Note: This page contains sample records for the topic cadmium iron manganese from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Comparative Effects of Iron Deficiency Induced by Bleeding and a Low-Iron Diet on the Intestinal Absorptive Interactions of Iron, Cobalt, Manganese, Zinc, Lead and Cadmium1  

Microsoft Academic Search

Dietary iron deficiency enhances the absorption of iron, cobalt, manganese, zinc, cadmium and lead, whereas, iron deficiency due to bleeding in creases the absorption of iron, cobalt and perhaps manganese. To determine whether the response to bleeding is qualitatively different from that induced by dietary iron deficiency, metal absorption was studied in mice fed either a high- iron diet (120

PETER R. FLANAGAN; JAMES HAIST; LESLIE S. VALBERG

2

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

3

Characterizing the role of rice NRAMP5 in Manganese, Iron and Cadmium Transport  

PubMed Central

Metals like manganese (Mn) and iron (Fe) are essential for metabolism, while cadmium (Cd) is toxic for virtually all living organisms. Understanding the transport of these metals is important for breeding better crops. We have identified that OsNRAMP5 contributes to Mn, Fe and Cd transport in rice. OsNRAMP5 expression was restricted to roots epidermis, exodermis, and outer layers of the cortex as well as in tissues around the xylem. OsNRAMP5 localized to the plasma membrane, and complemented the growth of yeast strains defective in Mn, Fe, and Cd transport. OsNRAMP5 RNAi (OsNRAMP5i) plants accumulated less Mn in the roots, and less Mn and Fe in shoots, and xylem sap. The suppression of OsNRAMP5 promoted Cd translocation to shoots, highlighting the importance of this gene for Cd phytoremediation. These data reveal that OsNRAMP5 contributes to Mn, Cd, and Fe transport in rice and is important for plant growth and development.

Ishimaru, Yasuhiro; Takahashi, Ryuichi; Bashir, Khurram; Shimo, Hugo; Senoura, Takeshi; Sugimoto, Kazuhiko; Ono, Kazuko; Yano, Masahiro; Ishikawa, Satoru; Arao, Tomohito; Nakanishi, Hiromi; Nishizawa, Naoko K.

2012-01-01

4

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

2013-04-16

5

Atmospheric pollution in the Venice area. II. Iron, manganese, lead, vanadium and cadmium in suspended particulate.  

PubMed

The average yearly and semestral concentrations of some metals (Fe, Mn, Pb, V and Cd) contained in the suspended particulate of three different sites in the Venice area, are presented. The 24-h concentrations of the five metals fit a log-normal distribution. The correlation coefficients between metals, and between metals and sulphur dioxide, suspended particles, and sulphates are also reported; they are very high in the insular zone (historical centre of Venice). This is not found for cadmium, which shows a different behaviour with respect to the other metals. Cadmium is the only pollutant studied whose concentration is higher in the insular urban zone than in the industrial and urban zones of the mainland. PMID:3810148

Bertolaccini, M A; Gucci, P M

1986-12-01

6

Lead, mercury, cadmium, chromium, nickel, copper, zinc, calcium, iron, manganese and chromium (VI) levels in Nigeria and United States of America cement dust.  

PubMed

This study was aimed at investigating the relative abundance of heavy metals in cement dust from different cement dust factories in order to predict their possible roles in the severity of cement dust toxicity. The concentrations of total mercury (Hg), copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), manganese (Mn), lead (Pb), iron (Fe) and chromium (VI) (Cr (VI)) levels in cement dust and clinker samples from Nigeria and cement dust sample from the United States of America (USA) were determined using graphite furnace atomic absorption (GFAAS), while Zn and Ca were measured by flame atomic absorption spectrophotometry (FAAS), and Cr (VI) by colorimetric method. Total Cu, Ni and Mn were significantly higher in cement dust sample from USA (p<0.05), also, both total Cr and Cr (VI) were 5.4-26 folds higher in USA cement dust compared with Nigeria cement dust or clinker (p<0.001). Total Cd was higher in both Nigeria cement dust and clinker (p<0.05 and p<0.001), respectively. Mercury was more in both Nigeria cement dust and clinker (p<0.05), while Pb was only significantly higher in clinker from Nigeria (p<0.001). These results show that cement dust contain mixture of metals that are known human carcinogens and also have been implicated in other debilitating health conditions. Additionally, it revealed that metal content concentrations are factory dependent. This study appears to indicate the need for additional human studies relating the toxicity of these metals and their health impacts on cement factory workers. PMID:23261125

Ogunbileje, J O; Sadagoparamanujam, V-M; Anetor, J I; Farombi, E O; Akinosun, O M; Okorodudu, A O

2012-12-21

7

Alterations in the metabolism of endogenous trace metals due to cadmium, manganese and nickel - effect of partial hepatectomy  

SciTech Connect

The effect of cadmium, manganese and nickel on the levels of copper, manganese, iron and zinc in liver was studied in sham operated and partially hepatectomized rats, 72 hrs after metal administration. Partial hepatectomy produced significant increase in the level of zinc and decrease in the levels of copper, iron and manganese. The metabolic disposition of these essential micronutrients were significantly altered as a result of cadmium administration in both the groups. Manganese and nickel had little effect and only induced the level of zinc.

Srivastava, R.C.; Ahmad, I.; Kaur, G.; Hasan, S.K.

1988-01-01

8

Manganese is highly effective in protecting cells from cadmium intoxication  

SciTech Connect

Cadmium poisoning results in cell death. Although several intracellular pathways have been identified in this response, transport systems responsible for cadmium entry into cells remain poorly understood and controversial. Here, we analyzed the effects of several divalent cations on cadmium toxicity in different cell types. We found that zinc, previously reported as a protective agent against cadmium poisoning, is actually much less efficient than manganese. We show that manganese dramatically reduces cadmium intake, and that this is associated with the inhibition of our recently reported sustained activation of ERK, characteristic of cadmium intoxication. Finally, we show that this inhibition of cadmium entry and ERK-sustained activation perfectly correlates with a high cellular resistance to cadmium exposure. Our results, together with previously published data, support the idea that the yet to be characterized manganese transporter system(s) may be responsible for cadmium entry into cells.

Martin, Patrick [CNRS UMR 6548, Nice University, Parc Valrose, 06108 Nice Cedex 2 (France)]. E-mail: pmartin@unice.fr; Fareh, Mohamed [CNRS UMR 6548, Nice University, Parc Valrose, 06108 Nice Cedex 2 (France)]. E-mail: fareh10@hotmail.com; Poggi, Marie Christine [CNRS UMR 6548, Nice University, Parc Valrose, 06108 Nice Cedex 2 (France)]. E-mail: poggi@unice.fr; Boulukos, Kim E. [CNRS UMR 6548, Nice University, Parc Valrose, 06108 Nice Cedex 2 (France)]. E-mail: boulukos@unice.fr; Pognonec, Philippe [CNRS UMR 6548, Nice University, Parc Valrose, 06108 Nice Cedex 2 (France)]. E-mail: pognonec@unice.fr

2006-12-08

9

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.

Aguirre, J. Dafhne; Culotta, Valeria C.

2012-01-01

10

Investigation of manganese-doped iron ammonia synthesis catalysts  

Microsoft Academic Search

The iron catalysts for ammonia synthesis doped with manganese in amounts up to 3wt.% has been investigated. The addition of manganese oxide did not influence the distribution of other promoters in the catalyst precursors, manganese oxide itself was entirely incorporated into phases of iron oxides, its concentration in the wustite phase was about twice that in the magnetite phase.At concentrations

Micha? J. Figurski; Walerian Arabczyk; Zofia Lendzion-Bielu?; Stanis?aw Lenart

2004-01-01

11

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

12

AM1* parameters for manganese and iron.  

PubMed

We report the parameterization of AM1* for the elements manganese and iron. The basis sets for both metals contain one set each of s-, p- and d-orbitals. AM1* parameters are now available for H, C, N, O and F (which use the original AM1 parameters), Al, Si, P, S, Cl, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Zr, Mo, I and Au. The performance and typical errors of AM1* are discussed for Mn and Fe, and are compared with available NDDO Hamiltonians. PMID:19937261

Kayi, Hakan; Clark, Timothy

2009-11-24

13

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

SciTech Connect

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

Ho, S.Y.

1981-01-01

14

A zinc-resistant human epithelial cell line is impaired in cadmium and manganese import  

SciTech Connect

A human epithelial cell line (HZR) growing with high zinc concentrations has been analyzed for its ability to sustain high cadmium concentrations. Exposure to up to 200 {mu}M of cadmium acetate for 24 h hardly impacted viability, whereas most of parental HeLa cells were killed by less than 10 {mu}M of cadmium. Upon challenge by 35 fold higher cadmium concentrations than HeLa cells, HZR cells did not display increased DNA damage, increased protein oxidation, or changed intracellular cadmium localization. Rather, the main cause of resistance against cadmium was by avoiding cadmium entry into cells, which differs from that against zinc as the latter accumulates inside cells. The zinc-resistant phenotype of these cells was shown to also impair extracellular manganese uptake. Manganese and cadmium competed for entry into HeLa cells. Probing formerly identified cadmium or manganese transport systems in different animal cells did not evidence any significant change between HeLa and HZR cells. These results reveal zinc adaptation influences manganese and cadmium cellular traffic and they highlight previously unknown connections among homeostasis of divalent metals.

Rousselet, Estelle [CEA, DSV, IRTSV, Laboratoire de Chimie et Biologie des Metaux, Grenoble (France)]|[LCBM, CNRS UMR5249, Grenoble (France); Universite Joseph Fourier, Grenoble (France); Richaud, Pierre [CEA, DSV, IBEB, SBVME, LB3M, Saint-Paul-lez-Durance (France)]|[LB3M, CNRS UMR 6191, Saint-Paul-lez-Durance (France)]|[Universite Aix-Marseille (France); Douki, Thierry; Chantegrel, Jocelyne Garcia; Favier, Alain [Universite Joseph Fourier, Grenoble (France)]|[CEA, DSM, INaC/SCIB, Laboratoire 'Lesions des Acides Nucleiques', Grenoble (France); Bouron, Alexandre [CEA, DSV, IRTSV, Laboratoire de Chimie et Biologie des Metaux, Grenoble (France)]|[LCBM, CNRS UMR5249, Grenoble (France)]|[Universite Joseph Fourier, Grenoble (France); Moulis, Jean-Marc [CEA, DSV, IRTSV, Laboratoire de Chimie et Biologie des Metaux, Grenoble (France)]|[LCBM, CNRS UMR5249, Grenoble (France)]|[Universite Joseph Fourier, Grenoble (France)], E-mail: jean-marc.moulis@cea.fr

2008-08-01

15

Thermochemistry of iron manganese oxide spinels  

SciTech Connect

Oxide melt solution calorimetry has been performed on iron manganese oxide spinels prepared at high temperature. The enthalpy of formation of (Mn{sub x}Fe{sub 1-x}){sub 3}O{sub 4} at 298K from the oxides, tetragonal Mn{sub 3}O{sub 4} (hausmannite) and cubic Fe{sub 3}O{sub 4} (magnetite), is negative from x=0 to x=0.67 and becomes slightly positive for 0.670.6) spinels of intermediate compositions. The enthalpies of formation are discussed in terms of three factors: oxidation-reduction relative to the end-members, cation distribution, and tetragonality. A combination of measured enthalpies and Gibbs free energies of formation in the literature provides entropies of mixing. {delta}S{sub mix}, consistent with a cation distribution in which all trivalent manganese is octahedral and all other ions are randomly distributed for x>0.5, but the entropy of mixing appears to be smaller than these predicted values for x<0.4.

Guillemet-Fritsch, Sophie [Centre InterUniversitaire de Recherche et d'Ingenierie des Materiaux (CIRIMAT/LCMIE), Universite Paul Sabatier, Ba-hat timent 2R1, 118, route de Narbonne, 31062 Toulouse, Cedex 04 (France); Navrotsky, Alexandra [Thermochemistry Facility and NEAT ORU, University of California at Davis, One Shields Avenue, Davis, CA 95616-877 (United States)]. E-mail: anavrotsky@ucdavis.edu; Tailhades, Philippe [Centre InterUniversitaire de Recherche et d'Ingenierie des Materiaux (CIRIMAT/LCMIE), Universite Paul Sabatier, Ba-hat timent 2R1, 118, route de Narbonne, 31062 Toulouse, Cedex 04 (France); Coradin, Herve [Centre InterUniversitaire de Recherche et d'Ingenierie des Materiaux (CIRIMAT/LCMIE), Universite Paul Sabatier, Ba-hat timent 2R1, 118, route de Narbonne, 31062 Toulouse, Cedex 04 (France); Wang Miaojun [Thermochemistry Facility and NEAT ORU, University of California at Davis, One Shields Avenue, Davis, CA 95616-877 (United States)

2005-01-15

16

Manganese, nickel, selenium and cadmium in molluscs from the Magellan Strait, Chile.  

PubMed

The concentrations of manganese, selenium, nickel and cadmium were determined in 112 samples of molluscs belonging to mussels (Mytilus chilensis, n = 47) and limpets (Nacella deaurata, n = 65), which were collected from the coastline of the Magellan Strait, Chile. Four (6.2%) samples of limpets exceeded the maximum limits for cadmium established in Europe. Limpets showed higher mean manganese, nickel and cadmium concentrations than mussels, whilst the mean selenium concentration in mussels was higher. The consumption of one serving (100 g) of molluscs represents a considerable contribution to the dietary daily intake of selenium, and limpets make a significant contribution to the manganese and cadmium intakes. The sampling zone influenced the trace element concentrations, and different uptakes were observed between the mollusc species. PMID:15370827

Astorga España, M S; Rodríguez Rodríguez, E M; Díaz Romero, C

2004-08-01

17

Cadmium and manganese flux in eelgrass Zostera marina II. Metal uptake by leaf and root-rhizome tissues  

Microsoft Academic Search

Cadmium and manganese radionuclide uptake by Zostera marina L. tissues and translocation between rootrhizomes and leaves was examined. Cadmium concentrations in root-rhizomes increased with incubation time but appeared to reach saturation levels at 24 h of exposure. Translocation of cadmium between root-rhizomes and leaves occurred in both directions. A greater flux of cadmium downward suggested that root-rhizomes were a cadmium

B. H. Brinkhuis; W. F. Penello; A. C. Churchill

1980-01-01

18

Structural, spectral and mechanical studies of bimetallic crystal: cadmium manganese thiocyanate single crystals  

NASA Astrophysics Data System (ADS)

A nonlinear optical bimetallic thiocyanate complex crystal, cadmium manganese thiocyanate (CMTC) has been successfully synthesized. The growth of single crystals of cadmium manganese thiocyanate has been accomplished from aqueous solution using slow evaporation method. The presence of manganese and cadmium in the synthesized material was confirmed through energy dispersive spectrum (EDS) analysis. Structural analysis was carried out using powder X-ray diffractometer (PXRD) and crystalline perfection of the grown crystals was ascertained by high-resolution X-ray diffraction (HRXRD) analysis. Fourier transform infrared (FTIR) spectrum was taken to confirm the functional groups. The transmittance spectrum of the crystal in the UV-visible region has been recorded and the cutoff wavelength has been determined. The dielectric measurements for the crystals were performed for various frequencies and temperatures. The mechanical properties were evaluated by Vickers microhardness testing, which reveals hardness and stiffness constant of the crystals.

Manikandan, M.; Vijaya Prasath, G.; Bhagavannarayan, G.; Vijayan, N.; Mahalingam, T.; Ravi, G.

2012-09-01

19

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

20

Compartmentation of Cadmium and Iron in Mesembryanthemum crystallinum Plants during the Adaptation to Cadmium Stress  

Microsoft Academic Search

The common ice plants (Mesembryanthemum crystallinum) at the stage of five leaf pairs were exposed to cadmium chloride solutions (1, 0.1, and 0.01 mM) under the conditions of water culture. After five days, the partition of cadmium and iron in the plant organs and in the cell structures of the apical root region were investigated. Plant adaptation to excess cadmium

N. I. Shevyakova; I. A. Netronina; E. E. Aronova; Vl. V. Kuznetsov

2003-01-01

21

SUBSURFACE REMOVAL OF IRON AND MANGANESE FROM GROUNDWATER - CASE STUDY  

Microsoft Academic Search

Although subsurface removal of iron and manganese from groundwater had been used in Europe for decades, it doesn't have an established design criteria and its application depends on the field practice and trials. The first application of the method in Egypt was performed few years ago by a pioneer water company. A full technical and economical study was carried out

Ashraf A. K. Karakish

22

Iron-manganese formations in the Baikal region  

Microsoft Academic Search

This work is a review of the modern concepts of the accumulation of Fe and Mn in the Baikal bottom sediments and the regularities of formation of iron-manganese (including phosphate-bearing) nodules in the lake. Special attention is given to the probable participation of hydrothermal water in this process and the genesis of ancient nodules deeply buried in the Baikal sediments.

L. Z. Granina; V. D. Mats; M. A. Phedorin

2010-01-01

23

Elements of the iron and manganese cycles in Lake Baikal  

Microsoft Academic Search

Using data obtained in recent years, we considered the external mass balance and characteristics of internal iron and manganese\\u000a cycles in Lake Baikal (biological uptake, remineralization, sedimentary and diffusive fluxes, accumulation in sediments, time\\u000a of renewal, etc.). Some previous results and common concepts were critically reevaluated.

L. Z. Granina; E. Callender

2007-01-01

24

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

25

Morphology Studies of Iron-Manganese Thin Films on Silicon and Graphite Substrates  

Microsoft Academic Search

In the Fischer-Tropsch Synthesis, hydrogenation of carbon monoxide is used to make hydrocarbons with iron as the catalyst. Sulfur from coal deactivates iron. Manganese increases the activity of iron in the presence of sulfur. Different alloys of iron and manganese (100% Fe, 100% Mn, 50% Fe -50% Mn) were made by Okasaki's method of electro-compaction. Thin films were then made

George Mathew

1994-01-01

26

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

27

Ocean environment and developing of oceanic iron-manganese ores  

NASA Astrophysics Data System (ADS)

This work is devoted to some problems of the genesis, chemical composition, and forming rates of iron-manganese ores (IMOs) in the ocean bed due to real outlooks of their development in the years 2015-2020. It is particularly accentuated that ores are continuously originating on the ocean bed with rates of several millimeters per million years. IMO accumulation in modern oceans is greatly more than the age of the mobile ocean bed. These unique ores are not only sorbents of some strategic microelements, but also store easily mobilized oxygen, which is able to supersaturate water in endogenic processes on the ocean bed, blocking their expansion in a limited volume. Thus, iron-manganese ores must be mined only with nonpolluting methods and under the control of competent authorities.

Bazilevskaya, E. S.

2009-12-01

28

Distributions of manganese, iron, and manganese-oxidizing bacteria in Lake Superior sediments of different organic carbon content  

Microsoft Academic Search

Profiles of oxygen, soluble and particulate manganese and iron, organic carbon and nitrogen were examined in Lake Superior sediment cores, along with the distribution and abundance of heterotrophic and manganese oxidizing bacteria. Analyses were performed using cores collected with the submersible Johnson Sea Link II. Three cores, exhibiting a range of organic carbon content, were collected from the deepest basin

Laurie L. Richardson; Kenneth H. Nealson

1989-01-01

29

Heavy metal pollution among autoworkers. II. Cadmium, chromium, copper, manganese, and nickel.  

PubMed Central

Garages and auto-repair workshops may be polluted with other heavy metals besides lead. Blood of autoworkers with high lead content was analysed for cadmium, chromium, copper manganese, nickel, ALAD activity and carboxyhaemoglobin level. Cadmium and copper levels in blood of autoworkers were comparable with those of the control subjects while chroimium and nickel levels were significantly higher (P less than 0-01 for both metals), and scattered raised values of manganese were found. There was no significant mutual correlation between levels of various heavy metals determined in whole blood. High copper levels were slightly related to decreasing ALAD activity (P less than 0-1). Nineteen per cent of autoworkers were found to have an abnormally blood level of carboxyhaemoglobin. The amount of particulate heavy metal in autoworkshop air was not related to biochemical abnormalities found in the autoworkers. Various sources of pollution of these heavy metals in autoworkshops are discussed.

Clausen, J; Rastogi, S C

1977-01-01

30

Cadmium effects in rats on tissue iron, selenium, and blood pressure: blood and hair cadmium in some Oregon residents  

PubMed Central

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.

Whanger, P. D.

1979-01-01

31

Varying Levels of Manganese and Iron Affect Absorption and Gut Endogenous Losses of Manganese by Rats1  

Microsoft Academic Search

The interactive effects of manganese and iron on true absorption and endogenous losses of man ganese were investigated by feeding rats three levels of manganese (0.9, 48 or 188 ug Mn\\/g diet) and two levels of iron (19 or 276 ug Fe\\/a diet) for 7 wk. After 45 d, half of the rats were fed •'^Mn and half were injected

CINDY D. DAVIS; TERRY L WOLF; ANDJ. L GREGER

32

Zinc, iron, manganese, and magnesium accumulation in crayfish populations near copper-nickel smelters at Sudbury, Ontario, Canada  

SciTech Connect

The Sudbury basin has been subjected to extreme ecological disturbances from logging, mining and smelting activities. Elevated concentrations of copper, cadmium, and nickel have been reported in crayfish populations close to the Sudbury smelting works. The present study compares concentrations of zinc (Zn), iron (Fe), manganese (Mn) and magnesium (Mg) in freshwater crayfish at selected distances of the habitat from the emission source. These metals were selected since they are known to be emitted in moderately high quantities into the Sudbury environment as byproduct of the smelting process. Various tissue concentrations in crayfish were also examined to determined specific tissue sites for these accumulations.

Bagatto, G.; Alikhan, M.A.

1987-06-01

33

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

34

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

Microsoft Academic Search

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

Maria Kippler; Eva-Charlotte Ekstroem; Bo Loennerdal; Walter Goessler; Agneta Åkesson; Shams El Arifeen; Lars-Åke Persson; Marie. Vahter

2007-01-01

35

Long-term follow-up of workplace and well water manganese effects on iron status indexes in manganese miners.  

PubMed

The authors assessed the effect of water reconstitution in the workplace by evaluating the iron status of manganese mine workers during a long-term study. Subsequent analyses and biological monitoring were performed in a group of 150 manganese miners before, and 2.8 yr after, reconstitution of drinking water in the miners' workplace. The authors found significantly high concentrations of manganese in the workplace well water, as well as in the miners' blood, urine, and hair. There was a considerable prevalence of epithelial lesions, which resulted from iron deficiency, in the miners, compared with controls. The authors assessed the prevalence of iron deficiency grades (i.e., I > II > III > IV) before and after water reconstitution. Reconstitution of drinking water for the ultimate attainment of healthy levels of manganese and other minerals resulted in a significant improvement in the miners' iron status and a decreased prevalence of epithelial lesions. The authors concluded that alterations in iron status may result from the cumulative effect of high levels of manganese in consumed water, as well as in airborne dust, in the workplace. Such elevated levels should be considered as an occupational hazard because they have an ability to interfere with iron absorption. PMID:12696648

Boojar, Massod Mashhadi Akbar; Goodarzi, Faranak; Basedaghat, Mohamad Ali

36

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

37

Iron and cadmium capture gamma-ray photofission measurements  

Microsoft Academic Search

Photofission measurements have been made in ²³⁸U, ²³²Th, and ²³⁷Np in iron and cadmium capture gamma-ray spectra in cylindrical neutron-driven gamma-ray sources in the thermal column of the National Bureau of Standards (NBS) Reactor. The gamma-ray source strength was measured with neutron activation foils and by direct counting of activations produced in the metal cylinders. Photofission measurements were made with

T. G. Williamson; G. P. Lamaze; D. M. Gilliam; C. M. Eisenhauer

1990-01-01

38

Distributions of manganese, iron, and manganese-oxidizing bacteria in Lake Superior sediments of different organic carbon content  

SciTech Connect

Profiles of oxygen, soluble and particulate manganese and iron, organic carbon and nitrogen were examined in Lake Superior sediment cores, along with the distribution and abundance of heterotrophic and manganese oxidizing bacteria. Analyses were performed using cores collected with the submersible Johnson Sea Link II. Three cores, exhibiting a range of organic carbon content, were collected from the deepest basin in Lake Superior and the north and south ends of the Caribou trough, and brought to the surface for immediate analysis. Minielectrode profiles of oxygen concentration of the three cores were carried out using a commercially available minielectrode apparatus. Oxygen depletion to less than 1% occurred within 4 cm of the surface for two of the cores, but not until approximately 15 cm for the core from the south basin of the Caribou trough. The three cores exhibited very different profiles of soluble, as well as leachable, manganese and iron, suggesting different degrees of remobilization of these metals in the sediments. Vertical profiles of viable bacterial and Mn oxidizing bacteria, determined by plating and counting, showed that aerobic heterotrophic bacteria were present at the highest concentrations near the surface and decreased steadily with depth, while Mn oxidizing bacteria were concentrated primarily at and above the oxic/anoxic interface. Soluble manganese in the pore waters, along with abundant organic carbon, appeared to enhance the presence of manganese oxidizing bacteria, even below the oxic/anoxic interface. Profiles of solid-phase leachable manganese suggested a microbial role in manganese reprecipitation in these sediments.

Richardson, L.L.; Nealson, K.H.

1989-01-01

39

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

40

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

41

Some characteristics of structure formation in manganese cast irons and steels  

Microsoft Academic Search

1.Manganese lowers the solubility of carbon in the melt, while austenite raises the eutectic equilibrium temperature and shifts the eutectic point toward lower carbon concentrations.2.With a high manganese concentration in cast iron the shift of the eutectic point leads to a sharp change in the ratio of phases and their composition. The amount of cementite is insufficient for the formation

G. I. Sil'man; N. I. Pristuplyuk; M. S. Frol'tsov

1977-01-01

42

Biochemical Indications as a means of distinguishing between Iron and Manganese Deficiency Symptoms in Citrus Plants  

Microsoft Academic Search

IRON and manganese deficiencies are widespread in many citrus-gcowing areas throughout the world, including Israel. Similarity of the visual symptoms of these deficiencies, in some stages (Fig. 1), makes differentiation difficult1.

A. Bar-Akiva

1961-01-01

43

Spectroscopic and Microscopic Characterization of Iron and\\/or Manganese-Promoted Sulfated Zirconia  

Microsoft Academic Search

The structures of iron-promoted sulfated zirconia (FSZ), manganese-promoted sulfated zirconia (MSZ) and iron- and manganese-promoted sulfated zirconia (FMSZ) were investigated by ultra-violet-visible (UV-vis) diffuse reflectance, ESR, laser Raman, and X-ray photoelectron (XP) spectroscopies and by transmission electron microscopy with energy dispersive X-ray microanalysis. The bulk structure of tetragonal zirconia and the surface sulfate structure of SZ remained virtually unchanged when

Markus Scheithauer; Eric Bosch; Uwe A. Schubert; Helmut Knözinger; Tsz-Keung Cheung; Friederike C. Jentoft; Bruce C. Gates; Bernd Tesche

1998-01-01

44

Removal of Arsenate from Aqueous Solution by Manganese and Iron (hydr)oxides Coated Resin  

Microsoft Academic Search

A composite adsorbent MIR, manganese and iron (hydr)oxides coated resin, was prepared by coating manganese and iron (hydr)oxides onto the weak basic anion exchange resin D301. The effects of solution pH, contact time, ionic strength, and coexisting ions on arsenate removal with MIR were investigated in batch experiments. The results showed that As(V) can be effectively removed in a wide

Hongmei Ma; Zhiliang Zhu; Lijing Dong; Yanling Qiu; Jianfu Zhao

2010-01-01

45

[Effect of iron-containing supplements on the level of iron, copper, and manganese in young sportsmen].  

PubMed

In was defined that 2-week intake by senior school pupils of iron-containing supplements combined with an ascorbic acid was followed by a significant increase of iron concentration in plasma and formal blood elements, hemoglobin and erythrocytes level, increase of vitamin C provision and physical performance efficiency at simultaneous decrease of copper and manganese content in blood plasma. PMID:20968011

Za?tseva, I P

2010-01-01

46

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

47

Removal of iron and manganese from micro-polluted surface source water using bio-sand filtration system  

Microsoft Academic Search

Bio-sand filter was adopted to study the iron and manganese removal from micro-polluted surface source water, and the effect by biofilm formation method, dissolved oxygen (DO) and water temperature on iron and manganese were analyzed. The results demonstrate that natural start-up and inoculm start-up methods of filters both have a high removal of iron and manganese. The former method is

Si-min Li; Bo Zhao; Zhennan Shi; Wei Zhang

2010-01-01

48

Manganese carbonyl nitrosyls: comparison with isoelectronic iron carbonyl derivatives.  

PubMed

The manganese carbonyl nitrosyls Mn(NO)(CO)4, Mn2(NO)2(CO)n (n = 7, 6, 5, 4), and Mn3(NO)3(CO)9 have been studied by density functional theory (DFT) using the B3LYP and BP86 methods for comparison of their predicted structures with those of isoelectronic iron carbonyl derivatives. DFT predicts a trigonal bipyramidal structure for Mn(NO)(CO)4 with an equatorial NO group very close to the experimental structure. The predicted lowest energy structure for Mn2(NO)2(CO)7 has two bridging NO groups in contrast to the known structure of the isoelectronic Fe2(CO)9, which has three bridging CO groups. The structures for the unsaturated binuclear Mn2(NO)2(CO)n (n = 6, 5, 4) derivatives are similar to those of the corresponding binuclear iron carbonyls Fe2(CO)n+2 derivatives but always with a preference of bridging NO groups over bridging CO groups. The trinuclear Mn3(NO)3(CO)9 is predicted to have a structure analogous to the known structure for Fe3(CO)12 but with two bridging NO groups rather than two bridging CO groups across one of the metal-metal edges of the M3 triangle. The dark red solid photolysis product of Mn(NO)(CO)4 characterized by its nu(CO) and nu(NO) frequencies approximately 45 years ago is suggested by these DFT studies not to be the originally assumed Mn2(NO)2(CO)7 analogous to Fe2(CO)9. Instead, this photolysis product appears to be Mn2(NO)2(CO)5 with a Mn(triple bond)Mn formal triple bond analogous to (eta5-C5H5)2V2(CO)5 obtained from the photolysis of (eta5-C5H5)V(CO)4. PMID:17173444

Wang, Hongyan; Xie, Yaoming; King, R Bruce; Schaefer, Henry F

2006-12-25

49

Manganese content of mustard leaves in relation to iron and major nutrient supply  

Microsoft Academic Search

Summary In a study of manganese uptake by mustard plants in nutrient culture, the Mn\\/Fe, P\\/Fe, and K\\/Ca ratios in the leaves have been shown to vary in the same way with change in iron concentration of the medium. Copper shows similar inverse changes with iron. The metabolic significance of these ratios is discussed.

P. C. Dekock; R. H. E. Inkson

1962-01-01

50

Simultaneous determination of iron and manganese in water using artificial neural network catalytic spectrophotometric method  

NASA Astrophysics Data System (ADS)

A new analytical method using Back-Propagation (BP) artificial neural network and kinetic spectrophotometry for simultaneous determination of iron and magnesium in tap water, the Yellow River water and seawater is established. By conditional experiments, the optimum analytical conditions and parameters are obtained. Levenberg-Marquart (L-M) algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 15-16-2 (nodes). The initial value of gradient coefficient µ is fixed at 0.001 and the increase factor and reduction factor of µ take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviation of the calculated results for iron and manganese is 2.30% and 2.67% respectively. The results of standard addition method show that for the tap water, the recoveries of iron and manganese are in the ranges of 98.0%-104.3% and 96.5%-104.5%, and the RSD is in the range of 0.23%-0.98%; for the Yellow River water (Lijin district of Shandong Province), the recoveries of iron and manganese are in the ranges of 96.0%-101.0% and 98.7%-104.2%, and the RSD is in the range of 0.13%-2.52%; for the seawater in Qingdao offshore, the recoveries of iron and manganese are in the ranges of 95.3%-104.8% and 95.3%-104.7%, and the RSD is in the range of 0.14%-2.66%. It is found that 21 common cations and anions do not interfere with the determination of iron and manganese under the optimum experimental conditions. This method exhibits good reproducibility and high accuracy in the determination of iron and manganese and can be used for the simultaneous determination of iron and manganese in tap water and natural water. By using the established ANN-catalytic spectrophotometric method, the iron and manganese concentrations of the surface seawater at 11 sites in Qingdao offshore are determined and the level distribution maps of iron and manganese are drawn.

Ji, Hongwei; Xu, Yan; Li, Shuang; Xin, Huizhen; Cao, Hengxia

2012-09-01

51

Manganese.  

PubMed

Manganese is a very hard, brittle metal, which is used to increase the strength of steel alloys. Absorption from the gastrointestinal tract occurs in the divalent and tetravalent forms. Permanganates, which are strong oxidizing agents, have a +7 valence. The principal organomanganese compound is the anti-knock additive, methylcyclopentadienyl manganese tricarbonyl. Manganese is a ubiquitous constituent of the environment comprising about 0.1% of the earth's crust. For the general population, food is the most important source of manganese with daily intake ranging from 2-9 mg Mn. Combustion of gasoline containing methylcyclopentadienyl manganese tricarbonyl releases submicron particles of Mn3O4 that are potentially respirable. Biomagnification of manganese in the food chain probably does not occur. The lungs and gastrointestinal tract absorb some manganese, but the relative amounts absorbed from each site are not known. Homeostatic mechanisms limit the absorption of manganese from the gastrointestinal tract. Elimination of manganese occurs primarily by excretion into the bile. Animal studies indicate that manganese is an essential co-factor for enzymes, such as hexokinase, superoxide dismutase, and xanthine oxidase. However, no case of manganese deficiency in humans has been identified. Manganism is a central nervous system disease first described in the 1800s following exposure to high concentrations of manganese oxides. Manganese madness was the term used to describe the initial psychiatric syndrome (compulsive behavior, emotional lability, hallucinations). More commonly, these workers developed a Parkinson's-like syndrome. Currently, the risks of exposure to low concentrations of manganese in the industrial and in the environmental settings (e.g., methylcyclopentadienyl manganese tricarbonyl in gasoline) are being evaluated with regards to the development of subclinical neuropsychological changes. The American Conference of Governmental and Industrial Hygienists recently lowered the TLV-TWA for manganese compounds and inorganic manganese compounds to 0.2 mg Mn/m3. PMID:10382563

Barceloux, D G

1999-01-01

52

Levels of Arsenic, Cadmium, Lead, Manganese and Zinc in Biological Samples of Paralysed Steel Mill Workers with Related to Controls  

Microsoft Academic Search

The determination of essential trace and toxic elements in the biological samples of human beings is an important clinical\\u000a screening procedure. This study aimed to assess the possible effects of environmental exposure on paralysed male workers (n?=?75) belonging to the production and quality control departments of a steel mill. In this investigation, the concentrations\\u000a of arsenic, cadmium, lead, manganese and

Hassan Imran Afridi; Tasneem Gul Kazi; Atif G. Kazi; Faheem Shah; Sham Kumar Wadhwa; Nida Fatima Kolachi; Abdul Qadir Shah; Jameel Ahmed Baig; Naveed Kazi

53

Identification of high levels of phytochelatins, glutathione and cadmium in the phloem sap of Brassica napus. A role for thiol-peptides in the long-distance transport of cadmium and the effect of cadmium on iron translocation  

PubMed Central

Summary Phytochelatins (PCs) are glutathione-derived peptides that function in heavy metal detoxification in plants and certain fungi. Recent research in Arabidopsis has shown that PCs undergo long-distance transport between roots and shoots. However, it remains unknown which tissues or vascular systems, xylem or phloem, mediate PC translocation and whether PC transport contributes to physiologically relevant long-distance transport of cadmium (Cd) between shoots and roots. To address these questions, xylem and phloem sap were obtained from Brassica napus to quantitatively analyze which thiol species are present in response to Cd exposure. High levels of PCs were identified in the phloem sap within 24 h of Cd exposure using combined mass spectrometry and fluorescence HPLC analyses. Unexpectedly, the concentration of Cd was more than four-fold higher in phloem sap compared to xylem sap. Cadmium exposure dramatically decreased iron levels in xylem and phloem sap whereas other essential heavy metals such as zinc and manganese remained unchanged. Data suggest that Cd inhibits vascular loading of iron but not nicotianamine. The high ratios [PCs]/[Cd] and [glutathione]/[Cd] in the phloem sap suggest that PCs and glutathione (GSH) can function as long-distance carriers of Cd. In contrast, only traces of PCs were detected in xylem sap. Our results suggest that, in addition to directional xylem Cd transport, the phloem is a major vascular system for long-distance source to sink transport of Cd as PC–Cd and glutathione–Cd complexes.

Mendoza-Cozatl, David G.; Butko, Emerald; Springer, Franziska; Torpey, Justin W.; Komives, Elizabeth A.; Kehr, Julia; Schroeder, Julian I.

2010-01-01

54

Iron and cadmium capture gamma-ray photofission measurements  

SciTech Connect

Photofission measurements have been made in {sup 238}U, {sup 232}Th, and {sup 237}Np in iron and cadmium capture gamma-ray spectra in cylindrical neutron-driven gamma-ray sources in the thermal column of the National Bureau of Standards (NBS) Reactor. The gamma-ray source strength was measured with neutron activation foils and by direct counting of activations produced in the metal cylinders. Photofission measurements were made with NBS miniature fission chambers. The integral photofission cross sections were compared with differential measurements by integrating the capture gamma-ray spectra with measured cross-section shapes. The integral cross sections measured in the capture gamma-ray fields are lower than the cross sections calculated from measured differential data.

Williamson, T.G. (Virginia Univ., Charlottesville, VA (USA). Dept. of Nuclear Engineering); Lamaze, G.P.; Gilliam, D.M.; Eisenhauer, C.M. (National Inst. of Standards and Technology, Gaithersburg, MD (USA))

1990-01-01

55

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

USGS Publications Warehouse

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

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

1974-01-01

56

Reversal of cadmium toxicity in a diatom: an interaction between cadmium activity and iron  

SciTech Connect

In batch cultures of Thalassiosira weissflogii subjected to high Cd/sup 2 +/ activities, normal growth rates are resumed when the cadmium ion activity is lowered by either dilution of the medium or addition of a chelating agent (EDTA). Toxicity reversal is possible after up to several days of high (Cd/sup 2 +/) exposure, depending on the initial Cd/sup 2 +/ activity. A sufficiently high ferric ion activity is critical for toxicity reversal; Fe must be added when the Cd/sup 2 +/ activity is decreased by addition of EDTA. The order of Fe and EDTA addition is unimportant for the reversal process. An antagonism between Cd and Fe is clearly indicated, implying that the mechanism of Cd toxicity involves in some way an impairment of iron nutrition.

Foster, P.; Morel, F.M.M.

1982-01-01

57

The influence of iron stores on cadmium body burden in a Thai population.  

PubMed

Cadmium is a toxin of increasing public health concern due to its presence in most human foodstuffs and in cigarette smoke. Exposure to cadmium leads to tissue bioaccumulation and, in particular, has nephrotoxic effects. The aim of the present study was to investigate the association between cadmium body burden and iron stores in a Thai population. A total of 182 healthy adult Thai subjects of both genders (89 males, 93 females) aged between 18 and 57 years and weighing 40-95 kg were included in this study. The total amounts of cadmium excreted in urine over 2 h (microg/g creatinine) were used as an index of long-term cadmium exposure. Quantitation of cadmium was performed using electrothermal (graphite furnace) atomic absorption spectrometry. The urinary cadmium excreted displayed a normal frequency distribution. The average urinary cadmium level did not exceed the WHO maximum tolerable internal dose for the non-exposed population (2 microg/g creatinine). Body iron stores reflected by serum ferritin levels did not show any correlation with cadmium burden in both males and females, although a relatively stronger influence of body iron store status on cadmium burden was shown in females. When the levels of serum ferritin were stratified into five levels (<20, 20-100, 101-200, 201-300, and >300 microg/l), a significant difference in total cadmium body burden was observed between females and males only in the group with a low level of serum ferritin of <20 microg/l. The cadmium body burden in females was about twice that in males in this group. PMID:19806462

Apinan, Roongnapa; Satarug, Soisunwan; Ruengweerayut, Ronnatrai; Mahavorasirikul, Wiratchanee; Na-Bangchang, Kesara

2009-10-06

58

State of adsorption layers of fatty acids on the surfaces of iron, manganese, and copper ferrites  

NASA Astrophysics Data System (ADS)

States of adsorbed substances in surface layers arising during the adsorption of oleic, linoleic, and linolenic acids from carbon tetrachloride, heptane, and cyclohexane solutions on the surfaces of iron, manganese, and copper ferrites, are investigated. Adsorption isotherms and two-dimensional state diagrams of surface layers of iron, manganese, and copper ferrites are obtained experimentally. It is shown that the adsorption of fatty acids from solutions in organic solvents proceeds via filling the volume of the ferrites' porous space with adsorption solutions, while the state of ferrite surface layers changes due to the structural rearrangement of adsorption solutions upon an increase in solute concentration.

