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1

Effect of iron upon cadmium-manganese and cadmium-iron interaction  

SciTech Connect

Increase cadmium production has enhanced the potential danger of this toxic metal including its effect upon the metabolism of some essential elements as, for instance, manganese of some essential elements as, for instance, manganese and iron. Relevant data about the cadmium-manganese interaction are rather scanty. Since there are more data of the effect of iron on the metabolism of either of these ions independently. The authors decided to investigate how the presence of iron affected the interaction between cadmium and manganese and how cadmium alone or in combination with the additional iron affected iron transfer and retention in the intestinal wall.

Gruden, N.; Munic, S.

1987-06-01

2

Effects of dietary copper, cadmium, iron, molybdenum and manganese on selenium utilization by the rat  

SciTech Connect

The possible antagonistic effects of different dietary concentrations of copper (1.3-200 mg/kg), cadmium (1-5 mg/kg), iron (20-500 mg/kg), molybdenum (0.3-50 mg/kg) and manganese (0.2-200 mg/kg) on selenium utilization by the rat were studied by the measurement of the absorption and organ distribution of dietary selenium as (75Se)selenite and by effects on organ glutathione peroxidase (GSH-Px: EC 1.11.1.9) activity. Although a high concentration of copper (200 mg/kg) in the diet did not alter the percentage absorption and total-body retention of doses of 75SeO3(2)- by rats, after such treatment tissue 75Se distribution was changed and was lower total selenium in some tissues. After copper treatment (200 mg/kg diet) GSH-Px activity of liver, testis, kidney and whole blood was also lower. Dietary cadmium, iron, molybdenum and manganese at the concentrations investigated had no significant effects on selenium metabolism. Thus it is unlikely that copper, cadmium, iron, molybdenum and manganese at normal dietary concentrations will have a major effect on selenium metabolism in the rat, especially if adequate amounts of selenium are being consumed.

Abdel Rahim, A.G.; Arthur, J.R.; Mills, C.F.

1986-03-01

3

Cadmium and Nickel Adsorption and Uptake in Cattail as Affected by Iron and Manganese Plaque on the Root Surface  

Microsoft Academic Search

The effects of iron (Fe) and manganese (Mn) plaque on the adsorption and uptake of cadmium (Cd) and nickel (Ni) in cattail (Typha latifolia L.) were investigated in nutrient solution cultures under laboratory conditions. Seedlings with and without Fe or Mn plaque on the roots (induced with 15 µg mL Fe or Mn) were exposed to 0.2 and 0.8 µg

Z. H. Ye; K. C. Cheung; M. H. Wong

2003-01-01

4

The ColRS signal transduction system responds to the excess of external zinc, iron, manganese, and cadmium  

PubMed Central

Background The ColRS two-component system has been shown to contribute to the membrane functionality and stress tolerance of Pseudomonas putida as well as to the virulence of Pseudomonas aeruginosa and plant pathogenic Xanthomonas species. However, the conditions activating the ColRS pathway and the signal(s) sensed by ColS have remained unknown. Here we aimed to analyze the role of the ColRS system in metal tolerance of P. putida and to test whether ColS can respond to metal excess. Results We show that the ColRS system is necessary for P. putida to tolerate the excess of iron and zinc, and that it also contributes to manganese and cadmium tolerance. Excess of iron, zinc, manganese or cadmium activates ColRS signaling and as a result modifies the expression of ColR-regulated genes. Our data suggest that the genes in the ColR regulon are functionally redundant, as several loci have to be deleted to observe a significant decrease in metal tolerance. Site-directed mutagenesis of ColS revealed that excess of iron and, surprisingly, also zinc are sensed by a conserved ExxE motif in ColS’s periplasmic domain. While ColS is able to sense different metals, it still discriminates between the two oxidation states of iron, specifically responding to ferric and not ferrous iron. We propose a signal perception model involving a dimeric ColS, where each monomer donates one ExxE motif for metal binding. Conclusions Several transition metals are essential for living organisms in certain amounts, but toxic in excess. We show that ColRS is a sensor system which detects and responds to the excess of physiologically important metals such as zinc, iron and manganese. Thus, the ColRS system is an important factor for metal homeostasis and tolerance in P. putida. PMID:24946800

2014-01-01

5

Manganese and iron oxide immobilized activated carbons precursor to dead biomasses in the remediation of cadmium-contaminated waters.  

PubMed

The aim of the present investigation was to exploit the high specific surface area of activated carbons in immobilizing the manganese and iron oxides as to obtain a suitable, efficient and cost effective and environment benign wastewater treatment process in the remediation of cadmium-contaminated waters. The manganese and iron oxides were impregnated in situ onto the surface and pores of the activated carbons precursors to the rice hulls and areca nut wastes. The solids were characterized with the help of Fourier transform infrared spectroscopy and X-ray diffraction analytical data, and the BET specific surface area as obtained. The surface morphology of these solids was discussed with the help of scanning electron microscopic images. The activated carbon samples along with the manganese and iron immobilized activated carbons were further employed in the batch and column reactor operations in the remediation of cadmium-contaminated waters. The batch data showed that an increase in sorptive pH from 2.0 to 10.0 and concentration from 1.0 to 20 mg/L favoured the uptake of cadmium by these solids. Moreover, the 1,000 times increase in background electrolyte concentrations NaNO3 caused an insignificant decrease in cadmium uptake by these solids, which inferred that sorbing ions/species were sorbed specifically and forming 'inner-sphere' complexes onto the solid surface. The concentration dependence data were utilized to model various adsorption isotherms and indicated that Freundlich adsorption isotherm was reasonably fitted well. The kinetic data was fitted well to the pseudo-second-order rate equations; hence, the equilibrium sorption capacity was estimated. Furthermore, the dynamic experiments carried out by the column experiments and the breakthrough data were fitted well to the non-linear Thomas equations; accordingly, the loading capacity of the column was estimated. Iron or manganese immobilized activated carbons showed relatively higher loading capacity compared to its precursor activated carbons hence showing its possible implication in the remediation processes. Moreover, among these modified ACs, IIAC showed higher removal capacity than the MIAC solid. PMID:23589235

Lee, Seung-Mok; Lalhmunsiama; Choi, Sang-Il; Tiwari, Diwakar

2013-10-01

6

Variations between rice cultivars in iron and manganese plaque on roots and the relation with plant cadmium uptake.  

PubMed

To understand certain mechanisms causing variations between rice cultivars with regard to cadmium uptake and tolerance, pot soil experiments were conducted with two rice cultivars of different genotypes under different soil Cd levels. The relationships between plant Cd uptake and iron/manganese (Fe/Mn) plaque formation on roots were investigated. The results showed that rice cultivars differed markedly in Cd uptake and tolerance. Under soil Cd treatments, Cd concentrations and accumulations in the cultivar Shanyou 63 (the genotype indica) were significantly higher than those in the cultivar Wuyunjing 7 (the genotype japonica) (P < 0.01, or P < 0.05), and Shanyou 63 was more sensitive to Cd toxicity than Wuyunjing 7. The differences between the rice cultivars were the largest at relatively low soil Cd level (i.e., 10 mg/kg). Fe concentrations in dithionite-citrate-bicarbonate root extracts of Shanyou 63 were generally lower than that of Wuyunjing 7, and the difference was the most significant under the treatment of 10 mg Cd/kg soil. The results indicated that the formation of iron plaque on rice roots could act as a barrier to soil Cd toxicity, and may be a "buffer" or a "reservoir" which could reduce Cd uptake into rice roots. And the plaque may contribute, to some extent, to the genotypic differences of rice cultivars in Cd uptake and tolerance. PMID:21174997

Liu, Jianguo; Cao, Changxun; Wong, Minghung; Zhang, Zhijun; Chai, Yuhong

2010-01-01

7

Inductively coupled plasma atomic fluorescence spectrometric determination of cadmium, copper, iron, lead, manganese and zinc  

USGS Publications Warehouse

An inductively coupled plasma atomic fluorescence spectrometric method is described for the determination of six elements in a variety of geological materials. Sixteen reference materials are analysed by this technique to demonstrate its use in geochemical exploration. Samples are decomposed with nitric, hydrofluoric and hydrochloric acids, and the residue dissolved in hydrochloric acid and diluted to volume. The elements are determined in two groups based on compatibility of instrument operating conditions and consideration of crustal abundance levels. Cadmium, Cu, Pb and Zn are determined as a group in the 50-ml sample solution under one set of instrument conditions with the use of scatter correction. Limitations of the scatter correction technique used with the fluorescence instrument are discussed. Iron and Mn are determined together using another set of instrumental conditions on a 1-50 dilution of the sample solution without the use of scatter correction. The ranges of concentration (??g g-1) of these elements in the sample that can be determined are: Cd, 0.3-500; Cu, 0.4-500; Fe, 85-250 000; Mn, 45-100 000; Pb, 5-10 000; and Zn, 0.4-300. The precision of the method is usually less than 5% relative standard deviation (RSD) over a wide concentration range and acceptable accuracy is shown by the agreement between values obtained and those recommended for the reference materials.

Sanzolone, R. F.

1986-01-01

8

Drinking Water Problems: Iron and Manganese  

E-print Network

concentrations of iron and manganese) Oxidizing filter?manganese greensand or zeolite (use with zeolite coated with manganese oxide. These substances adsorb dis- solved iron and manganese. Synthetic zeolite requires less backwash water and softens water as it removes impurities...

Dozier, Monty; McFarland, Mark L.

2004-02-20

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  

SciTech Connect

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.

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)] [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)] [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)] [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)] [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)] [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)] [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)] [Statistics Norway, P.Box 8131 Dep, N-0033 Oslo (Norway)

2010-07-15

10

Iron and manganese in lakes  

Microsoft Academic Search

The role of redox processes in determining the chemistry of iron and manganese is considered systematically. Both metals have soluble reduced forms and insoluble oxyhydroxides which are readily interconverted in the vicinity of a redox boundary. Although the oxyhydroxides are dominant in well-oxygenated waters, measureable concentrations of Fe(II) and Mn(II) can be observed, especially where photochemical reduction occurs. Differences in

William Davison

1993-01-01

11

Battles with Iron: Manganese in Oxidative Stress Protection*  

PubMed Central

The redox-active metal manganese plays a key role in cellular adaptation to oxidative stress. As a cofactor for manganese superoxide dismutase or through formation of non-proteinaceous manganese antioxidants, this metal can combat oxidative damage without deleterious side effects of Fenton chemistry. In either case, the antioxidant properties of manganese are vulnerable to iron. Cellular pools of iron can outcompete manganese for binding to manganese superoxide dismutase, and through Fenton chemistry, iron may counteract the benefits of non-proteinaceous manganese antioxidants. In this minireview, we highlight ways in which cells maximize the efficacy of manganese as an antioxidant in the midst of pro-oxidant iron. PMID:22247543

Aguirre, J. Dafhne; Culotta, Valeria C.

2012-01-01

12

Deposition of manganese sulfide and cadmium doped manganese sulfide thin films by M-CBD  

NASA Astrophysics Data System (ADS)

Un-doped and cadmium doped manganese sulfide thin films were prepared by M-CBD of aqueous solution onto glass substrates. The structural properties studied using X-ray diffraction showed that the un-doped manganese sulfide films exhibit amorphous structure; however Cd doped manganese sulfide films were crystalline. The surface morphological studies from SEM depicted the formation of clusters-like structure of un-doped manganese sulfide while the Cd doped film showed the nanocrystalline grains on the surface. From the optical studies, the absorbance in the wavelength range of 350-850 nm was found to increase after doping of Cd. The optical band gap was found to be 3.9 eV for un-doped manganese sulfide film and 3.7 eV for Cd doped films.

Pathan, Habib M.; Kale, Sampat S.; Pandit, Vishal K.

2012-06-01

13

Precise coulometric determination of iron in iron ores with electrogenerated manganese(III) fluoride.  

PubMed

Iron in Mohr's salt, electrolytic iron and iron ores has been determined by precision coulometric titration with electrolytically generated manganese (III) fluoride, with biamperometric end-point detection. The titration curve indicated the irreversibility of the electrode reaction of manganese(III) fluoride. Total iron in several standard samples of iron ores was determined with standard deviations of about 0.012%. PMID:18961613

Yoshimori, T; Tanaka, T

1975-01-01

14

40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Cobalt iron manganese oxide, carboxylic acid-modified...Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid-modified...identified generically as cobalt iron manganese oxide, carboxylic...

2013-07-01

15

40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).  

... 2014-07-01 false Cobalt iron manganese oxide, carboxylic acid-modified...Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid-modified...identified generically as cobalt iron manganese oxide, carboxylic...

2014-07-01

16

Thermochemistry of iron manganese oxide spinels  

Microsoft Academic Search

Oxide melt solution calorimetry has been performed on iron manganese oxide spinels prepared at high temperature. The enthalpy of formation of (MnxFe1?x)3O4 at 298K from the oxides, tetragonal Mn3O4 (hausmannite) and cubic Fe3O4 (magnetite), is negative from x=0 to x=0.67 and becomes slightly positive for 0.67

Sophie Guillemet-Fritsch; Alexandra. Navrotsky; Philippe Tailhades; Hervé Coradin; Miaojun Wang

2005-01-01

17

Colloidal iron and manganese in water affecting RO operation  

Microsoft Academic Search

The finding of various forms of iron, and less commonly of manganese, in numerous reverse osmosis (RO) membrane autopsies we have performed, have led us to call attention to the diverse forms of iron and manganese species in natural waters. Correlation of elemental composition analyses of foulants with contaminants in RO feedwater and pretreatment steps led to successful solutions of

Robert Y. Ning

2009-01-01

18

Monoamine oxidase activity in placenta in relation to manganese, cadmium, lead, and mercury at delivery.  

E-print Network

Monoamine oxidase activity in placenta in relation to manganese, cadmium, lead, and mercury challenge in regard to study of early toxic effects. Monoamine oxidase activity, shown to be influenced: manganese, lead, cadmium, mercury, monoamine oxidase, pregnancy inserm-00422145,version1-6Oct2009 #12

Paris-Sud XI, Université de

19

Structural and mechanical studies of cadmium manganese thiocyanate crystal  

NASA Astrophysics Data System (ADS)

Single crystals of cadmium manganese thiocyanate (CMTC) have been synthesized successfully and grown by slow evaporation method. The structural perfection of the grown crystals has been analyzed by High resolution X-ray diffraction (HRXRD), which shows the crystalline perfection of the grown crystal is quite good. Optical behavior was assessed by UV-Vis analysis and found that no absorption in the UV visible region and it may be useful for second harmonic applications. The mechanical hardness of the grown crystals was studied and Vicker's microhardness, Stiffness constant was calculated.

Manikandan, M. R.; Vijayaprasath, G.; babu, G. Anandha; Bhagavannarayan, G.; Vijayan, N.; Ravi, G.

2012-06-01

20

The interaction of mitochondrial iron with manganese superoxide dismutase.  

PubMed

Superoxide dismutase 2 (SOD2) is one of the rare mitochondrial enzymes evolved to use manganese as a cofactor over the more abundant element iron. Although mitochondrial iron does not normally bind SOD2, iron will misincorporate into Saccharomyces cerevisiae Sod2p when cells are starved for manganese or when mitochondrial iron homeostasis is disrupted by mutations in yeast grx5, ssq1, and mtm1. We report here that such changes in mitochondrial manganese and iron similarly affect cofactor selection in a heterologously expressed Escherichia coli Mn-SOD, but not a highly homologous Fe-SOD. By x-ray absorption near edge structure and extended x-ray absorption fine structure analyses of isolated mitochondria, we find that misincorporation of iron into yeast Sod2p does not correlate with significant changes in the average oxidation state or coordination chemistry of bulk mitochondrial iron. Instead, small changes in mitochondrial iron are likely to promote iron-SOD2 interactions. Iron binds Sod2p in yeast mutants blocking late stages of iron-sulfur cluster biogenesis (grx5, ssq1, and atm1), but not in mutants defective in the upstream Isu proteins that serve as scaffolds for iron-sulfur biosynthesis. In fact, we observed a requirement for the Isu proteins in iron inactivation of yeast Sod2p. Sod2p activity was restored in mtm1 and grx5 mutants by depleting cells of Isu proteins or using a dominant negative Isu1p predicted to stabilize iron binding to Isu1p. In all cases where disruptions in iron homeostasis inactivated Sod2p, we observed an increase in mitochondrial Isu proteins. These studies indicate that the Isu proteins and the iron-sulfur pathway can donate iron to Sod2p. PMID:19561359

Naranuntarat, Amornrat; Jensen, Laran T; Pazicni, Samuel; Penner-Hahn, James E; Culotta, Valeria C

2009-08-21

21

Manganese and iron oxidation by fungi isolated from building stone.  

PubMed

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. PMID:24190274

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

1994-01-01

22

The biogeochemistry of manganese and iron reduction in marine sediments  

Microsoft Academic Search

Manganese and iron reduction in marine sediments are known to play important roles in the biogeochemical cycles of many elements, including carbon, sulfur, phosphorus and several trace elements. These reduction reactions affect these cycles on a variety of time scales, ranging from those as short as seasonal time scales (e.g., nutrient cycling in coastal ecosystems), to those as long as

David J. Burdige

1993-01-01

23

Elements of the iron and manganese cycles in Lake Baikal  

USGS Publications Warehouse

Using data obtained in recent years, we considered the external mass balance and characteristics of internal iron and manganese cycles in Lake Baikal (biological uptake, remineralization, sedimentary and diffusive fluxes, accumulation in sediments, time of renewal, etc.). Some previous results and common concepts were critically reevaluated. ?? Pleiades Publishing, Ltd. 2007.

Granina, L.Z.; Callender, E.

2007-01-01

24

Iron and manganese are two similar ele-ments that can be a nuisance in a drinking  

E-print Network

Iron and manganese are two similar ele- ments that can be a nuisance in a drinking water supply. Iron is more common than manganese, but they often occur together. They are not hazardous to health. What problems do iron and manganese cause? Iron and manganese can give water an unpleasant taste, odor

25

Manganese, iron, and total particulate exposures to welders.  

PubMed

Welders are exposed to a variety of metal fumes, including manganese, that may elevate the risk for neurological disease. This study examines several large data sets to characterize manganese, iron, and total particulate mass exposures resulting from welding operations. The data sets contained covariates for a variety of exposure modifiers, including the presence of ventilation, the degree of confinement, and the location of the personal sampler (i.e., behind or in front of the welding helmet). The analysis suggests that exposures to manganese are frequently at or above the current ACGIH(R) threshold limit value of 0.2 mg/m(3). In addition, there is evidence that local exhaust ventilation can control the exposures to manganese and total fume but that mechanical ventilation may not. The data suggest that higher exposures are associated with a greater degree of enclosure, particularly when local exhaust ventilation is absent. Samples taken behind the helmet were, in general, lower than those measured outside of it. There were strong correlations among manganese, iron, and total particulate mass exposures, suggesting simple equations to estimate one fume component from any of the others. PMID:20013450

Flynn, Michael R; Susi, Pam

2010-02-01

26

Western Pacific coastal sources of iron, manganese, and aluminum to the Equatorial Undercurrent  

E-print Network

Western Pacific coastal sources of iron, manganese, and aluminum to the Equatorial Undercurrent Lia results from the first zonal transect of iron, aluminum, and manganese conducted from the western source, aluminum, and manganese were evident in the EUC. These maxima were generally greatest in the western

Murray, James W.

27

Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide  

USGS Publications Warehouse

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 is reflected in decreasing equilibrium constants for selenite with increasing adsorption density and both experimental observations and modeling results suggest that manganese dioxide has fewer sites of higher energy for selenite adsorption than amorphous iron oxyhydroxide. Modeling and interpreting the adsorption of phosphate, molybdate, and silicate on the oxides are made difficult by the lack of constraint in choosing surface species and the fact that equally good fits can be obtained with different surface species. Finally, predictions of anion competition using the model results from single adsorbate systems are not very successful because the model does not account for surface site heterogeneity. Selenite adsorption data from a multi-adsorbate system could be fit if the equilibrium constant for selenite is decreased with increasing anion adsorption density. ?? 1990.

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

1990-01-01

28

Iron and Manganese in Potable Water  

E-print Network

in nitric acid solution free from chlorides, is first treated with 3odium "bismuthate, "boiled until the color of manganic acid has arisen to a maximum and tben disappeared. By this means all organic matter is ox­ idized. The solution is then clearified... is used in that no filtration is necessary if the water has been freed from chloride. Methods. Sufficient amount of water to give one to five mil­ ligrams of Manganese is evaporated with five cubic centi­ meters of concentrated sulphuric acid until...

Young, Clifford Caudy

1911-06-01

29

Dynamics of manganese, cadmium, and lead in experimental power plant ponds  

Microsoft Academic Search

This study was designed to determine the effect of heated power plant cooling water on the compartmentalization of manganese, lead, and cadmium in experimental ponds. Caged channel catfish and green sunfish were kept in an experimental pond and a control pond. Periodically, whole fishes, gill, heart, kidney, liver, and musculature were analyzed for the three metals. Concentrations of the three

B. J. Mathis; T. F. Cummings; Mary Gower; Michael Taylor; Christine King

1977-01-01

30

Permeation of Manganese, Cadmium, Zinc, and Beryllium Through Calcium Channels of an Insect Muscle Membrane  

Microsoft Academic Search

Larval muscle fibers of a beetle, Xylotrupes dichotomus, produce calcium spikes that are maintained when the fibers are bathed in saline solutions containing manganese, cadmium, zinc, or beryllium instead of calcium. This indicates that these cations permeate the calcium channels of the muscle fiber. By contrast, cobalt, nickel, and magnesium are nonpermeating and behave as competitive inhibitors of the permeation

Jun Fukuda; Kazuyoshi Kawa

1977-01-01

31

Biogeochemistry of manganese- and iron-rich sediments in Toolik Lake, Alaska  

Microsoft Academic Search

The sediments within Toolik Lake in arctic Alaska are characterized by extremely low rates of organic matter sedimentation\\u000a and unusually high concentrations of iron and manganese. Pore water and solid phase measurements of iron, manganese, trace\\u000a metals, carbon, nitrogen, phosphorus, and sulfur are consistent with the hypothesis that the reduction of organic matter by\\u000a iron and manganese is the most

Jeffrey C. Cornwell; George W. Kipphut

1992-01-01

32

Iron isotopes constrain biogeochemical redox cycling of iron and manganese in a Palaeoproterozoic stratified basin  

NASA Astrophysics Data System (ADS)

The Hotazel Formation in the uppermost stratigraphic portion of the Neoarchaean-Palaeoproterozoic Transvaal Supergroup of southern Africa is an unusual sedimentary sequence of banded iron-formation (BIF) intercalated with three manganese-rich layers. As such, it is a succession that holds great potential to offer a unique view of one of the most dramatic transitions in early Earth history — the switch to a full oxidative cycle in shallow oceans at ca. 2.3 Ga. We present iron isotope results from BIF and Mn-rich samples collected across the entire Hotazel sequence, with a view to constraining processes of biogeochemical redox cycling for both metals close to the transition from a reducing to an oxidizing ocean-atmosphere system. The recorded de-coupling of Fe- and Mn reduction during anaerobic organic carbon cycling in the Hotazel strata, suggests that manganese became an important electron acceptor in stratified marine environments of the Palaeoproterozoic during periods of increased primary manganese precipitation relative to iron. Very low ? 57Fe values registered across the entire Hotazel sequence and especially in manganese-rich samples (-2.4 to -3.5‰) signify deposition of iron and manganese in a terminal, stratified aqueous reservoir that was depleted in the heavy iron isotopes. These isotopic signatures, in conjunction with the unusual endowment of the Hotazel sequence in manganese, are interpreted to have evolved by Rayleigh distillation processes during protracted deposition of Mn-poor BIFs as preserved in the lower stratigraphic portion of the Transvaal Supergroup (Kuruman and Griquatown BIFs). The unique end-member geochemical and isotopic characteristics of the Hotazel rocks may therefore constitute a potential link between the widespread deposition of BIF during the Neoarchaean and Palaeoproterozoic, and the postulated rise in atmospheric oxygen levels around 2.3 Ga ago.

Tsikos, Harilaos; Matthews, Alan; Erel, Yigal; Moore, John M.

2010-09-01

33

Iron and manganese oxide mineralization in the Pacific  

USGS Publications Warehouse

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. Iron and manganese deposits occur in five forms: nodules, crusts, cements, mounds and sediment-hosted stratabound layers. Seafloor oxides show a wide range of compositions from nearly pure iron to nearly pure manganese end members. Fe/Mn ratios vary from about 24 000 (up to 58% elemental Fe) for hydrothermal seamount ironstones to about 0.001 (up to 52% Mn) for hydrothermal stratabound manganese oxides from active volcanic arcs. Hydrogenetic Fe-Mn crusts that occur on most seamounts in the ocean basins have a mean Fe/Mn ratio of 0.7 for open-ocean seamount crusts and 1.2 for continental margin seamount crusts. Fe-Mn nodules of potential economic interest from the Clarion-Clipperton Zone have a mean Fe/Mn ratio of 0.3, whereas the mean ratio for nodules from elsewhere in the Pacific is about 0.7. Crusts are enriched in Co, Ni and Pt and nodules in Cu and Ni, and both have significant concentrations of Pb, Zn, Ba, Mo, V and other elements. In contrast, hydrothermal deposits commonly contain only minor trace metal contents, although there are many exceptions, for example, with Ni contents up to 0.66%, Cr to 1.2%, and Zn to 1.4%. Chondrite-normalized REE patterns generally show a positive Ce anomaly and abundant ??REEs for hydrogenetic and mixed hydrogenetic-diagenetic deposits, whereas the Ce anomaly is negative for hydrothermal deposits and ??REE contents are low. However, the Ce anomaly in crusts may vary from strongly positive in East Pacific crusts to slightly negative in West Pacific crusts, which may reflect the redox conditions of seawater. The concentration of elements in hydrogenetic Fe-Mn crusts depends on a wide variety of water column and crust surface characteristics, whereas concentration of elements in hydrothermal oxide deposits depends of the intensity of leaching, rock types leached, and precipitation of sulphides at depth in the hydrothermal system.

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

1997-01-01

34

Kinetics of Ion Removal from an Iron-Rich Industrial Coproduct: III. Manganese and Chromium  

E-print Network

Kinetics of Ion Removal from an Iron-Rich Industrial Coproduct: III. Manganese and Chromium Yigal by employing adsorption isotherms, column studies, and the stirred-flow (SF) kinetic technique. Manganese characteristics from the IRM, and (ii) to ascertain the kinetics of Mn and Cr removal from the IRM. Manganese

Sparks, Donald L.

35

Atmospheric input of manganese and iron to the ocean: Seawater dissolution experiments with Saharan and North American dusts  

E-print Network

Atmospheric input of manganese and iron to the ocean: Seawater dissolution experiments with Saharan online 9 September 2008 Keywords: Iron Manganese Aerosol Dust dissolution Marine chemistry Dissolution of wind blown dust is a major source of iron, manganese and other trace nutrients in the ocean. Kinetic

Guieu, Cécile

36

Manganese doping of magnetic iron oxide nanoparticles: tailoring surface reactivity for a regenerable heavy metal sorbent.  

PubMed

A method for tuning the analyte affinity of magnetic, inorganic nanostructured sorbents for heavy metal contaminants is described. The manganese-doped iron oxide nanoparticle sorbents have a remarkably high affinity compared to the precursor material. Sorbent affinity can be tuned toward an analyte of interest simply by adjustment of the dopant quantity. The results show that following the Mn doping process there is a large increase in affinity and capacity for heavy metals (i.e., Co, Ni, Zn, As, Ag, Cd, Hg, and Tl). Capacity measurements were carried out for the removal of cadmium from river water and showed significantly higher loading than the relevant commercial sorbents tested for comparison. The reduction in Cd concentration from 100 ppb spiked river water to 1 ppb (less than the EPA drinking water limit of 5 ppb for Cd) was achieved following treatment with the Mn-doped iron oxide nanoparticles. The Mn-doped iron oxide nanoparticles were able to load ~1 ppm of Cd followed by complete stripping and recovery of the Cd with a mild acid wash. The Cd loading and stripping is shown to be consistent through multiple cycles with no loss of sorbent performance. PMID:22329500

Warner, Cynthia L; Chouyyok, Wilaiwan; Mackie, Katherine E; Neiner, Doinita; Saraf, Laxmikant V; Droubay, Timothy C; Warner, Marvin G; Addleman, R Shane

2012-02-28

37

Manganese Doping of Magnetic Iron Oxide Nanoparticles: Tailoring Surface Reactivity for a Regenerable Heavy Metal Sorbent  

SciTech Connect

A method for tuning the analyte affinity of magnetic, inorganic nanostructured sorbents for heavy metal contaminants is described. The manganese-doped iron oxide nanoparticle sorbents have a remarkably high affinity compared to the precursor material. Sorbent affinity can be tuned toward an analyte of interest simply by adjustment of the dopant quantity. The results show that following the Mn doping process there is a large increase in affinity and capacity for heavy metals (i.e., Co, Ni, Zn, As, Ag, Cd, Hg, and Tl). Capacity measurements were carried out for the removal of cadmium from river water and showed significantly higher loading than the relevant commercial sorbents tested for comparison. The reduction in Cd concentration from 100 ppb spiked river water to 1 ppb (less than the EPA drinking water limit of 5 ppb for Cd) was achieved following treatment with the Mn-doped iron oxide nanoparticles. The Mn-doped iron oxide nanoparticles were able to load 1 ppm of Cd followed by complete stripping and recovery of the Cd with a mild acid wash. The Cd loading and stripping is shown to be consistent through multiple cycles with no loss of sorbent performance.

Warner, Cynthia L.; Chouyyok, Wilaiwan; Mackie, Katherine E.; Neiner, Doinita; Saraf, Laxmikant; Droubay, Timothy C.; Warner, Marvin G.; Addleman, Raymond S.

2012-02-28

38

Combined nonlinear-optical electric and magnetic field response in a cadmium manganese telluride crystal  

Microsoft Academic Search

Utilizing experimental results, which demonstrate the presence of both Faraday rotation and electric-field-induced linear birefringence in a diluted-magnetic-semiconductor crystal of cadmium manganese telluride (CMT), a single probe that is capable of sensing both electric and magnetic fields independently has been developed. A higher field sensitivity and greater accuracy are observed for the CMT crystal when compared to a lithium tantalate

Chia-Chu Chen; John F. Whitaker

2008-01-01

39

The influence of phosphorus, zinc and manganese on absorption and translocation of iron in watercress  

Microsoft Academic Search

Absorption and translocation of iron by intact watercress plants (Rorippa nasturtium-aquaticum (L) Hayek) was studied in short period uptake experiments utilising 59Fe labelled ferric chloride. Total translocation of iron was inhibited by increasing levels of phosphorus, zinc and manganese in the nutrient medium; the elevated phosphorus and zinc concentrations enhanced iron absorption into roots, but increased retention of absorbed iron

I. P. Cumbus; D. J. Hornsey; L. W. Robinson

1977-01-01

40

Cadmium effects in rats on tissue iron, selenium, and blood pressure; blood and hair cadmium in some oregon residents.  

PubMed

Exposure of rats to cadmium causes a marked depletion of iron in liver and kidney. Selenium neither counteracts or intensifies the influence of cadmium on tissue iron levels. Selenium injections protect against cadmium-induced testicular damage but cause this element to accumulate in the testes at higher concentration than in animals exposed to cadmium without selenium. Selenium injection diverts the binding of cadmium from low molecular weight proteins to high molecular weight ones. Dosing rats with selenium and cadmium or inclusion of Se or Cd in the diet did not result in altered cadmium binding in tissues, raising some questions concerning the environmental significance of these injection experiments. Addition of selenium to a diet containing cadmium decreased the accumulation of cadmium in liver and kidney, but increased its deposition in testes. The metabolism of cadmium bound to metallothionein was markedly different as compared to the inorganic salt of this element. Dietary ascorbate, but not citrate or cysteine, decreased the deposition of cadmium in rat tissues. In some low-level exposure experiments with cadmium (1 to 1000 ppb), no differences were found in the percentage of dose absorbed or rate of cadmium accumulation when provided in food versus water. Female rats tended to absorb more cadmium than males. The binding of cadmium to cytosolic proteins was found to be different between rats fed low levels of cadmium (up to 1 ppm) as compared to those fed high levels of this element (100 ppm). Cadmium was not found to contribute to hypertension in rats, and a summary of results by various investigators is presented. Blood and hair cadmium levels in Oregon residents were found to be highest in employees of a mine, and hair cadmium was found to be respectively higher in smokers than nonsmokers and in metal workers than office workers. No relationships were observed in humans between blood or hair cadmium levels and blood pressure. PMID:488028

Whanger, P D

1979-02-01

41

Interactive effects of manganese and/or iron supplementation in adult women  

SciTech Connect

Evaluation of the practical significance of manganese-iron interactions has been hampered by the limited methodologies available to assess manganese status. Manganese status has not been monitored longitudinally in control studies with humans. Forty-eight women were recruited for a double blind 125-day supplementation study. After an initial 5-day baseline period, subjects were assigned to one of four treatments: placebo; 30 mg iron as ferrous fumarate daily; 15 mg manganese as an amino acid chelated manganese supplement daily or both the iron and manganese supplements daily. Dietary information, blood and 3-day urine samples were collected during the baseline period and after 20, 55, 85 and 120 days of consuming the supplements. Urinary manganese excretion ranged from 0.11 to 1.40 {mu}g/day. Serum manganese ranged from 0.16 to 1.92 {mu}g/l. Serum was also analyzed for iron, zinc, copper, ferritin and transferrin concentrations. Lymphocytes were isolated and manganese-dependent superoxide dismutase activity was determined as a new method to assess manganese status. Plasma cholesterol ranged from 126 to 229 mg/dl and HDL cholesterol ranged from 31 to 84 mg/dl. Plasma triglycerides were determined and LDL cholesterol was calculated by difference.

Davis, C.D.; Greger, J.L. (Univ. of Wisconsin, Madison (United States))

1991-03-15

42

Effect of Acute and Subchronic Exposure to Cadmium on the Retention of Iron in Rats  

Microsoft Academic Search

The influence of cadmium on the retention of a single dose of iron after acute and subchronic treatment with cadmium was studied in normal rats. Additionally the results were compared with iron retention in unexposed iron-defi cient animals. Test solutions contained iron and cadmium in various molar ratios (Fe:Cd = 1:0, 1:0.5, 1:1, 1:2 jimol\\/kg body weight). In acute experiments

SIEGFRIED G. SCHÃ; FER ANDWOLFGANG FORTH

43

Evolution of Microstructures During Austempering of Ductile Irons Alloyed with Manganese and Copper  

NASA Astrophysics Data System (ADS)

The influences of relatively high manganese (0.45 through 1.0 wt pct) and copper (0.56 through 1.13 wt pct) contents on microstructure development and phase transformation in three austempered ductile irons have been studied. The experimental ductile irons alloyed with copper and manganese are found to be practically free from intercellular manganese segregation. This suggests that the positive segregation of manganese is largely neutralized by the negative segregation of copper when these alloying elements are added in appropriate proportions. The drop in unreacted austenite volume (UAV) with increasing austempering temperature and time is quite significant in irons alloyed with copper and manganese. The ausferrite morphology also undergoes a transition from lenticular to feathery appearance of increasing coarseness with the increasing austempering temperature and time. SEM micrographs of the austempered samples from the base alloy containing manganese only, as well as copper plus manganese-alloyed irons, clearly reveal the presence of some martensite along with retained austenite and ferrite. X-ray diffraction analysis also confirms the presence of these phases. SEM examination further reveals the presence of twinned martensite in the copper plus manganese-alloyed samples. The possibility of strain-induced transformation of austenite to martensite during austempering heat treatment is suggested.

Dasgupta, Ranjan Kumar; Mondal, Dipak Kumar; Chakrabarti, Ajit Kumar

2013-03-01

44

Influences on the oceanic biogeochemical cycling of the hybrid-type metals, cobalt, iron, and manganese  

E-print Network

Trace metal cycling is one of many processes that influence ocean ecosystem dynamics. Cobalt, iron, and manganese are redox active trace metal micro-nutrients with oceanic distributions that are influenced by both biological ...

Noble, Abigail Emery

2012-01-01

45

Combined nonlinear-optical electric and magnetic field response in a cadmium manganese telluride crystal  

NASA Astrophysics Data System (ADS)

Utilizing experimental results, which demonstrate the presence of both Faraday rotation and electric-field-induced linear birefringence in a diluted-magnetic-semiconductor crystal of cadmium manganese telluride (CMT), a single probe that is capable of sensing both electric and magnetic fields independently has been developed. A higher field sensitivity and greater accuracy are observed for the CMT crystal when compared to a lithium tantalate electro-optic crystal and terbium gallium garnet magneto-optic crystal. The linear electro-optic coefficient r41 for CMT has been calculated from electric-field measurements to be 3.5±0.2pm/V.

Chen, Chia-Chu; Whitaker, John F.

2008-03-01

46

Tuning the redox properties of manganese(II) and its implications to the electrochemistry of manganese and iron superoxide dismutases.  

PubMed

Superoxide dismutases (SODs) catalyze the disproportionation of superoxide to dioxygen and hydrogen peroxide. The active metal sites of iron and manganese superoxide dismutases are structurally indistinguishable from each other. Despite the structural homology, these enzymes exhibit a high degree of metal selective activity suggesting subtle redox tuning of the active site. The redox tuning model, however, up to now has been challenged by the existence of so-called cambialistic SODs that function with either metal ion. We have prepared and investigated two sets of manganese complexes in which groups of varying electron-withdrawing character, as measured by their Hammett constants sigma Para, have been introduced into the ligands. We observed that the Mn(III)/Mn(II) reduction potential for the series based on 4'-X-terpyridine ligands together with the corresponding values for the iron-substituted 4'-X-terpyridine complexes changed linearly with sigma Para. The redox potential of the iron and manganese complexes could be varied by as much as 600 mV by the 4'-substitution with the manganese complexes being slightly more sensitive to the substitution than iron. The difference was such that in the case where the 4'-substituent was a pyrrolidine group both the manganese and the iron complex were thermodynamically competent to catalytically disproportionate superoxide, making this particular ligand "cambialistic". Taking our data and those available from the literature together, it was found that in addition to the electron-withdrawing capacity of the 4'-substituents the overall charge of the Mn(II) complexes plays a major role in tuning the redox potential, about 600 mV per charge unit. The ion selectivity in Mn and FeSODs and the occurrence of cambialistic SODs are discussed in view of these results. We conclude that the more distant electrostatic contributions may be the source of metal specific enzymatic activity. PMID:18271528

Sjödin, Martin; Gätjens, Jessica; Tabares, Leandro C; Thuéry, Pierre; Pecoraro, Vincent L; Un, Sun

2008-04-01

47

Hawaiian submarine manganese-iron oxide crusts - A dating tool?  

USGS Publications Warehouse

Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measured on samples collected since 1965 on the Hawaiian Ridge from 140 dive or dredge localities. Fifty-nine (42%) of the sites were collected in 2001 by remotely operated vehicles (ROVs). The thinner crusts on many samples apparently result from post-depositional breakage, landsliding, and intermittent burial of outcrops by sediment. The maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site. The measurements show an irregular progressive thickening of the crusts toward the northwest-i.e., progressive thickening toward the older volcanic features with increasing distance from the Hawaiian hotspot. Comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust-growth rate of about 2.5 mm/m.y. The thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes, but also provides specific age estimates of volcanic and landslide deposits. The data indicate that some of the landslide blocks within the south Kona landslide are the oldest exposed rock on Mauna Loa, Kilauea, or Loihi volcanoes. Crusts on the floors of submarine canyons off Kohala and East Molokai volcanoes indicate that these canyons are no longer serving as channelways for downslope, sediment-laden currents. Mahukona volcano was approximately synchronous with Hilo Ridge, both being younger than Hana Ridge. The Nuuanu landslide is considerably older than the Wailau landslide. The Waianae landslide southwest of Oahu has yielded samples with the greatest manganese-iron oxide crusts (9.5 mm thick) and therefore apparently represents the oldest submarine material yet found in the study area. The submarine volcanic field 100 km southwest of Oahu is apparently younger than the Waianae landslide. ?? 2004 Geological Society of America.

Moore, J.G.; Clague, D.A.

2004-01-01

48

Morphology of graphite-supported iron-manganese catalyst particles: Formation of hollow spheres during oxidation  

SciTech Connect

Transmission electron microscopy (TEM) and Moessbauer spectroscopy (MES) were used to study the morphology of graphite-supported iron-manganese particles. Following oxidation at 500 K MES showed the iron in the particles to be fully oxidized. TEM showed all the particles to be torroidal in appearance. However, tilting resulting in no change in the apparent dimensions of the particles, yet the apparent distances between particles were sharply reduced. These results suggest the particles are actually spherical. On the basis of these experiments, and similar experiments with reduced particles, a model was developed: Following reduction the particles are spherical and consist of a metallic iron core surrounded by a shell of manganese oxide. During oxidation, iron ions diffuse through the manganese oxide shell to the particle surface. Eventually, this results in the formation of nearly spherical particles with hollow centers, inner shells of iron-manganese spinel, and outer shells of iron oxide. Upon an additional reduction the hollow center remains, but the shells phase segregate into regions of iron metal and manganese oxide.

Chen, A.A.; Vannice, M.A.; Phillips, J. (Pennsylvania State Univ., University Park (USA))

1989-04-01

49

Potentiating effects of oxygen in lungs damaged by methylcyclopentadienyl manganese tricarbonyl, cadmium chloride, oleic acid, and antitumor drugs  

Microsoft Academic Search

The intraperitoneal administration of methylcyclopentadienyl manganese tricarbonyl (MMT) and cyclophosphamide, exposure to an aerosol of cadmium chloride, intravenous administration of oleic acid, and intratracheal instillation of bleomycin to young female BALB\\/c mice or CD\\/CR rats result in acute lung injury. Pulmonary morphology and lung collagen content were examined in animals treated with these chemicals alone or in combination with an

P. J. Hakkinen; C. C. Morse; F. M. Martin; W. E. Dalbey; W. M. Haschek; H. R. Witschi

1983-01-01

50

Environmentally acquired lead, cadmium, and manganese in the cattle egret, Bubulcus ibis , and the laughing gull, Larus atricilla  

Microsoft Academic Search

The concentrations of lead, cadmium, and manganese in the tissues of cattle egrets (Bubulcus ibis) and laughing gulls (Larus atricilla) gathered from the Galveston Bay region of Texas were compared, to determine if different patterns of accumulation exist. Their levels in these species were within the range reported for other bird species. Lead levels in bone were comparable, but gulls

Michael Hulse; John S. Mahoney; Gene D. Schroder; Carl S. Hacker; Stanley M. Pier

1980-01-01

51

Relationships between chemical forms of soil iron and manganese and their absorption by rice from 34 flooded Gulf Coast soils of Texas  

E-print Network

manganese vs. plant manganese Solution iron vs. plant iron Solution Fe/Mn ratios vs. plant Re/Mn ratio . . . V. SUMMARY AND CONCLUSIONS 24 24 32 43 43 46 49 54 54 56 56 62 62 67 LITERATURE CITED APPENDIX 70 75 ix LIST OF TABLES Table... of iron (Fe) and manganese (Mn) in 34 Gulf Coast rice soils at 48 days from submergence . . . 44 6 Content of active iron and manganese, exchangeable iron and manganese (48 days from submergence), and water soluble iron and manganese (48 days from...

Phillips, Douglas Patton

2012-06-07

52

Topologically Constrained Manganese(III) and Iron(III) Complexes of Two Cross-Bridged Tetraazamacrocycles  

E-print Network

substituting azide for chloride ligands. Air oxidation of the dichloro complex of Mn (1)2+ in basic solution prepared by the chemical oxidation of the divalent manganese and iron analogues. The ligands are ethylene and iron oxides limits the utility, especially in aqueous media, of functional catalysts based on common

Hubin, Tim

53

Zinc and cadmium specifically interfere with RNA-binding activity of human iron regulatory protein 1  

Microsoft Academic Search

The cellular pro-oxidative stress induced by high zinc concentrations or cadmium is most likely mediated by disruption of redox (mainly thiol) homeostasis or by mishandling of redox-active transition metals. The impact of zinc and cadmium on the main regulators of iron homeostasis in metazoans, the iron regulatory proteins (IRP) 1 and 2, has been probed with the human recombinant proteins.

Alain Martelli; Jean-Marc Moulis

2004-01-01

54

Recent research progress on iron- and manganese-based positive electrode materials for rechargeable sodium batteries  

NASA Astrophysics Data System (ADS)

Large-scale high-energy batteries with electrode materials made from the Earth-abundant elements are needed to achieve sustainable energy development. On the basis of material abundance, rechargeable sodium batteries with iron- and manganese-based positive electrode materials are the ideal candidates for large-scale batteries. In this review, iron- and manganese-based electrode materials, oxides, phosphates, fluorides, etc, as positive electrodes for rechargeable sodium batteries are reviewed. Iron and manganese compounds with sodium ions provide high structural flexibility. Two layered polymorphs, O3- and P2-type layered structures, show different electrode performance in Na cells related to the different phase transition and sodium migration processes on sodium extraction/insertion. Similar to layered oxides, iron/manganese phosphates and pyrophosphates also provide the different framework structures, which are used as sodium insertion host materials. Electrode performance and reaction mechanisms of the iron- and manganese-based electrode materials in Na cells are described and the similarities and differences with lithium counterparts are also discussed. Together with these results, the possibility of the high-energy battery system with electrode materials made from only Earth-abundant elements is reviewed.

Yabuuchi, Naoaki; Komaba, Shinichi

2014-08-01

55

Influence of iron and zinc status on cadmium accumulation in Bangladeshi women  

SciTech Connect

Cadmium is a widespread environmental contaminant present in food. The absorption in the intestine increases in individuals with low iron stores, but the effect of zinc deficiency is not clear. The aim of the present study was to assess the influence of iron and zinc status on cadmium accumulation in pregnant Bangladeshi women. We measured cadmium in urine from 890 women using inductively coupled plasma mass spectrometry (ICPMS). Further, we also measured ferritin and zinc in plasma. The median cadmium concentration in urine was 0.59 {mu}g/L (adjusted to mean specific gravity of 1.012 g/mL). Analysis of covariance (ANCOVA) showed that urinary cadmium was associated with plasma ferritin and plasma zinc via a significant interaction between dichotomized plasma ferritin and plasma zinc. The analysis was adjusted for age and socioeconomic status. Women with low iron stores and adequate zinc status had significantly higher urinary cadmium compared to women with both adequate iron stores and zinc status. There was no difference in urinary cadmium between women with both low iron stores and zinc status compared to those with both adequate iron stores and zinc status. In conclusion, low iron stores were associated with increased cadmium accumulation, but only at adequate zinc status.

Kippler, Maria [Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden); Ekstroem, Eva-Charlotte [International Maternal and Child Health, Uppsala University, Uppsala (Sweden); Loennerdal, Bo [Department of Nutrition, University of California, Davis, CA 95616 (United States); Goessler, Walter [Institut fuer Chemie - Analytische Chemie, Karl-Franzens-Universitaet, Graz (Austria); Akesson, Agneta [Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden); El Arifeen, Shams [International Centre for Diarrhoeal Disease Research, Bangladesh - ICDDR-B, GPO Box 128, Dhaka 1000 (Bangladesh); Persson, Lars-Ake [International Maternal and Child Health, Uppsala University, Uppsala (Sweden); Vahter, Marie [Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden)]. E-mail: Marie.Vahter@ki.se

2007-07-15

56

Iron-Deficiency Induces Cadmium Uptake and Accumulation in Solanum nigrum L  

Microsoft Academic Search

Phytoremediation is a promising tool in removing pollutants from the environment or in rendering them harmless. The objective\\u000a of this research was to determine the effect of iron-deficiency on the uptake of cadmium by Solanum nigrum L. Results showed that iron-deficiency induced cadmium uptake, biomass decrease and changes in pH and Eh in hydroponic culture.\\u000a Under iron-deficiency status, the decrease

Tong Bao; Lina Sun; Tieheng Sun; Pin Zhang; Zhixin Niu

2009-01-01

57

Adsorption of iron cyanide complexes onto clay minerals, manganese oxide, and soil.  

PubMed

The adsorption characteristics of an iron cyanide complex, soluble Prussian blue KFe(III)[Fe(II)(CN)(6)], were evaluated for representative soil minerals and soil at pH 3.7, 6.4 and 9.7. Three specimen clay minerals (kaolinite, montmorillonite, and illite), two synthesized manganese oxides (birnessite and cryptomelane), and a Drummer soil from Indiana were used as the adsorbents. Surface protonation of variable charge sites increased with decreasing pH yielding positively charged sites on crystal edges and enhancing the attractive force between minerals and iron cyanide complexes. Anion adsorption on clays often is correlated to the metal content of the adsorbent, and a positive relationship was observed between iron or aluminum content and Prussian blue adsorption. Illite had high extractable iron and adsorbed more ferro-ferricyande anion, while kaolinite and montmorillonite had lower extractable iron and adsorbed less. However, less pH effect was observed on the adsorption of iron cyanide to manganese oxides. This may due to the manganese oxide mediated oxidation of ferrocyanide [Fe(II)(CN)(6)(4-)], to ferricyanide [Fe(III)(CN)(6)(3-)], which has a low affinity for manganese oxides. PMID:20665323

Kang, Dong-Hee; Schwab, A Paul; Johnston, C T; Banks, M Katherine

2010-09-01

58

Chlorobenzene oxidation using ozone over iron oxide and manganese oxide catalysts.  

PubMed

A low-temperature catalytic oxidation of chlorobenzene (CB) has been performed at temperatures of 60-210°C using ozone (O(3)) over iron oxide and manganese oxide, respectively. In the absence of ozone, CB conversion achieved with these two catalysts at 200°C was below 10%. However, addition of 1200 ppm ozone results in a remarkable increase in CB conversion and the conversion reaches 91.7% at 150°C for iron oxide, while 81.5% conversion is achieved with manganese oxide at 90°C. The activation energy of manganese oxide (48 kJ mol(-1)) is higher than that of iron oxide (43 kJ mol(-1)) without ozone. However, as ozone is added, the activation energy is significantly reduced to 20.0 kJ mol(-1) for iron oxide. CO and CO(2) are the only carbon-containing products detected in the effluent gas stream. For the long-term test, no obvious deactivation was found in iron oxide and ozone. However, in the case of manganese oxide and ozone, 3% reduction of CB conversion was observed. Slight deactivation might be attributed to a small amount of reaction byproducts (carboxylic acid species) and residual chloride (MnCl(2)) being deposited on the active sites of the catalysts. PMID:21227575

Wang, Hou Chuan; Liang, Hsu Shang; Chang, Moo Been

2011-02-28

59

Geological reconnaissance of some Uruguayan iron and manganese deposits in 1962  

USGS Publications Warehouse

Three mineralized areas lie in an area near the town of Minas de Corrales in the Departamento de Rivera; they are the Cerro Amelia, the Cerro de Papagayo, and the Cerro Iman. The Cerro Amelia is composed of small bands of iron-rich rock separated by an amphibolitic or mafic rock. Selective mining would be necessary to extract the 31,000 tons per meter of depth of iron-rich rock that ranges from 15 to 40 percent metallic iron. The Cerro de Papagayo district contains many small, rich deposits of ferruginous manganese ore. The ratio of Mn to Fe varies widely within each small deposit as well as from deposit to deposit. Some ferruginous manganese ore contains 50-55 percent manganese dioxide. Although there are many thousands of tons of ore in the district, small-scale mining operations are imperative. One deposit, the Cerro Avestuz manganese mine, was visited. The manganese ore body lies within contorted highly metamorphosed itabirite that contains both hard low grade and soft high grade ferruginous manganese ores estimated to average 40 percent Mn. About 38,000 tons of manganese ore is present in this deposit. The Cerro Iman is a large block of itabirite that contains about 40 percent Fe. The grade is variable and probably runs from less than 35 percent Fe to more than 50 percent Fe. No exploration has been done on this deposit. It is recommended that the Cerro de Iman area be geologically mapped in detail, and that a geological reconnaissance be made of the area that is between the Cuchilla de Corrales and the Cuchilla de Areycua/Cuchilla del Cerro Pelado area.

