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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, mercury, iron, copper, manganese and zinc in the liver and kidney of the Icelandic lamb.  

PubMed

The purpose of this study was to evaluate the levels of cadmium, mercury, iron, copper, manganese and zinc in lamb liver and kidney from six areas in Iceland and to compare the results against aerial deposition data for the same elements obtained using moss as an indicator organism. The total number of samples was 96 for each organ. Cadmium was determined by graphite furnace atomic absorption spectrophotometry, mercury by cold-vapour atomic absorption, and iron, copper, manganese and zinc by inductively coupled plasma atomic emission spectrophotometry. Analysis of variance determined significance differences among means for areas, and Pearson's correlation coeffcients were calculated to study correlation among trace elements in liver and kidney. The mean fresh weight concentrations in lamb liver and kidney respectively were 0.045 and 0.058 mgkg(-1) for cadmium, 0.009 and 0.012 mgkg(-1) for mercury, 141 and 52.7 mgkg(-1) for iron, 28.1 and 2.89 mgkg(-1) for copper, 4.01 and 1.13 mgkg(-1) for manganese and 48.7 and 25.2 mgkg(-1) for zinc. Concentrations of cadmium, mercury and copper in the liver and kidney of the Icelandic lamb were low compared with data from other countries. Iron concentrations in the organs, however, were high. No sample exceeded 46% of the proposed maximum level for cadmium in organs for human consumption in the EC. Cadmium, mercury, iron and copper in the liver and kidney differed significantly between areas. Deposition of cadmium and copper in moss was not a usefull indicator in the evaluation of the susceptibility of the Icelandic lamb to accumulation of cadmium and copper. However, iron levels in Icelandic lamb liver showed the same pattern as results for iron from the moss study. The cadmium and mercury levels of organs from lambs grazing in the vicinity of Mount Hekla a few months after its eruption did not indicate a significant contamination from volcanic activity. PMID:11665737

Reykdal, O; Thorlacius, A

2001-11-01

3

Total and Suspended Cadmium, Cobalt, Copper, Iron, Lead, Manganese, Nickel, and Zinc in the Water Column of the Black Sea  

Microsoft Academic Search

\\u000a The trace metals cadmium, cobalt, copper, iron, manganese, nickel, lead and zinc were determined at eleven different stations\\u000a in the Black Sea, in November 1984. Sampling from the surface down to 2100 m was carried out. Suspended matter was collected\\u000a and analysed. It was found that elements which form strong sulphide complexes show significantly lower concentration in the\\u000a anoxic zone.

Conny Haraldsson; Stig Westerlund

4

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

5

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

PubMed Central

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

2014-01-01

6

The levels of cadmium, nickel, manganese lead, zinc, iron, tin, copper and arsenic in the brined canned Jordanian cheese.  

PubMed

The levels of cadmium, nickel, manganese, lead, zinc, iron, tin, copper and arsenic in fresh sheep's milk, white brined cheese preserved in glass jars and in tin containers and their corresponding brines, salt and tin plates were determined by atomic absorption spectrophotometry. The results have been compared with those reported in recent years. Although metal levels were comparable with other investigators' data, our data shows that white brined cheese picked-up metals from tin containers and from the naturally contaminated salt, on the contrary brined cheese in preserved glass jars showed lower levels of metals. We recommend a purified salt for brine preparation and glass jars for white cheese preservation in order to minimize cheese contamination with metals from tin cans and salt. PMID:8212904

Ereifej, K I; Gharaibeh, S H

1993-08-01

7

Manganese, copper, zinc, iron, cadmium, mercury and lead in muscle meat, liver and kidneys of poultry, rabbit and sheep slaughtered in the northern part of Poland, 1987  

Microsoft Academic Search

Manganese, copper, zinc, iron, cadmium, mercury and lead concentrations have been determined in muscle meat, livers and kidneys of ducks, geese, chickens, hens, rabbits and sheep slaughtered in the northern part of Poland in 1987. The mean values obtained related to wet weight for muscle meat, livers and kidneys of animals were: 0.11–0.27, 0.73–3.3 and 0.90–1.9 mg\\/kg Mn; 0.52–7.3, 3.8–88

J. Falandysz

1991-01-01

8

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

USGS Publications Warehouse

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

Sanzolone, R. F.

1986-01-01

9

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

SciTech Connect

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

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

2010-07-15

10

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

2013-03-01

11

[Effect of occupational lead exposure on various elements in the human blood. Effects on calcium, cadmium, iron, copper, magnesium, manganese and zinc levels in the human blood, erythrocytes and plasma in vivo].  

PubMed

The influence of occupational lead-exposure on calcium, magnesium and trace elements concentration in blood was investigated. We examined 96 lead-exposed persons and for comparison 46 persons without occupational lead exposure. The levels of lead, cadmium, calcium, iron, copper, magnesium, manganese and zinc were determined by atomic absorption spectrometry (AAS) in whole-blood, erythrocytes, as well as in plasma. The median of the lead-concentration in whole blood of the exposed group was 646 micrograms/l (+/- 66.6%-range: 449-814 micrograms/l). For the normal persons a median of 148 micrograms Pb/l (+/- 66.6%-range: 107-235 micrograms Pb/l) was calculated. In whole-blood, erythrocytes and plasma all element-concentrations of the non-exposed persons were in the normal ranges. The lead-exposed workers showed a higher manganese level. The other elements were found in normal values for this group. Increasing lead-concentrations in blood correlated with elevated levels of manganese and zinc in whole-blood, erythrocytes and plasma. The lead workers showed for the whole-blood manganese concentration a median of 14.2 micrograms/l (+/- 66.6%-range: 8.5-22.3 micrograms/l), for zinc a median of 6.3 mg/l (+/- 66.6%-range: 5.2-8.2 mg/l). Those levels were significantly higher than the levels of the non-exposed persons. For this group the median concentration of manganese was 4.8 micrograms/l (+/- 66.6%-range: 2.7-8.6 micrograms/l) and 5.7 mg/l (+/- 66.6%-range: 5.1-6.3 mg/l) for zinc respectively. For zinc positive correlation between blood lead levels and the levels of manganese and zinc in the three blood-compartments was found. An essential change of the element concentrations between erythrocytes and plasma, in the sense of a displacement from one blood-compartment to the other could not be detected. PMID:6475377

Truckenbrodt, R; Winter, L; Schaller, K H

1984-06-01

12

Battles with iron: manganese in oxidative stress protection.  

PubMed

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

Aguirre, J Dafhne; Culotta, Valeria C

2012-04-20

13

Cross-resistance of cadmium-resistant cells to manganese is associated with reduced accumulation of both cadmium and manganese.  

PubMed

The mechanism of cellular entry of cadmium remains unclear. We have previously established cadmium-resistant cells from mouse embryonic cells of metallothionein (MT)-null mice, and demonstrated that the down-regulation of a zinc transporter, Zrt/Irt-related protein (ZIP) 8, was responsible for the reduced cadmium incorporation into cells. In the present study, we developed cadmium-resistant cells (A+70 and B+70) from mouse embryonic cells of MT-expressing wild-type mice. The LC?? values of CdCl? for A+70 and B+70 cells were about 200 ?M while that of the parental cells was 30 ?M. We found that the cadmium resistance of these cells was conferred not only by enhanced expression of MT, but also by a decrease in cadmium accumulation. Since the uptake rates of cadmium into A+70 and B+70 cells were lowered, we determined the expression levels of the metal transporters and channels potentially involved in the cellular uptake of cadmium. We found a down-regulation of multiple transport systems, including ZIP8, divalent metal transporter 1 (DMT1), and ?? subunits of L-type (Ca(V)1.2) and T-type (Ca(V)3.1) voltage-dependent calcium channels, in A+70 and B+70 cells. Furthermore, A+70 and B+70 cells exhibited cross-resistance to cytotoxicity of MnCl?, probably due to a marked decrease in manganese uptake in these cells. These results suggest that the suppressed expression of ZIP8 and DMT1, which are known to have affinities for both cadmium and manganese, may be responsible for the reduction in the uptake, and consequently the cytotoxicity, of cadmium and manganese in A+70 and B+70 cells. PMID:21172401

Fujishiro, Hitomi; Kubota, Keisuke; Inoue, Daisuke; Inoue, Atsuhito; Yanagiya, Takahiro; Enomoto, Shuichi; Himeno, Seiichiro

