and magnetic coupling of iron and copper phthalocyanine to ferromagnetic Co(100) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Felix; Sauther, Jens; Lach, Stefan; Ziegler, Christiane [Department of Physics, University of Kaiserslautern, Erwin Schroedinger Str. 56, D-67663 Kaiserslautern (Germany); Ali, Ehesan; Oppeneer, Peter [Department of Physics and Materials Science, Box 530, Uppsala University, S-75121 Uppsala (Sweden)

    2009-07-01

    Metallo-phthalocyanines are organic semiconductors which show in certain cases promising magnetic properties, advertising them for use in organic spintronics. Here, copper (CuPc) and iron phthalocyanine (FePc) were grown on ultra thin layers of Co(100) substrates with well known highly spin-polarized electron injection capability. Photoelectron spectroscopy (XPS) reveals different interactions between the pyrolytic nitrogen atoms and the cobalt surface for the two phthalocyanines. The analysis of the different multiplet structures appearing for the nitrogen core levels in the submonolayer regime and UPS investigations of the valence band electronic structure of the Co dominated region near the Fermi level indicates a particularly electronic coupling and a rehybridisation of the molecular orbitals with the cobalt orbitals. In order to clarify the influence of the two different central atoms on the electronic- and subsequently the magnetic coupling to the Co substrate, theoretical calculations using the GGA and GGA+U methodologies on a structure of Fe/Cu-phthalocyanine adsorbed on a 3-layered cobalt surface were performed indicating a ferromagnetic coupling between FePc and Co.

  13. Effect of iron oxide reductive dissolution on the transformation and immobilization of arsenic in soils: New insights from X-ray photoelectron and X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jian-Xin [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); School of River and Ocean Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Wang, Yu-Jun, E-mail: yjwang@issas.ac.cn [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Liu, Cun [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Wang, Li-Hua; Yang, Ke [Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of sciences, Shanghai 201204 (China); Zhou, Dong-Mei, E-mail: dmzhou@issas.ac.cn [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Li, Wei; Sparks, Donald L. [Environmental Soil Chemistry Group, Delaware Environmental Institute and Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19717-1303 United States (United States)

    2014-08-30

    Graphical abstract: - Highlights: • Immobility and transformation of As on different Eh soils were investigated. • μ-XRF, XANES, and XPS were used to gain As distribution and speciation in soil. • Sorption capacity of As on anaerobic soil was much higher than that on oxic soil. • Fe oxides reductive dissolution is a key factor for As sorption and transformation. - Abstract: The geochemical behavior and speciation of arsenic (As) in paddy soils is strongly controlled by soil redox conditions and the sequestration by soil iron oxyhydroxides. Hence, the effects of iron oxide reductive dissolution on the adsorption, transformation and precipitation of As(III) and As(V) in soils were investigated using batch experiments and synchrotron based techniques to gain a deeper understanding at both macroscopic and microscopic scales. The results of batch sorption experiments revealed that the sorption capacity of As(V) on anoxic soil was much higher than that on control soil. Synchrotron based X-ray fluorescence (μ-XRF) mapping studies indicated that As was heterogeneously distributed and was mainly associated with iron in the soil. X-ray absorption near edge structure (XANES), micro-X-ray absorption near edge structure (μ-XANES) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the primary speciation of As in the soil is As(V). These results further suggested that, when As(V) was introduced into the anoxic soil, the rapid coprecipitation of As(V) with ferric/ferrous ion prevented its reduction to As(III), and was the main mechanism controlling the immobilization of As. This research could improve the current understanding of soil As chemistry in paddy and wetland soils.

  14. Effect of iron oxide reductive dissolution on the transformation and immobilization of arsenic in soils: New insights from X-ray photoelectron and X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Fan, Jian-Xin; Wang, Yu-Jun; Liu, Cun; Wang, Li-Hua; Yang, Ke; Zhou, Dong-Mei; Li, Wei; Sparks, Donald L.

    2014-01-01

    Graphical abstract: - Highlights: • Immobility and transformation of As on different Eh soils were investigated. • μ-XRF, XANES, and XPS were used to gain As distribution and speciation in soil. • Sorption capacity of As on anaerobic soil was much higher than that on oxic soil. • Fe oxides reductive dissolution is a key factor for As sorption and transformation. - Abstract: The geochemical behavior and speciation of arsenic (As) in paddy soils is strongly controlled by soil redox conditions and the sequestration by soil iron oxyhydroxides. Hence, the effects of iron oxide reductive dissolution on the adsorption, transformation and precipitation of As(III) and As(V) in soils were investigated using batch experiments and synchrotron based techniques to gain a deeper understanding at both macroscopic and microscopic scales. The results of batch sorption experiments revealed that the sorption capacity of As(V) on anoxic soil was much higher than that on control soil. Synchrotron based X-ray fluorescence (μ-XRF) mapping studies indicated that As was heterogeneously distributed and was mainly associated with iron in the soil. X-ray absorption near edge structure (XANES), micro-X-ray absorption near edge structure (μ-XANES) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the primary speciation of As in the soil is As(V). These results further suggested that, when As(V) was introduced into the anoxic soil, the rapid coprecipitation of As(V) with ferric/ferrous ion prevented its reduction to As(III), and was the main mechanism controlling the immobilization of As. This research could improve the current understanding of soil As chemistry in paddy and wetland soils

  15. Electron spin resonance spectroscopy for immunoassay using iron oxide nanoparticles as probe.

    Science.gov (United States)

    Jiang, Jia; Tian, Sizhu; Wang, Kun; Wang, Yang; Zang, Shuang; Yu, Aimin; Zhang, Ziwei

    2018-02-01

    With the help of iron oxide nanoparticles, electron spin resonance spectroscopy (ESR) was applied to immunoassay. Iron oxide nanoparticles were used as the ESR probe in order to achieve an amplification of the signal resulting from the large amount of Fe 3+ ion enclosed in each nanoparticle. Rabbit IgG was used as antigen to test this method. Polyclonal antibody of rabbit IgG was used as antibody to detect the antigen. Iron oxide nanoparticle with a diameter of either 10 or 30 nm was labeled to the antibody, and Fe 3+ in the nanoparticle was probed for ESR signal. The sepharose beads were used as solid phase to which rabbit IgG was conjugated. The nanoparticle-labeled antibody was first added in the sample containing antigen, and the antigen-conjugated sepharose beads were then added into the sample. The nanoparticle-labeled antibody bound to the antigen on sepharose beads was separated from the sample by centrifugation and measured. We found that the detection ranges of the antigen obtained with nanoparticles of different sizes were different because the amount of antibody on nanoparticles of 10 nm was about one order of magnitude higher than that on nanoparticles of 30 nm. When 10 nm nanoparticle was used as probe, the upper limit of detection was 40.00 μg mL -1 , and the analytical sensitivity was 1.81 μg mL -1 . When 30 nm nanoparticle was used, the upper limit of detection was 3.00 μg mL -1 , and the sensitivity was 0.014 and 0.13 μg mL -1 depending on the ratio of nanoparticle to antibody. Graphical abstract Schematic diagram of procedure and ESR spectra.

  16. Electronic and optical properties of antiferromagnetic iron doped NiO - A first principles study

    Science.gov (United States)

    Petersen, John E.; Twagirayezu, Fidele; Scolfaro, Luisa M.; Borges, Pablo D.; Geerts, Wilhelmus J.

    2017-05-01

    Antiferromagnetic NiO is a candidate for next generation high-speed and scaled RRAM devices. Here, electronic and optical properties of antiferromagnetic NiO: Fe 25% in the rock salt structure are studied and compared to intrinsic NiO. From density of states and complex dielectric function analysis, the first optical transition is found to be at lower frequency than intrinsic NiO due to an Fe impurity level being the valence band maximum. The resulting effects on refractive index, reflectivity, absorption, optical conductivity and loss function for Fe-doped NiO are compared to those of intrinsic NiO, and notable differences are analyzed. The electronic component of the static dielectric constant of NiO: Fe 25% is calculated to be about 2% less than that of intrinsic NiO.

  17. Comparison between POES energetic electron precipitation observations and riometer absorptions: Implications for determining true precipitation fluxes

    Science.gov (United States)

    Rodger, Craig J.; Kavanagh, Andrew J.; Clilverd, Mark A.; Marple, Steve R.

    2013-12-01

    electron precipitation (EEP) impacts the chemistry of the middle atmosphere with growing evidence of coupling to surface temperatures at high latitudes. To better understand this link, it is essential to have realistic observations to properly characterize precipitation and which can be incorporated into chemistry-climate models. The Polar-orbiting Operational Environmental Satellite (POES) detectors measure precipitating particles but only integral fluxes and only in a fraction of the bounce loss cone. Ground-based riometers respond to precipitation from the whole bounce loss cone; they measure the cosmic radio noise absorption (CNA), a qualitative proxy with scant direct information on the energy flux of EEP. POES observations should have a direct relationship with ΔCNA and comparing the two will clarify their utility in studies of atmospheric change. We determined ionospheric changes produced by the EEP measured by the POES spacecraft in ~250 overpasses of an imaging riometer in northern Finland. The ΔCNA modeled from the POES data is 10-15 times less than the observed ΔCNA when the >30 keV flux is reported as ground-based measurements. The discrepancy occurs mostly during periods of low geomagnetic activity, and we contend that weak diffusion is dominating the pitch angle scattering into the bounce loss cone at these times. A correction to the calculation using measurements of the trapped flux considerably reduces the discrepancy and provides further support to our hypothesis that weak diffusion leads to underestimates of the EEP.

  18. First principles electron-correlated calculations of optical absorption in magnesium clusters★

    Science.gov (United States)

    Shinde, Ravindra; Shukla, Alok

    2017-11-01

    In this paper, we report large-scale configuration interaction (CI) calculations of linear optical absorption spectra of various isomers of magnesium clusters Mgn (n = 2-5), corresponding to valence transitions. Geometry optimization of several low-lying isomers of each cluster was carried out using coupled-cluster singles doubles (CCSD) approach, and these geometries were subsequently employed to perform ground and excited state calculations using either the full-CI (FCI) or the multi-reference singles-doubles configuration interaction (MRSDCI) approach, within the frozen-core approximation. Our calculated photoabsorption spectrum of magnesium dimer (Mg2) is in excellent agreement with the experiments both for peak positions, and intensities. Owing to the sufficiently inclusive electron-correlation effects, these results can serve as benchmarks against which future experiments, as well as calculations performed using other theoretical approaches, can be tested. Supplementary material in the form of one pdf fille available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80356-6.

  19. An Electron Microscopy Study of Graphite Growth in Nodular Cast Irons

    Science.gov (United States)

    Laffont, L.; Jday, R.; Lacaze, J.

    2018-04-01

    Growth of graphite during solidification and high-temperature solid-state transformation has been investigated in samples cut out from a thin-wall casting which solidified partly in the stable (iron-graphite) and partly in the metastable (iron-cementite) systems. Transmission electron microscopy has been used to characterize graphite nodules in as-cast state and in samples having been fully graphitized at various temperatures in the austenite field. Nodules in the as-cast material show a twofold structure characterized by an inner zone where graphite is disoriented and an outer zone where it is well crystallized. In heat-treated samples, graphite nodules consist of well-crystallized sectors radiating from the nucleus. These observations suggest that the disoriented zone appears because of mechanical deformation when the liquid contracts during its solidification in the metastable system. During heat-treatment, the graphite in this zone recrystallizes. In turn, it can be concluded that nodular graphite growth mechanism is the same during solidification and solid-state transformation.

  20. Resistivity recovery simulations of electron-irradiated iron: Kinetic Monte Carlo versus cluster dynamics

    International Nuclear Information System (INIS)

    Dalla Torre, J.; Fu, C.-C.; Willaime, F.; Barbu, A.; Bocquet, J.-L.

    2006-01-01

    The isochronal resistivity recovery in high purity α-iron irradiated by electrons was successfully reproduced by a multiscale modelling approach. The stability and mobility of small self-defect clusters determined by ab initio methods were used as input data for an event based Kinetic Monte Carlo (KMC) model, used to explore the defect population evolution during the annealing and to extract the resistivity recovery peaks. In this paper, we investigate the possibility of using an efficient mesoscale model, the Cluster Dynamics (CD), instead of KMC in this approach. The comparison between the two methods for various CD initial conditions shows the importance of spatial correlations between defects, which are neglected in the CD model. However, using appropriate initial conditions, e.g. starting from the concentration of Frenkel pairs after the uncorrelated stage I E , the CD model captures the main characteristics of subsequent defect population evolution, and it can therefore be used for fast and semi-quantitative investigations

  1. A study of point defects created by electron irradiation of dilute iron-carbon alloys

    International Nuclear Information System (INIS)

    Leveque, J.L.

    1969-10-01

    Resistivity and magnetic after effect (m.a.e.) measurements are used to study the influence of carbon atoms on the annealing process of point defects created by electron irradiation (3 MeV) at low temperature (20 deg. K). The presence of the carbon atoms has a strong influence on the recovery sub-stage I E and stage III. For the former, the carbon impurity traps the freely migrating iron interstitial. For the latter the effect is interpreted as being due to formation during annealing, of a carbon vacancy pair. A pronounced m.a.e. band is attributed to the reorientation of this carbon vacancy complex. All these results are coherent with the interpretation of a low temperature migrating free interstitial. (author) [fr

  2. Dry reforming of methane with CO2 on an electron-activated iron catalytic bed.

    Science.gov (United States)

    Labrecque, Raynald; Lavoie, Jean-Michel

    2011-12-01

    A preliminary experimental investigation of dry reforming of methane with carbon dioxide, that has been performed on an iron bed activated with an electric current is reported. Operating conditions for the reaction included temperature ranging from 700 to 800° C and pressure close to 1 atm. The reaction, involving an excess of pure methane and carbon dioxide, was performed with and without addition of water vapour, provided by hot water saturation of the gaseous feed. According to syngas compositions, the electron flow has a dramatic effect on the conversion of both methane and carbon dioxide. It was shown also that hot water saturation of the CO(2) and CH(4) mixture allowed very good conversion, giving a syngas with a composition very close to what was expected from equilibrium calculations. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Electronic structure of nanoscale Cu/Pt alloys: A combined X-ray diffraction and X-ray absorption investigations

    International Nuclear Information System (INIS)

    Chen Xing; Chu Wangsheng; Cai Quan; Xia Dingguo; Wu Zhonghua; Wu Ziyu

    2006-01-01

    PVP-protected Cu/Pt clusters were prepared by glycol/water reduction method and characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD) and absorption spectra. TEM and XRD analysis show that the Cu/Pt clusters with different molar ratio have fcc structure with particle size of about 4 nm, while the lattice parameters in these clusters reduce with increasing Cu concentration. From the X-ray absorption near edge structure (XANES) at Cu-K edge and Pt-L 2,3 edge, we demonstrate that the d-electronic states of Cu and Pt are affected by the local environment as a function of Cu/Pt molar ratio. With increasing Cu concentration, Pt loses a fraction of 5d electrons and the hybridization between p- and d-states at Cu sites is enhanced

  4. Electronic structure of nanoscale Cu/Pt alloys: A combined X-ray diffraction and X-ray absorption investigations

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xing [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); Graduate School of the Chinese Academy of Sciences, 100864 Beijing (China); Chu Wangsheng [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); University of Science and Technology of China, Hefei, 230036 (China); Cai Quan [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); Graduate School of the Chinese Academy of Sciences, 100864 Beijing (China); Xia Dingguo [College of Environmental and Energy Engineering, Beijing University of Technology, 100022 Beijing (China); Wu Zhonghua [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); Wu Ziyu [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China) and National Center for Nanoscience and Technology (China)]. E-mail: wuzy@ihep.ac.cn

    2006-11-15

    PVP-protected Cu/Pt clusters were prepared by glycol/water reduction method and characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD) and absorption spectra. TEM and XRD analysis show that the Cu/Pt clusters with different molar ratio have fcc structure with particle size of about 4 nm, while the lattice parameters in these clusters reduce with increasing Cu concentration. From the X-ray absorption near edge structure (XANES) at Cu-K edge and Pt-L{sub 2,3} edge, we demonstrate that the d-electronic states of Cu and Pt are affected by the local environment as a function of Cu/Pt molar ratio. With increasing Cu concentration, Pt loses a fraction of 5d electrons and the hybridization between p- and d-states at Cu sites is enhanced.

  5. Study of electron transition energies between anions and cations in spinel ferrites using differential UV–vis absorption spectra

    International Nuclear Information System (INIS)

    Xue, L.C.; Wu, L.Q.; Li, S.Q.; Li, Z.Z.; Tang, G.D.; Qi, W.H.; Ge, X.S.; Ding, L.L.

    2016-01-01

    It is very important to determine electron transition energies (E_t_r) between anions and different cations in order to understand the electrical transport and magnetic properties of a material. Many authors have analyzed UV–vis absorption spectra using the curve (αhν)"2 vs E, where α is the absorption coefficient and E(=hν) is the photon energy. Such an approach can give only two band gap energies for spinel ferrites. In this paper, using differential UV–vis absorption spectra, dα/dE vs E, we have obtained electron transition energies (E_t_r) between the anions and cations, Fe"2"+ and Fe"3"+ at the (A) and [B] sites and Ni"2"+ at the [B] sites for the (A)[B]_2O_4 spinel ferrite samples Co_xNi_0_._7_−_xFe_2_._3O_4 (0.0≤x≤0.3), Cr_xNi_0_._7Fe_2_._3_−_xO_4 (0.0≤x≤0.3) and Fe_3O_4. We suggest that the differential UV–vis absorption spectra should be accepted as a general analysis method for determining electron transition energies between anions and cations.

  6. Effect of interdiffusion and external magnetic field on electronic states and light absorption in Gaussian-shaped double quantum ring

    Science.gov (United States)

    Aziz-Aghchegala, V. L.; Mughnetsyan, V. N.; Kirakosyan, A. A.

    2018-02-01

    The effect of interdiffusion and magnetic field on confined states of electron and heavy hole as well as on interband absorption spectrum in a Ga1-xAlxAs/GaAs Gaussian-shaped double quantum ring are investigated. It is shown that both interdiffusion and magnetic field lead to the change of the charge carriers' quantum states arrangement by their energies. The oscillating behavior of the electron ground state energy as a function of magnetic field induction gradually disappears with the increase of diffusion parameter due to the enhanced tunneling of electron to the central region of the ring. For the heavy hole the ground state energy oscillations are not observable in the region of the values of magnetic field induction B = 0 - 10 T . For considered transitions both the magnetic field and the interdiffusion lead to a blue-shift of the absorption spectrum and to decreasing of the absorption intensity. The obtained results indicate on the opportunity of purposeful manipulation of energy states and absorption spectrum of a Gaussian-shaped double quantum ring by means of the post growth annealing and the external magnetic field.

  7. Soft x-ray absorption spectroscopy on Co doped ZnO: structural distortions and electronic structure

    International Nuclear Information System (INIS)

    Kowalik, I A; Guziewicz, E; Godlewski, M; Arvanitis, D

    2016-01-01

    We present soft x-ray absorption spectra from a series of Co doped ZnO films. We discuss systematic variations of the Co L-edge white line intensity and multiplet features for this series of samples. We document sizeable differences in the electronic state of the Co ionic cores, as well as in the local environment of the host lattice atoms, characterised by means of x-ray absorption spectra at the O K-edge and Zn L-edges. Model calculations allow to correlate the observed effects to small structural distortions of the ZnO lattice. (paper)

  8. Summary of radiation-induced transient absorption and recovery in fiber optic waveguides. [Pulsed electrons and x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Skoog, C.D.

    1976-11-01

    The absorption induced in fiber optic waveguides by pulsed electron and X-ray radiation has been measured as a function of optical wavelength from 450 to 950 nm, irradiation temperature from -54 to 71/sup 0/C, and dose from 1 to 500 krads. The fibers studied are Ge-doped silica core fibers (Corning Low Loss), ''pure'' vitreous silica core fibers (Schott, Bell Laboratories, Fiberoptic Cable Corp., and Valtec Fiberoptics), polymethyl-methacrylate core fibers (DuPont CROFON and PFX), and polystyrene core fibers (International Fiber Optics and Polyoptics). Models that have been developed to account for the observed absorption recovery are also summarized.

  9. Theoretical study of electronic absorption spectroscopy of propadienylidene molecule vis-â-vis the observed diffuse interstellar bands

    International Nuclear Information System (INIS)

    Reddy, Samala Nagaprasad; Mahapatra, S.

    2012-01-01

    Highlights: ► Theoretical study of spectroscopy and dynamics of electronically excited l-C 3 H 2 . ► Construction of ab initio electronic potential energy and diabatic coupling surfaces. ► First principles study of nuclear dynamics on excited electronic states. ► Findings reveal l-C 3 H 2 is a potential molecular carrier of diffuse interstellar bands. ► Electronically excited l-C 3 H 2 decays by ultrafast nonradiative internal conversion. -- Abstract: Observation of broad and diffuse interstellar bands (DIBs) at 4881 Å and 5440 Å assigned to the optical absorption spectrum of Y-shaped propadienylidene (H 2 C=C=C:) molecule is theoretically examined in this paper. This molecule apparently absorbs in the same wavelength region as the observed DIBs and was suggested to be a potential carrier of these DIBs. This assignment mostly relied on the experimental data from radioastronomy and laboratory measurements. Motivated by these available experimental data we attempt here a theoretical study and investigate the detailed electronic structure and nuclear dynamics underlying the electronic absorption bands of propadienylidene molecule. Our results show that this molecule indeed absorbs in the wavelength region of the recorded DIBs. Strong nonadiabatic coupling between its energetically low-lying electronic states plays major role, initiates ultrafast internal conversion and contributes to the spectral broadening. Theoretical findings are finally compared with the available experimental and theoretical data and discussed in connection with the recorded DIBs.

  10. Morphology and electronic structure of the oxide shell on the surface of iron nanoparticles.

    Science.gov (United States)

    Wang, Chongmin; Baer, Donald R; Amonette, James E; Engelhard, Mark H; Antony, Jiji; Qiang, You

    2009-07-01

    An iron (Fe) nanoparticle exposed to air at room temperature will be instantly covered by an oxide shell that is typically approximately 3 nm thick. The nature of this native oxide shell, in combination with the underlying Fe(0) core, determines the physical and chemical behavior of the core-shell nanoparticle. One of the challenges of characterizing core-shell nanoparticles is determining the structure of the oxide shell, that is, whether it is FeO, Fe(3)O(4), gamma-Fe(2)O(3), alpha-Fe(2)O(3), or something else. The results of prior characterization efforts, which have mostly used X-ray diffraction and spectroscopy, electron diffraction, and transmission electron microscopic imaging, have been framed in terms of one of the known Fe-oxide structures, although it is not necessarily true that the thin layer of Fe oxide is a known Fe oxide. In this Article, we probe the structure of the oxide shell on Fe nanoparticles using electron energy loss spectroscopy (EELS) at the oxygen (O) K-edge with a spatial resolution of several nanometers (i.e., less than that of an individual particle). We studied two types of representative particles: small particles that are fully oxidized (no Fe(0) core) and larger core-shell particles that possess an Fe core. We found that O K-edge spectra collected for the oxide shell in nanoparticles show distinct differences from those of known Fe oxides. Typically, the prepeak of the spectra collected on both the core-shell and the fully oxidized particles is weaker than that collected on standard Fe(3)O(4). Given the fact that the origin of this prepeak corresponds to the transition of the O 1s electron to the unoccupied state of O 2p hybridized with Fe 3d, a weak pre-edge peak indicates a combination of the following four factors: a higher degree of occupancy of the Fe 3d orbital; a longer Fe-O bond length; a decreased covalency of the Fe-O bond; and a measure of cation vacancies. These results suggest that the coordination configuration in

  11. Stochasticity of the energy absorption in the electron cyclotron resonance; Estocasticidad de la absorcion de energia en la resonancia electron-ciclotronica

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez T, C. [Departamento de Fisica, ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Hernandez A, O

    1998-07-01

    The energy absorption mechanism in cyclotron resonance of the electrons is a present problem, since it could be considered from the stochastic point of view or this related with a non-homogeneous but periodical of plasma spatial structure. In this work using the Bogoliubov average method for a multi periodical system in presence of resonances, the drift equations were obtained in presence of a RF field for the case of electron cyclotron resonance until first order terms with respect to inverse of its cyclotron frequency. The absorbed energy equation is obtained on part of electrons in a simple model and by drift method. It is showed the stochastic character of the energy absorption. (Author)

  12. Nutritional iron deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.; Hurrell, R.F.

    2007-01-01

    Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming

  13. Effect of microplastic deformation on the electron ultrasonic absorption in high-purity molybdenum monocrystals

    International Nuclear Information System (INIS)

    Pal'-Val', P.P.; Kaufmann, Kh.-J.

    1983-01-01

    The low temperature (100-6 K) linear absorption of ultrasound (88 kHz) by high purity molybdenum single crystals have been studied. Both unstrained samples and samples sub ected to microplastic deformation (epsilon 0 approximately 10 -4 , during 10 min, at 6 K. A new relaxation peak of absorption at 10 K has been found in strained samples

  14. Electronic absorption spectrum of copper-doped magnesium potassium phosphate hexahydrate

    Science.gov (United States)

    Rao, S. N.; Sivaprasad, P.; Reddy, Y. P.; Rao, P. S.

