WorldWideScience

Sample records for iron manganese molybdenum

  1. Adhesive wear of iron chromium nickel silicon manganese molybdenum niobium alloys with duplex structure

    International Nuclear Information System (INIS)

    Lugscheider, E.; Deppe, E.; Ambroziak, A.; Melzer, A.

    1991-01-01

    Iron nickel chromium manganese silicon and iron chromium nickel manganese silicon molybdenum niobium alloys have a so-called duplex structure in a wide concentration range. This causes an excellent resistance to wear superior in the case of adhesive stress with optimized concentrations of manganese, silicon, molybdenum and niobium. The materials can be used for welded armouring structures wherever cobalt and boron-containing alloy systems are not permissible, e.g. in nuclear science. Within the framework of pre-investigations for manufacturing of filling wire electrodes, cast test pieces were set up with duplex structure, and their wear behavior was examined. (orig.) [de

  2. Influence of iron supply on toxic effects of manganese, molybdenum and vanadium on soybean, peas, and flax

    Energy Technology Data Exchange (ETDEWEB)

    Warington, K

    1954-01-01

    The investigations were carried out in nutrient solution with iron as ferric citrate and nitrogen in the form of nitrate. The addition of 2.5 ppm vanadium to plants in which iron chlorosis was already established, either by a lack of iron or by excess manganese, failed to counteract the condition, and caused toxic symptoms. The reduction of the standard iron supply to 1/2 or 1/3 accentuated the toxicity of 2.5 or 5 ppm V to soybean and flax, but a similar reduction in phosphorus had no influence. The toxicity to peas, however, was increased when the phosphorus was reduced to 1/10, provided the iron level was high (20 ppm Fe). Raising the iron supply to 20 or 30 ppm counteracted the toxicity of manganese (10 ppm), molybdenum (40 ppm) and vanadium (2.5 ppm), but the result was less marked when these three elements were combined. Iron supplied in successive, small doses proved less efficient in overcoming molybdenum or vanadium, but not manganese excess, than the same amount of iron supplied in fewer and larger quantities. Varying the iron supply had little effect when the concentration of the three elements was low. When increased iron supply had reduced the chlorosis caused by high manganese or vanadium, it also reduced the manganese and vanadium contents of the shoot (ppm/dm), but the molybdenum content was only lowered by high iron when given in non-toxic concentrations (0.1 ppm Mo) combined with excess manganese. Yield data for soybean and flax indicated an interaction between manganese with both molybdenum and vanadium if the iron supply was low, but none between molybdenum and vanadium. The effect of all three metals was additive in respect to iron.

  3. Monitoring of occupational exposure in manufacturing of stainless steel constructions. Part I: Chromium, iron, manganese, molybdenum, nickel and vanadium in the workplace air of stainless steel welders.

    Science.gov (United States)

    Kucera, J; Bencko, V; Pápayová, A; Saligová, D; Tejral, J; Borská, L

    2001-11-01

    Exposure to workplace airborne pollutants was examined in a group of 20 workers dealing mainly with welding, polishing, drilling and assembling of stainless steel constructions. Airborne particulate matter (APM) collected using both personal and stationary samplers was analyzed by instrumental neutron activation analysis (INAA). Quality assurance procedures of both sampling and analytical stages are described. Of the elements determined, results are presented for chromium, iron, manganese, molybdenum, nickel and vanadium. The median values of element concentrations exceeded the maximum admissible limits for workplace pollutants only for chromium, while for nickel the limit was exceeded in several individual cases. Sampling of hair, nails, blood, urine and saliva to be used for biological monitoring of the exposed and control groups is also described.

  4. Thermodynamic Properties of Manganese and Molybdenum

    International Nuclear Information System (INIS)

    Desai, P.D.

    1987-01-01

    This work reviews and discusses the data on the various thermodynamic properties of manganese and molybdenum available through March 1985. These include heat capacity, enthalpy, enthalpy of transitions and melting, vapor pressure, and enthalpy of vaporization. The existing data have been critically evaluated and analyzed. The recommended values for the heat capacity, enthalpy, entropy, and Gibbs energy function from 0.5 to 2400 K for manganese and from 0.4 to 5000 K for molybdenum have been generated, as have heat capacity values for supercooled β-Mn and for γ-Mn below 298.15 K. The recommended values for vapor pressure cover the temperature range from 298.15 to 2400 K for manganese and from 298.15 to 5000 K for molybdenum. These values are referred to temperatures based on IPTS-1968. The uncertainties in the recommended values of the heat capacity range from +-3% to +-5% for manganese and from +-1.5% to +-3% for molybdenum

  5. Monitoring of occupational exposure in manufacturing of stainless steel constructions. Part I: Chromium, iron, manganese, molybdenum, nickel and vanadium in the workplace air of stainless steel welders

    International Nuclear Information System (INIS)

    Kucera, J.; Hnatowicz, V.; Bencko, V.; Papayova, A.; Saligova, D.; Tejral, J.; Borska, L.

    2000-01-01

    Exposure to workplace airborne pollutants was examined in a group of 20 workers dealing mainly with welding, polishing, drilling and assembling of stainless steel constructions. Monitoring of airborne particulate matter (ARM) was performed using both personal and stationary samplers. For the personal full-shift monitoring, a SKC 224 PCRX-4 constant flow rate pump was used which was connected to a sampling head with mixed cellulose matched-weight filters having a diameter of 32 mm and a 0.8 μm pore size. The constant flow rate amounted to 2 L min -1 . For the stationary sampling, the ''Gent'' stacked filter unit PM10 sampler was used, operating at a flow rate of 16 L min -1 . It collects particles having an equivalent aerodynamic diameter (EAD) of less than 10,um in the separate ''coarse'' (2-10 μm EAD) and ''fine'' (< 2 μm EAD) size fractions on two sequential polycarbonate (Costar, Nuclepore) filters with a 47 mm diameter. The filters of both types were analyzed by instrumental neutron activation analysis (INAA). Of the elements determined, results for chromium, iron, manganese, molybdenum, nickel and vanadium are presented. Procedures for quality assurance of both sampling and analytical stages are described. Sampling of biological material for elemental analysis (hair, nails, urine and blood and/or serum) of exposed and control persons in contamination-free conditions was also performed. In addition, saliva samples were collected for studying immunological and genotoxicity aspects of occupational exposure. (author)

  6. Effect of molybdenum on the severity of toxicity symptoms in flax induced by an excess of either manganese, zinc, copper, nickel or cobalt in the nutrient solution

    Energy Technology Data Exchange (ETDEWEB)

    Millikan, C R

    1947-01-01

    The addition of molybdenum to solutions containing an excess of either manganese, zinc, copper, nickel or cobalt respectively, resulted in decreases in the severity of iron deficiency symptoms which normally occurred when flax was grown in solutions containing the same concentrations of any of these elements, but without molybdenum. The efficacy of molybdenum in this regard increased with increasing concentration up to 25 parts per million. However, concentrations of 0.5 to 2 parts per million of molybdenum had little effect on the severity of iron deficiency symptoms at the concentrations of heavy metals used. Molybdenum 5, 10 or 25 parts per million also retarded the date of appearance and reduced the severity of lower leaf necrosis which is another characteristic symptom of the presence of excess manganese (25 to 100 parts per million) in the nutrient solution. It is concluded that an essential function of molybdenum is intimately associated with the regulation of the deleterious effect of manganese, zinc, copper, nickel or cobalt on the physiological availability of iron to the plant. 46 references, 3 figures.

  7. Iron and manganese deposits in Uruguay

    International Nuclear Information System (INIS)

    Alvarado, B.

    1959-01-01

    This report is the results of the study carried out for the United Nations expert which the main object was: the study of the information available about iron and manganese formation in Uruguay, as well as the main researching deposit to determinate economical possibilities in the exportation.

  8. Effect of molybdenum and iron supply on molybdenum (99Mo) and iron (59Fe) uptake and activity of certain enzymes in tomato plants grown in sand culture

    International Nuclear Information System (INIS)

    Chatterjee, C.; Agarwala, S.C.

    1979-01-01

    Tomato (Lycopersicon esculentum Mill. var. Marglobe) plants were raised under controlled sand culture to study the interaction of molybdenum and iron supply on the uptake of molybdenum and iron and activity of certain enzymes affected by iron and/or molybdenum supply. Iron deficiency caused a decrease in the molybdenum uptake and accentuated the effect of molybdenum deficiency in reducing the uptake and more so the translocation of molybdenum from roots to shoots, thus inducing more severe molybdenum deficiency. The deficiency of iron and molybdenum decreased the activity of catalase, succinate dehydrogenase and nitrate reductase, the most marked decrease being found in plants supplied with both iron and molybdenum at low levels. Changes in the activities of nitrate reductase and catalase can be attributed to the interaction of iron and molybdenum supply in their absorption and translocation. (auth.)

  9. Iron and manganese removal from drinking water

    OpenAIRE

    Pascu, Daniela-Elena; Neagu (Pascu), Mihaela; Alina Traistaru, Gina; Nechifor, Aurelia Cristina; Raluca Miron, Alexandra

    2016-01-01

    The purpose of the present study is to find a suitable method for removal of iron and manganese from ground water, considering both local economical and environmental aspects. Ground water is a highly important source of drinking water in Romania. Ground water is naturally pure from bacteria at a 25 m depth or more. However, solved metals may occur and if the levels are too high, the water is not drinkable. Different processes, such as electrochemical and combined electrochemical-adsorption m...

  10. Adsorptive removal of manganese, arsenic and iron from groundwater

    NARCIS (Netherlands)

    Buamah, R.

    2009-01-01

    Arsenic, manganese and iron in drinking water at concentrations exceeding recommended guideline values pose health risks and aesthetic defects. Batch and pilot experiments on manganese adsorption equilibrium and kinetics using iron-oxide coated sand (IOCS), Aquamandix and other media have been

  11. Analysis of molybdenum, chromium, vanadium and iron by polarographic techniques

    International Nuclear Information System (INIS)

    Al-Zand, T.K.

    1986-01-01

    The application of direct current Tast polarograph, differential pulse polarography and phase-selective alternative current Tast polarography to the problem of determining molybdenum, chromium, vanadium and iron in various supporting electrolytes is reported. The effect of the supporting electrolyte on the wave/peak potential and sensitivity of the metal ion have been examined. The polarographic methods were applied for simultaneous determination of chromium (3)/chromium (6), vanadium (4), vanadium (5) and iron (2)/iron (3) in different supporting electrolytes

  12. Ferromagnetic properties of manganese doped iron silicide

    Science.gov (United States)

    Ruiz-Reyes, Angel; Fonseca, Luis F.; Sabirianov, Renat

    We report the synthesis of high quality Iron silicide (FeSi) nanowires via Chemical Vapor Deposition (CVD). The materials exhibits excellent magnetic response at room temperature, especially when doped with manganese showing values of 2.0 X 10-04 emu for the FexMnySi nanowires. SEM and TEM characterization indicates that the synthesized nanowires have a diameter of approximately 80nm. MFM measurements present a clear description of the magnetic domains when the nanowires are doped with manganese. Electron Diffraction and XRD measurements confirms that the nanowires are single crystal forming a simple cubic structure with space group P213. First-principle calculations were performed on (111) FeSi surface using the Vienna ab initio simulation package (VASP). The exchange correlations were treated under the Ceperley-Alder (CA) local density approximation (LDA). The Brillouin Zone was sampled with 8x8x1 k-point grid. A total magnetic moment of about 10 μB was obtained for three different surface configuration in which the Iron atom nearest to the surface present the higher magnetization. To study the effect of Mn doping, Fe atom was replaced for a Mn. Stronger magnetization is presented when the Mn atom is close to the surface. The exchange coupling constant have been evaluated calculating the energy difference between the ferromagnetic and anti-ferromagnetic configurations.

  13. Iron and manganese removal from drinking water

    Directory of Open Access Journals (Sweden)

    Daniela-Elena Pascu

    2016-04-01

    Full Text Available The purpose of the present study is to find a suitable method for removal of iron and manganese from ground water, considering bothlocal economical and environmental aspects. Ground water is a highly important source of drinking water in Romania. Ground water is naturally pure from bacteria at a 25 m depth or more. However, solved metals may occur and if the levels are too high, the water is not drinkable. Different processes, such as electrochemical and combined electrochemical-adsorption methods have been applied to determine metals content in accordance to reports of National Water Agency from Romania (ANAR. Every water source contains dissolved or particulate compounds. The concentrations of these compounds can affect health, productivity, compliance requirements, or serviceability and cannot be economically removed by conventional filtration means. In this study, we made a comparison between the electrochemical and adsorption methods (using membranes. Both methods have been used to evaluate the efficiency of iron and manganese removal at various times and temperatures. We used two membrane types: composite and cellulose, respectively. Different approaches, including lowering the initial current density and increasing the initial pH were applied. Reaction kinetics was achieved using mathematical models: Jura and Temkin.

  14. Metabolism of manganese, iron, copper, and selenium in calves

    International Nuclear Information System (INIS)

    Ho, S.Y.

    1981-01-01

    Sixteen male Holstein calves were used to study manganese and iron metabolism. The calves were fed one of the following diets for 18 days: control, control + iron, control + manganese, and control + iron and manganese. All calves were dosed orally with manganese-54. Tissue concentrations of manganese, iron and manganese-54 were determined. Small intestinal iron was lower in calves fed the high manganese diet than in controls. Tissue manganese-54 was lower in calves fed a high manganese diet. Fecal manganese content increased in calves fed both high manganese and high manganese-high iron diets. Serum total iron was not affected by the dietary treatments. To study the effects of high dietary levels of copper and selenium on the intracellular distributions of these two elements in liver and kidney cytosol, calves were fed one of four diets for 15 days. These were 0 and 100 ppM supplemental copper and 0 and 1 ppM added selenium. The control diet containing 0.1 ppM of selenium and 15 ppM of copper. All calves were orally dosed 48 hrs prior to sacrifice with selenium-75. A high copper diet increased copper concentrations in all intracellular liver fractions and most kidney fractions. Only the effects in the liver were significant. Less copper was found in the mitochondria fractions in liver and kidney of calves fed a high selenium diet. Three major copper-binding protein peaks were separated from the soluble fractions of calf liver and kidney. Peak 1 appeared to be the major copper-binding protein in liver and kidney cytosol of copper-loaded animals. Added selenium alone or in combination with copper accentuated the copper accumulation in this peak. Most of selenium-75 was recovered in the same peak as the copper. The results of this experiment indicated that the large molecular proteins in liver and kidney cytosol of calves play an important role in copper and selenium-75 metabolism

  15. Removal of Iron and Manganese in Groundwater using Natural Biosorbent

    Science.gov (United States)

    Baharudin, F.; Tadza, M. Y. Mohd; Imran, S. N. Mohd; Jani, J.

    2018-04-01

    This study was conducted to measure and compare the concentration of iron, manganese and hardness of the river and groundwater and to determine the effectiveness of iron and manganese removal by using natural biosorbent which is banana peels. The samples of river and groundwater were collected at riverbank filtration site at Jenderam Hilir, Dengkil. Based on the water quality investigation, the concentration of iron and manganese in the samples of groundwater have exceeded the drinking water quality standard which are 0.3 mg/L for iron and 0.1 mg/L for manganese. The removal process of the iron and manganese in the groundwater was done by using 2, 4 and 8 grams of banana peels activated carbon. It is found that with higher amount of activated banana peels, the removal of iron and manganese is more effective. The ranges of percentage of iron and manganese removal are between 82.25% to 90.84% and 98.79% to 99.43% respectively. From the result, banana peels activated carbon can be concluded as a one of the most effective low-cost adsorbent for groundwater treatment.

  16. Biological removal of iron and manganese in rapid sand filters - Process understanding of iron and manganese removal

    DEFF Research Database (Denmark)

    Lin, Katie

    to precipitation and corrosion. Manganese and iron can either be removed physico-chemically or biologically or combined. The physico-chemical oxidation and precipitation of manganese can theoretically be achieved by aeration, but this process is slow unless pH is raised far above neutral, making the removal...... of manganese by simple aeration and precipitation under normal drinking water treatment conditions insignificant. Manganese may also be oxidized autocatalytically. Iron is usually easier to remove. First, iron is rapidly chemically oxidized by oxygen at neutral pH followed by precipitation and filtration......-filter, where iron is removed. Step 2: Filtration in an after-filter where e.g. ammonium and manganese is removed. The treatment relies on microbial processes and may present an alternative, greener and more sustainable approach for drinking water production spending less chemicals and energy than chemical (e...

  17. Bioconcentration of manganese and iron in Panaeoloideae Sing

    NARCIS (Netherlands)

    Stijve, T.; Blake, C.

    1994-01-01

    According to literature, the manganese content of most basidiomycetes fluctuates between 10 and 60 mg/kg, whereas the iron levels range from 100-500 mg/kg (both expressed on dry weight). The present authors report that bioconcentration of manganese is a distinguishing feature of the Panaeoloideae,

  18. Arsenic, chromium, copper, iron, manganese, lead, selenium and ...

    African Journals Online (AJOL)

    Arsenic, chromium, copper, iron, manganese, lead, selenium and zinc in the tissues of the largemouth yellowfish, Labeobarbus kimberleyensis (Gilchrist and Thompson, 1913), from the Vaal Dam, South Africa, and associated consumption risks.

  19. Iron and manganese oxide mineralization in the Pacific

    Science.gov (United States)

    Hein, J. R.; Koschinsky, A.; Halbach, P.; Manheim, F. T.; Bau, M.; Jung-Keuk, Kang; Lubick, N.

    1997-01-01

    Iron, manganese, and iron-manganese deposits occur in nearly all geomorphologic and tectonic environments in the ocean basins and form by one or more of four processes: (1) hydrogenetic precipitation from cold ambient seawater, (2) precipitation from hydrothermal fluids, (3) precipitation from sediment pore waters that have been modified from bottom water compositions by diagenetic reactions in the sediment column and (4) replacement of rocks and sediment. These processes are discussed.

  20. Iron-responsive olfactory uptake of manganese improves motor function deficits associated with iron deficiency.

    Directory of Open Access Journals (Sweden)

    Jonghan Kim

    Full Text Available Iron-responsive manganese uptake is increased in iron-deficient rats, suggesting that toxicity related to manganese exposure could be modified by iron status. To explore possible interactions, the distribution of intranasally-instilled manganese in control and iron-deficient rat brain was characterized by quantitative image analysis using T1-weighted magnetic resonance imaging (MRI. Manganese accumulation in the brain of iron-deficient rats was doubled after intranasal administration of MnCl(2 for 1- or 3-week. Enhanced manganese level was observed in specific brain regions of iron-deficient rats, including the striatum, hippocampus, and prefrontal cortex. Iron-deficient rats spent reduced time on a standard accelerating rotarod bar before falling and with lower peak speed compared to controls; unexpectedly, these measures of motor function significantly improved in iron-deficient rats intranasally-instilled with MnCl(2. Although tissue dopamine concentrations were similar in the striatum, dopamine transporter (DAT and dopamine receptor D(1 (D1R levels were reduced and dopamine receptor D(2 (D2R levels were increased in manganese-instilled rats, suggesting that manganese-induced changes in post-synaptic dopaminergic signaling contribute to the compensatory effect. Enhanced olfactory manganese uptake during iron deficiency appears to be a programmed "rescue response" with beneficial influence on motor impairment due to low iron status.

  1. Sulfidation of alumina-supported iron and iron-molybdenum oxide catalysts

    NARCIS (Netherlands)

    Ramselaar, W.L.T.M.; Crajé, M.W.J.; Hadders, R.H.; Gerkema, E.; Beer, de V.H.J.; Kraan, van der A.M.

    1990-01-01

    The transition of alumina-supported iron and iron-molybdenum catalysts from the oxidic precursor to the sulfided catalysts was systematically studied by means of in-situ Mössbauer spectroscopy at room temperature. This enabled the adjudgement of various sulfidic phases in the sulfided catalysts. The

  2. Manganese and iron oxidation by fungi isolated from building stone.

    Science.gov (United States)

    de la Torre, M A; Gomez-Alarcon, G

    1994-01-01

    Acid and nonacid generating fungal strains isolated from weathered sandstone, limestone, and granite of Spanish cathedrals were assayed for their ability to oxidize iron and manganese. In general, the concentration of the different cations present in the mineral salt media directly affected Mn(IV) oxide formation, although in some cases, the addition of glucose and nitrate to the culture media was necessary. Mn(II) oxidation in acidogenic strains was greater in a medium containing the highest concentrations of glucose, nitrate, and manganese. High concentrations of Fe(II), glucose, and mineral salts were optimal for iron oxidation. Mn(IV) precipitated as oxides or hydroxides adhered to the mycelium. Most of the Fe(III) remained in solution by chelation with organic acids excreted by acidogenic strains. Other metabolites acted as Fe(III) chelators in nonacidogenic strains, although Fe(III) deposits around the mycelium were also detected. Both iron and manganese oxidation were shown to involve extracellular, hydrosoluble enzymes, with maximum specific activities during exponential growth. Strains able to oxidize manganese were also able to oxidize iron. It is concluded that iron and manganese oxidation reported in this work were biologically induced by filamentous fungi mainly by direct (enzymatic) mechanisms.

  3. Bioconcentration of manganese and iron in Panaeoloideae Sing

    OpenAIRE

    Stijve, T.; Blake, C.

    1994-01-01

    According to literature, the manganese content of most basidiomycetes fluctuates between 10 and 60 mg/kg, whereas the iron levels range from 100-500 mg/kg (both expressed on dry weight). The present authors report that bioconcentration of manganese is a distinguishing feature of the Panaeoloideae, as demonstrated by the analysis of 44 collections representing 15 taxons. Carpophores generally contain between 250 and 2500 mg/kg on dry weight, and, with the notable exception of Panaeolus semiova...

  4. Manganese and Iron Catalysts in Alkyd Paints and Coatings

    Directory of Open Access Journals (Sweden)

    Ronald Hage

    2016-04-01

    Full Text Available Many paint, ink and coating formulations contain alkyd-based resins which cure via autoxidation mechanisms. Whilst cobalt-soaps have been used for many decades, there is a continuing and accelerating desire by paint companies to develop alternatives for the cobalt soaps, due to likely classification as carcinogens under the REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals legislation. Alternative driers, for example manganese and iron soaps, have been applied for this purpose. However, relatively poor curing capabilities make it necessary to increase the level of metal salts to such a level that often coloring of the paint formulation occurs. More recent developments include the application of manganese and iron complexes with a variety of organic ligands. This review will discuss the chemistry of alkyd resin curing, the applications and reactions of cobalt-soaps as curing agents, and, subsequently, the paint drying aspects and mechanisms of (model alkyd curing using manganese and iron catalysts.

  5. [Factors affecting biological removal of iron and manganese in groundwater].

    Science.gov (United States)

    Xue, Gang; He, Sheng-Bing; Wang, Xin-Ze

    2006-01-01

    Factors affecting biological process for removing iron and manganese in groundwater were analyzed. When DO and pH in groundwater after aeration were 7.0 - 7.5 mg/L and 6.8 - 7.0 respectively, not only can the activation of Mn2+ oxidizing bacteria be maintained, but also the demand of iron and manganese removal can be satisfied. A novel inoculating approach of grafting mature filter material into filter bed, which is easier to handle than selective culture media, was employed in this research. However, this approach was only suitable to the filter material of high-quality manganese sand with strong Mn2+ adsorption capacity. For the filter material of quartz sand with weak adsorption capacity, only culturing and domesticating Mn2+ oxidizing bacteria by selective culture media can be adopted as inoculation in filter bed. The optimal backwashing rate of biological filter bed filled with manganese sand and quartz sand should be kept at a relatively low level of 6 - 9 L/(m2 x s) and 7 -11 L/( m2 x s), respectively. Then the stability of microbial phase in filter bed was not disturbed, and iron and manganese removal efficiency recovered in less than 5h. Moreover, by using filter material with uniform particle size of 1.0 - 1.2 mm in filter bed, the filtration cycle reached as long as 35 - 38h.

  6. Iron Sulfur and Molybdenum Cofactor Enzymes Regulate the Drosophila Life Cycle by Controlling Cell Metabolism

    Science.gov (United States)

    Marelja, Zvonimir; Leimkühler, Silke; Missirlis, Fanis

    2018-01-01

    Iron sulfur (Fe-S) clusters and the molybdenum cofactor (Moco) are present at enzyme sites, where the active metal facilitates electron transfer. Such enzyme systems are soluble in the mitochondrial matrix, cytosol and nucleus, or embedded in the inner mitochondrial membrane, but virtually absent from the cell secretory pathway. They are of ancient evolutionary origin supporting respiration, DNA replication, transcription, translation, the biosynthesis of steroids, heme, catabolism of purines, hydroxylation of xenobiotics, and cellular sulfur metabolism. Here, Fe-S cluster and Moco biosynthesis in Drosophila melanogaster is reviewed and the multiple biochemical and physiological functions of known Fe-S and Moco enzymes are described. We show that RNA interference of Mocs3 disrupts Moco biosynthesis and the circadian clock. Fe-S-dependent mitochondrial respiration is discussed in the context of germ line and somatic development, stem cell differentiation and aging. The subcellular compartmentalization of the Fe-S and Moco assembly machinery components and their connections to iron sensing mechanisms and intermediary metabolism are emphasized. A biochemically active Fe-S core complex of heterologously expressed fly Nfs1, Isd11, IscU, and human frataxin is presented. Based on the recent demonstration that copper displaces the Fe-S cluster of yeast and human ferredoxin, an explanation for why high dietary copper leads to cytoplasmic iron deficiency in flies is proposed. Another proposal that exosomes contribute to the transport of xanthine dehydrogenase from peripheral tissues to the eye pigment cells is put forward, where the Vps16a subunit of the HOPS complex may have a specialized role in concentrating this enzyme within pigment granules. Finally, we formulate a hypothesis that (i) mitochondrial superoxide mobilizes iron from the Fe-S clusters in aconitase and succinate dehydrogenase; (ii) increased iron transiently displaces manganese on superoxide dismutase, which

  7. Iron Sulfur and Molybdenum Cofactor Enzymes Regulate the Drosophila Life Cycle by Controlling Cell Metabolism

    Directory of Open Access Journals (Sweden)

    Zvonimir Marelja

    2018-02-01

    Full Text Available Iron sulfur (Fe-S clusters and the molybdenum cofactor (Moco are present at enzyme sites, where the active metal facilitates electron transfer. Such enzyme systems are soluble in the mitochondrial matrix, cytosol and nucleus, or embedded in the inner mitochondrial membrane, but virtually absent from the cell secretory pathway. They are of ancient evolutionary origin supporting respiration, DNA replication, transcription, translation, the biosynthesis of steroids, heme, catabolism of purines, hydroxylation of xenobiotics, and cellular sulfur metabolism. Here, Fe-S cluster and Moco biosynthesis in Drosophila melanogaster is reviewed and the multiple biochemical and physiological functions of known Fe-S and Moco enzymes are described. We show that RNA interference of Mocs3 disrupts Moco biosynthesis and the circadian clock. Fe-S-dependent mitochondrial respiration is discussed in the context of germ line and somatic development, stem cell differentiation and aging. The subcellular compartmentalization of the Fe-S and Moco assembly machinery components and their connections to iron sensing mechanisms and intermediary metabolism are emphasized. A biochemically active Fe-S core complex of heterologously expressed fly Nfs1, Isd11, IscU, and human frataxin is presented. Based on the recent demonstration that copper displaces the Fe-S cluster of yeast and human ferredoxin, an explanation for why high dietary copper leads to cytoplasmic iron deficiency in flies is proposed. Another proposal that exosomes contribute to the transport of xanthine dehydrogenase from peripheral tissues to the eye pigment cells is put forward, where the Vps16a subunit of the HOPS complex may have a specialized role in concentrating this enzyme within pigment granules. Finally, we formulate a hypothesis that (i mitochondrial superoxide mobilizes iron from the Fe-S clusters in aconitase and succinate dehydrogenase; (ii increased iron transiently displaces manganese on superoxide

  8. Adsorptive removal of manganese, arsenic and iron from groundwater

    NARCIS (Netherlands)

    Buamah, R.

    2009-01-01

    To determine the scale of the problem of arsenic, iron and manganese contamination of groundwater in Ghana a survey was performed in the first phase of the research to provide in depth information with respect to these contaminants. Presence of these mentioned contaminants in groundwater is not

  9. Arsenic, chromium, copper, iron, manganese, lead, selenium and ...

    African Journals Online (AJOL)

    2014-05-20

    May 20, 2014 ... Arsenic, chromium, copper, iron, manganese, lead, selenium and zinc in the ... and sediment were collected and trace element concentrations were measured with an ICP-MS. ..... Clay minerals are known to have high sorption affinities ..... sediment/water quality interaction with particular reference to the.

  10. Manganese, iron and copper contents in leaves of maize plants ...

    African Journals Online (AJOL)

    Micronutrients such as boron (B), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) play important physiological roles in humans and animals. Zn and B are the micronutrients most often deficient in maize, in Iran. A completely randomized factorial block design experiment was carried out at Fars province of Iran during ...

  11. Pilot study points way to iron/manganese removal

    Energy Technology Data Exchange (ETDEWEB)

    Qureshi, N.; Barnes, A. [Progressive Consulting Engineers Inc., Minneapolis, MN (United States)

    1994-12-31

    The use of coal, greensand and sand in filters for removing iron and manganese from the Brooklyn Park, Minnesota, water supply was investigated. The most effective and economic treatment involved using a dual media filtration and potassium permanganate as the oxidant.

  12. Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide

    Science.gov (United States)

    Balistrieri, L.S.; Chao, T.T.

    1990-01-01

    This work compares and models the adsorption of selenium and other anions on a neutral to alkaline surface (amorphous iron oxyhydroxide) and an acidic surface (manganese dioxide). Selenium adsorption on these oxides is examined as a function of pH, particle concentration, oxidation state, and competing anion concentration in order to assess how these factors might influence the mobility of selenium in the environment. The data indicate that 1. 1) amorphous iron oxyhydroxide has a greater affinity for selenium than manganese dioxide, 2. 2) selenite [Se(IV)] adsorption increases with decreasing pH and increasing particle concentration and is stronger than selenate [Se(VI)] adsorption on both oxides, and 3. 3) selenate does not adsorb on manganese dioxide. The relative affinity of selenate and selenite for the oxides and the lack of adsorption of selenate on a strongly acidic surface suggests that selenate forms outer-sphere complexes while selenite forms inner-sphere complexes with the surfaces. The data also indicate that the competition sequence of other anions with respect to selenite adsorption at pH 7.0 is phosphate > silicate > molybdate > fluoride > sulfate on amorphous iron oxyhydroxide and molybdate ??? phosphate > silicate > fluoride > sulfate on manganese dioxide. The adsorption of phosphate, molybdate, and silicate on these oxides as a function of pH indicates that the competition sequences reflect the relative affinities of these anions for the surfaces. The Triple Layer surface complexation model is used to provide a quantitative description of these observations and to assess the importance of surface site heterogeneity on anion adsorption. The modeling results suggest that selenite forms binuclear, innersphere complexes with amorphous iron oxyhydroxide and monodentate, inner-sphere complexes with manganese dioxide and that selenate forms outer-sphere, monodentate complexes with amorphous iron oxyhydroxide. The heterogeneity of the oxide surface sites

  13. Gold, iron and manganese in central Amapá, Brazil

    Directory of Open Access Journals (Sweden)

    Wilson Scarpelli

    Full Text Available ABSTRACT: Greenstone belts with deposits of gold, iron and manganese are common in the Paleoproterozoic Maroni-Itacaiunas Tectonic Province of the Guiana Shield. In Brazil, in the State of Amapá and northwest of Pará, they are represented by the Vila Nova Group, constituted by a basal unit of metabasalts, covered by metasediments of clastic and chemical origin. The basal metasediments, the Serra do Navio Formation, are made of a cyclothem with lenses of manganese marbles at the top of each cycle. Under the intense weathering of the Amazon, these lenses were oxidized to large deposits of high-grade manganese oxides. The exploitation of these oxides left behind the manganese carbonates and low-grade oxides. The overlaying Serra da Canga Formation presents a calcium and magnesium domain grading to an iron domain with banded silicate and oxide iron formations, mined for iron ores. Overlapping structures and superposed metamorphic crystallizations indicate two phases of dynamothermal metamorphism, the first one with axis to north-northeast and the second one to northwest, with an intermediate phase of thermal metamorphism related to syntectonic granitic intrusions. Shears oriented north-south, possibly formed during the first dynamothermal metamorphism and reactivated in the second, are ideal sites for hydrothermalism and gold mineralization, which is greater when occurs in iron formation and carbonate-bearing rocks, as it happened at the Tucano mine. Layered mafic-ultramafic intrusions in the greenstones represent a potential for chromite and platinum group elements. Pegmatites are source of cassiterite and tantalite exploited from alluvial deposits.

  14. Factors affecting radium removal using mixed iron-manganese oxides

    International Nuclear Information System (INIS)

    Mott, H.V. Singh, S.; Kondapally, V.R.

    1993-01-01

    Batch experiments confirmed that sorption of radium by a mixed iron-manganese oxide solid phase shows promise for treating radium-contaminated water. The capacities of these mixed oxides for sorption of radium depend on the composition of the solid phase, the pH of the aqueous solution, and the presence of competing cations. The removal of the oxide-radium complexes from aqueous suspension by manganese greensand filtration was also investigated. It was found that influent radium concentrations of 100 pCi/L were reduced to 2--9 pCi/L by this process. Additional study of the fate of radium in manganese greensand filters is recommended before this procedure is used for drinking water treatment

  15. Factors affecting radium removal using mixed iron-manganese oxides

    Energy Technology Data Exchange (ETDEWEB)

    Mott, H.V. Singh, S.; Kondapally, V.R. (South Dakota School of Mines and Technology, Rapid City, SD (United States))

    1993-10-01

    Batch experiments confirmed that sorption of radium by a mixed iron-manganese oxide solid phase shows promise for treating radium-contaminated water. The capacities of these mixed oxides for sorption of radium depend on the composition of the solid phase, the pH of the aqueous solution, and the presence of competing cations. The removal of the oxide-radium complexes from aqueous suspension by manganese greensand filtration was also investigated. It was found that influent radium concentrations of 100 pCi/L were reduced to 2--9 pCi/L by this process. Additional study of the fate of radium in manganese greensand filters is recommended before this procedure is used for drinking water treatment.

  16. Iron binary and ternary coatings with molybdenum and tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Yar-Mukhamedova, Gulmira, E-mail: gulmira-alma-ata@mail.ru [Institute Experimental and Theoretical Physics Al-Farabi Kazakh National University, 050038, Al-Farabi av., 71, Almaty (Kazakhstan); Ved, Maryna; Sakhnenko, Nikolay; Karakurkchi, Anna; Yermolenko, Iryna [National Technical University “Kharkov Polytechnic Institute”, Kharkov (Ukraine)

    2016-10-15

    Highlights: • High quality coatings of double Fe-Mo and ternary Fe-Mo-W electrolytic alloys can be produced both in a dc and a pulsed mode. • Application of unipolar pulsed current allows receiving an increased content of the alloying components and their more uniform distribution over the surface. • It is established that Fe-Mo and Fe-Mo-W coatings have an amorphous structure and exhibit improved corrosion resistance and microhardness as compared with the steel substrate due to the inclusion molybdenum and tungsten. - Abstract: Electrodeposition of Fe-Mo-W and Fe-Mo layers from a citrate solution containing iron(III) on steel and iron substrates is compared. The utilization of iron(III) compounds significantly improved the electrolyte stability eliminating side anodic redox reactions. The influence of concentration ratios and electrodeposition mode on quality, chemical composition, and functional properties of the alloys is determined. It has been found that alloys deposited in pulse mode have more uniform surface morphology and chemical composition and contain less impurities. Improvement in physical and mechanical properties as well as corrosion resistance of Fe-Mo and Fe-Mo-W deposits when compared with main alloy forming metals is driven by alloying components chemical passivity as well as by alloys amorphous structure. Indicated deposits can be considered promising materials in surface hardening technologies and repair of worn out items.

  17. Structural and electrical properties of iron molybdenum phosphate glasses

    International Nuclear Information System (INIS)

    De Oliveira, R.S.; Quixada-Ceara, Univ. Estadual do Ceara; De Paiva, J.A.C.; De Araujo, M.A.B.; Sombra, A. S.B.

    1998-01-01

    iron molybdenum phosphate glasses (xMoO 3 ·(0.6 - x)P 2 O 5 ·0.4Li 2 O) : yFe 2 O 2 with 0≤x≤ 0.6 and y = 0.03 (mol%) prepared in ambient atmosphere using the melt quenching technique were studied by using DC electrical conductivity, 57 Fe Moessbauer and infrared spectroscopies. The Dc conductivity depends on the MoO 3 concentration x. It was observed that, with increasing x, the ratio Fe 2+ /(Fe 3+ + Fe 2+ ) and the Dc conductivity increase. Infrared spectroscopy and X-ray powder diffraction indicate that a Li 2 MoO 4 crystalline phase is present for high MoO 3 content samples (x = 0.5, 0.6)

  18. Restoration of growth by manganese in a mutant strain of Escherichia coli lacking most known iron and manganese uptake systems

    DEFF Research Database (Denmark)

    Taudte, Nadine; German, Nadezhda; Zhu, Yong-Guan

    2016-01-01

    The interplay of manganese and iron homeostasis and oxidative stress in Escherichia coli can give important insights into survival of bacteria in the phagosome and under differing iron or manganese bioavailabilities. Here, we characterized a mutant strain devoid of all know iron/manganese-uptake ......The interplay of manganese and iron homeostasis and oxidative stress in Escherichia coli can give important insights into survival of bacteria in the phagosome and under differing iron or manganese bioavailabilities. Here, we characterized a mutant strain devoid of all know iron...

  19. Arsenic enrichment in estuarine sediments-impact of iron and manganese mining

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, M.; Joseph, T.; Balachandran, K.K.; Nair, K.K.C.; Paimpillii, J.S.

    River Mandovi and Zuari, Goa (west coast of India) are flowing through iron and manganese mining areas and are heavily used for iron and manganese ore transport. This region generates 25-30 million tons of mining rejects per year. The iron ore...

  20. Manganese

    Science.gov (United States)

    Cannon, William F.; Kimball, Bryn E.; Corathers, Lisa A.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Manganese is an essential element for modern industrial societies. Its principal use is in steelmaking, where it serves as a purifying agent in iron-ore refining and as an alloy that converts iron into steel. Although the amount of manganese consumed to make a ton of steel is small, ranging from 6 to 9 kilograms, it is an irreplaceable component in the production of this fundamental material. The United States has been totally reliant on imports of manganese for many decades and will continue to be so for at least the near future. There are no domestic reserves, and although some large low-grade resources are known, they are far inferior to manganese ores readily available on the international market. World reserves of manganese are about 630 million metric tons, and annual global consumption is about 16 million metric tons. Current reserves are adequate to meet global demand for several decades. Global resources in traditional land-based deposits, including both reserves and rocks sufficiently enriched in manganese to be ores in the future, are much larger, at about 17 billion metric tons. Manganese resources in seabed deposits of ferromanganese nodules and crusts are larger than those on land and have not been fully quantified. No production from seabed deposits has yet been done, but current research and development activities are substantial and may bring parts of these seabed resources into production in the future. The advent of economically successful seabed mining could substantially alter the current scenario of manganese supply by providing a large new source of manganese in addition to traditional land-based deposits.From a purely geologic perspective, there is no global shortage of proven ores and potential new ores that could be developed from the vast tonnage of identified resources. Reserves and resources are very unevenly distributed, however. The Kalahari manganese district in South Africa contains 70 percent of the world’s identified resources

  1. Dimensional crossover in manganese based analogues of iron pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Zingl, Manuel; Assmann, Elias; Aichhorn, Markus [University of Technology, Institute of Theoretical Physics and Computational Physics, Graz (Austria)

    2016-07-01

    The manganese pnicitides BaMn{sub 2}As{sub 2} and LaOMnAs crystallize in the same structure as the extensively studied iron pnictide high-temperature superconductors BaFe{sub 2}As{sub 2} and LaOFeAs. In contrast to the d{sup 6} configuration of the iron systems, the manganese d-shell is only half-filled (d{sup 5}). As a consequence, electronic correlations are much stronger, placing these compounds at the verge of the Mott metal-insulator transition. In this region of the phase diagram materials are prone to enhanced magnetism, apparent in the remarkably high Neel temperature of 625 K for BaMn{sub 2}As{sub 2}. We demonstrate that the experimentally observed differences in the Neel temperatures, the band gap, and the optical properties of the manganese compounds under consideration can be traced back to their effective dimensionality. Our fully charge self-consistent DFT+DMFT calculations show excellent agreement with experiments, especially measured optical spectra.

  2. Iron and manganese oxides modified maize straw to remove tylosin from aqueous solutions.

    Science.gov (United States)

    Yin, Yongyuan; Guo, Xuetao; Peng, Dan

    2018-08-01

    Maize straw modified by iron and manganese oxides was synthesized via a simple and environmentally friendly method. Three maize straw materials, the original maize straw, maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides, were detected by SEM, BET, XPS, XRD and FTIR. The results showed that maize straw was successfully modified and maize straw modified by iron and manganese oxides has a larger surface area than MS. According to the experimental data, the sorption trend could conform to the pseudo-second-order kinetic model well, and the sorption ability of tylosin on sorbents followed the order of original maize straw oxides iron and manganese oxides. The study indicated that manganese oxides and iron-manganese oxides could significantly enhance the sorption capacity of original maize straw. The sorption isotherm data of tylosin on original maize straw fit a linear model well, while Freundlich models were more suitable for maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides. The pH, ionic strength and temperature can affect the sorption process. The sorption mechanisms of tylosin on iron and manganese oxides modified maize straw were attribute to the surface complexes, electrostatic interactions, H bonding and hydrophobic interactions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Early diagenesis of manganese, iron and phosphorus in European continental margin sediments

    NARCIS (Netherlands)

    Zee, C. van der

    2002-01-01

    This thesis describes the results of a project that was carried out as a part of the Sedimentary Manganese and Iron cycLEs (SMILE) research program funded by the Netherlands Organisation of Scientific Research (NWO/ALW). SMILE aimed at studying the biogeochemistry of iron and manganese cycles in

  4. Early diagenesis of Manganese, Iron and Phosphorus in European continental margin sediments

    NARCIS (Netherlands)

    van der Zee, C.

    2002-01-01

    This thesis describes the results of a project that was carried out as a part of the Sedimentary Manganese and Iron cycLEs (SMILE) research program funded by the Netherlands Organisation of Scientific Research (NWO/ALW). SMILE aimed at studying the biogeochemistry of iron and manganese cycles in

  5. Iron and manganese removal from a groundwater supply

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, W.; Seifert, K.; Kasch, O.K. (Arber Richard P. Associates, Inc., Denver, CO (USA))

    1988-11-01

    The treatment options and planning techniques used by the town of Castle Rock (Colorado) for a new water treatment facility are described. Castle Rock officials assessed the available treatment options for dissolved iron and manganese removal and selected potassium permanganate as the primary oxidant to be followed by manganese greensand. A backup prechlorination system for oxidation was also installed. In addition, to prevent excess headloss buildup in the manganese greensand filter media, an anthracite carbon cap was used as the top filter medium for precipitate removal. It is recommended that a treatability study be performed to determine individual design criteria to allow for specific site conditions. The town also assessed the capital and operation and maintenance costs for both treatment at individual well fields and a centralized location for treatment of a cluster of well fields. The results indicate that it is more economical to provide centralized water treatment even though there are capital costs associated with piping raw water from the individual well fields to the central facility. 3 refs.

  6. Removal of iron and manganese from groundwater: a study of using potassium permanganate and sedimentation

    Directory of Open Access Journals (Sweden)

    Elsheikh Mohamed

    2018-01-01

    Full Text Available Experiments are done for different combinations of Fe+2 and Mn+2 concentrations. The obtained results show that Potassium Permanganate (PP gives good results in iron and manganese removal. By using PP dose near to half of the theoretically required one, it can remove up to 100 % and 90 % of iron and manganese, respectively over different tested concentrations at pH=7.0. Increasing rate of filtration influences the Mn+2 removal process obviously. Sedimentation is required when combined concentrations of iron and manganese are greater than 5.0 ppm to reduce filter rapid clogging. Using conventional treatment with adding alum, flocculation, sedimentation and filtration can remove up to 97% and 18% of iron and manganese, respectively. Using PP in addition to alum enhances manganese removal but decreases iron removal. However, using alum with increasing pH to 10 leads to 100 % and 95 % of Fe+2 and Mn+2 removal and increases filter working period.

  7. 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

  8. Thermodynamic Interactions Among Carbon, Silicon and Iron in Carbon Saturated Manganese Melts

    International Nuclear Information System (INIS)

    Paek, Min-Kyu; Lee, Won-Kyu; Jin, Jinan; Jang, Jung-Mock; Pak, Jong-Jin

    2012-01-01

    Thermodynamics of carbon in manganese alloy melts is important in manufacturing low carbon ferromanganese and silico-manganese alloys. In order to predict the carbon solubility in liquid Mn-Si-Fe-Csat alloys as a function of melt composition and temperature, thermodynamic interactions among carbon, silicon and iron in carbon saturated liquid manganese should be known. In the present study, the effects of silicon and iron on the carbon solubility in Mn-Si, Mn-Fe and Mn-Si-Fe melts were measured in the temperature range from 1673 to 1773 K. The carbon solubility decreases significantly as silicon and iron contents increase in liquid manganese alloy. The interaction parameters among carbon, silicon and iron in carbon saturated liquid manganese were determined from the carbon solubility data and the Lupis' relation for the interaction coefficient at constant activity.

  9. Effect of dispersed particles of calcium fluoride on the molybdenum solubility in iron

    International Nuclear Information System (INIS)

    Shvejkin, G.P.; Antsiferov, V.N.; Postnikov, V.S.

    1981-01-01

    The results of the investigation of compositions containing 20 at% Mo and 12 vol.% CaF 2 are presented. The sample diffractograms of compositions Fe+20 at% Mo and (Fe+20 at% Mo)+12 vol.% CaF 2 are given. It is shown that the introduction of calcium fluoride results in formation of continuos series of solid solutions of molybdenum in iron. The results of X-ray diffraction investigations on exceeding solubility limit of molybdenum in iron in the presence of calcium fluoride are confirmed

  10. Voltammetric determination of arsenic in high iron and manganese groundwaters.

    Science.gov (United States)

    Gibbon-Walsh, Kristoff; Salaün, Pascal; Uroic, M Kalle; Feldmann, Joerg; McArthur, John M; van den Berg, Constant M G

    2011-09-15

    Determination of the speciation of arsenic in groundwaters, using cathodic stripping voltammetry (CSV), is severely hampered by high levels of iron and manganese. Experiments showed that the interference is eliminated by addition of EDTA, making it possible to determine the arsenic speciation on-site by CSV. This work presents the CSV method to determine As(III) in high-iron or -manganese groundwaters in the field with only minor sample treatment. The method was field-tested in West-Bengal (India) on a series of groundwater samples. Total arsenic was subsequently determined after acidification to pH 1 by anodic stripping voltammetry (ASV). Comparative measurements by ICP-MS as reference method for total As, and by HPLC for its speciation, were used to corroborate the field data in stored samples. Most of the arsenic (78±0.02%) was found to occur as inorganic As(III) in the freshly collected waters, in accordance with previous studies. The data shows that the modified on-site CSV method for As(III) is a good measure of water contamination with As. The EDTA was also found to be effective in stabilising the arsenic speciation for longterm sample storage at room temperature. Without sample preservation, in water exposed to air and sunlight, the As(III) was found to become oxidised to As(V), and Fe(II) oxidised to Fe(III), removing the As(V) by adsorption on precipitating Fe(III)-hydroxides within a few hours. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Determination of iron, copper, manganese and zinc in the soils, grapes and wines of the Azores

    Directory of Open Access Journals (Sweden)

    María Teresa Ribeiro de Lima

    2004-06-01

    Full Text Available This paper describes the determination of iron, copper, manganese and zinc in the soils, grapes and wines of the three viticultural regions of the Azores. Iron, copper and zinc were determined by flame atomic absorption spectrometry and manganese by graphite furnace atomic absorption. The concentrations of the four elements differed in soils of the three regions; there was no difference in the concentration in grapes, whereas significant differences were observed for the wines as regards the amounts of iron, manganese and zinc. The concentrations of these four elements in wine correspond with the mean values observed for other European regions.

  12. Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: Arsenic, manganese, fluoride, iron, and uranium

    Energy Technology Data Exchange (ETDEWEB)

    Bacquart, Thomas [Better Life Laboratories, Calais, VT (United States); Frisbie, Seth [Better Life Laboratories, Calais, VT (United States); Department of Chemistry and Biochemistry, Norwich University, Northfield, VT (United States); Mitchell, Erika [Better Life Laboratories, Calais, VT (United States); Grigg, Laurie [Department of Earth and Environmental Science, Norwich University, Northfield, VT (United States); Cole, Christopher [Department of Chemistry and Biochemistry, Norwich University, Northfield, VT (United States); Small, Colleen [Vermont Department of Health Laboratory, Burlington, VT (United States); Sarkar, Bibudhendra, E-mail: bsarkar@sickkids.ca [Department of Molecular Structure and Function, The Research Institute of The Hospital for Sick Children, University of Toronto, Toronto, Ontario (Canada); Department of Biochemistry, University of Toronto, Toronto, Ontario (Canada)

    2015-06-01

    In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic

  13. Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: Arsenic, manganese, fluoride, iron, and uranium

    International Nuclear Information System (INIS)

    Bacquart, Thomas; Frisbie, Seth; Mitchell, Erika; Grigg, Laurie; Cole, Christopher; Small, Colleen; Sarkar, Bibudhendra

    2015-01-01

    In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic

  14. Synthesis, structure and magnetism of manganese and iron dipicolinates with N,N '-donor ligands

    Czech Academy of Sciences Publication Activity Database

    Uhrecký, Róbert; Svoboda, I.; Růžičková, Z.; Koman, M.; Dlháň, L.; Pavlík, J.; Moncol, J.; Boca, R.

    2015-01-01

    Roč. 425, JAN (2015), s. 134-144 ISSN 0020-1693 Institutional support: RVO:61388980 Keywords : Manganese * Iron * Dipicolinate complexes * Crystal structure * Magnetism Subject RIV: CA - Inorganic Chemistry Impact factor: 1.918, year: 2015

  15. Sublethal effects of cadmium, manganese, lead, zinc and iron on the ...

    African Journals Online (AJOL)

    The toxicological evaluations of cadmium, iron, manganese, lead and zinc were carried out against albino mice model, Mus musculus. On the basis of 96 hrLC50 value, cadmium (0.47 mM) was found to be the most toxic followed by zinc (2.40 mM), lead (2.42 mM), iron (4.25 mM) and manganese (5.70 mM) was least toxic.

  16. Contribution to the study of iron-manganese alloy oxidation in oxygen at high temperatures

    International Nuclear Information System (INIS)

    Olivier, Francoise

    1972-01-01

    This research thesis reports a systematic investigation of the oxidation of three relatively pure iron-manganese alloys in oxygen, under atmospheric pressure, and between 400 and 1000 C, these alloys being annealed as well as work-hardened. It also compares their behaviour with that of non-alloyed iron oxidized under the same conditions. The author describes the experimental techniques and installations, discusses the morphology of oxide films formed under the experimental conditions, discusses the film growth kinetics which is studied by thermogravimetry, proposes interpretations of results, and outlines the influence of manganese addition to iron on iron oxidation

  17. Characteristics and treatment mechanism of mine water with high concentration of iron and manganese

    Energy Technology Data Exchange (ETDEWEB)

    Li, F.; Yang, J.; He, X.; Yang, J.; Tian, T. [Hebei University of Engineering, Handan (China)

    2006-12-15

    The characteristics and treatment of mine water with high concentration or iron and manganese were studied with mine water produced in Jiukuang and Siwan belonging to Hebi Coal Industry Group Co., Ltd. Analysis shows that the mine water is abundant in dissolved oxygen and has high TDS and high turbidity so the mine water does not need aeration. The effect of removal of iron and manganese by coagulation-sedimentation and the influence of filter material and influent water flow rate on effluent quality were investigated. It is shown that the removal rate of iron can reach 90% while removal of manganese can only reach about 20%. The concentration of iron and manganese in the effluent is lower than 0.1 mg/L with filter material of manganese sand which was immersed in KMnO{sub 4} solution at a filtration rate of 7 - 9 m/h. The results show that the layer of activated compound substance membrane formed on the surface of the manganese sand plays an important role in the removal of manganese. 7 refs., 2 figs., 3 tabs.

  18. Effects of manganese oxide and sulphate on the olefin selectivity of iron catalysts in the Fischer Tropsch reaction

    NARCIS (Netherlands)

    Dijk, van W.L.; Niemantsverdriet, J.W.; Kraan, van der A.M.; van der Baan, Hessel

    1982-01-01

    Although it has been claimed by various authors that the addition of manganese oxide, MnO, to an iron catalyst gives a marked increase in the olefin selectivity of iron catalysts, we have been unable to confirm these claims in Fischer Tropsch experiments at 513 K for an iron manganese oxide catalyst

  19. Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: arsenic, manganese, fluoride, iron, and uranium.

    Science.gov (United States)

    Bacquart, Thomas; Frisbie, Seth; Mitchell, Erika; Grigg, Laurie; Cole, Christopher; Small, Colleen; Sarkar, Bibudhendra

    2015-06-01

    In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic

  20. Removal of iron and manganese using biological roughing up flow filtration technology.

    Science.gov (United States)

    Pacini, Virginia Alejandra; María Ingallinella, Ana; Sanguinetti, Graciela

    2005-11-01

    The removal of iron and manganese from groundwater using biological treatment methods is almost unknown in Latin America. Biological systems used in Europe are based on the process of double rapid biofiltration during which dissolved oxygen and pH need to be strictly controlled in order to limit abiotic iron oxidation. The performance of roughing filter technology in a biological treatment process for the removal of iron and manganese, without the use of chemical agents and under natural pH conditions was studied. Two pilot plants, using two different natural groundwaters, were operated with the following treatment line: aeration, up flow roughing filtration and final filtration (either slow or rapid). Iron and manganese removal efficiencies were found to be between 85% and 95%. The high solid retention capability of the roughing filter means that it is possible to remove iron and manganese simultaneously by biotic and abiotic mechanisms. This system combines simple, low-cost operation and maintenance with high iron and manganese removal efficiencies, thus constituting a technology which is particularly suited to small waterworks.

  1. Manganese

    Science.gov (United States)

    ... research suggests that taking a specific product (7-Keto Naturalean) containing manganese, 7-oxo-DHEA, L-tyrosine, ... can absorb.Milk proteinAdding milk protein to the diet might increase the amount of manganese the body ...

  2. Manganese

    International Nuclear Information System (INIS)

    Fayziev, A.R.

    2002-01-01

    Present article is devoted to manganese content in fluoride. The manganese content of some geologic deposits of Tajikistan was determined by means of chemical analysis. The mono mineral samples of fluorite of 5 geologic deposits of various mineralogical and genetic type was studied. The manganese content in fluorite of geologic deposits of various mineralogical and genetic type was defined.

  3. Stabilization of iron and molybdenum amorphous state with interstitials under high rates of cooling

    International Nuclear Information System (INIS)

    Barmin, Yu.V.; Vavilova, V.V.; Verevkin, A.G.; Gertsen, A.T.; Kovneristyj, Yu.K.; Kotyurgin, E.A.; Mirkin, B.V.; Palij, N.A.

    1993-01-01

    Amorphous solidification of iron and molybdenum is investigated in thin films and on surface laser irradiated on air at 10 12 and 10 8 /Ks cooling rates correspondingly. Amorphous solidification occurs during ion plasma spraying in thin films of 50 nm at saturation of carbon and oxygen atoms in the ratio of C:0=2.3, but amorphous state is absent at room temperature. Metastable fcc phase, among bcc, is formed by crystallization

  4. Activity of molybdenum-containing oxide catalysts in the reaction of ethane oxidation

    International Nuclear Information System (INIS)

    Konovalov, V.I.; Ehpova, T.I.; Shchukin, V.P.; Averbukh, A.Ya.

    1977-01-01

    Investigation results concerning the catalytic activity of molybdenum-containing catalysts in ethane oxidation reaction are presented. It has been found that the greatest activity in the temperature range from 450 to 600 deg C is exhibited by cobalt-molybdenum catalyst; at 600 deg C bismuth-molybdenum catalyst is the most active. Nickel-molybdenum catalyst is selective and active with respect to ethylene. Iron- and manganese-molybdenum catalysts do not show high ethane oxidation rates and their selectivity is insignificant

  5. The scavenging of silver by manganese and iron oxides in stream sediments collected from two drainage areas of Colorado

    Science.gov (United States)

    Chao, T.T.; Anderson, B.J.

    1974-01-01

    Stream sediments of two well-weathered and aerated drainage areas of Colorado containing anomalous amounts of silver were allowed to react by shaking with nitric acid of different concentrations (1-10M). Silver, manganese, and iron simultaneously dissolved were determined by atomic absorption. The relationship between silver dissolution and the dissolution of manganese and/or iron was evaluated by linear and multiple regression analyses. The highly significant correlation coefficient (r = 0.913) between silver and manganese dissolution suggests that manganese oxides are the major control on the scavenging of silver in these stream sediments, whereas iron oxides only play a secondary role in this regard. ?? 1974.

  6. Synthesis of waste cooking oil based biodiesel via ferric-manganese promoted molybdenum oxide / zirconia nanoparticle solid acid catalyst: influence of ferric and manganese dopants.

    Science.gov (United States)

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

    2015-01-01

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

  7. Distribution of uranium and thorium isotopes in iron-manganese concretions of the Pacific ocean

    International Nuclear Information System (INIS)

    Kuznetsov, V.Yu.; Andreev, S.I.

    1995-01-01

    Distribution of 238 U, 234 U, 232 Th, 230 Th in cross sections of samples from the Pacific Ocean iron-manganese concretions (IMC) of different genetic types has been studied, the results are presented. Possible influence of diagenetic processes in the deposits mentioned on distribution of the radionuclides in iron-manganese septarian nodules has been considered. The assumption is made that remobilization of Mn, Ni, Cu from IMC containing deposits does not upset uranium and thorium distribution in the concretions resulted from sedimentation mechanism of their formation. 18 refs., 3 tabs

  8. Bioaccessibility of micron-sized powder particles of molybdenum metal, iron metal, molybdenum oxides and ferromolybdenum--Importance of surface oxides.

    Science.gov (United States)

    Mörsdorf, Alexander; Odnevall Wallinder, Inger; Hedberg, Yolanda

    2015-08-01

    The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, that are manufactured, imported or used in different products (substances or articles) are identified and proven safe for humans and the environment. Metals and alloys need hence to be investigated on their extent of released metals (bioaccessibility) in biologically relevant environments. Read-across from available studies may be used for similar materials. This study investigates the release of molybdenum and iron from powder particles of molybdenum metal (Mo), a ferromolybdenum alloy (FeMo), an iron metal powder (Fe), MoO2, and MoO3 in different synthetic body fluids of pH ranging from 1.5 to 7.4 and of different composition. Spectroscopic tools and cyclic voltammetry have been employed to characterize surface oxides, microscopy, light scattering and nitrogen absorption for particle characterization, and atomic absorption spectroscopy to quantify released amounts of metals. The release of molybdenum from the Mo powder generally increased with pH and was influenced by the fluid composition. The mixed iron and molybdenum surface oxide of the FeMo powder acted as a barrier both at acidic and weakly alkaline conditions. These findings underline the importance of the surface oxide characteristics for the bioaccessibility of metal alloys. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Daily dietary intake of iron, copper, zinc and manganese in a Spanish population.

    Science.gov (United States)

    Rubio, Carmen; Gutiérrez, Angel José; Revert, Consuelo; Reguera, Juan Ignacio; Burgos, Antonio; Hardisson, Arturo

    2009-11-01

    To evaluate the daily dietary intake of essential metals in the Canary Islands, the iron, copper, zinc and manganese contents in 420 food and drink samples collected in local markets were analysed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The estimated daily dietary intakes of iron, copper, zinc and manganese are 13.161 mg/day, 2.098 mg/day, 8.954 mg/day and 2.372 mg/day, respectively. The iron dietary intake was found to be below the recommendations fixed for adult women, while the copper and manganese dietary intakes fulfilled the Recommended Dietary Allowances. The mean daily intake of zinc was below the Recommended Dietary Allowance. Cereals were found to be the food group that contributed most to the intake of these metals. While the island of El-Hierro presented iron, copper, zinc and manganese mean intakes over the estimated intakes for the whole archipelago, Fuerteventura island showed the lowest intakes. Tenerife and Fuerteventura showed the lowest iron intakes, being below the recommendations.

  10. Estimation of the effect of molybdenum on chemical and electrochemical stability of iron-based alloys

    International Nuclear Information System (INIS)

    Tyurin, A.G.

    2003-01-01

    The E-pH diagram for Mo-H 2 O system is made more precise. It is shown that a passivating film on molybdenum in weakly acid, neutral and alkali solutions may constitute MoO 2 only. In strongly acid solutions at anodic polarization the film should transform according to the following scheme: MoO 2 → Mo 4 O 11 → Mo 9 O 26 → MoO 3 . Sections of a Fe-Mo-O system phase diagram and a Fe-Mo-H 2 O system E-pH diagram at 25 deg C are plotted. MoO 2 is found to be a product of iron-molybdenum alloy oxidation in the air and in water. For the system of alloy Kh17N13M2-H 2 O the section of a E-pH diagram is plotted at 25 deg C [ru

  11. Iron Intermetallic Phases in the Alloy Based on Al-Si-Mg by Applying Manganese

    Directory of Open Access Journals (Sweden)

    Podprocká R.

    2017-09-01

    Full Text Available Manganese is an effective element used for the modification of needle intermetallic phases in Al-Si alloy. These particles seriously degrade mechanical characteristics of the alloy and promote the formation of porosity. By adding manganese the particles are being excluded in more compact shape of “Chinese script” or skeletal form, which are less initiative to cracks as Al5FeSi phase. In the present article, AlSi7Mg0.3 aluminium foundry alloy with several manganese content were studied. The alloy was controlled pollution for achieve higher iron content (about 0.7 wt. % Fe. The manganese were added in amount of 0.2 wt. %, 0.6 wt. %, 1.0 wt. % and 1.4 wt. %. The influence of the alloying element on the process of crystallization of intermetallic phases were compared to microstructural observations. The results indicate that increasing manganese content (> 0.2 wt. % Mn lead to increase the temperature of solidification iron rich phase (TAl5FeSi and reduction this particles. The temperature of nucleation Al-Si eutectic increase with higher manganese content also. At adding 1.4 wt. % Mn grain refinement and skeleton particles were observed.

  12. Manganese and iron geochemistry in sediments underlying the redox-stratified Fayetteville Green Lake

    Science.gov (United States)

    Herndon, Elizabeth M.; Havig, Jeff R.; Singer, David M.; McCormick, Michael L.; Kump, Lee R.