2011-02-27

14

Phase instability of manganese-iron carbides  

Microsoft Academic Search

The stability of carbon saturated manganese-iron alloys was studied by means of simulated decrepitation tests, and it was\\u000a found that the product must contain a minimum of about 5 wt pct iron to be stable during storage. By means of several experimental\\u000a techniques it was shown that the structure of the carbide phase present in carbon saturated ferromanganese determines whether

G. J. W. Kor

1979-01-01

15

Iron and manganese dynamics in lake water  

Microsoft Academic Search

The speciation and fractionation of iron and manganese compounds from Hinze Dam water samples (Gold Coast City, Queensland, Australia) were studied using atomic absorption spectrophotometry (AAS), electron paramagnetic resonance spectroscopy (EPRS), gel filtration, ion-exchange chromatography, ultrafiltration and various acid digestion regimes. Samples were taken at various depths and times of year, and both filtrate and particulate samples of water column

Myint Zaw; Barry Chiswell

1999-01-01

16

First principle study of manganese doped cadmium sulphide sheet  

NASA Astrophysics Data System (ADS)

First-principle electronic structure calculations for cadmium sulphide (CdS) sheet in hexagonal phase, with Manganese substitution and addition, as well as including the Cd defects, are investigated. The lattice constants calculated for CdS sheet agrees fairly well with results reported for thin films experimentally. The calculations of total spin density of states and partial density of states in different cases shows substantial magnetic dipole moments acquired by the sheet. A magnetic dipole moment 5.00612 ?B and band gap of the order 1 eV are found when cadmium atom is replaced by Manganese. The magnetism acquired by the sheet makes it functionally important candidate in many applications.

Kumar, Sanjeev; Kumar, Ashok; Ahluwalia, P. K.

2014-04-01

17

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...substance identified generically as cobalt iron manganese oxide, carboxylic...

2013-07-01

18

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

19

Iron and manganese removal by using manganese ore constructed wetlands in the reclamation of steel wastewater.  

PubMed

To reclaim treated steel wastewater as cooling water, manganese ore constructed wetland was proposed in this study for the removal of iron and manganese. In lab-scale wetlands, the performance of manganese ore wetland was found to be more stable and excellent than that of conventional gravel constructed wetland. The iron and manganese concentration in the former was below 0.05 mg/L at hydraulic retention time of 2-5 days when their influent concentrations were in the range of 0.16-2.24 mg/L and 0.11-2.23 mg/L, respectively. Moreover, its removals for COD, turbidity, ammonia nitrogen and total phosphorus were 55%, 90%, 67% and 93%, respectively, superior to the corresponding removals in the gravel wetland (31%, 86%, 58% and 78%, respectively). The good performance of manganese ore was ascribed to the enhanced biological manganese removal with the aid of manganese oxide surface and the smaller size of the medium. The presence of biological manganese oxidation was proven by the facts of good manganese removal in wetlands at chemical unfavorable conditions (such as ORP and pH) and the isolation of manganese oxidizing strains from the wetlands. Similar iron and manganese removal was later observed in a pilot-scale gravel-manganese-ore constructed wetland, even though the manganese ore portion in total volume was reduced from 100% (in the lab-scale) to only 4% (in the pilot-scale) for the sake of cost-saving. The quality of the polished wastewater not only satisfied the requirement for cooling water but also suitable as make-up water for other purposes. PMID:19443107

Xu, Jing-Cheng; Chen, Gu; Huang, Xiang-Feng; Li, Guang-Ming; Liu, Jia; Yang, Na; Gao, Sai-Nan

2009-09-30

20

Nutritional immunity beyond iron: a role for manganese and zinc  

PubMed Central

Summary Vertebrates sequester iron from invading pathogens, and conversely, pathogens express a variety of factors to steal iron from the host. Recent work has demonstrated that in addition to iron, vertebrates sequester zinc and manganese both intracellularly and extracellularly to protect against infection. Intracellularly, vertebrates utilize the ZIP/ZnT families of transporters to manipulate zinc levels, as well as Nramp1 to manipulate manganese levels, respectively. Extracellularly, the S100 protein calprotectin sequesters manganese and potentially zinc to inhibit microbial growth. To circumvent these defenses, bacteria possess high affinity transporters to import specific nutrient metals. Limiting the availability of zinc and manganese as a mechanism to defend against infection expands the spectrum of nutritional immunity and further establishes metal sequestration as a key defense against microbial invaders.

Kehl-Fie, Thomas E.; Skaar, Eric P.

2009-01-01

21

The Interaction of Mitochondrial Iron with Manganese Superoxide Dismutase*  

PubMed Central

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

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

2009-01-01

22

Manganese  

SciTech Connect

Manganese (Mn) is a hard, brittle, gray-white transition metal, with the most numerous oxidation states of the elements in the first series of the Periodic Table. Since the manganese atom can donate up to seven electrons from its outer two shells, manganese compounds exist with valences from -3 to +7, the most common being +2, +4, and +7. Due to its sulfur-fixing, deoxidizing, and alloying properties, as well as its low cost, the principal commercial application for manganese is in iron and steel production. Manganese is also employed in non-ferrous metallurgy, batteries and chemical processes. Although potentially harmful to the respiratory and nervous systems, manganese is an essential element for animals and humans, and a micronutrient for plants.

Major-Sosias, M.A.

1996-10-01

23

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

24

Manganese and Iron Oxidation During Benthic Oxygenic Photosynthesis  

NASA Astrophysics Data System (ADS)

The effect of benthic oxygenic photosynthesis on sediment-water fluxes of manganese and iron was studied for an intertidal sediment. Undisturbed sediments were incubated at an incident surface irradiance of 250 ?E m -2 s -1at 26 °C. Oxygenic photosynthesis was selectively inhibited by adding [3-(3,4-dichloro)-1,1-dimethyl-urea] (DCMU). Benthic fluxes were determined experimentally from the change in manganese and iron concentrations in the overlying water, and were predicted from the pore water concentration gradients at the sediment-water interface assuming molecular diffusion as the transport mechanism. The experimental fluxes of manganese and iron in DCMU-treated cores amounted to -0·84 and -0·59 mmol m -2day -1, respectively, and were directed from the sediment towards the overlying water. In the control cores, showing high rates of benthic oxygenic photosynthesis, the fluxes of manganese and iron were directed towards the sediment, 0·06 and 0·01 mmol m -2day -1, respectively. Mass balances for the 0·1-0·14 cm thick oxic zone, calculated from the experimental fluxes and the predicted fluxes, suggest a minimum areal reoxidation of 0·6 mmol m -2day -1for manganese and of 0·48 mmol m -2day -1for iron in cores showing benthic photosynthesis. The estimated turnover times for dissolved Mn 2+and dissolved Fe 2+in the oxic surface layer during benthic photosynthesis were 0·8 and 0·25 h, respectively. Sediment oxygen microprofiles and the sediment pH profiles suggest that chemical precipitation and reoxidation dominates the retention of manganese and iron during benthic oxygenic photosynthesis in shallow intertidal sediments.

Epping, E. H. G.; Schoemann, V.; de Heij, H.

1998-12-01

25

Elements of the iron and manganese cycles in Lake Baikal  

USGS Publications Warehouse

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

Granina, L. Z.; Callender, E.