    1992-04-01

    The optical absorption and EPR spectra of magnesium potassium phosphate hexahydrate (MPPH) doped with copper ions are recorded both at room and liquid nitrogen temperatures. The spectrum is characteristic of Cu2+ in tetragonal symmetry. The spin-Hamiltonian parameters and molecular orbital coefficients are evaluated. A correlation between EPR and optical absorption studies is drawn.

  15. Mechanism of redox reactions induced by light and electron pulse in solutions of mixed ligand iron(II) complex cyanides

    International Nuclear Information System (INIS)

    Horvath, A.; Szoeke, J.; Wojnarovits, L.

    1991-01-01

    Redox reactions induced by light and electron pulse have been studied in aqueous solutions of mixed ligand iron(II) complex cyanides. The short lived intermediates have been identified by time resolved specroscopy, the results of detailed kinetic analysis have been discussed. (author) 6 refs.; 3 figs.; 2 tabs

  16. Sequential Proton Loss Electron Transfer in Deactivation of Iron(IV) Binding Protein by Tyrosine Based Food Components

    DEFF Research Database (Denmark)

    Tang, Ning; Skibsted, Leif Horsfelt

    2017-01-01

    The iron(IV) binding protein ferrylmyoglobin, MbFe(IV)=O, was found to be reduced by tyrosine based food components in aqueous solution through a sequential proton loss electron transfer reaction mechanism without binding to the protein as confirmed by isothermal titration calorimetry. Dopamine a...

  17. Absorptive Capacities of Local Enterprises from the Electric-Electronics Sector In the State of Tamaulipas, Mexico

    Directory of Open Access Journals (Sweden)

    Francisco García Fernández

    2012-02-01

    Full Text Available The paper analyzes the absorptive capacities of a group of enterprises from the electric-electronics sector in the state of Tamaulipas Mexico. First, the literature on absorptive capabilities is reviewed, adopting an evolutionist approach. Then, an analysis of the sector is carried out in order to verify the recent changes made in various indicators – value of the total products by the selected states, job generation and productivity rates – based on data from the last three economic censuses. Finally, an analysis of the three selected enterprises’ absorptive capacities is addressed from a case study perspective, making our own interpretation of the construct based on the integration of the different analyzed proposals.

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... an MCV of less than 80 femtoliters (fL). Prevention strategies If you have certain risk factors , such ... drinking black tea, which reduces iron absorption. Other treatments If you have chronic kidney disease and iron- ...

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... C to help your body absorb iron. Avoid drinking black tea, which reduces iron absorption. Other treatments ... improve health through research and scientific discovery. Improving health with current research Learn about the following ways ...

  20. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... also often take other medicines—such as proton pump inhibitors, anticoagulants, or blood thinners—that may cause iron-deficiency anemia. Proton pump inhibitors interfere with iron absorption, and blood thinners ...

  1. 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

    NARCIS (Netherlands)

    Zimmermann, M.B.; Biebinger, R.; Egli, I.; Zeder, C.; Hurrell, R.F.

    2011-01-01

    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

  2. Study to determine the content of vanadium, aluminum, nickel, sodium, iron and copper in a catalytic cracking catalyst, by using Atomic Absorption Spectrometry

    International Nuclear Information System (INIS)

    Gomez, J.; Alonso, A.; Tumbarell, O.; Bustanmete, E.

    2003-01-01

    Atomic Absorption Spectrometry (AAS), has the advantage of its simplicity, speed and low cost. All this, together with its high sensibility and selectivity, makes the AAS one the most widely used analytic techniques. The present work shows, the study to determine the content of vanadium, aluminum, nickel, sodium, iron and copper in a catalytic cracking catalyst of a refinery, by using this technique. The results are compared to those of two laboratories which use the ICP-AES and AAS techniques and shows the processing of the statistics with the use of the t of Student and the F of Snedecor. The results using different methods are also shown as well as the recommended application of this results in the chemical characterization of this type of catalysts

  3. Enhanced carrier collection efficiency and reduced quantum state absorption by electron doping in self-assembled quantum dot solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tian, E-mail: tianlee@umd.edu, E-mail: dage@ece.umd.edu; Dagenais, Mario, E-mail: tianlee@umd.edu, E-mail: dage@ece.umd.edu [Department of Electrical Engineering, University of Maryland, College Park, Maryland 20742 (United States); Lu, Haofeng; Fu, Lan; Tan, Hark Hoe; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia)

    2015-02-02

    Reduced quantum dot (QD) absorption due to state filling effects and enhanced electron transport in doped QDs are demonstrated to play a key role in solar energy conversion. Reduced QD state absorption with increased n-doping is observed in the self-assembled In{sub 0.5}Ga{sub 0.5}As/GaAs QDs from high resolution below-bandgap external quantum efficiency (EQE) measurement, which is a direct consequence of the Pauli exclusion principle. We also show that besides partial filling of the quantum states, electron-doping produces negatively charged QDs that exert a repulsive Coulomb force on the mobile electrons, thus altering the electron trajectory and reducing the probability of electron capture, leading to an improved collection efficiency of photo-generated carriers, as indicated by an absolute above-bandgap EQE measurement. The resulting redistribution of the mobile electron in the planar direction is further validated by the observed photoluminescence intensity dependence on doping.

  4. Experimental and theoretical study of electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Festa, Floriane

    2013-01-01

    Matter in extreme conditions belongs to Warm Dense Matter regime which lays between dense plasma regime and condensed matter. This regime is still not well known, indeed it is very complex to generate such plasma in the laboratory to get experimental data and validate models. The goal of this thesis is to study electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy. Experimentally aluminum has reached high densities and high temperatures, up to now unexplored. An X-ray source has also been generated to probe highly compressed aluminum. Two spectrometers have recorded aluminum absorption spectra and aluminum density and temperature conditions have been deduced thanks to optical diagnostics. Experimental spectra have been compared to ab initio spectra, calculated in the same conditions. The theoretical goal was to validate the calculation method in high densities and high temperatures regime with the study of K-edge absorption modifications. We also used absorption spectra to study the metal-non metal transition which takes place at low density (density ≤ solid density). This transition could be study with electronic structure modifications of the system. (author) [fr

  5. Correlated single-crystal electronic absorption spectroscopy and X-ray crystallography at NSLS beamline X26-C

    International Nuclear Information System (INIS)

    Orville, A.M.; Buono, R.; Cowan, M.; Heroux, A.; Shea-McCarthy, G.; Schneider, D.K.; Skinner, J.M.; Skinner, M.J.; Stoner-Ma, D.; Sweet, R.M.

    2011-01-01

    The research philosophy and new capabilities installed at NSLS beamline X26-C to support electronic absorption and Raman spectroscopies coupled with X-ray diffraction are reviewed. This beamline is dedicated full time to multidisciplinary studies with goals that include revealing the relationship between the electronic and atomic structures in macromolecules. The beamline instrumentation has been fully integrated such that optical absorption spectra and X-ray diffraction images are interlaced. Therefore, optical changes induced by X-ray exposure can be correlated with X-ray diffraction data collection. The installation of Raman spectroscopy into the beamline is also briefly reviewed. Data are now routinely generated almost simultaneously from three complementary types of experiments from the same sample. The beamline is available now to the NSLS general user population.

  6. Local versus global electronic properties of chalcopyrite alloys: X-ray absorption spectroscopy and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Sarmiento-Pérez, Rafael; Botti, Silvana, E-mail: silvana.botti@univ-lyon1.fr [Institut Lumière Matière and ETSF, UMR5306 Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne Cedex (France); Schnohr, Claudia S., E-mail: c.schnohr@uni-jena.de [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Lauermann, Iver [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Rubio, Angel [Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Departamento de Física de Materiales, Centro de Física de Materiales CSIC-MPC and DIPC, Universidad del País Vasco UPV/EHU, Avenida de Tolosa 72, E-20018 San Sebastián (Spain); Fritz Haber Institute, Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany); Johnson, Benjamin, E-mail: benjamin.johnson@alumni.tu-berlin.de [Fritz Haber Institute, Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany)

    2014-09-07

    Element-specific unoccupied electronic states of Cu(In, Ga)S{sub 2} were studied as a function of the In/Ga ratio by combining X-ray absorption spectroscopy with density functional theory calculations. The S absorption edge shifts with changing In/Ga ratio as expected from the variation of the band gap. In contrast, the cation edge positions are largely independent of composition despite the changing band gap. This unexpected behavior is well reproduced by our calculations and originates from the dependence of the electronic states on the local atomic environment. The changing band gap arises from a changing spatial average of these localized states with changing alloy composition.

  7. Estimation of perimortal percent carboxy-heme in nonstandard postmortem specimens using analysis of carbon monoxide by GC/MS and iron by flame atomic absorption spectrophotometry.

    Science.gov (United States)

    Middleberg, R A; Easterling, D E; Zelonis, S F; Rieders, F; Rieders, M F

    1993-01-01

    In decomposed, formalin-fixed, embalmed, exhumed, and some fire-dried cases in which normal blood is unavailable, the usual methods for determination of carboxyhemoglobin saturation frequently fail. To address these specimens, a method utilizing both gas chromatography/mass spectrometric (GC/MS) determination of carbon monoxide (CO) and flame atomic absorption spectrophotometry (FAAS) determination of iron (Fe), in the same specimen, was developed. The method is reported here, along with its application to seven pertinent forsensic death investigations. The CO analytical methodology involves acid liberation of the gas from the specimen aliquot in a headspace vial. After heating and equilibrating, a sample of the headspace vapor is injected into the GC/MS system with a gastight syringe. Quantitation is achieved by standard addition comparison utilizing the ideal gas law equation. Iron is quantified by FAAS analysis of the same aliquot used for the CO determination, following nitric acid digestion. The concentration is determined by comparison to a standard curve. A formula for determining the minimum percent carboxy-heme saturation was derived by using the ratio of the amount of CO to the amount of Fe in the aliquot analyzed. Tissue types analyzed include spleen, liver, muscle, dried blood, and unspecified decomposed tissue.

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

    OpenAIRE

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

    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, ?-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 ?-Fe2O3 to Fe3O4 via ?-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide ...

  9. Improvement of the intrinsic time resolving power of the Cologne iron-free orange type electron spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Regis, J.-M.; Materna, Th.; Pascovici, G.; Christen, S.; Dewald, A.; Fransen, C.; Jolie, J.; Petkov, P.; Zell, K. O. [Institut fuer Kernphysik (IKP), Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany)

    2010-11-15

    Conversion electron spectroscopy represents an important tool for nuclear structure analysis of medium and heavy nuclei. Two iron-free magnetic electron spectrometers of the orange type have been installed at the Institute for Nuclear Physics of the University of Cologne. The very large transmission of 15% and the very good energy resolution of 1% makes the iron-free orange spectrometer a powerful instrument. By means of fast timing techniques, lifetimes of nuclear excited states can be measured with an accuracy better than 20 ps. For the first time, the energy dependent centroid position of prompt events yielding the time-walk characteristics (the prompt curve) of the orange spectrometer fast timing setup has been measured using prompt secondary {delta}-electrons generated in a pulsed beam experiment. The prompt curve calibrated as a function of energy allows precise lifetime determination down to a few tens of picoseconds by the use of the centroid shift method.

  10. Time-dependent radiolytic yields at room temperature and temperature-dependent absorption spectra of the solvated electrons in polyols

    International Nuclear Information System (INIS)

    Lin Mingzhang; Mostafavi, M.; Lampre, I.; Muroya, Y.; Katsumura, Y.

    2007-01-01

    The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900, 970, and 1000 mol -1 ·m 2 for 1,2-ethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (13PD), respectively. These values are two-third or three-fourth of the value usually reported in the published report. Picosecond pulse radiolysis studies have aided in depicting the radiolytic yield of the solvated electron in these solvents as a function of time from picosecond to microsecond. The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution. The temperature dependent absorption spectra of the solvated electron in 12ED, 12PD, and 13PD have been also investigated. In all the three solvents, the optical spectra shift to the red with increasing temperature. While the shape of the spectra does not change in 13PD, a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures. (authors)

  11. The Iron-Sulfur Cluster of Electron Transfer Flavoprotein-ubiquinone Oxidoreductase (ETF-QO) is the Electron Acceptor for Electron Transfer Flavoprotein†

    Science.gov (United States)

    Swanson, Michael A.; Usselman, Robert J.; Frerman, Frank E.; Eaton, Gareth R.; Eaton, Sandra S.

    2011-01-01

    Electron-transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) accepts electrons from electron-transfer flavoprotein (ETF) and reduces ubiquinone from the ubiquinone-pool. It contains one [4Fe-4S]2+,1+ and one FAD, which are diamagnetic in the isolated oxidized enzyme and can be reduced to paramagnetic forms by enzymatic donors or dithionite. In the porcine protein, threonine 367 is hydrogen bonded to N1 and O2 of the flavin ring of the FAD. The analogous site in Rhodobacter sphaeroides ETF-QO is asparagine 338. Mutations N338T and N338A were introduced into the R. sphaeroides protein by site-directed mutagenesis to determine the impact of hydrogen bonding at this site on redox potentials and activity. The mutations did not alter the optical spectra, EPR g-values, spin-lattice relaxation rates, or the [4Fe-4S]2+,1+ to FAD point-dipole interspin distances. The mutations had no impact on the reduction potential for the iron-sulfur cluster, which was monitored by changes in the continuous wave EPR signals of the [4Fe-4S]+ at 15 K. For the FAD semiquinone, significantly different potentials were obtained by monitoring the titration at 100 or 293 K. Based on spectra at 293 K the N338T mutation shifted the first and second midpoint potentials for the FAD from +47 mV and −30 mV for wild type to −11 mV and −19 mV, respectively. The N338A mutation decreased the potentials to −37 mV and −49 mV. Lowering the midpoint potentials resulted in a decrease in the quinone reductase activity and negligible impact on disproportionation of ETF1e− catalyzed by ETF-QO. These observations indicate that the FAD is involved in electron transfer to ubiquinone, but not in electron transfer from ETF to ETF-QO. Therefore the iron-sulfur cluster is the immediate acceptor from ETF. PMID:18672901

  12. Ab-initio simulations of pressure effects on structural and electronic properties of iron based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Tomic, Milan

    2013-07-01

    The ab-initio molecular dynamics framework has been the cornerstone of computational solid state physics in the last few decades. Although it is already a mature field it is still rapidly developing to accommodate the growth in solid state research as well as to efficiently utilize the increase in computing power. Starting from the first principles, the ab-initio molecular dynamics provides essential information about structural and electronic properties of matter under various external conditions. In this thesis we use the ab-initio molecular dynamics to study the behavior of BaFe{sub 2}As{sub 2} and CaFe{sub 2}As{sub 2} under the application of external pressure. BaFe{sub 2}As{sub 2} and CaFe{sub 2}As{sub 2} belong to the family of iron based superconductors which are a novel and promising superconducting materials. The application of pressure is one of two key methods by which electronic and structural properties of iron based superconductors can be modified, the other one being doping (or chemical pressure). In particular, it has been noted that pressure conditions have an important effect, but their exact role is not fully understood. To better understand the effect of different pressure conditions we have performed a series of ab-initio simulations of pressure application. In order to apply the pressure with arbitrary stress tensor we have developed a method based on the Fast Inertial Relaxation Engine, whereby the unit cell and the atomic positions are evolved according to the metadynamical equations of motion. We have found that the application of hydrostatic and c axis uniaxial pressure induces a phase transition from the magnetically ordered orthorhombic phase to the non-magnetic collapsed tetragonal phase in both BaFe{sub 2}As{sub 2} and CaFe{sub 2}As{sub 2}. In the case of BaFe{sub 2}As{sub 2}, an intermediate tetragonal non-magnetic tetragonal phase is observed in addition. Application of the uniaxial pressure parallel to the c axis reduces the

  13. Ab-initio simulations of pressure effects on structural and electronic properties of iron based superconductors

    International Nuclear Information System (INIS)

    Tomic, Milan

    2013-01-01

    The ab-initio molecular dynamics framework has been the cornerstone of computational solid state physics in the last few decades. Although it is already a mature field it is still rapidly developing to accommodate the growth in solid state research as well as to efficiently utilize the increase in computing power. Starting from the first principles, the ab-initio molecular dynamics provides essential information about structural and electronic properties of matter under various external conditions. In this thesis we use the ab-initio molecular dynamics to study the behavior of BaFe 2 As 2 and CaFe 2 As 2 under the application of external pressure. BaFe 2 As 2 and CaFe 2 As 2 belong to the family of iron based superconductors which are a novel and promising superconducting materials. The application of pressure is one of two key methods by which electronic and structural properties of iron based superconductors can be modified, the other one being doping (or chemical pressure). In particular, it has been noted that pressure conditions have an important effect, but their exact role is not fully understood. To better understand the effect of different pressure conditions we have performed a series of ab-initio simulations of pressure application. In order to apply the pressure with arbitrary stress tensor we have developed a method based on the Fast Inertial Relaxation Engine, whereby the unit cell and the atomic positions are evolved according to the metadynamical equations of motion. We have found that the application of hydrostatic and c axis uniaxial pressure induces a phase transition from the magnetically ordered orthorhombic phase to the non-magnetic collapsed tetragonal phase in both BaFe 2 As 2 and CaFe 2 As 2 . In the case of BaFe 2 As 2 , an intermediate tetragonal non-magnetic tetragonal phase is observed in addition. Application of the uniaxial pressure parallel to the c axis reduces the critical pressure of the phase transition by an order of magnitude

  14. Low-field microwave absorption and magnetoresistance in iron nanostructures grown by electrodeposition on n-type lightly doped silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Felix, J.F. [Universidade Federal de Viçosa-UFV, Departamento de Física, 36570-900 Viçosa, MG (Brazil); Universidade de Brasília-UnB, Instituto de Física, Núcleo de Física Aplicada, 70910-900 Brasília, DF (Brazil); Figueiredo, L.C. [Universidade de Brasília-UnB, Instituto de Física, Núcleo de Física Aplicada, 70910-900 Brasília, DF (Brazil); Mendes, J.B.S. [Universidade Federal de Viçosa-UFV, Departamento de Física, 36570-900 Viçosa, MG (Brazil); Morais, P.C. [Universidade de Brasília-UnB, Instituto de Física, Núcleo de Física Aplicada, 70910-900 Brasília, DF (Brazil); Huazhong University of Science and Technology, School of Automation, 430074 Wuhan (China); Araujo, C.I.L. de., E-mail: dearaujo@ufv.br [Universidade de Brasília-UnB, Instituto de Física, Núcleo de Física Aplicada, 70910-900 Brasília, DF (Brazil)

    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. - Highlights: • Electrodeposition of Fe nanostructures on high resistive silicon substrates. • Spin polarized current among clusters through Si suggested by isotropic magnetoresistance. • Low field microwave absorption arising from the sample shape anisotropy. • Contactless magnetoresistive device characterization by resonance measurements.

  15. Electron cyclotron wave absorption by the fast tail generated by the dc electric field in tokamak plasmas

    International Nuclear Information System (INIS)

    Giruzzi, G.; Krivenski, V.; Fidone, I.; Ziebell, L.F.

    1985-03-01

    Wave damping near the electron gyrofrequency in a tokamak plasma with the energetic tail generated by the dc electric field is investigated. The electron tail is computed by a Fokker-Planck initial value code as a function of the relevant parameter Esub(parallel)/Esub(c)=Esub(parallel)Tsub(e)/(2πsub(e)c 3 Λ). It is shown that in most cases of physical interest strong damping of the e-mode occurs for oblique propagation. The results are of relevance for studies of ECRH in present-day tokamaks and in future reactors where a mildly relativistic electron tail is naturally present for large tsub(e). Special emphasis is therefore given to wave absorption for frequencies f significantly below the central electron gyrofrequency, and to the associated rf-driven current

  16. Temperature and isotope effects on the shape of the optical absorption spectrum of solvated electrons in water

    International Nuclear Information System (INIS)

    Jou, F.Y.; Freeman, G.R.

    1979-01-01

    The optical absorption spectra of solvated electrons in H 2 O and D 2 O have been measured at 274, 298, 340, and 380 K. All the spectra were fitted very well with the Gaussian and Lorentzian shape functions at the low- and high-energy sides of the absorption maximum, respectively, excluding the high-energy tail. The spectrum does not shift uniformly with temperature. The temperature coefficient of absorption decreases rapidly with increasing energy on the low-energy side of the absorption maximum, while it changes only slightly on the high-energy side. When the temperature increases the Lorentzian width remains constant, the Gaussian width varies proportionally to T/sup 1/2/, and the spectrum becomes more symmetrical. On going from H 2 O to D 2 O we found that the spectrum at a given A/A/sub max/ shows a shift of +0.05 eV in the low-energy wing. The shift decreases with increasing energy, reaching 0.03 eV at the absorption maximum. On the high-energy side of the band the shift becomes negative at hν > 2.2 eV. The shift on the low-energy side seems to be related to the difference of the zero-point energies of the inter- and intramolecular vibrations. The wavelength dependence of the temperature and isotope effects is consistent with the model that different types of excitation occur on the low- and high-energy sides of the absorption band. The temperature and isotopic dependence of the low-energy side are consistent with its width being due to phonon interactions

  17. EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014 . Scientific Opinion on the substantiation of a health claim related to vitamin C and increasing non-haem iron absorption pursuant to Article 14 of Regulation (EC ) No 1924/2006

    DEFF Research Database (Denmark)

    Tetens, Inge

    to deliver an opinion on the scientific substantiation of a health claim related to vitamin C and increasing non haem iron absorption. The food constituent, vitamin C, which is the subject of the health claim, is sufficiently characterised. Increasing non haem iron absorption is a beneficial physiological...... effect for infants and young children. A claim on vitamin C and increasing non haem iron absorption in the general population has already been assessed by the Panel with a favourable outcome. The Panel considers that the role of vitamin C in increasing non haem iron absorption applies to all ages......, including infants and young children (from birth to three years). The Panel concludes that a cause and effect relationship has been established between the dietary intake of vitamin C and increasing non haem iron absorptions....

  18. Surface plasmon resonance enhanced light absorption and wavelength tuneable in gold-coated iron oxide spherical nanoparticle

    Science.gov (United States)

    Dasri, Thananchai; Chingsungnoen, Artit

    2018-06-01

    Surface plasmon in nano-sized particles, such as gold, silver, copper and their composites, has recently attracted a great deal of attention due to its possible uses in many applications, especially in life sciences. It is desirable for application devices with a tenability of surface plasmon wavelength and optical properties enhancement. This article presents enhanced optical light absorption and tunable wavelength in gold-coated magnetite (Fe3O4@Au core-shell) nanoparticles embedded in water using the theoretical method of discrete dipole approximation (DDA). The absorption spectra in the wavelengths from 350 to 900 nm were found to be the spectra obtained from Fe3O4@Au core-shell nanoparticles, and when compared with pure Fe3O4 nanoparticles, the surface plasmon resonance can be enhanced and tuned over the entire visible spectrum (viz. 350-800 nm) of the electromagnetic spectrum by varying the Au shell thickness (2-5 nm). Similarly, the Faraday rotation spectra can also be obtained.

  19. Determination of iron in seawater by electrothermal atomic absorption spectrometry and atomic fluorescence spectrometry: A comparative study

    International Nuclear Information System (INIS)

    Cabon, J.Y.; Giamarchi, P.; Le Bihan, A.

    2010-01-01

    Two methods available for direct determination of total Fe in seawater at low concentration level have been examined: electrothermal atomization atomic absorption spectrometry (ETAAS) and electrothermal atomization laser excited atomic fluorescence spectrometry (ETA-LEAFS). In a first part, we have optimized experimental conditions of ETAAS (electrothermal program, matrix chemical modification) for the determination of Fe in seawater by minimizing the chemical interference effects and the magnitude of the simultaneous background absorption signal. By using the best experimental conditions, a detection limit of 80 ng L -1 (20 μL, 3σ) for total Fe concentration was obtained by ETAAS. Using similar experimental conditions (electrothermal program, chemical modification), we have optimized experimental conditions for the determination of Fe by LEAFS. The selected experimental conditions for ETA-LEAFS: excitation wavelength (296.69 nm), noise attenuation and adequate background correction led to a detection limit (3σ) of 3 ng L -1 (i.e. 54 pM) for total Fe concentration with the use a 20 μL seawater sample. For the two methods, concentration values obtained for the analysis of Fe in a NASS-5 (0.2 μg L -1 ) seawater sample were in good agreement with the certified values.

  20. Determination of iron in seawater by electrothermal atomic absorption spectrometry and atomic fluorescence spectrometry: a comparative study.

    Science.gov (United States)

    Cabon, J Y; Giamarchi, P; Le Bihan, A

    2010-04-07

    Two methods available for direct determination of total Fe in seawater at low concentration level have been examined: electrothermal atomization atomic absorption spectrometry (ETAAS) and electrothermal atomization laser excited atomic fluorescence spectrometry (ETA-LEAFS). In a first part, we have optimized experimental conditions of ETAAS (electrothermal program, matrix chemical modification) for the determination of Fe in seawater by minimizing the chemical interference effects and the magnitude of the simultaneous background absorption signal. By using the best experimental conditions, a detection limit of 80 ng L(-1) (20 microL, 3sigma) for total Fe concentration was obtained by ETAAS. Using similar experimental conditions (electrothermal program, chemical modification), we have optimized experimental conditions for the determination of Fe by LEAFS. The selected experimental conditions for ETA-LEAFS: excitation wavelength (296.69 nm), noise attenuation and adequate background correction led to a detection limit (3sigma) of 3 ng L(-1) (i.e. 54 pM) for total Fe concentration with the use a 20 microL seawater sample. For the two methods, concentration values obtained for the analysis of Fe in a NASS-5 (0.2 microg L(-1)) seawater sample were in good agreement with the certified values. Copyright 2010 Elsevier B.V. All rights reserved.