    2018-06-01

    Manganese and iron are redox-sensitive elements that yield clues about biogeochemistry and redox conditions both in modern environments and in the geologic past. Here, we investigated Mn and Fe-bearing minerals preserved in basin sediments underlying Fayetteville Green Lake, a redox-stratified lake that serves as a geochemical analogue for Paleoproterozoic oceans. Synchrotron-source microprobe techniques (μXRF, μXANES, and μXRD) and bulk geochemical analyses were used to examine the microscale distribution and speciation of Mn, Fe, and S as a function of depth in the top 48 cm of anoxic lake sediments. Manganese was primarily associated with calcite grains as a manganese-rich carbonate that precipitated in the chemocline of the water column and settled through the euxinic basin to collect in lake sediments. Iron was preserved in framboidal iron sulfides that precipitated in euxinic bottom waters and underwent transformation to pyrite and marcasite in the sediments. Previous studies attribute the formation of manganese-rich carbonates to the diagenetic alteration of manganese oxides deposited in basins underlying oxygenated water. Our study challenges this paradigm by providing evidence that Mn-bearing carbonates form in the water column and accumulate in sediments below anoxic waters. Consequently, manganoan carbonates preserved in the rock record do not necessarily denote the presence of oxygenated bottom waters in ocean basins.

  13. 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.

  14. 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

  15. 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.

  16. The Efficiency of Iron and Manganese Removal from Groundwater Using Tower Aeration

    Directory of Open Access Journals (Sweden)

    Meghdad Pirsaheb

    2012-09-01

    Full Text Available Groundwaters passing through different layers of soil and due to its water properties and its high solubility, contain elements and minerals of material in the soil that sometimes can be dangerous for the health of consumers or at least undesirable in terms of cognitive beautiful. Iron and manganese are from constitutive of the soil and rocks of the Earth's surface. Water penetration through soil and rock can minerals such as these elements have dissolved and bring them into solution. The problems of iron and manganese in groundwater in domestic installations, commercial, industrial and refineries are created, and because much of the community water supply from underground water supplies will be removed where iron and manganese concentrations exceeded it is necessary. In this study Tower aeration system performance for the removal of iron and manganese from groundwater sources have been studied. In this research, pilot column aeration tower design, implementation and was established. This system made of PVC with a diameter and height 150 cm and 15 cm which was filled with flexible pipe parts. The initial pH=5, 7 and 9 and the initial concentration of Fe and Mn 2, 3 and 4 mg/l of the output system, sampling was done.

  17. Removal of Iron and Manganese Using Cascade Aerator and Limestone Roughing Filter

    Directory of Open Access Journals (Sweden)

    Mohd Sanusi Azrin

    2016-01-01

    Full Text Available Combination between oxidation and filtration can be used for removing iron and manganese from groundwater especially when the concentrations of these metals were high. This study focused on the effectiveness of the cascade aerator and the size of the limestone filter media to remove iron and manganese from groundwater. Water samples used for this study were collected from orphanage home, Rumah Nur Kasih, Taiping. Universiti Sains Malaysia (USM has provided a tube well of 15 m depth and 150 mm diameter for the orphanage home. However, the water cannot be used for domestic consumption due to high amount of iron and manganese at 6.48 and 1.9 mg/L which exceeded the drinking water standard of 0.3 and 0.1 mg/L respectively. Using laboratory physical model, the study has shown that the removals of iron and manganese have reduce the concentration until 0.17 and 0.2 mg/L respectively. Thus, the results from this study which utilize cascade aerator and limestone roughing filter could be implemented on site for the community to use the ground water for domestic purposes.

  18. X-ray fluorescence determination of cobalt in iron-manganese oceanic concretions

    International Nuclear Information System (INIS)

    Ivanenko, V.V.; Kustov, V.N.; Metelev, A.Yu.; Rakita, K.A.

    1989-01-01

    A method was developed for resolution of weak analytical lines for elements determined by radionuclide-excited X-ray fluorescence multi-element analysis. The method was used aboart for determining cobalt and some other commercially valuable elements in iron-manganese concretions of Pacific ocean 109 Cd was used as an ionizing radiation source

  19. Iron and manganese deposits in Uruguay; Los yacimientos de hierro y manganeso en el Uruguay

    Energy Technology Data Exchange (ETDEWEB)

    Alvarado, B

    1959-07-01

    This report is the results of the study carried out for the United Nations expert which the main object was: the study of the information available about iron and manganese formation in Uruguay, as well as the main researching deposit to determinate economical possibilities in the exportation.

  20. Speciation of iron and manganese in the sediments of Mandovi Estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; Rajendran, A.

    Several attempts have been made to study the distribution of iron and manganese in Mandovi Estuary, Goa, India. But this is the first report of its kind on the speciation of these metals in sediments from Indian waters. This study would be useful...

  1. Redox transitions of chromium, manganese, iron, cobalt and nickel protoporphyrins in aqueous solution

    NARCIS (Netherlands)

    de Groot, M.T.; Koper, M.T.M.

    2008-01-01

    The electrochemical redox behavior of immobilized chromium, manganese, iron, cobalt, and nickel protoporphyrins IX has been investigated over the pH 0–14 range. In the investigated potential domain the metalloporphyrins were observed in four different oxidation states (MI, MII, MIII and MIV). The

  2. Magnetic particles extracted from manganese nodules: Suggested origin from stony and iron meteorites

    Science.gov (United States)

    Finkelman, R.B.

    1970-01-01

    On the basis of x-ray diffraction and electron microprobe data, spherical and ellipsoidal particles extracted from manganese nodules were divided into three groups. Group I particles are believed to be derived from iron meteorites, and Group II particles from stony meteorites. Group III particles are believed to be volcanic in origin.

  3. A chemical approach toward low temperature alloying of immiscible iron and molybdenum metals

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Applied Chemistry Research Centre, Pakistan Council of Scientific and Industrial Research Laboratories Complex, Lahore 54600 (Pakistan); Ahmed, Sohail [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mazhar, Muhammad, E-mail: mazhar42pk@yahoo.com [Department of Chemistry, University of Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia); Akhtar, Muhammad Javed; Siddique, Muhammad [Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Khan, Nawazish Ali [Material Science Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Shah, Muhammad Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Nadeem, Muhammad [Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)

    2013-11-15

    Graphical abstract: - Highlights: • Low temperature pyrolysis of [Fe(bipy){sub 3}]Cl{sub 2} and [Mo(bipy)Cl{sub 4}] homogeneous powder. • Easy low temperature alloying of immiscible metals like Fe and Mo. • Uniform sized Fe–Mo nanoalloy with particle size of 48–68 nm. • Characterization by EDXRF, AFM, XRPD, magnetometery, {sup 57}Fe Mössbauer and impedance. • Alloy behaves as almost superparamagnetic obeying simple –R(CPE)– circuit. - Abstract: The present research is based on a low temperature operated feasible method for the synthesis of immiscible iron and molybdenum metals’ nanoalloy for technological applications. The nanoalloy has been synthesized by pyrolysis of homogeneous powder precipitated, from a common solvent, of the two complexes, trisbipyridineiron(II)chloride, [Fe(bipy){sub 3}]Cl{sub 2}, and bipyridinemolybedenum(IV) chloride, [Mo(bipy)Cl{sub 4}], followed by heating at 500 °C in an inert atmosphere of flowing argon gas. The resulting nanoalloy has been characterized by using EDXRF, AFM, XRD, magnetometery, {sup 57}Fe Mössbauer and impedance spectroscopies. These results showed that under provided experimental conditions iron and molybdenum metals, with known miscibility barrier, alloy together to give (1:1) single phase material having particle size in the range of 48–66 nm. The magnetism of iron is considerably reduced after alloy formation and shows its trend toward superparamagnetism. The designed chemical synthetic procedure is equally feasible for the fabrication of other immiscible metals.

  4. A chemical approach toward low temperature alloying of immiscible iron and molybdenum metals

    International Nuclear Information System (INIS)

    Nazir, Rabia; Ahmed, Sohail; Mazhar, Muhammad; Akhtar, Muhammad Javed; Siddique, Muhammad; Khan, Nawazish Ali; Shah, Muhammad Raza; Nadeem, Muhammad

    2013-01-01

    Graphical abstract: - Highlights: • Low temperature pyrolysis of [Fe(bipy) 3 ]Cl 2 and [Mo(bipy)Cl 4 ] homogeneous powder. • Easy low temperature alloying of immiscible metals like Fe and Mo. • Uniform sized Fe–Mo nanoalloy with particle size of 48–68 nm. • Characterization by EDXRF, AFM, XRPD, magnetometery, 57 Fe Mössbauer and impedance. • Alloy behaves as almost superparamagnetic obeying simple –R(CPE)– circuit. - Abstract: The present research is based on a low temperature operated feasible method for the synthesis of immiscible iron and molybdenum metals’ nanoalloy for technological applications. The nanoalloy has been synthesized by pyrolysis of homogeneous powder precipitated, from a common solvent, of the two complexes, trisbipyridineiron(II)chloride, [Fe(bipy) 3 ]Cl 2 , and bipyridinemolybedenum(IV) chloride, [Mo(bipy)Cl 4 ], followed by heating at 500 °C in an inert atmosphere of flowing argon gas. The resulting nanoalloy has been characterized by using EDXRF, AFM, XRD, magnetometery, 57 Fe Mössbauer and impedance spectroscopies. These results showed that under provided experimental conditions iron and molybdenum metals, with known miscibility barrier, alloy together to give (1:1) single phase material having particle size in the range of 48–66 nm. The magnetism of iron is considerably reduced after alloy formation and shows its trend toward superparamagnetism. The designed chemical synthetic procedure is equally feasible for the fabrication of other immiscible metals

  5. 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.

  6. Removal of Arsenic, Iron, Manganese, and Ammonia in Drinking Water: Nagaoka International Corporation CHEMILES NCL Series Water Treatment System

    Science.gov (United States)

    The Nagaoka International Corporation CHEMILES NCL Series system was tested to verify its performance for the reduction of multiple contaminants including: arsenic, ammonia, iron, and manganese. The objectives of this verification, as operated under the conditions at the test si...

  7. A predictive regression model for the geochemical variability of iron and manganese in a coral reef ecosystem

    Digital Repository Service at National Institute of Oceanography (India)

    Gopinath, A.; Kumar, N.C.; Jayalakshmy, K.V.; Padmalal, D.; Nair, S.M.

    This article focuses on the influence of nutrient forms (nitrogen/phosphorous forms) and parameters like pH and organic carbon in the distributional characteristics of two important trace metals, viz. iron and manganese, in different sedimentary...

  8. Methods for the shipboard determination of dissolved iron and manganese in samples of sediment interstitial water

    International Nuclear Information System (INIS)

    Hydes, D.J.; Chapman, E.

    1986-01-01

    Iron is extremely unstable in the presence of oxygen. A working atmosphere containing less than 0.2% oxygen is required if iron losses are not to be significant. Iron can be determined with a single addition of reagent, either manually or by a continuous flow procedure using ferrozine. Using a continuous flow procedure with a 5 cm colorimeter cell the method is linear up to 40 μM Fe and the precision is 2%. Manganese can similarly be determined with a single reagent addition using formaldoxime. For the continuous flow procedure with a 5 cm colorimeter cell the method is linear up to 60 μM Mn and the precision is 1%; however, under these conditions a solution containing 100 μm of iron produces an interference equivalent to 4.7 μM of manganese. A two-reagent procedure was developed using EDTA to suppress the iron interference. Using a 5% EDTA solution interference from a solution containing 100 μM of iron was undetectable. (author)

  9. Influence of iron and beryllium additions on heat resistance of silicide coatings on TsMB-30 molybdenum alloy

    International Nuclear Information System (INIS)

    Zajtseva, A.L.; Fedorchuk, N.M.; Lazarev, Eh.M.; Korotkov, N.A.

    1985-01-01

    Alloying of titanium modified silicide coatings on TsMB-30 molybdenum alloy with iron or beryllium is stated to improve their protective properties. Coatings with low content of alloying elements have the best protective properties. Service life of coatings is determined by the formed oxide film and phase transformations taking place in the coating

  10. Power loss and energy density of the asymmetric ultracapacitor loaded with molybdenum doped manganese oxide

    International Nuclear Information System (INIS)

    Wang, Yue-Sheng; Tsai, Dah-Shyang; Chung, Wen-Hung; Syu, Yong-Sin; Huang, Ying-Sheng

    2012-01-01

    Highlights: ► Mo-doping (15 mol%) enhances capacitance and diminishes oxide resistance. ► Influences of Mo-doped MnO 2 are analyzed at the level of capacitor power and energy. ► Polarization loss of the asymmetric capacitor is more than that of the symmetric one. ► Pseudocapacitance benefit on energy is evaluated with power and current densities. - Abstract: Ultracapacitors of asymmetric configuration have been prepared with activated carbon (AC) and undoped or Mo-doped manganese oxide (MnO 2 ) in 1.0 M Na 2 SO 4 electrolyte. Phase analysis shows the AC powder, 1–15 μm in size, contains both disordered and graphitic structures, and the undoped and Mo-doped oxide powder, 0.05–0.20 μm in particle size, mainly involves amorphous MnO 2 and MoO 2 . CV results indicate the single electrode of AC plus 10 wt% Mo-doped MnO 2 (A9O M 1) is superior to the electrode with undoped MnO 2 or high content of doped MnO 2 , exhibiting features of double layer capacitance at high scan rate and pseudocapacitance characteristics at low scan rate. When assembled with a negative electrode of AC, the capacitor of positive A9O M 1 electrode demonstrates the least power loss among three asymmetric capacitors. This asymmetric capacitor also shows a higher capacitance than the symmetric AC capacitor when the current density is less than 8.0 A g −1 in 1.8 V potential window. But a higher electrode resistance of A9O M 1, in contrast with AC, compromises its capacitance plus. When the energy density of A9O M 1 asymmetric capacitor is compared with that of symmetric AC capacitor at the same power level, the capacitance benefit on energy density is restricted to current density ≤ 3.0 A g −1 .

  11. Associations of iron metabolism genes with blood manganese levels: a population-based study with validation data from animal models

    Directory of Open Access Journals (Sweden)

    Claus Henn Birgit

    2011-11-01

    Full Text Available Abstract Background Given mounting evidence for adverse effects from excess manganese exposure, it is critical to understand host factors, such as genetics, that affect manganese metabolism. Methods Archived blood samples, collected from 332 Mexican women at delivery, were analyzed for manganese. We evaluated associations of manganese with functional variants in three candidate iron metabolism genes: HFE [hemochromatosis], TF [transferrin], and ALAD [δ-aminolevulinic acid dehydratase]. We used a knockout mouse model to parallel our significant results as a novel method of validating the observed associations between genotype and blood manganese in our epidemiologic data. Results Percentage of participants carrying at least one copy of HFE C282Y, HFE H63D, TF P570S, and ALAD K59N variant alleles was 2.4%, 17.7%, 20.1%, and 6.4%, respectively. Percentage carrying at least one copy of either C282Y or H63D allele in HFE gene was 19.6%. Geometric mean (geometric standard deviation manganese concentrations were 17.0 (1.5 μg/l. Women with any HFE variant allele had 12% lower blood manganese concentrations than women with no variant alleles (β = -0.12 [95% CI = -0.23 to -0.01]. TF and ALAD variants were not significant predictors of blood manganese. In animal models, Hfe-/- mice displayed a significant reduction in blood manganese compared with Hfe+/+ mice, replicating the altered manganese metabolism found in our human research. Conclusions Our study suggests that genetic variants in iron metabolism genes may contribute to variability in manganese exposure by affecting manganese absorption, distribution, or excretion. Genetic background may be critical to consider in studies that rely on environmental manganese measurements.

  12. Biomimetic oxidation of piperine and piplartine catalyzed by iron(III) and manganese(III) porphyrins.

    Science.gov (United States)

    Schaab, Estela Hanauer; Crotti, Antonio Eduardo Miller; Iamamoto, Yassuko; Kato, Massuo Jorge; Lotufo, Letícia Veras Costa; Lopes, Norberto Peporine

    2010-01-01

    Synthetic metalloporphyrins, in the presence of monooxygen donors, are known to mimetize various reactions of cytochrome P450 enzymes systems in the oxidation of drugs and natural products. The oxidation of piperine and piplartine by iodosylbenzene using iron(III) and manganese(III) porphyrins yielded mono- and dihydroxylated products, respectively. Piplartine showed to be a more reactive substrate towards the catalysts tested. The structures of the oxidation products were proposed based on electrospray ionization tandem mass spectrometry.

  13. Evaluation of iron, zinc, copper, manganese and selenium in oral hospital diets.

    OpenAIRE

    Moreira, Daniele Caroline Faria; Sá, Júlia Sommerlatte Manzoli de; Cerqueira, Isabel B.; Oliveira, Ana P. F. de; Morgano, Marcelo Antonio; Quintaes, Késia Diego

    2013-01-01

    Background & aims: Many trace elements are nutrients essential to humans, acting in the metabolism as constituents or as enzymatic co-factors. The iron, zinc, copper, manganese and selenium contents of hospital diets (regular, blend and soft) and of oral food complement (OFC) were determined, evaluating the adequacy of each element in relation to the nutritional recommendations (DRIs) and the percent contribution alone and with OFC. Methods: Duplicate samples were taken of six daily meals ...

  14. Use of a portable X-ray analyser for manganese and iron assay in minerals

    International Nuclear Information System (INIS)

    Taqueda, M.H.S.; Agudo, E.G.

    1975-01-01

    The use of a protable X-ray fluorescence analyser for manganese and iron assay in minerals is described. The concentration range in the measured samples was 30% to 60% for Mn and 2% to 20% for Fe. The excitation source used was a 3 mCi 109 Cd sealed source. Balanced filters were used for the X-ray analysis. The statistical study of results showed a precision better than 0,5 for Mn, but only 4% for iron. They can be improved either increasing the counting time or using a 238 Pu source

  15. Iron and manganese in anaerobic respiration: environmental significance, physiology, and regulation

    Science.gov (United States)

    Nealson, K. H.; Saffarini, D.

    1994-01-01

    Dissimilatory iron and/or manganese reduction is known to occur in several organisms, including anaerobic sulfur-reducing organisms such as Geobacter metallireducens or Desulfuromonas acetoxidans, and facultative aerobes such as Shewanella putrefaciens. These bacteria couple both carbon oxidation and growth to the reduction of these metals, and inhibitor and competition experiments suggest that Mn(IV) and Fe(III) are efficient electron acceptors similar to nitrate in redox abilities and capable of out-competing electron acceptors of lower potential, such as sulfate (sulfate reduction) or CO2 (methanogenesis). Field studies of iron and/or manganese reduction suggest that organisms with such metabolic abilities play important roles in coupling the oxidation of organic carbon to metal reduction under anaerobic conditions. Because both iron and manganese oxides are solids or colloids, they tend to settle downward in aquatic environments, providing a physical mechanism for the movement of oxidizing potential into anoxic zones. The resulting biogeochemical metal cycles have a strong impact on many other elements including carbon, sulfur, phosphorous, and trace metals.

  16. The concentration of manganese, iron and strontium in bone of red fox Vulpes vulpes (L. 1758).

    Science.gov (United States)

    Budis, Halina; Kalisinska, Elzbieta; Lanocha, Natalia; Kosik-Bogacka, Danuta I

    2013-12-01

    The aims of the study were to determine manganese (Mn), iron (Fe) and strontium (Sr) concentrations in fox bone samples from north-western Poland and to examine the relationships between the bone Mn, Fe and Sr concentrations and the sex and age of the foxes. In the studied samples of fox cartilage, cartilage with adjacent compact bone, compact bone and spongy bone, the concentrations of the analysed metals had the following descending order: Fe > Sr > Mn. The only exception was in compact bone, in which the concentrations were arranged in the order Sr > Fe > Mn. Manganese concentrations were significantly higher in cartilage, compact bone and cartilage with compact bone than in spongy bone. Iron concentrations were higher in cartilage and spongy bone compared with compact bone. Strontium concentrations were greater in compact bone than in cartilage and spongy bone. The manganese, iron and strontium concentrations in the same type of bone material in many cases correlated with each other, with the strongest correlation (r > 0.70) between Mn and Fe in almost all types of samples. In addition, concentrations of the same metals in different bone materials were closely correlated for Mn and Fe in cartilage and cartilage with adjacent compact bone, and for Sr in compact bone and cartilage with compact bone. In the fox from NW Poland, there were no statistically significant differences in Mn, Fe and Sr in any of the types of bone material between the sexes and immature and adult foxes.

  17. Effects of iron and manganese on the formation of HAAs upon chlorinating Chlorella vulgaris

    International Nuclear Information System (INIS)

    Ge, Fei; Wu, Xiuzhen; Wang, Na; Zhu, Runliang; Wang, Tong; Xu, Yin

    2011-01-01

    The major objective of the present study was to investigate the role of iron and manganese on the formation of haloacetic acids (HAAs) when algae are chlorinated at different pHs. The results showed that both iron and manganese can reduce the yields of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) on chlorinating green alga Chlorella vulgaris (C. vulgaris) at a pH range of 6.0-9.0, and the decline of DCAA and TCAA was shown to be more significant at the low pH range. At pH 6.0, DCAA and TCAA yields decreased by 44.5% and 57.3%, respectively with the addition of 0.5 mg L -1 iron, and decreased 39.5% and 49.4%, respectively with the addition of 0.5 mg L -1 manganese. The main reason for decreasing the yields of HAAs as shown by scanning electron microscope (SEM) is that Fe(OH) 3(am) or MnO 2(am) coat the algal cells , which then improves their agglomeration of algal cells which is also revealed by the laser particle size analysis (LPSA).

  18. Effects of iron and manganese on the formation of HAAs upon chlorinating Chlorella vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Fei, E-mail: gefei@xtu.edu.cn [Department of Environmental Science and Engineering, Xiangtan University, Egongtang Road, Xiangtan, Hunan 411105 (China); Wu, Xiuzhen; Wang, Na; Zhu, Runliang; Wang, Tong; Xu, Yin [Department of Environmental Science and Engineering, Xiangtan University, Egongtang Road, Xiangtan, Hunan 411105 (China)

    2011-05-15

    The major objective of the present study was to investigate the role of iron and manganese on the formation of haloacetic acids (HAAs) when algae are chlorinated at different pHs. The results showed that both iron and manganese can reduce the yields of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) on chlorinating green alga Chlorella vulgaris (C. vulgaris) at a pH range of 6.0-9.0, and the decline of DCAA and TCAA was shown to be more significant at the low pH range. At pH 6.0, DCAA and TCAA yields decreased by 44.5% and 57.3%, respectively with the addition of 0.5 mg L{sup -1} iron, and decreased 39.5% and 49.4%, respectively with the addition of 0.5 mg L{sup -1} manganese. The main reason for decreasing the yields of HAAs as shown by scanning electron microscope (SEM) is that Fe(OH){sub 3(am)} or MnO{sub 2(am)} coat the algal cells{sub ,} which then improves their agglomeration of algal cells which is also revealed by the laser particle size analysis (LPSA).

  19. Removal of iron and manganese using granular activated carbon and zeolite in artificial barrier of riverbank filtration

    Science.gov (United States)

    Ismail, Abustan; Harmuni, Halim; Mohd, Remy Rozainy M. A. Z.

    2017-04-01

    Iron and Manganese was examined from riverbank filtration (RBF) and river water in Sungai Kerian, Lubok Buntar, Serdang Kedah. Water from the RBF was influenced by geochemical and hydro chemical processes in the aquifer that made concentrations of iron (Fe), and manganese (Mn) high, and exceeded the standard values set by the Malaysia Ministry of Health. Therefore, in order to overcome the problem, the artificial barrier was proposed to improve the performance of the RBF. In this study, the capability and performance of granular activated carbon, zeolite and sand were investigated in this research. The effects of dosage, shaking speed, pH and contact time on removal of iron and manganese were studied to determine the best performance. For the removal of iron using granular activated carbon (GAC) and zeolite, the optimum contact time was at 2 hours with 200rpm shaking speed with 5g and 10g at pH 5 with percentage removal of iron was 87.81% and 83.20% respectively. The removal of manganese and zeolite arose sharply in 75 minutes with 90.21% removal, with 100rpm shaking speed. The GAC gave the best performance with 99.39% removal of manganese. The highest removal of manganese was achieved when the adsorbent dosage increased to 10g with shaking speed of 200rpm.

  20. Simultaneous removal of iron and manganese of aqueous solutions using as adsorbent a Mexican natural zeolite

    International Nuclear Information System (INIS)

    Garcia M, A.; Solache R, M. J.; Olguin G, M. T.

    2009-01-01

    In this work was evaluated the removal capacity of iron and manganese of aqueous solutions using a Mexican natural zeolite. It was observed that the Freundlich pattern describes the adsorption process appropriately and that a competitive effect exists between both metals by the exchange places of the zeolite, when it is starting of solutions that contain to both metals, impacting mainly in the manganese removal. A natural zeolite coming from the Puebla State, Mexico was used. The material was milled and sieved to a mesh size 30 and was conditioned with a solution 0.5 N of sodium chloride. Later on was characterized by means of scanning electron microscopy and X-ray diffraction.

  1. Removal of iron and manganese by artificial destratification in a tropical climate (Upper Layang Reservoir, Malaysia).

    Science.gov (United States)

    Ismail, R; Kassim, M A; Inman, M; Baharim, N H; Azman, S

    2002-01-01

    Environmental monitoring was carried out at Upper Layang Reservoir situated in Masai, Johor, Malaysia. The study shows that thermal stratification and natural mixing of the water column do exist in the reservoir and the level of stratification varies at different times of the year. Artificial destratification via diffused air aeration techniques was employed at the reservoir for two months. The results show that thermal stratification was eliminated after a week of continuous aeration. The concentrations of iron and to a lesser extent manganese in the water column was also reduced during the aeration period.

  2. Control of manganese and iron in Skagerrak sediments (northeastern North Sea)

    Digital Repository Service at National Institute of Oceanography (India)

    Rajendran, A.; DileepKumar, M.; Bakker, J.F.

    - 80. I00 E E 40" "I- l-- n 6Or hl 80" ioo (a) MANGANESE ( mmo\\[. kg ''1 ) ,? 2,0 3p ~, A ,o =o 40" 6O" I00 B (b) IRON (mmol. kg '-I ) 4o 6o- 8O" IO( ~o,oo ,ooo i I I 590 I A o 20- . 40" 60" ,J o 2o 40" 60" 80- IOO... in these sediments, expressed as change in concentration with time on a volume basis of sediments or pore water \\[see Berner (1980) for a discussion \\], the steady-state equations of Burdige and Gieskes (1983) have been used. These are, ( 1 ) oxic zone...

  3. Effect of molybdenum, vanadium, boron on mechanical properties of high chromium white cast iron in as-cast condition

    Science.gov (United States)

    Nurjaman, F.; Sumardi, S.; Shofi, A.; Aryati, M.; Suharno, B.

    2016-02-01

    In this experiment, the effect of the addition carbide forming elements on high chromium white cast iron, such as molybdenum, vanadium and boron on its mechanical properties and microstructure was investigated. The high chromium white cast iron was produced by casting process and formed in 50 mm size of grinding balls with several compositions. Characterization of these grinding balls was conducted by using some testing methods, such as: chemical and microstructure analysis, hardness, and impact test. From the results, the addition of molybdenum, vanadium, and boron on high chromium white cast iron provided a significant improvement on its hardness, but reduced its toughness. Molybdenum induced fully austenitic matrix and Mo2C formation among eutectic M7C3 carbide. Vanadium was dissolved in the matrix and carbide. While boron was played a role to form fine eutectic carbide. Grinding balls with 1.89 C-13.1 Cr-1.32 Mo-1.36 V-0.00051 B in as-cast condition had the highest hardness, which was caused by finer structure of eutectic carbide, needle like structure (upper bainite) matrix, and martensite on its carbide boundary.

  4. Effects of Exogenous Gibberellic Acid3 on Iron and Manganese Plaque Amounts and Iron and Manganese Uptake in Rice

    Science.gov (United States)

    Guo, Yue; Zhu, Changhua; Gan, Lijun; Ng, Denny; Xia, Kai

    2015-01-01

    Gibberellins (GA) regulate various components of plant development. Iron and Mn plaque result from oxiding and hydroxiding Fe and Mn, respectively, on the roots of aquatic plant species such as rice (Oryza sativa L.). In this study, we found that exogenous gibberellic acid3 (GA3) spray decreased Fe plaque, but increased Mn plaque, with applications of Kimura B nutrient solution. Similar effects from GA3, leading to reduced Fe plaque and increased Mn plaque, were also found by scanning electron microscopy and energy dispersive X-ray spectrometric microanalysis. Reduced Fe plaque was observed after applying GA3 to the groups containing added Fe2+ (17 and 42 mg•L-1) and an increasing trend was detected in Mn plaques of the Mn2+ (34 and 84 mg•L-1) added treatments. In contrast, an inhibitor of GA3, uniconazole, reversed the effects of GA3. The uptake of Fe or Mn in rice plants was enhanced after GA3 application and Fe or Mn plaque production. Strong synergetic effects of GA3 application on Fe plaque production were detected. However, no synergetic effects on Mn plaque production were detected. PMID:25710173

  5. Effect of Iron Impurity on the Phase Composition, Structure and Properties of Magnesium Alloys Containing Manganese and Aluminum

    Science.gov (United States)

    Volkova, E. F.

    2017-07-01

    Results of a study of the interaction between iron impurity and manganese and aluminum alloying elements during formation of phase composition in alloys of the Mg - Mn, Mg - Al, Mg - Al - Mn, and Mg - Al - Zn - Mn systems are presented. It is proved that this interaction results in introduction of Fe into the intermetallic phase. The phase compositions of model magnesium alloys and commercial alloys MA2-1 and MA5 are studied. It is shown that both manganese and aluminum may bind the iron impurity into phases. Composite Fe-containing intermetallic phases of different compositions influence differently the corrosion resistance of magnesium alloys.

  6. Redox speciation of particulate iron and manganese during river/ocean mixing

    International Nuclear Information System (INIS)

    Zaw, M.; Szymczak, R.; Payne, T.

    2000-01-01

    Full text: A synchrotron radiation experiment was performed at the Australian National Beamline Facility (Photon Factory, Tsukuba, Japan) to investigate changes in the physico-chemical nature of particles during estuarine mixing. X-ray absorption near edge structure spectra (XANES) analysis was used to determine solid-state redox speciation of iron and manganese throughout the river/ocean salinity transects. Particles (>0.4μm) collected using clean techniques were stored under nitrogen during TROPICS Project expeditions to the Fly and Sepik Rivers, PNG. Results indicated that initially, particulate manganese was mostly present as Mn(IV) and Mn(III) compounds with some surface-adsorbed Mn(II). Similarly, iron was present as particulate Fe(III) and Fe(II/III) compounds with some adsorbed Fe(II). During river-ocean mixing, the proportions of both Mn(II) and Fe(III) significantly increased. These observations maybe due to increasing photochemical activity in the river plume, surface-sorption of reduced species related to the estuarine residence time of particles, or enhanced scavenging of ocean-sourced elements. Copyright (2000) American Chemical Society

  7. Evaluation of chromium, nickel, iron and manganese content in wheat, flour, bran and selected baked products

    Directory of Open Access Journals (Sweden)

    Bawiec Piotr

    2014-06-01

    Full Text Available Considering the nutritional values, breadstuff plays a big part in covering human nourishment needs and constitutes a base of all day diet. Moreover, bread is an excellent source of numerous vitamins and minerals the abundance of which depends on the degree of grinding. Thus, it seems to be very important to know the composition and level of bio-elements. That is why the main target of this study was to evaluate the concentration of selected trace elements: chromium (Cr, nickel (Ni, iron (Fe and manganese (Mn in wheat grain, wheat bran, different wheat and rye flour types and variety of breadstuff also with addition of grains and seeds from different bakeries and mills. Another task was to analyze if the technological process has an influence on secondary despoil of bread goods with heavy metal elements. The analyzed trace elements were measured with a precise and accurate atomic absorption spectrophotometric method (AAS and the results were expressed in mg/kg of selected sample. Obtained results show that bread and grain products are a good source of trace elements like chromium, nickel, iron and manganese. However, the higher levels of chromium and nickel in bread goods could rather be an effect of impurity caused by a technological process in mill and bakeries.

  8. Multimicronutrient Slow-Release Fertilizer of Zinc, Iron, Manganese, and Copper

    Directory of Open Access Journals (Sweden)

    Siladitya Bandyopadhyay

    2014-01-01

    Full Text Available The process for the production of a slow-release micronutrient fertilizer is described. The compound contains zinc, iron, manganese, and copper as micronutrients and is produced by polymerizing a system containing phosphoric acid, zinc oxide, hematite, pyrolusite, copper sulfate, and magnesium oxide followed by neutralization of the polyphosphate chain with ammonium hydroxide. Changes in temperature, density, and viscosity of the reaction system during polymerization were studied. Reaction kinetics was studied at three different temperatures. Rate curves revealed a multistage process with essentially linear rates at each stage. Thus, each stage displayed zero order kinetics. The product was crystalline and revealed ordering of P-O-P chains. It had low solubility in water but high solubility in 0.33 M citric acid and 0.005 M DTPA. Three different field trials showed significant yield increments using the slow-release micronutrient fertilizer compared to the conventional micronutrients. Yield increments in rice were in the range of 10–55% over control (with no micronutrient and up to 17% over the conventional micronutrient fertilizers. There were significant increases in total uptake of zinc, iron, and manganese in the grain. Slow-release fertilizers also produced significant yield increases in potato as well as significant increase in vitamin C content of the tuber.

  9. Pilot scale evaluation of biological and pressure clarification processes for the removal of high level of iron and manganese

    Energy Technology Data Exchange (ETDEWEB)

    Yannoni, C.C.; Kinsley, B.P. [Fay, Spofford & Thorndike, Inc., Burlington, MA (United States); Marston, T.R. [Connecticut Water Company, Clinton, CT (United States)

    1996-11-01

    Iron and manganese originating from groundwater supplies have a long history of causing consumer complaints in water distribution systems. Although iron and manganese are not public health concerns, they are a major concern from an aesthetic standpoint. The elevated awareness of consumers in regard to the quality of drinking water, an increase in regulations requiring additional treatment and the cost associated with developing new sources of supply, has required many utilities to implement improvements to existing facilities. Historical water quality data collected from the Connecticut Water Company`s (CWC) Westbrook Well revealed an increasing trend in iron and manganese concentrations. As a result, the existing greensand filtration facility located at the well, provides insufficient removal rates and inefficient operating cycles. Variations in operating procedures were not successful in correcting these problems. A water treatment feasibility study recommended evaluation of biological and pressure clarification processes to reduce iron (9 mg/l) and manganese (1.5 mg/l) levels below the secondary maximum contaminant levels of 0.30 and 0.05 mg/l, respectively. Assessment of these processes was accomplished through the construction and operation of a 5 gallon per minute (gpm) capacity pilot plant at the Westbrook Water Treatment Plant. Application of biological treatment for iron removal was then piloted on the existing full-scale treatment facility.

  10. Correlation between airborne manganese concentration at the workstations in the iron foundry and manganese concentration in workers’ blood

    Directory of Open Access Journals (Sweden)

    Seyedtaghi Mirmohammadi

    2017-08-01

    Full Text Available Background: Manganese (Mn used as raw material for melting process in the ferrous foundry is considered as hazardous neurotoxic substance because it accumulates in the central nervous system and may cause neurological disorders. The furnace-men and melting department workers are potentially exposed to manganese particles or fume in the workplace. The objective of the research has been to investigate the sources and levels of manganese exposure in the foundry by correlation of blood-manganese (B-Mn and air-manganese (air-Mn measurement. Material and Methods: Air-Mn and Mn of blood serum were measured involving workers who worked in a big-sized foundry during 1 year. The standard method of the Occupational Safety and Health Administration (OSHA ID-121 was used for air and blood assessment and atomic absorption spectroscopy (AAS was carried out for air and blood sample analysis. Results: The air sampling results have revealed that there is a high exposure to manganese (4.5 mg/m3 in the workplace as compared to the National Institute for Occupational Safety and Health’s (NIOSH time weighted average (the reference time-weighted average (TWA = 1 mg/m3. The average blood serum Mn concentration was 2.745 μg/l for subjects working for shorter than 3 months and 274.85 μg/l for subjects working 3–12 months. Conclusions: Against the research hypothesis there was no correlation between the air-Mn concentration and the B-Mn (serum level of manganese in the serum of the exposed subjects. It may be due to short time of air sampling of manganese airborne particles, and a real-time monitoring of airborne manganese particles is suggested for any future study. Med Pr 2017;68(4:449–458

  11. Bacterial Disproportionation of Elemental Sulfur Coupled to Chemical Reduction of Iron or Manganese

    Science.gov (United States)

    Thamdrup, Bo; Finster, Kai; Hansen, Jens Würgler; Bak, Friedhelm

    1993-01-01

    A new chemolithotrophic bacterial metabolism was discovered in anaerobic marine enrichment cultures. Cultures in defined medium with elemental sulfur (S0) and amorphous ferric hydroxide (FeOOH) as sole substrates showed intense formation of sulfate. Furthermore, precipitation of ferrous sulfide and pyrite was observed. The transformations were accompanied by growth of slightly curved, rod-shaped bacteria. The quantification of the products revealed that S0 was microbially disproportionated to sulfate and sulfide, as follows: 4S0 + 4H2O → SO42- + 3H2S + 2H+. Subsequent chemical reactions between the formed sulfide and the added FeOOH led to the observed precipitation of iron sulfides. Sulfate and iron sulfides were also produced when FeOOH was replaced by FeCO3. Further enrichment with manganese oxide, MnO2, instead of FeOOH yielded stable cultures which formed sulfate during concomitant reduction of MnO2 to Mn2+. Growth of small rod-shaped bacteria was observed. When incubated without MnO2, the culture did not grow but produced small amounts of SO42- and H2S at a ratio of 1:3, indicating again a disproportionation of S0. The observed microbial disproportionation of S0 only proceeds significantly in the presence of sulfide-scavenging agents such as iron and manganese compounds. The population density of bacteria capable of S0 disproportionation in the presence of FeOOH or MnO2 was high, > 104 cm-3 in coastal sediments. The metabolism offers an explanation for recent observations of anaerobic sulfide oxidation to sulfate in anoxic sediments. PMID:16348835

  12. Study of granitic biotites by X-ray fluorescence analysis: determination of iron, manganese, titanium, calcium, potassium, silicon and aluminium

    International Nuclear Information System (INIS)

    Toubes, R. O.; Bermudez Polonio, J.

    1968-01-01

    A method for the quantitative determination of iron, manganese, titanium, calcium potassium, silicon, and aluminium, is reported, Sample preparation is carried out by the miniature flux technique, and rubidium is used as internal standard for silicon and aluminium. (Author) 5 refs

  13. Bio-inspired iron and manganese complexes derived from mixed N,O ligands for the oxidation of olefins

    NARCIS (Netherlands)

    Moelands, M.A.H.

    2014-01-01

    This Thesis describes the synthesis and structural analysis of bio-inspired iron and manganese complexes used for the catalytic oxidation of olefin substrates. The development of catalytic systems for oxidation chemistry that are based on first row transition metals and that apply a green oxidant

  14. The synthesis, structures and characterisation of new mixed-ligand manganese and iron complexes with tripodal, tetradentate ligands

    NARCIS (Netherlands)

    van Gorkum, R.; Berding, J.; Mills, A.M.; Kooijman, H.; Tooke, D.M.; Spek, A.L.; Mutikainen, I.; Turpeinen, U.; Reedijk, J.; Bouwman, E.

    2008-01-01

    The preparation of new manganese and iron complexes with the general formula [M(tripod)(anion)] is described, where M = FeIII or MnIII, “tripod” is a dianionic tetradentate tripodal ligand and the anion is a chelating β-diketonate, 8-oxyquinoline or acetate. The synthesis of this type of complexes

  15. Iron and manganese shuttles control the formation of authigenic phosphorus minerals in the euxinic basins of the Baltic Sea

    NARCIS (Netherlands)

    Jilbert, T.|info:eu-repo/dai/nl/304835714; Slomp, C.P.|info:eu-repo/dai/nl/159424003

    2013-01-01

    Microanalysis of epoxy resin-embedded sediments is used to demonstrate the presence of authigenic iron (Fe) (II) phosphates and manganese (Mn)-calcium (Ca)-carbonate-phosphates in the deep euxinic basins of the Baltic Sea. These minerals constitute major burial phases of phosphorus (P) in this area,

  16. The iron-regulated transporter 1 plays an essential role in uptake, translocation and grain-loading of manganese, but not iron, in barley

    DEFF Research Database (Denmark)

    Long, Lizhi; Persson, Daniel Olaf; Duan, Fengying

    2018-01-01

    Transporters involved in manganese (Mn) uptake and intracellular Mn homeostasis in Arabidopsis and rice are well characterized, while much less is known for barley, which is particularly prone to Mn deficiency. In this study we have investigated the role of the iron-regulated transporter 1 (IRT1...

  17. Removal of Iron and Manganese from Natural Groundwater by Continuous Reactor Using Activated and Natural Mordenite Mineral Adsorption

    Science.gov (United States)

    Zevi, Y.; Dewita, S.; Aghasa, A.; Dwinandha, D.

    2018-01-01

    Mordenite minerals derived from Sukabumi natural green stone founded in Indonesia was tested in order to remove iron and manganese from natural groundwater. This research used two types of adsorbents which were consisted of physically activated and natural mordenite. Physical activation of the mordenite was carried out by heating at 400-600°C for two hours. Batch system experiments was also conducted as a preliminary experiment. Batch system proved that both activated and natural mordenite minerals were capable of reducing iron and manganese concentration from natural groundwater. Then, continuous experiment was conducted using down-flow system with 45 ml/minute of constant flow rate. The iron & manganese removal efficiency using continuous reactor for physically activated and natural mordenite were 1.38-1.99%/minute & 0.8-1.49%/minute and 2.26%/minute & 1.37-2.26%/minute respectively. In addition, the regeneration treatment using NH4Cl solution managed to improve the removal efficiency of iron & manganese to 1.98%/minute & 1.77-1.90%/minute and 2.25%/minute & 2.02-2.21%/minute on physically activated mordenite and natural mordenite respectively. Subsequently, the activation of the new mordenite was carried out by immersing mordenite in NH4Cl solution. This chemical activation showed 2.42-2.75%/minute & 0.96 - 2.67 %/minute and 2.66 - 2.78 %/minute & 1.34 - 2.32 %/minute of iron & manganese removal efficiency per detention time for chemically activated and natural mordenite respectively.

  18. The quality of Metroxylon Sago sucker: morphology and uptake of manganese and iron

    International Nuclear Information System (INIS)

    Nashriyah Mat; Abdul Khalik Wood; Ramli Ishak

    2001-01-01

    Metroxylon sago or sagopalm is an important source of carbohydrate for the South East Asian countries, apart from rice. In Malaysia, wild sagopalm grows in Sarawak in its natural habitats, the coastal peat swamp. The quality of sucker growing vegetatively on sagopalm was studied at Sungai Talau experimental station, Dalat plantation and Oya/Mukah plantation in Sarawak. The coefficients of variability (C) and Index of similiarity (I) were calculated based on sucker morphology and uptake of manganese and iron, The matrix of hypothetical exact interpoint distances (Indices of Similarity and Dissimilarity) shows that sucker on matured sagopalm at Sungai Talam experimental station was a high quality, sucker on 5 years old sagopalm at Mukah sago plantation was approximately one-third as good, whereas sucker on 1.5 years old sagopalm at Oya/dalat sago plantation was of inferior quality. (Author)

  19. Acrylate intercalation and in situ polymerization in iron-, cobalt-, or manganese-substituted nickel hydroxides.

    Science.gov (United States)

    Vaysse, C; Guerlou-Demourgues, L; Duguet, E; Delmas, C

    2003-07-28

    A chimie douce route based on successive redox and exchange reactions has allowed us to prepare new hybrid organic-inorganic materials, composed of polyacrylate macromolecules intercalated into layered double hydroxides (LDHs), deriving from Ni(OH)(2). Monomer intercalation and in situ polymerization mechanisms have appeared to be strongly dependent upon the nature of the substituting cation in the slabs. In the case of iron-based LDHs, a phase containing acrylate monomeric intercalates has been isolated and identified by X-ray diffraction and infrared spectroscopy. Second, interslab free-radical polymerization of acrylate anions has been successfully initiated using potassium persulfate. In cobalt- or manganese-based LDHs, one-step polymerization has been observed, leading directly to a material containing polyacrylate intercalate.

  20. Acute Toxicity and Accumulation of Iron, Manganese and, Aluminum in Caspian Kutum Fish (Rutilus kutum

    Directory of Open Access Journals (Sweden)

    Saeed Zahedi

    2014-03-01

    Full Text Available Background: Iron, manganese, and aluminum are three abundant metals on earth and their concentrations have increased in aquatic environments as a result of natural and industrial activities. This study was undertaken to report the median acute toxicity (LC50 and accumulation of the sub-lethal concentration (10% 96-h LC50 of iron (Fe, manganese (Mn and aluminum (Al in kutum (Rutilus kutum fingerlings. Methods: For the 96-h LC50, the fish were exposed to concentrations of 105, 111, 117, 123, 129 and 135 mg/l of Fe and 40, 45, 50, 55, 60, and 65 mg/l of Mn and 18, 22, 26, 30, 34 and 38 mg/l of aluminum for 4 days. For sublethal exposure, they were exposed to mediums with concentrations of 12.3, 5.4 and 2.9 for Fe, Mn, and aluminum, respectively. Metal concentrations were determined by atomic absorption spectrophotometry in the gill tissues. Results: Probit analysis showed the 96-h LC50 values of 122.98, 54.39, and 28.89 mg/l for Fe, Mn, and aluminum, respectively. Sub-lethal tests were conducted with nominal concentrations of 12.3, 5.4, and 2.9 mg/l of Fe, Mn, and aluminum for four days, respectively. Significant accumulations were observed in gills for all tested metals as compared to the control groups in short-term exposure (P<0.05. Conclusion: Obtained results clearly show that aluminum is the most toxic metal among tested ones for kutum fingerlings and it has the highest branchial AF value during sub-lethal exposure.

  1. Integrated pyrolucite fluidized bed-membrane hybrid process for improved iron and manganese control in drinking water.

    Science.gov (United States)

    Dashtban Kenari, Seyedeh Laleh; Barbeau, Benoit

    2017-04-15

    Newly developed ceramic membrane technologies offer numerous advantages over the conventional polymeric membranes. This work proposes a new configuration, an integrated pyrolucite fluidized bed (PFB)-ceramic MF/UF hybrid process, for improved iron and manganese control in drinking water. A pilot-scale study was undertaken to evaluate the performance of this process with respect to iron and manganese control as well as membrane fouling. In addition, the fouling of commercially available ceramic membranes in conventional preoxidation-MF/UF process was compared with the hybrid process configuration. In this regard, a series of experiments were conducted under different influent water quality and operating conditions. Fouling mechanisms and reversibility were analyzed using blocking law and resistance-in-series models. The results evidenced that the flux rate and the concentration of calcium and humic acids in the feed water have a substantial impact on the filtration behavior of both membranes. The model for constant flux compressible cake formation well described the rise in transmembrane pressure. The compressibility of the filter cake substantially increased in the presence of 2 mg/L humic acids. The presence of calcium ions caused significant aggregation of manganese dioxide and humic acid which severely impacted the extent of membrane fouling. The PFB pretreatment properly alleviated membrane fouling by removing more than 75% and 95% of iron and manganese, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Evaluation of trends for iron and manganese concentrations in wells, reservoirs, and water distribution networks, Qom city, Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Fahiminia

    2015-06-01

    Full Text Available Background: This study aimed to evaluated trends for iron and manganese concentrations in wells, reservoirs, and water distribution networks in Qom city during the summer of 2012. Methods: This was a cross-sectional study. The studied scopes consisted of groundwater (60 wells, reservoirs (10 tanks, and water distribution network (33 points. One sample was taken from each source monthly. Statistical tests used included post hoc tests (Tukey HSD. Finally, the results were compared with drinking water standards. Results: The average concentrations of iron in groundwater, reservoirs, and distribution networks were 0.09, 0.07, and 0.07 mg/l, respectively. The average concentrations of manganese in groundwater, reservoirs, and distribution networks were 0.15, 0.09, and 0.1 mg/l, respectively. The turbidity averages in groundwater, reservoirs, and distribution networks were 0.58, 0.6, and 0.52 NTU, respectively. The average concentrations of free chlorine residual in water reservoirs and distribution networks were 1.74 and 1.06 mg/l, respectively. The pH averages in groundwater, reservoirs, and distribution networks were 7.4, 7.7, and 7.5, respectively. The amounts of iron, manganese, turbidity, free chlorine residual, and pH in the investigated resources had no significant differences (P > 0.05. Conclusion: The amounts of iron, manganese, turbidity, free chlorine residual and pH in groundwater, reservoirs, and water distribution networks of Qom are within permissible limits of national standards and EPA guidelines. Only the amount of manganese was higher than the Environmental Protection Agency (EPA permissible limit.

  3. Molybdenum extraction from copper-molybdenum ores

    International Nuclear Information System (INIS)

    Nevaeva, L.M.

    1982-01-01

    Molybdenum extraction from copper-molybdenum ores as practised in different countries is reviewed. In world practice the production process including depression of copper and iron sulfides and flotation of molybdenite is widely spread. At two USA factories the process of a selective flotation with molybdenite depression by dextrin is used

  4. Chemical and mineralogical characterization of silicon manganese iron slag as railway ballast

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Ralph Werner Heringer; Barreto, Rairane Aparecida, E-mail: ralph@em.ufop.br, E-mail: rairanebarreto@hotmail.com [Universidade Federal de Ouro Preto (UFOP), MG (Brazil); Fernandes, Gilberto, E-mail: gilberto@unicerp.edu.br [Centro Universitário do Cerrado Patrocínio (UNICERP), Patrocínio, MG (Brazil); Sousa, Fabiano Carvalho, E-mail: fabiano.carvalho.sousa@vale.com [Vale, Belo Horizonte, MG (Brazil)

    2017-10-15

    In nature, metal ores such as iron, lead, aluminum and others are found in an impure state, sometimes oxidized and mixed with silicates of other metals. During casting, when the ore is exposed to high temperatures, these impurities are separated from the molten metal and can be removed. The mass formed by these compounds is slag. Slag is the co-product of the smelting of ore to purify metals. It may be considered a mixture of metal oxides, but may also contain metal sulphites and metal atoms in their elemental form. After it is reprocessed to separate the metals contained, the co-products of this process can be used in cement, rail ballast, road paving and various other purposes. The objective of this research work is the presentation of the chemical and mineralogical characterization tests of the silicon-manganese iron slag with the purpose of reusing the coproduct as rail ballast. X-ray diffraction tests, quantitative chemical analyzes, scanning electron microscopy and free lime content were prepared for these characterizations. The results of these tests showed the technical feasibility of using slag as rail ballast. (author)

  5. Chemical and mineralogical characterization of silicon manganese iron slag as railway ballast

    International Nuclear Information System (INIS)

    Oliveira, Ralph Werner Heringer; Barreto, Rairane Aparecida; Fernandes, Gilberto; Sousa, Fabiano Carvalho

    2017-01-01

    In nature, metal ores such as iron, lead, aluminum and others are found in an impure state, sometimes oxidized and mixed with silicates of other metals. During casting, when the ore is exposed to high temperatures, these impurities are separated from the molten metal and can be removed. The mass formed by these compounds is slag. Slag is the co-product of the smelting of ore to purify metals. It may be considered a mixture of metal oxides, but may also contain metal sulphites and metal atoms in their elemental form. After it is reprocessed to separate the metals contained, the co-products of this process can be used in cement, rail ballast, road paving and various other purposes. The objective of this research work is the presentation of the chemical and mineralogical characterization tests of the silicon-manganese iron slag with the purpose of reusing the coproduct as rail ballast. X-ray diffraction tests, quantitative chemical analyzes, scanning electron microscopy and free lime content were prepared for these characterizations. The results of these tests showed the technical feasibility of using slag as rail ballast. (author)

  6. Spectroscopic studies of the iron and manganese reconstituted tyrosyl radical in Bacillus cereus ribonucleotide reductase R2 protein.

    Directory of Open Access Journals (Sweden)

    Ane B Tomter

    Full Text Available Ribonucleotide reductase (RNR catalyzes the rate limiting step in DNA synthesis where ribonucleotides are reduced to the corresponding deoxyribonucleotides. Class Ib RNRs consist of two homodimeric subunits: R1E, which houses the active site; and R2F, which contains a metallo cofactor and a tyrosyl radical that initiates the ribonucleotide reduction reaction. We studied the R2F subunit of B. cereus reconstituted with iron or alternatively with manganese ions, then subsequently reacted with molecular oxygen to generate two tyrosyl-radicals. The two similar X-band EPR spectra did not change significantly over 4 to 50 K. From the 285 GHz EPR spectrum of the iron form, a g(1-value of 2.0090 for the tyrosyl radical was extracted. This g(1-value is similar to that observed in class Ia E. coli R2 and class Ib R2Fs with iron-oxygen cluster, suggesting the absence of hydrogen bond to the phenoxyl group. This was confirmed by resonance Raman spectroscopy, where the stretching vibration associated to the radical (C-O, ν(7a = 1500 cm(-1 was found to be insensitive to deuterium-oxide exchange. Additionally, the (18O-sensitive Fe-O-Fe symmetric stretching (483 cm(-1 of the metallo-cofactor was also insensitive to deuterium-oxide exchange indicating no hydrogen bonding to the di-iron-oxygen cluster, and thus, different from mouse R2 with a hydrogen bonded cluster. The HF-EPR spectrum of the manganese reconstituted RNR R2F gave a g(1-value of ∼2.0094. The tyrosyl radical microwave power saturation behavior of the iron-oxygen cluster form was as observed in class Ia R2, with diamagnetic di-ferric cluster ground state, while the properties of the manganese reconstituted form indicated a magnetic ground state of the manganese-cluster. The recent activity measurements (Crona et al., (2011 J Biol Chem 286: 33053-33060 indicates that both the manganese and iron reconstituted RNR R2F could be functional. The manganese form might be very important, as it has 8

  7. Development of low-cost technology for the removal of iron and manganese from ground water in siwa oasis.

    Science.gov (United States)

    El-Naggar, Hesham M

    2010-01-01

    Ground water is the only water resource for Siwa Oasis. It is obtained from natural freshwater wells and springs fed by the Nubian aquifer. Water samples collected from Siwa Oasis had relatively higher iron (Fe) and manganese (Mn) than the permissible limits specified in WHO Guidelines and Egyptian Standards for drinking water quality. Aeration followed by sand filtration is the most commonly used method for the removal of iron from ground water. The study aimed at development of low-cost technology for the removal of iron and manganese from ground water in Siwa Oasis. The study was carried out on Laboratory-scale columns experiments sand filters with variable depths of 15, 30, 45, 60, 75, 90 cm and three graded types of sand were studied. The graded sand (E.S. =0.205 mm, U.C. =3.366, depth of sand = 60 cm and filtration rate = 1.44 m3/m2/hr) was the best type of filter media. Iron and manganese concentrations measured in ground water with aeration only, decreased with an average removal percentage of 16%, 13% respectively. Iron and manganese concentrations after filtration with aeration came down to 0.1123, 0.05 mg/L respectively in all cases from an initial concentration of 1.14, 0.34 mg/L respectively. Advantages of such treatment unit included simplicity, low cost design, and no need for chemical addition. In addition, the only maintenance required was periodic washing of the sand filter or replacement of the sand in order to maintain reasonable flow rate through the system.

  8. Bio-accumulation of copper, zinc, iron and manganese in oyster Saccostrea cucullata, Snail Cerithium rubus and Clam Tellina angulata from the Bombay coast

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnakumari, L.; Nair, V.R; Moraes, C.

    accumulation was high in S. cucullata, manganese in C. rubus and iron in T. angulata. Similarly, copper and zinc in S. cucullata and copper in C. rubus were found occasionally higher than accepted health standards...

  9. Up-gradation of MoO{sub 3} and separation of copper, iron, zinc from roasted molybdenum ore by a leaching process

    Energy Technology Data Exchange (ETDEWEB)

    Jin-Young, Lee; Jyothi Rajesh, Kumar; Ho-Seok, Jeon; Joon-Soo, Kim, E-mail: rajeshkumarphd@rediffmail.com, E-mail: rkumarphd@kigam.re.kr [Extractive Metallurgy Department, Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM) (Korea, Republic of)

    2013-04-15

    The present research paper deals with the oxidation process of molybdenum ore. The main target of the present study is the up-gradation of MoO{sub 3} from roasted molybdenum ore by a leaching process without waste generation. The most important application of hydrometallurgical processing is the leaching process of the ore and it is the primary process to make pure metal from ore. The present investigations optimize the following experimental parameters to improve the concentration of MoO{sub 3} as well as the separation of copper, iron and zinc in roasted molybdenum ore: effect of acid concentration, temperature, pulp density and leaching time were studied systematically. The temperature study was carried out at 550-595 Degree-Sign C for the oxidation process. The XRD result shows that oxidation process of molybdenum ore and SEM pictures were taken for particles before and after the oxidation process at 585 Degree-Sign C for 360 min. (author)

  10. Synthesis of carbon nanotubes by CVD method using iron and molybdenum-based catalysts supported on ceramic matrices

    International Nuclear Information System (INIS)

    Teixeira, Ana Paula de Carvalho

    2010-01-01

    Molybdenum is known for its synergistic effect in the synthesis of carbon nanotubes (CNs) by chemical vapor deposition (CVD method). When added to typical catalysts like iron, nickel, and cobalt, even in small quantities, it is increases the yield of these nanostructures. The presence of Mo also has an influence on the type and number of CN walls formed. Although this effect is widely documented in the literature, there is not yet a consensus about the mechanism of action of molybdenum in catalytic systems. The objective of the present work is to study the influence of molybdenum on the catalytic activity of iron nanoparticle-based catalysts supported on magnesium oxide (Fe/MgO system) in the synthesis of carbon nanotubes by the CVD method. The Mo concentration was systematically varied from null to molar ratio values four times greater than the quantity of Fe, and the obtained material (catalysts and carbon nanotubes) were broadly characterized by different techniques. In order to also study the influence of the preparation method on the final composition of the catalytic system phases, the catalytic systems (Fe/MgO e FeMo x /MgO) were synthesized by two different methods: co-precipitation and impregnation. The greatest CN yields were observed for the catalysts prepared by coprecipitation. The difference was attributed to better dispersion of the Fe and Mo phases in the catalyst ceramic matrix. In the precipitation stage, it was observed the formation of layered double hydroxides whose concentration increased with the Mo content up to the ratio of Mo/Fe equal to 0.2. This phase is related to a better distribution of Fe and Mo in this concentration range. Another important characteristic observed is that the ceramic matrix is not inert. It can react both with Fe and Mo and form the iron solid solution in the magnesium oxide and the phases magnesium-ferrite (MgFe 2 0 4 ) and magnesium molybdate (MgMo0 4 ). The MgFe 2 0 4 phase is observed in all catalytic systems

  11. Thermomagnetic identification of manganese and iron minerals present in soils and industrial dusts

    Science.gov (United States)

    Wawer, Małgorzata; Rachwał, Marzena; Jabłońska, Mariola; Krzykawski, Tomasz; Magiera, Tadeusz

    2017-04-01

    Many industries (e.g. metallurgy, power, cement, and coking plants) constitute a sources of industrial dusts containing technogenic magnetic particles (TMP). TMP are mostly iron oxides with ferrimagnetic or antiferromagnetic properties, therefore their presence in dusts, soils and sediments can be easily detected by magnetic susceptibility measurements. TMP, thanks their specific mineral and magnetic properties, and well developed specific surface area, are characterized by a chemical affinity for some elements like heavy metals. The main objective of this study was identification of manganese and iron (hydro)oxides occurring in industrial dusts and soils being under their deposition for long time period. In principle, Mn and Fe (hydro)oxides present in these samples originate from high-temperature technological processes. Soils samples (collected from different soil horizons) taken from surroundings of power station, iron/steel and non-ferrous plants as well as metallurgical dusts and fly ashes from power stations were subjected to investigation. During the studies temperature dependent magnetic susceptibility measurements and X-ray powder diffraction analyses were applied. Thermomagnetic analyses (K-T) revealed differences between samples from particular industries, however an inflexion at 450-500°C of all curves was observed indicating a probable occurrence of maghemite- or titanomagnetite-like phases. The curves of TMP emitted by power plants have inflection at 580 °C indicating that magnetite was the main magnetic phase. In case of TMP originated from non-ferrous metal smelting additional curve deflection at 130 and 210 °C occurred relating to intermediate titanomagnetite or iron sulfides. X-ray diffraction proved the occurrence of magnetite and maghemite in almost all samples, especially connected with power industry and iron/steel metallurgy. Mineral analysis revealed that kind of industrial process influenced on the dominating mineral forms found in

  12. Evaluation of Iron and Manganese-Coated Pumice Application for the Removal of as(v from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Leila Babaie Far

    2012-12-01

    Full Text Available Arsenic contamination of water has been recognized as a serious environmental issue and there are reports on its epidemiological problems to human health. The objective of this study was to evaluate the performances of iron-coated pumice and manganese-coated pumice as the adsorbents for removing arsenate from aqueous solutions. The effect of various parameters such as adsorbent dose, contact time, pH and initial concentration on removal efficiency of arsenate were evaluated in batch mode. The data obtained from the kinetic studies were analyzed using kinetic models of pseudo-first-order and pseudo-second-order. In addition, two isotherm models of Freundlich and Langmuir were used to fit the experimental data. The results showed that the optimum dosage of iron-coated pumice and manganese-coated pumice for arsenate removal were 40 and 80 g/L whereas the adsorption process reached equilibrium after 80 and 100 min, respectively. The maximum removal efficiency of arsenate using the two adsorbents were both recorded in pH=3 as the removal efficiency gradually declinedfollowing every increase in pH values of the solution. Iron-coated pumice also showed to have high removal efficiency when the initial concentration of arsenate was high while the low concentration of arsenate was efficiently removed by manganese-coated pumice. Moreover, it was depicted that the adsorption kinetics by bothadsorbents followed pseudo-second order equation and the uptake data of arsenate were well fitted with Langmuir isotherm model. Therefore, it could be concluded that iron and manganese-coated pumice could beconsidered as suitable adsorbents for arsenate removal from aqueous solutions.

  13. 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

  14. Charge state mapping of mixed valent iron and manganese mineral particles using Scanning Transmission X-ray Microscopy (STXM)

    International Nuclear Information System (INIS)

    Pecher, K.; Nealson, K.; Kneedler, E.; Rothe, J.; Meigs, G.; Warwick, T.; Tonner, B.

    2000-01-01

    The interfaces between solid mineral particles and water play a crucial role in partitioning and chemical transformation of many inorganic as well as organic pollutants in environmental systems. Among environmentally significant minerals, mixed-valent oxides and hydroxides of iron (e.g. magnetite, green rusts) and manganese (hausmanite, birnessite) have been recognized as particularly strong sorbents for metal ions. In addition, minerals containing Fe(II) have recently been proven to be powerful reductants for a wide range of pollutants. Chemical properties of these minerals strongly depend on the distribution and availability of reactive sites and little is known quantitatively about the nature of these sites. We have investigated the bulk distribution of charge states of manganese (Mn (II, III, IV)) and iron (Fe(II, III)) in single particles of natural manganese nodules and synthetic green rusts using Scanning Transmission X-ray SpectroMicroscopy (STXM). Pixel resolved spectra (XANES) extracted from stacks of images taken at different wave lengths across the metal absorption edge were fitted to total electron yield (TEY) spectra of single valent reference compounds. Two dimensional maps of bulk charge state distributions clearly reveal domains of different oxidation states within single particles of Mn-nodules and green rust precipitates. Changes of oxidation states of iron were followed as a result of reductive transformation of an environmental contaminant (CCl 4 ) using green rust as the only reductant

  15. Determination of the oxidizing capacity of manganese ores.

    Science.gov (United States)

    Prasad, R

    1974-09-01

    An accurate method is described for determining the amount of active oxygen in manganese ores, based on the oxidation-reduction reaction between the ore and arsenic(III) in presence of ammonium molybdate, followed by the back-titration of excess of arsenic(III) with cerium(IV), using osmium tetroxide as catalyst and Disulphine Blue V as indicator. A survey has been made of the applicability of this method to various pyrolusite ores containing less than 0.2% phosphorus. Aluminium(III), copper(II), iron(III), manganese(II), and molybdenum(VI) do not interfere. Up to 30% phosphorus(V) causes no interference.