2007-01-01

26

Manganese and iron oxidation by fungi isolated from building stone  

Microsoft Academic Search

Acid and nonacid generating fungal strains isolated from weathered sandstone, limestone, and granite of Spanish cathedrals were assayed for their ability to oxidize iron and manganese. In general, the concentration of the different cations present in the mineral salt media directly affected Mn(IV) oxide formation, although in some cases, the addition of glucose and nitrate to the culture media was

M. A. Torre; G. Gomez-Alarcon

1994-01-01

27

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

28

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

29

Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide  

NASA Astrophysics Data System (ADS)

This work compares and models the adsorption of selenium and other anions on a neutral to alkaline surface (amorphous iron oxyhydroxide) and an acidic surface (manganese dioxide). Selenium adsorption on these oxides is examined as a function of pH, particle concentration, oxidation state, and competing anion concentration in order to assess how these factors might influence the mobility of selenium in the environment. The data indicate that 1) amorphous iron oxyhydroxide has a greater affinity for selenium than manganese dioxide, 2) selenite [Se(IV)] adsorption increases with decreasing pH and increasing particle concentration and is stronger than selenate [Se(VI)] adsorption on both oxides, and 3) selenate does not adsorb on manganese dioxide. The relative affinity of selenate and selenite for the oxides and the lack of adsorption of selenate on a strongly acidic surface suggests that selenate forms outer-sphere complexes while selenite forms inner-sphere complexes with the surfaces. The data also indicate that the competition sequence of other anions with respect to selenite adsorption at pH 7.0 is phosphate > silicate > molybdate > fluoride > sulfate on amorphous iron oxyhydroxide and molybdate ? phosphate > silicate > fluoride > sulfate on manganese dioxide. The adsorption of phosphate, molybdate, and silicate on these oxides as a function of pH indicates that the competition sequences reflect the relative affinities of these anions for the surfaces. The Triple Layer surface complexation model is used to provide a quantitative description of these observations and to assess the importance of surface site heterogeneity on anion adsorption. The modeling results suggest that selenite forms binuclear, innersphere complexes with amorphous iron oxyhydroxide and monodentate, inner-sphere complexes with manganese dioxide and that selenate forms outer-sphere, monodentate complexes with amorphous iron oxyhydroxide. The heterogeneity of the oxide surface sites is reflected in decreasing equilibrium constants for selenite with increasing adsorption density and both experimental observations and modeling results suggest that manganese dioxide has fewer sites of higher energy for selenite adsorption than amorphous iron oxyhydroxide. Modeling and interpreting the adsorption of phosphate, molybdate, and silicate on the oxides are made difficult by the lack of constraint in choosing surface species and the fact that equally good fits can be obtained with different surface species. Finally, predictions of anion competition using the model results from single adsorbate systems are not very successful because the model does not account for surface site heterogeneity. Selenite adsorption data from a multi-adsorbate system could be fit if the equilibrium constant for selenite is decreased with increasing anion adsorption density.

Balistrieri, Laurie S.; Chao, T. T.

1990-03-01

30

Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide  

USGS Publications Warehouse

This work compares and models the adsorption of selenium and other anions on a neutral to alkaline surface (amorphous iron oxyhydroxide) and an acidic surface (manganese dioxide). Selenium adsorption on these oxides is examined as a function of pH, particle concentration, oxidation state, and competing anion concentration in order to assess how these factors might influence the mobility of selenium in the environment. The data indicate that 1. 1) amorphous iron oxyhydroxide has a greater affinity for selenium than manganese dioxide, 2. 2) selenite [Se(IV)] adsorption increases with decreasing pH and increasing particle concentration and is stronger than selenate [Se(VI)] adsorption on both oxides, and 3. 3) selenate does not adsorb on manganese dioxide. The relative affinity of selenate and selenite for the oxides and the lack of adsorption of selenate on a strongly acidic surface suggests that selenate forms outer-sphere complexes while selenite forms inner-sphere complexes with the surfaces. The data also indicate that the competition sequence of other anions with respect to selenite adsorption at pH 7.0 is phosphate > silicate > molybdate > fluoride > sulfate on amorphous iron oxyhydroxide and molybdate ??? phosphate > silicate > fluoride > sulfate on manganese dioxide. The adsorption of phosphate, molybdate, and silicate on these oxides as a function of pH indicates that the competition sequences reflect the relative affinities of these anions for the surfaces. The Triple Layer surface complexation model is used to provide a quantitative description of these observations and to assess the importance of surface site heterogeneity on anion adsorption. The modeling results suggest that selenite forms binuclear, innersphere complexes with amorphous iron oxyhydroxide and monodentate, inner-sphere complexes with manganese dioxide and that selenate forms outer-sphere, monodentate complexes with amorphous iron oxyhydroxide. The heterogeneity of the oxide surface sites is reflected in decreasing equilibrium constants for selenite with increasing adsorption density and both experimental observations and modeling results suggest that manganese dioxide has fewer sites of higher energy for selenite adsorption than amorphous iron oxyhydroxide. Modeling and interpreting the adsorption of phosphate, molybdate, and silicate on the oxides are made difficult by the lack of constraint in choosing surface species and the fact that equally good fits can be obtained with different surface species. Finally, predictions of anion competition using the model results from single adsorbate systems are not very successful because the model does not account for surface site heterogeneity. Selenite adsorption data from a multi-adsorbate system could be fit if the equilibrium constant for selenite is decreased with increasing anion adsorption density. ?? 1990.

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

1990-01-01

31

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

Microsoft Academic Search

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

Jeffrey C. Cornwell; George W. Kipphut

1992-01-01

32

SEPARATION OF CADMIUM FROM URANIUM, COBALT, NICKEL, MANGANESE, ZINC, COPPER, TITANIUM, AND OTHER ELEMENTS BY CATION EXCHANGE CHROMATOGRAPHY  

Microsoft Academic Search

A study of the distribution curves of cations with AG 5OW-X8 resin in ; hydrochloric acid showed that most cations are adsorbed strongly from 0.5 N ; hydrochloric acid, while cadmium is not. This fact was used to develop a cation ; exchange chromatographic procedure to separate cadmium from uranium, cobalt, ; nickel, manganese, zinc, copper, and titanium. Other cations

F. W. E. Strelow; F. W. E

1960-01-01

33

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

34

Simultaneous Biological Removal of Iron, Manganese and Ammonium Nitrogen in Simulated Groundwater Using Biological Aerated Filter  

Microsoft Academic Search

The simultaneous biological removal of iron, manganese and ammonia from simulated contaminated groundwater was studied by biological aerated filter using dual layer ceramsite as support material in the lab. The system was simultaneously inoculated with iron and manganese oxidizing bacteria, nitrifying bacteria and nitrification bacteria and a series of experiments was performed to investigate simultaneous removal performance of the filter.

Tang Yulan; He Juanjuan; Ma Xingguan; You Kun; Zhang Rongxin; Wu Weibing; Fu Jinxiang; Zhao Haipeng

2010-01-01

35

[Chronic bronchitis in workers producing iron-manganese alloys].  

PubMed

Out of 205 workers employed at production of iron-manganese alloys in 35.6% chronic bronchitis (CB) was found. In 11.1% CB occurred in non-smokers, and in 42.5% in cigarette smokers. The incidence of CB was increasing with the number of smoked cigarettes, and in the workers with smoking index < or = 10 it was 53.3% (smoking index = number of cigarette packs smoked daily (1 pack = 20 cigarettes) x number of smoking years). No influence of occupation environment was found on the incidence of CB in the studied workers. PMID:7941575

Misiewicz, A; Radwan, K; Karmoli?ski, M; Dziewit, T; Matysek, A

1994-04-01

36

Growth and characterization of gel grown pure and mixed iron-manganese levo-tartrate crystals  

Microsoft Academic Search

Several applications of iron tartrate and manganese tartrate compounds are reported in the literature. In the present investigation,\\u000a we have grown pure and mixed iron (II)-manganese levo-tartrate crystals by single diffusion gel growth technique. Crystals\\u000a with spherulitic morphology were harvested. The colouration of the crystals changed from black to pinkish brown upon increasing\\u000a the content of manganese in the crystals.

S. J. Joshi; B. B. Parekh; K. D. Vohra; M. J. Joshi

2006-01-01

37

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

SciTech Connect

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

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

2012-02-28

38

Iron and iron/manganese ratio in forage from Icelandic sheep farms: relation to scrapie  

PubMed Central

This study was undertaken in order to examine whether any connection existed between the amounts of iron in forage and the sporadic occurrence of scrapie observed in certain parts of Iceland. As iron and manganese are considered antagonistic in plants, calculation of the Fe/Mn ratios was also included by using results from Mn determination earlier performed in the same samples. Forage samples (n = 170) from the summer harvests of 2001–2003, were collected from 47 farms for iron and manganese analysis. The farms were divided into four categories: 1. Scrapie-free farms in scrapie-free areas (n = 9); 2. Scrapie-free farms in scrapie-afflicted areas (n = 17); 3. Scrapie-prone farms (earlier scrapie-afflicted, restocked farms) (n = 12); 4. Scrapie-afflicted farms (n = 9). Farms in categories 1 and 2 are collectively referred to as scrapie-free farms. The mean iron concentration in forage samples from scrapie-afflicted farms was significantly higher than in forage samples from farms in the other scrapie categories (P = 0.001). The mean Fe/Mn ratio in forage from scrapie-afflicted farms was significantly higher than in forage from scrapie-free and scrapie-prone farms (P < 0.001). The results indicated relative dominance of iron over manganese in forage from scrapie-afflicted farms as compared to farms in the other categories. Thus thorough knowledge of iron, along with manganese, in soil and vegetation on sheep farms could be a pivot in studies on sporadic scrapie.