  1. A comparison of simultaneous plasma, atomic absorption, and iron colorimetric determinations of major and trace constituents in acid mine waters

    Science.gov (United States)

    Ball, J.W.; Nordstrom, D. Kirk

    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

  2. Scanning electron microscopy and magnetic characterization of iron oxides in solid waste landfill leachate

    International Nuclear Information System (INIS)

    Huliselan, Estevanus Kristian; Bijaksana, Satria; Srigutomo, Wahyu; Kardena, Edwan

    2010-01-01

    Leachate sludge samples were taken from two municipal solid waste sites of Jelekong and Sarimukti in Bandung, Indonesia. Their magnetic mineralogy and granulometry were analyzed to discriminate the sources of magnetic minerals using X-ray diffraction (XRD), scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX) and rock magnetism. SEM-EDX analyses infer that the main magnetic minerals in the leachate sludge are iron oxides. In terms of their morphology, the grains from Jelekong are mostly octahedral and angular, which are similar to the general shapes of magnetic grains from the local soils. The grains from Sarimukti, on the other hand, are dominated by imperfect spherule shapes suggesting the product of combustion processes. Hysteresis parameters verify that the predominant magnetic mineral in leachate sludge is low coercivity ferrimagnetic mineral such as magnetite (Fe 3 O 4 ). Furthermore, comparisons of rock magnetic parameters show that the magnetic minerals of soil samples from Jelekong have higher degree of magnetic pedogenesis indicating higher proportion of superparamagnetic/ultrafine particles than those of soil samples from Sarimukti. The plot of susceptibilities ratio versus coercive force has a great potential to be used as a discriminating tool for determining the source of magnetic minerals.

  3. Final Report: The Impact of Carbonate on Surface Protonation, Electron Transfer and Crystallization Reactions in Iron Oxide Nanoparticles and Colloids

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, David Adams [The University of Alabama

    2013-07-02

    This project addresses key issues of importance in the geochemical behavior of iron oxides and in the geochemical cycling of carbon and iron. For Fe, we are specifically studying the influence of carbonate on electron transfer reactions, solid phase transformations, and the binding of carbonate to reactive sites on the edges of particles. The emphasis on carbonate arises because it is widely present in the natural environment, is known to bind strongly to oxide surfaces, is reactive on the time scales of interest, and has a speciation driven by acid-base reactions. The geochemical behavior of carbonate strongly influences global climate change and CO{sub 2} sequestration technologies. Our goal is to answer key questions with regards to specific site binding, electron transfer reactions, and crystallization reactions of iron oxides that impact both the geochemical cycling of iron and CO{sub 2} species. Our work is focused on the molecular level description of carbonate chemistry in solution including the prediction of isotope fractionation factors. We have also done work on critical atmospheric species.

  4. Influence of Carbon Sources and Electron Shuttles on Ferric Iron Reduction by Cellulomonas sp. Strain ES6

    Energy Technology Data Exchange (ETDEWEB)

    Dr Robin Gerlach; Erin K. Field; Sridhar Viamajala; Brent M. Peyton; William A. Apel; Al B. Cunningham

    2011-09-01

    Microbially reduced iron minerals can reductively transform a variety of contaminants including heavy metals, radionuclides, chlorinated aliphatics, and nitroaromatics. A number of Cellulomonas spp. strains, including strain ES6, isolated from aquifer samples obtained at the U.S. Department of Energy's Hanford site in Washington, have been shown to be capable of reducing Cr(VI), TNT, natural organic matter, and soluble ferric iron [Fe(III)]. This research investigated the ability of Cellulomonas sp. strain ES6 to reduce solid phase and dissolved Fe(III) utilizing different carbon sources and various electron shuttling compounds. Results suggest that Fe(III) reduction by and growth of strain ES6 was dependent upon the type of electron donor, the form of iron present, and the presence of synthetic or natural organic matter, such as anthraquinone-2,6-disulfonate (AQDS) or humic substances. This research suggests that Cellulomonas sp. strain ES6 could play a significant role in metal reduction in the Hanford subsurface and that the choice of carbon source and organic matter addition can allow for independent control of growth and iron reduction activity.

  5. 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.

    Science.gov (United States)

    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 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.

  6. Duodenal Cytochrome b (DCYTB in Iron Metabolism: An Update on Function and Regulation

    Directory of Open Access Journals (Sweden)

    Darius J. R. Lane

    2015-03-01

    Full Text Available Iron and ascorbate are vital cellular constituents in mammalian systems. The bulk-requirement for iron is during erythropoiesis leading to the generation of hemoglobin-containing erythrocytes. Additionally; both iron and ascorbate are required as co-factors in numerous metabolic reactions. Iron homeostasis is controlled at the level of uptake; rather than excretion. Accumulating evidence strongly suggests that in addition to the known ability of dietary ascorbate to enhance non-heme iron absorption in the gut; ascorbate regulates iron homeostasis. The involvement of ascorbate in dietary iron absorption extends beyond the direct chemical reduction of non-heme iron by dietary ascorbate. Among other activities; intra-enterocyte ascorbate appears to be involved in the provision of electrons to a family of trans-membrane redox enzymes; namely those of the cytochrome b561 class. These hemoproteins oxidize a pool of ascorbate on one side of the membrane in order to reduce an electron acceptor (e.g., non-heme iron on the opposite side of the membrane. One member of this family; duodenal cytochrome b (DCYTB; may play an important role in ascorbate-dependent reduction of non-heme iron in the gut prior to uptake by ferrous-iron transporters. This review discusses the emerging relationship between cellular iron homeostasis; the emergent “IRP1-HIF2α axis”; DCYTB and ascorbate in relation to iron metabolism.

  7. Investigation of the electronic structure of high-temperature superconductors and related transition metal oxides with near-edge x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Gerhold, S.

    2001-01-01

    The unoccupied electronic structure and its orbital character has been studied with polarization-dependent near-edge x-ray absorption spectroscopy (NEXAFS) for selected high-temperature superconductors (HTSC) and related transition metal oxides. Although YBa 2 Cu 3 O 7-δ (Y-123) is arguably the best-investigated HTSC a conclusive NEXAFS study on how partial substitution of Cu by other transition metals affects the electronic structure has sorely been missing. The study presented here on a series of well characterized YBa 2 Cu 3-x Fe x O y single crystals shows that the cause for T c suppression is not at all magnetic pair breaking but charge carrier depletion, primarily in the chains; effects from disorder cannot be excluded. Annealing at high oxygen pressure increases along with oxygen content both the hole concentration and T c . Fe 3d-O 2p-derived states contribute prominently to the spectra for all polarizations a few eV above E F . Iron prefers a trivalent state in Y-123; upon reduction a spin transition can be observed. As YBa 2 Cu 3-x Fe x O y single crystals cannot be detwinned it is very difficult to distinguish between contributions from planes and chains to the spectra. In this situation thin films grown with a reduced degree of twinning ('twin-poor') allow more detailed investigations. An extended self-absorption correction was developed for fluorescence yield NEXAFS on epitactical HTSC thin films. Its application to twin-poor Y-123 thin films demonstrates that (apart from the effect of residual twins) the spectral information is equivalent to that of detwinned single crystals for a range of optimum film thicknesses, and this in turn allows to augment the NEXAFS study of YBa 2 Cu 3-x Fe x O y with spectra for corresponding twin-poor thin films. The system Ca 2-x (Sr,La) x RuO 4 is structurally related to the HTSCs; the development of its unoccupied electronic structure with x was investigated in this work, with emphasis on the metal

  8. Optical absorption and electron spin resonance studies of Cu 2 in ...

    Indian Academy of Sciences (India)

    B2O3–As2O3 glasses. N Srinivasa Rao Shashidhar ... K Siva Kumar Syed Rahman. Ceramics and Glasses Volume 28 Issue 6 October 2005 pp 589-592 ... Keywords. Glass transition temperature; ESR; optical absorption; bonding parameters.

  9. Fokker-Planck code for the quasi-linear absorption of electron cyclotron waves in a tokamak plasma

    International Nuclear Information System (INIS)

    Meyer, R.L.; Giruzzi, G.; Krivenski, V.

    1986-01-01

    We present the solution of the kinetic equation describing the quasi-linear evolution of the electron momentum distribution function under the influence of the electron cyclotron wave absorption. Coulomb collisions and the dc electric field in a tokamak plasma. The solution of the quasi-linear equation is obtained numerically using a two-dimensional initial value code following an ADI scheme. Most emphasis is given to the full non-linear and self-consistent problem, namely, the wave amplitude is evaluated at any instant and any point in space according to the actual damping. This is necessary since wave damping is a very sensitive function of the slope of the local momentum distribution function because the resonance condition relates the electron momentum to the location of wave energy deposition. (orig.)

  10. Experimental study of water absorption of electronic components and internal local temperature and humidity into electronic enclosure

    DEFF Research Database (Denmark)

    Conseil, Helene; Jellesen, Morten Stendahl; Ambat, Rajan

    2014-01-01

    Corrosion reliability of electronic products is a key factor for electronics industry, and today there is a large demand for performance reliability in large spans of temperature and humidity during day and night shifts. Corrosion failures are still seen due to the effects of temperature, humidity......, differential humidity, and temperature effects simulating day/night, and the use of desiccants....

  11. Probing the Influence of the Conjugated Structure and Halogen Atoms of Poly-Iron-Phthalocyanine on the Oxygen Reduction Reaction by X-ray Absorption Spectroscopy and Density Functional Theory

    International Nuclear Information System (INIS)

    Peng, Yingxiang; Cui, Lufang; Yang, Shifeng; Fu, Jingjing; Zheng, Lirong; Liao, Yi; Li, Kai; Zuo, Xia; Xia, Dingguo

    2015-01-01

    Metal-phthalocyanine (MPc) macrocyclic catalysts have been perceived as promising alternatives to Pt and Pt-based catalysts for the oxygen reduction reaction (ORR). However, the effect of different MPc molecular structures on the ORR has rarely been reported in depth. Herein, iron-phthalocyanine polymers (poly-FePcs) and multi-walled carbon nanotubes (MWCNTs) composites with different structures were synthesized using microwave method. The relationship between their molecular structure and electrocatalytic activity was fully revealed by density functional theory (DFT) and X-ray fine absorption spectroscopy (XAFS). DFT calculations revealed that the introduction of halogen atoms can increase the ion potential (IP) and the dioxo-binding energy () of the poly-FePcs. Meanwhile, their conjugated structure not only facilitates electronic transmission, but also significantly increases . XAFS analysis indicated that the poly-FePc/MWCNTs composites had a square planar structure and a smaller of phthalocyanine ring (Fe-N 4 structure) skeleton structure radius when a larger conjugated structure or introduced halogen atoms was present. The experimental results suggest that the these changes in properties arising from the different structures of the MPc macrocyclic compounds led to a huge effect on their ORR electrochemical activities, and provide a guide to obtaining promising electrochemical catalysts

  12. Probing the influence of the center atom coordination structure in iron phthalocyanine multi-walled carbon nanotube-based oxygen reduction reaction catalysts by X-ray absorption fine structure spectroscopy

    Science.gov (United States)

    Peng, Yingxiang; Li, Zhipan; Xia, Dingguo; Zheng, Lirong; Liao, Yi; Li, Kai; Zuo, Xia

    2015-09-01

    Three different pentacoordinate iron phthalocyanine (FePc) electrocatalysts with an axial ligand (pyridyl group, Py) anchored to multi-walled carbon nanotubes (MWCNTs) are prepared by a microwave method as high performance composite electrocatalysts (FePc-Py/MWCNTs) for the oxygen reduction reaction (ORR). For comparison, tetracoordinate FePc electrocatalysts without an axial ligand anchored to MWCNTs (FePc/MWCNTs) are assembled in the same way. Ultraviolet-visible spectrophotometry (UV-Vis), Raman spectroscopy (RS), and high-resolution transmission electron microscopy (HRTEM) are used to characterize the obtained electrocatalysts. The electrocatalytic activity of the samples is measured by linear sweep voltammetry (LSV), and the onset potential of all of the FePc-Py/MWCNTs electrocatalysts is found to be more positive than that of their FePc/MWCNTs counterparts. X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy are employed to elucidate the relationship between molecular structure and electrocatalytic activity. XPS indicates that higher concentrations of Fe3+ and pyridine-type nitrogen play critical roles in determining the electrocatalytic ORR activity of the samples. XAFS spectroscopy reveals that the FePc-Py/MWCNTs electrocatalysts have a coordination geometry around Fe that is closer to the square pyramidal structure, a higher concentration of Fe3+, and a smaller phthalocyanine ring radius compared with those of FePc/MWCNTs.

  13. Transmission electron microscopy of carbon-coated and iron-doped titania nanoparticles

    KAUST Repository

    Anjum, Dalaver H.

    2016-08-02

    We present a study on the properties of iron (Fe)-doped and carbon (C)-coated titania (TiO2) nanoparticles (NPs) which has been compiled by using x-ray diffraction (XRD), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). These TiO2 NPs were prepared by using the flame synthesis method. This method allows the simultaneous C coating and Fe doping of TiO2 NPs. XRD investigations revealed that the phase of the prepared NPs was anatase TiO2. Conventional TEM analysis showed that the average size of the TiO2 NPs was about 65 nm and that the NPs were uniformly coated with the element C. Furthermore, from the x-ray energy dispersive spectrometry analysis, it was found that about 8 at.% Fe was present in the synthesized samples. High-resolution TEM (HRTEM) revealed the graphitized carbon structure of the layer surrounding the prepared TiO2 NPs. HRTEM analysis further revealed that the NPs possessed the crystalline structure of anatase titania. Energy-filtered TEM (EFTEM) analysis showed the C coating and Fe doping of the NPs. The ratio of L3 and L2 peaks for the Ti-L23 and Fe-L23 edges present in the core loss electron energy loss spectroscopy (EELS) revealed a +4 oxidation state for the Ti and a +3 oxidation state for the Fe. These EELS results were further confirmed with XPS analysis. The electronic properties of the samples were investigated by applying Kramers-Kronig analysis to the low-loss EELS spectra acquired from the prepared NPs. The presented results showed that the band gap energy of the TiO2 NPs decreased from an original value of 3.2 eV to about 2.2 eV, which is quite close to the ideal band gap energy of 1.65 eV for photocatalysis semiconductors. The observed decrease in band gap energy of the TiO2 NPs was attributed to the presence of Fe atoms at the lattice sites of the anatase TiO2 lattice. In short, C-coated and Fe-doped TiO2 NPs were synthesized with a rather cost-effective and comparatively easily scalable method. The

  14. Comparative analysis of the vibrational structure of the absorption spectra of acrolein in the excited ( S 1) electronic state

    Science.gov (United States)

    Koroleva, L. A.; Tyulin, V. I.; Matveev, V. K.; Pentin, Yu. A.

    2012-04-01

    The assignments of absorption bands of the vibrational structure of the UV spectrum are compared with the assignments of bands obtained by the CRDS method in a supersonic jet from the time of laser radiation damping for the trans isomer of acrolein in the excited ( S 1) electronic state. The ν00 trans = 25861 cm-1 values and fundamental frequencies, including torsional vibration frequency, obtained by the two methods were found to coincide in the excited electronic state ( S 1) for this isomer. The assignments of several absorption bands of the vibrational structure of the spectrum obtained by the CRDS method were changed. Changes in the assignment of (0-v') transition bands of the torsional vibration of the trans isomer in the Deslandres table from the ν00 trans trans origin allowed the table to be extended to high quantum numbers v'. The torsional vibration frequencies up to v' = 5 were found to be close to the frequencies found by analyzing the vibrational structure of the UV spectrum and calculated quantum-mechanically. The coincidence of the barrier to internal rotation (the cis-trans transition) in the one-dimensional model with that calculated quantum-mechanically using the two-dimensional model corresponds to a planar structure of the acrolein molecule in the excited ( S 1) electronic state.

  15. Direct analysis of Antarctic krill by slurry sampling: determination of copper, iron, manganese and zinc by flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Alves Flávia L.

    2000-01-01

    Full Text Available Slurry sampling in combination with flame atomic absorption spectrometry was employed for the direct determination of four essential trace elements, namely Cu, Fe, Mn and Zn in Antarctic krill. The effect of instrumental operating conditions and slurry sampling preparation on the analytical signal was investigated. For the determination of Cu, Fe and Zn, samples were suspended in a solution containing 2 mol L-1 HNO3. In the case of Mn, 4 mol L-1 HNO3 was necessary for the preparation of the slurry. The precision between sample replicates was better than 5%. The method was applied to the direct determination of Cu, Fe, Mn and Zn in Antarctic krill samples using aqueous reference solutions to prepare the calibration curves. The results obtained were in good agreement with those achieved by FAAS and ICP-AES after microwave-assisted wet digestion of the krill samples. The detection limits were 4.5, 1.0, 4.9 and 8.4 mug L-1 for Cu, Zn, Mn and Fe, respectively.

  16. Vibrational, X-ray absorption, and Mössbauer spectra of sulfate minerals from the weathered massive sulfide deposit at Iron Mountain, California

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

    2011-01-01

    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 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 Δn=0 absorption in medium-Z plasmas for astrophysical applications.

  18. Interaction of primaquine and chloroquine with ionic micelles: 1 H NMR and electronic absorption spectroscopy

    International Nuclear Information System (INIS)

    Perussi, Janice R.; Monte, Shirley C.; Imasato, Hidetake; Tabak, Marcel; Yushmanov, Victor E.

    1995-01-01

    The characteristic of binding of primaquine (PQ) and chloroquine (CQ) to micelles of surfactants with different charge of headgroups were studied by 1 H-NMR and optical absorption spectroscopy. Cetyltrimethylammonium (CTAC) was used as a cationic surfactant, sodium dodecylsulfate (SDS) as an anionic surfactant and N-hexadecyl-N, N-dimethyl-3-ammonio-1-propanesulfonate (HPS) as zwitterionic. The pK values and binding constants were estimated. (author)

  19. Electronic and oscillation absorption spectra of blood plamsa at surgical diseases of thyroid gland

    Science.gov (United States)

    Guminetskiy, S. G.; Motrich, A. V.; Poliansky, I. Y.; Hyrla, Ya. V.

    2012-01-01

    The results of investigating the absorption spectra of blood plasma in the visible and infrared parts of spectra obtained using the techniques of spherical photometer and spectrophotometric complex "Specord IR75" are presented. The possibility of using these spectra for diagnoses the cases of diffuse toxic goiter and nodular goiter and control of treatment process in postsurgical period in the cases of thyroid gland surgery is estimated.

  20. Electron paramagnetic resonance and optical absorption of uranium ions diluted in CdF2 single crystals

    International Nuclear Information System (INIS)

    Pereira, J.J.C.R.

    1976-08-01

    The electron paramagnetic resonance (EPR) has been studied in conection with the optical absortion spectra of Uranium ions diluted in CdF 2 single crystals. Analyses of the EPR and optical absorption spectra obtained experimentally, and a comparison with known results in the isomorfic CaF 2 , SrF 2 and BaF 2 , allowed the identification of two paramagnetic centers associated with Uranium ions. These are the U(2+) ion in cubic symmetry having the triplet γ 5 as ground state, and the U(3+) ion in cubic symmetry having the dublet γ 6 as ground state. (Author) [pt

  1. Ruthenium(II) chloro-bis(bipyridyl) complexes with substituted pyridine ligands: interpretation of their electronic absorption spectra

    International Nuclear Information System (INIS)

    Sizova, O.V.; Ershov, A.Yu.; Ivanova, N.V.; Shashko, A.D.; Kutejkina-Teplyakova, A.V.

    2003-01-01

    A number of complexes cis-[Ru(Bipy) 2 (L)(Cl)](BF 4 ), where Bipy-2,2'-bipyridine, L-pyridine, 4-aminopyridine, 4-picoline, nicotinamide, isonicotinamide, 3- and 4-cyanopyridine, 4,4'-bipyridine, trans-1,2-bis(4-pyridyl)ethylene, 4,4'-azopyridine, pyrazine, imidazole and NH 3 , were prepared. Using the CINDO-CI semiempirical method the energies and intensities of transition in electronic absorption spectra (EAS) of the complexes were calculated. It is shown that major differences in EAS of the compounds stem from position of transitions with charge transfer d π (Ru)→π*(L) [ru

  2. Impact of radial transport on the quasilinear plateau formation due to electron cyclotron wave absorption

    NARCIS (Netherlands)

    Peeters, A.G.; Westerhof, E.

    1996-01-01

    Numerical simulations using a three-dimensional Fokker-Planck code show that for small tokamaks the transport of electrons across the magnetic surfaces at a level consistent with anomalous transport has a large influence on the formation of the quasilinear plateau during electron cyclotron resonant

  3. Handbook of theoretical atomic physics data for photon absorption, electron scattering, and vacancies decay

    CERN Document Server

    Amusia, Miron Ya; Yarzhemsky, Victor

    2012-01-01

    The aim of this book is to present highly accurate and extensive theoretical Atomic data and to give a survey of selected calculational methods for atomic physics, used to obtain these data. The book presents the results of calculations of cross sections and probabilities of a broad variety of atomic processes with participation of photons and electrons, namely on photoabsorption, electron scattering and accompanying effects. Included are data for photoabsorption and electron scattering cross-sections and probabilities of vacancy decay formed for a large number of atoms and ions. Attention is also given to photoionization and vacancy decay in endohedrals and to positron-atom scattering. The book is richly illustrated. The methods used are one-electron Hartree-Fock and the technique of Feynman diagrams that permits to include many-electron correlations. This is done in the frames of the Random Phase approximation with exchange and the many-body perturbation theory. Newly obtained and previously collected atomi...

  4. Absorption and backscatter of internal conversion electrons in the measurements of surface contamination of 137Cs

    International Nuclear Information System (INIS)

    Yunoki, A.; Kawada, Y.; Yamada, T.; Unno, Y.; Sato, Y.; Hino, Y.

    2013-01-01

    We measured 4π and 2π counting efficiencies for internal conversion electrons (ICEs), gross β-particles and also β-rays alone with various source conditions regarding absorber and backing foil thickness using e-X coincidence technique. Dominant differences regarding the penetration, attenuation and backscattering properties among ICEs and β-rays were revealed. Although the abundance of internal conversion electrons of 137 Cs- 137 Ba is only 9.35%, 60% of gross counts may be attributed to ICEs in worse source conditions. This information will be useful for radionuclide metrology and for surface contamination monitoring. - Highlights: • Counting efficiencies for internal conversion electrons from 137 Cs were measured, and compared with those for β-rays. • Electron-X coincidence technique was employed. • A thin NaI(Tl) scintillation detector was used for X-ray detection. • Backscattering fractions of electrons and beta particles were studied by similar experiments

  5. Electron spin resonance insight into broadband absorption of the Cu3Bi(SeO32O2Br metamagnet

    Directory of Open Access Journals (Sweden)

    A. Zorko

    2016-05-01

    Full Text Available Metamagnets, which exhibit a transition from a low-magnetization to a high-magnetization state induced by the applied magnetic field, have recently been highlighted as promising materials for controllable broadband absorption. Here we show results of a multifrequency electron spin resonance (ESR investigation of the Cu3Bi(SeO32O2Br planar metamagnet on the kagome lattice. Its mixed antiferromagnetic/ferromagnetic phase is stabilized in a finite range of applied fields around 0.8 T at low temperatures and is characterized by enhanced microwave absorption. The absorption signal is non-resonant and its boundaries correspond to two critical fields that determine the mixed phase. With decreasing temperature these increase like the sublattice magnetization of the antiferromagnetic phase and show no frequency dependence between 100 and 480 GHz. On the contrary, we find that the critical fields depend on the magnetic-field sweeping direction. In particular, the higher critical field, which corresponds to the transition from the mixed to the ferromagnetic phase, shows a pronounced hysteresis effect, while such a hysteresis is absent for the lower critical field. The observed hysteresis is enhanced at lower temperatures, which suggests that thermal fluctuations play an important role in destabilizing the highly absorbing mixed phase.

  6. Delayed electron relaxation in CdTe nanorods studied by spectral analysis of the ultrafast transient absorption

    Energy Technology Data Exchange (ETDEWEB)

    Kriegel, I., E-mail: ilka.kriegel@iit.it [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Scotognella, F. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); CNST of IIT@POLIMI, Via Pascoli 70/3, 20133 Milano (Italy); Soavi, G. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Brescia, R. [Department of Nanochemistry, Istituto Italiano di Tecnologia (IIT), via Morego 30, 16163 Genova (Italy); Rodríguez-Fernández, J.; Feldmann, J. [Photonics and Optoelectronics Group, Department of Physics and CeNS, Ludwig-Maximilians-Universität München, Amalienstr. 54, 80799 Munich (Germany); Nanosystems Initiative Munich (NIM), Schellingstr. 4, 80799 Munich (Germany); Lanzani, G., E-mail: guglielmo.lanzani@iit.it [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); CNST of IIT@POLIMI, Via Pascoli 70/3, 20133 Milano (Italy); Tassone, F. [CNST of IIT@POLIMI, Via Pascoli 70/3, 20133 Milano (Italy)

    2016-06-01

    Highlights: • We study the photophysics of CdTe nanorods by ultrafast absorption spectroscopy. • We fit photobleaching and photoinduced absorption features at all time delays. • Dynamics are extracted from superpositions of bleaches (Gaussians) and derivatives. • Fast non-radiative recombination and slower hole trapping processes are extracted. • A potential approach to unveil ultrafast non-radiative recombination processes. - Abstract: In transient absorption (TA) spectra, the bleach features originating from state filling are overlapped by their energy-shifted derivatives, arising from excited state energy level shifts. This makes the direct extraction of carrier dynamics from a single-wavelength time-trace misleading. Fitting TA spectra in time, as Gaussian functions and their derivative-like shifted Gaussians, allows to individually extract the real dynamics of both photobleached transitions, and their energy shifts. In CdTe nanorods (NRs) we found a delayed heating of holes due to the release of the large excess energy in the electron relaxation process. The slow hole-trapping process is consistent with a high number of surface trap states in these model NRs. Our results show that only a correct disentanglement of bleaching and energy shift contributions provides a reliable framework to extract the underlying carrier relaxation dynamics, including trapping, non-radiative recombination, and eventually carrier multiplication.