  16. Growth rates of iron-manganese concretions in the Pacific and Indian oceans

    International Nuclear Information System (INIS)

    Kuznetsov, Yu.V.; Pospelov, Yu.N.

    1978-01-01

    Radiochemical analysis has been used for studying the distribution of 231 Pa, 230 Th, 232 Th, 226 Ra, 234 U, and 238 U isotopes in nineteen iron-manganese concretions. The study has shown a considerable violation of the equilibrium between uranium and daughter isotopes, viz, protactinium-231 and thorium-230. A sharp decrease of the ratios between the 231 Pain concretions made it possible to find the growth rates of 10 concretions from pelagic regions of the Pacific and Indian oceans. The obtained data deviate in narrow limits and amount to (3-6)mm/10 6 years when evaluation is made according to 230 Th decay and (4-7)mm/10 6 years when 231 Pa is used. The presence of Ra excess (as compared with mother isotopes 230 Th) in inner layers of the concretions points to the fact that the growth rates determined by the radium method are raised too high due to radium migration from the surface layers into the depth of the concretion. It is shown that accumulation of 231 Pa and 230 Th in concretions accounts for a small part (less than 25%) of their production from uranium dissolved in the sea water

  17. Substitution of manganese and iron into hydroxyapatite: Core/shell nanoparticles

    International Nuclear Information System (INIS)

    Pon-On, Weeraphat; Meejoo, Siwaporn; Tang, I.-Ming

    2008-01-01

    The bioceramics, hydroxyapatite (HAP), is a material which is biocompatible to the human body and is well suited to be used in hyperthermia applications for the treatment of bone cancer. We investigate the substitution of iron and manganese into the hydroxyapatite to yield ceramics having the empirical formula Ca 9.4 Fe 0.4 Mn 0.2 (PO 4 ) 6 (OH) 2 . The samples were prepared by the co-precipitation method. The formation of the nanocrystallites in the HAP structure as the heating temperatures were raised to obtain a glass-ceramic system are confirmed by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and electron spin resonance (ESR). TEM images show the core/shell structure of the nanoparticles, with the core being formed by the ferrites and the shell by the hydroxyapatite. The ED patterns indicate the nanoparticles formed at 500 deg. C have an amorphous structure while the nanoparticles formed at 1000 deg. C are crystalline. ESR spectroscopy indicated that the Fe 3+ ions have a g-factor of 4.23 and the Mn 2+ ions have a g-factor of 2.01. The values of the parameters in the spin Hamiltonian which describes the interaction between the transition metal ions and the Ca 2+ ions, indicate that the Mn 2+ ion substitute into the Ca 2+ sites which are ninefold coordinated, i.e., the Ca(1) sites

  18. Development and Evaluation of a Manganese and Iron Food Frequency Questionnaire for Pediatrics.

    Science.gov (United States)

    Zipkin, Frida B; Falciglia, Grace A; Kuhnell, Pierce; Haynes, Erin N

    2017-09-14

    Manganese (Mn) is an essential nutrient, but overexposure can lead to neurotoxicity. Given the essentiality of Mn in the diet, particularly during children's growth and development, it is imperative to quantify dietary Mn intake in populations that may be exposed to industrial sources of Mn. Dietary absorption of Mn is inversely associated with iron (Fe) stores, yet there is currently no food frequency questionnaire (FFQ) to assess dietary Mn and Fe intake. The study objective was to develop and evaluate the validity of a FFQ to measure dietary Mn and Fe intake in pediatrics by comparing the estimated intakes of Mn and Fe with biomarkers: Mn in blood and hair and Fe in serum. This study utilized a subset of the Communities Actively Researching Exposure Study (CARES) population residing in Guernsey County, Ohio. Dietary Mn was not correlated with either blood or hair Mn; however, dietary Mn and serum ferritin were significantly correlated, with a correlation coefficient of 0.51, p < 0.01. Moreover, dietary Fe and serum ferritin were also significantly correlated, with a correlation coefficient of 0.51, p < 0.01. This FFQ is a valid measurement tool for Fe intake as measured by serum ferritin; however, Mn intake did not correlate with either blood or hair Mn.

  19. Bacterial disproportionation of elemental sulfur coupled to chemical reduction of iron or manganese

    DEFF Research Database (Denmark)

    Thamdrup, Bo; Finster, Kai; Hansen, Jens Würgler

    1993-01-01

    and pyrite was observed. The transformations were accompanied by growth of slightly curved, rod-shaped bacteria. The quantification of the products revealed that S was microbially disproportionated to sulfate and sulfide, as follows: 4S + 4H(2)O --> SO(4) + 3H(2)S + 2H. Subsequent chemical reactions between...... reduction of MnO(2) to Mn. Growth of small rod-shaped bacteria was observed. When incubated without MnO(2), the culture did not grow but produced small amounts of SO(4) and H(2)S at a ratio of 1:3, indicating again a disproportionation of S. The observed microbial disproportionation of S only proceeds...... significantly in the presence of sulfide-scavenging agents such as iron and manganese compounds. The population density of bacteria capable of S disproportionation in the presence of FeOOH or MnO(2) was high, > 10 cm in coastal sediments. The metabolism offers an explanation for recent observations of anaerobic...

  20. Concentrations of manganese and iron in some woody and herbs plants

    Directory of Open Access Journals (Sweden)

    Stanković Dragica M.

    2011-01-01

    Full Text Available Heavy metals are the substances that indicate environmental pollution. The plants polluted with heavy metals may endanger natural environment and cause health problems in humans. In our multidisciplinary research of the concentrations of pollutants in forest ecosystems and natural environment in Belgrade, we examined the contents of heavy metals essential for plants but harmful in greater concentrations on a long-term basis. The fact that heavy metals manganese and iron are accumulated in plants to the greatest extent focused our work on determination of the level of concentrations of Mn and Fe in the vegetative parts of 8 plant types on three locations on the Avala Mountain and one location in the centre of the city of Belgrade. The analyses of heavy metals contents in plants were performed by the method of flame atomic absorption spectrophotometry. The examination of the existence of important differences between the average values was performed by implementation of Duncan’s test for the level of significance of 95%. The current contents of heavy metals in plants in the area of the protected natural resource Avala do not represent danger that would presently cause notable damage to forests but show the tendency of the increase of concentrations. Therefore, this issue should be constantly monitored.

  1. Thiosulfate and sulfite distributions in porewater of marine sediments related to manganese, iron, and sulfur geochemistry

    Science.gov (United States)

    Thamdrup, Bo; Finster, Kai; Fossing, Henrik; Hansen, Jens Würgler; Jørgensen, Bo Barker

    1994-01-01

    Depth distributions of thiosulfate (S 2O 32-) and sulfite (SO 32-) were measured in the porewaters of a Danish salt marsh and subtidal marine sediments by HPLC analysis after derivatization with DTNP [2,2'-dithiobis(5-nitropyridine)]. The distributions were compared to the redox zonation as indicated by Eh and Mn 2+, Fe 2+ and H 2S distributions. Concentrations of S 2O 32- varied from below detection (<50 nM) to 600 nM while SO 32- concentrations generally were 2-3 times higher, 100-1500 nM. Depth distributions of the two species were roughly similar. Lowest concentrations were found in the oxidized zone, including both the oxic surface layer and the suboxic zone of intense manganese and iron reduction, and concentrations tended to increase through the suboxic and into the reduced, sulfidic zone. The similarity of SO 32- and S 2O 32- profiles suggested a close coupling of the cycling of the two species. Rates of consumption were suggested as the main factor governing their distribution. Rapid turnover times for S 2O 32- and H 2S of 4 and 1.1 h, respectively, were estimated for the upper 0-1 cm of a subtidal sediment.

  2. Using Iron-Manganese Co-Oxide Filter Film to Remove Ammonium from Surface Water.

    Science.gov (United States)

    Zhang, Ruifeng; Huang, Tinglin; Wen, Gang; Chen, Yongpan; Cao, Xin; Zhang, Beibei

    2017-07-19

    An iron-manganese co-oxide filter film (MeO x ) has been proven to be a good catalyst for the chemical catalytic oxidation of ammonium in groundwater. Compared with groundwater, surface water is generally used more widely and has characteristics that make ammonium removal more difficult. In this study, MeO x was used to remove ammonium from surface water. It indicated that the average ammonium removal efficiency of MeO x was greater than 90%, even though the water quality changed dramatically and the water temperature was reduced to about 6-8 °C. Then, through inactivating microorganisms, it showed that the removal capability of MeO x included both biological (accounted for about 41.05%) and chemical catalytic oxidation and chemical catalytic oxidation (accounted for about 58.95%). The investigation of the characterizations suggested that MeO x was formed by abiotic ways and the main elements on the surface of MeO x were distributed homogenously. The analysis of the catalytic oxidation process indicated that ammonia nitrogen may interact with MeO x as both ammonia molecules and ammonium ions and the active species of O₂ were possibly • O and O₂ - .

  3. Evaluation of iron, zinc, copper, manganese and selenium in oral hospital diets.

    Science.gov (United States)

    Moreira, Daniele C F; de Sá, Júlia S M; Cerqueira, Isabela B; Oliveira, Ana P F; Morgano, Marcelo A; Quintaes, Késia D

    2014-10-01

    Many trace elements are nutrients essential to humans, acting in the metabolism as constituents or as enzymatic co-factors. The iron, zinc, copper, manganese and selenium contents of hospital diets (regular, blend and soft) and of oral food complement (OFC) were determined, evaluating the adequacy of each element in relation to the nutritional recommendations (DRIs) and the percent contribution alone and with OFC. Duplicate samples were taken of six daily meals and of the OFC on two non-consecutive days from a hospital in Belo Horizonte (MG, Brazil) in May and September of 2010 and January of 2011. The elements were determined by ICP OES. Of the diets, the soft diet showed the highest elements content. Offering the OFC was insufficient to provide adequate levels of the trace elements. The oral hospital diets were inadequate in relation to the RDAs for the trace elements studied and the use of the OFCs was insufficient to compensate the values. Copyright © 2013 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  4. Microbial community response reveals underlying mechanism of industrial-scale manganese sand biofilters used for the simultaneous removal of iron, manganese and ammonia from groundwater.

    Science.gov (United States)

    Zhang, Yu; Sun, Rui; Zhou, Aijuan; Zhang, Jiaguang; Luan, Yunbo; Jia, Jianna; Yue, Xiuping; Zhang, Jie

    2018-01-08

    Most studies have employed aeration-biofiltration process for the simultaneous removal of iron, manganese and ammonia in groundwater. However, what's inside the "black box", i.e., the potential contribution of functional microorganisms behavior and interactions have seldom been investigated. Moreover, little attention has been paid to the correlations between environmental variables and functional microorganisms. In this study, the performance of industrial-scale biofilters for the contaminated groundwater treatment was studied. The effluent were all far below the permitted concentration level in the current drinking water standard. Pyrosequencing illustrated that shifts in microbial community structure were observed in the microbial samples from different depths of filter. Microbial networks showed that the microbial community structure in the middle- and deep-layer samples was similar, in which a wide range of manganese-oxidizing bacteria was identified. By contrast, canonical correlation analysis showed that the bacteria capable of ammonia-oxidizing and nitrification was enriched in the upper-layer, i.e., Propionibacterium, Nitrosomonas, Nitrosomonas and Candidatus Nitrotoga. The stable biofilm on the biofilter media, created by certain microorganisms from the groundwater microflora, played a crucial role in the simultaneous removal of the three pollutants.

  5. Biomonitoring for iron, manganese, chromium, aluminum, nickel and cadmium in workers exposed to welding fume: a preliminary study

    Directory of Open Access Journals (Sweden)

    Mulyana

    2015-05-01

    Full Text Available The control of exposure to welding fumes is increasing importance in promoting a healthy, safe and productive work environment. This study is a case-control design, random study was conducted among welder (56 subjects and non welder (39 subjects with more than 1 years experience in the same job task in an automotive parts manufactory within the industrial area at Cikarang in 2013. All subjects were completed physical examination, informed consent and questionnaire. Blood heavy metals were determined by Inductively-Coupled Plasma Mass Spectrometry (ICP-MS. Whole blood iron, manganese, chromium and lead in welder were higher than non-welder, but not different for aluminum, nickel and cadmium. In welder, chromium and manganese correlated with smoking status, cadmium correlated with age and smoking status. In multivariate analysis, wholeblood cadmium correlates with age and smoking status.

  6. Atomic contributions to the valence band photoelectron spectra of metal-free, iron and manganese phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Bidermane, I., E-mail: ieva.bidermane@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box-516, 75120 Uppsala (Sweden); Institut des Nanosciences de Paris, UPMC Univ. Paris 06, CNRS UMR 7588, F-75005 Paris (France); Brumboiu, I.E. [Department of Physics and Astronomy, Uppsala University, Box-516, 75120 Uppsala (Sweden); Totani, R. [Department of Physical and Chemical Sciences, University of L’Aquila, Via Vetoio, Coppito, I-67010 L’Aquila (Italy); Grazioli, C. [CNR-IOM, Laboratorio TASC, ss. 14 km. 163.5, Basovizza, 34149 Trieste (Italy); Departement of Chemical and Pharmaceutical Sciences, University of Trieste (Italy); Shariati-Nilsson, M.N.; Herper, H.C.; Eriksson, O.; Sanyal, B. [Department of Physics and Astronomy, Uppsala University, Box-516, 75120 Uppsala (Sweden); Ressel, B. [University of Nova Gorica, Vipavska Cesta 11c, 5270 Ajdovščina (Slovenia); Simone, M. de [CNR-IOM, Laboratorio TASC, ss. 14 km. 163.5, Basovizza, 34149 Trieste (Italy); Lozzi, L. [Department of Physical and Chemical Sciences, University of L’Aquila, Via Vetoio, Coppito, I-67010 L’Aquila (Italy); Brena, B.; Puglia, C. [Department of Physics and Astronomy, Uppsala University, Box-516, 75120 Uppsala (Sweden)

    2015-11-15

    Highlights: • In detail comparison between the valence band structure of H{sub 2}Pc, FePc and MnPc. • Comparison between the gas phase samples and thin evaporated films on Au (1 1 1). • Detailed analysis of the atomic orbital contributions to the valence band features. • DFT/HSE06 study of the valence band electronic structure of H{sub 2}Pc, FePc and MnPc. - Abstract: The present work reports a photoelectron spectroscopy study of the low-energy region of the valence band of metal-free phthalocyanine (H{sub 2}Pc) compared with those of iron phthalocyanine (FePc) and manganese phthalocyanine (MnPc). We have analysed in detail the atomic orbital composition of the valence band both experimentally, by making use of the variation in photoionization cross-sections with photon energy, and theoretically, by means of density functional theory. The atomic character of the Highest Occupied Molecular Orbital (HOMO), reflected on the outermost valence band binding energy region, is different for MnPc as compared to the other two molecules. The peaks related to the C 2p contributions, result in the HOMO for H{sub 2}Pc and FePc and in the HOMO-1 for MnPc as described by the theoretical predictions, in very good agreement with the experimental results. The DFT simulations, discerning the atomic contribution to the density of states, indicate how the central metal atom interacts with the C and N atoms of the molecule, giving rise to different partial and total density of states for these three Pc molecules.

  7. Control of arsenic mobilization in paddy soils by manganese and iron oxides.

    Science.gov (United States)

    Xu, Xiaowei; Chen, Chuan; Wang, Peng; Kretzschmar, Ruben; Zhao, Fang-Jie

    2017-12-01

    Reductive mobilization of arsenic (As) in paddy soils under flooded conditions is an important reason for the relatively high accumulation of As in rice, posing a risk to food safety and human health. The extent of As mobilization varies widely among paddy soils, but the reasons are not well understood. In this study, we investigated As mobilization in six As-contaminated paddy soils (total As ranging from 73 to 122 mg kg -1 ) in flooded incubation and pot experiments. Arsenic speciation in the solution and solid phases were determined. The magnitude of As mobilization into the porewater varied by > 100 times among the six soils. Porewater As concentration correlated closely with the concentration of oxalate-extractable As, suggesting that As associated with amorphous iron (oxyhydr)oxides represents the potentially mobilizable pool of As under flooded conditions. Soil containing a high level of manganese oxides showed the lowest As mobilization, likely because Mn oxides retard As mobilization by slowing down the drop of redox potential upon soil flooding and maintaining a higher arsenate to arsenite ratio in the solid and solution phases. Additions of a synthetic Mn oxide (hausmannite) to two paddy soils increased arsenite oxidation, decreased As mobilization into the porewater and decreased As concentrations in rice grain and straw. Consistent with previous studies using simplified model systems or pure mineral phases, the present study shows that Mn oxides and amorphous Fe (oxyhydr)oxides are important factors controlling reductive As mobilization in As-contaminated paddy soils. In addition, this study also suggests a potential mitigation strategy using exogenous Mn oxides to decrease As uptake by rice in paddy soils containing low levels of indigenous Mn oxides, although further work is needed to verify its efficacy and possible secondary effects under field conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Influences of iron, manganese, and dissolved organic carbon on the hypolimnetic cycling of amended mercury

    International Nuclear Information System (INIS)

    Chadwick, Shawn P.; Babiarz, Chris L.; Hurley, James P.; Armstrong, David E.

    2006-01-01

    The biogeochemical cycling of iron, manganese, sulfide, and dissolved organic carbon were investigated to provide information on the transport and removal processes that control the bioavailability of isotopic mercury amended to a lake. Lake profiles showed a similar trend of hypolimnetic enrichment of Fe, Mn, DOC, sulfide, and the lake spike ( 202 Hg, purity 90.8%) and ambient of pools of total mercury (HgT) and methylmercury (MeHg). Hypolimnetic enrichment of Fe and Mn indicated that reductive mobilization occurred primarily at the sediment-water interface and that Fe and Mn oxides were abundant within the sediments prior to the onset of anoxia. A strong relationship (r 2 = 0.986, n = 15, p 2 = 0.966, n = 15, p 2 = 0.964, n = 15, p 2 = 0.920, n = 27, p 2 = 0.967, n = 23, p 2 = 0.406, n = 27, p 2 = 0.314, n = 15, p = 0.002) suggest a role of organic matter in Hg transport and cycling. However, a weak relationship between the ambient and lake spike pools of MeHg to DOC indicated that other processes have a major role in controlling the abundance and distribution of MeHg. Our results suggest that Fe and Mn play important roles in the transport and cycling of ambient and spike HgT and MeHg in the hypolimnion, in part through processes linked to the formation and dissolution of organic matter-containing Fe and Mn hydrous oxides particles

  9. Stability Behavior and Thermodynamic States of Iron and Manganese in Sandy Soil Aquifer, Manukan Island, Malaysia

    International Nuclear Information System (INIS)

    Lin, Chin Yik; Abdullah, Mohd. Harun; Musta, Baba; Praveena, Sarva Mangala; Aris, Ahmad Zaharin

    2011-01-01

    A total of 20 soil samples were collected from 10 boreholes constructed in the low lying area, which included ancillary samples taken from the high elevation area. Redox processes were investigated in the soil as well as groundwater in the shallow groundwater aquifer of Manukan Island, Sabah, Malaysia. Groundwater samples (n = 10) from each boreholes were also collected in the low lying area to understand the concentrations and behaviors of Fe and Mn in the dissolved state. This study strives to obtain a general understanding of the stability behaviors on Fe and Mn at the upper unsaturated and the lower-saturated soil horizons in the low lying area of Manukan Island as these elements usually play a major role in the redox chemistry of the shallow groundwater. Thermodynamic calculations using PHREEQC showed that the groundwater samples in the study area are oversaturated with respect to goethite, hematite, Fe(OH) 3 and undersaturated with respect to manganite and pyrochroite. Low concentrations of Fe and Mn in the groundwater might be probably due to the lack of minerals of iron and manganese oxides, which exist in the sandy aquifer. In fact, high organic matters that present in the unsaturated horizon are believed to be responsible for the high Mn content in the soil. It was observed that the soil samples collected from high elevation area (BK) comprises considerable amount of Fe in both unsaturated (6675.87 mg/kg) and saturated horizons (31440.49 mg/kg) compared to the low Fe content in the low lying area. Based on the stability diagram, the groundwater composition lies within the stability field for Mn 2+ and Fe 2+ under suboxic condition and very close to the FeS/Fe 2+ stability boundary. This study also shows that both pH and Eh values comprise a strong negative value thus suggesting that the redox potential is inversely dependent on the changes of pH.

  10. Synthesis by reactive grinding of molybdenum iron bimetallic nitride; Sintesis por molienda reactiva del nitruro bimetalico Mo-Fe: Mo{sub 3}Fe{sub 3}N

    Energy Technology Data Exchange (ETDEWEB)

    Roldan, M. A.; Ortega, A.; Palencia, I.; Real, C.

    2008-07-01

    The transition metal nitride ternary show similar properties to the binary nitride and some times this behaviour are improved. In the present work, the molybdenum-iron nitride has been prepared by reactive grinding form the two metals under nitrogen atmosphere at a pressure of 11 bar. The characterization of the compounds is presented and it is also shown a study of the stability of the nitride under several atmospheres. (Author) 42 refs.

  11. 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)

  12. Manganese: it turns iron into steel (and does so much more)

    Science.gov (United States)

    Cannon, William F.

    2014-01-01

    Manganese is a common ferrous metal with atomic weight of 25 and the chemical symbol Mn. It constitutes roughly 0.1 percent of the Earth’s crust, making it the 12th most abundant element. Its early uses were limited largely to pigments and oxidants in chemical processes and experiments, but the significance of manganese to human societies exploded with the development of modern steelmaking technology in the 1860s. U.S consumption of manganese is about 500,000 metric tons each year, predominantly by the steel industry. Because manganese is essential and irreplaceable in steelmaking and its global mining industry is dominated by just a few nations, it is considered one of the most critical mineral commodities for the United States.

  13. Relating dynamic conditions to the performance of biological rapid sand filters used to remove ammonium, iron, and manganese from drinking water

    DEFF Research Database (Denmark)

    Lee, Carson; Albrechtsen, Hans-Jørgen; Smets, Barth F.

    consistently meeting regulatory guidelines for compounds like ammonium and reduced forms of iron and manganese. These compounds can cause biological instability in the distribution system and can lead to many problems including the growth of pathogens and aesthetic problems (taste, odor, and color...... and media samples were collected throughout the depth of the column and over the operational cycle of the columns. Substrate analysis included ammonium, nitrite, nitrate, iron, and manganese. Qpcr analysis were also performed to quantify ammonium oxidizing bacteria (AOBs), ammonium oxidizing archea ( AOAs...

  14. Grains of Nonferrous and Noble Metals in Iron-Manganese Formations and Igneous Rocks of Submarine Elevations of the Sea of Japan

    Science.gov (United States)

    Kolesnik, O. N.; Astakhova, N. V.

    2018-01-01

    Iron-manganese formations and igneous rocks of submarine elevations in the Sea of Japan contain overlapping mineral phases (grains) with quite identical morphology, localization, and chemical composition. Most of the grains conform to oxides, intermetallic compounds, native elements, sulfides, and sulfates in terms of the set of nonferrous, noble, and certain other metals (Cu, Zn, Sn, Pb, Ni, Mo, Ag, Pd, and Pt). The main conclusion that postvolcanic hydrothermal fluids are the key sources of metals is based upon a comparison of the data of electron microprobe analysis of iron-manganese formations and igneous rocks dredged at the same submarine elevations in the Sea of Japan.

  15. Influence of biofilms on iron and manganese deposition in drinking water distribution systems.

    Science.gov (United States)

    Ginige, Maneesha P; Wylie, Jason; Plumb, Jason

    2011-02-01

    Although health risk due to discoloured water is minimal, such water continues to be the source of one of the major complaints received by most water utilities in Australia. Elevated levels of iron (Fe) and/or manganese (Mn) in bulk water are associated with discoloured water incidents. The accumulation of these two elements in distribution systems is believed to be one of the main causes for such elevated levels. An investigation into the contribution of pipe wall biofilms towards Fe and Mn deposition, and discoloured water events is reported in this study. Eight laboratory-scale reactors were operated to test four different conditions in duplicate. Four reactors were exposed to low Fe (0.05 mg l(-1)) and Mn (0.02 mg l(-1)) concentrations and the remaining four were exposed to a higher (0.3 and 0.4 mg l(-1) for Fe and Mn, respectively) concentration. Two of the four reactors which received low and high Fe and Mn concentrations were chlorinated (3.0 mg l(-1) of chlorine). The biological activity (measured in terms of ATP) on the glass rings in these reactors was very low (∼1.5 ng cm(-2) ring). Higher concentrations of Fe and Mn in bulk water and active biofilms resulted in increased deposition of Fe and Mn on the glass rings. Moreover, with an increase in biological activity, an increase in Fe and Mn deposition was observed. The observations in the laboratory-scale experiments were in line with the results of field observations that were carried out using biofilm monitors. The field data additionally demonstrated the effect of seasons, where increased biofilm activities observed on pipe wall biofilms during late summer and early autumn were found to be associated with increased deposition of Fe and Mn. In contrast, during the cooler months, biofilm activities were a magnitude lower and the deposited metal concentrations were also significantly less (ie a drop of 68% for Fe and 86% for Mn). Based on the laboratory-scale investigations, detachment of pipe wall

  16. Surface chemistry and electrocatalytic behaviour of tetra-carboxy substituted iron, cobalt and manganese phthalocyanine monolayers on gold electrode

    International Nuclear Information System (INIS)

    Mashazi, Philani N.; Westbroek, Philippe; Ozoemena, Kenneth I.; Nyokong, Tebello

    2007-01-01

    Surface chemistry and electrocatalytic properties of self-assembled monolayers of metal tetra-carboxylic acid phthalocyanine complexes with cobalt (Co), iron (Fe) and manganese (Mn) as central metal ions have been studied. These phthalocyanine molecules are immobilized on gold electrode via the coupling reaction between the ring substituents and pre-formed mercaptoethanol self-assembled monolayer (Au-ME SAM). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirmed chemisorption of mercaptoethanol via sulfur group on gold electrode and also coupling reaction between phthalocyanines and Au-ME SAM. Electrochemical parameters of the immobilized molecules show that these molecules are densely packed with a perpendicular orientation. The potential applications of the gold modified electrodes were investigated towards L-cysteine detection and the analysis at phthalocyanine SAMs. Cobalt and iron tetra-carboxylic acid phthalocyanine monolayers showed good oxidation peak for L-cysteine at potentials where metal oxidation (M III /M II ) takes place and this metal oxidation mediates the catalytic oxidation of L-cysteine. Manganese tetra-carboxylic acid phthalocyanine monolayer also exhibited a good catalytic oxidation peak towards L-cysteine at potentials where Mn IV /Mn III redox peak occurs and this redox peak mediates L-cysteine oxidation. The analysis of cysteine at phthalocyanine monolayers displayed good analytical parameters with good detection limits of the orders of 10 -7 mol L -1 and good linearity for a studied concentration range up to 60 μmol L -1

  17. Removal of aluminum, iron and manganese ions from industrial wastes using granular activated carbon and Amberlite IR-120H

    Directory of Open Access Journals (Sweden)

    Mohamed E. Goher

    2015-01-01

    Full Text Available The removal of aluminum, iron and manganese from some pollution sources that drain into Ismailia Canal has been investigated using two different sorbents; granular activated carbon (GAC and Amberlite IR-120H (AIR-120H. Batch equilibrium experiments showed that the two sorbents have maximum removal efficiency for aluminum and iron pH 5 and 10 min contact time in ambient room temperature, while pH 7 and 30 min were the most appropriate for manganese removal. Dosage of 2 g/l for both GAC and AIR-120H was established to give the maximum removal capacity. At optimum conditions, the removal trend was in order of Al+3 > Fe+2 > Mn+2 with 99.2, 99.02 and 79.05 and 99.55, 99.42 and 96.65% of metal removal with GAC and AIR-120H, respectively. For the three metals, Langmuir and Freundlich isotherms showed higher R2 values, with a slightly better fitting for the Langmuir model. In addition, separation factors (RL and exponent (n values indicated favorable Langmuir (0 < RL < 1 and Freundlich (1 < n < 10 approach. GAC and AIR-120H can be used as excellent alternative, effective and inexpensive materials to remove high amounts of heavy metals from waste water.

  18. Adsorption and transformation of selected human-used macrolide antibacterial agents with iron(III) and manganese(IV) oxides

    Energy Technology Data Exchange (ETDEWEB)

    Feitosa-Felizzola, Juliana [Laboratoire Chimie Provence, Aix-Marseille Universites-CNRS (UMR 6264), 3 place Victor Hugo, 13331 Marseille Cedex 3 (France); Hanna, Khalil [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement, CNRS-Universite Henri Poincare-Nancy 1 (UMR 7564), 405 rue de Vandoeuvre, 54600 Villers-les-Nancy (France); Chiron, Serge [Laboratoire Chimie Provence, Aix-Marseille Universites-CNRS (UMR 6264), 3 place Victor Hugo, 13331 Marseille Cedex 3 (France)], E-mail: serge.chiron@univ-provence.fr

    2009-04-15

    The adsorption/transformation of two members (clarithromycin and roxithromycin) of the macrolide (ML) antibacterial agents on the surface of three environmental subsurface sorbents (clay, iron(III) and manganese(IV) oxy-hydroxides) was investigated. The adsorption fitted well to the Freundlich model with a high sorption capacity. Adsorption probably occurred through a surface complexation mechanism and was accompanied by slow degradation of the selected MLs. Transformation proceeded through two parallel pathways: a major pathway was the hydrolysis of the cladinose sugar, and to a lesser extent the hydrolysis of the lactone ring. A minor pathway was the N-dealkylation of the amino sugar. This study indicates that Fe(III) and Mn(IV) oxy-hydroxides in aquatic sediments may play an important role in the natural attenuation of MLs. Such an attenuation route yields a range of intermediates that might retain some of their biological activity. - Iron(III) and manganese(IV) oxy-hydroxides in aquatic sediments may play an important role in the natural attenuation of macrolide antibacterial agents.

  19. Biodegradation of pharmaceuticals and endocrine disruptors with oxygen, nitrate, manganese (IV), iron (III) and sulfate as electron acceptors

    Science.gov (United States)

    Schmidt, Natalie; Page, Declan; Tiehm, Andreas

    2017-08-01

    Biodegradation of pharmaceuticals and endocrine disrupting compounds was examined in long term batch experiments for a period of two and a half years to obtain more insight into the effects of redox conditions. A mix including lipid lowering agents (e.g. clofibric acid, gemfibrozil), analgesics (e.g. diclofenac, naproxen), beta blockers (e.g. atenolol, propranolol), X-ray contrast media (e.g. diatrizoic acid, iomeprol) as well as the antiepileptic carbamazepine and endocrine disruptors (e.g. bisphenol A, 17α-ethinylestradiol) was analyzed in batch tests in the presence of oxygen, nitrate, manganese (IV), iron (III), and sulfate. Out of the 23 selected substances, 14 showed a degradation of > 50% of their initial concentrations under aerobic conditions. The beta blockers propranolol and atenolol and the analgesics pentoxifylline and naproxen showed a removal of > 50% under anaerobic conditions. In particular naproxen proved to be degradable with oxygen and under most anaerobic conditions, i.e. with manganese (IV), iron (III), or sulfate. The natural estrogens estriol, estrone and 17β-estradiol showed complete biodegradation under aerobic and nitrate-reducing conditions, with a temporary increase of estrone during transformation of estriol and 17β-estradiol. Transformation of 17β-estradiol under Fe(III)-reducing conditions resulted in an increase of estriol as well. Concentrations of clofibric acid, carbamazepine, iopamidol and diatrizoic acid, known for their recalcitrance in the environment, remained unchanged.

  20. Adsorption and transformation of selected human-used macrolide antibacterial agents with iron(III) and manganese(IV) oxides

    International Nuclear Information System (INIS)

    Feitosa-Felizzola, Juliana; Hanna, Khalil; Chiron, Serge

    2009-01-01

    The adsorption/transformation of two members (clarithromycin and roxithromycin) of the macrolide (ML) antibacterial agents on the surface of three environmental subsurface sorbents (clay, iron(III) and manganese(IV) oxy-hydroxides) was investigated. The adsorption fitted well to the Freundlich model with a high sorption capacity. Adsorption probably occurred through a surface complexation mechanism and was accompanied by slow degradation of the selected MLs. Transformation proceeded through two parallel pathways: a major pathway was the hydrolysis of the cladinose sugar, and to a lesser extent the hydrolysis of the lactone ring. A minor pathway was the N-dealkylation of the amino sugar. This study indicates that Fe(III) and Mn(IV) oxy-hydroxides in aquatic sediments may play an important role in the natural attenuation of MLs. Such an attenuation route yields a range of intermediates that might retain some of their biological activity. - Iron(III) and manganese(IV) oxy-hydroxides in aquatic sediments may play an important role in the natural attenuation of macrolide antibacterial agents

  1. Radium desorption, manganese and iron dissolution from sand filters of a conventional ground water treatment plant under reductive conditions

    International Nuclear Information System (INIS)

    Al-Hobaib, A.S.; Al-Sulaiman, K.M.; Al-Dhayan, D.M.; Al-Suhybani, A.A.

    2006-01-01

    Sand filters are used as a filter bed in many ground water treatment plants to remove the physical contaminants and oxidation products. A build-up of radioactivity may take place on the granules, where iron and manganese oxides are deposited and form thin films on the surface of sand filter. The oxides of iron and manganese play an important role in adsorbing radium from ground water. The disposal of those granules makes a significant problem. A batch technique is used for solubilization of radium from sand filters in the presence of some organic acids, which act as reducing agents. These acids are formic acid, acetic acid, benzoic acid, succinic acid, oxalic acid, phthalic acid, and adipic acid. The data were obtained as a function of acidity, temperature, contact time and liquid/solid ratio particle size and shaking speed. It was found that oxalic acid was the best for radium removal. The effectiveness of these acids on radium removal was as follows: oxalic acid > phthalic acid > adipic acid > succinic acid > formic acid > acetic acid. The maximum removal obtained was 69.9% at 1M oxalic acid at 8 ml/g ratio. Reaction kinetics and mechanism parameters of the dissolution process were studied and compared with other published data. (author)

  2. Influences of iron, manganese, and dissolved organic carbon on the hypolimnetic cycling of amended mercury

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, Shawn P. [University of Wisconsin-Madison, Environmental Chemistry and Technology Program, 660 North Park Street, Madison, WI 53706-1481 (United States)]. E-mail: spchadwick@wisc.edu; Babiarz, Chris L. [University of Wisconsin-Madison, Environmental Chemistry and Technology Program, 660 North Park Street, Madison, WI 53706-1481 (United States); Hurley, James P. [University of Wisconsin-Madison, Environmental Chemistry and Technology Program, 660 North Park Street, Madison, WI 53706-1481 (United States); University of Wisconsin Aquatic Sciences Center, 1975 Willow Drive Madison, WI 53706-1177 (United States); Armstrong, David E. [University of Wisconsin-Madison, Environmental Chemistry and Technology Program, 660 North Park Street, Madison, WI 53706-1481 (United States)

    2006-09-01

    The biogeochemical cycling of iron, manganese, sulfide, and dissolved organic carbon were investigated to provide information on the transport and removal processes that control the bioavailability of isotopic mercury amended to a lake. Lake profiles showed a similar trend of hypolimnetic enrichment of Fe, Mn, DOC, sulfide, and the lake spike ({sup 202}Hg, purity 90.8%) and ambient of pools of total mercury (HgT) and methylmercury (MeHg). Hypolimnetic enrichment of Fe and Mn indicated that reductive mobilization occurred primarily at the sediment-water interface and that Fe and Mn oxides were abundant within the sediments prior to the onset of anoxia. A strong relationship (r {sup 2} = 0.986, n = 15, p < 0.001) between filterable Fe and Mn indicated that reduction of Fe and Mn hydrous oxides in the sediments is a common in-lake source of Fe(II) and Mn(II) to the hypolimnion and that a consistent Mn : Fe mass ratio of 0.05 exists in the lake. A strong linear relationship of both the filterable [Fe] (r {sup 2} = 0.966, n = 15, p < 0.001) and [Mn] (r {sup 2} = 0.964, n = 15, p < 0.001) to [DOC] indicated a close linkage of the cycles of Fe and Mn to DOC. Persistence of iron oxides in anoxic environments suggested that DOC was being co-precipitated with Fe oxide and released into solution by the reductive dissolution of the oxide. The relationship between ambient and lake spike HgT (r {sup 2} = 0.920, n = 27, p < 0.001) and MeHg (r {sup 2} = 0.967, n = 23, p < 0.001) indicated that similar biogeochemical processes control the temporal and spatial distribution in the water column. The larger fraction of MeHg in the lake spike compared to the ambient pool in the hypolimnion suggests that lake spike may be more available for methylation. A linear relationship of DOC to both filterable ambient HgT (r {sup 2} = 0.406, n = 27, p < 0.001) and lake spike HgT (r {sup 2} = 0.314, n = 15, p = 0.002) suggest a role of organic matter in Hg transport and cycling. However, a weak

  3. Nitrogen reduction: Molybdenum does it again

    Science.gov (United States)

    Schrock, Richard R.

    2011-02-01

    Nature reduces dinitrogen under mild conditions using nitrogenases, the most active of which contains molybdenum and iron. The only abiological dinitrogen reduction catalyst that avoids the harsh conditions of the Haber-Bosch process contains just molybdenum.

  4. Formation of a homocitrate-free iron-molybdenum cluster on NifEN: implications for the role of homocitrate in nitrogenase assembly.

    Science.gov (United States)

    Fay, Aaron Wolfe; Blank, Michael Aaron; Yoshizawa, Janice Mariko; Lee, Chi Chung; Wiig, Jared Andrew; Hu, Yilin; Hodgson, Keith Owen; Hedman, Britt; Ribbe, Markus Walter

    2010-03-28

    Molybdenum (Mo)-dependent nitrogenase is a complex metalloprotein that catalyzes the biological reduction of dinitrogen (N(2)) to ammonia (NH(3)) at the molybdenum-iron cofactor (FeMoco) site of its molybdenum-iron (MoFe) protein component. Here we report the formation of a homocitrate-free, iron-molybdenum ("FeMo") cluster on the biosynthetic scaffold of FeMoco, NifEN. Such a NifEN-associated "FeMo" cluster exhibits EPR features similar to those of the NifEN-associated, fully-complemented "FeMoco", which originate from the presence of Mo in both cluster species; however, "FeMo" cluster and "FeMoco" display different temperature-dependent changes in the line shape and the signal intensity of their respective EPR features, which reflect the impact of homocitrate on the redox properties of these clusters. XAS/EXAFS analysis reveals that the Mo centers in both "FeMo" cluster and "FeMoco" are present in a similar coordination environment, although Mo in "FeMo" cluster is more loosely coordinated as compared to that in "FeMoco" with respect to the Mo-O distances in the cluster, likely due to the absence of homocitrate that normally serves as an additional ligand for the Mo in the cluster. Subsequent biochemical investigation of the "FeMo" cluster not only facilitates the determination of the sequence of events in the mobilization of Mo and homocitrate during FeMoco maturation, but also permits the examination of the role of homocitrate in the transfer of FeMoco between NifEN and MoFe protein. Combined outcome of these studies establishes a platform for future structural analysis of the interactions between NifEN and MoFe protein, which will provide useful insights into the mechanism of cluster transfer between the two proteins.

  5. [Effect of selenium on the uptake and translocation of manganese, iron, phosphorus and selenium in rice (Oryza sativa L.)].

    Science.gov (United States)

    Hu, Ying; Huang, Yi-Zong; Huang, Yan-Chao; Liu, Yun-Xia; Liang, Jian-Hong

    2013-10-01

    A pot experiment was conducted to clarify the effect of selenium on the uptake and translocation of manganese (Mn), iron (Fe) , phosphorus (P) and selenium (Se) in rice ( Oryza sativa L.). The results showed that addition of Se led to the significant increase of Se concentration in iron plaque on the root surface, root, shoot, husk and brown rice, and significant decrease of Mn concentration in shoot, husk and brown rice. At the Se concentrations of 0.5 and 1.0 mg.kg-1 in soil, Mn concentrations in rice shoot decreased by 32. 2% and 35.0% respectively, in husk 22.0% and 42.6% , in brown rice 27.5% and 28.5% , compared with the Se-free treatment. There was no significant effect of Se on the P and Fe concentrations in every parts of rice, except for Fe concentrations in husk. The translocation of P and Fe from iron plaque, root, shoot and husk to brown rice was not significantly affected by Se addition, but Mn translocation from iron plaque and root to brown rice was significantly inhibited by Se addition. Addition of 1.0 mg.kg-1. Se resulted in the decrease of translocation factor from iron plaque and root to brown rice by 38.9% and 37.9%, respectively, compared with the control treatment. The distribution ratios of Mn, Fe, P and Se in iron plaque, root, shoot, husk and brown rice were also affected by Se addition. The results indicated that Mn uptake, accumulation and translocation in rice could be decreased by the addition of Se in soil, therefore, Se addition could reduce the Mn harm to human health through food chain.

  6. Effects of carbon and molybdenum on the microstructures of high chromium white cast irons

    International Nuclear Information System (INIS)

    Sinatora, Amilton; Ambrosio Filho, Francisco; Goldenstein, Helio; Fuoco, Ricardo; Albertin, Eduardo; Mei, Paulo Roberto

    1992-01-01

    The effects of 3 levels of carbon and 1.5% Mo addition on the solidification structures of a 15% chromium white cast iron were studied. The volume fraction of primary austenite and of eutectic carbides, as well as the number of carbide particles per unit length and the mean secondary dendrite arm spacing were measured. By means of thermal analysis, thermal arrest corresponding to the formation of the primary austenite and of the eutectic were determined. The increase in the carbon content and the addition of Mo led to lowering of the thermal arrests and to coarsening of the particles. (author)

  7. Effects of resuspension on benthic fluxes of oxygen, nutrients, dissolved inorganic carbon, iron and manganese in the Gulf of Finland, Baltic Sea

    NARCIS (Netherlands)

    Almroth, E.; Tengberg, A.; Andersson, J.H.; Pakhomova, S.; Hall, P.O.J.

    2009-01-01

    The effect of resuspension on benthic fluxes of oxygen (O2), ammonium (NH4+), nitrate (NO3-), phosphate (PO43-), silicate (Si(OH)4), dissolved inorganic carbon (DIC), total dissolved iron (Fe) and total dissolved manganese (Mn) was studied at three different stations in the Gulf of Finland (GoF),

  8. Pilot study of iron and manganese removal from Mexican drinking water supply sources; Estudio piloto para remocion de fierro y manganeso en las fuentes de abastecimiento de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Simeonova, Verguinia Petkova; Mintchev, Mintcho Lliev; Rivera, Maria Lourdes [Instituto Mexicano de Tecnologia del Agua, Jiutepec, Morelos (Mexico)

    1999-08-01

    This study demonstrates the efficiency of a technique for manganese removal through adsorption-oxidation on zeolite. Several Mexican groundwater sources were selected for pilot installations. The results show that the final iron and manganese concentrations are within the limits set in the Official Mexican Standard, NOM-127-SSA1, referring to drinking water. An analysis was made of the effect of the operating rate and the granule size of the filtering material on iron and manganese removal and of calcium and magnesium salts associated with hardness. Zeolite covered with manganese precipitates was highly selective for iron and manganese; this made the treatment of groundwater with high iron and manganese concentrations possible, even in the presence of hardness and alkalinity. A description is given of the procedures to prepare the material and regenerate its filtration capacity without interrupting the filtration process. [Spanish] El presente estudio comprueba la eficiencia de la tecnica propuesta para la remocion de manganeso por adsorcion-oxidacion sobre zeolita a traves de estudios piloto en varias fuentes subterraneas de Mexico. Los resultados demuestran que la concentracion de fierro y manganeso en el agua producida cumple con la Norma Oficial Mexicana NOM-127-SSA1 para el consumo humano en todo los casos estudiados. Fueron analizadas la influencia de la tasa de operacion y la granulometria del material filtrante sobre el grado de remocion de fierro y manganeso, asi como el efecto de las sales de calcio y magnesio que originan la dureza del agua. Durante la experimentacion se comprobo que la zeolita recubierta con los precipitados de manganeso es altamente selectiva respecto al fierro y manganeso, lo que permite tratar el agua de las fuentes subterraneas con elevada concentracion de Fe y Mn en presencia de alta dureza y alcalinidad. En el articulo se describen los procedimientos para la preparacion del material filtrante y la regeneracion de su capacidad sin

  9. Metal Tolerance Protein 8 Mediates Manganese Homeostasis and Iron Reallocation during Seed Development and Germination

    Czech Academy of Sciences Publication Activity Database

    Eroglu, S.; Giehl, R.F.H.; Meier, B.; Takahashi, M.; Terada, Y.; Ignatyev, K.; Andresen, Elisa; Küpper, Hendrik; Peiter, E.; von Wiren, N.

    2017-01-01

    Roč. 174, č. 3 (2017), s. 1633-1647 ISSN 0032-0889 Institutional support: RVO:60077344 Keywords : diffusion facilitator family * arabidopsis-thaliana * x-ray * vacuolar manganese Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 6.456, year: 2016

  10. Distribution of iron, manganese, cobalt and nickel in sediment cores of the northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, Ch.M.; Setty, M.G.A.P.

    :72; 3:205; and 6:265; (b) for the slope it is 1:116; and (c) the basin 6:170. The values are highest in one core. This suggests an enrichment of manganese in the shelf region and in the basin, but great mobility in the slope and parts of the shelf...

  11. A kinetic study of the redox reactions of complex cyanides of iron, molybdenum and tungsten with compounds of the group VI A elements

    International Nuclear Information System (INIS)

    Dennis, C.R.

    1981-01-01

    The kinetic study arises out of the fact that few is known about redox kinetics of complex cyanides of molybdenum and tungsten. The redox kinetics of the complex cyanides of iron with organic and inorganic compounds are well known in organic chemistry. This comparitive study is done to obtain more information on redox reactions of complex cyanides of molybdenum and tungsten considering its greater applicability in organic and inorganic chemistry because of the propitious reduction potential of this complex cyanide in acidic and alkaline mediums. Various redox systems are kinetically investigated regarding the influence of the oxidising agent, reducing agent hydrogen ions and alkaline-metal ions on the reaction rate. A reaction mechanism is proposed for every system

  12. Hierarchical assembly of urchin-like alpha-iron oxide hollow microspheres and molybdenum disulphide nanosheets for ethanol gas sensing.

    Science.gov (United States)

    Zhang, Dongzhi; Fan, Xin; Yang, Aijun; Zong, Xiaoqi

    2018-08-01

    In this paper, we fabricated a high-performance ethanol sensor using layer-by-layer self-assembled urchin-like alpha-iron oxide (α-Fe 2 O 3 ) hollow microspheres/molybdenum disulphide (MoS 2 ) nanosheets heterostructure as sensitive materials. The nanostructural, morphological, and compositional properties of the as-prepared α-Fe 2 O 3 /MoS 2 heterostructure were characterized by X-ray diffraction (XRD), energy dispersive spectrometer (EDS), scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS), which confirmed its successful preparation and rationality. The α-Fe 2 O 3 /MoS 2 nanocomposite sensor shows good selectivity, excellent reproducibility, fast response/recovery time and low detection limit towards ethanol gas at room temperature, which is superior to the single component of α-Fe 2 O 3 hollow microspheres and MoS 2 nanosheets. Furthermore, the response of the α-Fe 2 O 3 /MoS 2 nanocomposite sensor as a function of ethanol gas concentration was also demonstrated. The enhanced ethanol sensing properties of the α-Fe 2 O 3 /MoS 2 nanocomposite sensor were ascribed to the synergistic effect and heterojunction between the urchin-Like α-Fe 2 O 3 hollow microspheres and MoS 2 nanosheets. This work verifies that the hierarchical α-Fe 2 O 3 /MoS 2 nanoheterostructure is a potential candidate for fabricating room-temperature ethanol gas sensor. Copyright © 2018 Elsevier Inc. All rights reserved.

  13. Modeling the Performance of Biological Rapid Sand Filters Used to Remove Ammonium, Iron, and Manganese From Drinking Water

    DEFF Research Database (Denmark)

    Lee, Carson; Albrechtsen, Hans-Jørgen; Smets, Barth F.

    activated carbon and are often used following ozonation to remove additional biodegradable organics created during ozonation. In Europe, biological filters are also used to remove ammonium and reduced forms of iron and manganese. These compounds can cause biological instability in the distribution system...... tracer, are performed during an operational cycle of a filter to examine how the filter flow changes with time. The data is used to validate a mathematical model that can both predict process performance and to gain an understanding of how dynamic conditions can influence filter performance....... The mathematical model developed is intended to assist in the design of new filters, set up of pilot plant studies, and as a tool to troubleshoot existing problems in full scale filters. Unlike previous models, the model developed accounts for the effects of particle/precipitate accumulation and its effects...

  14. Water-soluble Manganese and Iron Mesotetrakis(carboxyl)porphyrin: DNA Binding, Oxidative Cleavage, and Cytotoxic Activities.

    Science.gov (United States)

    Shi, Lei; Jiang, Yi-Yu; Jiang, Tao; Yin, Wei; Yang, Jian-Ping; Cao, Man-Li; Fang, Yu-Qi; Liu, Hai-Yang

    2017-06-29

    Two new water-soluble metal carboxyl porphyrins, manganese (III) meso -tetrakis (carboxyl) porphyrin and iron (III) meso -tetrakis (carboxyl) porphyrin, were synthesized and characterized. Their interactions with ct-DNA were investigated by UV-Vis titration, fluorescence spectra, viscosity measurement and CD spectra. The results showed they can strongly bind to ct-DNA via outside binding mode. Electrophoresis experiments revealed that both complexes can cleave pBR322 DNA efficiently in the presence of hydrogen peroxide, albeit 2-Mn exhibited a little higher efficiency. The inhibitor tests suggest the oxidative DNA cleavage by these two complexes may involve hydroxyl radical active intermediates. Notably, 2-Mn exhibited considerable photocytotoxicity against Hep G2 cell via triggering a significant generation of ROS and causing disruption of MMP after irradiation.

  15. Iron and manganese in oxide minerals and in glasses: preliminary consideration of Eh buffering potential at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Caporuscio, F.A.; Vaniman, D.T.

    1985-04-01

    The tuffs of Yucca Mountain at the Nevada Test Site are currently under investigation as a possible deep burial site for high-level radioactive waste disposal. One of the main concerns is the effect of oxidizing groundwater on the transport of radionuclides. Rock components that may affect the oxygen content of groundwater include Fe-Ti oxides, Mn oxides, and glasses that contain ferrous iron. Some phenocryst Fe-Ti oxides at Yucca Mountain are in reduced states, whereas groundmass Fe-Ti oxides have been oxidized to hematite, rutile, and pseudobrookite (Fe 3+ -bearing phases) exclusively. Estimates of Fe 2+ -bearing oxides indicate that less than 0.33 vol% phenocrysts is available to act as solid buffering agents of Eh. Of this percentage, significant amounts of Fe-Ti oxides are isolated from effective interaction with groundwater because they occur in densely welded, devitrified tuffs that have low interstitial permeability. Manganese oxides occur primarily along fractures in the ash-flow tuffs. Because the Mn oxides are concentrated along the same pathways (fractures) where transport has occurred in the past, these small volume percentages could act as buffers. However, the oxidation states of actual Mn-oxide phases are high (Mn 4+ ), and these minerals have virtually no potential for reducing groundwater Eh. Manganese oxides may even act as oxidizing agents. However, regardless of their poor capabilities as reducing agents, the Mn oxides could be important as sorbents of heavy metals at Yucca Mountain. The lack of accessible, pristine Fe-Ti oxides and the generally high oxidation states of Mn oxides seem to rule out these oxides as Eh buffers of the Yucca Mountain groundwater system. Reduction of ferrous iron within glassy tuffs may have some effect on Eh, but further study is needed. At present it is prudent to assume that minerals and glasses have little or no capacity for reducing oxygen-rich groundwater at Yucca Mountain. 25 refs., 3 figs., 12 tabs

  16. QUANTITATIVE CHANGES OF IRON, MANGANESE, ZINC AND COPPER IN PINE BARK COMPOSTED WITH PLANT MASS AND EFFECTIVE MICROORGANISMS

    Directory of Open Access Journals (Sweden)

    Jacek Czekała

    2014-10-01

    Full Text Available The objective of the investigation was to ascertain changes in the total contents, as well as water-soluble forms of iron, manganese, zinc and copper during the process of composting of pine bark with plant material (PM, with or without the addition of effective microorganisms (EM. Experiments were carried out at a forest nursery area and comprised the following treatments: pile 1. pine bark, pile 2. pine bark + PM, pile 3. pine bark + PM + EM. Compost piles were formed from pine bark (4 m3 and as described above, 2 Mg of plant material were added to pile 2 and to pile 3 – plant material and effective microorganisms in the amount of 3 dm3·m-3 bark. All compost files were also supplemented with 0.3 kg P2O5·m-3 (in the form of superphosphate 20% P2O5 and 0,1 kg K2O·m-3 (in the form of potassium salt 60%. The plant material comprised a mixture of buckwheat, field pea, serradella and vetch harvested before flowering. Piles were mixed and formed with the tractor aerator. At defined dates, using the method of atomic spectrophotometry, total contents of iron, manganese, zinc and copper, as well as their water-soluble forms were determined. It was found that all the examined elements underwent changes, albeit with different dynamics. This was particularly apparent in the case of water-soluble forms. This solubility was, in general, high during the initial days of the process and declined with the passage of time. No significant impact of effective microorganisms on the solubility of the examined chemical elements was determined, especially in mature composts.

  17. [Vitamin and mineral supplements in the diet of military personnel: effect on the balance of iron, copper and manganese, immune reactivity and physical work-capacity].

    Science.gov (United States)

    Zaĭtseva, I P; Nosolodin, V V; Zaĭtsev, O N; Gladkikh, I P; Koznienko, I V; Beliakov, R A; Arshinov, N P

    2012-03-01

    Conducted with the participation of 50 students of military educational study the effect of various vitamin and mineral complexes for the provision by the body naturally iron, copper and manganese on the immune and physical status. Found that diets enriched BMV was accompanied by a significant delay in the micro-elements, mainly iron, which indicates a deficiency of these bioelements in chickens Santo during the summer. Under the influence of vitamin-mineral complexes significantly increased rates of natural and specific immunity. As the delay increases significantly increased iron medical indicators of immunological reaction efficiency and physical performance.

  18. Synthesis and Characterization of Mixed Iron-Manganese Oxide Nanoparticles and Their Application for Efficient Nickel Ion Removal from Aqueous Samples

    Science.gov (United States)

    Serra, Antonio; Monteduro, Anna Grazia; Padmanabhan, Sanosh Kunjalukkal; Licciulli, Antonio; Bonfrate, Valentina; Salvatore, Luca; Calcagnile, Lucio

    2017-01-01

    Mixed iron-manganese oxide nanoparticles, synthesized by a simple procedure, were used to remove nickel ion from aqueous solutions. Nanostructures, prepared by using different weight percents of manganese, were characterized by transmission electron microscopy, selected area diffraction, X-ray diffraction, Raman spectroscopy, and vibrating sample magnetometry. Adsorption/desorption isotherm curves demonstrated that manganese inclusions enhance the specific surface area three times and the pores volume ten times. This feature was crucial to decontaminate both aqueous samples and food extracts from nickel ion. Efficient removal of Ni2+ was highlighted by the well-known dimethylglyoxime test and by ICP-MS analysis and the possibility of regenerating the nanostructure was obtained by a washing treatment in disodium ethylenediaminetetraacetate solution. PMID:28804670

  19. Synthesis and Characterization of Mixed Iron-Manganese Oxide Nanoparticles and Their Application for Efficient Nickel Ion Removal from Aqueous Samples

    Directory of Open Access Journals (Sweden)

    Alessandro Buccolieri

    2017-01-01

    Full Text Available Mixed iron-manganese oxide nanoparticles, synthesized by a simple procedure, were used to remove nickel ion from aqueous solutions. Nanostructures, prepared by using different weight percents of manganese, were characterized by transmission electron microscopy, selected area diffraction, X-ray diffraction, Raman spectroscopy, and vibrating sample magnetometry. Adsorption/desorption isotherm curves demonstrated that manganese inclusions enhance the specific surface area three times and the pores volume ten times. This feature was crucial to decontaminate both aqueous samples and food extracts from nickel ion. Efficient removal of Ni2+ was highlighted by the well-known dimethylglyoxime test and by ICP-MS analysis and the possibility of regenerating the nanostructure was obtained by a washing treatment in disodium ethylenediaminetetraacetate solution.

  20. [Reference values of iron, iodine, zinc, selenium, copper, molybdenum, vitamin C, vitamin E, vitamin K, carotenoids and polyphenols for the Venezuelan population].

    Science.gov (United States)

    García-Casal, Maria Nieves; Landaeta, Maritza; Adrianza de Baptista, Gertrudis; Murillo, Carolain; Rincón, Mariela; Bou Rached, Lizet; Bilbao, Arantza; Anderson, Hazel; García, Doris; Franquiz, Julia; Puche, Rafael; Garcia, Omar; Quintero, Yurimay; Peña-Rosas, Juan Pablo

    2013-12-01

    The review on iron, iodine, zinc, selenium, copper, molybdenum, vitamin C, vitamin E, vitamin K, carotenoids and polyphenols recommendations for Venezuela comprise the definitions adopted worldwide known as Dietary Reference Intakes (DRIs) that include Recommended Dietary Allowance (RDA), Estimated Average Requirement (EAR), Adequate Intake (AI) and Tolerable Upper Intake Levels (UL). The RDA for iron: 11 mg/day for infants Vitamin C: 40-50 mg/day for infants, 15-45 mg/ day for children, 75 mg/day for male adolescents, 65 mg/day for female adolescents, 90 mg/day for adult males, 75 mg/day for adult females, 80-85 mg/day during pregnancy and 115-120 mg/day during lactation. Recommendations for copper, selenium, molybdenum, vitamins E, K, carotenoids and polyphenols are also presented. These recommendations will help to design adequate and efficient policies that could help to avoid or to treat the consequences derived from the deficiency or the excess of these nutrients.

  1. Trithiocyanurate Complexes of Iron, Manganese and Nickel and Their Anticholinesterase Activity

    Directory of Open Access Journals (Sweden)

    Pavel Kopel

    2014-04-01

    Full Text Available The complexes of Fe(II, Mn(II and Ni(II with a combination of a Schiff base, nitrogen-donor ligand or macrocyclic ligand and trithiocyanuric acid (ttcH3 were prepared and characterized by elemental analysis and spectroscopies. Crystal and molecular structures of the iron complex of composition [Fe(L1](ttcH2(ClO4·EtOH·H2O (1, where L1 is Schiff base derived from tris(2-aminoethylamine and 2-pyridinecarboxaldehyde, were solved. It was found that the Schiff base is coordinated to the central iron atom by six nitrogens forming deformed octahedral arrangement, whereas trithiocyanurate(1- anion, perchlorate and solvent molecules are not coordinated. The X-ray structure of the Schiff base sodium salt is also presented and compared with the iron complex. The anticholinesterase activity of the complexes was also studied.

  2. Hydrometallurgical method for recycling rare earth metals, cobalt, nickel, iron, and manganese from negative electrodes of spent Ni-MH mobile phone batteries

    International Nuclear Information System (INIS)

    Santos, Vinicius Emmanuel de Oliveira dos; Lelis, Maria de Fatima Fontes; Freitas, Marcos Benedito Jose Geraldo de

    2014-01-01

    A hydrometallurgical method for the recovery of rare earth metals, cobalt, nickel, iron, and manganese from the negative electrodes of spent Ni-MH mobile phone batteries was developed. The rare earth compounds were obtained by chemical precipitation at pH 1.5, with sodium cerium sulfate (NaCe(SO 4 ) 2 .H 2 O) and lanthanum sulfate (La 2 (SO 4 ) 3 .H 2 O) as the major recovered components. Iron was recovered as Fe(OH) 3 and FeO. Manganese was obtained as Mn 3 O 4 .The recovered Ni(OH) 2 and Co(OH) 2 were subsequently used to synthesize LiCoO 2 , LiNiO 2 and CoO, for use as cathodes in ion-Li batteries. The anodes and recycled materials were characterized by analytical techniques. (author)

  3. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

  4. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

  5. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

  6. Adsorption of Arsenate by Nano Scaled Activated Carbon Modified by Iron and Manganese Oxides

    Directory of Open Access Journals (Sweden)

    George P. Gallios

    2017-09-01

    Full Text Available The presence of arsenic in water supplies is a major problem for public health and still concerns large parts of population in Southeast Asia, Latin America and Europe. Removal of arsenic is usually accomplished either by coagulation with iron salts or by adsorption with iron oxides or activated alumina. However, these materials, although very efficient for arsenic, normally do not remove other undesirable constituents from waters, such as chlorine and organo-chlorine compounds, which are the results of water chlorination. Activated carbon has this affinity for organic compounds, but does not remove arsenic efficiently. Therefore, in the present study, iron modified activated carbons are investigated as alternative sorbents for the removal of arsenic(V from aqueous solutions. In addition, modified activated carbons with magnetic properties can easily be separated from the solutions. In the present study, a simple and efficient method was used for the preparation of magnetic Fe3(Mn2+O4 (M:Fe and/or Mn activated carbons. Activated carbons were impregnated with magnetic precursor solutions and then calcinated at 400 °C. The obtained carbons were characterized by X-ray diffraction (XRD, nitrogen adsorption isotherms, scanning electron microscopy (SEM, vibrating sample magnetometer (VSM, Fourier Transform Infrared Spectrometry (FTIR and X-ray photoelectron spectroscopy (XPS measurements. Their adsorption performance for As(V was evaluated. The iron impregnation presented an increase in As(V maximum adsorption capacity (Qmax from about 4 mg g−1 for the raw carbon to 11.05 mg g−1, while Mn incorporation further increased the adsorption capacity at 19.35 mg g−1.

  7. Effect of Microstructures on Working Properties of Nickel-Manganese-Copper Cast Iron

    Directory of Open Access Journals (Sweden)

    Daniel Medyński

    2018-05-01

    Full Text Available In the paper, the effects, on basic usable properties (abrasive wear and corrosion resistance, of solidification (acc. to the stable and non-stable equilibrium system and transformations occurring in the matrix during the cooling of castings of Ni-Mn-Cu cast iron were determined. Abrasive wear resistance was mainly determined by the types and arrangements of high-carbon phases (indicated by eutectic saturation degree, and the kinds of matrices (indicated by the nickel equivalent value, calculated from chemical composition. The highest abrasive wear resistance was found for white cast iron, with the highest degree of austenite to martensite transformation occurring in its matrix. Irrespective of solidification, a decrease of the equivalent value below a limit value resulted in increased austenite transformation, and thus, to a significant rise in hardness and abrasive wear resistance for the castings. At the same time, corrosion resistance of the alloy was slightly reduced. The examinations showed that corrosion resistance of Ni-Mn-Cu cast iron is, too a much lesser degree, decided by the means of solidification of the castings, rather than transformations occurring in the matrix, as controlled by nickel equivalent value (especially elements with high electrochemical potential.