Balmasova, O. V.; Ramazanova, A. G.; Korolev, V. V.

2012-07-01

59

Structural and magnetic properties of cadmium substituted manganese ferrites prepared by hydrothermal route  

NASA Astrophysics Data System (ADS)

Cd-substituted manganese ferrite Mn1-xCdxFe2O4 powders with x having values 0.0, 0.1, 0.3 and 0.5 have been synthesized by hydrothermal route at 180 °C in presence of NaOH as mineralizer. The obtained ferrite samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The XRD analysis showed that pure single phases of cubic ferrites were obtained with x upto 0.3. However, sample with x?0.5 showed hexagonal phase of cadmium hydroxide (Cd(OH)2) besides the ferrite phase. The increase in Cd-substitution upto x=0.3 leads to an increase in the lattice parameter as well as the average crystallite size of the prepared ferrites. The average crystallite size increased by increasing the Cd-content and was in the range of 39-57 nm. According to VSM results, the saturation magnetization increased with Cd ion substitution.

Mostafa, Nasser Y.; Zaki, Z. I.; Heiba, Z. K.

2013-03-01

60

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) measurement, and low-temperature photoluminescence spectra, and we also assessed their responses as detectors of radiation exposure. The crystal from the stable growth region proved to be superior to that from the last-to-freeze region; it is a single-grain crystal, free of twins, and displayed a resistivity higher by one order 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})e value was 2.6 x 10{sup -3} cm{sup 2}/V, which is acceptable for thin detectors, including their application in medicine.

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

2010-01-01

61

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

62

Sorption of trace amounts of ruthenium, manganese and europium on iron(III) hydroxide  

Microsoft Academic Search

Summary The effect of pH on the sorption of trace amounts of ruthenium, manganese and europium on iron(III) hydroxide was studied by radiotracer techniques. The effect of amount of sorbent and duration of the contact between the sorbate and the sorbent were also studied. The results indicate that an iron(III) hydroxide precipitate can be used for the preconcentration of traces

R. H. H. Wolf; J. Šipalo-Žuljevi?

1978-01-01

63

Iron and manganese removal in wetland treatment systems: rates, processes and implications for management.  

PubMed

Mine water drainage is a significant environmental problem throughout the world and constructed wetlands are being increasingly used to treat such contaminating discharges. Iron and manganese removal within a wetland treatment system at Whittle Colliery, UK which receives alkaline waters, was monitored to determine rates and processes within the different components of the system. In addition hourly samples were taken for a period of 24 h to determine the effect of photosynthetic organisms on metal removal. Significant iron removal occurred, with removal rates of 98% at Whittle. Oxidation of iron to form iron hydroxide precipitates was the dominant removal process in the proximal sections of the treatment system (i.e. oxidation ponds and initial reaches of the wetland), whereas biotic removal processes appeared to become more important in distal parts of the systems, where iron concentrations were much lower. Significant manganese removal was also observed, although this did not become substantial until iron concentrations had fallen below 5 mg/L. The process by which manganese was removed is not clear, but bacterially-mediated oxidation may be involved. Further elucidation of the relative importance of abiotic and biotic removal processes within treatment systems is important in the design and long-term management of constructed systems. PMID:18281079

Batty, Lesley; Lesley, Batty; Hooley, Daniel; Daniel, Hooley; Younger, Paul; Paul, Younger

2008-02-20

64

Effect of austempering time on mechanical properties of a low manganese austempered ductile iron  

Microsoft Academic Search

An investigation was carried out to examine the influence of austempering time on the resultant microstructure and the room-temperature mechanical properties of an unalloyed and low manganese ductile cast iron with initially ferritic as-cast structure. The effect of austempering time on the plane strain fracture toughness of this material was also studied. Compact tension and round cylindrical tensile specimens were

Susil K. Putatunda; Pavan K. Gadicherla

2000-01-01

65

Effect of iron manganese oxide solid solutions on selectivity for lower hydrocarbons from carbon monoxide hydrogenation  

Microsoft Academic Search

There exists considerable current interest in the study of catalysts that demonstrate high selectivities for Câ-Câ hydrocarbons from carbon monoxide hydrogenation. In this respect iron manganese matrix catalysts have been well studied by a number of authors since Koelbel initially disclosed that these catalysts could give high yields of Câ-Câ hydrocarbons with a corresponding very low methane selectivity. The mechanism

G. J. Hutchings; J. C. A. Boeyens

1986-01-01

66

Purification of phosphoric acid by minimizing iron, copper, cadmium and fluoride  

Microsoft Academic Search

Commercial phosphoric acid manufactured using wet process has been purified by minimizing the iron, cadmium, copper and fluoride content. Bentonite clay is found suitable for removal of humic acids and suspended materials from crude phosphoric acid. An attempt to minimize the iron content by the addition of potassium sulfate, calcium sulfate, sodium sulfate, individually; silicon dioxide+sodium carbonate+potassium sulfate, in combination,

Ahmed A. El-Asmy; Homam M. Serag; Mohammad A. Mahdy; Moustafa I. Amin

2008-01-01

67

Alterations in cellular IRP-dependent iron regulation by in vitro manganese exposure in undifferentiated PC12 cells.  

PubMed

Manganese (Mn) may interfere with iron regulation by altering the binding of iron regulatory proteins (IRPs) to their response elements found on the mRNA encoding proteins critical to iron homeostasis. To explore this, the effects of 24-h in vitro manganese exposure (1, 10, 50, and 200 microM Mn) on: (i) total intracellular and labile iron concentrations; (ii) the cellular abundance of transferrin receptor (TfR), H- and L-ferritin, and mitochondrial aconitase proteins; and (iii) IRP binding to a [32P](-) labeled mRNA sequence of L-ferritin were evaluated in undifferentiated PC12 cells. In vitro manganese exposure altered the cellular abundance of TfR, H-/L-ferritin, and m-aconitase, resulting in an increase in labile iron. This latter effect led to a decrease in IRP binding activity at the lower (10 and 50 microM) manganese exposures. In contrast, 200 microM manganese exposure increased IRP binding, in spite of the significant increase in labile iron. These data indicate that at lower exposures, manganese directly interfered with IRP-dependent translational events, producing an increase in labile iron, which in turn signaled a decrease in IRP binding at 24 h. At higher exposures, the intracellular burden of manganese resulted in overt cytotoxicity and appeared to compromise the normal compensatory response to increased labile iron, producing increased IRP binding. We conclude that low to moderate manganese exposure interferes with cellular iron regulation, and thus may serve as a contributory mechanism underlying manganese neurotoxicity. PMID:12729948

Kwik-Uribe, Catherine L; Reaney, Stephen; Zhu, Zhiwu; Smith, Donald

2003-05-23

68

Blood Manganese Concentration is Elevated in Infants with Iron Deficiency.  

PubMed

The present study was done to determine whether blood Mn concentration is elevated in iron-deficient infants. Thirty-one infants with iron deficiency and thirty-six control subjects (6-24 months of age) were tested for blood Mn concentration, complete blood counts, serum ferritin, and serum iron/transferring iron-binding capacity (Fe/TIBC). All the 31 iron-deficient infants were treated with iron supplement; however, 19 of them underwent blood Mn checkup again in compliance with follow-up schedule when their ferritin levels returned to the normal range. Iron therapies were done for 1-6 months (mean, 2.8; standard deviation, 1.6) using ferric hydroxide-polymaltose complex (6 mg/kg Fe(3+) daily). Infants with iron deficiency had a higher mean blood Mn concentration than controls (2.550 vs. 1.499 ?g/dL, respectively). After iron therapy, the blood Mn levels of iron-deficient infants significantly decreased compared to their pre-therapy levels (2.045 vs. 2.971 ?g/dL, respectively), and their hemoglobin and ferritin levels significantly increased. After adjustment for covariates (e.g., age and breast-feeding), multiple linear regression models showed that increased blood Mn levels were significantly associated with low serum ferritin and hemoglobin levels, whereas with Fe/TIBC there was only a tendency. Our results indicate that iron deficiency increases blood Mn levels in infants, presumably by increasing Mn absorption. PMID:23955423

Park, Sangkyu; Sim, Chang-Sun; Lee, Heun; Kim, Yangho

2013-08-17

69

Molecular characterization of microbial populations in full-scale biofilters treating iron, manganese and ammonia containing groundwater in Harbin, China.  

PubMed

In iron and manganese-containing groundwater treatment for drinking water production, biological filter is an effective process to remove such pollutants. Until now the exact microbial mechanism of iron and manganese removal, especially coupled with other pollutants, such as ammonia, has not been clearly understood. To assess this issue, the performance of a full-scale biofilter located in Harbin, China was monitored over four months. Microbial populations in the biofilter were investigated using T-RFLP and clone library technique. Results suggested that Gallionella, Leptothrix, Nitrospira, Hyphomicrobium and Pseudomonas are dominant in the biofilter and play major roles in the removal of iron, manganese and ammonia. The spatial distribution of microbial populations along the depth of the biofilter demonstrated the stratification of the removal of iron, manganese and ammonia. Additionally, the absence of ammonia-oxidizing bacteria in the biofilter implicated that ammonia-oxidizing archaea might be responsible for the oxidation of ammonia to nitrite. PMID:23994965

Li, Xiang-Kun; Chu, Zhao-Rui; Liu, Ya-Jun; Zhu, Meng-Ting; Yang, Liu; Zhang, Jie

2013-08-09

70

Iron-Mediated Inhibition of Mitochondrial Manganese Uptake Mediates Mitochondrial Dysfunction in a Mouse Model of Hemochromatosis  

PubMed Central

Previous phenotyping of glucose homeostasis and insulin secretion in a mouse model of hereditary hemochromatosis (Hfe?/?) and iron overload suggested mitochondrial dysfunction. Mitochondria from Hfe?/? mouse liver exhibited decreased respiratory capacity and increased lipid peroxidation. Although the cytosol contained excess iron, Hfe?/? mitochondria contained normal iron but decreased copper, manganese, and zinc, associated with reduced activities of copper-dependent cytochrome c oxidase and manganese-dependent superoxide dismutase (MnSOD). The attenuation in MnSOD activity was due to substantial levels of unmetallated apoprotein. The oxidative damage in Hfe?/? mitochondria is due to diminished MnSOD activity, as manganese supplementation of Hfe?/? mice led to enhancement of MnSOD activity and suppressed lipid peroxidation. Manganese supplementation also resulted in improved insulin secretion and glucose tolerance associated with increased MnSOD activity and decreased lipid peroxidation in islets. These data suggest a novel mechanism of iron-induced cellular dysfunction, namely altered mitochondrial uptake of other metal ions.

Jouihan, Hani A; Cobine, Paul A; Cooksey, Robert C; Hoagland, Emily A; Boudina, Sihem; Abel, E Dale; Winge, Dennis R; McClain, Donald A

2008-01-01

71

Iron et al.: Incorporation of Manganese in the Crystal Lattice of Magnetosome Magnetite  

NASA Astrophysics Data System (ADS)

Incorporation of foreign metal into the crystal matrix of the magnetotactic bacterial magnetite has been attempted worldwide. Recently, presence of small amounts of cobalt and manganese in magnetosome magnetite crystals in cultured and uncultured magnetotactic bacteria, respectively, was reported. Magnetization of the uncultured cells and their magnetosomes were not determined, while only marginal changes in the magnetic properties of the cultured cobalt-grown cells and their magnetosomes were observed, however no evidence of incorporation of these metals into the crystalline lattice was presented. We grew cells of a magnetotactic bacterium, Magnetospirillum gryphiswaldense strain MSR-1, in the presence of manganese, ruthenium, zinc and vanadium, of which only manganese was incorporated within the magnetosome magnetite crystals. For the first time we demonstrate that the magnetic properties of magnetite crystals of magnetotactic bacteria can be significantly altered by the incorporation of metal ions, other than iron, in the crystal structure, as signaled by a major shift in the Verwey transition.

Prozorov, Tanya; Perez-Gonzalez, Teresa; Jimenez-Lopez, Concepcion; Mallapragada, Surya K.; Howse, Paul; Bazylinski, Dennis A.; Prozorov, Ruslan

2010-03-01

72

Characteristics of micromorphology and element distribution of iron–manganese cutans in typical soils of subtropical China  

Microsoft Academic Search

The goal of this study was to investigate the characteristics of iron–manganese cutans and to observe information of their pedogenic processes and certain environmental condition changes in the pedogenic process of subtropical Chinese soils. The characteristics of micromorphology of iron–manganese cutans and element distribution with linear microprofiles (i.e., the vertical microprofile from cutan to matrix soil) in Fragiudalfs (FRA), Ferrudalfs

Li Huang; Jun Hong; Wenfeng Tan; Hongqing Hu; Fan Liu; Mingkuang Wang

2008-01-01

73

Upgrading of Low-Grade Manganese Ore by Selective Reduction of Iron Oxide and Magnetic Separation  

NASA Astrophysics Data System (ADS)

The utilization of low-grade manganese ores has become necessary due to the intensive mining of high-grade ores for a long time. In this study, calcined ferruginous low-grade manganese ore was selectively reduced by CO, which converted hematite to magnetite, while manganese oxide was reduced to MnO. The iron-rich component was then separated by magnetic separation. The effects of the various reduction parameters such as particle size, reduction time, temperature, and CO content on the efficiency of magnetic separation were studied by single-factor experiments and by a comprehensive full factorial experiment. Under the best experimental conditions tested, the manganese content in the ore increased from around 36 wt pct to more than 44 wt pct, and almost 50 wt pct of iron was removed at a Mn loss of around 5 pct. The results of the full factorial experiments allowed the identification of the significant effects and yielded regression equations for pct Fe removed, Mn/Fe, and pct Mn loss that characterize the efficiency of the upgrading process.

Gao, Yubo; Olivas-Martinez, M.; Sohn, H. Y.; Kim, Hang Goo; Kim, Chan Wook

2012-12-01

74

Concentrations of cadmium, manganese, copper, zinc, and lead in the tissues of the oyster (Crassostrea iredalei) obtained from Setiu Lagoon, Terengganu, Malaysia  

Microsoft Academic Search

Heavy metals pollution in aquatic environments is a major problem contributing to human health issues. The study of these pollutants through bioindicators such as the oyster Crassostrea iredalei is important for (1) determining the levels and sources and (2) regulating the quantity of pollutants. The concentrations of cadmium (Cd), manganese (Mn), copper (Cu), zinc (Zn), and lead (Pb) in tissues

M. Azlisham; V. J. Vedamanikam; N. A. M. Shazilli

2009-01-01

75

Chlorobenzene oxidation using ozone over iron oxide and manganese oxide catalysts  

Microsoft Academic Search

A low-temperature catalytic oxidation of chlorobenzene (CB) has been performed at temperatures of 60–210°C using ozone (O3) 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 1200ppm ozone results in a remarkable increase in CB conversion and the conversion reaches 91.7% at

Hou Chuan Wang; Hsu Shang Liang; Moo Been Chang

2011-01-01

76

Effect of austempering time on mechanical properties of a low manganese austempered ductile iron  

Microsoft Academic Search

An investigation was carried out to examine the influence of austempering time on the resultant microstructure and the room-temperature\\u000a mechanical properties of an unalloyed and low manganese ductile cast iron with initially ferritic as-cast structure. The effect\\u000a of austempering time on the plane strain fracture toughness of this material was also studied. Compact tension and round cylindrical\\u000a tensile specimens were

Susil K. Putatunda; Pavan K. Gadicherla

2000-01-01

77

Redox cycling of iron and manganese in sediments of the Kalix River estuary, Northern Sweden  

Microsoft Academic Search

Iron and manganese redox cycling in the sediment — water interface region in the Kalix River estuary was investigated by using sediment trap data, pore-water and solid-phase sediment data. Nondetrital phases (presumably reactive Fe and Mn oxides) form substantial fractions of the total settling flux of Fe and Mn (51% of Fetotal and 84% of Mntotal). A steady-state box model

Anders Widerlund; Johan Ingri

1996-01-01

78

INFLUENCE OF AUSTEMPERING TEMPERATURE ON FRACTURE TOUGHNESS OF A LOW MANGANESE AUSTEMPERED DUCTILE IRON (ADI)  

Microsoft Academic Search

The influence of microstructure on the plane strain fracture toughness of an unalloyed, austempered ductile cast iron (ADI) with low manganese content (<0.15 wt %) and with predominantly as-cast (solidified) ferritic structure was studied. Test specimens were austenitized at 927°C (1700°F) for 2 hr and then austempered over a range of temperatures to produce different microstructures. The microstructures were characterized

Susil K. Putatunda

2001-01-01

79

Recalculation, evaluation, and prediction of surface complexation constants for metal adsorption on iron and manganese oxides  

Microsoft Academic Search

The triple-layer model of the oxide\\/water interface can be used to calculate the partitioning of metals among solid and aqueous phases. The defensible use of the triple-layer model in groundwater\\/sediment systems requires an adequate and consistent set of intrinsic adsorption constants. In the present study, published values of p{sup *}K{sup int} for cation adsorption on iron and manganese oxides have

Robert W. Smith; E. A. Jenne

1991-01-01

80

Removal of ammonia, iron and manganese from groundwaters of northern Croatia—pilot plant studies  

Microsoft Academic Search

The removal of iron, manganese and ammonia from groundwater originating from four different locations in northern Croatia was studied. Four pilot plants, mainly differing in their aeration systems and operation pressures, have been used. Quartz sand, coated with a naturally formed layer of MnO2 and a biofilm containing micro-organisms, were used as filter media. The bacteria of the genus Siderocapsa,

Tamara Štembal; Marinko Marki?; Nataša Ribi?i?; Felicita Briški; Laszlo Sipos

2005-01-01

81

Supercritical alkylation and butene dimerization over sulfated zirconia and iron–manganese promoted sulfated zirconia catalysts  

Microsoft Academic Search

Supercritical alkylation and butene dimerization were investigated using sulfated zirconia (SZ) and iron–manganese promoted sulfated zirconia catalysts (SFMZ), as a function of iso-butane\\/olefin (I\\/O) ratio and at temperatures between 60 and 155°C. Detailed product analysis demonstrated that while C8 yields were as high as 80wt.%, neither catalyst produced significant quantities of trimethyl pentanes, although both had high selectivities to dimethyl

A. S Chellappa; R. C Miller; W. J Thomson

2001-01-01

82

Neopentane cracking catalyzed by iron- and manganese-promoted sulfated zirconia  

Microsoft Academic Search

Cracking of neopentane was catalyzed by a sulfated oxide of zirconium promoted with iron and manganese. Reaction at 300–450°C, atmospheric pressure, and neopentane partial pressures of 0.00025–0.005 bar gave methane as the principal product, along with C2 and C3 hydrocarbons, butenes, and coke. The order of reaction in neopentane was determined to be 1, consistent with a monomolecular reaction mechanism

Tsz-Keung Cheung; Julie L. d'Itri; Friederike C. Lange; Bruce C. Gates

1995-01-01

83

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

2013-09-07

84

Effect of iron manganese oxide solid solutions on selectivity for lower hydrocarbons from carbon monoxide hydrogenation  

SciTech Connect

There exists considerable current interest in the study of catalysts that demonstrate high selectivities for C/sub 2/-C/sub 4/ hydrocarbons from carbon monoxide hydrogenation. In this respect iron manganese matrix catalysts have been well studied by a number of authors since Koelbel initially disclosed that these catalysts could give high yields of C/sub 2/-C/sub 4/ hydrocarbons with a corresponding very low methane selectivity. The mechanism by which the manganese component causes these product distributions is at present poorly understood. Recently Jensen and Massoth have proposed that small iron particles are supported on and electronically promoted by MnO. Although these oxide solid solutions have been identified there have been no reported studies that have investigated the effect of these catalyst components on catalyst selectivity. Oxide solid solutions are known to be important as catalysts of a number of reactions involving carbon monoxide. In this note the authors present their initial findings for the effect of iron manganese oxide solid solutions on catalyst selectivity in carbon monoxide hydrogenation. 24 references.

Hutchings, G.J.; Boeyens, J.C.A.

1986-08-01

85

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.

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

86

Effects of zinc, iron and copper deficiencies on cadmium in tissues of Japanese quail. [Coturnix coturnix japonica  

SciTech Connect

Experiments with young Japanese quail were conducted to determine whether combined moderate deficiencies of zinc, iron and copper would cause greater uptake and tissue retention of cadmium than the single deficiencies. Birds were fed the experimental diets containing 62 ppb cadmium from hatching to 16 days of age. On day 9 each bird received a dose of /sup 109/CdCl/sub 2/ in its diet. On day 10, the duodenal and jejunal-ileal tissues contained large amounts of cadmium, and there were many significant effects of treatment on cadmium-109 retention in the livers and kidneys. At day 16, zinc deficiency caused increased cadmium in the liver, whereas iron and copper deficiencies each caused increased cadmium in the kidneys. Combined deficiencies had little or no greater effect than single deficiencies and in some cases the combined effect was less than that of a single deficiency. 13 references, 11 tables.

Fox, M.R.S.; Tao, S.H.; Stone, C.L.; Fry, B.E. Jr.

1984-03-01

87

Iron depletion increases manganese uptake and potentiates apoptosis through ER stress.  

PubMed

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 60mg 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

2013-06-10

88

Mobility of Iron and Manganese within Two Citrus Genotypes after Foliar Applications of Iron Sulfate and Manganese Sulfate  

Microsoft Academic Search

Seedlings of sour orange (Citrus aurantium L.) and Carrizo citrange (C. sinensis L. cv. Washington navel x Poncirus trifoliata)] were grown in plastic pots containing a sand: perlite mixture and watered with a modified Hoagland No 2 nutrient solution throughout the experiment. Three-months-old plants were divided in three groups and sprayed with 0.018 M iron sulfate (FeSO4 7H2O), 0.018 M

Ioannis E. Papadakis; Thomas E. Sotiropoulos; Ioannis N. Therios

2007-01-01

89

The photochemistry of manganese and the origin of banded iron formations  

NASA Astrophysics Data System (ADS)

The origin of the deposition of superior-type Precambrian banded iron formations (BIFs) is investigated in experiments where the effect of UV radiation on dissolved manganese was studied to determine if the commonly accepted photochemical model for BIF formation is consistent with the distribution of Mn in BIFs. Solutions containing 0.56 M NaCl and about 180 microM MnCl2, with or without 3 to 200 microM FeCl2 were irradiated with filtered and unfiltered UV light for up to 8 hrs; the solutions were deaerated and buffered to a pH of 7, and the experiments were conducted under oxygen-free atmosphere. Data on the rate of manganese photooxidation confirmed that a photochemical model for the origin of oxide facies BIFs is consistent with field observations.

Anbar, A. D.; Holland, H. D.

1992-07-01

90

Intestinal absorption of dietary cadmium in women depends on body iron stores and fiber intake.  

PubMed Central

Measurements of intake and uptake of cadmium in relation to diet composition were carried out in 57 nonsmoking women, 20-50 years of age. A vegetarian/high-fiber diet and a mixed-diet group were constructed based on results from a food frequency questionnaire. Duplicate diets and the corresponding feces were collected during 4 consecutive days in parallel with dietary recording of type and amount of food ingested for determination of the dietary intake of cadmium and various nutrients. Blood and 24-hr urine samples were collected for determination of cadmium, hemoglobin, ferritin, and zinc. There were no differences in the intake of nutrients between the mixed-diet and the high-fiber diet groups, except for a significantly higher intake of fiber (p < 0.001) and cadmium (p < 0.002) in the high-fiber group. Fecal cadmium corresponded to 98% in the mixed-diet group and 100% in the high-fiber diet group. No differences in blood cadmium (BCd) or urinary cadmium (UCd) between groups could be detected. There was a tendency toward higher BCd and UCd concentrations with increasing fiber intake; however, the concentrations were not statistically significant at the 5% level, indicating an inhibitory effect of fiber on the gastrointestinal absorption of cadmium. Sixty-seven percent of the women had serum ferritin < 30 micrograms/l, indicating reduced body iron stores, which were highly associated with higher BCd (irrespective of fiber intake). BCd was mainly correlated with UCd, serum ferritin, age, anf fibre intake. UCd and serum ferritin explained almost 60% of the variation in BCd.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 1. Figure 2. Figure 3. A Figure 3. B Figure 4. Figure 5.

Berglund, M; Akesson, A; Nermell, B; Vahter, M

1994-01-01

91

Effect of austempering time on mechanical properties of a low manganese austempered ductile iron  

NASA Astrophysics Data System (ADS)

An investigation was carried out to examine the influence of austempering time on the resultant microstructure and the room-temperature mechanical properties of an unalloyed and low manganese ductile cast iron with initially ferritic as-cast structure. The effect of austempering time on the plane strain fracture toughness of this material was also studied. Compact tension and round cylindrical tensile specimens were prepared from unalloyed ductile cast iron with low manganese content and with a ferritic as-cast (solidified) structure. These specimens were then austempered in the upper (371 °C) and lower (260 °C) bainitic temperature ranges for different time periods, ranging from 30 min. to 4 h. Microstructural features such as type of bainite and the volume fraction of ferrite and austenite and its carbon content were evaluated by X-ray diffraction to examine the influence of microstructure on the mechanical properties and fracture toughness of this material. The results of the present investigation indicate that for this low manganese austempered ductile iron (ADI), upper ausferritic microstructures exhibit higher fracture toughness than lower ausferritic microstructures. Yield and tensile strength of the material was found to increase with an increase in austempering time in a lower bainitic temperature range, whereas in the upper bainitic temperature range, time has no significant effect on the mechanical properties. A retained austenite content between 30 to 35% was found to provide optimum fracture toughness. Fracture toughness was found to increase with the parameter ( X?C?/d)1/2, where X? is the volume fraction of austenite, C? is the carbon content of the austenite, and d is the mean free path of dislocation motion in ferrite.

Putatunda, Susil K.; Gadicherla, Pavan K.

2000-04-01

92

Effect of austempering time on mechanical properties of a low manganese austempered ductile iron  

SciTech Connect

An investigation was carried out to examine the influence of austempering time on the resultant microstructure and the room-temperature mechanical properties of an unalloyed and low manganese ductile cast iron with initially ferritic as-cast structure. The effect of austempering time on the plane strain fracture toughness of this material was also studied. Compact tension and round cylindrical tensile specimens were prepared from unalloyed ductile cast iron with low manganese content and with a ferritic as-cast (solidified) structure. These specimens were then austempered in the upper (371 C) and lower (260 C) bainitic temperature ranges for different time periods, ranging from 30 min. to 3 h. Microstructural features such as type of bainite and the volume fraction of ferrite and austenite and its carbon content were evaluated by X-ray diffraction to examine the influence of microstructure on the mechanical properties and fracture toughness of this material. The results of the present investigation indicate that for this low manganese austempered ductile iron (ADI), upper ausferritic microstructures exhibit higher fracture toughness than lower ausferritic microstructures. Yield and tensile strength of the material was found to increase with an increase in austempering time in a lower bainitic temperature range, whereas in the upper bainitic temperature range, time has no significant effect on the mechanical properties. A retained austenite content between 30 to 35% was found to provide optimum fracture toughness. Fracture toughness was found to increase with the parameter (X{gamma}C{gamma}/d){sup 1/2}, where X{gamma} is the volume fraction of austenite, C{gamma} is the carbon content of the austenite, and d is the mean free path of dislocation motion in ferrite.

Putatunda, S.K.; Gadicherla, P.K.

2000-04-01

93

Interplay between Manganese and Iron in Pneumococcal Pathogenesis: Role of the Orphan Response Regulator RitR  

PubMed Central

Streptococcus pneumoniae (the pneumococcus) is a major human pathogen that is carried asymptomatically in the nasopharynx by up to 70% of the human population. Translocation of the bacteria into internal sites can cause a range of diseases, such as pneumonia, otitis media, meningitis, and bacteremia. This transition from nasopharynx to growth at systemic sites means that the pneumococcus needs to adjust to a variety of environmental conditions, including transition metal ion availability. Although it is an important nutrient, iron potentiates oxidative stress, and it is established that in S. pneumoniae, expression of iron transport systems and proteins that protect against oxidative stress are regulated by an orphan response regulator, RitR. In this study, we investigated the effect of iron and manganese ion availability on the growth of a ritR mutant. Deletion of ritR led to impaired growth of bacteria in high-iron medium, but this phenotype could be suppressed with the addition of manganese. Measurement of metal ion accumulation indicated that manganese prevents iron accumulation. Furthermore, the addition of manganese also led to a reduction in the amount of hydrogen peroxide produced by bacterial cells. Studies of virulence in a murine model of infection indicated that RitR was not essential for pneumococcal survival and suggested that derepression of iron uptake systems may enhance the survival of pneumococci in some niches.

Ong, Cheryl-Lynn Y.; Potter, Adam J.; Trappetti, Claudia; Walker, Mark J.; Jennings, Michael P.; Paton, James C.

2013-01-01

94

Shellac-coated iron oxide nanoparticles for removal of cadmium(II) ions from aqueous solution.  

PubMed

This study describes a new effective adsorbent for cadmium removal from aqueous solution synthesized by coating a shellac layer, a natural biodegradable and renewable resin with abundant hydroxyl and carboxylic groups, on the surface of iron oxide magnetic nanoparticles. Transmission Electron Microscopy (TEM) imaging showed shellac-coated magnetic nanoparticle (SCMN) adsorbents had a core-shell structure with a core of 20 nm and shell of 5 nm. Fourier Transform Infrared Spectroscopic analysis suggested the occurrence of reaction between carboxyl groups on the SCMN adsorbent surface and cadmium ions in aqueous solution. Kinetic data were well described by pseudo second-order model and adsorption isotherms were fitted with both Langmuir and Freundlich models with maximum adsorption capacity of 18.80 mg/g. SCMN adsorbents provided a favorable adsorption capacity under high salinity conditions, and cadmium could easily be desorbed using mild organic acid solutions at low concentration. PMID:23513435

Gong, Jilai; Chen, Long; Zeng, Guangming; Long, Fei; Deng, Jiuhua; Niu, Qiuya; He, Xun

2012-01-01

95

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

96

THEORETICAL TECHNIQUE FOR DETERMINING THE CUMULATIVE IMPACT OF IRON AND MANGANESE OXIDATION IN STREAMS RECEIVING COAL-MINE DISCHARGE.  

USGS Publications Warehouse

Two U. S. Geological Survey computer programs are modified and linked to predict the cumulative impact of iron and manganese oxidation in coal-mine discharge on the dissolved-chemical quality of a receiving stream. The coupled programs calculate the changes in dissolved-iron, dissolved-manganese, and dissolved-oxygen concentrations, and the pH of surface water downstream from the discharge. The cumulative impact of representative discharges from several coal mines on stream quality in a small watershed in southwestern Indiana was simulated to determine the effectiveness and sensitivity of the coupled programs.

Bobay, Keith, E.; Banaszak, Konrad, J.

1985-01-01

97

Microstructure and Mechanical Properties of As-Cast Ductile Irons Alloyed with Manganese and Copper  

NASA Astrophysics Data System (ADS)

The present investigation was carried out to study the effect of manganese and copper addition, singly as well as in combination, on the microstructure, micro-segregation, and mechanical properties of ductile irons. Alloy A (3.18C, 2.64Si, 0.45Mn), alloy B (3.35C, 2.51Si, 0.82Mn), alloy C (3.16C, 2.80Si, 1.08Mn, 0.56Cu), and alloy D (3.18C, 3.00Si, 1.04Mn, 1.13Cu) were melted and cast in the form of Y-block test pieces. The cast microstructures varied from ferrito-pearlitic in alloys A, B, and C to pearlitic in alloy D. However, on XRD analysis and SEM examination, the presence of martensite patches was also detected. There was a marginal decrease in nodule count in alloy B. In alloys C and D, nodule counts were higher, but the proportion of ferrite decreased drastically. Alloy D was found to be the strongest (UTS ? 800 MPa, El = 5%) with alloys A and C coming next in strength; while alloy B was weakest of the four. The presence of martensite patches in association with pearlite appears to be responsible for low toughness of these alloys. Microprobe analysis shows some silicon segregation near the graphite nodules and practically little segregation of manganese. Elemental mapping by FE-SEM does not indicate any manganese segregation.

Dasgupta, Ranjan Kumar; Mondal, Dipak Kumar; Chakrabarti, Ajit Kumar; Ganguli, Ashis Chandra

2012-08-01

98

Determination of cadmium(II), copper(II), manganese(II) and nickel(II) species in Antarctic seawater with complexing resins  

Microsoft Academic Search

The strong species of cadmium(II), copper(II), manganese(II) and nickel(II) in an Antarctic seawater sample are investigated by a method based on the sorption of metal ions on complexing resins. The resins compete with the ligands present in the sample to combine with the metal ions. Two resins with different adsorbing strengths were used. Very stable metal complexes were investigated with

Raffaela Biesuz; Giancarla Alberti; Girolamo D'Agostino; Emanuele Magi; Maria Pesavento

2006-01-01

99

Cadmium uptake in barley affected by iron concentration of the medium: Role of phytosiderophores  

Microsoft Academic Search

Several experiments were conducted using barley (Hordeum vulgare L. cv. Minorimugi) grown hydroponically in a medium containing cadmium (Cd) to clarify the role of phytosiderophores (PS) in chelator-assisted phytoextraction of Cd and the influence of iron (Fe) on Cd uptake. In the first experiment, plants were grown for 7 days in media containing 5 µmol L Cd sulfate (CdSO4), in which the concentration

Kazuaki Kudo; Hiroaki Kudo; Shigenao Kawai

2007-01-01

100

Solid Solution, Mass Transport, and Crystal Growth Studies of Cadmium Iron Selenide.  

NASA Astrophysics Data System (ADS)

Cadmium iron selenide, a semimagnetic semiconductor, has been investigated. Solid solubilities of iron in CdSe were determined at temperatures between 650^ circC and 1100^circC, using the X-ray diffraction Debye-Scherrer powder technique. The solubility limits of Fe in CdSe increase with the temperatures to reach a maximum of about 19.5 mole % FeSe_ {1.24} at 925^circ C, and then decrease with further increasing temperature. Solidification phenomena of the Cd-Fe-Se solid solutions were observed employing optical microscopy, which reveals a typical divorced, eutectic type, nonequilibrium solidification. The combination of the X-ray diffraction and the microscopic investigations yielded a pseudo-binary, eutectic type phase diagram of the Cd-Fe-Se system. Partial pressures of the major vapor species in the Cd-Fe-Se physical and the Cd-Fe-Se-Iodine chemical vapor transport systems were calculated. The partial pressure of gaseous iron species of the PVT system may be neglected compared to those of Cd and Se_2^ecies. This suggests that cadmium iron selenide crystals cannot be grown by the PVT method. For the PVT experiments, using the as-synthesized (CdSe)_ {0.90}(FeSe_{1.24})_{0.10 } source materials, crystals with compositions of 6-8 mole % FeSe_{1.24} were grown at a source temperature of 1000^ circC and a DeltaT of 12^circC. These result are contradictory to the thermodynamic predictions, and were further investigated employing specially purified source materials. Iron contents in the crystals grown in these experiments are close to zero. The transport of iron in the initial mass transport experiments may be due to the chemical impurities (most likely the metal chlorides) in the as-synthesized source materials. Mass transport experiments of the Cd-Fe-Se-Iodine CVT system were performed as a function of source temperatures, the degrees of undercooling (DeltaT), and initial iodine pressures. Promising parameters for the growth of cadmium iron selenide single crystals by the CVT method, e.g., the source temperatures of 800-850 ^circC, initial iodine pressures of 0.5-1.0 atm, and DeltaT of 10 -20^circC, were established. Mass fluxes of cadmium iron selenide were computed using a one -dimensional diffusion equation. The overall trends of the computed mass flux as a function of growth conditions are consistent with the experimental results. However, differences between the theoretical and experimental mass fluxes may be due to the uncertainties of the thermochemical data used and the approximations made in these estimations. Single crystals of cadmium iron selenide with compositions of 6.5-8.5 mole % FeSe_{1.24 } and of about 5 mm edge lengths were successfully grown from the (CdSe)_{0.90 }(FeSe_{1.24})_{0.10} source materials by the CVT method. Compositions of various portions of the bulk crystals are nearly constant along its axis within the error limits, indicating that the crystals possess reasonable compositional uniformity. The indices of the crystal surfaces were obtained by the X -ray diffraction Laue method. The (0001) and (1011) planes usually developed as the natural facets on the surfaces, and (1010) and(1120) as the cleavage planes. A promising chemical etchant for cadmium iron selenide crystals was developed, consisting of about 20 vol. % concentrated HNO_3, 60 vol. % glacial CH _3COOH, and 20 vol. % concentrated H _2SO_4 acids. Etch pit densities of the grown crystals are in the range of 5times10 ^4-rm5times10^5/cm ^2..

Huang, Xuejun

101

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

2012-04-12

102

Stimulation of cyclic AMP production in chick renal tissue by cadmium and manganese.  

PubMed

The effects of cadmium on production of cyclic AMP by partially purified chick renal plasma membrane preparations and binding of 125I-parathyrin to the membranes have been investigated. At certain concentrations Cd2+ ions (and Mn2+ ions) markedly stimulated the production of cyclic AMP by the tissue. It was found that concentrations of Cd2+ roughly in the same range were also capable of stimulating binding of 125I-parathyrin to the membrane preparations. PMID:2995580

Cook, D B; Dewar, J H; Ershadi, S S

1985-07-01

103

Uptake of iron, zinc, manganese, and copper by seedlings of hybrid and traditional rice cultivars from different soil types  

Microsoft Academic Search

In pot experiments, uptake of zinc (Zn), copper (Cu), iron (Fe), and manganese (Mn) by hybrid rice from different soil types was compared with a traditional rice (Oryza sativa L.) cultivar. The concentration and total uptake of Fe in the shoots of hybrid rice grown in Oxisol and Ultisol were lower than those of the traditional cultivar. The concentration and

X. Yang; V. Römheld; H. Marschner

1994-01-01

104

Olefin epoxidation and alkane hydroxylation catalyzed by robust sulfonated manganese and iron porphyrins supported on cationic ion-exchange resins  

Microsoft Academic Search

Robust sulfonated manganese and iron porphyrin supported on poly(vinylpyridinium) polymers have been used as catalysts in olefin epoxidation and alkane hydroxylation by iodosylbenzene. The metalloporphyrins are attached to protonated or methylated poly(vinylpyridine) polymers by the coordination of one pyridine unit, thus providing a proximal effect, and by additional interactions of the porphyrin sulfonato groups with the polymer pyridinium units. The

Sandro Campestrini; Bernard Meunier

1992-01-01

105

Group concentration and atomic-absorption determination of iron, manganese, Zinc, Copper, Cobalt, and nickel in powdered molybdenum and tungsten  

SciTech Connect

This paper proposes a rapid, selective, and simple method for the group concentration and separation of trace concentrations (n /SUP ./ 10/sup -4/%) of iron (III), manganese (II), zinc (II), copper (II), cobalt (II), and nickel (II) from powdered molybdenum and tungsten using the polymeric chelate sorbent polystyrene-methyleneiminino-4-nitro-6-sulfophenol.

Basargin, N.N.