Wallace, Roberts Manning

1976-01-01

60

Alteration of Serum Concentrations of Manganese, Iron, Ferritin, and Transferrin Receptor Following Exposure to Welding Fumes Among Career Welders  

PubMed Central

This study was performed to determine airborne manganese levels during welding practice and to establish the relationship between long-term, low-level exposure to manganese and altered serum concentrations of manganese, iron, and proteins associated with iron metabolism in career welders. Ninety-seven welders (average age of 36 years) who have engaged in electric arc weld in a vehicle manufacturer were recruited as the exposed group. Welders worked 7–8 h per day with employment duration of 1–33 years. Control subjects consisted of 91 employees (average age of 35 years) in the same factory but not in the welding profession. Ambient manganese levels in welders’ breathing zone were the highest inside the vehicle (1.5 ± 0.7 mg/m3), and the lowest in the center of the workshop (0.2 ± 0.05 mg/m3). Since the filter size was 0.8 ?m, it is possible that these values may be likely an underestimation of the true manganese levels. Serum levels of manganese and iron in welders were about three-fold (p < 0.01) and 1.2-fold (p < 0.01), respectively, higher than those of controls. Serum concentrations of ferritin and transferrin were increased among welders, while serum transferrin receptor levels were significantly decreased in comparison to controls. Linear regression analyses revealed a lack of association between serum levels of manganese and iron. However, serum concentrations of iron and ferritin were positively associated with years of welder experience (p < 0.05). Moreover, serum transferrin receptor levels were inversely associated with serum manganese concentrations (p < 0.05). These findings suggest that exposure to welding fume among welders disturbs serum homeostasis of manganese, iron, and the proteins associated with iron metabolism. Serum manganese may serve as a reasonable biomarker for assessment of recent exposure to airborne manganese. PMID:15713346

Lu, Ling; Zhang, Long-lian; Li, G. Jane; Guo, Wenrui; Liang, Wannian; Zheng, Wei

2014-01-01

61

The autoxidation activity of new mixed-ligand manganese and iron complexes with tripodal ligands  

Microsoft Academic Search

The activity of new manganese and iron complexes of dianionic tripodal ligands in the autoxidation of ethyl linoleate (EL) is reported. EL consumption rates were monitored using time-resolved FTIR and the degree of oligomerisation was determined by SEC. Almost all complexes showed the same trend in the autoxidation of EL. After a short induction time, the reaction started at a

Remy van Gorkum; Joris Berding; Duncan M. Tooke; Anthony L. Spek; Jan Reedijk; Elisabeth Bouwman

2007-01-01

62

Kinetics of manganese oxide reduction from basic slags by carbon dissolved in liquid iron  

Microsoft Academic Search

The reduction of manganese oxide from a basic slag by carbon dissolved in liquid iron is a slow reaction, failing to approach equilibrium closely in 20 hr. Furthermore, the rate of stirring has no apparent effect on the reaction rate. This identifies the rate-controlling step as a chemical reaction at the interface. Only the model for the reaction O 2-

Weldon L. Daines; Robert D. Pehlke

1971-01-01

63

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

USGS Publications Warehouse

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.

Finkelman, R.B.

1970-01-01

64

Investigation of nanostructured iron and manganese oxides as novel intercalation hosts for lithium  

Microsoft Academic Search

Rechargeable lithium battery systems are being pushed to the limits of their performance in modern portable devices, with increasing demands for higher energy and higher power. The intercalation cathode or positive electrode in these batteries is one of the primary bottlenecks in terms of performance. In this thesis, investigation of nanostructured iron and manganese oxide compounds that show immense promise

Gaurav Jain

2005-01-01

65

Western Pacific coastal sources of iron, manganese, and aluminum to the Equatorial Undercurrent  

Microsoft Academic Search

We present results from the first zonal transect of iron, aluminum, and manganese conducted from the western source region of the Equatorial Undercurrent (EUC) to the central equatorial Pacific. Trace metals were elevated along the slope of Papua New Guinea and within the New Guinea Coastal Undercurrent (NGCU), which is the primary Southern Hemisphere entry path of water to the

Lia O. Slemons; James W. Murray; Joseph Resing; Barbara Paul; Pierre Dutrieux

2010-01-01

66

Influence of vegetative cycle of asparagus ( Asparagus officinalis L.) on copper, iron, zinc and manganese content  

Microsoft Academic Search

The essential elements copper (Cu), iron (Fe), zinc (Zn) and manganese (Mn) were analyzed in fresh asparagus to determine the effects of the vegetative cycle of the plant on the micronutrient content. Asparagus samples were classified in two groups by diameter (14 mm). Asparagus from a sample group with the same diameter were divided into two portions (apical and basal)

M. A. Amaro-Lopez; G. Zurera-Cosano; R. Moreno-Rojas; R. M. Garcia-Gimeno

1995-01-01

67

Associations of Toenail Arsenic, Cadmium, Mercury, Manganese, and Lead with Blood Pressure in the Normative Aging Study  

PubMed Central

Background: Arsenic, cadmium, mercury, and lead are associated with cardiovascular disease in epidemiologic research. These associations may be mediated by direct effects of the metals on blood pressure (BP) elevation. Manganese is associated with cardiovascular dysfunction and hypotension in occupational cohorts. Objectives: We hypothesized that chronic arsenic, cadmium, mercury, and lead exposures elevate BP and that manganese lowers BP. Methods: We conducted a cross-sectional analysis of associations between toenail metals and BP among older men from the Normative Aging Study (n = 639), using linear regression and adjusting for potential confounders. Results: An interquartile range increase in toenail arsenic was associated with higher systolic BP [0.93 mmHg; 95% confidence interval (CI): 0.25, 1.62] and pulse pressure (0.76 mmHg; 95% CI: 0.22, 1.30). Positive associations between arsenic and BP and negative associations between manganese and BP were strengthened in models adjusted for other toenail metals. Conclusions: Our findings suggest associations between BP and arsenic and manganese. This may be of public health importance because of prevalence of both metal exposure and cardiovascular disease. Results should be interpreted cautiously given potential limitations of toenails as biomarkers of metal exposure. PMID:21878420

Wright, Robert O.; Hu, Howard; Amarasiriwardena, Chitra; Baccarelli, Andrea; Litonjua, Augusto; Sparrow, David; Vokonas, Pantel; Schwartz, Joel

2011-01-01

68

Investigations of Cadmium Manganese Telluride Crystals for Room-Temperature Radiation Detection  

SciTech Connect

Cadmium manganese telluride (CMT) has high potential as a material for room-temperature nuclear-radiation detectors. We investigated indium-doped CMT crystals taken from the stable growth region of the ingot, and compared its characteristics with that from the last-to-freeze region. We employed different techniques, including synchrotron white-beam X-ray topography (SWBXT), current-voltage (I-V) measurements, and low-temperature photoluminescence spectra, and we also assessed their responses as detectors to irradiation exposure. The crystal from the stable growth region proved superior to that from the last-to-freeze region; it is a single-grain crystal, free of twins, and displayed a resistivity higher by two orders-of-magnitude. The segregation of indium dopant in the ingot might be responsible for its better resistivity. Furthermore, we recorded a good response in the detector fabricated from the crystal taken from the stable growth region; its ({mu}{tau}){sub e} value was 2.6 x 10{sup -3} cm{sup 2}/V, which is acceptable for thin detectors, including for applications in medicine.

Yang, G.; Bolotnikov, A.; Camarda, G.; Cui, Y.; Hossain, A.; Kim, K.; Carcelen, V.; Gul, R.; James, R.

2009-10-06

69

Computational Reconstruction of Iron- and Manganese-Responsive Transcriptional Networks in ?-Proteobacteria  

PubMed Central

We used comparative genomics to investigate the distribution of conserved DNA-binding motifs in the regulatory regions of genes involved in iron and manganese homeostasis in alpha-proteobacteria. Combined with other computational approaches, this allowed us to reconstruct the metal regulatory network in more than three dozen species with available genome sequences. We identified several classes of cis-acting regulatory DNA motifs (Irr-boxes or ICEs, RirA-boxes, Iron-Rhodo-boxes, Fur-alpha-boxes, Mur-box or MRS, MntR-box, and IscR-boxes) in regulatory regions of various genes involved in iron and manganese uptake, Fe-S and heme biosynthesis, iron storage, and usage. Despite the different nature of the iron regulons in selected lineages of alpha-proteobacteria, the overall regulatory network is consistent with, and confirmed by, many experimental observations. This study expands the range of genes involved in iron homeostasis and demonstrates considerable interconnection between iron-responsive regulatory systems. The detailed comparative and phylogenetic analyses of the regulatory systems allowed us to propose a theory about the possible evolution of Fe and Mn regulons in alpha-proteobacteria. The main evolutionary event likely occurred in the common ancestor of the Rhizobiales and Rhodobacterales, where the Fur protein switched to regulating manganese transporters (and hence Fur had become Mur). In these lineages, the role of global iron homeostasis was taken by RirA and Irr, two transcriptional regulators that act by sensing the physiological consequence of the metal availability rather than its concentration per se, and thus provide for more flexible regulation. PMID:17173478

Rodionov, Dmitry A; Gelfand, Mikhail S; Todd, Jonathan D; Curson, Andrew R. J; Johnston, Andrew W. B

2006-01-01

70

Association of arsenic, cadmium and manganese exposure with neurodevelopment and behavioural disorders in children: a systematic review and meta-analysis.  

PubMed

The aim of this study was to analyse the scientific evidence published to date on the potential effects on neurodevelopment and behavioural disorders in children exposed to arsenic, cadmium and manganese and to quantify the magnitude of the effect on neurodevelopment by pooling the results of the different studies. We conducted a systematic review of original articles from January 2000 until March 2012, that evaluate the effects on neurodevelopment and behavioural disorders due to pre or post natal exposure to arsenic, cadmium and manganese in children up to 16 years of age. We also conducted a meta-analysis assessing the effects of exposure to arsenic and manganese on neurodevelopment. Forty-one articles that evaluated the effects of metallic elements on neurodevelopment and behavioural disorders met the inclusion criteria: 18 examined arsenic, 6 cadmium and 17 manganese. Most studies evaluating exposure to arsenic (13 of 18) and manganese (14 of 17) reported a significant negative effect on neurodevelopment and behavioural disorders. Only two studies that evaluated exposure to cadmium found an association with neurodevelopmental or behavioural disorders. The results of our meta-analysis suggest that a 50% increase of arsenic levels in urine would be associated with a 0.4 decrease in the intelligence quotient (IQ) of children aged 5-15 years. Moreover a 50% increase of manganese levels in hair would be associated with a decrease of 0.7 points in the IQ of children aged 6-13 years. There is evidence that relates arsenic and manganese exposure with neurodevelopmental problems in children, but there is little information on cadmium exposure. Few studies have evaluated behavioural disorders due to exposure to these compounds, and manganese is the only one for which there is more evidence of the existence of association with attention deficit disorder with hyperactivity. PMID:23570911

Rodríguez-Barranco, Miguel; Lacasaña, Marina; Aguilar-Garduño, Clemente; Alguacil, Juan; Gil, Fernando; González-Alzaga, Beatriz; Rojas-García, Antonio

2013-06-01

71

STUDIES ON THE DETERMINATION OF TRACE OF ELEMENTS IN IRON AND STEELS. VII. SPECTROPHOTOMETRIC DETERMINATION OF MICRO AMOUNTS OF CADMIUM IN CAST IRON  

Microsoft Academic Search

An absorption photometric method for the determination of cadmium in ; cast iron by extraction as a dithizonate is described. The sample is decomposed ; by perchloric acid. After an addition of citric acid, ammonium hydroxide is ; added up to pH 9. Cadmium is extracted together with copper and nickel by ; dithizone --chloroform solution. From the extract, cadmium

S. Maekawa; Y. Yoneyama

1961-01-01

72

Cadmium exposure affects iron acquisition in barley (Hordeum vulgare) seedlings.  

PubMed

This study addresses the question of the interference between iron (Fe) nutrition and cadmium (Cd) toxicity at the level of growth performance, phytosiderophores (PS) release, micronutrient accumulation and expression of genes involved in Fe homeostasis in barley seedlings, a plant with strategy II-based response to Fe shortage. Cd exposure induced responses similar to those of genuine Fe deficiency also in Fe-sufficient plants. Most genes involved in PS biosynthesis and secretion (HvNAS3, HvNAS4, HvNAS6, HvNAS7, HvNAAT-A, HvDMAS1 and HvTOM1) induced by Fe deprivation were also significantly upregulated in the presence of Cd under Fe sufficient conditions. Accordingly, the enhanced expression of these genes in roots under Cd exposure was accompanied by an increase of PS release. However, induced expression of HvIRO2 and the downregulation of HvIDEF1 and HvIRT1, after Cd exposure, suggested the presence of a pathway that induces HvIRO2-mediated PS biosynthesis under Cd stress, which probably is not simply caused by Fe deficiency. The downregulation of HvIRT1 and HvNramp5 may represent a protective mechanism at transcriptional level against further Cd uptake by these transporters. These results likely indicate that Cd itself may be able to activate Fe acquisition mechanism in an Fe-independent manner. PMID:24724721

Astolfi, Stefania; Ortolani, Maria R; Catarcione, Giulio; Paolacci, Anna R; Cesco, Stefano; Pinton, Roberto; Ciaffi, Mario

2014-12-01

73

Manganese exposure among smelting workers: blood manganese-iron ratio as a novel tool for manganese exposure assessment  

PubMed Central

Unexposed control subjects (n = 106), power distributing and office workers (n = 122), and manganese (Mn)-exposed ferroalloy smelter workers (n = 95) were recruited to the control, low and high groups, respectively. Mn concentrations in saliva, plasma, erythrocytes, urine and hair were significantly higher in both exposure groups than in the controls. The Fe concentration in plasma and erythrocytes, however, was significantly lower in Mn-exposed workers than in controls. The airborne Mn levels were significantly associated with Mn/Fe ratio (MIR) of erythrocytes (eMIR) (r = 0.77, p < 0.01) and plasma (pMIR) (r = 0.70, p < 0.01). The results suggest that the MIR may serve as a useful biomarker to distinguish Mn-exposed workers from the unexposed, control population. PMID:19283519

Cowan, Dallas M.; Fan, Qiyuan; Zou, Yan; Shi, Xiujuan; Chen, Jian; Aschner, Michael; Rosenthal, Frank S.; Zheng, Wei

2014-01-01

74

Content of trace metals (iron, zinc, manganese, chromium, copper, nickel) in canned variegated scallops (Chlamys varia).  

PubMed

This article presents the results obtained through a study of the concentration of trace metals (iron, zinc, manganese, chromium, copper, nickel) in some conserves of variegated scallops (Chlamys varia, Bivalvia, Mollusca). A total of 300 samples of seven different commercial brands (named A, B, D, H, J, L and M) and one processing type, 'scallop sauce', were analysed. Samples were collected weekly in a large shopping centre in Santa Cruz de Tenerife during a 12-month period. Variegated scallops have considerable concentrations of zinc, cupper and manganese, so that their dietary intake constitutes an important source of these metals. However, they have low concentrations of chrome and nickel, and the levels of iron are similar to those found in other bivalve molluscs. PMID:19086337

Gutiérrez, Angel J; González-Weller, Dailos; González, Tomás; Burgos, Antonio; Lozano, Gonzalo; Hardisson, Arturo

2008-09-01

75

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

PubMed Central

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 [?-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) ?g/l. Women with any HFE variant allele had 12% lower blood manganese concentrations than women with no variant alleles (? = -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. PMID:22074419

2011-01-01

76

Kinetics of manganese oxide reduction from basic slags by carbon dissolved in liquid iron  

Microsoft Academic Search

The reduction of manganese oxide from a basic slag by carbon dissolved in liquid iron is a slow reaction, failing to approach\\u000a equilibrium closely in 20 hr. Furthermore, the rate of stirring has no apparent effect on the reaction rate. This identifies\\u000a the rate-controlling step as a chemical reaction at the interface. Only the model for the reactionO\\u000a 2? =O

Weldon L. Daines; Robert D. Pehlke

1971-01-01

77

Decrease of Manganese Superoxide Dismutase Activity in Rats Fed High Levels of Iron During Colon Carcinogenesis  

Microsoft Academic Search

Diets high in fat or iron have been associated with an increased risk for development of colon cancer. These two dietary factors are known to decrease manganese superoxide dismutase (MnSOD) activity in colonic mucosa. MnSOD is an antioxidant enzyme that protects mitochondria from oxygen radical damage. MnSOD has tumour suppressive activity and is absent or decreased in most tumours, including

C. N. Kuratko

1998-01-01

78

Limitation of marine phytoplankton reproductive rates by zinc, manganese, and iron1  

Microsoft Academic Search

The reproductive rates of 21 species of marine phytoplankton were measured in media in which free zinc, manganese, and iron ion activities were controlled at different levels using EDTA-trace metal ion buffer systems. In general, the reproductive rates of neritic species were limited by zinc activities below 1O-11.5 M, while those of oceanic species were either not limited or only

Larry E. Brand

1983-01-01

79

Plasma manganese, selenium, zinc, copper, and iron concentrations in patients with schizophrenia  

Microsoft Academic Search

A number of essential trace elements play a major role in various metabolic pathways. Selenium (Se), manganese (Mn), copper\\u000a (Cu), zinc (Zn), and iron (Fe) are essential trace elements that have been studied in many diseases, including autoimmune,\\u000a neurological, and psychiatric disorders. However, the findings of previous research on the status of trace elements in patients\\u000a with schizophrenia have been

Medaim Yanik; Abdurrahim Kocyigit; Hamdi Tutkun; Huseyin Vural; Hasan Herken

2004-01-01

80

Women with Fibromyalgia Have Lower Levels of Calcium, Magnesium, Iron and Manganese in Hair Mineral Analysis  

PubMed Central

Little is known about hair mineral status in fibromyalgia patients. This study evaluated the characteristics of hair minerals in female patients with fibromyalgia compared with a healthy reference group. Forty-four female patients diagnosed with fibromyalgia according to the American College of Rheumatology criteria were enrolled as the case group. Ageand body mass index-matched data were obtained from 122 control subjects enrolled during visit for a regular health check-up. Hair minerals were analyzed and compared between the two groups. The mean age was 43.7 yr. General characteristics were not different between the two groups. Fibromyalgia patients showed a significantly lower level of calcium (775 µg/g vs 1,093 µg/g), magnesium (52 µg/g vs 72 µg/g), iron (5.9 µg/g vs 7.1 µg/g), copper (28.3 µg/g vs 40.2 µg/g) and manganese (140 ng/g vs 190 ng/g). Calcium, magnesium, iron, and manganese were loaded in the same factor using factor analysis; the mean of this factor was significantly lower in fibromyalgia group in multivariate analysis with adjustment for potential confounders. In conclusion, the concentrations of calcium, magnesium, iron, and manganese in the hair of female patients with fibromyalgia are lower than of controls, even after adjustment of potential confounders. PMID:22022174

Kim, Young-Sang; Kim, Kwang-Min; Lee, Duck-Joo; Kim, Bom-Taeck; Park, Sat-Byul; Cho, Doo-Yeoun; Suh, Chang-Hee; Kim, Hyoun-Ah; Park, Rae-Woong

2011-01-01

81

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

PubMed

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. PMID:24013932

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

2013-12-01

82

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

NASA Technical Reports Server (NTRS)

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.

Nealson, K. H.; Saffarini, D.

1994-01-01

83

Characterization of cadmium manganese telluride (Cd1-xMnxTe) crystals grown by floating zone method  

NASA Astrophysics Data System (ADS)

Recently, Cadmium Manganese Telluride (CMT) emerged as a promising material for roomtemperature X- and gamma-ray detectors. However, our studies revealed several material defects primarily related to growth processes that are impeding the production of large single crystals with high resistivity and high mobility-lifetime product. In this work, we characterized various defects in materials grown by the floating zone method, including twins, Te inclusions, and dislocations, using our unique facilities. We also fabricated detectors from selected CMT crystals and tested their performance. This paper discusses our detailed findings on the material's properties and the performance of fabricated CMT detectors.

Hossain, A.; Gu, G. D.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Gul, R.; Roy, U. N.; Yang, G.; Liu, T.; Zhong, R.; Schneeloch, J.; James, R. B.

2014-09-01

84

Alteration of saliva and serum concentrations of manganese, copper, zinc, cadmium and lead among career welders  

PubMed Central

Human saliva offers a unique noninvasive approach for populational study. Purposes of this study were to investigate the feasibility of using saliva manganese (Mn) concentration as a biomarker of Mn exposure among career welders and to study the variations of Mn, copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) in saliva as affected by the welding profession. Forty-nine male welders, of whom 28 were in the low exposed group and 21 in the high exposed group, were recruited. Control subjects were 33 military soldiers without metal exposure. Ambient Mn levels in breathing zones were 0.01, 0.24 and 2.21 mg/m3for control, low, and high exposed groups, respectively. Saliva samples were collected to quantify metals by inductive coupled plasma mass spectrometer (ICP-MS). Saliva concentrations of Mn and Cu were significantly higher in welders than in controls (p < 0.01); the variation in saliva levels appeared likely to be associated with airborne Mn levels among study populations. Saliva levels of Zn were significantly lower in welders than in controls (p < 0.05), while Cd and Pb levels in saliva were unchanged. Significant associations were observed between saliva and serum for Mn (r = 0.575, p < 0.05) and Cu (r = 0.50, p < 0.05). Moreover, saliva Mn concentrations were higher among welders with 5–10 years of employment than those with less than 5 years of employment. Linear regression analysis revealed a significant correlation between saliva Mn and Cu and between saliva Mn and Zn. Taken together, these data suggest that Mn concentrations in saliva appear reflective of welders’ exposure to airborne Mn and their years of welding experience. respectively. Elevated Mn levels among welders may alter the homeostasis of Cu and Zn. PMID:18054180

Wang, Dixin; Du, Xuqin; Zheng, Wei

2014-01-01

85

Role of the node in controlling traffic of cadmium, zinc, and manganese in rice.  

PubMed

Heavy metals are transported to rice grains via the phloem. In rice nodes, the diffuse vascular bundles (DVBs), which enclose the enlarged elliptical vascular bundles (EVBs), are connected to the panicle and have a morphological feature that facilitates xylem-to-phloem transfer. To find a mechanism for restricting cadmium (Cd) transport into grains, the distribution of Cd, zinc (Zn), manganese (Mn), and sulphur (S) around the vascular bundles in node I (the node beneath the panicle) of Oryza sativa 'Koshihikari' were compared 1 week after heading. Elemental maps of Cd, Zn, Mn, and S in the vascular bundles of node I were obtained by synchrotron micro-X-ray fluorescence spectrometry and electron probe microanalysis. In addition, Cd K-edge microfocused X-ray absorption near-edge structure analyses were used to identify the elements co-ordinated with Cd. Both Cd and S were mainly distributed in the xylem of the EVB and in the parenchyma cell bridge (PCB) surrounding the EVB. Zn accumulated in the PCB, and Mn accumulated around the protoxylem of the EVB. Cd was co-ordinated mainly with S in the xylem of the EVB, but with both S and O in the phloem of the EVB and in the PCB. The EVB in the node retarded horizontal transport of Cd toward the DVB. By contrast, Zn was first stored in the PCB and then efficiently transferred toward the DVB. Our results provide evidence that transport of Cd, Zn, and Mn is differentially controlled in rice nodes, where vascular bundles are functionally interconnected. PMID:22291135

Yamaguchi, Noriko; Ishikawa, Satoru; Abe, Tadashi; Baba, Koji; Arao, Tomohito; Terada, Yasuko

2012-04-01

86

Role of the node in controlling traffic of cadmium, zinc, and manganese in rice  

PubMed Central

Heavy metals are transported to rice grains via the phloem. In rice nodes, the diffuse vascular bundles (DVBs), which enclose the enlarged elliptical vascular bundles (EVBs), are connected to the panicle and have a morphological feature that facilitates xylem-to-phloem transfer. To find a mechanism for restricting cadmium (Cd) transport into grains, the distribution of Cd, zinc (Zn), manganese (Mn), and sulphur (S) around the vascular bundles in node I (the node beneath the panicle) of Oryza sativa ‘Koshihikari’ were compared 1 week after heading. Elemental maps of Cd, Zn, Mn, and S in the vascular bundles of node I were obtained by synchrotron micro-X-ray fluorescence spectrometry and electron probe microanalysis. In addition, Cd K-edge microfocused X-ray absorption near-edge structure analyses were used to identify the elements co-ordinated with Cd. Both Cd and S were mainly distributed in the xylem of the EVB and in the parenchyma cell bridge (PCB) surrounding the EVB. Zn accumulated in the PCB, and Mn accumulated around the protoxylem of the EVB. Cd was co-ordinated mainly with S in the xylem of the EVB, but with both S and O in the phloem of the EVB and in the PCB. The EVB in the node retarded horizontal transport of Cd toward the DVB. By contrast, Zn was first stored in the PCB and then efficiently transferred toward the DVB. Our results provide evidence that transport of Cd, Zn, and Mn is differentially controlled in rice nodes, where vascular bundles are functionally interconnected. PMID:22291135

Yamaguchi, Noriko; Ishikawa, Satoru; Abe, Tadashi; Baba, Koji; Terada, Yasuko

2012-01-01

87

New Iron(II) and Manganese(II) Complexes of Two Ultra-Rigid, Cross-Bridged Tetraazamacrocycles for Catalysis and Biomimicry  

E-print Network

New Iron(II) and Manganese(II) Complexes of Two Ultra-Rigid, Cross-Bridged Tetraazamacrocycles abstraction reactions. Introduction Manganese and iron share with copper dominance over the vast realm iron-based oxidation catalysis while Mn catalase,5 mitochondrial superoxide dismu- tase,6

Hubin, Tim

88

Coprecipitation mechanisms and products in manganese oxidation in the presence of cadmium  

USGS Publications Warehouse

Manganese oxidation products were precipitated in an aerated open-aqueous system where a continuous influx of mixed Mn2+ and Cd2+ solution was supplied and pH was maintained with an automated pH-stat adding dilute NaOH. X-ray diffraction and electron diffraction identified the solids produced as mixtures of Cd2Mn34+O8, Mn2+2Mn4+3O8, MnO2 (ramsdellite), and CdCO3. Mean oxidation numbers of the total precipitated Mn as great as 3.6 were reached during titrations. During subsequent aging in solution, oxidation numbers between 3.8 and 3.9 were reached in some precipitates in less than 40 days. Conditional oxidation rate constants calculated from a crystal-growth equation applied to titration data showed the overall precipitation rate, without considering manganese oxidation state in the precipitate, was increased by a factor of ~4 to ~7 when the mole ratio (Cd/Mn + Cd) of cadmium in the feed solution was 0.40 compared with rate constants for hausmannite (Mn2+Mn23+O4 precipitation under similar conditions but without accessory metals. Kinetic experiments were made to test effects of various Cd/Mn + Cd mole ratios and rates of addition of the feed solution, different temperatures from 5.0 to 35??C, and pH from 8.0 to 9.0. Oxidation rates were slower when the Cd mole ratio was less than 0.40. The rate increased by a factor of ~10 when pH was raised one-half unit. The effect of temperature on the rate constants was also substantial, but the meaning of this is uncertain because the rate of formation of Mn4+ oxide in the absence of Cd or other accessory metals was too slow to be measurable in titration experiments. The increased rate of Mn4+ oxide formation in the presence of Cd2+ can be ascribed to the formation of a labile adsorbed intermediate, CdMn2O4 Int, an analog of hausmannite, formed on precipitate surfaces at the beginning of the oxidation process. The increased lability of this structure, resulting from coordination-chemical behavior of Cd2+ during the titration, causes a rapid second-stage rearrangement and facilitates disproportionation of the Mn3+ ions. The Mn2+ ions thus released provide a positive feedback mechanism that couples the two steps of the conversion of Mn2+ to Mn4+ more closely than is possible when other metal ions besides manganese are not present. During aging of precipitates in contact with solutions, proportions of Cd2Mn3O8 and MnO2 increased at the expense of other precipitate components. ?? 1991.

Hem, J.D.; Lind, C.J.

1991-01-01

89

Manganese  

MedlinePLUS

... no RDAs for a nutrient, the Adequate Intake (AI) is used as a guide. The AI is the estimated amount of the nutrient that ... assumed to be adequate. The daily Adequate Intake (AI) levels for manganese are: infants birth to 6 ...

90

Manganese and iron as indicators of the processes at the water column redox interfaces  

NASA Astrophysics Data System (ADS)

Investigations of the redox-interfaces structure were performed in the NE Black Sea (central and coastal parts) and Norwegian fjords (Bunnefjorden, Baerumsbassenget, Hunnbunn) in 2008-2009. Bunnefjorden is a 160 m deep anoxic basin, with flushing ones per several years, redox interface at about 90 m (aphotic zone); Baerumsbassenget is a 33 m deep permanent anoxic basin with redox interface positioned in the euphotic zone (15-20 m) subjected to the river input,; Hunnbunn is a 12 m deep permanent anoxic isolated inlet with a redox interface positioned in the euphotic zone (6 m) without influence of a river. Central Black Sea is an example of balanced redox-zone structure. Dissolved Mn(II) concentration start to increase when oxygen concentration goes down below the detection limit (<3 uM), dissolved Fe(II) - at more reduced conditions at appearance of hydrogen sulfide traces. Maximum of suspended manganese is situated at the beginning of the Mn(II) onset, maximum of dissolved bounded manganese (Mn(III)) - directly under suspended manganese. Coastal stations of the Black Sea are often characterized by irregularities of iron and manganese species distribution at normal distribution of other parameters. Such structure could arise as response to oxygen injection to this layer some time ago that is observed sometimes in coastal waters under river input, currents etc. It is known that different time is needed for different elements to return to stable equilibrium state. Perhaps such distribution is intermediate stage of system conversion to initial steady state when oxygen is already consumed and it is needed longer time for manganese/iron reduction as microbial processes. It was shown that redox zone structure in Bunnefjorden (90 m) is practically identical to the Black Sea both for absolute content of studied parameters and for its distribution shape. Redox zone structures of shallow basins Baerumsbassenget and Hunnbunn differ significantly from the Black Sea. Wide of redox zone in Baerumsbassenget varies from 2 to 9 m (2008, 2009). Redox zones of these two basins have reduced character that lead particularly to practically total disappearance of suspended manganese in samples in one day. Distribution of dissolved bounded manganese is enough chaotic in Baerumsbassenget. In Hunnbunn this manganese form was not found. It was noted that Mn(II) concentration started to increase at 7 uM of oxygen, 14 m depth, and manganese reduction in this zone must be an aerobic process. The highly organic nature of the water column in the fjords suggests that the breakdown of humic acids may be critical in the early redox cycling of manganese. All mentioned above concerns the iron cycle too. The appearance of Fe(II) started in the Baerumsbassenget and Hunnbunn not from the sulfidic boundary as in the Black Sea. It started both in the upper part of the suboxic layer, 1 m deeper than the disappearance of oxygen and at the same depth with manganese at oxic conditions. The primary factors influencing the redox cycling of elements in these basins are limited vertical advective-mediated mixing and the rates of microbially-mediated redox reactions across relatively stable oxic/anoxic boundaries. The flushing events, river input and increased mixing from time to time and anoxygenic photosynthesis play an important role in the formation of redox zone. These processes generally operate on time scales of hours to days to months and could have seasonal character. Response time for changes in the microbial processes involved in reduction and/or reoxidation of Mn and Fe lags behind that for oxygen injection into water. Concentrations of redox-sensitive species of Mn and Fe should thus be useful as a tracer to inter prior hypoxic/anoxic conditions not apparent from oxygen levels at the time of sampling.

Pakhomova, Svetlana; Yakushev, Evgeniy

2010-05-01

91

Sorption of ferric iron from ferrioxamine B to synthetic and biogenic layer type manganese oxides  

NASA Astrophysics Data System (ADS)

Siderophores are biogenic chelating agents produced in terrestrial and marine environments that increase the bioavailability of ferric iron. Recent work has suggested that both aqueous and solid-phase Mn(III) may affect siderophore-mediated iron transport, but scant information appears to be available about the potential roles of layer type manganese oxides, which are relatively abundant in soils and the oligotrophic marine water column. To probe the effects of layer type manganese oxides on the stability of aqueous Fe-siderophore complexes, we studied the sorption of ferrioxamine B [Fe(III)HDFOB +, an Fe(III) chelate of the trihydroxamate siderophore desferrioxamine B (DFOB)] to two synthetic birnessites [layer type Mn(III,IV) oxides] and a biogenic birnessite produced by Pseudomonas putida GB-1. We found that all of these predominantly Mn(IV) oxides greatly reduced the aqueous concentration of Fe(III)HDFOB + at pH 8. Analysis of Fe K-edge EXAFS spectra indicated that a dominant fraction of Fe(III) associated with the Mn(IV) oxides is not complexed by DFOB as in solution, but instead Fe(III) is specifically adsorbed to the mineral structure at multiple sites, thus indicating that the Mn(IV) oxides displaced Fe(III) from the siderophore complex. These results indicate that layer type manganese oxides, including biogenic minerals, may sequester iron from soluble ferric complexes. We conclude that the sorption of iron-siderophore complexes may play a significant role in the bioavailability and biogeochemical cycling of iron in marine and terrestrial environments.

Duckworth, Owen W.; Bargar, John R.; Sposito, Garrison

2008-07-01

92

Iron Acquisition by Phytosiderophores Contributes to Cadmium Tolerance1[OA  

PubMed Central

Based on the ability of phytosiderophores to chelate other heavy metals besides iron (Fe), phytosiderophores were suggested to prevent graminaceous plants from cadmium (Cd) toxicity. To assess interactions between Cd and phytosiderophore-mediated Fe acquisition, maize (Zea mays) plants were grown hydroponically under limiting Fe supply. Exposure to Cd decreased uptake rates of 59Fe(III)-phytosiderophores and enhanced the expression of the Fe-phytosiderophore transporter gene ZmYS1 in roots as well as the release of the phytosiderophore 2?-deoxymugineic acid (DMA) from roots under Fe deficiency. However, DMA hardly mobilized Cd from soil or from a Cd-loaded resin in comparison to the synthetic chelators diaminetriaminepentaacetic acid and HEDTA. While nano-electrospray-high resolution mass spectrometry revealed the formation of an intact Cd(II)-DMA complex in aqueous solutions, competition studies with Fe(III) and zinc(II) showed that the formed Cd(II)-DMA complex was weak. Unlike HEDTA, DMA did not protect yeast (Saccharomyces cerevisiae) cells from Cd toxicity but improved yeast growth in the presence of Cd when yeast cells expressed ZmYS1. When supplied with Fe-DMA as a Fe source, transgenic Arabidopsis (Arabidopsis thaliana) plants expressing a cauliflower mosaic virus 35S-ZmYS1 gene construct showed less growth depression than wild-type plants in response to Cd. These results indicate that inhibition of ZmYS1-mediated Fe-DMA transport by Cd is not related to Cd-DMA complex formation and that Cd-induced phytosiderophore release cannot protect maize plants from Cd toxicity. Instead, phytosiderophore-mediated Fe acquisition can improve Fe uptake in the presence of Cd and thereby provides an advantage under Cd stress relative to Fe acquisition via ferrous Fe. PMID:17337530

Meda, Anderson R.; Scheuermann, Enrico B.; Prechsl, Ulrich E.; Erenoglu, Bulent; Schaaf, Gabriel; Hayen, Heiko; Weber, Gunther; von Wiren, Nicolaus

2007-01-01

93

THE EFFECTS OF IRON(II) ON ARSENIC(III) OXIDATION AND ARSENIC SORPTION/DESORPTION ON MANGANESE OXIDES  

E-print Network

THE EFFECTS OF IRON(II) ON ARSENIC(III) OXIDATION AND ARSENIC SORPTION/DESORPTION ON MANGANESE � 2014 Yun Wu All Rights Reserved #12;THE EFFECTS OF IRON(II) ON ARSENIC(III) OXIDATION AND ARSENIC, Caroline Golt on arsenic speciation and UD Soil Test Lab. I thank all current and previous members

Sparks, Donald L.

94

Iron depletion increases manganese uptake and potentiates apoptosis through ER stress  

PubMed Central

Iron deficiency is a risk factor for manganese (Mn) accumulation. Excess Mn promotes neurotoxicity but the mechanisms involved and whether iron depletion might affect these pathways is unknown. To study Mn intoxication in vivo, iron deficient and control rats were intranasally instilled with 60 mg MnCl2/kg over 3 weeks. TUNEL staining of olfactory tissue revealed that Mn exposure induced apoptosis and that iron deficiency potentiated this effect. In vitro studies using the dopaminergic SH-SY5Y cell line confirmed that Mn-induced apoptosis was enhanced by iron depletion using the iron chelator desferrioxamine. Mn has been reported to induce apoptosis through endoplasmic reticulum stress. In SH-SY5Y cells, Mn exposure induced the ER stress genes glucose regulated protein 94 (GRP94) and C/EBP homologous protein (CHOP). Increased phosphorylation of the eukaryotic translation initiation factor 2? (phospho-eIF2?) was also observed. These effects were accompanied by the activation of ER resident enzyme caspase-12, and the downstream apoptotic effector caspase-3 was also activated. All of the Mn-induced responses were enhanced by DFO treatment. Inhibitors of ER stress and caspases significantly blocked Mn-induced apoptosis and its potentiation by DFO, indicating that ER stress and subsequent caspase activation underlie cell death. Taken together, these data reveal that Mn induces neuronal cell death through ER stress and the UPR response pathway and that this apoptotic effect is potentiated by iron deficiency most likely through upregulation of DMT1. PMID:23764342

Seo, Young Ah; Li, Yuan; Wessling-Resnick, Marianne

2013-01-01

95

Cadmium toxicity induced alterations in the root proteome of green gram in contrasting response towards iron supplement.  

PubMed

Cadmium signifies a severe threat to crop productivity and green gram is a notably iron sensitive plant which shows considerable variation towards cadmium stress. A gel-based proteomics analysis was performed with the roots of green gram exposed to iron and cadmium combined treatments. The resulting data show that twenty three proteins were down-regulated in iron-deprived roots either in the absence (-Fe/-Cd) or presence (-Fe/+Cd) of cadmium. These down-regulated proteins were however well expressed in roots under iron sufficient conditions, even in the presence of cadmium (+Fe/+Cd). The functional classification of these proteins determined that 21% of the proteins are associated with nutrient metabolism. The other proteins in higher quantities are involved in either transcription or translation regulation, and the rest are involved in biosynthesis metabolism, antioxidant pathways, molecular chaperones and stress response. On the other hand, several protein spots were also absent in roots in response to iron deprivation either in absence (-Fe/-Cd) or presence (-Fe/+Cd) of cadmium but were well expressed in the presence of iron (+Fe/+Cd). Results suggest that green gram plants exposed to cadmium stress are able to change the nutrient metabolic balance in roots, but in the mean time regulate cadmium toxicity through iron supplements. PMID:24739807

Muneer, Sowbiya; Hakeem, Khalid Rehman; Mohamed, Rozi; Lee, Jeong Hyun

2014-01-01

96

Cadmium Toxicity Induced Alterations in the Root Proteome of Green Gram in Contrasting Response towards Iron Supplement  

PubMed Central

Cadmium signifies a severe threat to crop productivity and green gram is a notably iron sensitive plant which shows considerable variation towards cadmium stress. A gel-based proteomics analysis was performed with the roots of green gram exposed to iron and cadmium combined treatments. The resulting data show that twenty three proteins were down-regulated in iron-deprived roots either in the absence (?Fe/?Cd) or presence (?Fe/+Cd) of cadmium. These down-regulated proteins were however well expressed in roots under iron sufficient conditions, even in the presence of cadmium (+Fe/+Cd). The functional classification of these proteins determined that 21% of the proteins are associated with nutrient metabolism. The other proteins in higher quantities are involved in either transcription or translation regulation, and the rest are involved in biosynthesis metabolism, antioxidant pathways, molecular chaperones and stress response. On the other hand, several protein spots were also absent in roots in response to iron deprivation either in absence (?Fe/?Cd) or presence (?Fe/+Cd) of cadmium but were well expressed in the presence of iron (+Fe/+Cd). Results suggest that green gram plants exposed to cadmium stress are able to change the nutrient metabolic balance in roots, but in the mean time regulate cadmium toxicity through iron supplements. PMID:24739807

Muneer, Sowbiya; Hakeem, Khalid Rehman; Mohamed, Rozi; Lee, Jeong Hyun

2014-01-01

97

Arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in feathers of Black-legged Kittiwake ( Rissa tridactyla) and Black Oystercatcher ( Haematopus bachmani) from Prince William Sound, Alaska  

Microsoft Academic Search

Arsenic, cadmium, chromium, lead, manganese, mercury and selenium were analyzed in the feathers of Black-legged Kittiwakes (Rissa tridactyla) from Shoup Bay in Prince William Sound, Alaska to determine if there were age-related differences in metal levels, and in Black Oystercatchers (Haematopus bachmani)) from the same region to determine if there were differences in oiled and unoiled birds. Except for mercury,

Joanna Burger; Michael Gochfeld; Kelsey Sullivan; David Irons; Aly McKnight

2008-01-01

98

The freshwater river crab, Potamonautes warreni, as a bioaccumulative indicator of iron and manganese pollution in two aquatic systems.  

PubMed

The aim of this study was to determine the potential use of the freshwater river crab, Potamonautes warreni, as a bioaccumulative indicator of iron and manganese pollution in aquatic ecosystems. Water and sediment analysis of the two study sites (Germiston Lake and Potchefstroom Dam) revealed that while levels of manganese were higher in Germiston Lake, iron concentrations were higher in Potchefstroom Dam. Metal analysis of P. warreni revealed that while the crabs from Potchefstroom Dam contained slightly higher iron levels than those from Germiston Lake, manganese concentrations in P. warreni from the latter site were significantly higher than those in the crabs from the former site. Iron and manganese levels in these organisms were influenced by the size, mass, and sex of the crabs on occasion, but these relationships were not always consistent at both of the sites. The results of this study clearly indicate that the ultimate levels of iron and manganese attained in P. warreni do vary depending on the site from which animals are collected. From this, it is suggested that these crustaceans be incorporated into biomonitoring protocols, particularly in areas that are subjected to elevated metal levels in the environment PMID:9756709

Sanders, M J; Du Preez, H H; Van Vuren, J H

1998-10-01

99

Journal of the Geological Society, London, Vol. 168, 2011, pp. 805815. doi: 10.1144/0016-76492010-132. Hydrothermal origin of elevated iron, manganese and redox-sensitive trace  

E-print Network

.1144/0016-76492010-132. 805 Hydrothermal origin of elevated iron, manganese and redox-sensitive trace elements in the c. 635 that has been recently noted but not adequately studied is the high concentration of iron (Fe), manganese

Jiang, Ganqing

100

Significance of concentrations of lead, cadmium, and iron in the plumage of the feral pigeon  

Microsoft Academic Search

Lead, cadmium, and iron contamination was examined in the plumage of feral pigeons. Metal contamination in pigeons from different regions in Bratislava or in different seasons did not differ significantly; seasonal type of food did not significantly influence the concentrations. The blood of birds was examined for the presence of complement fixing antibodies toChlamydia psittaci. Birds with antibodies did not

Marifin Janiga; Blanka Mafikovskfi; Monika Bobal'ová; Gabriela ?ur?ová

1990-01-01

101

Growth and Dissolution of Iron and Manganese Oxide Films  

SciTech Connect

Growth and dissolution of Fe and Mn oxide films are key regulators of the fate and transport of heavy metals in the environment, especially during changing seasonal conditions of pH and dissolved oxygen. The Fe and Mn are present at much higher concentrations than the heavy metals, and, when Fe and Mn precipitate as oxide films, heavy metals surface adsorb or co-precipitate and are thus essentially immobilized. Conversely, when the Fe and Mn oxide films dissolve, the heavy metals are released to aqueous solution and are thus mobilized for transport. Therefore, understanding the dynamics and properties of Fe and Mn oxide films and thus on the uptake and release of heavy metals is critically important to any attempt to develop mechanistic, quantitative models of the fate, transport, and bioavailablity of heavy metals. A primary capability developed in our earlier work was the ability to grow manganese oxide (MnO{sub x}) films on rhodochrosite (MnCO{sub 3}) substrate in presence of dissolved oxygen under mild alkaline conditions. The morphology of the films was characterized using contact-mode atomic force microscopy. The initial growth began by heteroepitaxial nucleation. The resulting films had maximum heights of 1.5 to 2 nm as a result of thermodynamic constraints. Over the three past years, we have investigated the effects of MnO{sub x} growth on the interactions of MnCO{sub 3} with charged ions and microorganisms, as regulated by the surface electrical properties of the mineral. In 2006, we demonstrated that MnO{sub x} growth could induce interfacial repulsion and surface adhesion on the otherwise neutral MnCO{sub 3} substrate under environmental conditions. Using force-volume microscopy (FVM), we measured the interfacial and adhesive forces on a MnO{sub x}/MnCO{sub 3} surface with a negatively charged silicon nitride tip in a 10-mM NaNO3 solution at pH 7.4. The interfacial force and surface adhesion of MnOx were approximately 40 pN and 600 pN, respectively, whereas those of MnCO{sub 3} were essentially zero. The force differences between MnO{sub x} and MnCO{sub 3} suggest that oxide film growth can focus adsorbates to certain parts of the surface and thereby templating a heterogeneous layout of them. We suspected that the force differences were in part due to the differences in surface electrical properties. In 2007, we investigated two important electrical properties of MnO{sub x} and MnCO{sub 3} surfaces, namely surface potential and ion mobility. Surface potential is a composite quantity that can be linked to the local lattice structure of the reconstructed surface and the adsorption of water layers. The mobile surface ions formed by dissolution can also contribute to surface potential. Using Kelvin probe force microscopy (KPFM) and scanning polarization force microscopy (SPFM), we found that MnOx possessed excess surface potentials of over +200 mV in humid nitrogen and the excess surface potential decreased with increasing relative humidity (i.e., increasing adsorbed water layers on the mineral surface). The dependence of the excess surface potential was attributed to the change of the contributions from mobile ions. These results supported our earlier hypothesis that MnO{sub x} and MnCO{sub 3} had different surface electrical properties. In the third year, we systematically characterized that the change of the electrical double layer (EDL) structure of MnCO{sub 3} surface due to MnO{sub x} growth in aqueous solution and its dependence on pH. The structure of the electrical double layer determines the electrostatic interactions between the mineral surface and charged adsorbates. As described by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the electrostatic force, together with van der Waals interaction, regulates surface adsorption and bacterial attachment. Once adsorbates establish contact with the surface, they must resist hydraulic shear forces through surface adhesion. The adhesion of mineral surfaces is also affected by their electrostatic interactions with adsorbates. To probe the EDL structure, we ap

Scot T. Martin

2008-12-22

102

Manganese transport across the blood-brain barrier: relationship to iron homeostasis.  

PubMed

The binding characteristics of manganese (Mn) to transferrin (Tf) were examined on G-75 Sephadex gel columns. When 54MnCl2 was combined with Tf and immediately fractionated on the Sephadex column, 49% of 54Mn was found to Tf. The fraction of 54Mn which was Tf-bound was dependent upon the incubation period, and increased in a time-dependent fashion. In vivo, 6 hr of intravenous administration of ferric-hydroxide dextran complex significantly inhibited (p less than 0.05) 54Mn brain uptake as compared to its uptake in iron-free dextran-treated rats. These results suggest that iron (Fe) homeostasis may play an important role in the regulation of Mn transport across the blood-brain barrier (BBB). PMID:2372703

Aschner, M; Aschner, J L

1990-06-01

103

Environmentally acquired lead, cadmium, and manganese in the cattle egret, Bubulcus ibis, and the laughing gull, Larus atricilla.  

PubMed

The concentrations of lead, cadmium, and manganese in the tissues of cattle egrets (Bubulcus ibis) and laughing gulls (Larus atricilla) gathered from the Galveston Bay region of Texas were compared, to determine if different patterns of accumulation exist. Their levels in these species were within the range reported for other bird species. Lead levels in bone were comparable, but gulls had more lead in brain, kidney and liver tissues than the egrets, which suggested a higher rate of accumulation or exposure. Due to their high abundance and comparable positions in the estaurine and terrestrial food webs, it is suggested that Bubulcus ibis and Larus atricilla may serve as convenient biological indicators to monitor potentially toxic substances in these ecosystems. PMID:7189395

Hulse, M; Mahoney, J S; Schroder, G D; Hacker, C S; Pier, S M

1980-01-01

104

The proteome of copper, iron, zinc, and manganese micronutrient deficiency in Chlamydomonas reinhardtii.  

PubMed

Trace metals such as copper, iron, zinc, and manganese play important roles in several biochemical processes, including respiration and photosynthesis. Using a label-free, quantitative proteomics strategy (MS(E)), we examined the effect of deficiencies in these micronutrients on the soluble proteome of Chlamydomonas reinhardtii. We quantified >10(3) proteins with abundances within a dynamic range of 3 to 4 orders of magnitude and demonstrated statistically significant changes in ~200 proteins in each metal-deficient growth condition relative to nutrient-replete media. Through analysis of Pearson's coefficient, we also examined the correlation between protein abundance and transcript abundance (as determined via RNA-Seq analysis) and found moderate correlations under all nutritional states. Interestingly, in a subset of transcripts known to significantly change in abundance in metal-replete and metal-deficient conditions, the correlation to protein abundance is much stronger. Examples of new discoveries highlighted in this work include the accumulation of O(2) labile, anaerobiosis-related enzymes (Hyd1, Pfr1, and Hcp2) in copper-deficient cells; co-variation of Cgl78/Ycf54 and coprogen oxidase; the loss of various stromal and lumenal photosynthesis-related proteins, including plastocyanin, in iron-limited cells; a large accumulation (from undetectable amounts to over 1,000 zmol/cell) of two COG0523 domain-containing proteins in zinc-deficient cells; and the preservation of photosynthesis proteins in manganese-deficient cells despite known losses in photosynthetic function in this condition. PMID:23065468

Hsieh, Scott I; Castruita, Madeli; Malasarn, Davin; Urzica, Eugen; Erde, Jonathan; Page, M Dudley; Yamasaki, Hiroaki; Casero, David; Pellegrini, Matteo; Merchant, Sabeeha S; Loo, Joseph A

2013-01-01

105

Influence of iron overload on manganese, zinc, and copper concentration in rat tissues in vivo: study of liver, spleen, and brain.  

PubMed

Although hemochromatosis and pathological situations due to chronic iron overload have been extensively described, there is little information about the influence of iron on other trace elements in the cell. The aim of this study was to investigate changes in the concentration of zinc, manganese, and copper in the liver, spleen, and brain of rats after iron overload. Iron overload in Wistar rats was achieved by iron-supplemented diet or by intraperitoneal or intravenous injection of polymaltose iron. Iron, zinc, manganese, and copper were determined by atomic absorption spectrophotometry. Iron overload in rats, regardless of the route of its application, resulted in an increase not only of iron but also of zinc and manganese in the liver and the spleen, whereas the content of these metals in the brain did not change. The copper content of the liver, spleen, and brain remained the same after iron overload. The increase of zinc and manganese in the liver and spleen following iron overload was probably a result not only of increased intestinal absorption but also of increased uptake from the cell. This is also supported by the fact that no increase in the zinc and manganese concentrations occurred in the brain since, despite iron overload, the iron content remained constant. PMID:9801930

Vayenas, D V; Repanti, M; Vassilopoulos, A; Papanastasiou, D A

1998-01-01

106

Investigation of the influence of cadmium processing on zinc gallium oxide:manganese thin films for photoluminescent and thin film electroluminescent applications  

NASA Astrophysics Data System (ADS)

Cadmium processing of ZnGa2O4 films provides a new fabrication route for phosphor powders and thin films. It relies on the enhanced diffusion due to the large vacancy concentration left by the sublimation of cadmium. Photoluminescent powders can be made with a single high temperature firing. Thin film devices can be processed at a significantly lower temperature, expanding the range of available substrates. Powders and thin films of ZnGa2O4:Mn were fabricated using starting materials in which between 0% and 50% of the ZnO was substituted by CdO. It was found that the emission spectra of the various compositions was unaffected by the change in composition, peaking at 504 nm, with the colour coordinates x = 0.08 and y = 0.69. The invariance of the emission spectrum is due to the spinel crystal structure exhibited by the compound. However, the maximum PL brightness was obtained from powders in which 10% of the ZnO had been substituted by CdO in the starting materials. The improved brightness is the result of better manganese incorporation which resulted from CdO sublimation during processing. This left a large vacancy concentration which enhanced the diffusion, and hence the manganese incorporation. In the case of thin films sputtered from cadmium processed targets, the composition of the films as deposited closely mirrored that of the target starting materials. The as deposited films were not luminescent and had to be annealed in vacuum in order to activate the manganese. EDX of these films showed that all of the cadmium had sublimed during the anneal. Very long anneal times also resulted in the loss of zinc. The decomposition products were amorphous or nanocrystalline. These films had an identical PL emission to the powders. The loss of cadmium correlated with the onset of bright 254 nm photoluminescence in the films, indicating that cadmium loss aided in the activation of the manganese. This was the result of the enhanced diffusion due to the large vacancy concentration left by the sublimed material, which aided the incorporation and activation of the manganese. The cadmium in the sputtering targets also impacted the crystal structure of the films. Films from cadmium free targets exhibited a strong (111) x-ray diffraction peak, while those from cadmium processed targets more closely resembled the powder structure. The optimum thin film electroluminescent performance was obtained for films sputtered from targets processed with between 5% and 15% cadmium substituted for zinc. This was the result of improved diffusion during the anneals, due to the sublimation of cadmium oxide and the resulting large vacancy concentration. The best performance was obtained for films annealed at between 875°C and 900°C for 6--12 hours. These films exhibited both the maximum luminance (55 cd/m2 at 60 Hz) and the lowest transferred charge (˜20 muC/cm2). This combined for a peak efficiency of 0.5 lm/W at 60 Hz). Beyond 12 hours at 900°C or temperatures higher than this, EL performance degraded due to the decomposition of the thin film. It was concluded that the luminescent performance of this material is strongly influenced by the loss of cadmium during processing. The enhanced diffusion afforded by the cadmium sublimation results in improved EL performance at annealing temperature lower that that of pure zinc gallate.