  7. Delayed electron relaxation in CdTe nanorods studied by spectral analysis of the ultrafast transient absorption

    International Nuclear Information System (INIS)

    Kriegel, I.; Scotognella, F.; Soavi, G.; Brescia, R.; Rodríguez-Fernández, J.; Feldmann, J.; Lanzani, G.; Tassone, F.

    2016-01-01

    Highlights: • We study the photophysics of CdTe nanorods by ultrafast absorption spectroscopy. • We fit photobleaching and photoinduced absorption features at all time delays. • Dynamics are extracted from superpositions of bleaches (Gaussians) and derivatives. • Fast non-radiative recombination and slower hole trapping processes are extracted. • A potential approach to unveil ultrafast non-radiative recombination processes. - Abstract: In transient absorption (TA) spectra, the bleach features originating from state filling are overlapped by their energy-shifted derivatives, arising from excited state energy level shifts. This makes the direct extraction of carrier dynamics from a single-wavelength time-trace misleading. Fitting TA spectra in time, as Gaussian functions and their derivative-like shifted Gaussians, allows to individually extract the real dynamics of both photobleached transitions, and their energy shifts. In CdTe nanorods (NRs) we found a delayed heating of holes due to the release of the large excess energy in the electron relaxation process. The slow hole-trapping process is consistent with a high number of surface trap states in these model NRs. Our results show that only a correct disentanglement of bleaching and energy shift contributions provides a reliable framework to extract the underlying carrier relaxation dynamics, including trapping, non-radiative recombination, and eventually carrier multiplication.

  8. Gold-coated iron nanoparticles in transparent Si3N4 matrix thin films

    Science.gov (United States)

    Sánchez-Marcos, J.; Céspedes, E.; Jiménez-Villacorta, F.; Muñoz-Martín, A.; Prieto, C.

    2013-06-01

    A new method to prepare thin films containing gold-coated iron nanoparticles is presented. The ternary Fe-Au-Si3N4 system prepared by sequential sputtering has revealed a progressive variation of microstructures from Au/Fe/Au/Si3N4 multilayers to iron nanoparticles. Microstructural characterization by transmission electron microscopy, analysis of the magnetic properties and probing of the iron short-range order by X-ray absorption spectroscopy confirm the existence of a gold-coated iron nanoparticles of 1-2 nm typical size for a specific range of iron and gold contents per layer in the transparent silicon nitride ceramic matrix.

  9. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... normally stores but has used up. Increase your intake of vitamin C to help your body absorb iron. Avoid drinking black tea, which reduces iron absorption. Other treatments If you have chronic kidney disease and iron-deficiency anemia, your doctor may recommend ...

  10. Local 3d Electronic Structures of Co-Based Complexes with Medicinal Molecules Probed by Soft X-ray Absorption

    Science.gov (United States)

    Yamagami, Kohei; Fujiwara, Hidenori; Imada, Shin; Kadono, Toshiharu; Yamanaka, Keisuke; Muro, Takayuki; Tanaka, Arata; Itai, Takuma; Yoshinari, Nobuto; Konno, Takumi; Sekiyama, Akira

    2017-07-01

    We have examined the local 3d electronic structures of Co-Au multinuclear complexes with the medicinal molecules d-penicillaminate (d-pen) [Co{Au(PPh3)(d-pen)}2]ClO4 and [Co3{Au3(tdme)(d-pen)3}2] by Co L2,3-edge soft X-ray absorption (XAS) spectroscopy, where PPh3 denotes triphenylphosphine and tdme stands for 1,1,1-tris[(diphenylphosphino)methyl]ethane. The Co L2,3-edge XAS spectra indicate the localized ionic 3d electronic states in both materials. The experimental spectra are well explained by spectral simulation for a localized Co ion under ligand fields with the full multiplet theory, which verifies that the ions are in the low-spin Co3+ state in the former compound and in the high-spin Co2+ state in the latter.

  11. Electron volt spectroscopy on a pulsed neutron source using resonance absorption filters

    International Nuclear Information System (INIS)

    Newport, R.J.; Williams, W.G.

    1983-05-01

    The design aspects of an inelastic neutron spectrometer based on energy selection by the resonance absorption filter difference method are discussed. Detailed calculations of the accessible dynamical range (Q, ω), energy and momentum transfer resolutions and representative count rates are presented for Sm and Ta resonance filters in an inverse geometry spectrometer on a high intensity pulsed source such as the RAL Spallation Neutron Source (SNS). A discussion is given of the double-difference method, which provides a means of improving the resonance attenuation peak shape. As a result of this study, as well as preliminary experimental results, recommendations are made for the future development of the technique. (author)

  12. Electronic absorption bands of HoCl3 and SmCl3 complexes in alcohols

    International Nuclear Information System (INIS)

    Ramesh Babu, V.; Buddhudu, S.; Rangarajan, V.N.

    1987-01-01

    The normal absorption and second derivative spectra of ten alcoholic complexes of HoCl 3 and SmCl 3 were recorded. From the observed bands, energies and intensity values were measured. To fit in these measured values with the theoretical values, a set of spectroscopic parameters namely, Judd-Ofelt (T 2 , T 4 , T 6 ), intensity (Ω 2 , Ω 4 , Ω 6 ) had been computed. A good fit of intensities was obtained between the experimental and theoretical data. The environmental influences on the intensities of the hypersensitive transitions of Sm(III) and Ho(III) ions were found to be noteworthy. (author). 7 tables, 20 refs

  13. Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton.

    Science.gov (United States)

    Schuback, Nina; Schallenberg, Christina; Duckham, Carolyn; Maldonado, Maria T; Tortell, Philippe D

    2015-01-01

    Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETR(RCII), mol e- mol RCII(-1) s(-1)) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal--oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETR(RCII): CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements.

  14. Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton.

    Directory of Open Access Journals (Sweden)

    Nina Schuback

    Full Text Available Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETR(RCII, mol e- mol RCII(-1 s(-1 increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal--oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETR(RCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements.

  15. Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton

    Science.gov (United States)

    Schuback, Nina; Schallenberg, Christina; Duckham, Carolyn; Maldonado, Maria T.; Tortell, Philippe D.

    2015-01-01

    Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETRRCII, mol e- mol RCII-1 s-1) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal – oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETRRCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements. PMID:26171963

  16. X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, Thomas; Kern, Jan; Kubin, Markus; Ratner, Daniel; Gul, Sheraz; Fuller, Franklin D.; Löchel, Heike; Krzywinski, Jacek; Lutman, Alberto; Ding, Yuantao; Dakovski, Georgi L.; Moeller, Stefan; Turner, Joshua J.; Alonso-Mori, Roberto; Nordlund, Dennis L.; Rehanek, Jens; Weniger, Christian; Firsov, Alexander; Brzhezinskaya, Maria; Chatterjee, Ruchira; Lassalle-Kaiser, Benedikt; Sierra, Raymond G.; Laksmono, Hartawan; Hill, Ethan; Borovik, Andrew; Erko, Alexei; Föhlisch, Alexander; Mitzner, Rolf; Yachandra, Vittal K.; Yano, Junko; Wernet, Philippe; Bergmann, Uwe

    2016-01-01

    © 2016 Optical Society of America. X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based on self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. We show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements.

  17. Estimation of electron temperature and density by de convolving the absorption part of the plasma dispersion function

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez D, H.; Cabral P, A.; Melendez L, L.; Lopez C, R.; Colunga S, S.; Valencia A, R.; Cruz J, S.; Gaytan G, E.; Chavez A, E

    1992-04-15

    In this work a method to estimate the temperature and density of the electron (T{sub e}, n{sub e}), based on the deconvolution of the part of absorption of the dispersion function of the plasma is suggested. The absorptive part of this function, is proportional to the convolution of a Gauss distribution with a Lorentz function. The Gaussian represents to the Maxwell function of velocities distribution of the electrons of the plasma. The Lorentzian represents to the form of it lines of an linearized electrostatic wave that spreads with reduction in the plasma. The complex variable z of the plasma dispersion function is written as: z = u + ia, where u = 2 (w-w{sub 0}) {radical} Ln 2 /{gamma}{sub G} is the dimensionless frequency variable, a = {gamma}{sub L} {radical} Ln 2 /{gamma}{sub G} is the Posener parameter, {gamma}{sub G} = k {gamma}{sup '}{sub G} where k is the wave number of the oscillatory phenomenon, {gamma}{sup '}{sub G} is the FWHM of the Gaussian and {gamma}{sub L} = 2 {alpha}, {alpha} being the damping constant; i.e the imaginary part of the frequency {omega}. In this method, it will be assumed that a wave of frequency , and of amplitude small enough to avoid non-linear effects, propagates in the plasma and decays in such a way {alpha} is the Landau damping. With this assumption, the method is only valid in the interval k < < k{sub D}, where k{sub D} is the Debye wave number. Deconvolution of the detected absorption frequency spectrum of the signal, gives the values of {gamma}{sub G} and {gamma}{sub L} from which the values of n{sub e} and T{sub e} can be deduced. (Author)

  18. Estimation of electron temperature and density by de convolving the absorption part of the plasma dispersion function

    International Nuclear Information System (INIS)

    Jimenez D, H.; Cabral P, A.; Melendez L, L.; Lopez C, R.; Colunga S, S.; Valencia A, R.; Cruz J, S.; Gaytan G, E.; Chavez A, E.

    1992-04-01

    In this work a method to estimate the temperature and density of the electron (T e , n e ), based on the deconvolution of the part of absorption of the dispersion function of the plasma is suggested. The absorptive part of this function, is proportional to the convolution of a Gauss distribution with a Lorentz function. The Gaussian represents to the Maxwell function of velocities distribution of the electrons of the plasma. The Lorentzian represents to the form of it lines of an linearized electrostatic wave that spreads with reduction in the plasma. The complex variable z of the plasma dispersion function is written as: z = u + ia, where u = 2 (w-w 0 ) √ Ln 2 /Γ G is the dimensionless frequency variable, a = Γ L √ Ln 2 /Γ G is the Posener parameter, Γ G = k Γ ' G where k is the wave number of the oscillatory phenomenon, Γ ' G is the FWHM of the Gaussian and Γ L = 2 α, α being the damping constant; i.e the imaginary part of the frequency ω. In this method, it will be assumed that a wave of frequency , and of amplitude small enough to avoid non-linear effects, propagates in the plasma and decays in such a way α is the Landau damping. With this assumption, the method is only valid in the interval k D , where k D is the Debye wave number. Deconvolution of the detected absorption frequency spectrum of the signal, gives the values of Γ G and Γ L from which the values of n e and T e can be deduced. (Author)

  19. Local probe investigations of the electronic phase diagrams of iron pnictides and chalcogenides

    Energy Technology Data Exchange (ETDEWEB)

    Materne, Philipp

    2015-09-24

    In this work, the electronic phase diagrams of Ca{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} and Fe{sub 1+y}Te were investigated using muon spin relaxation and Moessbauer spectroscopy. Single crystals of Ca{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} with x = 0.00, 0.35, 0.50, and 0.67 were examined. The undoped 122 parent compound CaFe{sub 2}As{sub 2} is a semi metal and shows antiferromagnetic commensurate spin density wave order below 167 K. By hole doping via Na substitution, the magnetic order is suppressed and superconductivity emerges including a Na-substitution level region, where both phases coexist. Upon Na substitution, a tilting of the magnetic moments out of the ab-plane is found. The interaction of the magnetic and superconducting order parameter in this coexistence region was studied and a nanoscopic coexistence of both order parameters is found. This is proven by a reduction of the magnetic order parameter of 7 % in x = 0.50 below the superconducting transition temperature. This reduction was analysed using Landau theory and a systematic correlation between the reduction of the magnetic order parameter and the ratio of the transition temperatures, T{sub c}/T{sub N}, for the 122 family of the iron pnictides is presented. The magnetic phase transition is accompanied by a tetragonal-to-orthorhombic phase transition. The lattice dynamics at temperatures above and below this magneto-structural phase transition were studied and no change in the lattice dynamics were found. However, the lattice for finite x is softer than for the undoped compound. For x = 0.67, diluted magnetic order is found. Therefore, the magnetism in Ca{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} is persistent even at optimal doping. The superconducting state is investigated by measuring the temperature dependence of the magnetic penetration depth, where two superconducting gaps with a weighting of nearly 50:50 are obtained. A temperature independent anisotropy of the magnetic penetration depth γ{sub

  20. Local probe investigations of the electronic phase diagrams of iron pnictides and chalcogenides

    International Nuclear Information System (INIS)

    Materne, Philipp

    2015-01-01

    In this work, the electronic phase diagrams of Ca 1-x Na x Fe 2 As 2 and Fe 1+y Te were investigated using muon spin relaxation and Moessbauer spectroscopy. Single crystals of Ca 1-x Na x Fe 2 As 2 with x = 0.00, 0.35, 0.50, and 0.67 were examined. The undoped 122 parent compound CaFe 2 As 2 is a semi metal and shows antiferromagnetic commensurate spin density wave order below 167 K. By hole doping via Na substitution, the magnetic order is suppressed and superconductivity emerges including a Na-substitution level region, where both phases coexist. Upon Na substitution, a tilting of the magnetic moments out of the ab-plane is found. The interaction of the magnetic and superconducting order parameter in this coexistence region was studied and a nanoscopic coexistence of both order parameters is found. This is proven by a reduction of the magnetic order parameter of 7 % in x = 0.50 below the superconducting transition temperature. This reduction was analysed using Landau theory and a systematic correlation between the reduction of the magnetic order parameter and the ratio of the transition temperatures, T c /T N , for the 122 family of the iron pnictides is presented. The magnetic phase transition is accompanied by a tetragonal-to-orthorhombic phase transition. The lattice dynamics at temperatures above and below this magneto-structural phase transition were studied and no change in the lattice dynamics were found. However, the lattice for finite x is softer than for the undoped compound. For x = 0.67, diluted magnetic order is found. Therefore, the magnetism in Ca 1-x Na x Fe 2 As 2 is persistent even at optimal doping. The superconducting state is investigated by measuring the temperature dependence of the magnetic penetration depth, where two superconducting gaps with a weighting of nearly 50:50 are obtained. A temperature independent anisotropy of the magnetic penetration depth γ λ = 1.5(4) is obtained, which is much smaller compared to other 122 compounds

  1. Handbook of theoretical atomic physics. Data for photon absorption, electron scattering, and vacancies decay

    Energy Technology Data Exchange (ETDEWEB)

    Amusia, Miron [Hebrew Univ., Jerusalem (Israel). Racah Inst. of Physics; Ioffe Physico-Technical Inst., St. Petersburg (Russian Federation); Chernysheva, Larissa [Ioffe Physico-Technical Inst., St. Petersburg (Russian Federation); Yarzhemsky, Victor [Kurnakov Institute of General and Inorganic Chemistry, Moscow (Russian Federation)

    2012-07-01

    The aim of this book is to present highly accurate and extensive theoretical Atomic data and to give a survey of selected calculational methods for atomic physics, used to obtain these data. The book presents the results of calculations of cross sections and probabilities of a broad variety of atomic processes with participation of photons and electrons, namely on photoabsorption, electron scattering and accompanying effects. Included are data for photoabsorption and electron scattering cross-sections and probabilities of vacancy decay formed for a large number of atoms and ions. Attention is also given to photoionization and vacancy decay in endohedrals and to positron-atom scattering. The book is richly illustrated. The methods used are one-electron Hartree-Fock and the technique of Feynman diagrams that permits to include many-electron correlations. This is done in the frames of the Random Phase approximation with exchange and the many-body perturbation theory. Newly obtained and previously collected atomic data are presented. The atomic data are useful for investigating the electronic structure and physical processes in solids and liquids, molecules and clusters, astronomical objects, solar and planet atmospheres and atomic nucleus. Deep understanding of chemical reactions and processes is reached by deep and accurate knowledge of atomic structure and processes with participation of atoms. This book is useful for theorists performing research in different domains of contemporary physics, chemistry and biology, technologists working on production of new materials and for experimentalists performing research in the field of photon and electron interaction with atoms, molecules, solid bodies and liquids.

  2. Fish scale deformation analysis using scanning electron microscope: New potential biomarker in aquatic environmental monitoring of aluminum and iron contamination

    Energy Technology Data Exchange (ETDEWEB)

    Hidayati, Dewi; Sulaiman, Norela; Othman, Shuhaimi; Ismail, B. S. [School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2013-11-27

    Fish scale has the potential to be a rapid biomarker due to its structure and high possibility to come into contact with any pollutant in the aquatic environment. The scale structure consists of osteoblastic cells and other bone materials such as collagen where it is possible to form a molecular complex with heavy metals such as aluminum and iron. Hence, aluminum and iron in water could possibly destroy the scale material and marked as a scale deformation that quantitatively could be analyzed by comparing it to the normal scale structure. Water sampling and fish cage experiment were performed between June and July 2011 in Porong river which represented the water body that has high aluminum and iron contamination. The filtered water samples were preserved and extracted using the acid-mixture procedure prior to measurement of the aluminum and iron concentrations using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), while samples for total suspended solid (TSS) analysis were kept at 4 °C in cool-boxes. The scales were cleaned with sterile water, then dehydrated in 30, 50, 70, and 90% ethanol and dried on filter papers. They were then mounted on an aluminum stub and coated with gold in a sputter coater prior to Scanning Electron Microscope (SEM) observation. According to the SEM analysis, it was found that there were several deformations on the scale samples taken from sites that have high concentrations of aluminum and iron i.e. the increasing number of pits, deformation and decreasing number of spherules and ridges while the control scale exhibited the normal features. However, the site with higher TSS and pH indicated lower aluminum effect. A moderate correlation was found between the number of pits with aluminum (r=0.43) and iron (r=0.41) concentrations. Fish scale deformation using SEM analysis can potentially be a rapid biomarker in aquatic monitoring of aluminum and iron contamination. However, the measurement must be accompanied by pH and

  3. Fish scale deformation analysis using scanning electron microscope: New potential biomarker in aquatic environmental monitoring of aluminum and iron contamination

    Science.gov (United States)

    Hidayati, Dewi; Sulaiman, Norela; Othman, Shuhaimi; Ismail, B. S.

    2013-11-01

    Fish scale has the potential to be a rapid biomarker due to its structure and high possibility to come into contact with any pollutant in the aquatic environment. The scale structure consists of osteoblastic cells and other bone materials such as collagen where it is possible to form a molecular complex with heavy metals such as aluminum and iron. Hence, aluminum and iron in water could possibly destroy the scale material and marked as a scale deformation that quantitatively could be analyzed by comparing it to the normal scale structure. Water sampling and fish cage experiment were performed between June and July 2011 in Porong river which represented the water body that has high aluminum and iron contamination. The filtered water samples were preserved and extracted using the acid-mixture procedure prior to measurement of the aluminum and iron concentrations using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), while samples for total suspended solid (TSS) analysis were kept at 4 °C in cool-boxes. The scales were cleaned with sterile water, then dehydrated in 30, 50, 70, and 90% ethanol and dried on filter papers. They were then mounted on an aluminum stub and coated with gold in a sputter coater prior to Scanning Electron Microscope (SEM) observation. According to the SEM analysis, it was found that there were several deformations on the scale samples taken from sites that have high concentrations of aluminum and iron i.e. the increasing number of pits, deformation and decreasing number of spherules and ridges while the control scale exhibited the normal features. However, the site with higher TSS and pH indicated lower aluminum effect. A moderate correlation was found between the number of pits with aluminum (r=0.43) and iron (r=0.41) concentrations. Fish scale deformation using SEM analysis can potentially be a rapid biomarker in aquatic monitoring of aluminum and iron contamination. However, the measurement must be accompanied by pH and

  4. Electronically excited states of vitamin B12 and methylcobalamin: theoretical analysis of absorption, CD, and MCD data.

    Science.gov (United States)

    Solheim, Harald; Kornobis, Karina; Ruud, Kenneth; Kozlowski, Pawel M

    2011-02-03

    Linear and quadratic response time-dependent density functional theory (TD-DFT) has been applied to investigate absorption (Abs), circular dichroism (CD), and magnetic CD (MCD) spectra of cyanocobalamin (CNCbl) and methylcobalamin (MeCbl). Although electronically excited states of both cobalamins have been probed by applying different experimental techniques, their exact nature remains poorly understood from an electronic structure point of view. Recent theoretical studies have revealed a lot of relevant information about their properties but also left some unresolved issues related to the nature of individual transitions. In this contribution, not only Abs but also CD and MCD spectra of both cobalamins were computed for direct comparison with experiment. The results were evaluated with respect to the choice of exchange-correlation functional, basis set, and the environment (gas phase or solvent) used in the calculation. Taking into account the complexity of the CNCbl and MeCbl systems, reliable agreement between theory and experiment was achieved based on calculations employing the BP86 functional, particularly for the low-energy α/β bands. This spectral range has been traditionally interpreted as a vibrational progression associated with a single electronic excitation, but according to the present analysis for both cobalamins, these bands are best interpreted as consisting of multiple electronic transitions.

  5. Study of iron exchanged zeolites by Moessbauer effect and electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Aguirre Campuzano, C.E.

    1993-01-01

    Crystalline iron exchanged NaY zeolites, prepared from aqueous solutions and calcined at atmospheric conditions, have been studied and characterized by XRD, Moessbauer and EPR spectroscopies and TGA analysis. Three iron sites are clearly distinguished from Moessbauer and EPR measurements. Firstly, characteristic Moessbauer and EPR spectra may arise from framework sites, suggesting that Fe has substituted Al. It is also found that their spectroscopic signals are not intensity affected by thermal treatments. Secondly, a Moessbauer doublet which may arise from octahedral sites in the large cavity of the zeolite, shows however, that this doublet and its EPR signal are intensity temperature affected. An additional line broadening is observed on the low velocity line of this doublet, Thirdly, characteristic Moessbauer and EPR signals, which are also intensity temperature dependent have been associated to accluded material, where the Moessbauer doublet presents the line broadening effect before mentioned. Such line broadening effect may be due to perturbing signals from iron ions in tetrahedral sites. Finally, it has been observed that during calcination of the FeY zeolites, the three characteristic EPR signals for the three iron sites, do not increase at the expenses of the other. A result that may suggest a strong bonding between Fe-site of the Y zeolite, irrespective of the iron source. (Author)

  6. Beta transmutations in apatites with ferric iron as an electron acceptor - implication for nuclear waste form development.

    Science.gov (United States)

    Yao, Ge; Zhang, Zelong; Wang, Jianwei

    2017-09-27

    Apatite-structured materials have been considered for the immobilization of a number of fission products from reprocessing nuclear fuel because of their chemical durability as well as compositional and structural flexibility. It is hypothesized that the effect of beta decay on the stability can be mitigated by introducing an appropriate electron acceptor at the neighboring sites in the structure. The decay series 137 Cs → 137 Ba and 90 Sr → 90 Y → 90 Zr were investigated using a spin-polarized DFT approach to test the hypothesis. Apatites with compositions of Ca 10 (PO 4 ) 6 F 2 and Ca 4 Y 6 (SiO 4 ) 6 F 2 were selected as model systems for the incorporation of radionuclides Cs and Sr, respectively. Ferric iron was introduced in the structure as an electron acceptor. Electron density of states, crystal and defect structures, and energies before and after beta decay were calculated. The calculated electron density of states suggests that the extra electron is localized at the ferric iron, which changes its oxidation state and becomes ferrous iron. The crystal and defect structures were analyzed based on the volume, lattice parameters, radial distribution functions, metal cation to coordinating oxygen distances, and the metaprism twist angle of the apatite crystal structure. The results show that there are minor changes in the crystal and defect structures of CsFeCa 8 (PO 4 ) 6 F 2 with Cs + and Fe 3+ substitutions undergoing the Cs → Ba transmutation, and of Ca 3 SrY 4 Fe 2 (SiO 4 ) 6 F 2 with Sr 2+ and Fe 3+ substitutions undergoing the Sr → Y → Zr transmutations. The last decay change, from Y 3+ → Zr 4+ , causes relatively larger changes in the local defect structure around Zr involving the coordination environment but the change is not significant to the crystal structure. The results on calculated cohesive energy suggest that the transmutations Cs + → Ba 2+ and Sr 2+ → Y 3+ → Zr 4+ in both apatite compositions are energetically favorable

  7. Electron beam absorption in solid and in water phantoms: depth scaling and energy-range relations

    International Nuclear Information System (INIS)

    Grosswendt, B.; Roos, M.