1986-08-01

106

The Effect of Heat Treatment on the Ferromagnetic Resonance of Lutecium Iron Garnet and Manganese Ferrite Single Crystals.  

National Technical Information Service (NTIS)

In this paper, the Effects of different heat treatments on the ferromagnetic resonance of lutecium iron garnet (Lu3Fe5O12) and manganese ferrite (MnFe2O4) single crystals are investigated. The two heat treatments applied are, respectively, 700C in air for...

L. Guo-dong T. Sheng-shu

1966-01-01

107

Genotoxic effects of aluminum, iron and manganese in human cells and experimental systems: A review of the literature  

Microsoft Academic Search

There is considerable evidence indicating an increase in neurodegenerative disorders in industrialized countries. The clinical symptoms and the possible mutagenic effects produced by acute poisoning and by chronic exposure to metals are of major interest. This study is a review of the data found concerning the genotoxic potential of three metals: aluminum (Al), iron (Fe) and manganese (Mn), with emphasis

PDL Lima; MC Vasconcellos; RC Montenegro; MO Bahia; ET Costa; LMG Antunes; RR Burbano

2011-01-01

108

[Acid mining drainage impacts on the separation between iron and manganese in sediments of the Aha Lake, Guizhou Province].  

PubMed

Since the Aha Lake, located in Guizhou Province, China, was enlarged in 1982, a great amount of iron and manganese were input into it owing to the uninterrupted pollution from acidic mining drainage of coal mines (AMD). The results show that dissolved Fe2+ and Mn2+, mainly from AMD, were markedly separated each other as water flowed from inlet to downstream. The Aha lake water, with the average pH equal to 7.28, was not acidified just because the lake is developed in the karst area and people continuously put lime in it in recent years. Fe2 + and Mn2 + deposit in the different locations in lake because of the difference of oxidizing rate between Fe2+ and Mn2+ during water flowing from inlet to downstream, and also forming the horizontal separation along the lake water flowing direction. Manganese tends to be obviously enriched in the upper of sediment in lake's deep locations, presenting the remarkable separation with iron in the vertical section. After normalized by Ti content in sediment, it is obvious that the remarkable separation between iron and manganese corresponds with the enlargement of lake in 1982. As shown in the concentration profile of pore water in sediment, iron was remobilized weakly while manganese reduction mainly happens in the upper of sediment, indicating its strong remobilization. Based on the studies, a mechanism for environment and fractionation of Fe2+ /Mn2 + during water flowing in the lake was also demonstrated. PMID:15859425

Wang, Fu-shun; Liu, Cong-qiang; Liang, Xiao-bin; Wei, Zhong-qin; Li, Jun

2005-01-01

109

Manganese: A transition metal protects nigrostriatal neurons from oxidative stress in the iron-induced animal model of Parkinsonism  

Microsoft Academic Search

It has been suggested that transition metals such as iron and manganese produce oxidative injury to the dopaminergic nigrostriatal system, which may play a critical role in the pathogenesis of Parkinson's disease. Intranigral infusion of ferrous citrate (0 to 8.4 nmol, i.n.) acutely increased lipid peroxidation in the substantia nigra and dopamine turnover in the caudate nucleus. Subsequently, it caused

I. Sziráki; K. P. Mohanakumar; P. Rauhala; H. G. Kim; K. J. Yeh; C. C. Chiueh

1998-01-01

110

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

111

The relationship between body iron stores and blood and urine cadmium concentrations in US never-smoking, non-pregnant women aged 20-49 years  

SciTech Connect

Background: Cadmium is a ubiquitous environmental pollutant associated with increased risk of leading causes of mortality and morbidity in women, including breast cancer and osteoporosis. Iron deficiency increases absorption of dietary cadmium, rendering women, who tend to have lower iron stores than men, more susceptible to cadmium uptake. We used body iron, a measure that incorporates both serum ferritin and soluble transferrin receptor, as recommended by the World Health Organization, to evaluate the relationships between iron status and urine and blood cadmium. Methods: Serum ferritin, soluble transferrin receptor, urine and blood cadmium values in never-smoking, non-pregnant, non-lactating, non-menopausal women aged 20-49 years (n=599) were obtained from the 2003-2008 National Health and Nutrition Examination Surveys. Body iron was calculated from serum ferritin and soluble transferrin receptor, and iron deficiency defined as body iron <0 mg/kg. Robust linear regression was used to evaluate the relationships between body iron and blood and urine cadmium, adjusted for age, race, poverty, body mass index, and parity. Results: Per incremental (mg/kg) increase in body iron, urine cadmium decreased by 0.003 {mu}g/g creatinine and blood cadmium decreased by 0.014 {mu}g/L. Iron deficiency was associated with 0.044 {mu}g/g creatinine greater urine cadmium (95% CI=0.020, 0.069) and 0.162 {mu}g/L greater blood cadmium (95% CI=0.132, 0.193). Conclusions: Iron deficiency is a risk factor for increased blood and urine cadmium among never-smoking, pre-menopausal, non-pregnant US women, independent of age, race, poverty, body mass index and parity. Expanding programs to detect and correct iron deficiency among non-pregnant women merits consideration as a potential means to reduce the risk of cadmium associated diseases. - Highlights: {yields} Body iron was calculated from serum ferritin and soluble transferrin receptor. {yields} Body iron was inversely associated with blood and urine cadmium in US women. {yields} Inverse associations with blood cadmium were evident in all race/ethnic subsamples. {yields} Inverse associations with urine cadmium were evident in women of other/multi-race. {yields} Black women had lower mean body iron compared to white women.

Gallagher, Carolyn M., E-mail: 2crgallagher@optonline.net [PhD Program in Population Health and Clinical Outcomes Research, Stony Brook University, NY (United States) and Department of Preventive Medicine, Stony Brook University, Z-8036, Level 3, HSC, Stony Brook, NY 11794-8036 (United States); Chen, John J.; Kovach, John S. [Department of Preventive Medicine, Stony Brook University, Z-8036, Level 3, HSC, Stony Brook, NY 11794-8036 (United States)] [Department of Preventive Medicine, Stony Brook University, Z-8036, Level 3, HSC, Stony Brook, NY 11794-8036 (United States)

2011-07-15

112

Levels of arsenic, cadmium, lead, manganese and zinc in biological samples of paralysed steel mill workers with related to controls.  

PubMed

The determination of essential trace and toxic elements in the biological samples of human beings is an important clinical screening procedure. This study aimed to assess the possible effects of environmental exposure on paralysed male workers (n?=?75) belonging to the production and quality control departments of a steel mill. In this investigation, the concentrations of arsenic, cadmium, lead, manganese and zinc were determined in biological samples (blood, urine and scalp hair samples) of exposed paralysis and non-paralysed steel mill workers. For comparative purposes, unexposed healthy subjects of same age group were selected as referents. The elements in the biological samples were measured by atomic absorption spectrophotometry prior to microwave-assisted acid digestion. The validity of the methodology was checked by the biological certified reference materials. The results indicate that the level understudy elements in all three biological samples were significantly higher in paralysed workers of both groups (quality control and production) as compared to referents (p?

Afridi, Hassan Imran; Kazi, Tasneem Gul; Kazi, Atif G; Shah, Faheem; Wadhwa, Sham Kumar; Kolachi, Nida Fatima; Shah, Abdul Qadir; Baig, Jameel Ahmed; Kazi, Naveed

2011-05-06

113

Single pot synthesis of pyridine-N-oxide based polymeric complexes of cadmium and manganese: Crystal structure and luminescence property  

NASA Astrophysics Data System (ADS)

Two new polymeric complexes of cadmium(II) and manganese(II) with Pyridine-N-oxide (pyo) mediated by thiocyanate and dicyanamide (dca) anions have been synthesized and characterized by X-ray single crystal structure analysis. The structural analyses reveal that complexes [Cd(pyo)2(SCN)2]n (1) and [Mn(pyo)2(dca)2]n (2) [where, pyo = pyridine-N-oxide; dca = dicyanamide] are 2D coordination polymers. In complex 1 hexa-coordinated Cd(II) centers posses distorted octahedral coordination environments. Each Cd(II) is coordinated by four SCN- in end to end fashion forming a zigzag chain and two pyo monodentate ligands bridge two adjacent Cd(II) centers leading to a two-dimensional sheet structure. In complex 2 hexa-coordinated Mn(II) centers posses octahedral coordination environments. The coordination polymer constitute a 2D polymeric sheet and has a (4, 4) grid network architecture Successive stacking of coordination polymeric sheets are enforced by inter layer OH\\ctdot O and OH\\ctdot N hydrogen bonding. The luminescence properties of these two polynuclear complexes in solid state were studied and complex 1 exhibits higher luminescence intensity than 2.

Mondal, Sandip; Guha, Averi; Suresh, Eringathodi; Jana, Atish Dipankar; Banerjee, Arpita

2012-12-01

114

Deriving freshwater quality criteria for copper, cadmium, aluminum and manganese for protection of aquatic life in Malaysia.  

PubMed

Freshwater quality criteria for copper (Cu), cadmium (Cd), aluminum (Al), and manganese (Mn) were developed with particular reference to aquatic biota in Malaysia, and based on USEPA's guidelines. Acute toxicity tests were performed on eight different freshwater domestic species in Malaysia, which were Macrobrachiumlanchesteri (prawn), two fish -Poeciliareticulata and Rasborasumatrana, Melanoidestuberculata (snail), Stenocyprismajor (ostracod), Chironomusjavanus (midge larvae), Naiselinguis (annelid), and Duttaphrynusmelanostictus (tadpole), to determine 96-h LC50 values for Cu, Cd, Al, and Mn. The final acute values (FAVs) for Cu, Cd, Al, and Mn were 2.5, 3.0, 977.8, and 78.3 ?gL(-1), respectively. Using an estimated acute-to-chronic ratio (ACR) of 8.3, the value for final chronic value (FCV) was derived. Based on FAV and FCV, a Criterion Maximum Concentration (CMC) and a criterion Continuous Concentration (CCC) for Cu, Cd, Al, and Mn of 1.3, 1.5, 488.9, and 39.1 ?gL(-1) and 0.3, 0.36, 117.8, and 9.4 ?gL(-1), respectively, were derived. The results of this study provide useful data for deriving national or local water quality criteria for Cu, Cd, Al, and Mn based on aquatic biota in Malaysia. Based on LC50 values, this study indicated that R.sumatrana, M.lanchesteri, C.javanus, and N.elinguis were the most sensitive to Cu, Cd, Al, and Mn, respectively. PMID:23246727

Shuhaimi-Othman, M; Nadzifah, Y; Nur-Amalina, R; Umirah, N S

2012-12-13

115

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

Microsoft Academic Search

Manganese oxidation products were precipitated in an aerated open-aqueous system where a continuous influx of mixed Mn{sup 2+} and Cd{sup 2+} 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 CdâMnâ{sup 4+}Oâ, Mnâ{sup 2+}Mnâ{sup 4+}Oâ, MnOâ (ramsdellite), and CdCOâ. Mean oxidation numbers of

J. D. Hem; C. J. Lind

1991-01-01

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

2013-04-25

117

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

118

Sources and leaching of manganese and iron in the Saigon River Basin, Vietnam.  

PubMed

High concentrations of manganese and iron in the Saigon River are major problems for the water supply in Ho Chi Minh City (HCMC), Viet Nam. To identify their sources and leaching processes, we surveyed water quality along the Saigon River and ran batch leaching tests using soil and sediment samples. Two important leaching processes were identified: acidic leaching from acid sulfate soil (ASS) in the middle reaches of the river, and Mn dissolution and Fe reduction from sediments in the downstream reaches. Low pH caused the concurrent release of Fe and Mn from the ASS. In contrast, anoxia caused the release of Fe but not Mn from the sediments, whereas low pH facilitated Mn dissolution. Sediments are a more important source of Mn because of their higher Mn contents (10 times) and release rates (14 times) than those from ASS. PMID:21977643

Ha, Nguyen Thi Van; Takizawa, Satoshi; Oguma, Kumiko; Phuoc, Nguyen Van

2011-01-01

119

Lead-210, polonium-210, manganese and iron in the Cariaco Trench  

NASA Astrophysics Data System (ADS)

Measurements of temperature, salinity, dissolved oxygen, sulfide, 226Ra, Mn, Fe, 210Pb, 210Po, and total suspended matter from three cruises of R.V. Atlantis II in the Cariaco Trench are reported. Distributions of dissolved and particulate Mn and Fe are similar to those for the Black Sea and reflect similar diffusion and redox-potential controls. Results for 210Pb and 226Ra in the anoxic deep water indicate a residence time for 210Pb in solution of less than two years. Particulate 210Pb results suggest that removal occurs largely by incorporation into metal sulfide phases forming in the water column. There is also evidence for precipitation of 210Pb with manganese oxide or iron hydroxide just above the O 2-H 2S interface. In the upper 300 m, 210Po is enriched by 55% over radioactive equilibrium with 210Pb. Possible sources of this excess include the bottom sediments and the water upwelling along the Venezuelan coast.

Bacon, Michael P.; Brewer, Peter G.; Spencer, Derek W.; Murray, James W.; Goddard, John

1980-02-01

120

Management of dietary essential metals (iron, copper, zinc, chromium and manganese) by Wistar and Zucker obese rats fed a self-selected high-energy diet  

Microsoft Academic Search

The balances and content of essential elements (iron, copper, zinc, chromium and manganese) in the body of Wistar, Zucker lean and Zucker obese rats fed a reference or cafeteria diet from day 30 to 60 after birth have been studied. Intestinal iron absorption compensated for low iron content of the cafeteria diet and the extra needs of growth and fat

José-Antonio Fernández-López; Montserrat Esteve; Immaculada Rafecas; Xavier Remesar; Marià Alemany

1994-01-01

121

Adsorption of copper, cadmium, lead and zinc onto a synthetic manganese oxide.  

PubMed

Due to its simple and inexpensive synthesis, a new amorphous hydrous manganese oxide (AMO) has been studied as a possible chemical stabilizing agent for soils contaminated with metals. Preliminary experiments evaluating the stability of AMO in pure water have reported only minor dissolution (5.70% and 0.24% depending on the w/v ratio). Sorption kinetics have shown fast metal adsorption, especially for Pb. The sorption capacities of AMO for Cu, Cd, Pb, and Zn have been described and compared with synthetic birnessite for pH 4 and 5.5. Both oxides show similar sorption capacities at pH 4 despite the fact that birnessite characteristics (pH of zero point charge, specific surface area and cation exchange capacity) are more favorable for metal sorption. Moreover, the pH adsorption-edges show that the AMO is more pH-dependent than birnessite. PMID:23566588

Della Puppa, Loïc; Komárek, Michael; Bordas, François; Bollinger, Jean-Claude; Joussein, Emmanuel

2013-02-27

122

Ueber Mangandaubreelith in den Troilitknollen des Odessa-Eisenmeteorits (The Manganese Daubreelite in the Troilite Nodules of the Odessa-Iron Meteorite).  

National Technical Information Service (NTIS)

In the troilite inclusions of the available piece of the Odessa iron meteorite, the authors have found, by means of an electron-beam microprobe, manganese daubreelite. The inclusions consist of a nucleus of troilite surrounded by graphite, schreibersite a...

W. Kiesl H. H. Weinke

1969-01-01

123

Sedimentary profiles and sediment-water solute exchange of iron and manganese in reef and river-dominated shelf regions of the Coral Sea  

Microsoft Academic Search

Vertical profiles and sediment-water solute exchange of iron and manganese were measured in reef- (central Great Barrier Reef Lagoon) and river-dominated (Fly Delta-Gulf of Papua) shelf regions of the Coral Sea. Solid-phase iron and manganese concentrations were greater in the Papuan deposits (Fe range: 42.8 98.3 mg g-1 sediment DW; Mn range: 423 2500 mug g-1 DW) than in the

Daniel M. Alongi; Frank Tirendi; Paul Christoffersen

1993-01-01

124

Metals, oxidative stress and neurodegeneration: a focus on iron, manganese and mercury.  

PubMed

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 review 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, João Batista Teixeira; Aschner, Michael

2012-12-21

125

Long-term removal and retention of iron and manganese from acidic mine drainage by wetlands. Volume 2. Tarutis thesis. Final report, July 1987-January 1990  

SciTech Connect

The behavior of sedimentary iron and manganese in a volunteer wetland receiving mine drainage on a reclaimed coal surface mine in Pennsylvania was characterized to determine if these metals can be retained in the sediments. Five metal fractions sensitive to changes in environmental conditions were examined. The potential for the association of iron and manganese with organic carbon and sulfur was studied to evaluate diagenetic changes important to metal cycling in wetland sedimentary environments. The aerobic zone was characterized by an abundance of iron and manganese oxides, organic carbon, and sulfur in the sediment, and virtually no dissolved iron and manganese in the interstitial water. The anaerobic zone was characterized by relatively low levels of iron and manganese oxides and a concomitant increase of dissolved iron and manganese in the interstitial water. The low concentration of metal sulfides and the high carbon/sulfur ratios observed suggest that sulfate reduction was a relatively unimportant process for metal removal. In the wetland studied, the aerobic zone was more important in metal retention than the anaerobic zone based on the results of multivariate analysis.

Brooks, R.P.; Unz, R.F.; Davis, L.K.; Tarutis, W.J.; Yanchunas, J.

1990-01-01

126

Variation in Manganese and Iron Accumulation Among Soybean Genotypes Growing on Hydroponic Solutions of Differing Manganese and Nitrate Concentrations  

Microsoft Academic Search

Manganese (Mn) is an essential element of plant growth and has been identified as a cofactor in soybean (Glycine max Merr.) leaves for catabolism of ureides, which are the main products of nitrogen fixation transported from nodules to shoot. Variations among genotypes were observed in the rate of ureide catabolism when plants were grown in nutrient solutions deficient in Mn.

Maria Luisa Izaguirre-Mayoral; Thomas R. Sinclair

2005-01-01

127

Olefin epoxidation and alkane hydroxylation catalyzed by robust sulfonated manganese and iron porphyrins supported on cationic ion-exchange resins  

SciTech Connect

Robust sulfonated manganese and iron porphyrin supported on poly(vinylpyridinium) polymers have been used as catalysts in olefin epoxidation and alkane hydroxylation by iodosylbenzene. The metalloporphyrins are attached to protonated or methylated poly(vinylpyridine) polymers by the coordination of one pyridine unit, thus providing a proximal effect, and by additional interactions of the porphyrin sulfonato groups with the polymer pyridinium units. The best catalysts are the complexes containing halogen atoms at the pyrrole [beta]-positions. In all these oxygenation reactions manganese porphyrins are better catalysts than the corresponding iron complexes. From comparative studies with another ion-exchange resin without a potential axial ligand, it can be noted that the concept of the proximal effect is a key factor in metalloporphyrin-catalyzed reactions, not only for soluble complexes but also for supported catalysts.

Campestrini, S.; Meunier, B. (CNRS, Toulouse (France))

1992-05-27

128

Iron, cadmium, and chromium in seagrass (Thalassia testudinum) from a coastal nature reserve in karstic Yucatán.  

PubMed

The management of protected areas in karstic regions is a challenge because flooded cave systems form there and provide underground hydrological conducts that may link different zones. As a consequence, affectations to the protected areas can possibly occur as a consequence of human activities in remote areas and may therefore pass undetected. Thus, the monitoring of possible contaminants in these regions is becoming imperative. In this work, we analyze the concentration of essential (iron) and non-essential metals (cadmium and chromium) in the seagrass Thalassia testudinum that grows in Yalahau Lagoon, located in a near-to-pristine protected area of the Yucatán Peninsula, close to the rapidly developing touristic belt of the Mexican Caribbean. Salinity and silicate patterns show that Yalahau is an evaporation lagoon, where groundwater discharge is important. High iron (> 400 ?g/g), cadmium (>4 ?g/g), and chromium (? 1 ?g/g) concentrations were found in the area of highest groundwater input of the lagoon. High levels (5.1 ?g/g) were also found near the town dump. In the rest of the sampling sites, metal concentrations remained near to background levels as estimated from other works. Temporal changes of concentrations in the seagrass tissues show also a local input and an input from the groundwater that could provoke an environmental problem in the Yalahau Lagoon in the near future. PMID:23404548

Avelar, Mayra; Bonilla-Heredia, Blanca; Merino-Ibarra, Martín; Herrera-Silveira, Jorge A; Ramirez, Javier; Rosas, Humberto; Valdespino, Job; Carricart-Ganivet, Juan P; Martínez, Ana

2013-02-13

129

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.

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

2011-01-01

130

A Predictive Regression Model for the Geochemical Variability of Iron and Manganese in a Coral Reef Ecosystem  

Microsoft Academic Search

This article focuses on the influence of nutrient forms (nitrogen\\/phosphorous forms) and parameters like pH and organic carbon in the distributional characteristics of two important trace metals, viz. iron and manganese, in different sedimentary microenvironments of coral reef ecosystem of Lakshadweep Archipelago. Positive correlations of Fe\\/Mn with nutrient forms attributes to a similar pattern of remineralization and depositional characteristics involved

Anu Gopinath; N. C. Kumar; K. V. Jayalakshmi; D. Padmalal; S. M. Nair

2005-01-01

131

Effect of reducing agents on microstructure and catalytic performance of precipitated iron-manganese catalyst for Fischer–Tropsch synthesis  

Microsoft Academic Search

Effects of reducing agents on the textural properties and bulk\\/surface phase compositions of a precipitated iron-manganese catalyst were investigated by N2-physisorption, X-ray photoelectron spectroscopy (XRD), Mössbauer effect spectroscopy (MES), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (LRS). Fischer–Tropsch synthesis (FTS) was performed in a slurry-phase continuously stirred tank reactor. The characterization results indicated that the hematite in the fresh catalyst

Mingyue Ding; Yong Yang; Baoshan Wu; Tiejun Wang; Hongwei Xiang; Yongwang Li

2011-01-01

132

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

Microsoft Academic Search

Three samples of manganese associated hydrous iron(III) oxide (MNHFO), prepared by incinerating metal hydroxide precipitate at T (±5)=90, 300 and 600°C, showed increase of crystalline nature in XRD patterns with decreasing As(III) removal percentages. TEM images showed the increase of crystallinity from sample-1 (MNHFO-1) to sapmple-3 (MNHFO-3). Dimensions (nm) of particles estimated were 5.0, 7.0 and 97.5. Optimization of pH

Kaushik Gupta; Arjun Maity; Uday Chand Ghosh

2010-01-01

133

Chromium–manganese iron alloy system design cast in metal and sand moulds for erosion resistance: a positron lifetime study  

Microsoft Academic Search

Erosion characteristics of high chromium (Cr, 16–19%) alloy cast iron with 5% and 10% manganese (Mn) prepared in metal and\\u000a sand moulds through induction melting are investigated using jet erosion test setup in both as-cast and heat-treated conditions.\\u000a The samples were characterised for hardness and microstructural properties. A new and novel non-destructive evaluation technique\\u000a namely positron lifetime spectroscopy has also

P. Sampathkumaran; C. Ranganathaiah; S. Seetharamu; Kishore

2011-01-01

134

The Relationship Between the Diagenetic Cycles of Reducible Iron and Manganese Oxides and Dissolved Organic Carbon (DOC)  

NASA Astrophysics Data System (ADS)

Field evidence suggests that the fate of sedimentary DOC is intimately linked to the diagenetic cycles of iron and manganese in marine sediments. Co-variations of their concentrations in sediment pore water [1], as well as the release of DOC upon the reductive dissolution of authigenic iron and manganese oxides [1] suggest that sorption (i.e., co-precipitation and/or adsorption) onto these oxides may play an important role on the diagenetic behavior of DOC. Whereas the diagenetic cycling of iron and manganese between oxic and suboxic sediments is well documented, DOC pore water gradients have most often been interpreted uniquely as indicative of a flux of DOC out of the sediments to the overlying bottom waters [2-5]. This interpretation stems from our inability to resolve a subsurface DOC sink from the vertical distribution of sedimentary particulate organic carbon (POC). This DOC sink, if it exists, would considerably alter our views of the mechanisms that regulate DOC fluxes across the sediment-water interface as well as their quantification. Sorption onto authigenic metal oxides may also lead to a molecular and isotopic fractionation of DOC. Furthermore, if DOC sorption to metal oxides is a reversible process, it may buffer pore water DOC concentrations and release to the overlying waters. Oxic surface sediments recovered from the St. Lawrence Estuary and the Saguenay Fjord were incubated under anaerobic conditions and extracted with a mild reducing agent to determine the amount and composition (molecular and isotopic) of the DOC associated with the authigenic iron and manganese oxides. Preliminary results from the study will be presented. References: [1] Deflandre et al. (2002) Geochim. Cosmochim. Acta, 66; 14, 2547-2558. [2] Alperin et. al., (1999) Geochim. Cosmochim. Acta, 63; 3-4, 427-448. [3] Burdige et al., (1999) Geochim. Cosmochim. Acta, 63; 10, 507-1515. [4] Holcombe et al., (2001) Limnol. Oceanogr., 46; 2, 298-308. [5] Papadimitriou et. al. (2002) Mar. Chem., 79, 37-47.

Barazzuol, L. N.; Mucci, A.; Gélinas, Y.

2004-05-01

135

Activation of Ethane in the Presence of Solid Acids: Sulfated Zirconia, Iron and Manganese-Promoted Sulfated Zirconia, and Zeolites  

Microsoft Academic Search

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°C, and ethane partial pressures in the range 0.01–0.2 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.

Tsz-Keung Cheung; Bruce C. Gates

1997-01-01

136

Removal of As(III) in a column reactor packed with iron-coated sand and manganese-coated sand  

Microsoft Academic Search

The applicability of manganese-coated sand (MCS) and iron-coated sand (ICS) for the treatment of As(III) via oxidation and adsorption processes was investigated. Scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to observe the surface properties of the coated layer. In the batch adsorption, the adsorption rate of As(V) onto ICS was greater than that of As(III), and

Yoon-Young Chang; Ki-Hoon Song; Jae-Kyu Yang

2008-01-01

137

Effects of vanadium- and iron-doping on crystal morphology and electrochemical properties of 1D nanostructured manganese oxides  

Microsoft Academic Search

One-dimensional (1D) nanostructures of vanadium- and iron-doped manganese oxides, Mn1?xMxO2 (M=V and Fe), are synthesized via one-pot hydrothermal reactions. The results of X-ray diffraction studies and electron microscopic analyses demonstrate that all the present 1D nanostructured materials possess ?-MnO2-type structure. While the vanadium dopants produce 1D nanorods with a smaller aspect ratio of ?3–5, iron dopants produce 1D nanowires with

Ha Na Yoo; Dae Hoon Park; Seong-Ju Hwang

2008-01-01

138

Zinc, lead and cadmium accumulation and tolerance in Typha latifolia as affected by iron plaque on the root surface  

Microsoft Academic Search

The effects of iron plaque on the growth of Typha latifolia L. and its accumulation of zinc (Zn), lead (Pb) and cadmium (Cd) were investigated under field conditions and in nutrient solution cultures in the laboratory. In the field, Zn concentrations (but not Cd) on the root surface were positively related to Fe concentrations on the root surface. In the

Zhihong Ye; Alan J. M Baker; Ming-Hung Wong; Arthur J Willis

1998-01-01

139

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

140

Iron deficient and manganese supplemented diets alter metals and transporters in the developing rat brain.  

PubMed

Manganese (Mn) neurotoxicity in adults can result in psychological and neurological disturbances similar to Parkinson's disease, including extrapyramidal motor system defects and altered behaviors. Iron (Fe) deficiency is one of the most prevalent nutritional disorders in the world, affecting approximately 2 billion people, especially pregnant and lactating women, infants, toddlers, and adolescents. Fe deficiency can enhance brain Mn accumulation even in the absence of excess Mn in the environment or the diet. To assess the neurochemical interactions of dietary Fe deficiency and excess Mn during development, neonatal rats were exposed to either a control diet, a low-Fe diet (ID), or a low-Fe diet supplemented with Mn (IDMn) via maternal milk during the lactation period (postnatal days [PN] 4-21). In PN21 pups, both the ID and IDMn diets produced changes in blood parameters characteristic of Fe deficiency: decreased hemoglobin (Hb) and plasma Fe, increased plasma transferrin (Tf), and total iron binding capacity (TIBC). Treated ID and IDMn dams also had decreased Hb throughout lactation and ID dams had decreased plasma Fe and increased Tf and TIBC on PN21. Both ID and IDMn pups had decreased Fe and increased copper brain levels; in addition, IDMn pups also had increased brain levels of several other essential metals including Mn, chromium, zinc, cobalt, aluminum, molybdenum, and vanadium. Concurrent with altered concentrations of metals in the brain, transport proteins divalent metal transporter-1 and transferrin receptor were increased. No significant changes were determined for the neurotransmitters gamma aminobutyric acid and glutamate. The results of this study confirm that there is homeostatic relationship among several essential metals in the brain and not simply between Fe and Mn. PMID:17060373

Garcia, Stephanie J; Gellein, Kristin; Syversen, Tore; Aschner, Michael

2006-10-23

141

Copper, iron, manganese, and zinc content of hair from two populations of rhesus monkeys.  

PubMed

The concentrations of the elements copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) in hair of caged (in Maryland) and free-ranging (in Puerto Rico) rhesus monkey populations were determined. Significant chronological age-related decreases were evident for the trace elements Mn and Zn in both populations (P < or = 0.01) and for Cu and Fe in free-ranging monkeys (P < or = 0.005). The only overall gender difference was higher hair Mn concentration in free-ranging males than in females (P < 0.03). There were no significant differences in hair Cu, Fe, or Mn related to pregnancy status. Hair Zn was lower in samples from pregnant than from nonpregnant monkeys from the caged monkeys (P < or = 0.05), but did not differ in the free-ranging monkeys. Comparison of the two populations revealed that hair Zn levels were significantly higher in caged vs free-ranging animals (P < 0.001). We attribute this higher hair Zn in the caged monkeys to contact and ingestion of Zn from their galvanized enclosures. Hair iron levels were significantly higher (P < 0.001) in free-ranging monkeys, possibly as a result of Fe-rich soil ingestion from their environment. These data support continued investigation of the use of hair as an indicator of the exposure of large groups or populations to potentially high levels of specific minerals, and the use of nonhuman primates as models for the study of trace element deficiency and/or toxicity in humans. PMID:8862746

Marriott, B M; Smith, J C; Jacobs, R M; Jones, A O; Altman, J D

1996-01-01

142

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.

Kazantzis, G

1981-01-01

143

Thermochemical stability of low-iron, manganese-enriched olivine in astrophysical environments  

NASA Astrophysics Data System (ADS)

Low-iron, manganese-enriched (LIME) olivine grains are found in cometary samples returned by the Stardust mission from comet 81P/Wild 2. Similar grains are found in primitive meteoritic clasts and unequilibrated meteorite matrix. LIME olivine is thermodynamically stable in a vapor of solar composition at high temperature at total pressures of a millibar to a microbar, but enrichment of solar composition vapor in a dust of chondritic composition causes the FeO/MnO ratio of olivine to increase. The compositions of LIME olivines in primitive materials indicate oxygen fugacities close to those of a very reducing vapor of solar composition. The compositional zoning of LIME olivines in amoeboid olivine aggregates is consistent with equilibration with nebular vapor in the stability field of olivine, without re-equilibration at lower temperatures. A similar history is likely for LIME olivines found in comet samples and in interplanetary dust particles. LIME olivine is not likely to persist in nebular conditions in which silicate liquids are stable.

Ebel, Denton S.; Weisberg, Michael K.; Beckett, John R.

2012-04-01

144

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

145

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

146

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

147

Anticonvulsant-induced changes in tissue manganese, zinc, copper, and iron concentrations in Wistar rats.  

PubMed

Human epileptics have been reported to have low blood manganese (Mn) concentrations in comparison to nonepileptics, an observation that is important because Mn deficiency can increase seizure susceptibility in experimental animals. Factors that have been suggested to contribute to the low blood Mn levels in epileptics include anticonvulsant use, seizure-induced tissue redistribution of Mn, and genetics; in the present study, the first of these possibilities was tested. Wistar rats were fed semipurified diets containing diphenylhydantoin ([DPH] 3 g/kg diet), phenobarbital ([PB] 2 g/kg diet), or primidone ([PRIM] 3 g/kg diet) for 7 weeks, at which time they were killed and tissues collected and analyzed for Mn, zinc (Zn), copper (Cu), and iron (Fe) concentrations. In comparison to pair-fed rats, DPH- and PRIM-fed rats had significantly elevated liver Mn concentrations, while Mn concentrations in blood, brain, heart, and kidney were unaffected by anticonvulsant exposure. Changes in the concentrations of Zn, Cu, and Fe in specific tissues were also found. Overall, these findings suggest that the anticonvulsants tested do not lead to significant derangements in the metabolism of Mn. PMID:8345801

Critchfield, J W; Carl, F G; Keen, C L

1993-07-01

148

Manganese, cerium and iron in the Sulu, Celebes and Philippine Seas  

NASA Astrophysics Data System (ADS)

This study was undertaken to investigate trace metals in southeast Asian seas that have different hydrographic settings: the Philippine, the Celebes, and the Sulu seas. Results reveal characteristics of dissolved and leachable manganese, dissolved cerium, and leachable iron in the water column. Remarkable increases of Mn, Ce, and Fe exist at the bottom layer of the water column in the Celebes Sea. The Ce/Mn molar ratios in the bottom waters of the Celebes Sea are identical to those in the porewaters of the underlying sediment. Both Ce and Mn show similar geochemical cycles in these deep waters of the Celebes Sea. In the Sulu Sea's deep waters, the leachable particulate fractions are dominant for Fe and Mn. The residence time of Fe in the Sulu Sea is estimated as 12 years. This residence time estimate is very similar to the particle residence time in the water column, implying that resuspension of sediment-derived particles affects leachable Fe distributions in the Sulu Sea.

Obata, Hajime; Doi, Takashi; Hongo, Yayoi; Alibo, Dia Sotto; Minami, Hideki; Kato, Yoshihisa; Maruo, Masahiro

2007-01-01

149

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

150

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

151

Migration of iron, lead, cadmium and tin from tinplate-coated cans into chickpeas.  

PubMed

Migration studies of trace metals were carried out on coated chickpea cans marketed in Lebanon. Four elements - iron (Fe), tin (Sn), lead (Pb) and cadmium (Cd) - were analysed by atomic absorption spectrometry (AAS) after microwave digestion. Over 3 months, three different storage temperatures (5°C, room temperature and 40°C) were tested. In all cases, the migration of Fe reached a plateau after around 50 days of storage, while the migration of Pb was slow till 50 days, then it increased rapidly. Cd and Sn levels did not increase. Moreover, no effect of temperature was observed in the case of Fe, whereas Pb levels showed slower migration in cans stored at 5°C. Comparing cans from different chickpea brands (Lebanese and foreign) showed that the characteristics of the container have an effect on metal release. PMID:24059695

Kassouf, A; Chebib, H; Lebbos, N; Ouaini, R

2013-09-23

152

Dietary Copper, Manganese and Iron Affect the Formation of Aberrant Crypts in Colon of Rats Administered 3,2*Dimethyl4Aminobiphenyl1,2  

Microsoft Academic Search

Aberrant crypt foci (ACF) are preneoplastic lesions for colon cancer. Altered amounts of copper-zinc (CuZnSOD) and manganese (MnSOD) superoxide dismutases have been implicated in multistage carcinogesis of both rodents and humans. Dietary factors are potential modulators of both CuZnSOD and MnSOD activity. The purpose of this study was to investigate the interactive effects of dietary copper, manganese, and iron on

Cindy D. Davis; Yi Feng

153

Study on the removal of iron and manganese in groundwater by granular activated carbon  

Microsoft Academic Search

One of the problems related to groundwater is the reddish colour caused by the presence of ferrous and manganese. Initially, this colour cannot be seen but after it has been exposed to the air, the oxidation of groundwater will promote the precipitation of ferrous and manganese. Eventually, the groundwater turns into reddish in colour. Batch test had been carried out

Ahmad bin Jusoh; W. H. Cheng; W. M. Low; Ali Nora’aini; M. J. Megat Mohd Noor

2005-01-01

154

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

155

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

156

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

SciTech Connect

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

Pon-On, Weeraphat; Meejoo, Siwaporn [Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Tang, I.-Ming [Department of Physics, Faculty of Science, Mahidol University, Institute of Science and Technology for Research and Development, Salaya Campus, Mahidol University, Nakorn Pathom 71730 (Thailand)], E-mail: scimt@mahidol.ac.th

2008-08-04

157

Studies on the catalytic activity of zirconia promoted with sulfate, iron, and manganese  

SciTech Connect

The catalytic properties of iron- and manganese-promoted sulfated zirconia (SFMZ) for the isomerization of n-butane to isobutane are investigated using various catalyst pretreatments and reaction conditions. The n-butane isomerization reactivity at 30{degrees}C is effected by calcination of the catalyst at 650{degrees}C in helium and vacuum treatment at room temperature indicating that superacidity is not likely to be responsible for activity. In addition, SFMZ samples exposed to dry air at over 450{degrees}C are more active than those calcined in helium at a reaction temperature of 30{degrees}C (n-butane conversions of 18.7% vs 0.4%) suggesting the presence of an active site involving a metal {open_quotes}oxy{close_quotes} species. The oxy species is capable of reacting CO to CO{sub 2} at room temperature and is present at a number density of 10-15 {mu}mol/g. At a reaction temperature of 100{degrees}C, SFMZ catalysts calcined in air then activated in helium show similar reactivities to those activated in air up to a preheating temperature of 450{degrees}C; above 450{degrees}C the metal oxy species is formed and provides additional activity (n-butane conversions of 37.1% in air vs 15.4% in He for calcinations at 650{degrees}C). The nature of the active sites on SFMZ are investigated using temperature-programmed desorption of substituted benzenes. The liberation of CO{sub 2} and SO{sub 2} in the benzene TPD profile of SFMZ is attributed to the oxidation of benzene at the redox-active metal sites, resulting in the subsequent decomposition of the reduced iron (II) sulfate. Data from the TPD studies do not suggest the presence of superacidity on SFMZ that could contribute to the low-temperature n-butane isomerization activity. Instead, a bifunctional mechanism that involves a combination of a redox-active metal site and an acid site in close proximity is proposed. 62 refs., 17 figs., 4 tabs.

Wan, K.T.; Khouw, C.B.; Davis, M.E. [California Institute of Technology, Pasadena, CA (United States)

1996-01-01

158

Iron uptake system mediates nitrate-facilitated cadmium accumulation in tomato (Solanum lycopersicum) plants  

PubMed Central

Nitrogen (N) management is a promising agronomic strategy to minimize cadmium (Cd) contamination in crops. However, it is unclear how N affects Cd uptake by plants. Wild-type and iron uptake-inefficient tomato (Solanum lycopersicum) mutant (T3238fer) plants were grown in pH-buffered hydroponic culture to investigate the direct effect of N-form on Cd uptake. Wild-type plants fed NO3? accumulated more Cd than plants fed NH4+. Iron uptake and LeIRT1 expression in roots were also greater in plants fed NO3?. However, in mutant T3238fer which loses FER function, LeIRT1 expression in roots was almost completely terminated, and the difference between NO3? and NH4+ treatments vanished. As a result, the N-form had no effect on Cd uptake in this mutant. Furthermore, suppression of LeIRT1 expression by NO synthesis inhibition with either tungstate or L-NAME, also substantially inhibited Cd uptake in roots, and the difference between N-form treatments was diminished. Considering all of these findings, it was concluded that the up-regulation of the Fe uptake system was responsible for NO3? -facilitated Cd accumulation in plants.