Flynn, Michael John

107

Borrelia burgdorferi, a Pathogen That Lacks Iron, Encodes Manganese-dependent Superoxide Dismutase Essential for Resistance to Streptonigrin*  

PubMed Central

Borrelia burgdorferi, the causative agent of Lyme disease, exists in nature through a complex life cycle involving ticks of the Ixodes genus and mammalian hosts. During its life cycle, B. burgdorferi experiences fluctuations in oxygen tension and may encounter reactive oxygen species (ROS). The key metalloenzyme to degrade ROS in B. burgdorferi is SodA. Although previous work suggests that B. burgdorferi SodA is an iron-dependent superoxide dismutase (SOD), later work demonstrates that B. burgdorferi is unable to transport iron and contains an extremely low intracellular concentration of iron. Consequently, the metal cofactor for SodA has been postulated to be manganese. However, experimental evidence to support this hypothesis remains lacking. In this study, we provide biochemical and genetic data showing that SodA is a manganese-dependent enzyme. First, B. burgdorferi contained SOD activity that is resistant to H2O2 and NaCN, characteristics associated with Mn-SODs. Second, the addition of manganese to the Chelex-treated BSK-II enhanced SodA expression. Third, disruption of the manganese transporter gene bmtA, which significantly lowers the intracellular manganese, greatly reduced SOD activity and SodA expression, suggesting that manganese regulates the level of SodA. In addition, we show that B. burgdorferi is resistant to streptonigrin, a metal-dependent redox cycling compound that produces ROS, and that SodA plays a protective role against the streptonigrin. Taken together, our data demonstrate the Lyme disease spirochete encodes a manganese-dependent SOD that contributes to B. burgdorferi defense against intracellular superoxide. PMID:22500025

Troxell, Bryan; Xu, Haijun; Yang, X. Frank

2012-01-01

108

Borrelia burgdorferi, a pathogen that lacks iron, encodes manganese-dependent superoxide dismutase essential for resistance to streptonigrin.  

PubMed

Borrelia burgdorferi, the causative agent of Lyme disease, exists in nature through a complex life cycle involving ticks of the Ixodes genus and mammalian hosts. During its life cycle, B. burgdorferi experiences fluctuations in oxygen tension and may encounter reactive oxygen species (ROS). The key metalloenzyme to degrade ROS in B. burgdorferi is SodA. Although previous work suggests that B. burgdorferi SodA is an iron-dependent superoxide dismutase (SOD), later work demonstrates that B. burgdorferi is unable to transport iron and contains an extremely low intracellular concentration of iron. Consequently, the metal cofactor for SodA has been postulated to be manganese. However, experimental evidence to support this hypothesis remains lacking. In this study, we provide biochemical and genetic data showing that SodA is a manganese-dependent enzyme. First, B. burgdorferi contained SOD activity that is resistant to H(2)O(2) and NaCN, characteristics associated with Mn-SODs. Second, the addition of manganese to the Chelex-treated BSK-II enhanced SodA expression. Third, disruption of the manganese transporter gene bmtA, which significantly lowers the intracellular manganese, greatly reduced SOD activity and SodA expression, suggesting that manganese regulates the level of SodA. In addition, we show that B. burgdorferi is resistant to streptonigrin, a metal-dependent redox cycling compound that produces ROS, and that SodA plays a protective role against the streptonigrin. Taken together, our data demonstrate the Lyme disease spirochete encodes a manganese-dependent SOD that contributes to B. burgdorferi defense against intracellular superoxide. PMID:22500025

Troxell, Bryan; Xu, Haijun; Yang, X Frank

2012-06-01

109

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

PubMed

A new chemolithotrophic bacterial metabolism was discovered in anaerobic marine enrichment cultures. Cultures in defined medium with elemental sulfur (S) 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 S was microbially disproportionated to sulfate and sulfide, as follows: 4S + 4H(2)O --> SO(4) + 3H(2)S + 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 FeCO(3). Further enrichment with manganese oxide, MnO(2), instead of FeOOH yielded stable cultures which formed sulfate during concomitant 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 sulfide oxidation to sulfate in anoxic sediments. PMID:16348835

Thamdrup, B; Finster, K; Hansen, J W; Bak, F

1993-01-01

110

Changes in Fractions of Iron, Manganese, Copper, and Zinc in Soil under Continuous Cropping for More Than Three Decades  

Microsoft Academic Search

The effect of continuous cropping with maize and wheat on soil characteristics and various forms of micronutrient cations in an Incetisol over the years was studied in an ongoing long?term experiment in New Delhi, India. The soil samples collected in the years of 1993, 1995, 1997, 1999, 2001, 2003, and 2004 were analyzed for different fractions of iron (Fe), manganese

Sanjib Kumar Behera; Dhyan Singh; Brahma Swaroop Dwivedi

2009-01-01

111

Preparative and Structural Studies on the Carbonyl Cyanides of Iron, Manganese, and Ruthenium: Fundamentals Relevant to the  

E-print Network

Preparative and Structural Studies on the Carbonyl Cyanides of Iron, Manganese, and Ruthenium 61801 Received October 4, 2001 The reaction of cyanide, carbon monoxide, and ferrous derivatives led. Introduction While cyanide is often discussed in terms of its -acceptor properties, the most dominant

Rauchfuss, Thomas B.

112

Arsenic, Iron, Lead, Manganese and Uranium Concentrations in Private Bedrock Wells in Southeastern New Hampshire, 2012-2013  

EPA Science Inventory

Trace metals, such as arsenic, iron, lead, manganese, and uranium, in groundwater used for drinking have long been a concern because of the potential adverse effects on human health and the aesthetic or nuisance problems that some present. Moderate to high concentrations of the t...

113

SOLID PHASE SPECIATION OF IRON AND MANGANESE IN ALUM SHALE SOILS STUDIED BY PARALLEL AND SEQUENTIAL EXTRACTION  

Microsoft Academic Search

The kind of association of heavy metals with soil components determines the mobility and availability of metals in soils. It is, therefore, necessary to understand and differentiate the different physicochemical forms of metals. A laboratory study was conducted to investigate the solubility of iron (Fe) and manganese (Mn) and their association with soil components by the newly developed sequential extraction

R. P. Narwall; B. R. Singh

2001-01-01

114

Validation of In-Situ Iron-Manganese Oxide Coated Stream Pebbles as Sensors for Arsenic Source Monitoring  

NASA Astrophysics Data System (ADS)

Locating nonpoint source contaminant fluxes can be challenging due to the inherent heterogeneity of source and of the subsurface. Contaminants such as arsenic are a concern for drinking water quality and ecosystem health. Arsenic contamination can be the result of several natural and anthropogenic sources, and therefore it can be difficult to trace and identify major areas of arsenic in natural systems. Identifying a useful source indicator for arsenic is a crucial step for environmental remediation efforts. Previous studies have found iron-manganese oxide coated streambed pebbles as useful source indicators due to their high attraction for heavy metals in water. In this study, pebbles, surface water at baseflow and nearby rocks were sampled from the Pennypack Creek and its tributaries, in southwestern Pennsylvania, to test the ability of coated streambed pebbles as environmental source indicators for arsenic. Quartz pebbles, 5-7 cm in diameter, were sampled to minimize elemental contamination from rock chemistry. In addition, quartz provides an excellent substrate for iron and manganese coatings to form. These coatings were leached from pebbles using 4M nitric acid with 0.1% concentrated hydrochloric acid. Following sample processing, analyses were performed using an ICP-MS and the resulting data were spatially organized using ArcGIS software. Arsenic, iron and manganese concentrations in the leachate are normalized to pebble surface area and each location is reported as a ratio of arsenic to iron and manganese. Results suggest that iron-manganese coated stream pebbles are useful indicators of arsenic location within a watershed.

Blake, J.; Peters, S. C.; Casteel, A.

2013-12-01

115

Assessment of metals in down feathers of female common eiders and their eggs from the Aleutians: arsenic, cadmium, chromium, lead, manganese, mercury, and selenium  

Microsoft Academic Search

Concentrations of arsenic, cadmium, chromium, lead, manganese, mercury and selenium were examined in the down feathers and\\u000a eggs of female common eiders (Somateria mollissima) from Amchitka and Kiska Islands in the Aleutian Chain of Alaska to determine whether there were (1) differences between\\u000a levels in feathers and eggs, (2) differences between the two islands, (3) positive correlations between metal levels

Joanna Burger; Michael Gochfeld; Christian Jeitner; Daniel Snigaroff; Ronald Snigaroff; Timothy Stamm; Conrad Volz

2008-01-01

116

Novel processing of iron-manganese alloy-based biomaterials by inkjet 3-D printing.  

PubMed

The present work provides an assessment of 3-D printed iron-manganese biodegradable scaffolds as a bone scaffold material. Iron-based alloys have been investigated due to their high strength and ability to slowly corrode. Current fabrications of Fe-based materials generate raw material which must be machined into their desired form. By using inkjet 3-D printing, a technique which generates complex, customizable parts from powders mechanically milled Fe-30Mn (wt.%) powder was directly processed into scaffolds. The 3-D printed parts maintained an open porosity of 36.3% and formed a mixed phase alloy of martensitic ? and austenitic ? phases. Electrochemical corrosion tests showed the 3-D printed Fe-Mn to desirably corrode significantly more rapidly than pure iron. The scaffolds exhibited similar tensile mechanical properties to natural bone, which may reduce the risk of stress shielding. Cell viability testing of MC3T3-E1 pre-osteoblast cells seeded directly onto the Fe-Mn scaffolds using the live/dead assay and with cells cultured in the presence of the scaffolds' degradation products demonstrated good in vitro cytocompatibility compared to tissue culture plastic. Cell infiltration into the open pores of the 3-D printed scaffolds was also observed. Based on this preliminary study, we believe that 3-D printed Fe-Mn alloy is a promising material for craniofacial biomaterial applications, and represents an opportunity for other biodegradable metals to be fabricated using this unique method. PMID:23624222

Chou, Da-Tren; Wells, Derrick; Hong, Daeho; Lee, Boeun; Kuhn, Howard; Kumta, Prashant N

2013-11-01

117

Plant Uptake of Cadmium, Zinc, and Manganese in Soils Amended with Sewage Sludge and City Compost  

Microsoft Academic Search

presence of which in agricultural soils and crops is of great concern. Naturally occurring Cd concentration in soils which ranges from 0.01 to 7 ppm (Allaway, 1968) may rise to higher concentrations as a result of aerial deposition, irrigation with contaminated water, the application of sewage-based fertilizers, pesticides containing wastes from mining, metallurgical, industrial or urban activities. Cadmium may accumulate

V. Ramachandran; T. J. D'Souza

1998-01-01

118

OsNRAMP5, a major player for constitutive iron and manganese uptake in rice.  

PubMed

Manganese (Mn) and iron (Fe) are essential mineral micronutrients for plants and their deficiency and or toxicity represents a serious agricultural problem. In rice the information about genes involved in Mn uptake from soil is scarce. Recently, we showed that OsNRAMP5 is a plasma membrane protein involved in Mn and Fe transport. The concentration of Mn in roots, shoots and xylem sap of OsNRAMP5 RNAi (OsNRAMP5i) plants was significantly reduced compared with WT plants. The expression of OsNRAMP5 is not controlled by Fe deficiency in root and was also observed in pistil, ovary, lemma and palea. These data show that rice would utilize OsNRAMP5 for constitutive Fe and Mn uptake, while OsNRAMP5 would also play a role in Fe and Mn transport during flowering and seed development. PMID:22751306

Ishimaru, Yasuhiro; Bashir, Khurram; Nakanishi, Hiromi; Nishizawa, Naoko K

2012-07-01

119

Synthesis, crystal structure and magnetism of iron(III) and manganese(III) dipicolinates with pyridinemethanols  

NASA Astrophysics Data System (ADS)

Four ionic iron(III) and manganese(III) dipicolinato complexes of the formula (2-pymeH) [FeIII(dipic)2]?[FeIII(H2O)2Cl(dipic)]?2H2O, (3-pymeH)[MnIII(dipic)2]?1.5H2O, (4-pymeH)[FeIII(dipic)2]?2H2O and (4-pymeH)[MnIII(dipic)2]?2H2O, where H2dipic = pyridine-2,6-dicarboxylic acid, 2-pyme = 2-pyridinemethanol, 3-pyme = 3-pyridinemethanol, 4-pyme = 4-pyridinemethanol, have been prepared and characterized by the single-crystal X-ray structure analysis, infrared spectroscopy and magnetic measurements. The magnetic data were fitted to a zero-field splitting model revealing a slight magnetic anisotropy for Mn(III) systems. The molecular field correction was consistently formulated and included in the analysis for both, magnetic susceptibility and magnetization data.

Uhrecký, Róbert; Pavlik, Ján; R?ži?ková, Zde?ka; Dlhá?, ?ubor; Koman, Marian; Bo?a, Roman; Monco?, Ján

2014-11-01

120

Manganese exposure among smelting workers: Relationship between blood manganese-iron ratio and early onset neurobehavioral alterations  

PubMed Central

A biomarker for detection of early onset neurobehavioral alterations in manganism remains unknown. The purpose of this study was to use a neurobehavioral test battery to identify subtle changes in Mn-induced motor and memory dysfunction and to relate the quantifiable neurological dysfunction to an established Mn-exposure index such as blood manganese–iron ratio (MIR). A total of 323 subjects were recruited to control (n = 106), low-exposure (122), and high-exposure (95) groups. The test battery consisted of standard testing procedures including the nine-hole and groove-type steadiness tester, Benton visual retention test, and Purdue pegboard coordination test. No significant health problems or clinically diagnosed neurological dysfunctions were observed. Benton test did not reveal any abnormal memory deficits among Mn-exposed smelters, nor did the groove and nine-hole tests detect any abnormality in dynamic and static steadiness in tested subjects. Purdue pegboard test showed a remarkable age-related decline in fine movement coordination among all study participants regardless of the Mn-exposure condition. Mn exposure significantly exacerbated this age-related deterioration. Statistical modeling revealed that the plasma and erythrocyte MIR (i.e., pMIR and eMIR, respectively) were associated with Purdue pegboard scores. Among all subjects whose MIR were above the cut-off value (COV), pMIR was significantly correlated with pegboard scores (r = ?0.261, p = 0.002), whereas for those subjects over the age of 40, the eMIR, but not pMIR, was associated with declined pegboard performance (r = ?0.219, p = 0.069). When both factors were taken into account (i.e., age > 40 and MIR > the COV), only pMIR was inversely associated with pegboard scores. Combining their usefulness in Mn-exposure assessment, we recommend that the blood Mn–Fe ratio may serve as a reasonable biomarker not only for assessment of Mn exposure but also for health risk assessment. PMID:19963104

Cowan, Dallas M.; Zheng, Wei; Zou, Yan; Shi, Xiujuan; Chen, Jian; Rosenthal, Frank S.; Fan, Qiyuan

2014-01-01

121

A comparison of two-electron chemistry performed by the manganese and iron heterodimer and homodimers.  

PubMed

Two-electron chemistry with an iron dimer, a manganese dimer, and a manganese-iron dimer as a catalyst has been modeled using B3LYP* hybrid density functional theory. The recently discovered MnFe proteins form (at least) two functionally distinct groups, performing radical generation (class Ic ribonucleotide reductase subunit II) and substrate oxidations (subunit II-like ligand-binding oxidases, R2lox), respectively. Proteins from the latter group appear to be functionally similar to the diiron carboxylate proteins that perform two-electron oxidations of substrates, such as methane monooxygenase. To qualitatively determine the potential role of a MnFe center in R2lox, methane hydroxylation with the MnFe heterodimer and with the FeFe and MnMn homodimers is studied. The redox potential of the active state of the Mn(IV)Fe(IV) heterodimer is about 7 kcal mol(-1) lower than that of the active state of the Fe(IV)Fe(IV) homodimer, leading to a high barrier for the rate-limiting hydrogen abstraction with the MnFe site. If the entropy loss is not included, the barriers are lower, and the MnFe heterodimer can therefore have a role in R2lox as an oxidase for larger substrates exergonically bound to the protein. A MnMn center has a high barrier both with and without entropy loss. The higher stability of Fe(IV) in the presence of Mn(IV) in the other site compared with a second Fe(IV) suggests an explanation for the presence of the MnFe site in R2lox: to provide a metal center that is capable of two-electron chemistry, and which is more stable and less sensitive to external reductants than an Fe(IV)Fe(IV) site. PMID:22083102

Roos, Katarina; Siegbahn, Per E M

2012-03-01

122

Sorption of Ferric Iron from Ferrioxamine B to Synthetic and Biogenic Layer Type Manganese Oxides  

NASA Astrophysics Data System (ADS)

Siderophores are biogenic chelating agents produced in terrestrial and marine environments to increase the bioavailablity of ferric iron. Recent work has suggested that both aqueous and solid-phase Mn(III) may affect siderophore-mediated iron transport, but no information appears to be available about the effect of solid-phase Mn(IV). To probe the effects of predominantly Mn(IV) oxides, we studied the sorption reaction of ferrioxamine B [Fe(III)HDFOB+, an Fe(III) chelate of the trihydroxamate siderophore desferrioxamine B (DFOB)] with two synthetic birnessites [layer type Mn(III, IV) oxides] and a biogenic birnessite produced by Pseudomonas putida MnB1. We found that all of these predominantly Mn(IV) oxides greatly reduced the aqueous concentration of Fe(III)HDFOB+ over at pH 8. After 72 hours equilibration time, the sorption behavior for the synthetic birnessites could be accurately described by a Langmuir isotherm; for the biogenic oxide, a Freundlich isotherm was best utilized to model the sorption data. To study the molecular nature of the interaction between the Fe(III)HDFOB+ complex and the oxide surface, Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy was employed. Analysis of the EXAFS spectra indicated that Fe(III) associated with the Mn(IV) oxides is not complexed by DFOB as in solution, but instead Fe(III) is specifically adsorbed to into the mineral structure at multiple sites with no evidence of DFOB complexation, thus indicating that the Mn(IV) oxides displaced Fe(III) from the siderophore complex. These results indicate that manganese oxides, including biominerals, may strongly sequester iron from soluble ferric complexes and thus may play a significant role in the biogeochemical cycling of iron in marine and terrestrial environments.

Duckworth, O.; John, B.; Sposito, G.

2006-12-01

123

Spectroscopic Studies of the Iron and Manganese Reconstituted Tyrosyl Radical in Bacillus Cereus Ribonucleotide Reductase R2 Protein  

PubMed Central

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 g1-value of 2.0090 for the tyrosyl radical was extracted. This g1-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, ?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 g1-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 times higher activity. PMID:22432022

Tomter, Ane B.; Zoppellaro, Giorgio; Bell, Caleb B.; Barra, Anne-Laure; Andersen, Niels H.; Solomon, Edward I.; Andersson, K. Kristoffer

2012-01-01

124

Metallation and mismetallation of iron and manganese proteins in vitro and in vivo: the class I ribonucleotide reductases as a case study  

E-print Network

How cells ensure correct metallation of a given protein and whether a degree of promiscuity in metal binding has evolved are largely unanswered questions. In a classic case, iron- and manganese-dependent superoxide dismutases ...

Stubbe, JoAnne

125

Metals, Oxidative Stress and Neurodegeneration: A focus on Iron, Manganese and Mercury  

PubMed Central

Essential metals are crucial for the maintenance of cell homeostasis. Among the 23 elements that have known physiological functions in humans, 12 are metals, including iron (Fe) and manganese (Mn). Nevertheless, excessive exposure to these metals may lead to pathological conditions, including neurodegeneration. Similarly, exposure to metals that do not have known biological functions, such as mercury (Hg), also present great health concerns. This reviews focuses on the neurodegenerative mechanisms and effects of Fe, Mn and Hg. Oxidative stress (OS), particularly in mitochondria, is a common feature of Fe, Mn and Hg toxicity. However, the primary molecular targets triggering OS are distinct. Free cationic iron is a potent pro-oxidant and can initiate a set of reactions that form extremely reactive products, such as OH•. Mn can oxidize dopamine (DA), generating reactive species and also affect mitochondrial function, leading to accumulation of metabolites and culminating with OS. Cationic Hg forms have strong affinity for nucleophiles, such as –SH and –SeH. Therefore, they target critical thiol- and selenol-molecules with antioxidant properties. Finally, we address the main sources of exposure to these metals, their transport mechanisms into the brain, and therapeutic modalities to mitigate their neurotoxic effects. PMID:23266600

Farina, Marcelo; Avila, Daiana Silva; da Rocha, Joao Batista Teixeira

2013-01-01

126

Cadmium and manganese accumulation in Phytolacca americana L. and the roles of non-protein thiols and organic acids.  

PubMed

Phytolacca americana L. can accumulate large amounts of heavy metals in its aerial tissues, especially cadmium (Cd) and manganese (Mn). It has great potential for use in phytoextraction of metals from multi-metal-contaminated soils. This study was conducted to further investigate the Cd- and Mn-tolerance strategies of this plant. Concentrations of non-protein thiols (NPTs) and phytochelatins (PCs) in leaves and roots increased significantly as the concentration of Cd in solution increased. The molar ratios of PCs:soluble Cd ranged from 1.8 to 3.6 in roots and 8.1 to 31.6 in leaves, suggesting that the cellular response involving PC synthesis was sufficient to complex Cd ions in the cytosol, especially that of leaves. In contrast, excess Mn treatments did not result in a significant increase in NPT or PC concentrations in leaves or roots. Oxalic acid concentrations in leaves of plants exposed to 2 or 20 mM Mn reached 69.4 to 89.3 mg (0.771 to 0.992 mmol) g(-1) dry weight, respectively, which was approximately 3.7- to 8.6-fold higher than the Mn level in the 0.6 M HCl extract. Thus, oxalic acid may play an important role in the detoxification of Mn. PMID:23487997

Gao, Lu; Peng, Kejian; Xia, Yan; Wang, Guiping; Niu, Liyuan; Lian, Chunlan; Shen, Zhenguo

2013-01-01

127

Levels and predictors of airborne and internal exposure to manganese and iron among welders.  

PubMed

We investigated airborne and internal exposure to manganese (Mn) and iron (Fe) among welders. Personal sampling of welding fumes was carried out in 241 welders during a shift. Metals were determined by inductively coupled plasma mass spectrometry. Mn in blood (MnB) was analyzed by graphite furnace atom absorption spectrometry. Determinants of exposure levels were estimated with multiple regression models. Respirable Mn was measured with a median of 62 (inter-quartile range (IQR) 8.4-320) ?g/m(3) and correlated with Fe (r=0.92, 95% CI 0.90-0.94). Inhalable Mn was measured with similar concentrations (IQR 10-340??g/m(3)). About 70% of the variance of Mn and Fe could be explained, mainly by the welding process. Ventilation decreased exposure to Fe and Mn significantly. Median concentrations of MnB and serum ferritin (SF) were 10.30??g/l (IQR 8.33-13.15??g/l) and 131??g/l (IQR 76-240??g/l), respectively. Few welders were presented with low iron stores, and MnB and SF were not correlated (r=0.07, 95% CI -0.05 to 0.20). Regression models revealed a significant association of the parent metal with MnB and SF, but a low fraction of variance was explained by exposure-related factors. Mn is mainly respirable in welding fumes. Airborne Mn and Fe influenced MnB and SF, respectively, in welders. This indicates an effect on the biological regulation of both metals. Mn and Fe were strongly correlated, whereas MnB and SF were not, likely due to higher iron stores among welders. PMID:22377681

Pesch, Beate; Weiss, Tobias; Kendzia, Benjamin; Henry, Jana; Lehnert, Martin; Lotz, Anne; Heinze, Evelyn; Käfferlein, Heiko Udo; Van Gelder, Rainer; Berges, Markus; Hahn, Jens-Uwe; Mattenklott, Markus; Punkenburg, Ewald; Hartwig, Andrea; Brüning, Thomas

2012-01-01

128

Transcriptional regulation by iron and role during plant pathogenesis of genes encoding iron- and manganese-superoxide dismutases of Pseudomonas syringae pv. syringae B728a  

Microsoft Academic Search

The bean pathogen, Pseudomonas syringae B728a, may require iron-superoxide dismutase (FeSOD) and manganese–superoxide dismutase (MnSOD) activities in protection against reactive oxygen species (ROS) generated in planta. Genes encoding FeSOD or MnSOD of P. syringae B728a were cloned by hybridization with specific PCR probes amplified from P. syringae genomic DNA. The sodB gene was monocistronic whereas the sodA gene was transcribed

Y. C KIM; C. D MILLER; A. J ANDERSON

1999-01-01

129

Assimilation of zinc, cadmium, lead, copper, and iron by the spider Dysdera crocata, a predator of woodlice  

SciTech Connect

In this paper, an experiment is described on the assimilation of zinc, cadmium, lead, copper and iron by Dysdera crocata collected from a site in central Bristol. The spiders were fed on woodlice from their own site, and on woodlice from a site contaminated by a smelting works which contained much higher levels of zinc, cadmium and lead than the spiders would have been used to in their normal diet.

Hopkin, S.P.; Martin, M.H.

1985-02-01

130

Influence of iron overload on manganese, zinc, and copper concentration in rat tissues in vivo: study of liver, spleen, and brain  

Microsoft Academic Search

Although hemochromatosis and pathological situations due to chronic iron overload have been extensively described, there is\\u000a little information about the influence of iron on other trace elements in the cell. The aim of this study was to investigate\\u000a changes in the concentration of zinc, manganese, and copper in the liver, spleen, and brain of rats after iron overload. Iron\\u000a overload

D. V. Vayenas; M. Repanti; A. Vassilopoulos; D. A. Papanastasiou

1998-01-01

131

Specificity and phenetic relationships of iron- and manganese-containing superoxide dismutases on the basis of structure and sequence comparisons.  

PubMed

The iron- and manganese-containing superoxide dismutases (Fe/Mn-SOD) share the same chemical function and spatial structure but can be distinguished according to their modes of oligomerization and their metal ion specificity. They appear as homodimers or homotetramers and usually require a specific metal for activity. On the basis of 261 aligned SOD sequences and 12 superimposed x-ray structures, two phenetic trees were constructed, one sequence-based and the other structure-based. Their comparison reveals the imperfect correlation of sequence and structural changes; hyperthermophilicity requires the largest sequence alterations, whereas dimer/tetramer and manganese/iron specificities are induced by the most sizable structural differences within the monomers. A systematic investigation of sequence and structure characteristics conserved in all aligned SOD sequences or in subsets sharing common oligomeric and/or metal specificities was performed. Several residues were identified as guaranteeing the common function and dimeric conformation, others as determining the tetramer formation, and yet others as potentially responsible for metal specificity. Some form cation-pi interactions between an aromatic ring and a fully or partially positively charged group, suggesting that these interactions play a significant role in the structure and function of SOD enzymes. Dimer/tetramer- and iron/manganese-specific fingerprints were derived from the set of conserved residues; they can be used to propose selected residue substitutions in view of the experimental validation of our in silico derived hypotheses. PMID:14672935

Wintjens, René; Noël, Christophe; May, Alex C W; Gerbod, Delphine; Dufernez, Fabienne; Capron, Monique; Viscogliosi, Eric; Rooman, Marianne

2004-03-01

132

Induction of superoxide dismutases in Escherichia coli by manganese and iron  

SciTech Connect

Growth of Escherichia coli B in simple media enriched with Mn(II) resulted in the elevation of the manganese-containing superoxide dismutase, whereas growth in such medium enriched with iron caused increased content of the iron-containing superoxide dismutase. Enrichment of the medium with Co(II), Cu(II), Mo(VI), Zn(II), or Ni(II) had no effect. The inductions of superoxide dismutase by Mn(II) or by Fe(II) were dioxygen dependent, but these metals did not affect the CN/sup -/-resistant respiration of E. coli B and did not influence the increase in the CN/sup -/-resistant respiration caused by paraquat. Mn(II) and paraquat acted synergistically in elevating the superoxide dismutase content, and Mn(II) reduced the growth inhibition imposed by paraquat. E. coli grown in the complex 3% Trypticase soy broth (BBL Microbiology Systems)-0.5% yeast extract-0.2% glucose medium contained more superoxide dismutase than did cells grown in the simple media and were less responsive to enrichment of the medium with Mn(II) or Fe(II). Nevertheless, in the presence of paraquat, induction of superoxide dismutase by these metals could be seen even in the Trypticase-yeast extract-glucose medium. On the basis of these observations, the authors propose that the apo-superoxide dismutases may act as autogenous repressors and that Mn(II) and Fe(II) increase the cell content of the corresponding enzymes by speeding the conversion of the apo- to the holoenzymes.

Pugh, S.Y.R.; DiGuiseppi, J.L.; Fridovich, I.

1984-10-01

133

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

SciTech Connect

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.

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

1999-10-31

134

Cation distribution, structure and magnetic properties of lithium manganese iron oxide spinel solid solutions  

SciTech Connect

Single phase cubic spinel compounds Li {sub x}Mn{sub 1+x}Fe{sub 2-2x}O{sub 4} (x = 0, ..., 1) were obtained by thermal decomposition of freeze-dried formate solutions of appropriate composition. The samples were characterized by X-ray powder diffraction and Rietveld refinement, XANES, {sup 57}Fe Moessbauer spectroscopy and magnetization measurements. The combination of these methods provides useful conclusions concerning the structure, cation distribution and properties of the spinel solid solutions. The Li {sub x}Mn{sub 1+x}Fe{sub 2-2x}O{sub 4} samples contain Mn(II) and Mn(III) or Mn(III) and Mn(IV) for x < 0.5 or x > 0.5, respectively. With the increase of x the portion of Li ions occupying tetrahedral sites increases and becomes 100% at about x = 4/7. In spite of the preferred occupation of octahedral sites by manganese(III), the experimental results can only be explained by a partial occupation also of tetrahedral sites by Mn(III). An increase of M {sub S} with the increase of x (expected for a preferred substitution of magnetic ions in tetrahedral sites by non-magnetic Li ions) is not observed. It should be prevented by the decreasing cooperative coupling effects due to the reduction of the iron content.

Wende, C. [Institute of Inorganic Chemistry, Dresden University of Technology, 01062 Dresden (Germany); Olimov, Kh. [Institute of Physics, University of Bonn, 53115 Bonn (Germany); Modrow, H. [Institute of Physics, University of Bonn, 53115 Bonn (Germany); Wagner, F.E. [Physics Department, Technical University of Munich, 85748 Garching (Germany); Langbein, H. [Institute of Inorganic Chemistry, Dresden University of Technology, 01062 Dresden (Germany)]. E-mail: Hubert.Langbein@chemie.tu-dresden.de

2006-08-10

135

Investigation of nanostructured iron and manganese oxides as novel intercalation hosts for lithium  

NASA Astrophysics Data System (ADS)

Rechargeable lithium battery systems are being pushed to the limits of their performance in modern portable devices, with increasing demands for higher energy and higher power. The intercalation cathode or positive electrode in these batteries is one of the primary bottlenecks in terms of performance. In this thesis, investigation of nanostructured iron and manganese oxide compounds that show immense promise as cathode materials for rechargeable lithium batteries has been conducted. The electrochemical performance of these nanostructured compounds is dramatically superior to their microcrystalline counterparts, with higher specific discharge capacities, improved capacity retention upon charge-discharge cycling and enhanced rate performance. Tied to these promising electrochemical properties are unconventional structural and mechanistic characteristics that have been examined carefully. Higher solid-solubility of lithium in the nanostructured hosts, reduced tendency to undergo phase transformations typically observed in microcrystalline hosts, perfectly reversible lithium intercalation-deintercalation in nanostructured compounds possessing hydroxyl species, are some characteristics illustrated here. The properties exhibited by these materials are dependent upon such structural aspects as lack of long-range order, nano-sized morphology, disordered surface structure and non-stoichiometry. A detailed characterization of these compounds is conducted by studying the local atomic and electronic structures via x-ray absorption spectroscopy (XAS), in conjunction with studying the crystal structure via x-ray diffraction (XRD). The synthesis, electrochemistry, and structural phenomena that possess general relevance to fundamental nanoscale materials science, are highlighted in this work.

Jain, Gaurav

136

Role of cobalt, iron, lead, manganese, mercury, platinum, selenium, and titanium in carcinogenesis.  

PubMed Central

The possible carcinogenicity of cobalt, iron, lead, manganese, mercury, platinum, selenium, and titanium is reviewed, taking into account epidemiological data, the results of animal experimental studies, data on mutagenic effects and on other in vitro test systems. Of the great variety of occupations where exposure to one of these metals may occur, only haematite mining has been clearly shown to involve an increased human cancer risk. While the possibility that haematite might in some way act as a carcinogen has to be taken into consideration it is more likely that other carcinogens are responsible. Certain platinum coordination complexes are used in cancer chemotherapy, are mutagenic, and likely to be carcinogenic. Cobalt, its oxide and sulfide, certain lead salts, one organomanganese, and one organotitanium compound have been shown to have a limited carcinogenic effect in experimental animal studies, and except for titanium appear to be mutagenic. Certain mercury compounds are mutagenic but none have been shown to be carcinogenic. The presently available data are inadequate to assess the possible carcinogenicity of selenium compounds, but a few observations suggest that selenium may suppress the effect of other carcinogens administered to experimental animals and may even be associated with lower cancer mortality rates in man. Epidemiological observations are essential for the assessment of a human cancer risk, but the difficulty in collecting past exposure data in occupational groups and the complexity of multiple occupational exposures with changes over time, limits the usefulness of retrospective epidemiological studies. PMID:7023929

Kazantzis, G

1981-01-01

137

Regional patterns of bioturbation and iron and manganese reduction in the sediments of the southeastern Bering Sea  

NASA Astrophysics Data System (ADS)

Regional patterns of iron (Fe) and manganese (Mn) reduction rates across the shelf and slope of the southeastern Bering Sea, as well as the relative importance of these pathways in sedimentary organic matter remineralization, were investigated during the spring and summer of 2009. Reduction rates of Fe and Mn were calculated using depth profiles of solid-phase iron and manganese oxide concentrations and bioturbation coefficients, Db, determined from profiles of excess 234Th. Iron reduction was found to be a significant pathway for carbon mineralization across the shelf, with an average rate of 1.74 mmol m-2 d-1. However, Fe reduction rates higher than 6 mmol m-2 d-1 were calculated, and a significant regional pattern was observed, with highest rates found on the northern shelf, and dropping toward the south and offshore. Conversely, Mn oxide reduction was found to be of minor significance, with low reduction rates in all regions, averaging only 0.09 mmol m-2 d-1 across the shelf, and accounting for no more than 5% of total carbon oxidation in any region. These results indicate that Fe oxide reduction is a significant pathway for carbon remineralization in the northern and middle-shelf regions, where organic matter deposition rates and benthic biomass are high. Additionally, this work provides insight into the potential role of sedimentary iron reduction as a source of bioavailable Fe in this region.

Esch, Margaret E. S.; Shull, David H.; Devol, Allan H.; Moran, S. Bradley

2013-10-01

138

Geometric and Electronic Structures of Manganese-substituted Iron Superoxide Dismutase  

PubMed Central

The active-site structures of the oxidized and reduced forms of manganese-substituted iron superoxide dismutase (Mn(Fe)SOD) are examined, for the first time, using a combination of spectroscopic and computational methods. On the basis of electronic absorption, circular dichrosim (CD), magnetic CD (MCD), and variable-temperature variable-field MCD data obtained for oxidized Mn(Fe)SOD, we propose that the active site of this species is virtually identical to that of wild-type manganese SOD (MnSOD), both containing a metal ion that resides in a trigonal bipyramidal ligand environment. This proposal is corroborated by quantum mechanical / molecular mechanical (QM/MM) computations performed on complete protein models of Mn(Fe)SOD in both its oxidized and reduced states and, for comparison, wild-type (WT) MnSOD. The major differences between the QM/MM optimized active sites of WT MnSOD and Mn(Fe)SOD are a smaller (His)N–Mn–N(His) equatorial angle and a longer (Gln146(69))NH?O(sol) H-bond distance in the metal-substituted protein. Importantly, these modest geometric differences are consistent with our spectroscopic data obtained for the oxidized proteins and high-field electron paramagnetic resonance spectra reported previously for reduced Mn(Fe)SOD and MnSOD. As Mn(Fe)SOD exhibits a reduction midpoint potential (Em) almost 700 mV higher than that of MnSOD, which has been shown to be sufficient for explaining the lack of SOD activity displayed by the metal-subtituted species (Vance, C. K.; Miller, A. F. Biochemistry 2001, 40, 13079–13087), Ems were computed for our experimentally validated QM/MM optimized models of Mn(Fe)SOD and MnSOD. These computations properly reproduce the experimental trend and reveal that the drastically elevated Em of the metal substituted protein stems from a larger separation between the second-sphere Gln residue and the coordinated solvent in Mn(Fe)SOD relative to MnSOD, which causes a weakening of the corresponding H-bond interaction in the oxidized state and alleviates steric crowding in the reduced state. PMID:23461587

Jackson, Timothy A.; Gutman, Craig T.; Maliekal, James; Miller, Anne-Frances; Brunold, Thomas C.

2013-01-01

139

Iron and manganese speciation and cycling in glacially influenced high-latitude fjord sediments (West Spitsbergen, Svalbard): Evidence for a benthic recycling-transport mechanism  

NASA Astrophysics Data System (ADS)

Glacial environments may provide an important but poorly constrained source of potentially bioavailable iron and manganese phases to the coastal ocean in high-latitude regions. Little is known about the fate and biogeochemical cycling of glacially derived iron and manganese in the coastal marine realm. Sediment and porewater samples were collected along transects from the fjord mouths to the tidewater glaciers at the fjord heads in Smeerenburgfjorden, Kongsfjorden, and Van Keulenfjorden along Western Svalbard. Solid-phase iron and manganese speciation, determined by sequential chemical extraction, could be linked to the compositions of the local bedrock and hydrological/weathering conditions below the local glaciers. The concentration and sulfur isotope composition of chromium reducible sulfur (CRS) in Kongs- and Van Keulenfjorden sediments largely reflect the delivery rate and isotope composition of detrital pyrite originating from adjacent glaciers. The varying input of reducible iron and manganese oxide phases and the input of organic matter of varying reactivity control the pathways of organic carbon mineralization in the sediments of the three fjords. High reducible iron and manganese oxide concentrations and elevated metal accumulation rates coupled to low input of “fresh” organic matter lead to a strong expression of dissimilatory metal oxide reduction evidenced in very high porewater iron (up to 800 ?M) and manganese (up to 210 ?M) concentrations in Kongsfjorden and Van Keulenfjorden. Sediment reworking by the benthic macrofauna and physical sediment resuspension via iceberg calving may be additional factors that promote extensive benthic iron and manganese cycling in these fjords. On-going benthic recycling of glacially derived dissolved iron into overlying seawater, where partial re-oxidation and deposition occurs, facilitates the transport of iron across the fjords and potentially into adjacent continental shelf waters. Such iron-dominated fjord sediments are likely to provide significant fluxes of potentially bioavailable iron to coastal waters and beyond. By contrast, low delivery of reducible iron (oxyhydr)oxide phases and elevated organic carbon mineralization rates driven by elevated input of “fresh” marine organic matter allow organoclastic sulfate reduction to dominate carbon remineralization at the outer Smeerenburgfjorden sites, which may limit iron fluxes to the water column.

Wehrmann, Laura M.; Formolo, Michael J.; Owens, Jeremy D.; Raiswell, Robert; Ferdelman, Timothy G.; Riedinger, Natascha; Lyons, Timothy W.

2014-09-01

140

Community Metabolism in Microbial Mats: The Occurrence of Biologically-mediated Iron and Manganese Reduction  

NASA Astrophysics Data System (ADS)

Community metabolism and nutrient, iron (Fe) and manganese (Mn) cycling were examined in two intertidal, marine, microbial mat communities during short (4-5 days) incubations in closed, flow-through microcosms. Sediment microcosms were incubated under either light (light-dark cycles) or dark (continuous darkness) conditions to assess the effect(s) of photosynthetic oxygen production and microalgal activity on nutrient, Fe and Mn cycling. The effects of chemical redox reactions between reduced sulphur (S), Fe and Mn cycling were examined by blocking sulphate reduction, and reduced S production, with 25 mM molybdate while incubating under dark conditions. In light-incubated microcosms, negligible fluxes of nutrients (nitrogen and phosphorus) and trace metals were observed. A substantial sediment-water flux of reduced Fe (Fe 2+) and Mn (Mn 2+) was observed in microcosms incubated under continuous darkness; highest fluxes were observed in molybdate-amended microcosms. At both sites, biologically-mediated redox reactions accounted for a substantial (>50%) portion of the Fe 2+and Mn 2+flux. Both microbial mat communities exhibited similar rates of gross photosynthetic oxygen (O 2) production, but dramatically different rates of net benthic O 2flux. Distinct patterns of net O 2production and trace metal cycling arose from differences in either trace metal oxide availability or reactivity (mineralogy), organic carbon mineralization rates, or sediment characteristics (porosity). Variations in the microbial community responsible for trace metal cycling could have also contributed to the pattern. The present data illustrate that chemically-mediated redox reactions between metal oxides and reduced S complicate interpretation of Fe and Mn fluxes, underscoring the need to separate chemical and biological reactions when attempting to determine the role of biological trace metal reduction in organic carbon oxidation.

Joye, Samantha B.; Mazzotta, Mandy L.; Hollibaugh, James T.

1996-12-01

141

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

SciTech Connect

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){sub 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{sup 2+} and Fe{sup 2+} under suboxic condition and very close to the FeS/Fe{sup 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.

Lin, Chin Yik, E-mail: cy_lin_ars@hotmail.com [Universiti Malaysia Sabah, School of Science and Technology (Malaysia); Abdullah, Mohd. Harun [Universiti Malaysia Sabah, Water Research Unit, School of Science and Technology (Malaysia); Musta, Baba; Praveena, Sarva Mangala [Universiti Malaysia Sabah, School of Science and Technology (Malaysia); Aris, Ahmad Zaharin [Universiti Putra Malaysia, Faculty of Environmental Studies (Malaysia)

2011-03-15

142

Oxidation and competitive retention of arsenic between iron- and manganese oxides  

NASA Astrophysics Data System (ADS)

Manganese (Mn) and iron (Fe) oxides are ubiquitous solids in terrestrial systems that have high sorptive capacities for many trace metals, including arsenic (As). Although numerous studies have characterized the effects of As adsorption onto Fe and Mn oxides individually, the fate of arsenic within mixed systems representative of natural environments has not been completely resolved. Here, we examine oxidation and competitive retention of As on goethite and birnessite using a Donnan reactor, where each oxide is isolated by a semi-permeable membrane through which arsenic can migrate. To initiate the Donnan reactor experiments, As(III) was simultaneously added to both chambers. Arsenic(III) injected into the birnessite chamber is rapidly oxidized to As(V) and then slowly redistributes across both chambers, while that added to the goethite chamber undergoes rapid adsorption; the adsorbed As(III) on goethite subsequently undergoes desorption and diffusion into the birnessite chamber followed by oxidation to As(V). With increased reaction time, As(V) is generated and preferentially partitioned onto goethite due to higher adsorption affinity compared to birnessite. Furthermore, the dissolved concentration of As(V) is controlled by the adsorption capacity of the goethite surface, which when saturated, leads to increased aqueous As concentrations; despite an increase in As(V) loading on birnessite with increasing initial As(III) concentration, the resulting aqueous As(V) concentration increase appreciably once the goethite surface is saturated. Our findings show that Mn oxides in soils act as a temporary sorbent of As, but operate primarily as strong oxidants responsible for transformation of As(III) to As(V), which can then strongly adsorb on the surrounding Fe oxide matrix.

Ying, Samantha C.; Kocar, Benjamin D.; Fendorf, Scott

2012-11-01

143

Dietary manganese supplementation influences the expression of transporters involved in iron metabolism in chickens.  

PubMed

To investigate the effects of dietary manganese (Mn) supplementation on iron (Fe) metabolism, a total of 480 50-week-old hens were fed the basal diet (control, 24.35 mg Mn/kg) without Mn supplementation for 6 weeks to reduce Mn storage in the body. Hens were then randomly assigned to one of three treatments, which included the control and control added with 60 or 300 mg Mn/kg diet (M-Mn or H-Mn). Duodenum, heart, liver, and tibia were collected in hens after 12-week feeding period. No significant differences were observed in egg production, feed/egg ratio, shell breaking strength, and shell thickness among different treatments. Compared with control or M-Mn, H-Mn decreased (P??0.10) Fe concentration in the heart and tibia. In conjunction with reduced Fe retention, DMT1 mRNA expression decreased (P?

Bai, Shiping; Huang, Lirong; Luo, Yuheng; Wang, Leilei; Ding, Xuemei; Wang, Jianping; Zeng, Qiufeng; Zhang, Keying

2014-09-01

144

Single, binary, and multicomponent sorption of iron and manganese on lignite  

SciTech Connect

Acid mine drainage (AMD) has long been a significant environmental problem resulting from the microbial oxidation of iron pyrite in the presence of water and air, affording an acidic solution that contains toxic metal ions. The main objective of this study was to remove metal ions (Fe(II), Fe(III), Mn(II), Zn(II)) from AMD using lignite, a low-cost adsorbent. The lignite sorbent was utilized for the sorption of ferrous, ferric, manganese, zinc, and calcium ions in aqueous solutions. Studies were performed at different pH to find optimum pH. Equilibrium isotherms were determined to assess the maximum adsorption capacity of lignite for different metal ions. Sorption capacities were compared in single, binary, ternary, and multicomponent systems. The sorption data are correlated with Freundlich and Langmuir isotherms in each system. Both Freundlich and Langmuir isotherms fit the data reasonably well in terms of regression coefficients. Sorption studies were also performed at different temperatures to obtain the thermodynamic parameters of the process. The maximum lignite adsorption capacities at 25{sup o}C were 34.22, 25.84, and 11.90 mg/g for Fe(II), Mn(II), and Fe(III), respectively. Adsorption of Fe{sup 2+} (24.70 mg/g at 10{sup o}C and 46.46 mg/g at 40{sup o}C) increased with increased temperature, while Mn{sup 2+} adsorption (28.11 mg/g at 10{sup o}C and 7.70 mg/g at 40{sup o}C) decreased with increased temperature.

Mohad, D.; Chander, S. [Penn State University, University Park, PA (United States). Dept. of Energy & Geoenvironmental Engineering

2006-07-01

145

A Chronic Iron-Deficient\\/High-Manganese Diet in Rodents Results in Increased Brain Oxidative Stress and Behavioral Deficits in the Morris Water Maze  

Microsoft Academic Search

Iron deficiency (ID) is especially common in pregnant women and may even persist following childbirth. This is of concern\\u000a in light of reports demonstrating that ID may be sufficient to produce homeostatic dysregulation of other metals, including\\u000a manganese (Mn). These results are particularly important considering the potential introduction of the Mn-containing gas additive,\\u000a methyl cyclopentadienyl manganese tricarbonyl (MMT), in various

Vanessa A. Fitsanakis; Kimberly N. Thompson; Sarah E. Deery; Dejan Milatovic; Zak K. Shihabi; Keith M. Erikson; Russell W. Brown; Michael Aschner

2009-01-01

146

Cadmium Manganese Telluride (Cd1-xMnxTe): A potential material for room-temperature radiation detectors  

SciTech Connect

Cadmium Manganese Telluride (CdMnTe) recently emerged as a promising material for room-temperature X- and gamma-ray detectors. It offers several potential advantages over CdZnTe. Among them is its optimal tunable band gap ranging from 1.7-2.2 eV, and its relatively low (< 50%) content of Mn compared to that of Zn in CdZnTe that assures this favorable band-gap range. Another important asset is the segregation coefficient of Mn in CdTe that is approximately unity compared to 1.35 for Zn in CdZnTe, so ensuring the homogenous distribution of Mn throughout the ingot; hence, a large-volume stoichiometric yield is attained. However, some materials issues primarily related to the growth process impede the production of large, defect-free single crystals. The high bond-ionicity of CdMnTe entails a higher propensity to crystallize into a hexagonal structure rather than to adopt the expected zinc-blend structure, which is likely to generate twins in the crystals. In addition, bulk defects generate in the as-grown crystals due to the dearth of high-purity Mn, which yields a low-resistivity material. In this presentation, we report on our observations of such material defects in current CdMnTe materials, and our evaluation of its potential as an alternative detector material to the well-known CdZnTe detectors. We characterized the bulk defects of several indium- and vanadium-doped Cd1-xMnxTe crystals by using several advanced techniques, viz., micro-scale mapping, white-beam x-ray diffraction/reflection topography, and chemical etching. Thereafter, we fabricated some detectors from selected CdMnTe crystals, characterized their electrical properties, and tested their performance as room-temperature X- and gamma-ray detectors. Our experimental results indicate that CdMnTe materials could well prove to become a viable alternative in the near future.

Hossain, A.; Cui, Y.; Bolotnikov, A.; Camarda, G.; Yang, G.; Kim, K-H.; Gul, R.; Xu, L.; Li, L.; Mycielski, A.; and James, R.B.

2010-07-11

147

Effects of sulfur, zinc, iron, copper, manganese, and boron applications on sunflower yield and plant nutrient concentration  

SciTech Connect

Sulfur, zinc, iron, copper, manganese, and boron application did not affect the seed yield or oil percentage of sunflower (Helianthus annuus L.) on both dryland and irrigated soils in North Dakota in 1981. Field averages indicated significant Zn, Mn, and B uptake by sunflower at the 12-leaf stage as a result of fertilization with these elements. Increased Zn uptake was also observed in the uppermost mature leaf at anthesis from zinc fertilization. Although sunflower yield from boron fertilization was not significantly different from the check, a trend was observed in which boron fertilization seemed to decrease sunflower yield. Sunflower yields from the boron treatment were the lowest out of seven treatments in three out of four fields. Also, sunflower yield from the boron treatment was significantly lower than both iron and sulfur treatments when all fields were combined.

Hilton, B.R.; Zubriski, J.C.

1985-01-01

148

Cadmium  

Microsoft Academic Search

\\u000a Cadmium is a Group lib element discovered in 1818 by Herman and Strohmeyer and named after the mythological hero Cadmus who\\u000a founded Thebes in Greece. It was first extracted commercially in 1886 in Silesia. Its atomic weight is 112.41 (with natural\\u000a isotopes ranging from 106 to 116). A soft, ductile, silver-white metal (described also as blue-white; Baud, 1962) with a

Michael J. Scoullos; Gerrit H. Vonkeman; Iain Thornton; Zen Makuch

149

Blood cadmium is elevated in iron deficient U.S. children: a cross-sectional study  

PubMed Central

Background Cadmium (Cd), a widespread environmental contaminant, and iron deficiency (ID), the most common nutrient deficiency in the world, are known risk factors for neurodevelopmental delays, as well as other disorders, in infants and children. Studies assessing the cumulative effects of these factors are lacking in children, despite concerns of increased uptake of metals in the presence of ID. Here we sought to determine if blood and urine Cd levels were elevated in ID children compared to non-ID children. Methods Data for 5224 children, aged 3–19 years, were obtained from the 1999–2002 NHANES. ID was defined as ?2 of 3 abnormal iron indicators (low serum ferritin [SF], high free erythrocyte protoporphyrin [FEP], low % transferrin saturation [TSAT]); ID anemia (IDA) was defined as ID plus low hemoglobin (Hgb). Logistic regression was used to evaluate associations between ID, IDA, and abnormal iron indicators and categories of blood and urine Cd. Results Adjusted odds of ID, IDA, low SF, and low TSAT were associated with increasing category of blood Cd but not urine Cd. Adjusted ORs (95% CI) for blood Cd ?0.5 ?g/L versus?iron indicators revealed that the observed associations were strongest in females aged 16–19 years. Conclusions Given their shared neurotoxic effects in children, and that many people live in areas with high burdens of both ID and Cd, more research into the complex relationships between nutrient deficiencies and environmental toxicants is vital. PMID:24373608

2013-01-01

150

Tunable T1 and T2 contrast abilities of manganese-engineered iron oxide nanoparticles through size control  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate the tunable T1 and T2 contrast abilities of engineered iron oxide nanoparticles with high performance for liver contrast-enhanced magnetic resonance imaging (MRI) in mice. To enhance the diagnostic accuracy of MRI, large numbers of contrast agents with T1 or T2 contrast ability have been widely explored. The comprehensive investigation of high-performance MRI contrast agents with controllable T1 and T2 contrast abilities is of high importance in the field of molecular imaging. In this study, we synthesized uniform manganese-doped iron oxide (MnIO) nanoparticles with controllable size from 5 to 12 nm and comprehensively investigated their MRI contrast abilities. We revealed that the MRI contrast effects of MnIO nanoparticles are highly size-dependent. By controlling the size of MnIO nanoparticles, we can achieve T1-dominated, T2-dominated, and T1-T2 dual-mode MRI contrast agents with much higher contrast enhancement than the corresponding conventional iron oxide nanoparticles.In this paper, we demonstrate the tunable T1 and T2 contrast abilities of engineered iron oxide nanoparticles with high performance for liver contrast-enhanced magnetic resonance imaging (MRI) in mice. To enhance the diagnostic accuracy of MRI, large numbers of contrast agents with T1 or T2 contrast ability have been widely explored. The comprehensive investigation of high-performance MRI contrast agents with controllable T1 and T2 contrast abilities is of high importance in the field of molecular imaging. In this study, we synthesized uniform manganese-doped iron oxide (MnIO) nanoparticles with controllable size from 5 to 12 nm and comprehensively investigated their MRI contrast abilities. We revealed that the MRI contrast effects of MnIO nanoparticles are highly size-dependent. By controlling the size of MnIO nanoparticles, we can achieve T1-dominated, T2-dominated, and T1-T2 dual-mode MRI contrast agents with much higher contrast enhancement than the corresponding conventional iron oxide nanoparticles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02680b

Huang, Guoming; Li, Hui; Chen, Jiahe; Zhao, Zhenghuan; Yang, Lijiao; Chi, Xiaoqin; Chen, Zhong; Wang, Xiaomin; Gao, Jinhao

2014-08-01

151

Catalytic kinetic simultaneous determination of iron, silver and manganese with the Kalman filter by using flow injection analysis stopped-flow spectrophotometry  

Microsoft Academic Search

A catalytic differential kinetic method with Kalman filter for the simultaneous determination of multi-component is described. The oxidization of Rhodamine B (RB) by potassium periodate in a slightly acid solution is a slow reaction. But iron(III), silver(I) or manganese(II) has a differential catalytic effect on the oxidation reaction of RB in the presence of 1,10-phenanthroline as the activator. So iron,

Ying-Zhi Ye; Hong-Yan Mao; Ya-Hua Chen

1998-01-01

152

Deregulation of transition metals homeostasis is a key feature of cadmium toxicity in Salmonella.  