Gudmundsdottir, KB; Sigurdarson, S; Kristinsson, J; Eiriksson, T; Johannesson, T

2006-01-01

39

Distributions of Manganese, Iron, and Manganese-Oxidizing Bacteria In Lake Superior Sediments of Different Organic Carbon Content  

NASA Technical Reports Server (NTRS)

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 bacteria and Mn oxidizing bacteria, determined by plating and counting, showed that aerobic (and facultatively aerobic) heterotrophic bacteria were present at the highest concentrations near the surface and decreased steadily with depth, while Mn oxidizing bacteria were concentrations 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, Laurie L.; Nealson, Kenneth H.

1989-01-01

40

Iron nutrition affects cadmium accumulation and toxicity in rice plants  

Microsoft Academic Search

The effect of iron (Fe) nutrition on cadmium (Cd) toxicity and accumulation in rice plants was studied using a hydroponic\\u000a system. The inhibitory effect of Cd on plant growth and chlorophyll content (SPAD value) was dependent on Fe level and the\\u000a genotype. Malondialdehyde (MDA) content in leaves and roots was not much affected by an increased Cd stress at 0.171 mg l?1

Guosheng Shao; Mingxue Chen; Weixia Wang; Renxiang Mou; Guoping Zhang

2007-01-01

41

Distribution of iron, copper and manganese in the Arabian Sea  

NASA Astrophysics Data System (ADS)

The distribution of iron, copper and manganese was studied on a zonal transect of the Arabian Sea during the SW monsoon in 2007. The distribution of metals in the eastern and western ends of the transect are completely different, with concentrations of Fe and Mn higher in the east, but copper much higher in the west. Redox cycling in the east, and enhanced ventilation in the west contributes to these processes. It seems likely that blooms of Phaeocystis sp. contribute to the pronounced surface depletion and oxicline regeneration we observe, particularly for copper. The results are very different than similar surveys in the Peru upwelling, indicating controls by very different processes. These results have important implications for carbon and nitrogen cycling, particularly for processes mediated by key Cu and Fe metalloenzymes.

Moffett, James

2014-05-01

42

Voltammetric determination of arsenic in high iron and manganese groundwaters.  

PubMed

Determination of the speciation of arsenic in groundwaters, using cathodic stripping voltammetry (CSV), is severely hampered by high levels of iron and manganese. Experiments showed that the interference is eliminated by addition of EDTA, making it possible to determine the arsenic speciation on-site by CSV. This work presents the CSV method to determine As(III) in high-iron or -manganese groundwaters in the field with only minor sample treatment. The method was field-tested in West-Bengal (India) on a series of groundwater samples. Total arsenic was subsequently determined after acidification to pH 1 by anodic stripping voltammetry (ASV). Comparative measurements by ICP-MS as reference method for total As, and by HPLC for its speciation, were used to corroborate the field data in stored samples. Most of the arsenic (78±0.02%) was found to occur as inorganic As(III) in the freshly collected waters, in accordance with previous studies. The data shows that the modified on-site CSV method for As(III) is a good measure of water contamination with As. The EDTA was also found to be effective in stabilising the arsenic speciation for longterm sample storage at room temperature. Without sample preservation, in water exposed to air and sunlight, the As(III) was found to become oxidised to As(V), and Fe(II) oxidised to Fe(III), removing the As(V) by adsorption on precipitating Fe(III)-hydroxides within a few hours. PMID:21807202

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

2011-09-15

43

Cadmium and Manganese Flux in Eelgrass 'Zostera marina. I. Modelling Dynamics of Metal Release from Labelled Tissues.  

National Technical Information Service (NTIS)

Release of cadmium and manganese radionuclides from eelgrass leaves and root-rhizomes into seawater and seawater plus 0.0001 disodium ethylenediaminetetraacetate (EDTA) was monitored over periods of 6 h following incubations of 1 to 98 h. Flux of both iso...

W. F. Penello B. H. Brinkhuis

1980-01-01

44

Chemical Characterization of Transition Metal Spinel-Type Oxides. Part 2. Manganese-Chromium-Iron Spinels.  

National Technical Information Service (NTIS)

Spinel oxides of the type formed on Advanced Gas Cooled Reactor cladding contain manganese, chromium, and iron. A range of standard spinels containing these metals have been prepared by solid state reaction of the appropriate single oxides at temperatures...

G. C. Allen J. A. Jutson P. A. Tempest

1987-01-01

45

Interactions between iron, manganese, and the Al-Si eutectic in hypoeutectic Al-Si alloys  

Microsoft Academic Search

Sand-cast plates were used to determine the effect of iron and manganese concentrations on porosity levels in Al-9 pct Si-0.5\\u000a pct Mg alloys. Iron increased porosity levels. Manganese additions increased porosity levels in alloys with 0.1 pct Fe, but\\u000a reduced porosity in alloys with 0.6 and 1 pct Fe. Thermal analysis and quenching were undertaken to determine the effect of

C. M. Dinnis; J. A. Taylor; A. K. Dahle

2006-01-01

46

Iron monosulfide as a scavenger for dissolved hexavalent chromium and cadmium.  

PubMed

Iron sulfide minerals are common components of soil/sedimentary environments. Reactions near the surfaces of iron sulfides play important roles in metal retention, mobility, and bioavailability. A series of batch experiments was conducted to study the removal of aqueous chromium and cadmium by iron monosulfide. Hexavalent chromium was reduced to Cr(III) by iron monosulfide with simultaneous precipitation of chromium and iron oxyhydroxide. In contrast to chromium, the primary retention mechanism of cadmium by iron monosulfide was lattice exchange. Surface adsorption to iron monosulfide and precipitation with sulfide on the iron monosulfide surface also contributed to the removal of aqueous cadmium. New phases of both chromium and cadmium were confirmed with transmission electron microscopy. The solution pH was an important factor in this research; it can change particle surface charge and metal species, hence affecting the removal of chromium, but not cadmium. Ferrous ions without FeS exhibited less Cr(VI) removal than with FeS, which might be owing to sulfides from FeS and the existence of the solid phase. Iron monosulfide exhibited higher removal efficiency for chromium and cadmium than zero valent iron and other iron oxide minerals, and the synergistic effect of ferrous iron and sulfide appeared to cause this result. PMID:18844124

Jo, S; Lee, J Y; Kong, S H; Choi, J; Park, J W

2008-09-01

47

Modes of iron-manganese mineralization on the bottom of Lake Baikal  

NASA Astrophysics Data System (ADS)

The investigation of the bottom of Lake Baikal carried out during the 2008 summer season by means of Mir manned deep-submergence vehicles resulted in the recovery of a series of sediments, ferruginous crusts, and peculiar mineralized tubes several centimeters high and up to 2-6 cm in diameter. According to the scanning electron investigation, these formations consist mainly of the enclosing sediment particles and biogcnie silica cemented by iron and minor manganese hydroxides. The chemical composition of the tubes is similar to both that of the enclosing sediments and slightly ferruginous crusts and nodules, but the tubes and crusts are somewhat richer relative to the sediments in some microelements, namely, arsenic, cadmium, and uranium. In general, the structure and composition of these tubes reminds one of the worm tubes common in the sediments of a number of seas. The investigation of the rare earth elements in some samples or ferruginous formations and sediments revealed a positive europium anomaly, which might be related to either the composition of the surrounding continental magmatic rocks or to the influence of hypothetical hydrothermal solutions.

Baturin, G. N.; Peresypkin, V. I.; Zhegallo, E. A.

2011-06-01

48

Iron, Manganese and Copper Release from Synthetic Hydroxyapatite  

NASA Technical Reports Server (NTRS)

Kinetic stir-flow dissolution experiments were performed on iron- (Fe-SHA), manganese- (Mn-SHA), and copper- (Cu-SHA) containing synthetic hydroxyapatites. Solution treatments consisted of de-ionized water, citric acid and DTPA. Initially, Mn concentrations were higher than Cu concentrations and Fe concentrations were the lowest in all treatments. At later times Mn and Cu concentrations dropped in the DTPA treatment while Fe rose to the concentration similar to Mn and Cu. At all times, metal release concentrations in the water and citric acid treatments followed the trend of Mn>Cu>Fe. Rietveld analysis of x-ray diffraction data and ^31P NMR indicated that the metals substituted for Ca in the SHA structure. However, EPR data suggested that a metal (hydr)oxide phase existed either on the SHA surface or between the SHA crystallites. The metal concentration trend of Mn>Cu>Fe suggested that the initial solution metal concentrations are dependent on the dissolution of (hydr)oxides from SHA surfaces or between SHA crystallites. Similar metal concentrations at later times in the DTPA experiments suggests that metal concentrations were controlled by the release of Mn, Cu, or Fe from the SHA structure.