Luo, Bing Fang; Du, Shao Ting; Lu, Kai Xing; Liu, Wen Jing; Lin, Xian Yong; Jin, Chong Wei

2012-01-01

159

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

Microsoft Academic Search

The preparation of new manganese and iron complexes with\\u000athe general formula [M(tripod)(anion)] is described, where M\\u000a= FeIII or MnIII, “tripod” is a dianionic tetradentate tripodal\\u000aligand and the anion is a chelating ?-diketonate, 8-oxyquinoline\\u000aor acetate. The synthesis of this type of complexes was\\u000afound to be straightforward, which allows for the preparation\\u000aof a large variety of

Remy van Gorkum; Joris Berding; Allison M. Mills; Huub Kooijman; Duncan M. Tooke; Anthony L. Spek; Ilpo Mutikainen; Urho Turpeinen; Jan Reedijk; Elisabeth Bouwman

2008-01-01

160

The effect of iron to manganese substitution on microperoxidase 8 catalysed peroxidase and cytochrome P450 type of catalysis  

Microsoft Academic Search

This study describes the catalytic properties of manganese microperoxidase 8 [Mn(III)MP8] compared to iron microperoxidase\\u000a 8 [Fe(III)MP8]. The mini-enzymes were tested for pH-dependent activity and operational stability in peroxidase-type conversions,\\u000a using 2-methoxyphenol and 3,3?-dimethoxybenzidine, and in a cytochrome P450-like oxygen transfer reaction converting aniline\\u000a to para-aminophenol. For the peroxidase type of conversions the Fe to Mn replacement resulted in a

Jean-Louis Primus; Marelle G. Boersma; Dominique Mandon; Sjef Boeren; Cees Veeger; R. Weiss; Ivonne M. C. M. Rietjens

1999-01-01

161

A SitABCD homologue from an avian pathogenic Escherichia coli strain mediates transport of iron and manganese and resistance to hydrogen peroxide.  

PubMed

An operon encoding a member of the family of ATP-binding cassette (ABC) divalent metal ion transporters, homologous to Salmonella enterica SitABCD, has been identified in the avian pathogenic Escherichia coli (APEC) strain chi7122. The sitABCD genes were located on the virulence plasmid pAPEC-1, and were highly similar at the nucleotide level to the chromosomally encoded sitABCD genes present in Shigella spp. A cloned copy of sitABCD conferred increased growth upon a siderophore-deficient E. coli strain grown in nutrient broth supplemented with the chelator 2,2'-dipyridyl. Ion rescue demonstrated that Sit-mediated growth promotion of this strain was due to the transport of iron. SitABCD mediated increased transport of both iron and manganese as demonstrated by uptake of 55Fe, 59Fe or 54Mn in E. coli K-12 strains deficient for the transport of iron (aroB feoB) and manganese (mntH) respectively. Isotope uptake and transport inhibition studies showed that in the iron transport deficient strain, SitABCD demonstrated a greater affinity for iron than for manganese, and SitABCD-mediated transport was higher for ferrous iron, whereas in the manganese transport deficient strain, SitABCD demonstrated greater affinity for manganese than for iron. Introduction of the APEC sitABCD genes into an E. coli K-12 mntH mutant also conferred increased resistance to the bactericidal effects of hydrogen peroxide. APEC strain chi7122 derivatives lacking either a functional SitABCD or a functional MntH transport system were as resistant to hydrogen peroxide as the wild-type strain, whereas a Deltasit DeltamntH double mutant was more sensitive to hydrogen peroxide. Overall, the results demonstrate that in E. coli SitABCD represents a manganese and iron transporter that, in combination with other ion transport systems, may contribute to acquisition of iron and manganese, and resistance to oxidative stress. PMID:16514154

Sabri, Mourad; Léveillé, Simon; Dozois, Charles M

2006-03-01

162

Catalytic Convergence of Manganese and Iron Lipoxygenases by Replacement of a Single Amino Acid*  

PubMed Central

Lipoxygenases (LOXs) contain a hydrophobic substrate channel with the conserved Gly/Ala determinant of regio- and stereospecificity and a conserved Leu residue near the catalytic non-heme iron. Our goal was to study the importance of this region (Gly332, Leu336, and Phe337) of a lipoxygenase with catalytic manganese (13R-MnLOX). Recombinant 13R-MnLOX oxidizes 18:2n-6 and 18:3n-3 to 13R-, 11(S or R)-, and 9S-hydroperoxy metabolites (?80–85, 15–20, and 2–3%, respectively) by suprafacial hydrogen abstraction and oxygenation. Replacement of Phe337 with Ile changed the stereochemistry of the 13-hydroperoxy metabolites of 18:2n-6 and 18:3n-3 (from ?100% R to 69–74% S) with little effect on regiospecificity. The abstraction of the pro-S hydrogen of 18:2n-6 was retained, suggesting antarafacial hydrogen abstraction and oxygenation. Replacement of Leu336 with smaller hydrophobic residues (Val, Ala, and Gly) shifted the oxygenation from C-13 toward C-9 with formation of 9S- and 9R-hydroperoxy metabolites of 18:2n-6 and 18:3n-3. Replacement of Gly332 and Leu336 with larger hydrophobic residues (G332A and L336F) selectively augmented dehydration of 13R-hydroperoxyoctadeca-9Z,11E,15Z-trienoic acid and increased the oxidation at C-13 of 18:1n-6. We conclude that hydrophobic replacements of Leu336 can modify the hydroperoxide configurations at C-9 with little effect on the R configuration at C-13 of the 18:2n-6 and 18:3n-3 metabolites. Replacement of Phe337 with Ile changed the stereospecific oxidation of 18:2n-6 and 18:3n-3 with formation of 13S-hydroperoxides by hydrogen abstraction and oxygenation in analogy with soybean LOX-1.

Wennman, Anneli; Jerneren, Fredrik; Hamberg, Mats; Oliw, Ernst H.

2012-01-01

163

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

PubMed

Although health risk due to discoloured water is minimal, such water continues to be the source of one of the major complaints received by most water utilities in Australia. Elevated levels of iron (Fe) and/or manganese (Mn) in bulk water are associated with discoloured water incidents. The accumulation of these two elements in distribution systems is believed to be one of the main causes for such elevated levels. An investigation into the contribution of pipe wall biofilms towards Fe and Mn deposition, and discoloured water events is reported in this study. Eight laboratory-scale reactors were operated to test four different conditions in duplicate. Four reactors were exposed to low Fe (0.05 mg l(-1)) and Mn (0.02 mg l(-1)) concentrations and the remaining four were exposed to a higher (0.3 and 0.4 mg l(-1) for Fe and Mn, respectively) concentration. Two of the four reactors which received low and high Fe and Mn concentrations were chlorinated (3.0 mg l(-1) of chlorine). The biological activity (measured in terms of ATP) on the glass rings in these reactors was very low (?1.5 ng cm(-2) ring). Higher concentrations of Fe and Mn in bulk water and active biofilms resulted in increased deposition of Fe and Mn on the glass rings. Moreover, with an increase in biological activity, an increase in Fe and Mn deposition was observed. The observations in the laboratory-scale experiments were in line with the results of field observations that were carried out using biofilm monitors. The field data additionally demonstrated the effect of seasons, where increased biofilm activities observed on pipe wall biofilms during late summer and early autumn were found to be associated with increased deposition of Fe and Mn. In contrast, during the cooler months, biofilm activities were a magnitude lower and the deposited metal concentrations were also significantly less (ie a drop of 68% for Fe and 86% for Mn). Based on the laboratory-scale investigations, detachment of pipe wall biofilms due to cell death or flow dynamics could release the entrapped Fe and Mn into the bulk water, which could lead to a discoloured water event. Hence, managing biofilm growth on drinking water pipelines should be considered by water utilities to minimize accumulation of Fe and Mn in distribution networks. PMID:21229405

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

2011-02-01

164

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

165

Immunocytochemical localization of IdiA, a protein expressed under iron or manganese limitation in the mesophilic cyanobacterium Synechococcus PCC 6301 and the thermophilic cyanobacterium Synechococcus elongatus  

Microsoft Academic Search

.   Iron-deficiency-induced protein A (IdiA) with a calculated molecular mass of 35?kDa has previously been shown to be essential\\u000a under manganese- and iron-limiting conditions in the cyanobacteria Synechococcus PCC 6301 and PCC 7942. Studies of mutants indicated that in the absence of IdiA mainly photosystem II becomes damaged, suggesting\\u000a that the major function of IdiA is in Mn and not

Klaus-Peter Michel; Pablo Exss-Sonne; Gabriele Scholten-Beck; Uwe Kahmann; Hans Georg Ruppel; Elfriede K. Pistorius

1998-01-01

166

Rare earths and other trace elements in iron-manganese concretions from a catenary sequence of yellow-grey earth soils, New Zealand  

Microsoft Academic Search

Analyses of samples of iron-manganese concretions and their surrounding soil materials, from a catenary sequence of four yellowgrey earth soils (two Fragiaquepts and two Fragiochrepts) near Allanton, have been carried out using spark source mass spectrometry. Data are presented for 12 rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb) and 5 others

P. C. Rankin; C. W. Childs

1987-01-01

167

Cloning and characterization of the Pseudomonas aeruginosa sodA and sodB genes encoding manganese- and iron-cofactored superoxide dismutase: demonstration of increased manganese superoxide dismutase activity in alginate-producing bacteria.  

PubMed Central

Pseudomonas aeruginosa is a strict aerobe which is likely exposed to oxygen reduction products including superoxide and hydrogen peroxide during the metabolism of molecular oxygen. To counterbalance the potentially hazardous effects of elevated endogenous levels of superoxide, most aerobic organisms possess one or more superoxide dismutases or compounds capable of scavenging superoxide. We have previously shown that P. aeruginosa possesses both an iron- and a manganese-cofactored superoxide dismutase (D. J. Hassett, L. Charniga, K. A. Bean, D. E. Ohman, and M. S. Cohen, Infect. Immun. 60:328-336, 1992). In this study, the genes encoding manganese (sodA)- and iron (sodB)- cofactored superoxide dismutase were cloned by using a cosmid library of P. aeruginosa FRD which complemented an Escherichia coli (JI132) strain devoid of superoxide dismutase activity. The sodA and sodB genes of P. aeruginosa, when cloned into a high-copy-number vector (pKS-), partially restored the aerobic growth rate defect, characteristic of the Sod- strain, to that of the wild type (AB1157) when grown in Luria broth. The nucleotide sequences of sodA and sodB have open reading frames of 612 and 579 bp that encode dimeric proteins of 22.9 and 21.2 kDa, respectively. These data were also supported by the results of in vitro expression studies. The deduced amino acid sequence of the P. aeruginosa manganese and iron superoxide dismutase revealed approximately 50 and 67% similarity with manganese and iron superoxide dismutases from E. coli, respectively. There was also remarkable similarity with iron and manganese superoxide dismutases from other phyla. The mRNA start site of sodB was mapped to 174 bp upstream of the ATG codon. A likely promoter with similarity to the -10 and -35 consensus sequence of E. coli was observed upstream of the ATG start codon of sodB. Regions sequenced 519 bp upstream of the sodA electrophoresis, sodA gene revealed no such promoter, suggesting an alternative mode of control for sodA. By transverse field electrophoresis, sodA and sodB were mapped to the 71- to 75-min region on the P. aeruginosa PAO1 chromosome. Strikingly, mucoid alginate-producing bacteria generated greater levels of manganese superoxide dismutase than nonmucoid revertants, suggesting that mucoid P. aeruginosa is responding to oxidative stress and/or changes in the redox status of the cell. Images

Hassett, D J; Woodruff, W A; Wozniak, D J; Vasil, M L; Cohen, M S; Ohman, D E

1993-01-01

168

sup 210 Po and sup 210 Pb remobilization from lake sediments in relation to iron and manganese cycling  

SciTech Connect

The behavior of {sup 210}Po and {sup 210}Pb was studied in the water column of an oligotrophic, dimictic lake. Direct uptake of the radionuclides by sediments was negligible compared to removal on particles, and {sup 210}Pb scavenging was 4 times that of {sup 210}Po. Both nuclides were found to be significantly remobilized from sediments into the stratified, anoxic water column. Releases seem to be linked to the cycling of the transition metals, iron and possibly manganese. The distribution of both iron and {sup 210}Pb in stratified, anoxic waters can be modeled as constant release and rapid horizontal mixing/dilution; vertical turbulent transport had a negligible effect on element distributions. Upon contact with oxygen, iron rapidly reprecipitates, forming a particulate maximum and rescavenging {sup 210}Pb. Unlike {sup 210}Pb, much {sup 210}Po is released from sediments before overlying water becomes completely anoxic, leading to unsupported {sup 210}Po. {sup 210}Po cycling in the stratified water column is more complex than that of {sup 210}Pb, and additional removal mechanism(s) may be active, including perhaps oxidation of soluble Po(II) to insoluble Po(IV).

Benoit, G.; Hemond, H.F. (Massachusetts Institute of Technology, Cambridge (USA))

1990-08-01

169

Calculation of binodals and spinodals in multicomponent alloys by different statistical methods with application to iron-copper-manganese alloys  

SciTech Connect

A generalization of the pair-cluster (PC) approximation in the theory of disordered systems to multicomponent alloys is proposed. It is shown that phase equilibrium boundaries (binodals) calculated in the mean-field (MF) approximation, which is used in standard calculations of phase diagrams by the CALPHAD method, coincide with the results of rigorous calculations for dilute alloys; however, the application of these methods to calculating the boundaries of the stability region with respect to the decomposition of an alloy (spinodals) leads to large errors. At the same time, in the PC approximation, the description of all statistical properties, including binodals and spinodals, turns out to be exact for dilute alloys. The methods developed are illustrated by an example of iron-copper-manganese ternary alloys.

Vaks, V. G., E-mail: vaks@mbslab.kiae.ru; Zhuravlev, I. A.; Khromov, K. Yu. [Russian Research Centre Kurchatov Institute (Russian Federation)

2010-11-15

170

Iron and copper accumulation in the brain of coxsackievirus-infected mice exposed to cadmium  

SciTech Connect

Cadmium (Cd) is a potentially toxic metal widely distributed in the environment and known to cause adverse health effects in humans. During coxsackievirus infection, the concentrations of essential and nonessential trace elements (e.g., iron (Fe), copper (Cu), and Cd) change in different target organs of the infection. Fe and Cu are recognized cofactors in host defence reactions, and Fe is known to be associated with certain pathological conditions of the brain. However, whether nonessential trace elements could influence the balance of essential trace elements in the brain is unknown. In this study the brain Fe, Cu, and Cd contents were measured through inductively coupled plasma mass spectrometry and their distributions determined by nuclear microscopy in the early phase (day 3) of coxsackievirus B3 (CB3) infection in nonexposed and in Cd-exposed female Balb/c mice. In CB3 infection the brain is a well-known target that has not been studied with regard to trace element balance. The brain concentration of Cu compared with that of noninfected control mice was increased by 9% (P<0.05) in infected mice not exposed to Cd and by 10% (not significant) in infected Cd-exposed mice. A similar response was seen for Fe, which in infected Cd-exposed mice, compared to noninfected control mice, tended to increase by 16%. Cu showed an even tissue distribution, whereas Fe was distributed in focal deposits. Changes in Cd concentration in the brain of infected mice were less consistent but evenly distributed. Further studies are needed to define whether the accumulation and distribution of trace elements in the brain have an impact on brain function.

Ilbaeck, N.-G. [Section of Infectious Diseases, Department of Medical Sciences, Uppsala University Hospital, S-751 85 Uppsala (Sweden) and Toxicology Division, National Food Administration, Uppsala (Sweden)]. E-mail: nils-gunnar.ilback@slv.se; Lindh, U. [Research in Metal Biology, Rudbeck Laboratory, Uppsala University, Uppsala (Sweden); Minqin, R. [Centre for Ion Beam Applications, Department of Physics, National University of Singapore (Singapore); Friman, G. [Section of Infectious Diseases, Department of Medical Sciences, Uppsala University Hospital, S-751 85 Uppsala (Sweden); Watt, F. [Centre for Ion Beam Applications, Department of Physics, National University of Singapore (Singapore)

2006-11-15

171

Polymorphisms in Iron Homeostasis Genes and Urinary Cadmium Concentrations among Nonsmoking Women in Argentina and Bangladesh  

PubMed Central

Background: Cadmium (Cd) is a human toxicant and carcinogen. Genetic variation might affect long-term accumulation. Cd is absorbed via iron transporters. Objectives: We evaluated the impact of iron homeostasis genes [divalent metal transporter 1 (SLC11A2), transferrin (TF), transferrin receptors (TFR2 and TFRC), and ferroportin (SLC40A1)] on Cd accumulation. Methods: Subjects were nonsmoking women living in the Argentinean Andes [n = 172; median urinary Cd (U-Cd) = 0.24 µg/L] and Bangladesh (n = 359; U-Cd = 0.54 µg/L) with Cd exposure mainly from food. Concentrations of U-Cd and Cd in whole blood or in erythrocytes (Ery-Cd) were measured by inductively coupled plasma mass spectrometry. Fifty polymorphisms were genotyped by Sequenom. Gene expression was measured in whole blood (n = 72) with Illumina DirectHyb HumanHT-12 v4.0. Results: TFRC rs3804141 was consistently associated with U-Cd. In the Andean women, mean U-Cd concentrations were 22% (95% CI: –2, 51%), and they were 56% (95% CI: 10, 120%) higher in women with GA and AA genotypes, respectively, relative to women with the GG genotype. In the Bangladeshi women, mean U-Cd concentrations were 22% (95% CI: 1, 48%), and they were 58% (95% CI: –3, 157%) higher in women with GA and AA versus GG genotype, respectively [adjusted for age and plasma ferritin in both groups; ptrend = 0.006 (Andes) and 0.009 (Bangladesh)]. TFRC expression in blood was negatively correlated with plasma ferritin (rS = –0.33, p = 0.006), and positively correlated with Ery-Cd (significant at ferritin concentrations of < 30 µg/L only, rS = 0.40, p = 0.046). Rs3804141 did not modify these associations or predict TFRC expression. Cd was not consistently associated with any of the other polymorphisms evaluated. Conclusions: One TFRC polymorphism was associated with urine Cd concentration, a marker of Cd accumulation in the kidney, in two very different populations. The consistency of the findings supports the possibility of a causal association.

Rentschler, Gerda; Kippler, Maria; Axmon, Anna; Raqib, Rubhana; Ekstrom, Eva-Charlotte; Skerfving, Staffan; Vahter, Marie

2013-01-01

172

[Secondary Osteoporosis or Secondary Contributors to Bone Loss in Fracture. Bone metabolism and heavy metals (cadmium and iron) ].  

PubMed

Fibroblast growth factor 23 (FGF23) is a bone-derived phosphaturic factor and is known to regulate blood inorganic phosphate (Pi) . Cadmium (Cd) , a toxic transition metal, which is widely used in industry, affecting human health and through occupational and environmental exposure. Phosphaturia has been documented following Cd exposure in both human and experimental animals. In animal study, Cd administration increases serum FGF23 concentrations. Moreover, medication such as infusion of select iron-containing compounds increases serum FGF23 concentrations, with patients developing hypophosphatemia. Thus, a relationship between metal ion (Cd and Fe) and FGF23 metabolic pathway has been proposed. PMID:23999366

Kido, Shinsuke

2013-09-01

173

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

174

Damping properties of iron-manganese antifriction alloys with different types of crystal lattice  

Microsoft Academic Search

Conditions for ensuring a high damping capacity in high-strength low-cost antifriction materials are determined depending\\u000a on the content of manganese, methods of fabrication (traditional and powder metallurgy), and type of crystal lattice. The\\u000a mechanisms of energy dissipation in cast and powder Fe – Mn alloys are studied and the special features of their structure\\u000a responsible for the elevation of the

T. F. Volynova; M. A. Lushkin; I. K. Buravlev

2009-01-01

175

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

176

Iron Nutrition Influence on Cadmium Accumulation by 'Arabidopsis thaliana' (L.) Heynh.  

National Technical Information Service (NTIS)

Greenhouse experiments were conducted to determine whether Arabidopsis thaliana (L.) Heynh., a putative Fe-efficient species, accumulated higher concentrations of Cd from a sparingly soluble Cd source (cadmium dihydrogen phosphate) when growing in Fe-defi...

K. D. Rodecap D. T. Tingey E. H. Lee

1994-01-01

177

Structural and magnetic properties of the iron substituted lithium–manganese spinel oxides  

Microsoft Academic Search

Most studies on the lithium–manganese oxide as a cathode material have concentrated on the stabilization of the cubic spinel structure, mainly by doping other transition metal ions into LiMn2O4 lattice. Partial substitution of Fe3+ ions for Mn3+ restrains the Jahn–Teller effect, owing to the reduction of Mn3+\\/Mn4+ ratio. In LiFe0.1Mn1.9O4 spinel oxide the phase transitions from cubic to orthorhombic and\\/or

Emilia Wolska; Michael Tovar; Bartlomiej Andrzejewski; Waldemar Nowicki; Jolanta Darul; Pawel Piszora; Michael Knapp

2006-01-01

178

Respiration-linked proton translocation coupled to anaerobic reduction of manganese(IV) and iron(III) in Shewanella putrefaciens MR-1.  

PubMed Central

An oxidant pulse technique, with lactate as the electron donor, was used to study respiration-linked proton translocation in the manganese- and iron-reducing bacterium Shewanella putrefaciens MR-1. Cells grown anaerobically with fumarate or nitrate as the electron acceptor translocated protons in response to manganese (IV), fumarate, or oxygen. Cells grown anaerobically with fumarate also translocated protons in response to iron(III) and thiosulfate, whereas those grown with nitrate did not. Aerobically grown cells translocated protons only in response to oxygen. Proton translocation with all electron acceptors was abolished in the presence of the protonophore carbonyl cyanide m-chlorophenylhydrazone (20 microM) and was partially to completely inhibited by the electron transport inhibitor 2-n-heptyl-4-hydroxyquinoline N-oxide (50 microM).

Myers, C R; Nealson, K H

1990-01-01

179

RESPONSE OF ‘GRANNY SMITH’ APPLE TREES TO FOLIAR TITANIUM SPRAYS UNDER CONDITIONS OF LOW SOIL AVAILABILITY OF IRON, MANGANESE, AND ZINC  

Microsoft Academic Search

The aim of the study was to examine impact of foliar titanium (Ti) sprays on vegetative and reproductive response of apple (Malus domestica Borkh.) trees under conditions of low soil availability of iron (Fe), manganese (Mn), and zinc (Zn). The experiment was conducted during 2005–2006 at a Experimental Station in Isparta region, Turkey, on mature ‘Granny Smith’ apple trees\\/M.9, planted

Pawe? Wójcik; Hamide Gubbuk; Hüseyin Akgül; Esma Gunes; Kadir Ucgun; Hakk? Koçal; Cenk Küçükyumuk

2010-01-01

180

Long-term removal and retention of iron and manganese from acidic mine drainage by wetlands. Volume 1. Methods, results, and appendices. Final report, July 1987January 1990  

Microsoft Academic Search

A promising low-technology solution for treating acidic mine drainage (AMD) emanating from coal mined lands involves the use of constructed wetlands. The research was directed at addressing questions about retention mechanisms for the long-term storage of iron and manganese in constructed wetlands dominated by broad-leaved cattails (Typha latifolia). Three sites in central Pennsylvania spanning the range of water chemistry parameters

R. P. Brooks; R. F. Unz; L. K. Davis; W. J. Tarutis; J. Yanchunas

1990-01-01

181

ZrO 2 promoted with sulfate, iron and manganese: a solid superacid catalyst capable of low temperature n -butane isomerization  

Microsoft Academic Search

A sulfated oxide of zirconium, iron and manganese is prepared and shown to isomerizen-butane to isobutane at 35°C with rates approximately 2–3 orders of magnitude greater than sulfated zirconia as claimed by workers at Sun Refining and Marketing Company. Temperature programmed desorption of benzene is used to investigate the acidity of this remarkable catalyst. Adsorbed benzene is oxidized to CO2

Anup Jatia; Clark Chang; Jason D. MacLeod; Tatsuya Okubo; Mark E. Davis

1994-01-01

182

Protolytic cracking of low-molecular-weight alkanes in the presence of iron- and manganese-promoted sulfated zirconia: evidence of a compensation effect  

Microsoft Academic Search

Low conversions of propane, n-butane, and 2,2-dimethylpropane were measured with each reactant in the presence of iron- and manganese-promoted sulfated zirconia in a once-through plug-flow reactor at 101 kPa, 473–723 K, and reactant partial pressures of 25, 250, and 1000 Pa. Rates of the reactions (overall conversion of propane, of n-butane, and of 2,2-dimethylpropane; formation of methane from each of

T.-K. Cheung; F. C. Jentoft; J. L. d'Itri; B. C. Gates

1997-01-01

183

Cobalt, manganese, and iron near the Hawaiian Islands: A potential concentrating mechanism for cobalt within a cyclonic eddy and implications for the hybrid-type trace metals  

Microsoft Academic Search

The vertical distributions of cobalt, iron, and manganese in the water column were studied during the E-Flux Program (E-Flux II and III), which focused on the biogeochemistry of cold-core cyclonic eddies that form in the lee of the Hawaiian Islands. During E-Flux II (January 2005) and E-Flux III (March 2005), 17 stations were sampled for cobalt (n=147), all of which

Abigail E. Noble; Mak A. Saito; Kanchan Maiti; Claudia R. Benitez-Nelson

2008-01-01

184

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.

Cotruvo, Joseph A.; Stubbe, JoAnne

2012-01-01

185

Effects of dietary cadmium exposure on tissue-specific cadmium accumulation, iron status and expression of iron-handling and stress-inducible genes in rainbow trout: influence of elevated dietary iron.  

PubMed

Recent evidences suggest that dietary cadmium (Cd) uptake likely occurs via the dietary iron (Fe) uptake pathway in freshwater fish, at least in part. The present study investigated the interactive effects of dietary Cd and Fe in juvenile rainbow trout (Oncorhynchus mykiss). Fish were treated for four weeks with four different diets: normal Fe, high Fe, normal Fe plus Cd, and high Fe plus Cd. Physiological parameters, tissue-specific Fe and Cd level, plasma Fe status, and tissue-specific mRNA expression of transferrin, metallothioneins (MT-A and MT-B) and heat shock proteins 70 (HSP70a and HSP70b) were analyzed. Exposure to dietary Cd increased Cd burden in the following order: intestine>kidney>stomach>liver>gill>carcass. Interestingly, high dietary Fe reduced Cd accumulation in the stomach and intestine as well as in the wholebody of fish. Dietary Cd increased hepatic transferrin mRNA expression and total Fe binding capacity in the plasma, indicating the effect of Cd on Fe handling in fish. The mRNA expression of MTs and HSP70s was also increased in various tissues following dietary Cd exposure, however the response profile of different MT and HSP70 genes was not consistent among different tissues. In general, MT-A was more responsive to Cd exposure in the intestine and liver, whereas MT-B was more responsive in the kidney. Similarly, HSP70a expression was more sensitive to Cd exposure than HSP70b, particularly in the intestine. Interestingly, high Fe diet suppressed Cd-induced induction of transferrin, MT and HSP70 genes in various tissues. Overall, our study suggests that elevated dietary Fe can reduce Cd accumulation and ameliorate Cd-induced stress responses in freshwater fish. PMID:21371606

Kwong, Raymond W M; Andrés, Jose A; Niyogi, Som

2010-12-28

186

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

187

Dinuclear cadmium(II), zinc(II), and manganese(II), trinuclear nickel(II), and pentanuclear copper(II) complexes with novel macrocyclic and acyclic Schiff-base ligands having enantiopure or racemic camphoric diamine components.  

PubMed

Four novel [3 + 3] Schiff-base macrocyclic ligands I-IV condensed from 2,6-diformyl-4-substituted phenols (R = CH(3) or Cl) and enantiopure or racemic camphoric diamines have been synthesized and characterized. Metal-ion complexations of these enantiopure and racemic [3 + 3] macrocyclic ligands with different cadmium(II), zinc(II), manganese(II), nickel(II), and copper(II) salts lead to the cleavage of Schiff-base C horizontal lineN double bonds and subsequent ring contraction of the macrocyclic ligands due to the size effects and the spatial restrictions of the coordination geometry of the central metals, the steric hindrance of ligands, and the counterions used. As a result, five [2 + 2] and one [1 + 2] dinuclear cadmium(II) complexes (1-6), two [2 + 2] dinuclear zinc(II) (7 and 8), and two [2 + 2] dinuclear manganese(II) (9 and 10) complexes together with one [1 + 1] trinuclear nickel(II) complex (11) and one [1 + 2] pentanuclear copper(II) complex (12), bearing enantiopure or racemic ligands, different substituent groups in the phenyl rings, and different anionic ligands (Cl(-), Br(-), OAc(-), and SCN(-)), have been obtained in which the chiral carbon atoms in the camphoric backbones are arranged in different ways (RRSS for the enantiopure ligands in 1, 2, 4, 5, and 7-10 and RSRS for the racemic ligands in 3, 6, 11, and 12). The steric hindrance effects of the methyl group bonded to one of the chiral carbon atoms of camphoric diamine units are believed to play important roles in the formation of the acyclic [1 + 1] trinuclear complex 11 and [1 + 2] dinuclear and pentanuclear complexes 6 and 12. In dinuclear cadmium(II), zinc(II), and manganese(II) complexes 1-10, the sequence of separations between the metal centers is consistent with that of the ionic radii shortened from cadmium(II) to manganese(II) to zinc(II) ions. Furthermore, UV-vis, circular dichroism, (1)H NMR, and fluorescence spectra have been used to characterize and compare the structural differences between related compounds. PMID:20515021

Jiang, Jue-Chao; Chu, Zhao-Lian; Huang, Wei; Wang, Gang; You, Xiao-Zeng

2010-07-01

188

Electrochemical cell with a cadmium patch electrode  

SciTech Connect

A cadmium patch laminar electrode, comprising a dispersion of particulate cadmium in a binder matrix on a conductive plastic substrate is prepared by contacting a zinc patch electrode comprising a dispersion of particulate zinc in a binder matrix on a conductive plastic substrate with an aqueous solution of a cadmium salt. The cadmium patch electrode can be used in a primary electrochemical cell such as that employing a manganese dioxide cathode and a cadmium chloride electrolyte.

Ames, A.E.; Bloom, S.M.; Hoffman, A.; Norland, K.

1980-01-22

189

Using Flow Injection Analysis (FIA) to measure trace metal concentrations of iron and manganese in seawater  

Microsoft Academic Search

The improved sensitivity of the techniques used to measure trace metals in seawater has heightened our ability to quantify trace metal concentrations and better understand their ocean biogeochemical cycling. Flow Injection Analysis (FIA) with chemiluminescence was the highly sensitive technique used to measure dissolved iron and Mn in seawater. The main objectives of this investigation were to gain a better

Lisa Pickell; Ken Johnson; Zanna Chase; Ginger Elrod

190

Iron, manganese and copper emitted by cargo and passenger trains in Zürich (Switzerland): Size-segregated mass concentrations in ambient air  

NASA Astrophysics Data System (ADS)

Particle emissions caused by railway traffic have hardly been investigated in the past, due to their obviously minor influence on air quality compared to automotive traffic. In this study, emissions related to particle abrasion from wheels and tracks were investigated next to a busy railway line in Zürich (Switzerland), where trains run nearly exclusively with electrical locomotives. Hourly size-segregated aerosol samples (0.1-1, 1-2.5 and 2.5-10 ?m) were collected with a rotating drum impactor (RDI) and subsequently analyzed by synchrotron radiation X-ray fluorescence spectrometry (SR-XRF). In this way, hourly elemental mass concentrations were obtained for chromium, manganese, iron and copper, which are the elements most relevant for railway abrasion. Additionally, daily aerosol filters were collected at the same site as well as at a background site for subsequent analysis by gravimetry and wavelength dispersive XRF (WD-XRF). Railway related ambient air concentrations of iron and manganese were calculated for the coarse (2.5-10 ?m) and fine (<2.5 ?m) particle fraction by means of a Mn/Fe ratio investigation. The comparison to train type and frequency data showed that 75% and 60% of the iron and manganese mass concentrations related to cargo and passenger trains, respectively, were found in the coarse mode. The railway related iron mass concentration normalized by the train frequency ranges between 10 and 100 ng m -3 h iron in 10 m distance to the tracks, depending on train type. It is estimated that the personal exposure next to a busy railway line above ground is more than a magnitude lower than inside a subway station.

Bukowiecki, Nicolas; Gehrig, Robert; Hill, Matthias; Lienemann, Peter; Zwicky, Christoph N.; Buchmann, Brigitte; Weingartner, Ernest; Baltensperger, Urs

191

Synthesis and characterization of metal-centered, six-membered, mixed-valent, heterometallic wheels of iron, manganese, and indium.  

PubMed

Heptanuclear metal-centered, six-membered, mixed-valent, heterometallic wheels 1-3 of iron, manganese, and indium were prepared in a one-pot reaction from N-benzyldiethanolamine (H2L(1)), cesium carbonate, [PPh4]2[MnCl4], and FeCl3 or InCl3. All three complexes were characterized by the combination of elemental analysis, FAB mass spectroscopy, X-ray diffraction and cyclic voltammetry and in the case of 1 additionally by Mössbauer spectroscopy. In 1, four Mn(II) ions in the periphery are arranged in pairs alternating with one Fe(III) ion each, with an Fe(III) ion located in the center. In 2, three Mn(II) ions alternate with three In(III) ions, whereas in 3, four In(III) ions are arranged in pairs and alternate with one Mn(II) ion each. In 2 and 3 an Mn(II) ion is encapsulated in the center. PMID:16470618

Saalfrank, Rolf W; Prakash, Raju; Maid, Harald; Hampel, Frank; Heinemann, Frank W; Trautwein, Alfred X; Böttger, Lars H

2006-03-01

192

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

PubMed

A thermophilic anaerobic bacterium, designated strain BMAT (T = type strain), was isolated from the production water of Beatrice oil field in the North Sea (United Kingdom). The cells were straight to bent rods (1 to 5 by 0.3 to 0.5 microns) which stained gram negative. Strain BMAT obtained energy from the reduction of manganese (IV), iron(III), and nitrate in the presence of yeast extract, peptone, Casamino Acids, tryptone, hydrogen, malate, acetate, citrate, pyruvate, lactate, succinate, and valerate. The isolate grew optimally at 60 degrees C (temperature range for growth, 50 to 65 degrees C) and in the presence of 2% (wt/vol) NaCl (NaCl range for growth, 0 to 5% [wt/vol]). The DNA base composition was 34 mol% G + C. Phylogenetic analyses of the 16S rRNA gene indicated that strain BMAT is a member of the domain Bacteria. The closest known bacterium is the moderate thermophile Flexistipes sinusarabici (similarity value, 88%). Strain BMAT possesses phenotypic and phylogenetic traits that do not allow its classification as a member of any previously described genus; therefore, we propose that this isolate should be described as a member of a novel species of a new genus, Deferribacter thermophilus gen. nov., sp. nov. PMID:9103640

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

1997-04-01

193

Matrix isolation infrared spectra, assignment and DFT investigation on reactions of iron and manganese monoxides with CH3Cl.  

PubMed

The reactions of iron and manganese monoxide molecules (FeO, and MnO) with monochloromethane in solid argon have been studied by matrix isolation infrared spectroscopy and quantum chemistry calculations. When annealing, the reactions of FeO and MnO with CH3Cl first form the OM-(?(Cl)-CH3Cl) (MMn, Fe) complexes, which can isomerize to CH3MOCl (MMn, Fe) upon 300

Zhao, Yanying; Fan, Kexue; Huang, Yongfei; Zheng, Xuming

2013-07-10

194

Retention of nickel from aqueous solutions using iron oxide and manganese oxide coated sand: kinetic and thermodynamic studies.  

PubMed

In this study, the removal of nickel ions from aqueous solutions using iron oxide and manganese oxide coated sand (ICS and MCS) under different experimental conditions was investigated. The effect of metal concentration, contact time, solution pH and temperature on the amount of Ni(II) sorbed was studied and discussed. Langmuir and Freundlich isotherm constants and correlation coefficients for the present systems at different temperatures were calculated and compared. The equilibrium process was well described by the Langmuir isotherm model: the maximum sorption capacities (at 29 K) were 2.73 mg Ni/g and 3.33 mg Ni/g of sorbent for ICS and MCS, respectively. Isotherms were also used to evaluate the thermodynamic parameters (deltaG degrees, deltaH degrees, deltaS degrees) of adsorption. The sorption kinetics were tested for the pseudo-first-order, pseudo-second-order and intra-particle diffusion models. Good correlation coefficients were obtained for the pseudo-second-order kinetic model, showing that the nickel uptake process followed the pseudo-second-order rate expression. PMID:21275258

Boujelben, N; Bouzid, J; Elouear, Z; Feki, M

2010-12-14

195

Spatio-temporal Distribution and Chemical Speciation of Iron and Manganese in Sediments from Lake Aha, China  

NASA Astrophysics Data System (ADS)

This paper reports an investigation on pollution and potential risk on elements of iron (Fe) and manganese (Mn) in sediments from Lake Aha, which is a drinking-water source for Guiyang City, the capital of Guizhou Province in southwestern China. In the present research, chemical speciation of Fe and Mn in sediments from the lake was studied based on the sequential extraction procedure developed by Tessier et al.. The results obtained from the study are as follows. The average values of total Fe were 47617 mg/kg and 70325 mg/kg in sediments from the lake in summer and winter respectively, and its speciation consisted mainly of residual and Fe-Mn oxides fractions. The amounts of total Fe and the distribution of its speciation in the sediments should be affected by effluents from a large quantity of deserted coal mines in the lake basin in summer and winter. The average values of total Mn were 7996 mg/kg and 1753 mg/kg in summer and winter respectively, and its speciation is primarily comprised of carbonate and Fe-Mn oxides fractions. The amounts of total Mn and its distribution in different fractions in the sediments were believed to be primarily influenced by effluents from those deserted coal mines in summer and by the condition of redox interface in winter.

Liu, Feng; Hu, Jiwei; Qin, Fanxin; Jiang, Cuihong; Huang, Xianfei; Deng, Jiajun; Li, Cunxiong

2010-11-01

196

Intracellular Localization and Subsequent Redistribution of Metal Transporters in a Rat Choroid Plexus Model Following Exposure to Manganese or Iron  

PubMed Central

Confocal microscopy was used to investigate the effects of manganese (Mn) and iron (Fe) exposure on the subcellular distribution of metal transporting proteins, i.e., divalent metal transporter 1 (DMT1), metal transporter protein 1 (MTP1), and transferrin receptor (TfR), in the rat intact choroid plexus which comprises the blood-cerebrospinal fluid barrier. In control tissue, DMT1 was concentrated below the apical epithelial membrane, MTP1 was diffuse within the cytosol, and TfR was distributed in vesicles around nuclei. Following Mn or Fe treatment (1 and 10 µM), the distribution of DMT1 was not affected. However, MTP1 and TfR moved markedly toward the apical pole of the cells. These shifts were abolished when microtubules were disrupted. Quantitative RT-PCR and Western blot analyses revealed a significant increase in mRNA and protein levels of TfR but not DMT1 and MTP1 after Mn exposure. These results suggest that early events in the tissue response to Mn or Fe exposure involve microtubule-dependent, intracellular trafficking of MTP1 and TfR. The intracellular trafficking of metal transporters in the choroid plexus following Mn exposure may partially contribute to Mn-induced disruption in Fe homeostasis in the cerebrospinal fluid (CSF) following Mn exposure.

Wang, Xueqian; Miller, David S.; Zheng, Wei

2008-01-01

197

Intracellular localization and subsequent redistribution of metal transporters in a rat choroid plexus model following exposure to manganese or iron  

SciTech Connect

Confocal microscopy was used to investigate the effects of manganese (Mn) and iron (Fe) exposure on the subcellular distribution of metal transporting proteins, i.e., divalent metal transporter 1 (DMT1), metal transporter protein 1 (MTP1), and transferrin receptor (TfR), in the rat intact choroid plexus which comprises the blood-cerebrospinal fluid barrier. In control tissue, DMT1 was concentrated below the apical epithelial membrane, MTP1 was diffuse within the cytosol, and TfR was distributed in vesicles around nuclei. Following Mn or Fe treatment (1 and 10 {mu}M), the distribution of DMT1 was not affected. However, MTP1 and TfR moved markedly toward the apical pole of the cells. These shifts were abolished when microtubules were disrupted. Quantitative RT-PCR and Western blot analyses revealed a significant increase in mRNA and protein levels of TfR but not DMT1 and MTP1 after Mn exposure. These results suggest that early events in the tissue response to Mn or Fe exposure involve microtubule-dependent, intracellular trafficking of MTP1 and TfR. The intracellular trafficking of metal transporters in the choroid plexus following Mn exposure may partially contribute to Mn-induced disruption in Fe homeostasis in the cerebrospinal fluid (CSF) following Mn exposure.