PubMed

Cadmium is a highly toxic metal whose presence in the environment represents a challenge for all forms of life. To improve our knowledge on cadmium toxicity, we have explored Salmonella Typhimurium responses to this metal. We have found that cadmium induces the concomitant expression of the cation efflux pump ZntA and of the high affinity zinc import system ZnuABC. This observation suggests that cadmium accumulation within the cell induces a condition of apparent zinc starvation, possibly due to the ability of this metal to compete with zinc for the metal binding site of proteins. This hypothesis is supported by the finding that strains lacking ZntA or ZnuABC are hyper-susceptible to cadmium and that the cadmium-induced growth defect of a znuABC mutant strain is largely relieved by zinc supplementation. A similar growth defect was observed for a mutant with impaired ability to acquire iron, whereas cadmium does not affect growth of a strain defective in manganese import. Cadmium also influences the expression and activity of the two cytoplasmic superoxide dismutases FeSOD and MnSOD, which are required to control cadmium-mediate oxidative stress. Exposure to cadmium causes a reduction of FeSOD activity in Salmonella wild type and the complete abrogation of its expression in the strain defective in iron import. In contrast, although MnSOD intracellular levels increase in response to cadmium, we observed discrepancies between protein levels and enzymatic activity which are suggestive of incorporation of non-catalytic metals in the active site or to cadmium-mediated inhibition of manganese import. Our results indicate that cadmium interferes with the ability of cells to manage transition metals and highlight the close interconnections between the homeostatic mechanisms regulating the intracellular levels of different metals. PMID:24970347

Ammendola, Serena; Cerasi, Mauro; Battistoni, Andrea

2014-08-01

153

A Green Analytical Method Using Ultrasound in Sample Preparation for the Flow Injection Determination of Iron, Manganese, and Zinc in Soluble Solid Samples by Flame Atomic Absorption Spectrometry  

PubMed Central

A simple and rapid analytical method was developed for the determination of iron, manganese, and zinc in soluble solid samples. The method is based on continuous ultrasonic water dissolution of the sample (5–30?mg) at room temperature followed by flow injection flame atomic absorption spectrometric determination. A good precision of the whole procedure (1.2–4.6%) and a sample throughput of ca. 25 samples h–1 were obtained. The proposed green analytical method has been successfully applied for the determination of iron, manganese, and zinc in soluble solid food samples (soluble cocoa and soluble coffee) and pharmaceutical preparations (multivitamin tablets). The ranges of concentrations found were 21.4–25.61??g?g?1 for iron, 5.74–18.30??g?g?1 for manganese, and 33.27–57.90??g?g?1 for zinc in soluble solid food samples and 3.75–9.90??g?g?1 for iron, 0.47–5.05??g?g?1 for manganese, and 1.55–15.12??g?g?1 for zinc in multivitamin tablets. The accuracy of the proposed method was established by a comparison with the conventional wet acid digestion method using a paired t-test, indicating the absence of systematic errors. PMID:22567553

Yebra, M. Carmen

2012-01-01

154

Manganese antagonizes iron blocking mitochondrial aconitase expression in human prostate carcinoma cells  

Microsoft Academic Search

Aim:To investigate the possible role of manganese in the regulation of mitochondrial aconitase (mACON) activity human prostate carcinoma cell line PC-3 cells.Methods:The mACON enzymatic activities of human prostate carcinoma cell line PC-3 cells were determined using a reduced nicotinamide adenine dinucleotide-coupled assay. Immunoblot and transient gene expression assays were used to study gene expression of the mACON. The putative response

Ke-Hung Tsui; Phei-Lang Chang; Horng-Heng Juang

2006-01-01

155

Recovering iron, manganese, copper, cobalt, and high-purity nickel from sea nodules  

NASA Astrophysics Data System (ADS)

Many studies have investigated methods of recovering valuable metals from sea nodules. Recently, a research group in Japan developed a smelting and chlorine process after investigating a variety of existing processes and comparing their respective efficiencies with the same nodules. The best results were obtained by combining pyrometallurgical and hydrometallurgical treatments, which enabled the efficient recovery of manganese, nickel, copper, and cobalt. High-purity nickel can be also produced through further solvent extraction.

Kohga, Tetsuyoshi; Imamura, Masaki; Takahashi, Junichi; Tanaka, Nobuhiro; Nishizawa, Tokuo

1995-12-01

156

Iron deficiency is associated with increased levels of blood cadmium in the Korean general population: Analysis of 2008-2009 Korean National Health and Nutrition Examination Survey data  

SciTech Connect

Introduction: We present data from the Korean National Health and Nutrition Examination Survey 2008-2009 on the distribution of blood cadmium levels and their association with iron deficiency in a representative sample of the adult Korean population. Methods: Serum ferritin was categorized into three levels: low (serum ferritin <15.0 {mu}g/L), low normal (15.0-30.0 {mu}g/L for women and 15.0-50.0 for men), and normal ({>=}30.0 {mu}g/L for women and {>=}50.0 for men), and its association with blood cadmium level was assessed after adjustment for various demographic and lifestyle factors. Results: Geometric means of blood cadmium in the low serum ferritin group in women, men, and all participants were significantly higher than in the normal group. Additionally, multiple regression analysis after adjusting for various covariates showed that blood cadmium was significantly higher in the low-ferritin group in women, men, and all participants compared with the normal group. We also found an association between serum ferritin and blood cadmium among never-smoking participants. Discussion: We found, similar to other recent population-based studies, an association between iron deficiency and increased blood cadmium in men and women, independent of smoking status. The results of the present study show that iron deficiency is associated with increased levels of blood cadmium in the general population.

Lee, Byung-Kook [Institute of Environmental and Occupational Medicine, Soonchunhyang University, 646 Eupnae-ri, Shinchang-myun, Asan-si, Choongnam 336-745 (Korea, Republic of)] [Institute of Environmental and Occupational Medicine, Soonchunhyang University, 646 Eupnae-ri, Shinchang-myun, Asan-si, Choongnam 336-745 (Korea, Republic of); Kim, Yangho, E-mail: yanghokm@nuri.net [Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, 290-3 Cheonha-Dong, Dong-Gu, Ulsan 682-060 (Korea, Republic of)] [Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, 290-3 Cheonha-Dong, Dong-Gu, Ulsan 682-060 (Korea, Republic of)

2012-01-15

157

Chemically bonded phosphate ceramics of trivalent oxides of iron and manganese  

DOEpatents

A new method for combining elemental iron and other metals to form an inexpensive ceramic to stabilize arsenic, alkaline red mud wastes, swarfs, and other iron or metal-based additives, to create products and waste forms which can be poured or dye cast.

Wagh, Arun S. (Orland Park, IL); Jeong, Seung-Young (Westmont, IL)

2002-01-01

158

Cadmium (Cd(2+)) removal by nano zerovalent iron: surface analysis, effects of solution chemistry and surface complexation modeling.  

PubMed

Nano zerovalent iron (nZVI) is an effective remediant for removing various organic and inorganic pollutants from contaminated water sources. Batch experiments were conducted to characterize the nZVI surface and to investigate the effects of various solution properties such as pH, initial cadmium concentration, sorbent dosage, ionic strength, and competitive ions on cadmium removal by nZVI. Energy-dispersive X-ray and X-ray photoelectron spectroscopy results confirmed removal of Cd(2+) ions by nZVI through adsorption. Cd(2+) adsorption decreased in the presence of competitive cations in the order: Zn(2+)?>?Co(2+)?>?Mg(2+)?>?Mn(2+)?=?Cu(2+)?>?Ca(2+)?>?Na(2+)?=?K(+). Higher concentrations of Cl(-) significantly decreased the adsorption. Cadmium removal increased with solution pH and reached a maximum at pH 8.0. The effects of various solution properties indicated Cd(2+) adsorption on nZVI to be a chemisorption (inner-sphere complexation) process. The three surface complexation models (diffuse layer model, constant capacitance model, and triple layer model) fitted well to the adsorption edge experimental data indicating the formation of nZVI-Cd bidentate inner-sphere surface complexes. Our results suggest that nZVI can be effectively used for the removal of cadmium from contaminated water sources with varying chemical conditions. PMID:23589245

Boparai, Hardiljeet K; Joseph, Meera; O'Carroll, Denis M

2013-09-01

159

The Significance of Diagenesis versus Riverine Input in Contributing to the Sediment Geochemical Matrix of Iron and Manganese in an Intertidal Region  

NASA Astrophysics Data System (ADS)

Summer porewater and spring and summer surficial sediment samples were collected from 26 locations in the intertidal region of the Fraser River estuary. Porewaters were analysed for dissolved iron and manganese (as defined by species <0·2?m in diameter) to assess the contribution of diagenesis to concentrations of iron and manganese oxides at the sediment-water interface. Surficial sediment samples were geochemically characterized as: % organic matter (% LOI); reducible iron (RED Fe, iron oxides) and easily reducible manganese (ER Mn, manganese oxides). Grain size at each site was also determined. The sediment geochemical matrix, as defined by the above four parameters, was highly heterogeneous throughout the intertidal region (three-way ANOVA; P<0·0001). For RED Fe and ER Mn, this heterogeneity could be explained by either diagenetic processes (RED Fe) or by a combination of the proximity of the sample sites to the mouth of the Fraser River estuary plus diagenetic processes (ER Mn). Correlation (Spearman Rank Correlation Test (r s), of dissolved iron within the subsurface sediments with amounts of RED Fe recovered from the associated surface sediments was highly significant (r s=0·80, P<0·0001); high concentrations of RED Fe at the sediment-water interface co-occurred with high concentrations of dissolved iron, regardless of the proximity of the sample locations to riverine input. Compared with iron, the relationship between dissolved manganese and ER Mn from surface sediments was lower (r s=0·58; P<0·0008). Locations most strongly influenced by the Fraser River contained greater concentrations of ER Mn at the sediment-water interface than that which would be expected based on the contribution from diagenesis alone. Sediment grain size and organic matter were also influenced by the proximity to riverine input. Surficial sediment of sites close to the river mouth were comprised primarily of percent silt (2·0?m-50?m) whereas sites not influenced by riverine input were primarily percent sand (grain size >50?m). Concentrations of organic matter declined from the mouth to the foreslope of the estuary. With the exception of RED Fe, temporal variation (May vs July) was insignificant ( P>0·05, three-way ANOVA). Concentrations of RED Fe recovered from the surficial sediments were in general greater in the summer vs spring months, although spring and summer values were highly correlated (Pearson Product Moment Correlation Coefficient; PPCC; r=0·89; P<0·0001). As the bioavailability of metals is dependent on sediment geochemistry, availability throughout the intertidal region will also be spatially dependent. This heterogeneity needs to be taken into account in studies addressing the impact of metals on estuarine systems.

Thomas, C. A.; Bendell-Young, L. I.

1999-06-01

160

Elevated Airborne Exposures of Teenagers to Manganese, Chromium, and Iron from Steel Dust and New York City’s Subway System  

PubMed Central

There is increasing interest in potential health effects of airborne exposures to hazardous air pollutants at relatively low levels. This study focuses on sources, levels, and exposure pathways of manganese, chromium, and iron among inner-city high school students in New York City (NYC) and the contribution of subways. Samples of fine particulate matter (PM2.5) were collected during winter and summer over 48 h periods in a variety of settings including inside homes, outdoors, and personal samples (i.e., sampling packs carried by subjects). PM2.5 samples were also collected in the NYC subway system. For NYC, personal samples had significantly higher concentrations of iron, manganese, and chromium than did home indoor and ambient samples. The ratios and strong correlations between pairs of elements suggested steel dust as the source of these metals for a large subset of the personal samples. Time–activity data suggested NYC subways as a likely source of these elevated personal metals. In duplicate PM2.5 samples that integrated 8 h of underground subway exposure, iron, manganese, and chromium levels (>2 orders of magnitude above ambient levels) and their ratios were consistent with the elevated personal exposures. Steel dust in the NYC subway system was the dominant source of airborne exposures to iron, manganese, and chromium for many young people enrolled in this study, with the same results expected for other NYC subway riders who do not have occupational exposures to these metals. However, there are currently no known health effects at the exposure levels observed in this study. PMID:14968857

CHILLRUD, STEVEN N.; EPSTEIN, DAVID; ROSS, JAMES M.; SAX, SONJA N.; PEDERSON, DEE; SPENGLER, JOHN D.; KINNEY, PATRICK L.

2011-01-01

161

Alterations in plasma essential trace elements selenium, manganese, zinc, copper, and iron concentrations and the possible role of these elements on oxidative status in patients with childhood asthma  

Microsoft Academic Search

The aim of the present study is to evaluate the status of plasma essential trace element selenium (Se), manganese (Mn), copper\\u000a (Cu), zinc (Zn), and iron (Fe) concentrations and the effect of these elements on oxidative status in patients with childhood\\u000a asthma. Plasma Se, Mn, Cu, and Zn concentrations were determined by atomic absorption spectrophotometry (AAS) and Fe concentrations,\\u000a malondialdehyde

A. Kocyigit; F. Armutcu; A. Gurel; B. Ermis

2004-01-01

162

Mixed Ligand Complexes of Chromium(III), Manganese(III), Iron(III) And Cobalt(III) With Dipicolinic Acid and Some Monobasic Bidentate Nitrogen, Oxygen Donor Ligands  

Microsoft Academic Search

The mixed-ligand complexes of trivalent chromium, manganese, iron and cobalt of type [M(dipic)(N-O)] nH2O (Where dipicH2 = pyridine-2, 6-dicarboxylic acid or dipicolinic acid; N-OH represents different nitrogen, oxygen donor ligands viz., picolinic acid, nicotinic acid, isonicotinic acid, glycine, aminophenol, o-aminobenzoic acid or p-aminobenzoic acid) have been prepared and characterized on the basis of elemental analyses, magnetic susceptibility measurements and spectral

S. K. Sengupta; S. K. Sahni; R. N. Kapoor

1983-01-01

163

Iron and manganese reduction driven by organic matter and mixing of fresh and saline groundwater in the Fraser River Delta aquifer, Vancouver, Canada  

NASA Astrophysics Data System (ADS)

We present results of field investigations of the biogeochemistry of an aquifer a few km from the ocean adjacent to the Fraser River in Vancouver, Canada. At the site, a wedge of relatively dense saline ocean water enters the aquifer in the hyporheic zone at the river bottom, migrates away from the river along the base of the aquifer to a maximum distance of approximately 500m inland, where it overturns and mixes with fresh groundwater. The mixed saline - fresh water then flows back under a regional freshwater gradient and eventually discharges to the river at the top of the saline wedge. Pore waters show iron concentrations peak at over 300 ppm (5.4 mM) and manganese at 7 ppm (0.13 mM) at the interface between terrestrial recharge and top of the overturned saline groundwater. The reducible concentrations on the sediment are approximately 5000 ppm (solid/solid) iron and 70 ppm manganese. At present flow rates and fluxes of organic matter, between 300 and 1500 pore volumes are required to flush iron completely from the aquifer. Since the presence of organic matter, the dominant process is reductive dissolution of iron and manganese oxide minerals via organic matter oxidation, although acid-volatile sulfide and methane measurements show that both sulfate reduction and methanogenesis are also occurring. Dissolved organic matter concentrations range between 5 and 30 ppm. Excitation - emission fluorescence spectroscopy is used to help identify the distinct sources of dissolved organic matter, which include terrestrial from fresh recharge, detrital from sediments and from inflowing ocean water. Kinetic reactive-transport modeling that includes primary mineral redox reactions and secondary mineral precipitation was used to: i) interpret the role of mixing of fresh and saline water, ii) to constrain reduction rate parameters and metabolic activity levels from field data, including oxidation rate of organic matter by iron and manganese oxides, probably accompanied with sulfate reduction and methanogenesis. iii) to understand how other secondary minerals further control aqueous ferrous iron and manganese concentration through mineral precipitation/dissolution processes.

Jia, K.; Beckie, R. D.

2013-12-01

164

Metallation and mismetallation of iron and manganese proteins in vitro and in vivo: the class I ribonucleotide reductases as a case study.  

PubMed

How cells ensure correct metallation of a given protein and whether a degree of promiscuity in metal binding has evolved are largely unanswered questions. In a classic case, iron- and manganese-dependent superoxide dismutases (SODs) catalyze the disproportionation of superoxide using highly similar protein scaffolds and nearly identical active sites. However, most of these enzymes are active with only one metal, although both metals can bind in vitro and in vivo. Iron(ii) and manganese(ii) bind weakly to most proteins and possess similar coordination preferences. Their distinct redox properties suggest that they are unlikely to be interchangeable in biological systems except when they function in Lewis acid catalytic roles, yet recent work suggests this is not always the case. This review summarizes the diversity of ways in which iron and manganese are substituted in similar or identical protein frameworks. As models, we discuss (1) enzymes, such as epimerases, thought to use Fe(II) as a Lewis acid under normal growth conditions but which switch to Mn(II) under oxidative stress; (2) extradiol dioxygenases, which have been found to use both Fe(II) and Mn(II), the redox role of which in catalysis remains to be elucidated; (3) SODs, which use redox chemistry and are generally metal-specific; and (4) the class I ribonucleotide reductases (RNRs), which have evolved unique biosynthetic pathways to control metallation. The primary focus is the class Ib RNRs, which can catalyze formation of a stable radical on a tyrosine residue in their ?2 subunits using either a di-iron or a recently characterized dimanganese cofactor. The physiological roles of enzymes that can switch between iron and manganese cofactors are discussed, as are insights obtained from the studies of many groups regarding iron and manganese homeostasis and the divergent and convergent strategies organisms use for control of protein metallation. We propose that, in many of the systems discussed, "discrimination" between metals is not performed by the protein itself, but it is instead determined by the environment in which the protein is expressed. PMID:22991063

Cotruvo, Joseph A; Stubbe, Joanne

2012-10-01

165

Metallation and mismetallation of iron and manganese proteins in vitro and in vivo: the class I ribonucleotide reductases as a case study  

PubMed Central

How cells ensure correct metallation of a given protein and whether a degree of promiscuity in metal binding has evolved are largely unanswered questions. In a classic case, iron- and manganese-dependent superoxide dismutases (SODs) catalyze the disproportionation of superoxide using highly similar protein scaffolds and nearly identical active sites. However, most of these enzymes are active with only one metal, although both metals can bind in vitro and in vivo. Iron(II) and manganese(II) bind weakly to most proteins and possess similar coordination preferences. Their distinct redox properties suggest that they are unlikely to be interchangeable in biological systems except when they function in Lewis acid catalytic roles, yet recent work suggests this is not always the case. This review summarizes the diversity of ways in which iron and manganese are substituted in similar or identical protein frameworks. As models, we discuss (1) enzymes, such as epimerases, thought to use FeII as a Lewis acid under normal growth conditions but which switch to MnII under oxidative stress; (2) extradiol dioxygenases, which have been found to use both FeII and MnII, the redox role of which in catalysis remains to be elucidated; (3) SODs, which use redox chemistry and are generally metal-specific; and (4) the class I ribonucleotide reductases (RNRs), which have evolved unique biosynthetic pathways to control metallation. The primary focus is the class Ib RNRs, which can catalyze formation of a stable radical on a tyrosine residue in their ?2 subunits using either a di-iron or a recently characterized dimanganese cofactor. The physiological roles of enzymes that can switch between iron and manganese cofactors are discussed, as are insights obtained from the studies of many groups regarding iron and manganese homeostasis and the divergent and convergent strategies organisms use for control of protein metallation. We propose that, in many of the systems discussed, “discrimination” between metals is not performed by the protein itself, but it is instead determined by the environment in which the protein is expressed. PMID:22991063

Cotruvo, Joseph A.; Stubbe, JoAnne

2012-01-01

166

Extracting iron and manganese from bacteria with ionophores - a mechanism against competitors characterized by increased potency in environments low in micronutrients.  

PubMed

To maintain their metal ion homeostasis, bacteria critically depend on membrane integrity and controlled ion translocation. Terrestrial Streptomyces species undermine the function of the cytoplasmic membrane as diffusion barrier for metal cations in competitors using ionophores. Although the properties of the divalent cation ionophores calcimycin and ionomycin have been characterized to some extent in vitro, their effects on bacterial ion homeostasis, the factors leading to bacterial cell death, and their ecological role are poorly understood. To gain insight into their antibacterial mechanism, we determined the metal ion composition of the soil bacterium Bacillus subtilis after treatment with calcimycin and ionomycin. Within 15 min the cells lost approximately half of their cellular iron and manganese content whereas calcium levels increased. The proteomic response of B. subtilis provided evidence that disturbance of metal cation homeostasis is accompanied by intracellular oxidative stress, which was confirmed with a ROS-specific fluorescent probe. B. subtilis showed enhanced sensitivity to the ionophores in medium lacking iron or manganese. Furthermore, in the presence of ionophores bacteria were sensitive to high calcium levels. These findings suggest that divalent cation ionophores are particularly effective against competing microorganisms in soils rich in available calcium and low in available iron and manganese. PMID:23412951

Raatschen, Nadja; Wenzel, Michaela; Ole Leichert, Lars Ingo; Düchting, Petra; Krämer, Ute; Bandow, Julia Elisabeth

2013-04-01

167

Fast ultrasound-assisted extraction of copper, iron, manganese and zinc from human hair samples prior to flow injection flame atomic absorption spectrometric detection.  

PubMed

A dynamic ultrasound-assisted extraction procedure utilizing diluted nitric acid was developed for the determination of copper, iron, manganese and zinc in human hair taken from workers in permanent contact with a polluted environment. The extraction unit of the dynamic ultrasound-assisted extraction system contains a minicolumn into which a specified amount of hair (5-50 mg) is placed. Once inserted into the continuous manifold, trace metals were extracted at 3 mL min(-1) with 3 mol L(-1) nitric acid under the action of ultrasound for 2 min for zinc and 3 min for copper, iron and manganese determination, and using an ultrasonic water-bath temperature of 70 degrees C for zinc and 80 degrees C for copper, iron and manganese determination. The system permits the direct analysis of hair and yields concentrations with relative standard deviations of <3% (n = 11). The applicability of the procedure was verified by analysing human hair samples from workers exposed to welding fumes, and its accuracy was assessed through comparison with a conventional sample dissolution procedure and the use of a certified reference material (BCR 397, human hair). PMID:17404713

Yebra-Biurrun, M C; Cespón-Romero, R M

2007-06-01

168

Arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in feathers of Black-legged Kittiwake (Rissa tridactyla) and Black Oystercatcher (Haematopus bachmani) from Prince William Sound, Alaska.  

PubMed

Arsenic, cadmium, chromium, lead, manganese, mercury and selenium were analyzed in the feathers of Black-legged Kittiwakes (Rissa tridactyla) from Shoup Bay in Prince William Sound, Alaska to determine if there were age-related differences in metal levels, and in Black Oystercatchers (Haematopus bachmani)) from the same region to determine if there were differences in oiled and unoiled birds. Except for mercury, there were no age-related differences in metals levels in the feathers of kittiwakes. Kittiwakes over 13 years of age had the highest levels of mercury. There were no differences in levels of metals in the feathers of oystercatchers from oiled and unoiled regions of Prince William Sound. Except for mercury, the feathers of oystercatchers had significantly higher levels of all metals than those of kittiwakes. Levels of mercury in kittiwake feathers (mean of 2910 ng/g [ppb]) were within the range of many species of seabirds reported for other studies, and were generally below adverse effects levels. PMID:18440597

Burger, Joanna; Gochfeld, Michael; Sullivan, Kelsey; Irons, David; McKnight, Aly

2008-07-15

169

Optical Absorption Studies of the Diluted Magnetic Semiconductors ZINC(1-X)MANGANESE(X)TELLURIUM, CADMIUM(1 - and ZINC(1-X)MANGANESE(X)SELENIUM.  

NASA Astrophysics Data System (ADS)

Optical absorption measurements were carried out on the dilute magnetic semiconductors Zn(,1-x)Mn(,x)Te, Cd(,1-x)Mn(,x)Se, and Zn(,1-x)Mn(,x)Se: high manganese concentration was emphasized. For photon energies in the vicinity of the intrinsic absorption, sample thicknesses down to (TURN)10 (mu) were required. Results were obtained at room temperature, liquid nitrogen, and liquid helium. Samples of the zincblende crystal Zn(,1-x)Mn(,x)Te were studied at compositions x (TURN) 0.1, x (TURN) 0.5, and x (TURN) 0.6. Three absorption bands with maxima at (TURN)2.33, (TURN)2.40, and (TURN)2.605 eV, are respectively asso- ciated with the Mn('2+) intraion transitions in the 3d('5) configuration: ('6)A(,1)(('6)S) (--->) ('4)T(,1)(('4)G), ('6)A(,1)(('6)S) (--->) ('4)T(,2)(('4)G), and ('6)A(,1)(('6)S) (--->) ('4)A(,1), ('4)E(('4)G). A fourth absorption band (at 2.745 eV) although unidentified, is thought to be Mn related. Samples of the wurtzite crystal Cd(,1-x)Mn(,x)Se were studied at compositions x (TURN) 0.3, x (TURN) 0.42, and x (TURN) 0.45. In all samples, the intrinsic absorption edge exhibits the dichroism associated with the hexagonal structure. A strong Mn-related absorption edge is shown to exist in the two highest x samples at low temperatures, and is identified as the ('6)A(,1)(('6)S) (--->) ('4)T(,1)(('4)G) Mn('2+) intraion transition. The crystal field splitting (DELTA), obtained from the dichroism of the intrinsic edge, is found to be temperature dependent. A weak absorption band found below the Mn edge is known to give rise to the excitation spectrum of a known 1.35 eV emission band. Zn(,1-x)Mn(,x)Se is a zincblende crystal for x < 0.35 and wurtzite for 0.35 < x < 0.57. Samples with x (TURN) 0.23, x (TURN) 0.35, and x (TURN) 0.5 were studied. Three absorption bands with maxima at (TURN)2.42, (TURN)2.54, and (TURN)2.70 eV, are identified as the same three Mn related bands observed in Zn(,1-x)Mn(,x)Te. A higher absorption band at ((TURN)2.92 eV) is also seen. Polarization effects in the Mn-related absorption bands appear to be systematic. A region of broad absorption is seen below the Mn edge. The temperature dependent dichroism observed at high x in Cd(,1 -x)Mn(,x)Se is also found in wurtzite phase Zn(,1-x)Mn(,x)Se. Both behaviors are explained in terms of an acceptor-bound magnetic polaron. In all samples with high x, an anomalous increase in the energy of the intrinsic absorption edge occurs below the LN(,2) temperature. This result is understood on the basis of a blue shift of the intrinsic edge due to the onset of a magnetic phase transition.

Morales Toro, Juan Eduardo

170

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

NASA Astrophysics Data System (ADS)

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, elevating the total P burial rate above that expected for a euxinic depositional environment. Particle shuttles of Fe and Mn oxides into the deep euxinic basins act as drivers for P-bearing mineral authigenesis. While Fe(II) phosphates are formed continuously in the upper sediments following the sulfidization of Fe-oxyhydroxides and release of associated P, Mn-Ca-carbonate-phosphates are formed intermittently following inflow events of oxygenated North Sea water into the deep basins. The mechanism of Fe(II) phosphate formation differs from previously reported occurrences of vivianite formation in marine sediments, by occurring within, rather than below, the sulfate-methane transition zone. The spatial distribution of both authigenic phases in Baltic sediments varies in accordance with the periodic expansion of anoxia on centennial to millennial timescales. The results highlight the potential importance of authigenic P-bearing minerals other than carbonate fluorapatite for total P burial in euxinic basins.

Jilbert, Tom; Slomp, Caroline P.

2013-04-01

171

Manganese, iron and sulfur cycling in a coastal marine sediment, Aarhus bay, Denmark  

Microsoft Academic Search

The seasonal variation in oxidized and reduced pools of Mn, Fe and S, as well as the rates of SO 4 2- reduction, were studied in a fine-grained sediment. Below the 1-5 mm thick oxic zone, a zone of net Mn reduction extended to 1-2 cm depth, while iron reduction was found to 4-6 cm depth. Although the reactive Mn

Bo Thamdrup; Henrik Fossing; Bo Barker Jørgensen

1994-01-01

172

Microbial reduction of manganese and iron: New approaches to carbon cycling. [Shewanella putrefaciens  

SciTech Connect

This brief review introduces the reader to the importance and conceptual aspects of microbial metal reduction by focusing on a single group of Mn(IV)- and Fe(III)-reducing organisms in the group Shewanella putrefaciens. While this group is abundant and of worldwide distribution, it is only the tip of a very large iceberg' of metal reducers. A good example of another metal reducer is the organism GS-15, an obligate anaerobe with substantial carbon versatility and an ability to tolerate very high concentrations of metals. In addition, the authors have now isolated over 200 strains of manganese reducers (MR-203 is their latest organism), consisting of a wide variety of different taxa, including Pseudomonas spp., Bacillus spp., and many others. These isolates are from very diverse environments, including Lake Oneida, N.Y.; Lake Michigan; Green Bay, Wis.; the Black Sea; and Lake Baikal, USSR. A careful coupling of field and laboratory studies will be needed before the importance of these metal-reducing microbes, and their associated activities, are adequately understood.

Nealson, K.H. (Univ. of Wisconsin, Milwaukee (United States)); Myers, C.R. (Medical Coll. of Wisconsin, Milwaukee (United States))

1992-02-01

173

Poly[[hexa-?-cyanido-manganese(II)iron(III)] penta­hydrate  

PubMed Central

The structure of the title compound, MnII[FeIII(CN)6]2/3·5H2O, features a face-centered cubic –Mn—NC—Fe– framework with both Mn and Fe having site symmetry m m. Since one-third of the [Fe(CN)6]3? units are missing for a given formula in order to maintain charge neutrality, each Mn atom around such a vacancy is coordinated not only by the N atoms of the CN groups but also by the O atoms of the ligand water mol­ecules. In addition to ligand water mol­ecules, two types of non-coordinated water mol­ecules, so-called zeolitic water mol­ecules, exist in the inter­stitial sites of the –Mn—NC—Fe– framework. The positions of the O atoms of the zeolitic water mol­ecules are fixed by the linkage via hydrogen bonds between ligand water and zeolitic water mol­ecules. The structure is related to a recently reported rubidium manganese hexa­cyano­ferrate. Site occupancy factors for Fe, C, N are 0.67; for two O atoms the value is 0.83 and for one O atom is 0.17. PMID:21201245

Matsuda, Tomoyuki; Tokoro, Hiroko; Shiro, Motoo; Hashimoto, Kazuhito; Ohkoshi, Shin-ichi

2008-01-01

174

Relationship of manganese-iron oxides and associated heavy metals to grain size in stream sediments  

USGS Publications Warehouse

The distribution of ammonium citrate-leachable lead, zinc and cadmium among size fractions in stream sediments is strongly influenced by the presence of hydrous Mn-Fe oxides in the form of coatings on sediment grains. Distribution curves showing leachable metals as a function of particle size are given for eight samples from streams in New York State. These show certain features in common; in particular two concentrations of metals, one in the finest fractions, and a second peak in the coarse sand and gravel fraction. The latter can be explained as a result of the increasing prevalence and thickness of oxide coatings with increasing particle size, with the oxides serving as collectors for the heavy metals. The distribution of Zn and Cd in most of the samples closely parallels that of Mn; the distribution of Pb is less regular and appears to be related to Fe in some samples and Mn in others. The concentration of metals in the coarse fractions due to oxide coatings, combined with the common occurrence of oxide deposition in streams of glaciated regions, raises the possibility of using coarse materials for geochemical surveys and environmental heavy-metal studies. ?? 1975.

Whitney, P.R.

1975-01-01

175

Highly sensitive and selective fluorimetric methods for the determination of iron(III) and manganese(II) using fluorescein\\/hydrogen peroxide\\/triethylenetetramine and fluorescein\\/hydrogen peroxide\\/triethylenetetramine\\/tiron, respectively  

Microsoft Academic Search

Highly sensitive and selective spectrofluoriphotometric determinations of iron(III) with fluorescein(Fl)-hydrogen peroxide-triethylenetetramine (TETA), and manganese(II) with Fl-hydrogen peroxide-TETA-tiron are proposed. The methods are based on the inhibition of the oxidizing decomposition of Fl-hydrogen peroxide solution in the presence of iron(III)-TETA or manganese(II)-TETA-tiron combination. The calibration graphs are linear in the ranges of up to 220 ng iron(III) and up to 270

I. Mori; Y. Fujita; K. Ikuta; Y. Nakahashi; K. Kato

1989-01-01

176

Kinetic investigation of the rate-limiting step of manganese- and iron-lipoxygenases.  

PubMed

Lipoxygenases (LOX) oxidize polyunsaturated fatty acids to hydroperoxides, which are generated by proton coupled electron transfer to the metal center with FeIIIOH- or MnIIIOH-. Hydrogen abstraction by FeIIIOH- of soybean LOX-1 (sLOX-1) is associated with a large deuterium kinetic isotope effect (D-KIE). Our goal was to compare the D-KIE and other kinetic parameters at different temperatures of sLOX-1 with 13R-LOX with catalytic manganese (13R-MnLOX). The reaction rate and the D-KIE of sLOX-1 with unlabeled and [11-2H2]18:2n-6 were almost temperature independent with an apparent D-KIE of ?56 at 30°C, which is in agreement with previous studies. In contrast, the reaction rate of 13R-MnLOX increased 7-fold with temperature (8-50°C), and the apparent D-KIE decreased linearly from ?38 at 8°C to ?20 at 50°C. The kinetic lag phase of 13R-MnLOX was consistently extended at low temperatures. The Phe337Ile mutant of 13R-MnLOX, which catalyzes antarafacial hydrogen abstraction and oxygenation in analogy with sLOX-1, retained the large D-KIE and its temperature-dependent reaction rate. The kinetic differences between 13R-MnLOX and sLOX-1 may be due to protein dynamics, hydrogen donor-acceptor distances, and to the metal ligands, which may not equalize the 0.7V-gap between the redox potentials of the free metals. PMID:24857825

Wennman, Anneli; Karkehabadi, Saeid; Oliw, Ernst H

2014-08-01

177

Characterization, activity and mechanisms of a visible light driven photocatalyst: Manganese and iron co-modified TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

An attempt was made to prepare Mn,Fe-codoped nanostructured TiO2 photocatalyst for visible light assisted degradation of an azo dye (methylene blue) in aqueous solutions by a sol-gel process. The asprepared nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL) techniques. The photocatalytic activity of Mn,Fe-codoped TiO2 catalyst was evaluated by measuring degradation rates of methylene blue (MB) under visible light. The results showed that doping with the manganese and iron ions significantly enhanced the photocatalytic activity for MB degradation under visible light irradiation. This was ascribed to the fact that a small amount of manganese and iron dopants simultaneously increased MB adsorption capacity and separation efficiency of electron-hole pairs. The results of DRS showed that Mn,Fe-codoped TiO2 had significant absorption between 400 and 500 nm, which increased with the increase of manganese ion content. It is found that the stronger the PL intensity, the higher the photocatalytic activity. This could be explained by the points that PL spectra mainly resulted from surface oxygen vacancies and defects during the process of PL, while surface oxygen vacancies and defects could be favorable in capturing the photoinduced electrons during the process of photocatalytic reactions, so that the recombination of photoinduced electrons and holes could be effectively inhibited.

Zhang, Dongfang; Zeng, Fanbin

2011-10-01

178

An Experimental Study of Molten Salt Electrorefining of Uranium Using Solid Iron Cathode and Liquid Cadmium Cathode for Development of Pyrometallurgical Reprocessing  

Microsoft Academic Search

Electrorefining of uranium was studied for developing pyrometallurgical reprocessing technology of metal fuel cycle. After concentration dependence of polarization curve was measured, uranium was electrodeposited either on solid iron cathode or in liquid cadmium cathode. Design and operational conditions of the cathode were improved for obtaining much greater quantity of deposit, resulting in recovery of 732g of dendritic uranium on

Tadafumi KOYAMA; Masatoshi IIZUKA; Yuichi SHOJI; Reiko FUJITA; Hiroshi TANAKA; Tsuguyuki KOBAYASHI; Moriyasu TOKIWAI

1997-01-01

179

The abundance of iron-peak elements and the dust composition in ? Carinae: manganese  

NASA Astrophysics Data System (ADS)

We study the chemical abundances of the strontium filament found in the ejecta of ? Carinae. In particular, we derive the abundances of iron-peak elements from the spectra of their singly ionized ions present in the optical/infrared (IR) spectra. In this paper we analyse the spectrum of Mn II using a new non-local thermodynamic equilibrium (non-LTE) model for this system. In constructing this models we carried out theoretical calculations of radiative transition rates and electron impact excitation rate coefficients. We find that relative to Ni the gas-phase abundance ratio of Mn is roughly solar, similar to the Cr abundance but in contrast to the large enhancements in the abundances of Sc and Ti. We interpret this result as an indication of non-equilibrium condensation in the ejecta of ? Carinae.

Bautista, M. A.; Meléndez, M.; Hartman, H.; Gull, T. R.; Lodders, K.

2011-02-01

180

Arsenic, iron, lead, manganese, and uranium concentrations in private bedrock wells in southeastern New Hampshire, 2012-2013  

USGS Publications Warehouse

Trace metals, such as arsenic, iron, lead, manganese, and uranium, in groundwater used for drinking have long been a concern because of the potential adverse effects on human health and the aesthetic or nuisance problems that some present. Moderate to high concentrations of the trace metal arsenic have been identified in drinking water from groundwater sources in southeastern New Hampshire, a rapidly growing region of the State (Montgomery and others, 2003). During the past decade (2000–10), southeastern New Hampshire, which is composed of Hillsborough, Rockingham, and Strafford Counties, has grown in population by nearly 48,700 (or 6.4 percent) to 819,100. These three counties contain 62 percent of the State’s population but encompass only about 22 percent of the land area (New Hampshire Office of Energy and Planning, 2011). According to a 2005 water-use study (Hayes and Horn, 2009), about 39 percent of the population in these three counties in southeastern New Hampshire uses private wells as sources of drinking water, and these wells are not required by the State to be routinely tested for trace metals or other contaminants. Some trace metals have associated human-health benchmarks or nonhealth guidelines that have been established by the U.S. Environmental Protection Agency (EPA) to regulate public water supplies. The EPA has established a maximum contaminant level (MCL) of 10 micrograms per liter (?g/L) for arsenic (As) and a MCL of 30 ?g/L for uranium (U) because of associated health risks (U.S. Environmental Protection Agency, 2012). Iron (Fe) and manganese (Mn) are essential for human health, but Mn at high doses may have adverse cognitive effects in children (Bouchard and others, 2011; Agency for Toxic Substances and Disease Registry, 2012); therefore, the EPA has issued a lifetime health advisory (LHA) of 300 ?g/L for Mn. Recommended secondary maximum contaminant levels (SMCLs) for Fe (300 ?g/L) and Mn (50 ?g/L) were established primarily as nonhealth guidelines—based on aesthetic considerations, such as taste or the staining of laundry and plumbing fixtures—because these contaminants, at the SMCLs, are not considered to present risks to human health. Because lead (Pb) contamination of drinking water typically results from corrosion of plumbing materials belonging to water-system customers but still poses a risk to human health, the EPA established an action level (AL) of 15 ?g/L for Pb instead of an MCL or SMCL (U.S. Environmental Protection Agency, 2012). The 15-?g/L AL for Pb has been adopted by the New Hampshire Department of Environmental Services for public water systems, and if exceeded, the public water system must inform their customers and undertake additional actions to control corrosion in the pipes of the distribution system (New Hampshire Department of Environmental Services, 2013). Unlike the quality of drinking water provided by public water suppliers, the quality of drinking water obtained from private wells in New Hampshire is not regulated; consequently, private wells are sampled only when individual well owners voluntarily choose to sample them. The U.S. Geological Survey (USGS), in cooperation with the EPA New England, conducted an assessment in 2012–13 to provide private well owners and State and Federal health officials with information on the distribution of trace-metal (As, Fe, Pb, Mn, and U) concentrations in groundwater from bedrock aquifers in the three counties of southeastern New Hampshire. This fact sheet analyzes data from water samples collected by a randomly selected group of private well owners from the three-county study area and describes the major findings for trace-metal concentrations.

Flanagan, Sarah M.; Belaval, Marcel; Ayotte, Joseph D.

2014-01-01

181

Differential effects of salen and manganese-salen complex (EUK-8) on the regulation of cellular cadmium uptake and toxicity.  

PubMed

Cadmium (Cd) stimulates the production of reactive oxygen species (ROS) and causes cell damage. We investigated here the feasibility of using a cell permeable superoxide dismutase/catalase mimetic, EUK-8, to reduce the Cd-induced ROS and cytotoxicity in Chinese hamster ovary cells. EUK-8 reduces the ROS level caused by Cd treatment. EUK-8 also curtails propidium iodide (PI) influx and increases the viability of Cd-treated cells. The efficacy of EUK-8 as a Cd antidote diminishes gradually when added at a later stage of Cd treatment. EUK-8 blocks Cd transport into cells. It is ineffective in accelerating the efflux of metals from the cells. EUK-8 is a Mn-salen complex. Mn decreases the uptake and cytotoxicity of Cd, while salen perturbs the membrane integrity and increases the uptake and cytotoxicity of Cd. Salen is able to bind Cd, and the Cd-salen complex formed does not perturb the integrity of cell membranes and thus the influx of metal is not enhanced. Our results reveal a differential effect of salen and Mn-salen complex on the transport of Cd with subsequent different levels of cell damage. PMID:15689422

Yang, Pei-Ming; Chiu, Shu-Jun; Lin, Lih-Yuan

2005-05-01

182

Activation of ethane in the presence of solid acids: Sulfated zirconia, iron- and manganese-promoted sulfated zirconia, and zeolites  

SciTech Connect

Ethane was activated in the presence of solid acids [sulfated zirconia (SZ), iron- and manganese-promoted sulfated zirconia (FMSZ), HZSM-5, and USY zeolite] at 1 atm, 200-450{degrees}C, and ethane partial pressures in the range 0.014.2 atm. The data were measured with a flow reactor at low conversions (<0.005) such that reaction of ethane took place in the near absence of alkenes. Catalysis was demonstrated for ethane conversion in the presence of FMSZ at 450{degrees}C and 0.2 atm ethane partial pressure, but the reactions were not shown to be catalytic for the other solid acids and other conditions. FMSZ was active for converting ethane into methane, ethene, and butane at an ethane partial pressure of 0.2 atm and at temperatures of 200-300{degrees}C; the other solid acids had no detectable activities under these conditions. At higher temperatures, each of the solid acids was active for conversion of ethane into ethene; butane and methane were also formed in the presence of FMSZ, HZSM-5, and USY zeolite, whereas methane was the only other hydrocarbon observed in the presence of SZ. The initial (5 min on stream) selectivities to ethene at approximately 0.1 % conversion, ethane partial pressure of 0.2 atm, and 450{degrees}C were approximately 98, 94, 97, and 99%, for SZ, FMSZ, HZSM-5, and USY zeolite, respectively. Under the same reaction conditions, the initial rates of ethane conversion were 0. 1 5 x 10{sup -8}, 3.5 x 10{sup -8} 3.9 x 10{sup -8}, and 0.56 x 10{sup -8} mol/(s {circ} g) for SZ, FMSZ, HZSM-5, and USY zeolite, respectively. The reactivities are consistent with chemistry analogous to that occurring in superacidic solutions and with the suggestion that FMSZ is a stronger acid than the others investigated here. 25 refs., 13 figs., 1 tab.

Cheung, Tsz-Keung; Gates, B. [Univ. of California, Davis, CA (United States)] [Univ. of California, Davis, CA (United States)

1997-06-01

183

Efflux of Iron from the Cerebrospinal Fluid to the Blood at the Blood-CSF Barrier: Effect of Manganese Exposure  

PubMed Central

The blood-cerebrospinal fluid (CSF) barrier (BCB) resides within the choroid plexus, with the apical side facing the CSF and the basolateral side towards the blood. Previous studies demonstrate that manganese (Mn) exposure in rats disrupts iron (Fe) homeostasis in the blood and CSF. The present study used a primary culture of rat choroidal epithelial cells grown in the two-chamber Transwell system to investigate the transepithelial transport of Fe across the BCB. Free, unbound Fe as [59Fe] was added to the donor chamber and the radioactivity in the acceptor chamber was quantified to determine the direction of Fe fluxes. Under the normal condition, the [59Fe] efflux (from the CSF to the blood) was 128% higher than that of the influx (P < 0.01). Mn exposure significantly increased the efflux rate of [59Fe] (P < 0.01) and the effect was inhibited when the cells were pre-incubated with the antibody against divalent metal transport 1 (DMT1). Moreover, when the siRNA knocked down the cellular DMT1 expression, the elevated Fe uptake caused by Mn exposure in the choroidal epithelial Z310 cells was completely abolished, indicating that Mn may facilitate Fe efflux via a DMT1-mediated transport mechanism. In vivo subchronic exposure to Mn in rats reduced Fe clearance from the CSF, as demonstrated by the ventriculo-cisternal brain perfusion, along with up-regulated mRNAs encoding DMT1 and transferrin receptor (TfR) in the same animals. Taken together, these data suggest that free Fe appears to be favorably transported from the CSF toward the blood by DMT1 and this process can be facilitated by Mn exposure. Enhanced TfR-mediated influx of Fe from the blood and ferroportin-mediated expelling Fe toward the CSF may compromise DMT1-mediated efflux, leading to an increased Fe concentration in the CSF as seen in Mn-exposed animals. PMID:18849539

Wang, Xueqian; Li, G. Jane; Zheng, Wei

2014-01-01

184

Biodistribution and acute toxicity of a nanofluid containing manganese iron oxide nanoparticles produced by a mechanochemical process  

PubMed Central

Superparamagnetic iron oxide nanoparticles are candidate contrast agents for magnetic resonance imaging and targeted drug delivery. Biodistribution and toxicity assessment are critical for the development of nanoparticle-based drugs, because of nanoparticle-enhanced biological reactivity. Here, we investigated the uptake, in vivo biodistribution, and in vitro and in vivo potential toxicity of manganese ferrite (MnFe2O4) nanoparticles, synthesized by an original high-yield, low-cost mechanochemical process. Cultures of murine Balb/3T3 fibroblasts were exposed for 24, 48, or 72 hours to increasing ferrofluid concentrations. Nanoparticle cellular uptake was assessed by flow-cytometry scatter-light measurements and microscopy imaging after Prussian blue staining; cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony-forming assays. After a single intravenous injection, in vivo nanoparticle biodistribution and clearance were evaluated in mice by Mn spectrophotometric determination and Prussian blue staining in the liver, kidneys, spleen, and brain at different posttreatment times up to 21 days. The same organs were analyzed for any possible histopathological change. The in vitro study demonstrated dose-dependent nanoparticle uptake and statistically significant cytotoxic effects from a concentration of 50 ?g/mL for the MTT assay and 20 ?g/mL for the colony-forming assay. Significant increases in Mn concentrations were detected in all analyzed organs, peaking at 6 hours after injection and then gradually declining. Clearance appeared complete at 7 days in the kidneys, spleen, and brain, whereas in the liver Mn levels remained statistically higher than in vehicle-treated mice up to 3 weeks postinjection. No evidence of irreversible histopathological damage to any of the tested organs was observed. A comparison of the lowest in vitro toxic concentration with the intravenously injected dose and the administered dose of other ferrofluid drugs currently in clinical practice suggests that there might be sufficient safety margins for further development of our formulation. PMID:24790434

Bellusci, Mariangela; La Barbera, Aurelio; Padella, Franco; Mancuso, Mariateresa; Pasquo, Alessandra; Grollino, Maria Giuseppa; Leter, Giorgio; Nardi, Elisa; Cremisini, Carlo; Giardullo, Paola; Pacchierotti, Francesca

2014-01-01

185

Redox zonation at the saline-influenced boundaries of a permeable surficial aquifer: effects of physical forcing on the biogeochemical cycling of iron and manganese  

NASA Astrophysics Data System (ADS)

Research investigating geochemical changes accompanying subsurface mixing of fresh and saline water has primarily focused on cation exchange and mineral dissolution/precipitation reactions. In this study, we report on redox species zonation at the boundaries of a freshwater lens confined beneath a small, permeable island surrounded by saline marshes and tidal creeks and located on the estuary side of Sapelo Island, Georgia. The spatial and temporal distribution of the chemical species in the aquifer implies that the freshwater lens resists saline intrusion by maintaining constant advection across the salinity gradient. As a result, the biogeochemical processes in this aquifer seem to have reached a quasi steady-state very close to equilibrium. Redox reactions associated with natural organic matter oxidation may also play an important role at the salinity transition. Surprisingly, aerobic respiration and microbial iron reduction seem to be the main pathways for natural organic matter oxidation. Sulfate reduction is not significant despite the high concentration of sulfate available, and manganese oxides are probably chemically reduced by dissolved sulfide and Fe 2+. This study is the first to demonstrate that iron and manganese reduction takes place at the salinity transitions bounding both sides of an island freshwater lens and that microbial iron reduction accounts for most of anaerobic respiration of natural organic matter at these transitions.

Snyder, M.; Taillefert, M.; Ruppel, C.

2004-08-01

186

Evolution of novel bioresorbable iron-manganese implant surfaces and their degradation behaviors in vitro.  

PubMed

The purpose of this study is to advance understanding of surface degradation kinetics for Fe-Mn bioresorbable alloys (specifically Fe-20%Mn) and target degradable fracture fixation implants for hard tissues. This study addresses how arc melted Fe-20%Mn discs degrade in a static, osteogenic medium for up to a 3 month time span. Degradation behavior of these bulk alloys was investigated using both mass loss tests for measuring long-term corrosion rates and potentiostatic tests for following the instantaneous rate of degradation. It was discovered that cold-rolling Fe-20%Mn to 77% cold work (CW) suppressed the instantaneous corrosion rate compared with the cast structure. It was also found that an unstable iron-rich oxide layer forms on the entire surface of these bulk samples and the act of machining the bulk metal into a defined shape may affect the morphology of the oxide layer on the outer edge of the samples during degradation. The mechanisms behind the surface evolution of these potential orthopedic implants are investigated in detail. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 185-193, 2015. PMID:24616416

Heiden, Michael; Walker, Emily; Nauman, Eric; Stanciu, Lia

2015-01-01

187

X-ray fluorescence analysis of iron and manganese distribution in primary dopaminergic neurons.  