  8. Nanostructured Iron and Manganese Oxide Electrode Materials for Lithium Batteries: Influence of Chemical and Physical Properties on Electrochemistry

    Science.gov (United States)

    Durham, Jessica L.

    The widespread use of portable electronics and growing interest in electric and hybrid vehicles has generated a mass market for batteries with increased energy densities and enhanced electrochemical performance. In order to address a variety of applications, commercially fabricated secondary lithium-ion batteries employ transition metal oxide based electrodes, the most prominent of which include lithium nickel manganese cobalt oxide (LiNixMn yCo1-x-yO2), lithium iron phosphate (LiFePO4), and lithium manganese oxide (LiMn 2O4). Transition metal oxides are of particular interest as cathode materials due to their robust framework for lithium intercalation, potential for high energy density, and utilization of earth-abundant elements (i.e. iron and manganese) leading to decreased toxicity and cost-effective battery production on industrial scales. Specifically, this research focuses on MgFe2O4, AgxMn8O16, and AgFeO 2 transition metal oxides for use as electrode materials in lithium-based batteries. The electrode materials are prepared via co-precipitation, reflux, and hydrothermal methods and characterized by several techniques (XRD, SEM, BET, TGA, DSC, XPS, Raman, etc.). The low-temperature syntheses allowed for precise manipulation of structural, compositional, and/or functional properties of MgFe2O4, AgxMn8 O16, and AgFeO2 which have been shown to influence electrochemical behavior. In addition, advanced in situ and ex situ characterization techniques are employed to study the lithiation/de-lithiation process and establish valid redox mechanisms. With respect to both chemical and physical properties, the influence of MgFe2O4 particle size and morphology on electrochemical behavior was established using ex situ X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) imaging. Based on composition, tunneled AgxMn8O16 nanorods, prepared with distinct Ag+ contents and crystallite sizes, display dramatic differences in ion-transport kinetics due to

  9. Molecular-Level Processes Governing the Interaction of Contaminants with Iron and Manganese Oxides - Final Report; FINAL

    International Nuclear Information System (INIS)

    Brown, G. E. Jr.; Chambers, S. A.

    1999-01-01

    Many of the inorganic and organic contaminants present in sediments at DOE sites can be altered or destroyed by reduction and oxidation (redox) reactions occurring at mineral surfaces. A fundamental understanding of such redox processes provided by molecular-level studies on structurally and compositionally well-defined mineral surfaces will lead to: (i) improved models of contaminant fate and transport in geochemical systems, and (ii) optimized manipulation of these processes for remediation purposes. To contribute to this understanding, we will study, both experimentally and theoretically, redox processes involving three important contaminants - chromate ion, carbon tetrachloride, and trichloroethene TCE, on the following iron and manganese oxides - hematite, magnetite, maghemite, and pyrolusite. These oxides and their hydroxylated analogs commonly occur as coatings on minerals or as interfaces in the subsurface environment. Single-crystal surfaces of these oxides will be synthesized in carefully controlled fashion by molecular beam epitaxy. These surfaces, as well as high surface are powdered samples of these oxides, will be used in spectroscopic and kinetic experiments in both aqueous and gas phases. Our goal is to identify products and to determine the kinetics and mechanisms of surface-catalyzed redox reaction of Cr(VI) and CR(III), and the reductive dechlorination of carbon tetrachloride and TCE. The combination of theory and experiment will provide the base information needed to scale from the molecular level to the microscopic grain level minerals

  10. Environmental natural radioactive and radiation hazard in sedimentary rocks for manganese-iron ore at Um Bogma Area, Sinai, Egypt

    International Nuclear Information System (INIS)

    Abu-Zeid, H.M; Nada, A; Abd-Elmaksoud, T.M; Ragab, F.M.; El-Assy, I

    2011-01-01

    The aim of this study was to measure concentrations and distributions of natural radionuclides occurring in sedimentary rocks. The activity concentrations of the naturally occurring radionuclides 238 U, 232 Th,and 40 K in the manganese-iron ore of Um Bogma area which subdivided into three localities Wadi Nasieb (NS), Abu Thor (AT) and Um Bogma (UB) were measured using a high-purity germanium detector.The average concentration values of 238 U, 232 Th, and 40 K in the surveyed samples in Wadi Nasieb are 261.38, 9.57 and 130.63 Bqkg -1 respectively also in Abu Thor 224.51,6.7,94.99 Bqkg -1 and in Um Bogma 441.47,7.87 and 272.69 Bqkg -1 . The overall outdoor terrestrial gamma dose rates fluctuate from 103.38 to 193.5 nGyh -1 for all localities. The annual effective dose rate for all localities ranged from 0.13 to 0.24 mSvy -1 have been compared with the global averages which are within the safety range for workers in the studied localities.

  11. Deferribacter thermophilus gen. nov., sp. nov., a novel thermophilic manganese- and iron-reducing bacterium isolated from a petroleum reservoir.

    Science.gov (United States)

    Greene, A C; Patel, B K; Sheehy, A J

    1997-04-01

    A thermophilic anaerobic bacterium, designated strain BMAT (T = type strain), was isolated from the production water of Beatrice oil field in the North Sea (United Kingdom). The cells were straight to bent rods (1 to 5 by 0.3 to 0.5 microns) which stained gram negative. Strain BMAT obtained energy from the reduction of manganese (IV), iron(III), and nitrate in the presence of yeast extract, peptone, Casamino Acids, tryptone, hydrogen, malate, acetate, citrate, pyruvate, lactate, succinate, and valerate. The isolate grew optimally at 60 degrees C (temperature range for growth, 50 to 65 degrees C) and in the presence of 2% (wt/vol) NaCl (NaCl range for growth, 0 to 5% [wt/vol]). The DNA base composition was 34 mol% G + C. Phylogenetic analyses of the 16S rRNA gene indicated that strain BMAT is a member of the domain Bacteria. The closest known bacterium is the moderate thermophile Flexistipes sinusarabici (similarity value, 88%). Strain BMAT possesses phenotypic and phylogenetic traits that do not allow its classification as a member of any previously described genus; therefore, we propose that this isolate should be described as a member of a novel species of a new genus, Deferribacter thermophilus gen. nov., sp. nov.

  12. Surface properties of self-assembled monolayer films of tetra-substituted cobalt, iron and manganese alkylthio phthalocyanine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Akinbulu, Isaac Adebayo; Khene, Samson [Department of Chemistry, Rhodes University, Grahamstown 6140 (South Africa); Nyokong, Tebello, E-mail: t.nyokong@ru.ac.z [Department of Chemistry, Rhodes University, Grahamstown 6140 (South Africa)

    2010-09-30

    Self-assembled monolayer (SAM) films of iron (SAM-1), cobalt (SAM-2) and manganese (SAM-3) phthalocyanine complexes, tetra-substituted with diethylaminoethanethio at the non-peripheral positions, were formed on gold electrode in dimethylformamide (DMF). Electrochemical, impedimentary and surface properties of the SAM films were investigated. Cyclic voltammetry was used to investigate the electrochemical properties of the films. Ability of the films to inhibit common faradaic processes on bare gold surface (gold oxidation, solution redox chemistry of [Fe(H{sub 2}O){sub 6}]{sup 3+}/[Fe(H{sub 2}O){sub 6}]{sup 2+} and underpotential deposition (UDP) of copper) was investigated. Electrochemical impedance spectroscopy (EIS), using [Fe(CN){sub 6}]{sup 3-/4-} redox process as a probe, offered insights into the electrical properties of the films/electrode interfaces. Surface properties of the films were probed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The films were employed for the electrocatalytic oxidation of the pesticide, carbofuran. Electrocatalysis was evidenced from enhanced current signal and less positive oxidation potential of the pesticide on each film, relative to that observed on the bare gold electrode. Mechanism of electrocatalytic oxidation of the pesticide was studied using rotating disc electrode voltammetry.

  13. Comparison of Heavy-Duty Scuffing Behavior between Chromium-Based Ceramic Composite and Nickel-Chromium-Molybdenum-Coated Ring Sliding against Cast Iron Liner under Starvation

    Directory of Open Access Journals (Sweden)

    Yan Shen

    2017-10-01

    Full Text Available A running-in and starved lubrication experiment is designed to investigate the heavy-duty scuffing behavior of piston ring coatings against cast iron (Fe cylinder liner using the piston ring reciprocating liner test rig. The scuffing resistance of the piston ring with the chromium-based ceramic composite coating (CKS, and that with the thermally sprayed nickel-chromium-molybdenum coating (NCM is compared at different nominal pressures (40~100 MPa and temperatures (180~250 °C. With the failure time as a criterion, the rank order is as follows: NCM/Fe > CKS/Fe. Before the scoring occurs at the interface of the piston ring and cylinder liner (PRCL, the cast iron liner enters into a “polish wear” stage, and iron-based adhesive materials begin to form on the piston ring surface. With the macroscopic adhesion formation, the plastic shearing cycle causes surface damages mainly due to abrasive effects for the CKS/Fe pairs and adhesive effects for the NCM/Fe pairs.

  14. Experimental investigation and thermodynamic modeling of molybdenum and vanadium-containing carbide hardened iron-based alloys

    International Nuclear Information System (INIS)

    Cabrol, E.; Bellot, C.; Lamesle, P.; Delagnes, D.; Povoden-Karadeniz, E.

    2013-01-01

    Highlights: ► Improvement of a carbide selective extraction method. ► Determination of experimental data on the Fe–C–Cr–Mo–V system for carbides above 900 °C: crystallographic structures and compositions of precipitates, matrix composition. ► High molybdenum solubility in FCC carbides. ► Improvement of thermodynamic databases from experimental results. ► Validation of the optimized database with different compositions steels. -- Abstract: A technique for the microstructural study of steels, based on the use of matrix dissolution to collect the very low number density precipitates formed in martensitic steels, has been considerably improved. This technique was applied to two different grades of alloy, characterized by high nickel and cobalt contents and varying chromium, molybdenum and vanadium contents. The technique was implemented at temperatures ranging between 900 °C and 1000 °C, in order to accurately determine experimental data including the crystallographic structure and chemical composition of the carbides, the carbide solvus temperatures, and variations in the chemical composition of the matrix. These experimental investigations reveal that the solubility of molybdenum in FCC carbides can be very high. These results have been compared with the behavior predicted by computational thermodynamics, and used to evaluate and improve the thermodynamic Matcalc steel database. This upgraded database has been validated on three other steels with different chemical compositions, characterized by the same Fe–Cr–Mo–V–C system

  15. Experimental investigation and thermodynamic modeling of molybdenum and vanadium-containing carbide hardened iron-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cabrol, E., E-mail: ecabrol@mines-albi.fr [Institut Clément Ader, Mines Albi, Campus Jarlard, F-81013 Albi Cedex 09 (France); Aubert and Duval, BP1 F-63770 Les Ancizes (France); Bellot, C. [Institut Clément Ader, Mines Albi, Campus Jarlard, F-81013 Albi Cedex 09 (France); Aubert and Duval, BP1 F-63770 Les Ancizes (France); Lamesle, P.; Delagnes, D. [Institut Clément Ader, Mines Albi, Campus Jarlard, F-81013 Albi Cedex 09 (France); Povoden-Karadeniz, E. [Christian Doppler Laboratory for Early Stages of Precipitation, Vienna University of Technology, Favoritenstrasse 9-11, A-1040 Vienna (Austria)

    2013-04-15

    Highlights: ► Improvement of a carbide selective extraction method. ► Determination of experimental data on the Fe–C–Cr–Mo–V system for carbides above 900 °C: crystallographic structures and compositions of precipitates, matrix composition. ► High molybdenum solubility in FCC carbides. ► Improvement of thermodynamic databases from experimental results. ► Validation of the optimized database with different compositions steels. -- Abstract: A technique for the microstructural study of steels, based on the use of matrix dissolution to collect the very low number density precipitates formed in martensitic steels, has been considerably improved. This technique was applied to two different grades of alloy, characterized by high nickel and cobalt contents and varying chromium, molybdenum and vanadium contents. The technique was implemented at temperatures ranging between 900 °C and 1000 °C, in order to accurately determine experimental data including the crystallographic structure and chemical composition of the carbides, the carbide solvus temperatures, and variations in the chemical composition of the matrix. These experimental investigations reveal that the solubility of molybdenum in FCC carbides can be very high. These results have been compared with the behavior predicted by computational thermodynamics, and used to evaluate and improve the thermodynamic Matcalc steel database. This upgraded database has been validated on three other steels with different chemical compositions, characterized by the same Fe–Cr–Mo–V–C system.

  16. Fundamental studies of oral contrast agents for MR. Comparison of manganese agent and iron agent

    International Nuclear Information System (INIS)

    Fujita, Osamu; Hiraishi, Kumiko; Suginobu, Yoshito; Takeuchi, Masayasu; Narabayashi, Isamu

    1996-01-01

    We investigated and compared signal intensity and the effect of imaging the upper abdomen with blueberry juice (B.J.), a Mn agent utilizing the properties of paramagnetic metals, and FerriSeltz (F.S.), an iron agent. Since the relaxation effect was much stronger with B.J. than with F.S., the signal intensity required of a peroral contrast agent was able to be obtained at a much lower concentration of B.J. In imaging the upper abdomen, B.J. had a positive effect on imaging in T1-weighted images, and a negative effect in T2-weighted images. F.S. had a positive imaging effect in both, and because it showed extremely high signals in T2-weighted images, motion artifact arose. (author)

  17. Manganese, Iron, and Sulfur Cycling in a Coastal Marine Sediment, Aarhus Bay, Denmark

    DEFF Research Database (Denmark)

    THAMDRUP, B.; FOSSING, H.; JØRGENSEN, BB

    1994-01-01

    -scale measurements showed that it extended to the upper 0-2.5 mm during summer, when the zones of Mn and Fe reduction were compressed towards the surface. Most of the H2S produced precipitated as iron sulfides and S0 by reaction with Fe. Both Fe(III) and a nonsulfur-bound authigenic Fe(II) pool reacted efficiently...... of a diatom spring bloom caused distinct maxima in SRR and Mn2+ at 0.5-1 cm depth within two weeks. In autumn, the reactive Mn oxides were depleted due to a net release of Mn2+ to the water column. Thus, the Mn cycle extended significantly into the water column, while a constant Fe pool over the year suggests...

  18. Hydrothermal synthesis and crystal structure of a new molybdenum oxide compound with manganese-o-phen subunit: [Mn(o-phen)(H2O)MoO4]·H2O (o-phen=o-phenanthroline)

    International Nuclear Information System (INIS)

    Zhang Quanzheng; Lu Canzhong; Yang Wenbin; Chen Shumei; Yu Yaqin; He Xiang; Yan Ying; Liu Jiuhui; Xu Xinjiang; Xia Changkun; Wu Xiaoyuan; Chen Lijuan

    2004-01-01

    A new one-dimensional molybdenum oxide compound with manganese-o-phen subunit: [Mn(o-phen)(H 2 O)MoO 4 ]·H 2 O (1) (o-phen=o-phenanthroline) was synthesized by the hydrothermal reaction of Na 2 MoO 4 ·2H 2 O, MnSO 4 ·H 2 O, oxalic acid, o-phenanthroline (o-phen) and water. Its structure was determined by elemental analyses, ESR spectrum, TG analysis, IR spectrum and single-crystal X-ray diffraction. Compound 1 crystallizes in triclinic system, space group P-1 with a=7.0401(2) A, b=10.4498(2) A, c=10.5720(2) A, α=73.26(7) deg., β=83.34(8) deg., γ=77.33(9) deg., V=725.5089(0) A 3 , Z=2, and R 1 =0.0322 for 2337 observed reflections. Compound 1 exhibits one-dimensional chain structure. The chains are linked up via hydrogen bonding to 2D layers, which are further assembled through π-π stacking interactions to a 3D supermolecular structure

  19. 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)

  20. Novel mode of microbial energy metabolism: organic carbon oxidation coupled to dissimilatory reduction of iron or manganese.

    Science.gov (United States)

    Lovley, D R; Phillips, E J

    1988-06-01

    A dissimilatory Fe(III)- and Mn(IV)-reducing microorganism was isolated from freshwater sediments of the Potomac River, Maryland. The isolate, designated GS-15, grew in defined anaerobic medium with acetate as the sole electron donor and Fe(III), Mn(IV), or nitrate as the sole electron acceptor. GS-15 oxidized acetate to carbon dioxide with the concomitant reduction of amorphic Fe(III) oxide to magnetite (Fe(3)O(4)). When Fe(III) citrate replaced amorphic Fe(III) oxide as the electron acceptor, GS-15 grew faster and reduced all of the added Fe(III) to Fe(II). GS-15 reduced a natural amorphic Fe(III) oxide but did not significantly reduce highly crystalline Fe(III) forms. Fe(III) was reduced optimally at pH 6.7 to 7 and at 30 to 35 degrees C. Ethanol, butyrate, and propionate could also serve as electron donors for Fe(III) reduction. A variety of other organic compounds and hydrogen could not. MnO(2) was completely reduced to Mn(II), which precipitated as rhodochrosite (MnCO(3)). Nitrate was reduced to ammonia. Oxygen could not serve as an electron acceptor, and it inhibited growth with the other electron acceptors. This is the first demonstration that microorganisms can completely oxidize organic compounds with Fe(III) or Mn(IV) as the sole electron acceptor and that oxidation of organic matter coupled to dissimilatory Fe(III) or Mn(IV) reduction can yield energy for microbial growth. GS-15 provides a model for how enzymatically catalyzed reactions can be quantitatively significant mechanisms for the reduction of iron and manganese in anaerobic environments.

  1. Zinc, iron, manganese and copper uptake requirement in response to nitrogen supply and the increased grain yield of summer maize.

    Directory of Open Access Journals (Sweden)

    Yanfang Xue

    Full Text Available The relationships between grain yields and whole-plant accumulation of micronutrients such as zinc (Zn, iron (Fe, manganese (Mn and copper (Cu in maize (Zea mays L. were investigated by studying their reciprocal internal efficiencies (RIEs, g of micronutrient requirement in plant dry matter per Mg of grain. Field experiments were conducted from 2008 to 2011 in North China to evaluate RIEs and shoot micronutrient accumulation dynamics during different growth stages under different yield and nitrogen (N levels. Fe, Mn and Cu RIEs (average 64.4, 18.1 and 5.3 g, respectively were less affected by the yield and N levels. ZnRIE increased by 15% with an increased N supply but decreased from 36.3 to 18.0 g with increasing yield. The effect of cultivars on ZnRIE was similar to that of yield ranges. The substantial decrease in ZnRIE may be attributed to an increased Zn harvest index (from 41% to 60% and decreased Zn concentrations in straw (a 56% decrease and grain (decreased from 16.9 to 12.2 mg kg-1 rather than greater shoot Zn accumulation. Shoot Fe, Mn and Cu accumulation at maturity tended to increase but the proportions of pre-silking shoot Fe, Cu and Zn accumulation consistently decreased (from 95% to 59%, 90% to 71% and 91% to 66%, respectively. The decrease indicated the high reproductive-stage demands for Fe, Zn and Cu with the increasing yields. Optimized N supply achieved the highest yield and tended to increase grain concentrations of micronutrients compared to no or lower N supply. Excessive N supply did not result in any increases in yield or micronutrient nutrition for shoot or grain. These results indicate that optimized N management may be an economical method of improving micronutrient concentrations in maize grain with higher grain yield.

  2. Cobalt-Iron-Manganese Catalysts for the Conversion of End-of-Life-Tire-Derived Syngas into Light Terminal Olefins.

    Science.gov (United States)

    Falkenhagen, Jan P; Maisonneuve, Lise; Paalanen, Pasi P; Coste, Nathalie; Malicki, Nicolas; Weckhuysen, Bert M

    2018-03-26

    Co-Fe-Mn/γ-Al 2 O 3 Fischer-Tropsch synthesis (FTS) catalysts were synthesized, characterized and tested for CO hydrogenation, mimicking end-of-life-tire (ELT)-derived syngas. It was found that an increase of C 2 -C 4 olefin selectivities to 49 % could be reached for 5 wt % Co, 5 wt % Fe, 2.5 wt % Mn/γ-Al 2 O 3 with Na at ambient pressure. Furthermore, by using a 5 wt % Co, 5 wt % Fe, 2.5 wt % Mn, 1.2 wt % Na, 0.03 wt % S/γ-Al 2 O 3 catalyst the selectivity towards the fractions of C 5+ and CH 4 could be reduced, whereas the selectivity towards the fraction of C 4 olefins could be improved to 12.6 % at 10 bar. Moreover, the Na/S ratio influences the ratio of terminal to internal olefins observed as products, that is, a high Na loading prevents the isomerization of primary olefins, which is unwanted if 1,3-butadiene is the target product. Thus, by fine-tuning the addition of promoter elements the volume of waste streams that need to be recycled, treated or upgraded during ELT syngas processing could be reduced. The most promising catalyst (5 wt % Co, 5 wt % Fe, 2.5 wt % Mn, 1.2 wt % Na, 0.03 wt % S/γ-Al 2 O 3 ) has been investigated using operando transmission X-ray microscopy (TXM) and X-ray diffraction (XRD). It was found that a cobalt-iron alloy was formed, whereas manganese remained in its oxidic phase. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Manganese associated nanoparticles agglomerate of iron(III) oxide: synthesis, characterization and arsenic(III) sorption behavior with mechanism.

    Science.gov (United States)

    Gupta, Kaushik; Maity, Arjun; Ghosh, Uday Chand

    2010-12-15

    Three samples of manganese associated hydrous iron(III) oxide (MNHFO), prepared by incinerating metal hydroxide precipitate at T (± 5)=90, 300 and 600°C, showed increase of crystalline nature in XRD patterns with decreasing As(III) removal percentages. TEM images showed the increase of crystallinity from sample-1 (MNHFO-1) to sample-3 (MNHFO-3). Dimensions (nm) of particles estimated were 5.0, 7.0 and 97.5. Optimization of pH indicated that MNHFO-1 could remove aqueous As(III) efficiently at pH between 3.0 and 7.0. Kinetic and equilibrium data of reactions under the experimental conditions described the pseudo-second order and the Langmuir isotherm equations very well, respectively. The Langmuir capacity (q(m)) estimated was 691.04 mmol kg(-1). The values of enthalpy, Gibb's free energy and entropy changes (ΔH(0)=+23.23 kJ mol(-1), ΔG(0)=-3.43 to -7.20 kJ mol(-1) at T=283-323K, ΔS(0)=+0.094 kJ mol(-1)K(-1)) suggested that the reaction was endothermic, spontaneous and took place with increasing entropy. The As(III) sorbed by MNHFO-1 underwent surface oxidation to As(V), and evidences appeared from the XPS and FTIR investigations. MNHFO-1 packed column (internal diameter: 1.0 cm, height: 3.7 cm) filtered 11.5 dm(3) groundwater (105 μg As dm(-3)) with reducing arsenic concentration to ≤ 10 μg dm(-3). Copyright © 2010 Elsevier B.V. All rights reserved.

  4. Low-temperature superacid catalysis: Reactions of n - butane and propane catalyzed by iron- and manganese-promoted sulfated zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Tsz-Keung, Cheung; d`Itri, J.L.; Lange, F.C.; Gates, B.C. [Univ. of California, Davis, CA (United States)

    1995-12-31

    The primary goal of this project is to evaluate the potential value of solid superacid catalysts of the sulfated zirconia type for light hydrocarbon conversion. The key experiments catalytic testing of the performance of such catalysts in a flow reactor fed with streams containing, for example, n-butane or propane. Fe- and Mn-promoted sulfated zirconia was used to catalyze the conversion of n-butane at atmospheric pressure, 225-450{degrees}C, and n-butane partial pressures in the range of 0.0025-0.01 atm. At temperatures <225{degrees}C, these reactions were accompanied by cracking; at temperatures >350{degrees}C, cracking and isomerization occurred. Catalyst deactivation, resulting at least in part from coke formation, was rapid. The primary cracking products were methane, ethane, ethylene, and propylene. The observation of these products along with an ethane/ethylene molar ratio of nearly 1 at 450{degrees}C is consistent with cracking occurring, at least in part, by the Haag-Dessau mechanism, whereby the strongly acidic catalyst protonates n-butane to give carbonium ions. The rate of methane formation from n-butane cracking catalyzed by Fe- and Mn-promoted sulfated zirconia at 450{degrees}C was about 3 x 10{sup -8} mol/(g of catalyst {center_dot}s). The observation of butanes, pentanes, and methane as products is consistent with Olah superacid chemistry, whereby propane is first protonated by a very strong acid to form a carbonium ion. The carbonium ion then decomposes into methane and an ethyl cation which undergoes oligocondensation reactions with propane to form higher molecular weight alkanes. The results are consistent with the identification of iron- and manganese-promoted sulfated zirconia as a superacid.

  5. Trace Element Status (Zinc, Copper, Selenium, Iron, Manganese) in Patients with Long-Term Home Parenteral Nutrition.

    Science.gov (United States)

    Dastych, Milan; Šenkyřík, Michal; Dastych, Milan; Novák, František; Wohl, Petr; Maňák, Jan; Kohout, Pavel

    2016-01-01

    The objective of the present study was to determine concentrations of zinc (Zn), copper (Cu), iron (Fe), selenium (Se) in blood plasma and manganese (Mn) in the whole blood in patients with long-term home parenteral nutrition (HPN) in comparison to the control group. We examined 68 patients (16 men and 52 women) aged from 28 to 68 years on a long-term HPN lasting from 4 to 96 months. The short bowel syndrome was an indication for HPN. The daily doses of Zn, Cu, Fe, Se and Mn in the last 3 months were determined. No significant differences in blood plasma were found for Zn, Cu and Fe in patients with HPN and in the control group (p > 0.05). The concentration of Mn in whole blood was significantly increased in HPN patients (p < 0.0001), while Se concentration in these patients was significantly decreased (p < 0.005). The concentration of Mn in the whole blood of 16 patients with cholestasis was significantly increased compared to the patients without cholestasis (p < 0.001). The Cu concentration was increased with no statistical significance. In long-term HPN, the status of trace elements in the patients has to be continually monitored and the daily substitution doses of these elements have to be flexibly adjusted. Dosing schedule needs to be adjusted especially in cases of cholestatic hepatopathy. A discussion about the optimal daily dose of Mn in patients on HPN is appropriate. For clinical practice, the availability of a substitution mixture of trace elements lacking Mn would be advantageous. © 2016 S. Karger AG, Basel.

  6. Low iron stores are related to higher blood concentrations of manganese, cobalt and cadmium in non-smoking, Norwegian women in the HUNT 2 study

    International Nuclear Information System (INIS)

    Margrete Meltzer, Helle; Lise Brantsaeter, Anne; Borch-Iohnsen, Berit; Ellingsen, Dag G.; Alexander, Jan; Thomassen, Yngvar; Stigum, Hein; Ydersbond, Trond A.

    2010-01-01

    Low iron (Fe) stores may influence absorption or transport of divalent metals in blood. To obtain more knowledge about such associations, the divalent metal ions cadmium (Cd), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn) and lead (Pb) and parameters of Fe metabolism (serum ferritin, haemoglobin (Hb) and transferrin) were investigated in 448 healthy, menstruating non-smoking women, age 20-55 years (mean 38 years), participating in the Norwegian HUNT 2 study. The study population was stratified for serum ferritin: 257 were iron-depleted (serum ferritin 2 for the models were 0.28, 0.48 and 0.34, respectively. Strong positive associations between blood concentrations of Mn, Co and Cd were observed, also when controlled for their common association with ferritin. Apart from these associations, the models showed no significant interactions between the six divalent metals studied. Very mild anaemia (110≤Hb<120 g/L) did not seem to have any effect independent of low ferritin. Approximately 26% of the women with iron deficiency anaemia had high concentrations of all of Mn, Co and Cd as opposed to 2.3% of iron-replete subjects. The results confirm that low serum ferritin may have an impact on body kinetics of certain divalent metal ions, but not all. Only a fraction of women with low iron status exhibited an increased blood concentration of divalent metals, providing indication of complexities in the body's handling of these metals.

  7. 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)

  8. Recovery of molybdenum in froth flotation

    International Nuclear Information System (INIS)

    Parlman, R.M.; Bresson, C.R.

    1981-01-01

    Beta-mercaptoethanol has been found to be an effective suppressant for such minerals as copper, iron and lead in a molybdenum sulfide ore froth flotation operation. The recovery process and a suppressant utilizing said compound are claimed

  9. Low iron stores are related to higher blood concentrations of manganese, cobalt and cadmium in non-smoking, Norwegian women in the HUNT 2 study

    Energy Technology Data Exchange (ETDEWEB)

    Margrete Meltzer, Helle, E-mail: helle.margrete.meltzer@fhi.no [Division of Environmental Medicine, Department of Food Safety and Nutrition, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo (Norway); Lise Brantsaeter, Anne [Division of Environmental Medicine, Department of Food Safety and Nutrition, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo (Norway); Borch-Iohnsen, Berit [Institute of Basic Medical Sciences, Department of Nutrition, University of Oslo, PO Box 1046 Blindern, N-0316 Oslo (Norway); Ellingsen, Dag G. [National Institute of Occupational Health, PO Box 8149 Dep, N-0033 Oslo (Norway); Alexander, Jan [Division of Environmental Medicine, Department of Food Safety and Nutrition, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo (Norway); Thomassen, Yngvar [National Institute of Occupational Health, PO Box 8149 Dep, N-0033 Oslo (Norway); Stigum, Hein [Division of Epidemiology, Department of Chronic Diseases, Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo (Norway); Ydersbond, Trond A. [Statistics Norway, P.Box 8131 Dep, N-0033 Oslo (Norway)

    2010-07-15

    Low iron (Fe) stores may influence absorption or transport of divalent metals in blood. To obtain more knowledge about such associations, the divalent metal ions cadmium (Cd), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn) and lead (Pb) and parameters of Fe metabolism (serum ferritin, haemoglobin (Hb) and transferrin) were investigated in 448 healthy, menstruating non-smoking women, age 20-55 years (mean 38 years), participating in the Norwegian HUNT 2 study. The study population was stratified for serum ferritin: 257 were iron-depleted (serum ferritin <12 {mu}g/L) and 84 had iron deficiency anaemia (serum ferritin <12 {mu}g/L and Hb<120 g/L). The low ferritin group had increased blood concentrations of Mn, Co and Cd but normal concentrations of Cu, Zn and Pb. In multiple regression models, ferritin emerged as the main determinant of Mn, Co and Cd (p<0.001), while no significant associations with Cu, Zn and Pb were found. Adjusted r{sup 2} for the models were 0.28, 0.48 and 0.34, respectively. Strong positive associations between blood concentrations of Mn, Co and Cd were observed, also when controlled for their common association with ferritin. Apart from these associations, the models showed no significant interactions between the six divalent metals studied. Very mild anaemia (110{<=}Hb<120 g/L) did not seem to have any effect independent of low ferritin. Approximately 26% of the women with iron deficiency anaemia had high concentrations of all of Mn, Co and Cd as opposed to 2.3% of iron-replete subjects. The results confirm that low serum ferritin may have an impact on body kinetics of certain divalent metal ions, but not all. Only a fraction of women with low iron status exhibited an increased blood concentration of divalent metals, providing indication of complexities in the body's handling of these metals.

  10. A Predictive Framework for Thermomechanical Fatigue Life of High Silicon Molybdenum Ductile Cast Iron Based on Considerations of Strain Energy Dissipation

    Science.gov (United States)

    Avery, Katherine R.

    Isothermal low cycle fatigue (LCF) and anisothermal thermomechanical fatigue (TMF) tests were conducted on a high silicon molybdenum (HiSiMo) cast iron for temperatures up to 1073K. LCF and out-of-phase (OP) TMF lives were significantly reduced when the temperature was near 673K due to an embrittlement phenomenon which decreases the ductility of HiSiMo at this temperature. In this case, intergranular fracture was predominant, and magnesium was observed at the fracture surface. When the thermal cycle did not include 673K, the failure mode was predominantly transgranular, and magnesium was not present on the fracture surface. The in-phase (IP) TMF lives were unaffected when the thermal cycle included 673K, and the predominant failure mode was found to be transgranular fracture, regardless of the temperature. No magnesium was present on the IP TMF fracture surfaces. Thus, the embrittlement phenomenon was found to contribute to fatigue damage only when the temperature was near 673K and a tensile stress was present. To account for the temperature- and stress-dependence of the embrittlement phenomenon on the TMF life of HiSiMo cast iron, an original model based on the cyclic inelastic energy dissipation is proposed which accounts for temperature-dependent differences in the rate of fatigue damage accumulation in tension and compression. The proposed model has few empirical parameters. Despite the simplicity of the model, the predicted fatigue life shows good agreement with more than 130 uniaxial low cycle and thermomechanical fatigue tests, cyclic creep tests, and tests conducted at slow strain rates and with hold times. The proposed model was implemented in a multiaxial formulation and applied to the fatigue life prediction of an exhaust manifold subjected to severe thermal cycles. The simulation results show good agreement with the failure locations and number of cycles to failure observed in a component-level experiment.

  11. Study of granitic biotites by X-ray fluorescence analysis: determination of iron, manganese, titanium, calcium, potassium, silicon and aluminium; Estudio de biotitas graniticas por fluorescencia de rayos X: Determinacion de hierro, manganeso, titanio, calcio, potasio, silicio y aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Toubes, R. O.; Bermudez Polonio, J.

    1968-07-01

    A method for the quantitative determination of iron, manganese, titanium, calcium potassium, silicon, and aluminium, is reported, Sample preparation is carried out by the miniature flux technique, and rubidium is used as internal standard for silicon and aluminium. (Author) 5 refs.

  12. Study of the quenching and subsequent return to room temperature of uranium-chromium, uranium-iron, and uranium-molybdenum alloys containing only small amounts of the alloying element

    International Nuclear Information System (INIS)

    Delaplace, J.

    1960-09-01

    By means of an apparatus which makes possible thermal pre-treatments in vacuo, quenching carried out in a high purity argon atmosphere, and simultaneous recording of time temperature cooling and thermal contraction curves, the author has examined the transformations which occur in uranium-chromium, uranium-iron and uranium-molybdenum alloys during their quenching and subsequent return to room temperature. For uranium-chromium and uranium-iron alloys, the temperature at which the γ → β transformation starts varies very little with the rate of cooling. For uranium-molybdenum alloys containing 2,8 atom per cent of Mo, this temperature is lowered by 120 deg. C for a cooling rate of 500 deg. C/mn. The temperature at which the β → α transformation starts is lowered by 170 deg. C for a cooling rate of 500 deg. C/mn in the case of uranium-chromium alloy containing 0,37 atom per cent of Cr. The temperature is little affected in the case of uranium-iron alloys. The addition of chromium or iron makes it possible to conserve the form β at ordinary temperatures after quenching from the β and γ regions. The β phase is particularly unstable and changes into needles of the α form even at room temperatures according to an autocatalytic transformation law similar to the austenitic-martensitic transformation law in the case of iron. The β phase obtained by quenching from the β phase region is more stable than that obtained by quenching from the γ region. Chromium is a more effective stabiliser of the β phase than is iron. Unfortunately it causes serious surface cracking. The β → α transformation in uranium-chromium alloys has been followed at room temperature by means of micro-cinematography. The author has not observed the direct γ → α transformation in uranium-molybdenum alloys containing 2,8 per cent of molybdenum even for cooling rates of up to 2000 deg. C/s. He has however observed the formation of several martensitic structures. (author) [fr

  13. Combined Effects of Copper and Tin at Intermediate Level of Manganese on the Structure and Properties of As-Cast Nodular Graphite Cast Iron

    Directory of Open Access Journals (Sweden)

    Lacaze J.

    2017-06-01

    Full Text Available Copper, manganese and tin are commonly used as pearlite promoter elements in cast irons. A number of studies have been aimed at quantitatively evaluate the effect of each of these elements, individually or at given levels of the others. As a matter of fact, while tin may be necessary for achieving a fully pearlitic matrix, it is known that when in excess it is detrimental for mechanical properties. As the pearlite promoting effect of each of those elements is totally different, it is of real interest to know the optimum combination of them for a given cooling rate. The present report is a first part of a work dedicated at characterizing the best alloying levels in terms of room temperature mechanical properties of as-cast pearlitic materials.

  14. Mineral resource of the month: manganese

    Science.gov (United States)

    Corathers, Lisa A.

    2012-01-01

    Manganese is a silver-colored metal resembling iron and often found in conjunction with iron. The earliest-known human use of manganese compounds was in the Stone Age, when early humans used manganese dioxide as pigments in cave paintings. In ancient Rome and Egypt, people started using it to color or remove the color from glass - a practice that continued to modern times. Today, manganese is predominantly used in metallurgical applications as an alloying addition, particularly in steel and cast iron production. Steel and cast iron together provide the largest market for manganese (historically 85 to 90 percent), but it is also alloyed with nonferrous metals such as aluminum and copper. Its importance to steel cannot be overstated, as almost all types of steel contain manganese and could not exist without it.

  15. Survey of heavy metal pollution (copper, lead, zinc, cadmium, iron and manganese in drinking water resources of Nurabad city, Lorestan, Iran 2013

    Directory of Open Access Journals (Sweden)

    GHodratolah Shams Khorramabadi

    2016-09-01

    Full Text Available Background: Healthy water passes through the pipelines from supply resources to consuming places in which passing from these stages may cause some cases of contamination like heavy metal contamination. Therefore, the aim of this study was to evaluate the contamination of heavy metals (copper, lead, zinc, cadmium, iron, and manganese in water resources of Nurabad city of Lorestan in 2013. Materials and Methods: In this cross-sectional study, samples were collected from 7 wells of drinking water and 2 water storage tanks during 6 months in Nurabad. So that, heavy metal parameters such as copper, lead, zinc, cadmium, iron, and manganese were measured using an atomic absorption device and also electrical conductivity, sulfate, chloride and total dissolved solids were also measured in accordance with standard methods. Results: Results indicated that the concentration of studied metals in water sources was lower than the national standards and World Health Organization standard, and in the water supply system the concentration of some metals was more than standard level. Moreover, the results showed that the concentration of studied heavy metals were more in winter than in autumn. Conclusion: Generally, in the water resources of Nurabad city the concentration of studied heavy metals was lower than the national standards and World Health Organization standard and there are not problems for water consumers. However, due to public health and the presence of a high concentration of these metals in the distribution supply, the heavy metal concentration in drinking water of this region should be monitored regularly by responsible organizations.

  16. Study of the recrystallization mechanisms of ultra-high purity iron doped with carbon, manganese and phosphorus; Etude des mecanismes de recristallisation dans le fer de ultra-haute purete dope en carbone, manganese et phosphore

    Energy Technology Data Exchange (ETDEWEB)

    Lesne, L.

    2000-07-04

    High purity steels have the potential to improve deep drawing properties for automotive applications. Understanding the influence of the chemical composition on the recrystallization mechanisms and on texture development should help to improve their properties. We have studied the influence of 10 ppm of carbon, 1000 ppm of manganese and 120 ppm of phosphorus on the recrystallization mechanisms of ultra-high purity iron (UHP iron > 99.997%). For this purpose we used 4 materials: one undoped (UHP), one doped with C, one doped with C, Mn and one doped With C, Mn, P. In order to restrict grain coarsening in the hot strips, hot rolling was performed in the ferritic region, in one pass of 80% thickness reduction. The hot bands were then fully recrystallized but exhibited non-isotropic textures, with in particular an intense Goss [110]<001> component for the doped materials. The hot-bands were subsequently cold rolled down to a thickness of 0.8 mm corresponding to a thickness reduction of 80%, and then continuously annealed at 10 deg. C/s. The recrystallization kinetics are delayed with the addition of doping elements. In particular, the incubation time for nucleation is shifted towards higher temperatures while the recrystallization velocity increases. The textures of the fully recrystallized materials exhibit a strong Goss component prejudicial for deep drawing properties. We have established that this component can only appear if coarse grains and carbon in solid solution were simultaneously present in the material before deformation. Characterisation of the cold deformed state enabled us to evaluate the energy stored during deformation as a function of the material composition and the grain orientation: - the overall stored energy increases with the doping elements content. - the stored energy in the {gamma} fibre grains is greater than in the {alpha} fibre grains: 30 J/mol for the {gamma} fibre instead of 5 J/mol for the {alpha} fibre, in the undoped UHP iron. In the

  17. Manganese doped-iron oxide nanoparticle clusters and their potential as agents for magnetic resonance imaging and hyperthermia

    KAUST Repository

    Casula, Maria F.

    2016-06-10

    A simple, one pot method to synthesize water-dispersible Mn doped iron oxide colloidal clusters constructed of nanoparticles arranged into secondary flower-like structures was developed. This method allows the successful incorporation and homogeneous distribution of Mn within the nanoparticle iron oxide clusters. The formed clusters retain the desired morphological and structural features observed for pure iron oxide clusters, but possess intrinsic magnetic properties that arise from Mn doping. They show distinct performance as imaging contrast agents and excellent characteristics as heating mediators in magnetic fluid hyperthermia. It is expected that the outcomes of this study will open up new avenues for the exploitation of doped magnetic nanoparticle assemblies in biomedicine. © the Owner Societies 2016.

  18. Manganese doped-iron oxide nanoparticle clusters and their potential as agents for magnetic resonance imaging and hyperthermia

    KAUST Repository

    Casula, Maria F.; Conca, Erika; Bakaimi, Ioanna; Sathya, Ayyappan; Materia, Maria Elena; Casu, Alberto; Falqui, Andrea; Sogne, Elisa; Pellegrino, Teresa; Kanaras, Antonios G.

    2016-01-01

    A simple, one pot method to synthesize water-dispersible Mn doped iron oxide colloidal clusters constructed of nanoparticles arranged into secondary flower-like structures was developed. This method allows the successful incorporation and homogeneous distribution of Mn within the nanoparticle iron oxide clusters. The formed clusters retain the desired morphological and structural features observed for pure iron oxide clusters, but possess intrinsic magnetic properties that arise from Mn doping. They show distinct performance as imaging contrast agents and excellent characteristics as heating mediators in magnetic fluid hyperthermia. It is expected that the outcomes of this study will open up new avenues for the exploitation of doped magnetic nanoparticle assemblies in biomedicine. © the Owner Societies 2016.

  19. Determination of hafnium, molybdenum, and vanadium in niobium and niobium-based alloys by atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Ide, Kunikazu; Kobayashi, Takeshi; Sudo, Emiko.

    1985-01-01

    The analytical procedure is as follows: Weigh 1 g of a sample and put it into a 100 cm 3 PTFE beaker. Add 5 ml of distilled water and 5 ml of hydrofluoric acid, and then heat the solution on a hot plate, adding 3 ml of nitric acid dropwise. Dilute the solution to 100 cm 3 with distilled water. When hafnium is determined, add 2 g of diammonium titanium hexafluoride ((NH 4 ) 2 TiF 6 )) before dilution. Working standard solutions are prepared by adding the stock standard solutions of hafnium, molybdenum, and vanadium into niobium solutions. When hafnium is determined, add 2 g of (NH 4 ) 2 TiF 6 and the alloying elements in amounts corresponding to those in sample solutions into the working standard solutions. The tolerable amounts of hydrofluoric acid were 2.9 M, 2.1 M, and 3.1 M and those of nitric acid were 1.0 M, 1.6 M, and 1.6 M for hafnium, molybdenum, and vanadium, respectively. It was found that (NH 4 ) 2 TiF 6 greatly increased the sensitivity for hafnium determination. Niobium showed minus effect for hafnium and plus effect for molybdenum and vanadium. The atomic absorption of molybdenum and vanadium were not influenced by the presence of 20 % of each alloying element, while the atomic absorption of hafnium was given plus effect by 20 % of zirconium, iron, cobalt, nickel, manganese, chromium or vanadium and minus effect by 20 % tungsten. The analytical values of hafnium, molybdenum, and vanadium in niobium-based alloys by this method showed a good agreement with those by X-ray fluorescence analysis. The lower limits of determination (S/N=2) were 0.05, 0.001, and 0.002 % and the relative standard deviation were 3, 1, and 1.5 % for hafnium, molybdenum, and vanadium, respectively. (author)

  20. Manganese-induced hydroxyl radical formation in rat striatum is not attenuated by dopamine depletion or iron chelation in vivo

    NARCIS (Netherlands)

    W.N. Sloot (W.); J. Korf (Jakob); J.F. Koster (Johan); L.E.A. de Wit (Elly); J.-B.P. Gramsbergen (J. B P)

    1996-01-01

    textabstractThe present studies were aimed at investigating the possible roles of dopamine (DA) and iron in production of hydroxyl radicals (.OH) in rat striatum after Mn2+ intoxication. For this purpose, DA depletions were assessed concomitant with in vivo 2,3- and 2,5-dihydroxybenzoic acid (DHBA)

  1. Synthesis of carbon nanotubes by CVD method using iron and molybdenum-based catalysts supported on ceramic matrices;Sintese de nanotubos de carbono por CVD utilizando catalisadores a base de ferro e molibdenio suportados em matrizes ceramicas

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Ana Paula de Carvalho

    2010-07-01

    Molybdenum is known for its synergistic effect in the synthesis of carbon nanotubes (CNs) by chemical vapor deposition (CVD method). When added to typical catalysts like iron, nickel, and cobalt, even in small quantities, it is increases the yield of these nanostructures. The presence of Mo also has an influence on the type and number of CN walls formed. Although this effect is widely documented in the literature, there is not yet a consensus about the mechanism of action of molybdenum in catalytic systems. The objective of the present work is to study the influence of molybdenum on the catalytic activity of iron nanoparticle-based catalysts supported on magnesium oxide (Fe/MgO system) in the synthesis of carbon nanotubes by the CVD method. The Mo concentration was systematically varied from null to molar ratio values four times greater than the quantity of Fe, and the obtained material (catalysts and carbon nanotubes) were broadly characterized by different techniques. In order to also study the influence of the preparation method on the final composition of the catalytic system phases, the catalytic systems (Fe/MgO e FeMo{sub x}/MgO) were synthesized by two different methods: co-precipitation and impregnation. The greatest CN yields were observed for the catalysts prepared by coprecipitation. The difference was attributed to better dispersion of the Fe and Mo phases in the catalyst ceramic matrix. In the precipitation stage, it was observed the formation of layered double hydroxides whose concentration increased with the Mo content up to the ratio of Mo/Fe equal to 0.2. This phase is related to a better distribution of Fe and Mo in this concentration range. Another important characteristic observed is that the ceramic matrix is not inert. It can react both with Fe and Mo and form the iron solid solution in the magnesium oxide and the phases magnesium-ferrite (MgFe{sub 2}0{sub 4}) and magnesium molybdate (MgMo0{sub 4}). The MgFe{sub 2}0{sub 4} phase is observed in

  2. Streptococcus sanguinis class Ib ribonucleotide reductase: high activity with both iron and manganese cofactors and structural insights.

    Science.gov (United States)

    Makhlynets, Olga; Boal, Amie K; Rhodes, Delacy V; Kitten, Todd; Rosenzweig, Amy C; Stubbe, JoAnne

    2014-02-28

    Streptococcus sanguinis is a causative agent of infective endocarditis. Deletion of SsaB, a manganese transporter, drastically reduces S. sanguinis virulence. Many pathogenic organisms require class Ib ribonucleotide reductase (RNR) to catalyze the conversion of nucleotides to deoxynucleotides under aerobic conditions, and recent studies demonstrate that this enzyme uses a dimanganese-tyrosyl radical (Mn(III)2-Y(•)) cofactor in vivo. The proteins required for S. sanguinis ribonucleotide reduction (NrdE and NrdF, α and β subunits of RNR; NrdH and TrxR, a glutaredoxin-like thioredoxin and a thioredoxin reductase; and NrdI, a flavodoxin essential for assembly of the RNR metallo-cofactor) have been identified and characterized. Apo-NrdF with Fe(II) and O2 can self-assemble a diferric-tyrosyl radical (Fe(III)2-Y(•)) cofactor (1.2 Y(•)/β2) and with the help of NrdI can assemble a Mn(III)2-Y(•) cofactor (0.9 Y(•)/β2). The activity of RNR with its endogenous reductants, NrdH and TrxR, is 5,000 and 1,500 units/mg for the Mn- and Fe-NrdFs (Fe-loaded NrdF), respectively. X-ray structures of S. sanguinis NrdIox and Mn(II)2-NrdF are reported and provide a possible rationale for the weak affinity (2.9 μM) between them. These streptococcal proteins form a structurally distinct subclass relative to other Ib proteins with unique features likely important in cluster assembly, including a long and negatively charged loop near the NrdI flavin and a bulky residue (Thr) at a constriction in the oxidant channel to the NrdI interface. These studies set the stage for identifying the active form of S. sanguinis class Ib RNR in an animal model for infective endocarditis and establishing whether the manganese requirement for pathogenesis is associated with RNR.

  3. 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 ...

  4. Carbon, chromium and molybdenum contents

    International Nuclear Information System (INIS)

    Sinatora, A; Goldenstein, H.; Mei, P.R.; Albertin, E.; Fuoco, R.; Mariotto, C.L.

    1992-01-01

    This work describes solidification experiments on white cast iron, with 15 and 20% of chromium, 2.3, 3.0 and 3.6 % of carbon and 0.0, 1.5 and 2.5 % of molybdenum in test de samples with 30 mm diameter. Measurements were performed on the austenite and eutectic formation arrests, the number of the eutectic carbide particles relative to the total and the eutectic volumes, and the volume fraction of the primary austenite

  5. Hydroxyapatite formation on titania-based materials in a solution mimicking body fluid: Effects of manganese and iron addition in anatase.

    Science.gov (United States)

    Shin, Euisup; Kim, Ill Yong; Cho, Sung Baek; Ohtsuki, Chikara

    2015-03-01

    Hydroxyapatite formation on the surfaces of implanted materials plays an important role in osteoconduction of bone substitutes in bone tissues. Titania hydrogels are known to instigate hydroxyapatite formation in a solution mimicking human blood plasma. To date, the relationship between the surface characteristics of titania and hydroxyapatite formation on its surface remains unclear. In this study, titania powders with varying surface characteristics were prepared by addition of manganese or iron to examine hydroxyapatite formation in a type of simulated body fluid (Kokubo solution). Hydroxyapatite formation was monitored by observation of deposited particles with scale-like morphology on the prepared titania powders. The effect of the titania surface characteristics, i.e., crystal structure, zeta potential, hydroxy group content, and specific surface area, on hydroxyapatite formation was examined. Hydroxyapatite formation was observed on the surface of titania powders that were primarily anatase, and featured a negative zeta potential and low specific surface areas irrespective of the hydroxy group content. High specific surface areas inhibited the formation of hydroxyapatite because calcium and phosphate ions were mostly consumed by adsorption on the titania surface. Thus, these surface characteristics of titania determine its osteoconductivity following exposure to body fluid. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Characterization of iron and manganese minerals and their associated microbiota in different mine sites to reveal the potential interactions of microbiota with mineral formation.

    Science.gov (United States)

    Park, Jin Hee; Kim, Bong-Soo; Chon, Chul-Min

    2018-01-01

    Different environmental conditions such as pH and dissolved elements of mine stream induce precipitation of different minerals and their associated microbial community may vary. Therefore, mine precipitates from various environmental conditions were collected and their associated microbiota were analyzed through metagenomic DNA sequencing. Various Fe and Mn minerals including ferrihydrite, schwertmannite, goethite, birnessite, and Mn-substituted δ-FeOOH (δ-(Fe 1-x , Mn x )OOH) were found in the different environmental conditions. The Fe and Mn minerals were enriched with toxic metal(loid)s including As, Cd, Ni and Zn, indicating they can act as scavengers of toxic metal(loid)s in mine streams. Under acidic conditions, Acidobacteria was dominant phylum and Gallionella (Fe oxidizing bacteria) was the predominant genus in these Fe rich environments. Manganese oxidizing bacteria, Hyphomicrobium, was found in birnessite forming environments. Leptolyngbya within Cyanobacteria was found in Fe and Mn oxidizing environments, and might contribute to Fe and Mn oxidation through the production of molecular oxygen. The potential interaction of microbial community with minerals in mine sites can be traced by analysis of microbial community in different Fe and Mn mineral forming environments. Iron and Mn minerals contribute to the removal of toxic metal(loid)s from mine water. Therefore, the understanding characteristics of mine precipitates and their associated microbes helps to develop strategies for the management of contaminated mine water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Synthesis of nanostructured mixed oxide CeO2-Mn2O3 and investigation of their sorption ability for arsenic, ammoniac, iron, manganese

    International Nuclear Information System (INIS)

    Luu Minh Dai; Dao Ngoc Nhiem; Duong Thi Lim

    2012-01-01

    The nanostrutured mixed oxide CeO 2 -Mn 2 O 3 have been synthesised at low temperature (350 o C) by the combustion of gel prepared from polyvinyl alcohol (PVA), Ce (NO 3 ) 4 and Mn(No 3 ) 3 , CeO 2 -Mn 2 O 3 characterizations were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET (Brunauce-Emmet-Teller) measurements. The phase of CeO 2 -Mn 2 O 3 , with large specific surface ares 65.3 m 2 /g was obtained at 350 o C for 2 hours. The nanostructured CeO 2 -Mn 2 O 3 has been investigated for removing iron, manganese, arsenic and ammoniac from water. The sorption characteristics of the nanostrutured CeO 2 -Mn 2 O 3 for AS(V), NH4 + , Fe(III), Mn(II) according to the langmuir isotherm. The sorption capacities of nanostrutured CeO 2 -Mn 2 O 3 are 57.10 mg As(V)g; 154.54 mg NH4 + /g; 72.97 mg Fe(III)/g; 60.27 Mn(II) / g. (author)

  8. Method development for the determination of calcium, copper, magnesium, manganese, iron, potassium, phosphorus and zinc in different types of breads by microwave induced plasma-atomic emission spectrometry.

    Science.gov (United States)

    Ozbek, Nil; Akman, Suleyman

    2016-06-01

    A novel method was developed for the determination of calcium, magnesium, potassium, iron, copper, zinc, and manganese and phosphorous in various kinds of breads samples sold in Turkey by microwave plasma-atomic emission spectrometry (MIP-AES). Breads were dried at 100 °C for one day, ground thoroughly and then digested using nitric acid/hydrogen per oxide (3:1). The analytes in certified reference wheat flour and maize flour samples were determined in the uncertainty limits of the certified values as well as the analytes added to the mixture of ground bread and acid mixture prior to digestion were recovered quantitatively (>90%). Therefore, all determinations were made by linear calibration technique using aqueous standards. The LOD values for Ca, Cu, Fe, K, Mg, Mn, P and Zn were 13.1, 0.28, 4.47, 118, 1.10, 0.41, 7550 and 3.00 ng mL(-1), respectively. No spectral interference was detected at the working wavelengths of the analytes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. In vitro and in vivo corrosion properties of new iron-manganese alloys designed for cardiovascular applications.

    Science.gov (United States)

    Drynda, Andreas; Hassel, Thomas; Bach, Friedrich Wilhelm; Peuster, Matthias

    2015-04-01

    The principle of biodegradation for the production of temporary implant materials (e.g. stents) plays an important role in the treatment of congenital heart defects. In the last decade several attempts have been made with different alloy materials-mainly based on iron and magnesium. None of the currently available materials in this field have demonstrated satisfying results and have therefore not found entry into broad clinical practice. While magnesium or magnesium alloy systems corrode too fast, the corrosion rate of pure iron-stents is too slow for cardiovascular applications. In the last years FeMn alloy systems were developed with the idea that galvanic effects, caused by different electrochemical properties of Fe and Mn, would increase the corrosion rate. In vitro tests with alloys containing up to 30% Mn showed promising results in terms of biocompatibility. This study deals with the development of new FeMn alloy systems with lower Mn concentrations (FeMn 0.5 wt %, FeMn 2.7 wt %, FeMn 6.9 wt %) to avoid Mn toxicity. Our results show, that these alloys exhibit good mechanical features as well as suitable in vitro biocompatibility and corrosion properties. In contrast, the evaluation of these alloys in a mouse model led to unexpected results-even after 9 months no significant corrosion was detectable. Preliminary SEM investigations showed that passivation layers (FeMn phosphates) might be the reason for corrosion resistance. If this can be proved in further experiments, strategies to prevent or dissolve those layers need to be developed to expedite the in vivo corrosion of FeMn alloys. © 2014 Wiley Periodicals, Inc.

  10. X-ray target with substrate of molybdenum alloy

    International Nuclear Information System (INIS)

    Hirsch, H.H.

    1980-01-01

    Rotary targets for x-ray tubes are provided comprising a molybdenum base body alloyed with a stabilizing proportion of iron, silicon, cobalt, tantalum, niobium, hafnium, stable metal oxide, or a mixture of the preceding

  11. Manganese exposure in foundry furnacemen and scrap recycling workers

    DEFF Research Database (Denmark)

    Lander, F; Kristiansen, J; Lauritsen, Jens

    1999-01-01

    Cast iron products are alloyed with small quantities of manganese, and foundry furnacemen are potentially exposed to manganese during tapping and handling of smelts. Manganese is a neurotoxic substance that accumulates in the central nervous system, where it may cause a neurological disorder...

  12. Manganese Oxidation by Bacteria: Biogeochemical Aspects

    Digital Repository Service at National Institute of Oceanography (India)

    Sujith, P.P.; LokaBharathi, P.A.

    Manganese is an essential trace metal that is not as readily oxidizable like iron. Several bacterial groups posses the ability to oxidize Mn effectively competing with chemical oxidation. The oxides of Mn are the strongest of the oxidants, next...

  13. THE ROLE OF IRON IN Deinococcus radiodurans ENGINEERED FOR GROWTH ON TOLUENE AND THE ROLE OF MANGANESE IN THE EXTREME RADIATION RESISTANCE PHENOTYPE

    International Nuclear Information System (INIS)

    Hassan Brim; Elena K. Gaidamakova; Vera Y. Matrosova; Min Zhai; Amudhan Venkateswaran; Marina Omelchenko; Kira S. Makarova; Lawrence P. Wackett; James K. Fredrickson; Michael J. Daly

    2004-01-01

    Toluene and other fuel hydrocarbons are commonly found in association with radionuclides at numerous Department of Energy (DOE) sites, frequently occurring together with Cr(VI) and other heavy metals. In this study, the extremely radiation resistant bacterium Deinococcus radiodurans was engineered for complete toluene mineralization by cloned expression of tod and xyl genes of Pseudomonas putida. The recombinant Tod/Xyl strain showed significant incorporation of carbon from the toluene aromatic ring into cellular macromolecules and carbon dioxide, in the absence or presence of chronic radiation. We have shown that intracellular iron concentrations in wild-type D. radiodurans in minimal medium are exceptionally low and not sufficient to support growth on toluene using Fe-dependent oxygenases cloned from P. putida. Introducing the fur mutation into D. radiodurans increased intracellular Fe levels, and imparted on the engineered strain the ability to grow on meta-toluate as the sole carbon and energy source. The organism's native Cr(VI) reduction capabilities were facilitated by toluene when present as the sole carbon and energy source in natural sediment analogues of DOE contaminated environments. The engineered bacteria were able to oxidize toluene under both minimal and complex nutrient conditions, which is important since both conditions have environmental equivalents in the context of bioremediation processes. As such, the Tod/Xyl strain is providing a model for understanding the role of Fe and reduction of metals coupled to organic contaminant oxidation in aerobic radionuclide contaminated sediments. We have shown that D. radiodurans contains high intracellular manganese levels, and that Mn restriction sensitizes cells to irradiation. We propose that the unusually high Mn/Fe ratio of D. radiodurans facilitates survival by quenching oxidative stress during recovery.

  14. Manganese-incorporated iron(III) oxide-graphene magnetic nanocomposite: synthesis, characterization, and application for the arsenic(III)-sorption from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Nandi, Debabrata; Gupta, Kaushik; Ghosh, Arup Kumar [Presidency University, Department of Chemistry and Biochemistry (India); De, Amitabha [Saha Institute of Nuclear Physics, Chemical Science Division (India); Banerjee, Sangam [Saha Institute of Nuclear Physics, Surface Physics Division (India); Ghosh, Uday Chand, E-mail: ucghosh@yahoo.co.in [Presidency University, Department of Chemistry and Biochemistry (India)

    2012-12-15

    High specific surface area of graphene (GR) has gained special scientific attention in developing magnetic GR nanocomposite aiming to apply for the remediation of diverse environmental problems like point-of-use water purification and simultaneous separation of contaminants applying low external magnetic field (<1.0 T) from ground water. Fabrication of magnetic manganese-incorporated iron(III) oxide (Mn{sub x}{sup 2+}Fe{sub 2-x}{sup 3+}O{sub 4}{sup 2-}) (IMBO)-GR nanocomposite is reported by exfoliating the GR layers. Latest microscopic, spectroscopic, powder X-ray diffraction, BET surface area, and superconducting quantum interference device characterizations showed that the material is a magnetic nanocomposite with high specific surface area (280 m{sup 2} g{sup -1}) and pore volume (0.3362 cm{sup 3} g{sup -1}). Use of this composite for the immobilization of carcinogenic As(III) from water at 300 K and pH {approx}7.0 showed that the nanocomposite has higher binding efficiency with As(III) than the IMBO owing to its high specific surface area. The composite showed almost complete (>99.9 %) As(III) removal ({<=}10 {mu}g L{sup -1}) from water. External magnetic field of 0.3 T efficiently separated the water dispersed composite (0.01 g/10 mL) at room temperature (300 K). Thus, this composite is a promising material which can be used effectively as a potent As(III) immobilizer from the contaminated groundwater (>10 {mu}g L{sup -1}) to improve drinking water quality.

  15. Removal and distribution of iron, manganese, cobalt and nickel within a Pennsylvania constructed wetland treating coal combustion by-product leachate

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Z.H.; Whiting, S.N.; Lin, Z.-Q.; Lytle, C.M.; Qian, J.H.; Terry, N. [University of California, Berkeley, CA (USA). Dept. of Plant and Microbial Biology

    2001-08-01

    A flow-through wetland treatment system was constructed to treat coal combustion by-product leachate from an electrical power station at Springdale, Pennsylvania. In a nine-compartment treatment system, four cattail (Typha latifolia L.) wetland cells (designated Cells 1 through 4) successfully removed iron (Fe) and manganese (Mn) from the inlet water; Fe and Mn concentrations were decreased by an average of 91% in the first year and by 94 and 98% in the second year respectively. Cobalt (Co) and nickel (Ni) were decreased by an average of 39 and 47% in the first and 98 and 63% in the second year respectively. Most of the metal removed by the wetland cells was accumulated in sediments, which constituted the largest sink. Except for Fe, metal concentrations in the sediments tended to be greater in the top 5 cm of sediment than in the 5 to 10 or 10 to 15 cm layers and in Cell 1 than in Cells 2, 3 and 4. Plants constituted a much smaller sink for metals; only 0.91, 4.18, 0.19, and 0.38% of the Fe, Mn, Co and Ni were accumulated annually in the aboveground tissues of cattail, respectively. A greater proportion of each metal (except Mn) was accumulated in cattail fallen litter and submerged Chara (a macroalga) tissues, that is 2.81, 2.75 and 1.05% for Fe, Co and Ni, respectively. Considerably higher concentrations of metals were associated with cattail root than shoots, although Mn was a notable exception. 48 refs., 6 figs., 4 tabs.