Sutter, B.; Hossner, L. R.; Ming, Douglas W.

1999-01-01

49

Effect of aluminum on the hardness, friction coefficient, and wear resistance of austenitic manganese cast irons  

Microsoft Academic Search

1.Aluminum in amounts of 0.4–0.8% decreases the hardness, friction coefficient, and wear of austenitic manganese cast iron containing high concentrations of carbon in contact with lubricated and unlubricated quenched steel.2.The austenitic cast iron in contact with quenched steel has a considerably higher wear resistance and lower friction coefficient as compared to quenched steel on bronze.

V. B. Lyadskii

1964-01-01

50

[Acetylcholinesterase activity in erythrocytes of workers engaged in the production of iron-manganese alloys].  

PubMed

The activity of acetylcholinesterase in the red blood cells of metallurgy workers producing iron-manganese alloys was statistically less significant than the activity of this enzyme in the control group. Work tenure and smoking intensity, measured using the smoking index method did not significantly affect the acetylcholinesterase activity in the worker's red blood cells (smoking index = number of packs of cigarettes smoked per day x years of smoking; one pack = 20 cigarettes). The results may point to malfunctions of the erythrocytes membranes caused by harmful substances in iron works producing iron-manganese alloys. PMID:1635444

Misiewicz, A; Karmoli?ski, M

1992-01-01

51

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

52

Manganese-mitigation of cadmium toxicity to seedling growth of Phytolacca acinosa Roxb. is controlled by the manganese/cadmium molar ratio under hydroponic conditions.  

PubMed

Manganese (Mn) can interact with cadmium (Cd) in environments and influence the toxic effect of Cd on plants. However, few studies have investigated the relationship between the Mn/Cd ratio and plant Cd-toxicity along Cd concentrations. In this paper, we studied the effects of external Mn/Cd molar ratios (0, 10, 30, 50 and 60) on Cd toxicity in the Mn hyperaccumulator and Cd tolerant plant, Phytolacca acinosa Roxb., at three Cd levels (50, 100 and 200 ?M) under hydroponic conditions. Our result showed that seedling growth (y) under Cd stress was strongly positively related to the solution Mn/Cd molar ratio (SMCR). The relationship between the two variables under solution Cd concentrations was well explained by the linear regression model y=a+b1 (SMCR)+b2 (Solution-Cd). Increasing SMCR significantly reduced the Cd concentration and increased the Mn concentration in plant tissues. However, seedling growth was consistent with the shoot Mn/Cd molar ratio rather than with the Mn or Cd concentrations in plant tissues. At low levels of SMCR (e.g. 0 and 10), elevation of Mn distribution in shoot tissues might be a mechanism in P. acinosa seedlings to defend against Cd-toxicity. In comparison with low levels of SMCR, high levels of SMCR (e.g. 50 and 60) greatly alleviated lipid peroxidation and plant water-loss, and enhanced photosynthesis. However, the alleviated lipid peroxidation in the Mn-mitigation of Cd toxicity was likely to be the secondary effect resulting from the antagonism between Mn and Cd in the plant. PMID:24095921

Liu, Huimin; Zhang, Yuxiu; Chai, Tuanyao; Tan, Jinjuan; Wang, Jianwu; Feng, Shanshan; Liu, Geyu

2013-12-01

53

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

54

Role of iron in jejunal uptake of cadmium in the newborn rat  

SciTech Connect

There is evidence that suckling animals and children have a greater capacity for intestinal transport of both essential and nonessential metals than do adults of the species. It has also been observed in experiments using adult animals that the intestinal transport of iron and the nonessential metal cadmium interact with one another. In the study reported here, the influence of tissue iron status on jejunal uptake of cadmium was investigated in suckling, adolescent, and young adult rats using an in situ incubation technique. In the presence of 0.4 mM FeSO/sub 4/, intestinal uptake of cadmium was significantly decreased in 14-d-old pups. Access to an iron-deficient diet reduced tissue iron levels in 28- and 42-d-old but not in 14-d-old rats. Intestinal uptake of cadmium was significantly greater in 28- and 42-d-old rats placed on the iron-deficient diet but did not change in 14-d-old rats compared to controls. In suckling rats injected with iron dextran over a six-d period, a significant decrease in intestinal uptake of both cadmium and iron was observed compared to controls. The results of the present study suggest that intestinal cadmium transport in the suckling, as well as the adolescent and young adult rat, interacts with, at least in part, the pathway responsible for iron transport.

Leon, L.; Johnson, D.R.

1985-01-01

55

Some effects of oral ingestion of cadmium on zinc, copper, and iron metabolism.  

PubMed Central

Data are presented to show that ingestion of cadmium chloride by rats at low levels leads to alteration of zinc metabolism in the liver, even though the formation of metallothionein is not evident. A dose-response relationship between amount of cadmium ingested and degree of perturbation of zinc metabolism in liver was found. Oral cadmium was shown to cause emphysema and reduce pulmonary function in male rats; the effect was less severe or delayed in onset if dietary zinc concentration was high. Interference with copper and iron metabolism was shown to occur in rats given low levels of cadmium orally. Depression of copper and iron metabolism of the rat fetus was found to occur when dams received very low doses of cadmium during gestation, even though very little cadmium passed the placental barrier. Images FIGURE 1. a FIGURE 1. b FIGURE 2. a FIGURE 2. b

Petering, H G; Choudhury, H; Stemmer, K L

1979-01-01

56

Manganese: a transition metal protects nigrostriatal neurons from oxidative stress in the iron-induced animal model of parkinsonism.  

PubMed

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 a severe depletion of dopamine levels in the rat caudate nucleus. In contrast to iron's pro-oxidant effect, manganese (up to 30 nmol, i.n.) causes neither lipid peroxidation nor nigral injury/dopamine depletion. Manganese (1.05 to 4.2 nmol, i.n.) dose-dependently protected nigral neurons from iron-induced oxidative injury and dopamine depletion. Manganese also suppressed acute increase in dopamine turnover and contralateral turning behaviour induced by iron. In brain homogenates manganese (0 to 10 microM) concentration-dependently inhibited propagation of lipid peroxidation caused by iron (0 to 5 microM). Without the contribution of manganese-superoxide dismutase manganese was still effective in sodium azide and/or heat-pretreated brain homogenates. Surprisingly, iron but not manganese, catalysed the Fenton reaction or the conversion of hydrogen peroxide to hydroxyl radicals. The results indicate that iron and manganese are two transition metals mediating opposite effects in the nigrostriatal system, as pro-oxidant and antioxidant, respectively. In conclusion, intranigral infusion of iron, but not manganese, provides an animal model for studying the pathophysiological role of oxidant and oxidative stress in nigrostriatal degeneration and Parkinsonism. The present results further suggest that the atypical antioxidative properties of manganese may protect substantia nigra compacta neurons from iron-induced oxidative stress. PMID:9681949

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

1998-08-01

57

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

58

Some effects of oral ingestion of cadmium on zinc, copper, and iron metabolism  

Microsoft Academic Search

Several biological effects that reflect the interaction of cadmium and zinc when cadium is ingested by rats are described. Data from several reports and investigations show that the ingestion of low levels of cadmium by rats can cause alteration of zinc metabolism in the liver, emphysema, reduced pulmonary function, depression of copper and iron metabolism in the rat fetus, growth

H. G. Petering; H. Choudhury; K. L. Stemmer

1979-01-01

59

Occurrence and Distribution of Iron, Manganese, and Selected Trace Elements in Ground Water in the Glacial Aquifer System of the Northern United States  