PubMed

Transition metals have been suggested to play a pivotal role in the pathogenesis of Parkinson's disease. X-ray microscopy combined with a cryogenic setup is a powerful method for elemental imaging in low concentrations and high resolution in intact cells, eliminating the need for fixation and sectioning of the specimen. Here, we performed an elemental distribution analysis in cultured primary midbrain neurons with a step size in the order of 300 nm and ~ 0.1 ppm sensitivity under cryo conditions by using X-ray fluorescence microscopy. We report the elemental mappings on the subcellular level in primary mouse dopaminergic (DAergic) and non-DAergic neurons after treatment with transition metals. Application of Fe(2+) resulted in largely extracellular accumulation of iron without preference for the neuronal transmitter subtype. A quantification of different Fe oxidation states was performed using X-ray absorption near edge structure analysis. After treatment with Mn(2+) , a cytoplasmic/paranuclear localization of Mn was observed preferentially in DAergic neurons, while no prominent signal was detectable after Mn(3+) treatment. Immunocytochemical analysis correlated the preferential Mn uptake to increased expression of voltage-gated calcium channels in DAergic neurons. We discuss the implications of this differential elemental distribution for the selective vulnerability of DAergic neurons and Parkinson's disease pathogenesis. PMID:23106162

Du?i?, Tanja; Barski, Elisabeth; Salome, Murielle; Koch, Jan C; Bähr, Mathias; Lingor, Paul

2013-01-01

188

X-ray fluorescence analysis of iron and manganese distribution in primary dopaminergic neurons  

PubMed Central

Transition metals have been suggested to play a pivotal role in the pathogenesis of Parkinson's disease. X-ray microscopy combined with a cryogenic setup is a powerful method for elemental imaging in low concentrations and high resolution in intact cells, eliminating the need for fixation and sectioning of the specimen. Here, we performed an elemental distribution analysis in cultured primary midbrain neurons with a step size in the order of 300 nm and ? 0.1 ppm sensitivity under cryo conditions by using X-ray fluorescence microscopy. We report the elemental mappings on the subcellular level in primary mouse dopaminergic (DAergic) and non-DAergic neurons after treatment with transition metals. Application of Fe2+ resulted in largely extracellular accumulation of iron without preference for the neuronal transmitter subtype. A quantification of different Fe oxidation states was performed using X-ray absorption near edge structure analysis. After treatment with Mn2+, a cytoplasmic/paranuclear localization of Mn was observed preferentially in DAergic neurons, while no prominent signal was detectable after Mn3+ treatment. Immunocytochemical analysis correlated the preferential Mn uptake to increased expression of voltage-gated calcium channels in DAergic neurons. We discuss the implications of this differential elemental distribution for the selective vulnerability of DAergic neurons and Parkinson's disease pathogenesis. PMID:23106162

Ducic, Tanja; Barski, Elisabeth; Salome, Murielle; Koch, Jan C; Bahr, Mathias; Lingor, Paul

2013-01-01

189

Solid state 31phosphorus nuclear magnetic resonance of iron-, manganese-, and copper-containing synthetic hydroxyapatites.  

PubMed

The incorporation of micronutrients into synthetic hydroxyapatite (SHA) is proposed for slow release of these nutrients to crops in the National Aeronautics and Space Administration's (NASA's) Advanced Life Support (ALS) program for Lunar or Martian outposts. Solid state 31P nuclear magnetic resonance (NMR) was utilized to examine the paramagnetic effects of Fe3+, Mn2+, and Cu2+ to determine if they were incorporated into the SHA structure. Separate Fe3+, Mn2+, and Cu2+ containing SHA materials along with a transition metal free SHA (pure-SHA) were synthesized using a precipitation method. The proximity (<1 nm) of the transition metals to the 31P nuclei of SHA were apparent when comparing the integrated 31P signal intensities of the pure-SHA (87 arbitrary units g-1) with the Fe-, Mn-, and Cu-SHA materials (37-71 arbitrary units g-1). The lower integrated 31P signal intensities of the Fe-, Mn-, and Cu-SHA materials relative to the pure-SHA suggested that Fe3+, Mn2+, and Cu2+ were incorporated in the SHA structure. Further support for Fe3+, Mn2+, and Cu2+ incorporation was demonstrated by the reduced spin-lattice relaxation constants of the Fe-, Mn-, and Cu-SHA materials (T'=0.075-0.434s) relative to pure-SHA (T1=58.4s). Inversion recovery spectra indicated that Fe3+, Mn2+, and Cu2+ were not homogeneously distributed about the 31P nuclei in the SHA structure. Extraction with diethylene-triamine-penta-acetic acid (DTPA) suggested that between 50 and 80% of the total starting metal concentrations were incorporated in the SHA structure. Iron-, Mn-, and Cu-containing SHA are potential slow release sources of Fe, Mn, and Cu in the ALS cropping system. PMID:12088032

Sutter, B; Taylor, R E; Hossner, L R; Ming, D W

2002-01-01

190

Solid state 31phosphorus nuclear magnetic resonance of iron-, manganese-, and copper-containing synthetic hydroxyapatites  

NASA Technical Reports Server (NTRS)

The incorporation of micronutrients into synthetic hydroxyapatite (SHA) is proposed for slow release of these nutrients to crops in the National Aeronautics and Space Administration's (NASA's) Advanced Life Support (ALS) program for Lunar or Martian outposts. Solid state 31P nuclear magnetic resonance (NMR) was utilized to examine the paramagnetic effects of Fe3+, Mn2+, and Cu2+ to determine if they were incorporated into the SHA structure. Separate Fe3+, Mn2+, and Cu2+ containing SHA materials along with a transition metal free SHA (pure-SHA) were synthesized using a precipitation method. The proximity (<1 nm) of the transition metals to the 31P nuclei of SHA were apparent when comparing the integrated 31P signal intensities of the pure-SHA (87 arbitrary units g-1) with the Fe-, Mn-, and Cu-SHA materials (37-71 arbitrary units g-1). The lower integrated 31P signal intensities of the Fe-, Mn-, and Cu-SHA materials relative to the pure-SHA suggested that Fe3+, Mn2+, and Cu2+ were incorporated in the SHA structure. Further support for Fe3+, Mn2+, and Cu2+ incorporation was demonstrated by the reduced spin-lattice relaxation constants of the Fe-, Mn-, and Cu-SHA materials (T'=0.075-0.434s) relative to pure-SHA (T1=58.4s). Inversion recovery spectra indicated that Fe3+, Mn2+, and Cu2+ were not homogeneously distributed about the 31P nuclei in the SHA structure. Extraction with diethylene-triamine-penta-acetic acid (DTPA) suggested that between 50 and 80% of the total starting metal concentrations were incorporated in the SHA structure. Iron-, Mn-, and Cu-containing SHA are potential slow release sources of Fe, Mn, and Cu in the ALS cropping system.

Sutter, B.; Taylor, R. E.; Hossner, L. R.; Ming, D. W.

2002-01-01

191

Photoluminescence Properties of the Diluted Magnetic Semiconductors ZINC(1-X)MANGANESE(X)SELENIDE and CADMIUM(1 -  

NASA Astrophysics Data System (ADS)

Time-resolved and cw photoluminescence measurements were carried out on the diluted magnetic semiconductors Zn_{rm 1-x}Mn _{rm x}Se and Cd _{rm 1-x}Mn_ {rm x}Se; high manganese concentration was emphasized. Zn_{rm 1-x}Mn _{rm x}Se samples with 0 <= x <= 0.49 were investigated; four emission bands at ~2.15eV, ~2.03eV, ~1.95eV, and ~1.35 eV were observed. The bands of ~2.15 eV, ~2.03eV, and ~1.95eV were ascribed to Mn^ {2+} ^4T _1 to ^6 A_1 intraion transition, self-activated emission, and copper related emission, respectively. The temperature dependences and decay characteristics of these three bands were investigated for 18 < T < 136K. The ~2.15eV band decays monotonically, while the ~2.03 eV and ~1.95eV bands show a slow build up effect, the latter effect indicating the presence of energy transfer in the excitation of these two bands. Thermal quenching of the ~2.03 eV and ~1.95eV bands occur below 60K. An energy level scheme is suggested which takes into account mechanisms proposed for similar emissions in ZnSe. Time-resolved measurements on the ~2.13 eV and ~1.35eV photoluminescence bands in Cd_{rm 1-x}Mn _{rm x}Se were carried out for 18 < T < 300K and selected excitation energies 2.035eV < hnu_{rm ex} < 2.36eV. The ~2.13eV band is observable in an x = 0.48 sample; its decay is monotonic. For samples with x = 0.28 and x = 0.48, the ~1.35eV band exhibits complicated build up processes. A phenomenological model is presented which gives good agreement with data for the ~2.13 eV emission. The model ascribes the ~2.13 eV emission to the Mn^{2+} ^4T_1 to ^6A _1 transition, and assumes a two-level system and energy transfer between these levels. The excitation results on the ~1.35eV emisison suggest that the energy transfer from Mn ^4 T_1 excited states is an important source of excitation of this band for h nu_{rm ex} > 2.3eV, but two photon excitation of the ~2.13eV band or a similar mechanism is needed to explain the results of hnu_{ rm ex} < 2.3eV.

Wang, Bonnie I.-Keh

1987-09-01

192

The precipitation of aluminum, iron and manganese at the junction of Deer Creek with the Snake River in Summit County, Colorado  

USGS Publications Warehouse

The oxidation of disseminated pyrite in relatively acid schists and gneisses of the Snake River drainage basin provides abundant iron sulfate and sulfuric acid to ground and surface water. This acid water dissolves large quantities of many elements, particularly aluminum and surprisingly large quantities of elements, such as magnesium and zinc, not expected to be abundant in the drainage basin. The adjoining drainage to the west, Deer Creek, is underlain by basic rocks, from which the water inherits a high pH. Despite the presence of base- and precious- metal veins in the drainage basin of Deer Creek, it carries less metal than the Snake River. The principal precipitate on the bed of the Snake River is hydrated iron oxide with small quantities of the other metals. In Deer Creek manganese oxide is precipitated with iron oxide and large quantities of other metals are carried down with this precipitate. Below the junction of these streams the pH stabilizes at a near-neutral value. Iron is removed from the Snake River water at the junction, and aluminum is precipitated for some distance downstream. The aluminum precipitate carries down other metals in concentrations slightly less than that in the manganese precipitate on Deer Creek. The natural processes observed in this junction if carried to a larger scale could provide the mechanism described by Ansheles (1927) for the formation of bauxite. In the environment described, geochemical exploration by either water or stream sediment techniques is difficult because of (1) the extreme pH differential between the streams above their junction and (2) the difference in the precipitates formed on the streambeds. ?? 1963.

Theobald, P.K., Jr.; Lakin, H.W.; Hawkins, D.B.

1963-01-01

193

Assessment of cadmium and iron adsorption in sediment, employing a flow injection analysis system with on line filtration and detection by flame atomic absorption spectrometry and thermospray flame furnace atomic absorption spectrometry.  

PubMed

This work presents an evaluation of iron and cadmium adsorption in sediment of the Furnas Hydroelectric Plant Reservatory located in Alfenas, Minas Gerais (Brazil). The metal determination was done employing a flow injection analysis (FIA) with an on-line filtering system. As detection techniques, flame atomic absorption spectrometry (FAAS) for iron and thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for cadmium determinations were used. The developed methodology presented good limits of detection, being 190 ?g L(-1) for iron and 1.36 ?g L(-1) for cadmium, and high sampling frequency for both metals 144 and 60 readings h(-1) for iron and cadmium, respectively. Both metals obey the Langmuir model, with maximum adsorptive capacity of 0?169 mg g(-1) for iron and 7?991 mg g(-1) for cadmium. For iron, a pseudo-first-order kinetic model was obtained with a theoretical Q(e)=9?8355 mg g(-1) (experimental Q(e)=9?5432 mg g(-1)), while for cadmium, a pseudo-second-order kinetic model was obtained, with a theoretical Q(e)=0.3123 mg g(-1) (experimental Q(e)=0?3052 mg g(-1)). PMID:24418136

de Oliveira, Fagner Moreira; Marchioni, Camila; Barros, Juan A V de A; do Lago, Ayla Campos; Wisniewski, Célio; Luccas, Pedro Orival

2014-01-27

194

Effect of chronic ethanol ingestion on the metabolism of copper, iron, manganese, selenium, and zinc in an animal model of alcoholic cardiomyopathy  

SciTech Connect

Alcoholic cardiomyopathy (AC) is one of the diseases caused by alcohol abuse, and there has been considerable debate about the possibility that nutritional factors may be important in the etiology of AC. In addition, there is evidence that ethanol may affect the metabolism of trace elements. The purpose of this investigation was to determine if chronic ethanol administration produces changes in the metabolism of the essential metals copper, iron, manganese, zinc, and selenium using an animal model of AC. Eighteen male Sprague-Dawley rats were divided into three groups; an ad libitum control group (AL), a pair-fed control group (PF), and an ethanol-dosed group (ETOH). The latter group received gradually increasing concentrations (5-25%) of ethanol in the drinking water for 15 wk. Food intake was monitored and urine and feces collected for a 4-d period during the study to determine ethanol effects on trace-element balance. Growth of both the PF and ETOH animals was inhibited. Ethanol produced substantial increases in liver manganese and decreases in liver copper and zinc. Metal concentrations in heart and concentrations in other tissues studied (spleen, testes, brain, bone, kidney, and muscle) did not differ significantly among the groups, except for testes selenium and kidney zinc. Reduced food intake and ethanol ingestion were associated with a reduced percentage of ingested selenium excreted in the urine. Deficiencies of copper, iron, manganese, selenium, and zinc in myocardial tissue are not likely to be involved in the pathogenesis of AC in the rat. 38 references, 1 figure, 4 tables.

Bogden, J.D.; Al-Rabiai, S.; Gilani, S.H.

1984-01-01

195

Comparison of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in feathers in bald eagle (Haliaeetus leucocephalus), and comparison with common eider (Somateria mollissima), glaucous-winged gull (Larus glaucescens), pigeon guillemot (Cepphus columba), and tufted puffin (Fratercula cirrhata) from the Aleutian Chain of Alaska.  

PubMed

There is an abundance of field data for levels of metals from a range of places, but relatively few from the North Pacific Ocean and Bering Sea. In this paper we examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in feathers from common eiders (Somateria mollissima), glaucous-winged gulls (Larus glaucescens), pigeon guillemots (Cepphus columba), tufted puffins (Fratercula cirrhata) and bald eagles (Haliaeetus leucocephalus) from the Aleutian Chain of Alaska. Our primary objective was to test the hypothesis that there are no trophic levels relationships for arsenic, cadmium, chromium, lead, manganese, mercury and selenium among these five species of birds breeding in the marine environment of the Aleutians. There were significant interspecific differences in all metal levels. As predicted bald eagles had the highest levels of arsenic, chromium, lead, and manganese, but puffins had the highest levels of selenium, and pigeon guillemot had higher levels of mercury than eagles (although the differences were not significant). Common eiders, at the lowest trophic level had the lowest levels of some metals (chromium, mercury and selenium). However, eiders had higher levels than all other species (except eagles) for arsenic, cadmium, lead, and manganese. Levels of lead were higher in breast than in wing feathers of bald eagles. Except for lead, there were no significant differences in metal levels in feathers of bald eagles nesting on Adak and Amchitka Island; lead was higher on Adak than Amchitka. Eagle chicks tended to have lower levels of manganese than older eagles. PMID:18521716

Burger, Joanna; Gochfeld, Michael

2009-05-01

196

Expression profiling reveals functionally redundant multiple-copy genes related to zinc, iron and cadmium responses in Brassica rapa.  

PubMed

Genes underlying environmental adaptability tend to be over-retained in polyploid plant species. Zinc deficiency (ZnD) and iron deficiency (FeD), excess Zn (ZnE) and cadmium exposure (CdE) are major environmental problems for crop cultivation, but little is known about the differential expression of duplicated genes upon these stress conditions. Applying Tag-Seq technology to leaves of Brassica rapa grown under FeD, ZnD, ZnE or CdE conditions, with normal conditions as a control, we examined global gene expression changes and compared the expression patterns of multiple paralogs. We identified 812, 543, 331 and 447 differentially expressed genes under FeD, ZnD, ZnE and CdE conditions, respectively, in B. rapa leaves. Genes involved in regulatory networks centered on the transcription factors bHLH038 or bHLH100 were differentially expressed under (ZnE-induced) FeD. Further analysis revealed that genes associated with Zn, Fe and Cd responses tended to be over-retained in the B. rapa genome. Most of these multiple-copy genes showed the same direction of expression change under stress conditions. We conclude that the duplicated genes involved in trace element responses in B. rapa are functionally redundant, making the regulatory network more complex in B. rapa than in Arabidopsis thaliana. PMID:24738937

Li, Jimeng; Liu, Bo; Cheng, Feng; Wang, Xiaowu; Aarts, Mark G M; Wu, Jian

2014-07-01

197

Occupational Exposure to Welding Fume among Welders: Alterations of Manganese, Iron, Zinc, Copper, and Lead in Body Fluids and the Oxidative Stress Status  

PubMed Central

Welders in this study were selected from a vehicle manufacturer; control subjects were from a nearby food factory. Airborne manganese levels in the breathing zones of welders and controls were 1.45 ± SD1.08 mg/m3 and 0.11 ± 0.07 ?g/m3, respectively. Serum levels of manganese and iron in welders were 4.3-fold and 1.9-fold, respectively, higher than those of controls. Blood lead concentrations in welders increased 2.5-fold, whereas serum zinc levels decreased 1.2-fold, in comparison with controls. Linear regression revealed the lack of associations between blood levels of five metals and welder’s age. Furthermore, welders had erythrocytic superoxide dismutase activity and serum malondialdehyde levels 24% less and 78% higher, respectively, than those of controls. These findings suggest that occupational exposure to welding fumes among welders disturbs the homeostasis of trace elements in systemic circulation and induces oxidative stress. PMID:15091287

Li, Guojun Jane; Zhang, Long-Lian; Lu, Ling; Wu, Ping; Zheng, Wei

2014-01-01

198

Catalytic oxidation of NO with O2 over FeMnOx/TiO2: Effect of iron and manganese oxides loading sequences and the catalytic mechanism study  

NASA Astrophysics Data System (ADS)

FeMnOx/TiO2 with different iron and manganese oxides adding orders were prepared through isovolumetric impregnation and tested for catalytic oxidation of NO with O2. It was found that the sample obtained from one-step impregnation method had better catalytic activity. The excellent activity was attributed to higher surface area, lower crystalline of manganese oxides, abundant Mn3+, Fe3+ and chemisorbed oxygen species on the surface. Furthermore, effects of loading sequences on FeMnOx/TiO2 catalysts were investigated. The study showed that Fe and Mn would affect each other and change the surface physicochemical properties of FeMnOx/TiO2 when they were loaded step-by-step. In addition, the inhibiting effect of H2O on catalytic activity was reversible while the conversion of NO recovered to 40% when SO2 was cut off. XPS analysis between used and fresh catalysts revealed the electron transfer between Fen+ and Mnn+ ions in FeMnOx/TiO2. Possible reaction mechanism was put forward by comprehensive analysis of XPS and FT-IR results.

Zhang, Mengying; Li, Caiting; Qu, Long; Fu, Mengfan; Zeng, Guangming; Fan, Chunzhen; Ma, Jinfeng; Zhan, Fuman

2014-05-01

199

Pseudomonas aeruginosa sodA and sodB mutants defective in manganese- and iron-cofactored superoxide dismutase activity demonstrate the importance of the iron-cofactored form in aerobic metabolism.  

PubMed Central

The consumption of molecular oxygen by Pseudomonas aeruginosa can lead to the production of reduced oxygen species, including superoxide, hydrogen peroxide, and the hydroxyl radical. As a first line of defense against potentially toxic levels of endogenous superoxide, P. aeruginosa possesses an iron- and manganese-cofactored superoxide dismutase (SOD) to limit the damage evoked by this radical. In this study, we have generated mutants which possess an interrupted sodA (encoding manganese SOD) or sodB (encoding iron SOD) gene and a sodA sodB double mutant. Mutagenesis of sodA did not significantly alter the aerobic growth rate in rich medium (Luria broth) or in glucose minimal medium in comparison with that of wild-type bacteria. In addition, total SOD activity in the sodA mutant was decreased only 15% relative to that of wild-type bacteria. In contrast, sodB mutants grew much more slowly than the sodA mutant or wild-type bacteria in both media, and sodB mutants possessed only 13% of the SOD activity of wild-type bacteria. There was also a progressive decrease in catalase activity in each of the mutants, with the sodA sodB double mutant possessing only 40% of the activity of wild-type bacteria. The sodA sodB double mutant grew very slowly in rich medium and required approximately 48 h to attain saturated growth in minimal medium. There was no difference in growth of either strain under anaerobic conditions. Accordingly, the sodB but not the sodA mutant demonstrated marked sensitivity to paraquat, a superoxide-generating agent. P. aeuroginosa synthesizes a blue, superoxide-generating antibiotic similar to paraquat in redox properties which is called pyocyanin, the synthesis of which is accompanied by increased iron SOD and catalase activities (D.J. Hassett, L. Charniga, K. A. Bean, D. E. Ohman, and M. S. Cohen, Infect. Immun. 60:328-336, 1992). Pyocyanin production was completely abolished in the sodB and sodA sodB mutants and was decreased approximately 57% in sodA mutants relative to that of the wild-type organism. Furthermore, the addition of sublethal concentrations of paraquat to wild-type bacteria caused a concentration-dependent decrease in pyocyanin production, suggesting that part of the pyocyanin biosynthetic cascade is inhibited by superoxide. These results suggest that iron SOD is more important than manganese SOD for aerobic growth, resistance to paraquat, and optimal pyocyanin biosynthesis in P. aeruginosa. PMID:7592406

Hassett, D J; Schweizer, H P; Ohman, D E

1995-01-01

200

Investigation of the influence of cadmium processing on zinc gallium oxide:manganese thin films for photoluminescent and thin film electroluminescent applications  

Microsoft Academic Search

Cadmium processing of ZnGa2O4 films provides a new fabrication route for phosphor powders and thin films. It relies on the enhanced diffusion due to the large vacancy concentration left by the sublimation of cadmium. Photoluminescent powders can be made with a single high temperature firing. Thin film devices can be processed at a significantly lower temperature, expanding the range of

Michael John Flynn

2003-01-01

201

The Structure and Properties of Plasma Sprayed Iron Oxide Doped Manganese Cobalt Oxide Spinel Coatings for SOFC Metallic Interconnectors  

Microsoft Academic Search

Manganese cobalt oxide spinel doped with Fe2O3 was studied as a protective coating on ferritic stainless steel interconnects. Chromium alloying causes problems at high\\u000a operation temperatures in such oxidizing conditions where chromium compounds evaporate and poison the cathode active area,\\u000a causing the degradation of the solid oxide fuel cell. In order to prevent chromium evaporation, these interconnectors need\\u000a a protective

Jouni Puranen; Juha Lagerbom; Leo Hyvärinen; Mikko Kylmälahti; Olli Himanen; Mikko Pihlatie; Jari Kiviaho; Petri Vuoristo

2011-01-01

202

Manganese recycling in the United States in 1998  

USGS Publications Warehouse

This report describes the flow and processing of manganese within the U.S. economy in 1998 with emphasis on the extent to which manganese is recycled. Manganese was used mostly as an alloying agent in alloys in which it was a minor component. Manganese was recycled mostly within scrap of iron and steel. A small amount was recycled within aluminum used beverage cans. Very little manganese was recycled from materials being recovered specifically for their manganese content. For the United States in 1998, 218,000 metric tons of manganese was estimated to have been recycled from old scrap, of which 96% was from iron and steel scrap. Efficiency of recycling was estimated as 53% and recycling rate as 37%. Metallurgical loss of manganese was estimated to be about 1.7 times that recycled. This loss was mostly into slags from iron and steel production, from which recovery of manganese has yet to be shown economically feasible.

Jones, Thomas S.

2001-01-01

203

Determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys by atomic-absorption spectrophotometry.  

PubMed

A simple atomic-absorption spectrophotometry method is described for the determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys, with use of a single sample solution. The sample is dissolved in a mixture of hydrobromic acid and bromine, then fumed with sulphuric acid. The lead sulphate is dissolved in concentrated hydrochloric acid. The method is particularly suitable for the determination of silver and bismuth, which are co-precipitated with lead sulphate. The other elements can also be determined after removal of the lead sulphate by filtration. PMID:18964038

Chong, C

1986-01-01

204

Comparison of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in feathers in bald eagle ( Haliaeetus leucocephalus ), and comparison with common eider ( Somateria mollissima ), glaucous-winged gull (Larus glaucescens), pigeon guillemot ( Cepphus columba ), and tufted puffin ( Fratercula cirrhata ) from the Aleutian Chain of Alaska  

Microsoft Academic Search

There is an abundance of field data for levels of metals from a range of places, but relatively few from the North Pacific\\u000a Ocean and Bering Sea. In this paper we examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium\\u000a in feathers from common eiders (Somateria mollissima), glaucous-winged gulls (Larus glaucescens), pigeon guillemots (Cepphus columba), tufted puffins

Joanna Burger; Michael Gochfeld

2009-01-01

205

Detection of copper, lead, cadmium and iron in wine using electronic tongue sensor system.  

PubMed

An array of 10 potentiometric chemical sensors has been applied to the detection of total Fe, Cu, Pb and Cd content in digested wine. As digestion of organic matter of wine is necessary prior to the trace metal detection using potentiometric sensors, sample preparation procedures have been optimized. Different variants of wet and microwave digestion and dry ashing, 14 conditions in total, have been tested. Decomposition of organic matter was assessed using Fourier transform mid-infrared spectroscopy and total phenolic content. Dry ashing was found to be the most effective method of wine digestion. Measurements with sensors in individual solutions of Fe(III), Cu(II), Pb(II) and Cd(II) prepared on different backgrounds have shown that their detection limits were below typical concentration levels of these metals in wines and, in the case of Cu, Pb and Cd below maximum allowed concentrations. Detection of Fe in digested wine samples was possible using discrete iron-sensitive sensors with chalcogenide glass membranes with RMSEP of 0.05 mmol L(-1) in the concentration range from 0.0786 to 0.472 mmol L(-1). Low concentration levels of Cu, Pb and Cd in wine and cross-sensitivity of respective sensors resulted in the non-linearity of their responses, requiring back-propagation neural network for the calibration. Calibration models have been calculated using measurements in the model mixed solutions containing all three metals and a set of digested wine sample. RMSEP values for Cu, Pb and Cd were 3.9, 39 and 1.2 ?mol L(-1) in model solutions and 2, 150 and 1 ?mol L(-1) in digested wine samples. PMID:25127565

Simões da Costa, A M; Delgadillo, I; Rudnitskaya, A

2014-11-01

206

Cadmium interacts with the transport of essential micronutrients in the mammary gland - a study in rural Bangladeshi women.  

PubMed

Although the concentrations of the toxic metal cadmium in breast milk are generally low (< 1 microg/L), experimental studies indicated neurobehavioral and endocrine effects in the suckling offspring. The aim of the present study was to elucidate how cadmium is transported to breast milk by assessing interactions with essential micronutrients. The study is nested into a food and micronutrient supplementation trial conducted among pregnant women in Matlab, a rural area in Bangladesh, where malnutrition is prevalent and the cadmium exposure is relatively high. We measured cadmium in breast milk (BM-Cd; median 0.14 microg/kg; range <0.050-1.0 microg/kg), in erythrocytes (Ery-Cd; median 1.5 microg/kg; range 0.46-4.8 microg/kg) and in urine (U-Cd; median 0.63 microg/L; range 0.050-4.5 microg/L), using inductively coupled plasma mass spectrometry (ICPMS). We found a significant positive association between Ery-Cd and BM-Cd and a breast milk-plasma ratio of approximately 3-4, indicating no barrier against cadmium transport from plasma to breast milk. BM-Cd was positively associated with manganese (r(s)=0.56; p<0.01) and iron (r(s)=0.55; p<0.01) in breast milk, but not with plasma ferritin. On the other hand, BM-Cd was negatively associated with BM-Ca (r(s)=-0.17; p=0.05), indicating that cadmium inhibits the transport of calcium to breast milk. In conclusion, the present study may indicate that cadmium shares common transporters with iron and manganese for transfer to breast milk, but inhibits secretion of calcium to breast milk. PMID:19126424

Kippler, Maria; Lönnerdal, Bo; Goessler, Walter; Ekström, Eva-Charlotte; Arifeen, Shams El; Vahter, Marie

2009-03-01

207

Iron  

MedlinePLUS

... shows that giving iron intravenously can improve some symptoms of heart failure. It is not yet known if taking an iron supplement by mouth would help.Attention deficit-hyperactivity disorder (ADHD). Developing research shows that taking iron sulfate ( ...

208

The Structure and Properties of Plasma Sprayed Iron Oxide Doped Manganese Cobalt Oxide Spinel Coatings for SOFC Metallic Interconnectors  

NASA Astrophysics Data System (ADS)

Manganese cobalt oxide spinel doped with Fe2O3 was studied as a protective coating on ferritic stainless steel interconnects. Chromium alloying causes problems at high operation temperatures in such oxidizing conditions where chromium compounds evaporate and poison the cathode active area, causing the degradation of the solid oxide fuel cell. In order to prevent chromium evaporation, these interconnectors need a protective coating to block the chromium evaporation and to maintain an adequate electrical conductivity. Thermal spraying is regarded as a promising way to produce dense and protective layers. In the present work, the ceramic Mn-Co-Fe oxide spinel coatings were produced by using the atmospheric plasma spray process. Coatings with low thickness and low amount of porosity were produced by optimizing deposition conditions. The original spinel structure decomposed because of the fast transformation of solid-liquid-solid states but was partially restored by using post-annealing treatment.

Puranen, Jouni; Lagerbom, Juha; Hyvärinen, Leo; Kylmälahti, Mikko; Himanen, Olli; Pihlatie, Mikko; Kiviaho, Jari; Vuoristo, Petri

2011-01-01

209

X-Ray Microanalytic Concentration Measurements in Unsectioned Specimens: a Technique and its Application to Zinc, Manganese, and Iron Enriched Mechanical Structures of Organisms from Three Phyla  

NASA Astrophysics Data System (ADS)

A method for measuring concentrations of minor elements in microscopic volumes of heterogeneous, unsectioned biological specimens using an ion microprobe is developed. The element quantity is obtained from PIXE (Proton Induced X-ray Emission) and the total quantity of material is derived from STIM (Scanning Transmission Ion Microscopy) energy loss measurements. Sources of error, including changes in x-ray production cross section with proton energy and absorption of induced x-rays, are discussed and a method of calculating the total measurement uncertainty, typically about 25% here, is developed. The measurement accuracy is shown to be improved for symmetric specimens, and a method of using the bremsstrahlung background to correct for x-ray attenuation within irregular specimens is developed. Methods for measuring local concentrations in internal features are also discussed. With this technique, scorpions were found to contain cuticular accumulations of one or more heavy metals (manganese up to 5% of dry weight, iron up to 8%, zinc up to 24%) in the chelicera, pedipalp denticles, tarsal claws, and stingers; different region soften contained different metals. The stingers are argued to be of particular interest because they are not homologous to legs. Similar accumulations were found in spiders, some other chelicerates and crustaceans. Previous reports of manganese and zinc accumulations in insect and worm mouth parts were augmented with local concentration measurements and with the detection of other enrichment features (such as 6% iron in the paragnaths of the worm Nereis vexillosa). Zinc accumulations (up to only 0.1%) were also found in the tips of the teeth of a hagfish, Myxine + glutinosa. X-ray images of several of these features are presented. It is argued that the extreme magnitude of some concentration values suggests that some metals are incorporated in unusual biominerals rather than organically bound. Results of x-ray diffractometry and Vickers microhardness measurements are reported although the results are inconclusive. The atomic ratio of zinc to chlorine in these accumulations is shown not to be constant. It is suggested from their typical locations that at least two of the observed accumulation patterns impart different mechanical properties to the cuticle.

Schofield, Robert M. S.

210

Release of aluminum, arsenic, cadmium, chromium, copper, iron, lead, and zinc in a coal leachate, and their removal from solution undergoing neutralization  

SciTech Connect

Whole coal contains significant amounts of iron pyrite which is oxidized ultimately to ferric acid sulfate. As a result, trace elements are released from the coal and other minerals in potentially hazardous concentrations. The purpose of this research was to: (1) study the release and mobility of selected trace elements during the weathering of coal; (2) seek to understand factors controlling solubility of trace elements in a synthetic, acidic leachate undergoing gradual neutralization; and (3) develop a chemical thermodynamic computer model to predict the effects of dilution and neutralization of leachate on trace element mobility and speciation. Samples collected periodically from a slurry of whole ground coal in water were filtered and analyzed for dissolved sulfate (by ion chromatography), iron (by flame atomic absorption spectrophotometry), and Al, Zn, Cd, Cu, Cr, Pb, As, and Se (by graphite furnace AAS). Iron, copper, and probably arsenic tracked the production of sulfate, while aluminum, zinc, chromium, and cadmium concentrations were stable or rose slightly. A synthetic leachate of ferric sulfate and sulfuric acid was doped with trace levels of Al, Zn, Cu, Cd, Cr, Pb, As, and Se. Slow injection of sodium bicarbonate solution neutralized the stirred system, though hydrolysis of iron buffered the pH and 2.5.

Tatum, T.L.

1992-01-01

211

Ferromagnets based on diamond-like semiconductors GaSb, InSb, Ge, and Si supersaturated with manganese or iron impurities during laser-plasma deposition  

SciTech Connect

Properties of thin (30-100 nm) layers of diluted magnetic semiconductors based on diamond-like compounds III-V (InSb and GaSb) and elemental semiconductors Ge and Si doped with 3d impurities of manganese and iron up to 15% were measured and discussed. The layers were grown by laser-plasma deposition onto heated single-crystal gallium arsenide or sapphire substrates. The ferromagnetism of layers with the Curie temperature up to 500 K appeared in observations of the ferromagnetic resonance, anomalous Hall effect, and magneto-optic Kerr effect. The carrier mobility of diluted magnetic semiconductors is a hundred times larger than that of the previously known highest temperature magnetic semiconductors, i.e., copper and chromium chalcogenides. The difference between changes in the magnetization with temperature in diluted semiconductors based on III-V, Ge, and Si was discussed. A complex structure of the ferromagnetic resonance spectrum in Si:Mn/GaAs was observed. The results of magnetic-force microscopy showed a weak correlation between the surface relief and magnetic inhomogeneity, which suggests that the ferromagnetism is caused by the 3d-impurity solid solution, rather than ferromagnetic phase inclusions.

Demidov, E. S. [Lobachevsky State University (Russian Federation)], E-mail: demidov@phys.unn.ru; Podol'skii, V. V.; Lesnikov, V. P. [Lobachevsky State University, Research Physicotechnical Institute (Russian Federation); Sapozhnikov, M. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Druzhnov, D. M.; Gusev, S. N. [Lobachevsky State University (Russian Federation); Gribkov, B. A. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Filatov, D. O.; Stepanova, Yu. S.; Levchuk, S. A. [Lobachevsky State University (Russian Federation)

2008-01-15

212

Mineral of the month: manganese  

USGS Publications Warehouse

Manganese is one of the most important ferrous metals and one of the few for which the United States is totally dependent on imports. It is a black, brittle element predominantly used in metallurgical applications as an alloying addition, particularly in steel and cast iron production, which together provide the largest market for manganese (about 83 percent). It is also used as an alloy with nonferrous metals such as aluminum and copper. Nonmetallurgical applications of manganese include battery cathodes, soft ferrite magnets used in electronics, micronutrients found in fertilizers and animal feed, water treatment chemicals, and a colorant for bricks and ceramics.

Corathers, Lisa

2005-01-01

213

Progressive Sorption and Oxidation\\/Hydrolysis of Fe(II) Affects Cadmium Immobilization by Bacteria-Iron Oxide Composites  

Microsoft Academic Search

Iron-bacteria composite suspensions were prepared by exposure of Anoxybacillus flavithermus cells to increasing concentrations of Fe cations under different degrees of oxidation. Cd immobilization was investigated during and after the synthesis of the iron-bacteria composites via scanning electron microscopy and isotherm sorption experiments conducted at varied ratios of total iron to bacteria (expressed by the variable ?, mg Fe per

Christopher J. Daughney; Mohamad Fakih; Xavier Châtellier

2011-01-01

214

Influence of diagenetic processes in Thau lagoon on cadmium behavior and benthic fluxes  

NASA Astrophysics Data System (ADS)

DGT (Diffusive Gradient in Thin-films) and DET (Diffusive Equilibration in Thin-films) combined probes were used in Thau lagoon sediments to describe variations of dissolved concentrations of metals such as cadmium, manganese and iron, through the sediment-water interface. Two contrasted stations regarding organic carbon fluxes were studied from December 2001 to May 2003 during four field campaigns: station C4 in the middle of the lagoon, and station C5 in a shellfish-farming zone. Laboratory experiments and field deployments in such environment showed that DGT sampled pore water labile cadmium whereas iron and manganese concentrations were underestimated. These results suggest that no steady state in the flux of metals onto the gel was established for Fe and Mn. Kinetics of metal sulfide dissolution-precipitation may control metal fluxes onto the gel probe in marine sedimentary environments. Analysis of sediment and water column samples showed cadmium concentrations above natural background (3.3 and 7.6 nmol kg -1 for station C4 and station C5 sediments, respectively; between 40 and 800 pmol L -1 for the water column), suggesting contamination. Spatial and temporal patterns of cadmium behavior were observed. The sediment at station C4 was generally a source of cadmium whereas at station C5 it was a sink. The vertical extension of the diagenetic series was more important at station C4 with deeper oxygen penetration and lack of dissolved sulfide whereas station C5 showed steep ?H 2S gradients at the same depths. The data suggested that cadmium source was more likely organic matter. Cadmium mobility was probably controlled by aerobic mineralization at station C4 and by dissolution-precipitation of sulfides at station C5. Seasonal variations were observed in the depth of oxygen penetration and sulfide diffusion generating important remobilization of cadmium during December 2001. Conversely in May 2003 at station C5, bottom water suboxic conditions (i.e. %O 2 = 60) enhanced reductive conditions in the sediment favoring uptake of cadmium by the sediment from the water column.

Metzger, E.; Simonucci, C.; Viollier, E.; Sarazin, G.; Prévot, F.; Elbaz-Poulichet, F.; Seidel, J.-L.; Jézéquel, D.

2007-04-01

215

Iron  

MedlinePLUS

... several factors [ 1 , 3 , 8 , 11-15 ]. Storage levels of iron have the greatest influence on iron ... RDA), Adequate Intakes (AI), and Tolerable Upper Intake Levels (UL). The RDA recommends the average daily intake ...

216

The resistance to embrittlement by a hydrogen environment of selected high strength iron-manganese base alloys  

NASA Technical Reports Server (NTRS)

Fe-16Mn and Fe-25Mn base alloys, which had been cold worked to yield strength levels of 201 and 178 KSI, were resistant to degradation of mechanical properties in a one atmosphere hydrogen environment at ambient temperature under the loading conditions employed in this investigation. Transmission electron microscopy established that bands of epsilon phase martensite and fcc mechanical twins were formed throughout the fcc matrix when these alloys were cold worked. In the cold worked alloys a high density of crystal defects were observed associated with both types of strain induced structures, which should contribute significantly to the strengthening of these alloys. High strength iron base alloys can be produced which appear to have some resistance to degradation of mechanical properties in a hydrogen environment under certain conditions.

Benson, R. B., Jr.; Kim, D. K.; Atteridge, D.; Gerberich, W. W.

1974-01-01

217

Co-Overexpression FIT with AtbHLH38 or AtbHLH39 in Arabidopsis-Enhanced Cadmium Tolerance via Increased Cadmium Sequestration in Roots and Improved Iron Homeostasis of Shoots1[W  

PubMed Central

Cadmium (Cd) is toxic to plant cells. Under Cd exposure, the plant displayed leaf chlorosis, which is a typical symptom of iron (Fe) deficiency. Interactions of Cd with Fe have been reported. However, the molecular mechanisms of Cd-Fe interactions are not well understood. Here, we showed that FER-like Deficiency Induced Transcripition Factor (FIT), AtbHLH38, and AtbHLH39, three basic helix-loop-helix transcription factors involved in Fe homeostasis in plants, also play important roles in Cd tolerance. The gene expression analysis showed that the expression of FIT, AtbHLH38, and AtbHLH39 was up-regulated in the roots of plants treated with Cd. The plants overexpressing AtbHLH39 and double-overexpressing FIT/AtbHLH38 and FIT/AtbHLH39 exhibited more tolerance to Cd exposure than wild type, whereas no Cd tolerance was observed in plants overexpressing either AtbHLH38 or FIT. Further analysis revealed that co-overexpression of FIT with AtbHLH38 or AtbHLH39 constitutively activated the expression of Heavy Metal Associated3 (HMA3), Metal Tolerance Protein3 (MTP3), Iron Regulated Transporter2 (IRT2), and Iron Regulated Gene2 (IREG2), which are involved in the heavy metal detoxification in Arabidopsis (Arabidopis thaliana). Moreover, co-overexpression of FIT with AtbHLH38 or AtbHLH39 also enhanced the expression of NICOTIANAMINE SYNTHETASE1 (NAS1) and NAS2, resulting in the accumulation of nicotiananamine, a crucial chelator for Fe transportation and homeostasis. Finally, we showed that maintaining high Fe content in shoots under Cd exposure could alleviate the Cd toxicity. Our results provide new insight to understand the molecular mechanisms of Cd tolerance in plants. PMID:22184655

Wu, Huilan; Chen, Chunlin; Du, Juan; Liu, Hongfei; Cui, Yan; Zhang, Yue; He, Yujing; Wang, Yiqing; Chu, Chengcai; Feng, Zongyun; Li, Junming; Ling, Hong-Qing

2012-01-01

218

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

SciTech Connect

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.

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

219

A Holocene record of endogenic iron and manganese precipitation and vegetation history in a lake-fen complex in northwestern Minnesota  

USGS Publications Warehouse

Little Shingobee Lake and Fen are part of the extensive network of lakes and wetlands in the Shingobee River headwaters of northwestern Minnesota, designed to study the interactions between surface and ground waters. Prior to about 11. 2 cal. ka, most of these lakes and wetlands were interconnected to form glacial Lake Willobee, which apparently formed when a debris flow dammed the Shingobee River. Between 11. 2 and 8. 5 cal. ka, the level of Lake Willobee fell as a result of breaching of the dam, transforming the deep lake into the existing lakes and wetlands. Analyses of a 9-m core from Little Shingobee Lake (LSL-B), and lacustrine sediments under 3. 3 m of peat in a 17-m core from Little Shingobee Fen (LSF-10), show that the dominant components are allogenic clastic material, and endogenic CaCO3 and organic matter. In both cores almost all of the iron (Fe) and manganese (Mn) are incorporated in endogenic minerals, presumed to be X-ray amorphous oxyhydroxide minerals, that occur in significant quantities throughout the cores; almost no Fe and Mn are contributed from detrital aluminosilicate minerals. This suggests that, for most of the Holocene, the allogenic watershed contributions to lake chemistry were minor compared to the dissolved mineral load. In addition, prior to 3. 5 cal. ka, pollen zone boundaries coincide with large changes in lake-sediment mineralogy, indicating that both landscape and climate processes were linked to early- and mid-Holocene lake chemistry. The pollen time series, with sequential domination by spruce, pine, sagebrush-oak, birch-oak and, finally, white pine is typical of the region and reflects the changing location of the prairie-forest transition zone over time. These changes in vegetation had some profound effects on the geochemistry of the lake waters. ?? 2011 Springer Science+Business Media B.V. (outside the USA).

Dean, W.E.; Doner, L.A.

2012-01-01

220

Influence of manganese incorporation on structure, surface and As(III)/As(V) removal capacity of iron oxy-hydroxides  

NASA Astrophysics Data System (ADS)

Iron oxy-hydroxides are well defined As(V) adsorbents dominating in water treatment market. The main drawback of these adsorbents, as well as of all commercial one, is their significantly low adsorption capacity for As(III). A breakthrough for improving As(III) adsorption of iron oxy-hydroxides may come by the MnO2incorporation. However, MnO2 decreases the total arsenic capacity proportionally to its percentage since its efficiency for As(V) is much lower than that of an iron oxy-hydroxide. It is concluded that an ideal adsorbent capable for high and simultaneous As(III) and As(V) removal should be consisted of a binary Fe(III)-Mn(IV) oxy-hydroxide both efficient for As(III) oxidation, due to Mn(IV) presence, and capture of As(V) due to a high positively surface charge density. This work studies the optimum parameters at the synthesis of single Fe and binary Fe/Mn oxy-hydroxides in a continuous flow kilogram-scale production reactor through the precipitation of FeSO4 in the pH range 3-12, under intense oxidative conditions using H2O2/KMnO4, that maximize arsenic adsorption. The evaluation of their efficiency was based on its As(III) and As(V) adsorption capacity (Q10-index) at equilibrium concentration equal to drinking water regulation limit (Ce= 10 ?g/L) in NSF challenge water. The pH of synthesis was found to decisively affect, the structure, surface configuration and Q10-index. As a result, both single Fe and binary Fe/Mn oxy-hydroxides prepared at pH 4, which consist of schwertmannite and Mn(IV)-feroxyhyte respectively, were qualified according to their highest Q10-index of 13±0.5 ?g As(V)/ mg for a residual arsenic concentration of 10 ?g/L at an equilibrium pH 7. The high surface charge and the activation of an ion-exchange mechanism between SO42- adsorbed in the Stern layer and arsenate ions were found to significantly contribute to the increased adsorption capacity. The Q10-index for As(III) of Fe/Mn adsorbent at equilibrium pH 7 was 6.7 ?g/mg, which is 3.5 times greater of that for single Fe one (1.9 ?g/mg), although it is significantly lower of the respective for As(V). However, Fe/Mn oxy-hydroxide present almost equal adsorption capacity for both arsenic species in the pH range 7.5-8. The As(III) adsorption capacity of Fe/Mn oxy-hydroxides is positively affected by the Mn content and the redox potential values at equilibrium pH 6-7. The corresponding Q10-index values observed in rapid scale column tests were in agreement with those of batch experiments, illustrating the improved efficiency of the qualified adsorbent compared to the common commercial arsenic adsorbents. Acknowledgement This work was supported by the European Commission FP7/Research for SMEs "AquAsZero", Project No: 232241.

Tresintsi, Sofia; Simeonidis, Konstantinos; Mitrakas, Manassis

2013-04-01

221

The origin of manganese-rich metasediments and their relationship to iron formation and base metal deposits, western Georgia piedmont  

SciTech Connect

Manganiferous metasediments (coticules), banded iron-formation, and tourmaline-quartz rocks (tourmalinites) are found in close spatial association to each other and to volcanogenic base metal sulfide and gold deposits in the Northern Piedmont of western Georgia. Coticules, which consist of up to 90% garnet and contain from 1 to 15 weight % MnO and 14 to 37 % Fe/sub 2/O/sub 3/, are often hosted by metabasalt. Tourmalinites occur as poorly-bedded aggregates or disseminations and are also found locally associated with metabasalt. Trace element analyses of coticules yield conflicting results. Cu + Co + Ni values and Zr/Cr ratios are low and indicate a hydrothermal origin. Alumina concentrations, Y/P/sub 2/O/sub 5/% ratios, and Th values indicate the probable presence of pelagic sediments in the protolith. Rare earth element patterns are enriched in the light elements and have slight negative Eu anomalies, resembling the patterns of pelagic clays most closely. The protolith of coticules was apparently a hydrothermal sediment with pelagic and/or terrigenous input. Tourmaline in tourmalinites is chemically similar to stratabound sulfide-related examples. Both coticules and tourmalinites are interpreted as metamorphosed seafloor exhalative sediments and thus indicate the potential for the presence of genetically related ore mineralization.

Wonder, J.D.

1987-08-01

222

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

SciTech Connect

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-1{alpha} protein disappearance, which occurred by inhibiting HIF-prolyl hydroxylase (HPH), the key enzyme for HIF-1{alpha} hydroxylation and subsequent von Hippel-Lindau(VHL)-dependent HIF-1{alpha} degradation. HPH inhibition by manganese (II) was neutralized significantly by elevated dose of iron. Consistent with this, the induction of cellular HIF-1{alpha} 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.

Han, Jeongoh [Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735 (Korea, Republic of); Lee, Jong-Suk [Laboratory of Physiology, College of Pharmacy, Yeungnam University, Gyeongsan (Korea, Republic of); Choi, Daekyu; Lee, Youna; Hong, Sungchae; Choi, Jungyun; Han, Songyi [Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735 (Korea, Republic of); Ko, Yujin; Kim, Jung-Ae [Laboratory of Physiology, College of Pharmacy, Yeungnam University, Gyeongsan (Korea, Republic of); Mi Kim, Young [Medicinal Chemistry, College of Pharmacy, Pusan National University, Busan (Korea, Republic of); Jung, Yunjin [Laboratory of Biomedicinal Chemistry, College of Pharmacy, Pusan National University, Busan, 609-735 (Korea, Republic of)], E-mail: jungy@pusan.ac.kr

2009-03-15

223

Investigation of the effects of cadmium by micro analytical methods on Lycopersicon esculentum Mill. roots.  

PubMed

The interactions between cadmium stress and plant nutritional elements have been investigated on complete plant or at the level of organs. This study was undertaken to contribute to the exploration of the physiological basis of cadmium phytotoxicity. We examined the changes in the nutritional element compositions of the root epidermal cells of the seedlings of Lycopersicon esculentum Mill. at the initial growth stages that is known as the most sensitive stage to the stress. Effects of cadmium stress on the seedlings of Lycopersicon esculentum Mill. were examined by EDX (Energy Dispersive X-Ray Microanalysis) assay performed with using low vacuum (? 24 Pascal) Scanning Electron Microscopy. In the analysis performed at the level of root epidermal cells, some of the macro- and micronutrient contents of the cells (carbon, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, copper, and zinc levels) were found to change when the applying toxic concentrations of cadmium. There was no change in the manganese and sodium content of the epidermal cells. It was concluded that the changes in nutritional element composition of the cells can be considered as an effective parameter in explaining the physiological mechanisms of cadmium-induced growth inhibition. PMID:25194735

Colak, G; Baykul, M C; Gürler, R; Catak, E; Caner, N

2014-09-01

224

Localization and Role of Manganese Superoxide Dismutase in a Marine Diatom1[OA  

E-print Network

Localization and Role of Manganese Superoxide Dismutase in a Marine Diatom1[OA] Felisa Wolfe-Simon2 by their metal cofactor (iron, manganese [Mn], copper/zinc, nickel), MnSOD is the dominant form in the diatom in four isoforms, recognized by their metal center cofactors (iron [Fe], manganese [Mn], copper [Cu

225

Long-distance transport, vacuolar sequestration and transcriptional responses induced by cadmium and arsenic  

PubMed Central

Summary Iron, zinc, copper and manganese are essential metals for cellular enzyme functions while cadmium, mercury and the metalloid arsenic lack any biological function. Both, essential and non-essential metals and metalloids are extremely reactive and toxic. Therefore, plants have acquired specialized mechanisms to sense, transport and maintain essential metals within physiological concentrations and to detoxify non-essential metals and metalloids. This review focuses on the recent identification of transporters that sequester cadmium and arsenic in vacuoles and the mechanisms mediating the partitioning of these metal(loid)s between roots and shoots. We further discuss recent models of phloem-mediated long-distance transport, seed accumulation of Cd and As and recent data demonstrating that plants posses a defined transcriptional response that allow plants to preserve metal homeostasis. This research is instrumental for future engineering of reduced toxic metal(loid) accumulation in edible crop tissues as well as for improved phytoremediation technologies. PMID:21820943

Mendoza-Cózatl, David G.; Jobe, Timothy O.; Hauser, Felix; Schroeder, Julian I.

2011-01-01

226

MODIFYING IRON REMOVAL PROCESSES TO INCREASE ARSENIC REMOVAL  

EPA Science Inventory

Iron and manganese are naturally occurring substances that are normally found in insoluble forms in many ground waters in the US. Similar to iron and manganese, arsenic also occurs widely in the earth's crust and is a natural contaminant of many ground waters. Iron and manganese ...