  16. THE ROLE OF IRON IN Deinococcus radiodurans ENGINEERED FOR GROWTH ON TOLUENE AND THE ROLE OF MANGANESE IN THE EXTREME RADIATION RESISTANCE PHENOTYPE

    Energy Technology Data Exchange (ETDEWEB)

    Hassan Brim; Elena K. Gaidamakova; Vera Y. Matrosova; Min Zhai; Amudhan Venkateswaran; Marina Omelchenko; Kira S. Makarova; Lawrence P. Wackett; James K. Fredrickson; Michael J. Daly

    2004-03-17

    Toluene and other fuel hydrocarbons are commonly found in association with radionuclides at numerous Department of Energy (DOE) sites, frequently occurring together with Cr(VI) and other heavy metals. In this study, the extremely radiation resistant bacterium Deinococcus radiodurans was engineered for complete toluene mineralization by cloned expression of tod and xyl genes of Pseudomonas putida. The recombinant Tod/Xyl strain showed significant incorporation of carbon from the toluene aromatic ring into cellular macromolecules and carbon dioxide, in the absence or presence of chronic radiation. We have shown that intracellular iron concentrations in wild-type D. radiodurans in minimal medium are exceptionally low and not sufficient to support growth on toluene using Fe-dependent oxygenases cloned from P. putida. Introducing the fur mutation into D. radiodurans increased intracellular Fe levels, and imparted on the engineered strain the ability to grow on meta-toluate as the sole carbon and energy source. The organism's native Cr(VI) reduction capabilities were facilitated by toluene when present as the sole carbon and energy source in natural sediment analogues of DOE contaminated environments. The engineered bacteria were able to oxidize toluene under both minimal and complex nutrient conditions, which is important since both conditions have environmental equivalents in the context of bioremediation processes. As such, the Tod/Xyl strain is providing a model for understanding the role of Fe and reduction of metals coupled to organic contaminant oxidation in aerobic radionuclide contaminated sediments. We have shown that D. radiodurans contains high intracellular manganese levels, and that Mn restriction sensitizes cells to irradiation. We propose that the unusually high Mn/Fe ratio of D. radiodurans facilitates survival by quenching oxidative stress during recovery.

  17. Steel dust in the New York City subway system as a source of manganese, chromium, and iron exposures for transit workers.

    Science.gov (United States)

    Chillrud, Steven N; Grass, David; Ross, James M; Coulibaly, Drissa; Slavkovich, Vesna; Epstein, David; Sax, Sonja N; Pederson, Dee; Johnson, David; Spengler, John D; Kinney, Patrick L; Simpson, H James; Brandt-Rauf, Paul

    2005-03-01

    The United States Clean Air Act Amendments of 1990 reflected increasing concern about potential effects of low-level airborne metal exposure on a wide array of illnesses. Here we summarize results demonstrating that the New York City (NYC) subway system provides an important microenvironment for metal exposures for NYC commuters and subway workers and also describe an ongoing pilot study of NYC transit workers' exposure to steel dust. Results from the TEACH (Toxic Exposure Assessment, a Columbia and Harvard) study in 1999 of 41 high-school students strongly suggest that elevated levels of iron, manganese, and chromium in personal air samples were due to exposure to steel dust in the NYC subway. Airborne concentrations of these three metals associated with fine particulate matter were observed to be more than 100 times greater in the subway environment than in home indoor or outdoor settings in NYC. While there are currently no known health effects at the airborne levels observed in the subway system, the primary aim of the ongoing pilot study is to ascertain whether the levels of these metals in the subway air affect concentrations of these metals or related metabolites in the blood or urine of exposed transit workers, who due to their job activities could plausibly have appreciably higher exposures than typical commuters. The study design involves recruitment of 40 transit workers representing a large range in expected exposures to steel dust, the collection of personal air samples of fine particulate matter, and the collection of blood and urine samples from each monitored transit worker.

  18. Interlaboratory comparison survey of the determination of chromium, manganese, iron, titanium in dust and arsenic, cadmium, cobalt and chromium in urine

    International Nuclear Information System (INIS)

    Christensen, Jytte Molin

    2000-01-01

    This report describes an intercomparison survey based on the Danish External Quality Assessment Scheme (DEQAS). The study was carried out in 1998 for 10 laboratories in a research project on assessment of levels and health effects of airborne particulate matter in mining, metal refining and metal working industries using nuclear and related analytical techniques. The project was co-ordinated by the IAEA. Eight laboratories measured chromium (Cr), manganese (Mn), iron (Fe) and titanium (Ti) in welding fume dust loaded on filters. Six laboratories measured arsenic (As), four laboratories measured cadmium (Cd), five laboratories measured cobalt (Co) and four laboratories measured chromium (Cr) in urine. The target values of the quality control materials were traceable to certified reference materials with respect to Cr in welding fume and As, Cd, Co and Cr in urine. For Mn, Fe and Ti in welding fume the target values were established based on values from reference laboratories and consensus values from several DEQAS rounds. For evaluating the analytical performance the z-score and E n number were calculated as recommended in ISO 45. The judgement of laboratories according to the performance scores revealed that few laboratories could maintain an ideal z-score below 3 and an ideal E n number below 1. Nearly all participants had a high precision in the reported results. This is a good basis for improvements. The deviations from the target values appear to be systematic, because the deviations for Mn, Fe, Ti in welding dust as well as for As, Cd, Co and Cr in urine were a linear function of the target values (ISO 5725 evaluation). The cause for this bias is unknown at present and might not be the same for all participants. It is necessary to look further into the cause for this bias. Therefore, validation of the methodologies and regularly use of certified reference materials are highly recommended. (author)

  19. Spatial variability of arsenic concentration in soils and plants, and its relationship with iron, manganese and phosphorus

    International Nuclear Information System (INIS)

    Hossain, M.B.; Jahiruddin, M.; Panaullah, G.M.; Loeppert, R.H.; Islam, M.R.; Duxbury, J.M.

    2008-01-01

    Spatial distribution of arsenic (As) concentrations of irrigation water, soil and plant (rice) in a shallow tube-well (STW) command area (8 ha), and their relationship with Fe, Mn and P were studied. Arsenic concentrations of water in the 110 m long irrigation channel clearly decreased with distance from the STW point, the range being 68-136 μg L -1 . Such decreasing trend was also noticed with Fe and P concentrations, but the trend for Mn concentrations was not remarkable. Concerning soil As, the concentration showed a decreasing tendency with distance from the pump. The NH 4 -oxalate extractable As contributed 36% of total As and this amount of As was associated with poorly crystalline Fe-oxides. Furthermore only 22% of total As was phosphate extractable so that most of the As was tightly retained by soil constituents and was not readily exchangeable by phosphate. Soil As (both total and extractable As) was significantly and positively correlated with rice grain As (0.296 ± 0.063 μg g -1 , n = 56). Next to drinking water, rice could be a potential source of As exposure of the people living in the As affected areas of Bangladesh. - Arsenic concentrations of irrigation water, soil and rice decreased with distance from STW point and it was related with iron and phosphorus concentrations

  20. N-butylamine functionalized graphene oxide for detection of iron(III) by photoluminescence quenching.

    Science.gov (United States)

    Gholami, Javad; Manteghian, Mehrdad; Badiei, Alireza; Ueda, Hiroshi; Javanbakht, Mehran

    2016-02-01

    An N-butylamine functionalized graphene oxide nanolayer was synthesized and characterized by ultraviolet (UV)-visible spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Detection of iron(III) based on photoluminescence spectroscopy was investigated. The N-butylamine functionalized graphene oxide was shown to specifically interact with iron (III), compared with other cationic trace elements including potassium (I), sodium (I), calcium (II), chromium (III), zinc (II), cobalt (II), copper (II), magnesium (II), manganese (II), and molybdenum (VI). The quenching effect of iron (III) on the luminescence emission of N-butylamine functionalized graphene oxide layer was used to detect iron (III). The limit of detection (2.8 × 10(-6)  M) and limit of quantitation (2.9 × 10(-5)  M) were obtained under optimal conditions. Copyright © 2015 John Wiley & Sons, Ltd.

  1. Manganese (II) induces chemical hypoxia by inhibiting HIF-prolyl hydroxylase: Implication in manganese-induced pulmonary inflammation

    International Nuclear Information System (INIS)

    Han, Jeongoh; Lee, Jong-Suk; Choi, Daekyu; Lee, Youna; Hong, Sungchae; Choi, Jungyun; Han, Songyi; Ko, Yujin; Kim, Jung-Ae; Mi Kim, Young; Jung, Yunjin

    2009-01-01

    Manganese (II), a transition metal, causes pulmonary inflammation upon environmental or occupational inhalation in excess. We investigated a potential molecular mechanism underlying manganese-induced pulmonary inflammation. Manganese (II) delayed HIF-1α protein disappearance, which occurred by inhibiting HIF-prolyl hydroxylase (HPH), the key enzyme for HIF-1α hydroxylation and subsequent von Hippel-Lindau(VHL)-dependent HIF-1α degradation. HPH inhibition by manganese (II) was neutralized significantly by elevated dose of iron. Consistent with this, the induction of cellular HIF-1α protein by manganese (II) was abolished by pretreatment with iron. Manganese (II) induced the HIF-1 target gene involved in pulmonary inflammation, vascular endothelial growth factor (VEGF), in lung carcinoma cell lines. The induction of VEGF was dependent on HIF-1. Manganese-induced VEGF promoted tube formation of HUVEC. Taken together, these data suggest that HIF-1 may be a potential mediator of manganese-induced pulmonary inflammation

  2. Transport of trace metals in the Magela Creek system, Northern Territory. I. Concentrations and loads of iron, manganese, cadmium, copper, lead and zinc during flood periods in the 1978-1979 wet season

    International Nuclear Information System (INIS)

    Hart, B.T.; Davies, S.H.R.; Thomas, P.A.

    1981-12-01

    In order that realistic effluent standards may be established for the Ranger uranium operations at Jabiru, Northern Territory, it is necessary that there be a clear and detailed knowledge of the pre-mining levels of trace metals and their behaviour within the Magela Creek system. During the wet season, floodwaters were sampled for conductivity, suspended solids and the trace metals, iron, manganese, cadmium, copper, lead and zinc. All concentrations were found to be very low, as were the denudation rates for the trace metals and suspended materials

  3. A mixed iron-manganese based pyrophosphate cathode, Na2Fe0.5Mn0.5P2O7, for rechargeable sodium ion batteries.

    Science.gov (United States)

    Shakoor, Rana A; Park, Chan Sun; Raja, Arsalan A; Shin, Jaeho; Kahraman, Ramazan

    2016-02-07

    The development of secondary batteries based on abundant and cheap elements is vital. Among various alternatives to conventional lithium-ion batteries, sodium-ion batteries (SIBs) are promising due to the abundant resources and low cost of sodium. While there are many challenges associated with the SIB system, cathode is an important factor in determining the electrochemical performance of this battery system. Accordingly, ongoing research in the field of SIBs is inclined towards the development of safe, cost effective cathode materials having improved performance. In particular, pyrophosphate cathodes have recently demonstrated decent electrochemical performance and thermal stability. Herein, we report the synthesis, electrochemical properties, and thermal behavior of a novel Na2Fe0.5Mn0.5P2O7 cathode for SIBs. The material was synthesized through a solid state process. The structural analysis reveals that the mixed substitution of manganese and iron has resulted in a triclinic crystal structure (P1[combining macron] space group). Galvanostatic charge/discharge measurements indicate that Na2Fe0.5Mn0.5P2O7 is electrochemically active with a reversible capacity of ∼80 mA h g(-1) at a C/20 rate with an average redox potential of 3.2 V. (vs. Na/Na(+)). It is noticed that 84% of initial capacity is preserved over 90 cycles showing promising cyclability. It is also noticed that the rate capability of Na2Fe0.5Mn0.5P2O7 is better than Na2MnP2O7. Ex situ and CV analyses indicate that Na2Fe0.5Mn0.5P2O7 undergoes a single phase reaction rather than a biphasic reaction due to different Na coordination environment and different Na site occupancy when compared to other pyrophosphate materials (Na2FeP2O7 and Na2MnP2O7). Thermogravimetric analysis (25-550 °C) confirms good thermal stability of Na2Fe0.5Mn0.5P2O7 with only 2% weight loss. Owing to promising electrochemical properties and decent thermal stability, Na2Fe0.5Mn0.5P2O7, can be an attractive cathode for SIBs.

  4. One-step hydrothermal synthesis and electrochemical performance of sodium-manganese-iron phosphate as cathode material for Li-ion batteries

    Science.gov (United States)

    Karegeya, Claude; Mahmoud, Abdelfattah; Vertruyen, Bénédicte; Hatert, Frédéric; Hermann, Raphaël P.; Cloots, Rudi; Boschini, Frédéric

    2017-09-01

    The sodium-manganese-iron phosphate Na2Mn1.5Fe1.5(PO4)3 (NMFP) with alluaudite structure was obtained by a one-step hydrothermal synthesis route. The physical properties and structure of this material were obtained through XRD and Mössbauer analyses. X-ray diffraction Rietveld refinements confirm a cationic distribution of Na+ and presence of vacancies in A(2)', Na+ and small amounts of Mn2+ in A(1), Mn2+ in M(1), 0.5 Mn2+ and Fe cations (Mn2+,Fe2+ and Fe3+) in M(2), leading to the structural formula Na2Mn(Mn0.5Fe1.5)(PO4)3. The particles morphology was investigated by SEM. Several reactions with different hydrothermal reaction times were attempted to design a suitable synthesis protocol of NMFP compound. The time of reaction was varied from 6 to 48 h at 220 °C. The pure phase of NMFP particles was firstly obtained when the hydrothermal reaction of NMFP precursors mixture was maintained at 220 °C for 6 h. When the reaction time was increased from 6 to 12, 24 and 48 h, the dandelion structure was destroyed in favor of NMFP micro-rods. The combination of NMFP (NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H) structure refinement and Mössbauer characterizations shows that the increase of the reaction time leads to the progressive increment of Fe(III) and the decrease of the crystal size. The electrochemical tests indicated that NMFP is a 3 V sodium intercalating cathode. The comparison of the discharge capacity evolution of studied NMFP electrode materials at C/5 current density shows different capacities of 48, 40, 34 and 34 mA h g-1 for NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H respectively. Interestingly, all samples show excellent capacity retention of about 99% during 50 cycles.

  5. Molybdenum, molybdenum oxides, and their electrochemistry.

    Science.gov (United States)

    Saji, Viswanathan S; Lee, Chi-Woo

    2012-07-01

    The electrochemical behaviors of molybdenum and its oxides, both in bulk and thin film dimensions, are critical because of their widespread applications in steels, electrocatalysts, electrochromic materials, batteries, sensors, and solar cells. An important area of current interest is electrodeposited CIGS-based solar cells where a molybdenum/glass electrode forms the back contact. Surprisingly, the basic electrochemistry of molybdenum and its oxides has not been reviewed with due attention. In this Review, we assess the scattered information. The potential and pH dependent active, passive, and transpassive behaviors of molybdenum in aqueous media are explained. The major surface oxide species observed, reversible redox transitions of the surface oxides, pseudocapacitance and catalytic reduction are discussed along with carefully conducted experimental results on a typical molybdenum glass back contact employed in CIGS-based solar cells. The applications of molybdenum oxides and the electrodeposition of molybdenum are briefly reviewed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Distribution of iron and manganese

    Digital Repository Service at National Institute of Oceanography (India)

    Mesquita, A.; Kaisary, S.

    inverse distance weighting the spatial distributions of the particulate and dissolved concentrations of Fe and Mn were mapped along the salinity gradient of the two rivers. Significant seasonal signals were observed in the spatial variations...

  7. High strength tungsten heavy alloys with molybdenum additions

    International Nuclear Information System (INIS)

    Bose, A.; Sims, D.M.; German, R.M.

    1987-01-01

    Tungsten heavy alloys are candidates for numerous applications based on the unique combination of high density, high strength, and high ductility coupled with excellent machinability. Though there has been considerable research on heavy alloys, the primary focus has been on the ductility. These alloys are well suited for ballistic uses due to their high densities and it is expected that for superior ballistic performance, a high hardness, high strength and moderate ductility alloy would be ideal. The major goal of this investigation was to obtain heavy alloys with hardness greater than HRA 72. It is evident from the phase diagrams that molybdenum, which goes into solution in tungsten, nickel and iron, could act as a potential strengthening addition. With this in view, tungsten heavy alloys with molybdenum additions were fabricated from mixed elemental powders. A baseline composition of 90W-7Ni-3Fe was chosen to its good elongation and moderate strength. The molybdenum additions were made by replacing the tungsten. Compared to the baseline properties with no molybdenum addition, the strength and hardness showed a continuous increase with molybdenum addition. The ductility of the alloy continued to decrease with increasing molybdenum content, but even with 16% wt. % molybdenum of the elongation was still around 6%. An interesting facet of these alloying additions is the grain refinement that is brought about by adding to molybdenum to the system. The grain refinement is related to the lower solubility of tunbsten in the matrix due to partial displacement by molybdenum

  8. 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...

  9. 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 ...

  10. Analytic chemistry of molybdenum

    International Nuclear Information System (INIS)

    Parker, G.A.

    1983-01-01

    Electrochemical, colorimetric, gravimetric, spectroscopic, and radiochemical methods for the determination of molybdenum are summarized in this book. Some laboratory procedures are described in detail while literature citations are given for others. The reader is also referred to older comprehensive reviews of the analytical chemistry of molybdenum. Contents, abridged: Gravimetric methods. Titrimetric methods. Colorimetric methods. X-ray fluorescence. Voltammetry. Catalytic methods. Molybdenum in non-ferrous alloys. Molydbenum compounds

  11. Molybdenum from uranium solutions

    International Nuclear Information System (INIS)

    Gardner, H.E.

    1981-01-01

    A method of removing molybdenum from a uranium bearing solution is claimed. It comprises adding sufficient reactive lead compound to supply at least 90 percent of the stoichiometric quantity of lead ion required to fully react with the molybdenum present to form insoluble lead molybdate and continuing the reaction with agitation until the desired percentage of the molybdenum present has reacted with the lead ion

  12. Potentiometric determination of molybdenum

    International Nuclear Information System (INIS)

    Rusina, O.N.; Gorbatkova, B.Kh.

    1977-01-01

    Potentiometric titration by lead acetate is used to determine molybdenum in the form of molybdate ions. The behaviour of bimetallic electrode couples, i.e. tungsten-lead, platinum-lead, lead-carbon electrode, molybdenum-carbon electrode platinum-molibdenum has been investigated. The greatest jump of the potential in the finite point is observed for platinum-molybdenum electrode couple (150 mV/ml at pH 4.0-5.5). The limiting concentration of molybdenum in potentiometric titration by lead acetate is 2.8x10 -4 M. The measurements are accurate to within +-0.1%

  13. Recovery of manganese from manganese oxide ores in the EDTA solution

    Science.gov (United States)

    Zhang, Chao; Wang, Shuai; Cao, Zhan-fang; Zhong, Hong

    2018-04-01

    A new process has been experimentally and theoretically established for the recovery of manganese from manganese oxide ores, mainly including the reductive leaching of manganese by ethylenediaminetetraacetic acid (EDTA), EDTA recovery, and manganese electrolysis. The experimental conditions for this process were investigated. Moderate leaching environment by EDTA with the pH in the range of 5-6 is of benefit to leach manganese from some manganese oxide ores with high-content impurities, such as iron and aluminum. Most of EDTA can be recovered by acidification. A small amount of the residual EDTA in the electrolyte can prevent the generation of anode mud. In addition, trimanganese tetroxide (Mn3O4) can be obtained by the roasting of the EDTA-Mn crystallized product.

  14. Inhibitory Effect of Dissolved Silica on the H2O2 Decomposition by Iron(III) and Manganese(IV) Oxides: Implications for H2O2-based In Situ Chemical Oxidation

    Science.gov (United States)

    Pham, Anh Le-Tuan; Doyle, Fiona M.; Sedlak, David L.

    2011-01-01

    The decomposition of H2O2 on iron minerals can generate •OH, a strong oxidant that can transform a wide range of contaminants. This reaction is critical to In Situ Chemical Oxidation (ISCO) processes used for soil and groundwater remediation, as well as advanced oxidation processes employed in waste treatment systems. The presence of dissolved silica at concentrations comparable to those encountered in natural waters decreases the reactivity of iron minerals toward H2O2, because silica adsorbs onto the surface of iron minerals and alters catalytic sites. At circumneutral pH values, goethite, amorphous iron oxide, hematite, iron-coated sand and montmorillonite that were pre-equilibrated with 0.05 – 1.5 mM SiO2 were significantly less reactive toward H2O2 decomposition than their original counterparts, with the H2O2 loss rates inversely proportional to the SiO2 concentration. In the goethite/H2O2 system, the overall •OH yield, defined as the percentage of decomposed H2O2 producing •OH, was almost halved in the presence of 1.5 mM SiO2. Dissolved SiO2 also slows the H2O2 decomposition on manganese(IV) oxide. The presence of dissolved SiO2 results in greater persistence of H2O2 in groundwater, lower H2O2 utilization efficiency and should be considered in the design of H2O2-based treatment systems. PMID:22129132

  15. Molybdenum market in transition

    International Nuclear Information System (INIS)

    Sutulov, A.

    1980-01-01

    Since the beginning of 1980 - after seven years of constant unbalance between supply and demand of molybdenum, characterized by a demand overhang and after two years of unprecedented spot market prices - clear signals for a consolidation of the molybdenum market can be recognized. (orig.) [de

  16. Effect of increased manganese addition and mould type on the ...

    Indian Academy of Sciences (India)

    The wear resistance of high chromium iron is well recorded. However, the same is not the case as regards the use of manganese at higher percentages in high chromium irons and its influence on wear behaviour. Hence, this work highlights the slurry wear characteristics of chromium (□ ◻ 16–19%) iron following the ...

  17. Gastroprotective Properties of Manganese Chloride on Acetic Acid

    African Journals Online (AJOL)

    Dr Olaleye

    Drugs with multiple mechanisms of protective action may be effective in minimizing ... that Manganese had dose and treatment duration dependent effect on healing of ulcerated stomach. .... The stomach was bathed with normal saline ..... Arnaud, J., and Favier, A. (1995): "Copper, iron, manganese ... Experimental Toxic.

  18. Precipitation hardenable iron-nickel-chromium alloy having good swelling resistance and low neutron absorbence

    International Nuclear Information System (INIS)

    Korenko, M.K.; Merrick, H.F.; Gibson, R.C.

    1982-01-01

    An iron-nickel-chromium age-hardenable alloy suitable for use in fast breeder reactor ducts and cladding utilizes the gamma-double prime strengthening phase and has a morphology of the gamma-double prime phase enveloping the gamma-prime phase and delta phase distributed at or near the grain boundaries. The alloy consists essentially of about 40-50 percent nickel, 7.5-14 percent chromium, 1.5-4 percent niobium, .25-.75 percent silicon, 1-3 percent titanium, .1-.5 percent aluminum, .02-1 percent carbon, .002-.015 percent boron, and the balance iron. Up to 2 percent manganese and up to .01 percent magnesium may be added to inhibit trace element effects; up to .1 percent zirconium may be added to increase radiation swelling resistance; and up to 3 percent molybdenum may be added to increase strength

  19. Process for purifying molybdenum

    International Nuclear Information System (INIS)

    Cheresnowsky, J.

    1989-01-01

    This patent describes a process for purifying molybdenum containing arsenic and phosphorus. The process comprising: adding to an acidic slurry of molybdenum trioxide, a source of magnesium ions in a solid form, with the amount of magnesium and the magnesium ion concentration in the subsequently formed ammonium molybdate solution being sufficient to subsequently form insoluble compounds containing greater than about 80% by weight of the arsenic and greater than about 80% by weight of the phosphorus, and ammonia in an amount sufficient to subsequently dissolve the molybdenum and subsequently form the insoluble compounds, with the source of magnesium ions being added prior to the addition of the ammonia; digesting the resulting ammoniated slurry at a temperature sufficient to dissolve the molybdenum and form an ammonium molybdate solution while the pH is maintained at from bout 9 to about 10 to form a solid containing the insoluble compounds; and separating the solid from the ammonium molybdate solution

  20. Influence of molybdenum on hardenability of destabilized high chromium cast irons. Ko kuromu chutetsu no netsushori tokusei ni oyobosu moribuden no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kuwano, M. (Ube, Collete of Technology, Yamaguchi (Japan)); Ogi, K. (Kyushu University, Fukuoka (Japan). Faculty of Engineering); Sawamoto, A. (Yamaguchi University, Yamaguchi (Japan))

    1991-07-25

    Alloy elements are added to compensate for reduction in hardenability of high chromium cast iron as a result of destabilization heat treatment. With the purpose of investigating the influence of the added elements, this paper describes investigations made on effects of Mo and destabilization heat treatment conditions on martensite transformation , eutectoid transformation and base hardness, using Fe-Cr-C-based alloy containing C at 1.6-3.6%, and Cr at 6.6-26%. The main results obtained are as follows: Mo and Cr had the distribution coefficient for initial crystal austenite is smaller than one and were microscopically segregated in the dendrite base; the solute element distribution in the base is homogenized as a result of the long-time destabilization heat treatment while the Cr and C concentrations reduce largely, and the Mo concentration increases slightly; Mo has little influence on the Ms point, and reduces with the smaller the Cr/C ratio and the higher the retention temperature; and the base hardness corresponds well to a CCT diagram. 14 refs., 11 figs., 1 tab.

  1. Influence of Chemical Composition on Rupture Properties at 1200 Degrees F. of Forged Chromium-Cobalt-Nickel-Iron Base Alloys in Solution-Treated and Aged Condition

    Science.gov (United States)

    Reynolds, E E; Freeman, J W; White, A E

    1951-01-01

    The influence of systematic variations of chemical composition on rupture properties at 1200 degrees F. was determined for 62 modifications of a basic alloy containing 20 percent chromium, 20 percent nickel, 20 percent cobalt, 3 percent molybdenum, 2 percent tungsten, 1 percent columbium, 0.15 percent carbon, 1.7 percent manganese, 0.5 percent silicon, 0.12 percent nitrogen and the balance iron. These modifications included individual variations of each of 10 elements present and simultaneous variations of molybdenum, tungsten, and columbium. Laboratory induction furnace heats were hot-forged to round bar stock, solution-treated at 2200 degrees F., and aged at 1400 degrees F. The melting and fabrication conditions were carefully controlled in order to minimize all variable effects on properties except chemical composition. Information is presented which indicates that melting and hot-working conditions play an important role in high-temperature properties of alloys of the type investigated.

  2. Dissolution of manganese and cobalt and their deposition on Type 304 stainless steel in liquid sodium

    International Nuclear Information System (INIS)

    Yokota, Norikatsu; Shimoyashiki, Shigehiro

    1989-01-01

    Dissolution of manganese and cobalt and their deposition on Type 304 stainless steel in liquid sodium at 833 K for 3.6 x 10 3 ks were examined using a liquid sodium pot. Manganese was easily dissolved in sodium from the iron-manganese alloy specimen and deposited on the steel to form two kind of deposition particles, α-phase (body-centered cubic) composed of iron and γ-phase (face-centered cubic) composed of iron and manganese, respectively. Cobalt which was less easily dissolved than manganese also deposited on the Type 304 stainless steel, giving an iron-cobalt alloy. These three deposition particles corresponded to the precipitation lines of iron-manganese and iron-cobalt phase diagrams at 833 K, respectively. Therefore, the deposition process of manganese or cobalt in sodium was explained as a precipitation process of iron-manganese or iron-cobalt in the solid region of the binary phase diagram. A sodium chromite (NaCrO 2 ) layer was formed on the steel surface. (author)

  3. Spectroscopic characterization of manganese minerals.

    Science.gov (United States)

    Lakshmi Reddy, S; Padma Suvarna, K; Udayabhaska Reddy, G; Endo, Tamio; Frost, R L

    2014-01-03

    Manganese minerals ardenite, alleghanyite and leucopoenicite originated from Madhya Pradesh, India, Nagano prefecture Japan, Sussex Country and Parker Shaft Franklin, Sussex Country, New Jersey respectively are used in the present work. In these minerals manganese is the major constituent and iron if present is in traces only. An EPR study of on all of the above samples confirms the presence of Mn(II) with g around 2.0. Optical absorption spectrum of the mineral alleghanyite indicates that Mn(II) is present in two different octahedral sites and in leucophoenicite Mn(II) is also in octahedral geometry. Ardenite mineral gives only a few Mn(II) bands. NIR results of the minerals ardenite, leucophoenicite and alleghanyite are due to hydroxyl and silicate anions which confirming the formulae of the minerals. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Determination of molybdenum in flotation concentrates by atomic absorption spectrophotometry

    International Nuclear Information System (INIS)

    Ise, Kazuo

    1978-01-01

    Molybdenum was determined by atomic absorption spectrophotometry in 0.05 N ammoniacal solution after the decomposition of the concentrate with aqua regia. Negros ore from Philippines was used as a flotation feed, which contained chalcopyrites and calcium-magnesium minerals. Among the metals tested copper, iron and the alkaline earths interfered. Less than 50 ppm of copper yielded lower results for molybdenum. Higher results came out with more than 50 ppm of copper. In the presence of iron and citric acid (0.4 g/100 ml) which is a suppressor for hydroxide formation, a lower estimation resulted for molybdenum. Calcium interfered, lower results by 2 and >10% being obtained with respective 2.5 and 20 ppm of calcium. More than 20 ppm of magnesium behaved similarly. Sodium sulfate (0.5 g/100 ml) served as the suppressor for copper, iron and citric acid; 100 ppm each of copper and iron did not interfere in this way. Interferences due to calcium and magnesium (less than 60 ppm) was able to be masked by the addition of sodium silicate (200 ppm as silica). The analysis of flotation products and synthetic samples consisting of molybdenite, chalcopyrite, calcium chloride and magnesium sulfate revealed that the atomic absorption method can be applied to the analysis of the concentrates for molybdenum with an error of about 2%. (auth.)

  5. Bibliographic study on molybdenum biokinetics

    International Nuclear Information System (INIS)

    Erzberger, A.

    1988-05-01

    This bibliographical study compiles and analyzes findings about the metabolism and resorption of molybdenum. Besides including studies on the physiology of molybdenum 99, a general survey is given on molybdenum in the environment and on its physiological behaviour. In particular, information on the dependence of molybdenum resorption on various factors, such as the chemical form, antagonisms etc., are gathered from literature. These factors have to be considered for sensibly carrying out necessary experiments. (orig./MG) [de

  6. Molybdenum solar neutrino experiment

    International Nuclear Information System (INIS)

    Wolfsberg, K.; Cowan, G.A.; Bryant, E.A.

    1984-01-01

    The goal of the molybdenum solar neutrino experiment is to deduce the 8 B solar neutrino flux, averaged over the past several million years, from the concentration of 98 Tc in a deeply buried molybdenum deposit. The experiment is important to an understanding of stellar processes because it will shed light on the reason for the discrepancy between theory and observation of the chlorine solar neutrino experiment. Possible reasons for the discrepancy may lie in the properties of neutrinos (neutrino oscillations or massive neutrinos) or in deficiencies of the standard solar model. The chlorine experiment only measures the 8 B neutrino flux in current times and does not address possible temporal variations in the interior of the sun, which are also not considered in the standard model. In the molybdenum experiment, we plan to measure 98 Tc (4.2 Myr), also produced by 8 B neutrinos, and possibly 97 Tc (2.6 Myr), produced by lower energy neutrinos

  7. Method of producing molybdenum-99

    Science.gov (United States)

    Pitcher, Eric John

    2013-05-28

    Method of producing molybdenum-99, comprising accelerating ions by means of an accelerator; directing the ions onto a metal target so as to generate neutrons having an energy of greater than 10 MeV; directing the neutrons through a converter material comprising techentium-99 to produce a mixture comprising molybdenum-99; and, chemically extracting the molybdenum-99 from the mixture.

  8. The Escherichia coli small protein MntS and exporter MntP optimize the intracellular concentration of manganese.

    Directory of Open Access Journals (Sweden)

    Julia E Martin

    2015-03-01

    Full Text Available Escherichia coli does not routinely import manganese, but it will do so when iron is unavailable, so that manganese can substitute for iron as an enzyme cofactor. When intracellular manganese levels are low, the cell induces the MntH manganese importer plus MntS, a small protein of unknown function; when manganese levels are high, the cell induces the MntP manganese exporter and reduces expression of MntH and MntS. The role of MntS has not been clear. Previous work showed that forced MntS synthesis under manganese-rich conditions caused bacteriostasis. Here we find that when manganese is scarce, MntS helps manganese to activate a variety of enzymes. Its overproduction under manganese-rich conditions caused manganese to accumulate to very high levels inside the cell; simultaneously, iron levels dropped precipitously, apparently because manganese-bound Fur blocked the production of iron importers. Under these conditions, heme synthesis stopped, ultimately depleting cytochrome oxidase activity and causing the failure of aerobic metabolism. Protoporphyrin IX accumulated, indicating that the combination of excess manganese and iron deficiency had stalled ferrochelatase. The same chain of events occurred when mutants lacking MntP, the manganese exporter, were exposed to manganese. Genetic analysis suggested the possibility that MntS exerts this effect by inhibiting MntP. We discuss a model wherein during transitions between low- and high-manganese environments E. coli uses MntP to compensate for MntH overactivity, and MntS to compensate for MntP overactivity.

  9. Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria.

    Science.gov (United States)

    Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

    2012-11-01

    Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 10(6) acetate-utilizing manganese-reducing cells cm(-3) in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments.

  10. Molybdenum dioxide-molybdenite roasting

    International Nuclear Information System (INIS)

    Sabacky, B.J.; Hepworth, M.T.

    1984-01-01

    A process is disclosed for roasting molybdenite concentrates directly to molybdenum dioxide. The process comprises establishing a roasting zone having a temperature of about 700 0 C. to about 800 0 C., introducing into the roasting zone particulate molybdenum dioxide and molybdenite in a weight ratio of at least about 2:1 along with an oxygen-containing gas in amount sufficient to oxidize the sulfur content of the molybdenite to molybdenum dioxide

  11. Arsenic removal by manganese greensand filters

    Energy Technology Data Exchange (ETDEWEB)

    Phommavong, T. [Saskatchewan Environment, Regina (Canada); Viraraghavan, T. [Univ. of Regina, Saskatchewan (Canada). Faculty of Engineering

    1994-12-31

    Some of the small communities in Saskatchewan are expected to have difficulty complying with the new maximum acceptable concentration (MAC) of 25 {micro}g/L for arsenic. A test column was set up in the laboratory to study the removal of arsenic from the potable water using oxidation with KMnO{sub 4}, followed by manganese greensand filtration. Tests were run using water from the tap having a background arsenic concentration of <0.5 {micro}g/L and iron concentration in the range of 0.02 to 0.77 mg/L. The test water was spiked with arsenic and iron. Results showed that 61 % to 98% of arsenic can be removed from the potable water by oxidation with KMnO{sub 4} followed by manganese greensand filtration.

  12. Accumulation of iron and arsenic in the Chandina alluvium of the lower delta plain, Southeastern Bangladesh

    Science.gov (United States)

    Zahid, A.; Hassan, M.Q.; Breit, G.N.; Balke, K.-D.; Flegr, M.

    2009-01-01

    Accumulations of iron, manganese, and arsenic occur in the Chandina alluvium of southeastern Bangladesh within 2.5 m of the ground surface. These distinctive orange-brown horizons are subhorizontal and consistently occur within 1 m of the contact of the aerated (yellow-brown) and water-saturated (gray) sediment. Ferric oxyhydroxide precipitates that define the horizons form by oxidation of reduced iron in pore waters near the top of the saturated zone when exposed to air in the unsaturated sediment. Hydrous Fe-oxide has a high specific surface area and thus a high adsorption capacity that absorbs the bulk of arsenic also present in the reduced pore water, resulting in accumulations containing as much as 280 ppm arsenic. The steep redox gradient that characterizes the transition of saturated and unsaturated sediment also favors accumulation of manganese oxides in the oxidized sediment. Anomalous concentrations of phosphate and molybdenum also detected in the ferric oxyhydroxide-enriched sediment are attributed to sorption processes. ?? Springer Science+Business Media B.V. 2008.

  13. The determination, by atomic-absorption spectrophotometry, of impurities in manganese dioxide

    International Nuclear Information System (INIS)

    Balaes, G.E.E.; Robert, R.V.D.

    1981-01-01

    This report describes various methods for the determination of impurities in electrolytic manganese dioxide by atomic-absorption spectrophotometry (AAS). The sample is dissolved in a mixture of acids, any residue being ignited and retreated with acid. Several AAS methods were applied so that the analysis required to meet the specifications could be attained. These involved conventional flame AAS, AAS with electrothermal atomization (ETA), hydride generation coupled with AAS, and cold-vapour AAS. Of the elements examined, copper, iron, zinc, and lead can be determined direct with confidence with or without corrections based on recoveries obtained from spiked solutions. Nickel can be determined direct by use of the method of standard additions, and copper, nickel, and lead by ETA with the method of standard additions. Arsenic and antimony are determined by hydride generation coupled with AAS, and mercury by cold-vapour AAS. The precision of analysis (relative standard deviation) is generally less than 0,050. Values were obtained for aluminium, molybdenum, magnesium, sodium, copper, chromium, and cadmium, but the accuracy of these determinations has not been fully established

  14. Predicting molybdenum toxicity to higher plants: Influence of soil properties

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, S.P., E-mail: steve.mcgrath@bbsrc.ac.u [Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Mico, C. [Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Curdy, R. [Laboratory for Environmental Biotechnology (LBE), Swiss Federal Institute of Technology Lausanne (EPFL) Station 6 CH, 1015 Lausanne (Switzerland); Zhao, F.J. [Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom)

    2010-10-15

    The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED{sub 50}) of Mo in different soils, explaining > 65% of the variance in ED{sub 50} for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations. - Amorphous iron oxides or organic carbon were found to be the best predictors of the toxicity threshold values of Mo to higher plants on different soils.

  15. Predicting molybdenum toxicity to higher plants: Influence of soil properties

    International Nuclear Information System (INIS)

    McGrath, S.P.; Mico, C.; Curdy, R.; Zhao, F.J.

    2010-01-01

    The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED 50 ) of Mo in different soils, explaining > 65% of the variance in ED 50 for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations. - Amorphous iron oxides or organic carbon were found to be the best predictors of the toxicity threshold values of Mo to higher plants on different soils.

  16. Carbon-supported iron and iron-molybdenum sulfide catalysts

    International Nuclear Information System (INIS)

    Ramselaar, W.L.T.M.

    1988-01-01

    The main objective was to describe the relations between the characteristics (composition and dispersion) of the actual sulfide phase and the catalytic activity. Attention was also paid to the influence of preparational aspects on these characteristics. The catalysts were characterized using in-situ Moessbauer spectroscopy down to 2.0 K. 254 refs.; 47 figs.; 22 tabs

  17. Hydrometallurgical method for recycling rare earth metals, cobalt, nickel, iron, and manganese from negative electrodes of spent Ni-MH mobile phone batteries; Metodo hidrometalurgico para reciclagem de metais terras raras, cobalto, niquel, ferro e manganes de eletrodos negativos de baterias exauridas de Ni-MH de telefone celular

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Vinicius Emmanuel de Oliveira dos; Lelis, Maria de Fatima Fontes; Freitas, Marcos Benedito Jose Geraldo de, E-mail: viniciusemmanuel@hotmail.com [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Departamento de Quimica; Celante, Vinicius Guilherme [Instituto Federal do Espirito Santo (IFES), Aracruz, ES (Brazil)

    2014-07-01

    A hydrometallurgical method for the recovery of rare earth metals, cobalt, nickel, iron, and manganese from the negative electrodes of spent Ni-MH mobile phone batteries was developed. The rare earth compounds were obtained by chemical precipitation at pH 1.5, with sodium cerium sulfate (NaCe(SO{sub 4}){sub 2}.H{sub 2}O) and lanthanum sulfate (La{sub 2}(SO{sub 4}){sub 3}.H{sub 2}O) as the major recovered components. Iron was recovered as Fe(OH){sub 3} and FeO. Manganese was obtained as Mn{sub 3}O{sub 4}.The recovered Ni(OH){sub 2} and Co(OH){sub 2} were subsequently used to synthesize LiCoO{sub 2}, LiNiO{sub 2} and CoO, for use as cathodes in ion-Li batteries. The anodes and recycled materials were characterized by analytical techniques. (author)

  18. Globally sustainable manganese metal production and use.

    Science.gov (United States)

    Hagelstein, Karen

    2009-09-01

    The "cradle to grave" concept of managing chemicals and wastes has been a descriptive analogy of proper environmental stewardship since the 1970s. The concept incorporates environmentally sustainable product choices-such as metal alloys utilized steel products which civilization is dependent upon. Manganese consumption is related to the increasing production of raw steel and upgrading ferroalloys. Nonferrous applications of manganese include production of dry-cell batteries, plant fertilizer components, animal feed and colorant for bricks. The manganese ore (high grade 35% manganese) production world wide is about 6 million ton/year and electrolytic manganese metal demand is about 0.7 million ton/year. The total manganese demand is consumed globally by industries including construction (23%), machinery (14%), and transportation (11%). Manganese is recycled within scrap of iron and steel, a small amount is recycled within aluminum used beverage cans. Recycling rate is 37% and efficiency is estimated as 53% [Roskill Metals and Minerals Reports, January 13, 2005. Manganese Report: rapid rise in output caused by Chinese crude steel production. Available from: http://www.roskill.com/reports/manganese.]. Environmentally sustainable management choices include identifying raw material chemistry, utilizing clean production processes, minimizing waste generation, recycling materials, controlling occupational exposures, and collecting representative environmental data. This paper will discuss two electrolytically produced manganese metals, the metal production differences, and environmental impacts cited to date. The two electrolytic manganese processes differ due to the addition of sulfur dioxide or selenium dioxide. Adverse environmental impacts due to use of selenium dioxide methodology include increased water consumption and order of magnitude greater solid waste generation per ton of metal processed. The use of high grade manganese ores in the electrolytic process also

  19. On molybdenum (6) alcoholates

    International Nuclear Information System (INIS)

    Turova, N.Ya.; Kessler, V.G.

    1990-01-01

    Synthesis techniques for molybdenum (6) alcoholates of MoO(OR) 4 (1) and MoO 2 (OR) 2 (2) series by means of exchange interaction of corresponding oxychloride with MOR (M=Li, Na) are obtained. These techniques have allowed to prepare 1(R=Me, Et, i-Pr) and 2(R=Me, Et) with 70-98 % yield. Methylates are also prepared at ether interchange of ethylates by methyl alcohol. Metal anode oxidation in corresponding alcohol may be used for 1 synthesis. Physicochemical properties of both series alcoholates, solubility in alcohols in particular, depend on their formation conditions coordination polymerism. Alcoholates of 1 are rather unstable and tend to decomposition up to 2 and ether. It is suggested to introduce NaOR microquantities to stabilize those alcoholates

  20. Molybdenum Tube Characterization report

    Energy Technology Data Exchange (ETDEWEB)

    Beaux II, Miles Frank [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Usov, Igor Olegovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-07

    Chemical vapor deposition (CVD) techniques have been utilized to produce free-standing molybdenum tubes with the end goal of nuclear fuel clad applications. In order to produce tubes with properties desirable for this application, deposition rates were lowered requiring long deposition durations on the order of 50 hours. Standard CVD methods as well as fluidized-bed CVD (FBCVD) methods were applied towards these objectives. Characterization of the tubes produced in this manner revealed material suitable for fuel clad applications, but lacking necessary uniformity across the length of the tubes. The production of freestanding Mo tubes that possess the desired properties across their entire length represents an engineering challenge that can be overcome in a next iteration of the deposition system.

  1. Diffusion in molybdenum disilicide

    International Nuclear Information System (INIS)

    Salamon, M.; Mehrer, H.

    2005-01-01

    The diffusion behaviour of the high-temperature material molybdenum disilicide (MoSi 2 ) was completely unknown until recently. In this paper we present studies of Mo self-diffusion and compare our present results with our already published studies of Si and Ge diffusion in MoSi 2 . Self-diffusion of molybdenum in monocrystalline MoSi 2 was studied by the radiotracer technique using the radioisotope 99 Mo. Deposition of the radiotracer and serial sectioning after the diffusion anneals to determine the concentration-depth profiles was performed using a sputtering device. Diffusion of Mo is a very slow process. In the entire temperature region investigated (1437 to 2173 K), the 99 Mo diffusivities in both principal directions of the tetragonal MoSi 2 crystals obey Arrhenius laws, where the diffusion perpendicular to the tetragonal axis is faster by two to three orders of magnitude than parallel to it. The activation enthalpies for diffusion perpendicular and parallel to the tetragonal axis are Q perpendicular to = 468 kJ mol -1 (4.85 eV) and Q parallel = 586 kJ mol -1 (6.07 eV), respectively. Diffusion of Si and its homologous element Ge is fast and is mediated by thermal vacancies of the Si sublattice of MoSi 2 . The diffusion of Mo is by several orders of magnitude slower than the diffusion of Si and Ge. This large difference suggests that Si and Mo diffusion are decoupled and that the diffusion of Mo likely takes place via vacancies on the Mo sublattice. (orig.)

  2. Economic value of Valentines iron minerals

    International Nuclear Information System (INIS)

    Alvarado, B.

    1960-01-01

    This work is a investigation required by the government of Uruguay about the economic value of iron and manganese deposits in Valentines ferriferrous zone. The purpose is to study the potential commercial for the exportation.

  3. Selective adsorption of molybdenum(VI) from Mo-Re bearing effluent by chemically modified astringent persimmon

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Ying, E-mail: xiongying_1977@hotmail.com [School of Chemistry, Key Laboratory of Rare-scattered Elements of Liaoning Province, Liaoning University, Shenyang 110036 (China); Wang Haitao; Lou Zhenning; Shan Weijun; Xing Zhiqiang; Deng Guichun [School of Chemistry, Key Laboratory of Rare-scattered Elements of Liaoning Province, Liaoning University, Shenyang 110036 (China); Wu Dongbei [Department of Chemistry, Tongji University, 200092 (China); Fang Dawei [School of Chemistry, Key Laboratory of Rare-scattered Elements of Liaoning Province, Liaoning University, Shenyang 110036 (China); Biswas, Biplob Kumar [Department of Applied Chemistry, Saga University, Honjo 1, Saga 840-8502 (Japan); Department of Applied Chemistry and Chemical Engineering, Jessore Science and Technology University, Jessore (Bangladesh)

    2011-02-28

    Graphical abstract: The use of persimmon for the recovery of Mo(VI) from aqueous chloride medium was investigated. The excellent adsorption characteristics for Mo(VI) were confirmed by adsorption and elution tests using a column packed with the APF gel. Research highlights: {yields} Astringent persimmon was chemically cross-linked by formaldehyde to obtain a novel kind of adsorption gel. By comparing with the adsorption of some other metal ions, especially for Re(VII), this new gel exhibited selectivity only for molybdenum with a remarkably high capacity for Mo(VI) (1.05 mol/kg dry gel). {yields} The adsorption mechanisms of molybdenum on the astringent persimmon gel have been determined for deferent molybdenum species. And, the endothermic adsorption process followed pseudo-second order kinetics, and the adsorption behavior obeys the Langmuir mode. {yields} The excellent adsorption characteristics for Mo(VI) were confirmed by adsorption and elution tests using a column packed with the APF gel, especially from an actual industrial waste effluent. - Abstract: Astringent persimmon was chemically cross-linked by formaldehyde to obtain a novel kind of adsorption gel, which was named as APF gel. The adsorption behaviors of Mo(VI) and Re(VII) along with other coexisting metals onto the APF gel were studied in the present paper. The APF gel was found to be effective for the adsorption of Mo(VI) while the gel is almost completely inert toward rhenium and calcium over the whole hydrochloric acid concentration region. The APF gel has a low affinity for iron, copper, lead, nickel, manganese and zinc ions when the concentration of HCl is higher than 1 mol/L. The gel exhibited selectivity only for Mo(VI) with a remarkably high adsorption capacity 1.05 mol/kg, and the adsorption behavior obeys the Langmuir model. According to the thermodynamic and kinetic studies, the endothermic adsorption process followed pseudo-second order kinetics. Also, its excellent adsorption

  4. Manganese deposition in drinking water distribution systems.

    Science.gov (United States)

    Gerke, Tammie L; Little, Brenda J; Barry Maynard, J

    2016-01-15

    This study provides a physicochemical assessment of manganese deposits on brass and lead components from two fully operational drinking water distributions systems. One of the systems was maintained with chlorine; the other, with secondary chloramine disinfection. Synchrotron-based in-situ micro X-ray adsorption near edge structure was used to assess the mineralogy. In-situ micro X-ray fluorescence mapping was used to demonstrate the spatial relationships between manganese and potentially toxic adsorbed metal ions. The Mn deposits ranged in thickness from 0.01 to 400 μm. They were composed primarily of Mn oxides/oxhydroxides, birnessite (Mn(3+) and Mn(4+)) and hollandite (Mn(2+) and Mn(4+)), and a Mn silicate, braunite (Mn(2+) and Mn(4+)), in varying proportions. Iron, chromium, and strontium, in addition to the alloying elements lead and copper, were co-located within manganese deposits. With the exception of iron, all are related to specific health issues and are of concern to the U.S. Environmental Protection Agency (U.S. EPA). The specific properties of Mn deposits, i.e., adsorption of metals ions, oxidation of metal ions and resuspension are discussed with respect to their influence on drinking water quality. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Study of the quenching and subsequent return to room temperature of uranium-chromium, uranium-iron, and uranium-molybdenum alloys containing only small amounts of the alloying element; Etude de la trempe et du revenu a la temperature ordinaire d'alliages uranium-chrome, uranium-fer et uranium-molybdene, a faible teneur en element d'alliage

    Energy Technology Data Exchange (ETDEWEB)

    Delaplace, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1960-09-15

    By means of an apparatus which makes possible thermal pre-treatments in vacuo, quenching carried out in a high purity argon atmosphere, and simultaneous recording of time temperature cooling and thermal contraction curves, the author has examined the transformations which occur in uranium-chromium, uranium-iron and uranium-molybdenum alloys during their quenching and subsequent return to room temperature. For uranium-chromium and uranium-iron alloys, the temperature at which the {gamma} {yields} {beta} transformation starts varies very little with the rate of cooling. For uranium-molybdenum alloys containing 2,8 atom per cent of Mo, this temperature is lowered by 120 deg. C for a cooling rate of 500 deg. C/mn. The temperature at which the {beta} {yields} {alpha} transformation starts is lowered by 170 deg. C for a cooling rate of 500 deg. C/mn in the case of uranium-chromium alloy containing 0,37 atom per cent of Cr. The temperature is little affected in the case of uranium-iron alloys. The addition of chromium or iron makes it possible to conserve the form {beta} at ordinary temperatures after quenching from the {beta} and {gamma} regions. The {beta} phase is particularly unstable and changes into needles of the {alpha} form even at room temperatures according to an autocatalytic transformation law similar to the austenitic-martensitic transformation law in the case of iron. The {beta} phase obtained by quenching from the {beta} phase region is more stable than that obtained by quenching from the {gamma} region. Chromium is a more effective stabiliser of the {beta} phase than is iron. Unfortunately it causes serious surface cracking. The {beta} {yields} {alpha} transformation in uranium-chromium alloys has been followed at room temperature by means of micro-cinematography. The author has not observed the direct {gamma} {yields} {alpha} transformation in uranium-molybdenum alloys containing 2,8 per cent of molybdenum even for cooling rates of up to 2000 deg. C

  6. Study of the quenching and subsequent return to room temperature of uranium-chromium, uranium-iron, and uranium-molybdenum alloys containing only small amounts of the alloying element; Etude de la trempe et du revenu a la temperature ordinaire d'alliages uranium-chrome, uranium-fer et uranium-molybdene, a faible teneur en element d'alliage

    Energy Technology Data Exchange (ETDEWEB)

    Delaplace, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1960-09-15

    By means of an apparatus which makes possible thermal pre-treatments in vacuo, quenching carried out in a high purity argon atmosphere, and simultaneous recording of time temperature cooling and thermal contraction curves, the author has examined the transformations which occur in uranium-chromium, uranium-iron and uranium-molybdenum alloys during their quenching and subsequent return to room temperature. For uranium-chromium and uranium-iron alloys, the temperature at which the {gamma} {yields} {beta} transformation starts varies very little with the rate of cooling. For uranium-molybdenum alloys containing 2,8 atom per cent of Mo, this temperature is lowered by 120 deg. C for a cooling rate of 500 deg. C/mn. The temperature at which the {beta} {yields} {alpha} transformation starts is lowered by 170 deg. C for a cooling rate of 500 deg. C/mn in the case of uranium-chromium alloy containing 0,37 atom per cent of Cr. The temperature is little affected in the case of uranium-iron alloys. The addition of chromium or iron makes it possible to conserve the form {beta} at ordinary temperatures after quenching from the {beta} and {gamma} regions. The {beta} phase is particularly unstable and changes into needles of the {alpha} form even at room temperatures according to an autocatalytic transformation law similar to the austenitic-martensitic transformation law in the case of iron. The {beta} phase obtained by quenching from the {beta} phase region is more stable than that obtained by quenching from the {gamma} region. Chromium is a more effective stabiliser of the {beta} phase than is iron. Unfortunately it causes serious surface cracking. The {beta} {yields} {alpha} transformation in uranium-chromium alloys has been followed at room temperature by means of micro-cinematography. The author has not observed the direct {gamma} {yields} {alpha} transformation in uranium-molybdenum alloys containing 2,8 per cent of molybdenum even for cooling rates of up to 2000 deg. C

  7. CONCENTRAÇÕES RESIDUAIS DE COBRE, FERRO, MANGANÊS E ZINCO EM LATOSSOLO ROXO EUTRÓFICO SOB DIFERENTES TIPOS DE MANEJO RESIDUAL CONCENTRATION OF COPPER, IRON, MANGANESE AND ZINC IN EUTROPHIC 'LATOSSOLO ROXO’ UNDER DIFFERENT SOIL MANAGEMENTS

    Directory of Open Access Journals (Sweden)

    Itamar Pereira de Oliveira

    2007-09-01

    shallow harrow plowing and 4 deep stirring, using a chiseling plower and three level of fertilization: 1 Check (natural soil fertility, 2 Goiás State recommendation and 3 Fertilizers to cover the nutrients extracted by grain exportation. Larger values of the pH were observed in the superficial layer of soil submitted to deep moldboard plowing in relation to no-till, shallow harrow plowing and deep stirring. Uniform distributions of iron, manganese and zinc were observed in areas submitted to deep moldboard plowing. The 40-60 cm layer presented similar concentrations in all types of soil management. Copper tried in the superficial layer and at deepest layers can be explained by the larger concentration of organic matter and origin of the soil. No variation was observed in relation to fertilizers application.

    KEY-WORDS: Micronutrients; no till system; cerrado soil.

  8. Purification of molybdenum

    International Nuclear Information System (INIS)

    Cheresnowsky, M.J.; Brunelli, T.A.; Kim, T.K.

    1987-01-01

    A method for purifying molybdenum is described comprising: (a) adding to an ammoniacal ammonium molybdate solution which is at a pH of from about 8.5 to about 11 and which contains the impurities of phosphorus and arsenic with the phosphorus concentration being from about 0.01 to about 0.12 g/l, a soluble magnesium salt to form a precipitate comprising magnesium ammonium salts of the phosphorus and the arsenic, and to form a purified ammonium molybdate solution, with the amount of the magnesium salt being added in an amount sufficient to result in a concentration of from about 0.005 to about 0.04 moles Mg/l in the ammoniacal ammonium molybdate solution, and the purified solution containing no greater than about 0.01 g P/l; (b) separating the precipitate from the purified ammonium molybdate solution; and (c) contacting the purified ammonium molybdate solution with a chelating cation exchange resin supplying a sufficient amount of ammonium as the cation to remove the major portion of the magnesium ions from the purified solution and form a further purified ammonium molybdate solution

  9. Manganese in silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Linnarsson, M.K., E-mail: marga@kth.se [Royal Institute of Technology, School of Information and Communication Technology, P.O. Box E229, SE-16440 Kista-Stockhom (Sweden); Hallen, A. [Royal Institute of Technology, School of Information and Communication Technology, P.O. Box E229, SE-16440 Kista-Stockhom (Sweden)

    2012-02-15

    Structural disorder and relocation of implanted Mn in semi-insulating 4H-SiC has been studied. Subsequent heat treatment of Mn implanted samples has been performed in the temperature range 1400-2000 Degree-Sign C. The depth distribution of manganese is recorded by secondary ion mass spectrometry. Rutherford backscattering spectrometry has been employed for characterization of crystal disorder. Ocular inspection of color changes of heat-treated samples indicates that a large portion of the damage has been annealed. However, Rutherford backscattering shows that after heat treatment, most disorder from the implantation remains. Less disorder is observed in the [0 0 0 1] channel direction compared to [112{sup Macron }3] channel direction. A substantial rearrangement of manganese is observed in the implanted region. No pronounced manganese diffusion deeper into the sample is recorded.

  10. Manganese in silicon carbide

    International Nuclear Information System (INIS)

    Linnarsson, M.K.; Hallén, A.

    2012-01-01

    Structural disorder and relocation of implanted Mn in semi-insulating 4H–SiC has been studied. Subsequent heat treatment of Mn implanted samples has been performed in the temperature range 1400–2000 °C. The depth distribution of manganese is recorded by secondary ion mass spectrometry. Rutherford backscattering spectrometry has been employed for characterization of crystal disorder. Ocular inspection of color changes of heat-treated samples indicates that a large portion of the damage has been annealed. However, Rutherford backscattering shows that after heat treatment, most disorder from the implantation remains. Less disorder is observed in the [0 0 0 1] channel direction compared to [112 ¯ 3] channel direction. A substantial rearrangement of manganese is observed in the implanted region. No pronounced manganese diffusion deeper into the sample is recorded.

  11. Mixed graphite cast iron for automotive exhaust component applications

    Directory of Open Access Journals (Sweden)

    De-lin Li

    2017-11-01

    Full Text Available Both spheroidal graphite iron and compacted graphite iron are used in the automotive industry. A recently proposed mixed graphite iron exhibits a microstructure between the conventional spheroidal graphite iron and compacted graphite iron. Evaluation results clearly indicate the suitability and benefits of mixed graphite iron for exhaust component applications with respect to casting, machining, mechanical, thermophysical, oxidation, and thermal fatigue properties. A new ASTM standard specification (A1095 has been created for compacted, mixed, and spheroidal graphite silicon-molybdenum iron castings. This paper attempts to outline the latest progress in mixed graphite iron published.

  12. Method of molybdenum kinetic determination

    International Nuclear Information System (INIS)

    Krejngol'd, S.U.; Dzotsenidze, N.E.; Ruseishviyai, T.G.; Nelen', I.M.

    1980-01-01

    The method molybdenum kinetic determination according to oxidation of pyrogallol with bromate in the medium of 0.05-0.15 M perchloric or sulphuric acids is presented. 1 mg of Ni, Co, Mn, Mg, Zn, Cr(3); 100 μg of Ca, Al, Cu, 10 μg of Cr(4), W; 10 μg of Fe in the presence of 22x10 - 4 M solution of EDTA, as well as 10 - 4 M solutions of chlorides and fluorides, 10 - 5 M solutions of bromides do not interfere with molybdenum determination using the given method. The method is rather simple, it takes 30 min to carry out the analysis. Determination limit of molybdenum constitutes 0.01 μg/ml

  13. Isotope analysis of molybdenum in selected minerals

    International Nuclear Information System (INIS)

    Becker, S.; Dietze, H.J.

    1980-01-01

    An analytical method is described for the mass spectrometric determination of molybdenum abundance values. The results of analyses of three molybdenum mineral samples are presented and compared with the results of other authors. It is shown that the fine variations of molybdenum in natural minerals cannot be analysed with currently available mass spectrometers

  14. Manganese dipyridoxyl diphosphate:

    DEFF Research Database (Denmark)

    H, Brurok; Ardenkjær-Larsen, Jan Henrik; G, Hansson

    1999-01-01

    Manganese dipyridoxyl diphosphate (MnDPDP) is a contrast agent for magnetic resonance imaging (MRI) of the liver. Aims of the study were to examine if MnDPDP possesses superoxide dismutase (SOD) mimetic activity in vitro, and if antioxidant protection can be demonstrated in an ex vivo rat heart...

  15. Evaluation of molybdenum and its alloys

    International Nuclear Information System (INIS)

    Lundberg, L.B.

    1981-01-01

    The choice of pure molybdenum as the prime candidate material for space reactor core heat pipes is critically examined. Pure molybdenum's high ductile-brittle transition temperature appears to be its major disadvantage. The candidate materials examined in detail for this application include low carbon arc-cast molybdenum, TZM-molybdenum alloy, and molybdenum-rhenium alloys. Published engineering properties are collected and compared, and it appears that Mo-Re alloys with 10 to 15% rhenium offer the best combination. Hardware is presently being made from electron beam melted Mo-13Re to test this conclusion

  16. Manganese, Metallogenium, and Martian Microfossils

    Science.gov (United States)

    Stein, L. Y.; Nealson, K. H.

    1999-01-01

    Manganese could easily be considered an abundant element in the Martian regolith, assuming that the composition of martian meteorites reflects the composition of the planet. Mineralogical analyses of 5 SNC meteorites have revealed an average manganese oxide concentration of 0.48%, relative to the 0.1% concentration of manganese found in the Earth's crust. On the Earth, the accumulation of manganese oxides in oceans, soils, rocks, sedimentary ores, fresh water systems, and hydrothermal vents can be largely attributed to microbial activity. Manganese is also a required trace nutrient for most life forms and participates in many critical enzymatic reactions such as photosynthesis. The wide-spread process of bacterial manganese cycling on Earth suggests that manganese is an important element to both geology and biology. Furthermore, there is evidence that bacteria can be fossilized within manganese ores, implying that manganese beds may be good repositories for preserved biomarkers. A particular genus of bacteria, known historically as Metallogenium, can form star-shaped manganese oxide minerals (called metallogenium) through the action of manganese oxide precipitation along its surface. Fossilized structures that resemble metallogenium have been found in Precambrian sedimentary formations and in Cretaceous-Paleogene cherts. The Cretaceous-Paleogene formations are highly enriched in manganese and have concentrations of trace elements (Fe, Zn, Cu, and Co) similar to modern-day manganese oxide deposits in marine environments. The appearance of metallogenium-like fossils associated with manganese deposits suggests that bacteria may be preserved within the minerals that they form. Additional information is contained in the original extended abstract.