USGS Publications Warehouse

Dissolved trace elements, including iron and manganese, are often an important factor in use of ground water for drinking-water supplies in the glacial aquifer system of the United States. The glacial aquifer system underlies most of New England, extends through the Midwest, and underlies portions of the Pacific Northwest and Alaska. Concentrations of dissolved trace elements in ground water can vary over several orders of magnitude across local well networks as well as across regions of the United States. Characterization of this variability is a step toward a regional screening-level assessment of potential human-health implications. Ground-water sampling, from 1991 through 2003, of the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey determined trace element concentrations in water from 847 wells in the glacial aquifer system. Dissolved iron and manganese concentrations were analyzed in those well samples and in water from an additional 743 NAWQA land-use and major-aquifer survey wells. The samples are from monitoring and water-supply wells. Concentrations of antimony, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, selenium, strontium, thallium, uranium, and zinc vary as much within NAWQA study units (local scale; ranging in size from a few thousand to tens of thousands of square miles) as over the entire glacial aquifer system. Patterns of trace element concentrations in glacial aquifer system ground water were examined by using techniques suitable for a dataset with zero to 80 percent of analytical results reported as below detection. During the period of sampling, the analytical techniques changed, which generally improved the analytical sensitivity. Multiple reporting limits complicated the comparison of detections and concentrations. Regression on Order Statistics was used to model probability distributions and estimate the medians and other quantiles of the trace element concentrations. Strontium and barium were the most frequently detected and usually were present in the highest concentrations. Iron and manganese were the next most commonly detected and next highest in concentrations. Iron concentrations were the most variable with respect to the range of variations (both within local networks and aquifer-wide) and with respect to the disparity between magnitude of concentrations (detections) and the frequency of samples below reporting limits (nondetections). Antimony, beryllium, cadmium, silver, and thallium were detected too infrequently for substantial interpretation of their occurrence or distributions or potential human-health implications. For those elements that were more frequently detected, there are some geographic patterns in their occurrence that primarily reflect climate effects. The highest concentrations of several elements were found in the West-Central glacial framework area (High Plains and northern Plains areas). There are few important patterns for any element in relation to land use, well type, or network type. Shallow land-use (monitor) wells had iron concentrations generally lower than the glacial aquifer system wells overall and much lower than major-aquifer survey wells, which comprise mostly private- and public-supply wells. Unlike those for iron, concentration patterns for manganese were similar among shallow land-use wells and major-aquifer survey wells. An apparent relation between low pH and relatively low concentrations of many elements, except lead, may be more indicative of the relatively low dissolved-solids content in wells in the Northeastern United States that comprise the majority of low pH wells, than of a pH dependent pattern. Iron and manganese have higher concentrations and larger ranges of concentrations especially under more reducing conditions. Dissolved oxygen and well depth were related to iron and manganese concentrations. Redox conditions also affect several trace elements such

Groschen, George E.; Arnold, Terri L.; Morrow, William S.; Warner, Kelly L.

2009-01-01

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) 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

61

Absorption of Manganese and Iron in a Mouse Model of Hemochromatosis  

PubMed Central

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

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

2013-01-01

62

Geological reconnaissance of some Uruguayan iron and manganese deposits in 1962  

USGS Publications Warehouse

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

Wallace, Roberts Manning

1976-01-01

63

The Constitution of Alloys of Iron and Manganese with Transition Elements of the First Long Period  

Microsoft Academic Search

Using metals of the highest purity, the constitutions of iron-rich and manganese-rich binary alloys with the sequence of elements Ti-V-Cr-(Mn, Fe)-Co-Ni-Cu have been investigated by specially accurate thermal analysis, supplemented by microscopical and X-ray work. The liquidus and solidus curves have been determined accurately, and also the forms of the A4 (gamma \\/delta ) transformations in the iron alloys, and

A. Hellawell; W. Hume-Rothery

1957-01-01

64

Oxidant Selection for the Treatment of Manganese (II), Iron (II), and Arsenic (III) in Groundwaters  

EPA Science Inventory

In order to comply with the United States Environmental Protection Agency?s (U.S. EPA?s) arsenic standard and the manganese and iron secondary maximum contaminant levels (MCLs) in water (10µg/L, 50µg/L, and 300µg/L, respectively), many Midwestern water utilities must add a strong...

65

Chesterton soil concretions: ilmenite and not iron-manganese cementing matrix.  

PubMed

Dark reddish-brown spherules are common in soils of the Chesterton soil series of a high marine terrace in southern California. The spherules are concretionary in structure and are bound by ilmenite rather than by an iron-manganese complex. The spherules have been mislabeled both with respect to structure and mineralogy. PMID:17790010

White, K L

1979-06-01

66

Phytoavailability and Fractions of Iron and Manganese in Calcareous Soil Amended with Composted Urban Wastes  

Microsoft Academic Search

Little is known about the effects of applying composted urban wastes on the phytoavailability and distribution of iron (Fe) and manganese (Mn) among chemical fractions in soil. In order to study this concern several experiments in pots containing calcareous soil were carried out. The received treatments by adding separately two rates (20 and 80 Mg ha) of municipal solid waste

FRANCISCO GALLARDO-LARA; MARIANO AZCÓN; ALFREDO POLO

2006-01-01

67

Iron Deficient and Manganese Supplemented Diets Alter Metals and Transporters in the Developing Rat Brain  

Microsoft Academic Search

Manganese (Mn) neurotoxicity in adults can result in psycho- logical 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

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

2007-01-01

68

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

Microsoft Academic Search

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

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

2010-01-01

69

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

Microsoft Academic Search

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

Gaurav Jain

2005-01-01

70

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

Microsoft Academic Search

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

Maneesha P. Ginige; Jason Wylie; Jason Plumb

2011-01-01

71

Fast method for the determination of copper, manganese and iron in seafood samples  

Microsoft Academic Search

A slurry sampling flame atomic absorption spectrometric method is proposed for the determination of copper, manganese and iron in oysters (Crassostrea rhizophora), clams (Anomalocardia brasiliana) and mussels (Mytella guiyanensis; Perna perna). Optimization was carried out using univariate methodology involving the following variables: nature and concentration of the acid solution for slurry preparation, sonication time and sample mass. The optimized conditions

Erik G. P. da Silva; Vanessa Hatje; Walter N. L. dos Santos; Letícia M. Costa; Ana R. A. Nogueira; Sérgio L. C. Ferreira

2008-01-01

72

Manganese  

MedlinePLUS

... the body, including processing of cholesterol, carbohydrates, and protein. It might also be involved in bone formation. ... Antibiotics (Quinolone antibiotics)Manganese might decrease how much ... antibiotics might decrease the effectiveness of some antibiotics. To avoid ...

73

Interactions between iron, manganese, and the Al-Si eutectic in hypoeutectic Al-Si alloys  

NASA Astrophysics Data System (ADS)

Sand-cast plates were used to determine the effect of iron and manganese concentrations on porosity levels in Al-9 pct Si-0.5 pct Mg alloys. Iron increased porosity levels. Manganese additions increased porosity levels in alloys with 0.1 pct Fe, but reduced porosity in alloys with 0.6 and 1 pct Fe. Thermal analysis and quenching were undertaken to determine the effect of iron and managanese on the solidification of the Al-Si eutectic. At high iron levels, the presence of large ?-Al5FeSi was found to reduce the number of eutectic nucleation events and increase the eutectic grain size. The preferential formation of ?-Al15Mn3Si2 upon addition of manganese reversed these effects. It is proposed that this interaction is due to ?-Al5FeSi and the Al-Si eutectic having common nuclei. Porosity levels are proposed to be controlled by the eutectic grain size and the size of the iron-bearing intermetallic particles rather than the specific intermetallic phase that forms.

Dinnis, C. M.; Taylor, J. A.; Dahle, A. K.

2006-11-01

74

Iron Deficiency Increases Blood Cadmium Levels in Adolescents Surveyed in KNHANES 2010-2011.  