227

Application of VNIR diffuse reflectance spectroscopy to estimate soil organic carbon content, and content of different forms of iron and manganese  

NASA Astrophysics Data System (ADS)

Visible and near-infrared (VNIR) diffuse reflectance spectroscopy is a progressive method used for prediction of soil properties. Study was performed on the soils from the agricultural land from the south Moravia municipality of Brumovice. Studied area is characterized by a relatively flat upper part, a tributary valley in the middle and a colluvial fan at the bottom. Haplic Chernozem reminded at the flat upper part of the area. Regosols were formed at steep parts of the valley. Colluvial Chernozem and Colluvial soils were formed at the bottom parts of the valley and at the bottom part of the studied field. The goal of the study was to evaluate relationship between soil spectra curves and organic matter content, and different forms iron and manganese content (Mehlich III extract, ammonium oxalate extract and dithionite-citrate extract). Samples (87) were taken from the topsoil within regular grid covering studied area. The soil spectra curves (of air dry soil and sieved using 2 mm sieve) were measured in the laboratory using spectometer FieldSpec®3 (350 - 2 500 nm). The Fe and Mn contents in different extract were measured using ICP-OES (with an iCAP 6500 Radial ICP Emission spectrometer; Thermo Scientific, UK) under standard analytical conditions. Partial least squares regression (PLSR) was used for modeling of the relationship between spectra and measured soil properties. Prediction ability was evaluated using the R2, root mean square error (RMSE) and normalized root mean square deviation (NRMSD). The results showed the best prediction for Mn (R2 = 0.86, RMSE = 29, NRMSD = 0.11), Fe in ammonium oxalate extract (R2 = 0.82, RMSE = 171, NRMSD = 0.12) and organic matter content (R2 = 0.84, RMSE = 0.13, NRMSD = 0.09). The slightly worse prediction was obtained for Mn and Fe in citrate extract (R2 = 0.82, RMSE = 21, NRMSD = 0.10; R2 = 0.77, RMSE = 522, NRMSD = 0.23). Poor prediction was evaluated for Mn and Fe in Mehlich III extract (R2 = 0.43, RMSE = 13, NRMSD = 0.17; R2 = 0.39, RMSE = 13, NRMSD = 0.26). In general, the results confirmed that the measurement of soil spectral characteristics is a promising technology for a digital soil mapping and predicting studied soil properties. Acknowledgment: Authors acknowledge the financial support of the Ministry of Agriculture of the Czech Republic (grant No. QJ1230319) and the Czech Science Foundation (grant No. GA526/09/1762).

Klement, Ales; Jaksik, Ondrej; Kodesova, Radka; Drabek, Ondrej; Boruvka, Lubos

2013-04-01

228

Method for selective recovery of cadmium from cadmium-bearing waste  

Microsoft Academic Search

A method for the selective recovery of cadmium, nickel and cobalt from a nickel--cadmium battery waste comprises the following steps: (A) leaching the waste with an ammoniacal carbonate solution to form an aqueous ammoniacal carbonate solution containing cadmium, nickel and cobalt (II) ammine complexes and a leaching residue--any iron in the waste is in the leaching residue; (B) adding air

H. Reinhardt; H. D. Ottertun; J. H. A. Rydberg

1977-01-01

229

Cadmium transport in isolated enterocytes of freshwater rainbow trout: interactions with zinc and iron, effects of complexation with cysteine, and an ATPase-coupled efflux.  

PubMed

The present study investigated the mechanisms of intestinal cadmium (Cd) uptake and efflux, using isolated enterocytes of freshwater rainbow trout (Oncorhynchus mykiss) as the experimental model. The apical uptake of free Cd(2+) in the enterocytes was a saturable and high-affinity transport process. Both zinc (Zn(2+)) and iron (Fe(2+)) inhibited cellular Cd(2+) uptake through a competitive interaction, suggesting that Cd(2+) enters enterocytes via both Zn(2+) (e.g., ZIP8) and Fe(2+) (e.g., DMT1) transport pathways. Cellular Cd(2+) uptake increased in the presence of HCO(3)(-), which resembled the function of mammalian ZIP8. Cellular Cd(2+) uptake was unaffected by Ca(2+), indicating that Cd(2+) does not compete with Ca(2+) for apical uptake. Interestingly, Cd uptake was influenced by the presence of l-cysteine, and under the exposure condition where Cd(Cys)(+) was the predominant Cd species, cellular Cd uptake rate increased with the increased concentration of Cd(Cys)(+). The kinetic analysis indicated that the uptake of Cd(Cys)(+) occurs through a low capacity transport mechanism relative to that of free Cd(2+). In addition, Cd efflux from the enterocytes decreased in the presence of an ATPase inhibitor (orthovanadate), suggesting the existence of an ATPase-coupled extrusion process. Overall, our findings provide new mechanistic insights into the intestinal Cd transport in freshwater fish. PMID:21930242

Kwong, Raymond W M; Niyogi, Som

2012-03-01

230

A Holocene record of endogenic iron and manganese precipitation, isotopic composition of endogenic carbonate, and vegetation history in a lake-fen complex in northwestern Minnesota  

USGS Publications Warehouse

Little Shingobee Lake and Fen are part of an extensive network of lakes and wetlands in the Shingobee River headwaters area of northwestern Minnesota. Prior to about 9800 radiocarbon years, most of the lakes in the Shingobee watershed area were interconnected to form glacial Lake Willobee. From 9800 to 7700 radiocarbon years, the level of Lake Willobee fell as a result of breaching of a dam, leaving small separated basins containing the existing lakes and wetlands. The dominant components in the sediments in a 9-meter core from Little Shingobee Lake (LSL-B), and lacustrine sediments under 3.3 meters of peat in a 17-meter core from Little Shingobee Fen (LSF-10) are detrital clastic material, endogenic CaCO3, and organic matter. The detrital fraction in the Holocene section in core LSL-B varies considerably from 7 weight percent to 82 weight percent and closely parallels the concentration of detrital quartz measured by X-ray diffraction. The CaCO3 concentration, which also varies considerably from 10 weight percent to 70 weight percent, is generally antithetic to the detrital concentration owing to the dilution of detrital material by CaCO3, particularly during the early to middle Holocene (about 9000-6500 calendar years). The organic-matter content varies from 5 weight percent to 25 weight percent and, together with CaCO3, serves to dilute the allogenic detrital fraction. In both cores almost all of the iron (Fe) and manganese (Mn) is in endogenic minerals, presumed to be oxyhydroxide minerals, that are important components throughout the core; little Fe and Mn are contributed by detrital aluminosilicate minerals. The endogenic Fe mineral, calculated as Fe(OH)3, forms a larger percentage of the sediment than endogenic organic material throughout most of the Holocene section in the LSL-B core and in the lacustrine sediments below the peat in the LSF-10 core. Biogenic silica as opal (biopal; diatom debris) was not measured, but the average calculated biopal is 5 percent in the LSL-B core and 15.5 percent in the LSF-10 core. Values of delta18O in mollusk (Pisidium) and ostracode shells increase by only about 20 per mil from the bottom to the top of the LSL-B core (about 12600-2200 calendar years). The remarkably constant oxygen-isotope composition throughout the Holocene suggests that environmental conditions affecting values of delta18O (temperature, salinity, composition of the water, composition of precipitation) did not change greatly. Values of delta13C in carbonate shells generally decreased by about 2 per mil from 9000 calendar years to 6000 calendar years, but they did not increase in organic carbon. This mid-Holocene increase in delta13C in shells but not in organic carbon is likely due to an increase in residence time. A late Pleistocene forest dominated by spruce was replaced in the early Holocene by a pine forest. The pine forest migrated east during the middle Holocene and was replaced by an open sagebrush-oak savanna. The western migration of forests into northwestern Minnesota is marked first by a hardwood forest and finally a pine forest.

Dean, Walter E.; Doner, Lisa A.

2011-01-01

231

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

PubMed Central

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

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

2011-01-01

232

Structure of highly divided nonstoichiometric iron manganese oxide powders Fe{sub 3{minus}x}Mn{sub x{open_square}{sub 3{delta}/4}}O{sub 4+{delta}}  

SciTech Connect

Highly divided iron manganese oxide powders, Fe{sub 3{minus}x}Mn{sub x{open_square}{sub 3{delta}/4}}O{sub 4+{delta}}, were prepared at low temperature (T {le} 560 C) by the thermal decomposition of mixed oxalate precursors Fe{sub 1{minus}{alpha}}Mn{sub {alpha}}C{sub 2}O{sub 4}, 2H{sub 2}O ({alpha} = x/3). The manganese-rich compounds (x {ge} 1.5) have a complex structure that can be cubic, tetragonal, or a mixture of both tetragonal and cubic spinel phases that indicates a lack of miscibility existing in the Fe{sub 3}O{sub 4}-Mn{sub 3}O{sub 4} phase diagram at low temperature. The structure strongly depends on the chemical composition but also on the nonstoichiometric coefficient ({delta}). It has been identified as one of the mineral vredenburgite and has never been reported before for powders prepared by chimie douce. The oxygen excess, determined by thermogravimetric analyses, is the highest ({delta} = 0.4) when the oxide is prepared at 410 C. These oxides are defect spinel phases containing cationic vacancies.

Guillemet-Fritsch, S.; Viguie, S.; Rousset, A. [Univ. Paul Sabatier, Toulouse (France). Lab. de Chimie des Materiaux Inorganiques et Enginetiques] [Univ. Paul Sabatier, Toulouse (France). Lab. de Chimie des Materiaux Inorganiques et Enginetiques

1999-08-01

233

Determination of iron, cobalt, nickel, manganese, zinc, copper, cadmium and lead in human hair by inductively coupled plasma-atomic emission spectrometry  

Microsoft Academic Search

A method was standardized for the dissolution of hair samples and analysis was carried out by inductively coupled plasma atomic emission spectrometry (ICP-AES). Hair samples were brought into solution by using a mixture of nitric acid and hydrogen peroxide. Various parameters that influence the sample preparation, namely temperature, digestion time and ratio of acid mixture were studied and standardized. The

K. Sreenivasa Rao; T. Balaji; T. Prasada Rao; Y. Babu; G. R. K. Naidu

2002-01-01

234

Levels of lead, cadmium, copper, iron, and zinc in deciduous teeth of children living in Irbid, Jordan by ICP-OES: some factors affecting their concentrations.  

PubMed

The aim of this study was to measure the concentrations of lead (Pb), cadmium (Cd), copper (Cu), iron (Fe), and zinc (Zn) in deciduous teeth from children living in Jordan and to investigate the affecting factors. Deciduous teeth samples (n = 320, without fillings) were collected from 5- to 12-year-old children and analyzed for Pb, Cd, Cu, Fe, and Zn using inductively coupled plasma-optical emission spectrometry. A questionnaire was used to gather information on each child, such as sex, age, tooth type (incisors, canines, and molars), tooth position within the mouth (upper or lower jaw), caries status, presence of amalgam fillings inside the mouth, type of drinking water (tap water, home purified water, and plant purified water), and zone of residence (close to or far from heavy traffic roads). The mean concentrations of Pb, Cd, Cu, Fe, and Zn were 30.26, 0.55, 6.23, 34.72, and 128.21 ?g/g, respectively. Our results indicate that there is a clear relation between the concentrations of the metals analyzed in this study and tooth type, tooth position within the mouth, caries status, presence of amalgam fillings inside the mouth, and type of drinking water. No significant differences in the concentrations of the five metals analyzed were observed due to sex. Our results also show that no significant difference among Pb, Cd, Cu, Fe, and Zn concentrations and age among the ages of 5-6, 7-8, 9-10, and 11-12, except for Pb, which decreases at age 11-12. PMID:22851195

Alomary, A; Al-Momani, I F; Obeidat, S M; Massadeh, A M

2013-04-01

235

Manganese biofouling and the corrosion behavior of stainless steel  

Microsoft Academic Search

Manganese? and iron?oxidizing bacteria (MFOB) are widely implicated in microbially influenced corrosion, often in association with sulfate?reducing bacteria (SRB). Traditionally MFOB have been assigned a passive role in the corrosion process, promoting differential aeration cells, and providing oxygen depleted conditions conducive to the growth and corrosive attack of SRB. Recent work, summarized in this article, demonstrates that manganese biofouling alters

W. H. Dickinson; Z. Lewandowski

1996-01-01

236

Ecological risk assessment of on-site soil washing with iron(III) chloride in cadmium-contaminated paddy field.  

PubMed

On-site soil washing with iron(III) chloride reduces Cd levels in soil, and thus the human health risks caused by Cd in food. However, it may threaten aquatic organisms when soil washing effluent is discharged to open aquatic systems. Therefore, we conducted trial-scale on-site soil washing and ecological risk assessment in Nagano and Niigata prefectures, Japan. The ecological effect of effluent water was investigated by two methods. The first was bioassay using standard aquatic test organisms. Twice-diluted effluent water from the Nagano site and the original effluent water from the Niigata site had no significant effects on green algae, water flea, caddisfly, and fish. The safe dilution rates were estimated as 20 times and 10 times for the Nagano and Niigata sites, respectively, considering an assessment factor of 10. The second method was probabilistic effect analysis using chemical analysis and the species sensitivity distribution concept. The mixture effects of CaCl(2), Al, Zn, and Mn were considered by applying a response additive model. The safe dilution rates, assessed for a potentially affected fraction of species of 5%, were 7.1 times and 23.6 times for the Nagano and Niigata sites, respectively. The actual dilution rates of effluent water by river water at the Nagano and Niigata sites were 2200-67,000 times and 1300-110,000 times, respectively. These are much larger than the safe dilution rates derived from the two approaches. Consequently, the ecological risk to aquatic organisms of soil washing is evaluated as being below the concern level. PMID:22377402

Nagai, Takashi; Horio, Takeshi; Yokoyama, Atsushi; Kamiya, Takashi; Takano, Hiroyuki; Makino, Tomoyuki

2012-06-01

237

Role of mineral nutrition in minimizing cadmium accumulation by plants.  

PubMed

Cadmium (Cd) is a highly toxic heavy metal for both plants and animals. The presence of Cd in agricultural soils is of great concern regarding its entry into the food chain. Cadmium enters into the soil-plant environment mainly through anthropogenic activities. Compounds of Cd are more soluble than other heavy metals, so it is more available and readily taken up by plants and accumulates in different edible plant parts through which it enters the food chain. A number of approaches are being used to minimize the entry of Cd into the food chain. Proper plant nutrition is one of the good strategies to alleviate the damaging effects of Cd on plants and to avoid its entry into the food chain. Plant nutrients play a very important role in developing plant tolerance to Cd toxicity and thus, low Cd accumulation in different plant parts. In this report, the role of some macronutrients (nitrogen, phosphorus, sulfur and calcium), micronutrients (zinc, iron and manganese), and silicon (a beneficial nutrient) has been discussed in detail as to how these nutrients play their role in decreasing Cd uptake and accumulation in crop plants. PMID:20355131

Sarwar, Nadeem; Malhi, Sukhdev S; Zia, Munir Hussain; Naeem, Asif; Bibi, Sadia; Farid, Ghulam

2010-04-30

238

Nutritional interactions in intestinal cadmium uptake--possibilities for risk reduction.  

PubMed

Effects of dietary composition and trace element status on fractional intestinal cadmium uptake is reviewed below. Fractional cadmium uptake is of fundamental importance for internal dose, related individual susceptibility to cadmium, induced renal damage and eventually bone disease. Diet composition with regard to macronutrients has some effects on cadmium bioavailability. Major determinants of intestinal cadmium uptake are however diet composition with regard to crude fibres and trace elements, especially iron. Deficiencies may increase intestinal cadmium uptake 5-8 times. Ultimate risk management would be not to raise crops on cadmium polluted soil. Provisionally, assurance of optimal trace element statusin persons exposed to cadmium is essential for risk reduction. PMID:15688861

Andersen, Ole; Nielsen, Jesper B; Nordberg, Gunnar F

2004-10-01

239

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

Microsoft Academic Search

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

Kevin B. Hallberg; D. Barrie Johnson

2005-01-01

240

Spectroscopic characterization of manganese minerals  

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

241

Determination of calcium, copper, iron, magnesium, manganese, potassium, phosphorus, sodium, and zinc in fortified food products by microwave digestion and inductively coupled plasma-optical emission spectrometry: single-laboratory validation and ring trial.  

PubMed

A single-laboratory validation (SLV) and a ring trial (RT) were undertaken to determine nine nutritional elements in food products by inductively coupled plasma-optical emission spectrometry in order to modernize AOAC Official Method 984.27. The improvements involved extension of the scope to all food matrixes (including infant formula), optimized microwave digestion, selected analytical lines, internal standardization, and ion buffering. Simultaneous determination of nine elements (calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc) was made in food products. Sample digestion was performed through wet digestion of food samples by microwave technology with either closed- or open-vessel systems. Validation was performed to characterize the method for selectivity, sensitivity, linearity, accuracy, precision, recovery, ruggedness, and uncertainty. The robustness and efficiency of this method was proven through a successful RT using experienced independent food industry laboratories. Performance characteristics are reported for 13 certified and in-house reference materials, populating the AOAC triangle food sectors, which fulfilled AOAC criteria and recommendations for accuracy (trueness, recovery, and z-scores) and precision (repeatability and reproducibility RSD, and HorRat values) regarding SLVs and RTs. This multielemental method is cost-efficient, time-saving, accurate, and fit-for-purpose according to ISO 17025 Norm and AOAC acceptability criteria, and is proposed as an extended updated version of AOAC Official Method 984.27 for fortified food products, including infant formula. PMID:22468357

Poitevin, Eric

2012-01-01

242

210Pb and 210Po, manganese and iron cycling across the O2/H2S interface of a permanently anoxic fjord: Framvaren, Norway  

USGS Publications Warehouse

Vertical profiles of dissolved and particulate 201Po and 210Pb were measured across the redox transition zone at Station F1 in Framvaren Fjord, Norway. In this fjord, a sharp decrease in pH above the O2/H2S interface facilitates the aerobic dissolution of MnO2. In contrast, Fe(II) concentrations begin to increase only at the O2/H2S interface depth. Activity profiles reveal that dissolved 210Po and 210Pb are sequestered efficiently by particulates in surface waters. As polonium-210 and lead-210 activities descend down into the aerobic manganese reduction (AMR) zone, they are remobilized during the reductive dissolution of the carrier phase oxyhydroxides. Both 210Po and 210Pb are highly enriched at the O2/H2S interface where an active community of microbes, such as anoxygenic phototrophs (e.g., Chromatium, Chlorobium sp.), thrives. The coincident peaks in 210Po and 210Pb and microbial biomass suggest a strong biological influence on the behavior of these radionuclides. There is a strong covariance between the vertical distribution of Mn and Pb, indicating that their redox cycling is closely coupled and is likely microbially mediated.

Swarzenski, Peter W.; McKee, Brent A.; Sorenson, Kai; Todd, James F.

1999-01-01

243

Assessment of the permissible exposure level to manganese in workers exposed to manganese dioxide dust  

Microsoft Academic Search

The prevalence of neuropsychological and respiratory symptoms, lung ventilatory parameters, neurofunctional performances (visual reaction time, eye-hand coordination, hand steadiness, audioverbal short term memory), and several biological parameters (calcium, iron, luteinising hormone (LH), follicle stimulating hormone (FSH), and prolactin concentrations in serum, blood counts, manganese (Mn) concentration in blood and in urine) were examined in a group of workers (n =

H A Roels; P Ghyselen; J P Buchet; E Ceulemans; R R Lauwerys

1992-01-01

244

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

PubMed Central

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 106 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. PMID:22572639

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

2012-01-01

245

Electronic structure of the dioxygen to transition metal bond: generalized molecular orbital calculations on models of manganese, iron, and cobalt porphyrins  

E-print Network

-like character previously reported for the Fe-0 unit in 2 iron dioxygen porphyrins is not observed in the GMO-CI results. The Fe-0 unit appears to be a Fe (S=O)0 (S=O) state in which a pair +2 2 2 of electrons is donated to an Fe atom from the a state...)(N4CZH6)(NH3). . . . . . Compar1son of the Fe-0 ~-Orbital Coeff1cients for 2 the GMO-CI Calculations of Fe(02)(N4CZH6) (NH3) with 0 0 0-0 Bond Lengths of 1. 24A and 1. 21A. . Primary Conf1gur at1ons of the A" Ground-State Wavefunct1on of Co(02)(N...

Newton, James Edward

2012-06-07

246

Bacteriogenic manganese oxides.  

PubMed

Microorganisms control the redox cycling of manganese in the natural environment. Although the homogeneous oxidation of Mn(II) to form manganese oxide minerals is slow, solid MnO(2) is the stable form of manganese in the oxygenated portion of the biosphere. Diverse bacteria and fungi have evolved the ability to catalyze this process, producing the manganese oxides found in soils and sediments. Other bacteria have evolved to utilize MnO(2) as a terminal electron acceptor in respiration. This Account summarizes the properties of Mn oxides produced by bacteria (bacteriogenic MnO(2)) and our current thinking about the biochemical mechanisms of bacterial Mn(II) oxidation. According to X-ray absorption spectroscopy and X-ray scattering studies, the MnO(2) produced by bacteria consists of stacked hexagonal sheets of MnO(6) octahedra, but these particles are extremely small and have numerous structural defects, particularly cation vacancies. The defects provide coordination sites for binding exogenous metal ions, which can be adsorbed to a high loading. As a result, bacterial production of MnO(2) influences the bioavailability of these metals in the natural environment. Because of its high surface area and oxidizing power, bacteriogenic MnO(2) efficiently degrades biologically recalcitrant organic molecules to lower-molecular-mass compounds, spurring interest in using these properties in the bioremediation of xenobiotic organic compounds. Finally, bacteriogenic MnO(2) is reduced to soluble Mn(II) rapidly in the presence of exogenous ligands or sunlight. It can therefore help to regulate the bioavailability of Mn(II), which is known to protect organisms from superoxide radicals and is required to assemble the water-splitting complex in photosynthetic organisms. Bioinorganic chemists and microbiologists have long been interested in the biochemical mechanism of Mn(IV) oxide production. The reaction requires a two-electron oxidation of Mn(II), but genetic and biochemical evidence for several bacteria implicate multicopper oxidases (MCOs), which are only known to engage one-electron transfers from substrate to O(2). In experiments with the exosporium of a Mn(II)-oxidizing Bacillus species, we could trap the one-electron oxidation product, Mn(III), as a pyrophosphate complex in an oxygen-dependent reaction inhibited by azide, consistent with MCO catalysis. The Mn(III) pyrophosphate complex can further act as a substrate, reacting in the presence of the exosporium to produce Mn(IV) oxide. Although this process appears to be unprecedented in biology, it is reminiscent of the oxidation of Fe(II) to form Fe(2)O(3) in the ferritin iron storage protein. However, it includes a critical additional step of Mn(III) oxidation or disproportionation. We shall continue to investigate this biochemically unique process with purified enzymes. PMID:19778036

Spiro, Thomas G; Bargar, John R; Sposito, Garrison; Tebo, Bradley M

2010-01-19

247

Evaluation of powdered elemental iron as a plant nutrient in Texas soils  

E-print Network

Experiments Plant analysis. Location 1. o 1 cg Location 2 -'3 Yield Locai, ion 1 Location 2 vii Chapter Incubation Study Chemical analysis. Page 31 31 PN Iron Manganese. Zinc 31 43 57 66 V SUMNABY AND CONCLUSIONS . LITERATUBL" CITED... to incubation time. 59 12 Mean manganese concentration (DTPA extract- able) in four Texas soils due to treatments . 59 1 3 Manganese concentration (DTPA extractable) due to the addition of elemental iron Fe(1000 kg/ha). 60 14 Manganese concentration (DTPA...

Schneider, Russell Paul

2012-06-07

248

A study of the kinetics and fate of zinc-65 and iron-59 mobilized from labeled ghosts by reticulocyte lysates of normal and cadmium-treated rabbits  

E-print Network

(12, 55, 56). lrcsh, nonsterile, pooled rabbit serum was ob- tained from Pel Fre& z Laboratories for use as starting mat& rial . A saturating amount of iron nitrilotriacetate was added to an aliquot of serum, assuming the concentration... (12, 55, 56). lrcsh, nonsterile, pooled rabbit serum was ob- tained from Pel Fre& z Laboratories for use as starting mat& rial . A saturating amount of iron nitrilotriacetate was added to an aliquot of serum, assuming the concentration...

McAleese, Kathryn Noel

2012-06-07

249

Pathways of iron absorption.  

PubMed

Iron is vital for all living organisms but excess iron can be lethal because it facilitates free radical formation. Thus iron absorption is carefully regulated to maintain an equilibrium between absorption and body loss of iron. In countries where meat is a significant part of the diet, most body iron is derived from dietary heme because heme binds few of the dietary chelators that bind inorganic iron. Uptake of heme into enterocytes occurs as a metalloporphyrin in an endosomal process. Intracellular iron is released from heme by heme oxygenase to enter plasma as inorganic iron. Ferric iron is absorbed via a beta(3) integrin and mobilferrin pathway (IMP) which is unshared with other nutritional metals. Ferrous iron uptake is facilitated by a DMT-1 pathway which is shared with manganese. In the iron deficient gut, large quantities of both mobilferrin and DMT-1 are found in goblet cells and intraluminal mucins suggesting that they are secreted with mucin into the intestinal lumen to bind iron to facilitate uptake by the cells. In the cytoplasm, IMP and DMT associate in a large protein complex called paraferritin which serves as a ferrireductase. Paraferritin solublizes iron binding proteins and reduces iron to make iron available for production of iron containing proteins such as heme. Iron uptake by intestinal absorptive cells is regulated by the iron concentration within the cell. Except in hemochromatosis it remains in equilibrium with total body stores via transferrin receptors on the basolateral membrane of absorptive cells. Increased intracellular iron either up-regulates or satiates iron binding proteins on regulatory proteins to alter their location in the intestinal mucosa. PMID:12547224

Conrad, Marcel E; Umbreit, Jay N

2002-01-01

250

Olfactory uptake of manganese requires DMT1 and is enhanced by anemia  

PubMed Central

Manganese, an essential nutrient, can also elicit toxicity in the central nervous system (CNS). The route of exposure strongly influences the potential neurotoxicity of manganese-containing compounds. Recent studies suggest that inhaled manganese can enter the rat brain through the olfactory system, but little is known about the molecular factors involved. Divalent metal transporter-1 (DMT1) is the major transporter responsible for intestinal iron absorption and its expression is regulated by body iron status. To examine the potential role of this transporter in uptake of inhaled manganese, we studied the Belgrade rat, since these animals display significant defects in both iron and manganese metabolism due to a glycine-to-arginine substitution (G185R) in their DMT1 gene product. Absorption of intranasally instilled 54Mn was significantly reduced in Belgrade rats and was enhanced in iron-deficient rats compared to iron-sufficient controls. Immunohistochemical experiments revealed that DMT1 was localized to both the lumen microvilli and end feet of the sustentacular cells of the olfactory epithelium. Importantly, we found that DMT1 protein levels were increased in anemic rats. The apparent function of DMT1 in olfactory manganese absorption suggests that the neurotoxicity of the metal can be modified by iron status due to the iron-responsive regulation of the transporter. PMID:17116743

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

2008-01-01

251

Distribution of manganese soil concentrations surrounding ferromanganese plants in Brescia, Italy  

Microsoft Academic Search

Over the past 170 years, scientists have hypothesized that exposure to manganese in both environmental and occupational settings is linked with neurological disorders similar to Parkinson’s Disease, including disturbances of gait, dystonia, bradyknesia, and tremor. Ferromanganese plants produce large amounts of iron and manganese particulate that are released into the air and expose the surrounding communities. The objective of this

Benjamin M Hasbrouck

2008-01-01

252

Manganese Cell Labeling of Murine Hepatocytes Using Manganese(III)-Transferrin  

PubMed Central

Manganese(III)-transferrin (Mn(III)-Tf) was investigated as a way to accomplish manganese-labeling of murine hepatocytes for MRI contrast. It is postulated that Mn(III)-Tf can exploit the same transferrin-receptor-dependent and -independent metabolic pathways used by hepatocytes to transport the iron analogue Fe(III)-Tf. More specifically, it was investigated whether manganese delivered by transferrin could give MRI contrast in hepatocytes. Comparison of the T1 and T2 relaxation times of Mn(III)-Tf and Fe(III)-Tf over the same concentration range showed that the r1 relaxivities of the two metalloproteins are the same in vitro; with little contribution from paramagnetic enhancement. The degree of manganese cell labeling following incubation for 2–7 h in 31.5 ?M Mn(III)-Tf was comparable to that of hepatocytes incubated in 500 ?M Mn2+ for 1 h. The intrinsic manganese tissue relaxivity between Mn(III)-Tf-labeled and Mn2+-labeled cells was found to be the same; consistent with Mn(III) being released from transferrin and reduced to Mn2+. For both treatment regimens, manganese uptake by hepatocytes appeared to saturate in the first 1–2 h of the incubation period and may explain why the efficiency of hepatocyte cell labeling by the two methods appeared to be comparable in spite of the ~16-fold difference in effective manganese concentration. Hepatocytes continuously released manganese, as detected by MRI, and this was the same for both Mn2+- and Mn(III)-Tf-labeled cells. Manganese release may be the result of normal hepatocyte function; much in the same way that hepatocytes excrete manganese into the bile in vivo. This approach exploits a biological process – namely receptor binding, endocytosis, and endosomal acidification – to initiate the release of an MRI contrast agent; potentially confering more specificity to the labeling process. The ubiquitous expression of transferrin receptors by eukaryotic cells should make Mn(III)-Tf particularly useful for manganese labeling of a wide variety of cells both in culture and in vivo. PMID:18546093

Sotak, Christopher H.; Sharer, Kathryn; Koretsky, Alan P.

2011-01-01

253

Increase in methane flux and anaerobic oxidation of methane with iron and manganese oxides recorded in methane-derived carbonate nodules in the eastern margin of the Sea of Japan  

NASA Astrophysics Data System (ADS)

We studied the evolution of pore water geochemistry recorded in methane-derived carbonate nodules containing aggregates of aragonite. We used two samples from a gas hydrate area in the eastern margin of the Sea of Japan, where an increase in methane flux due to sea level drop depressurization during the last glacial epoch was expected. One sample has ellipsoidal and dike-like aggregates where aragonite needles occur radially and as opposed bands, respectively. The other has a belt-like aggregate in which a microcrystalline zone and needle aragonite zone border on each other. For the dike-like and belt-like aggregates, the carbon isotope composition (?13C) of aragonite is approximately -20 ‰VPDB, which is similar to the ?13C of dissolved inorganic carbon (DIC) currently found in the sulfate-methane transition (SMT). Because changes in the ?13C of DIC within the SMT is improbable at the sampling site, the aragonites are believed to have precipitated around the paleo SMT and record the pore water geochemistry of the paleo SMT. In the ellipsoidal aggregate, the aragonite ?13C gradually changes from -4 ‰ VPDB at the ellipsoid center to -12 ‰ at the rim and -23 ‰VPDB in the surrounding matrix. Because depth profile of DIC ?13C has negative peak at the SMT and the ?13C of DIC becomes higher with distance from the SMT, this ?13C trend indicates a gradual change in SMT depth relative to the ellipsoidal aggregate in sediments. Laser ablation ICP-MS traverses (a few hundred ?m interval) revealed gradually increasing barium concentration from rim to core in the ellipsoidal aggregate and fluctuations in rare earth elements (REEs) and manganese (Mn) abundances. These variations are consistent with a scenario of increasing methane flux and ensuing microbial anaerobic oxidation of methane (AOM) with iron (Fe) and Mn oxides and abiotic reduction of Mn oxide with AOM-derived Fe2+. The ellipsoidal aggregate thus preserves the evolution of pore water geochemistry caused by increased methane flux. Traverses across the dike-like and belt-like aggregates show no Mn peak and have approximately one order of magnitude lower REE concentrations than the ellipsoidal aggregate. The SMTs which geochemistry was recorded in these aggregates was distant from Fe- and Mn-cycling depths or in a steady state with respect to Fe and Mn redox. Gradual depletion of REEs in the older part of the belt-like aggregate is a record of the transition toward a redox steady state.

Hiruta, A.; Himmler, T.; Kluegel, A.; Matsumoto, R.

2012-12-01

254

Longitudinal MRI contrast enhanced monitoring of early tumour development with manganese chloride (MnCl2) and superparamagnetic iron oxide nanoparticles (SPIOs) in a CT1258 based in vivo model of prostate cancer  

PubMed Central

Background Cell lines represent a key tool in cancer research allowing the generation of neoplasias which resemble initial tumours in in-vivo animal models. The characterisation of early tumour development is of major interest in order to evaluate the efficacy of therapeutic agents. Magnetic resonance imaging (MRI) based in-vivo characterisation allows visualisation and characterisation of tumour development in early stages prior to manual palpation. Contrast agents for MRI such as superparamagnetic iron oxide nanoparticles (SPIOs) and manganese chloride (MnCl2) represent powerful tools for the in-vivo characterisation of early stage tumours. In this experimental study, we labelled prostate cancer cells with MnCl2 or SPIOs in vitro and used 1?T MRI for tracing labelled cells in-vitro and 7?T MRI for tracking in an in-vivo animal model. Methods Labelling of prostate cancer cells CT1258 was established in-vitro with MnCl2 and SPIOs. In-vitro detection of labelled cells in an agar phantom was carried out through 1?T MRI while in-vivo detection was performed using 7?T MRI after subcutaneous (s.c.) injection of labelled cells into NOD-Scid mice (n?=?20). The animals were scanned in regular intervals until euthanization. The respective tumour volumes were analysed and corresponding tumour masses were subjected to histologic examination. Results MnCl2in-vitro labelling resulted in no significant metabolic effects on proliferation and cell vitality. In-vitro detection-limit accounted 105 cells for MnCl2 as well as for SPIOs labelling. In-vivo 7?T MRI scans allowed detection of 103 and 104 cells. In-vivo MnCl2 labelled cells were detectable from days 4–16 while SPIO labelling allowed detection until 4?days after s.c. injection. MnCl2 labelled cells were highly tumourigenic in NOD-Scid mice and the tumour volume development was characterised in a time dependent manner. The amount of injected cells correlated with tumour size development and disease progression. Histological analysis of the induced tumour masses demonstrated characteristic morphologies of prostate adenocarcinoma. Conclusions To the best of our knowledge, this is the first study reporting direct in-vitro MnCl2 labelling and 7?T based in-vivo MRI tracing of cancer cells in a model of prostate cancer. MnCl2 labelling was found to be suitable for in-vivo tracing allowing long detection periods. The labelled cells kept their highly tumourigenic potential in-vivo. Tumour volume development was visualised prior to manual palpation allowing tumour characterisation in early stages of the disease. PMID:22784304

2012-01-01

255

A Manganese-rich Environment Supports Superoxide Dismutase Activity in a Lyme Disease Pathogen, Borrelia burgdorferi*  

PubMed Central

The Lyme disease pathogen Borrelia burgdorferi represents a novel organism in which to study metalloprotein biology in that this spirochete has uniquely evolved with no requirement for iron. Not only is iron low, but we show here that B. burgdorferi has the capacity to accumulate remarkably high levels of manganese. This high manganese is necessary to activate the SodA superoxide dismutase (SOD) essential for virulence. Using a metalloproteomic approach, we demonstrate that a bulk of B. burgdorferi SodA directly associates with manganese, and a smaller pool of inactive enzyme accumulates as apoprotein. Other metalloproteins may have similarly adapted to using manganese as co-factor, including the BB0366 aminopeptidase. Whereas B. burgdorferi SodA has evolved in a manganese-rich, iron-poor environment, the opposite is true for Mn-SODs of organisms such as Escherichia coli and bakers' yeast. These Mn-SODs still capture manganese in an iron-rich cell, and we tested whether the same is true for Borrelia SodA. When expressed in the iron-rich mitochondria of Saccharomyces cerevisiae, B. burgdorferi SodA was inactive. Activity was only possible when cells accumulated extremely high levels of manganese that exceeded cellular iron. Moreover, there was no evidence for iron inactivation of the SOD. B. burgdorferi SodA shows strong overall homology with other members of the Mn-SOD family, but computer-assisted modeling revealed some unusual features of the hydrogen bonding network near the enzyme's active site. The unique properties of B. burgdorferi SodA may represent adaptation to expression in the manganese-rich and iron-poor environment of the spirochete. PMID:23376276

Aguirre, J. Dafhne; Clark, Hillary M.; McIlvin, Matthew; Vazquez, Christine; Palmere, Shaina L.; Grab, Dennis J.; Seshu, J.; Hart, P. John; Saito, Mak; Culotta, Valeria C.

2013-01-01

256

Transcriptional regulation of metal transport genes and mineral nutrition during acclimatization to cadmium and zinc in the Cd/Zn hyperaccumulator, Thlaspi caerulescens (Ganges population).  

PubMed

We investigated changes in mineral nutrient uptake and cellular expression levels for metal transporter genes in the cadmium (Cd)/zinc (Zn) hyperaccumulator, Thlaspi caerulescens during whole plant and leaf ontogenesis under different long-term treatments with Zn and Cd. Quantitative mRNA in situ hybridization (QISH) revealed that transporter gene expression changes not only dependent on metal nutrition/toxicity, but even more so during plant and leaf development. The main mRNA abundances found were: ZNT1, mature leaves of young plants; ZNT5, young leaves of young plants; MTP1 (= ZTP1 = ZAT), young leaves of both young and mature plants. Surprisingly different cellular expression patterns were found for ZNT1 and ZNT5, both belonging to the ZIP family of transition metal transporters: ZNT1, photosynthetic mesophyll and bundle sheath cells; ZNT5, nonphotosynthetic epidermal metal storage cells and bundle sheath cells. Thus, ZNT1 may function in micronutrient nutrition while ZNT5 may be involved in metal storage associated with hyperaccumulation. Cadmium inhibited the uptake of Zn, iron (Fe) and manganese (Mn), probably by competing for transporters or by interfering with the regulation of transporter gene expression. Cadmium-induced changes in cellular expression for ZNT1, ZNT5 and MTP1 could also be part of plant acclimatization to Cd toxicity. Defence against Cd toxicity involved enhanced uptake of magnesium (Mg), calcium (Ca) and sulphur (S). PMID:19843304

Küpper, Hendrik; Kochian, Leon V

2010-01-01

257

Globally sustainable manganese metal production and use.  

PubMed

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 reduces the quantity of solid wastes generated during processing. Secondary aluminum facilities have reported hazardous waste generation management issues due to baghouse dusts from rotary furnaces processing selenium contaminated manganese alloys. Environmental impacts resulting from industry are represented by emission inventories of chemical releases to the air, water, and soil. The U.S. metals industry releases reported to EPA Toxic Release Inventory indicate the primary metals industry is the major source of metal air toxic emissions, exceeding electric utility air toxic emissions. The nonferrous metals industry is reported to be the Organization for Economic Co-operation and Development (OECD) most intensive airborne and land pollution source of bioaccumulative metals. However, total waste emissions from industries in the OECD countries have declined due to improving energy consumption. Emission registers and access are improving around the world. However, environmental databases for metal particulates have low confidence ratings since the majority of air toxic emissions are not reported, not monitored, or are estimated based on worst-case emission factors. Environmental assessments including biological monitoring are necessary to validate mandated particulate metal emission reductions and control technologies during metal processing. PMID:19467569

Hagelstein, Karen

2009-09-01

258

Seasonal variability in cadmium, lead, copper, zinc and iron concentrations in the three major fish species, Oreochromis niloticus, Lates niloticus and Rastrineobola argentea in Winam Gulf, Lake Victoria: impact of wash-off into the lake.  

PubMed

Trace metals Cadmium (Cd), Lead (Pb), Copper (Cu), Zinc (Zn) and Iron (Fe) were analyzed in edible portions of three main finfish species namely Lates niloticus, Oreochromis niloticus and Rastrineobola argentea sampled from various beaches of Winam Gulf, Lake Victoria, Kenya, in order to determine any seasonal and site variations and the results showed significantly (p < 0.05) higher mean concentrations of Cd, Cu, Zn and Fe during the wet season compared to the dry season for all the three species indicating the impact of wash-off into the lake during the rainy periods. The overall mean concentrations of the heavy metals (in ?g/g dry weight) in all combined samples ranged from 0.17-0.40 (Cd), 0.47-2.53 (Pb), 2.13-8.74 (Cu), 28.9-409.3 (Zn) and 31.4-208.1 (Fe), respectively. It was found that consumption of Rastrineobola argentea can be a significant source of heavy metals especially Zn, to humans, compared with Lates niloticus and Oreochromis niloticus, if only the muscle parts of the latter two are consumed. PMID:22130608

Ongeri, David M K; Lalah, Joseph O; Wandiga, Shem O; Schramm, Karl-Werner; Michalke, Bernard

2012-02-01

259

Vertical Advection Diffusion and Redox Potentials as Controls on the Distribution of Manganese and Other Trace Metals Dissolved in Waters of the Black Sea  

Microsoft Academic Search

Profiles of dissolved manganese, copper, iron, and zinc show that the distributions of these elements are markedly affected by redox reactions at the boundary between oxygenated surface waters and the sulfide-containing deep waters. Copper and zinc are depleted in the deep water by precipitation as insoluble sulfides. The concentrations of manganese and iron in the deep water greatly exceed those

Derek W. Spencer; Peter G. Brewer

1971-01-01

260

Sources of cadmium in the environment.  

PubMed

This paper is concerned with quantifying the major sources of cadmium in the European Community and assessing the relative significance of such inputs to the environmental compartments, air, land, and water. The methodology involved identification of potential sources of cadmium, including natural processes, as well as those associated with human activities. This was followed by a review of any emission studies of these processes and subsequent estimation of an emission factor for each source. The emission factor was applied to the most recent production or consumption data for the process in question to obtain an estimate of the annual discharge. The steel industry and waste incineration, followed by volcanic action and zinc production, are estimated to account for the largest emissions of atmospheric cadmium in the region. Waste disposal results in the single largest input of cadmium to land; the quantity of cadmium associated with this source is greater than the total from the four other major sources--coal combustion, iron and steel production, phosphate fertilizer manufacture and use, and zinc production. The characterization of cadmium inputs to aquatic systems is incomplete but of the sources considered, the manufacture of cadmium-containing articles accounts for the largest discharge, followed by phosphate fertilizer manufacture and zinc production. PMID:6303746

Hutton, M

1983-02-01

261

High manganese concentrations in rocks at Gale crater, Mars  

NASA Astrophysics Data System (ADS)

surface of Mars has long been considered a relatively oxidizing environment, an idea supported by the abundance of ferric iron phases observed there. However, compared to iron, manganese is sensitive only to high redox potential oxidants, and when concentrated in rocks, it provides a more specific redox indicator of aqueous environments. Observations from the ChemCam instrument on the Curiosity rover indicate abundances of manganese in and on some rock targets that are 1-2 orders of magnitude higher than previously observed on Mars, suggesting the presence of an as-yet unidentified manganese-rich phase. These results show that the Martian surface has at some point in time hosted much more highly oxidizing conditions than has previously been recognized.

Lanza, Nina L.; Fischer, Woodward W.; Wiens, Roger C.; Grotzinger, John; Ollila, Ann M.; Cousin, Agnes; Anderson, Ryan B.; Clark, Benton C.; Gellert, Ralf; Mangold, Nicolas; Maurice, Sylvestre; Le Mouélic, Stéphane; Nachon, Marion; Schmidt, Mariek; Berger, Jeffrey; Clegg, Samuel M.; Forni, Olivier; Hardgrove, Craig; Melikechi, Noureddine; Newsom, Horton E.; Sautter, Violaine

2014-08-01

262

The Experience and Limitations of using Manganese Alkaline Primary Cells in a large Operational AUV  

E-print Network

Cadmium · Nickel Metal Hydride · Silver Zinc · Lithium Ion Primary cells · Manganese Alkaline developments in lithium ion cells that give a significantly better specific energy. Silver Zinc cells were one, with a form displacement of 3.5T, there was considerable scope for increasing the battery payload to enable

Griffiths, Gwyn

263

Manganese and iron in Indian Ocean waters  

SciTech Connect

The first vertical profiles of dissolved Mn and Fe for the (NW) Indian Ocean are reported. The area is characterized by seasonal upwelling and a broad oxygen minimum zone in intermediate waters. The dissolved Fe-profile exhibits a maximum (5.1 nM) in the oxygen minimum zone, with low values both in surface waters (0.3 nM) and deep waters (around 1 nM). Mn concentrations in the surface waters are elevated (2.0-4.3 nM), and decrease rapidly in an offshore direction. Below the first 25 m, concentrations decrease dramatically (0.5-1.3 nM), indicating removal by oxidation and particle scavenging. Further down, various Mn maxima are observed which can be related to hydrographic features. The include the facts that: intermediate water originating from the Red Sea lost its dissolved O{sub 2} while flowing northward along the Omani coast and exhibits a strong Mn maximum (4.6-6.5 nM) coincident with the deep O{sub 2} minimum; at the two inshore stations in the Gulf of Oman this is overlain by relatively modest Mn maxima ({plus minus}2.7 nM) related to Arabian Gulf overflow water; and the strong Mn maxima (4.4-5.6 nM) in the oxygen minimum zone at the two offshore stations are related to yet another watermass. Below these various maxima, concentrations decrease gradually to values as low as 90 pM at 2,000 meters depth. Towards the sea floor concentrations increase again, leading to a modest bottom water maximum (0.7-1.5 nM). The overall vertical distributions of Mn and Fe are strikingly similar, also in actual concentrations, to those previously reported for the eastern equatorial Pacific, an area also characterized by an extensive O{sub 2}-minimum zone.

Saager, P.M.; De Baar, H.J.W. (NWO Laboratorium voor Isotopen Geologie, Amsterdam (Netherlands)); Burkill, P.H. (Plymouth Marine Laboratory (England))

1989-09-01

264

Drinking Water Problems: Iron and Manganese (Spanish)  

E-print Network

E l hierro y el manganeso son dos elementos similares que pueden ser un fastidio para el abastecimiento del agua potable. El hierro es m?s com?n que el manganeso pero frecuente- mente ocurren juntos. No son peligrosos para la salud. ?Qu? problemas... causan el hierro y el manganeso? El hierro y el manganeso pueden darle al agua un sabor, olor y color indeseable. El hierro causa man- chas rojizos-caf?s en la ropa, porcelana, platos, utensilios, vasos, lavaplatos, accesorios de plomer?a y concreto. El...

Dozier, Monty; McFarland, Mark L.

2004-02-20

265

Effect of natural organic materials on cadmium and neptunium sorption  

SciTech Connect

In a batch sorption study of the effect of naturally occurring organic materials on the sorption of cadmium and neptunium on oxides and tuff surfaces, the model sorbents were synthetic goethite, boehmite, amorphous silicon oxides, and a crushed tuff material from Yucca Mountain, Nevada. An amino acid, 3-(3,4-dihydroxypheny)-DL-alanine (DOPA), and an aquatic-originated fulvic material, Nordic aquatic fulvic acid (NAFA), were used as model organic chemicals. Sorption isotherm results showed that DOPA sorption followed the order aluminum oxide > iron oxide > silicon oxide and that the amount of DOAP sorption for a given sorbent increased as the solution pH was raised. The sorption of cadmium and neptunium on the iron oxide was about ten times higher than that on the aluminum oxide. The sorption of cadmium and neptunium on natural tuff material was much lower than that on aluminum and iron oxides. The sorption of cadmium on iron and aluminum oxides was found to be influenced by the presence of DOPA, and increasing the amount of DOPA coating resulted in higher cadmium sorption on aluminum oxide. However, for iron oxide, cadmium sorption decreased with increasing DOPA concentration. The presence of the model organic materials DOPA and NAFA did not affect the sorption of neptunium on tuff material or on the iron and aluminum oxides. Spectroscopic results indicate that cadmium complexes strongly with DOPA. Therefore, the effect of the organic material, DOPA, on the cadmium sorption is readily observed. However, neptunium is possibly complexed weakly with organic material. Thus, DOPA and NAFA have little effect on neptunium sorption on all sorbents selected for study.

Kung, K.S.; Triay, I.R.

1994-10-01

266

Cadmium carcinogenesis in review  

Microsoft Academic Search

Cadmium is an inorganic toxicant of great environmental and occupational concern which was classified as a human carcinogen in 1993. Occupational cadmium exposure is associated with lung cancer in humans. Cadmium exposure has also, on occasion, been linked to human prostate cancer. The epidemiological data linking cadmium and pulmonary cancer are much stronger than for prostatic cancer. Other target sites

Michael P Waalkes

2000-01-01

267

Manganese in dwarf spheroidal galaxies  

E-print Network

We provide manganese abundances (corrected for the effect of the hyperfine structure) for a large number of stars in the dwarf spheroidal galaxies Sculptor and Fornax, and for a smaller number in the Carina and Sextans dSph galaxies. Abundances had already been determined for a number of other elements in these galaxies, including alpha and iron-peak ones, which allowed us to build [Mn/Fe] and [Mn/alpha] versus [Fe/H] diagrams. The Mn abundances imply sub-solar [Mn/Fe] ratios for the stars in all four galaxies examined. In Sculptor, [Mn/Fe] stays roughly constant between [Fe/H]\\sim -1.8 and -1.4 and decreases at higher iron abundance. In Fornax, [Mn/Fe] does not vary in any significant way with [Fe/H]. The relation between [Mn/alpha] and [Fe/H] for the dSph galaxies is clearly systematically offset from that for the Milky Way, which reflects the different star formation histories of the respective galaxies. The [Mn/alpha] behavior can be interpreted as a result of the metal-dependent Mn yields of type II and ...

North, P; Jablonka, P; Hill, V; Shetrone, M; Letarte, B; Lemasle, B; Venn, K A; Battaglia, G; Tolstoy, E; Irwin, M J; Primas, F; Francois, P

2012-01-01

268

Occupational exposure to manganese.  

PubMed Central

The relationship between the degree of exposure and biological effects of manganese was studied in a group of 369 workers employed in the production of ferroalloys. Two other groups of workers, from an electrode plant and from an aluminium rolling mill, served as controls. Mean manganese concentrations at work places where ferroalloys were produced varied from 0-301 to 20-442 mg/m3. The exposure level of the two control groups was from 2 to 30 microgram/m3 and from 0-05 to 0-07 microgram/m3, in the electrode plant and rolling mill respectively. Sixty-two (16-8%) manganese alloy workers showed some signs of neurological impairment. These signs were noticeably less in the two control groups (5-8% and 0%) than in the occupationally exposed group. Subjective symptoms, which are nonspecific but may be symptoms of subclinical manganism, were not markedly different in the three groups. However, in the manganese alloy workers some of the subjective symptoms occurred more frequently in heavier smokers than in light smokers or nonsmokers. Heavier smokers engaged in manganese alloy production showed some of the subjective symptoms more often than heavier smokers from the control groups. PMID:871441

Saric, M; Markicevic, A; Hrustic, O

1977-01-01

269

ARSENIC REMOVAL BY IRON REMOVAL PROCESSES  

EPA Science Inventory

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...

270

Manganese abundances in Galactic bulge red giants  

E-print Network

Manganese is mainly produced in type II SNe during explosive silicon burning, in incomplete Si-burning regions, and depends on several nucleosynthesis environment conditions, such as mass cut beween the matter ejected and falling back onto the remnant, electron and neutron excesses, mixing fallback, and explosion energy. Manganese is also produced in type Ia SNe. The aim of this work is the study of abundances of the iron-peak element Mn in 56 bulge giants, among which 13 are red clump stars. Four bulge fields along the minor axis are inspected. The study of abundances of Mn-over-Fe as a function of metallicity in the Galactic bulge may shed light on its production mechanisms. High-resolution spectra were obtained using the FLAMES+UVES spectrograph on the Very Large Telescope. The spectra were obtained within a program to observe 800 stars using the GIRAFFE spectrograph, together with the present UVES spectra. We aim at identifying the chemical evolution of manganese, as a function of metallicity, in the Gala...

Barbuy, B; Zoccali, M; Minniti, D; Renzini, A; Ortolani, S; Gomez, A; Trevisan, M; Dutra, N

2013-01-01

271

Thermodynamics of the oxygen solutions in manganese-containing Fe-Co melts  

NASA Astrophysics Data System (ADS)

Thermodynamic analysis of the oxygen solutions in manganese-containing Fe-Co melts has been performed. The equilibrium constants of deoxidation reaction of iron-cobalt melts with manganese, the activity coefficients during infinity dilution, and the interaction parameters in various melts are found. During the deoxidation of manganese-containing Fe-Co melts, the oxide phase contains FeO and CoO along with MnO. The compositions of the oxide phase above Fe-Co-Mn-O melts are calculated. When the cobalt and manganese contents in the melts increase, the mole fraction of manganese oxide increases, and it approaches 1 in the case of pure cobalt. The dependences of the oxygen solubility in the melts on the cobalt and manganese contents are calculated. The deoxidizing capacity of manganese increases substantially with increasing cobalt content in the melt. The curves of oxygen solubility in Fe-Co melts have minima, whose values shift toward low manganese content in a melt. The manganese contents are determined at the minimum points in the oxygen solubility curves, and the corresponding minimum oxygen contents are found.

Aleksandrov, A. A.; Dashevskii, V. Ya.

2014-01-01

272

Cadmium and Soil Microorganisms.  

National Technical Information Service (NTIS)

In connection with the questions of how cadmium acts on soil microorganisms and how that action affects cadmium accumulation in the plant, investigations with groups of microorganisms (fungi, bacteria and streptomycetes) and some physiological groups (nit...

I. Gruen

1984-01-01

273

Manganese, Metallogenium, and Martian Microfossils  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

274

Process for removing technetium from iron and other metals  

DOEpatents

A process for removing technetium from iron and other metals comprises the steps of converting the molten, alloyed technetium to a sulfide dissolved in manganese sulfide, and removing the sulfide from the molten metal as a slag. 4 figs.

Leitnaker, J.M.; Trowbridge, L.D.