  17. Producción de hierros nodulares ferríticos directamente de fundición partiendo de chatarra de acero de alto manganeso // Production of ferrítics nodular irons directly from foundry leaving of high manganese scrap steel

    Directory of Open Access Journals (Sweden)

    C. DeFranch

    1999-07-01

    ñinos; lo que necesitaría de una gran inversión en cuanto a extractores y procesadores de estos gases.Los factores críticos en el proceso que emplea óxido de hierro para la eliminación del manganeso son: temperatura,composición química del baño y elementos presentes en la escoria, con el mismo se han logrado eliminaciones del manganesode hasta un 80% del contenido inicial y fundiciones ferríticas con elongaciones de hasta un 23%.Palabras claves: hierro nodular, fundición___________________________________________________________________________AbstractThe production of nodular irons with main ferrític is usually achieved with the use of special arrabios with contained first floorof elements formadores of carbides, or by means of long and expensive thermal treatments. These arrabios has high prices, forwhat becomes necessary the search of more economic variants for the production of this material type. The objective of thiswork is the obtaining of this material using like load steel scrap, which has a price a lot but I lower.The structure of the womb in the nodular iron, depends on its chemical composition, its cooling speed, as well as of the formand quantity of graphite nodules. When is wanted a main ferrítics, the elements who make the perlitic estructure they shouldbe maintained in contents the lowest thing possible for less susecful this way the solidification according to the diagram.The scrap use outlines the problem of the present manganese levels in the same one (generally between 0.6 and 0.8%. Themanganese that is an element who make the perlitic estructure avoids the obtaining of high elongations since the womb itDr. Ing C. DeFranch, Dr. Ing. T. Rodríguez Moliner26would be never completely ferrític. It is for this reason that if she/he wants himself to use steel scrap as load material it isnecessary the study in ways of eliminating it of the bathroom.For the elimination of the manganese diverse references exist in the literature to processes

  18. Gel Fabrication of Molybdenum “Beads”

    Energy Technology Data Exchange (ETDEWEB)

    Lowden, Richard Andrew [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Armstrong, Beth L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Cooley, Kevin M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

    2016-11-01

    Spherical molybdenum particles or “beads” of various diameters are of interest as feedstock materials for the additive manufacture of targets and assemblies used in the production of 99Mo medical isotopes using accelerator technology. Small metallic beads or ball bearings are typically fabricated from wire; however, small molybdenum spheres cannot readily be produced in this manner. Sol-gel processes are often employed to produce small dense microspheres of metal oxides across a broad diameter range that in the case of molybdenum could be reduced and sintered to produce metallic spheres. These Sol-gel type processes were examined for forming molybdenum oxide beads; however, the molybdenum trioxide was chemically incompatible with commonly used gelation materials. As an alternative, an aqueous alginate process being assessed for the fabrication of oxide spheres for catalyst applications was employed to form molybdenum trioxide beads that were successfully reduced and sintered to produce small molybdenum spheres.

  19. HYDROGEN VACANCY INTERACTION IN MOLYBDENUM

    NARCIS (Netherlands)

    Abd El Keriem, M.S.; van der Werf, D.P.; Pleiter, F

    1993-01-01

    Vacancy-hydrogen interaction in molybdenum was investigated by means of the perturbed angular correlation technique, using the isotope In-111 as a probe. The complex InV2 turned out to trap up to two hydrogen atoms: trapping of a single hydrogen atom gives rise to a decrease of the quadrupole

  20. Effects of carbon and molybdenum on the microstructures of high chromium white cast irons; Efeito do carbono e do molibdenio na microestrutura dos ferros fundidos brancos de alto cromo

    Energy Technology Data Exchange (ETDEWEB)

    Sinatora, Amilton; Ambrosio Filho, Francisco; Goldenstein, Helio; Fuoco, Ricardo; Albertin, Eduardo; Mei, Paulo Roberto

    1992-12-31

    The effects of 3 levels of carbon and 1.5% Mo addition on the solidification structures of a 15% chromium white cast iron were studied. The volume fraction of primary austenite and of eutectic carbides, as well as the number of carbide particles per unit length and the mean secondary dendrite arm spacing were measured. By means of thermal analysis, thermal arrest corresponding to the formation of the primary austenite and of the eutectic were determined. The increase in the carbon content and the addition of Mo led to lowering of the thermal arrests and to coarsening of the particles. (author) 15 refs., 6 figs., 5 tabs.

  1. ARSENIC REMOVAL BY IRON REMOVAL PROCESSES

    Science.gov (United States)

    Presentation will discuss the removal of arsenic from drinking water using iron removal processes that include oxidation/filtration and the manganese greensand processes. Presentation includes results of U.S. EPA field studies conducted in Michigan and Ohio on existing iron remo...

  2. Synthesis and characterization of iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of salicylidene-N-anilinoacetohydrazone (H2L1) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H2L2).

    Science.gov (United States)

    AbouEl-Enein, S A; El-Saied, F A; Kasher, T I; El-Wardany, A H

    2007-07-01

    Salicylidene-N-anilinoacetohydrazone (H(2)L(1)) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H(2)L(2)) and their iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes have been synthesized and characterized by IR, electronic spectra, molar conductivities, magnetic susceptibilities and ESR. Mononuclear complexes are formed with molar ratios of 1:1, 1:2 and 1:3 (M:L). The IR studies reveal various modes of chelation. The electronic absorption spectra and magnetic susceptibility measurements show that the iron(III), nickel(II) and cobalt(II) complexes of H(2)L(1) have octahedral geometry. While the cobalt(II) complexes of H(2)L(2) were separated as tetrahedral structure. The copper(II) complexes have square planar stereochemistry. The ESR parameters of the copper(II) complexes at room temperature were calculated. The g values for copper(II) complexes proved that the Cu-O and Cu-N bonds are of high covalency.

  3. Hydrogeochemistry in a relatively unmodified subtropical catchment: Insights regarding the health and aesthetic risks of manganese

    Directory of Open Access Journals (Sweden)

    Adam K. Rose

    2017-10-01

    New hydrological insights for region: Results show that the hydrogeochemistry of Baffle Creek was predominantly driven by rain events, with differing responses to varying magnitudes of rain and discharge. Following a flushing event, dissolved aluminium and nitrate increased in the surface and drinking water, whereas manganese and ammonia were undetectable in the drinking water and occurred only in small concentrations in the surface waters. In contrast, when rainfall events occurred without an associated flush, manganese, iron and ammonia concentrations increased in the drinking water. The hydrochemistry of manganese and iron in the supply chain infrastructure was strongly positively correlated with ammonia, and aluminium correlated with nitrate concentrations. Currently the drinking water supply does not pose a threat to chronic manganese exposure for humans, however elevated concentrations are experienced periodically; and may become more problematic under climate change scenarios.

  4. A study on the alkali leaching of complex compound for molybdenum trioxide and ferric oxide

    International Nuclear Information System (INIS)

    Kim, C.G.; Whang, Y.K.

    1981-01-01

    This study is to determine the alkali-leaching meachanism by which complex compound by the reaction made between molybdenite (MoS 2 ) and ferric oxide (Fe 2 O 3 ) in the roasted are when molybdenum trioxide (MoO 3 ) is formed by the roasting reaction of molybdenite concentrate. The results obtained from this experiment are summarized as follows: The heating reaction analysis shows that the complex compound of iron molybdates (Fe 2 O 3 .3-4 MoO 3 ) is formed by the reaction of molybdenum trioxide and ferric oxide at temperatures of above 500 0 C. It is shown that at various reaction temperature below 400 0 C molybdenum trioxide is almost completely leached by caustic soda irrespective of the mole ratio of two chemical samples used for the experiment, whereas at temperature above 400 0 C the leaching rate of molybdenum trioxide decreases except that it varies from 70.77% at a temperature of 900 0 C at which the mole ratio is 1 to 1 to 84.08% at a temperature of 1000 0 C. The x-ray diffraction analysis has shown that the complex compound reacted at a temperature of 1000 0 C produces a complex compound with the crystal structure of iron molybdates, and the alkali-leached residues even with 19.0% of molybdenum trioxide, however, contain only α-Fe 2 O 3 , without showing iron molybdates. The crystalline compound of iron molybdates obtained as a result of heating reaction was leached by using caustic soda, while MoO 3 and Fe 2 O 3 in the leaching residue was found to contain other compounds unable to be leached by caustic soda. (author)

  5. Biological manganese removal from acid mine drainage in constructed wetlands and prototype bioreactors.

    Science.gov (United States)

    Hallberg, Kevin B; Johnson, D Barrie

    2005-02-01

    Mine drainage waters vary considerably in the range and concentration of heavy metals they contain. Besides iron, manganese is frequently present at elevated concentrations in waters draining both coal and metal mines. Passive treatment systems (aerobic wetlands and compost bioreactors) are designed to remove iron by biologically induced oxidation/precipitation. Manganese, however, is problematic as it does not readily form sulfidic minerals and requires elevated pH (>8) for abiotic oxidation of Mn (II) to insoluble Mn (IV). As a result, manganese removal in passive remediation systems is often less effective than removal of iron. This was found to be the case at the pilot passive treatment plant (PPTP) constructed to treat water draining the former Wheal Jane tin mine in Cornwall, UK, where effective removal of manganese occurred only in one of the three rock filter components of the composite systems over a 1-year period of monitoring. Water in the two rock filter systems where manganese removal was relatively poor was generally system. These differences in water chemistry and manganese removal were due to variable performances in the compost bioreactors that feed the rock filter units in the composite passive systems at Wheal Jane. An alternative approach for removing soluble manganese from mine waters, using fixed bed bioreactors, was developed. Ferromanganese nodules (about 2 cm diameter), collected from an abandoned mine adit in north Wales, were used to inoculate the bioreactors (working volume ca. 700 ml). Following colonization by manganese-oxidizing microbes, the aerated bioreactor catalysed the removal of soluble manganese, via oxidation of Mn (II) and precipitation of the resultant Mn (IV) in the bioreactor, in synthetic media and mine water from the Wheal Jane PPTP. Such an approach has potential application for removing soluble Mn from mine streams and other Mn-contaminated water courses.

  6. Neutron scattering and models: molybdenum

    International Nuclear Information System (INIS)

    Smith, A.B.

    1999-01-01

    A comprehensive interpretation of the fast-neutron interaction with elemental and isotopic molybdenum at energies of le 30 MeV is given. New experimental elemental-scattering information over the incident energy range 4.5 r a rrow 10 MeV is presented. Spherical, vibrational and dispersive models are deduced and discussed, including isospin, energy-dependent and mass effects. The vibrational models are consistent with the ''Lane potential''. The importance of dispersion effects is noted. Dichotomies that exist in the literature are removed. The models are vehicles for fundamental physical investigations and for the provision of data for applied purposes. A ''regional'' molybdenum model is proposed. Finally, recommendations for future work are made

  7. CVD molybdenum films of high infrared reflectance

    Energy Technology Data Exchange (ETDEWEB)

    Carver, G. E.

    1979-01-01

    Molybdenum thin films of high infrared reflectance have been deposited by pyrolytic decomposition of molybdenum carbonyl (Mo(CO)/sub 6/), and by hydrogen reduction of molybdenum pentachloride (MoCl/sub 5/). Reflectance values within 0.7% of the reflectance of supersmooth bulk molybdenum have been attained by annealing films of lower reflectance in both reducing and non-reducing atmospheres. All depositions and anneals proceed at atmospheric pressure, facilitating a continuous, flow-through fabrication. These reflectors combine the high temperature stability of molybdenum thin films with the infrared reflectance of a material such as aluminum. Deposition from Mo(CO)/sub 6/ under oxidizing conditions, and subsequent anneal in a reducing atmosphere, results in films that combine high solar absorptance with low thermal emittance. If anti-reflected, black molybdenum films can serve as highly selective single layer photothermal converters. Structural, compositional, and crystallographic properties have been measured after both deposition and anneal.

  8. Molybdenum: the element and aqueous solution chemistry

    International Nuclear Information System (INIS)

    Sykes, A.G.

    1987-01-01

    This chapter on the chemistry of the coordination compounds of molybdenum concentrates on the element itself, its recovery from ores and its use in the manufacture of steels. Most of the chapter is devoted to the aqueous solution chemistry of molybdenum in oxidation states II, III and IV. (UK)

  9. Investigation of pressing of molybdenum powder compacts

    International Nuclear Information System (INIS)

    Mymrin, S.A.; Kuznetsov, V.Eh.; Yampol'skij, M.L.; Leonov, S.A.; Mikhridinov, R.M.; Korzukhin, V.A.

    1990-01-01

    Results of an experimental investigation into pressing of compacts of MCh type molybdenum powders using the industrial equipment are presented. To measure the density of powder molybdenum billets a radioisotopic density meter with cesium-137 is used as radioactive gamma radiation source. The dependence of the produced billet density on the specific compacting pressure at different values of the powder bulk density is ascertained

  10. Extraction of molybdenum VI by alpha benzoinoxime

    International Nuclear Information System (INIS)

    Achache, M.; Meklati, M.

    1990-06-01

    The concentration of molybdenum, was studied using alpha benzoinoxime dissolved in chloroform. Several acids and salt at different levels of concentration were investigated as well as other parameters such as (mixing time, extractant to metal ratio, temperature etc.) The molybdenum stippling was also studied in alkaline medium with the subsequent recovery of the extractant and solvent

  11. Molybdenum sealing glass-ceramic composition

    International Nuclear Information System (INIS)

    Eagan, R.J.

    1976-01-01

    A glass-ceramic composition is described having low hydrogen and helium permeability properties, along with high fracture strength, and a thermal coefficient of expansion similar to that of molybdenum. The composition is adaptable for hermetically sealing to molybdenum at temperatures between 900 and about 950 0 C to form a hermetically sealed insulator body

  12. Influence of molybdenum on the high-temperature mechanical resistance especially creep resistance around 7000C of 18-14 type stainless steels

    International Nuclear Information System (INIS)

    Ben Marzouk, M.T.

    1977-06-01

    The influence of molybdenum on the mechanical properties under traction, the creep parameters, sub-structure and diffusion parameters of iron in stainless steels was investigated. Between 20 0 C and 800 0 C molybdenum has no significant effect on the elastic limit, breaking load or consolidation coefficient but increases the distributed elongation between 500 0 C and 800 0 C; its influence is greatest at 700 0 C. Addition of molybdenum reduces the creep rate at high temperature from the start of the test up to breaking point. In the temperature range studied, 600 0 C to 900 0 C, its influence is greatest at 600 0 C, decreases as the temperature rises and disappears at 900 0 C. Addition of 2% molybdenum increases the activation energy from 72 kcal/mole to 88 kcal/mole. At 700 0 C molybdenum hardly affects the precipitation and structure of dislocations but delays healing processes. Between 1000 0 C and 1300 0 C molybdenum has no effect on the iron diffusion coefficient: Q=68.7kcal/mole, D 0 =1.3cm 2 /s. The influence of Mo on the creep resistance of austenitic steels between 600 0 C and 900 0 C does not seem to be due to precipitation but to a solid solution effect, which could be a decrease in the diffusion coefficient of iron below 900 0 C [fr

  13. Materials for Molybdenum 99 purification

    International Nuclear Information System (INIS)

    Wilkinson, M. Victoria; Mondino, Angel V.; Manzini, Alberto C.

    2003-01-01

    The National Atomic Energy Commission (CNEA) produces fission Mo 99, an isotope of wide use in nuclear medicine. In order to simplify the current Mo 99 production process, to shorten its duration and reduce impurities in the final product, alternative methods for purification steps were looked for. In this work a variety of new materials for the purification columns were designed, all of them with carbon. These materials were studied and a material which contribute with the best results for molybdenum retention, was selected. The preparation procedure and the working conditions were determined. (author)

  14. Molybdenum Oxides - From Fundamentals to Functionality.

    Science.gov (United States)

    de Castro, Isabela Alves; Datta, Robi Shankar; Ou, Jian Zhen; Castellanos-Gomez, Andres; Sriram, Sharath; Daeneke, Torben; Kalantar-Zadeh, Kourosh

    2017-10-01

    The properties and applications of molybdenum oxides are reviewed in depth. Molybdenum is found in various oxide stoichiometries, which have been employed for different high-value research and commercial applications. The great chemical and physical characteristics of molybdenum oxides make them versatile and highly tunable for incorporation in optical, electronic, catalytic, bio, and energy systems. Variations in the oxidation states allow manipulation of the crystal structure, morphology, oxygen vacancies, and dopants, to control and engineer electronic states. Despite this overwhelming functionality and potential, a definitive resource on molybdenum oxide is still unavailable. The aim here is to provide such a resource, while presenting an insightful outlook into future prospective applications for molybdenum oxides. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Microwave Production of Manganese from Manganese (IV) Oxide ...

    African Journals Online (AJOL)

    Michael O. Mensah

    2015-12-02

    Dec 2, 2015 ... energy consumption occurs in the upper part of the ferromanganese furnace ... The pre-reduction of manganese ores by carbon has been investigated by Abdel ..... Awaso Bauxite Ore using Waste Pure Water. Sachets as ...

  16. Manganese deficiency in plants

    DEFF Research Database (Denmark)

    Schmidt, Sidsel Birkelund; Jensen, Poul Erik; Husted, Søren

    2016-01-01

    Manganese (Mn) is an essential plant micronutrient with an indispensable function as a catalyst in the oxygen-evolving complex (OEC) of photosystem II (PSII). Even so, Mn deficiency frequently occurs without visual leaf symptoms, thereby masking the distribution and dimension of the problem...... restricting crop productivity in many places of the world. Hence, timely alleviation of latent Mn deficiency is a challenge in promoting plant growth and quality. We describe here the key mechanisms of Mn deficiency in plants by focusing on the impact of Mn on PSII stability and functionality. We also address...... the mechanisms underlying the differential tolerance towards Mn deficiency observed among plant genotypes, which enable Mn-efficient plants to grow on marginal land with poor Mn availability....

  17. Vapor deposition of molybdenum oxide using bis(ethylbenzene) molybdenum and water

    International Nuclear Information System (INIS)

    Drake, Tasha L.; Stair, Peter C.

    2016-01-01

    Three molybdenum precursors—bis(acetylacetonate) dioxomolybdenum, molybdenum isopropoxide, and bis(ethylbenzene) molybdenum—were tested for molybdenum oxide vapor deposition. Quartz crystal microbalance studies were performed to monitor growth. Molybdenum isopropoxide and bis(ethylbenzene) molybdenum achieved linear growth rates 0.01 and 0.08 Å/cycle, respectively, using atomic layer deposition techniques. Negligible MoO_x growth was observed on alumina powder using molybdenum isopropoxide, as determined by inductively coupled plasma optical emission spectroscopy. Bis(ethylbenzene) molybdenum achieved loadings of 0.5, 1.1, and 1.9 Mo/nm"2 on alumina powder after one, two, and five cycles, respectively, using atomic layer deposition techniques. The growth window for bis(ethylbenzene) molybdenum is 135–150 °C. An alternative pulsing strategy was also developed for bis(ethylbenzene) molybdenum that results in higher growth rates in less time compared to atomic layer deposition techniques. The outlined process serves as a methodology for depositing molybdenum oxide for catalytic applications. All as-deposited materials undergo further calcination prior to characterization and testing.

  18. Crystal structure of (Na0.70(Na0.70,Mn0.30(Fe3+,Fe2+2Fe2+(VO43, a sodium-, iron- and manganese-based vanadate with the alluaudite-type structure

    Directory of Open Access Journals (Sweden)

    Elhassan Benhsina

    2016-02-01

    Full Text Available The title compound, sodium (sodium,manganese triiron(II,III tris[vanadate(V], (Na0.70(Na0.70,Mn0.30(Fe3+,Fe2+2Fe2+(VO43, was prepared by solid-state reactions. It crystallizes in an alluaudite-like structure, characterized by a partial cationic disorder. In the structure, four of the 12 sites in the asymmetric unit are located on special positions, three on a twofold rotation axis (Wyckoff position 4e and one on an inversion centre (4b. Two sites on the twofold rotation axis are entirely filled by Fe2+ and V5+, whereas the third site has a partial occupancy of 70% by Na+. The site on the inversion centre is occupied by Na+ and Mn2+ cations in a 0.7:0.3 ratio. The remaining Fe2+ and Fe3+ atoms are statistically distributed on a general position. The three-dimensional framework of this structure is made up of kinked chains of edge-sharing [FeO6] octahedra stacked parallel to [10-1]. These chains are held together by VO4 tetrahedral groups, forming polyhedral sheets perpendicular to [010]. Within this framework, two types of channels extending along [001] are present. One is occupied by (Na+/Mn2+ while the second is partially occupied by Na+. The mixed site containing (Na+/Mn2+ has an octahedral coordination sphere, while the Na+ cations in the second channel are coordinated by eight O atoms.

  19. A regional mineralogical study of the manganese-bearing Voelwater subgroup in the northern Cape Province

    International Nuclear Information System (INIS)

    Kleyenstueber, A.S.E.

    1985-11-01

    The Voelwater Subgroup, of the Proterozoic Transvaal Sequence, in the Hotazel area, is preserved in five structurally controlled basins, on the eastern side of the Dimoten syncline. The Subgroup represents a relatively undisturbed unit of mixed volcanogenic - chemical sedimentary rocks. The Hotazel Formation within the Voelwater Subgroup, consists of a finely banded carbonate - silicate - hematite - manganese lutite sequence of banded iron-formation and must be unique in that it contains the world's largest land-based repository of manganese. Twenty-one drill cores, sampled lithologically at intervals of approximately one metre through the total sedimentary sequence, were studied by microscopic, X-ray diffraction and electron microprobe methods. The mineralogy of the Voelwater Subgroup was studied on a regional scale, with the emphasis on the minerals within the manganese beds of the Hotazel Formation. The objective of the study was: a. To study the variation and distrubution of minerals in the various manganese ores on a regional scale. b. To compare the mineralogical differences of the different ores mined, in order to gain a better understanding of their metallurgical behaviour. c. To try to locate high-grade manganese ore target areas for future exploration, with the aid of mineralogical information. d. To try to establish the origin of the manganese in the Voelwater Formation. e. To study the relationship of the manganese units with the adjacent chemical sediments of the Hotazel Formation

  20. Magnetic properties and morphology of manganese ferrite nanoparticles in glasses

    International Nuclear Information System (INIS)

    Edelman, I; Ivanova, O; Ivantsov, I; Velikanov, D; Petrakovskaja, E; Artemenko, A; Curély, J; Kliava, J; Zaikovskiy, V; Stepanov, S

    2011-01-01

    Static magnetization (SM), magnetic circular dichroism (MCD) and electron magnetic resonance (EMR) studies are reported of borate glasses 22.5 K 2 O-22.5 Al 2 O 3 -55 B 2 O 3 co-doped with iron and manganese oxides. In as-prepared glasses the paramagnetic ions usually are in diluted state; however, if the ratio of the iron and manganese oxides in the charge is 3/2, magnetic nanoparticles are found already in as-prepared glass. After additional thermal treatment all glasses show magnetic behaviour, MCD and EMR due to the presence of magnetic nanoparticles with characteristics close to those of manganese ferrite. By computer simulating the EMR spectra at variable temperatures, their morphological characteristics are deduced: relatively broad size and shape distribution with average diameter of ca. 3-4 nm. The characteristic temperature-dependent shift of the apparent resonance field is explained by a strong temperature dependence of the magnetocrystalline anisotropy in the nanoparticles. The potassium-alumina-borate glasses containing magnetic nanoparticles represent a novel class of materials: t ransparent magnets . Indeed, they remain transparent in a part of visible and near infrared spectral range while showing magnetic and magneto-optical properties characteristic of magnetically ordered materials.

  1. Manganese Research Health Project (MHRP)

    Science.gov (United States)

    2009-02-01

    green nucleic acid staining further confirmed the neurotoxic effect of cadmium in this cell model (Fig 10C). Next, we examined the enzymatic activity...Quantification of Nissl bodies revealed a widespread reduction in SNpc cell numbers. Other areas of the basal ganglia were also altered by manganese as...the substantia nigra pars compacta (SNpc) following manganese treatment. Quantification of Nissl bodies revealed a widespread reduction in SNpc

  2. molybdenum

    African Journals Online (AJOL)

    A [13]). However, the larger size leads to an enhanced Si-C bond length (1.868 A [13]) relative to that of the C-C bond (1.527 Á [13]). This leads to a net cancellation of effects. Consequently the data suggest that the SiMe, and 'Bu appear of similar size when viewed from the centroid of the substituted cyclopentadienyl ligand ...

  3. Manganese Deposits in the Artillery Mountains Region, Mohave County, Arizona

    Science.gov (United States)

    Lasky, S.G.; Webber, B.N.

    1944-01-01

    The manganese deposits of the Artillery Mountains region lie within an area of about 25 square miles between the Artillery and Rawhide Mountains, on the west side of the Bill Williams River in west-central Arizona. The richest croppings are on the northeast side of this area, among the foothills of the Artillery Mountains. They are 6 to 10 miles from Alamo. The nearest shipping points are Congress, about 50 miles to the east, and Aguila, about 50 miles to the southeast. The principal manganese deposits are part of a sequence of alluvial fan and playa material, probably of early Pliocene age, which were laid down in a fault basin. They are overlain by later Pliocene (?) basalt flows and sediments and by Quaternary basalt and alluvium. The Pliocene (?) rocks are folded into a shallow composite S1ncline ttat occupies the valley between the Artillery and Rawhide Mountains, and the folded rocks along either side of the valley, together with the overlying Quaternary basalt, are broken by faults that have produced a group of horsts, grabens, and step-fault blocks. The manganiferous beds, lie at two zones, 750 to 1,000 feet apart stratigraphically, each of which is locally as much as 300 to 400 feet thick. The main, or upper, zone contains three kinds of ore - sandstone ore, clay ore, and 'hard' ore. The sandstone and clay ores differ from the associated barren sandstone and clay, with which they are interlayered and into which they grade, primarily in containing a variable proportion of amorphous manganese oxides, besides iron oxides and clayey material such as are present in the barren beds. The 'hard' ore is sandstone that has been impregnated with opal and calcite and in which the original amorphous manganese oxides have been largely converted to psilomelane and manganite. The average manganese content of the sandstone and clay ores is between 3 and 4 percent and that of the 'hard' ore is between 6 and 7 percent. The ore contains an average of 3 percent of iron, 0

  4. Reductive Leaching Kinetics of Low Grade Manganese Deposits in H2SO4 Solution Using Malonic Acid as Reducing Agent

    OpenAIRE

    Taysser Lasheen; S. A. Abu Elenein; W. A. Saleh; A. H Orabi; D. A Ismaiel

    2014-01-01

    A leaching process was developed to extract manganese and metal values from Alloga manganese concentrate. The preferential leaching process was achieved through reductive leaching in dilute sulfuric acid medium with malonic acid as the reducing agent. Leaching parameters were optimized as 1.0 M H2SO4, 10% malonic acid in solid/liquid ratio 1:10 for 90 min at 80 C and using ore ground to – 74 µm. Under these conditions, the leaching efficiency of manganese reaches 97%, whilst iron dissolution ...

  5. Mechanistic Studies of the Iron and Molybdenum Nitrogenases

    OpenAIRE

    Harris, Derek

    2017-01-01

    As a basic building block in many biological molecules the element nitrogen (N) is essential for life. Dinitrogen (N2) is abundant in Earth’s atmosphere, but this form is biologically unavailable. To be biologically available N2 must undergo an energy demanding reduction reaction to the fixed form, ammonia (NH3). The industrial Haber-Bosch process, which accounts for approximately 50% of the worlds fixed nitrogen, uses energy from fossil fuels to achieve high pressures and temperatures to fac...

  6. Features of soldering of molybdenum a lols

    International Nuclear Information System (INIS)

    Grishin, V.L.; Rybkin, B.V.; Cherkasov, A.F.

    1980-01-01

    Soldering features of complex-alloy molybdenum alloys were investigated in comparison with alloys based on solid solutions. Soldering features of heterogeneous molybdenum base alloys were investigated using samples of 0.5-1.O mm sheets with the strain of about 95% made of ingots which had been smelted in arc vacuum furnaces. The soldering of samples was carried out in 5x1O -5 mm Hg vacuum using different sources of heating: radiation, electron-ray and contact. It was shown that heat-resisting soldered joints of heterogeneous molybdenum alloys could be produced using zirconium and niobium base solders containing the most effective hardeners of the parent material (titanum, vanadium, tantalum, molybdenum, tungsten). To preserve high mechanical properties of heterogeneous alloys it was expedient to use for welding local heating sources which permitted to decrease considerably temperature- time conditions of the process

  7. Large-Batch Reduction of Molybdenum Trioxide

    Energy Technology Data Exchange (ETDEWEB)

    Kiggans, Jr, James O. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lowden, Richard Andrew [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Menchhofer, Paul A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Nunn, Stephen D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bryan, Chris [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-12-01

    Unconverted, isotopically-enriched molybdenum metal must be recovered from the spent radiopharmaceutical solution used in NorthStar’s Technetium-99m generator and reused. The recycle process begins by recovering the metal from the aqueous potassium molybdate (K2MoO4) solutions as molybdenum trioxide (MoO3) employing a process developed at Argonne National Laboratory. The MoO3 powder is subsequently reduced to molybdenum metal powder which can be blended with new powder and further processed into a flowable form to be used to produce target disks for irradiation. The molybdenum oxide reduction process has been examined and scaled to produce kilogram quantities of metal powder suitable for processing into a useable form employing spray drying or similar technique and ultimately used for target fabrication.

  8. Spectrophotometric determination of molybdenum with non-ionic surfactant and thiocyanate

    International Nuclear Information System (INIS)

    Hayashi, Kenjiro; Yamamoto, Atsuo; Fujimura, Yasue; Ito, Saburo.

    1980-01-01

    Although the molybdenum (V)-thiocyanate complex is quite stable in non-aqueous solvent such as ether, the complex in dilute acidic solution is unstable. However, this unstable complex was stabilized remarkably by addition of some non-ionic surfactant such as Triton X-100 (alkylphenolpolyoxyethylene ether). The application of this stabilizing effect of the surfactant to the photometric determination of trace amounts of molybdenum with thiocyanate resulted in an increase in the sensitivity. The rate of formation of the Mo(V)-SCN complex was affected by the presence of ferrous ion and its rate constant was proportional to the concentration of Fe(II). The stabilizing effect of the surfactant on the yellowish orange coloration can be understood if we assume that the Mo(V)-SCN complex is incorporated into the micelles of Triton X-100 as [H 2 + , MoO(CNS) 5 2- ]. The optimum condition for the determination of molybdenum is as follows: concentration of sulfuric acid, 0.22 mol dm -3 ; Triton X-100, 0.8%; ascorbic acid, 0.32 mol dm -3 ; thiocyanate, 0.30 mol dm -3 ; iron, 40 mg dm -3 ; standing time for coloration, 10 min and more. Beer's law was obeyed over the range (1 -- 233) μg/50 cm 3 . The molar absorption coefficient at 468 nm was 1.7 2 x 10 4 cm -1 mol -1 dm 3 . The maximum permissible limits of foreign ions (mg/50 cm 3 ) were as follows: Ni(30); Co(12); W(VI) (2); Cu, Zn, V(V) (3); Cr(VI) (5). Large amounts of iron interfered, but this interference was removed by addition of the same amount of iron to the reagent blank. Trace amounts of molybdenum in steel was determined by this method with satisfactory results. (author)

  9. Extraction of manganese from electrolytic manganese residue by bioleaching.

    Science.gov (United States)

    Xin, Baoping; Chen, Bing; Duan, Ning; Zhou, Changbo

    2011-01-01

    Extraction of manganese from electrolytic manganese residues using bioleaching was investigated in this paper. The maximum extraction efficiency of Mn was 93% by sulfur-oxidizing bacteria at 4.0 g/l sulfur after bioleaching of 9days, while the maximum extraction efficiency of Mn was 81% by pyrite-leaching bacteria at 4.0 g/l pyrite. The series bioleaching first by sulfur-oxidizing bacteria and followed by pyrite-leaching bacteria evidently promoted the extraction of manganese, witnessing the maximum extraction efficiency of 98.1%. In the case of sulfur-oxidizing bacteria, the strong dissolution of bio-generated sulfuric acid resulted in extraction of soluble Mn2+, while both the Fe2+ catalyzed reduction of Mn4+ and weak acidic dissolution of Mn2+ accounted for the extraction of manganese with pyrite-leaching bacteria. The chemical simulation of bioleaching process further confirmed that the acid dissolution of Mn2+ and Fe2+ catalyzed reduction of Mn4+ were the bioleaching mechanisms involved for Mn extraction from electrolytic manganese residues. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Progress in development of iron base alloys

    International Nuclear Information System (INIS)

    Zackay, V.V.; Parker, E.R.

    1980-01-01

    The ways of development of new iron base high-strength alloys are considered. Perspectiveness of ferritic steel strengthening with intermetallides (TaFe 2 , for instance) is shown. Favourable combination of plasticity, strength and fracture toughness in nickel-free iron-manganese alloys (16-20%) is also pointed out. A strength level of alloyed maraging steels can be achieved by changes in chemical composition and by proper heat treatments of low- and medium-alloyed steels

  11. Molybdenum solubility in aluminium nitrate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Heres, X.; Sans, D.; Bertrand, M.; Eysseric, C. [CEA, Centre de Marcoule, Nuclear Energy Division, DRCP, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France); Brackx, E.; Domenger, R.; Excoffier, E. [CEA, Centre de Marcoule, Nuclear Energy Division, DTEC, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France); Valery, J.F. [AREVA-NC, DOR/RDP, Paris - La Defense (France)

    2016-07-01

    For over 60 years, research reactors (RR or RTR for research testing reactors) have been used as neutron sources for research, radioisotope production ({sup 99}Mo/{sup 99m}Tc), nuclear medicine, materials characterization, etc... Currently, over 240 of these reactors are in operation in 56 countries. They are simpler than power reactors and operate at lower temperature (cooled to below 100 C. degrees). The fuel assemblies are typically plates or cylinders of uranium alloy and aluminium (U-Al) coated with pure aluminium. These fuels can be processed in AREVA La Hague plant after batch dissolution in concentrated nitric acid and mixing with UOX fuel streams. The aim of this study is to accurately measure the solubility of molybdenum in nitric acid solution containing high concentrations of aluminium. The higher the molybdenum solubility is, the more flexible reprocessing operations are, especially when the spent fuels contain high amounts of molybdenum. To be most representative of the dissolution process, uranium-molybdenum alloy and molybdenum metal powder were dissolved in solutions of aluminium nitrate at the nominal dissolution temperature. The experiments showed complete dissolution of metallic elements after 30 minutes long stirring, even if molybdenum metal was added in excess. After an induction period, a slow precipitation of molybdic acid occurs for about 15 hours. The data obtained show the molybdenum solubility decreases with increasing aluminium concentration. The solubility law follows an exponential relation around 40 g/L of aluminium with a high determination coefficient. Molybdenum solubility is not impacted by the presence of gadolinium, or by an increasing concentration of uranium. (authors)

  12. Elimination of excess molybdenum by cattle

    Energy Technology Data Exchange (ETDEWEB)

    Toelgyesi, G.; Elmoty, I.A.

    1967-01-01

    It was found that cattle would ingest spontaneously 5-15 g of molybdenum on one occasion. The uptake of this quantity caused but moderate loss of appetite and mild enteritis, both normalizing in one week. The occurrence of a severe acute molybdenum poisoning can be practically excluded, owing to refusal of the poisoned feed. Spontaneously ingested molybdenum caused on the first day a 30-100 fold rise of ruminal Mo-level, decreasing to the order of the normal value in about one week. But in the urine and faeces, Mo-level was at least 10 fold, in the blood and milk about 4 fold of the normal one, even one or two weeks after ingestion. During this period at least 90% of ingested Mo was eliminated with the faeces, urine and milk. One week after the ingestion of molybdenum, the rumen content showed no evidence on poisoning and no trace of molybdenum. Oral administration of ammonium molybdenate in an amount equivalent to 40 g molybdenum caused no fatality. In fact, cattle would never ingest spontaneously such a large dose.

  13. Method of producing oxidation resistant coatings for molybdenum

    International Nuclear Information System (INIS)

    Timmons, G.A.

    1989-01-01

    A method is described for producing a molybdenum element having adherently bonded thereto a thermally self-healing plasma-sprayed coating consisting essentially of a composite of molybdenum and a refactory oxide material capable of reacting with molybdenum oxide under oxidizing conditions to form a substantially thermally stable refractory compound of molybdenum, the method comprising plasma-spraying a coating formed by the step-wise application of a plurality of interbonded plasma-sprayed layers of a composite of molybdenum/refractory oxide material produced from a particulate mixture thereof. The coating comprises a first layer of molybdenum plasma-sprayed bonded to the substrate of the molybdenum element, a second layer of plasma-sprayed mixture of particulate molybdenum/refactory oxide consisting essentially of predominantly molybdenum bonded to the first layer, and succeeding layers of this mixture. The next step is heating the coated molybdenum element under oxidizing conditions to an elevated temperature sufficient to cause oxygen to diffuse into the surface of the multi-layered coating to react with dispersed molybdenum therein to form molybdenum oxide and effect healing of the coating by reaction of the molybdenum oxide with the contained refractory oxide and thereby protect the substrate of the molybdenum element against oxidation

  14. Column solid phase extraction and flame atomic absorption spectrometric determination of manganese(II) and iron(III) ions in water, food and biological samples using 3-(1-methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid on synthesized graphene oxide

    International Nuclear Information System (INIS)

    Pourjavid, Mohammad Reza; Sehat, Ali Akbari; Arabieh, Masoud; Yousefi, Seyed Reza; Hosseini, Majid Haji; Rezaee, Mohammad

    2014-01-01

    A modified, selective, highly sensitive and accurate procedure for the determination of trace amounts of manganese and iron ions is established in the presented work. 3-(1-Methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid (MPPC) and graphene oxide (GO) were used in a glass column as chelating reagent and as adsorbent respectively prior to their determination by flame atomic absorption spectrometry. The adsorption mechanism of titled metals complexes on GO was investigated by using computational chemistry approach based on PM6 semi-empirical potential energy surface (PES). The effect of some parameters including pH, flow rate and volume of sample and type, volume and concentration of eluent, as well as the adsorption capacity of matrix ions on the recovery of Mn(II) and Fe(III) was investigated. The limit of detection was 145 and 162 ng L −1 for Mn(II) and Fe(III), respectively. Calibration was linear over the range of 0.31–355 μg L −1 for Mn(II) and 0.34–380 μg L −1 for Fe(III) ions. The method was successfully applied for the determination of understudied ions in water, food and biological samples. - Highlights: • We use synthesized graphene oxide as adsorbent for SPE of Mn(II) and Fe(III) ions. • Adsorption mechanism was investigated by PM6 semi-empirical potential energy surface. • Detection limits were 145 and 162 ng L −1 for Mn and Fe, respectively. • The preconcentration factor was 325 and sample flow rate is 8 mL min −1 . • It was successfully applied to the determination of Mn and Fe ions in real samples

  15. Column solid phase extraction and flame atomic absorption spectrometric determination of manganese(II) and iron(III) ions in water, food and biological samples using 3-(1-methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid on synthesized graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Pourjavid, Mohammad Reza, E-mail: pourjavid@gmail.com [NFCRS, Nuclear Science and Technology Research Institute, P.O. Box 11365-8486, Tehran (Iran, Islamic Republic of); Sehat, Ali Akbari [Department of Analytical Chemistry, Faculty of Chemistry, University College of Science, University of Tehran, P.O. Box 14155-6455, Tehran (Iran, Islamic Republic of); Arabieh, Masoud; Yousefi, Seyed Reza; Hosseini, Majid Haji; Rezaee, Mohammad [NFCRS, Nuclear Science and Technology Research Institute, P.O. Box 11365-8486, Tehran (Iran, Islamic Republic of)

    2014-02-01

    A modified, selective, highly sensitive and accurate procedure for the determination of trace amounts of manganese and iron ions is established in the presented work. 3-(1-Methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid (MPPC) and graphene oxide (GO) were used in a glass column as chelating reagent and as adsorbent respectively prior to their determination by flame atomic absorption spectrometry. The adsorption mechanism of titled metals complexes on GO was investigated by using computational chemistry approach based on PM6 semi-empirical potential energy surface (PES). The effect of some parameters including pH, flow rate and volume of sample and type, volume and concentration of eluent, as well as the adsorption capacity of matrix ions on the recovery of Mn(II) and Fe(III) was investigated. The limit of detection was 145 and 162 ng L{sup −1} for Mn(II) and Fe(III), respectively. Calibration was linear over the range of 0.31–355 μg L{sup −1} for Mn(II) and 0.34–380 μg L{sup −1} for Fe(III) ions. The method was successfully applied for the determination of understudied ions in water, food and biological samples. - Highlights: • We use synthesized graphene oxide as adsorbent for SPE of Mn(II) and Fe(III) ions. • Adsorption mechanism was investigated by PM6 semi-empirical potential energy surface. • Detection limits were 145 and 162 ng L{sup −1} for Mn and Fe, respectively. • The preconcentration factor was 325 and sample flow rate is 8 mL min{sup −1}. • It was successfully applied to the determination of Mn and Fe ions in real samples.

  16. Determination of manganese content in aqueous solutions

    International Nuclear Information System (INIS)

    Reeder, S.D.; Smith, J.R.

    1977-01-01

    The three analytical methods used in the hydrogen-to-manganese cross-section ratio measurement were: volumetric determination of manganese, gravimetric analysis of manganous sulfate; and densimetric determination of manganous sulfate

  17. Manganese activated phosphate glass for dosimetry

    International Nuclear Information System (INIS)

    Regulla, D.

    1975-01-01

    A measuring element comprises a metaphosphate glass doped with manganese as an activator. The manganese activated metaphosphate glass can detect and determine radiation doses in the range between milliroentgens and more than 10 megaroentgens. (auth)

  18. Sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides

    Directory of Open Access Journals (Sweden)

    R.V. Smotraiev

    2016-05-01

    Full Text Available The actual problem of water supply in the world and in Ukraine, in particular, is a high level of pollution in water resources and an insufficient level of drinking water purification. With industrial wastewater, a significant amount of pollutants falls into water bodies, including suspended particles, sulfates, iron compounds, heavy metals, etc. Aim: The aim of this work is to determine the impact of aluminum and manganese ions additives on surface and sorption properties of zirconium oxyhydroxide based sorbents during their production process. Materials and Methods: The sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides were prepared by sol-gel method during the hydrolysis of metal chlorides (zirconium oxychloride ZrOCl2, aluminum chloride AlCl3 and manganese chloride MnCl2 with carbamide. Results: The surface and sorption properties of sorbents based on xerogels of zirconium, aluminum and manganese oxyhydroxides were investigated. X-ray amorphous structure and evolved hydroxyl-hydrate cover mainly characterize the obtained xerogels. The composite sorbents based on xerogels of zirconium oxyhydroxide doped with aluminum oxyhydroxide (aS = 537 m2/g and manganese oxyhydroxide (aS = 356 m2/g have more developed specific surface area than single-component xerogels of zirconium oxyhydroxide (aS = 236 m2/g and aluminum oxyhydroxide (aS = 327 m2/g. The sorbent based on the xerogel of zirconium and manganese oxyhydroxides have the maximum SO42--ions sorption capacity. It absorbs 1.5 times more SO42–-ions than the industrial anion exchanger AN-221. The sorbents based on xerogels of zirconium oxyhydroxide has the sorption capacity of Fe3+-ions that is 1.5…2 times greater than the capacity of the industrial cation exchanger KU-2-8. The Na+-ions absorption capacity is 1.47…1.56 mmol/g for each sorbent. Conclusions: Based on these data it can be concluded that the proposed method is effective for sorbents production based on

  19. Determination of molybdenum by the gravimetric plumbate method (with the molybdenum content from 50 % and above)

    International Nuclear Information System (INIS)

    Stepin, V.V.; Kurbatova, V.I.; Fedorova, N.D.

    1980-01-01

    A gravimetric method of molybdenum determination in ferromolybdenum (Mo content from 50% and higher) after its dissolving in HNO 3 is developed. The method is based on Mo deposition in acetic acid solution in the form of molybdenum oxide lead after separation of Fe and other interfering elements with sodium hydroxide [ru

  20. Determination of molybdenum in natural waters by laser thermal-lens spectrometry

    International Nuclear Information System (INIS)

    Proskurnin, M.A.; Abroskin, A.G.; Artemova, S.I.; Belyaeva, T.V.; Ivanova, E.K.

    1992-01-01

    As before, the determination of nanogram quantities of heavy metals from small sample volumes of natural water represents an acute problem. This task has been solved more or less successfully by the use of different and sufficiently developed physicochemical methods. In most cases the determination requires a 100-fold preconcentration of the component determined (for instance, when using atomic absorption spectrometry). This significant disadvantage can be avoided by the use of thermal-lens laser spectrometry (TLS); some alternatives of the method have already found applications in analytical practice. The objective of the present study has been to investigate the optimum conditions for the determination of molybdenum in natural waters from small sample volumes by TLS. The resulting method based on the reaction with thiocyanate ions in the presence of ascorbic acid, has a detection limit of 19 pg/ml. Masking of iron(III) with a 1000-fold excess of tartrate ions has been proposed and it has been shown that a 10-fold excess of iron does not interfere in the determination of molybdenum. The procedure has been applied to the determination of molybdenum in drinking and natural waters

  1. Rapid analysis of molybdenum contents in molybdenum master alloys by X-ray fluorescence technique

    International Nuclear Information System (INIS)

    Tongkong, P.

    1985-01-01

    Determination of molybdenum contents in molybdenum master alloy had been performed using energy dispersive x-ray fluorescence (EDX) technique where analysis were made via standard additions and calibration curves. Comparison of EDX technique with other analyzing techniques, i.e., wavelength dispersive x-ray fluorescence, neutron activation analysis and inductive coupled plasma spectrometry, showed consistency in the results. This technique was found to yield reliable results when molybdenum contents in master alloys were in the range of 13 to 50 percent using HPGe detector or proportional counter. When the required error was set at 1%, the minimum analyzing time was found to be 30 and 60 seconds for Fe-Mo master alloys with molybdenum content of 13.54 and 49.09 percent respectively. For Al-Mo master alloys, the minimum times required were 120 and 300 seconds with molybdenum content of 15.22 and 47.26 percent respectively

  2. Identification of a cast iron alloy containing nonstrategic elements

    Science.gov (United States)

    Cooper, C. V.; Anton, D. L.; Lemkey, F. D.; Nowotny, H.; Bailey, R. S.; Favrow, L. H.; Smeggil, J. G.; Snow, D. B.

    1989-01-01

    A program was performed to address the mechanical and environmental needs of Stirling engine heater head and regenerator housing components, while reducing the dependence on strategic materials. An alloy was developed which contained no strategic elemental additions per se. The base is iron with additions of manganese, molybdenum, carbon, silicon, niobium, and ferro-chromium. Such an alloy should be producible on a large scale at very low cost. The resulting alloy, designated as NASAUT 4G-Al, contained 15 Mn, 15 Cr, 2 Mo, 1.5 C, 1.0 Si, 1.0 Nb (in weight percent) with a balance of Fe. This alloy was optimized for chemistry, based upon tensile strength, creep-rupture strength, fracture behavior, and fatigue resistance up to 800 C. Alloys were also tested for environmental compatibility. The microstructure and mechanic properties (including hardness) were assessed in the as-cast condition and following several heat treatments, including one designed to simulate a required braze cycle. The alloy was fabricated and characterized in the form of both equiaxed and columnar-grained castings. The columnar grains were produced by directional solidification, and the properties were characterized in both the longitudinal and transverse orientations. The NASAUT 4G-Al alloy was found to be good in cyclic-oxidation resistance and excellent in both hydrogen and hot-corrosion resistance, especially in comparison to the baseline XF-818 alloy. The mechanical properties of yield strength, stress-rupture life, high-cycle-fatigue resistance, and low-cycle-fatigue resistance were good to excellent in comparison to the current alloy for this application, HS-31 (X-40), with precise results depending in a complex manner on grain orientation and temperature. If required, the ductility could be improved by lowering the carbon content.

  3. 21 CFR 184.1446 - Manganese chloride.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Manganese chloride. 184.1446 Section 184.1446 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Specific Substances Affirmed as GRAS § 184.1446 Manganese chloride. (a) Manganese chloride (MnCl2·4H2O, CAS...

  4. 21 CFR 582.5446 - Manganese chloride.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Manganese chloride. 582.5446 Section 582.5446 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use. This...

  5. Trigo duro: tolerância à toxicidade de alumínio, manganês e ferro em soluções nutritivas Durum wheat: tolerance to aluminum, manganese and iron toxicities in nutrient solutions

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo de Oliveira Camargo

    1995-01-01

    exhibited root growth in the presence of 1 mg/L of Al3+, and all evaluated durum wheat inbred lines were sensitive to 0.4 mg/L of Al3+, showing an irreversible root growth. As the Mn2+ and Fe2+ concentrations were increasead into the solutions, the root length of all studied genotypes presented a significant reduction. The durum wheat inbred lines 1 (Avetoro "S" x Anhinga "S" - Purcell "S"/ D.67.2, 2 (Cando - Yavaros "S", 6 (Chen "S" e 8 (Carcomum "S" showed high level of tolerance to manganese toxicity in relation to 'Siete Cerros' and the durum wheat inbred lines 1, 6, 12 (CI 14955 x Yavaros "S"- Gediz"S"/Tropic Bird, 16 and 21 (Swan 'S" and 20 (Boyeros "S"/Cocorit-71/5/Crane/Ganso//Marte"S"/3/TiIdillo"S"/4/Memo "S" exhibited tolerance to the presence of high levels of Fe2+ into the nutrient solutions.

  6. Multitracer method of diffusion measurement in chromium-manganese steels

    International Nuclear Information System (INIS)

    Dudala, J.; Stegowski, Z.; Gilewicz-Wolter, J.

    2004-01-01

    The paper presents an application of multitracer method to diffusion measurement in Cr-Mn steels. Radioisotope tracers of chromium 51 Cr, manganese 54 Mn and iron 59 Fe were used simultaneously in the diffusion process, Gamma-spectrum measurement and the proper analysis enabled evaluation of concentration distribution for each tracer. As a new tool, artificial neural networks (ANN) method was used for spectrum analysis. The proper solution of the diffusion model was applied to the experimental tracers' distribution data and diffusion coefficients were determined. (author)

  7. Molybdenum reduction to molybdenum blue in Serratia sp. Strain DRY5 is catalyzed by a novel molybdenum-reducing enzyme.

    Science.gov (United States)

    Shukor, M Y; Halmi, M I E; Rahman, M F A; Shamaan, N A; Syed, M A

    2014-01-01

    The first purification of the Mo-reducing enzyme from Serratia sp. strain DRY5 that is responsible for molybdenum reduction to molybdenum blue in the bacterium is reported. The monomeric enzyme has an apparent molecular weight of 105 kDalton. The isoelectric point of this enzyme was 7.55. The enzyme has an optimum pH of 6.0 and maximum activity between 25 and 35°C. The Mo-reducing enzyme was extremely sensitive to temperatures above 50°C (between 54 and 70°C). A plot of initial rates against substrate concentrations at 15 mM 12-MP registered a V max for NADH at 12.0 nmole Mo blue/min/mg protein. The apparent K m for NADH was 0.79 mM. At 5 mM NADH, the apparent V max and apparent K m values for 12-MP of 12.05 nmole/min/mg protein and 3.87 mM, respectively, were obtained. The catalytic efficiency (k cat/K m ) of the Mo-reducing enzyme was 5.47 M(-1) s(-1). The purification of this enzyme could probably help to solve the phenomenon of molybdenum reduction to molybdenum blue first reported in 1896 and would be useful for the understanding of the underlying mechanism in molybdenum bioremediation involving bioreduction.

  8. Molybdenum Reduction to Molybdenum Blue in Serratia sp. Strain DRY5 Is Catalyzed by a Novel Molybdenum-Reducing Enzyme

    Directory of Open Access Journals (Sweden)

    M. Y. Shukor

    2014-01-01

    Full Text Available The first purification of the Mo-reducing enzyme from Serratia sp. strain DRY5 that is responsible for molybdenum reduction to molybdenum blue in the bacterium is reported. The monomeric enzyme has an apparent molecular weight of 105 kDalton. The isoelectric point of this enzyme was 7.55. The enzyme has an optimum pH of 6.0 and maximum activity between 25 and 35°C. The Mo-reducing enzyme was extremely sensitive to temperatures above 50°C (between 54 and 70°C. A plot of initial rates against substrate concentrations at 15 mM 12-MP registered a Vmax for NADH at 12.0 nmole Mo blue/min/mg protein. The apparent Km for NADH was 0.79 mM. At 5 mM NADH, the apparent Vmax and apparent Km values for 12-MP of 12.05 nmole/min/mg protein and 3.87 mM, respectively, were obtained. The catalytic efficiency (kcat/Km of the Mo-reducing enzyme was 5.47 M-1 s-1. The purification of this enzyme could probably help to solve the phenomenon of molybdenum reduction to molybdenum blue first reported in 1896 and would be useful for the understanding of the underlying mechanism in molybdenum bioremediation involving bioreduction.

  9. Economic value of Valentines iron minerals; Valor economico de los minerales de hierro de Valentines

    Energy Technology Data Exchange (ETDEWEB)

    Alvarado, B.

    1960-07-01

    This work is a investigation required by the government of Uruguay about the economic value of iron and manganese deposits in Valentines ferriferrous zone. The purpose is to study the potential commercial for the exportation.

  10. Nitrogenase activity of Herbaspirillum seropedicae grown under low iron levels requires the products of nifXorf1 genes.

    Science.gov (United States)

    Klassen, Giseli; de Oliveira Pedrosa, Fábio; de Souza, Emanuel M; Yates, M Geoffrey; Rigo, Liu Un

    2003-07-29

    Herbaspirillum seropedicae strains mutated in the nifX or orf1 genes showed 90% or 50% reduction in nitrogenase activity under low levels of iron or molybdenum respectively. Mutations in nifX or orf1 genes did not affect nif gene expression since a nifH::lacZ fusion was fully active in both mutants. nifX and the contiguous gene orf1 are essential for maximum nitrogen fixation under iron limitation and are probably involved in synthesis of nitrogenase iron or iron-molybdenum clusters.

  11. Preparation of selective molybdenum concentrate from collective coppermolybdenum concentrate

    Directory of Open Access Journals (Sweden)

    N. Tusupbaev

    2016-06-01

    Full Text Available The paper considers possibilities of selective separation of the concentrate of copper and molybdenum from a collective copper-molybdenum concentrate of Aktogay deposit using regrinding and conventional flotation reagents. In the case of conventional flotoreagents, the content of molybdenum in a molybdenum concentrate was 8.0% at extraction effectiveness 83.12%. At 27.96% extraction degree of copper, it’s content in the concentrate equaled to 21.3%. After regrinding, molybdenum content in the concentrate was 24.0% at the extraction effectiveness 59.63%, and copper content in the concentrate was 21.9% at the recovery of 61.23%. Thus, the regrinding of a collective copper-molybdenum concentrate resulted in an increase in the content of molybdenum in molybdenum concentrate by 16%, and the copper concentration increased by 0.6%.

  12. Dietary manganese in the Glasgow area

    International Nuclear Information System (INIS)

    Cross, J.D.; Dale, I.M.; Raie, R.M.

    1979-01-01

    The manganese content of the diet and human tissue (adult and infant) in the Glasgow area is established. The total manganese intake by a breast fed infant (6 μg/day) is very much lower than that of an adult (5 mg/day). This does not appear to cause any upset in the infant's metabolism and the tissue levels of both groups are similar. This indicates that the human system can obtain its required manganese from both levels of intake. Tea is the major source of manganese in the diet: tobacco, which is rich in manganese, does not contribute a significant amount when smoked. (author)

  13. Noncollinear magnetism in manganese nanostructures

    Czech Academy of Sciences Publication Activity Database

    Zelený, Martin; Šob, Mojmír; Hafner, J.

    2009-01-01

    Roč. 80, č. 14 (2009), 144414/1-144414/19 ISSN 1098-0121 R&D Projects: GA AV ČR IAA100100920; GA MŠk OC09011 Institutional research plan: CEZ:AV0Z20410507 Keywords : magnetism of nanostructures * nanowires * noncollinear magnetism * manganese Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  14. Bibliographic study on molybdenum biokinetics. Literaturstudie zur Biokinetik von Molybdaen

    Energy Technology Data Exchange (ETDEWEB)

    Erzberger, A.

    1988-05-01

    This bibliographical study compiles and analyzes findings about the metabolism and resorption of molybdenum. Besides including studies on the physiology of molybdenum 99, a general survey is given on molybdenum in the environment and on its physiological behaviour. In particular, information on the dependence of molybdenum resorption on various factors, such as the chemical form, antagonisms etc., are gathered from literature. These factors have to be considered for sensibly carrying out necessary experiments.

  15. The XUV spectra of highly ionised molybdenum

    International Nuclear Information System (INIS)

    Mansfield, M.W.D.; Peacock, N.J.; Smith, C.C.; Hobby, M.G.; Cowan, R.D.

    1978-01-01

    The spectra of molybdenum ions produced in Tokamaks in the wavelength range 10-200 A have been reproduced in a plasma formed by laser beam irradiation of solid molybdenum targets. Lines from highly ionised stages of molybdenum (Mo XXX to Mo XXXII) have been distinguished by varying the laser beam intensity. Detailed analyses of the simpler ions, Mo XV (Ni-like), Mo XVI (Co-like), Mo XXXII (Na-like), and to a lesser extent Mo XXXI (Mg-like) and Mo XVII (Fe-like), have been achieved by comparison with ab initio calculations. A general interpretation of intermediate ion stages is also given but it is shown that most of these spectra are so complex, as a result of inner-subshell excitation, that detailed term-scheme analyses are nearly impossible. (author)

  16. XUV spectra of highly ionised molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Mansfield, M W.D.; Peacock, N J; Smith, C C; Hobby, M G [UKAEA, Abingdon. Culham Lab.; Cowan, R D

    1978-05-14

    The spectra of molybdenum ions produced in Tokamaks in the wavelength range 10-200 A have been reproduced in a plasma formed by laser beam irradiation of solid molybdenum targets. Lines from highly ionised stages of molybdenum (Mo XXX to Mo XXXII) have been distinguished by varying the laser beam intensity. Detailed analyses of the simpler ions, Mo XV (Ni-like), Mo XVI (Co-like), Mo XXXII (Na-like), and to a lesser extent Mo XXXI (Mg-like) and Mo XVII (Fe-like), have been achieved by comparison with ab initio calculations. A general interpretation of intermediate ion stages is also given but it is shown that most of these spectra are so complex, as a result of inner-subshell excitation, that detailed term-scheme analyses are nearly impossible.

  17. Molybdenum peroxo complex. Structure and thermal behavior

    Energy Technology Data Exchange (ETDEWEB)

    Segawa, Koichi; Ooga, Katsumi; Kurusu, Yasuhiko

    1984-10-01

    The molybdenum peroxide (Mo-y) prepared by oxidation of molybdenum metal with hydrogen peroxide has been studied to determine its structure and thermal behavior. Temperature programmed decomposition has been used to study the thermal stability of Mo-y. Two distinct peaks, I and II, of decomposition processes are discernible in Mo-y. Peak I corresponds to the elimination of water of crystallization and peak II to the decomposition of a peroxide ion of Mo-y. IR and UV examinations support the results of the thermal analysis. The IR band at 931 cm/sup -1/ and the UV band at 381 nm show the same thermal behavior. Both bands are attributable to the peroxide ion of Mo-y. Spectroscopic studies show that Mo-y has the tetrahedral coordination derived from the single molybdenum complex, which has double bond oxygens attached to Mo atom and has a symmetric type of peroxide ion with one water of crystallization.

  18. Separation and selective determination of molybdenum with sodiumthiosulfate and ethylacetate

    International Nuclear Information System (INIS)

    Hainberger, L.; de Oliveira Andrade, W.

    1982-01-01

    A sensitive and selective method of spectrophotometric determination of molybdenum is described. Molybdenum is extracted to more than 97%. Lambert-Beer's law is obeyed between 0.35 and 30μg/10ml of the used aqueous solution. 43 ions concerning their interference are studied. The method was used to determine the content of molybdenum in black beans. (Author)

  19. Assessment of polyphase sintered iron-cobalt-iron boride cermets

    International Nuclear Information System (INIS)

    Nowacki, J.; Pieczonka, T.

    2004-01-01

    Sintering of iron, cobalt and boron powders has been analysed. As a result iron-iron boride, Fe-Fe 2 B and iron/cobalt boride with a slight admixture of molybdenum, Fe - Co - (FeMoCo) 2 B cermets have been produced. Iron was introduced to the mixture as the Astalloy Mo Hoeganaes grade powder. Elemental amorphous boron powder was used, and formation of borides occurred both during heating and isothermal sintering periods causing dimensional changes of the sintered body. Dilatometry was chosen to control basic phenomena taking place during multiphase sintering of investigated systems. The microstructure and phase constituents of sintered compacts were controlled as well. The cermets produced were substituted to: metallographic tests, X-ray analysis, measurements of hardness and of microhardness, and of wear in the process of sliding dry friction. Cermets are made up of two phases; hard grains of iron - cobalt boride, (FeCo) 2 B (1800 HV) constituting the reinforcement and a relatively soft and plastic eutectic mixture Fe 2 B - Co (400-500 HV) constituting the matrix. (author)

  20. Recovery of uranium and molybdenum from a carbonate type uranium-molybdenum ore

    International Nuclear Information System (INIS)

    Zhou Genmao; Zeng Yijun; Tang Baobin; Meng Shu; Xu Guolong

    2014-01-01

    Based on the results of process mineralogical research of a carbonate type uranium-molybdenum ore, leaching behaviors of the uranium-molybdenum ore were studied by alkali agitation leaching, conventional alkali column leaching and alkali curing column leaching processes. The results showed that using the alkali curing column leaching process, the leaching rate of molybdenum increased to more than 90%, and the leaching rate of uranium was about 85%, Compared with the conventional alkali column leaching process, the leaching time of the alkali curing column leaching process decreased by 60 days. (authors)

  1. Spectrographic analysis of uranium-molybdenum alloys

    International Nuclear Information System (INIS)

    Roca, M.

    1967-01-01

    A spectrographic method of analysis has been developed for uranium-molybdenum alloys containing up to 10 % Mo. The carrier distillation technique, with gallium oxide and graphite as carriers, is used for the semiquantitative determination of Al, Cr, Fe, Ni and Si, involving the conversion of the samples into oxides. As a consequence of the study of the influence of the molybdenum on the line intensities, it is useful to prepare only one set of standards with 0,6 % MoO 3 . Total burning excitation is used for calcium, employing two sets of standards with 0,6 and 7.5 MoO 3 . (Author) 5 refs

  2. Crystallization of nodular cast iron with carbides

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-12-01

    Full Text Available In this paper a crystallization process of nodular cast iron with carbides having a different chemical composition have been presented. It have been found, that an increase of molybdenum above 0,30% causes the ledeburutic carbides crystallization after (γ+ graphite eutectic phase crystallization. When Mo content is lower, these carbides crystallize as a pre-eutectic phase. In this article causes of this effect have been given.

  3. Nucleation of microwave plasma CVD diamond on molybdenum (Mo) substrate

    International Nuclear Information System (INIS)

    Inderjeet, K.; Ramesh, S.