Wang Xueqian [School of Health Sciences, Purdue University, West Lafayette, IN 47907 (United States); Miller, David S. [NIH/NIEHS, Research Triangle Park, NC 27709 (United States); Zheng Wei [School of Health Sciences, Purdue University, West Lafayette, IN 47907 (United States)], E-mail: wz18@purdue.edu

2008-07-15

198

Bacterial contribution to mitigation of iron and manganese in mangrove sediments.  

PubMed

The Mandovi and Chapora are two tropical estuaries lying in close geographic proximity on the west coast of India. Seasonal changes in down core variation of Fe, Mn and Total Organic Carbon (TOC) in the mangrove sediments adjoining these estuaries were studied to assess their influence on some of the representative benthic bacteria belonging to heterotrophic and autotrophic groups. Heterotrophic bacteria (HB) cultured on different nutrient concentrations (0.01%, 0.1% and 25%) together with nitrifiers (NtB; representating autotroph) were chosen to assess the influence of the above-mentioned abiotic parameters on the former. The experimental site located along the Mandovi is under the influence of extensive ferromanganese ore mining, while the control site at Chapora is relatively free from such influences. Geoaccumulation index computed for Mandovi showed that sediments (0-10cm) were 'uncontaminated to moderately contaminated' by Fe during the pre monsoon and monsoon seasons, while in the post monsoon season the 4-10cm fraction was almost completely restored from contamination. Similar computations for Mn showed that in pre monsoon, sediments fell in the 'moderately contaminated' and 'moderately to strongly contaminated' categories, while in the monsoon and post monsoon seasons all the sections were 'Uncontaminated'. The difference observed in correlation between Fe and Mn with the various fractions of heterotrophs and nitrifiers indicated that though these two elements shared a similar chemistry in the environment, microbes involved in biogeochemical processes might prefer them differentially. The relationship between TOC and HB enumerated on 0.01% dilute nutrient agar remained at r=0.50, p<0.05 throughout the year. Hence, it could be apparently linked to their preferred concentration of organic carbon requirement. A relationship of r=0.61, p<0.01 between manganese concentration and heterotrophs recovered on different strengths of nutrient agar is suggestive of their response to the metal enrichment. They could thus contribute towards maintaining the level of Mn at par with reference levels at Chapora. A positive correlation between Mn with NtB (n=10, p<0.05, r=0.58) at the experimental site during the non-monsoon months is suggestive of the latter's contribution to regulation of the metal concentration in the sediment probably through anaerobic nitrification at the expense of manganese. The study therefore supports our hypothesis that both autochthonous autotrophs and heterotrophs work in tandem to mitigate concentration of Mn and related metals in mangrove sediments. PMID:17632183

Krishnan, K P; Fernandes, Sheryl Oliveira; Chandan, G S; Loka Bharathi, P A

2007-07-16

199

Phytotoxicity and some interactions of the essential trace metals iron, manganese, molybdenum, zinc, copper, and boron  

Microsoft Academic Search

The essential trace elements Fe, Mn, Zn, Cu, and B in high concentrations can produce phytotoxicities. Iron toxicity resulted from 5 × 10 M and 10 M FeSO4, but not from equivalent amounts of FeEDDHA (ferric ethylenediamine di (o?hydroxyphenylacetic acid) ). Leaf concentrations in bush beans of 465 ?g Mn\\/g, 291 ?g B\\/g, and 321 ?g Zn\\/g all on the

A. Wallace; E. M. Romney; G. V. Alexander; J. Kinnear

1977-01-01

200

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

201

Bioaccumulation of iron, zinc, cadmium and chromium by juvenile snail Limicolaria aurora J., fed edible mushroom Pleurotus spp from Niger Delta, Nigeria.  

PubMed

The effects of uptake of metals (iron, zinc, cadmium and chromium) by juvenile snail Limicolaria aurora fed edible mushroom Pleurotus spp from 3 contaminated farm sites and a laboratory grown species (control) respectively were investigated. The 120 snails were fed in plastic snaileries for 4 weeks in the laboratory. Control site was risk free. Metal uptake was low and bioaccumulation in L. aurora tissue was below FAO/WHO standard of 1 mg/kg for chromium and cadmium. Snails were considered safe for consumption. PMID:23229305

Ebenso, I E; Solomon, I P; Akoje, C C; Akpan, I P; Eko, P M; Akpan, E A; Omole, A J

2012-12-11

202

Use of Manganese Cast Iron for Parts of Soil Working Machines (Primenenie Margantsovistogo Chuguna dlya Detalei Pochvoobrabatyvayushchikh Mashin).  

National Technical Information Service (NTIS)

Cast steels with high manganese contents (4-12%) and inoculated with cerium were evaluated as materials for tillage tools. The greatest wear resistance to soil abrasion occurred for the 4% manganese steels. Landsides of plows, cultivator tips, and disk hi...

V. B. Lyadski M. I. Masumov V. I. Rublev

1971-01-01

203

Novel Mode of Microbial Energy Metabolism: Organic Carbon Oxidation Coupled to Dissimilatory Reduction of Iron or Manganese  

PubMed Central

A dissimilatory Fe(III)- and Mn(IV)-reducing microorganism was isolated from freshwater sediments of the Potomac River, Maryland. The isolate, designated GS-15, grew in defined anaerobic medium with acetate as the sole electron donor and Fe(III), Mn(IV), or nitrate as the sole electron acceptor. GS-15 oxidized acetate to carbon dioxide with the concomitant reduction of amorphic Fe(III) oxide to magnetite (Fe3O4). When Fe(III) citrate replaced amorphic Fe(III) oxide as the electron acceptor, GS-15 grew faster and reduced all of the added Fe(III) to Fe(II). GS-15 reduced a natural amorphic Fe(III) oxide but did not significantly reduce highly crystalline Fe(III) forms. Fe(III) was reduced optimally at pH 6.7 to 7 and at 30 to 35°C. Ethanol, butyrate, and propionate could also serve as electron donors for Fe(III) reduction. A variety of other organic compounds and hydrogen could not. MnO2 was completely reduced to Mn(II), which precipitated as rhodochrosite (MnCO3). Nitrate was reduced to ammonia. Oxygen could not serve as an electron acceptor, and it inhibited growth with the other electron acceptors. This is the first demonstration that microorganisms can completely oxidize organic compounds with Fe(III) or Mn(IV) as the sole electron acceptor and that oxidation of organic matter coupled to dissimilatory Fe(III) or Mn(IV) reduction can yield energy for microbial growth. GS-15 provides a model for how enzymatically catalyzed reactions can be quantitatively significant mechanisms for the reduction of iron and manganese in anaerobic environments. Images

Lovley, Derek R.; Phillips, Elizabeth J. P.

1988-01-01

204

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

PubMed

A dissimilatory Fe(III)- and Mn(IV)-reducing microorganism was isolated from freshwater sediments of the Potomac River, Maryland. The isolate, designated GS-15, grew in defined anaerobic medium with acetate as the sole electron donor and Fe(III), Mn(IV), or nitrate as the sole electron acceptor. GS-15 oxidized acetate to carbon dioxide with the concomitant reduction of amorphic Fe(III) oxide to magnetite (Fe(3)O(4)). When Fe(III) citrate replaced amorphic Fe(III) oxide as the electron acceptor, GS-15 grew faster and reduced all of the added Fe(III) to Fe(II). GS-15 reduced a natural amorphic Fe(III) oxide but did not significantly reduce highly crystalline Fe(III) forms. Fe(III) was reduced optimally at pH 6.7 to 7 and at 30 to 35 degrees C. Ethanol, butyrate, and propionate could also serve as electron donors for Fe(III) reduction. A variety of other organic compounds and hydrogen could not. MnO(2) was completely reduced to Mn(II), which precipitated as rhodochrosite (MnCO(3)). Nitrate was reduced to ammonia. Oxygen could not serve as an electron acceptor, and it inhibited growth with the other electron acceptors. This is the first demonstration that microorganisms can completely oxidize organic compounds with Fe(III) or Mn(IV) as the sole electron acceptor and that oxidation of organic matter coupled to dissimilatory Fe(III) or Mn(IV) reduction can yield energy for microbial growth. GS-15 provides a model for how enzymatically catalyzed reactions can be quantitatively significant mechanisms for the reduction of iron and manganese in anaerobic environments. PMID:16347658

Lovley, D R; Phillips, E J

1988-06-01

205

High-resolution redox dynamics of iron and manganese as recorded in the sediments of Lake Zurich, Switzerland  

NASA Astrophysics Data System (ADS)

Trace metals, such as iron (Fe) and manganese (Mn), have received much attention in the last decades due to their redox-sensitive behaviour in the environment. In lakes, seasonal redox changes in the water column lead to biogeochemical cycling of Fe and Mn throughout the year. Under reducing conditions during stratification, they are (re)dissolved from the sediment. After water column (re)oxygenation during mixing, they precipitate and can be deposited and preserved in the lake sediment. In this case, they can serve as palaeoredox proxies. Although the redox-sensitive behaviour of Fe and Mn is quite well understood, the relationship between high-resolution trace metal data and short-term oxygen level changes still need to be shown. Therefore, in this study, seasonal redox dynamics of Fe and Mn were reconstructed in sediment cores along a depth transect from the mesotrophic and dimictic Lake Zurich, based on detailed measurements using a X-ray fluorescence (XRF) core scanner. A sample resolution of 0.3 mm enabled a high-resolution, semi-quantitative record of trace metals in the retrieved sediment cores. The bi-annual lamination pattern (i.e. varves) in the sediment, which is especially well reflected in the cyclic calcium (Ca) XRF data, was used to establish a precise age model with seasonal resolution. This trace metal record could be correlated with a unique long-term monitoring data series of water column properties, including monthly oxygen data, which exist for different water depths since 1936. The Fe signals were quite complex. As iron can be of detrital origin, as well as the product of redox-sensitive processes, the interpretation of the Fe concentration as palaeoredox proxy is not clearly determined. Peaks of Fe in fall/winter seemed to evidence traces of oxygen resupply. However, detrital inputs were also higher at this time of the year and high Ca intensities might lead to a dilution of Fe especially during summer time. In contrast, the match of Mn maxima with higher oxygen levels shows that oxygenation events during the winter half-year could be traced precisely in the core obtained from the maximum depth (137 m). However, the disappearance of Mn peaks in cores from lower water depths strongly indicates geochemical focusing. This process was earlier described in lower temporal resolution in similar lake systems (e.g. Lake Baldegg, Switzerland) leading to a removal of Mn from shallower water depths and the enrichment in sediments at maximum lake depth.

Naeher, S.; Gilli, A.; Schubert, C. J.

2012-04-01

206

No significant effect of iron deficiency on cadmium body burden or kidney dysfunction among women in the general population in Japan  

Microsoft Academic Search

Objective. To examine if iron-deficient conditions modify body burden or health effects of cadmium among women in the general population in Japan.Methods. In 2002, 1,482 women aged 20 to 74 years in six prefectures in Japan provided informed consent to participate in this study. They offered peripheral blood and spot urine samples, and answered questionnaires on their social habits and

T. Tsukahara; T. Ezaki; J. Moriguchi; K. Furuki; Y. Fukui; H. Ukai; S. Okamoto; H. Sakurai; M. Ikeda

2003-01-01

207

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.

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

2013-01-01

208

Iron and Manganese Pyrophosphates as Cathodes for Lithium-Ion Batteries  

SciTech Connect

The mixed-metal phases, (Li{sub 2}Mn{sub 1-y}Fe{sub y}P{sub 2}O{sub 7}, 0 {le} y {le} 1), were synthesized using a 'wet method', and found to form a solid solution in the P2{sub 1}/a space group. Both thermogravimetric analysis and magnetic susceptibility measurements confirm the 2+ oxidation state for both the Mn and Fe. The electrochemical capacity improves as the Fe concentration increases, as do the intensities of the redox peaks of the cyclic voltammogram, indicating higher lithium-ion diffusivity in the iron phase. The two Li{sup +} ions in the three-dimensional tunnel structure of the pyrophosphate phase allows for the cycling of more than one lithium per redox center. Cyclic voltammograms show a second oxidation peak at 5 V and 5.3 V, indicative of the extraction of the second lithium ion, in agreement with ab initio computation predictions. Thus, electrochemical capacities exceeding 200 Ah/kg may be achieved if a stable electrolyte is found.

Zhou, Hui; Upreti, Shailesh; Chernova, Natasha A.; Hautier, Geoffroy; Ceder, Gerbrand; Whittingham, M. Stanley (MIT); (SUNY-Binghamton)

2011-11-07

209

Release Rates of Ammonium?Nitrogen, Nitrate?Nitrogen, Phosphorus, Potassium, Magnesium, Iron, and Manganese from Seven Controlled?Release Fertilizers  

Microsoft Academic Search

Samples of seven controlled?release fertilizers, Nutricote Total 13–13–13, Nutricote Total 18–6–8, Osmocote Plus 15–9–12, Osmocote 13–13–13, Polyon 18–6–12, Polyon 14–14–14, and Plantacote 14–8–15, were placed in leaching columns containing acid?washed sand. Samples of all leachates were analyzed weekly to determine release rates of ammonium?nitrogen (N), nitrate?N, phosphorus (P), potassium (K), magnesium (Mg), manganese (Mn), and iron (Fe). Release rates for

Timothy K. Broschat; Kimberly K. Moore

2007-01-01

210

Manganese superoxide dismutase depletion in murine hematopoietic stem cells perturbs iron homeostasis, globin switching, and epigenetic control in erythrocyte precursor cells.  

PubMed

Heme synthesis partially occurs in the mitochondrial matrix; thus there is a high probability that enzymes and intermediates important in the production of heme will be exposed to metabolic by-products including reactive oxygen species. In addition, the need for ferrous iron for heme production, Fe/S coordination, and other processes occurring in the mitochondrial matrix suggests that aberrant fluxes of reactive oxygen species in this compartment might perturb normal iron homeostasis. Manganese superoxide dismutase (Sod2) is an antioxidant enzyme that governs steady-state levels of the superoxide in the mitochondrial matrix. Using hematopoietic stem cell-specific conditional Sod2 knockout mice we observed increased superoxide concentrations in red cell progeny, which caused significant pathologies including impaired erythrocytes and decreased ferrochelatase activity. Animals lacking Sod2 expression in erythroid precursors also displayed extramedullary hematopoiesis and systemic iron redistribution. Additionally, the increase in superoxide flux in erythroid precursors caused abnormal gene regulation of hematopoietic transcription factors, globins, and iron-response genes. Moreover, the erythroid precursors also displayed evidence of global changes in histone posttranslational modifications, a likely cause of at least some of the aberrant gene expression noted. From a therapeutic translational perspective, mitochondrially targeted superoxide-scavenging antioxidants partially rescued the observed phenotype. Taken together, our findings illuminate the superoxide sensitivity of normal iron homeostasis in erythrocyte precursors and suggest a probable link between mitochondrial redox metabolism and epigenetic control of nuclear gene regulation during mammalian erythropoiesis. PMID:23219873

Case, Adam J; Madsen, Joshua M; Motto, David G; Meyerholz, David K; Domann, Frederick E

2012-12-05

211

Design and application of rRNA-targeted oligonucleotide probes for the dissimilatory iron- and manganese-reducing bacterium Shewanella putrefaciens.  

PubMed Central

A 16S rRNA-targeted oligonucleotide probe specific for the iron (Fe3+)- and manganese (Mn4+)-reducing bacterium Shewanella putrefaciens was constructed and tested in both laboratory- and field-based hybridization experiments. The radioactively labeled probe was used to detect S. putrefaciens in field samples collected from the water column and sediments of Oneida Lake in New York and its major southern tributary, Chittenango Creek. S. putrefaciens was quantified by (i) hybridization of the probe to bulk RNA extracted from field samples and normalization of the S. putrefaciens-specific rRNA to total eubacterial rRNA, (ii) a colony-based probe hybridization assay, and (iii) a colony-based biochemical assay which detected the formation of iron sulfide precipitates on triple-sugar iron agar. The results of field applications indicated that the three detection methods were comparable in sensitivity for detecting S. putrefaciens in water column and sediment samples. S. putrefaciens rRNA was detected in the surficial layers of the lake and creek sediments, but the levels of S. putrefaciens rRNA were below the detection limits in the lake and creek water samples. The highest concentrations of S. putrefaciens rRNA, corresponding to approximately 2% of the total eubacterial rRNA, were detected in the surficial sediments of Chittenango Creek and at a midlake site where the Oneida Lake floor is covered by a high concentration of ferromanganese nodules. This finding supports the hypothesis that metal-reducing bacteria such as S. putrefaciens are important components in the overall biogeochemical cycling of iron, manganese and other elements in seasonally anoxic freshwater basins. Images

DiChristina, T J; DeLong, E F

1993-01-01

212

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

1963-01-01

213

Long-term removal and retention of iron and manganese from acidic mine drainage by wetlands. Volume 1. Methods, results, and appendices. Final report, July 1987-January 1990  

SciTech Connect

A promising low-technology solution for treating acidic mine drainage (AMD) emanating from coal mined lands involves the use of constructed wetlands. The research was directed at addressing questions about retention mechanisms for the long-term storage of iron and manganese in constructed wetlands dominated by broad-leaved cattails (Typha latifolia). Three sites in central Pennsylvania spanning the range of water chemistry parameters found in AMD were investigated. When the AMD was circumneutral, and metal loadings were low, 79% of the iron, and 48% of the manganese were retained on average. In the highly acidic site (pH approx. = 3), < 10% of the metal loadings were retained. The primary retention mechanism appears to be the formation of metal oxides in the aerobic zones of the sediments. Although most microbial isolates extracted from sediment cores originated in the aerobic portions of the sediments, there was no evidence that they were transforming metals. When AMD is circumneutral and metal loadings are low, constructed wetlands can be an effective approach to treating mine drainage. At sites with highly acidic waters and high metal loadings, the use of constructed wetlands to treat AMD may be ineffectual, and should be implemented with caution.

Brooks, R.P.; Unz, R.F.; Davis, L.K.; Tarutis, W.J.; Yanchunas, J.

1990-01-01

214

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

215

Removal of As(III) in a column reactor packed with iron-coated sand and manganese-coated sand.  

PubMed

The applicability of manganese-coated sand (MCS) and iron-coated sand (ICS) for the treatment of As(III) via oxidation and adsorption processes was investigated. Scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to observe the surface properties of the coated layer. In the batch adsorption, the adsorption rate of As(V) onto ICS was greater than that of As(III), and ICS showed a greater adsorption capacity for the removal of As(V) than As(III). From a bench-scale column test, a column reactor packed with both MCS and ICS was found to be the best system for the treatment of As(III) due to the promising oxidation efficiency of As(III) to As(V) by MCS and adsorption of As(V) by both MCS and ICS. From these bench-scale results, the treatment of synthetic wastewater contaminated with As(III) was investigated using a pilot-scale filtration system packed with equal amounts (each 21.5 kg) of MCS at the bottom and ICS on the top. The height and diameter of the column were 200 and 15 cm, respectively. As(III) solution was introduced into the bottom of the filtration system, at a speed of 5 x 10(-3)cms(-1), over 148 days. The breakthrough of total arsenic in the mid-sampling (end of the MCS bed) and final-sampling (end of the ICS bed) positions began after 18 and 44 days, respectively, and showed complete breakthrough after 148 days. Although the breakthrough of total arsenic in the mid-sampling position began after 18 days, the concentration of As(III) in the effluent was below 50 microg L(-1) for up to 61 days. This result indicates that MCS has sufficient oxidizing capacity for As(III), and 1 kg of MCS can oxidize 93 mg of As(III) for up to 61 days. When the complete breakthrough of total arsenic occurred, the total arsenic removed by 1 kg of MCS was 79.0 mg, suggesting MCS acts as an adsorbent for As(V), as well as an oxidant for As(III). From this work, a filtration system consisting of both MCS and ICS can potentially be used a new treatment system to simultaneously treat As(III) and As(V). PMID:17570581

Chang, Yoon-Young; Song, Ki-Hoon; Yang, Jae-Kyu

2007-05-10

216

Influence of austenitizing temperature on fracture toughness of a low manganese austempered ductile iron (ADI) with ferritic as cast structure  

Microsoft Academic Search

An investigation was carried out to examine the influence of austenitizing temperature on the resultant microstructure and mechanical properties of an unalloyed and low manganese ADI and with an as cast (solidified) ferritic structure. The investigation also examined the influence of austenitizing temperature on the fracture toughness of this material. Compact tension and round cylindrical tensile specimens were prepared from

Susil K Putatunda; Pavan K Gadicherla

1999-01-01

217

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.

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

1995-01-01

218

Effect of lead in water on the absorption of copper, iron, manganese and zinc by sheep (Ovis aries) infected with sheep tapeworm (Moniezia expansa).  

PubMed

The sheep tapeworm (Moniezia expansa) and its host Ovis aries were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) for their copper, iron, manganese, zinc and lead levels. Element concentrations in cestode parasites were compared to those in various organs (liver, kidney, and muscle) of sheep. Tapeworms in the small intestine of sheep that were administered 2g of Pb(CH(3)COO)(2) per os daily (7 days) had significantly higher lead concentrations than sheep tissues. Cu levels significantly increased after Pb administration in sheep muscle and sheep tapeworms. Contrarily, Zn content significantly decreased in sheep muscle, but significantly increased in sheep tapeworms. However, Mn content significantly decreased after Pb administration in sheep tapeworms. Furthermore, Fe content significantly decreased after Pb administration in sheep liver and kidneys. PMID:22425750

Jankovská, I; Száková, J; Lukešová, D; Langrová, I; Válek, P; Vadlejch, J; ?adková, Z; Petrtýl, M

2012-03-08

219

Repeated surveillance of exposure to cadmium, manganese, and arsenic in school-age children living in rural, urban, and nonferrous smelter areas in Belgium  

SciTech Connect

The intensity of exposure to Cd, As, Mn in groups of school-age children living around a lead smelter was assessed. By comparison, groups of children living in an urban and a rural area were also examined. The metal content of blood, urine, hand-rinsing, air, dust, and dirt collected in the school-playground was compared. The urinary excretion of cadmium in children living around the lead smelter is greater than in those living in the urban and in the rural area. In the latter there seems to exist a time-dependent trend in the renal accumulation of cadmium. This suggests that the overall pollution of the environment by cadmium in Belgium is progressively increasing. In the smelter area, both the oral and pulmonary routes play a role in the children's exposure to cadmium. Their relative contribution to the amount of cadmium absorbed appears similar. The concentration of arsenic in urine of children living around the smelter is significantly higher than that of rural children. Speciation of the chemical forms of arsenic in urine indicates that the difference is not due to different dietary habits of the children examined but to different intensity of exposure to inorganic arsenic. The amount of arsenic on the hand of children living at less than 1 km from the smelter (anti X = 17.6 ..mu..g As/hand) was more than 10 times that found in children living at 2.5 km from the plant (anti X = 1.5 ..mu..g As/hand) whereas that found in children living in urban and rural areas was below 0.2 ..mu..g As/hand. The arsenic concentration of dust and dirt collected in the school-playground in the different areas follows the same trend.

Buchet, J.P. (Univ. of Louvain, Brussels, Belgium); Roels, H.; Lauwerys, R.; Bruaux, P.; Claeys-Thoreau, F.; Lafontaine, A.; Verduyn, G.

1980-06-01

220

Toward the Discrimination of Manganese, Zinc, Copper, and Iron Deficiency in `Bragg' Soybean Using Spectral Detection Methods  

Microsoft Academic Search

cence (Fv), Fo\\/Fv; and the ratio of minimal fluorescence to the fluores- cence yield after 5 min of illumination (F5min), Fo\\/F5min. Manganese, Of those studies that compared differences between Zn, Cu, and Fe deficiencies were correctly identified 62, 40, 92, and or among stresses, comparisons were often qualitative, 30% of the time, respectively, as estimated by cross-validation. Con- comparing only

Matthew L. Adams; Wendell A. Norvell; William D. Philpot; John H. Peverly

2000-01-01

221

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

222

Effect of manganese on an iron-based Fischer–Tropsch synthesis catalyst prepared from ferrous sulfate  

Microsoft Academic Search

The effects of manganese on the textural properties, bulk and surface phase compositions, reduction\\/carburization behaviors and surface basicity of an Fe–Mn–K\\/SiO2 catalyst prepared from ferrous sulfate were investigated by N2 physisorption, Mössbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), H2 (or CO) temperature-programmed reduction (TPR) and CO2 temperature-programmed desorption (TPD). The Fischer–Tropsch synthesis (FTS) performance of the catalysts with different contents of

Tingzhen Li; Yong Yang; Chenghua Zhang; Xia An; Haijun Wan; Zhichao Tao; Hongwei Xiang; Yongwang Li; Fan Yi; Binfu Xu

2007-01-01

223

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

224

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 ?H2S 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. %O2 = 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

225

Oxidative precipitation of arsenic(III) with manganese(II) and iron(II) in dilute acidic solution by ozone  

Microsoft Academic Search

Oxidative precipitation using ozone has been examined for removal of arsenic with manganese from dilute acidic sulfate solution under the following conditions: the initial concentrations of arsenic(III) and arsenic(V)=1–100 mg\\/L, the initial mole ratio of Mn\\/As=10–100, pH=0.4–5.0 and temperature=15–80 °C. The oxidation–reduction potential (ORP) of the system was continuously measured to monitor the process of oxidation reactions. The O3–O2 gas

T Nishimura; Y Umetsu

2001-01-01

226

Effect of manganese on the onset of the stage 2 reaction in an austempered ductile iron matrix.  

National Technical Information Service (NTIS)

Austempered ductile irons (ADIs) possess a unique combination of toughness and ductility plus high strength which make them attractive alternatives to other metal castings. ADIs can have tensile strengths up to 230 ksi with a 1% elongation and high hardne...

K. N. Hagen

1990-01-01

227

Iron, manganese and copper concentrations in wet precipitations and kinetics of the oxidation of SO 2 in rain water at two urban sites, Jaipur and Kota, in Western India  

Microsoft Academic Search

Rain-water samples were collected from Jaipur and Kota in Western India during the monsoon seasons of 1996–1999. In all cases, the pH of rain-water samples exceeded 7.0 and fell in the range (7.1–8.5). In view of the fact that the trace metals particularly iron, manganese and copper have been held responsible for the catalytic activity of rain-water, the chemical analysis

S. V Manoj; C. D Mishra; M Sharma; A Rani; R Jain; S. P Bansal; K. S Gupta

2000-01-01

228

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.

229

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

230

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

2010-11-01

231

MtsABC Is Important for Manganese and Iron Transport, Oxidative Stress Resistance, and Virulence of Streptococcus pyogenes  

Microsoft Academic Search

MtsABC is a Streptococcus pyogenes ABC transporter which was previously shown to be involved in iron and zinc accumulation. In this study, we showed that an mtsABC mutant has impaired growth, particularly in a metal-depleted medium and an aerobic environment. In metal-depleted medium, growth was restored by the addition of 10 M MnCl2, whereas other metals had modest or no

Robert Janulczyk; Susanna Ricci; Lars Bjorck

2003-01-01

232

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.

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

2011-01-01

233

Chemical versus Enzymatic Digestion of Contaminated Estuarine Sediment: Relative Importance of Iron and Manganese Oxides in Controlling Trace Metal Bioavailability  

NASA Astrophysics Data System (ADS)

Chemical and enzymatic reagents have been employed to determine available concentrations of Fe, Mn, Cu and Zn in contaminated estuarine sediment. Gastric and intestinal enzymes (pepsin, pH 2, and trypsin, pH 7·6, respectively) removed significantly more metal than was water-soluble or exchangeable (by seawater or ammonium acetate), while gastro-intestinal fluid of the demersal teleost, Pleuronectes platessa L. (plaice), employed to operationally define a bioavailable fraction of contaminants, generally solubilized more metal than the model enzymes. Manganese was considerably more available than Fe under these conditions and it is suggested that the principal mechanism of contaminant release is via surface complexation and reductive solubilization of Mn oxides, a process which is enhanced under conditions of low pH. Of the chemical reagents tested, acetic acid best represents the fraction of Mn (as well as Cu and Zn) which is available under gastro-intestinal conditions, suggesting that the reducing tendency of acetate is similar to that of the ligands encountered in the natural digestive environment. Although the precise enzymatic and non-enzymatic composition of plaice gastro-intestinal fluid may be different to that encountered in more representative, filter-feeding or burrowing organisms, a general implication of this study is that contaminants associated with Mn oxides are significantly more bioavailable than those associated with Fe oxides, and that contaminant bioavailability may be largely dictated by the oxidic composition of contaminated sediment.

Turner, A.; Olsen, Y. S.

2000-12-01

234

IRON  

Technology Transfer Automated Retrieval System (TEKTRAN)

Iron is an essential mineral. Although abundant in nature, it is mostly insoluble and biological absorbable forms are limited to most organisms. Iron is of fundamental importance to a variety of iron-containing proteins, especially the oxygen-carrying molecules hemoglobin and myoglobin. Iron may als...

235

The magnetism of metallic manganese alloys  

SciTech Connect

The magnetic excitations in antiferromagnetic manganese-copper and manganese-iron alloys are characterized by high spin-wave velocities, and energy gap at long wavelengths and wavelength dependent damping. There are strong elastic constant anomalies above T[sub N] as well as magnetoelastic distortions below T[sub N]. The theoretical explanation of these effects is reviewed.

Holden, T.M. (Atomic Energy of Canada Ltd., Chalk River, ON (Canada)); Mikke, K. (Institute of Atomic Energy, Otwock-Swierk (Poland)); Fawcett, E. (Toronto Univ., ON (Canada)); Fernandez-Baca, J.A. (Oak Ridge National Lab., TN (United States))

1992-01-01

236

The magnetism of metallic manganese alloys  

SciTech Connect

The magnetic excitations in antiferromagnetic manganese-copper and manganese-iron alloys are characterized by high spin-wave velocities, and energy gap at long wavelengths and wavelength dependent damping. There are strong elastic constant anomalies above T{sub N} as well as magnetoelastic distortions below T{sub N}. The theoretical explanation of these effects is reviewed.

Holden, T.M. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada); Mikke, K. [Institute of Atomic Energy, Otwock-Swierk (Poland); Fawcett, E. [Toronto Univ., ON (Canada); Fernandez-Baca, J.A. [Oak Ridge National Lab., TN (United States)

1992-12-31

237

Application of Zeeman graphite furnace atomic absorption spectrometry with high-frequency modulation polarization for the direct determination of aluminum, beryllium, cadmium, chromium, mercury, manganese, nickel, lead, and thallium in human blood.  

PubMed

Determination of aluminum (Al), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and thallium (Tl) concentrations in human blood using high-frequency modulation polarization Zeeman graphite furnace atomic absorption spectrometry (GFAAS) was performed. No sample digestion was used in the current study. Blood samples were diluted with deionized water or 0.1 % (m/v) Triton X-100 solution for Tl. Dilution factors ranged from 1/5 per volume for Be and Tl to 1/20 per volume for Cd and Pb. For Tl, Cd, and Hg, noble metals (gold, platinum, rhodium, etc.) were applied as surface modifiers. To mitigate chloride interference, 2 % (m/v) solution of NH(4)NO(3) was used as matrix modifier for Tl and Ni assessment. The use of Pd(NO(3))(2) as oxidative modifier was necessary for blood Hg and Tl measurement. Validation of the methods was performed by analyzing two-level reference material Seronorm. The precision of the designed methods as relative SD was between 4 and 12 % (middle of a dynamic range) depending on the element. For additional validation, spiked blood samples were analyzed. Limits of detection (LoDs, 3?, n = 10) for undiluted blood samples were 2.0 ?g L(-1) for Al, 0.08 ?g L(-1) for Be, 0.10 ?g L(-1) for Cd, 2.2 ?g L(-1) for Cr, 7 ?g L(-1) for Hg, 0.4 ?g L(-1) for Mn, 2.3 ?g L(-1) for Ni, 3.4 ?g L(-1) for Pb, and 0.5 ?g L(-1) for Tl. The LoDs achieved allowed determination of Al, Cd, Cr, Mn, Ni, and Pb at both toxic and background levels. Be, Hg, and Tl could be reliably measured at toxic levels only. The methods developed are used for clinical diagnostics and biological monitoring of work-related exposure. PMID:22868581

Ivanenko, Natalya B; Solovyev, Nikolay D; Ivanenko, Anatoly A; Ganeev, Alexander A

2012-08-07

238

Hydrogenation of carbon monoxide over Raney iron-manganese catalysts: effect of leaching reagents on activity and selectivity  

SciTech Connect

The activity and selectivity of Raney Fe-Mn catalysts for the production of low molecular weight olefins (C/sub 2/-C/sub 4/) from H/sub 2/ and CO were investigated. The Raney catalysts were prepared by extracting Al from an Fe-Mn-Al alloy with different reagents including NaOH, KOH, LiOH, and NH/sub 4/OH. The data on the extent of Al extraction indicated that NaOH was the most effective leaching reagent. The ratios of Fe to Mn remained constant in the catalysts regardless of the leaching agent used, while the Al content of the catalysts was found to be dependent on the degree of leaching. The NaOH and KOH leached catalysts chemisorbed greater amounts of H/sub 2/ and CO. The NaOH and LiOH leached catalysts were more selective for low molecular weight olefins. The activity of the KOH leached catalyst was similar to that of the NaOH leached catalyst. Magnetite were found in the NaOH leached catalyst, while a mixed phase comprised of ..cap alpha..-iron, magnetite and FeAl/sub 3/ was identified in the other catalysts by X-ray diffraction study. The presence of an ..cap alpha..-iron phase was identified in all the reduced catalysts. Except for the NaOH leached catalyst, FeAl/sub 3/ was also identified in all the reduced catalysts. The predominant carbide phase in the spent KOH leached catalyst was Chi-Fe/sub 5/C/sub 2/ while the predominant carbide phase in the other spent catalysts was epsilon-Fe/sub 2.2/C. Surface Fe was determined to be present as an iron oxide phase after leaching, and as an Fe metal phase after reduction by ESCA (Electron Spectroscopy for Chemical Analysis). The Mn was found to be in the oxide state during all stages in the life of the catalysts. The spent catalyst surface was found to be almost completely covered by carbon for the NaOH leached, KOH leached and coprecipitated catalysts, while relatively smaller portions of the catalyst surface were covered by carbon for the spent LiOH leached and NH/sub 4/OH leached catalysts.

Chen, K.R.

1986-01-01

239

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

240

Multiobjective Optimization of Manganese Recovery from Sea Nodules Using Genetic Algorithms  

Microsoft Academic Search

Treatment of low grade manganese ores is receiving widespread attention due to major use of manganese (85–90%) as ferromanganese alloy in the rapidly growing iron and steel sector and also in other important industrial products like electrolytic manganese dioxide (EMD) used in the energy sector. Manganese bearing polymetallic sea nodules containing less than 40% Mn fall in the category of

Arijit Biswas; N. Chakraborti; P. K. Sen

2008-01-01

241

Iron  

MedlinePLUS

... high in calories but low in vitamins and minerals. Sugar sweetened sodas and most desserts are examples ... higher doses of iron supplementation [ 86 ]. Iron and mineral interactions Some researchers have raised concerns about interactions ...

242

An estimate of the efficiency of the iron- and manganese-driven dissolved inorganic phosphorus trap at an oxic/euxinic water column redoxcline  

NASA Astrophysics Data System (ADS)

Geochemical records suggest the ocean has undergone periods of at least partial deeper-ocean anoxia or euxinia. Two counteracting feedback loops involving redox control of the dynamics of the phytoplankton nutrient dissolved inorganic phosphorus (DIP) might coexist, helping to stabilize the redox state of the atmosphere and oceans. This concept implies that, during deeper-ocean anoxia, the DIP transfer from the deep anoxic into the oxic surface ocean is uninhibited by processes taking place at the redoxcline. This implicit assumption requires testing because iron (Fe) and manganese (Mn) dynamics at oxic/anoxic water column redoxclines have the potential to form a DIP trap, inhibiting DIP transport from anoxic deep into oxic surface waters. Using a time series data set of Fe, Mn, DIP, and dissolved oxygen distributions in the Eastern Gotland Basin of the Baltic Sea, we provide estimates of the efficiency of this Fe- and Mn-driven DIP trap. This efficiency was estimated by calculating the ratios of (1) the downward flux of DIP adsorbed onto and/or coprecipitated into the settling authigenic Fe- and Mn-rich particles just above the redoxcline and (2) the upward turbulent-diffusive DIP flux across the redoxcline. Depending on the assumed particle densities, we find average ±1 SD trapping efficiencies of 0.38 ± 0.29 and 0.63 ± 0.45. The efficiencies are significant in that they seem to impact cyanobacterial dynamics in the central Baltic Sea. We discuss possible implications of the trapping mechanism for, and propose two hypotheses relating to the potential importance of Fe-controlled DIP trapping at redoxclines during, ocean anoxic events.

Turnewitsch, Robert; Pohl, Christa

2010-12-01

243

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

244

IRON  

EPA Science Inventory

The document surveys the effects of organic and inorganic iron that are relevant to humans and their environment. The biology and chemistry of iron are complex and only partially understood. Iron participates in oxidation reduction processes that not only affect its geochemical m...

245

US Food and Drug Administration survey of cadmium, lead and other elements in clams and oysters.  

PubMed

In Fiscal Years 1985/1986, the US Food and Drug Administration conducted a survey of cadmium, lead and other elements in fresh clams and oysters collected from US coastal areas in use for shellfish production. Shellfish were analysed for cadmium and lead by using a dry ash-anodic stripping voltammetric method. Other elements (aluminium, arsenic, beryllium, calcium, chromium, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, phosphorus, potassium, selenium, sodium, strontium, vanadium and zinc) were determined by using inductively coupled plasma-atomic emission spectrometry, direct current plasma-atomic emission spectrometry or hydride generation atomic absorption spectrometry. A total of 75 hardshell clam, 59 softshell clam, 104 Eastern oyster and 40 Pacific oyster samples were analysed for cadmium and lead. Average levels found were 0.09, 0.05, 0.51 and 1.1 mg/kg wet weight for cadmium and 0.24, 0.30, 0.11 and 0.06 mg/kg wet weight for lead in hardshell clams, softshell clams, Eastern oysters and Pacific oysters, respectively. The other 19 elements were determined in 10-104 samples of the four types of shellfish. These data provide baseline values for elements in clams and oysters harvested from US coastal waters. PMID:8799717

Capar, S G; Yess, N J

1996-07-01

246

Oxidation of manganese and iron by Leptothrix discophora: Use of N,N,N prime ,N prime -tetramethyl-p-phenylenediamine as an indicator of metal oxidation  

Microsoft Academic Search

A new method for the quantification and characterization of manganese-oxidizing activity by spent culture medium of Leptothrix discophora SS-1 was developed. It is based on the formation of the dye Wurster blue from N,N,Nâ²,Nâ²-tetramethyl-p-phenylenediamine by oxidized manganese generated in the spent medium. The kinetic parameters thus obtained agreed well with data obtained with other methods. It was also possible to

E. W. de Vrind-de Jong; P. L. A. M. Corstjens; E. S. Kempers; P. Westbroek; J. P. M. de Vrind

1990-01-01

247

Cast B2-phase iron-aluminum alloys with improved fluidity  

DOEpatents

Systems and methods are described for iron aluminum alloys. A composition includes iron, aluminum and manganese. A method includes providing an alloy including iron, aluminum and manganese; and processing the alloy. The systems and methods provide advantages because additions of manganese to iron aluminum alloys dramatically increase the fluidity of the alloys prior to solidification during casting.

Maziasz, Philip J. (122 Clark La., Oak Ridge, TN 37830); Paris, Alan M. (P.O. Box 64, Tarrs, PA 15688); Vought, Joseph D. (124 Cove Point Rd., Rockwood, TN 37854)

2002-01-01

248

The use of Apatite II™ to remove divalent metal ions zinc(II), lead(II), manganese(II) and iron(II) from water in passive treatment systems: column experiments.  