1999-03-23

275

Metallic solvent extraction of manganese and titanium from ferroalloys  

NASA Astrophysics Data System (ADS)

The selective removal of valuable elements from ferroalloys has been investigated. It has been found that liquid bismuth is a suitable solvent for leaching manganese from its ferroalloy. High recoveries and rapid reaction rates were obtained for low-carbon ferromanganese, but results for the high-carbon ferromanganese and silicomanganese were less favorable due to the lower activity of manganese in these alloys and the lack of wetting by liquid bismuth. Antimony was found to be a suitable solvent for titanium from ferrotitanium but iron was also taken into solution. Manganese was successfully transferred from solution in liquid bismuth to liquid aluminum by fused salt electrorefining, using a NaCl-KCl-MnCl electrolyte, at high current efficiencies with negligible carryover of bismuth.

Godsell, A. J.; Fray, D. J.

1990-04-01

276

Manganese in dwarf spheroidal galaxies  

NASA Astrophysics Data System (ADS)

We provide manganese abundances (corrected for the effect of the hyperfine structure) for a large number of stars in the dwarf spheroidal galaxies Sculptor and Fornax, and for a smaller number in the Carina and Sextans dSph galaxies. Abundances had already been determined for a number of other elements in these galaxies, including ? and iron-peak ones, which allowed us to build [Mn/Fe] and [Mn/?] versus [Fe/H] diagrams. The Mn abundances imply sub-solar [Mn/Fe] ratios for the stars in all four galaxies examined. In Sculptor, [Mn/Fe] stays roughly constant between [Fe/H] ~ -1.8 and -1.4 and decreases at higher iron abundance. In Fornax, [Mn/Fe] does not vary in any significant way with [Fe/H]. The relation between [Mn/?] and [Fe/H] for the dSph galaxies is clearly systematically offset from that for the Milky Way, which reflects the different star formation histories of the respective galaxies. The [Mn/?] behavior can be interpreted as a result of the metal-dependent Mn yields of Type II and Type Ia supernovae. We also computed chemical evolution models for star formation histories matching those determined empirically for Sculptor, Fornax, and Carina, and for the Mn yields of SNe Ia, which were assumed to be either constant or variable with metallicity. The observed [Mn/Fe] versus [Fe/H] relation in Sculptor, Fornax, and Carina can be reproduced only by the chemical evolution models that include a metallicity-dependent Mn yield from the SNe Ia. Based on observations made with the FLAMES-GIRAFFE multi-object spectrograph mounted on the Kuyen VLT telescope at ESO-Paranal Observatory (programs 171.B-0588, 074.B-0415 and 076.B-0146).Appendices are available in electronic form at http://www.aanda.org

North, P.; Cescutti, G.; Jablonka, P.; Hill, V.; Shetrone, M.; Letarte, B.; Lemasle, B.; Venn, K. A.; Battaglia, G.; Tolstoy, E.; Irwin, M. J.; Primas, F.; François, P.

2012-05-01

277

Cadmium sulfide membranes  

DOEpatents

A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

Spanhel, Lubomir (Madison, WI); Anderson, Marc A. (Madison, WI)

1992-07-07

278

Cadmium sulfide membranes  

DOEpatents

A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

Spanhel, Lubomir (Madison, WI); Anderson, Marc A. (Madison, WI)

1991-10-22

279

Bioavailability of cadmium adsorbed on various oxides minerals to wetland plant species Phragmites australis  

Microsoft Academic Search

The bioavailability of heavy metals strongly depends on their speciation in the environment. The effect of different chemical speciations of cadmium ions (i.e. adsorbed on different oxide minerals) on its bioavailability to wetland plant Phragmites australis was studied. Goethite, magnetite, gibbsite, alumina, and manganese oxide were chosen as representatives of metal (hydr)oxides commonly present in sediment. The cultivar system with

He Wang; Yongfeng Jia; Shaofeng Wang; Huijie Zhu; Xing Wu

2009-01-01

280

Journal of Materials Science, Vol. 39, 2004, 39493955. CarbonCarbon Interactions in Iron  

E-print Network

Journal of Materials Science, Vol. 39, 2004, 3949­3955. Carbon­Carbon Interactions in Iron H. K. D interstitial sites in iron so that the configurations of any solid­solution at constant composition depend atoms. INTRODUCTION There are no solutions of iron which are ideal. The iron­manganese liquid phase

Cambridge, University of

281

Manganese and copper in the root plaque of Phragmites australis (cav. ) trin. ex steudel  

Microsoft Academic Search

Manganese and copper were found in the iron oxide plaque on roots of Phragmites australis collected at six sampling sites in southern Quebec and Ontario, Canada. Manganese concentration in the plaque, like that of Fe, is correlated with Mn-bound-to-carbonates fraction of the soil\\/sediment. The Fe:Mn ratio of the plaque resemble the same ratio of Fe:Mn-bound-to-carbonates in the substrate. The ratio

LOUISE ST-CYR; ADELE A. CROWDER

1990-01-01

282

Tissue Manganese Concentrations in Young Male Rhesus Monkeys following Subchronic Manganese Sulfate Inhalation  

Microsoft Academic Search

High-dose human exposure to manganese results in manganese accumulation in the basal ganglia and dopaminergic neuropa- thology. Occupational manganese neurotoxicity is most frequently linked with manganese oxide inhalation; however, exposure to other forms of manganese may lead to higher body burdens. The objective of this study was to determine tissue manganese con- centrations in rhesus monkeys following subchronic (6 h\\/day,

David C. Dorman; Melanie F. Struve; Marianne W. Marshall; Carl U. Parkinson; R. Arden James; Brian A. Wong

2006-01-01

283

Manganese Supplementation Protects Against Diet-Induced Diabetes in Wild Type Mice by Enhancing Insulin Secretion  

PubMed Central

Mitochondrial dysfunction is both a contributing mechanism and complication of diabetes, and oxidative stress contributes to that dysfunction. Mitochondrial manganese-superoxide dismutase (MnSOD) is a metalloenzyme that provides antioxidant protection. We have previously shown in a mouse model of hereditary iron overload that cytosolic iron levels affected mitochondrial manganese availability, MnSOD activity, and insulin secretion. We therefore sought to determine the metallation status of MnSOD in wild-type mice and whether altering that status affected ?-cell function. 129/SvEVTac mice given supplemental manganese exhibited a 73% increase in hepatic MnSOD activity and increased metallation of MnSOD. To determine whether manganese supplementation offered glucose homeostasis under a situation of ?-cell stress, we challenged C57BL/6J mice, which are more susceptible to diet-induced diabetes, with a high-fat diet for 12 weeks. Manganese was supplemented or not for the final 8 weeks on that diet, after which we examined glucose tolerance and the function of isolated islets. Liver mitochondria from manganese-injected C57BL/6J mice had similar increases in MnSOD activity (81%) and metallation as were seen in 129/SvEVTac mice. The manganese-treated group fed high fat had improved glucose tolerance (24% decrease in fasting glucose and 41% decrease in area under the glucose curve), comparable with mice on normal chow and increased serum insulin levels. Isolated islets from the manganese-treated group exhibited improved insulin secretion, decreased lipid peroxidation, and improved mitochondrial function. In conclusion, MnSOD metallation and activity can be augmented with manganese supplementation in normal mice on normal chow, and manganese treatment can increase insulin secretion to improve glucose tolerance under conditions of dietary stress. PMID:23372018

Lee, Soh-Hyun; Jouihan, Hani A.; Cooksey, Robert C.; Jones, Deborah; Kim, Hyung J.; Winge, Dennis R.

2013-01-01

284

Mineralogical and elemental description of pacific manganese nodules  

NASA Astrophysics Data System (ADS)

The report is divided into three sections: morphology, mineralogy and elemental composition. The nodule morphology section defines what is considered a nodule for the study, and details the external characteristics and internal structure. Nodule mineralogy is discussed in three sections: manganese minerals, iron oxide minerals, and accessory minerals. The major manganese minerals discussed are todorokite, birnessite, and vernadite. The iron oxide minerals are less well known and include feroxyhyte, goethite, and lepidocrocite. Accessory minerals present include quartz, clays, and other silicates and nonsilicates. A discussion on moisture content is also included. The elemental composition section presents data on 74 elements occurring as cations or anions. Summary data, histograms, and interelement correlation coefficients are presented.

Haynes, B. W.; Law, S. L.; Barron, D. C.

1983-03-01

285

Cadmium and renal cancer  

SciTech Connect

Background: Rates of renal cancer have increased steadily during the past two decades, and these increases are not explicable solely by advances in imaging modalities. Cadmium, a widespread environmental pollutant, is a carcinogen that accumulates in the kidney cortex and is a cause of end-stage renal disease. Several observations suggest that cadmium may be a cause of renal cancer. Methods: We performed a systematic review of the literature on cadmium and renal cancer using MEDLINE for the years 1966-2003. We reviewed seven epidemiological and eleven clinical studies. Results: Despite different methodologies, three large epidemiologic studies indicate that occupational exposure to cadmium is associated with increased risk renal cancer, with odds ratios varying from 1.2 to 5.0. Six of seven studies that compared the cadmium content of kidneys from patients with kidney cancer to that of patients without kidney cancer found lower concentrations of cadmium in renal cancer tissues. Conclusions: Exposure to cadmium appears to be associated with renal cancer, although this conclusion is tempered by the inability of studies to assess cumulative cadmium exposure from all sources including smoking and diet. The paradoxical findings of lower cadmium content in kidney tissues from patients with renal cancer may be caused by dilution of cadmium in rapidly dividing cells. This and other methodological problems limit the interpretation of studies of cadmium in clinical samples. Whether cadmium is a cause of renal cancer may be answered more definitively by future studies that employ biomarkers of cadmium exposure, such as cadmium levels in blood and urine.

Il'yasova, Dora [Department of Cancer Biology, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157 (United States); Department of Public Health Sciences, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157 (United States); Schwartz, Gary G. [Department of Cancer Biology, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157 (United States) and Department of Public Health Sciences, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157 (United States)]. E-mail: gschwart@wfubmc.edu

2005-09-01

286

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2013-04-01

287

21 CFR 582.5455 - Manganese glycerophosphate.  

...2014-04-01 2014-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2014-04-01

288

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2011-04-01

289

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2010-04-01

290

21 CFR 582.5455 - Manganese glycerophosphate.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Manganese glycerophosphate. 582.5455 Section...or Dietary Supplements 1 § 582.5455 Manganese glycerophosphate. (a) Product. Manganese glycerophosphate. (b) Conditions...

2012-04-01

291

Manganese Accumulates within Golgi Apparatus in Dopaminergic Cells as Revealed by Synchrotron X-ray Fluorescence Nanoimaging  

PubMed Central

Chronic exposure to manganese results in neurological symptoms referred to as manganism and is identified as a risk factor for Parkinson’s disease. In vitro, manganese induces cell death in the dopaminergic cells, but the mechanisms of manganese cytotoxicity are still unexplained. In particular, the subcellular distribution of manganese and its interaction with other trace elements needed to be assessed. Applying synchrotron X-ray fluorescence nanoimaging, we found that manganese was located within the Golgi apparatus of PC12 dopaminergic cells at physiologic concentrations. At increasing concentrations, manganese accumulates within the Golgi apparatus until cytotoxic concentrations are reached resulting in a higher cytoplasmic content probably after the Golgi apparatus storage capacity is exceeded. Cell exposure to manganese and brefeldin A, a molecule known to specifically cause the collapse of the Golgi apparatus, results in the striking intracellular redistribution of manganese, which accumulates in the cytoplasm and the nucleus. These results indicate that the Golgi apparatus plays an important role in the cellular detoxification of manganese. In addition manganese exposure induces a decrease in total iron content, which could contribute to the overall neurotoxicity. PMID:22778823

2009-01-01

292

Hot coal gas desulfurization with manganese based sorbents. Quarterly report, June--September 1994  

SciTech Connect

The focus of work being performed on hot coal gas desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% Al{sub 2}O{sub 3}) appears to be a strong contender to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc; hence, it is not as likely to undergo zinc-depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron; hence, the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Also manganese chlorides are much less stable and volatile than zinc chlorides. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Eighth Quarterly Report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite.

Hepworth, M.T.; Slimane, R.B.

1994-11-01

293

Cadmium - A metallohormone?  

SciTech Connect

Cadmium is a heavy metal that is often referred to as the metal of the 20th century. It is widely used in industry principally in galvanizing and electroplating, in batteries, in electrical conductors, in the manufacture of alloys, pigments, and plastics, and in the stabilization of phosphate fertilizers. As a byproduct of smelters, cadmium is a prevalent environmental contaminant. In the general population, exposure to cadmium occurs primarily through dietary sources, cigarette smoking, and, to a lesser degree, drinking water. Although the metal has no known physiological function, there is evidence to suggest that the cadmium is a potent metallohormone. This review summarizes the increasing evidence that cadmium mimics the function of steroid hormones, addresses our current understanding of the mechanism by which cadmium functions as a hormone, and discusses its potential role in development of the hormone dependent cancers.

Byrne, Celia [Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC (United States); Divekar, Shailaja D.; Storchan, Geoffrey B.; Parodi, Daniela A. [Department of Biochemistry and Molecular and Cellular Biology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC (United States); Martin, Mary Beth [Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC (United States); Department of Biochemistry and Molecular and Cellular Biology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC (United States)], E-mail: martinmb@georgetown.edu

2009-08-01

294

Cadmium - a metallohormone?  

PubMed Central

Cadmium is a heavy metal that is often referred to as the metal of the 20th Century. It is widely used in industry principally in galvanizing and electroplating, in batteries, in electrical conductors, in the manufacture of alloys, pigments, and plastics, and in the stabilization of phosphate fertilizers. As a byproduct of smelters, cadmium is a prevalent environmental contaminant. In the general population, exposure to cadmium occurs primarily through dietary sources, cigarette smoking, and, to a lesser degree, drinking water. Although the metal has no known physiological function, there is evidence to suggest that the cadmium is a potent metallohormone. This review summarizes the increasing evidence that cadmium mimics the function of steroid hormones, addresses our current understanding of the mechanism by which cadmium functions as a hormone, and discusses its potential role in development of the hormone dependent cancers. PMID:19362102

Byrne, Celia; Divekar, Shailaja D.; Storchan, Geoffrey B.; Parodi, Daniela A.; Martin, Mary Beth

2009-01-01

295

Cadmium in tobacco  

SciTech Connect

The present study was conducted to determine the cadmium level in tobacco planted in five main tobacco-producing areas, a cadmium polluted area, and in cigarettes produced domestically (54 brands). The results indicate that average cadmium content in tobacco was 1.48 (0.10-4.95 mg/kg), which was similar to that of Indian tobacco (1.24 mg/kg), but the cadmium of tobacco produced in the cadmium polluted area was quite high (8.60 mg/kg). The average cigarette cadmium was 1.05 micrograms/g (with filter tip) and 1.61 micrograms/g (regular cigarette). Therefore special attention should be paid to the soil used in planting tobacco.

Yue, L. (Institute of Environmental Health Monitoring, Chinese Academy of Preventive Medicine, Beijing (China))

1992-03-01

296

Restoration of cadmium-contaminated paddy soils by washing with ferric chloride: Cd extraction mechanism and bench-scale verification  

Microsoft Academic Search

The ability of FeCl3 to extract Cd from three paddy soils was compared with that of various irons, manganese, and zinc salts to elucidate the extraction mechanism. Manganese, zinc and iron salts (including FeCl3) extracted 4–41%, 8–44% and 24–66% of total Cd, respectively. This difference reflected the pH of the extraction solution, indicating that the primary mechanism of Cd extraction

Tomoyuki Makino; Hiroyuki Takano; Takashi Kamiya; Tadashi Itou; Naoki Sekiya; Makoto Inahara; Yasuhiro Sakurai

2008-01-01

297

Iron and Iron Deficiency  

MedlinePLUS

... other types of foods eaten at the same meal. Foods containing heme iron (meat, poultry, and fish) ... heme iron absorption when eaten at the same meal. Substances (such as polyphenols, phytates, or calcium) that ...

298

Monitoring cadmium exposure  

SciTech Connect

Increased attention has been focused recently on cadmium as an environmental pollutant. Many of cadmium's effects, such as hypertension and liver and kidney damage, are also caused by excessive alcohol and cigarette consumption. Thus, recognition of cadmium as a pollutant has been slow in coming. But recognition has followed quickly upon the heels of recent events: the outbreak in Japan of itai-itai disease, a particularly disabling and painful form of cadmium poisoning; the discovery of the highest airborne concentration of cadmium ever recorded, near a lead recovery plant in London; the determination of up to 1400 ppM cadmium in estuarine sediment near a zinc refining plant in Tasmania, Australia; and the disclosure that residents of Shipham in the UK have about 10 times the normal concentration of cadmium in their bodies. Shipham is built atop the tailings of a former zinc mine that has been closed for decades. Cadmium concentrations in the town's soil are very high, and this is believed to have contaminated local vegetables. PBNA (partial body neutron activation) is the technique for assessing body burdens of this pollutant. PBNA is being used to monitor populations suspected of having been exposed to cadmium.

Not Available

1980-01-01

299

Interaction and accumulation of manganese and cadmium in the manganese accumulator Lupinus albus.  

PubMed

The effects of the interaction between Mn and Cd on the growth of the white lupin (Lupinus albus), uptake of these metals, their accumulation, and effects on heavy metal stress indicators were studied under glasshouse conditions. Plants were grown with and without Mn and/or Cd for 4 weeks. The absence of Mn and Cd led to lipid peroxidation-induced loss of flavonoids and anthocyanins in the roots, reduced the size of the plant canopy, and led to the appearance of proteoid roots. Sensitivity to Cd in white lupin was enhanced by a low Mn supply, despite lower Cd uptake and accumulation (leaf Mn:Cd concentration ratio <3), as evidenced by increased lipid peroxidation in the leaves and strong inhibition of growth. However, when the Mn supply was adequate, the plants showed few symptoms of Cd toxicity, even though Cd uptake and accumulation increased. A Mn:Cd ratio of up to 20 was enough to minimize Cd stress in the leaf, reflecting the plants' relative tolerance to Cd under such conditions. Irrespective of the Mn supply, the increase in antioxidant compounds observed in the roots of Cd-treated plants might act as a protective mechanism by minimizing the oxidative stress caused by Cd exposure. In summary, high leaf Mn concentrations seem to render white lupins more tolerant to Cd stress. PMID:20399531

Zornoza, Pilar; Sánchez-Pardo, Beatriz; Carpena, Ramón O

2010-09-01

300

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.  

PubMed

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 ?g L(-1) for Mn(II) and 0.34-380 ?g L(-1) for Fe(III) ions. The method was successfully applied for the determination of understudied ions in water, food and biological samples. PMID:24411390

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

2014-02-01

301

Influence of welding fume on systemic iron status.  

PubMed

Iron is the major metal found in welding fumes, and although it is an essential trace element, its overload causes toxicity due to Fenton reactions. To avoid oxidative damage, excess iron is bound to ferritin, and as a result, serum ferritin (SF) is a recognized biomarker for iron stores, with high concentrations linked to inflammation and potentially also cancer. However, little is known about iron overload in welders. Within this study, we assessed the iron status and quantitative associations between airborne iron, body iron stores, and iron homeostasis in 192 welders not wearing dust masks. Welders were equipped with personal samplers in order to determine the levels of respirable iron in the breathing zone during a working shift. SF, prohepcidin and other markers of iron status were determined in blood samples collected after shift. The impact of iron exposure and other factors on SF and prohepcidin were estimated using multiple regression models. Our results indicate that respirable iron is a significant predictor of SF and prohepcidin. Concentrations of SF varied according to the welding technique and respiratory protection used, with a median of 103 ?g l-1 in tungsten inert gas welders, 125 ?g l-1 in those wearing air-purifying respirators, and 161 ?g l-1 in other welders. Compared to welders with low iron stores (SF < 25 ?g l-1), those with excess body iron (SF ? 400 ?g l-1) worked under a higher median concentration of airborne iron (60 ?g m(-3) versus 148 ?g m(-3)). Even though air concentrations of respirable iron and manganese were highly correlated, and low iron stores have been reported to increase manganese uptake in the gastrointestinal tract, no correlation was seen between SF and manganese in blood. In conclusion, monitoring SF may be a reasonable method for health surveillance of welders. Respiratory protection with air-purifying respirators can decrease iron exposure and avoid chronically higher SF in welders working with high-emission technologies. PMID:25223225

Casjens, Swaantje; Henry, Jana; Rihs, Hans-Peter; Lehnert, Martin; Raulf-Heimsoth, Monika; Welge, Peter; Lotz, Anne; Gelder, Rainer Van; Hahn, Jens-Uwe; Stiegler, Hugo; Eisele, Lewin; Weiss, Tobias; Hartwig, Andrea; Brüning, Thomas; Pesch, Beate

2014-11-01

302

Oral cadmium in mice carrying 5 versus 2 copies of the Slc39a8 gene: comparison of uptake, distribution, metal content, and toxicity.  

PubMed

The highly conserved human and mouse SLC39A8 gene encodes the divalent cation/bicarbonate symporter ZIP8 expressed ubiquitously in most cell types. Our bacterial artificial chromosome-transgenic BTZIP8-3 line has 3 additional copies of the Slc39a8 gene in addition to its constitutive diploid pair found in wild-type (WT) mice. In liver, kidney, lung, testis, gastrointestinal tract, and brain, BTZIP8-3 mice are known to express ?2.5 times greater amounts of ZIP8, compared with WT mice. Herein we administered cadmium chloride (CdCl2) in drinking water (100 mg/L through week 2, 200 mg/L through week 4, 400 mg/L through week 8, 800 mg/L through week 12, and 1600 mg/L through week 20, when the experiment was concluded). We postulated that Cd uptake and distribution--and, therefore, toxicity in certain tissues--would be enhanced in BTZIP8-3, compared with WT mice. BTZIP8-3 and WT groups ingested comparable amounts of Cd. Compared with WT, BTZIP8-3 mice showed tissue specific: increases in Cd, zinc, and manganese content and decreases in calcium content. Both Cd-exposed BTZIP8-3 and WT were similar in lower urinary pH; increased plasma alanine and aspartate aminotransferase activities; elevated iron and copper content in liver, kidney, lung, and testis; and higher blood urea nitrogen and kidney weight. Histological changes in liver, kidney, lung, and testis were minimal. In summary, at the daily oral Cd exposures chosen for this study, 5 versus 2 Slc39a8 gene copies result in no differences in Cd toxicity but do cause differences in tissue-specific content of Cd, zinc, manganese, calcium, iron, and copper. PMID:24345748

Schneider, Scott N; Liu, Zhiwei; Wang, Bin; Miller, Marian L; Afton, Scott E; Soleimani, Manoocher; Nebert, Daniel W

2014-01-01

303

The Iron Within  

NSDL National Science Digital Library

Forty-fifth monthly installment of our "What A Year!" website project, introducing life science breakthroughs to middle and high school students and their teachers. In order to cause infection, pathogenic bacteria must be able to obtain all the nutrients they need from the human body, including metals such as zinc, iron, and manganese. As a result, many vertebrate species (including humans) have evolved ways to store these metals in forms that are not readily accessible to bacteria. This mechanism is known as nutritional immunity. Staphylococcus aureus has developed such a mechanism, making it a very successful invader.

2011-02-01

304

Np and Pu Sorption to Manganese Oxide Minerals  

SciTech Connect

Manganese oxide minerals are a significant component of the fracture lining mineralogy at Yucca Mountain (Carlos et al., 1993) and within the tuff-confining unit at Yucca Flat (Prothro, 1998), Pahute Mesa (Drellack et al., 1997), and other locations at the Nevada Test Site (NTS). Radionuclide sorption to manganese oxide minerals was not included in recent Lawrence Livermore National Laboratory (LLNL) hydrologic source term (HST) models which attempt to predict the migration behavior of radionuclides away from underground nuclear tests. However, experiments performed for the Yucca Mountain Program suggest that these minerals may control much of the retardation of certain radionuclides, particularly Np and Pu (Triay et al., 1991; Duff et al., 1999). As a result, recent HST model results may significantly overpredict radionuclide transport away from underground nuclear tests. The sorption model used in HST calculations performed at LLNL includes sorption to iron oxide, calcite, zeolite, smectite, and mica minerals (Zavarin and Bruton 2004a; 2004b). For the majority of radiologic source term (RST) radionuclides, we believe that this accounts for the dominant sorption processes controlling transport. However, for the case of Np, sorption is rather weak to all but the iron and manganese oxides (Figure 1). Thus, we can expect to significantly reduce predicted Np transport by accounting for Np sorption to manganese oxides. Similarly, Pu has been shown to be predominantly associated with manganese oxides in Yucca Mountain fractured tuffs (Duff et al., 1999). Recent results on colloid-facilitated Pu transport (Kersting and Reimus, 2003) also suggest that manganese oxide coatings on fracture surfaces may compete with colloids for Pu, thus reducing the effects of colloid-facilitated Pu transport (Figure 1b). The available data suggest that it is important to incorporate Np and Pu sorption to manganese oxides in reactive transport models. However, few data are available for inclusion in our model. A survey of published data found only single-point (Triay et al., 1991; Kersting and Reimus, 2003; Keeney-Kennicutt and Morse, 1984; 1985) and qualitative (Duff et al., 1999; Dyer et al., 2000a; 2000b) Np and Pu sorption information. This report describes recent experiments that quantified the sorption and desorption of Np(V) and Pu(IV) onto three manganese oxide minerals as a function of pH and time. The three manganese oxides (pyrolusite, birnessite, and hollandite) have all been observed on fracture surfaces at Yucca Mountain and are likely to predominate at the NTS. Pyrolusite, birnessite, and hollandite comprise both a range of manganese oxide structure (framework, layered, and tunnel, respectively) and composition and a range of observed manganese oxide mineralogies. The pH range of 3-10 used in these experiments covers the range of pH observed in NTS groundwater (Rose et al., 1997).

Zhao, P; Johnson, M R; Roberts, S K; Zavarin, M

2005-08-30

305

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Manganese heterocyclic tetraamine complex (generic). ...Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic). ...identified generically as manganese heterocyclic tetraamine complex (PMNs...

2010-07-01

306

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Manganese heterocyclic tetraamine complex (generic). ...Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic). ...identified generically as manganese heterocyclic tetraamine complex (PMNs...

2011-07-01

307

February 22, 2001 1 "Iron-Out": A nutritional program for geraniums and other crops prone to iron  

E-print Network

................................................................. 2 A.3 Understand the conditions (low pH and high fertilizer concentration with sensitive cultivars of necrotic spots and marginal burn, the affected leaves do not completely heal, and the only option iron/ manganese toxicity (and low pH) from occurring. The Iron-Out program is based on pre

New Hampshire, University of

308

Tellurium content of marine manganese oxides and other manganese oxides  

USGS Publications Warehouse

Tellurium in amounts ranging from 5 to 125 parts per million was present in all of 12 samples of manganese oxide nodules from the floor of the Pacific and Indian oceans. These samples represent the first recognized points of high tellurium concentration in a sedimentary cycle. The analyses may lend support to the theory that the minor-element content of seafloor manganese nodules is derived from volcanic emanations.

Lakin, H. W.; Thompson, C. E.; Davidson, D. F.

1963-01-01

309

Bioaccumulation of manganese and its toxicity in feral pigeons (Columba livia) exposed to manganese oxide dust (Mn{sub 3}O{sub 4})  

SciTech Connect

Manganese tetroxide (Mn{sub 3}O{sub 4}) is a product from the combustion of methylcyclopentadienyl manganese tricarbonyl. Exposure to high levels of manganese can lead to serious health effects especially to the central nervous and respiratory systems. Very few studies on the effects of long-term low level exposure to Mn{sub 3}O{sub 4} have been reported. The present study was therefore conducted to examine the bioaccumulation and toxicity of manganese in various organs of feral pigeons (Columba kivia) when exposed to low levels of Mn{sub 3}O{sub 4} via inhalation and hence to find any possible relationship between these two parameters. A total of 22 pigeons was exposed to 239 {micro}g/m{sup 3} of manganese for 7 h/day, 5 days/week for 5, 9, and 13 consecutive weeks. Manganese concentrations in various tissues, e.g., brain (mesencephalon), lung, liver, intestine, pancreas, kidney, muscle, bone, and whole blood, were measured by neutron activation analysis. Various biochemical parameters in blood, e.g., hematocrit, total proteins, glucose, uric acid, alinine aminotransferase, total iron, blood urea nitrogen and triglycerides, were also measured.

Sierra, P.; Chakrabarti, S.; Tounkara, R.; Loranger, S.; Kennedy, G.; Zayed, J. [Univ. of Montreal (Canada)] [Univ. of Montreal (Canada)

1998-11-01

310

Amino acid sequence of the small cadmium-binding protein (MP II) from Nereis diversicolor (annelida, polychaeta). Evidence for a myohemerythrin structure.  

PubMed

The primary sequence of the low-molecular-mass cadmium-binding protein metalloprotein II of Nereis diversicolor (Hediste diversicolor, recent denomination) has been determined. This protein is composed of 119 amino acids and has 80.8% identity with the N. diversicolor myohemerythrin [Takagi, T. & Cox, J. A. (1991) FEBS Lett. 285, 25-27]. The fact that iron, which normally binds to myohemerythrin, is not found to be associated with the cadmium-binding protein metalloprotein II in cadmium-exposed animals could be the result of the complete abolition of the iron-binding capacity of the protein due to the binding of cadmium. PMID:8223553

Demuynck, S; Li, K W; Van der Schors, R; Dhainaut-Courtois, N

1993-10-01

311

Characterization of cadmium uptake in Lactobacillus plantarum and isolation of cadmium and manganese uptake mutants  

SciTech Connect

Two different Cd{sup 2+} uptake systems were identified in Lactobacillus plantarum. One is a high-affinity, high-velocity Mn{sup 2+} uptake system which also takes up Cd{sup 2+} and is induced by Mn{sup 2+} starvation. The calculated K{sub m} and V{sub max} are 0.26 {mu}M and 3.6 {mu}mol g of dry cell{sup {minus}1} min{sup {minus}1}, respectively. Unlike Mn{sup 2+} uptake, which is facilitated by citrate and related tricarboxylic acids, Cd{sup 2+} uptake is weakly inhibited by citrate. Cd{sup 2+} and Mn{sup 2+} are competitive inhibitors of each other, and the affinity of the system for Cd{sup 2+} is higher than that for Mn{sup 2+}. The other Cd{sup 2+} uptake system is expressed in Mn{sup 2+}-sufficient cells, and no K{sub m} can be calculated for it because uptake is nonsaturable. Mn{sup 2+} does not compete for transport through this system, nor does any other tested cation, i.e., Zn{sup 2+}, Cu{sup 2+}, Co{sup 2+}, Mg{sup 2+}, Ca{sup 2+}, Fe{sup 2+}, or Ni{sup 2+}. Both systems require energy, since uncouplers completely inhibit their activities. Two Mn{sup 2+}-dependent L. plantarum mutants were isolated by chemical mutagenesis and ampicillin enrichment. They required more than 5,000 times as much Mn{sup 2+} for growth as the parental strain. Mn{sup 2+} starvation-induced Cd{sup 2+} uptake in both mutants was less than 5% the wild-type rate. The low level of long-term Mn{sup 2+} or Cd{sup 2+} accumulation by the mutant strains also shows that the mutations eliminate the high-affinity Mn{sup 2+} and Cd{sup 2+} uptake system.

Hao, Z.; Reiske, H.R.; Wilson, D.B.

1999-11-01

312

Manganese oxidation model for rivers  

USGS Publications Warehouse

The presence of manganese in natural waters (>0.05 mg/L) degrades water-supply quality. A model was devised to predict the variation of manganese concentrations in river water released from an impoundment with the distance downstream. The model is one-dimensional and was calibrated using dissolved oxygen, biochemical oxygen demand, pH, manganese, and hydraulic data collected in the Duck River, Tennessee. The results indicated that the model can predict manganese levels under various conditions. The model was then applied to the Chattahoochee River, Georgia. Discrepancies between observed and predicted may be due to inadequate pH data, precipitation of sediment particles, unsteady flow conditions in the Chattahoochee River, inaccurate rate expressions for the low pH conditions, or their combinations.

Hess, Glen W.; Kim, Byung R.; Roberts, Philip J.W.

1989-01-01

313

FATE OF METHYLCYCLOPENTADIENYL MANGANESE TRICARBONYL  

EPA Science Inventory

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been proposed as an octane booster for unleaded gasoline; such use could result in ecological and human exposure through surface water and ground water ecosystems. o evaluate the environmental risks from MMT, its environmenta...

314

Action of manganese on puberty  

E-print Network

Manganese (Mn) is considered important for normal growth and reproduction. Because Mn can cross the blood brain barrier and accumulate in the hypothalamus, and because it has been suggested that infants and children are potentially more sensitive...

Lee, Bo Yeon

2007-09-17

315

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

USGS Publications Warehouse

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, 0.08 percent of phosphorus, 1.1 percent of barium, and minute quantities of copper, lead, and zinc. Although the manganese content of the sandstone and clay ore may change abruptly from bed to bed, the content within any individual bed changes gradually, and for any large volume of ore both the nanganese and iron content are remarkably uniform. Explorations to June 1941 consisted chiefly of 49 holes diamond-drilled in the upper zone on the Artillery Mountains side of the area. The district is estimated to contain an assured minimum of 200,000,000 tons of material having an average manganese content of 3 to 4 percent. About 20,000,000 tons of this total contains 5 percent or more of manganese, and 2,000,000 to 3,000,000 tons contains 10 percent or more. To what extent these deposits can be utilized is a metallurgical and economic problem. Although the clay and sandstone ores, as well as the 'hard' ore, are present in large tonnages, the 'hard' ore is the only kind that combines minable tonnage with promising grade. About 15,000,000 tons of 'hard' ore is present; about 500,000 tons of this contains 15 percent or more of manganese and averages 17 percent, and somewhat over 2,000,000 tons contains 10 percent or more and averages nearly 13 percent. Except for closer drilling to determine such things as the tonnage, grade, spacing, and form of the richer shoots with greater accuracy before beginning to mine them, further explorations are not recommended, for any new ore found is likely to be similar, both in grade and kind, to that already discovered.

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

1944-01-01

316

Extraction with long-chain amines--VI. Separation of manganese as Mn(CNS)4-(6) complex and its complexometric determination in calcareous material.  

PubMed

Manganese is quantitatively extracted into a benzene solution of trioctylmethyl-ammonium chloride from a solution at least 0.25M in potassium thiocyanate and at pH 2.5-7. After stripping into dilute ammonia containing triethanolamine (TEA) and hydroxylamine hydrochloride, manganese is determined by EDTA titration. Calcium and magnesium are not extracted even in traces. Iron is co-extracted with manganese and is masked with TEA during the stripping. Aluminium also does not interfere. In the aqueous phase, after the extraction of manganese, calcium or magnesium can be determined by the usual EDTA titration. The method described permits highly selective individual determination of manganese and calcium and/or magnesium in all materials rich in manganese. PMID:18961238

Pribil, R; Adam, J

1973-01-01

317

Hot coal gas desulfurization with manganese-based sorbents. Annual report, September 1992--September 1993  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E. T. Turkdogan indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Annual Topical Report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/ alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite. It includes the prior Quarterly Technical Reports which indicate that the manganese carbonate material, being of higher purity than the manganese ore, has a higher degree of sulfur capacity and more rapid absorption kinetics. A 2-inch fixed-bed reactor has been fabricated and is now ready for subjecting pellets to cyclic loading and regeneration.

Hepworth, M.T.

1993-12-01

318

Cadmium migration in aerospace nickel cadmium cells  

Microsoft Academic Search

The effects of temperature, the nature of separator material, charge and discharge, carbonate contamination, and the mode of storage are studied with respect to the migration of active material from the negative toward the positive plate. A theoretical model is proposed which takes into account the solubility of cadmium in various concentrations of hydroxide and carbonate at different temperatures, the

P. P. McDermott

1976-01-01

319

Effects of Iron Status on Transpulmonary Transport and Tissue Distribution of Mn and Fe  

PubMed Central

Manganese transport into the blood can result from inhaling metal-containing particles. Intestinal manganese and iron absorption is mediated by divalent metal transporter 1 (DMT1) and is upregulated in iron deficiency. Since iron status alters absorption of Fe and Mn in the gut, we tested the hypothesis that iron status may alter pulmonary transport of these metals. DMT1 expression in the lungs was evaluated to explore its role in metal transport. The pharmacokinetics of intratracheally instilled 54Mn or 59Fe in repeatedly bled or iron oxide–exposed rats were compared with controls. Iron oxide exposure caused a reduction in pulmonary transport of 54Mn and 59Fe, and decreased uptake in other major organs. Low iron status from repeated bleeding also reduced pulmonary transport of iron but not of manganese. However, uptake of manganese in the brain and of iron in the spleen increased in bled rats. DMT1 transcripts were detected in airway epithelium, alveolar macrophages, and bronchial-associated lymphoid tissue in all rats. Focal increases were seen in particle-containing macrophages and adjacent epithelial cells, but no change was observed in bled rats. Although lung DMT1 expression did not correlate with iron status, differences in pharmacokinetics of instilled metals suggest that their potential toxicity can be modified by iron status. PMID:16340001

Brain, Joseph D.; Heilig, Elizabeth; Donaghey, Thomas C.; Knutson, Mitchell D.; Wessling-Resnick, Marianne; Molina, Ramon M.

2006-01-01

320

Olfactory ferric and ferrous iron absorption in iron-deficient rats  

PubMed Central

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

Ruvin Kumara, V. M.

2012-01-01

321

Mineral commodity profiles: Cadmium  

USGS Publications Warehouse

Overview -- Cadmium is a soft, low-melting-point metal that has many uses. It is similar in abundance to antimony and bismuth and is the 63d element in order of crustal abundance. Cadmium is associated in nature with zinc (and, less closely, with lead and copper) and is extracted mainly as a byproduct of the mining and processing of zinc. In 2000, it was refined in 27 countries, of which the 8 largest accounted for two-thirds of world production. The United States was the third largest refiner after Japan and China. World production in 2000 was 19,700 metric tons (t) and U.S. production was 1,890 t. In the United States, one company in Illinois and another in Tennessee refined primary cadmium. A Pennsylvania company recovered cadmium from scrap, mainly spent nickel-cadmium (NiCd) batteries. The supply of cadmium in the world and in the United States appears to be adequate to meet future industrial needs; the United States has about 23 percent of the world reserve base.

Butterman, W. C.; Plachy, Jozef

2004-01-01

322

Manganese metallurgy review. Part II: Manganese separation and recovery from solution  

Microsoft Academic Search

Various methods for manganese separation and recovery from solution are reviewed, which are potentially applicable to leach solutions of secondary manganese sources, particularly nickel laterite waste effluents. The main methods include solvent extraction, sulfide precipitation, ion exchange, hydroxide precipitation and oxidative precipitation. These methods are briefly compared and assessed for both purification of manganese solutions and recovery of manganese from

Wensheng Zhang; Chu Yong Cheng

2007-01-01

323

Manganese-spinel catalysts in CO/H/sub 2/ olefin synthesis  

SciTech Connect

A process is described for synthesizing a hydrocarbon mixture containing C/sub 2/-C/sub 6/ olefins comprising the step of contacting a catalyst composition comprised of an unsupported iron-manganese spinel. The spinel exhibits a single spinel phase, being isostructural with Fe/sub 3/O/sub 4/ as determined by X-ray diffractometry, and possessing an iron-manganese atomic ratio of 2:1 to 19:1. The spinel is surface impregnated or deposited with a potassium salt, the atomic ratio of iron/potassium being about 20:1 to 200:1, with a mixture of CO/hydrogen under process conditions of pressure, space velocity (SHSV) and elevated temperature for time sufficient to produce the C/sub 2/-C/sub 6/ olefins.

Soled, S.L.; Fiato, R.A.

1987-06-02

324

Manganese: brain transport and emerging research needs.  

PubMed

Idiopathic Parkinson's disease (IPD) represents a common neurodegenerative disorder. An estimated 2% of the U.S. population, age 65 and older, develops IPD. The number of IPD patients will certainly increase over the next several decades as the baby-boomers gradually step into this high-risk age group, concomitant with the increase in the average life expectancy. While many studies have suggested that industrial chemicals and pesticides may underlie IPD, its etiology remains elusive. Among the toxic metals, the relationship between manganese intoxication and IPD has long been recognized. The neurological signs of manganism have received close attention because they resemble several clinical disorders collectively described as extrapyramidal motor system dysfunction, and in particular, IPD and dystonia. However, distinct dissimilarities between IPD and manganism are well established, and it remains to be determined whether Mn plays an etiologic role in IPD. It is particularly noteworthy that as a result of a recent court decision, methylcyclopentadienyl Mn tricarbonyl (MMT) is presently available in the United States and Canada for use in fuel, replacing lead as an antiknock additive. The impact of potential long-term exposure to low levels of MMT combustion products that may be present in emissions from automobiles has yet to be fully evaluated. Nevertheless, it should be pointed out that recent studies with various environmental modeling approaches in the Montreal metropolitan (where MMT has been used for more than 10 years) suggest that airborne Mn levels were quite similar to those in areas where MMT was not used. These studies also show that Mn is emitted from the tail pipe of motor vehicles primarily as a mixture of manganese phosphate and manganese sulfate. This brief review characterizes the Mn speciation in the blood and the transport kinetics of Mn into the central nervous system, a critical step in the accumulation of Mn within the brain, outlines the potential susceptibility of selected populations (e.g., iron-deficient) to Mn exposure, and addresses future research needs for Mn. PMID:10852840

Aschner, M

2000-06-01

325

Manganese abundances in Galactic bulge red giants  

NASA Astrophysics Data System (ADS)

Context. Manganese is mainly produced in type II SNe during explosive silicon burning, in incomplete Si-burning regions, and depends on several nucleosynthesis environment conditions, such as mass cut between the matter ejected and falling back onto the remnant, electron and neutron excesses, mixing fallback, and explosion energy. Manganese is also produced in type Ia SNe. Aims: The aim of this work is the study of abundances of the iron-peak element Mn in 56 bulge giants, among which 13 are red clump stars. Four bulge fields along the minor axis are inspected. The study of abundances of Mn-over-Fe as a function of metallicity in the Galactic bulge may shed light on its production mechanisms. Methods: High-resolution spectra were obtained using the FLAMES+UVES spectrograph on the Very Large Telescope. The spectra were obtained within a program to observe 800 stars using the GIRAFFE spectrograph, together with the present UVES spectra. Results: We aim at identifying the chemical evolution of manganese, as a function of metallicity, in the Galactic bulge. We find [Mn/Fe] ~ -0.7 at [Fe/H] ~ -1.3, increasing to a solar value at metallicities close to solar, and showing a spread around - 0.7 ? [Fe/H] ? -0.2, in good agreement with other work on Mn in bulge stars. There is also good agreement with chemical evolution models. We find no clear difference in the behaviour of the four bulge fields. Whereas [Mn/Fe] vs. [Fe/H] could be identified with the behaviour of the thick disc stars, [Mn/O] vs. [O/H] has a behaviour running parallel, at higher metallicities, compared to thick disc stars, indicating that the bulge enrichment might have proceeded differently from that of the thick disc. Observations collected at the European Southern Observatory, Paranal, Chile (ESO programmes 71.B-0617A, 73.B0074A, and GTO 71.B-0196).Tables 1-6 and Figs. 1-6 are available in electronic form at http://www.aanda.org

Barbuy, B.; Hill, V.; Zoccali, M.; Minniti, D.; Renzini, A.; Ortolani, S.; Gómez, A.; Trevisan, M.; Dutra, N.

2013-11-01

326

Nickel-cadmium battery recycling through the INMETCOR high temperature metals recovery process  

Microsoft Academic Search

INMETCO, a subsidiary of Inco Limited, is the only facility in North America that provides the high temperature metals recovery (HTMR) process for nickel-cadmium secondary batteries. In 1993, INMETCO recycled more than 2,200 tons of nickel-cadmium, nickel-iron and nickel metal hydride batteries. The paper describes Inco's experience in metals recovery, traces the development and explains operation of the HTMR Process

J. J. Liotta; J. C. Onuska; R. H. Hanewald

1995-01-01

327

Cadmium migration in aerospace nickel cadmium cells  

NASA Technical Reports Server (NTRS)

The effects of temperature, the nature of separator material, charge and discharge, carbonate contamination, and the mode of storage are studied with respect to the migration of active material from the negative toward the positive plate. A theoretical model is proposed which takes into account the solubility of cadmium in various concentrations of hydroxide and carbonate at different temperatures, the generation of the cadmiate ion, Cd(OH)3(-), during discharge, the migration of the cadmiate ion and particulate Cd(OH)2 due to electrophoretic effects and the movement of electrolyte in and out of the negative plate and, finally, the recrystallization of cadmiate ion in the separator as Cd(OH)2. Application of the theoretical model to observations of cadmium migration in cycled cells is also discussed.

Mcdermott, P. P.

1976-01-01

328

STRAIN AGING OF AUSTENITIC HADFIELD MANGANESE STEEL  

E-print Network

STRAIN AGING OF AUSTENITIC HADFIELD MANGANESE STEEL W. S. OWEN1 { and M. GRUJICIC2 1 Department. INTRODUCTION Had®eld manganese steel, here represented by the nominal composition Fe±12Mn±1.2C wt%, is a stable. Noting that manganese decreases the activity of carbon in austenite, they speculated that the relatively

Grujicic, Mica

329

Manganese-enhanced MRI of rat brain based on slow cerebral delivery of manganese(II) with silica-encapsulated Mn x Fe(1-x) O nanoparticles.  

PubMed

In this work, we report a monodisperse bifunctional nanoparticle system, MIO@SiO2 -RITC, as an MRI contrast agent [core, manganese iron oxide (MIO); shell, amorphous silica conjugated with rhodamine B isothiocyanate (RITC)]. It was prepared by thermal decomposition and modified microemulsion methods. The nanoparticles with varying iron to manganese ratios displayed different saturated magnetizations and relaxivities. In vivo MRI of rats injected intravenously with MIO@SiO2-RITC nanoparticles exhibited enhancement of the T1 contrast in brain tissue, in particular a time-delayed enhancement in the hippocampus, pituitary gland, striatum and cerebellum. This is attributable to the gradual degradation of MIO@SiO2-RITC nanoparticles in the liver, resulting in the slow release of manganese(II) [Mn(II)] into the blood pool and, subsequently, accumulation in the brain tissue. Thus, T1-weighted contrast enhancement was clearly detected in the anatomic structure of the brain as time progressed. In addition, T2*-weighted images of the liver showed a gradual darkening effect. Here, we demonstrate the concept of the slow release of Mn(II) for neuroimaging. This new nanoparticle-based manganese contrast agent allows one simple intravenous injection (rather than multiple infusions) of Mn(II) precursor, and results in delineation of the detailed anatomic neuroarchitecture in MRI; hence, this provides the advantage of the long-term study of neural function. PMID:23526743

Chen, Wei; Lu, Fang; Chen, Chiao-Chi V; Mo, Kuan-Chi; Hung, Yann; Guo, Zhi-Xuan; Lin, Chia-Hui; Lin, Ming-Huang; Lin, Yu-Hsuan; Chang, Chen; Mou, Chung-Yuan

2013-09-01

330

Factors influencing intestinal cadmium uptake in pregnant Bangladeshi women--a prospective cohort study.  

PubMed

Experimental studies indicate that zinc (Zn) and calcium (Ca) status, in addition to iron (Fe) status, affect gastrointestinal absorption of cadmium (Cd), an environmental pollutant that is toxic to kidneys, bone and endocrine systems. The aim of this study was to evaluate how various nutritional factors influence the uptake of Cd in women, particularly during pregnancy. The study was carried out in a rural area of Bangladesh, where malnutrition is prevalent and exposure to Cd via food appears elevated. The uptake of Cd was evaluated by associations between erythrocyte Cd concentrations (Ery-Cd), a marker of ongoing Cd exposure, and concentrations of nutritional markers. Blood samples, collected in early pregnancy and 6 months postpartum, were analyzed by inductively coupled plasma mass spectrometry (ICPMS). Ery-Cd varied considerably (range: 0.31-5.4microg/kg) with a median of 1.1microg/kg (approximately 0.5microg/L in whole blood) in early pregnancy. Ery-Cd was associated with erythrocyte manganese (Ery-Mn; positively), plasma ferritin (p-Ft; negatively), and erythrocyte Ca (Ery-Ca; negatively) in decreasing order, indicating common transporters for Cd, Fe and Mn. There was no evidence of Cd uptake via Zn transporters, but the association between Ery-Cd and p-Ft seemed to be dependent on adequate Zn status. On average, Ery-Cd increased significantly by 0.2microg/kg from early pregnancy to 6 months postpartum, apparently due to up-regulated divalent metal transporter 1 (DMT1). In conclusion, intestinal uptake of Cd appears to be influenced either directly or indirectly by several micronutrients, in particular Fe, Mn and Zn. The negative association with Ca may suggest that Cd inhibits the transport of Ca to blood. PMID:19646688

Kippler, M; Goessler, W; Nermell, B; Ekström, E C; Lönnerdal, B; El Arifeen, S; Vahter, M

2009-10-01

331

Factors influencing intestinal cadmium uptake in pregnant Bangladeshi women-A prospective cohort study  

SciTech Connect

Experimental studies indicate that zinc (Zn) and calcium (Ca) status, in addition to iron (Fe) status, affect gastrointestinal absorption of cadmium (Cd), an environmental pollutant that is toxic to kidneys, bone and endocrine systems. The aim of this study was to evaluate how various nutritional factors influence the uptake of Cd in women, particularly during pregnancy. The study was carried out in a rural area of Bangladesh, where malnutrition is prevalent and exposure to Cd via food appears elevated. The uptake of Cd was evaluated by associations between erythrocyte Cd concentrations (Ery-Cd), a marker of ongoing Cd exposure, and concentrations of nutritional markers. Blood samples, collected in early pregnancy and 6 months postpartum, were analyzed by inductively coupled plasma mass spectrometry (ICPMS). Ery-Cd varied considerably (range: 0.31-5.4 {mu}g/kg) with a median of 1.1 {mu}g/kg (approximately 0.5 {mu}g/L in whole blood) in early pregnancy. Ery-Cd was associated with erythrocyte manganese (Ery-Mn; positively), plasma ferritin (p-Ft; negatively), and erythrocyte Ca (Ery-Ca; negatively) in decreasing order, indicating common transporters for Cd, Fe and Mn. There was no evidence of Cd uptake via Zn transporters, but the association between Ery-Cd and p-Ft seemed to be dependent on adequate Zn status. On average, Ery-Cd increased significantly by 0.2 {mu}g/kg from early pregnancy to 6 months postpartum, apparently due to up-regulated divalent metal transporter 1 (DMT1). In conclusion, intestinal uptake of Cd appears to be influenced either directly or indirectly by several micronutrients, in particular Fe, Mn and Zn. The negative association with Ca may suggest that Cd inhibits the transport of Ca to blood.

Kippler, M. [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm (Sweden)] [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm (Sweden); Goessler, W. [Institut fuer Chemie-Analytische Chemie, Karl-Franzens-Universitaet, Universitaetsplatz 1, 8010 Graz (Austria)] [Institut fuer Chemie-Analytische Chemie, Karl-Franzens-Universitaet, Universitaetsplatz 1, 8010 Graz (Austria); Nermell, B. [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm (Sweden)] [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm (Sweden); Ekstroem, E.C. [Department of Women's and Children's Health, International Maternal and Child Health, Uppsala University, SE-751 85 Uppsala (Sweden)] [Department of Women's and Children's Health, International Maternal and Child Health, Uppsala University, SE-751 85 Uppsala (Sweden); Loennerdal, B. [Department of Nutrition, University of California, Davis, CA 95616 (United States)] [Department of Nutrition, University of California, Davis, CA 95616 (United States); El Arifeen, S. [International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), GPO Box 128, Dhaka 100 (Bangladesh)] [International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), GPO Box 128, Dhaka 100 (Bangladesh); Vahter, M., E-mail: Marie.Vahter@ki.se [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm (Sweden)

2009-10-15

332

New layered manganese oxide halides.  