    2000-01-01

    Molybdenum is a metal, which is gaining increasing significance in industrial applications. The main use of Mo is as all alloying element added in small amounts to steel, irons and non- ferrous alloys in order to enhance the strength, toughness and wear resistance. Mo is also vastly being employed in the automotive and aircraft industries, mainly due to its low coefficient of friction. Diamond, on be other hand, is a unique material for innumerable applications because of its usual combination of physical and chemical properties. Several potential applications can be anticipated for diamond in many sectors including electronics, optics, as protective corrosion resistant coatings, cutting tools, etc. With the enhancement in science and technology, diamond microcrystals and thin films are now being produced from the vapour phase by a variety of chemical vapour deposition (CVD) techniques; such as microwave plasma CVD. With such technology being made available, it is envisage that diamond-coated molybdenum would further enhance the performance and to open up new avenue for Mo in various industries. Therefore, it is the aim of the present work to study the nucleation and growth of diamond particles on Mo surface by employing microwave plasma CVD (MAPCVD). In the present work, diamond deposition was carried out in several stages by varying the deposition distance. The nucleation and growth rate were studied using scanning electron microscopy (SEM). In addition, the existence of diamond was verified by X-ray diffraction (XRD) analysis. It has been found that the nucleation and growth rate of diamond particles were influenced by the deposition height between the substrate and plasma. Under the optimum condition, well defined diamond crystallites distributed homogeneously throughout the surface, could be obtained. Some of the important parameters controlling the deposition and growth of diamond particles on Mo surface are discussed. (author)

  4. Response of the marine diatom Thalassiosira weissflogii to iron stress

    International Nuclear Information System (INIS)

    Harrison, G.I.; Morel, F.M.M.

    1986-01-01

    The coastal diatom Thalassiosira weissflogii responds to iron limitation with decreasing growth rate, decreasing quotas of cellular iron, and increasing rates of maximum short term uptake. Growth response to steady iron limitation can be modeled according to the equations of Droop and Monod. The cellular iron quota varies from about 2 to 25 x 10 -1 mol iron per liter-cell with increasing iron; the half-saturation constant for growth, Kμ, is 1.1 x 10 -21 M (free ferric ion). In contrast, the half-saturation constant for 59 I iron uptake, K/sub rho/ is about 3 x 10 -19 M; the maximum iron uptake rate (rho/sub max/) is increased several-fold under iron limitation, resulting in a potential short term uptake rate that is a few hundred times the steady state rate. At a fixed concentration of free manganese ion, the cellular manganese quota is increased several-fold in iron-limited cultures compared to iron-sufficient cultures

  5. Process for separation of tungsten and molybdenum by extraction

    International Nuclear Information System (INIS)

    Zelikman, A.N.; Voldman, G.M.; Rumyantsev, V.K.; Ziberov, G.N.; Kagermanian, V.S.

    1976-01-01

    A process for the separation of tungsten and molybdenum by extraction involves the addition of HCl or HNO 3 to an aqueous solution containing tungsten and molybdenum to obtain a pH from 0.5 to 4.3, and introduction of a stabilizer comprising water-soluble phosphorus salts and a complexing agent, hydrogen peroxide, in an amount from 1.5 to 2 mole per 1 g-atom of the total content of tungsten and molybdenum. Then molybdenum is selectively extracted from the resulting aqueous solution with tri-n-butylphosphate with equal volumetric proportioning of the aqueous and organic solutions. Re-extraction of molybdenum and partially tungsten is carried out from the organic extracting agent with an alkali or soda solution. The process makes possible the preparation of tungsten solution containing no more than 0.001 g/l of molybdenum, and an increase in the degree of extraction of tungsten and molybdenum

  6. Recent situation and future of molybdenum mineral resources; Molybdenum shigen no genjo to shorai

    Energy Technology Data Exchange (ETDEWEB)

    Ono, K.; Nishiyama, T. [Kyoto University, Kyoto (Japan)

    1997-05-05

    Molybdenum is produced mainly from molybdenite, and the majority of this ore is exploited from the porphyry deposit. The reserve is estimated at 5.5-million ton. A total of 118-thousand ton was produced across the world in 1995, in the U.S., China, Chile, and Canada, the countries named in the order of quantities they exploited. Molybdenite is first refined by flotation for the production of a sulphide. It is subjected to oxidizing roasting for conversion into crude molybdenum trioxide, which is next subjected to extraction in warmed-up aqueous ammonia and then to evaporation for the crystallization of ammonium paramolybdate. The crystals are baked for conversion into molybdenum trioxide of the ordinary purity, to be further processed into ferromolybdenum, molybdenum compounds, molybdenum powder, etc. In view of the magnitude of demand, the metal is used mostly for the manufacture of special steels and special alloys. The demand for this metal, though small in size, involves important articles, such as line materials for semiconductors in the power industry, catalysts in the chemical industry, and lubricants. Japan`s stockpile includes molybdenum, but the U.S. has been stockpiling none since 1977. 9 refs., 4 figs., 1 tab.

  7. Paraelasticity in electron-irradiated molybdenum

    International Nuclear Information System (INIS)

    Beuneu, Brigitte; Quere, Yves.

    1981-11-01

    The relaxation of a radiation-induced point defect-most probably the rotation of a dumbell-is observed during isothermal anneals of irradiated molybdenum by resistivity measurements. The recovery of close pairs is not affected, in first analysis, by the presence of a uniaxial stress

  8. Exploring atomic defects in molybdenum disulphide monolayers

    KAUST Repository

    Hong, Jinhua; Hu, Zhixin; Probert, Matt; Li, Kun; Lv, Danhui; Yang, Xinan; Gu, Lin; Mao, Nannan; Feng, Qingliang; Xie, Liming; Zhang, Jin; Wu, Dianzhong; Zhang, Zhiyong; Jin, Chuanhong; Ji, Wei; Zhang, Xixiang; Yuan, Jun; Zhang, Ze

    2015-01-01

    Defects usually play an important role in tailoring various properties of two-dimensional materials. Defects in two-dimensional monolayer molybdenum disulphide may be responsible for large variation of electric and optical properties. Here we present a comprehensive joint experiment-theory investigation of point defects in monolayer molybdenum disulphide prepared by mechanical exfoliation, physical and chemical vapour deposition. Defect species are systematically identified and their concentrations determined by aberration-corrected scanning transmission electron microscopy, and also studied by ab-initio calculation. Defect density up to 3.5 × 10 13 cm '2 is found and the dominant category of defects changes from sulphur vacancy in mechanical exfoliation and chemical vapour deposition samples to molybdenum antisite in physical vapour deposition samples. Influence of defects on electronic structure and charge-carrier mobility are predicted by calculation and observed by electric transport measurement. In light of these results, the growth of ultra-high-quality monolayer molybdenum disulphide appears a primary task for the community pursuing high-performance electronic devices.

  9. Exploring atomic defects in molybdenum disulphide monolayers

    KAUST Repository

    Hong, Jinhua

    2015-02-19

    Defects usually play an important role in tailoring various properties of two-dimensional materials. Defects in two-dimensional monolayer molybdenum disulphide may be responsible for large variation of electric and optical properties. Here we present a comprehensive joint experiment-theory investigation of point defects in monolayer molybdenum disulphide prepared by mechanical exfoliation, physical and chemical vapour deposition. Defect species are systematically identified and their concentrations determined by aberration-corrected scanning transmission electron microscopy, and also studied by ab-initio calculation. Defect density up to 3.5 × 10 13 cm \\'2 is found and the dominant category of defects changes from sulphur vacancy in mechanical exfoliation and chemical vapour deposition samples to molybdenum antisite in physical vapour deposition samples. Influence of defects on electronic structure and charge-carrier mobility are predicted by calculation and observed by electric transport measurement. In light of these results, the growth of ultra-high-quality monolayer molybdenum disulphide appears a primary task for the community pursuing high-performance electronic devices.

  10. Reaction of boron carbide with molybdenum disilicide

    International Nuclear Information System (INIS)

    Novikov, A.V.; Melekhin, V.F.; Pegov, V.S.

    1989-01-01

    The investigation results of interaction in the B 4 C-MoSi 2 system during sintering in vacuum are presented. Sintering of boron carbide with molybdenum disilicide is shown to lead to the formation of MoB 2 , SiC, Mo 5 Si 3 compounds, the presence of carbon-containing covering plays an important role in sintering

  11. Molybdenum silicide based materials and their properties

    International Nuclear Information System (INIS)

    Yao, Z.; Stiglich, J.; Sudarshan, T.S.

    1999-01-01

    Molybdenum disilicide (MoSi 2 ) is a promising candidate material for high temperature structural applications. It is a high melting point (2030 C) material with excellent oxidation resistance and a moderate density (6.24 g/cm 3 ). However, low toughness at low temperatures and high creep rates at elevated temperatures have hindered its commercialization in structural applications. Much effort has been invested in MoSi 2 composites as alternatives to pure molybdenum disilicide for oxidizing and aggressive environments. Molybdenum disilicide-based heating elements have been used extensively in high-temperature furnaces. The low electrical resistance of silicides in combination with high thermal stability, electron-migration resistance, and excellent diffusion-barrier characteristics is important for microelectronic applications. Projected applications of MoSi 2 -based materials include turbine airfoils, combustion chamber components in oxidizing environments, missile nozzles, molten metal lances, industrial gas burners, diesel engine glow plugs, and materials for glass processing. On this paper, synthesis, fabrication, and properties of the monolithic and composite molybdenum silicides are reviewed

  12. Carbon, chromium and molybdenum contents; Teores de carbono, cromo e molibdenio

    Energy Technology Data Exchange (ETDEWEB)

    Sinatora, A; Goldenstein, H; Mei, P R; Albertin, E; Fuoco, R; Mariotto, C L

    1993-12-31

    This work describes solidification experiments on white cast iron, with 15 and 20% of chromium, 2.3, 3.0 and 3.6 % of carbon and 0.0, 1.5 and 2.5 % of molybdenum in test de samples with 30 mm diameter. Measurements were performed on the austenite and eutectic formation arrests, the number of the eutectic carbide particles relative to the total and the eutectic volumes, and the volume fraction of the primary austenite 9 figs., 3 tabs.

  13. Carbon, chromium and molybdenum contents; Teores de carbono, cromo e molibdenio

    Energy Technology Data Exchange (ETDEWEB)

    Sinatora, A; Goldenstein, H.; Mei, P.R.; Albertin, E.; Fuoco, R.; Mariotto, C.L

    1992-12-31

    This work describes solidification experiments on white cast iron, with 15 and 20% of chromium, 2.3, 3.0 and 3.6 % of carbon and 0.0, 1.5 and 2.5 % of molybdenum in test de samples with 30 mm diameter. Measurements were performed on the austenite and eutectic formation arrests, the number of the eutectic carbide particles relative to the total and the eutectic volumes, and the volume fraction of the primary austenite 9 figs., 3 tabs.

  14. The Development of Molybdenum Speciation as a Paleoredox Tool

    Science.gov (United States)

    Rodley, J.; Peacock, C.; Mosselmans, J. F. W.; Poulton, S.

    2017-12-01

    The redox state of the oceans has changed throughout geological time and an understanding of these changes is essential to elucidate links between ocean chemistry, climate and life. Due to its abundance in seawater and redox-sensitive nature, molybdenum has enormous potential as a paleoredox proxy. Although a significant amount of research has been done on molybdenum in ancient and modern sediments in terms of its concentrations and isotopic ratios there remains a limited understanding of the drawdown mechanisms of molybdenum under different redox conditions restricting its use in identifying a range of redox states. In order to address these uncertainties, we have developed a novel sequential extraction technique to examine molybdenum concentrations in six sediment fractions from modern samples that represent oxic, nitrogenous, ferruginous and euxinic environments. In addition we use µ-XRF and µ-XANES synchrotron spectroscopy to examine the molybdenum speciation within these fractions and environments. To interpret our µ-XANES data we have developed an extensive library of molybdenum XANES standards that represent molybdenum sequestration by the sediment fractions identified from the sequential extraction. To further verify our synchrotron results we developed a series of µ-XANES micro-column experiments to examine preferential uptake pathways of molybdenum to different sediment phases under a euxinic water column. The initial data from both the sequential extraction and µ-XANES methods indicate that molybdenum is not limited to a single burial pathway in any of the redox environments. We find that each of the redox environments can be characterised by a limited set of molybdenum phase associations, with molybdenum adsorption to pyrite likely the dominant burial pathway. These findings agree with existing research for molybdenum speciation in euxinic environments suggesting that both pyrite and sulphidised organic matter act as important molybdenum sinks. Our

  15. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    Science.gov (United States)

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  16. Oxidative Precipitation of Manganese from Acid Mine Drainage by Potassium Permanganate

    Directory of Open Access Journals (Sweden)

    Regeane M. Freitas

    2013-01-01

    Full Text Available Although oxidative precipitation by potassium permanganate is a widely recognised process for manganese removal, research dealing with highly contaminated acid mine drainage (AMD has yet to be performed. The present study investigated the efficiency of KMnO4 in removing manganese from AMD effluents. Samples of AMD that originated from inactive uranium mine in Brazil were chemically characterised and treated by KMnO4 at pH 3.0, 5.0, and 7.0. Analyses by Raman spectroscopy and geochemical modelling using PHREEQC code were employed to assess solid phases. Results indicated that the manganese was rapidly oxidised by KMnO4 in a process enhanced at higher pH. The greatest removal, that is, 99%, occurred at pH 7.0, when treated waters presented manganese levels as low as 1.0 mg/L, the limit established by the Brazilian legislation. Birnessite (MnO2, hausmannite (Mn3O4, and manganite (MnOOH were detected by Raman spectroscopy. These phases were consistently identified by the geochemical model, which also predicted phases containing iron, uranium, manganese, and aluminium during the correction of the pH as well as bixbyite (Mn2O3, nsutite (MnO2, pyrolusite (MnO2, and fluorite (CaF2 following the KMnO4 addition.

  17. Use of hydrous titanium dioxide as potential sorbent for the removal of manganese from water

    Directory of Open Access Journals (Sweden)

    Ramakrishnan Kamaraj

    2014-12-01

    Full Text Available This research article deals with an electrosynthesis of hydrous titanium dioxide by anodic dissolution of titanium sacrificial anodes and their application for the adsorption of manganese from aqueous solution. Titanium sheet was used as the sacrificial anode and galvanized iron sheet was used as the cathode. The optimization of different experimental parameters like initial ion concentration, current density, pH, temperature, etc., on the removal efficiency of manganese was carried out. The maximum removal efficiency of 97.55 % was achieved at a current density of 0.08 A dm-2 and pH of 7.0. The Langmuir, Freundlich and Redlich Peterson isotherm models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The adsorption of manganese preferably followed the Langmuir adsorption isotherm. The adsorption kinetics was modelled by first- and second- order rate models and the adsorption kinetic studies showed that the adsorption of manganese was best described using the second-order kinetic model. Thermodynamic parameters indicate that the adsorption of manganese on hydrous titanium dioxide was feasible, spontaneous and exothermic.

  18. Finite Element Analysis and Optimization for the Multi-stage Deep Drawing of Molybdenum Sheet

    International Nuclear Information System (INIS)

    Kim, Heung-Kyu; Hong, Seok Kwan; Kang, Jeong Jin; Heo, Young-moo; Lee, Jong-Kil; Jeon, Byung-Hee

    2005-01-01

    Molybdenum, a bcc refractory metal with a melting point of about 2600 deg. C, has a high heat and electrical conductivity. In addition, it remains strong mechanically at high temperatures as well as at low temperatures. Therefore it is a technologically very important material for the applications operating at high temperatures. However, a multi-stage process is required due to the low drawability for making a deep drawn part from the molybdenum sheet. In this study, a multi-stage deep drawing process for a molybdenum circular cup was designed by combining the drawing with the ironing, which was effective for the low drawability materials. A parametric study by FE analysis for the multi-stage deep drawing was conducted for evaluation of the design variables effect. Based on the FE analysis result, the multi-stage deep drawing process was parameterized by the design variables, and an optimum process design was obtained by the process optimization based on the FE simulation at each stage

  19. Manganese and iron as oxygen carriers to anoxie estuarine sediment

    Science.gov (United States)

    Brayner, F. M. M.; Matvienko, B.

    2003-05-01

    We studied the concentration of a series of transition metals including Mn and Fe in an estuarine fishpond. The pond is situated at latitude 8°10'S and longitude 34°55'W, in the Capibaribe River estuary, within the Recife city boundaries, which is located in Pernambuco, a state of the Brazilian Northeast Pond area is 1.5 ha and it bas a 0.5 m depth. It is separated from the river by dikes. Water temperature at 28° C is stable throughout the year. Light breezes keep the water aerated, but intense ongoing decomposition makes the sediment anoxie. The area, originally of mangrove type, has been changed by antropic action on its fauna and vegetation. The study focuses on changes in behaviour of heavy metals. Samples of bottom sediments wore collected by Eckman dredge sediment sampler and total metal concentration was determined by the lithium borate fusion method. Water, recent sediment, and consolidated sediment were examined in this fishpond where Mn and Fe are brought in periodically by water and then gradually go into the sediment at respective rates of 10.52 and 1332 mg m^{-2}a^{-1}. Strong bioturbation re-suspends sediment while simultaneously re-dissolution of these ions is going on fhrough reduction in the anoxie sédiment. As soluble species these ions migrate from sediment to water and are there continually oxidized by dissolved oxygen, becoming insoluble. With their precipitation, chemically bound oxygen is carried down to the sediment, constituting a parallel channel of transport in addition to migration into the sediment bydiffusion of the oxygen dissolved in the water. The estimated flow rates are 3.25 and 76 mg O2 m^{-2}a^{-1} due to Mn and Fe respectively. The rates were established using natural silicon as a tracer.

  20. Anaerobic manganese- or iron-mediated pharmaceutical degradation in water

    NARCIS (Netherlands)

    Liu, Wenbo

    2018-01-01

    Pharmaceutical compounds, originating mainly from industrial production and public consumption, are detected at extremely low levels (ng·L-1 –µg·L-1) in groundwater, surface water, and wastewater. So far, the adverse effects of pharmaceuticals and their intermediates have been widely reported,

  1. Iron, zinc, and manganese distribution in mature soybean seeds

    DEFF Research Database (Denmark)

    Cvitanich, Cristina; Przybyłowicz, Wojciech J; Mesjasz-Przybyłowicz, Jolanta

    2009-01-01

    Micronutrient deficiencies have a negative impact in the lives of millions of people worldwide. Most affected are children and pregnant women in developing regions. Biofortification is a sustainable way to alleviate micronutrient deficiencies in at-risk populations. To optimize the biofortificati...

  2. Molybdenum distribution and sensitivity in tomatoes, sunflowers and beans

    Energy Technology Data Exchange (ETDEWEB)

    Hecht-Buchholz, C

    1973-01-01

    The influence of increasing levels of molybdenum on the growth, molybdenum uptake and distribution in individual plant organs was investigated in tomatoes, beans and sunflowers in a 9 day trial. With tomatoes, which showed marked damage with high molybdenum levels, the molybdenum content of dry matter was highest in the leaf and lowest in the stem. On the other hand, beans, insensitive towards the high molybdenum level, dry matter molybdenum content was appreciably higher in the stem than in the leaf. It is supposed that in plant species, insensitive to high molybdenum levels, molybdenum is held less firmly in this tissue and can attain damaging levels in the cytoplasm of the youngest leaf tissue cells. It is supposed, on the basis of the reactions which were carried out with expressed root juice and on the basis of the yellow coloration attainable in vitro in the tissue caused by the addition of molybdate solution, that the yellow coloration appearing in the cells and plant organs of various plant species, here tomatoes and sunflowers, with high molybdenum levels is due to a reaction between molybdenum and polyvalent phenols in cellsap.

  3. Iron persistence in a distal hydrothermal plume supported by dissolved-particulate exchange

    Science.gov (United States)

    Fitzsimmons, Jessica N.; John, Seth G.; Marsay, Christopher M.; Hoffman, Colleen L.; Nicholas, Sarah L.; Toner, Brandy M.; German, Christopher R.; Sherrell, Robert M.

    2017-02-01

    Hydrothermally sourced dissolved metals have been recorded in all ocean basins. In the oceans' largest known hydrothermal plume, extending westwards across the Pacific from the Southern East Pacific Rise, dissolved iron and manganese were shown by the GEOTRACES program to be transported halfway across the Pacific. Here, we report that particulate iron and manganese in the same plume also exceed background concentrations, even 4,000 km from the vent source. Both dissolved and particulate iron deepen by more than 350 m relative to 3He--a non-reactive tracer of hydrothermal input--crossing isopycnals. Manganese shows no similar descent. Individual plume particle analyses indicate that particulate iron occurs within low-density organic matrices, consistent with its slow sinking rate of 5-10 m yr-1. Chemical speciation and isotopic composition analyses reveal that particulate iron consists of Fe(III) oxyhydroxides, whereas dissolved iron consists of nanoparticulate Fe(III) oxyhydroxides and an organically complexed iron phase. The descent of plume-dissolved iron is best explained by reversible exchange onto slowly sinking particles, probably mediated by organic compounds binding iron. We suggest that in ocean regimes with high particulate iron loadings, dissolved iron fluxes may depend on the balance between stabilization in the dissolved phase and the reversibility of exchange onto sinking particles.

  4. Kinetics of molybdenum reduction to molybdenum blue by Bacillus sp. strain A.rzi.

    Science.gov (United States)

    Othman, A R; Bakar, N A; Halmi, M I E; Johari, W L W; Ahmad, S A; Jirangon, H; Syed, M A; Shukor, M Y

    2013-01-01

    Molybdenum is very toxic to agricultural animals. Mo-reducing bacterium can be used to immobilize soluble molybdenum to insoluble forms, reducing its toxicity in the process. In this work the isolation of a novel molybdate-reducing Gram positive bacterium tentatively identified as Bacillus sp. strain A.rzi from a metal-contaminated soil is reported. The cellular reduction of molybdate to molybdenum blue occurred optimally at 4 mM phosphate, using 1% (w/v) glucose, 50 mM molybdate, between 28 and 30 °C and at pH 7.3. The spectrum of the Mo-blue product showed a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of bacterial electron transport system (ETS) such as rotenone, sodium azide, antimycin A, and potassium cyanide could not inhibit the molybdenum-reducing activity. At 0.1 mM, mercury, copper, cadmium, arsenic, lead, chromium, cobalt, and zinc showed strong inhibition on molybdate reduction by crude enzyme. The best model that fitted the experimental data well was Luong followed by Haldane and Monod. The calculated value for Luong's constants p max, K(s), S(m), and n was 5.88 μmole Mo-blue hr(-1), 70.36 mM, 108.22 mM, and 0.74, respectively. The characteristics of this bacterium make it an ideal tool for bioremediation of molybdenum pollution.

  5. Evaluation of oxide dispersion strengthened (ODS) molybdenum and molybdenum-rhenium alloys

    International Nuclear Information System (INIS)

    Mueller, A.J.; Bianco, R.; Buckman, R.W. Jr.

    1999-01-01

    Oxide dispersion strengthened (ODS) molybdenum alloys being developed for high temperature applications possess excellent high temperature strength and creep resistance. In addition they exhibit a ductile-to-brittle transition temperature (DBIT) in the worked and stress-relieved condition under longitudinal tensile load well below room temperature. However, in the recrystallized condition, the DBTT maybe near or above room temperature, depending on the volume fraction of oxide dispersion and the amount of prior work. Dilute rhenium additions (7 and 14 wt.%) to ODS molybdenum were evaluated to determine their effect on low temperature ductility. The addition of 7 wt.% rhenium to the ODS molybdenum did not significantly enhance the mechanical properties. However, the addition of 14 wt.% rhenium to the ODS molybdenum resulted in a DBTT well below room temperature in both the stress-relieved and recrystallized condition. Additionally, the tensile strength of ODS Mo-14Re is greater than the base ODS molybdenum at 1,000 to 1,250 C

  6. 10Be in manganese nodules

    International Nuclear Information System (INIS)

    Thomas, J.; Parker, P.; Mangini, A.; Cochran, K.; Turekian, K.; Krishnaswami, S.; Sharma, P.

    1981-01-01

    10 Be (t/sub 1/2) = 1.5 MY) is(formed in the upper atmosphere by cosmic ray spallation on nitrogen and oxygen. It is transported to the earth's surface via precipitation. In the oceans it is eventually associated with solid phases depositing on the ocean floor such as manganese nodules and deep-sea sediments. One of the assumptions that is normally made in analysis of such processes is that 10 Be has been produced at a relatively uniform rate over the pat several million years. If we assume, in addition, that the initial specific concentration of 10 Be as it precipitates with a solid phase is invariant with time, then we would expect that the decrease of the 10 Be concentration as a function of depth in a deep-sea core or in a manganese nodule would provide a record of sediment accumulation rate in the former and of growth rate in the latter. The possibility of using cosmic-ray produced 10 Be for the dating of marine deposits had been proposed 25 years ago by Arnold and Goel et al. The method of analysis used by these investigators, and those subsequently pursuing the problem, was low-level β counting. Though the potential of using 10 Be for dating manganese nodules was explored more than a decade ago, only a few measurements of 10 Be in nodules exist in date. This is largely because of the 10 Be measurements in environmental samples have gained considerable momentum during the past 3 to 4 years, after the development of accelerator mass spectrometry for its determination

  7. Study of the molybdenum retention in alumina

    International Nuclear Information System (INIS)

    Wilkinson, Maria V.; Mondino, Angel V.; Manzini, Alberto

    2002-01-01

    The Argentine National Atomic Energy Commission routinely produces 99 Mo by fission of highly enriched uranium contained in targets irradiated in RA-3 reactor. The current process begins with the dissolution of the irradiated target in a basic media, considering the possibility of changing the targets, it could be convenient to dissolve them in acid media. The use of alumina as a first separation step in acid dissolution processes is already known although it is necessary to determine both the type of alumina to be used and the separation conditions. The study of molybdenum retention in alumina was performed at laboratory scale, using Mo-99 as radiotracer. Different kinds of alumina were tried, varying charge solution acidity. Influence of uranium concentration in the loading solution on molybdenum retention was also studied. (author)

  8. Evaluation of a molybdenum assay canister

    International Nuclear Information System (INIS)

    Yoshizumi, T.T.; Keener, S.J.

    1988-01-01

    The performance characteristics of a commercial molybdenum assay canister were evaluated. The geometrical variation of the technetium-99m (/sup 99m/Tc) activity reading was studied as a function of the elution volume for the standard vials. It was found that the /sup 99m/Tc canister activity reading was ∼ 5% lower than that of the standard method. This is due to attenuation by the canister wall. However, the effect of the geometric variation on the clinical dose preparation was found to be insignificant. The molybdenum-99 ( 99 Mo) contamination level was compared by two methods: (1) the commercial canister and (2) the standard assay kit. The 99 Mo contamination measurements with the canister indicated consistently lower readings than those with the standard 99 Mo assay kit. The authors conclude that the canister may be used in the clinical settings. However, the user must be aware of the problems and the limitations associated with this canister

  9. Electrical resistivity of sputtered molybdenum films

    International Nuclear Information System (INIS)

    Nagano, J.

    1980-01-01

    The electrical resistivity of r.f. sputtered molybdenum films of thickness 5-150 nm deposited on oxidized silicon substrates was resolved into the three electron scattering components: isotropic background scattering, scattering at grain boundaries and scattering at surfaces. It was concluded that the isotropic background scattering is almost equal to that of bulk molybdenum and is not influenced by sputtering and annealing conditions. When the film thickness is sufficient that surface scattering can be ignored, the decrease in film resistivity after annealing is caused by the decrease in scattering at the grain boundaries for zero bias sputtered films, and is caused by an increase of the grain diameter for r.f. bias sputtered films. (Auth.)

  10. Investigation of molybdenum pentachloride interaction with chlorine

    International Nuclear Information System (INIS)

    Salyulev, A.B.; Vovkotrub, Eh.G.; Strekalovskij, V.N.

    1993-01-01

    In Raman spectra of molybdenum pentachloride solutions in liquid chlorine lines were recorded in case of 397, 312, 410, 217 and 180 cm - 1 vibrations of ν 1 (A 1 '), ν 2 (A 1 '), ν 5 (E'), ν 6 (E') and ν 8 (E'') monomer (symmetry D 3h ) molecules of MoCl 5 . Interaction of molten molybdenum pentachloride with chlorine at increased (up to 6 MPa) pressures of Cl 2 was studied. In Raman spectra of its vapour distillation in liquid chlorine alongside with MoCl 5 lines appearance of new lines at 363 and 272 cm -1 , similar in their frequency to the ones calculated for the vibrations ν 1 (A 1g ) and ν 2 (E g ) of MoCl 6 molecules (symmetry O h ), was observed

  11. Molybdenum-99 supply: a global issue

    International Nuclear Information System (INIS)

    Cote, R.V.

    2011-01-01

    This article discusses the global supply of Molybdenum 99 used in nuclear medicine. Following a disruption in supplies of isotopes in the last few years, a Canadian expert panel assessed the most viable options for securing a sustainable supply of Technitium 99 over the medium to long term. The general recommendations were to strive for diversity and redundancy throughout the supply chain, leverage multi-use infrastructure, continue with international coordination and seek processing standardization within North America.

  12. Reaction between molybdenum hexafluoride and carboxylic acids

    International Nuclear Information System (INIS)

    Shustov, L.D.; Nikolenko, L.N.; Senchenkova, T.M.

    1983-01-01

    Trifluoromethyl derivatives of pyridine, imidazole and difluoromethane are synthesized during interaction of MoF 6 surplUs (190-210 deg) with nicotine-isomicotine-, 2,6-pyridinedicarboxylic-, 4,5-imidazoledicarboxyclic- and diffluoroacetic acids. The yield of trifluoromethyl derivatives attains 84%. Molybdenum hexafluoride offers some advantages in comparisoo with toxic SF 4 . MoF 6 toxicity is low; leakage of MoF 6 vapors is easily detected

  13. Statistics of grain misorientations in molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Rybin, V V; Titovets, Yu F; Teplitskij, D M; Zolotorevskij, N Yu

    1982-03-01

    Sets of misorientations between neighbouring grains for three recrystallized molybdenum polycrystals differing in purity, phase composition and prehistory are experimentally determined. The data obtained are analyzed according to modern representations of intergrain boundary structure. In the two materials among the three mentioned above the share of boundaries close to special boundaries with high density of coinciding points turned to be 1.5 times higher than in the polycrystal with chaotic distribution of grains by orientations.

  14. Manganese and the Evolution of Photosynthesis

    Science.gov (United States)

    Fischer, Woodward W.; Hemp, James; Johnson, Jena E.

    2015-09-01

    Oxygenic photosynthesis is the most important bioenergetic event in the history of our planet—it evolved once within the Cyanobacteria, and remained largely unchanged as it was transferred to algae and plants via endosymbiosis. Manganese plays a fundamental role in this history because it lends the critical redox behavior of the water-oxidizing complex of photosystem II. Constraints from the photoassembly of the Mn-bearing water-oxidizing complex fuel the hypothesis that Mn(II) once played a key role as an electron donor for anoxygenic photosynthesis prior to the evolution of oxygenic photosynthesis. Here we review the growing body of geological and geochemical evidence from the Archean and Paleoproterozoic sedimentary records that supports this idea and demonstrates that the oxidative branch of the Mn cycle switched on prior to the rise of oxygen. This Mn-oxidizing phototrophy hypothesis also receives support from the biological record of extant phototrophs, and can be made more explicit by leveraging constraints from structural biology and biochemistry of photosystem II in Cyanobacteria. These observations highlight that water-splitting in photosystem II evolved independently from a homodimeric ancestral type II reaction center capable of high potential photosynthesis and Mn(II) oxidation, which is required by the presence of homologous redox-active tyrosines in the modern heterodimer. The ancestral homodimer reaction center also evolved a C-terminal extension that sterically precluded standard phototrophic electron donors like cytochrome c, cupredoxins, or high-potential iron-sulfur proteins, and could only complete direct oxidation of small molecules like Mn2+, and ultimately water.

  15. Biomass as biosorbent for molybdenum ions

    Energy Technology Data Exchange (ETDEWEB)

    Yamaura, Mitiko; Santos, Jacinete L. dos; Damasceno, Marcos O.; Egute, Nayara dos S.; Moraes, Adeniane A.N.; Santos, Bruno Z., E-mail: myamaura@ipen.br, E-mail: jlsantos@ipen.br, E-mail: molidam@ipen.br, E-mail: nayara.egute@usp.br, E-mail: adenianemrs@ig.com.br, E-mail: bzsantos@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Biosorbents have been focused as renewable materials of low cost, and have been used for metal removal from the wastewater by adsorption phenomenon. Biosorbents are prepared of biomass, whose reactive sites in its chemical structure have affinity to bind to metal ions. In this work, performance of corn husk, sugarcane bagasse, coir, banana peel, fish scale, chitin and chitosan as biosorbents of molybdenum (VI) ions in aqueous medium was evaluated. The adsorption experiments were investigated in a batch system varying the pH solution from 0.5 to 12 and the contact time between the phases from 2 min to 70 min. {sup 99}Mo radioisotope was used as radioactive tracer for analysis of molybdenum ions by gamma spectroscopy using a HPGe detector. Results revealed that acidity of the solution favored the adsorption of Mo (VI) ions on the all biosorbents. Adsorption values higher than 85% were found on sugarcane bagasse, coir, corn husk, chitin and chitosan at pH 2.0. Only the chitosan was dissolved at pH 0.5 and a gel was formed. The models of pseudo-second order and external film diffusion described the kinetics of adsorption of Mo ions on the coir. This work showed that the studied biomass has high potential to be used as biosorbent of molybdenum ions from acidic wastewater, and the kinetics of Mo adsorption on the coir suggested high-affinity adsorption governed by chemisorption. (author)

  16. Biomass as biosorbent for molybdenum ions

    International Nuclear Information System (INIS)

    Yamaura, Mitiko; Santos, Jacinete L. dos; Damasceno, Marcos O.; Egute, Nayara dos S.; Moraes, Adeniane A.N.; Santos, Bruno Z.

    2013-01-01

    Biosorbents have been focused as renewable materials of low cost, and have been used for metal removal from the wastewater by adsorption phenomenon. Biosorbents are prepared of biomass, whose reactive sites in its chemical structure have affinity to bind to metal ions. In this work, performance of corn husk, sugarcane bagasse, coir, banana peel, fish scale, chitin and chitosan as biosorbents of molybdenum (VI) ions in aqueous medium was evaluated. The adsorption experiments were investigated in a batch system varying the pH solution from 0.5 to 12 and the contact time between the phases from 2 min to 70 min. 99 Mo radioisotope was used as radioactive tracer for analysis of molybdenum ions by gamma spectroscopy using a HPGe detector. Results revealed that acidity of the solution favored the adsorption of Mo (VI) ions on the all biosorbents. Adsorption values higher than 85% were found on sugarcane bagasse, coir, corn husk, chitin and chitosan at pH 2.0. Only the chitosan was dissolved at pH 0.5 and a gel was formed. The models of pseudo-second order and external film diffusion described the kinetics of adsorption of Mo ions on the coir. This work showed that the studied biomass has high potential to be used as biosorbent of molybdenum ions from acidic wastewater, and the kinetics of Mo adsorption on the coir suggested high-affinity adsorption governed by chemisorption. (author)

  17. Preparation of single phase molybdenum boride

    International Nuclear Information System (INIS)

    Camurlu, Hasan Erdem

    2011-01-01

    Highlights: → Formation of Mo and a mixture of molybdenum boride phases take place in preparation of molybdenum borides. → It is intricate to prepare single phase molybdenum borides. → Formation of single phase MoB from MoO 3 + B 2 O 3 + Mg mixtures has not been reported previously. → Single phase MoB was successfully prepared through a combination of mechanochemical synthesis and annealing process. - Abstract: The formation of MoB through volume combustion synthesis (VCS), and through mechanochemical synthesis (MCS) followed by annealing has been investigated. MoO 3 , B 2 O 3 and Mg were used as reactants while MgO and NaCl were introduced as diluents. Products were leached in dilute HCl solution and were subjected to X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) examinations. Mo was the major phase component in the VCS products under all the experimental conditions. Mo 2 B, MoB, MoB 2 and Mo 2 B 5 were found as minor phases. Products of MCS contained a mixture of Mo 2 B, MoB, MoB 2 and Mo. After annealing the MCS product at 1400 deg. C for 3 h, single phase α-MoB was obtained.

  18. Weldability of powder-metallurgy molybdenum with low oxygen content

    International Nuclear Information System (INIS)

    Hiraoka, Yutaka; Okada, Masatoshi

    1987-01-01

    Relationships between the formation of weld pores and the chemical compositions in powder-metallurgy molybdenum were investigated. It is suggested that almost 100% of Ca and Mg form oxides. In contrast, Fe, Ni, Cr and Al, Si only partly form oxides. A powder-metallurgy molybdenum containing less than 84 at.ppm oxygen did not show any large weld pores. The reduction of the oxygen content was achieved by purifying the molybdenum powder. (orig.) [de

  19. Molybdenum(6) complexing with ethylenediaminedisuccinic acid from PMR spectroscopy data

    International Nuclear Information System (INIS)

    Larchenko, V.E.; Kovaleva, I.B.; Mitrofanova, N.D.; Martynenko, L.I.

    1989-01-01

    Methods of high resolution PMR spectroscopy and pH potentiometry are used to study molybdenum(6) complexing with ethylenediaminedisuccinic acid in aqueous solutions. It is shown that molybdenum(6) interacts with ethylenediaminedisuccinic acid in the narrow range of pH values 4.0-6.5, where MoO 3 H 2 L 2 - and MoO 3 HL 3- complexes with asymmetrical structure are formed. Composition and structure of molybdenum(6) ethylenediaminedisuccinates and ethylenediaminetetraacetates are compared

  20. Deformation localization and cyclic strength in polycrystalline molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, O.T.; Rakshin, A.F.; Fenyuk, M.I.

    1983-06-01

    Conditions of deformation localization and its interrelation with cyclic strength in polycrystalline molybdenum were investigated. A fatigue failure of polycrystalline molybdenum after rolling and in an embrittled state reached by recrystallization annealing under cyclic bending at room temperature takes place under nonuniform distribution of microplastic strain resulting in a temperature rise in separate sections of more than 314 K. More intensive structural changes take place in molybdenum after rolling than in recrystallized state.

  1. Matrix composition effects on the tensile properties of tungsten-molybdenum heavy alloys

    International Nuclear Information System (INIS)

    Bose, A.; German, R.N.

    1990-01-01

    Tungsten-base heavy alloys are liquid-phase sintered from mixed tungsten, nickel, and iron powders. The sintered product is a composite consisting of interlaced tungsten and solidified matrix (W-Ni-Fe) phases. These alloys are most useful in applications requiring high density, strength, and toughness. The design of improved tungsten heavy alloys has been the subject of several research investigations. Much success has taken place through improved processing, but parallel compositional studies have resulted in new microstructure-property combinations. As part of these investigations, the Ni/Fe ratio has been varied, with the general conclusion that optimal strength and ductility occur with a ratio between 2 and 4. Brittle intermetallic phases can form outside of this composition range. Historically, a 7/3 Ni/Fe ratio has been selected for processing studies. Recently, others reported higher ductilities and impact energies for 90 and 93 pct W heavy alloys with the 8/2 Ni/Fe ratio. Alternatively, these alloys can be strengthened by both solid solution and grain size refinement through incorporation of molybdenum, tantalum, or rhenium. These additions are soluble in both the tungsten and matrix phases and retard solution-reprecipitation during liquid phase sintering. In this study, the alloy composition was varied in the nickel/iron ratio and molybdenum was partially substituted for tungsten. The sintered tensile properties are assessed vs these compositional variations

  2. The separation and determination of trace elements in iron ore

    International Nuclear Information System (INIS)

    Jones, E.A.

    1977-01-01

    The separation, concentration, and determination of trace elements in iron ores are described. After the sample has been dissolved, the iron is separated by liquid-liquid extraction with a liquid cation-exchanger, di-(2-ethylhexyl) phosphoric acid. The trace elements aluminium, cadmium, calcium, chromium, cobalt, copper, lead, magnesium, manganese, mercury, potassium, sodium, vanadium, and zinc are determined in the aqueous phase by atomic-absorption spectrophotometry

  3. Influence of Irrigation Rate and Soil Type on the Vertical Migration of Iron and Manganese in the Soils of South-East Spain; Influencia de la Cantidad de Riego y Tipo de Suelo sobre la Emigracion Vertical de Hierro y Manganeso en Suelos del Sureste Espanol

    Energy Technology Data Exchange (ETDEWEB)

    Costa, F.; Carpena, O. [Instituto Nacional de Edafologia y Agrobiologia, Centro de Edafologia y Biologia Aplicada del Segura, Murcia (Spain); Esparraguera, I.; Ortin, N.; Del Val, M.; La Cruz, F. de; Cellini, R. F. [Junta de Energia Nuclear, Madrid (Spain)

    1967-11-15

    The citrus plantations in south-east Spain, situated largely on calcareous soils which are submitted to intensive cultivation, are investigating nutritional changes caused mainly by deficiencies of trace elements, especially iron and manganese, which result in a lower yield and premature exhaustion of the trees. The paper deals with a radioactive tracer study of the behaviour of these ions in soils and with the factors influencing their migration to the root zone; the object of the work is to develop a rational and economic fertilization policy. The work has been based on two types of soil, representing extreme situations encountered in practice; one soil is calcareous and the other non-calcareous. A set of columnsiwas assembled, each column having a length of 1 m and a cross-section of 32 cm{sup 2} ; solutions of {sup 59}Fe and {sup 54}Mn were added to these columns both in sulphate and chelate form. A definite amount of water, proportional to the requirements .of citrus plantations, was intermittently passed through these columns. Soil samples were taken periodically and the total activity and the activity of the assimilable and non-assimilable fractions of the elements being studied were measured. At the same time an apparatus involving a collimated scintillation detector was developed to follow the vertical migration of these ions in soils; the water drained from the columns after each irrigation was analysed radiochemically for the same purpose. (author) [Spanish] Las plantaciones citrfcolas del sureste espanol, radicadas en gran parte sobre suelos calizos y sometidos a cultivos intensivos, experimentan con el tiempo alteraciones de orden nutritivo debido principalmente a deficiencias de oligoelementos, especialmente hierro y manganeso, que se traduce en una menor produccion y en un agotamiento prematuro de los arboles. En la presente comunicacion se estudia, mediante trazadores radiactivos, el comportamiento de estos iones en los suelos, asi como los factores

  4. Sorption of molybdenum by cellulose polyphosphate from acid solutions

    International Nuclear Information System (INIS)

    Luneva, N.K.; Oputina, A.G.; Ermolenko, I.N.

    1985-01-01

    The sorption of molybdenum on cellulose polyphosphate from acid solutions of ammonium molybdate depending on the phosphorus content in samples, concentration and pH of the solution, sorption time is studied. It is shown that a maximum molybdenum content on the cellulose samples with different phosphorus content is pointed out at an ammonium molybdate concentration 0.02 M. Saturation of the sorption curve is attained at molar ratio of adsrbed molybdenum to phosphorus 1:4. In case of small fillings the compound with molybdenum to phosphorus ratio 1:10 is formed

  5. Separation of uranium from molybdenum by alkyl phosphoric acid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Zhongshi, Li

    1986-08-01

    The regularities of separation of uranium from molybdenum by alkyl phosphoric acid extraction are described. Two parameters, i.e., density ratio of uranium to molybdenum in organic phase at first stage and density of uranium in raffinate at last stage are presented. The relationship between these parameters and purity of molybdenum and uranium products is given. The method of adjusting and controlling these parameters in experiments and production is worked out. The technical key problem in comprehensive utilization of sedimentary type uranium ore containing molybdenum with close concentration of these to elements has been solved.

  6. Effect of processing variables on mechanical properties of sintered manganese steels Fe-3%Mn-0.8%C

    International Nuclear Information System (INIS)

    Sulowski, M.; Cias, A.

    1998-01-01

    The powder metallurgy route may allow sintered manganese steels to be made based on pure iron powder and ferromanganese powder with control over alloy microstructure. The factors that contribute to the mechanical properties of sintered Fe-3%Mn-0.8%C manganese steel, such as the sintering atmosphere, dew point, sintering temperature, cooling rate are summarised. The paper shows the influence of these parameters on the tensile strength, yield strength, transverse rupture strength, impact strength and hardness. It is showed that tensile high strength level higher than those of many present sintered steels can be obtained already in the as-sintered condition. (author)

  7. Growth and characterization of gel grown pure and mixed iron ...

    Indian Academy of Sciences (India)

    Unknown

    is to grow pure and mixed iron (II)–manganese levo-tartrate crystals by the single diffusion gel growth technique and characterize them by several methods. 2. ... also attracted several researchers to grow different crystals for various ...

  8. A comparison of the iraddiated tensile properties of a high-manganese austenitic steel and type 316 stainless steel

    International Nuclear Information System (INIS)

    Klueh, R.L.; Grossbeck, M.L.

    1984-01-01

    The USSR steel EP-838 is a high-manganese, low-nickel steel that also has lower chromium and molybdenum than type 316 stainless steel. Tensile specimens of 20%-cold-worked EP-838 and type 316 stainless steel were irradiated in the High Flux Isotope Reactor (HFIR) at the coolant temperature (approx.=50 0 C). A displacement damage level of 5.2 dpa was reached for the EP-838 and up to 9.5 dpa for the type 316 stainless steel. Tensile tests at room temperature and 300 0 C on the two steels indicated that the irradiation led to increased strength and decreased ductility compared to the unirradiated steels. Although the 0.2% yield stress of the type 316 stainless steel in the unirradiated condition was greater than that for the EP-838, after irradiation there was essentially no difference between the strength or ductility of the two steels. The results indicate that the replacement of the majority of the nickel by manganese and a reduction of chromium and molybdenum in an austenitic stainless steel of composition near that for type 316 stainless steel has little effect on the irradiated and unirradiated tensile properties at low temperatures. (orig.)

  9. Mutation in HFE gene decreases manganese accumulation and oxidative stress in the brain after olfactory manganese exposure.

    Science.gov (United States)

    Ye, Qi; Kim, Jonghan

    2016-06-01

    Increased accumulation of manganese (Mn) in the brain is significantly associated with neurobehavioral deficits and impaired brain function. Airborne Mn has a high systemic bioavailability and can be directly taken up into the brain, making it highly neurotoxic. While Mn transport is in part mediated by several iron transporters, the expression of these transporters is altered by the iron regulatory gene, HFE. Mutations in the HFE gene are the major cause of the iron overload disorder, hereditary hemochromatosis, one of the prevalent genetic diseases in humans. However, whether or not HFE mutation modifies Mn-induced neurotoxicity has not been evaluated. Therefore, our goal was to define the role of HFE mutation in Mn deposition in the brain and the resultant neurotoxic effects after olfactory Mn exposure. Mice carrying the H67D HFE mutation, which is homologous to the H63D mutation in humans, and their control, wild-type mice, were intranasally instilled with MnCl2 with different doses (0, 0.2, 1.0 and 5.0 mg kg(-1)) daily for 3 days. Mn levels in the blood, liver and brain were determined using inductively-coupled plasma mass spectrometry (ICP-MS). H67D mutant mice showed significantly lower Mn levels in the blood, liver, and most brain regions, especially in the striatum, while mice fed an iron-overload diet did not. Moreover, mRNA expression of ferroportin, an essential exporter of iron and Mn, was up-regulated in the striatum. In addition, the levels of isoprostane, a marker of lipid peroxidation, were increased in the striatum after Mn exposure in wild-type mice, but were unchanged in H67D mice. Together, our results suggest that the H67D mutation provides decreased susceptibility to Mn accumulation in the brain and neurotoxicity induced by inhaled Mn.

  10. On the effect of interaction of molybdenum trioxide and magnesium oxide in water

    International Nuclear Information System (INIS)

    Bunin, V.M.; Karelin, A.I.; Solov'eva, L.N.

    1992-01-01

    Interaction of molybdenum trioxide and magnesium oxide in water was studied. It is shown that molybdenum trioxide forms consecutively magnesium molybdate, dimolybdate and magnesium polymolybdates with magnesium oxide

  11. The impact of anthropogenic factors on the occurrence of molybdenum in stream and river sediments of central Upper Silesia (Southern Poland

    Directory of Open Access Journals (Sweden)

    Pasieczna Anna

    2017-12-01

    Full Text Available In our study, a detailed survey was conducted with the aim to determine the distribution and possible anthropogenic sources of molybdenum in river and stream sediments in the central Upper Silesian Industrial Region (Southern Poland, where for many years, iron and zinc smelters as well as coking and thermal power plants were operating. At the same time, this has also been a residential area with the highest population density in the country. Sediments (1397 samples in total were collected from rivers and streams, and analysed for the content of molybdenum and 22 other elements. ICP-AES and CV-AAS methods were applied for the determination of the content of elements. The studies revealed molybdenum content in the range of 5 mg·kg−1. The spatial distribution of molybdenum demonstrated by the geochemical map has indicated that the principal factor determining its content in sediments is the discharge of wastewater from steelworks and their slag heaps. Another source of this element in sediments has been the waste of the historical mining of zinc ore and metallurgy of this metal. Additionally, molybdenum migration from landfills of power plants, coal combustion and Mo emission to the atmosphere and dust fall-out have been significant inputs of Mo pollution to the sediments.

  12. The aluminosilicate fraction of North Pacific manganese nodules

    Science.gov (United States)

    Bischoff, J.L.; Piper, D.Z.; Leong, K.

    1981-01-01

    Nine nodules collected from throughout the deep North Pacific were analyzed for their mineralogy and major-element composition before and after leaching with Chester-Hughes solution. Data indicate that the mineral phillipsite accounts for the major part (> 75%) of the aluminosilicate fraction of all nodules. It is suggested that formation of phillipsite takes place on growing nodule surfaces coupled with the oxidation of absorbed manganous ion. All the nodules could be described as ternary mixtures of amorphous iron fraction (Fe-Ti-P), manganese oxide fraction (Mn-Mg Cu-Ni), and phillipsite fraction (Al-Si-K-Na), these fractions accounting for 96% of the variability of the chemical composition. ?? 1981.

  13. Manganese oxide nanoparticles, methods and applications

    Science.gov (United States)

    Abruna, Hector D.; Gao, Jie; Lowe, Michael A.

    2017-08-29

    Manganese oxide nanoparticles having a chemical composition that includes Mn.sub.3O.sub.4, a sponge like morphology and a particle size from about 65 to about 95 nanometers may be formed by calcining a manganese hydroxide material at a temperature from about 200 to about 400 degrees centigrade for a time period from about 1 to about 20 hours in an oxygen containing environment. The particular manganese oxide nanoparticles with the foregoing physical features may be used within a battery component, and in particular an anode within a lithium battery to provide enhanced performance.

  14. Research of the technology of obtaining pure and disperse molybdenum disulfide from molybdenum concentrate

    International Nuclear Information System (INIS)

    Hovsepyan, A.H.; Israyelyan, S.M.

    2009-01-01

    The technology of obtaining pure and disperse molybdenum disulfide is worked out. The processes of refinement from the flotation reagents and deslimation by means of decantation, refinement of molybdenite concentrate from impurities by selective leaching methods are studied. The optimal regime of technological process is chosen

  15. Microbial dissimilatory iron(III) reduction: Studies on the mechanism and on processes of environmental relevance

    OpenAIRE

    Jahn, Michael

    2005-01-01

    Many microbes are able to respire aerobically oxygen or anaerobically other electron acceptors for example sulphate, nitrate, manganese(IV) or Fe(III). As iron minerals are widespread in nature, dissimilatory iron(III) reduction by different microorganisms is a very important process of anaerobic respiration. The general goal of this work was to improve the knowledge of processes, in which iron-reducing microbes are said to play an important role. For this purpose, in one part the focus wa...

  16. The Effect of Molybdenum Fertilization on Arachis Glabrata Biomass ...

    African Journals Online (AJOL)

    The effect of molybdenum fertilization on biomass and the number of nodules of Arachis glabrata was assessed at the Teaching and Research Farm of the University of Dschang in 2011 at different periods of mowing. A factorial design comparing four doses of molybdenum as ammonium molybdate (0, 0.75, 1.5 and 2.25 ...

  17. Tetrathionate reductase of Salmonella thyphimurium: a molybdenum containing enzyme

    International Nuclear Information System (INIS)

    Hinojosa-Leon, M.; Dubourdieu, M.; Sanchez-Crispin, J.A.; Chippaux, M.

    1986-01-01

    Use of radioactive molybdenum demonstrates that the tetrathionate reductase of Salmonella typhimurium is a molydenum containing enzyme. It is proposed that this enzyme shares with other molybdo-proteins, such as nitrate reductase, a common molybdenum containing cofactor the defect of which leads to the loss of the tetrathionate reductase and nitrate reductase activities

  18. Influence of Soil Solution Salinity on Molybdenum Adsorption by Soils

    Science.gov (United States)

    Molybdenum (Mo) adsorption on five arid-zone soils from California was investigated as a function of equilibrium solution Mo concentration (0-30 mg L-1), solution pH (4-8), and electrical conductivity (EC = 0.3 or 8 dS m-1). Molybdenum adsorption decreased with increasing pH. An adsorption maximum...

  19. Low-temperature heat capacity of molybdenum borides

    International Nuclear Information System (INIS)

    Bolgar, A.S.; Klinder, A.V.; Novoseletskaya, L.M.; Turov, V.P.; Klochkov, L.A.; Lyashchenko, A.B.

    1988-01-01

    Heat capacity of molybdenum borides Mo 2 B, MoB, Mo 2 B 5 is studied for the first time in the 60-300 K range using the adiabatic method. Standard (at 298.15 K) thermodynamic functions (enthalpy, heat capacity, entropy, reduced Gibbs energy) of molybdenum borides are calculated

  20. Kinetics of Molybdenum Reduction to Molybdenum Blue by Bacillus sp. Strain A.rzi

    Directory of Open Access Journals (Sweden)

    A. R. Othman

    2013-01-01

    Full Text Available Molybdenum is very toxic to agricultural animals. Mo-reducing bacterium can be used to immobilize soluble molybdenum to insoluble forms, reducing its toxicity in the process. In this work the isolation of a novel molybdate-reducing Gram positive bacterium tentatively identified as Bacillus sp. strain A.rzi from a metal-contaminated soil is reported. The cellular reduction of molybdate to molybdenum blue occurred optimally at 4 mM phosphate, using 1% (w/v glucose, 50 mM molybdate, between 28 and 30°C and at pH 7.3. The spectrum of the Mo-blue product showed a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of bacterial electron transport system (ETS such as rotenone, sodium azide, antimycin A, and potassium cyanide could not inhibit the molybdenum-reducing activity. At 0.1 mM, mercury, copper, cadmium, arsenic, lead, chromium, cobalt, and zinc showed strong inhibition on molybdate reduction by crude enzyme. The best model that fitted the experimental data well was Luong followed by Haldane and Monod. The calculated value for Luong’s constants pmax, Ks, Sm, and n was 5.88 μmole Mo-blue hr−1, 70.36 mM, 108.22 mM, and 0.74, respectively. The characteristics of this bacterium make it an ideal tool for bioremediation of molybdenum pollution.

  1. The detection of magnetotactic bacteria in deep sea sediments from the east Pacific Manganese Nodule Province.

    Science.gov (United States)

    Dong, Yi; Li, Jinhua; Zhang, Wuchang; Zhang, Wenyan; Zhao, Yuan; Xiao, Tian; Wu, Long-Fei; Pan, Hongmiao

    2016-04-01

    Magnetotactic bacteria (MTB) are distributed ubiquitously in sediments from coastal environments to the deep sea. The Pacific Manganese Nodule Province contains numerous polymetallic nodules mainly composed of manganese, iron, cobalt, copper and nickel. In the present study we used Illumina MiSeq sequencing technology to assess the communities of putative MTB in deep sea surface sediments at nine stations in the east Pacific Manganese Nodule Province. A total of 402 sequence reads from MTB were classified into six operational taxonomic units (OTUs). Among these, OTU113 and OTU759 were affiliated with the genus Magnetospira, OTU2224 and OTU2794 were affiliated with the genus Magnetococcus and Magnetovibrio, respectively, OTU3017 had no known genus affiliation, and OTU2556 was most similar to Candidatus Magnetananas. Interestingly, OTU759 was widely distributed, occurring at all study sites. Magnetism measurements revealed that all sediments were dominated by low coercivity, non-interacting single domain magnetic minerals. Transmission electron microscopy confirmed that the magnetic minerals were magnetosomes. Our data suggest that diverse putative MTB are widely distributed in deep sea surface sediments from the east Pacific Manganese Nodule Province. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  2. Behaviour of helium after implantation in molybdenum

    International Nuclear Information System (INIS)

    Viaud, C.; Maillard, S.; Carlot, G.; Valot, C.; Gilabert, E.; Sauvage, T.; Peaucelle, C.; Moncoffre, N.

    2009-01-01

    This study deals with the behaviour of helium in a molybdenum liner dedicated to the retention of fission products. More precisely this work contributes to evaluate the release of implanted helium when the gas has precipitated into nanometric bubbles close to the free surface. A simple model dedicated to calculate the helium release in such a condition is presented. The specificity of this model lays on the assumption that the gas is in equilibrium with a simple distribution of growing bubbles. This effort is encouraging since the calculated helium release fits an experimental dataset with a set of parameters in good agreement with the literature

  3. Spectra from foil-excited molybdenum ions

    International Nuclear Information System (INIS)

    Johnson, B.M.; Jones, K.W.; Cecchi, J.L.; Kruse, T.H.

    1978-01-01

    The extreme-ultraviolet spectra (5 to 55 nm) for foil-excited molybdenum ions have been measured using 22 to 200 MeV beams from the Brookhaven National Laboratory MP tandem Van de Graaff accelerator facility, 20 μg/cm 2 C stripping foils, and a grazing incidence spectrometer. The mean ion charge states (13 to 28) and the narrow distribution widths (about 2 charge states) were accurately predictable from experimental parameters. Where possible, comparisons are given with Mo radiation from tokamaks, vacuum sparks, and laser-excited plasmas

  4. Molybdenum protective coatings adhesion to steel substrate

    Science.gov (United States)

    Blesman, A. I.; Postnikov, D. V.; Polonyankin, D. A.; Teplouhov, A. A.; Tyukin, A. V.; Tkachenko, E. A.

    2017-06-01

    Protection of the critical parts, components and assemblies from corrosion is an urgent engineering problem and many other industries. Protective coatings’ forming on surface of metal products is a promising way of corrosionprevention. The adhesion force is one of the main characteristics of coatings’ durability. The paper presents theoretical and experimental adhesion force assessment for coatings formed by molybdenum magnetron sputtering ontoa steel substrate. Validity and reliability of results obtained by simulation and sclerometry method allow applying the developed model for adhesion force evaluation in binary «steel-coating» systems.

  5. MHD simulations of molybdenum X-pinches

    International Nuclear Information System (INIS)

    Ivanenkov, G.V.; Stepnevski, V.

    2002-01-01

    One investigates into compression of molybdenum X-pinches applying numerical MHD-models with parabolic and conical initial geometry. The second model describing plasma axial motion in greater detail offers a real geometry of a discharge and is applicable to loads characterized by higher masses in contrast to the first one. Both models enabled to describe all basic phases of compression including origination of a minidiode, occurrence of a narrow neck, microexplosion of a hot point and origination of shock waves followed by sausage instability [ru

  6. Hot rolling of thick uranium molybdenum alloys

    Science.gov (United States)

    DeMint, Amy L.; Gooch, Jack G.

    2015-11-17

    Disclosed herein are processes for hot rolling billets of uranium that have been alloyed with about ten weight percent molybdenum to produce cold-rollable sheets that are about one hundred mils thick. In certain embodiments, the billets have a thickness of about 7/8 inch or greater. Disclosed processes typically involve a rolling schedule that includes a light rolling pass and at least one medium rolling pass. Processes may also include reheating the rolling stock and using one or more heavy rolling passes, and may include an annealing step.

  7. Electrochemical ammonia production on molybdenum nitride nanoclusters

    DEFF Research Database (Denmark)

    Howalt, Jakob Geelmuyden; Vegge, Tejs

    2013-01-01

    Theoretical investigations of electrochemical production of ammonia at ambient temperature and pressure on nitrogen covered molybdenum nanoparticles are presented. Density functional theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free...... energy profile for electrochemical protonation of N2 and N adatoms on cuboctahedral Mo13 nanoparticles. Pathways for electrochemical ammonia production via direct protonation of N adatoms and N2 admolecules with an onset potential as low as -0.5 V and generally lower than -0.8 V on both a nitrogen...

  8. Simulations of intergranular fracture in nanocrystalline molybdenum

    DEFF Research Database (Denmark)

    Frederiksen, Søren Lund; Jacobsen, Karsten Wedel; Schiøtz, Jakob

    2004-01-01

    Using molecular dynamics simulations we investigate the plastic deformation of nanocrystalline molybdenum with a grain size of 12 nm at high strain rates. The simulations are performed with an interatomic potential which is obtained through matching of atomic forces to a database generated...... with density-functional calculations. The simulations show the plastic deformation to involve both grain boundary processes and dislocation migration which in some cases lead to twin boundary formation. A large component of the strain is accommodated through the formation of cracks in the grain boundaries...

  9. Molybdenum Dichalcogenides for Environmental Chemical Sensing

    Directory of Open Access Journals (Sweden)

    Dario Zappa

    2017-12-01

    Full Text Available 2D transition metal dichalcogenides are attracting a strong interest following the popularity of graphene and other carbon-based materials. In the field of chemical sensors, they offer some interesting features that could potentially overcome the limitation of graphene and metal oxides, such as the possibility of operating at room temperature. Molybdenum-based dichalcogenides in particular are among the most studied materials, thanks to their facile preparation techniques and promising performances. The present review summarizes the advances in the exploitation of these MoX2 materials as chemical sensors for the detection of typical environmental pollutants, such as NO2, NH3, CO and volatile organic compounds.

  10. Molybdenum oxide nanocubes: Synthesis and characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Muthamizh, S.; Suresh, R.; Giribabu, K.; Manigandan, R.; Kumar, S. Praveen; Munusamy, S.; Narayanan, V., E-mail: vnnara@yahoo.co.in [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai -600025 (India); Stephen, A. [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-600025 (India)

    2015-06-24

    Molybdenum oxide nanoparticles were prepared by Solid state synthesis. The MoO{sub 3} nanoparticles were synthesized by using commercially available ammonium heptamolybdate. The XRD pattern reveals that the synthesized MoO{sub 3} has orthorhombic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MoO{sub 3} nanoparticles. DRS-UV analysis shows that MoO{sub 3} has a band gap of 2.89 eV. FE-SEM analysis confirms the material morphology in cubes with nano scale.

  11. Solid solutions of hydrogen in niobium, molybdenum and their alloys

    International Nuclear Information System (INIS)

    Ishikawa, T.T.

    1981-01-01

    The solubility of hydrogen in niobium, molybdenum and niobium-molybdenum alloys with varying atomic fraction of molybdenum from 0.15 to 0.75 was measured on the temperature range of 673 0 K to 1273 0 k for one atmosphere hydrogen pressure. The experimental technique involved the saturation of the solvent metal or alloy with hydrogen, followed by quenching and analysis of the solid solution. The results obtained of hydrogen solubility are consistent with the quasi-regular model for the dilute interstitial solid solutions. The partial molar enthalpy and partial molar entropy in excess of the dissolved hydrogen atoms were calculated from data of solubility versus reciprocal doping temperature. The variation of the relative partial molar enthalpy of hydrogen dissolved in niobium-molybdenum alloys, with the increase of molybdenum content of the alloy was analized. (Author) [pt

  12. Thermal cyclic strength of molybdenum monocrystal at high temperatures

    International Nuclear Information System (INIS)

    Strizhalo, V.A.; Uskov, E.I.

    1975-01-01

    The results of the investigation of the thermocyclic creep and low-cycle fatigue of a molybdenum single crystal are discussed. The strength of a molybdenum single crystal under nonisothermal stressing has been investigated by using two different regimes of temperature and load variation. The temperature limits of the cycle were the same for the two testing regimes, the maximum temperature being 1700degC and the minimum 350degC. At higher temperatures (above 1500degC) the short-term strength of single-crystal molybdenum is comparable with that of commercial molybdenum and the refractory alloys, while the ductility is considerably higher. It should be noted that the failure of single-crystal molybdenum under rigid alternating loading is preceded by intensive distortion of the specimen, owing to directional cyclic creep of the metal in zones of bulging and thinning

  13. Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria

    OpenAIRE

    Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

    2012-01-01

    Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the p...