PubMed

Discrepancies have been reported in the relationships between iron and cadmium concentrations. The distribution of blood cadmium concentrations was assessed in a representative sample of Korean adolescents participating in the Korean National Health and Nutritional Examination Survey (KNHANES) 2010-2011, and the association between blood cadmium and iron concentrations was determined. This study was based on data from KNHANES, in which a rolling sampling design was used to perform a complex, stratified, multistage probability cluster survey of a representative sample of the noninstitutionalized civilian population in South Korea. Serum ferritin was categorized as low (<15.0 ?g/L), low normal (15.0-<30.0 ?g/L for girls, 15.0-<50.0 ?g/L for boys), or normal (?30.0 ?g/L for girls, ?50.0 ?g/L for boys), and the association between serum ferritin and blood cadmium concentrations was assessed after adjustment for various demographic and lifestyle factors. The geometric mean (GM) of blood cadmium was significantly higher among both boys and girls in the low than in the normal ferritin group. After controlling for covariates, multiple regression analysis showed that blood cadmium concentration was inversely correlated with serum ferritin concentration in both boys and girls. In conclusion, iron deficiency is associated with increased blood cadmium concentrations in a representative sample of Korean adolescents, as evaluated in KNHANES. PMID:24797808

Lee, Byung-Kook; Kim, Suk Hwan; Kim, Nam-Soo; Ham, Jung-O; Kim, Yangho

2014-06-01

75

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

SciTech Connect

The intraperitoneal administration of methylcyclopentadienyl manganese tricarbonyl (MMT) and cyclophosphamide, exposure to an aerosol of cadmium chloride, intravenous administration of oleic acid, and intratracheal instillation of bleomycin to young female BALB/c mice or CD/CR rats result in acute lung injury. Pulmonary morphology and lung collagen content were examined in animals treated with these chemicals alone or in combination with an elevated oxygen concentration (80%) in the inspired air. In mice, the development of fibrosis could be significantly enhanced if animals treated with MMT, cadmium chloride, cyclophosphamide, or bleomycin were exposed to 80% oxygen immediately following exposure to these agents. In rats only cyclophosphamide- and bleomycin-induced acute lung injury was potentiated by hyperoxia, resulting in significant enhancement of lung collagen content. The pathogenesis responsible for this differential species response of pulmonary injury to hyperoxia remains to be investigated.

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

1983-01-01

76

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

PubMed Central

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

Wang, Dixin; Du, Xuqin; Zheng, Wei

2014-01-01

77

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

PubMed Central

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

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

2012-01-01

78

Microwave Resonance and Relaxation of Excess-Iron Manganese Ferrites  

Microsoft Academic Search

FMR measurements at 9.3 GHz have been made on single crystal disks of manganese ferrites with resistivities of the order of 0.1 \\\\varOmegacm (300 K), for various values of thickness. Comparison of the data with calculated absorption formulae indicates that an appreciable influence of skin depth effect remains until the thickness becomes as small as about 40 mum. This means

Yoshiyuki Watanabe

1973-01-01

79

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

PubMed Central

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

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

2006-01-01

80

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

USGS Publications Warehouse

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

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

1991-01-01

81

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

82

Synthesis, characterisation and catalytic evaluation of iron–manganese mixed oxide pillared clay for VOC decomposition reaction  

Microsoft Academic Search

A series of iron and manganese mixed oxide pillared clay with varying manganese to iron ratio has been successfully synthesized. Prepared materials were characterized by low angle XRD, TG\\/DTA, hydrogen TPR and nitrogen adsorption desorption experiment. All the materials were found to be thermally stable up to 500°C having basal spacing ?16.5?. Surface area and pore volume increases with the

T. Mishra; P. Mohapatra; K. M. Parida

2008-01-01

83

Topologically constrained manganese(III) and iron(III) complexes of two cross-bridged tetraazamacrocycles.  

PubMed

A family of Mn3+ and Fe3+ complexes of 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (1) and 4,10-dimethyl-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane (2) has been prepared by the chemical oxidation of the divalent manganese and iron analogues. The ligands are ethylene cross-bridged tetraazamacrocycles derived from cylam and cyclen, respectively. The synthesis and characterization of these complexes, including X-ray crystal structure determinations, are described. The structural evidence demonstrates that the tetradentate ligands enforce distorted octahedral geometries on the metal ions, with two cis sites occupied by labile ligands. Magnetic measurements reveal that the complexes are high spin with typical magnetic moments. Cyclic voltammetry shows reversible redox processes for the Fe3+/Fe2+ couples of the iron(III) complexes, while Mn3+/Mn2+ and Mn4+/Mn3+ couples were observed for the complexes with manganese(III). The manganese chemistry of 1 was studied in depth. The dichloro manganese(III) cation of 1 undergoes facile ligand substitution reactions at the labile, monodentate sites, for example substituting azide for chloride ligands. Air oxidation of the dichloro complex of Mn (1)2+ in basic solution does not give the expected mu-oxo dimeric product common to manganese. Instead, an unusual manganese(III)-OH complex has been isolated from this reaction and structurally characterized. A similar reaction under slightly different conditions gives a putative MnIII(OH)2 complex that metathesizes to MnIII(OMe)2 upon recrystallization from methanol. PMID:11209599

Hubin, T J; McCormick, J M; Alcock, N W; Busch, D H

2001-01-29

84

Some observations on the interaction of zinc, copper, and iron metabolism in lead and cadmium toxicity.  

PubMed Central

A brief review of the literature indicates that nutritional deficiencies have been shown to increase the absorption and toxicity of orally ingested lead and cadmium. Results from recent studies indicates that low level oral ingestion of cadmium and lead perturbs the metabolism of zinc, copper, and iron and that these changes may be the earliest manifestation of the toxicity of lead and cadmium. The significance of these findings reveals itself in two ways: namely, that toxicologic investigations of lead and cadmium, whether experimental or clinical, must be based on a definitive consideration of the nutritional status of animals or people, and, secondly, that the preventive role of nutrition, especially that of trace metal intakes, must be taken seriously when establishing measures for reducing, eliminating, or combatting the toxic effects of widespread exposure to lead and cadmium in humans.

Petering, H G

1978-01-01

85

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

PubMed Central

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

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

2014-01-01

86

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

87

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

PubMed Central

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

2011-01-01

88

Cadmium Accumulation and Its Effects on Uptake of Micronutrients in Indian Mustard [Brassica juncea (L.) Czern.] Grown in a Loamy Sand Soil Artificially Contaminated with Cadmium  

Microsoft Academic Search

A pot experiment was conducted in a greenhouse to evaluate the effects of different levels of cadmium (Cd) on Cd accumulation and their effects on uptake of micronutrients in Indian mustard [Brassica juncea (L.) Czern.]. Cadmium accumulation in shoots and interactions among other metals [manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn)] were investigated. Ten levels of Cd ranging

R. Sikka; V. Nayyar

2012-01-01

89

Sulfated zirconia and iron- and manganese-promoted sulfated zirconia: do they protonate alkanes?  

Microsoft Academic Search

Because of their high activities for alkane conversion, sulfated zirconia and iron- and manganese-promoted sulfated zirconia\\u000a have been the objects of much recent attention as a possible next generation of solid acid catalysts for alkane conversion.\\u000a These catalysts have been suggested to be superacidic on the basis of measurements with adsorbed Hammett indicator bases,\\u000a but published data determined with other

T.-K. Cheung; B. C. Gates

1998-01-01

90

Production of bare argon, manganese, iron and nickel nuclei in the Dresden EBIT  

Microsoft Academic Search

The production of highly charged argon, manganese, iron and nickel ions in a room-temperature electron beam ion trap (EBIT), the Dresden EBIT, has been investigated by means of energy dispersive X-ray spectroscopy of the direct excitation (DE) and radiative recombination (RR) processes. To derive the charge state distributions of the ions in the trap, direct excitation and radiative recombination cross-sections

U. Kentsch; G. Zschornack; F. Großmann; V. P. Ovsyannikov; F. Ullmann; S. Fritzsche; A. Surzhykov

2002-01-01

91

Effect of manganese on the transformation of austenite in white chromium cast irons  

Microsoft Academic Search

1.When the manganese content is raised from 0.22 to 5.2% in chromium cast iron (12–14% Cr), the rate of the isothermal transformation decreases both in the pearlitic and intermediate ranges, the transformation temperature range becoming narrower, while the temperature where the stability of austenite is lowest decreases.The temperature at the start of the martensitic transformation also decreases and the amount

E. V. Rozhkova; M. E. Garber; I. I. Tsypin

1981-01-01

92

Microbial DNA extraction and analyses of soil iron–manganese nodules  

Microsoft Academic Search

Iron–manganese (Fe–Mn) nodules and concretions are soil new growth, reflecting soil environmental conditions during their formation. Bacteria play a dominant role in the oxidation of dissolved Mn(II) in aqueous systems and the formation of marine and freshwater Fe–Mn nodules. However, the role and significance of bacteria in soil Fe–Mn nodule formation have not been well recognized. In this paper, microbial