PubMed

The conventional passive treatments for remediation of acid mine drainage using calcite are not totally efficient in the removal of certain heavy metal ions. Although pH increases to 6-7 and promotes the precipitation of trivalent and some divalent metals as hydroxides and carbonates, the remaining concentrations of some divalent metals ions do not fulfill the environmental regulations. In this study, Apatite II™, a biogenic hydroxyapatite, is used as an alternative reactive material to remove Zn(II), Pb(II), Mn(II) and Fe(II). Apatite II™ reacted with acid water releasing phosphate and increasing pH up to 6.5-7, inducing metals to precipitate mainly as metal-phosphates: zinc precipitated as hopeite, Zn(3)(PO(4))(2)·4H(2)O, lead as pyromorfite, Pb(5)(PO(4))(3)OH, manganese as metaswitzerite, Mn(3)(PO(4))(2)·4H(2)O and iron as vivianite, Fe(3)(PO(4))(2)·8H(2)O. Thus, metal concentrations from 30 to 75 mg L(-1) in the inflowing water were depleted to values below 0.10 mg L(-1). Apatite II™ dissolution is sufficiently fast to treat flows as high as 50 m/a. For reactive grain size of 0.5-3mm, the treatment system ends due to coating of the grains by precipitates, especially when iron and manganese are present in the solution. PMID:20851514

Oliva, Josep; De Pablo, Joan; Cortina, José-Luis; Cama, Jordi; Ayora, Carlos

2010-08-21

249

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

250

Altered transition metal homeostasis in mice following manganese injections for manganese-enhanced magnetic resonance imaging.  

PubMed

In manganese-enhanced magnetic resonance imaging (MEMRI), the paramagnetic divalent ion of manganese (Mn(2+)) is injected into animals to generate tissue contrast, typically at much higher exposures than have been previously used in studies of Mn toxicity. Here we investigate the effect of these injections on the homeostasis of the transition metals iron and copper in mice to see if there are disruptions which should be considered in MEMRI studies. Manganese shares transport proteins with other transition metals including iron and copper, so it is possible that changes in manganese levels in tissue following injections of the metal may affect other metal levels too. This in turn may affect MRI contrast or the investigation of disease processes in the animal models being imaged. In this study, we measured manganese, iron, and copper concentrations in the blood, kidney, liver and in brain regions in mice treated with four injections of 30 mg/kg MnCl(2) 4H(2)O (dry chemical weight/body weight)-a common dose used in MEMRI. In addition to the expected increases in manganese in tissues, we noted a statistically significant reduction in copper in the kidney and liver. Also, we noted a statistically significant decrease in concentration of iron in the thalamus of the brain. These findings suggest that the high doses of manganese injected in MEMRI studies can disrupt the homeostasis of other transition metals in mice. PMID:23334711

Moldovan, Nataliya; Al-Ebraheem, Alia; Miksys, Nelson A; Farquharson, Michael J; Bock, Nicholas A

2013-01-19

251

Lithium-manganese oxide rechargeable battery  

SciTech Connect

A new type of rechargeable battery in which lithium ions shuttle between a lithium-manganese oxide electrode and a carbon electrode was unveiled recently by chemists from Bell Communications Research (Bellcore), Red Bank, N.J. The new battery--still experimental--is safer, longer lasting, and potentially cheaper to manufacture than other lithium-ion batteries. In addition, it provides three times the energy of nickel-cadmium cells, the most popular type of rechargeable battery. Bellcore scientists believe the new battery could replace nickel-cadmium and small lead-acid batteries in many applications.

Dagani, R.

1993-01-04

252

Structural Features of Manganese Precipitating Bacteria  

NASA Astrophysics Data System (ADS)

Studies of biological communities of the past (and their associated activities) are usually dependent upon preservation of fossil material. With bacteria this rarely occurs because of the absence of sufficient fossilizable cellular material. However, some bacteria deposit metabolic products that can, conditions allowing, be preserved indefinitely. In particular, manganese and iron depositing bacteria have the capacity to form preservable microfossils. In order to better understand these microfossils of the past, we have examined present day morphologies of manganese oxidizing bacteria. These bacteria are highly pleomorphic, depending on the growth medium, the age of the culture, and the extent of manganese oxidation. Transmission electron microscopy indicates that manganese may be deposited either intra-or extra-cellularly. The prognosis of the use of morphological information for the interpretation of ancient and modern manganese deposits is discussed.

Nealson, Kenneth H.; Tebo, Bradley

1980-06-01

253

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

2012-08-01

254

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

NASA Astrophysics Data System (ADS)

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 optimized method has been employed to digest standard reference materials and hair samples of residents of India, collected from different age groups and sex, and analyzed for Fe, Co, Ni, Mn, Zn, Cu, Cd and Pb. The values agree for most of the metals with the data reported for human hair samples of residents of India. The NIES CRM Human Hair No. 5 and IAEA Reference Hair HH-1 certified reference materials were used in order to verify the accuracy of the method and the results were in excellent agreement with the certified values.

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

2002-08-01

255

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

256

Impact of two iron(III) chelators on the iron, cadmium, lead and nickel accumulation in poplar grown under heavy metal stress in hydroponics.  

PubMed

Poplar (Populus jacquemontiana var. glauca cv. Kopeczkii) was grown in hydroponics containing 10 ?M Cd(II), Ni(II) or Pb(II), and Fe as Fe(III) EDTA or Fe(III) citrate in identical concentrations. The present study was designed to compare the accumulation and distribution of Fe, Cd, Ni and Pb within the different plant compartments. Generally, Fe and heavy-metal accumulation were higher by factor 2-7 and 1.6-3.3, respectively, when Fe(III) citrate was used. Iron transport towards the shoot depended on the Fe(III) chelate and, generally, on the heavy metal used. Lead was accumulated only in the root. The amounts of Fe and heavy metals accumulated by poplar were very similar to those of cucumber grown in an identical way, indicating strong Fe uptake regulation of these two Strategy I plants: a cultivar and a woody plant. The Strategy I Fe uptake mechanism (i.e. reducing Fe(III) followed by Fe(II) uptake), together with the Fe(III) chelate form in the nutrient solution had significant effects on Fe and heavy metal uptake. Poplar appears to show phytoremediation potential for Cd and Ni, as their transport towards the shoot was characterized by 51-54% and 26-48% depending on the Fe(III) supply in the nutrient solution. PMID:22305049

Mihucz, Victor G; Csog, Árpád; Fodor, Ferenc; Tatár, Enik?; Szoboszlai, Norbert; Silaghi-Dumitrescu, Lumini?a; Záray, Gyula

2012-02-02

257

Relation of arsenic, iron, and manganese in ground water to aquifer type, bedrock lithogeochemistry, and land use in the New England coastal basins  

USGS Publications Warehouse

In a study of arsenic concentrations in public-supply wells in the New England Coastal Basins, concentrations at or above 0.005 mg/L (milligrams per liter) were detected in more samples of water from wells completed in bedrock (25 percent of all samples) than in water from wells completed in stratified drift (7.5 percent of all samples). Iron and manganese were detected (at concentrations of 0.05 and 0.03 mg/L, respectively) at approximately the same frequency in water from wells in both types of aquifers. Concentrations of arsenic in public-supply wells drilled in bedrock (in the National Water-Quality Assessment Program New England Coastal Basins study unit) vary with the bedrock lithology. Broad groups of lithogeochemical units generalized from bedrock lithologic units shown on state geologic maps were used in the statistical analyses. Concentrations of arsenic in water from public-supply wells in metasedimentary bedrock units that contain slightly to moderately calcareous and calcsilicate rocks (lithogeochemical group Mc) were significantly higher than the concentrations in five other groups of bedrock units in the study unit. Arsenic was detected, at or above 0.005 mg/L, in water from 44 percent of the wells in the lithogeochemical group M c and in water from less than 28 percent of wells in the five other groups. Additionally, arsenic concentrations in ground water were the lowest in the metasedimentary rocks that are characterized as variably sulfidic (group Ms ). Generally, concentrations of arsenic were low in water from bedrock wells in the felsic igneous rocks (group If ) though locally some bedrock wells in granitic rocks are known to have ground water with high arsenic concentrations, especially in New Hampshire. The concentrations of arsenic in ground water also correlate with land-use data; significantly higher concentrations are found in areas identified as agricultural land use than in undeveloped areas. There is, however, more agricultural land in areas overlying the metasedimentary rocks of lithogeochemical groups Mc and the minimally-deformed clastic sediments of group Mmd than in areas overlying other lithogeochemical groups. This correlation complicates the interpretation of sources of arsenic to ground water in bedrock. A test of this association revealed that relations between arsenic concentrations and the metasedimentary rocks of group Mc are not weakened when data associated with agricultural land use is removed; the reverse is true, however, if the data associated with the group Mc are removed from the analysis. The occurrence and variability of arsenic in water from bedrock supply wells could be related to several factors. These include (1) the distribution and chemical form of arsenic in soils and rocks that are part of the ground-water-flow system, (2) the characteristics that influence the solubility and transport of arsenic in ground water, (3) the differing degrees of vulnerability of ground-water supplies to surface contamination, and (4) the spatial associations between land use, geology, and ground-water-flow patterns. Strong relations between agricultural land use and the metasedimentary rocks of group Mc complicate the interpretation of arsenic source to water in these bedrock aquifers. This is due in part to the past use of arsenical pesticides; additionally, few whole-rock geochemical data are available for the rock types in the lithogeochemical groups of aquifers that contain ground water with elevated concentrations of arsenic. Without such data, identifying specific bedrock types as arsenic sources is not possible. In southern Maine and south-central New Hampshire, and in northern Massachusetts, the few available whole-rock analyses suggest, at least for these local areas, a connection between known bedrock chemistry and ground-water arsenic levels. Although the lithogeochemical group and land-use category variables individually describe much of the variance in the concentrations of

Ayotte, Joseph D.; Nielsen, Martha G.; Robinson, Gilpin R., Jr.; Moore, Richard B.

1999-01-01

258

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

1999-08-01

259

Lithium-manganese oxide rechargeable battery  

Microsoft Academic Search

A new type of rechargeable battery in which lithium ions shuttle between a lithium-manganese oxide electrode and a carbon electrode was unveiled recently by chemists from Bell Communications Research (Bellcore), Red Bank, N.J. The new battery--still experimental--is safer, longer lasting, and potentially cheaper to manufacture than other lithium-ion batteries. In addition, it provides three times the energy of nickel-cadmium cells,

Dagani

1993-01-01

260

Manganese exposure in foundry furnacemen and scrap recycling workers  

Microsoft Academic Search

Objectives: Cast iron products are alloyed with small quantities of manganese, and foundry furnacemen are potentially exposed to manganese\\u000a during tapping and handling of smelts. Manganese is a neurotoxic substance that accumulates in the central nervous system,\\u000a where it may cause a neurological disorder that bears many similarities to Parkinson's disease. The aim of the study was to\\u000a investigate the

F. Lander; J. Kristiansen; J. M. Lauritsen

1999-01-01

261

Liver Manganese in Hemochromatosis.  

National Technical Information Service (NTIS)

A comparative study was performed in which the manganese concentration in liver samples from cases of hemochromatosis was compared with the manganese concentration of normal liver. A higher mean concentration of liver manganese was found in the former gro...

L. B. Altstatt S. Pollack M. H. Feldman R. C. Reba W. H. Crosby

1966-01-01

262

Manganese potentiates nitric oxide production by microglia.  

PubMed

Manganese toxicity has been associated with clinical symptoms of neurotoxicity which are similar to the symptoms observed in Parkinson's disease. Earlier reports indicated that reactive microglia was present in the substantia nigra of patients with Parkinson's disease. Using N9 microglial cells, the current study was designed to determine whether high levels of manganese were associated with microglial activation. Results indicated that manganese significantly increased the bacterial lipopolysaccharide-induced nitric oxide production. This potent activity of manganese was not shared by other transition metals tested, including iron, cobalt, nickel, copper and zinc. Immunohistochemical staining and Western blot analysis indicated that manganese increased the cellular production of inducible nitric oxide synthase. Northern blot analysis indicated that manganese likely increased iNOS gene transcription since this agent increased the mRNA level of the inducible nitric oxide synthase. In contrast to other transition metals tested, manganese did not appear to be cytotoxic to microglial cells. These results suggested that manganese could induce sustained production of neurotoxic nitric oxide by activated microglial cells, which might cause detrimental consequences to surrounding neurons. PMID:10320780

Chang, J Y; Liu, L Z

1999-05-01

263

Thermodynamics of carbon and oxygen solutions in manganese melts  

NASA Astrophysics Data System (ADS)

The thermodynamics of carbon and oxygen solutions in manganese melts is studied. An equation for the temperature dependence of the activity coefficient of carbon in liquid manganese is obtained (?{C(Mn)/0}= -1.5966 + (1.0735 × 10-3) T). The temperature dependence of the Gibbs energy of the reaction of carbon dissolved in liquid manganese with the oxygen of manganese oxide is shown to be described by the equation ? G {T/0}= 375264 - 184.66 T(J/mol). This reaction can noticeably be developed depending on the carbon content at temperatures of 1700 1800°C. The deoxidation ability of carbon in manganese melts is shown to be much lower than that in iron and nickel melts due to the higher affinity of manganese to both oxygen and carbon. Although the deoxidation ability of carbon in manganese melts increases with temperature, the process develops at rather high carbon contents in all cases.

Dashevskii, V. Ya.

2007-12-01

264

Precipitation of manganese ammonium phosphate from homogeneous solution.  

PubMed

Precipitation of manganese, zinc and cadmium ammonium phosphates from homogeneous solution by decomposition of metal EDTA complexes by boiling with hydrogen peroxide in presence of phosphate has been investigated. Precipitation of Cd is not quantitative, but of Mn is complete in 2 hr, and of Zn in 6 hr. PMID:18960650

Buzágh-Gere, E; Erdey, L

1969-10-01

265

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

266

Does hydrogen-bonding donation to manganese(IV)-oxo and iron(IV)-oxo oxidants affect the oxygen-atom transfer ability? A computational study.  

PubMed

Iron(IV)-oxo intermediates are involved in oxidations catalyzed by heme and nonheme iron enzymes, including the cytochromes P450. At the distal site of the heme in P450 Compound?I (Fe(IV) -oxo bound to porphyrin radical), the oxo group is involved in several hydrogen-bonding interactions with the protein, but their role in catalysis is currently unknown. In this work, we investigate the effects of hydrogen bonding on the reactivity of high-valent metal-oxo moiety in a nonheme iron biomimetic model complex with trigonal bipyramidal symmetry that has three hydrogen-bond donors directed toward a metal(IV)-oxo group. We show these interactions lower the oxidative power of the oxidant in reactions with dehydroanthracene and cyclohexadiene dramatically as they decrease the strength of the O?H bond (BDEOH ) in the resulting metal(III)-hydroxo complex. Furthermore, the distal hydrogen-bonding effects cause stereochemical repulsions with the approaching substrate and force a sideways attack rather than a more favorable attack from the top. The calculations, therefore, give important new insights into distal hydrogen bonding, and show that in biomimetic, and, by extension, enzymatic systems, the hydrogen bond may be important for proton-relay mechanisms involved in the formation of the metal-oxo intermediates, but the enzyme pays the price for this by reduced hydrogen atom abstraction ability of the intermediate. Indeed, in nonheme iron enzymes, where no proton relay takes place, there generally is no donating hydrogen bond to the iron(IV)-oxo moiety. PMID:23362213

Latifi, Reza; Sainna, Mala A; Rybak-Akimova, Elena V; de Visser, Sam P

2013-01-30

267

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

Microsoft Academic Search

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 upregu- lated 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

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

268

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

269

Improved Manganese Phosphate Coatings.  

National Technical Information Service (NTIS)

Work was conducted to determine the mechanism by which superior manganese phosphate coatings are produced. The phosphate coatings were applied at temperatures above 212 F and with manganese-organic compounds added to the phosphating solution. Experimental...

H. Crain

1975-01-01

270

ZIP8 Is an Iron and Zinc Transporter Whose Cell-surface Expression Is Up-regulated by Cellular Iron Loading*  

PubMed Central

ZIP8 (SLC39A8) belongs to the ZIP family of metal-ion transporters. Among the ZIP proteins, ZIP8 is most closely related to ZIP14, which can transport iron, zinc, manganese, and cadmium. Here we investigated the iron transport ability of ZIP8, its subcellular localization, pH dependence, and regulation by iron. Transfection of HEK 293T cells with ZIP8 cDNA enhanced the uptake of 59Fe and 65Zn by 200 and 40%, respectively, compared with controls. Excess iron inhibited the uptake of zinc and vice versa. In RNA-injected Xenopus oocytes, ZIP8-mediated 55Fe2+ transport was saturable (K0.5 of ?0.7 ?m) and inhibited by zinc. ZIP8 also mediated the uptake of 109Cd2+, 57Co2+, 65Zn2+ > 54Mn2+, but not 64Cu (I or II). By using immunofluorescence analysis, we found that ZIP8 expressed in HEK 293T cells localized to the plasma membrane and partially in early endosomes. Iron loading increased total and cell-surface levels of ZIP8 in H4IIE rat hepatoma cells. We also determined by using site-directed mutagenesis that asparagine residues 40, 88, and 96 of rat ZIP8 are glycosylated and that N-glycosylation is not required for iron or zinc transport. Analysis of 20 different human tissues revealed abundant ZIP8 expression in lung and placenta and showed that its expression profile differs markedly from ZIP14, suggesting nonredundant functions. Suppression of endogenous ZIP8 expression in BeWo cells, a placental cell line, reduced iron uptake by ?40%, suggesting that ZIP8 participates in placental iron transport. Collectively, these data identify ZIP8 as an iron transport protein that may function in iron metabolism.

Wang, Chia-Yu; Jenkitkasemwong, Supak; Duarte, Stephanie; Sparkman, Brian K.; Shawki, Ali; Mackenzie, Bryan; Knutson, Mitchell D.

2012-01-01

271

Astrocytes and manganese neurotoxicity  

Microsoft Academic Search

Increasing evidence suggests that astrocytes are the site of early dysfunction and damage in manganese neurotoxicity. Astrocytes accumulate manganese by a high affinity, high capacity, specific transport system. Chronic exposure to manganese leads to increased pallidal signal hyperintensities on T1-weighted magnetic resonance images and selective neuronal loss in basal ganglia structures together with characteristic astrocytic changes known as Alzheimer type

Alan S Hazell

2002-01-01

272

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.

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

2012-01-01

273

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

PubMed

Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 10(6) acetate-utilizing manganese-reducing cells cm(-3) in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments. PMID:22572639

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

2012-05-10

274

Manganese import is a key element of the OxyR response to hydrogen peroxide in Escherichia coli  

PubMed Central

Very little manganese is imported into Escherichia coli under routine growth conditions: the import system is weakly expressed, the manganese content is low, and a manganese-dependent enzyme is not correctly metallated. Mutants that lack MntH, the importer, grow at wild-type rates, indicating that manganese plays no critical role. However, MntH supports the growth of iron-deficient cells, suggesting that manganese can substitute for iron in activating at least some metalloenzymes. MntH is also strongly induced when cells are stressed by hydrogen peroxide. This adaptation is essential, as E. coli cannot tolerate peroxide stress if mntH is deleted. Other workers have observed that manganese improves the ability of a variety of microbes to tolerate oxidative stress, and the prevailing hypothesis is that manganese does so by chemically scavenging hydrogen peroxide and/or superoxide. We found that manganese does not protect peroxide-stressed cells by scavenging peroxide. Instead, the beneficial effects of manganese correlate with its ability to metallate mononuclear enzymes. Because iron-loaded enzymes are vulnerable to the Fenton reaction, the substitution of manganese may prevent protein damage. Accordingly, during H2O2 stress, mutants that cannot import manganese and/or are unable to sequester iron suffer high rates of protein oxidation.

Anjem, Adil; Varghese, Shery; Imlay, James A.

2009-01-01

275

Terrestrial manganese-53 — A new monitor of Earth surface processes  

NASA Astrophysics Data System (ADS)

We report the first systematic study of the terrestrial cosmogenic radionuclide manganese-53 ( T1/2 = 3.7 Ma) measured in thirteen samples from nine dolerite surfaces in the Dry Valleys, Antarctica. The terrestrial manganese-53 concentrations correlate well with cosmic-ray-produced helium-3 and neon-21 concentrations in the same samples, implying that the manganese-53 is produced continuously in situ and retained quantitatively over millions of years. The terrestrial manganese-53 production rate determination normalized to iron (the only important target element) and to high-latitude and sealevel yields a value of P53 = 103 ± 11 atoms yr - 1 (g Fe) - 1 . This is consistent with the theoretical value of 120 ± 18 atoms yr - 1 (g Fe) - 1 obtained from modeling calculations. Our results show that the manganese-53 concentrations in bulk terrestrial rocks can be used to monitor Earth surface processes on time-scales exceeding 10 My.

Schaefer, Joerg M.; Faestermann, Thomas; Herzog, Gregory F.; Knie, Klaus; Korschinek, Gunther; Masarik, Jozef; Meier, Astrid; Poutivtsev, Michail; Rugel, Georg; Schlüchter, Christian; Serifiddin, Feride; Winckler, Gisela

2006-11-01

276

Treatability of manganese by sodium silicate and chlorine  

SciTech Connect

Manganese sequestering by nearly simultaneous additions of sodium silicate and sodium hypochlorite was studied in laboratory-prepared waters. Under conditions of near-neutral pH and 150-250 mg/liter of alkalinity as CaCO{sub 3}, 1-2 mg manganese/liter could be sequestered for up to one day. Less effective manganese treatability was found at pH 8 than at pH 7. Additionally, at pH 7 the best results were obtained when neither silicate nor hypochlorite was added because of the slow manganese oxidation rate by oxygen alone. Aging of diluted stock silicate solutions prior to dosing also resulted in poor treatment; the presence of background silica increased the treatment effectiveness only slightly. Overall, manganese was less treatable by this method than iron under the same treatment conditions.

Robinson, F.B.; Ronk, S.K. (Tennessee Univ., Knoxville (USA))

1987-11-01

277

Manganese action in brain function  

Microsoft Academic Search

Manganese, an essential trace metal, is supplied to the brain via both the blood–brain and the blood–cerebrospinal fluid barriers. There are some mechanisms in this process and transferrin may be involved in manganese transport into the brain. A large portion of manganese is bound to manganese metalloproteins, especially glutamine synthetase in astrocytes. A portion of manganese probably exists in the

Atsushi Takeda

2003-01-01

278

Hydrolysis of an organophosphate ester by manganese dioxide.  

PubMed

Amorphous manganese dioxide facilitates the hydrolysis of p-nitrophenyl phosphate to p-nitrophenol and orthophosphate despite insignificant adsorption of p-nitrophenyl phosphate or p-nitrophenol to the manganese dioxide. At pH 8, the orthophosphate product is released into solution; at pH 4 and pH 6, some remains adsorbed. The rate of hydrolysis is an order of magnitude more rapid than the same reaction facilitated by iron oxides. Because manganese dioxides are ubiquitous components of soils and sediments, this suggests the possibility of significant abiotic pathways for the formation of bioavailable orthophosphate from phosphate ester precursors. PMID:11349282

Baldwin, D S; Beattie, J K; Coleman, L M; Jones, D R

2001-02-15

279

Zinc dependence of zinT (yodA) mutants and binding of zinc, cadmium and mercury by ZinT  

SciTech Connect

ZinT (B1973), previously known as YodA, was originally characterised as a cadmium-induced periplasmic protein under the regulation of Fur and SoxS. Here we describe a decrease in zinT transcript in response to elevated copper concentrations and the zinc and copper dependent phenotype of a {delta}zinT strain. Cadmium sensitivity of the {delta}zinT strain was not observed. We demonstrate the binding of nickel, zinc, cadmium, and mercury, but not cobalt, copper, iron, and manganese, to purified ZinT using mass spectrometry. This and previous studies support the hypothesis that ZinT plays a role in zinc homeostasis and is required for growth under zinc limited conditions, suggesting that ZinT is either a periplasmic zinc chaperone or is involved in zinc import. Limited metal ion discrimination results in regulation of PzinT in a non-specific manner, which is mirrored in the binding of several different heavy metals by ZinT.

Kershaw, Christopher J.; Brown, Nigel L. [School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Hobman, Jon L. [School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)], E-mail: jon.hobman@nottingham.ac.uk

2007-12-07

280

Non-heme manganese catalase - the 'other' catalase  

PubMed Central

Non-heme manganese catalases are widely distributed over microbial life and represent an environmentally important alternative to heme-containing catalases in antioxidant defense. Manganese catalases contain a binuclear manganese complex as their catalytic active site rather than a heme, and cycle between Mn2(II,II) and Mn2(III,III) states during turnover. X-ray crystallography has revealed the key structural elements of the binuclear manganese active site complex that can serve as the starting point for computational studies on the protein. Four manganese catalase enzymes have been isolated and characterized, and the enzyme appears to have a broad phylogenetic distribution including both bacteria and archae. More than 100 manganese catalase genes have been annotated in genomic databases, although the assignment of many of these putative manganese catalases needs to be experimentally verified. Iron limitation, exposure to low levels of peroxide stress, thermostability and cyanide resistance may provide the biological and environmental context for the occurrence of manganese catalases.

Whittaker, James W.

2012-01-01

281

Non-heme manganese catalase--the 'other' catalase.  

PubMed

Non-heme manganese catalases are widely distributed over microbial life and represent an environmentally important alternative to heme-containing catalases in antioxidant defense. Manganese catalases contain a binuclear manganese complex as their catalytic active site rather than a heme, and cycle between Mn(2)(II,II) and Mn(2)(III,III) states during turnover. X-ray crystallography has revealed the key structural elements of the binuclear manganese active site complex that can serve as the starting point for computational studies on the protein. Four manganese catalase enzymes have been isolated and characterized, and the enzyme appears to have a broad phylogenetic distribution including both bacteria and archae. More than 100 manganese catalase genes have been annotated in genomic databases, although the assignment of many of these putative manganese catalases needs to be experimentally verified. Iron limitation, exposure to low levels of peroxide stress, thermostability and cyanide resistance may provide the biological and environmental context for the occurrence of manganese catalases. PMID:22198285

Whittaker, James W

2011-12-16

282

Ligating properties of a potentially tetradentate Schiff base [(CH3)2NCH2CH2N=CHC6H3(OH)(OMe)] with zinc(II), cadmium(II), cobalt(II), cobalt(III) and manganese(III) ions: synthesis and structural studies.  

PubMed

A series of Zn(II), Cd(II), Co(II), Co(III) and Mn(III) complexes with the Schiff base [(CH3)2NCH2CH2N=CHC6H3(OH)(OMe)], LH, derived from 2-dimethylaminoethylamine and o-vanillin, has been synthesised and structures of all the products have been established by X-ray crystallography. In the cases of zinc and cadmium, dimeric complexes [Zn(LH)2(NCS)] [Zn2(L)(mu(1,1)-CH3COO)(NCS)3] (1), [Cd2(L)2(Cl)2] (2) and [Cd2(L)2(NCS)2] (3), and for cobalt and manganese, monomeric complexes [Co(LH)2(NCS)]2 [Co(NCS)4] (4), [Co(LH)2(NCS)]ClO4 (5), [Co(L)(N3)(o-vanillinate)] x 0.5 MeOH (6) and [Mn(LH)2(MeOH)2](ClO4)3 (7), are formed with various terminal ligands. All the complexes have been characterised by elemental analysis and IR spectra. UV-Vis and NMR spectroscopy, magnetic, and electrochemical studies, were also carried out where feasible. The Schiff base functions as a bi-, tri- or tetra-dentate chelating agent and coordinates via the protonated or deprotonated phenolic oxygen, amine and imine nitrogens, and only in case of 1 with the methoxy oxygen atoms, to the metal ion leading to the formation of mono- or bi-metallic complexes. PMID:16568185

Sen, Soma; Talukder, Pritha; Dey, Subrata K; Mitra, Samiran; Rosair, Georgina; Hughes, David L; Yap, Glenn P A; Pilet, Guillaume; Gramlich, V; Matsushita, T

2006-01-06

283

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

284

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.

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

2008-01-01

285

Process for producing manganese dioxide  

SciTech Connect

The invention relates to the manufacture of manganese dioxide by a chemical process. The resulting manganese dioxide product takes the form of particles characterized by filament-like protrusions jutting out from its surface. The manganese dioxide particles having such surface features can be manufactured by reacting manganese sulfate with sodium peroxodisulfate in an aqueous solution. The process can be controlled to yield high density manganese dioxide. The manganese dioxide formed in the process can be deposited directly onto the surface of electrolytic manganese dioxide (EMD). The manganese dioxide product the is particularly suitable for use as a cathode active material in electrochemical cells. 16 figs.

Wang, E.I.; Lin, L.; Bowden, W.L.

1994-01-11

286

State of atoms and interatomic interactions in complex perovskite-like oxides: I. State of manganese atoms in LaSrMnâAlâ-âOâ solid solutions  

Microsoft Academic Search

Study of the temperature and concentration dependences of the magnetic properties of solid solutions of layered oxides containing manganese and aluminum atoms in similar crystallographic positions revealed a change in the ground state of part of the manganese atoms. Such an effect was previously observed for iron, cobalt, and nickel atoms in similar solid solutions. In the case of manganese,

N. P. Bobrysheva; N. V. Chezhina

1994-01-01

287

Minerals Yearbook, 1988. Cadmium  

SciTech Connect

Cadmium metal production in the United States increased significantly in 1988, and four companies operating four plants produced all of the domestic cadmium. Imports for consumption of cadmium metal decreased, but exports increased. Dramatic increases in cadmium prices in 1988 were attributed to the tight supply of cadmium, heavy speculative trading, and the large quantities of cadmium being bought by the nickel-cadmium battery industry, particularly in Japan. The report discusses the following: Domestic data coverage; legislation and government programs; domestic production; consumption and uses; stocks; prices; foreign trade; world capacity; world review--France, Mexico; and Technology.

Llewellyn, T.O.

1988-01-01

288

A manganese-rich environment supports superoxide dismutase activity in a Lyme disease pathogen, Borrelia burgdorferi.  

PubMed

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

2013-02-02

289

The Internalization of Iron and Manganese as Discrete Particles During the Bioreduction of Fe(III) and Mn(IV) by a Dissimilatory Metal-Reducing Bacterium  

NASA Astrophysics Data System (ADS)

Shewanella putrefaciens CN32 is a dissimilatory iron-reducing, facultative anaerobe that substitutes Fe3+ as well as other metal and organic substrates for O2 as the terminal electron acceptor of the electron transport chain to gain energy for growth and metabolism (1). During the dissimilatory reduction (DR) of hydrous ferric oxide (HFO), the bacteria produce Fe2+ at the cell surface which results in the precipitation of FeII mineral phases external to the cell. We have shown previously that, at the same time the extracellular minerals are produced, intracellular granules of mineral Fe precipitate as well. These granules form clusters that are located at the poles of the cells (2). We have recently characterized the intracellular particles using X-ray microspectroscopy, which reveals that the particles contain FeII and FeIII in a 1:1 ratio (3). In order to determine if the internal Fe particles represent a general phenomenon of dissimilatory metal reduction, we have extended our investigations on the formation of internal mineral phases to Mn(IV) as well as V(V) (4, 5). Both metals are relatively non-toxic to bacteria, exist in several oxidation states in earth surface environments, and are respired by CN32. Culture experiments were combined with electron microscopy (EM) and scanning transmission X-ray microspectroscopy (STXM) studies of CN32 during respiration of Mn(IV) and V(V). The use of EM and STXM techniques in concert allowed us to detail cell wall ultrastructure and resolve metal chemical states at the nanometer scale. The final extracellular products of Mn(IV) and V(V) respiration were Mn(II) and V(III)/V(IV). Intracellular particles were only observed during the dissimilatory reduction of Mn(IV); however, the particles were not as abundant as those appearing during the bioreduction of HFO. This indicates that the uptake mechanism has specificity for divalent cations, although it is likely that differences in the rate of reduced metal accumulation at the cell surface impact the development of the biominerals. It is remarkable that very little metal accumulated at the surface of individual bacteria during DR of mineral- bound Fe(III), Mn(IV), or V(V). Using X-ray microspectroscopy techniques, we observed that the concentrations of metal associated with many of the bacterial cells were below detection limits in spite of the high levels of extracellular soluble metal produced during DR. Results support that the uptake and compartmentalization of metals by bacteria in anaerobic environments is tightly controlled, and is distinct from aerobic metal association and uptake. References 1. Nealson, K.H. & Saffarini, D.,1994, Ann. Rev. Microbiol. 48: 311-343. 2. Glasauer, S., Langley, S. & Beveridge, T.J., 2002, Science 295: 117-119. 3. Glasauer, S. Langley, M. Boyanov, B. Lai, K. Kemner, T. J. Beveridge, Applied and Environmental Microbiology, in review. 4. Glasauer, S., Langley, S., and Beveridge, T. J., 2004, Environ. Microbiol. 6: 1042-1048. 5. Glasauer, S., Fakra, S., Li, S., Tyliszczak, T., Shuh, D. and T. J. Beveridge, in preparation.

Glasauer, S. M.; Langley, S.; Beveridge, T. J.; Fakra, S.; Tyliszczak, T.; Shuh, D.; Boyanov, M.; Kemner, K.

2006-12-01

290

Lipid peroxidation in the gill and hepatopancreas of Oziotelphusa senex senex fabricius during cadmium and copper exposure  

SciTech Connect

Environmental contamination by metals has increased in recent years due to the excessive use of metals in agriculture and industry. Due to their bioconcentration, immutable and non-degradable properties, these metals constitute a major source of pollutants. Among these metals cadmium, lead and mercury are non-essential, where as copper, iron, manganese, and zinc are essential elements. They are required in trace amounts by all forms of life but are toxic when present in excess. Considerable information is available on the toxic effects of cadmium on biological mechanisms at all integration levels, such as molecular, biochemical, physiological and behavioural, in animals. It is also well known that heavy metal contamination alters cellular physiology, particularly by affecting aspects such as transport across plasma membranes, mitochondrial functions, lysosomal stability etc. Even though it has been demonstrated that the in vitro addition of heavy metals stimulates membrane lipid peroxidation, the in vivo effects exerted by different cations on this process are still not clear. The present work reports the effect of exposure to sublethal concentrations of heavy metals such as Cu and Cd on lipid peroxidation in the tissues of the edible freshwater crab, Oziotelphusa senex senex. 16 refs., 3 tabs.

Reddy, P.S. (Pondicherry Univ. (India)); Bhagyalakshmi, A. (Sri Padmavathi Women's Polytechnic, Tirupati (India))

1994-11-01

291

Cellular Iron Distribution in Bacillus anthracis  

PubMed Central

Although successful iron acquisition by pathogens within a host is a prerequisite for the establishment of infection, surprisingly little is known about the intracellular distribution of iron within bacterial pathogens. We have used a combination of anaerobic native liquid chromatography, inductively coupled plasma mass spectrometry, principal-component analysis, and peptide mass fingerprinting to investigate the cytosolic iron distribution in the pathogen Bacillus anthracis. Our studies identified three of the major iron pools as being associated with the electron transfer protein ferredoxin, the miniferritin Dps2, and the superoxide dismutase (SOD) enzymes SodA1 and SodA2. Although both SOD isozymes were predicted to utilize manganese cofactors, quantification of the metal ions associated with SodA1 and SodA2 in cell extracts established that SodA1 is associated with both manganese and iron, whereas SodA2 is bound exclusively to iron in vivo. These data were confirmed by in vitro assays using recombinant protein preparations, showing that SodA2 is active with an iron cofactor, while SodA1 is cambialistic, i.e., active with manganese or iron. Furthermore, we observe that B. anthracis cells exposed to superoxide stress increase their total iron content more than 2-fold over 60 min, while the manganese and zinc contents are unaffected. Notably, the acquired iron is not localized to the three identified cytosolic iron pools.

Tu, Wang Yung; Pohl, Susanne; Gray, Joe; Robinson, Nigel J.; Harwood, Colin R.

2012-01-01

292

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.

2012-01-01

293

Process for producing manganese dioxide  

Microsoft Academic Search

The invention relates to the manufacture of manganese dioxide by a chemical process. The resulting manganese dioxide product takes the form of particles characterized by filament-like protrusions jutting out from its surface. The manganese dioxide particles having such surface features can be manufactured by reacting manganese sulfate with sodium peroxodisulfate in an aqueous solution. The process can be controlled to

E. I. Wang; L. Lin; W. L. Bowden

1994-01-01

294

Formation of iron plaque on mangrove Kandalar. Obovata (S.L.) root surfaces and its role in cadmium uptake and translocation.  

PubMed

In this study, a pot experiment was conducted to investigate the formation of iron plaque under Cd stress and its role in Cd uptake and translocation by mangrove Kandalar. Obovata (S.L.). Results showed: In conclusion, formation of Fe plaque can precipitate Cd on root surfaces and impede its uptake and translocation in Kandalar. Obovata (S.L.). However, in comparison with root tissues, Fe plaque is of little significance. It is the mangrove root tissue that acts as the main buffer to Cd uptake and translocation. PMID:23932478

Du, Jingna; Yan, Chongling; Li, Zhaodeng

2013-08-06

295

Hot coal gas desulfurization with manganese-based sorbents  

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 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.

Hepworth, M.T.; Ben-Slimane, R.

1994-12-01

296

Process for producing cadmium sulfide on a cadmium telluride surface  

DOEpatents

A process for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness.

Levi, Dean H. (Lakewood, CO); Nelson, Art J. (Longmont, CO); Ahrenkiel, Richard K. (Lakewood, CO)

1996-01-01

297

New Vanadium and Manganese Oxides for Lithium Batteries  

Microsoft Academic Search

Transition metal oxides, that can intercalate lithium ions in a reversible manner and with an energy in the range of 3 to 4 volts, are a critical link in the advancement of high energy density lithium batteries. Vanadium, manganese and iron oxides form the appropriate polyhedral structures that might intercalate small ions. Such structures have been formed at low temperatures

M. Stanley Whittingham; Peter Y. Zavalij; Thomas Chirayil; Rongji Chen

1997-01-01

298

The relative abundances of the elements scandium to manganese in relativistic cosmic rays and the possible radioactive decay of manganese 54  

NASA Astrophysics Data System (ADS)

We report measurements of the abundances relative to iron of the elements scandium through manganese in galactic cosmic rays in the energy interval 0.7 to 18 GeV/n using data collected by our cosmic ray telescope on the HEAO-3 satellite. The variation versus energy of the abundance ratio of manganese over iron is markedly flatter than that of other iron secondaries. This difference is interpreted as being due to 54Mn survival at E > 15 GeV/n and to its progressive beta decay at lower energies.

Koch, L.; Engelmann, J. J.; Goret, P.; Juliusson, E.; Petrou, N.; Rio, Y.; Soutoul, A.; Byrnak, B.; Lund, N.; Peters, B.

1981-10-01

299

Multimedia Levels Cadmium.  

National Technical Information Service (NTIS)

The report is a review of environmental levels of cadmium based on published reports and other information sources. Cadmium levels are reported for the atmosphere, surface and ground waters, drinking water, sediments, soil, sludge, terrestrial and aquatic...

1977-01-01

300

Treatment of cadmium and nickel electroplating rinse water by electrocoagulation  

Microsoft Academic Search

Treatments of cadmium?cyanide and nickel?cyanide electroplating rinse water were investigated in an electrochemical reactor equipped with iron plate electrodes in a batch mode by electrocoagulation (EC). Effects of the process variables such as pH, current density, and operating time were explored with respect to removal efficiencies of cadmium, nickel and cyanide in electroplating rinse water and operating costs as well.

M. Kobya; E. Demirbas; N. U. Parlak; S. Yigit

2010-01-01

301

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

302

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

303

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2010 CFR

... § 184.1449 Manganese citrate. (a) Manganese citrate (Mn3 (C6 H5 O7 )2 ...white powder. It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The...

2009-04-01

304

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2013 CFR

... § 184.1449 Manganese citrate. (a) Manganese citrate (Mn3 (C6 H5 O7 )2, ...white powder. It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The...