  14. 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.

  15. Manganese(II) chelate contrast media

    International Nuclear Information System (INIS)

    Rocklage, S.M.; Quay, S.C.

    1994-01-01

    New chelate forming compounds for use as contrast media in NMR imaging are described. Especially mentioned are manganese(II) ion chelates of N,N' dipyridoxaldiamine, N,N' diacetic acid, and salts and esters thereof. 1 fig

  16. 21 CFR 73.2775 - Manganese violet.

    Science.gov (United States)

    2010-04-01

    .... Mercury (as Hg), not more than 1 part per million. Total color, based on Mn content in “as is” sample, not less than 93 percent. (c) Uses and restrictions. Manganese violet is safe for use in coloring cosmetics...

  17. Synthesis of molybdenum borides and molybdenum silicides in molten salts and their oxidation behavior in an air-water mixture

    NARCIS (Netherlands)

    Kuznetsov, S.A.; Kuznetsova, S.V.; Rebrov, E.V.; Mies, M.J.M.; Croon, de M.H.J.M.; Schouten, J.C.

    2005-01-01

    The formation of various coatings in molybdenum-boron and molybdenum-silicon systems was investigated. Boronizing and siliciding treatments were conducted in molten salts under inert gas atm. in the 850-1050 DegC temp. range for 7 h. The presence of boride (e.g. Mo2B, MoB, Mo2B5) and silicide

  18. Personality traits in persons with manganese poisoning

    Energy Technology Data Exchange (ETDEWEB)

    Platonov, A A

    1976-10-01

    Results of studies with the Minnesota Multiphasic Personality Inventory (MMPI) in 3 groups of arc welders with various degrees of manganese poisoning (22 symptom-free, 23 with functional disturbances, 55 with organic symptoms) and 50 controls were discussed. There was a close relation between the severity of the poisoning and quantitative and qualitative personality changes. Personality tests are considered a useful addition to the clinical diagnosis of chronic manganese poisoning.

  19. Crystallization and structure of chromium cast iron with addition of Mo and Ni

    International Nuclear Information System (INIS)

    Pietrowski, S.

    1998-01-01

    The aim of the presented paper is to show the results of examination of the crystallization process using the method of thermal-derivative analysis (ATD) and the structure examination of chromium cast iron, chromium molybdenum c. i. and chromium molybdenum nickel c.i. It was found that molybdenum in amount over 2 wt % causes the crystallization of eutectic carbides M 23 C 6 and M 6 C. The M 23 C 6 carbide crystallizes upon the crystallization of eutectic carbides M 3 C and M 7 C 3 . It is shown that ATD method facilitates both interpretation and control of the crystallization as well as formation of the cast iron structure at the solid state. (author)

  20. Iron behavior in the ozonation and filtration of groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Sallanko, J.; Lakso, E.; Ropelinen, J. [University of Oulu, Oulu (Finland)

    2006-08-15

    In Finnish groundwater, the main substances that require treatment are iron and manganese. In addition to this, groundwaters are soft and acidic. Iron removal is usually relatively effective by oxidizing dissolved iron into an insoluble form, either by aeration or chemical oxidation and removing the formed precipitate by sand filtration. Sometimes, if the untreated water contains high amounts of organic matter, problems may arise for iron removal. In Finland, it is quite common that groundwater contains high levels of both iron and natural organic matter, mainly as humic substances. The groundwater of the Kukkala intake plant in Liminka has been found to be problematic, due to its high level of natural organic matter. This research studied the removal of iron from this water by means of oxidation with ozone and filtration. While the oxidation of iron by ozone was rapid, the precipitate particles formed were small, and thus could not be removed by sand and anthracite filtration, and the iron residue in the treated water was more than 2 mg L{sup -1}. And while the filtration was able to remove iron well without the feed of ozone, the iron residue in the treated water was only 0.30 mg L{sup -1}. In this case, iron was led to the filter in a bivalent dissolved form. So, the result of iron removal was the best when the sand/anthracite filter functioned largely as an adsorption filter.

  1. Autonomic function in manganese alloy workers

    Energy Technology Data Exchange (ETDEWEB)

    Barrington, W.W.; Angle, C.R.; Willcockson, N.K.; Padula, M.A. [Univ. of Nebraska Medical Center, Omaha, NE (United States); Korn, T.

    1998-07-01

    The observation of orthostatic hypotension in an index case of manganese toxicity lead to this prospective attempt to evaluate cardiovascular autonomic function and cognitive and emotional neurotoxicity in eight manganese alloy welders and machinists. The subjects consisted of a convenience sample consisting of an index case of manganese dementia, his four co-workers in a frog shop for gouging, welding, and grinding repair of high manganese railway track and a convenience sample of three mild steel welders with lesser manganese exposure also referred because of cognitive or autonomic symptoms. Frog shop air manganese samples 9.6--10 years before and 1.2--3.4 years after the diagnosis of the index case exceeded 1.0 mg/m{sup 3} in 29% and 0.2 mg/m{sup 3} in 62%. Twenty-four-hour electrocardiographic (Holter) monitoring was used to determine the temporal variability of the heartrate (RR{prime} interval) and the rates of change at low frequency and high frequency. MMPI and MCMI personality assessment and short-term memory, figure copy, controlled oral word association, and symbol digit tests were used.

  2. Magnesium and manganese content of halophilic bacteria

    International Nuclear Information System (INIS)

    de Medicis, E.; Paquette, J.; Gauthier, J.J.; Shapcott, D.

    1986-01-01

    Magnesium and manganese contents were measured by atomic absorption spectrophotometry in bacteria of several halophilic levels, in Vibrio costicola, a moderately halophilic eubacterium growing in 1 M NaCl, Halobacterium volcanii, a halophilic archaebacterium growing in 2.5 NaCl, Halobacterium cutirubrum, an extremely halophilic archaebacterium growing in 4 M NaCl, and Escherichia coli, a nonhalophilic eubacterium growing in 0.17 M NaCl. Magnesium and manganese contents varied with the growth phase, being maximal at the early log phase. Magnesium and manganese molalities in cell water were shown to increase with the halophilic character of the logarithmically growing bacteria, from 30 mmol of Mg per kg of cell water and 0.37 mmol of Mn per kg of cell water for E. coli to 102 mmol of Mg per kg of cell water and 1.6 mmol of Mn per kg of cell water for H cutirubrum. The intracellular concentrations of manganese were determined independently by a radioactive tracer technique in V. costicola and H. volcanii. The values obtained by 54 Mn loading represented about 70% of the values obtained by atomic absorption. The increase of magnesium and manganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation

  3. Climax-Type Porphyry Molybdenum Deposits

    Science.gov (United States)

    Ludington, Steve; Plumlee, Geoffrey S.

    2009-01-01

    Climax-type porphyry molybdenum deposits, as defined here, are extremely rare; thirteen deposits are known, all in western North America and ranging in age from Late Cretaceous to mainly Tertiary. They are consistently found in a postsubduction, extensional tectonic setting and are invariably associated with A-type granites that formed after peak activity of a magmatic cycle. The deposits consist of ore shells of quartz-molybdenite stockwork veins that lie above and surrounding the apices of cupola-like, highly evolved, calc-alkaline granite and subvolcanic rhyolite-porphyry bodies. These plutons are invariably enriched in fluorine (commonly >1 percent), rubidium (commonly >500 parts per million), and niobium-tantalum (Nb commonly >50 parts per million). The deposits are relatively high grade (typically 0.1-0.3 percent Mo) and may be very large (typically 100-1,000 million tons). Molybdenum, as MoS2, is the primary commodity in all known deposits. The effect on surface-water quality owing to natural influx of water or sediment from a Climax-type mineralized area can extend many kilometers downstream from the mineralized area. Waste piles composed of quartz-silica-pyrite altered rocks will likely produce acidic drainage waters. The potential exists for concentrations of fluorine or rare metals in surface water and groundwater to exceed recommended limits for human consumption near both mined and unmined Climax-type deposits.

  4. High-strength chromium--molybdenum rails

    International Nuclear Information System (INIS)

    Smith, Y.E.; Sawhill, J.M. Jr.; Cias, W.W.; Eldis, G.T.

    1976-01-01

    A laboratory study was conducted with the aim of developing an as-rolled rail of over 100 ksi (689 N/mm 2 ) yield strength. A series of compositions providing both pearlitic and bainitic microstructures was evaluated. A fine pearlitic structure was developed in a 0.73 percent C -- 0.83 percent Mn -- 0.16 percent Si -- 0.75 percent Cr -- 0.21 percent Mo steel by simulating the mill cooling rate of 132-lb/yd (65.5-kg/m) rail. Two 100-ton commercial heats were made of this approximate composition and processed into 132-lb/yd (65.5-kg/m) rail. Samples tested in the laboratory ranged from 109 to 125 ksi (750 to 860 N/mm 2 ) in yield strength. The chromium-molybdenum rails also exhibited excellent fracture toughness and fatigue properties. Sections of the rail were joined by both flash-butt welding and thermite welding. The hardness peaks produced in the flash-butt welds could be reduced by applying either a postweld current or an induction heating cycle. The high-strength chromium-molybdenum rails have been in service for over eight months in curved sections of an ore railway that carries over 55 million gross long tons per year. 7 tables, 18 figs

  5. Neutron activation determination of impurities in molybdenum

    International Nuclear Information System (INIS)

    Usmanova, M.M.; Mukhamedshina, N.M.; Obraztsova, T.V.; Saidakhmedov, K.Kh.

    1984-01-01

    Instrumental neutron-activation techniques of impurity element determination in molybdenum and MoO 3 (solid and powdered samples) have been developed. When determining impurities of Na, K, Mn, Cu, W, Re molybdenum has been irradiated by thermal neutrons in reactor for 20 min, the sample mass constituted 200-300 mg, sample cooling time after irradiation - 2.5-3.5 h. It is shown that in the process of Cr, Fe, Co, Zn determination the samples should be irradiated with thermal neutrons, and in the process of Sb, Ta and Ni determination - with resonance and fast neutrons. Simultaneous determination of the elements during irradiation with neutrons with reactor spectrum is possible. When determining P and S the samples are irradiated with thermal and epithermal neutrons and β-activity of samples and comparison samples are measured using β-spectrometer with anthracene crystal. The techniques developed permit to determine impurities in Mo with a relative standard deviation 0.07-0.15 and lower boundaries of contents determined - 10 -4 - 10 -7 %

  6. Understanding the nature of the manganese hot dip phosphatizing process of steel

    Energy Technology Data Exchange (ETDEWEB)

    Alvarado M, G.; Fuentes A, J. C.; Salinas R, A.; Rodriguez V, F. J., E-mail: juan.fuentes@cinvestav.edu.mx [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Av. Industria Metalurgica No. 1062, Parque Industrial Ramos Arizpe, 25900 Saltillo, Coahuila (Mexico)

    2013-07-01

    In this work, the phosphatizing process of steel is investigated using open circuit potential and Tafel curves as well as scanning electron microscopy and energy dispersive X-ray spectroscopy. The results reveal that a ph of 2.57 in the phosphatizing solution promotes the dissociation of phosphoric acid which assist the formation of the manganese tertiary salt (Mn{sub 3}(PO{sub 4}){sub 2}), which is deposited on the substrate. It was also observed that an increase in the temperature from 25 to 90 C and the presence of HNO{sub 3} as catalysts enhances the manganese phosphatizing kinetics. On the other hand, the generation of iron phosphates and oxides is predominant at a ph of 1 and 90 C. These observations are supported by species distribution and Pourbaix thermodynamic diagrams. (Author)

  7. Understanding the nature of the manganese hot dip phosphatizing process of steel

    International Nuclear Information System (INIS)

    Alvarado M, G.; Fuentes A, J. C.; Salinas R, A.; Rodriguez V, F. J.

    2013-01-01

    In this work, the phosphatizing process of steel is investigated using open circuit potential and Tafel curves as well as scanning electron microscopy and energy dispersive X-ray spectroscopy. The results reveal that a ph of 2.57 in the phosphatizing solution promotes the dissociation of phosphoric acid which assist the formation of the manganese tertiary salt (Mn 3 (PO 4 ) 2 ), which is deposited on the substrate. It was also observed that an increase in the temperature from 25 to 90 C and the presence of HNO 3 as catalysts enhances the manganese phosphatizing kinetics. On the other hand, the generation of iron phosphates and oxides is predominant at a ph of 1 and 90 C. These observations are supported by species distribution and Pourbaix thermodynamic diagrams. (Author)

  8. Preparation of molybdenum oxide thin films by MOCVD

    International Nuclear Information System (INIS)

    Guerrero, R. Martinez; Garcia, J.R. Vargas; Santes, V.; Gomez, E.

    2007-01-01

    In this study, molybdenum oxide films were prepared in a horizontal hot-wall MOCVD apparatus using molybdenum dioxide acetylacetonate as precursor. The molybdenum precursor was synthesized from acetylacetone and molybdenum oxide powder. Thermal gravimetric (TG) and differential thermal analyses (DTA) of the precursor suggested the formation of molybdenum oxides around 430 o C (703 K). Thus, a range of deposition temperatures varying from 350 to 630 o C (623-903 K) was explored to investigate the effects on the nature of the molybdenum oxide films. X-ray diffraction (XRD) results showed that the films consisted of α-MoO 3 phase at deposition temperatures ranging from 400 to 560 o C (673-833 K). Crystalline α-MoO 3 films can be obtained from molybdenum dioxide acetylacetonate precursor, without need of a post-annealing treatment. The best crystalline quality was found in films having needle-like crystallites grown at deposition temperature of about 560 o C (833 K), which exhibit a strong (0 1 0) preferred orientation and a transparent visual appearance

  9. Preparation of molybdenum oxide thin films by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, R. Martinez [Depto. de Ingenieria Metalurgica, ESIQIE-IPN, Mexico 07300, D.F. (Mexico); Garcia, J.R. Vargas [Depto. de Ingenieria Metalurgica, ESIQIE-IPN, Mexico 07300, D.F. (Mexico)]. E-mail: rvargasga@ipn.mx; Santes, V. [CIIEMAD-IPN, Miguel Othon de Mendizabal 485, Mexico 07700, D.F. (Mexico); Gomez, E. [Instituto de Quimica-UNAM, Circuito Exterior-Ciudad Universitaria, Mexico 04510, D.F. (Mexico)

    2007-05-31

    In this study, molybdenum oxide films were prepared in a horizontal hot-wall MOCVD apparatus using molybdenum dioxide acetylacetonate as precursor. The molybdenum precursor was synthesized from acetylacetone and molybdenum oxide powder. Thermal gravimetric (TG) and differential thermal analyses (DTA) of the precursor suggested the formation of molybdenum oxides around 430 {sup o}C (703 K). Thus, a range of deposition temperatures varying from 350 to 630 {sup o}C (623-903 K) was explored to investigate the effects on the nature of the molybdenum oxide films. X-ray diffraction (XRD) results showed that the films consisted of {alpha}-MoO{sub 3} phase at deposition temperatures ranging from 400 to 560 {sup o}C (673-833 K). Crystalline {alpha}-MoO{sub 3} films can be obtained from molybdenum dioxide acetylacetonate precursor, without need of a post-annealing treatment. The best crystalline quality was found in films having needle-like crystallites grown at deposition temperature of about 560 {sup o}C (833 K), which exhibit a strong (0 1 0) preferred orientation and a transparent visual appearance.

  10. Behavior of molybdenum in mixed-oxide fuel

    International Nuclear Information System (INIS)

    Giacchetti, G.; Sari, C.

    1976-01-01

    Metallic molybdenum, Mo--Ru--Rh--Pd alloys, barium, zirconium, and tungsten were added to uranium and uranium--plutonium oxides by coprecipitation and mechanical mixture techniques. This material was treated in a thermal gradient similar to that existing in fuel during irradiation to study the behavior of molybdenum in an oxide matrix as a function of the O/(U + Pu) ratio and some added elements. Result of ceramographic and microprobe analysis shows that when the overall O/(U + Pu) ratio is less than 2, molybdenum and Mo--Ru--Rh--Pd alloy inclusions are present in the uranium--plutonium oxide matrix. If the O/(U + Pu) ratio is greater than 2, molybdenum oxidizes to MoO 2 , which is gaseous at a temperature approximately 1000 0 C. Molybdenum oxide vapor reacts with barium oxide and forms a compound that exists as a liquid phase in the columnar grain region. Molybdenum oxide also reacts with tungsten oxide (tungsten is often present as an impurity in the fuel) and forms a compound that contains approximately 40 wt percent of actinide metals. The apparent solubility of molybdenum in uranium and uranium--plutonium oxides, determined by electron microprobe, was found to be less than 250 ppM both for hypo- and hyperstoichiometric fuels

  11. Spheroidization of molybdenum powder by radio frequency thermal plasma

    Science.gov (United States)

    Liu, Xiao-ping; Wang, Kuai-she; Hu, Ping; Chen, Qiang; Volinsky, Alex A.

    2015-11-01

    To control the morphology and particle size of dense spherical molybdenum powder prepared by radio frequency (RF) plasma from irregular molybdenum powder as a precursor, plasma process parameters were optimized in this paper. The effects of the carrier gas flow rate and molybdenum powder feeding rate on the shape and size of the final products were studied. The molybdenum powder morphology was examined using high-resolution scanning electron microscopy. The powder phases were analyzed by X-ray diffraction. The tap density and apparent density of the molybdenum powder were investigated using a Hall flow meter and a Scott volumeter. The optimal process parameters for the spherical molybdenum powder preparation are 50 g/min powder feeding rate and 0.6 m3/h carrier gas rate. In addition, pure spherical molybdenum powder can be obtained from irregular powder, and the tap density is enhanced after plasma processing. The average size is reduced from 72 to 62 µm, and the tap density is increased from 2.7 to 6.2 g/cm3. Therefore, RF plasma is a promising method for the preparation of high-density and high-purity spherical powders.

  12. Leaching of manganese from electrolytic manganese residue by electro-reduction.

    Science.gov (United States)

    Shu, Jiancheng; Liu, Renlong; Liu, Zuohua; Chen, Hongliang; Tao, Changyuan

    2017-08-01

    In this study, an improved process for leaching manganese from electrolytic manganese residue (EMR) by electro-reduction was developed. The mechanisms of the electro-reduction leaching were investigated through X-ray diffraction, scanning electron microscopy, X-ray fluorescence, and Brunauer Emmett Teller. The results show that the electric field could change the surface charge distribution of EMR particles, and the high-valent manganese can be reduced by electric field. The leaching efficient of manganese reached 84.1% under the optimal leaching condition: 9.2 wt% H 2 SO 4 , current density of 25 mA/cm 2 , solid-to-liquid ratio of 1:5, and leaching time for 1 h. It is 37.9% higher than that attained without an electric field. Meanwhile, the manganese content in EMR decreased from 2.57% to 0.48%.

  13. Effect of manganese on neonatal rat: manganese concentration and enzymatic alterations in brain

    Energy Technology Data Exchange (ETDEWEB)

    Seth, P K; Husain, R; Mushtaq, M; Chandra, S V

    1977-01-01

    Suckling rats were exposed for 15 and 30 days to manganese through the milk of nursing dams receiving 15 mg MnCl/sub 2/.4H/sub 2/O/kg/day orally and after which the neurological manifestations of metal poisoning were studied. No significant differences in the growth rate, developmental landmarks and walking movements were observed between the control and manganese-exposed pups. The metal concentration was significantly increased in the brain of manganese-fed pups at 15 days and exhibited a further three-fold increase over the control, at 30 days. The accumulation of the metal in the brain of manganese-exposed nursing dams was comparatively much less. A significant decrease in succinic dehydrogenase, adenosine triphosphatase, adenosine deaminase, acetylcholine esterase and an increase in monoamine oxidase activity was observed in the brain of experimental pups and dams. The results suggest that the developing brain may also be susceptible to manganese.

  14. Development of Silicide Coating on Molybdenum Alloy Cladding

    International Nuclear Information System (INIS)

    Lim, Woojin; Ryu, Ho Jin

    2015-01-01

    The molybdenum alloy is considered as one of the accident tolerant fuel (ATF) cladding materials due to its high temperature mechanical properties. However, molybdenum has a weak oxidation resistance at elevated temperatures. To modify the oxidation resistance of molybdenum cladding, silicide coating on the cladding is considered. Molybdenum silicide layers are oxidized to SiO 2 in an oxidation atmosphere. The SiO 2 protective layer isolates the substrate from the oxidizing atmosphere. Pack cementation deposition technique is widely adopted for silicide coating for molybdenum alloys due to its simple procedure, homogeneous coating quality and chemical compatibility. In this study, the pack cementation method was conducted to develop molybdenum silicide layers on molybdenum alloys. It was found that the Mo 3 Si layer was deposited on substrate instead of MoSi 2 because of short holding time. It means that through the extension of holding time, MoSi 2 layer can be formed on molybdenum substrate to enhance the oxidation resistance of molybdenum. The accident tolerant fuel (ATF) concept is to delay the process following an accident by reducing the oxidation rate at high temperatures and to delay swelling and rupture of fuel claddings. The current research for Atf can be categorized into three groups: First, modification of existing zirconium-based alloy cladding by improving the high temperature oxidation resistance and strength. Second, replacing Zirconium based alloys with alternative metallic materials such as refractory elements with high temperature oxidation resistance and strength. Third, designing alternative fuel structures using ceramic and composite systems

  15. Crystalline silicon films sputtered on molybdenum A study of the silicon-molybdenum interface

    Energy Technology Data Exchange (ETDEWEB)

    Reinig, P.; Fenske, F.; Fuhs, W.; Schoepke, A.; Selle, B

    2003-04-15

    Polycrystalline silicon films were grown on molybdenum (Mo)-coated substrates at high deposition rate using the pulsed magnetron sputtering technique. Our study investigates the silicon-molybdenum interface of these films to elucidate stimulating mechanisms for an ordered crystalline silicon thin film growth. Both Auger electron spectroscopy and Rutherford backscattering reveal that at a substrate temperature as low as T{sub S}=450 deg. C during the deposition process intermixing of Si and Mo at the Si-Mo interface takes place leading to a compositional ratio Mo:Si of about 1:2. By Raman spectroscopy hexagonal {beta}-MoSi{sub 2} could be identified as the dominant phase in this intermixed region. The dependence of the resulting thickness of the reacted interface layer on the deposition conditions is not fully understood yet.

  16. Crystalline silicon films sputtered on molybdenum A study of the silicon-molybdenum interface

    International Nuclear Information System (INIS)

    Reinig, P.; Fenske, F.; Fuhs, W.; Schoepke, A.; Selle, B.

    2003-01-01

    Polycrystalline silicon films were grown on molybdenum (Mo)-coated substrates at high deposition rate using the pulsed magnetron sputtering technique. Our study investigates the silicon-molybdenum interface of these films to elucidate stimulating mechanisms for an ordered crystalline silicon thin film growth. Both Auger electron spectroscopy and Rutherford backscattering reveal that at a substrate temperature as low as T S =450 deg. C during the deposition process intermixing of Si and Mo at the Si-Mo interface takes place leading to a compositional ratio Mo:Si of about 1:2. By Raman spectroscopy hexagonal β-MoSi 2 could be identified as the dominant phase in this intermixed region. The dependence of the resulting thickness of the reacted interface layer on the deposition conditions is not fully understood yet

  17. Molybdenum plasma spray powder, process for producing said powder, and coating made therefrom

    International Nuclear Information System (INIS)

    Lafferty, W.D.; Cheney, R.F.; Pierce, R.H.

    1979-01-01

    Plasma spray powders of molybdenum particles containing 0.5 to 15 weight percent oxygen and obtained by reacting molybdenum particles with oxygen or oxides in a plasma, form plasma spray coatings exhibiting hardness comparable to flame sprayed coatings formed from molybdenum wire and plasma coatings of molybdenum powders. Such oxygen rich molybdenum powders may be used to form wear resistant coatings, such as for piston rings. (author)

  18. Old age and gender influence the pharmacokinetics of inhaled manganese sulfate and manganese phosphate in rats

    International Nuclear Information System (INIS)

    Dorman, David C.; McManus, Brian E.; Marshall, Marianne W.; James, R. Arden; Struve, Melanie F.

    2004-01-01

    In this study, we examined whether gender or age influences the pharmacokinetics of manganese sulfate (MnSO 4 ) or manganese phosphate (as the mineral form hureaulite). Young male and female rats and aged male rats (16 months old) were exposed 6 h day -1 for 5 days week -1 to air, MnSO 4 (at 0.01, 0.1, or 0.5 mg Mn m -3 ), or hureaulite (0.1 mg Mn m -3 ). Tissue manganese concentrations were determined in all groups at the end of the 90-day exposure and 45 days later. Tissue manganese concentrations were also determined in young male rats following 32 exposure days and 91 days after the 90-day exposure. Intravenous 54 Mn tracer studies were also performed in all groups immediately after the 90-day inhalation to assess whole-body manganese clearance rates. Gender and age did not affect manganese delivery to the striatum, a known target site for neurotoxicity in humans, but did influence manganese concentrations in other tissues. End-of-exposure olfactory bulb, lung, and blood manganese concentrations were higher in young male rats than in female or aged male rats and may reflect a portal-of-entry effect. Old male rats had higher testis but lower pancreas manganese concentrations when compared with young males. Young male and female rats exposed to MnSO 4 at 0.5 mg Mn m -3 had increased 54 Mn clearance rates when compared with air-exposed controls, while senescent males did not develop higher 54 Mn clearance rates. Data from this study should prove useful in developing dosimetry models for manganese that consider age or gender as potential sensitivity factors

  19. The extended family of hexagonal molybdenum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Hartl, Monika [Los Alamos National Laboratory; Daemen, Luke [Los Alamos National Laboratory; Lunk, J H [NON LANL; Hartl, H [NON LANL; Frisk, A T [NON LANL; Shendervich, I [NON LANL; Mauder, D [NON LANL; Feist, M [NON LANL; Eckelt, R [NON LANL

    2009-01-01

    Over the last 40 years, a large number of isostructural compounds in the system MoO{sub 3}-NH{sub 3}-H{sub 2}O have been published. The reported molecular formulae of 'hexagonal molybdenum oxide' (HEMO) varied from MoO{sub 3}, MoO{sub 3} {center_dot} 0.33NH{sub 3}, MoO{sub 3} {center_dot} nH{sub 2}O (0.09 {le} n {le} 0.69) to MoO{sub 3} {center_dot} mNH{sub 3} {center_dot} nH{sub 2}O (0.09 {le} m {le} 0.20; 0.18 {le} n {le} 0.60). Samples, prepared by the acidification route, were investigated using thermal analysis coupled on-line to a mass spectrometer for evolved gas analysis; X-ray powder diffraction; Fourier Transform Infrared, Raman and Magic-Angle-Spinning {sup 1}H-NMR spectroscopy; Incoherent Inelastic Neutron Scattering. The X-ray study of a selected monocrystal confirmed the presence of the well-known framework of edge-sharing MoO{sub 6} octahedra: Space group P6{sub 3}/m, a = 10.527(1), c =3.7245(7) {angstrom}, {gamma} = 120{sup o}. The structure of the synthesized samples can best be described by the structural formula (NH{sub 4})[Mo{sub x}{open_square}{sub 1/2+p/2}(O{sub 3x + 1/2-p/2})(OH){sub p}] {center_dot} yH{sub 2}O (x 5.9-7.1; p {approx} 0.1; y = 1.2-2.6), which is consistent with the existence of one vacancy for 12-15 molybdenum sites. The 'chimie douce' reaction of MoO{sub 3} {center_dot} 0.155NH{sub 3} {center_dot} 0.440H{sub 2}O with a 1:1 mixture of NO/NO{sub 2} at 100 C resulted in the synthesis of MoO{sub 3} {center_dot} 0.539H{sub 2}O. Tailored nano-sized molybdenum powders can be produced using HEMO as precursor.

  20. Low cycle fatigue behavior of titanium carbide coated molybdenum

    International Nuclear Information System (INIS)

    Nishi, Hiroshi; Oku, Tatsuo; Kodaira, Tsuneo; Kikuyama, Toshihiko

    1985-09-01

    Sintered molybdenum coated by TiC is used for the first wall such as a troidal fixed limiter and a magnetic limiter plate in JT-60, that is being operated at JAERI presently. This report describes the low cycle fatigue behavior of sintered molybdenum and the influence of TiC coating on fatigue strength. The low cycle fatigue test was conducted at room temperature and 500 0 C. The test results was also analyzed by fractographic observation, metallography and element analysis using EPMA. The low cycle fatigue strength of the molybdenum coated by TiC at 500 0 C is decreased compared with the one at room temperature. (author)

  1. Loss of hfe function reverses impaired recognition memory caused by olfactory manganese exposure in mice.

    Science.gov (United States)

    Ye, Qi; Kim, Jonghan

    2015-03-01

    Excessive manganese (Mn) in the brain promotes a variety of abnormal behaviors, including memory deficits, decreased motor skills and psychotic behavior resembling Parkinson's disease. Hereditary hemochromatosis (HH) is a prevalent genetic iron overload disorder worldwide. Dysfunction in HFE gene is the major cause of HH. Our previous study has demonstrated that olfactory Mn uptake is altered by HFE deficiency, suggesting that loss of HFE function could alter manganese-associated neurotoxicity. To test this hypothesis, Hfe-knockout (Hfe (-/-)) and wild-type (Hfe (+/+)) mice mice were intranasally-instilled with manganese chloride (MnCl2 5 mg/kg) or water daily for 3 weeks and examined for memory function. Olfactory Mn diminished both short-term recognition and spatial memory in Hfe (+/+) mice, as examined by novel object recognition task and Barnes maze test, respectively. Interestingly, Hfe (-/-) mice did not show impaired recognition memory caused by Mn exposure, suggesting a potential protective effect of Hfe deficiency against Mn-induced memory deficits. Since many of the neurotoxic effects of manganese are thought to result from increased oxidative stress, we quantified activities of anti-oxidant enzymes in the prefrontal cortex (PFC). Mn instillation decreased superoxide dismutase 1 (SOD1) activity in Hfe (+/+) mice, but not in Hfe (-/-) mice. In addition, Hfe deficiency up-regulated SOD1 and glutathione peroxidase activities. These results suggest a beneficial role of Hfe deficiency in attenuating Mn-induced oxidative stress in the PFC. Furthermore, Mn exposure reduced nicotinic acetylcholine receptor levels in the PFC, indicating that blunted acetylcholine signaling could contribute to impaired memory associated with intranasal manganese. Together, our model suggests that disrupted cholinergic system in the brain is involved in airborne Mn-induced memory deficits and loss of HFE function could in part prevent memory loss via a potential up-regulation of

  2. Effect of manganese and zinc on the growth of Anacystis nidulans

    Energy Technology Data Exchange (ETDEWEB)

    Lee, L.H.; Lustigman, B.; Dandorf, D. (Montclair State College, Upper Montclair, NJ (United States))

    1994-07-01

    Anacystis nidulans is a unicellular member of the cyanobacteria, one of the largest groups of the Kingdom Monera. It is similar to other bacteria in the structure and chemistry of the cell wall, and its cell division and genetic recombination. Photoautotrophy is the main mode of nutrition and the photosynthetic apparatus is similar to that of other cyanobacteria. Cyanobacteria are excellent organisms to serve as environmental pollution indicators for the investigation of a wide variety of biological problems. There have been several studies on the effects of heavy metals on A. nidulans. Some of these elements, such as manganese, are known to be essential nutrients for cyanobacteria. Others, such as cadmium, are not known to be necessary for normal growth and metabolism. Large amounts of either essential or non-essential elements can be toxic. Manganese and zinc are essential elements for all living organisms. Manganese is a cofactor for a number of different enzymatic reactions particularly those involved in phosphorylation. Iron deficiency induced by a number of metals, cobalt and manganese in particular, inhibit chlorophyll biosynthesis. Zinc deficiency affects early mitotic events and the cells are large and aberrant in appearance. Light is essential for cells to take in zinc. As an industrial contaminant, zinc has been found to block photosynthesis by causing structural damage to the photosynthetic apparatus. In the presence of various pH ranges, high zinc concentrations can be associated with low pH. It has been indicated that pH value and EDTA (Ethylene Diamine Tetraacetic Acid) have an influence on the effect of some metals. The purpose of this study was to determine the effect of manganese and zinc on the growth of Anacystis nidulans, with and without EDTA.

  3. Cast irons

    CERN Document Server

    1996-01-01

    Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

  4. Use of ion exchange during preparation of raw materials for production of molybdenum and tungsten of high purify

    International Nuclear Information System (INIS)

    Blokhin, A.A.; Rumyantsev, V.K.; Taushkanov, V.P.; Maksimkov, S.M.; Majorov, D.Yu.; Pak, V.I.

    1988-01-01

    The data on the application of selective ionites for the steep purification of ammonium molybdate and tungstate solutions, are given. It is shown that to purify molybdenum and ammonium tungstate solutions from the impuerities of alkali earth and two- and threevalent transition metals, iminodiacetate ampholites of the ANKB-35 type are the most effective sorbents. To purify from phosphorus, silicon and arsenic impurities composition ionites on the base of hydrated oxides of multivalent metals introduced in the granules of porous cationites should be used. To extract phosphorus, silicon, arsenic impurities from ammonium molybdate and tungstate solutions and tungsten from ammonium molybdate solutions the method of their coprecipitation with iron (3) hydroxide can also be used. The best results on the purification of ammonium molybdate from tungstate provides for the application of structural organomineral ionites as well as weak-basicity anionites of the AN-31 type and its different modifications containing hydroxyl groups along with aminogroups. To purity ammonium tungstate solutions from molybdate a method is developed which transforms molybdenum in the form of thiocomplexes and the following selective sorption by strong-basicity anionites. The data on the quality of molybdenum monocrystals which are taken from the raw material purified using ionites, are given

  5. Effect of molybdenum and chromium additions on the mechanical properties of Fe3Al-based alloys

    International Nuclear Information System (INIS)

    Sun Yangshan; Xue Feng; Mei Jianping; Yu Xingquan; Zhang Lining

    1995-01-01

    Iron aluminides based on Fe 3 Al offer excellent oxidation and sulfidation resistance, with lower material cost and density than stainless steels. However, their potential use as structural material has been hindered by limited ductility and a sharp drop in strength above 600 C. Recent development efforts have indicated that adequate engineering ductility of 10--20% and tensile yield strength of as high as 500 MPa can be achieved through control of composition and microstructure. These improved tensile properties make Fe 3 Al-based alloys more competitive against conventional austenic and ferritic steels. The improvement of high temperature mechanical properties has been achieved mainly by alloying processes. Molybdenum has been found to be one of the most important alloying elements for strengthening Fe 3 Al-based alloys at high temperatures. However, the RT(room temperature) ductility decreases with the increase of a molybdenum addition. On the other hand, a chromium addition to Fe 3 Al-based alloys is very efficient for improving RT ductility but not beneficial to yield strength at temperatures to 800 C. The purpose of the present paper is to report the effects of combined additions of molybdenum and chromium on mechanical properties at ambient temperature and high temperature of 600 C

  6. Electron emission from molybdenum under ion bombardment

    International Nuclear Information System (INIS)

    Ferron, J.; Alonso, E.V.; Baragiola, R.A.; Oliva-Florio, A.

    1981-01-01

    Measurements are reported of electron emission yields of clean molybdenum surfaces under bombardment with H + , H 2 + , D + , D 2 + , He + , N + , N 2 + , O + , O 2 + , Ne + , Ar + , Kr + and Xe + in the wide energy range 0.7-60.2 keV. The clean surfaces were produced by inert gas sputtering under ultrahigh vacuum. The results are compared with those predicted by a core-level excitation model. The disagreement found when using correct values for the energy levels of Mo is traced to wrong assumptions in the model. A substantially improved agreement with experiment is obtained using a model in which electron emission results from the excitation of valence electrons from the target by the projectiles and fast recoiling target atoms. (author)

  7. Molybdenum-base cermet fuel development

    International Nuclear Information System (INIS)

    Gurwell, W.E.; Moss, R.W.; Pilger, J.P.; White, G.D.

    1987-07-01

    Development of a multimegawatt (MMW) space nuclear power system requires identification and resolution of several technical feasibility issues before selecting one or more promising system concepts. Demonstration of reactor fuel fabrication technology is required for cermet-fueled reactor concepts. MMW reactor fuel development activity at Pacific Northwest Laboratory (PNL) is focused on producing a molybdenum-matrix uranium-nitride (UN) fueled cermet. This cermet is to have a high matrix density (≥95%) for high strength and high thermal conductance coupled with a high particle (UN) porosity (∼25%) for retention of released fission gas at high burnup. Fabrication process development involves the use of porous TiN microspheres as surrogate fuel material until porous UN microspheres become available. Process development has been conducted in the areas of microsphere synthesis, particle sealing/coating, and high-energy-rate forming (HERF) and vacuum hot press consolidation techniques. This paper summarizes the status of these activities

  8. Dithiolato complexes of molybdenum and tungsten

    International Nuclear Information System (INIS)

    Nieuwpoort, A.

    1975-01-01

    The synthesis of eight-coordinated and six-coordinated tungsten and molybdenum complexes with dithioligands is described. Molecular and crystal structures are determined and bond angles, bond lengths and structural parameters tabulated. Infrared spectra of dithiocarbamato complexes are discussed more extensively. Redox reactions are studied by voltammetry and electron transfer properties derived. Properties of the d electrons of the metal ion are interpreted in the ligand field model with data from electronic and e.s.r. spectra and magnetic susceptibilities. The result of molecular orbital calculations with the extended Hueckel-LCAO method are presented for eight-coordinated d 1 and d 2 systems, the six-coordinated complexes, and the free ligands

  9. Scattering of fast neutrons from elemental molybdenum

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.

    1982-11-01

    Differential broad-resolution neutron-scattering cross sections of elemental molybdenum were measured at 10 to 20 scattering angles distributed between 20 and 160 degrees and at incident-neutron energy intervals of approx. = 50 to 200 keV from 1.5 to 4.0 MeV. Elastically-scattered neutrons were fully resolved from inelastic events. Lumped-level inelastic-neutron-scattering cross sections were determined corresponding to observed excitation energies of; 789 +- 23, 195 +- 23, 1500 +- 34, 1617 +- 12, 1787, 1874, 1991, 2063 +- 24, 2296, 2569 and 2802 keV. An optical-statistical model was deduced from the measured elastic-scattering results. The experimental values were compared with the respective quantities given in ENDF/B-V

  10. Thermal ripples in model molybdenum disulfide monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Remsing, Richard C.; Klein, Michael L. [Institute for Computational Molecular Science, Center for the Computational, Design of Functional Layered Materials, and Department of Chemistry, Temple University, 1925 N. 12th St., 19122, Philadelphia, PA (United States); Waghmare, Umesh V. [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, 560 064, Jakkur, Bangalore (India)

    2017-01-15

    Molybdenum disulfide (MoS{sub 2}) monolayers have the potential to revolutionize nanotechnology. To reach this potential, it will be necessary to understand the behavior of this two-dimensional (2D) material on large length scales and under thermal conditions. Herein, we use molecular dynamics (MD) simulations to investigate the nature of the rippling induced by thermal fluctuations in monolayers of the 2H and 1T phases of MoS{sub 2}. The 1T phase is found to be more rigid than the 2H phase. Both monolayer phases are predicted to follow long wavelength scaling behavior typical of systems with anharmonic coupling between vibrational modes as predicted by classic theories of membrane-like systems. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Ion adsorption properties of molybdenum (II) bromide

    International Nuclear Information System (INIS)

    Ganzerli-Valentini, M.T.; Meloni, S.; Caramella-Crespi, V.; Borroni, P.A.

    1976-01-01

    The adsorption of about 50 ions on molybdenum dibromide, (Mo 6 Br 8 )Br 4 .2H 2 O in nitric acid was investigated. The behaviour of the investigated elements on MDB in nitric acid, in the concentration range 10 -2 -8M is presented, where the distribution coefficients are given against the HNO 3 molarity. In some cases the elements were investigated in different oxidation states. Most of the elements are not adsorbed or poorly adsorbed, among these the stable anions, thus indicating that bromide ions substitution with other anions is not competitive. The preparation of the adsorber and its characterization is presented and discussed. Adsorption mechanism studies were carried out for some noble metals and chromium. Sorption cannot be ascribed to ion exchange mechanism but to formation of insoluble species, and to settlement of few ions into surface sorption sites or into a limited number of cavitites in the cluster crystal structure of the adsorber. (T.G.)

  12. Radio frequency induction plasma spraying of molybdenum

    International Nuclear Information System (INIS)

    Jiang Xianliang

    2003-01-01

    Radio frequency (RF) induction plasma was used to make free-standing deposition of molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were investigated. The effect of process parameters such as plasma power, chamber pressure, and spray distance on the phenomena mentioned above was studied. Scanning electron microscopy (SEM) was used to analyze the plasma-processed powder, splats formed, and deposits obtained. Experimental results show that less Mo particles are spheroidized when compared to the number of spheroidized tungsten (W) particles at the same powder feed rate under the same plasma spray condition. Molten Mo particles can be sufficiently flattened on substrate. The influence of the process parameters on the flattening behavior is not significant. Mo deposit is not as dense as W deposit, due to the splash and low impact of molten Mo particles. Oxidation of the Mo powder with a large particle size is not evident under the low pressure plasma spray

  13. Microplastic relaxations of single and polycrystalline molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Pichl, W.; Weiss, B. [Wien Univ. (Austria). Inst. fuer Materialphysik; Chen, D.L.

    1998-05-01

    The microplasticity of high-purity molybdenum single crystals and of Mo polycrystals of technical purity has been investigated by relaxation step tests in uniaxial compression. A new model for the evaluation of relaxation tests in the microplastic range of b.c.c metals is presented which takes into account the decrease of the mobile dislocation density due to exhaustion of non-screw dislocations. The model allows an independent determination of the activation volume and of the microstructure parameters controlling dislocation exhaustion. The results indicate that in the high-purity single crystals the deformation rate is controlled by interactions of non-screw dislocations with the grown-in network. In the polycrystals additional interactions with impurity atoms seem to occur. In the single crystals the activity and subsequent exhaustion of two different glide systems was observed, followed by a gradual onset of screw dislocation motion. (orig.) 26 refs.

  14. The molybdenum-technetium solar neutrino experiment

    International Nuclear Information System (INIS)

    Schroeder, N.C.; Wolfsberg, K.; Rokop, D.J.

    1991-01-01

    The authors are attempting to measure the time-averaged 8 B solar-neutrino flux over 10 Myr by measuring 98 Tc produced through the 98 Mo( nu ,e - ) reaction in a deeply buried molybdenum deposit. This will test the prediction of periodic mixing of the Sun's core over long time intervals. To separate technetium from 10,000-ton quantities of Henderson ore, the authors have taken advantage of the commercial processing of molybdenite. Technetium, volatilized during roasting of molybdenite to MoO 3 , was scrubbed from the gas stream and collected on anion exchange columns. After sample reduction and chemical separation and purification they measured technetium, as TcO 4 - , using negative thermal ionization mass spectrometry. Measurement of 99 Tc in spiked and 98 Tc in unspiked fractions from one sample gives an apparent solar neutrino production rate of 95.8 SNU. However, roaster memory probably invalidates this result

  15. Measured oscillator strengths in singly ionized molybdenum

    Science.gov (United States)

    Mayo-García, R.; Aragón, C.; Aguilera, J. A.; Ortiz, M.

    2015-11-01

    In this article, 112 oscillator strengths from Mo II have been measured, 79 of which for the first time. The radiative parameters have been obtained by laser-induced breakdown spectroscopy (LIBS). The plasma is produced from a fused glass sample prepared from molybdenum oxide with a Mo atomic concentration of 0.1%. The plasma evolved in air at atmospheric pressure, and measurements were carried out with the following plasma parameters: an electron density of (2.5+/- 0.1)\\cdot {10}17 cm-3 and an electron temperature of 14,400+/- 200 K. In these conditions, a local thermodynamic equilibrium environment and an optically thin plasma were confirmed for the measurements. The relative intensities were placed on an absolute scale by combining branching fractions with the measured lifetimes and by comparing well-known lines using the plasma temperature. Comparisons were made to previously obtained experimental and theoretical values wherever possible.

  16. Principles for prevention of toxic effects from metals

    DEFF Research Database (Denmark)

    Landrigan, Philip J.; Kotelchuk, David; Grandjean, Philippe

    2007-01-01

    of the Toxic Effects of Metals Aluminum Antimony Arsenic Barium Beryllium Bismuth Cadmium Chromium Cobalt Copper Gallium and Semiconductor Compounds Germanium Indium Iron Lead Manganese Mercury Molybdenum Nickel Palladium Platinum Selenium Silver Tellurium Thallium Tin Titanium Tungsten Uranium Vanadium Zinc...

  17. African leafy vegetables consumed by households in the Limpopo ...

    African Journals Online (AJOL)

    pureed green leafy vegetables was shown to have a beneficial effect ..... was regarded as very nutritious; “having it is just like having meat”. ...... chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc.

  18. ORIGINAL ARTICLES

    African Journals Online (AJOL)

    deficiency in children and the relative risks of associated health problems, applied to revised burden of disease estimates for. South Africa in the ..... Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum,. Nickel ...

  19. Photogeochemical reactions of manganese under anoxic conditions

    Science.gov (United States)

    Liu, W.; Yee, N.; Piotrowiak, P.; Falkowski, P. G.

    2017-12-01

    Photogeochemistry describes reactions involving light and naturally occurring chemical species. These reactions often involve a photo-induced electron transfer that does not occur in the absence of light. Although photogeochemical reactions have been known for decades, they are often ignored in geochemical models. In particular, reactions caused by UV radiation during an ozone free early Earth could have influenced the available oxidation states of manganese. Manganese is one of the most abundant transition metals in the crust and is important in both biology and geology. For example, the presence of manganese (VI) oxides in the geologic record has been used as a proxy for oxygenic photosynthesis; however, we suggest that the high oxidation state of Mn can be produced abiotically by photochemical reactions. Aqueous solutions of manganese (II) as well as suspensions of rhodochrosite (MnCO3) were irradiated under anoxic condition using a 450 W mercury lamp and custom built quartz reaction vessels. The photoreaction of the homogeneous solution of Mn(II) produced H2 gas and akhtenskite (ɛ-MnO2) as the solid product . This product is different than the previously identified birnessite. The irradiation of rhodochrosite suspensions also produced H2 gas and resulted in both a spectral shift as well as morphology changes of the mineral particles in the SEM images. These reactions offer alternative, abiotic pathways for the formation of manganese oxides.

  20. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... risk for iron-deficiency anemia, including: Vegetarian or vegan eating patterns. Not eating enough iron-rich foods, ... iron-fortified foods that have iron added. Vegetarian diets can provide enough iron if you choose nonmeat ...

  1. Manganese and acute paranoid psychosis: a case report

    NARCIS (Netherlands)

    Verhoeven, W.M.A.; Egger, J.I.M.; Kuijpers, H.J.H.

    2011-01-01

    Introduction Manganese regulates many enzymes and is essential for normal development and body function. Chronic manganese intoxication has an insidious and progressive course and usually starts with complaints of headache, fatigue, sleep disturbances, irritability and emotional instability. Later,

  2. Manganese and acute paranoid psychosis: A case report

    NARCIS (Netherlands)

    W.M.A. Verhoeven (Wim); J.I.M. Egger (Jos); H.J. Kuijpers (Harold)

    2011-01-01

    textabstractIntroduction: Manganese regulates many enzymes and is essential for normal development and body function. Chronic manganese intoxication has an insidious and progressive course and usually starts with complaints of headache, fatigue, sleep disturbances, irritability and emotional

  3. Investigation into iron moessbauer atom state in a deformed iron-manganese alloys

    International Nuclear Information System (INIS)

    Mints, R.I.; Semenkin, V.A.; Shevchenko, Yu.A.

    1977-01-01

    A plastically deformed Fe + 12 at. %. Mn alloy was investigated by the method of nuclear gamma-resonance on Fe 57 nuclei. The specimens were deformed by 5 to 57 %. The obtained nuclear gamma-resonance spectra, which are a superposition of the paramagnetic single line (ν-phase) and the Zeeman splitting line (α-phase), were statistically processed with the aid of a computer. The behaviour of the values of Moessbauer parameters possessing a least dispersion, such as isomer chemical shift, quadrupolar reaction constant, effectiveness of magnetic field and of area of the nuclear gamma-resonance spectrum, points to their connection with the degree of the deformation disintegration of the initial solid solution

  4. Molybdenum-UO2 cermet irradiation at 1145 K.

    Science.gov (United States)

    Mcdonald, G.

    1971-01-01

    Two molybdenum-uranium dioxide cermet fuel pins with molybdenum clad were fission-heated in a forced-convection helium coolant for sufficient time to achieve 5.3% burnup. The cermet core contained 20 wt % of 93.2% enriched uranium dioxide. The results were as follows: there was no visible change in the appearance of the molybdenum clad during irradiation; the maximum increase in diameter of the fuel pins was 0.8%; there was no migration of uranium dioxide along grain boundaries and no evident interaction between molybdenum and uranium dioxide; and, finally, approximately 12% of the fission gas formed was released from the cermet core into the gas plenum.

  5. Recovering and recycling uranium used for production of molybdenum-99

    Science.gov (United States)

    Reilly, Sean Douglas; May, Iain; Copping, Roy; Dale, Gregory Edward

    2017-12-12

    A processes for recycling uranium that has been used for the production of molybdenum-99 involves irradiating a solution of uranium suitable for forming fission products including molybdenum-99, conditioning the irradiated solution to one suitable for inducing the formation of crystals of uranyl nitrate hydrates, then forming the crystals and a supernatant and then separating the crystals from the supernatant, thus using the crystals as a source of uranium for recycle. Molybdenum-99 is recovered from the supernatant using an adsorbent such as alumina. Another process involves irradiation of a solid target comprising uranium, forming an acidic solution from the irradiated target suitable for inducing the formation of crystals of uranyl nitrate hydrates, then forming the crystals and a supernatant and then separating the crystals from the supernatant, thus using the crystals as a source of uranium for recycle. Molybdenum-99 is recovered from the supernatant using an adsorbent such as alumina.

  6. Sintering of cermets on the base of corundum and molybdenum

    International Nuclear Information System (INIS)

    Fedotov, A.V.

    1987-01-01

    Liquid-phase sintering of cermets has been studied to develop rational technology allowing to produce a dense material at lower temperatures. Molybdenum of the MPCh mark with the specific surface ranged from 1900 to 4000 cm 2 /g and the corundum powder of the VK-94-1 mark with the specific surface of 6000 cm 2 /g containing upto 10% of the glass-phase have been used as initial materials. It is shown that application of the VK-94-1 ceramics powder for molybdenum content cermets allows to decrease the temperature of dense material production (∼ upto 100 deg C). To produce dense materials, it is necessary to restrict the initial porosity of compaction and to correspond it to the sintering conditions. The increase of molybdenum dispersion allows to produce material with the more homogeneous structure, higher density and strength. Molybdenum presence decreases recrystallization of corundum crystals and causes structure production resistant to high-temperature heating

  7. Physical chemical quality control of the molybdenum technetium generator

    International Nuclear Information System (INIS)

    Olive, E.; Cruz, J.; Isaac, M.; Gamboa, R.; D'Alessandro, K.; Desdin, L.F.

    1995-01-01

    Comparative operational procedure imported molybdenum technetium generators have been made. Procedures for determination of chemical, radiochemical and radionuclidic purities that may be applied in Hospital's laboratories and in the quality control of generators production are developed

  8. Electroplating and stripping copper on molybdenum and niobium

    Science.gov (United States)

    Power, J. L.

    1978-01-01

    Molybdenum and niobium are often electroplated and subsequently stripped of copper. Since general standard plating techniques produce poor quality coatings, general procedures have been optimized and specified to give good results.

  9. Alkaline elution of uranium and molybdenum and their recovery

    International Nuclear Information System (INIS)

    Song Wenlan; Wu Peisheng; Zhao Pinzhi; Tao Dening; Xie Chaoyan

    1987-01-01

    The uranium and molybdenum can be simultaneously eluted by using eluant (NH 4 ) 2 CO 3 + (NH 4 ) 2 SO 4 from resin loaded uranium and molybdenum. The ADU is precipitated from eluant by volatilization of ammonia. The molybdenum is extracted by TFA-TBP-kerosene from the filtrate at pH 3.0-3.2 with molybdenum extraction > 98%. Uranium is nearly not extracted. The precipitation of Mo is reached by sulphuric acid after stripping and the ammonium multimolybdate is obtained. This process can give the total recovery more than 99% for U and 90% for Mo. Because of the use of sulphate salt system, the hazard of NO 3 - can be avoided

  10. Mechanical properties of molybdenum coated with titanium carbide film

    International Nuclear Information System (INIS)

    Shikama, T.; Shinno, H.; Fukutomi, M.; Fujitsuka, M.; Okada, M.

    1983-01-01

    TiC-coated molybdenum is mechanically tensile tested. The 6 μm thick TiC-coated molybdenum has a higher 0.2% proof strength with a slight decrease in uniform and rupture elongation than the uncoated one. This strengthening effect of the TiC coating can be explained by the constrained effect of the high strength TiC film. The 1.2 μm thick TiC-coated molybdenum starts its plastic deformation at a lower stress than the uncoated one. Also, the coating makes the stress-strain curve more smooth. These effects are attributed to the surface effect, namely, that the interface between the molybdenum substrate and the strong and brittle TiC film acts as a strong dislocation source. The compressive stress in the TiC film will also help the start of plastic deformation at lower external stresses. (author)

  11. Molybdenum-A Key Component of Metal Alloys

    Science.gov (United States)

    Kropschot, S.J.

    2010-01-01

    Molybdenum, whose chemical symbol is Mo, was first recognized as an element in 1778. Until that time, the mineral molybdenite-the most important source of molybdenum-was believed to be a lead mineral because of its metallic gray color, greasy feel, and softness. In the late 19th century, French metallurgists discovered that molybdenum, when alloyed (mixed) with steel in small quantities, creates a substance that is remarkably tougher than steel alone and is highly resistant to heat. The alloy was found to be ideal for making tools and armor plate. Today, the most common use of molybdenum is as an alloying agent in stainless steel, alloy steels, and superalloys to enhance hardness, strength, and resistance to corrosion.

  12. Change of mechanical properties of molybdenum after chemical heat treatment

    International Nuclear Information System (INIS)

    Skuratov, L.P.; Yatsimirskij, V.K.; Kirillova, N.V.

    1987-01-01

    Gaseous media (argon, ammonia, nitrogen-hydrogen-ammonia mixture) are studied for their effect on mechanical characteristics of molybdenum at temperatures up to 1000 deg C. It is established that the highest hardening occurs when molybdenum is esposed in the nitrogen-hydrogen medium, while the highest lost of strength takes place in the ammonia medium. An increase of the ammonia concentration in nitrogen-hydrogen-ammonia mixture promotes regular increasing of the deformation rate. With ammonia concentration of 33.3% the gaseous mixture acts the same as pure ammonia. Change of physical-and-mechanical properties of molybdenum under the action of nitrogen-containing gaseous media is associated with formation of molybdenum compounds with nitrogen. During nitriding in ammonia an internal (volume) nitriding proceeds while in the medium of nitrogen-hydrogen mixture surface nitride layers form

  13. Dinitrogen binding and cleavage by multinuclear iron complexes.

    Science.gov (United States)

    McWilliams, Sean F; Holland, Patrick L

    2015-07-21

    The iron-molybdenum cofactor of nitrogenase has unprecedented coordination chemistry, including a high-spin iron cluster called the iron-molybdenum cofactor (FeMoco). Thus, understanding the mechanism of nitrogenase challenges coordination chemists to understand the fundamental N2 chemistry of high-spin iron sites. This Account summarizes a series of studies in which we have synthesized a number of new compounds with multiple iron atoms, characterized them using crystallography and spectroscopy, and studied their reactions in detail. These studies show that formally iron(I) and iron(0) complexes with three- and four-coordinate metal atoms have the ability to weaken and break the triple bond of N2. These reactions occur at or below room temperature, indicating that they are kinetically facile. This in turn implies that iron sites in the FeMoco are chemically reasonable locations for N2 binding and reduction. The careful evaluation of these compounds and their reaction pathways has taught important lessons about what characteristics make iron more effective for N2 activation. Cooperation of two iron atoms can lengthen and weaken the N-N bond, while three working together enables iron atoms to completely cleave the N-N bond to nitrides. Alkali metals (typically introduced into the reaction as part of the reducing agent) are thermodynamically useful because the alkali metal cations stabilize highly reduced complexes, pull electron density into the N2 unit, and make reduced nitride products more stable. Alkali metals can also play a kinetic role, because cation-π interactions with the supporting ligands can hold iron atoms near enough to one another to facilitate the cooperation of multiple iron atoms. Many of these principles may also be relevant to the iron-catalyzed Haber-Bosch process, at which collections of iron atoms (often promoted by the addition of alkali metals) break the N-N bond of N2. The results of these studies teach more general lessons as well. They

  14. Criticality of iron and its principal alloying elements.

    Science.gov (United States)

    Nuss, Philip; Harper, E M; Nassar, N T; Reck, Barbara K; Graedel, T E

    2014-04-01

    Because modern technology depends on reliable supplies of a wide variety of materials and because of increasing concern about those supplies, a comprehensive methodology was created to quantify the degree of criticality of the metals of the periodic table. In this paper, we apply this methodology to iron and several of its main alloying elements (i.e., vanadium, chromium, manganese, and niobium). These elements represent the basic metals of any industrial society and are vital for national security and economic well-being. Assessments relating to the dimensions of criticality - supply risk, vulnerability to supply restriction, and environmental implications - for 2008 are made on the global level and for the United States. Evaluations of each of the multiple indicators are presented, with aggregate results plotted in "criticality space", together with Monte Carlo simulation-derived "uncertainty cloud" estimates. Iron has the lowest supply risk, primarily because of its widespread geological occurrence. Vanadium displays the highest cradle-to-gate environmental implications, followed by niobium, chromium, manganese, and iron. Chromium and manganese, both essential in steel making, display the highest vulnerability to supply restriction, largely because substitution or substitution at equal performance is not possible for all end-uses. From a comprehensive perspective, we regard the overall criticality as low for iron and modest for the alloying elements we evaluated.

  15. Silver manganese oxide electrodes for lithium batteries

    Science.gov (United States)

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2006-05-09

    This invention relates to electrodes for non-aqueous lithium cells and batteries with silver manganese oxide positive electrodes, denoted AgxMnOy, in which x and y are such that the manganese ions in the charged or partially charged electrodes cells have an average oxidation state greater than 3.5. The silver manganese oxide electrodes optionally contain silver powder and/or silver foil to assist in current collection at the electrodes and to improve the power capability of the cells or batteries. The invention relates also to a method for preparing AgxMnOy electrodes by decomposition of a permanganate salt, such as AgMnO4, or by the decomposition of KMnO4 or LiMnO4 in the presence of a silver salt.

  16. Hydrotreatment activities of supported molybdenum nitrides and carbides

    Energy Technology Data Exchange (ETDEWEB)

    Dolce, G.M.; Savage, P.E.; Thompson, L.T. [University of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering

    1997-05-01

    The growing need for alternative sources of transportation fuels encourages the development of new hydrotreatment catalysts. These catalysts must be active and more hydrogen efficient than the current commercial hydrotreatment catalysts. Molybdenum nitrides and carbides are attractive candidate materials possessing properties that are comparable or superior to those of commercial sulfide catalysts. This research investigated the catalytic properties of {gamma}-Al{sub 2}O{sub 3}-supported molybdenum nitrides and carbides. These catalysts were synthesized via temperature-programmed reaction of supported molybdenum oxides with ammonia or methane/hydrogen mixtures. Phase constituents and compositions were determined by X-ray diffraction, elemental analysis, and neutral activation analysis. Oxygen chemisorption was used to probe the surface properties of the catalysts. Specific activities of the molybdenum nitrides and carbides were competitive with those of a commercial sulfide catalyst for hydrodenitrogenation (HDN), hydrodesulfurization (HDS), and hydrodeoxygenation (HDO). For HDN and HDS, the catalytic activity on a molybdenum basis was a strong inverse function of the molybdenum loading. Product distributions of the HDN, HDO and HDS of a variety of heteroatom compounds indicated that several of the nitrides and carbides were more hydrogen efficient than the sulfide catalyst. 35 refs., 8 figs., 7 tabs.

  17. High Manganese Tolerance and Biooxidation Ability of Serratia marcescens Isolated from Manganese Mine Water in Minas Gerais, Brazil

    Directory of Open Access Journals (Sweden)

    Natália R. Barboza

    2017-10-01

    Full Text Available Manganese is an important metal for the maintenance of several biological functions, but it can be toxic in high concentrations. One of the main forms of human exposure to metals, such as manganese (Mn, is the consumption of solar salt contaminated. Mn-tolerant bacteria could be used to decrease the concentration of this metal from contaminated sites through safer environmental-friendly alternative technology in the future. Therefore, this study was undertaken to isolate and identify Mn resistant bacteria from water samples collected from a Mn mine in the Iron Quadrangle region (Minas Gerais, Brazil. Two bacterial isolates were identified as Serratia marcescens based on morphological, biochemical, 16S rDNA gene sequencing and phylogeny analysis. Maximum resistance of the selected isolates against increasing concentrations of Mn(II, up to 1200 mg L-1 was determined in solid media. A batch assay was developed to analyze and quantify the Mn removal capacities of the isolates. Biological Mn removal capacities of over 55% were detected for both isolates. Whereas that mechanism like biosorption, precipitation and oxidation could be explaining the Mn removal, we seek to give an insight into some of the molecular mechanisms adopted by S. marcescens isolates. For this purpose, the following approaches were adopted: leucoberbelin blue I assay, Mn(II oxidation by cell-free filtrate and electron microscopy and energy-dispersive X-ray spectroscopy analyses. Overall, these results indicate that S. marcescens promotes Mn removal in an indirect mechanism by the formation of Mn oxides precipitates around the cells, which should be further explored for potential biotechnological applications for water recycling both in hydrometallurgical and mineral processing operations.

  18. Manganese phospate physical chemistry and surface properties

    International Nuclear Information System (INIS)

    Najera R, N.; Romero G, E. T.

    2008-01-01

    This paper presents the methodology for the manganese phosphate (III) synthesis (MnP0 4 H 2 0) from manganese chloride. The physicochemical characterization was carried out by: X-ray diffraction, scanning electron microscopy, infrared analysis and thermal gravimetric analysis. The surface characterization is obtained through the determination of surface area, point of zero charge and kinetics of moisture. As a phosphate compound of a metal with low oxidation state is a promising compound for removal pollutants from water and soil, can be used for the potential construction of containment barriers for radioactive wastes. (Author)

  19. IRON DOME

    African Journals Online (AJOL)

    6 Israeli Navy 'First Arm of the Sea: The Successful Interception of the Iron Dome Rocket .... sky to destroy them whilst in flight to minimise civilian casualties. ..... Including The Moon and Celestial Bodies.53 Demeyere further emphasises the.

  20. Iron overdose

    Science.gov (United States)

    ... tracing) X-ray to detect and track iron tablets through the stomach and intestines Treatment may include: ... BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: Elsevier; 2016: ...