    1989-01-01

    In electron dosimetry energy parameters are used with values evaluated from ranges in water. The electron ranges in water may be deduced from ranges measured in solid phantoms. Several procedures recommended by national and international organisations differ both in the scaling of the ranges and in the energy-range relations for water. Using the Monte Carlo method the application of different procedures for electron energies below 10 MeV is studied for different phantom materials. It is shown that deviations in the range scaling and in the energy-range relations for water may accumulate to give energy errors of several per cent. In consequence energy-range relations are deduced for several solid phantom materials which enable a single-step energy determination. (author)

  8. Making oxidation potentials predictable: Coordination of additives applied to the electronic fine tuning of an iron(II) complex

    KAUST Repository

    Haslinger, Stefan

    2014-11-03

    This work examines the impact of axially coordinating additives on the electronic structure of a bioinspired octahedral low-spin iron(II) N-heterocyclic carbene (Fe-NHC) complex. Bearing two labile trans-acetonitrile ligands, the Fe-NHC complex, which is also an excellent oxidation catalyst, is prone to axial ligand exchange. Phosphine- and pyridine-based additives are used for substitution of the acetonitrile ligands. On the basis of the resulting defined complexes, predictability of the oxidation potentials is demonstrated, based on a correlation between cyclic voltammetry experiments and density functional theory calculated molecular orbital energies. Fundamental insights into changes of the electronic properties upon axial ligand exchange and the impact on related attributes will finally lead to target-oriented manipulation of the electronic properties and consequently to the effective tuning of the reactivity of bioinspired systems.

  9. Making oxidation potentials predictable: Coordination of additives applied to the electronic fine tuning of an iron(II) complex

    KAUST Repository

    Haslinger, Stefan; Kü ck, Jens W.; Hahn, Eva M.; Cokoja, Mirza; Pö thig, Alexander; Basset, Jean-Marie; Kü hn, Fritz

    2014-01-01

    This work examines the impact of axially coordinating additives on the electronic structure of a bioinspired octahedral low-spin iron(II) N-heterocyclic carbene (Fe-NHC) complex. Bearing two labile trans-acetonitrile ligands, the Fe-NHC complex, which is also an excellent oxidation catalyst, is prone to axial ligand exchange. Phosphine- and pyridine-based additives are used for substitution of the acetonitrile ligands. On the basis of the resulting defined complexes, predictability of the oxidation potentials is demonstrated, based on a correlation between cyclic voltammetry experiments and density functional theory calculated molecular orbital energies. Fundamental insights into changes of the electronic properties upon axial ligand exchange and the impact on related attributes will finally lead to target-oriented manipulation of the electronic properties and consequently to the effective tuning of the reactivity of bioinspired systems.

  10. Iron monoxide photodissociation

    Science.gov (United States)

    Chestakov, D. A.; Parker, D. H.; Baklanov, A. V.

    2005-02-01

    The photodissociation of Fe56O was studied by means of the velocity map imaging technique. A molecular beam of iron atoms and iron monoxide molecules was created using an electrical discharge with an iron electrode in a supersonic expansion of molecular oxygen. The ground state iron atom Fe(D45) and FeO concentrations in the molecular beam have been estimated. The dissociation energy of the FeO XΔ5 ground electronic state was found to be D00(FeO )=4.18±0.01eV. The effective absorption cross section of FeO at 252.39nm (vac), leading to the Fe(D45)+O(P3) dissociation channel, is ˜1.2×10-18cm2. A (1+1) resonantly enhanced multiphoton ionization spectrum of Fe56O in the region 39550-39580 cm-1 with rotational structure has been observed, but not assigned. Angular distributions of Fe(D45) and Fe(D35) products for the channel FeO →Fe(D4,35)+O(P3) have been measured at several points in the 210-260nm laser light wavelength region. The anisotropy parameter varies strongly with wavelength for both channels.

  11. Temperature-Induced Large Broadening and Blue Shift in the Electronic Band Structure and Optical Absorption of Methylammonium Lead Iodide Perovskite.

    Science.gov (United States)

    Yang, Jia-Yue; Hu, Ming

    2017-08-17

    The power conversion efficiency of hybrid halide perovskite solar cells is profoundly influenced by the operating temperature. Here we investigate the temperature influence on the electronic band structure and optical absorption of cubic CH 3 NH 3 PbI 3 from first-principles by accounting for both the electron-phonon interaction and thermal expansion. Within the framework of density functional perturbation theory, the electron-phonon coupling induces slightly enlarged band gap and strongly broadened electronic relaxation time as temperature increases. The large broadening effect is mainly due to the presence of cation organic atoms. Consequently, the temperature-dependent absorption peak exhibits blue-shift position, decreased amplitude, and broadened width. This work uncovers the atomistic origin of temperature influence on the optical absorption of cubic CH 3 NH 3 PbI 3 and can provide guidance to design high-performance hybrid halide perovskite solar cells at different operating temperatures.

  12. Molecular design of photovoltaic materials for polymer solar cells: toward suitable electronic energy levels and broad absorption.

    Science.gov (United States)

    Li, Yongfang

    2012-05-15

    Bulk heterojunction (BHJ) polymer solar cells (PSCs) sandwich a blend layer of conjugated polymer donor and fullerene derivative acceptor between a transparent ITO positive electrode and a low work function metal negative electrode. In comparison with traditional inorganic semiconductor solar cells, PSCs offer a simpler device structure, easier fabrication, lower cost, and lighter weight, and these structures can be fabricated into flexible devices. But currently the power conversion efficiency (PCE) of the PSCs is not sufficient for future commercialization. The polymer donors and fullerene derivative acceptors are the key photovoltaic materials that will need to be optimized for high-performance PSCs. In this Account, I discuss the basic requirements and scientific issues in the molecular design of high efficiency photovoltaic molecules. I also summarize recent progress in electronic energy level engineering and absorption spectral broadening of the donor and acceptor photovoltaic materials by my research group and others. For high-efficiency conjugated polymer donors, key requirements are a narrower energy bandgap (E(g)) and broad absorption, relatively lower-lying HOMO (the highest occupied molecular orbital) level, and higher hole mobility. There are three strategies to meet these requirements: D-A copolymerization for narrower E(g) and lower-lying HOMO, substitution with electron-withdrawing groups for lower-lying HOMO, and two-dimensional conjugation for broad absorption and higher hole mobility. Moreover, better main chain planarity and less side chain steric hindrance could strengthen π-π stacking and increase hole mobility. Furthermore, the molecular weight of the polymers also influences their photovoltaic performance. To produce high efficiency photovoltaic polymers, researchers should attempt to increase molecular weight while maintaining solubility. High-efficiency D-A copolymers have been obtained by using benzodithiophene (BDT), dithienosilole

  13. Spatio-temporal analysis of the electron power absorption in electropositive capacitive RF plasmas based on moments of the Boltzmann equation

    Science.gov (United States)

    Schulze, J.; Donkó, Z.; Lafleur, T.; Wilczek, S.; Brinkmann, R. P.

    2018-05-01

    Power absorption by electrons from the space- and time-dependent electric field represents the basic sustaining mechanism of all radio-frequency driven plasmas. This complex phenomenon has attracted significant attention. However, most theories and models are, so far, only able to account for part of the relevant mechanisms. The aim of this work is to present an in-depth analysis of the power absorption by electrons, via the use of a moment analysis of the Boltzmann equation without any ad-hoc assumptions. This analysis, for which the input quantities are taken from kinetic, particle based simulations, allows the identification of all physical mechanisms involved and an accurate quantification of their contributions. The perfect agreement between the sum of these contributions and the simulation results verifies the completeness of the model. We study the relative importance of these mechanisms as a function of pressure, with high spatial and temporal resolution, in an electropositive argon discharge. In contrast to some widely accepted previous models we find that high space- and time-dependent ambipolar electric fields outside the sheaths play a key role for electron power absorption. This ambipolar field is time-dependent within the RF period and temporally asymmetric, i.e., the sheath expansion is not a ‘mirror image’ of the sheath collapse. We demonstrate that this time-dependence is mainly caused by a time modulation of the electron temperature resulting from the energy transfer to electrons by the ambipolar field itself during sheath expansion. We provide a theoretical proof that this ambipolar electron power absorption would vanish completely, if the electron temperature was constant in time. This mechanism of electron power absorption is based on a time modulated electron temperature, markedly different from the Hard Wall Model, of key importance for energy transfer to electrons on time average and, thus, essential for the generation of capacitively

  14. Iron species determination by task-specific ionic liquid-based in situ solvent formation dispersive liquid-liquid microextraction combined with flame atomic absorption spectrometry.

    Science.gov (United States)

    Sadeghi, Susan; Ashoori, Vahid

    2017-10-01

    The task-specific ionic liquid (TSIL) of 1-ethyl-3-methylimidazolium bromide functionalized with 8-hydroxyquinoline was used as a chelating agent and extracting solvent for dispersive liquid-liquid microextraction and subsequent determination of Fe(III) by flame atomic absorption spectrometry. The in situ solvent formation of TSIL using KPF 6 provided the desired water-immiscible ionic liquid. The total Fe concentration could be determined after pre-oxidation of Fe(II) to Fe(III). Various factors affecting the proposed extraction procedure were optimized. The proposed analytical conditions were: sample pH 5, TSIL amount 0.3% (w/v), KPF 6 amount 0.15% (w/v), anti-sticking 0.1% (w/v) and salt concentration 5% (w/v). Under optimal conditions, the linear dynamic ranges for Fe(III) and total Fe were 20-80 and 20-110 ng mL -1 , respectively, with a detection limit of 6.9 ng mL -1 for Fe(III) and relative standard deviation of 2.2%. The proposed method was successfully applied to the determination of trace Fe(III) in water (underground, tap, refined water and artificial sea water) and beverage (apple, tomato, and tea) samples. The developed method offers advantages such as simplicity, ease of operation, and extraction of Fe(III) from aqueous solutions without the use of organic solvent. It was successfully applied for iron speciation in different real samples. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  15. Triplet excited electronic state switching induced by hydrogen bonding: A transient absorption spectroscopy and time-dependent DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Ravi Kumar, Venkatraman; Ariese, Freek; Umapathy, Siva, E-mail: umapathy@ipc.iisc.ernet.in [Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012 (India)

    2016-03-21

    The solvent plays a decisive role in the photochemistry and photophysics of aromatic ketones. Xanthone (XT) is one such aromatic ketone and its triplet-triplet (T-T) absorption spectra show intriguing solvatochromic behavior. Also, the reactivity of XT towards H-atom abstraction shows an unprecedented decrease in protic solvents relative to aprotic solvents. Therefore, a comprehensive solvatochromic analysis of the triplet-triplet absorption spectra of XT was carried out in conjunction with time dependent density functional theory using the ad hoc explicit solvent model approach. A detailed solvatochromic analysis of the T-T absorption bands of XT suggests that the hydrogen bonding interactions are different in the corresponding triplet excited states. Furthermore, the contributions of non-specific and hydrogen bonding interactions towards differential solvation of the triplet states in protic solvents were found to be of equal magnitude. The frontier molecular orbital and electron density difference analysis of the T{sub 1} and T{sub 2} states of XT indicates that the charge redistribution in these states leads to intermolecular hydrogen bond strengthening and weakening, respectively, relative to the S{sub 0} state. This is further supported by the vertical excitation energy calculations of the XT-methanol supra-molecular complex. The intermolecular hydrogen bonding potential energy curves obtained for this complex in the S{sub 0}, T{sub 1}, and T{sub 2} states support the model. In summary, we propose that the different hydrogen bonding mechanisms exhibited by the two lowest triplet excited states of XT result in a decreasing role of the nπ{sup ∗} triplet state, and are thus responsible for its reduced reactivity towards H-atom abstraction in protic solvents.

  16. Direct Measurement of the Electron Bernstein Wave Absorption and Current Drive at the WEGA Stellarator

    Czech Academy of Sciences Publication Activity Database

    Laqua, H.; Marsen, S.; Otte, M.; Podoba, Y.; Preinhaelter, Josef; Urban, Jakub

    2007-01-01

    Roč. 52, č. 16 (2007), s. 280-280 ISSN 0003-0503. [Annual Meeting of the Division of Plasma Physics/49th./. Orlando , Florida, 12.11.2007-16.11.2007] Institutional research plan: CEZ:AV0Z20430508 Keywords : Conversion * Emission * Tokamaks * Electron Bernstein waves * Simulation * NSTX Subject RIV: BL - Plasma and Gas Discharge Physics http://meetings.aps.org/Meeting/DPP07/Content/901

  17. Research of electronic absorption spectra of benzazols derivatives by ab initio calculations

    Science.gov (United States)

    Irgibaeva, I. S.; Birimzhanova, D. A.; Barashkov, N. N.

    Using the method of density functional theory in approximating B3LYP with the basis set 6-31G* the computations of structures and UV-vis spectra (TDDFT method) of benzazols derivatives were performed. The comparison of estimated electron spectra with the observed ones was made indicating good agreement of theoretically obtained results with experiment. Moreover these compounds have distinctive spectral-luminescent properties (large stokes shift) because of intramolecular proton transfer in excited state.

  18. Bimodal Exciplex Formation in Bimolecular Photoinduced Electron Transfer Revealed by Ultrafast Time-Resolved Infrared Absorption.

    Science.gov (United States)

    Koch, Marius; Licari, Giuseppe; Vauthey, Eric

    2015-09-03

    The dynamics of a moderately exergonic photoinduced charge separation has been investigated by ultrafast time-resolved infrared absorption with the dimethylanthracene/phthalonitrile donor/acceptor pair in solvents covering a broad range of polarity. A distinct spectral signature of an exciplex could be identified in the -C≡N stretching region. On the basis of quantum chemistry calculations, the 4-5 times larger width of this band compared to those of the ions and of the locally excited donor bands is explained by a dynamic distribution of exciplex geometry with different mutual orientations and distances of the constituents and, thus, with varying charge-transfer character. Although spectrally similar, two types of exciplexes could be distinguished by their dynamics: short-lived, "tight", exciplexes generated upon static quenching and longer-lived, "loose", exciplexes formed upon dynamic quenching in parallel with ion pairs. Tight exciplexes were observed in all solvents, except in the least polar diethyl ether where quenching is slower than diffusion. The product distribution of the dynamic quenching depends strongly on the solvent polarity: whereas no significant loose exciplex population could be detected in acetonitrile, both exciplex and ion pair are generated in less polar solvents, with the relative population of exciplex increasing with decreasing solvent polarity. These results are compared with those reported previously with donor/acceptor pairs in different driving force regimes to obtain a comprehensive picture of the role of the exciplexes in bimolecular photoinduced charge separation.

  19. An electron-microscope study of alpha to gamma transformation in an iron-nickel alloy

    Science.gov (United States)

    Lobodyuk, V. A.; Khandros, L. G.; Fedas, N. P.

    1980-01-01

    Procedures used to study the alpha to gamma conversion in thin foils of an iron alloy with 32% nickel concentration and initial martensite conversion temperature of -60 C are described. Photomicrographs show deformation twinning as well as changes in samples after they were heated. Reverse conversion is discussed and results are examined.

  20. Doping dependence of spin fluctuations and electron correlations in iron pnictides

    Czech Academy of Sciences Publication Activity Database

    Ikeda, H.; Arita, R.; Kuneš, Jan

    2010-01-01

    Roč. 82, č. 2 (2010), 024508/1-024508/6 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : iron pnicitdes * dynamic spin susceptibility * fluctuation-exchange approximation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010 http://prb.aps.org/abstract/PRB/v82/i2/e024508

  1. Occupied and unoccupied electronic structures of an L-cysteine film studied by core-absorption and resonant photoelectron spectroscopies

    Science.gov (United States)

    Kamada, M.; Hideshima, T.; Azuma, J.; Yamamoto, I.; Imamura, M.; Takahashi, K.

    2016-04-01

    Unoccupied and occupied electronic structures of an L-cysteine film have been studied by absorption and resonant photoelectron spectroscopies. Core absorptions at S-L, C-K, N-K, and O-K levels indicate that the lower unoccupied states are predominantly composed of oxygen-2p, carbon-2p, and sulfur-4s+3d orbitals, while higher unoccupied states may be attributed dominantly to nitrogen-np (n ≥ 3), oxygen-np (n ≥ 3), and sulfur-ns+md (n ≥ 4, m ≥ 3) orbitals. Resonant photoelectron spectra at S-L23 and O-K levels indicate that the highest occupied state is originated from sulfur-3sp orbitals, while oxygen-2sp orbitals contribute to the deeper valence states. The delocalization lifetimes of the oxygen-1s and sulfur-2p excited states are estimated from a core-hole clock method to be about 9 ± 1 and 125 ± 25 fs, respectively.

  2. Occupied and unoccupied electronic structures of an L-cysteine film studied by core-absorption and resonant photoelectron spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, M., E-mail: kamada@cc.saga-u.ac.jp; Hideshima, T.; Azuma, J.; Yamamoto, I.; Imamura, M.; Takahashi, K. [Synchrotron Light Application Center, Saga University, Honjo 1, Saga 840-8502 (Japan)

    2016-04-15

    Unoccupied and occupied electronic structures of an L-cysteine film have been studied by absorption and resonant photoelectron spectroscopies. Core absorptions at S-L, C-K, N-K, and O-K levels indicate that the lower unoccupied states are predominantly composed of oxygen-2p, carbon-2p, and sulfur-4s+3d orbitals, while higher unoccupied states may be attributed dominantly to nitrogen-np (n ≥ 3), oxygen-np (n ≥ 3), and sulfur-ns+md (n ≥ 4,  m ≥ 3) orbitals. Resonant photoelectron spectra at S-L{sub 23} and O-K levels indicate that the highest occupied state is originated from sulfur-3sp orbitals, while oxygen-2sp orbitals contribute to the deeper valence states. The delocalization lifetimes of the oxygen-1s and sulfur-2p excited states are estimated from a core-hole clock method to be about 9 ± 1 and 125 ± 25 fs, respectively.

  3. Influence of Carbon Sources and Electron Shuttles on Ferric Iron Reduction by Cellulomonas sp. Strain ES6

    Energy Technology Data Exchange (ETDEWEB)

    Erin K. Field; Robin Gerlach; Sridhar Viamajala; Laura K. Jennings; Alfred B. Cunningham; Brent M. Peyton; William A. Apel

    2011-09-01

    The reduction of hexavalent chromium, Cr(VI), to trivalent chromium, Cr(III), can be an important aspect of remediation processes at Department of Energy (DOE) and other contaminated sites. Cellulomonas species are found at several Cr(VI) contaminated and uncontaminated locations at the DOE site in Hanford, Washington. Members of this genus have demonstrated the ability to effectively reduce Cr(VI) to Cr(III) fermentatively and therefore play a potential role in hexavalent chromium remediation at this site. Batch studies were conducted with Cellulomonas sp. strain ES6 to assess the influence of various carbon sources, iron minerals, and electron shuttling compounds on Cr(VI) reduction. These chemical species are likely to be present in these terrestrial environments during in situ bioremediation. Results indicated that there were a number of interactions between these compounds that influenced Cr(VI) reduction rates. The type of carbon source as well as the type of electron shuttle present influenced Cr(VI) reduction rates. When an electron shuttle, such as anthraquinone-2,6-disulfonate (AQDS), was present in the system, reduction rates increased significantly. Biologically reduced AQDS (AHDS) reduced Cr(VI) almost instantaneously. The presence of iron minerals and their concentrations did not significantly influence Cr(VI) reduction rates. However, strain ES6 or AQDS could directly reduce surface-associated Fe(III) to Fe(II) which was capable of reducing Cr(VI) at a near instantaneous rate. These results suggest the rate limiting step in these systems is the transfer of electrons from strain ES6 to the intermediate or terminal electron acceptor whether that is Cr(VI), Fe(III), or AQDS.

  4. Study of electron transmission through thin metallic films by the electron moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Babikova, Yu.F.; Vakar, O.M.; Gruzin, O.M.; Petrikin, Yu.V.

    1983-01-01

    Results of the experimental study of the transmission of conversion electrons through aluminium, iron, tin and gold films are presented. Absorption of resonance electrons of the Moessbauer nuclide 57 Fe, formed during target irradiation with γ-quanta of 57 Co source in chromium matrix has been studied. It is asserted that absorption of conversion electrons in films of different elements is similar; at that, like in the case of β-particles, the law of absorption of resonance electrons, emitted from the flat layer, is exponential For conversion electrons of the Moessbauer nuclide 57 Fe the absorption coefficient is (0.025+-0.002) cm 2 /μg, which in the case of iron absorbing film corresponds to (20.0+-1.0)x10 4 cm -1

  5. Selective Two-Photon Absorptive Resonance Femtosecond-Laser Electronic-Excitation Tagging (STARFLEET) Velocimetry in Flow and Combustion Diagnostics

    Science.gov (United States)

    Jiang, Naibo; Halls, Benjamin R.; Stauffer, Hans U.; Roy, Sukesh; Danehy, Paul M.; Gord, James R.

    2016-01-01

    Selective Two-Photon Absorptive Resonance Femtosecond-Laser Electronic-Excitation Tagging (STARFLEET), a non-seeded ultrafast-laser-based velocimetry technique, is demonstrated in reactive and non-reactive flows. STARFLEET is pumped via a two-photon resonance in N2 using 202.25-nm 100-fs light. STARFLEET greatly reduces the per-pulse energy required (30 µJ/pulse) to generate the signature FLEET emission compared to the conventional FLEET technique (1.1 mJ/pulse). This reduction in laser energy results in less energy deposited in the flow, which allows for reduced flow perturbations (reactive and non-reactive), increased thermometric accuracy, and less severe damage to materials. Velocity measurements conducted in a free jet of N2 and in a premixed flame show good agreement with theoretical velocities and further demonstrate the significantly less-intrusive nature of STARFLEET.

  6. UV-Visible Absorption Spectroscopy Enhanced X-ray Crystallography at Synchrotron and X-ray Free Electron Laser Sources.

    Science.gov (United States)

    Cohen, Aina E; Doukov, Tzanko; Soltis, Michael S

    2016-01-01

    This review describes the use of single crystal UV-Visible Absorption micro-Spectrophotometry (UV-Vis AS) to enhance the design and execution of X-ray crystallography experiments for structural investigations of reaction intermediates of redox active and photosensitive proteins. Considerations for UV-Vis AS measurements at the synchrotron and associated instrumentation are described. UV-Vis AS is useful to verify the intermediate state of an enzyme and to monitor the progression of reactions within crystals. Radiation induced redox changes within protein crystals may be monitored to devise effective diffraction data collection strategies. An overview of the specific effects of radiation damage on macromolecular crystals is presented along with data collection strategies that minimize these effects by combining data from multiple crystals used at the synchrotron and with the X-ray free electron laser.

  7. Temporally resolved characterization of shock-heated foam target with Al absorption spectroscopy for fast electron transport study

    Energy Technology Data Exchange (ETDEWEB)

    Yabuuchi, T.; Sawada, H.; Wei, M. S.; Beg, F. N. [Center for Energy Research, University of California, San Diego, La Jolla, California 92093 (United States); Regan, S. P.; Anderson, K.; Betti, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Hund, J.; Paguio, R. R.; Saito, K. M.; Stephens, R. B. [General Atomics, San Diego, California 92186 (United States); Key, M. H.; Mackinnon, A. J.; McLean, H. S.; Patel, P. K.; Wilks, S. C. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2012-09-15

    The CH foam plasma produced by a laser-driven shock wave has been characterized by a temporally resolved Al 1s-2p absorption spectroscopy technique. A 200 mg/cm{sup 3} foam target with Al dopant was developed for this experiment, which used an OMEGA EP [D. D. Meyerhofer et al., J. Phys.: Conf. Ser. 244, 032010 (2010)] long pulse beam with an energy of 1.2 kJ and 3.5 ns pulselength. The plasma temperatures were inferred with the accuracy of 5 eV from the fits to the measurements using an atomic physics code. The results show that the inferred temperature is sustained at 40-45 eV between 6 and 7 ns and decreases to 25 eV at 8 ns. 2-D radiation hydrodynamic simulations show a good agreement with the measurements. Application of the shock-heated foam plasma platform toward fast electron transport experiments is discussed.

  8. Intestinal absorbtion from therapeutic iron doses

    International Nuclear Information System (INIS)

    Werner, E.