2013-04-01

305

21 CFR 184.1449 - Manganese citrate.  

Code of Federal Regulations, 2010 CFR

... § 184.1449 Manganese citrate. (a) Manganese citrate (Mn3 (C6 H5 O7 )2 ...white powder. It is obtained by precipitating manganese carbonate from manganese sulfate and sodium carbonate solutions. The...

2010-01-01

306

Astrocytes and manganese neurotoxicity.  

PubMed

Increasing evidence suggests that astrocytes are the site of early dysfunction and damage in manganese neurotoxicity. Astrocytes accumulate manganese by a high affinity, high capacity, specific transport system. Chronic exposure to manganese leads to increased pallidal signal hyperintensities on T1-weighted magnetic resonance images and selective neuronal loss in basal ganglia structures together with characteristic astrocytic changes known as Alzheimer type II astrocytosis. Manganese is sequestered in mitochondria where it inhibits oxidative phosphorylation. Exposure of astrocytes to manganese results in important changes including (i) decreased uptake of glutamate; (ii) increased densities of binding sites for the "peripheral-type" benzodiazepine receptor (PTBR), a class of receptor localized to mitochondria of astrocytes and involved in oxidative metabolism, mitochondrial proliferation, and neurosteroid synthesis; (iii) increased gene expression and activity of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH), known to be associated with apoptosis; (iv) increased uptake of L-arginine, a precursor of nitric oxide, together with increased expression of the inducible form of nitric oxide synthase (iNOS). Potential consequences of these alterations in astrocytic gene expression include failure of energy metabolism, production of reactive oxygen species (ROS), increased extracellular glutamate concentration and excitotoxicity which could play a key role in manganese-induced neuronal cell death as a direct result of impaired astrocytic-neuronal interactions. PMID:12106778

Hazell, Alan S

2002-10-01

307

Biologically relevant heterodinuclear iron-manganese complexes.  

PubMed

The heterodinuclear complexes [Fe(III)Mn(II)(L-Bn)(?-OAc)(2)](ClO(4))(2) (1) and [Fe(II)Mn(II)(L-Bn)(?-OAc)(2)](ClO(4)) (2) with the unsymmetrical dinucleating ligand HL-Bn {[2-bis[(2-pyridylmethyl)aminomethyl

Carboni, Michaël; Clémancey, Martin; Molton, Florian; Pécaut, Jacques; Lebrun, Colette; Dubois, Lionel; Blondin, Geneviève; Latour, J-M

2012-09-18

308

Preparation of lithium manganese oxides containing iron  

Microsoft Academic Search

Preparation of LiFeO2–Li2MnO3 solid solution has been attempted using hydrothermal and solid state reactions. Three 10% Fe-doped Li2MnO3 samples (Fe\\/(Fe+Mn)=0.1) with different average particle sizes could be obtained by both methods. The initial charge capacities for these cathodes were sensitive to the preparation method; the capacity up to 4.3V is 45mAh\\/g for the hydrothermally-obtained sample, 24mAh\\/g for the post-annealed sample

Mitsuharu Tabuchi; Hikari Shigemura; Kazuaki Ado; Hironori Kobayashi; Hikari Sakaebe; Hiroyuki Kageyama; Ryoji Kanno

2001-01-01

309

Iron titanium manganese alloy hydrogen storage  

SciTech Connect

A three component alloy is described which is capable of reversible sorption of hydrogen and having the chemical formula, TiFe{sub 1{minus}x}Mn{sub x}, where x is in the range of about 0.02 to 0.5. The method of storing hydrogen using said alloy is also disclosed. 2 figs.

Reilly, J.J.; Wiswall, R.H. Jr.

1979-08-28

310

Manganese and iron in Indian Ocean waters  

Microsoft Academic Search

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).

Paul M. Saager; Hein J. W. De Baar; Peter H. Burkill

1989-01-01

311

40 CFR 721.10667 - Slimes and sludges, aluminum and iron casting, wastewater treatment, solid waste.  

Code of Federal Regulations, 2013 CFR

...the treatment of wastewaters during aluminum and iron casting, machining and finishing operations. It may contain aluminum, barium, chromium, copper, iron, lead, manganese, nickel, and zinc.) is subject to reporting under this section for the...

2013-07-01

312

CADMIUM SOLUBILITY IN PADDY SOILS: EFFECTS OF SOIL OXIDATION, METAL SULFIDES AND COMPETITIVE IONS.  

EPA Science Inventory

Cadmium (Cd) is a non-essential element for human nutrition and is an agricultural soil contaminant. Cadmium solubility in paddy soils affects Cd accumulation in the grain of rice. This is a human health risk, exacerbated by the fact that rice grains are deficient in iron (Fe) an...

313

Disulfide disproportionation and CdS formation upon cadmium sorption on FeS 2  

Microsoft Academic Search

Adsorption reactions are important for understanding the distribution of ions between aqueous and solid phases; they govern solution concentrations, bioavailability, and mobility of ions in the environment. Iron disulfide is a sorbent of cadmium in reduced systems but sorption on sulfides is not well understood. The purpose of this research is to determine the surface structures and products of cadmium

Benjamin C Bostick; Scott Fendorf; Mark Fendorf

2000-01-01

314

Improved corrosion resistance of tool steel H13 by means of cadmium ion implantation and deposition  

Microsoft Academic Search

Cadmium presents excellent resistance to corrosion, being useful to form a protective coating mainly on iron but also on a variety of steels. A very common way to cover such substrates with Cd is by means of electrodeposition. However, more recently, the use of cadmium electroplating has been restricted due to environmental and health concerns. In addition, specific procedures must

R. M. Oliveira; J. A. N. Gonçalves; M. Ueda; S. Oswald; S. C. Baldissera

2010-01-01

315

Porewater cadmium geochemistry and the porewater cadmium:. delta. sup 13 C relationship  

SciTech Connect

Results from two continental margin cores collected off Pt. Sur, California, make possible a direct determination of the relationship between dissolved cadmium and the carbon isotopic composition of dissolved inorganic carbon in the interstitial water of suboxic marine sediments. The {delta}{sup 13}C values of dissolved inorganic carbon decrease nearly 1{per thousand} in the top 0.5 cm of the sediments and display a more gradual decrease through the top 20 cm of the sediments. Dissolved cadmium concentrations increase by 0.6 to 1.5 nmol/kg in the top 0.5 cm of the sediments, and then rapidly decrease to values of approximately 0.12 nmol/kg between 5 and 10 cm into the sediments, apparently as a result of scavenging onto iron oxide surfaces. This pattern contrasts with porewater cadmium profiles previously reported for pelagic sediments, which no evidence of cadmium scavenging by the sediments. However, porewater cadmium concentrations are poorly correlated with porewater {delta}{sup 13}C values in both oxic and suboxic sediments. These results suggest that the cadmium/calcium ratios and {delta}{sup 13}C values of infaunal benthic foraminifera need not be tightly linked, and that the relationship between these two aspects of foraminiferal shell chemistry may vary in response to changes in sediment geochemistry.

McCorkle, D.C. (Woods Hole Oceanographic Institution, MA (USA)); Klinkhammer, G.P. (Massachusetts Institute of Technology, Cambridge (USA))

1991-01-01

316

Kinetics of microbial manganese oxidation and trace metal binding in sediments: Results from an in situ dialysis technique  

Microsoft Academic Search

Sediments associated with freshwater fcrromanganese concretions in Lake Charlotte, Nova Sco- tia, contained microscopic precipitates of manganese and iron. These precipitates were dispersed throughout the sediment and were as rich in nickel, cobalt, and copper as deep sea concretions. In addition, the development of the precipitates appeared to be associated with the microbial oxidation of manganese. Results from the deployment

Paul E. Kepkay

1985-01-01

317

Manganese micro-nodules on ancient brick walls.  

PubMed

Romans, Jews, Arabs and Christians built the ancient city of Toledo (Spain) with bricks as the main construction material. Manganese micro-nodules (circa 2 microm in diameter) have grown under the external bio-film surface of the bricks. Recent anthropogenic activities such as industrial emissions, foundries, or traffic and housing pollution have further altered these old bricks. The energy-dispersive X-ray microanalyses (XPS) of micro-nodules show Al, Si, Ca, K, Fe and Mn, with some carbon species. Manganese atoms are present only as Mn(4+) and iron as Fe(3+) (FeOOH-Fe(2)O(3) mixtures). The large concentration of alga biomass of the River Tagus and the Torcón and Guajaraz reservoirs suggest manganese micro-nodules are formed either from water solutions rich in anthropogenic MnO(4)K in a reduction environment (from Mn(7+) to Mn(4+)) or by oxidation mechanisms from dissolved Mn(2+) (from Mn(2+) to Mn(4+)) linked to algae biofilm onto the ancient brick surfaces. Ancient wall surfaces were also studied by scanning electron microscopy (SEM-EDS) and X-ray diffraction (XRD). Chemical and biological analyses of the waters around Toledo are also analysed for possible sources of manganese. Manganese micro-nodules on ancient brick walls are good indicators of manganese pollution. PMID:12526915

López-Arce, P; García-Guinea, J; Fierro, J L G

2003-01-20

318

Study of Manganese Phosphating Reactions.  

National Technical Information Service (NTIS)

Work was conducted to determine the composition of and the reactions associated with the formation of manganese-phosphate coatings. An improved phosphate coating was studied as produced from a stock manganese phosphating bath to which an addition of manga...

J. Menke

1971-01-01

319

Investigation of cadmium resistance in an Alcaligenes sp  

SciTech Connect

The mechanisms of metal resistance of a cadmium-resistant Alcaligenes sp. were studied. Growth in a defined medium was unaffected by cadmium at concentrations up to 0.1 mM, while at concentrations up to 2.5 mM, growth occurred after an extended lag phase. The increase in length of the lag phase was abolished by repeated subculturing at these higher concentrations. However, subculture in the absence of cadmium reversed the adaptation process. Plasmid DNA was not detected in adapted cells, suggesting that adaptation is not plasmid mediated. Increased sulfide production in response to cadmium was observed, although the levels were too low to account fully for cadmium resistance. Adaptation of cells to cadmium resulted in the appearance of a major new membrane preparation. This protein was induced at cadmium concentrations of 0.1 mM and above, but below this level the protein was absent. The onset of growth at concentrations above 0.1 mM was coincident with the appearance of this protein, which was also induced by zinc (0.4 mM) but not by manganese or nickel. The protein was only solubilized by a sodium dodecyl sulfate-2-mercaptoethanol mixture. Similar solubility properties were shown by a second major membrane protein (molecular weight, 33,000). These two proteins proved to be similar by peptide-mapping experiments and amino acid analysis. The appearance of the 34,500-molecular-weight protein and its possible role in cadmium resistance are discussed.

McEntee, J.D.; Woodrow, J.R.; Quirk, A.V.

1986-03-01

320

Manganese biomining: A review.  

PubMed

Biomining comprises of processing and extraction of metal from their ores and concentrates using microbial techniques. Currently this is used by the mining industry to extract copper, uranium and gold from low grade ores but not for low grade manganese ore in industrial scale. The study of microbial genomes, metabolites and regulatory pathways provide novel insights to the metabolism of bioleaching microorganisms and their synergistic action during bioleaching operations. This will promote understanding of the universal regulatory responses that the biomining microbial community uses to adapt to their changing environment leading to high metal recovery. Possibility exists of findings ways to imitate the entire process during industrial manganese biomining endeavor. This paper reviews the current status of manganese biomining research operations around the world, identifies factors that drive the selection of biomining as a processing technology, describes challenges in exploiting these innovations, and concludes with a discussion of Mn biomining's future. PMID:21632238

Das, A P; Sukla, L B; Pradhan, N; Nayak, S

2011-05-14

321

Corrosion resistant gray cast iron graphite flake alloys  

Microsoft Academic Search

Corrosion resistant gray cast iron alloys useful in downhole oil well environments and the like. The alloys are substantially lower in cost and substantially higher in tensile strength than high nickel-copper cast irons commonly used downhole in submergible pumps. The alloys contain substantial amounts of aluminum in combination with nickel, chromium, manganese, molybdenum, carbon, silicon, and iron. Copper, tin, vanadium,

1985-01-01

322

Bioaccumulation of manganese and its toxicity in feral pigeons (Columba livia) exposed to manganese oxide dust (Mn3O4).  

PubMed

Manganese tetroxide (Mn3O4) 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 Mn3O4 have been reported. The present study was therefore conducted to examine the bioaccumulation and toxicity of manganese in various organs of feral pigeons (Columba livia) when exposed to low levels of Mn3O4 via inhalation and hence to find any possible relationship between these two parameters. A total of 22 pigeons was exposed to 239 micrograms/m3 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, alanine aminotransferase, total iron, blood urea nitrogen and triglycerides, were also measured. Manganese concentrations in brain, lung, and bone were significantly higher in Mn3O4-exposed pigeons (0.59, 0.58, and 3.02 micrograms wet tissue, respectively) than in the control group (0.46, 0.19, 1.74 micrograms/g wet tissue, respectively). However, except for total proteins such exposure did not produce any changes in various biochemical parameters which were within the normal values. Thus these results have shown that, despite significant bioaccumulation of manganese in some tissues, no significant toxic effects could be seen. PMID:9841807

Sierra, P; Chakrabarti, S; Tounkara, R; Loranger, S; Kennedy, G; Zayed, J

1998-11-01

323

Sputtered Zn{sub 1-x}Ga{sub 2}O{sub 4}:Mn thin-film electroluminescent devices prepared using cadmium-assisted processing  

SciTech Connect

Incorporating cadmium in the sputtering targets used to grow green-emitting zinc gallate doped with manganese is found to provide improvements in crystallinity, photoluminesience (PL), and electroluminescence (EL) performance, while reducing the annealing temperature requirements. It is shown that as-grown thin films do contain cadmium. The cadmium is then lost during thin-film annealing. The effect of cadmium is interpreted as an enhancement in vacancy concentration during the thin-film annealing process, which improves crystallinity, EL, and PL. X-ray diffraction and microscopy results are carefully studied and discussed.

Flynn, M.; Kitai, A.H. [Department of Engineering Physics, McMaster University, Hamilton (Canada)

2005-05-01

324

Differential Regulation of Iron and Manganese-Specific MtsABC and Heme-Specific HtsABC Transporters by the Metalloregulator MtsR of Group A Streptococcus  

Microsoft Academic Search

The genome of the human pathogen group A Streptococcus (GAS) encodes the transporters MtsABC, FtsABCD, and HtsABC to take up ferric and manganese ions, ferric ferrichrome, and heme, respectively. The GAS genome also encodes two metalloregulators PerR and MtsR. To understand the regulation of the expression of these transporters, the mtsR and perR deletion mutants of a GAS serotype M1

Tracey S. Hanks; Mengyao Liu; Michael J. McClure; Maki Fukumura; Angela Duffy; Benfang Lei

2006-01-01

325

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

326

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

327

Cadmium Toxicity and Treatment  

PubMed Central

Cadmium is a heavy metal of considerable toxicity with destructive impact on most organ systems. It is widely distributed in humans, the chief sources of contamination being cigarette smoke, welding, and contaminated food and beverages. Toxic impacts are discussed and appear to be proportional to body burden of cadmium. Detoxification of cadmium with EDTA and other chelators is possible and has been shown to be therapeutically beneficial in humans and animals when done using established protocols.

Bernhoft, Robin A.

2013-01-01

328

Studies on Indian Ocean manganese nodules. 3: Adsorption of aqueous selenite on ferromanganese nodules  

SciTech Connect

Adsorption of aqueous selenite (SeO{sub 3}{sup 2{minus}}) on Indian Ocean manganese nodules was studied as a function of time, temperature, pH, and concentrations of adsorbate and adsorbent in acetic acid-sodium acetate buffer medium. Analysis of adsorption data supports a heterogeneous nature for the surface of manganese nodules. The adsorption capacity of various manganese nodules for selenite was correlated with their chemical composition and surface properties. Adsorption of selenite/selenate on hydrous oxides of iron, manganese, and aluminum appears to be an efficient and inexpensive method for removing trace contaminants. Manganese nodules, a naturally occurring complex material, with its high contents of oxides/oxyhydroxides of Mn, Fe, Si, and Al, high porosity, and high surface area may be a suitable substitute for conventional adsorbents.

Parida, K.M.; Gorai, B.; Das, N.N. [Regional Research Lab., Bhubaneswar (India)

1997-03-15

329

Cadmium Transport in a Model of Neonatal Intestinal Cells Correlates to MRP1 and Not DMT1 or FPN1  

PubMed Central

Newborns have a higher gastrointestinal uptake of cadmium than adults. In adults, the iron transporters DMT1 and FPN1 are involved in the intestinal absorption of cadmium, while in neonates, the mechanisms for cadmium absorption are unknown. We have investigated possible cadmium transporters in the neonatal intestine by applying a model of immature human intestinal epithelial Caco-2 cells. To mimic the continuous cadmium exposure via diet in neonates, cells were allowed to differentiate for 7 days in medium containing 1??M CdCl2. A dramatic upregulation of the MT1 gene expression followed cadmium pretreatment, indicating a high sensitivity of the immature cells to cadmium. Cadmium pretreatment increased the basolateral efflux of 109Cd, without causing any effects on the passive diffusion of mannitol or the transepithelial electrical resistance. The augmented transport of cadmium was correlated to an upregulation of MRP1 gene expression and increased activity of the efflux protein MRP1. No effects were observed on gene expression of the efflux proteins MRP2 and P-gp or the iron transporters DMT1, DMT1-IRE and FPN1. In conclusion, our data indicate that continuous cadmium exposure increases the absorption of the metal in immature intestinal cells and that MRP1 is involved in the intestinal cadmium absorption in newborns.

Ohrvik, Helena; Tyden, Eva; Artursson, Per; Oskarsson, Agneta

2013-01-01

330

Manganese and biotic debris associations in some deep-sea sediments.  

PubMed

Incipient manganese concretions occur in microcavities of planktonic skeletal debris (especially diatom frustules) in some Pacific Basin deep-sea sediments. These concretions contain over 50 percent manganese and very little iron (< 1 percent). There is a continuum of growth stages in the concretions having a diameter between 0 and approximately 2 millimeters, and a genetic relationship is suggested between the very small and the centimeter sized concretions. PMID:17790381

Greenslate, J

1974-11-01

331

Intercalation of manganese chloride into mesophase pitch-based graphite fibers via gaseous complexes  

Microsoft Academic Search

The intercalation of certain metal chlorides into carbon fibers presents some problems, which depend on both their structure (three-dimensional ordering in particular) and the intercalation techniques. In this work, the intercalation of manganese chloride into pitch-based carbon fibers was investigated. The use of manganese chloride in the presence of iron(III) chloride or copper(II) chloride enhances the vapor pressure of the

D Sarmeo; S Blazewicz; M Mermoux; Ph Touzain

2001-01-01

332

Manganese supplementation protects against diet-induced diabetes in wild type mice by enhancing insulin secretion.  

PubMed

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; McClain, Donald A

2013-01-31

333

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

334

CONVERSATION OF DISSOLVED MANGANESE TO PARTICULATE MANGANESE DURING DIATOM BLOOM: EFFECTS ON THE MANGANESE CYCLE IN THE MERL MICROCOSMS  

EPA Science Inventory

Conversion of dissolved manganese to particulate manganese occurred during a minor diatom bloom during August and September 1978 in the MERL microcosms. Correlations between chlorophyll a and particulate manganese suggest that 29 moles Mn were transferred to the particulate phase...

335

Process for producing cadmium sulfide on a cadmium telluride surface  

DOEpatents

A process is described for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness. 12 figs.

Levi, D.H.; Nelson, A.J.; Ahrenkiel, R.K.

1996-07-30

336

Transcriptional and translational regulation of COX-2 expression by cadmium in C6 glioma cells.  

PubMed

High exposure to cadmium is a risk factor for many neuronal diseases. Overexpression of cyclooxygenase (COX)-2 is linked to many neuroinflammatory and neoplastic diseases. We, herein, investigated the effect of cadmium on the expression of COX-2 in C6 rat glioma cells. Treatment with cadmium sulfate (cadmium) increased the expression of COX-2 mRNA. Remarkably, cadmium treatment further increased expression of not only the N-glycosylated COX-2 protein of 72 kDa but also the unglycosylated COX-2 of 66 kDa, as assessed by the unglycosylated COX-2 induced by tunicamycin or glucosamine, known inhibitors of COX-2 N-glycosylation. Of note, when translation was blocked in the presence of cycloheximide (CHX), levels of both N-glycosylated and unglycosylated COX-2 proteins induced by cadmium rapidly declined but the decline was prevented by MG132, a 26S proteasomal inhibitor. However, in the absence of CHX, cadmium induced and maintained expression of the unglycosylated COX-2 proteins. Pharmacological inhibition studies importantly demonstrated that the cadmium-mediated COX-2 transcriptional upregulation in C6 cells was not shown by exogenous glutathione (GSH) supplementation or treatment with inhibitors of extracellular signal-regulated protein kinase-1/2 (ERK-1/2), p38 MAPK and c-Jun N-terminal protein kinase-1/2 (JNK-1/2), respectively. Expression of COX-2 was not noted in C6 cells exposed to other heavy metals (cobalt or manganese). These results demonstrate that cadmium specifically induces expression of COX-2 through both transcriptional and co-translational (N-glycosylation) regulation in C6 cells in which the cadmium-induced COX-2 transcriptional upregulation is closely related to oxidative stress-dependent activation of the family of MAPKs and the cadmium-induced expression of both N-glycosylated and unglycosylated COX-2 proteins is proteasome- and translation-dependent. PMID:22767315

Park, Yu-Kyoung; Hong, Hua; Jang, Byeong-Churl

2012-07-03

337

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.

2009-01-01

338

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

339

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

340

Transport of cadmium ions from zinc plant leach solutions through emulsion liquid membrane-containing Aliquat 336 as carrier  

Microsoft Academic Search

The zinc plant purification cake (CINKUR Co., Turkiye) was leached with sulphuric acid. The transport of cadmium from this leach solution-containing zinc, iron, copper, aluminum, cadmium, nickel and cobalt through emulsion liquid membrane (ELM) using amine extractant dissolved in kerosene as a mobile carrier was studied. The ELM consists of Aliquat 336 as a carrier, Span 80 as a surfactant,

Recep Ali Kumbasar

2008-01-01

341

Effects of dietary manganese and iron on manganese and iron metabolism during infancy  

SciTech Connect

To derive a better understanding of the metabolism of Mn during infancy, infant formulas with different levels of Mn and Fe were labeled with {sup 54}Mn and {sup 59}Fe and administered orally to suckling rats: control low-Fe formula; control with 100-times Mn; and control with 100-times Fe. Another group received 200 {mu}g MnCl{sub 2} daily during infancy. 12 hr post-dosing, the pattern of {sup 54}Mn distribution in the tissues paralleled that of {sup 59}Fe. An excess of either mineral decreased overall retention but led to higher recoveries of both elements in the proximal intestine and liver. Conversely, these recoveries in pups given Mn from birth were lower than in controls. Analysis of the cytosolic fractions from intestine and liver using FPLC gel filtration demonstrated the impact of the mineral loads on protein profiles. In all cases except the high-Mn dose, dietary manipulations resulted in greater relative levels of a high molecular weight protein with MW similar to ferritin. The high-Mn formula seemed to induce in the hepatocyte a lower MW protein with which most of the {sup 54}Mn and {sup 59}Fe was associated. These results suggest a possible role of Mn as a regulator in the synthesis of cytosolic proteins of the enterocyte and hepatocyte in infants.

Kiehl, H.; Loennerdal, B. (Univ. of California, Davis (United States))

1991-03-15

342

Iron and Iron Deficiency  

MedlinePLUS

... them to get enough iron from their normal diet. Women who are pregnant have higher iron needs. To ... iron sources in the diet (e.g., vegetarian diets) Low absorption Taking antacids beyond ... Young children and pregnant women are at higher risk of iron deficiency because ...

343

Oxidative basis of manganese neurotoxicity.  

PubMed

Exposure to excessive levels of manganese, an essential trace element, can evoke severe psychiatric and extrapyramidal motor dysfunction closely resembling Parkinson's disease. The clinical manifestations of manganese toxicity arise from focal injury to the basal ganglia. This region, characterized by intense consumption of oxygen and significant dopamine content, can incur mitochondrial dysfunction, depletion of levels of peroxidase and catalase, and catecholamine biochemical imbalances following manganese exposure. The site specificity of the pathology and the nature of the cellular damage caused by manganese have been attributed to its capacity to produce cytotoxic levels of free radicals. However, support for such a pro-oxidant role for manganese has been largely limited to inferences drawn from histopathological observations. More recently, research efforts into the molecular details of manganese toxicity have provided evidence of an etiological relationship between oxidative stress and manganese-related neurodegeneration. This review focuses on studies that evaluate the redox chemistry of manganese during the neurodegenerative process and its molecular consequences. PMID:15105260

HaMai, Diem; Bondy, Stephen C

2004-03-01

344

Manganese: brain transport and emerging research needs.  

PubMed Central

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.

Aschner, M

2000-01-01

345

Method for dehydrating manganese dioxide  

SciTech Connect

A method is described for preparing a water-free lithium-manganese dioxide battery comprising: assembling the battery comprising lithium anode, a cathode comprising carbon and manganese dioxide, and a cell container; adding to the cell container a fluid containing a dehydrating agent which reacts with water bound to the manganese dioxide to form a reaction product that is extractable from the manganese dioxide; removing the fluid from the cell container; hermetically sealing and connecting the container to a vacuum source; establishing a vacuum within the compartment to pull off any remaining amount of the fluid and any volatile reaction product from the manganese dioxide; releasing the vacuum; and adding anhydrous electrolyte and hermetically sealing the cell.

Marincic, N.; Fuksa, R.

1987-05-05

346

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

347

Neutral catecholate derivatives of manganese and iron: Synthesis and characterization of the metal-oxygen cubane-like species M sub 4 (DBCat) sub 4 (py) sub 6 (M = Mn, Fe), the trinuclear complex Mn sub 3 (DBCat) sub 4 (py) sub 4 , and the dimers M sub 2 (DBCat) sub 2 (py) sub n (M = Mn, n = 6; M = Fe, n = 4, 6)  

SciTech Connect

The synthesis and characterization of several new catecholate derivatives of manganese and iron are described. The reaction of 3,5-di-tert-butylcatechol (DBCatH{sub 2}) with the amides M(N(SiMe{sub 3}){sub 2}){sub 2} (M = Mn, Fe) in the presence of pyridine (py) affords the title compounds in high yield. The dimers Mn{sub 2}(DBCat){sub 2}(py){sub 6} (1) and Fe{sub 2}(DBCat){sub 2}(py){sub n} (n = 4 (4a), 6 (4b)) are obtained by treatment of catechol with the appropriate amide in pyridine. In hexane or toluene, this reaction gives the tetrametallic species M{sub 4}(DBCat){sub 4}(py){sub 6} (M = Mn (2), Fe (5)) upon the addition of 2 equiv of pyridine or, in the case of 2, by recrystallization of the dimer from toluene. Mn{sub 3}(DBCat){sub 4}(py){sub 4} (3) is obtained by slow air oxidation of 2 or by addition of 1/3 equiv of 3,5-di-tert-butyl-o-benzoquinone to the reaction of Mn(N(SiMe{sub 3}){sub 2}){sub 2} with DBCatH{sub 2} in hexane with subsequent addition of pyridine. Compounds 1-5 were characterized by infrared, UV-visible, {sup 1}H NMR, and EPR spectroscopy and X-ray crystallography.

Shoner, S.C.; Power, P.P. (Univ. of California, Davis (United States))

1992-03-18

348

Effect of PVC and iron materials on Mn(II) deposition in drinking water distribution systems.  

PubMed

Polyvinyl chloride (PVC) and iron pipe materials differentially impacted manganese deposition within a drinking water distribution system that experiences black water problems because it receives soluble manganese from a surface water reservoir that undergoes biogeochemical cycling of manganese. The water quality study was conducted in a section of the distribution system of Tegucigalpa, Honduras and evaluated the influence of iron and PVC pipe materials on the concentrations of soluble and particulate iron and manganese, and determined the composition of scales formed on PVC and iron pipes. As expected, total Fe concentrations were highest in water from iron pipes. Water samples obtained from PVC pipes showed higher total Mn concentrations and more black color than that obtained from iron pipes. Scanning electron microscopy demonstrated that manganese was incorporated into the iron tubercles and thus not readily dislodged from the pipes by water flow. The PVC pipes contained a thin surface scale consisting of white and brown layers of different chemical composition; the brown layer was in contact with the water and contained 6% manganese by weight. Mn composed a greater percentage by weight of the PVC scale than the iron pipe scale; the PVC scale was easily dislodged by flowing water. This research demonstrates that interactions between water and the infrastructure used for its supply affect the quality of the final drinking water. PMID:16765409

Cerrato, José M; Reyes, Lourdes P; Alvarado, Carmen N; Dietrich, Andrea M

2006-06-09

349

Kinetics of microbial manganese oxidation and trace metal binding in sediments: results from an in situ dialysis technique  

SciTech Connect

Sediments associated with freshwater ferromanganese concretions in Lake Charlotte, Nova Scotia, contained microscopic precipitates of manganese and iron. These precipitates were dispersed throughout the sediment and were as rich in nickel, cobalt, and copper as deep sea concretions. In addition, the development of the precipitates appeared to be associated with the microbial oxidation of manganese. Results from the deployment of poisoned and unpoisoned dialysis probes or peepers demonstrated that microbial manganese oxidation and nickel binding were closely associated, causing a fivefold enhancement of abiotic processes such as adsorption. The microbial enhancement of copper binding was far less pronounced, due to organic-metal interactions in competition with manganese oxidation. Organic-metal interactions and oxidation may both have been in effect during iron binding, but the relative importance of the two processes could not be determined from the kinetic data.

Not Available

1985-07-01

350

Trace Elements Status in Selenium-Deficient Rats—Interaction with Cadmium  

Microsoft Academic Search

Although the metabolic and toxicological interactions between essential element selenium (Se) and toxic element cadmium (Cd)\\u000a have been reported for a long time, the experimental studies explored mostly acute, high-dose interactions. Limited data are\\u000a available regarding the effects of Se-deficiency on toxicokinetics of cadmium, as well as on the levels of key trace elements—copper,\\u000a zinc, and iron. In the present

Dana Kotyzová; Pavla ?erná; Ladislav Lešetický; Vladislav Eybl

2010-01-01

351

Cadmium biosorption by Saccharomyces cerevisiae  

Microsoft Academic Search

Cadmium uptake by nonliving and resting cells of Saccharomyces cerevisiae obtained from aerobic or anaerobic cultures from pure cadmium-bearing solutions was examined. The highest cadmium uptake exceeding 70 mg Cd\\/g was observed with aerobic baker's yeast biomass from the exponential growth phase. Nearly linear sorption isotherms featured by higher sorbing resting cells together with metal deposits localized exclusively in vacuoles

B. Volesky; H. May; Z. R. Holan

1993-01-01

352

The Iron Assimilatory Protein, FEA1, from Chlamydomonas reinhardtii Facilitates Iron-Specific Metal Uptake in Yeast and Plants.  

PubMed

We demonstrate that the unique green algal iron assimilatory protein, FEA1, is able to complement the Arabidopsis iron-transporter mutant, irt1, as well as enhance iron accumulation in FEA1 expressing wild-type plants. Expression of the FEA1 protein reduced iron-deficient growth phenotypes when plants were grown under iron limiting conditions and enhanced iron accumulation up to fivefold relative to wild-type plants when grown in iron sufficient media. Using yeast iron-uptake mutants, we demonstrate that the FEA1 protein specifically facilitates the uptake of the ferrous form of iron. Significantly, the FEA1 protein does not increase sensitivity to toxic concentrations of competing, non-ferrous metals nor facilitate their (cadmium) accumulation. These results indicate that the FEA1 protein is iron specific consistent with the observation the FEA1 protein is overexpressed in cadmium stressed algae presumably to facilitate iron uptake. We propose that the FEA1 iron assimilatory protein has ideal characteristics for the iron biofortification of crops and/or for facilitated iron uptake in plants when they are grown in low iron, high pH soils, or soils that may be contaminated with heavy metals. PMID:22639604

Narayanan, Narayanan N; Ihemere, Uzoma; Chiu, Wai Ting; Siritunga, Dimuth; Rajamani, Sathish; Singh, Sareena; Oda, Saharu; Sayre, Richard T

2011-10-21

353

The Iron Assimilatory Protein, FEA1, from Chlamydomonas reinhardtii Facilitates Iron-Specific Metal Uptake in Yeast and Plants  

PubMed Central

We demonstrate that the unique green algal iron assimilatory protein, FEA1, is able to complement the Arabidopsis iron-transporter mutant, irt1, as well as enhance iron accumulation in FEA1 expressing wild-type plants. Expression of the FEA1 protein reduced iron-deficient growth phenotypes when plants were grown under iron limiting conditions and enhanced iron accumulation up to fivefold relative to wild-type plants when grown in iron sufficient media. Using yeast iron-uptake mutants, we demonstrate that the FEA1 protein specifically facilitates the uptake of the ferrous form of iron. Significantly, the FEA1 protein does not increase sensitivity to toxic concentrations of competing, non-ferrous metals nor facilitate their (cadmium) accumulation. These results indicate that the FEA1 protein is iron specific consistent with the observation the FEA1 protein is overexpressed in cadmium stressed algae presumably to facilitate iron uptake. We propose that the FEA1 iron assimilatory protein has ideal characteristics for the iron biofortification of crops and/or for facilitated iron uptake in plants when they are grown in low iron, high pH soils, or soils that may be contaminated with heavy metals.

Narayanan, Narayanan N.; Ihemere, Uzoma; Chiu, Wai Ting; Siritunga, Dimuth; Rajamani, Sathish; Singh, Sareena; Oda, Saharu; Sayre, Richard T.

2011-01-01

354

Mechanism of Impurity Poisoning in the Luminescence of Zinc Sulfide Phosphors with Manganese Activator  

Microsoft Academic Search

An investigation was made of the poisoning effects of iron, cobalt, and nickel impurity in cub.-Zns: Mn phosphors. The parameters varied included: (1) proportion of manganese, (2) proportion of poison impurity, (3) photon energy of the exciting radiation, (4) intensity of the exciting radiation, and (5) operating temperature of the phosphor. Analysis of the results shows that the two most

Richard H. Bube; Simon Larach; Ross E. Shrader

1953-01-01

355

Effect of heat treatment on the structure and properties of alloyed white cast iron  

Microsoft Academic Search

1.Heat treatment of white cast iron alloyed with manganese and vanadium in certain combinations makes it possible to obtain strength, toughness, and wear resistance that are unusually high for cast irons.2.These cast irons can be used for parts operating under abrasive wear conditions at high loads.

G. I. Sil'man; M. S. Frol'tsov; N. A. Bolkhovitina

1976-01-01

356

Preparation of chemical manganese dioxide from manganese sulfate  

Microsoft Academic Search

Chemical Manganese Dioxide (CMD) was prepared by an alkali-oxidation method. There are several virtues to this environmental friendly and clean process, including the nontoxic and harmless reagents and products, easy operations, no pollutants, easily obtained raw materials and moderate reaction conditions. The synthesized manganese dioxide was characterized by XRD and SEM. The particles were small, consisting primarily of ?-MnO2 and

Jiangang FU; Zhangxing HE; Hui WANG; Wei LIANG; Chao GUO

2010-01-01

357

Disulfide disproportionation and CdS formation upon cadmium sorption on FeS{sub 2}  

SciTech Connect

Adsorption reactions are important for understanding the distribution of ions between aqueous and solid phases; they govern solution concentrations, bioavailability, and mobility of ions in the environment. Iron disulfide is a sorbent of cadmium in reduced systems but sorption on sulfides is not well understood. The purpose of this research is to determine the surface structures and products of cadmium sorbed on amorphous FeS{sub 2}. Raman spectroscopy, x-ray diffraction, electron microscopy, and scanning tunneling microscopy were used to study the disulfide surface. The FeS{sub 2} undergoes surface reconstruction and disproportionation during cadmium sorption, which leads to discrete zones of elemental sulfur, cadmium sulfide, and iron hydroxide. Therefore, simple surface complexation is not the predominant mechanism of sorption. Disproportionation may provide a mechanism for the surface to reorganize and for isolated crystalline cadmium sulfide domains to develop. Cadmium surface precipitates are very stable and their formation may be a significant means of attenuating this hazardous element. Thus, it appears that FeS{sub 2} may be an important sorbent of cadmium in natural environments.

Bostick, B.C.; Fendorf, S.; Fendorf, M.

2000-01-01

358

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

359

Mortality of copper cadmium alloy workers with special reference to lung cancer and non-malignant diseases of the respiratory system, 1946-92  

Microsoft Academic Search

OBJECTIVES--To identify and quantify any relations between occupational exposure to cadmium oxide fume and mortalities from lung cancer and from chronic non-malignant diseases of the respiratory system. METHODS--The mortality experience of 347 copper cadmium alloy workers, 624 workers employed in the vicinity of copper cadmium alloy work (vicinity workers), and 521 iron and brass foundry workers (all men) was investigated

T Sorahan; A Lister; M S Gilthorpe; J M Harrington

1995-01-01

360

Cadmium Retention in Rats Fed Either Bound Cadmium in Scallops or Cadmium Sulfate.  

National Technical Information Service (NTIS)

Feeding studies were conducted to compare the effects of dietary sources of cadmium and protein on the excretion and retention of cadmium in the weanling rat. In the first study, whether ingested as bound cadmium in calico scallops (Aequipecten gibbus) or...

H. R. Legally G. N. Biddle T. C. Siewicki

1980-01-01

361

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

362

Hot Coal Gas Desulfurization with manganese based sorbents. Quarterly report, August 1, 1993--September 30, 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 report documents progress in pelletizing and testing via thermogravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite. Preliminary results 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.

1993-10-01

363

Cadmium in the aquatic environment  

SciTech Connect

This volume presents a comprehensive account of current research on the chemistry and toxicology of cadmium in natural waters. The first four chapters focus on the sources (natural vs. anthropogenic), behavior, and fate of cadmium in natural waters. These are followed by three chapters on the biocycling and effects of cadmium on freshwater biota. The ecotoxicity of cadmium to marine biota are covered by the next two chapters. The final chapter presents a succinct review of the analytical chemistry of cadmium in natural waters.

Nriagu, J.O.; Sprague, J.B. (eds.)

1987-01-01

364

Treatment of cadmium and nickel electroplating rinse water by electrocoagulation.  

PubMed

Treatments of cadmium-cyanide and nickel-cyanide electroplating rinse water were investigated in an electrochemical reactor equipped with iron plate electrodes in a batch mode by electrocoagulation (EC). Effects of the process variables such as pH, current density, and operating time were explored with respect to removal efficiencies of cadmium, nickel and cyanide in electroplating rinse water and operating costs as well. Removal efficiencies and operating costs under the optimum conditions (30 A/m2, 30 min and pH 8-10 for cadmium; 60A/m2, 80 min and pH 8-10 for nickel) for the EC process in electroplating rinse water were determined as 99.4% and 1.05/m3 for cadmium, 99.1% and 2.45/m3 for nickel and > 99.7% for cyanide, respectively. The results indicated that EC was very effective treatment for the removals of cadmium, nickel, and cyanide ions from the electroplating rinse water. PMID:21214006

Kobya, M; Demirbas, E; Parlak, N U; Yigit, S

2010-12-01

365

Standard Reference Materials: Methods for the Chemical Analysis of White Cast Iron Standards.  

National Technical Information Service (NTIS)

The procedures described are those used at the National Bureau of Standards in the analysis of white cast iron standard reference materials for the ten major elements; namely, carbon, manganese, phosphorus, sulfur, silicon, copper, nickel, chromium, vanad...

J. I. Shultz

1965-01-01

366

Standard Reference Materials: Methods for the Chemical Analysis of White Cast Iron Standards.  

National Technical Information Service (NTIS)

The procedures described in this publication are those used at the National Bureau of Standards in the analysis of white cast iron standard reference materials for the ten (10) major elements; namely, carbon, manganese, phosphorus, sulfur, silicon, copper...