PubMed

The first layered manganese(III) oxide chlorides, Sr2MnO3Cl and Sr4Mn3O8-yCl2, have been synthesised; Sr2MnO3Cl adopts a K2NiF4 type structure with sheets of MnO5 square based pyramids linked through oxygen and separated by SrCl layers; it is the end member of a new family of Ruddlesden-Popper type manganese oxide halides which includes the three-layer member Sr4Mn3O8-yCl2 also reported herein. PMID:12120392

Knee, Christopher S; Weller, Mark T

2002-02-01

333

Ferric Iron Reduction by Acidophilic Heterotrophic Bacteria  

PubMed Central

Fifty mesophilic and five moderately thermophilic strains of acidophilic heterotrophic bacteria were tested for the ability to reduce ferric iron in liquid and solid media under aerobic conditions; about 40% of the mesophiles (but none of the moderate thermophiles) displayed at least some capacity to reduce iron. Both rates and extents of ferric iron reduction were highly strain dependent. No acidophilic heterotroph reduced nitrate or sulfate, and (limited) reduction of manganese(IV) was noted in only one strain (Acidiphilium facilis), an acidophile which did not reduce iron. Insoluble forms of ferric iron, both amorphous and crystalline, were reduced, as well as soluble iron. There was evidence that, in at least some acidophilic heterotrophs, iron reduction was enzymically mediated and that ferric iron could act as a terminal electron acceptor. In anaerobically incubated cultures, bacterial biomass increased with increasing concentrations of ferric but not ferrous iron. Mixed cultures of Thiobacillus ferrooxidans or Leptospirillum ferrooxidans and an acidophilic heterotroph (SJH) produced sequences of iron cycling in ferrous iron-glucose media. PMID:16348395

Johnson, D. Barrie; McGinness, Stephen

1991-01-01

334

Ionization Ability of Manganese Nanoparticles  

NASA Astrophysics Data System (ADS)

Manganese oxide nanoparticles (Mn-O NPs) were prepared through our novel method as reagents for laser desorption/ionization mass spectrometry (LDI-MS). Through the control of the reaction time in the chemical preparation method (0.5, 1, and 5 h), we succeeded in preparing three different types of manganese oxide particles. The particles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and DC magnetization measurements. These characterization results indicated that the manganese ions oxidized in aqueous alkaline solution, and that the spinel structure was retained for the Mn3O4 phase, which then gradually changed into the MnO2 phase. The mass spectra of substance P (MW = 1347.6) were measured by MALDI-TOF mass spectrometry with Mn-O NPs. The Mn-O NPs that reacted with 3-aminopropyltriethoxysilane(?-APTES) for 1 h or 5 h had higher ionization abilities than those reacted for 0.5 h. These different abilities are attributed to the different crystal structures of the prepared manganese oxides.

Hiroki, Tomoyuki; Shigeoka, Daiki; Kimura, Shinji; Mashino, Toshiyuki; Taira, Shu; Ichiyanagi, Yuko

2011-05-01

335

Manganese and chronic hepatic encephalopathy  

Microsoft Academic Search

SummaryClinical observations and animal studies have raised the hypothesis that increased concentrations of manganese (Mn) in whole blood might lead to accumulation of this metal within the basal ganglia in patients with end-stage liver disease. We studied ten patients with liver failure (and ten controls) by magnetic resonance imaging (MRI) and measurement of Mn in brain tissue of three patients

D Krieger; S Krieger; L Theilmann; O Jansen; P Gass; H Lichtnecker

1995-01-01

336

Mineral of the month: cadmium  

USGS Publications Warehouse

Cadmium, which was once used almost exclusively for pigments, now has many diverse applications. Cadmium’s low melting point, excellent electrical conductivity and resistance to corrosion make it valuable for many products including batteries, electroplated coatings, stabilizers for plastics, solar cells and nonferrous alloys. Today’s cadmium is primarily used in rechargeable batteries, accounting for about 78 percent of consumption in 2004. In 2000, an estimated 3.5 billion consumer batteries were sold in the United States, of which almost 10 percent were nickel-cadmium batteries.

Klimasauskas, Edward

2005-01-01

337

The origin of high cadmium loads in some bivalve molluscs from Shark Bay, Western Australia: a new mechanism for cadmium uptake by filter feeding organisms.  

PubMed

Although Shark Bay is remote from all known industrial and geological sources of heavy metals, the cadmium content of several species of Shark Bay molluscs may exceed 10 mg/kg. The cadmium load in these molluscs varies geographically within the bay, but possible explanations for cadmium distribution involving variation in salinity, saline groundwater influx, the dissolved cadmium concentration, the cadmium concentration in substrate sediments, species, or an anthropogenic source are not supported by analytical data. The cadmium concentration is normal in Shark Bay seawater (0.04 microgram/L to about 0.35 microgram/L), rarely exceeds 0.25 microgram/L in ground waters, bore waters, and salt lake brines, and very seldom exceeds 1 mg/kg in sediments. No direct link between the cadmium loads in molluscs and its concentration in the water or substrate sediment is evident, but the cadmium load in molluscs is usually highest where turbulence is high and the substrate sediment contains fine hematite. Over about 2,000 km2, the water depth in Shark Bay is less than 1 m and fine sediment is readily suspended by strong winds. The iron-oxides (superfine hematite) are eroded from the Peron Sandstone exposed in some coastal cliffs and constitute up to 2% of substrate sediments near these cliffs. This study reveals that cadmium in the water adsorbs extremely efficiently onto the surface of the hematite, which is negatively charged at the prevailing seawater pH of 8.15, and that suspended hematite particles are ingested by the molluscs. Inside the molluscs, lower pH conditions cause reversal of the hematite charge and the cadmium is released and accumulated by the organism.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1958082

McConchie, D M; Lawrance, L M

1991-08-01

338

Process for removing and detoxifying cadmium from scrap metal including mixed waste  

SciTech Connect

Cadmium-bearing scrap from nuclear applications, such as neutron shielding and reactor control and safety rods, must usually be handled as mixed waste since it is radioactive and the cadmium in it is both leachable and highly toxic. Removing the cadmium from this scrap, and converting it to a nonleachable and minimally radioactive form, would greatly simplify disposal or recycling. A process now under development will do this by shredding the scrap; leaching it with reagents which selectively dissolve out the cadmium; reprecipitating the cadmium as its highly insoluble sulfide; then fusing the sulfide into a glassy matrix to bring its leachability below EPA limits before disposal. Alternatively, the cadmium may be recovered for reuse. A particular advantage of the process is that all reagents (except the glass frit) can easily be recovered and reused in a nearly closed cycle, minimizing the risk of radioactive release. The process does not harm common metals such as aluminum, iron and stainless steel, and is also applicable to non-nuclear cadmium-bearing scrap such as nickel-cadmium batteries.

Kronberg, J.W.

1994-07-01

339

Structural basis for the metal-selective activation of the manganese transport regulator of Bacillus subtilis.  

PubMed

The manganese transport regulator (MntR) of Bacillus subtilis is activated by Mn(2+) to repress transcription of genes encoding transporters involved in the uptake of manganese. MntR is also strongly activated by cadmium, both in vivo and in vitro, but it is poorly activated by other metal cations, including calcium and zinc. The previously published MntR.Mn(2+) structure revealed a binuclear complex of manganese ions with a metal-metal separation of 3.3 A (herein designated the AB conformer). Analysis of four additional crystal forms of MntR.Mn(2+) reveals that the AB conformer is only observed in monoclinic crystals at 100 K, suggesting that this conformation may be stabilized by crystal packing forces. In contrast, monoclinic crystals analyzed at room temperature (at either pH 6.5 or pH 8.5), and a second hexagonal crystal form (analyzed at 100 K), all reveal the shift of one manganese ion by 2.5 A, thereby leading to a newly identified conformation (the AC conformer) with an internuclear distance of 4.4 A. Significantly, the cadmium and calcium complexes of MntR also contain binuclear complexes with a 4.4 A internuclear separation. In contrast, the zinc complex of MntR contains only one metal ion per subunit, in the A site. Isothermal titration calorimetry confirms the stoichiometry of Mn(2+), Cd(2+), and Zn(2+) binding to MntR. We propose that the specificity of MntR activation is tied to productive binding of metal ions at two sites; the A site appears to act as a selectivity filter, determining whether the B or C site will be occupied and thereby fully activate MntR. PMID:16533030

Kliegman, Joseph I; Griner, Sarah L; Helmann, John D; Brennan, Richard G; Glasfeld, Arthur

2006-03-21

340

Chemical and microbiological studies of sulfide?mediated manganese reduction  

Microsoft Academic Search

Laboratory studies of manganese reduction by naturally occurring reduced inorganic compounds were undertaken, both to study further possible in situ mechanisms of manganese reduction and to examine how manganese redox reactions might be coupled to other biogeochemical processes. Chemical manganese reduction by sulfide (in the presence of excess manganese oxide) was found to be rapid and complete, with all sulfide

David J. Burdige; Kenneth H. Nealson

1986-01-01

341

Inhibition of premixed methane flames by manganese and tin compounds † † Official contribution of NIST, not subject to copyright in the United States  

Microsoft Academic Search

The first experimental measurements of the influence of manganese- and tin-containing compounds (MMT, TMT) on the burning velocity of methane\\/air flames are presented. Comparisons with Fe(CO)5 and CF3Br demonstrate that manganese and tin-containing compounds are effective inhibitors. The inhibition efficiency of MMT is about a factor of two less than that of iron pentacarbonyl, and that of TMT is about

GREGORY T. LINTERIS; VADIM D. KNYAZEV; VALERI I. BABUSHOK

2002-01-01

342

Nanocrystalline lithium–manganese oxide spinels for Li-ion batteries — Sol-gel synthesis and characterization of their structure and selected physical properties  

Microsoft Academic Search

Nanocrystalline lithium–manganese oxide spinels were synthesized by a modified sol-gel method. Simple salts of lithium, manganese and iron were used as starting reagents and citric acid as a complexing agent. The gelled materials turned into nanopowders after the calcination was carried out in air in the 450–700°C temperature range. The combined DSC-TGA measurements have shown important stages of the syntheses.

M. Michalska; L. Lipi?ska; M. Mirkowska; M. Aksienionek; R. Diduszko; M. Wasiucionek

2011-01-01

343

Effect of heat treatment on the physico-chemical properties and catalytic activity of manganese nodules leached residue towards decomposition of hydrogen peroxide  

Microsoft Academic Search

The effect of calcination temperature on the physico-chemical characterization of manganese nodule leached residue (MNLR) and water-washed manganese nodule leached residue (WMNLR) has been investigated on the basis of chemical analysis, XRD, TG-DTA, FTIR, surface hydroxyl groups, surface oxygen, reducing and oxidizing sites, surface area. XRD and IR confirm the presence of amorphous iron oxyhydroxides, ?-MnO2, which are converted to

K. M. Parida; S. S. Dash; S. Mallik; J. Das

2005-01-01

344

Alteration at translational but not transcriptional level of transferrin receptor expression following manganese exposure at the blood-CSF barrier in vitro  

SciTech Connect

Manganese exposure alters iron homeostasis in blood and cerebrospinal fluid (CSF), possibly by acting on iron transport mechanisms localized at the blood-brain barrier and/or blood-CSF barrier. This study was designed to test the hypothesis that manganese exposure may change the binding affinity of iron regulatory proteins (IRPs) to mRNAs encoding transferrin receptor (TfR), thereby influencing iron transport at the blood-CSF barrier. A primary culture of choroidal epithelial cells was adapted to grow on a permeable membrane sandwiched between two culture chambers to mimic blood-CSF barrier. Trace {sup 59}Fe was used to determine the transepithelial transport of iron. Following manganese treatment (100 {mu}M for 24 h), the initial flux rate constant (K {sub i}) of iron was increased by 34%, whereas the storage of iron in cells was reduced by 58%, as compared to controls. A gel shift assay demonstrated that manganese exposure increased the binding of IRP1 and IRP2 to the stem loop-containing mRNAs. Consequently, the cellular concentrations of TfR proteins were increased by 84% in comparison to controls. Assays utilizing RT-PCR, quantitative real-time reverse transcriptase-PCR, and nuclear run off techniques showed that manganese treatment did not affect the level of heterogeneous nuclear RNA (hnRNA) encoding TfR, nor did it affect the level of nascent TfR mRNA. However, manganese exposure resulted in a significantly increased level of TfR mRNA and reduced levels of ferritin mRNA. Taken together, these results suggest that manganese exposure increases iron transport at the blood-CSF barrier; the effect is likely due to manganese action on translational events relevant to the production of TfR, but not due to its action on transcriptional, gene expression of TfR. The disrupted protein-TfR mRNA interaction in the choroidal epithelial cells may explain the toxicity of manganese at the blood-CSF barrier.

Li, G. Jane [School of Health Sciences, Purdue University, 550 Stadium Mall Drive, Room 1163D, West Lafayette, IN 47907 (United States); Zhao Qiuqu [School of Health Sciences, Purdue University, 550 Stadium Mall Drive, Room 1163D, West Lafayette, IN 47907 (United States); Zheng Wei [School of Health Sciences, Purdue University, 550 Stadium Mall Drive, Room 1163D, West Lafayette, IN 47907 (United States)]. E-mail: wzheng@purdue.edu

2005-06-01

345

Cadmium plating replacements  

SciTech Connect

The Boeing Company has been searching for replacements to cadmium plate. Two alloy plating systems seem close to meeting the needs of a cadmium replacement. The two alloys, zinc-nickel and tin-zinc are from alloy plating baths; both baths are neutral pH. The alloys meet the requirements for salt fog corrosion resistance, and both alloys excel as a paint base. Currently, tests are being performed on standard fasteners to compare zinc-nickel and tin-zinc on threaded hardware where cadmium is heavily used. The Hydrogen embrittlement propensity of the zinc-nickel bath has been tested, and just beginning for the tin-zinc bath. Another area of interest is the electrical properties on aluminum for tin-zinc and will be discussed. The zinc-nickel alloy plating bath is in production in Boeing Commercial Airplane Group for non-critical low strength steels. The outlook is promising that these two coatings will help The Boeing Company significantly reduce its dependence on cadmium plating.

Nelson, M.J.; Groshart, E.C.

1995-03-01

346

Cadmium plating replacements  

NASA Technical Reports Server (NTRS)

The Boeing Company has been searching for replacements to cadmium plate. Two alloy plating systems seem close to meeting the needs of a cadmium replacement. The two alloys, zinc-nickel and tin-zinc are from alloy plating baths; both baths are neutral pH. The alloys meet the requirements for salt fog corrosion resistance, and both alloys excel as a paint base. Currently, tests are being performed on standard fasteners to compare zinc-nickel and tin-zinc on threaded hardware where cadmium is heavily used. The Hydrogen embrittlement propensity of the zinc-nickel bath has been tested, and just beginning for the tin-zinc bath. Another area of interest is the electrical properties on aluminum for tin-zinc and will be discussed. The zinc-nickel alloy plating bath is in production in Boeing Commercial Airplane Group for non-critical low strength steels. The outlook is promising that these two coatings will help The Boeing Company significantly reduce its dependence on cadmium plating.

Nelson, Mary J.; Groshart, Earl C.

1995-01-01

347

Bio-inspired iron catalysts for degradation of aromatic pollutants and alkane hydroxylation  

Microsoft Academic Search

Today, more and more metalloenzymes are understood at the molecular level. The accumulated knowledge is a very rich source of inspiration for chemists to prepare new catalysts with iron, manganese or copper, which could be cheaper and lead to processes more friendily with environment. We report here two examples. First, the preparation and study with Elf of iron catalysts efficient

Nathalie Raffard; Véronique Balland; Jalila Simaan; Sylvie Létard; Martine Nierlich; Keiji Miki; Frédéric Banse; Elodie Anxolabéhère-Mallart; Jean-Jacques Girerd

2002-01-01

348

Trace elements in spinach ( Spinacia oleracea ) cultivated in soil fortified with graded levels of iron  

Microsoft Academic Search

Trace elements in two varieties of spinach cultivated in soil with different levels of added iron were determined. Addition of iron to soil decreased potassium, sodium and magnesium contents in spinach markedly (pp>0.05). Differential behaviour of spinach varieties was found in the zinc, manganese and sodium contents.

N. S. Reddy; T. N. Khan; V. G. Malewar; K. B. Dudde

1995-01-01

349

The possibility using converter slag; a by-product of steel factory, as an iron fertilizer  

Microsoft Academic Search

This study investigates the effect of converter slag- a by-product of steel industry- as an iron fertilizer on Fe and pH of some calcareous soils. Slag used contained approximately 24% of iron oxides plus a relatively large amount of calcium, silicon, phosphorus, and manganese. An incubation study was conducted with 3 calcareous soils for up to 2 months and the

A. Mohammadi Torkashvand; Islamic Azad

2010-01-01

350

Neurotoxicity of manganese oxide nanomaterials  

Microsoft Academic Search

Manganese (Mn) toxicity in humans has been observed as manganism, a disease that resembles Parkinson’s disease. The mechanism\\u000a of Mn toxicity and the chemical forms that may be responsible for its neurotoxicity are not well understood. We examined the\\u000a toxicity of Mn oxide nanomaterials in a neuronal precursor cell model, using the MTS assay to evaluate mitochondrial function\\u000a in living

Diana M. Stefanescu; Ali Khoshnan; Paul H. Patterson; Janet G. Hering

2009-01-01

351

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Cobalt lithium manganese nickel oxide. 721.10201...Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical...chemical substance identified as cobalt lithium manganese nickel oxide (PMN...

2013-07-01

352

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Cobalt lithium manganese nickel oxide. 721.10201...Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical...chemical substance identified as cobalt lithium manganese nickel oxide (PMN...

2012-07-01

353

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2013-07-01

354

40 CFR 721.10011 - Barium calcium manganese strontium oxide.  

...2014-07-01 false Barium calcium manganese strontium oxide. 721.10011 Section...Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance...substance identified as barium calcium manganese strontium oxide (PMN...

2014-07-01

355

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2012-07-01

356

40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).  

...2014-07-01 2014-07-01 false Manganese heterocyclic tetraamine complex (generic...Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic...chemical substances identified generically as manganese heterocyclic tetraamine...

2014-07-01

357

40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.  

...2014-07-01 false Cobalt lithium manganese nickel oxide. 721.10201 Section...Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance...substance identified as cobalt lithium manganese nickel oxide (PMN...

2014-07-01

358

Heterogeneous clay-manganese(II) oxidation catalyst  

Microsoft Academic Search

A manganese(II)-Schiff base complex has been heterogenized by its intercalation into clay minerals. The incorporation of the homogeneous manganese(II) complexes in the interlayer space of aluminosilicate mineral is accomplished by a cation exchange process. The obtained clay-manganese(II) composite has been studied by chemical analysis, X-ray diffraction and FT-IR spectroscopy. The new catalytic material has been evaluated as oxidation catalyst. Our

D Gournis; M Louloudi; M. A Karakassides; C Kolokytha; K Mitopoulou; N Hadjiliadis

2002-01-01

359

Comment on “Methylcyclopentadienyl Manganese Tricarbonyl as an Antiknock: Composition and Fate of Manganese Exhaust Products”  

Microsoft Academic Search

In an article published in the August 1975, Journal of the Air Pollution Control Association entitled “Methylcyclopentadienyl Manganese Tricarbonyl as an Antiknock: Composition and Pate of Manganese Exhaust Products,” the authors conclude that, “… use of MMT in gasoline will result in no public health hazards, because of the low toxicity of manganese and because of the very low concentration

Edward J. Calabrese; Alfred Sorensen

1975-01-01

360

Influence of Dietary Manganese on the Pharmacokinetics of Inhaled Manganese Sulfate in Male CD Rats  

Microsoft Academic Search

Concerns exist as to whether individuals with relative manga- nese deficiency or excess may be at increased risk for manganese toxicity following inhalation exposure. The objective of this study was to determine whether manganese body burden influences the pharmacokinetics of inhaled manganese sulfate (MnSO4). Postna- tal day (PND) 10 rats were placed on either a low (2 ppm), sufficient (10

David C. Dorman; Melanie F. Struve; R. Arden James; Brian E. McManus; Marianne W. Marshall; Brian A. Wong

2001-01-01

361

Bacterial Manganese Reduction and Growth with Manganese Oxide as the Sole Electron Acceptor  

Microsoft Academic Search

Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium, Alteromonas putrefaciens MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest

Charles R. Myers; Kenneth H. Nealson

1988-01-01

362

Manganese inhibition of microbial iron reduction in anaerobic sediments  

USGS Publications Warehouse

Potential mechanisms for the lack of Fe(II) accumulation in Mn(IV)-containing anaerobic sediments were investigated. The addition of Mn(IV) to sediments in which Fe(II) reduction was the terminal electron-accepting process removed all the pore-water Fe(II), completely inhibited net Fe(III) reduction, and stimulated Mn(IV) reduction. Results demonstrate that preferential reduction of Mn(IV) by FE(III)-reducing bacteria cannot completely explain the lack of Fe(II) accumulation in anaerobic, Mn(IV)-containing sediments, and indicate that Mn(IV) oxidation of Fe(II) is the mechanism that ultimately prevents Fe(II) accumulation. -Authors

Lovley, D. R.; Phillips, E. J. P.

1988-01-01

363

Microbial reduction of manganese oxides - Interactions with iron and sulfur  

NASA Technical Reports Server (NTRS)

Alteromonas putrefaciens (strain MR-1) is capable of rapid Mn(IV) reduction under conditions of neutral pH and temperatures characteristic of the Oneida Lake, New York, sediments from which it was isolated. MR-1 also reduces Fe(3+) to Fe(2+), and disproportionates thiosulfate to sulfide and sulfite; independently, the Fe(2+) and sulfide act as rapid reductants of Mn. The addition of Fe(3+) or thiosulfate to cultures of MR-1 in the presence of oxidized Mn increases the rate and the extent of Mn reduction relative to that observed in the absence of Fe(3+) or thiosulfate. Furthermore, when Fe(3+) and Mn oxides are present conjointly, Fe(2+) does not appear until the reduction of the oxidized Mn is complete. These results demonstrate that the observed rates of Fe(2+) and sulfide production may underestimate the total rates of Fe and sulfate reduction in those environments containing oxidized Mn. These results also demonstrate the potential impact that a single microbe can exert on sediment geochemistry, and provide the basis for preliminary models of the complexity of microbial and geochemical interactions that occur.

Myers, Charles R.; Nealson, Kenneth H.

1988-01-01

364

Microbial reduction of manganese oxides: Interactions with iron and sulfur  

Microsoft Academic Search

Alteromonas putrefaciens (strain MR-1) is capable of rapid Mn(IV) reduction under conditions of neutral pH and temperatures characteristic of the Oneida Lake, New York, sediments from which it was isolated. MR-1 also reduces Fe{sup 3+} to Fe{sup 2+}, and disproportionates thiosulfate to sulfide and sulfite; independently, the Fe{sup 2+} and sulfide act as rapid reductants of Mn. The addition of

C. R. Myers; K. H. Nealson

1988-01-01

365

Manganese and Iron Interactions in Cave and Rock Varnish Communities  

NASA Astrophysics Data System (ADS)

Microbial communities in arid land caves and surface desert environments interact with Fe and Mn, yielding deposits of intimately associated Fe- and Mn-oxides as a result. Although the geological setting and fundamental rock makeup may be similar in some cases, the environments of these two types of communities differ radically. The manner in which the organisms interact with the rock environment may reflect these differences in the resulting minerals, although the biological oxidation mechanisms of Mn and Fe may be similar. We are mapping the Mn and Fe deposition patterns in the mineral coatings in relation to the concentrations of organic carbon indicative of microbial presence, identifying minerals that are biogenic, along with isolating the perpetrators responsible and reproducing relevant minerals in the laboratory. We are also uncovering the underlying biodiversity as revealed by molecular phylogenetic techniques. The ultimate goal is to determine the degree of microbial responsibility for the secondary mineral deposits observed and the potential role of these communities in both dissolution of subsurface bedrock and deposition of surface oxide coatings. Synchrotron XRF and XRD data reveal differences in the mineralogy of the coatings. Lithiophorite is the predominate crystalline Mn-mineral in cave samples, although crystal size is small. TEM analyses show that the Mn-oxides range from amorphous or microcrystalline to exhibiting coherent crystalline lattices. XRF mapping indicates that Ni, Cu, Zn, As and Pb are associated with the Mn-oxides. In the desert surface oxide samples birnessite predominates the crystalline minerals. X-ray maps show a laminated structure with a complex and variable chemistry, including variability in trace elements such as Ni and Pb. DNA extraction of rock varnish samples, followed by the construction of clone libraries from community DNA, demonstrated the apparent predominance of cyanobacteria in rock varnish communities. The clone library sequences also revealed the presence of actinobacteria, chloroflexi, Alphaproteobacteria, and environmental isolates whose closest relatives were found in Hawaiian volcanic soils, thermal soils, and uranium wastes. Cultured isolates from both environments produce amorphous oxides followed by an array of minerals that undergo increasing crystallization over time (months to years) with live cultures but which cease when cultures are killed.

Boston, P. J.; Spilde, M. N.; Northup, D. E.; Mullen, K.; Bargar, J.; Carey, R.

2004-12-01

366

Manganese inhibition of microbial iron reduction in anaerobic sediments  

Microsoft Academic Search

Potential mechanisms for the lack of Fe(II) accumulation in Mn(IV)?con?taining anaerobic sediments were investigated. The addition of Mn(IV) to sediments in which Fe(III) reduction was the terminal electron?accepting process removed all the pore?water Fe(II), completely inhibited net Fe(III) reduction, and stimulated Mn(IV) reduction. In a solution buffered at pH 7, Mn(IV) oxidized Fe(II) to amorphic Fe(III) oxide. Mn(IV) naturally present

Derek R. Lovley; Elizabeth J. P. Phillips

1988-01-01

367

Al-Fe-Mn (Aluminum-Iron-Manganese)  

SciTech Connect

[88Ray] reviewed the experimental data on this system. The reviewed results were presented as: (1) liquidus and solidus projections for Fe-rich alloys and for compositions near the Al-corner; and (2) partial isothermal sections at 1200, 1000, 760, and 600{degrees}C.

Raghavan, V.

1994-08-01

368

Boron, zinc, iron, and manganese content in four grassland species  

SciTech Connect

A post experiment was carried out to test the response of the B, Zn, Fe, and Mn concentration in four wild herbaceous species exposed to three landfill leachate treatments of increasing concentration of contaminants. The species tested were clustered clover (Trifolium glomeratum L.), cotton clover (T. tomentosum L.) wall barley (Hordeum murinum L.), and soft brome (Bromus hordaceus L.). The legume species accumulated more Fe and B than the grasses. The least contaminated leachate (leachate A) significantly increased the Fe and Ma content in T glomeratum. Leachate B significantly increased the Zn content in both clover species and Fe content in T. glomeratum and H. murinum, while it significantly decreased the B content in T. glomeratum. The most contaminated leachate (leachate C) significantly increased the Zn content in T. glomeratum, while it significantly decreased the B and Fe content. In the four species the content of B, Fe, and Mn in the plants under the leachate treatments was in a normal values range, while in T. glomeratum and H. murinum the Zn content had in some cases a toxic level. The dry weight of the four species tested diminished significantly under the most contaminated leachate. The ANOVA confirmed a major significant influence of the species factor on the response of the plant to leachate supply, but the treatment factor also had significant F-values in some cases. The species tested have a potential revegetation value for some areas degraded by landfill leachates.

Adarve, M.J.; Hernandez, A.J. [Univ. de Alcala de Henares, Madrid (Spain); Gil, A.; Pastor, J. [CSIC, Madrid (Spain). Environmental Sciences Research Center

1998-11-01

369

Boron, zinc, iron, and manganese content in four grassland species  

Microsoft Academic Search

A post experiment was carried out to test the response of the B, Zn, Fe, and Mn concentration in four wild herbaceous species exposed to three landfill leachate treatments of increasing concentration of contaminants. The species tested were clustered clover (Trifolium glomeratum L.), cotton clover (T. tomentosum L.) wall barley (Hordeum murinum L.), and soft brome (Bromus hordaceus L.). The

M. J. Adarve; A. J. Hernandez; A. Gil; J. Pastor

1998-01-01

370

Role of manganese: Are welders at risk?.  

E-print Network

??Serious concerns exist among welders and occupational health investigators on the possible association between exposure to manganese via welding fumes and neurological effects. One suggestion… (more)

Nawrocki, R.P.

2012-01-01

371

The Single Superoxide Dismutase of Rhodobacter capsulatus Is a Cambialistic, Manganese-Containing Enzyme  

PubMed Central

The phototrophic bacterium Rhodobacter capsulatus contains a single, oxygen-responsive superoxide dismutase (SODRc) homologous to iron-containing superoxide dismutase enzymes. Recombinant SODRc, however, displayed higher activity after refolding with Mn2+, especially when the pH of the assay mixture was raised. SODRc isolated from Rhodobacter cells also preferentially contains manganese, but metal discrimination depends on the culture conditions, with iron fractions increasing from 7% in aerobic cultures up to 40% in photosynthetic cultures. Therefore, SODRc behaves as a Mn-containing dismutase with cambialistic properties. PMID:12730184

Tabares, Leandro C.; Bittel, Cristian; Carrillo, Néstor; Bortolotti, Ana; Cortez, Néstor

2003-01-01

372

Iron overdose  

MedlinePLUS

Iron is an ingredient in many mineral and vitamin supplements. Iron supplements are also sold by themselves. Types include: Ferrous sulfate (Feosol, Slow Fe) Ferrous gluconate (Fergon) Ferrous fumarate (Femiron, Feostat) Note: This list may not be all-inclusive.

373

Manganese(III) binding to a pyoverdine siderophore produced by a manganese(II)-oxidizing bacterium  

NASA Astrophysics Data System (ADS)

The possible roles of siderophores (high affinity chelators of iron(III)) in the biogeochemistry of manganese remain unknown. Here we investigate the interaction of Mn(III) with a pyoverdine-type siderophore (PVD MnB1) produced by the model Mn(II)-oxidizing bacterium Pseudomonas putida strain MnB1. PVD MnB1 confirmed typical pyoverdine behavior with respect to: (a) its absorption spectrum at 350-600 nm, both in the absence and presence of Fe(III), (b) the quenching of its fluorescence by Fe(III), (c) the formation of a 1:1 complex with Fe(III), and (d) the thermodynamic stability constant of its Fe(III) complex. The Mn(III) complex of PVD MnB1 had a 1:1 Mn:pvd molar ratio, showed fluorescence quenching, and exhibited a light absorption spectrum (A max = 408-410 nm) different from that of either PVD MnB1-Fe(III) or uncomplexed PVD MnB1. Mn(III) competed strongly with Fe(III) for binding by PVD MnB1 in culture filtrates (pH 8, 4°C). Equilibration with citrate, a metal-binding ligand, did not detectably release Mn from its PVD MnB1 complex at a citrate/PVD MnB1 molar ratio of 830 (pH 8, 4°C), whereas pyrophosphate under the same conditions removed 55% of the Mn from its PVD MnB1 complex. Most of the PVD MnB1-complexed Mn was released by reaction with ascorbate, a reducing agent, or with EDTA, a ligand that is also oxidized by Mn(III). Data on the competition for binding to PVD MnB1 by Fe(III) vs. Mn(III) were used to determine a thermodynamic stability constant (nominally at 4°C) for the neutral species MnHPVD MnB1 (log K = 47.5 ± 0.5, infinite dilution reference state). This value was larger than that determined for FeHPVD MnB1 (log K = 44.6 ± 0.5). This result has important implications for the metabolism, solubility, speciation, and redox cycling of manganese, as well as for the biologic uptake of iron.

Parker, Dorothy L.; Sposito, Garrison; Tebo, Bradley M.

2004-12-01

374

REGULAR ARTICLE Interaction of nickel and manganese in accumulation  

E-print Network

REGULAR ARTICLE Interaction of nickel and manganese in accumulation and localization in leaves . Hyperaccumulator. Manganese localization . Nickel localization . Phytoremediation . trichomes Introduction More

Sparks, Donald L.

375

Current status of cadmium as an environmental health problem  

SciTech Connect

Cadmium is a toxic metal occurring in the environment naturally and as a pollutant emanating from industrial and agricultural sources. Food is the main source of cadmium intake in the non-smoking population. The bioavailability, retention and toxicity are affected by several factors including nutritional status such as low iron status. Cadmium is efficiently retained in the kidney (half-time 10-30 years) and the concentration is proportional to that in urine (U-Cd). Cadmium is nephrotoxic, initially causing kidney tubular damage. Cadmium can also cause bone damage, either via a direct effect on bone tissue or indirectly as a result of renal dysfunction. After prolonged and/or high exposure the tubular injury may progress to glomerular damage with decreased glomerular filtration rate, and eventually to renal failure. Furthermore, recent data also suggest increased cancer risks and increased mortality in environmentally exposed populations. Dose-response assessment using a variety of early markers of kidney damage has identified U-Cd points of departure for early kidney effects between 0.5 and 3 {mu}g Cd/g creatinine, similar to the points of departure for effects on bone. It can be anticipated that a considerable proportion of the non-smoking adult population has urinary cadmium concentrations of 0.5 {mu}g/g creatinine or higher in non-exposed areas. For smokers this proportion is considerably higher. This implies no margin of safety between the point of departure and the exposure levels in the general population. Therefore, measures should be put in place to reduce exposure to a minimum, and the tolerably daily intake should be set in accordance with recent findings.

Jaerup, Lars [Department of Epidemiology and Public Health, Imperial College London (United Kingdom); Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden)], E-mail: l.jarup@imperial.ac.uk; Akesson, Agneta [Institute of Environmental Medicine, Karolinska Institutet, Stockholm (Sweden)

2009-08-01

376

Survey of cadmium emission sources  

SciTech Connect

This document presents technical data used to support decision making on the need for listing cadmium under Section 108(a)(1), Section 112(b)(1)(A), or Section 111(b)(1)(A) as required by Section 122 of the Clean Air Act, as amended in 1977. Data are presented describing potential sources of cadmium emissions, control techniques used for cadmium emission control, estimated controlled and uncontrolled cadmium emissions, estimated ambient air quality, and compliance status. The results of special dispersion modeling are presented for incineration, interaction of smelters, and for interaction of sources in the New York City - New Jersey area.

Not Available

1981-09-01

377

Eat Iron?!!  

NSDL National Science Digital Library

To gain an understanding of mixtures and the concept of separation of mixtures, students use strong magnets to find the element of iron in iron-fortified breakfast cereal flakes. Through this activity, they see how the iron component of this heterogeneous mixture (cereal) retains its properties and can thus be separated by physical means.

NSF GK-12 and Research Experience for Teachers (RET) Programs,

378

Essential elements, cadmium, and lead in raw and pasteurized cow and goat milk  

Microsoft Academic Search

Fifteen essential elements plus cadmium and lead were determined in raw and pasteurized cow and goat milks by atomic absorption spectrophotometry. When results were compared on a wet weight basis, there were no significant differences between the raw and pasteurized milks except for cobalt, iron, and lead in goat milk. When copper in goat milk was expressed on a dry

Anthony Lopez; W. F. Collins; H. L. Williams

1985-01-01

379

High copper concentrations in squid livers in association with elevated levels of silver, cadmium, and zinc  

Microsoft Academic Search

Livers from 43 Loligo opalescens, 14 Ommastrephes bartrami, and 7 Symplectoteuthis oualaniensis were analyzed for their silver, cadmium, copper, zinc and iron contents. Copper concentrations of up to 15,000 µg\\/g dry weight were found in L. opalescens in conjunction with significant correlations between this element and Ag, Cd and Zn. The latter elements are known to affect Cu metabolism in

J. H. Martin; A. R. Flegal

1975-01-01

380

Use of Iron and Manganese-Oxidizing Bacteria for the Combined Removal of Iron, Manganese and Arsenic from Contaminated Groundwater  

Microsoft Academic Search

The problem of groundwater contamination with arsenic has been under extensive discussion, especially in recent years, because of its adverse effects on human health and its widespread presence in groundwater throughout the world. Large drinking water plants in developed countries normally find alternative and arsenic-free water resources, or they apply con- ventional arsenic removal methods, such as coagulation\\/filtration, activated alumina

Ioannis A. Katsoyiannis; Anastasios I. Zouboulis

2006-01-01

381

Iron supplementation in athletes. Current recommendations.  

PubMed

There is still debate in the literature on whether or not endurance athletes tend to have low iron stores. In this article, we propose that endurance athletes really are at risk of becoming iron deficient due to an imbalance between absorption of dietary iron and exercise-induced iron loss. The purpose of this article is to present a critical review of the literature on iron supplementation in sport. The effect of iron deficiency on performance, its diagnosis and suggestions for treatment are also discussed. Studies of the nutritional status of athletes in various disciplines have shown that male, but not female, athletes clearly achieve the recommended dietary intake of iron (10 to 15 mg/day). This reflects the situation in the general population, with menstruating women being the main risk group for mild iron deficiency, even in developed countries. Whereas the benefit of iron supplementation in athletes with iron deficiency anaemia is well established, this is apparently not true for non-anaemic athletes who have exhausted iron stores alone (prelatent iron deficiency); most of the studies in the literature show no significant changes due to supplementation in the physical capacity of athletes with prelatent iron deficiency. However, the treatment protocols used in some of these studies do not meet the general recommendations for the optimal clinical management of iron deficiency, that is, with respect to adequate daily dosage, mode of administration and treatment period. For future studies, we recommend a prolonged treatment period (> or = 3 months) with standardised conditions of administration (use of a pharmaceutical iron preparation with known high bioavailability and a dosage of ferrous (Fe++) iron 100 mg/day, taken on an empty stomach). Currently, decisions regarding iron supplementation are best made on the basis of taking care of individual athletes. We believe that there are sufficient arguments to support controlled iron supplementation in all athletes with low serum ferritin levels. Firstly, the development of iron deficiency is prevented. Secondly, the nonspecific upregulation of intestinal metal ion absorption is reverted to normal, thus limiting the hyperabsorption of potentially toxic lead and cadmium even in individuals with mild iron deficiency. PMID:9820921

Nielsen, P; Nachtigall, D

1998-10-01

382

Manganese and Oxidative Damage in Cucumber  

Microsoft Academic Search

Micronutrients in low or high concentration can affect growth, respiration, photosynthesis, and reproduction in plants. Cucumber (Cucumis sativus, L.) is grown in India in areas low or high in manganese concentration in soils. A study was conducted to investigate the effects of manganese concentration on some metabolic activities affecting developmental responses in cucumber. Seed of cucumber, cv. Sonali, were grown

Rajeev Gopal

2008-01-01

383

Contaminant Transformation by a Biogenic Manganese Oxide  

NASA Astrophysics Data System (ADS)

Biomineralization of manganese by Pseudomonas putida strain MnB1 produces tetravalent manganese oxides that surround the exterior of the bacterial cell. The manganese oxides produced by P. putida transform the herbicide atrazine, a widespread environmental contaminant, by dechlorination, dealkylation and deamination reactions. The transformation reactions catalyzed by biogenic manganese oxide surfaces create a suite of transformation intermediates whose properties, such as aqueous solubility, toxicity and biodegradability, differ dramatically from those of the parent compound. The rates and products of atrazine transformation by biogenic manganese oxide surfaces were examined as functions of temperature and water potential. Air-dry samples of hydrous manganese oxide (? -MnO2) and biogenic manganese oxide were isopiestically equilibrated to -3.10, -0.50 and -0.04 MPa at 40 degrees Celsius and to -0.04 MPa at 20 and 30 degrees Celcius. The concentrations of atrazine and eight transformation intermediates were determined by HPLC. Our results suggest that biogenic manganese oxides may contribute greatly to the detoxification and immobilization of organic contaminants in the environment because of their nanoparticle size, large surface area and high chemical reactivity.

Toner, B. M.; Sposito, G.

2001-12-01

384

Manganese Neurotoxicity: An Update of Pathophysiologic Mechanisms  

Microsoft Academic Search

The central nervous system, and the basal ganglia in particular, is an important target in manganese neurotoxicity, a disorder producing neurological symptoms similar to that of Parkinson's disease. Increasing evidence suggests that astrocytes are a site of early dysfunction and damage; chronic exposure to manganese leads to selective dopaminergic dysfunction, neuronal loss, and gliosis in basal ganglia structures together with

Louise Normandin; Alan S. Hazell

2002-01-01

385

Globally sustainable manganese metal production and use  

Microsoft Academic Search

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

Karen Hagelstein

2009-01-01

386

Manganese regulates expression of manganese peroxide by Phanerochaete chrysosporium  

SciTech Connect

The appearance of manganese peroxidase (MnP) activity in nitrogen-limited cultures of Phanerochaete chrysosporium is dependent on the presence of manganese. Cultures grown in the absence of Mn developed normally and produced normal levels of the secondary metabolite veratryl alcohol but produced no MnP activity. Immunoblot analysis indicated that appearance of MnP protein in the extracellular medium was also dependent on the presence of Mn. Intracellular MnP protein was detectable only in cells grown in the presence of Mn. MnP mRNA was detected by Northern (RNA) blot analysis only in cells grown in the presence of Mn. If Mn was added to 4-day-old nitrogen-limited Mn-deficient cultures, extracellular MnP activity appeared after 6 h and reached a maximum after 18 h. Both actinomycin D and cycloheximide inhibited the induction of MnP activity by Mn. These results indicate that Mn, the substrate of the enzyme, is involved in the transcriptional regulation of the MnP gene.

Brown, J.A.; Glenn, J.K.; Gold, M.H. (Oregon Graduate Institute of Science and Technology, Beaverton (USA))

1990-06-01

387

Relationship between blood manganese and blood pressure in the Korean general population according to KNHANES 2008  

SciTech Connect

Introduction: We present data on the association of manganese (Mn) level with hypertension in a representative sample of the adult Korean population who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) 2008. Methods: This study was based on the data obtained by KNHANES 2008, which was conducted for three years (2007-2009) using a rolling sampling design involving a complex, stratified, multistage, probability-cluster survey of a representative sample of the noninstitutionalized civilian population of South Korea. Results: Multiple regression analysis after controlling for covariates, including gender, age, regional area, education level, smoking, drinking status, hemoglobin, and serum creatinine, showed that the beta coefficients of log blood Mn were 3.514, 1.878, and 2.517 for diastolic blood pressure, and 3.593, 2.449, and 2.440 for systolic blood pressure in female, male, and all participants, respectively. Multiple regression analysis including three other blood metals, lead, mercury, and cadmium, revealed no significant effects of the three metals on blood pressure and showed no effect on the association between blood Mn and blood pressure. In addition, doubling the blood Mn increased the risk of hypertension 1.828, 1.573, and 1.567 fold in women, men, and all participants, respectively, after adjustment for covariates. The addition of blood lead, mercury, and cadmium as covariates did not affect the association between blood Mn and the prevalence of hypertension. Conclusion: Blood Mn level was associated with an increased risk of hypertension in a representative sample of the Korean adult population. - Highlights: {yields} We showed the association of manganese with hypertension in Korean population. {yields} This study was based on the data obtained by KNHANES 2008. {yields} Blood manganese level was associated with an increased risk of hypertension.

Lee, Byung-Kook [Institute of Environmental and Occupational Medicine, Soonchunhyang University 646 Eupnae-ri, Shinchang-myun, Asan-si, Choongnam 336-745 (Korea, Republic of)] [Institute of Environmental and Occupational Medicine, Soonchunhyang University 646 Eupnae-ri, Shinchang-myun, Asan-si, Choongnam 336-745 (Korea, Republic of); Kim, Yangho, E-mail: yanghokm@nuri.net [Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, 290-3 Cheonha-Dong, Dong-Gu, Ulsan 682-060 (Korea, Republic of)] [Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, 290-3 Cheonha-Dong, Dong-Gu, Ulsan 682-060 (Korea, Republic of)

2011-08-15

388

Accumulation of cadmium by green microalgae  

Microsoft Academic Search

The accumulation of cadmium from aqueous systems by various green microalgae was investigated with focus, on Chlorella regularis as it is known to concentrate large amounts of heavy metals. The amount of cadmium absorbed by Chlorella cells was rapid during the first 30 min following addition of cadmium and then continued to be absorbed more slowly. The uptake of cadmium

Takashi Sakaguchi; Tomoko Tsuji; Akira Nakajima; Takao Horikoshi

1979-01-01

389

APPENDIX C Partition Coefficients For Cadmium  

E-print Network

APPENDIX C Partition Coefficients For Cadmium #12;Appendix C Partition Coefficients For Cadmium C.1.0 Background Cadmium Kd values and some important ancillary parameters that have been shown to influence cadmium sorption were collected from the literature and tabulated. Data included in this data set

390

TREMOR, OLFACTORY AND MOTOR CHANGES IN ITALIAN ADOLESCENTS EXPOSED TO HISTORICAL FERRO-MANGANESE EMISSION  

PubMed Central

Background and Objective Increased prevalence of Parkinsonism was observed in Valcamonica, Italy, a region impacted by ferroalloy plants emissions containing manganese and other metals for a century until 2001. The aim of this study was to assess neurobehavioral functions in adolescents from the impacted region and the reference area of Garda Lake. Methods Adolescents age 11–14 yrs were recruited through the school system for neuro-behavioral testing. Metals including manganese, lead, iron, zinc, copper were measured in airborne particulate matter collected with 24-hour personal samplers, and in soil, tap water, blood, urine and hair. Independent variables included parental education and socio-economic status, children’s body mass index, number of siblings, parity order, smoking and drinking habits. Results A total of 311 subjects (49.2% females), residing in either the exposed (n=154) or the reference (n=157) area participated. Average airborne and soil manganese were respectively 49.5 ng/m3 (median 31.4, range 1.24–517) and 958 ppm (median 897, range 465–1729) in the impacted area, and 27.4 ng/m3 (median 24.7, range 5.3–85.9) ng/m3 and 427 ppm (median 409 range 160–734) in the reference area. Regression models showed significant impairment of motor coordination (Luria-Nebraska test, p=0.0005), hand dexterity (Aiming Pursuit test, p= 0.0115) and odor identification (Sniffin’ task, p=0.003 ) associated with soil manganese. Tremor intensity was positively associated with blood (p=0.005) and hair (p=0.01) manganese. Conclusion Historical environmental exposure to manganese from ferroalloy emission reflected by the concentration in soil and the biomarkers was associated with subclinical deficits in olfactory and motor function among adolescents. PMID:22322213

Lucchini, Roberto G; Guazzetti, Stefano; Zoni, Silvia; Donna, Filippo; Peter, Stephanie; Zacco, Annalisa; Salmistraro, Marco; Bontempi, Elza; Zimmerman, Neil J; Smith, Donald R

2012-01-01

391

Hydrothermal manganese mineralization in the Peterbourgskoye ore field (North Atlantic)  

NASA Astrophysics Data System (ADS)

The manganese crust covered by pelagic sediment was recovered from the 3 km depth from the Peterbourgskoye ore field located on the eastern flank of the Mid-Atlantic Ridge. The crust comprises a platy brittle aggregate 1-5 cm thick made of black heterogeneous and partly porous material. The inner structure consists of aggregated parallel microplaits several micrometers to 0.2 mm thick consisting of well-crystallized bisnessite with a minor admixture of colloform vernadite. The chemical composition of the crust is dominated by manganese (more than 60% MnO) with minor iron (1.7% Fe2O3) and somewhat notable sodium and sulfur. The trace element composition is characterized by very high molybdenum, moderate gallium and uranium, and very low values of 40 other trace elements. Compared to previous publications, the composition of this crust is fairly different from the average values previously defined for hydrothermal crusts. On the other hand, it is rather close to some crusts recovered from subsea volcanoes in the Sea of Japan.

Baturin, G. N.; Dobretsova, I. G.; Dubinchuk, V. T.

2014-03-01

392

The chemical evolution of Manganese in different stellar systems  

E-print Network

Aims. To model the chemical evolution of manganese relative to iron in three different stellar systems: the solar neighbourhood, the Galactic bulge and the Sagittarius dwarf spheroidal galaxy, and compare our results with the recent and homogeneous observational data. Methods. We adopt three chemical evolution models well able to reproduce the main properties of the solar vicinity, the galactic Bulge and the Sagittarius dwarf spheroidal. Then, we compare different stellar yields in order to identify the best set to match the observational data in these systems. Results. We compute the evolution of manganese in the three systems and we find that in order to reproduce simultaneously the [Mn/Fe] versus [Fe/H] in the Galactic bulge, the solar neighbourhood and Sagittarius, the type Ia SN Mn yield must be metallicity-dependent. Conclusions. We conclude that the different histories of star formation in the three systems are not enough to reproduce the different behaviour of the [Mn/Fe] ratio, unlike the situation for [alpha/Fe]; rather, it is necessary to invoke metallicity-dependent type Ia SN Mn yields, as originally suggested by McWilliam, Rich & Smecker-Hane in 2003.

G. Cescutti; F. Matteucci; G. A. Lanfranchi; A. McWilliam

2008-07-09

393

The chemical evolution of Manganese in different stellar systems  

E-print Network

Aims. To model the chemical evolution of manganese relative to iron in three different stellar systems: the solar neighbourhood, the Galactic bulge and the Sagittarius dwarf spheroidal galaxy, and compare our results with the recent and homogeneous observational data. Methods. We adopt three chemical evolution models well able to reproduce the main properties of the solar vicinity, the galactic Bulge and the Sagittarius dwarf spheroidal. Then, we compare different stellar yields in order to identify the best set to match the observational data in these systems. Results. We compute the evolution of manganese in the three systems and we find that in order to reproduce simultaneously the [Mn/Fe] versus [Fe/H] in the Galactic bulge, the solar neighbourhood and Sagittarius, the type Ia SN Mn yield must be metallicity-dependent. Conclusions. We conclude that the different histories of star formation in the three systems are not enough to reproduce the different behaviour of the [Mn/Fe] ratio, unlike the situation f...

Cescutti, G; Lanfranchi, G A; McWilliam, A

2008-01-01

394

Characterisation and Processing of Some Iron Ores of India  

NASA Astrophysics Data System (ADS)

Lack of process characterization data of the ores based on the granulometry, texture, mineralogy, physical, chemical, properties, merits and limitations of process, market and local conditions may mislead the mineral processing entrepreneur. The proper implementation of process characterization and geotechnical map data will result in optimized sustainable utilization of resource by processing. A few case studies of process characterization of some Indian iron ores are dealt with. The tentative ascending order of process refractoriness of iron ores is massive hematite/magnetite < marine black iron oxide sands < laminated soft friable siliceous ore fines < massive banded magnetite quartzite < laminated soft friable clayey aluminous ore fines < massive banded hematite quartzite/jasper < massive clayey hydrated iron oxide ore < manganese bearing iron ores massive < Ti-V bearing magnetite magmatic ore < ferruginous cherty quartzite. Based on diagnostic process characterization, the ores have been classified and generic process have been adopted for some Indian iron ores.

Krishna, S. J. G.; Patil, M. R.; Rudrappa, C.; Kumar, S. P.; Ravi, B. P.

2013-10-01

395

The Structural Stability of Manganese Oxide Electrodes for Lithium Batteries  

Microsoft Academic Search

Manganese oxides are of interest as insertion electrodes for rechargeable 3 V and 4 V lithium batteries. During discharge, lithium ions are inserted into the manganese oxide host structure with a concomitant reduction of the manganese ions; the reverse process occurs on charge. The cycle life of these batteries is critically dependent on the ability of the manganese oxide structure

Michael M. Thackeray

1997-01-01

396

Iron behavior in the ozonation and filtration of groundwater  

SciTech Connect

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.

Sallanko, J.; Lakso, E.; Ropelinen, J. [University of Oulu, Oulu (Finland)

2006-08-15

397

Iron uptake and homeostasis related genes in potato cultivated in vitro under iron deficiency and overload.  

PubMed

Potato is one of the most important staple food in the world because it is a good source of vitamin C, vitamin B6 but also an interesting source of minerals including mainly potassium, but also magnesium, phosphorus, manganese, zinc and iron to a lesser extent. The lack of iron constitutes the main form of micronutrient deficiency in the world, namely iron deficiency anemia, which strongly affects pregnant women and children from developing countries. Iron biofortification of major staple food such as potato is thus a crucial issue for populations from these countries. To better understand mechanisms leading to iron accumulation in potato, we followed in an in vitro culture experiment, by qPCR, in the cultivar Désirée, the influence of media iron content on the expression of genes related to iron uptake, transport and homeostasis. As expected, plantlets grown in a low iron medium (1 mg L(-1) FeNaEDTA) displayed a decreased iron content, a strong induction of iron deficiency-related genes and a decreased expression of ferritins. Inversely, plantlets grown in a high iron medium (120 mg L(-1) FeNaEDTA) strongly accumulated iron in roots; however, no significant change in the expression of our set of genes was observed compared to control (40 mg L(-1) FeNaEDTA). PMID:22983142

Legay, Sylvain; Guignard, Cédric; Ziebel, Johanna; Evers, Danièle

2012-11-01

398

Body retention and tissue distribution of59Fe and 54Mn in newborn rats fed iron-supplemented cow's milk  

E-print Network

», Nuclear Chicago, USA). S9Fe and 54Mn activities in the liver, spleen and intestinal tract were determined). The distribution of radioactive iron and manganese in the gastrointestinal tract, liver and spleen (table 2 retention in the liver as well, but to a lesser degree. Iron had no effect on 5'Mn retention in the spleen

Boyer, Edmond

399

Manganese metallurgy review. Part I: Leaching of ores\\/secondary materials and recovery of electrolytic\\/chemical manganese dioxide  

Microsoft Academic Search

The world rapidly growing demand for manganese has made it increasingly important to develop processes for economical recovery of manganese from low grade manganese ores and other secondary sources. Part I of this review outlines metallurgical processes for manganese production from various resources, particularly focusing on recent developments in direct hydrometallurgical leaching and recovery processes to identify potential sources of

Wensheng Zhang; Chu Yong Cheng

2007-01-01