    1977-01-01

    On a total of 105 persons with normal iron stores, iron depletion, and iron deficiency the intestinal absorption from therapeutic iron doses (100 mg Fe and 50 mg Fe as ferrous glycocoll sulphate) of a special galenic form was measured. The measurements were performed by means of a whole-body counter and preparations labelled with radio iron ( 59 Fe). Mean values of absorption rates from 100 mg Fe in healthy males were 5.0% and in healthy females 5.6% whereas in latent iron deficiency and in iron deficiency anemia mean values of 10% and 13% were obtained, respectively. The maximum absorption rate of 20 to 25% is reached already in the late stage of latent iron deficiency. Advancing severeness of iron deficiency is not followed by an increase of iron absorption. Investigations an 21 persons showed no significant difference between absorption rates of the galenic preparations used when administered orally before or after breakfast, respectively. (orig.) [de

  9. Current understanding of iron homeostasis.

    Science.gov (United States)

    Anderson, Gregory J; Frazer, David M

    2017-12-01

    Iron is an essential trace element, but it is also toxic in excess, and thus mammals have developed elegant mechanisms for keeping both cellular and whole-body iron concentrations within the optimal physiologic range. In the diet, iron is either sequestered within heme or in various nonheme forms. Although the absorption of heme iron is poorly understood, nonheme iron is transported across the apical membrane of the intestinal enterocyte by divalent metal-ion transporter 1 (DMT1) and is exported into the circulation via ferroportin 1 (FPN1). Newly absorbed iron binds to plasma transferrin and is distributed around the body to sites of utilization with the erythroid marrow having particularly high iron requirements. Iron-loaded transferrin binds to transferrin receptor 1 on the surface of most body cells, and after endocytosis of the complex, iron enters the cytoplasm via DMT1 in the endosomal membrane. This iron can be used for metabolic functions, stored within cytosolic ferritin, or exported from the cell via FPN1. Cellular iron concentrations are modulated by the iron regulatory proteins (IRPs) IRP1 and IRP2. At the whole-body level, dietary iron absorption and iron export from the tissues into the plasma are regulated by the liver-derived peptide hepcidin. When tissue iron demands are high, hepcidin concentrations are low and vice versa. Too little or too much iron can have important clinical consequences. Most iron deficiency reflects an inadequate supply of iron in the diet, whereas iron excess is usually associated with hereditary disorders. These disorders include various forms of hemochromatosis, which are characterized by inadequate hepcidin production and, thus, increased dietary iron intake, and iron-loading anemias whereby both increased iron absorption and transfusion therapy contribute to the iron overload. Despite major recent advances, much remains to be learned about iron physiology and pathophysiology. © 2017 American Society for Nutrition.

  10. Performance of Iron Plaque of Wetland Plants for Regulating Iron, Manganese, and Phosphorus from Agricultural Drainage Water

    Directory of Open Access Journals (Sweden)

    Xueying Jia

    2018-01-01

    Full Text Available Agricultural drainage water continues to impact watersheds and their receiving water bodies. One approach to mitigate this problem is to use surrounding natural wetlands. Our objectives were to determine the effect of iron (Fe-rich groundwater on phosphorus (P removal and nutrient absorption by the utilization of the iron plaque on the root surface of Glyceria spiculosa (Fr. Schmidt. Rosh. The experiment was comprised of two main factors with three regimes: Fe2+ (0, 1, 20, 100, 500 mg·L−1 and P (0.01, 0.1, 0.5 mg·L−1. The deposition and structure of iron plaque was examined through a scanning electron microscope and energy-dispersive X-ray analyzer. Iron could, however, also impose toxic effects on the biota. We therefore provide the scanning electron microscopy (SEM on iron plaques, showing the essential elements were iron (Fe, oxygen (O, aluminum (Al, manganese (Mn, P, and sulphur (S. Results showed that (1 Iron plaque increased with increasing Fe2+ supply, and P-deficiency promoted its formation; (2 Depending on the amount of iron plaque on roots, nutrient uptake was enhanced at low levels, but at higher levels, it inhibited element accumulation and translocation; (3 The absorption of manganese was particularly affected by iron plague, which also enhanced phosphorus uptake until the external iron concentration exceeded 100 mg·L−1. Therefore, the presence of iron plaque on the root surface would increase the uptake of P, which depends on the concentration of iron-rich groundwater.

  11. Electronic structure study of Co doped CeO2 nanoparticles using X-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Kumar, Shalendra; Gautam, Sanjeev; Song, T.K.; Chae, Keun Hwa; Jang, K.W.; Kim, S.S.

    2014-01-01

    Highlights: • The electronic structural of Co–CeO 2 nanoparticles is investigated using XAFS. • Ce M 5,4 , Ce L 3 and O K edge NEXAFS reveal that the Ce-ions are in +4 valence state. • The NEXAFS spectrum performed at Co L3,2-edge confirms Co-ion in 2+ state. • The EXAFS analysis also show that Co ions are occupying Ce position in doped CeO 2 . • The distances between Ce–O and Ce–Ce/Co in all shells decreases with Co doping. - Abstract: We investigated the electronic structure of well characterized Co doped CeO 2 nanoparticles using X-ray absorption fine structure (XAFS) spectroscopy. Near edge X-ray absorption fine structure (NEXAFS) spectra at Ce M 5,4 , Ce L 3 and O K-edge conclude that the Ce-ions are in +4 valence state in pure as well as in Co doped CeO 2 nanoparticles. The local structure around Ce-atom in Co doped CeO 2 nanoparticles was also determined using extended X-ray absorption fine structure (EXAFS) spectroscopy at Ce L 3 edge. The EXAFS analysis suggest that the inter-atomic distance of Ce–O, Ce–Ce/Co decreases with Co doping, which indicate a contraction of the lattice. The decease in Ce–O distance also reflect that there is a formation of oxygen vacancies in CeO 2 matrix. The Debye–Waller factor also shows the consistent behaviour for all the coordination shells. The atomic multiplet calculations for Co L 3,2 -edge was performed to determine the valence state, symmetry and field splitting, which reflect that Co-ions are in 2+ state and substituted at Ce-site with crystal field splitting of 10Dq=-0.57eV. The XAFS measurements reveal that the Co-ions occupy the Ce position in the CeO 2 host matrix and create a oxygen vacancy

  12. Iron environment in ferritin with large amounts of phosphate, from Azotobacter vinelandii and horse spleen, analyzed using Extended X-ray Absorption fine Structure (EXAFS)

    International Nuclear Information System (INIS)

    Rohrer, J.S.; Islam, Q.T.; Sayes, D.E.; Theil, E.C.; Watt, G.D.

    1990-01-01

    The iron core of proteins in the ferritin family displays structural variations that includes phosphate content was well as the number and the degree of ordering of the iron atoms. Earlier studies had shown that ferritin iron cores naturally high in phosphate, e.g., Azotobacter vinelandii (AV) ferritin had decreased long-range order. Here, the influence of phosphate on the local structure around iron in ferritin cores is reported, comparing the EXAFS of AV ferritin, reconstituted ferritin and native horse spleen ferritin. In contrast, when the phosphate content was high in AV ferritin and horse spleen ferritin reconstituted with phosphate, the average iron atom had five to six phosphorus neighbors at 3.17 angstrom. Moreover, the number of detectable iron neighbors was lower when phosphate was high or present during reconstitution and the interatomic distance was longer indicating that some phosphate bridges neighboring iron atoms. However, the decrease in the number of detectable iron-iron neighbors compared to HSF and the higher number of Fe-P interactions relative to Fe-Fe interactions suggest that some phosphate ligands were chain termini, or blocked crystal growth, and/or introduced defects which contributed both to the long-range disorder and to altered redox properties previously observed in AV ferritin

  13. Spin-wave propagation and spin-polarized electron transport in single-crystal iron films

    Science.gov (United States)

    Gladii, O.; Halley, D.; Henry, Y.; Bailleul, M.

    2017-11-01

    The techniques of propagating spin-wave spectroscopy and current-induced spin-wave Doppler shift are applied to a 20-nm-thick Fe/MgO(001) film. The magnetic parameters extracted from the position of the spin-wave resonance peaks are very close to those tabulated for bulk iron. From the zero-current propagating wave forms, a group velocity of 4 km/s and an attenuation length of about 6 μ m are extracted for 1.6-μ m -wavelength spin wave at 18 GHz. From the measured current-induced spin-wave Doppler shift, we extract a surprisingly high degree of spin polarization of the current of 83 % , which constitutes the main finding of this work. This set of results makes single-crystalline iron a promising candidate for building devices utilizing high-frequency spin waves and spin-polarized currents.

  14. New innovative electrocoagulation (EC) treatment technology for BWR colloidal iron utilizing the seeding and filtration electronically (SAFETTM) system

    International Nuclear Information System (INIS)

    Denton, Mark S.; Bostick, William D.

    2007-01-01

    is 1) to break the colloid (i.e., break the outer radius repulsive charges of the similar charged colloidal particles), 2) allow these particles to now flocculate (floc), and 3) form a type of floc that is more readily filterable, and, thus, de-waterable. This task has been carried out with the innovative application of electronically seeding the feed stream with the metal of choice, and without the addition of chemicals common to ferri-flocking, or polymer addition. This patent-pending new system and technique is called Seeding And Filtration Electronically, or the SAFE TM System. Once the colloid has been broken and flocking has begun, removal of the resultant floc can be carried out by standard, back-washable (or, in simple cases, dead-end) filters; or simply in de-waterable HICs or liners. Such applications include low level radwaste (LLW) from both PWRs and BWRs, fuel pools, storage basins, salt water collection tanks, etc. For the removal of magnetic materials, such as some BWR irons, an Electro Magnetic Filter (EMF) was developed to couple with the Electro Coagulation (EC), (or metal-Flocking) Unit. In the advent that the waste stream primarily contains magnetic materials (e.g., boiler condensates and magnetite, and he-magnetite from BWRs), the material was simply filtered using the EMF. Bench-, pilot- and full-scale systems have been assembled and applied on actual plant waste samples quite successfully. The effects of initial feed pH and conductivity, as well as flocculation retention times was examined prior to applying the production equipment into the field. Since the initial studies (Denton, et al, EPRI, 2006), the ultimate success of field applications is now being demonstrated as the next development phase. For such portable field demonstrations and demand systems, a fully self enclosed (secondary containment) EC system was first developed and assembled in a modified B 25 Box (Floc-In-A-Box) and is being deployed to a number of NPP sites. Finally, a

  15. Localized holes and delocalized electrons in photoexcited inorganic perovskites: Watching each atomic actor by picosecond X-ray absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    Fabio G. Santomauro

    2017-07-01

    Full Text Available We report on an element-selective study of the fate of charge carriers in photoexcited inorganic CsPbBr3 and CsPb(ClBr3 perovskite nanocrystals in toluene solutions using time-resolved X-ray absorption spectroscopy with 80 ps time resolution. Probing the Br K-edge, the Pb L3-edge, and the Cs L2-edge, we find that holes in the valence band are localized at Br atoms, forming small polarons, while electrons appear as delocalized in the conduction band. No signature of either electronic or structural changes is observed at the Cs L2-edge. The results at the Br and Pb edges suggest the existence of a weakly localized exciton, while the absence of signatures at the Cs edge indicates that the Cs+ cation plays no role in the charge transport, at least beyond 80 ps. This first, time-resolved element-specific study of perovskites helps understand the rather modest charge carrier mobilities in these materials.

  16. Electronic and spatial structures of water-soluble dinitrosyl iron complexes with thiol-containing ligands underlying their ability to act as nitric oxide and nitrosonium ion donors.

    Science.gov (United States)

    Vanin, Anatoly F; Burbaev, Dosymzhan Sh

    2011-01-01

    The ability of mononuclear dinitrosyl iron commplexes (M-DNICs) with thiolate ligands to act as NO donors and to trigger S-nitrosation of thiols can be explain only in the paradigm of the model of the [Fe(+)(NO(+))(2)] core ({Fe(NO)(2)}(7) according to the Enemark-Feltham classification). Similarly, the {(RS(-))(2)Fe(+)(NO(+))(2)}(+) structure describing the distribution of unpaired electron density in M-DNIC corresponds to the low-spin (S = 1/2) state with a d(7) electron configuration of the iron atom and predominant localization of the unpaired electron on MO(d(z2)) and the square planar structure of M-DNIC. On the other side, the formation of molecular orbitals of M-DNIC including orbitals of the iron atom, thiolate and nitrosyl ligands results in a transfer of electron density from sulfur atoms to the iron atom and nitrosyl ligands. Under these conditions, the positive charge on the nitrosyl ligands diminishes appreciably, the interaction of the ligands with hydroxyl ions or with thiols slows down and the hydrolysis of nitrosyl ligands and the S-nitrosating effect of the latter are not manifested. Most probably, the S-nitrosating effect of nitrosyl ligands is a result of weak binding of thiolate ligands to the iron atom under conditions favoring destabilization of M-DNIC.

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

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Walter N.L. dos [Departamento de Ciencias Exatas e da Terra, Universidade do Estado da Bahia, Salvador, Bahia (Brazil); Universidade Federal da Bahia, Instituto de Quimica, Campus Ondina, Salvador, Bahia, 40170-290 Brazil (Brazil)], E-mail: wlopes@uneb.br; Brandao, Geovani C.; Portugal, Lindomar A.; David, Jorge M.; Ferreira, Sergio L.C. [Universidade Federal da Bahia, Instituto de Quimica, Campus Ondina, Salvador, Bahia, 40170-290 Brazil (Brazil)

    2009-06-15

    This paper proposes the use of photo-oxidation with UV radiation/H{sub 2}O{sub 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{sup - 1}), this procedure allows the determination of iron and manganese with limits of detection of 30 and 22 {mu}g L{sup - 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{sup - 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{sup - 1} for iron and from 1.30 to 1.91 mg L{sup - 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)

  18. Coupled Effect of Ferrous Ion and Oxygen on the Electron Selectivity of Zerovalent Iron for Selenate Sequestration.

    Science.gov (United States)

    Qin, Hejie; Li, Jinxiang; Yang, Hongyi; Pan, Bingcai; Zhang, Weiming; Guan, Xiaohong

    2017-05-02

    Although the electron selectivity (ES) of zerovalent iron (ZVI) for target contaminant and its utilization ratio (UR) decide the removal capacity of ZVI, little effort has been made to improve them. Taking selenate [Se(VI)] as a target contaminant, this study investigated the coupled influence of aeration gas and Fe(II) on the ES and UR of ZVI. Oxygen was necessary for effective removal of Se(VI) by ZVI without Fe(II) addition. Due to the application of 1.0 mM Fe(II), the ES of ZVI was increased from 3.2-3.6% to 6.2-6.8% and the UR of ZVI was improved by 5.0-19.4% under aerobic conditions, which resulted in a 100-180% increase in the Se(VI) removal capacity by ZVI. Se(VI) reduction by Fe 0 was a heterogeneous redox reaction, and the enrichment of Se(VI) on ZVI surface was the first step of electron transfer from Fe 0 core to Se(VI). Oxygen promoted the generation of iron (hydr)oxides, which facilitated the enrichment of Se(VI) on the ZVI particle surface. Therefore, the high oxygen fraction (25-50%) in the purging gas resulted in only a slight decrease in the ES of ZVI. Fe(II) addition resulted in a pH drop and promoted the generation of lepidocrocite and magnetite, which benefited Se(VI) adsorption and the following electron transfer from underlying Fe 0 to surface-located Se(VI).

  19. Iron hexacyanide/cytochrome-C - intramolecular electron transfer and binding constants - (pulse radiolytic study). Progress report

    International Nuclear Information System (INIS)

    Ilan, Y.; Shafferman, A.

    Internal oxidation and reduction rates of horse cytochrome-c in the complexes, CII.Fe/sup III/(CN) -3 6 and CIII.Fe/sup II/(CN) -4 6 , are 4.6.10 4 s -1 and 3.3.10 2 s -1 , respectively. The binding sites of the iron hexacyanide ions on either CII or CIII are kinetically almost indistinguishable; binding constants range from 0.87.10 3 to 2.10 3 M -1 . The present pulse radiolytic kinetic data are compared with that from N.M.R, T-jump and equilibrium dialysis studies

  20. Electronic and Spatial Structures of Water-Soluble Dinitrosyl Iron Complexes with Thiol-Containing Ligands Underlying Their Ability to Act as Nitric Oxide and Nitrosonium Ion Donors

    OpenAIRE

    Vanin, Anatoly F.; Burbaev, Dosymzhan Sh.

    2011-01-01

    The ability of mononuclear dinitrosyl iron commplexes (M-DNICs) with thiolate ligands to act as NO donors and to trigger S-nitrosation of thiols can be explain only in the paradigm of the model of the [Fe+(NO+)2] core ({Fe(NO)2}7 according to the Enemark-Feltham classification). Similarly, the {(RS−)2Fe+(NO+)2}+ structure describing the distribution of unpaired electron density in M-DNIC corresponds to the low-spin (S = 1/2) state with a d7 electron configuration of the iron atom and predomin...

  1. Electron Emission by N6+ Ions Scattered at a Magnetized Iron Surface

    International Nuclear Information System (INIS)

    Solleder, B.; Lemell, C.; Burgdoerfer, J.; Tokesi, K.

    2006-01-01

    Complete text of publication follows. Magnetized materials are of considerable interest in the electronics industry (hard discs, spintronics, etc.). A detailed understanding of the properties of magnetized surfaces is therefore important to optimize technical applications. In the last decades, different experimental techniques have been developed to probe spin effects in magnetized materials. In this work the spin polarization of electrons emitted during the impact of N 6+ ions on a magnetized Fe surface is investigated. We study potential emission (PE) of electrons as well as secondary electron (SE) production and transport in the target with the help of Monte Carlo (MC) simulations. Spin dependence of electron transfer processes and of transport in the solid are included. Fig. 1 shows the results of our simulation for the energy distribution and spin polarization of emitted electrons in comparison with experimental data of Pfandzelter et al. [1] for the interaction of N 6+ ions with magnetized Fe. Electrons with energies higher than 200 eV are predominantly PE electrons, emitted close to the surface via autoionization (AI), Auger capture (AC) and Auger deexcitation (AD) channels. Low energy electrons are dominated by promoted, autoionized, and secondary electrons. The polarization of above surface electrons is determined by the high of the potential barrier separating projectile and target. At large distances, the barrier drops only slightly below the Fermi edge and enables transitions of electrons from this part of the band structure which has about 50% polarization. These electrons are transferred to high n states feeding promotion and AI processes between high lying states. Electrons emitted by these processes therefore reflect the polarization near the Fermi edge. Close to the surface, the barrier is low enough to allow for electron capture from the entire conduction band. K-Auger electrons are emitted in immediate vicinity of the surface and therefore mirror

  2. Measurement of the electronic absorption coefficient for 57Co 14.4 keV gamma photons in aluminium using the Moessbauer effect as a monochromator

    International Nuclear Information System (INIS)

    Rajan, N.; Nigam, A.K.

    1984-01-01

    The total electronic absorption coefficient for 14.4 keV gamma photons in aluminium, has been measured experimentally, for the first time, using the Moessbauer effect as a monochromator. This data is important for the determination of background in Moessbauer recoilless fraction measurements especially if the energy of X-rays of the source host lattice lie near the 14.4 keV photon energy (e.g. in Rh and Pd) in which case electronic absorption coefficients should be known precisely. The coefficient obtained by interpolation from available values at other energies differ from our experimental value by as much as 20%. It is shown that this can lead to errors, in recoilless fraction values, which are far from negligible. The above absorption coefficient for aluminium was measured to be 11+-1 cm 2 /g. (orig.)

  3. Iron speciation of airborne subway particles by the combined use of energy dispersive electron probe X-ray microanalysis and Raman microspectrometry.

    Science.gov (United States)

    Eom, Hyo-Jin; Jung, Hae-Jin; Sobanska, Sophie; Chung, Sang-Gwi; Son, Youn-Suk; Kim, Jo-Chun; Sunwoo, Young; Ro, Chul-Un

    2013-11-05

    Quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), known as low-Z particle EPMA, and Raman microspectrometry (RMS) were applied in combination for an analysis of the iron species in airborne PM10 particles collected in underground subway tunnels. Iron species have been reported to be a major chemical species in underground subway particles generated mainly from mechanical wear and friction processes. In particular, iron-containing particles in subway tunnels are expected to be generated with minimal outdoor influence on the particle composition. Because iron-containing particles have different toxicity and magnetic properties depending on their oxidation states, it is important to determine the iron species of underground subway particles in the context of both indoor public health and control measures. A recently developed analytical methodology, i.e., the combined use of low-Z particle EPMA and RMS, was used to identify the chemical species of the same individual subway particles on a single particle basis, and the bulk iron compositions of airborne subway particles were also analyzed by X-ray diffraction. The majority of airborne subway particles collected in the underground tunnels were found to be magnetite, hematite, and iron metal. All the particles collected in the tunnels of underground subway stations were attracted to permanent magnets due mainly to the almost ubiquitous ferrimagnetic magnetite, indicating that airborne subway particles can be removed using magnets as a control measure.

  4. In situ Transmission Electron Microscopy He{sup +} implantation and thermal aging of nanocrystalline iron

    Energy Technology Data Exchange (ETDEWEB)

    Muntifering, Brittany, E-mail: brmunti@sandia.gov [Sandia National Laboratories, Albuquerque, NM, 87185 (United States); Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, 60208 (United States); Fang, Youwu [Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, 60208 (United States); Leff, Asher C. [Department of Materials Science & Engineering, Drexel University, Philadelphia, PA, 19104 (United States); Dunn, Aaron [Sandia National Laboratories, Albuquerque, NM, 87185 (United States); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, UMI 2958 Georgia Tech CNRS, 57070, Metz (France); Qu, Jianmin [Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, 60208 (United States); School of Engineering, Tufts University, Medford, MA, 02155 (United States); Taheri, Mitra L. [Department of Materials Science & Engineering, Drexel University, Philadelphia, PA, 19104 (United States); Dingreville, Remi; Hattar, Khalid [Sandia National Laboratories, Albuquerque, NM, 87185 (United States)

    2016-12-15

    The high density of interfaces in nanostructured materials are hypothesized to improve radiation tolerance compared to coarse-grained materials. In order to investigate the roles of vacancies, self-interstitials, and helium, both room temperature in situ TEM He{sup +} implantation and annealing, as well as high temperature He{sup +} implantation was performed on nanocrystalline iron. Dislocation loops are formed by the accumulation of mobile point defects rather than by displacement cascades at intermediate temperatures. Around 600 °C, loops disappeared through gradual shrinking, which is hypothesized to correspond to the annihilation of self-interstitial atoms by mobile vacancies that also resulted in cavity formation. The room temperature implantation resulted in cavities evenly distributed throughout the grain after annealing, whereas cavities were predominately observed at grain boundaries for the elevated temperature implantation. This difference is associated with the formation of stable helium-vacancy complexes in the grains during room temperature implantation, which is not present during high temperature implantation. - Highlights: • In situ TEM He{sup +} implantation and annealing was performed on nanocrystalline iron. • Small grains limited loop size and resulted in complete disappearance of loops by 600 °C. • Implantation followed by annealing resulted in cavities evenly distributed through grain. • Cavities predominately observed at grain boundaries after He{sup +} implantation at 600 °C.

  5. Electron-capture and Low-mass Iron-core-collapse Supernovae: New Neutrino-radiation-hydrodynamics Simulations

    Science.gov (United States)

    Radice, David; Burrows, Adam; Vartanyan, David; Skinner, M. Aaron; Dolence, Joshua C.

    2017-11-01

    We present new 1D (spherical) and 2D (axisymmetric) simulations of electron-capture (EC) and low-mass iron-core-collapse supernovae (SN). We consider six progenitor models: the ECSN progenitor from Nomoto; two ECSN-like low-mass low-metallicity iron-core progenitors from A. Heger (2016, private communication); and the 9, 10, and 11 {M}⊙ (zero-age main-sequence) progenitors from Sukhbold et al. We confirm that the ECSN and ESCN-like progenitors explode easily even in 1D with explosion energies of up to a 0.15 Bethes (1 {{B}}\\equiv {10}51 {erg}), and are a viable mechanism for the production of very-low-mass neutron stars. However, the 9, 10, and 11 {M}⊙ progenitors do not explode in 1D and are not even necessarily easier to explode than higher-mass progenitor stars in 2D. We study the effect of perturbations and of changes to the microphysics and we find that relatively small changes can result in qualitatively different outcomes, even in 1D, for models sufficiently close to the explosion threshold. Finally, we revisit the impact of convection below the protoneutron star (PNS) surface. We analyze 1D and 2D evolutions of PNSs subject to the same boundary conditions. We find that the impact of PNS convection has been underestimated in previous studies and could result in an increase of the neutrino luminosity by up to factors of two.

  6. Study of thermochemically reduced and electron-irradiated LiNbO3 single crystals by positron annihilation and optical absorption measurements

    International Nuclear Information System (INIS)

    Pareja, R.; Gonzalez, R.; Pedrosa, M.A.

    1984-01-01

    Irradiation of LiNbO 3 single crystals using Van de Graaff electrons with an energy of 1.5 MeV introduces an optical absorption band similar to that observed in thermochemically reduced samples. As-grown, reduced, or irradiated crystals show single-component positron lifetime spectra with an average decay time of 234 ps. (author)

  7. Observation of magnetostatic wave electron absorption in ferrite-high temperature superconductor structure. Nablyudenie ehlektronnogo pogloshcheniya magnitostaticheskikh voln v strukture ferrit-vysokotemperaturnyj sverkhprovodnik

    Energy Technology Data Exchange (ETDEWEB)

    Anfinogenov, V B; Gulyaev, Yu V; Zil' berman, P E; Kotelyanskij, I M; Polzikova, N I; Sukhanov, A A [AN SSSR, Moscow (USSR). Inst. Radiotekhniki i Ehlektroniki

    1989-07-26

    Conditions for magneto-static wave (MSW) propagation in laminar structures ferrite-high-temperature superconductor (YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}) and effect of transition into superconducting state under the temperature drop on these conditions are investigated. MSW electron absorption effrect in such structures (strongly dependent on the temperature) is detected and its interpretation is given.