J. I. Shultz

1965-01-01

367

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.

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

2006-01-01

368

Extraction of manganese from electrolytic manganese residue by bioleaching.  

PubMed

Extraction of manganese from electrolytic manganese residues using bioleaching was investigated in this paper. The maximum extraction efficiency of Mn was 93% by sulfur-oxidizing bacteria at 4.0 g/l sulfur after bioleaching of 9days, while the maximum extraction efficiency of Mn was 81% by pyrite-leaching bacteria at 4.0 g/l pyrite. The series bioleaching first by sulfur-oxidizing bacteria and followed by pyrite-leaching bacteria evidently promoted the extraction of manganese, witnessing the maximum extraction efficiency of 98.1%. In the case of sulfur-oxidizing bacteria, the strong dissolution of bio-generated sulfuric acid resulted in extraction of soluble Mn2+, while both the Fe2+ catalyzed reduction of Mn4+ and weak acidic dissolution of Mn2+ accounted for the extraction of manganese with pyrite-leaching bacteria. The chemical simulation of bioleaching process further confirmed that the acid dissolution of Mn2+ and Fe2+ catalyzed reduction of Mn4+ were the bioleaching mechanisms involved for Mn extraction from electrolytic manganese residues. PMID:21050747

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

2010-11-02

369

Sources of Atmospheric Cadmium.  

National Technical Information Service (NTIS)

This report is one of a series of reports which will be used by EPA in responding to the Congressional request under section 122 of the Clean Air Act Amendments of 1977 to determine whether atmospheric emissions of cadmium pose any threat to public health...

R. Coleman

1979-01-01

370

CADMIUM PHOSPHATE GLASS  

DOEpatents

A method of preparing a cadmium phosphate glass that comprises providing a mixture of solid inorganic compounds of cadmuim and phosphate having vaporizable components and heating the resulting composition to a temperature of at least 850 un. Concent 85% C is presented. (AEC)

Carpenter, H.W.; Johnson, P.D.

1963-04-01

371

Cadmium and prostate cancer  

Microsoft Academic Search

Prostatic cancer is a common and frequently lethal malignant disease. In the United States and other countries the incidence and mortality rate of prostate cancer continue to rise. Cancer of the prostate has an extremely complex etiology and appears dependent on a variety of factors, making linkage to a single factor very difficult to detect. Cadmium is a metallic toxin

Michael P. Waalkes; Sabine Rehm

1994-01-01

372

Study of hazardous metals in iron slag waste using laser induced breakdown spectroscopy  

Microsoft Academic Search

Laser Induced Breakdown Spectroscopy (LIBS) was applied for quantitative elemental analysis of slag samples collected from a local steel plant using an Nd: YAG laser emitting radiation at 1064 nm wavelength. The concentration of different elements of environmental significance such as cadmium, calcium, sulfur, magnesium, chromium, manganese, titanium, barium, phosphorus and silicon were 44, 2193, 1724,78578, 217260, 22220, 5178, 568,

M. A. Gondal; T. Hussain; Z. H. Yamani; A. H. Bakry

2007-01-01

373

Maternal–fetal Distribution of Manganese in the Rat Following Inhalation Exposure to Manganese Sulfate  

Microsoft Academic Search

Studies examining the pharmacokinetics of manganese during pregnancy have largely focused on the oral route of exposure and have shown that the amount of manganese that crosses the rodent placenta is low. However, limited information exists regarding the distribution of manganese in fetal tissues following inhalation. The objective of this study was to determine manganese body burden in CD rats

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

2005-01-01

374

Ligating properties of a potentially tetradentate Schiff base [(CH3)2NCH2CH2N?CHC6H3(OH)(OMe)] with zinc(ii), cadmium(ii), cobalt(ii), cobalt(iii) and manganese(iii) ions: synthesis and structural studies  

Microsoft Academic Search

As eries of Zn( II), Cd(II), Co(II), Co(III )a nd Mn( III) complexes with the Schiff base ((CH3)2NCH2CH2N=CHC6H3(OH)(OMe)), LH, derived from 2-dimethylaminoethylamine and o-vanillin, has been synthesised and structures of all the products have been established by X-ray crystallography. In the cases of zinc and cadmium, dimeric complexes (Zn(LH)2(NCS)) (Zn2(L)(l1,1-CH3COO)(NCS)3 )( 1), (Cd2(L)2(Cl)2 )( 2) and (Cd2(L)2(NCS)2 )( 3), and

Soma Sen; Pritha Talukder; Subrata K. Dey; Samiran Mitra; Georgina Rosair; David L. Hughes; Glenn P. A. Yap; Guillaume Pilet; V. Gramlich; T. Matsushita

2006-01-01

375

Cadmium, osteoporosis and calcium metabolism.  

PubMed

Occupational exposure to cadmium has for long been associated with renal tubular cell dysfunction, osteomalacia with osteoporosis, hypercalciuria and renal stone formation. High environmental exposure in Japan resulting from a stable diet of cadmium contaminated rice caused itai-itai disease, fractures occurring mainly in elderly multiparous women, with a form of osteomalacia, osteoporosis and renal dysfunction. More recently a population based study in Europe, in the vicinity of zinc smelters has shown that low to moderate exposure to cadmium, with a mean urinary excretion of cadmium of the order of 1 microg/g creatinine has been associated with a decrease in bone density, an increased risk of bone fractures in women and of height loss in men. In a population-based study of residents near a cadmium smelter in China, forearm bone density was shown to decrease linearly with age and urinary cadmium in both sexes, suggesting a dose effect relationship between cadmium dose and bone mineral density. A marked increase in the prevalence of fractures was shown in the cadmium-polluted area in both sexes. Concentrations of cadmium in blood and urine were taken as exposure biomarkers, and beta2-microglobulin, retinol binding protein and albumin as biomarkers of effect. A marked dose response relationship between these indicators of exposure and effect was shown. Hypercalciuria, which may progress to osteoporosis, has been taken as a sensitive renal-tubular biomarker of a low level of cadmium exposure. Cadmium may also act directly on bone. Animal studies have shown cadmium to stimulate the formation and activity of osteoclasts, breaking down the collagen matrix in bone. Osteoporosis is the main cause of fracures in post-menopausal women, a common occurrence worldwide, giving rise to disability and a high cost to health services. The identification of cadmium, an environmental pollutant, as one causal factor is highly significant in helping to control the incidence of this complex condition. PMID:15688852

Kazantzis, George

2004-10-01

376

Essential and nonessential elements in nestling rooks Corvus frugilegus from eastern Poland with a special emphasis on their high cadmium contamination.  

PubMed

Concentration of minerals (sodium, potassium, calcium [Ca], magnesium, iron [Fe], copper, zinc [Zn], manganese [Mn], and cobalt) as well as toxic metals (cadmium [Cd], lead [Pb]) were determined in five tissues (liver, lung, kidney, muscle, and bone) of nestling rooks (Corvus frugilegus; 1 to 13 days old) found dead in seven breeding colonies in eastern Poland. Cd concentration in all analyzed tissues was in the narrow range of 17.0-17.2 mg/kg dry weight (dw) Cd, which in the light of the literature data indicates acute contamination by this toxic metal. Similarly, we found increased levels of Pb, which in all tissues ranged between 5.0 and 6.2 mg/kg dw. Results of multivariate general linear model (GLM) testing of the effect of three variables (tissue type, colony, and nestling age) on tissue concentrations of various metals showed significance for Fe, Cu, Zn, and Mn. Only concentrations of Ca, Fe, and Zn differed significantly between the analyzed tissues. GLM analysis did not show any statistically significant differences in tissue levels of minerals and both toxic metals among examined rookeries, which indicates the widespread presence of nonpoint Cd and Pb pollution linked to agricultural activity and similar levels of these inorganic contaminants on crop fields (feeding grounds) around breeding colonies. We concluded that high levels of both toxic metals, Cd and Pb, probably resulting from the diet of nestling rooks, are based mainly on a diet of ground-dwelling beetles gathered on crop fields. PMID:22945854

Or?owski, Grzegorz; Kami?ski, Piotr; Kasprzykowski, Zbigniew; Zawada, Zbigniew; Koim-Puchowska, Beata; Szady-Grad, Ma?gorzata; Klawe, Jacek J

2012-09-04

377

Relating the sediment phase speciation of arsenic, cadmium, and chromium with their bioavailability for the deposit-feeding polychaete Nereis succinea.  

PubMed

We studied the influence of sediment geochemistry on bioavailability of As, Cd, and Cr in deposit-feeding polychaetes. Metal phase speciation in sediments was determined with a sequential extraction scheme, and assimilation efficiencies (AEs) of ingested metals were determined by pulse-chase feeding experiments using ?-emitting isotopes. Worms were fed sediments collected from geochemically diverse estuaries that were labeled by sorbing dissolved radiotracers or mixing with radiolabeled algae. Uptake of sediment-bound metals was compared with that from labeled algae or goethite. Metal AEs showed a positive relationship with the exchangeable and carbonate sedimentary fractions, whereas metals in iron and manganese oxides and acid-volatile sulfides, or in pyrite and other refractory material, were inversely correlated with AEs. Arsenic was most bioavailable from algae (72%), less from sediments mixed with algae (24-70%) and least from sediments labeled directly (1-12%). Arsenic AEs in sediments labeled directly showed a positive correlation with sedimentary Mn and Al and negative correlation with Fe. Cadmium AEs were positively correlated with salinity and negatively correlated with sedimentary organic C. The AEs of Cr from sediments or algae were less than 5%, but they were 34% from pure goethite. By quantifying the relationship of metal speciation in sediments with their bioavailability for deposit-feeding polychaetes, the present study provides new insight into understanding metal bioaccumulation in benthic invertebrates. PMID:21154840

Baumann, Zofia; Fisher, Nicholas S

2011-01-20

378

21 CFR 73.2775 - Manganese violet.  

Code of Federal Regulations, 2013 CFR

...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity...Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in...

2013-04-01

379

21 CFR 582.5452 - Manganese gluconate.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b)...

2013-04-01

380

21 CFR 582.5449 - Manganese citrate.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b)...

2013-04-01

381

21 CFR 582.5458 - Manganese hypophosphite.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite....

2013-04-01

382

Toxicological Profile for Manganese and Compounds.  

National Technical Information Service (NTIS)

The ATSDR Toxicological Profile is intended to characterize succinctly the toxicological and health effects information for manganese compounds. It identifies and reviews the key literature that describes manganese compounds' toxicological properties. Oth...

1992-01-01

383

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

384

MANGANESE OXIDE REDUCTION IN LABORATORY MICROCOSMS  

Microsoft Academic Search

Manganese biogeochemistry holds special interest for the characterization of passive treatment systems designed to treat acidic mine waters while meeting enforceable effluent discharge limits set for manganese. In the present study, an initial anoxic enrichment culture was developed for use as an inoculum in experimental systems. Standard anoxic microcosms capable of reducing manganese from ~n~' to ~n'' were established from

Richard A. Royer; Richard F. Unz

2006-01-01

385

Manganese oxide cathodes for rechargeable batteries  

Microsoft Academic Search

Manganese oxides are considered as promising cathodes for rechargeable batteries due to their low cost and low toxicity as well as the abundant natural resources. In this dissertation, manganese oxides have been investigated as cathodes for both rechargeable lithium and alkaline batteries. Nanostructured lithium manganese oxides designed for rechargeable lithium cells have been synthesized by reducing lithium permanganate with methanol

Dongmin Im

2002-01-01

386

Autonomic Function in Manganese Alloy Workers  

Microsoft Academic Search

The observation of orthostatic hypotension in an index case of manganese toxicity lead to this prospective attempt to evaluate cardiovascular autonomic function and cognitive and emotional neurotoxicity in eight manganese alloy welders and machinists. The subjects consisted of a convenience sample consisting of an index case of manganese dementia, his four co-workers in a “frog shop” for gouging, welding, and

William W. Barrington; Carol R. Angle; Nancy K. Willcockson; Marjorie A. Padula; Thomas Korn

1998-01-01

387

21 CFR 184.1461 - Manganese sulfate.  

Code of Federal Regulations, 2010 CFR

...sulfate. (a) Manganese sulfate (MnSO4 ·H2...obtained by reacting manganese compounds with...byproduct in the manufacture of hydroquinone...on a slurry of manganese dioxide in sulfuric...with solid ferrous sulfate and coal,...

2010-01-01

388

21 CFR 184.1461 - Manganese sulfate.  

Code of Federal Regulations, 2010 CFR

...sulfate. (a) Manganese sulfate (MnSO4 ·H2...obtained by reacting manganese compounds with...byproduct in the manufacture of hydroquinone...on a slurry of manganese dioxide in sulfuric...with solid ferrous sulfate and coal,...

2009-04-01

389

Hot Coal Gas Desulfurization with manganese-based sorbents. Quarterly report, April--June 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 zincbased 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 Seventh Quarterly Report documents progress in bench-scale testing of a leading manganese-based sorbent pellets (FORM4-A). This formulation is a high-purity manganese carbonate-based material. This formulation was subjected to 20 consecutive cycles of sulfidation and regeneration at 900{degrees}C in a 2-inch fixed bed reactor. The sulfidation gas was a simulated Tampella U-gas with an increased hydrogen sulfide content of 3% by volume to accelerate the rate of breakthrough, arbitrarily taken as 500 ppmv. Consistent with thermo-gravimetric analysis (TGA) on individual pellets, the fixed bed tests show small improvement in capacity and kinetics with the sulfur-loading capacity being about 22% by weight of the original pellet, which corresponds to approximately 90% bed utilization!

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

1994-06-01

390

Critical review of animal carcinogenesis by cadmium and its inorganic compounds.  

National Technical Information Service (NTIS)

Animal carcinogenic biassays relative to 6 inorganic cadmium substances (cadmium metal, cadmium oxide, cadmium sulfide, cadmium sulfate, cadmium chloride and cadmium acetate) are reviewed (speciation). Critical evaluation of literature data on carcinogeni...

R. Maximilien B. Dero

1990-01-01

391

Dietary Cadmium and Risk of Invasive Postmenopausal Breast Cancer in the VITAL Cohort  

PubMed Central

Purpose Estimate the association between dietary intake of cadmium, a carcinogenic heavy metal, and risk of invasive breast cancer. Methods Study subjects were 30,543 postmenopausal women in the VITamins And Lifestyle (VITAL) cohort who completed a food frequency questionnaire (FFQ) at baseline (2000–2002). Dietary cadmium consumption was estimated by combining FFQ responses with US Food and Drug Administration data on food cadmium content. Incidence of invasive breast cancer was ascertained through linkage of the cohort to the western Washington Surveillance, Epidemiology, and End Results cancer registry through December 31, 2009. Cox regression was applied to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for breast cancer with increasing dietary cadmium intake, adjusted for total energy intake, smoking history, consumption of vegetables, potatoes, and whole grains, multivitamin use, education, race, body mass index, physical activity, age at first birth, postmenopausal hormone use, and mammography. Results Vegetables and grains together contributed an average of 66% of estimated dietary cadmium. During a mean of 7.5 years of follow-up, 1,026 invasive postmenopausal breast cancers were identified. Among 899 cases with complete covariate information, no evidence of an association between dietary cadmium intake and breast cancer risk was observed (aHR (95% CI), highest to lowest quartile cadmium: 1.00 (0.72–1.41), Ptrend=0.95). No evidence was found for interactions between dietary cadmium and breast cancer risk factors, smoking habits, or total intake of calcium, iron, or zinc from diet, supplements, and multivitamins. Conclusions This study does not support the hypothesis that dietary cadmium intake is a risk factor for breast cancer. However, non-differential measurement error in the estimate of cadmium intake is likely the most important factor that could have obscured an association.

Adams, Scott V.; Newcomb, Polly A.; White, Emily

2012-01-01

392

Carcinogenicity, mutagenicity and teratogenicity of manganese compounds.  

PubMed

Manganese, an essential trace element, is one of the most used metals in the industry. Recently, several new manganese compounds have been introduced as fungicide, as antiknock agent in petrol and as contrasting agent in nuclear magnetic resonance tomography. Manganese displays a somewhat unique behaviour with regard to its toxicity. It is relatively non-toxic to the adult organism except to the brain where it causes Parkinson-like symptoms when inhaled even at moderate amounts over longer periods of time. Relatively high doses of manganese affect DNA replication and repair in bacteria and causes mutations in microorganism and mammalian cells although the Ames test does not appear to be particularly responsive to manganese. In mammalian cells, manganese causes DNA damage and chromosome aberrations. Information on organic manganese derivatives is still insufficient. Large amounts of manganese affect fertility in mammals and are toxic to the embryo and foetus. The fungicide MANEB and the contrasting agent MnDPDP also can be embryotoxic, but the latter only at doses much higher than those clinically employed. Information on the anti-knock agent MMT is inadequate. On the other hand, manganese deficiency can also affect fertility and be teratogenic. Information on cancer due to manganese is scanty but the results available do not indicate that inorganic manganese is carcinogenic. More information is desirable with regard to the organic manganese derivatives. It may surprise that an agent that causes mutations is not also carcinogenic. The experience with manganese shows that conclusions with regard to carcinogenicity of an agent based on the observation of mutations are subject to uncertainties. Altogether, it appears that, because of the very high doses at which positive effects have been found, manganese would not represent a significant carcinogenic risk to the population and workers. Care must, however, be exercised with respect to central-nervous symptoms after chronic exposure and with respect to effects on the embryo. Pregnant women should not be exposed to manganese at the work place. PMID:11923066

Gerber, G B; Léonard, A; Hantson, Ph

2002-04-01

393

Cadmium and mercury nephrotoxicity.  

PubMed

Despite increasing attempts to control environmental pollution, changes in the distribution and bioavailability of toxic metals like mercury and cadmium are still occurring. Apart from natural processes, other contributory factors include the gradual spread of industrialization, the use of sewage sludge as a fertilizer and the acidification of Northern Hemisphere groundwater. Animals (including man and domestic varieties) can accumulate harmful concentrations of toxic metals. We therefore looked for damage to the kidneys in seabirds contaminated with mercury and cadmium and made comparisons with kidneys from three other groups of animals: seabirds from an uncontaminated colony, metal-dosed birds and metal-dosed mice. We report here that, comparing all these groups of animals, individuals with comparatively high levels of metals had nephrotoxic lesions of a similar type and severity. Moreover, the metal concentrations at which damage began and at which biochemical changes could be detected were below those presently considered as relatively safe for humans by the World Health Organization. PMID:6877384

Nicholson, J K; Kendall, M D; Osborn, D

394

Bioaccumulation of cadmium in marine organisms.  

PubMed Central

A general review of cadmium concentrations in marine organisms and studies of cadmium bioaccumulation is presented. Factors which influence cadmium concentrations, such as regional differences, seasonal fluctuations and salinity, are discussed and species which are likely to accumulate cadmium identified. Experimental studies designed to investigate the influence of some of these factors on cadmium bioaccumulation in a filter feeding bivalve mollusk, the American oyster (Crassostrea virginica), are presented. Field studies of seasonal dynamics of cadmium in oysters indicate patterns which may be correlated with seasonal physiological activity. The bioaccumulation of cadmium following input to estuarine systems by natural phenomena is observed. Cadmium concentrations in oysters collected from regions of different salinity suggest an inverse relationship between cadmium concentration and salinity. Laboratory experiments designed to investigate mechanisms of cadmium accumulation demonstrate that an inducible cadmium binding protein, similar to metallothiomein, is present in the American oyster.

Frazier, J M

1979-01-01

395

Simultaneous cadmium removal and 2,4-dichlorophenol degradation from aqueous solutions by Phanerochaete chrysosporium.  

PubMed

Phanerochaete chrysosporium has been recognised as an effective bioremediation agent due to its unique degradation to xenobiotic and biosorption ability to heavy metals. However, few studies have focused on the simultaneous removal of heavy metals and organic pollutants. The aim of this work was to study the feasibility of simultaneous cadmium removal and 2,4-dichlorophenol (2,4-DCP) degradation in P. chrysosporium liquid cultures. The removal efficiencies were pH dependent and the maximum removal efficiencies were observed at pH 6.5 under an initial cadmium concentration of 5 mg/L and an initial 2,4-DCP concentration of 20 mg/L. The removal efficiencies for cadmium and 2,4-DCP reached 63.62% and 83.90%, respectively, under the optimum conditions. The high production levels of lignin peroxidase (7.35 U/mL) and manganese peroxidase (8.30 U/mL) resulted in an increase in 2,4-DCP degradation. The protein content decreased with increasing cadmium concentration. The surface characteristics and functional groups of the biomass were studied by scanning electron microscopy and a Fourier-transformed infrared spectrometer. The results showed that the use of P. chrysosporium is promising for the simultaneous removal of cadmium and 2,4-DCP from liquid media. PMID:21556917

Chen, Anwei; Zeng, Guangming; Chen, Guiqiu; Fan, Jiaqi; Zou, Zhengjun; Li, Hui; Hu, Xinjiang; Long, Fei

2011-05-10

396

Flash-induced blocking of the high-affinity manganese-binding site in photosystem II by iron cations: dependence on the dark interval between flashes and binary oscillations of fluorescence yield.  

PubMed

Incubation of Fe(II) cations with Mn-depleted PSII membranes (PSII(-Mn)) under weak continuous light is accompanied by blocking of the high-affinity, Mn-binding (HAZ) site with ferric cations (Semin, B.K. et al. Biochemistry 2002, 41, 5854-5864). In this study we investigated the blocking yield under single-turnover flash conditions. The flash-probe fluorescence method was used to estimate the blocking efficiency. We found that the yield of blocking increases with flash number and reaches 50% after 7 flashes. When the dark interval between the flashes (Delta t) was varied, we found that the percentage of blocking decreases at Delta t < 100 ms (t 1/2, 4-10 ms). No inhibition of the blocking yield was found at longer time intervals (as with photoactivation). This result shows the necessity of a dark rearrangement during the blocking process (the dual-site hypothesis described in the text) and indicates the formation of a binuclear iron center. During the blocking experiments, we found a binary oscillation of the Fmax elicited during a train of flashes. The oscillations were observed only in the presence of Fe(II) cations or other electron donors (including Mn(II)) but not in the presence of Ca2+. Chelators had no effect on the oscillations. Our results indicate that the oscillations are due to processes on the acceptor side of PSII and to the appearance of "acceptor X" after odd flashes. Acceptor X is reduced by QA- at very high rate (<2 ms), is not sensitive to DCMU, and is rather stable in the dark (t l/2 approximately 2 min). These properties are similar to those of nonheme Fe(III) (Fe(III)NHI). When Fe(II)NHI was oxidized with ferricyanide (Fe(CN)6), the fluorescence decay kinetics and yield of fluorescence were identical to those observed when the sample was exposed to 1 flash prior to the fluorescence measurement. We suggest that acceptor X is Fe(III)NHI, oxidized by the semiquinone form of QB-. This is similar to the mechanism of "reduction-induced oxidation of Fe(II)NHI" by exogenous quinones reported in the literature. We suggest that involvement of QB- in the oxidation of Fe(II)NHI in PSII(-Mn) membranes is due to the modification of the QB-binding site and increase of its redox potential resulting from extraction of the functional Mn cluster. PMID:17166004

Semin, Boris K; Seibert, Michael

2006-12-21

397

Isolation of iron bacteria from terrestrial and aquatic environments  

NASA Astrophysics Data System (ADS)

Bacteria, which are capable of iron oxidation or at least iron deposition are widely distributed in environments where zones of dissolved ferrous iron and oxygen gradients are overlapping [1]. They take part in the biological cycling of iron and influence other cycles of elements for example carbon [2]. Manganese can be used for similar metabolic purposes as iron, because it can be biologically oxidized by chemolithotrophs or can be reduced by respirating bacteria as well [3, 4]. Bacterial activity is responsible for the accumulation of ferric iron compounds in their surroundings. The formation of bog ore is a well known example for a soil horizon, with an extreme enrichment of biogenic ferric iron [5]. We focused on the isolation of neutrophilic iron bacteria and bacteria capable of manganese oxidation. We used samples from Tierra del Fuego (Argentina) the National Park "Unteres Odertal" (Germany) and Berlin ground water wells. Microscopic examination of the samples revealed a considerable diversity of iron encrusted structures of bacterial origin. Most of these morphologic types are already well known. The taxonomic classification of many of these organisms is based on morphologic features and is not reliable compared to recent methods of molecular biology. That is mainly due to the fact, that most of these bacteria are hardly culturable or do not show their characteristic morphologic features under culture conditions. We established a collection of more than 300 iron depositing strains. Phylogenetic analyses showed that we have many yet uncultured strains in pure culture. We obtained many isolates which form distinct branches within long known iron bacteria groups like the Sphaerotilus-Leptothrix cluster. But some of the strains belong to groups, which have not yet been associated with iron oxidation activity. The strains deposit high amounts of oxidized iron and manganese compounds under laboratory conditions. However it is unclear if these precipitations are due to biological oxidation or biological deposition of chemically oxidized iron. We examined the morphologic characteristics of selected isolates under near-natural conditions to assign them to morphologic structures which occur in native samples. Our aim for the future is to describe several strains. References: [1] Weber, K. A. ; Achenbach, L. A. ; Coates, J. D. : Microorganisms pumping iron: anaerobic microbial iron oxidation and reduction. In: Nature Reviews Microbiology 4 (2006) 752-764 [2] Van Capellen, P. ; Wang Y. : Cycling of iron and manganese in surface sediments: a general theory for the coupled transport and reaction of carbon, oxygen, nitrogen, sulfur, iron and manganese. In: American Journal of Science 296 (1996) 197-243 [3] Tebo, B. M. ; Bargar, J. R. ; Clement, B. G. ; Dick, G. J. ; Murray, K. J. ; Parker, D. Verity R. ; Webb, S. M. : Biogenic manganese oxides: properties and mechanisms of formation. In: Annual Reviews Earth Planet Science 32 (2004) 287-328 [4] Erlich, H. L. : Manganese oxide reduction as a form of anaerobic respiration. In: Geomicrobiology Journal 5 (1987) 423-431 [5] Ghiorse W. C. : Biology of iron- and manganese-depositing bacteria. In: Annual Reviews 38 (1984) 515-550

Schmidt, Bertram; Szewzyk, Ulrich

2010-05-01

398

Response of the marine diatom Thalassiosira weissflogii to iron stress  

SciTech Connect

The coastal diatom Thalassiosira weissflogii responds to iron limitation with decreasing growth rate, decreasing quotas of cellular iron, and increasing rates of maximum short term uptake. Growth response to steady iron limitation can be modeled according to the equations of Droop and Monod. The cellular iron quota varies from about 2 to 25 x 10/sup -1/ mol iron per liter-cell with increasing iron; the half-saturation constant for growth, K..mu.., is 1.1 x 10/sup -21/ M (free ferric ion). In contrast, the half-saturation constant for /sup 59/I iron uptake, K/sub rho/ is about 3 x 10/sup -19/ M; the maximum iron uptake rate (rho/sub max/) is increased several-fold under iron limitation, resulting in a potential short term uptake rate that is a few hundred times the steady state rate. At a fixed concentration of free manganese ion, the cellular manganese quota is increased several-fold in iron-limited cultures compared to iron-sufficient cultures.

Harrison, G.I.; Morel, F.M.M.

1986-09-01

399

Urinary cadmium and beta2-microglobulin: correlation with nutrition and smoking history (journal version)  

SciTech Connect

Urinary cadmium and beta2-microglobulin concentrations from approximately 1000 samples from the general adult U.S. population, collected as part of the National Health and Nutritional Examination Survey II (NHANES II), were related to nutritional and smoking history of the individuals. Urinary cadmium concentration was negatively correlated with dietary iron (significance level of 0.0065), negatively correlated with dietary calcium (significance level of less than 0.0001), and significantly (level of less than 0.001) higher in past or present smokers than in those who had never smoked. The results suggest increased cadmium absorption in the presence of low dietary intake of iron, low dietary intake of calcium, and cigarette smoking in the general population of the United States.

Kowal, N.E.

1988-01-01

400

A novel Porphyromonas gingivalis FeoB plays a role in manganese accumulation.  

PubMed

FeoB is an atypical transporter that has been shown to exclusively mediate ferrous ion transport in some bacteria. Unusually the genome of the periodontal pathogen Porphyromonas gingivalis has two genes (feoB1 and feoB2) encoding FeoB homologs, both of which are expressed in bicistronic operons. Kinetic analysis of ferrous ion transport by P. gingivalis W50 revealed the presence of a single, high affinity system with a K(t) of 0.31 microM. FeoB1 was found to be solely responsible for this transport as energized cells of the isogenic FeoB1 mutant (W50FB1) did not transport radiolabeled iron, while the isogenic FeoB2 mutant (W50FB2) transported radiolabeled iron at a rate similar to wild type. This was reflected in the iron content of W50FB1 grown in iron excess conditions which was approximately half that of the wild type and W50FB2. The W50FB1 mutant had increased sensitivity to both oxygen and hydrogen peroxide and was avirulent in an animal model of infection whereas W50FB2 exhibited the same virulence as the wild type. Analysis of manganous ion uptake using inductively coupled plasma-mass spectrometry revealed a greater than 3-fold decrease in intracellular manganese accumulation in W50FB2 which was also unable to grow in manganese-limited media. The protein co-expressed with FeoB2 appears to be a novel FeoA-MntR fusion protein that exhibits homology to a manganese-responsive, DNA-binding metalloregulatory protein. These results indicate that FeoB2 is not involved in iron transport but plays a novel role in manganese transport. PMID:15901729

Dashper, Stuart G; Butler, Catherine A; Lissel, J Patricia; Paolini, Rita A; Hoffmann, Brigitte; Veith, Paul D; O'Brien-Simpson, Neil M; Snelgrove, Sarah L; Tsiros, John T; Reynolds, Eric C

2005-05-18

401

Catalytic role of Manganese oxides in prebiotic Nucleobases synthesis from Formamide  

NASA Astrophysics Data System (ADS)

The evolution of living cell from chemicals is more complicated reaction which could be studied in multistep. A study of prebiotic synthesis of naturally occurring purine and pyrimidine derivatives from formamide under catalytic condition with different oxides of manganese reveals a significant role. Manganese oxides are highly efficient in the conversion of formamide into different nucleobases. Neat formamide is converted to the purine, 9-(hydroxyacetyl) purine, cytosine, 4(3H)-pyrimidinone, thymine and adenine in good yield. Metal oxides have provided their surfaces and catalyzed the reactions from simple molecules to more complex bio-organic molecules. Our results show that probably prebiotic reactions might have occured on the sea floor where the existence of manganese oxide is second to iron transition metal minerals.

Bhushan, Brij

2012-07-01

402

MINERAL NUTRIENT STATUS OF THE CONSUMER AFFECTS THE BIOAVAILABILITY OF CADMIUM FROM FOOD  

Technology Transfer Automated Retrieval System (TEKTRAN)

Grains such as rice, wheat, and maize consumed as staple foods by different population groups differ greatly in their concentrations and bioavailability of nutrients that are antagonists to cadmium (Cd) absorption. These include zinc (Zn), iron (Fe), and calcium (Ca). We hypothesized that indiv...

403

Bioavailability as an issue in risk assessment and management of food cadmium: A review  

Technology Transfer Automated Retrieval System (TEKTRAN)

The bioavailability of cadmium (Cd) from food could be an important determinant of the risk potential of dietary Cd to the consumer. This review summarizes recent work that describes the effects of marginal deficiencies of the essential nutrients zinc (Zn), iron (Fe), and calcium (Ca) on the enhance...

404

Behavior of cadmium, lead and zinc at the sediment–water interface by electrochemically initiated processes  

Microsoft Academic Search

Nowadays, electrokinetic remediation is one of the popular and cheapest in situ remediation techniques for contaminated soils. This method uses a low-level electrical energy and is known for removal of heavy metals like, cadmium, chromium, copper, iron, lead, mercury, nickel, zinc and the metalloid arsenic from polluted and spiked soils. The driving force is the migration of those ions in

Reena Shrestha; R. Fischer; D. Rahner

2003-01-01

405

Origin of Oceanic Manganese Minerals  

Microsoft Academic Search

A criterion is suggested for discrimination between ferromanganese oxide minerals, deposited after the introduction of manganese and associated elements in sea water solution at submarine vulcanism, and minerals which are slowly formed from dilute solution, largely of continental origin. The simultaneous injection of thorium into the ocean by submarine vulcanism is indicated, and its differentiation from continental thorium introduced into

G. Arrhenius; J. Mero; J. Korkisch

1964-01-01

406

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

407

Manganese Star Iota Coronae Borealis.  

National Technical Information Service (NTIS)

An abundance analysis of the manganese star Iota Coronae Borealis is carried out in detail by making use of a model atmosphere with theta sub e = 0.458, log g = 3.7, N(He)/N(H) = 0.12. The energy distribution and H gamma profile are reproduced by this mod...

J. E. Ross L. H. Aller

1969-01-01

408

Metallothionein-like cadmium binding protein in rat testes administered with cadmium and selenium  

Microsoft Academic Search

It is well known that the testicular damage caused by acute cadmium toxicity are protected by simultaneous selenium administration with cadmium, and that the cadmium concentration in the testis increases remarkably as compared with that of only cadmium administration. The increased cadmium in the testis was found in the high molecular weight fraction containing selenium, and it has been thought

Hisayoshi Ohta; Yukio Seki; Shunichiro Imamiya

1988-01-01

409

Cadmium treatment and lead-induced suppression of splenic erythropoiesis.  

PubMed

Young adult female mice were injected with lead acetate (d 0). Following injection, determinations were made of the percentages of radioactive iron (59Fe) uptake into the hemoglobin of erythrocytes produced by spleen. Control 59Fe uptake percentage vacillated between 4.2 and 5.5 within the 7-d period of observation. On d 4 following lead treatment, splenic percentages were dramatically reduced below those of the saline-injected controls; by d 6 the splenic 59Fe uptake of lead-treated mice was comparable to that of controls. For rodents injected with cadmium chloride on 0, the 59Fe uptake values showed a statistically significant elevation by d 2, which was extended beyond that of the controls' d 4 value. For those animals receiving both lead and cadmium (d 0), the uptake percentages paralleled those of the controls throughout the 7-d period of observation. These data suggest that the inhibitory effect of lead on erythropoiesis of the spleen is blocked by a concurrent cadmium treatment. Results are interpreted in regard to a possible vulnerable target and competition for the target by lead and cadmium. PMID:1728662

Hogan, G R

1992-01-01

410

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

411

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

412

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

413

Status of and prospects for cadmium substitution.  

National Technical Information Service (NTIS)

About 2069 t of cadmium were used in West Germany in 1979. Intensive efforts reduced cadmium consumption to 1079 t in 1981. Since then a weak increase in cadmium consumption can be observed. Other industrialized countries use much less cadmium, at least i...

E. Boehm W. Toetsch

1989-01-01

414

Accumulation of cadmium by Artemia salina  

Microsoft Academic Search

The relative importance of accumulation of cadmium by Artemia salina (L.) directly from solution and from ingested food has been studied at 3 cadmium concentrations (0.1, 1 and 10 ppm) under controlled experimental conditions. At each cadmium concentration, A. salina were exposed to cadmium in 4 ways; in solution; in solution in the presence of latex “food” particles; in solution

J. R. Jennings; P. S. Rainbow

1979-01-01

415

Cancer mortality of cadmium workers.  

PubMed Central

Several epidemiological studies of workers exposed to cadmium indicate an increased risk of lung and prostatic cancer. The increase is statistically significant in some of the studies but the SMR is greater than 100 in almost all. A cohort study of the mortality among 522 Swedish workers exposed to cadmium for at least one year in a nickel-cadmium battery plant support the earlier findings. The SMR for lung and prostatic cancer increased with increasing dose and latency but did not obtain statistical significance. A combination of all the available data from the most recent follow up of causes of death among cadmium workers in six different cohorts shows 28 cases of prostatic cancer (SMR = 162) and 195 cases of lung cancer (SMR = 121). This new analysis suggests that long term, high level exposure to cadmium is associated with an increased risk of cancer. The role of concomitant exposure to nickel needs further study.

Elinder, C G; Kjellstrom, T; Hogstedt, C; Andersson, K; Spang, G

1985-01-01

416

Cadmium Toxicity in Glutathione Mutants of Escherichia coli? †  

PubMed Central

The higher affinity of Cd2+ for sulfur compounds than for nitrogen and oxygen led to the theoretical consideration that cadmium toxicity should result mainly from the binding of Cd2+ to sulfide, thiol groups, and sulfur-rich complex compounds rather than from Cd2+ replacement of transition-metal cations from nitrogen- or oxygen-rich biological compounds. This hypothesis was tested by using Escherichia coli for a global transcriptome analysis of cells synthesizing glutathione (GSH; wild type), ?-glutamylcysteine (?gshB mutant), or neither of the two cellular thiols (?gshA mutant). The resulting data, some of which were validated by quantitative reverse transcription-PCR, were sorted using the KEGG (Kyoto Encyclopedia of Genes and Genomes) orthology system, which groups genes hierarchically with respect to the cellular functions of their respective products. The main difference among the three strains concerned tryptophan biosynthesis, which was up-regulated in wild-type cells upon cadmium shock and strongly up-regulated in ?gshA cells but repressed in ?gshB cells containing ?-glutamylcysteine instead of GSH. Overall, however, all three E. coli strains responded to cadmium shock similarly, with the up-regulation of genes involved in protein, disulfide bond, and oxidative damage repair; cysteine and iron-sulfur cluster biosynthesis; the production of proteins containing sensitive iron-sulfur clusters; the storage of iron; and the detoxification of Cd2+ by efflux. General energy conservation pathways and iron uptake were down-regulated. These findings indicated that the toxic action of Cd2+ indeed results from the binding of the metal cation to sulfur, lending support to the hypothesis tested.

Helbig, Kerstin; Grosse, Cornelia; Nies, Dietrich H.

2008-01-01

417

Soluble manganese removal by porous media filtration.  

PubMed

Filtration experiments were conducted to investigate soluble manganese removal in granular media filtration; sand, manganese oxide coated sand (MOCS), sand + MOCS (1:1) and granular activated carbon (GAC) were used as filter media. Manganese removal, manganese oxide accumulation, turbidity removal, and regeneration of MOCS under various conditions were examined. Soluble manganese removal by the MOCS column was rapid and efficient; most of the removal happened at the top (e.g. 5 cm) of the filter. When filter influent with an average manganese concentration of 0.204 mg l(-1) was fed through the filter columns, the sand + MOCS and MOCS columns removed 98.9% and 99.2% of manganese, respectively. However, manganese removal in sand and the GAC columns was not significant during the initial stage of filtration, but after eight months of filter run they could remove 99% and 35% of manganese, respectively. It was revealed that partial replacement of sand with MOCS showed comparable manganese removal to that of the MOCS filter media. PMID:19149348

Kim, J; Jung, S

2008-12-01

418

IMPROVEMENT OF SCREENING FOR MANGANESE EFFICIENCY BY PRODUCING SEED WITH SIMILAR MANGANESE CONTENT IN DIFFERENT GENOTYPES AND GENETIC STOCKS  

Microsoft Academic Search

Genetic improvement of manganese efficiency of crops demands a precise bioassay that avoids the confounding effect of seed manganese on the bioassay for the trait, for a proper comparison of the genotypes the seed manganese content must be similar. Variation in seed manganese can be minimized by the addition of manganese to individual seeds to be planted providing the effect

H. Khabaz-Saberi; R. D. Graham

2002-01-01

419

Status of the cadmium thermoelectrochemical hydrogen cycle  

Microsoft Academic Search

The three-step cadmium thermoelectrochemical water-splitting cycle produces hydrogen by an electrochemical reaction of water with an anode of cadmium metal, which is regenerated by the thermochemical decomposition of by-product cadmium oxide at temperatures of 1200°C and higher. Work on the electrochemical step has centered on the removal of the passivating layer of cadmium hydroxide that forms on the cadmium metal

T. Whaley; B. Yudow; R. Remick; J. Pangborn; A. Sammells

1982-01-01

420

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

421

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...Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. ...The chemical substance identified as cobalt lithium manganese nickel...