  8. Electronic properties and surface reactivity of SrO-terminated SrTiO3 and SrO-terminated iron-doped SrTiO3.

    Science.gov (United States)

    Staykov, Aleksandar; Tellez, Helena; Druce, John; Wu, Ji; Ishihara, Tatsumi; Kilner, John

    2018-01-01

    Surface reactivity and near-surface electronic properties of SrO-terminated SrTiO 3 and iron doped SrTiO 3 were studied with first principle methods. We have investigated the density of states (DOS) of bulk SrTiO 3 and compared it to DOS of iron-doped SrTiO 3 with different oxidation states of iron corresponding to varying oxygen vacancy content within the bulk material. The obtained bulk DOS was compared to near-surface DOS, i.e. surface states, for both SrO-terminated surface of SrTiO 3 and iron-doped SrTiO 3 . Electron density plots and electron density distribution through the entire slab models were investigated in order to understand the origin of surface electrons that can participate in oxygen reduction reaction. Furthermore, we have compared oxygen reduction reactions at elevated temperatures for SrO surfaces with and without oxygen vacancies. Our calculations demonstrate that the conduction band, which is formed mainly by the d-states of Ti, and Fe-induced states within the band gap of SrTiO 3 , are accessible only on TiO 2 terminated SrTiO 3 surface while the SrO-terminated surface introduces a tunneling barrier for the electrons populating the conductance band. First principle molecular dynamics demonstrated that at elevated temperatures the surface oxygen vacancies are essential for the oxygen reduction reaction.

  9. Electronic structure of deep levels in silicon. A study of gold, magnesium, and iron centers in silicon

    International Nuclear Information System (INIS)

    Thilderkvist, A. L.

    1994-02-01

    The electronic structure of gold, magnesium and iron related deep centers in silicon is investigated. Their deep and shallow levels are studied by means of fourier transform spectroscopy, combined with uniaxial stress and Zeeman spectroscopy. The neutral substitutional gold center in silicon is investigated and the center is paramagnetic, S=1/2, with g||≅2.8 and g≅0, and has a static distortion. Reorientation between different equivalent distortions is observed even at 1.9 K. A gold pair center in silicon is studied and several line series, with a zero-phonon line followed by several phonon replicas, are observed. Uniaxial stress and Zeeman results reveal a trigonal symmetry of the center, which together with the high dissociation energy of 1.7 eV suggests that the center consists of two nearest-neighbor substitutional gold atoms. A divacancy model is employed to explain the electronic properties of the center. The interstitial magnesium double donor in silicon in its two charge states Mg o and Mg + is investigated. Deviations in the binding energies of the excited states from those calculated within the effective-mass theory (EMT) are found and explained by a perturbation in the central-cell region. The quadratic Zeeman effect of shallow donors in silicon is analyzed within the framework of the EMT using a numerical approach. The wave functions are calculated in a discrete radial mesh and the Zeeman Hamiltonian has be evaluated for the lowest excited states for fields up to 6 T. The neutral interstitial iron defect in silicon gives rise to two sets of line spectra. The first set arises when an electron is excited to a shallow donor like state where the electron is decoupled from the Fe + core which has a 4 T 1 ground state term. The second set arises when an excited electron of a 1 symmetry is coupled by exchange interaction to the core, yielding at 5 T 1 final state. Experiments determine the multiplet splitting of the 4 T 1 and 5 T 1 states due to spring

  10. Transmission electron microscopy characterization of laser-clad iron-based alloy on Al-Si alloy

    International Nuclear Information System (INIS)

    Mei, Z.; Wang, W.Y.; Wang, A.H.

    2006-01-01

    Microstructure characterization is important for controlling the quality of laser cladding. In the present work, a detailed microstructure characterization by transmission electron microscopy was carried out on the iron-based alloy laser-clad on Al-Si alloy and an unambiguous identification of phases in the coating was accomplished. It was found that there is austenite, Cr 7 C 3 and Cr 23 C 6 in the clad region; α-Al, NiAl 3 , Fe 2 Al 5 and FeAl 2 in the interface region; and α-Al and silicon in the heat-affected region. A brief discussion was given for their existence based on both kinetic and thermodynamic principles

  11. Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition.

    Science.gov (United States)

    Glazyrin, K; Pourovskii, L V; Dubrovinsky, L; Narygina, O; McCammon, C; Hewener, B; Schünemann, V; Wolny, J; Muffler, K; Chumakov, A I; Crichton, W; Hanfland, M; Prakapenka, V B; Tasnádi, F; Ekholm, M; Aichhorn, M; Vildosola, V; Ruban, A V; Katsnelson, M I; Abrikosov, I A

    2013-03-15

    We discover that hcp phases of Fe and Fe(0.9)Ni(0.1) undergo an electronic topological transition at pressures of about 40 GPa. This topological change of the Fermi surface manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio, and Mössbauer center shift observed in our experiments. First-principles simulations within the dynamic mean field approach demonstrate that the transition is induced by many-electron effects. It is absent in one-electron calculations and represents a clear signature of correlation effects in hcp Fe.

  12. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... is blood loss during dialysis. People who have chronic kidney disease also often take other medicines—such as proton ... reduces iron absorption. Other treatments If you have chronic kidney disease and iron-deficiency anemia, your doctor may recommend ...

  13. A role for iron and oxygen chemistry in preserving soft tissues, cells and molecules from deep time

    OpenAIRE

    Schweitzer, Mary H.; Zheng, Wenxia; Cleland, Timothy P.; Goodwin, Mark B.; Boatman, Elizabeth; Theil, Elizabeth; Marcus, Matthew A.; Fakra, Sirine C.

    2014-01-01

    The persistence of original soft tissues in Mesozoic fossil bone is not explained by current chemical degradation models. We identified iron particles (goethite-αFeO(OH)) associated with soft tissues recovered from two Mesozoic dinosaurs, using transmission electron microscopy, electron energy loss spectroscopy, micro-X-ray diffraction and Fe micro-X-ray absorption near-edge structure. Iron chelators increased fossil tissue immunoreactivity to multiple antibodies dramatically, suggesting a ro...

  14. Moessbauer effect studies of magnetic interactions in iron and dilute iron alloys

    International Nuclear Information System (INIS)

    Woude, F. van der; Schurer, P.J.; Sawatzky, G.A.

    1975-01-01

    A temperature-dependent Moessbauer study was conducted in FeX alloys, where X = Al, Si, Ti, V, Cr, Mn, Co, and Ni, aimed at solving the problem of 'what is localized and what is itinerant in iron ferromagnetism'. The experimental results are interpreted using a phenomenological model based on a modified Zener-Vonsovskij theory. Absorption spectra of FeX alloys were measured as a function of temperature. It was found that the 3d magnetic moments in iron were mainly localized while exchange coupling was provided by partly itinerant 3d electrons. (L.D.)

  15. Full-potential theoretical investigations of electron inelastic mean free paths and extended x-ray absorption fine structure in molybdenum

    International Nuclear Information System (INIS)

    Chantler, C T; Bourke, J D

    2014-01-01

    X-ray absorption fine structure (XAFS) spectroscopy is one of the most robust, adaptable, and widely used structural analysis tools available for a range of material classes from bulk solids to aqueous solutions and active catalytic structures. Recent developments in XAFS theory have enabled high-accuracy calculations of spectra over an extended energy range using full-potential cluster modelling, and have demonstrated particular sensitivity in XAFS to a fundamental electron transport property—the electron inelastic mean free path (IMFP). We develop electron IMFP theory using a unique hybrid model that simultaneously incorporates second-order excitation losses, while precisely accounting for optical transitions dictated by the complex band structure of the solid. These advances are coupled with improved XAFS modelling to determine wide energy-range absorption spectra for molybdenum. This represents a critical test case of the theory, as measurements of molybdenum K-edge XAFS represent the most accurate determinations of XAFS spectra for any material. We find that we are able to reproduce an extended range of oscillatory structure in the absorption spectrum, and demonstrate a first-time theoretical determination of the absorption coefficient of molybdenum over the entire extended XAFS range utilizing a full-potential cluster model. (paper)

  16. Unraveling the electronic structures of low-valent naphthalene and anthracene iron complexes: X-ray, spectroscopic, and density functional theory studies

    NARCIS (Netherlands)

    Schnoeckelborg, E.M.; Khusniyarov, M.M.; de Bruin, B.; Hartl, F.; Langer, T.; Eul, M.; Schulz, S.; Poettgen, R.; Wolf, R.

    2012-01-01

    Naphthalene and anthracene transition metalates are potent reagents, but their electronic structures have remained poorly explored. A study of four Cp*-substituted iron complexes (Cp* = pentamethylcyclopentadienyl) now gives rare insight into the bonding features of such species. The highly oxygen-

  17. Electron hopping and temperature dependent oxidation states of iron in ilvaite studied by Moessbauer effect

    International Nuclear Information System (INIS)

    Heilmann, I.U.; Staun Olsen, J.; Olsen, N.B.

    1977-01-01

    The Moessbauer spectrum of ilvaite was measured between 115 K and 898 K, and the energy dispersive X-ray powder pattern was measured between 300 K and 1123 K. Below 500 K the Moessbauer spectrum varies strongly with temperature while the X-ray spectrum remains unchanged. The results are interpreted by electron exchange between nearly identical Fe-sites in ilvaite. (Auth.)

  18. Ruthenium and iron complexes with benzotriazole and benzimidazole derivatives as simple models for proton-coupled electron transfer systems

    Directory of Open Access Journals (Sweden)

    Rocha Reginaldo C.

    2001-01-01

    Full Text Available Iron and ruthenium complexes of the type [M-LH]n (where M = RuII,III(NH35(2+,3+, RuII,III(edta2-,- [edta = ethylenedinitrilotetraacetate], or FeII,III(CN5(3-,2- and LH = benzotriazole or benzimidazole were prepared and characterized in aqueous solutions by means of electrochemical and spectroelectrochemical methods. Special emphasis was given to the pH-dependent redox processes, exhibited by all the investigated complexes. From their related Pourbaix diagrams, which displayed a typically Nernstian behavior, the pKa and formal reduction potential values were extracted. In addition, these E1/2 versus pH curves were also used to illustrate the partitioning relationship concerning the redox and acid-base species, and their interconversion equilibria. The active area in which the dependence of the M III/M II couple on the pH takes place, as delimited by pKaIII and pKaII, was taken into account in order to evaluate the usefulness of such simple complexes as models for proton-coupled electron transfer (PCET. The results were interpreted in terms of the acceptor/donor electronic character of the ligands and sigma,pi-metal-ligand interactions in both redox states of the metal ion.

  19. Effects of pre-irradiation annealing at high temperature on optical absorption and electron paramagnetic resonance of natural pumpellyite mineral

    International Nuclear Information System (INIS)

    Javier-Ccallata, Henry; Filho, Luiz Tomaz; Sartorelli, Maria L.; Watanabe, Shigueo

    2013-01-01

    Highlights: •Natural pumpellyite mineral presents superposition bands around 900 and 1060 nm due Fe 2+ and Fe 3+ . •High temperature annealing influences the EPR and OA spectra. •The behavior of EPR line for 800 and 900 °C can be attributed to forbidden dd transitions due the Fe 3+ . -- Abstract: Natural silicate mineral of pumpellyite, Ca 2 MgAl 2 (SiO 4 )(Si 2 O 7 )(OH) 2 ·(H 2 O), point group A2/m, has been studied concerning high temperature annealing and γ-radiation effects on Optical Absorption (OA) and Electron Paramagnetic Resonance (EPR) properties. Chemical analysis revealed that besides Si, Al, Ca and Mg, other oxides i.e., Fe, Mn, Na, K, Ti and P are present in the structure as impurities. OA measurements of natural and annealed pumpellyite revealed several bands in the visible region due to spin forbidden transitions of Fe 2+ and Fe 3+ . The behaviour of bands around 900 and 1060 nm, with pre-annealing and γ radiation dose, indicating a transition Fe 2+ → e − + Fe 3+ . On the other hand, EPR measurements reveal six lines of Mn 2+ , and satellites due to hyperfine interaction, superimposed on the signal of Fe 3+ around of g = 2. For heat treatment from 800 °C the signal grows significantly and for 900 °C a strong signal of Fe 3+ hides all Mn 2+ lines. The strong growth of this signal indicates that the transitions are due to Fe 3+ dipole–dipole interactions

  20. Hydrogen absorption in U{sub 3}Si{sub 2} and its impact on electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Mašková, Silvie, E-mail: maskova@mag.mff.cuni.cz [Department of Condensed Matter Physics, Charles University, Prague 2, The Czech Republic (Czech Republic); Miliyanchuk, Khrystyna [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Lviv (Ukraine); Havela, Ladislav [Department of Condensed Matter Physics, Charles University, Prague 2, The Czech Republic (Czech Republic)

    2017-04-15

    U{sub 3}Si{sub 2} reversibly absorbs hydrogen at very low H{sub 2} pressures (kPa range), yielding U{sub 3}Si{sub 2}H{sub 1.8}. One characteristic desorption temperature implies that there is only one type of H sites. U{sub 3}Si{sub 2} is a weak Pauli paramagnet (χ < 2·10{sup −8} m{sup 3}/mol U) with the shortest inter-uranium distances between the U atoms in different sheets (d{sub U-U} = 332 pm). The volume-expanded (10%) hydride is a spin fluctuator with temperature dependent magnetic susceptibility and a weak ferromagnetic component gradually arising below T = 100 K. The location of U{sub 3}Si{sub 2}H{sub 1.8} at the verge of magnetic ordering is evidenced by the low temperature specific heat with an upturn in C/T and a dramatic enhancement of the Sommerfeld coefficient of electronic specific heat γ, which reaches 500 mJ/mol f.u. K{sup 2}. - Highlights: •U{sub 3}Si{sub 2} can be hydrogenated at very low H{sub 2} pressure, yielding U{sub 3}Si{sub 2}H{sub 1.8}. •The H absorption to a single H-site is reversible. •Hydrogenation leads to the expansion of the unit cell by 10%. •U{sub 3}Si{sub 2} is a weak Pauli paramagnet. •The hydride is a spin fluctuator with temperature dependent magnetic susceptibility.

  1. Effects of pre-irradiation annealing at high temperature on optical absorption and electron paramagnetic resonance of natural pumpellyite mineral

    Energy Technology Data Exchange (ETDEWEB)

    Javier-Ccallata, Henry, E-mail: henrysjc@gmail.com [Escuela de Ingeniería Electrónica y Telecomunicaciones, Universidad Alas Peruanas Filial Arequipa, Urb. D. A. Carrión G-14, J. L. Bustamante y Rivero, Arequipa (Peru); Laboratório de Sistemas Nanoestruturados, Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina (Brazil); Filho, Luiz Tomaz [Departamento de Física Nuclear, Instituto de Física, Universidade de São Paulo, Rua do Matão, travessa R, 187, CEP 05508-900 São Paulo, SP (Brazil); Faculdade de Tecnologia e Ciências Exatas, Universidade São Judas Tadeu, Rua Taquari 546, São Paulo, SP (Brazil); Sartorelli, Maria L. [Laboratório de Sistemas Nanoestruturados, Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina (Brazil); Watanabe, Shigueo [Departamento de Física Nuclear, Instituto de Física, Universidade de São Paulo, Rua do Matão, travessa R, 187, CEP 05508-900 São Paulo, SP (Brazil)

    2013-09-15

    Highlights: •Natural pumpellyite mineral presents superposition bands around 900 and 1060 nm due Fe{sup 2+}and Fe{sup 3+}. •High temperature annealing influences the EPR and OA spectra. •The behavior of EPR line for 800 and 900 °C can be attributed to forbidden dd transitions due the Fe{sup 3+}. -- Abstract: Natural silicate mineral of pumpellyite, Ca{sub 2}MgAl{sub 2}(SiO{sub 4})(Si{sub 2}O{sub 7})(OH){sub 2}·(H{sub 2}O), point group A2/m, has been studied concerning high temperature annealing and γ-radiation effects on Optical Absorption (OA) and Electron Paramagnetic Resonance (EPR) properties. Chemical analysis revealed that besides Si, Al, Ca and Mg, other oxides i.e., Fe, Mn, Na, K, Ti and P are present in the structure as impurities. OA measurements of natural and annealed pumpellyite revealed several bands in the visible region due to spin forbidden transitions of Fe{sup 2+} and Fe{sup 3+}. The behaviour of bands around 900 and 1060 nm, with pre-annealing and γ radiation dose, indicating a transition Fe{sup 2+} → e{sup −} + Fe{sup 3+}. On the other hand, EPR measurements reveal six lines of Mn{sup 2+}, and satellites due to hyperfine interaction, superimposed on the signal of Fe{sup 3+} around of g = 2. For heat treatment from 800 °C the signal grows significantly and for 900 °C a strong signal of Fe{sup 3+} hides all Mn{sup 2+} lines. The strong growth of this signal indicates that the transitions are due to Fe{sup 3+} dipole–dipole interactions.

  2. Electron paramagnetic resonance and optical absorption study of V{sup 4+} centres in YVO{sub 4} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Garces, N Y [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Stevens, K T [Northrop Grumman Space Technology, Synoptics, Charlotte, NC 28273 (United States); Foundos, G K [Northrop Grumman Space Technology, Synoptics, Charlotte, NC 28273 (United States); Halliburton, L E [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States)

    2004-10-06

    Electron paramagnetic resonance (EPR) has been used to characterize three distinct V{sup 4+} centres in undoped Czochralski-grown yttrium orthovanadate (YVO{sub 4}) crystals. These EPR signals are observed at low temperatures, and their average c-axis splittings between adjacent {sup 51}V hyperfine lines are 40 G, 123 G, and 140 G. We refer to these centres as [V{sup 4+}]{sub A}, [V{sup 4+}]{sub B}, and [V{sup 4+}]{sub C}, respectively. The [V{sup 4+}]{sub A} and [V{sup 4+}]{sub B} centres are present in as-grown crystals. Exposure at 77 K to ionizing radiation (x-rays or an ultraviolet laser beam) destroys these centres and creates the [V{sup 4+}]{sub C} centres. The as-grown state of the crystal is restored upon returning to room temperature. Angular dependence data are used to determine the principal values and principal directions of the g tensor and the {sup 51}V hyperfine tensor for each of the centres. We suggest that the [V{sup 4+}]{sub A} centre is a V{sup 4+} ion adjacent to an oxygen vacancy and that the [V{sup 4+}]{sub B} centre is a V{sup 4+} ion substituting for a Y{sup 3+} ion (i.e. a vanadium antisite defect). The [V{sup 4+}]{sub C} centre is assigned to a V{sup 4+} ion at a regular vanadium site with a nearby stabilizing defect, possibly a Zr{sup 4+} on a Y{sup 3+} site. In as-grown crystals, there is a correlation between the number of [V{sup 4+}]{sub A} centres and the intensity (at 380 nm) of a broad near-edge optical absorption band. This band, now associated with oxygen vacancies, gives YVO{sub 4} a 'yellow' appearance.

  3. An experimental study of the electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles and their electrosynthesized polymers.

    Science.gov (United States)

    Diaw, A K D; Gningue-Sall, D; Yassar, A; Brochon, J-C; Henry, E; Aaron, J-J

    2015-01-25

    Electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles (N-PhPys), including HOPhPy, MeOPhPy, ThPhPy, PhDPy, DPhDPy, PyPhThThPhPy, and their available, electrosynthesized polymers were investigated. Electronic absorption spectra, fluorescence excitation and emission spectra, fluorescence quantum yields (ΦF) and lifetimes (τF), and other photophysical parameters of these N-PhPy derivatives and their polymers were measured in DMF, DMSO diluted solutions and/or solid state at room temperature. The electronic absorption spectra of N-PhPy derivatives and their polymers included one to several bands, located in the 270-395 nm region, according to the p-phenyl substituent electron-donating effect and conjugated heteroaromatic system length. The fluorescence excitation spectra were characterized by one broad main peak, with, in most cases, one (or more) poorly resolved shoulder (s), appearing in the 270-405 nm region, and their emission spectra were generally constituted of several bands located in the 330-480 nm region. No significant shift of the absorption, fluorescence excitation and emission spectra wavelengths was found upon going from the monomers to the corresponding polymers. ΦF values were high, varying between 0.11 and 0.63, according to the nature of substituents(s) and to the conjugated system extension. Fluorescence decays were mono-exponential for the monomers and poly-exponential for PyPhThThPhPy and for polymers. τF values were relatively short (0.35-5.17 ns), and markedly decreased with the electron-donor character of the phenyl group p-substituent and the conjugated system extension. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Electronic transport in tungsten and iron-doped tungsten below 1 K

    International Nuclear Information System (INIS)

    Uher, C.; Khoshnevisan, M.; Pratt, W.P. Jr.; Bass, J.

    1979-01-01

    The electric resistivity rho and the thermoelectric ratio G have been measured for zone-refined single crystals of both tungsten and iron-doped tungsten from 5 K down to 40 mK. The samples had residual resistance ratios RRR ranging from 1750 to 90,000. The observed behavior is conveniently divided into two classes, ''normal'' and ''anomalous.'' Completely normal behavior was displayed by only three W samples with high RRRs. The Fe-doped W and the remaining W samples contained one or more anomalies. Normal behavior is that which would be expected for W containing impurities with no internal degrees of freedom. In normal behavior rho decreased monotonically with decreasing temperature and was consistent with the equation rho=rho 0 +AT 2 below about 1.5K. In normal behavior, G was positive and constant below about 0.5 K, increased in magnitude as T rose to 4 or 5 K, and then began to decrease, becoming negative above about 7 K. The anomalous class displayed at least one of three anomalies: (1) a minimum in the electrical resistivity, with an approximately logarithmic variation with T at temperatures below the minimum; (2) a positive contribution to G which increased in magnitude with decreasing temperature approximately at T/sup -1/2/ from about 4 K down to at least 0.5 K; and (3) a negative contribution to G which set in at about 0.5 K, varied approximately as log T, and dominated G at the lowest temperatures

  5. X-ray absorption spectroscopy: EXAFS and XANES - A versatile tool to study the atomic and electronic structure of materials

    International Nuclear Information System (INIS)

    Alp, E.E.; Mini, S.M.; Ramanathan, M.

    1990-01-01

    X-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. The correct interpretation of the oscillatory structure in the x-ray absorption cross-section above the absorption edge has transformed XAS from a spectroscopic tool to a structural technique. EXAFS (Extended X-ray Absorption Fine Structure) yields information about the interatomic distances, near neighbor coordination numbers, and lattice dynamics. XANES (X-ray Absorption Near Edge Structure), on the other hand, gives information about the valence state, energy bandwidth and bond angles. Today, there are about 50 experimental stations in various synchrotrons around the world dedicated to collecting x-ray absorption data from the bulk and surfaces of solids and liquids. In this chapter, they will give the basic principles of XAS, explain the information content of essentially two different aspects of the absorption process leading to EXAFS and XANES, and discuss the source and sample limitations

  6. Cloud point extraction of iron(III) and vanadium(V) using 8-quinolinol derivatives and Triton X-100 and determination of 10(-7)moldm(-3) level iron(III) in riverine water reference by a graphite furnace atomic absorption spectroscopy.

    Science.gov (United States)

    Ohashi, Akira; Ito, Hiromi; Kanai, Chikako; Imura, Hisanori; Ohashi, Kousaburo

    2005-01-30

    The cloud point extraction behavior of iron(III) and vanadium(V) using 8-quinolinol derivatives (HA) such as 8-quinolinol (HQ), 2-methyl-8-quinolinol (HMQ), 5-butyloxymethyl-8-quinolinol (HO(4)Q), 5-hexyloxymethyl-8-quinolinol (HO(6)Q), and 2-methyl-5-octyloxymethyl-8-quinolinol (HMO(8)Q) and Triton X-100 solution was investigated. Iron(III) was extracted with HA and 4% (v/v) Triton X-100 in the pH range of 1.70-5.44. Above pH 4.0, more than 95% of iron(III) was extracted with HQ, HMQ, and HMO(8)Q. Vanadium(V) was also extracted with HA and 4% (v/v) Triton X-100 in the pH range of 2.07-5.00, and the extractability increased in the following order of HMQ HQ cloud point extraction was applied to the determination of iron(III) in the riverine water reference by a graphite furnace atomic absorption spectroscopy. When 1.25 x 10(-3)M HMQ and 1% (v/v) Triton X-100 were used, the found values showed a good agreement with the certified ones within the 2% of the R.S.D. Moreover, the effect of an alkyl group on the solubility of 5-alkyloxymethyl-8-quinolinol and 2-methyl-5-alkyloxymethyl-8-quinolinol in 4% (v/v) Triton X-100 at 25 degrees C was also investigated.

  7. Iron homeostasis during pregnancy.

    Science.gov (United States)

    Fisher, Allison L; Nemeth, Elizabeta

    2017-12-01

    During pregnancy, iron needs to increase substantially to support fetoplacental development and maternal adaptation to pregnancy. To meet these iron requirements, both dietary iron absorption and the mobilization of iron from stores increase, a mechanism that is in large part dependent on the iron-regulatory hormone hepcidin. In healthy human pregnancies, maternal hepcidin concentrations are suppressed in the second and third trimesters, thereby facilitating an increased supply of iron into the circulation. The mechanism of maternal hepcidin suppression in pregnancy is unknown, but hepcidin regulation by the known stimuli (i.e., iron, erythropoietic activity, and inflammation) appears to be preserved during pregnancy. Inappropriately increased maternal hepcidin during pregnancy can compromise the iron availability for placental transfer and impair the efficacy of iron supplementation. The role of fetal hepcidin in the regulation of placental iron transfer still remains to be characterized. This review summarizes the current understanding and addresses the gaps in knowledge about gestational changes in hematologic and iron variables and regulatory aspects of maternal, fetal, and placental iron homeostasis. © 2017 American Society for Nutrition.

  8. The effect of threading dislocations on optical absorption and electron scattering in strongly mismatched heteroepitaxial III-V compound semiconductors on silicon

    CERN Document Server

    Peiner, E; Wehmann, H H

    2002-01-01

    The effect of threading dislocations on the optical and electrical properties of InP and GaAs heteroepitaxial layers on (001) silicon was investigated. Charged deep states act as scattering centres for electrons, thus affecting the electron mobility at low temperatures. The electric field arising from charged dislocations causes enhanced optical absorption at wavelengths near the fundamental absorption edge. The mean charge of the threading dislocations in GaAs/Si was found to be considerably higher than that for InP/Si. A model is described relating this effect to a regular arrangement of alpha-type 60 deg. dislocations at extended twin defects which were observed in InP/Si but were absent in GaAs/Si.

  9. Optical Absorption Spectra and Electronic Properties of Symmetric and Asymmetric Squaraine Dyes for Use in DSSC Solar Cells: DFT and TD-DFT Studies

    Directory of Open Access Journals (Sweden)

    Reda M. El-Shishtawy

    2016-04-01

    Full Text Available The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1–SQD4 were investigated using density functional theory (DFT and time-dependent (TD-DFT density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time dependent density functionals Perdew, Burke and Ernzerhof (PBE, PBE1PBE (PBE0, and the exchange functional of Tao, Perdew, Staroverov, and Scuseria (TPSSh with 6-311++G** basis set were employed to examine optical absorption properties. In an extensive comparison between the optical data and DFT benchmark calculations, the BEP functional with 6-311++G** basis set was found to be the most appropriate in describing the electronic absorption spectra. The calculated energy values of lowest unoccupied molecular orbitals (LUMO were 3.41, 3.19, 3.38 and 3.23 eV for SQD1, SQD2, SQD3, and SQD4, respectively. These values lie above the LUMO energy (−4.26 eV of the conduction band of TiO2 nanoparticles indicating possible electron injection from the excited dyes to the conduction band of the TiO2 in dye-sensitized solar cells (DSSCs. Also, aromaticity computation for these dyes are in good agreement with the data obtained optically and geometrically with SQD4 as the highest aromatic structure. Based on the optimized molecular geometries, relative positions of the frontier orbitals, and the absorption maxima, we propose that these dyes are suitable components of photovoltaic DSSC devices.

  10. Electron delocalization in cyanide-bridged coordination polymer electrodes for Li-ion batteries studied by soft x-ray absorption spectroscopy

    NARCIS (Netherlands)

    Asakura, Daisuke; Okubo, Masashi; Mizuno, Yoshifumi; Kudo, Tetsuichi; Zhou, Haoshen; Amemiya, Kenta; de Groot, Frank M. F.; Chen, Jeng-Lung; Wang, Wei-Cheng; Glans, Per-Anders; Chang, Chinglin; Guo, Jinghua; Honma, Itaru

    2011-01-01

    The electronic structure change during the reversible Li-ion storage reaction in a bimetallic MnFe-Prussian blue analogue (Li(x)K(0.14)Mn(1.43)[Fe(CN)(6)] center dot 6H(2)O) was investigated by soft x-ray absorption spectroscopy. The Mn L(2,3)-edgespectra revealed the unchanged Mn(2+) high-spin

  11. Intracellular trafficking of superparamagnetic iron oxide nanoparticles conjugated with TAT peptide: 3-dimensional electron tomography analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nair, Baiju G.; Fukuda, Takahiro; Mizuki, Toru; Hanajiri, Tatsuro [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan); Maekawa, Toru, E-mail: maekawa@toyo.jp [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan)

    2012-05-18

    Highlights: Black-Right-Pointing-Pointer We study the intracellular localisation of TAT-SPIONs using 3-D electron tomography. Black-Right-Pointing-Pointer 3-D images of TAT-SPIONs in a cell are clearly shown. Black-Right-Pointing-Pointer Release of TAT-SPIONs from endocytic vesicles into the cytoplasm is clearly shown. -- Abstract: Internalisation of nanoparticles conjugated with cell penetrating peptides is a promising approach to various drug delivery applications. Cell penetrating peptides such as transactivating transcriptional activator (TAT) peptides derived from HIV-1 proteins are effective intracellular delivery vectors for a wide range of nanoparticles and pharmaceutical agents thanks to their amicable ability to enter cells and minimum cytotoxicity. Although different mechanisms of intracellular uptake and localisation have been proposed for TAT conjugated nanoparticles, it is necessary to visualise the particles on a 3-D plane in order to investigate the actual intracellular uptake and localisation. Here, we study the intracellular localisation and trafficking of TAT peptide conjugated superparamagnetic ion oxide nanoparticles (TAT-SPIONs) using 3-D electron tomography. 3-D tomograms clearly show the location of TAT-SPIONs in a cell and their slow release from the endocytic vesicles into the cytoplasm. The present methodology may well be utilised for further investigations of the behaviours of nanoparticles in cells and eventually for the development of nano drug delivery systems.

  12. Intracellular trafficking of superparamagnetic iron oxide nanoparticles conjugated with TAT peptide: 3-dimensional electron tomography analysis

    International Nuclear Information System (INIS)

    Nair, Baiju G.; Fukuda, Takahiro; Mizuki, Toru; Hanajiri, Tatsuro; Maekawa, Toru

    2012-01-01

    Highlights: ► We study the intracellular localisation of TAT-SPIONs using 3-D electron tomography. ► 3-D images of TAT-SPIONs in a cell are clearly shown. ► Release of TAT-SPIONs from endocytic vesicles into the cytoplasm is clearly shown. -- Abstract: Internalisation of nanoparticles conjugated with cell penetrating peptides is a promising approach to various drug delivery applications. Cell penetrating peptides such as transactivating transcriptional activator (TAT) peptides derived from HIV-1 proteins are effective intracellular delivery vectors for a wide range of nanoparticles and pharmaceutical agents thanks to their amicable ability to enter cells and minimum cytotoxicity. Although different mechanisms of intracellular uptake and localisation have been proposed for TAT conjugated nanoparticles, it is necessary to visualise the particles on a 3-D plane in order to investigate the actual intracellular uptake and localisation. Here, we study the intracellular localisation and trafficking of TAT peptide conjugated superparamagnetic ion oxide nanoparticles (TAT-SPIONs) using 3-D electron tomography. 3-D tomograms clearly show the location of TAT-SPIONs in a cell and their slow release from the endocytic vesicles into the cytoplasm. The present methodology may well be utilised for further investigations of the behaviours of nanoparticles in cells and eventually for the development of nano drug delivery systems.

  13. Acetate, lactate, propionate, and isobutyrate as electron donors for iron and sulfate reduction in Arctic marine sediments, Svalbard

    DEFF Research Database (Denmark)

    Finke, Niko; Vandieken, Verona; Jørgensen, Bo Barker

    2007-01-01

    The contribution of volatile fatty acids (VFA) as e--donors for anaerobic terminal oxidation of organic carbon through iron and sulfate reduction was studied in Arctic fjord sediment. Dissolved inorganic carbon, Fe2+, VFA concentrations, and sulfate reduction were monitored in slurries from...... by alternative e--donors. The accumulation of VFA in the selenate-inhibited 0-2 cm slurry did not enhance iron reduction, indicating that iron reducers were not limited by VFA availability....

  14. Phase mapping of iron-based rapidly quenched alloys using precession electron diffraction

    International Nuclear Information System (INIS)

    Svec, P.; Janotova, I.; Hosko, J.; Matko, I.; Janickovic, D.; Svec, P. Sr.; Kepaptsoglou, D. M.

    2013-01-01

    The present contribution is focused on application of PED and phase/orientation mapping of nanocrystals of bcc-Fe formed during the first crystallization stage of amorphous Fe-Co-Si-B ribbon. Using precession electron diffraction and phase/orientation mapping the formation of primary crystalline phase, bcc-Fe, from amorphous Fe-Co-Si-B has been analyzed. Important information about mutual orientation of the phase in individual submicron grains as well as against the sample surface has been obtained. This information contributes to the understanding of micromechanisms controlling crystallization from amorphous rapidly quenched structure and of the structure of the original amorphous state. The presented technique due to its high spatial resolution, speed and information content provided complements well classical techniques, especially in nanocrystalline materials. (authors)

  15. Localisation assisted by the lattice relaxation and the optical absorption of extra-framework electrons in 12CaO.Al2O3

    International Nuclear Information System (INIS)

    Sushko, Peter V.; Shluger, Alexander L.; Hayashi, Katsuro; Hirano, Masahiro; Hosono, Hideo

    2005-01-01

    The crystalline framework of a complex oxide 12CaO.7Al 2 O 3 (C12A7) is built from positively charged sub-nanometer cages able to trap electrons. An embedded cluster approach is used to study the electronic structure and optical properties of electron-containing C12A7 for different concentration of extra-framework electrons. Our results suggest that the conduction band of the C12A7 consists of a relatively narrow band of empty cage states (cage conduction band) with one-electron energies between 5.5 and 6.1 eV above the top of the valence band (VB), and a framework conduction band at about 6.7 - 7.0 eV above the to of the VB. The gap between the cage conduction band and the framework conduction band is estimated to be about 1 - 1.5 eV. The energies of the lowest optical transitions from the top of the valence band to the cage conduction band are predicted to be at 5.2 - 5.5 eV. The extra-electrons occupy cage states, which split from the cage conduction band to about 4 eV above the top of the VB. The extra-framework electrons introduce two absorption bands with the experimental peaks at 0.4 eV and 2.8 eV. These bands are assigned to the inter-cage charge transfer and the intra-cage s-p transitions respectively. The changes in the optical absorption spectra as a function of the extra-electrons concentration are also discussed

  16. Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

    OpenAIRE

    Edelman , Irina; Ivanova , Oxana; Ivantsov , Ruslan; Velikanov , D.; Zabluda , V.; Zubavichus , Y.; Veligzhanin , A.; Zaikovskiy , V.; Stepanov , S.; Artemenko , Alla; Curély , Jacques; Kliava , Janis

    2012-01-01

    International audience; A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge struct...

  17. Formation of biomineral iron oxides compounds in a Fe hyperaccumulator plant: Imperata cylindrica (L.) P. Beauv.

    Science.gov (United States)

    Fuente, V; Rufo, L; Juárez, B H; Menéndez, N; García-Hernández, M; Salas-Colera, E; Espinosa, A

    2016-01-01

    We report a detailed work of composition and location of naturally formed iron biominerals in plant cells tissues grown in iron rich environments as Imperata cylindrica. This perennial grass grows on the Tinto River banks (Iberian Pyritic Belt) in an extreme acidic ecosystem (pH∼2.3) with high concentration of dissolved iron, sulphate and heavy metals. Iron biominerals were found at the cellular level in tissues of root, stem and leaf both in collected and laboratory-cultivated plants. Iron accumulated in this plant as a mix of iron compounds (mainly as jarosite, ferrihydrite, hematite and spinel phases) was characterized by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), Mössbauer spectroscopy (MS), magnetometry (SQUID), electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX; TEM-EDX; HRSTEM). A low fraction of phosphorous was detected in this iron hyperaccumulator plant. Root and rhizomes tissues present a high proportion of ferromagnetic iron oxide compounds. Iron oxides-rich zones are localized in electron dense intra and inter-cellular aggregates that appear as dark deposits covering the inner membrane and organelles of the cell. This study aims to contribute to a better understanding of the mechanisms of accumulation, transport, distribution of iron in Imperata cylindrica. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Studies on internal friction in electron-irradiated iron crystals after plastic deformation

    International Nuclear Information System (INIS)

    Wolf, J.

    1986-01-01

    For the analysis of atomic point defects in high-purity the generation of atomic point defects was, above all, carried out by electron radiation, but in addition, also by plastic deformation. The exposure to radiation was realized at different temperatures in the Dynamitron of the University of Stuttgart (80 K, 160 K) and also in the low-temperature radiation facility of the nuclear research plant (KfA) Juelich (50 K). The radiation doses ranged between 2.7.10 21 e - /m 2 and 1.0.10 23 e - /m 2 . In situ plastic deformation was achieved at about 80 K (torsion, 4%). Internal friction which was determined in an inverse torsion pendulum in the temperature range of 80 K - 700 K and at frequencies of about 1 Hz served as defect indicator. In this study simulation programs were developed which were to give information prior to the realization of measurements on the temperatures and the intensity of the damping peaks to be expected. The internal friction peaks measured in the framework of this study could be assigned to the recovery stages I-IV. The measured values were discussed for three temperature ranges with main emphasis on the investigation of the recovering, radiation-induced or deformation-induced, atomic point defect in the temperature range of the recovery stage III (200 K - 270 K). (orig./MM) [de

  19. Electron spin resonance studies of iron-group impurities in beryllium fluoride glasses

    Energy Technology Data Exchange (ETDEWEB)

    Griscom, D L; Stapelbroek, M [Naval Research Lab., Washington, DC (USA); Weber, M J [California Univ., Livermore (USA). Lawrence Livermore National Lab.

    1980-11-01

    Electron spin resonance investigations have been carried out on unirradiated BeF/sub 2/ glasses. Two relatively intense resonances were observed in a water-free distilled glass known to contain 49 ppM Ni, 13 ppM Mn, and < 20 ppM Fe. One of these was the paramagnetic resonance spectrum of Mn/sup 2 +/. Analysis of the observed /sup 19/F superhyperfine structure demonstrated this manganese to occupy distorted octahedral sites in the glass network. The second resonance was shown by temperature and frequency dependence studies, coupled with computer line shape analysis, to be a ferromagnetic resonance signal due to precipitated ferrite phases. The data suggest that these ferrites are somewhat heterogeneous and most likely comprize magnetite-like phases similar to NiFe/sub 2/O/sub 4/. An optical extinction curve rising into the ultraviolet with an approximate lambda/sup -4/ dependence is tentatively ascribed to light scattering by ferrite particles approximately 1000 Angstroems in diameter.

  20. Amorphization-induced strong localization of electronic states in CsPbBr3 and CsPbCl3 studied by optical absorption measurements

    Science.gov (United States)

    Kondo, S.; Sakai, T.; Tanaka, H.; Saito, T.

    1998-11-01

    Optical absorption spectra of amorphous CsPbX3 films (X=Br,Cl) are characterized by two Gaussian bands near the fundamental edge, with the optical energy gap largely blueshifted and the absorption intensity strongly reduced as compared with the crystalline films. The peak energies of the bands are close to those of the A and C bands of Pb-doped alkali halides. The spectral features are discussed in terms of a molecular orbital theory based on a quasicomplex Pb2+(X-)6 model similar to the complex model for the doped alkali halides. It is shown that not only Pb2+ 6s and 6p extended states near the band edges but also X- p states contributing to upper valence bands are localized by amorphization. The transitions from the localized Pb2+ 6s to 6p states produce the spin-orbit allowed 3P1 and dipole allowed 1P1 states responsible for the two Gaussians. The localized X- p states lie deeper in energy than the localized Pb2+ 6s state and only contribute to higher-energy absorption above the Gaussian bands, giving the reason for the reduced absorption near the fundamental edge. The blueshift of the optical energy gap is attributed to the disappearance of k dispersions for these one-electron states.

  1. Ingestion of polydextrose increase the iron absorption in rats submitted to partial gastrectomy A ingestão de polidextrose aumenta a absorção de ferro em ratos submetidos à gastrectomia parcial

    Directory of Open Access Journals (Sweden)

    Elisvânia Freitas dos Santos

    2010-12-01

    Full Text Available PURPOSE: To investigate whether polydextrose stimulates iron absorption in rats submitted to partial gastrectomy and sham operated. METHODS: The rats were submitted to partial gastrectomy (Billroth II or laparotomy (sham-operated control, in groups of 20 and 20 each respectively. The animals were fed with a control diet (AIN-93M without polydextrose or a diet containing polydextrose (50g/Kg of diet for eight weeks. They were divided into four subgroups: sham-operated and Billroth II gastrectomy and with or without polydextrose. Two animals died during the experiment. All rats submitted to gastrectomy received B-12 vitamin (intramuscular each two weeks. The hematocrit and hemoglobin concentration were measured at the start and on day 30 and 56 after the beginning of the experimental period. At the end of the study, the blood was collected for determination of serum iron concentration. RESULTS: The diet with polydextrose reduced the excretion of iron. Apparent iron absorption was higher in the polydextrose fed groups than in the control group. The haematocrit and haemoglobin concentration were lower after Billroth II gastrectomy rats fed the control diet as compared to the polydextrose diet groups. CONCLUSION: Polydextrose increase iron absorption and prevents postgastrectomy anemia.OBJETIVO: Investigar se a polidextrose estimula a absorção de ferro em ratos submetidos à gastrectomia parcial e sham operados. MÉTODOS: Os ratos foram submetidos à gastrectomia parcial (Billroth II e à laparotomia (controle sham-operados em grupos de 20 e 20 cada, respectivamente. Os animais foram alimentados com uma dieta controle (AIN-93M, sem polidextrose ou uma dieta contendo polidextrose (50g/kg de dieta durante oito semanas. Foram divididos em quatro grupos: sham-operados e com gastrectomia BII e com ou sem polidextrose. Dois animais morreram durante o experimento. Todos os ratos com gastrectomia receberam vitamina B-12 (intramuscular a cada duas semanas

  2. First-principles calculation of optical absorption spectra in conjugated polymers: Role of electron-hole interaction

    International Nuclear Information System (INIS)

    Rohlfing, Michael; Tiago, M.L.; Louie, Steven G.

    2000-01-01

    Experimental and theoretical studies have shown that excitonic effects play an important role in the optical properties of conjugated polymers. The optical absorption spectrum of trans-polyacetylene, for example, can be understood as completely dominated by the formation of exciton bound states. We review a recently developed first-principles method for computing the excitonic effects and optical spectrum, with no adjustable parameters. This theory is used to study the absorption spectrum of two conjugated polymers: trans-polyacetylene and poly-phenylene-vinylene(PPV)

  3. Electronic absorption spectroscopy of matrix-isolated polycyclic aromatic hydrocarbon cations. I - The naphthalene cation (C10H8/+/)

    Science.gov (United States)

    Salama, F.; Allamandola, L. J.

    1991-01-01

    The ultraviolet, visible, and near-infrared absorption spectra of naphthalene (C10H8) and its radical ion (C10H8/+/), formed by vacuum ultraviolet irradiation, were measured in argon and neon matrices at 4.2 K. The associated vibronic band systems and their spectroscopic assignments are discussed together with the physical and chemical conditions governing ion production in the solid phase. The absorption coefficients were calculated for the ion and found lower than previous values, presumably due to the low polarizability of the neon matrix.

  4. First-principles calculation of optical absorption spectra in conjugated polymers: Role of electron-hole interaction

    Energy Technology Data Exchange (ETDEWEB)

    Rohlfing, Michael; Tiago, M.L.; Louie, Steven G.

    2000-03-20

    Experimental and theoretical studies have shown that excitonic effects play an important role in the optical properties of conjugated polymers. The optical absorption spectrum of trans-polyacetylene, for example, can be understood as completely dominated by the formation of exciton bound states. We review a recently developed first-principles method for computing the excitonic effects and optical spectrum, with no adjustable parameters. This theory is used to study the absorption spectrum of two conjugated polymers: trans-polyacetylene and poly-phenylene-vinylene(PPV).

  5. Flame atomic absorption spectrometric determination of zinc, nickel, iron and lead in different matrixes after solid phase extraction on sodium dodecyl sulfate (SDS)-coated alumina as their bis (2-hydroxyacetophenone)-1, 3-propanediimine chelates

    International Nuclear Information System (INIS)

    Ghaedi, M.; Tavallali, H.; Shokrollahi, A.; Zahedi, M.; Montazerozohori, M.; Soylak, M.

    2009-01-01

    A sensitive and simple solid phase extraction method for the simultaneous determination of trace and toxic metals in food samples has been reported. The method is based on the adsorption of zinc, nickel, iron and lead on sodium dodecyl sulfate (SDS)-coated alumina, which is also chelated with bis (2-hydroxyacetophenone)-1, 3-propanediimine (BHAPN). The retained analyte ions on modified solid phase were eluted using 8 mL of 4 mol L -1 HNO 3 . The analyte determinations were carried out by flame atomic absorption spectrometry. The influences of some metal ions and anions on the recoveries of understudy analyte ions were investigated. The proposed method has been successfully applied for the evaluation of these trace and toxic metals in some traditional food samples from Iran.

  6. Investigation of electronic states of infinite-layer SrFeO2 epitaxial thin films by X-ray photoemission and absorption spectroscopies

    International Nuclear Information System (INIS)

    Chikamatsu, Akira; Matsuyama, Toshiya; Hirose, Yasushi; Kumigashira, Hiroshi; Oshima, Masaharu; Hasegawa, Tetsuya

    2012-01-01

    Highlights: ► Electronic states of infinite-layer SrFeO 2 films have been experimentally observed. ► Fe 3d states have higher densities of states in the valence-band region. ► Three peaks derived from Fe 3d states were observed in the conduction-band region. ► Indirect bandgap value was determined to be 1.3 eV. - Abstract: We investigated the electronic states of a single-crystal SrFeO 2 epitaxial thin film in the valence-band and conduction-band regions using synchrotron-radiation X-ray photoemission and absorption spectroscopies. Fe 2p–3d resonant photoemission measurements revealed that the Fe 3d states have higher densities of states at binding energies of 3–5 eV and 5–8.5 eV in the valence-band region. The O K-edge X-ray absorption spectrum exhibited three peaks in the Fe 3d-derived conduction band hybridized with O 2p states; these can be assigned to Fe 3d xy , 3d xz + 3d yz , and 3d x 2 –y 2 . In addition, the indirect bandgap value of the SrFeO 2 film was determined to be 1.3 eV by transmission and absorption spectroscopies.

  7. On the spatio-temporal and energy-dependent response of riometer absorption to electron precipitation: drift-time and conjunction analyses in realistic electric and magnetic fields

    Science.gov (United States)

    Kellerman, Adam; Shprits, Yuri; Makarevich, Roman; Donovan, Eric; Zhu, Hui

    2017-04-01

    Riometers are low-cost passive radiowave instruments located in both northern and southern hemispheres that capable of operating during quiet and disturbed conditions. Many instruments have been operating continuously for multiple solar cycles, making them a useful tool for long-term statistical studies and for real-time analysis and forecasting of space weather. Here we present recent and new analyses of the relationship between the riometer-measured cosmic noise absorption and electron precipitation into the D-region and lower E-region ionosphere. We utilize two techniques: a drift-time analysis in realistic electric and magnetic field models, where a particle is traced from one location to another, and the energy determined by the time delay between similar observations; and a conjunction analysis, where we directly compare precipitated fluxes from THEMIS and Van Allen Probes with the riometer absorption. In both cases we present a statistical analysis of the response of riometer absorption to electron precipitation as a function of MLAT, MLT, and geomagnetic conditions.

  8. Cloud point extraction of copper, lead, cadmium, and iron using 2,6-diamino-4-phenyl-1,3,5-triazine and nonionic surfactant, and their flame atomic absorption spectrometric determination in water and canned food samples.

    Science.gov (United States)

    Citak, Demirhan; Tuzen, Mustafa

    2012-01-01

    A cloud point extraction procedure was optimized for the separation and preconcentration of lead(II), cadmium(II), copper(II), and iron(III) ions in various water and canned food samples. The metal ions formed complexes with 2,6-diamino-4-phenyl-1,3,5-triazine that were extracted by surfactant-rich phases in the nonionic surfactant Triton X-114. The surfactant-rich phase was diluted with 1 M HNO3 in methanol prior to its analysis by flame atomic absorption spectrometry. The parameters affecting the extraction efficiency of the proposed method, such as sample pH, complexing agent concentration, surfactant concentration, temperature, and incubation time, were optimized. LOD values based on three times the SD of the blank (3Sb) were 0.38, 0.48, 1.33, and 1.85 microg/L for cadmium(II), copper(II), lead(II), and iron(III) ions, respectively. The precision (RSD) of the method was in the 1.86-3.06% range (n=7). Validation of the procedure was carried out by analysis of National Institute of Standards and Technology Standard Reference Material (NIST-SRM) 1568a Rice Flour and GBW 07605 Tea. The method was applied to water and canned food samples for determination of metal ions.

  9. Electronic structure of Pt-Co cathode catalysts in membrane electrolyte assembly observed by X-ray absorption fine structure spectroscopy with different probing depth

    International Nuclear Information System (INIS)

    Kobayashi, M.; Hidai, S.; Niwa, H.; Harada, Y.; Oshima, M.; Ofuchi, H.; Nakamori, Y.; Aoki, T.

    2010-01-01

    Electronic structures of Pt-Co cathode and Pt-Ru anode catalysts in membrane electrolyte assemblies (MEAs) for polymer electrolyte fuel cell have been investigated using X-ray absorption near edge structure (XANES) spectroscopy, and the changes of electronic structures accompanied with degradation have been observed by comparison between spectra obtained by fluorescence-yield (FY) and conversion-electron-yield (CEY) methods, probing depths of which are several hundreds μm and ∼100 nm, respectively. The Co K XANES spectra of the as-fabricated MEA show that the Co atoms in the cathode are metallic and oxidized Co ions exist at the interface between the cathode and electrolyte. The spectra of the long-time operated MEA suggest that the oxidation of Co makes progress with degradation of the cathode catalysts. In contrast to the Co K XANES spectra, the line shape of the Ru K XANES spectra is unchanged even after the long-time operation.