Li-Mei Zhang; Fan Liu; Wen-Feng Tan; Xiong-Han Feng; Yong-Guan Zhu; Jizheng He

2008-01-01

93

Copper, Chromium, Manganese, Iron, Nickel, and Zinc Levels in Biological Samples of Diabetes Mellitus Patients  

Microsoft Academic Search

There is accumulating evidence that the metabolism of several trace elements is altered in diabetes mellitus and that these\\u000a nutrients might have specific roles in the pathogenesis and progress of this disease. The aim of present study was to compare\\u000a the level of essential trace elements, chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn) in

Tasneem Gul Kazi; Hassan Imran Afridi; Naveed Kazi; Mohammad Khan Jamali; Mohammad Bilal Arain; Nussarat Jalbani; Ghulam Abbas Kandhro

2008-01-01

94

Regional distribution of manganese, iron, copper, and zinc in the rat brain during development  

Microsoft Academic Search

Manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn) concentrations were determined in the brain regions of normal 1-, 3-, 5-, 7-, 14-, 21-, 42-, 77-, and 147-day-old Wistar rats using inductively coupled plasma mass spectrometry (ICP-MS), and their maps were illustrated in color to visually compare the distribution of the elements at various stages of the growth process. Sagittal

Tohru Tarohda; Masayoshi Yamamoto; Ryohei Amamo

2004-01-01

95

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

96

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

97

Hydrogenation of carbon monoxide over coprecipitated iron-manganese catalysts in a pseudo slurry reactor  

SciTech Connect

The hydrogenation of carbon monoxide to produce low-molecular-weight olefins has been investigated over unsupported iron-manganese catalysts with an approximate manganese-to-iron atomic ratio of 2:100. Temperature distributions in the following reactor modes have been studied: a conventional dense-bed reactor; a dense-bed trickle flow reactor; a dense-bed, pseudo slurry reactor; a diluted-bed reactor; a diluted-bed trickle flow reactor; and a diluted-bed, pseudo slurry reactor. A nearly isothermal temperature distribution was observed in the diluted-bed, pseudo slurry reactor. The n-hexadecane was determined to be a suitable heat transfer liquid for the diluted-bed pseudo slurry operation. The hydrogenation of carbon monoxide in a diluted-bed reactor over coprecipitated iron-manganese catalysts obeys the Schulz-Flory weight distribution law for hydrocarbons having a carbon number of up to 15. A higher chain growth probability was observed for hydrocarbons with carbon numbers greater than 15. A complete process variable investigation was conducted in the diluted-bed reactor and in the diluted-bed, pseudo slurry reactor using n-hexadecane as the heat transfer liquid. The process variables investigated were reaction temperature, reactor pressure, H/sub 2//CO ratio, and reactant gas space velocity. The results of this investigation agreed with the data reported in the literature.

Tai, W.P.

1983-01-01

98

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

NASA Technical Reports Server (NTRS)

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

Nealson, K. H.; Saffarini, D.

1994-01-01

99

Lead, chromium, tin, iron and cadmium in foods in welded cans.  

PubMed

The levels of lead, chromium, tin, iron and cadmium in fruit and vegetables in welded tinplate cans were determined by atomic absorption spectrophotometry. The levels found were compared with those in foods in soldered tinplate cans and fresh foods. The results show that the lead levels in foods in welded cans were much lower than those in similar foods in soldered cans. Foods in unlacquered welded cans contain much more lead, chromium and tin than foods in lacquered welded cans. The cadmium and iron levels in canned fruit and vegetables in welded cans were similar to those found in the corresponding fresh foods. PMID:3653455

Jorhem, L; Slorach, S

1987-01-01

100

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

PubMed

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

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

2014-01-01

101

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

PubMed Central

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

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

2014-01-01

102

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

NASA Astrophysics Data System (ADS)

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

Pakhomova, Svetlana; Yakushev, Evgeniy

2010-05-01

103

OPT3 Is a Phloem-Specific Iron Transporter That Is Essential for Systemic Iron Signaling and Redistribution of Iron and Cadmium in Arabidopsis[W][OPEN  

PubMed Central

Iron is essential for both plant growth and human health and nutrition. Knowledge of the signaling mechanisms that communicate iron demand from shoots to roots to regulate iron uptake as well as the transport systems mediating iron partitioning into edible plant tissues is critical for the development of crop biofortification strategies. Here, we report that OPT3, previously classified as an oligopeptide transporter, is a plasma membrane transporter capable of transporting transition ions in vitro. Studies in Arabidopsis thaliana show that OPT3 loads iron into the phloem, facilitates iron recirculation from the xylem to the phloem, and regulates both shoot-to-root iron signaling and iron redistribution from mature to developing tissues. We also uncovered an aspect of crosstalk between iron homeostasis and cadmium partitioning that is mediated by OPT3. Together, these discoveries provide promising avenues for targeted strategies directed at increasing iron while decreasing cadmium density in the edible portions of crops and improving agricultural productivity in iron deficient soils.

Zhai, Zhiyang; Gayomba, Sheena R.; Jung, Ha-il; Vimalakumari, Nanditha K.; Pineros, Miguel; Craft, Eric; Rutzke, Michael A.; Danku, John; Lahner, Brett; Punshon, Tracy; Guerinot, Mary Lou; Salt, David E.; Kochian, Leon V.; Vatamaniuk, Olena K.

2014-01-01

104

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

NASA Astrophysics Data System (ADS)

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 by evaporation of the bulk alloy with silicon as the substrate. Our primary goal was to make atomic resolution images of manganese using a scanning tunneling microscope (STM). However, we did not get atomic -scale images for thin films deposited on Si. Every effort was then made to improve the stability of the instrument. A double stage vibration isolation stage was built. Other aspects like the etching of sharp Pt/Ir tips was achieved by a new approach that incorporated a double etching process. While using the STM for analysis of the bulk thin films, a high percentage of manganese films showed Mn-like surface features. Images from an atomic force microscope, on the other hand, showed that the grain size of the bulk iron thin films was less than that of manganese. The size of the grains (50 nm to 150 nm) observed was in agreement with the University of Utah researchers, Jensen et al. Due to the affinity of Si towards oxygen, we concluded that Si was not a good choice for depositing thin films of iron or manganese as atomic resolution was not achieved. We then switched to graphite (Highly Oriented Pyrolytic Graphite single crystal, HOPG) as our substrate. I was fortunate to be a part of the University of Louisville team that observed all the six carbon sites of graphite well resolved with exact dimensions of 2.45 A (in agreement with the standard result) between alpha - and alpha-, beta - and beta-, and 1.4 A between the nearest neighbors alpha- and beta-. Contributions from alpha - and beta- sites varied with the bias. At an intermediate bias between 0 and 0.5 V, equal contributions from both alpha - and beta-sites were observed. The asymmetry factor as defined by Tomanek et al. (the contribution from alpha- and beta - sites) showed a minimum ~0.3 V. On graphite, thin films of Fe, Mn, and 50% Fe -50% Mn were deposited and studied using an STM. Even on graphite, a large thickness (a few hundred A) of adsorbate -metal thin film did not provide us with well-resolved atomic scale images. At lower thickness (~ 10 A), well-resolved atomic scale images were observed. Usually, metal films are difficult to image while using an STM. To get around this problem, dissimilar metals were used to image oxides of iron over a graphite substrate. Iron deposited on graphite showed a lattice spacing of ~ 3 A, in agreement with Galloway et al. The Mn lattice was successfully imaged with 3.33 and 4.44 A unit vectors and with 83.4^circ between the unit vectors. Also, catalytically active sites like steps, mounds, point defects, and clusters were successfully imaged. (Abstract shortened by UMI.).

Mathew, George

105

Expanding the menu for carnivorous plants: uptake of potassium, iron and manganese by carnivorous pitcher plants.  

PubMed

Carnivorous plants use animals as fertiliser substitutes which allow them to survive on nutrient deficient soils. Most research concentrated on the uptake of the prey's nitrogen and phosphorus; only little is known on the utilisation of other elements. We studied the uptake of three essential nutrients, potassium, iron and manganese, in three species of carnivorous pitcher plants (Cephalotus follicularis LaBilladiere, Sarracenia purpureaL., Heliamphora nutans Bentham). Using relatively short-lived and gamma-emitting radiotracers, we significantly improved the sensitivity compared to conventional protocols and gained the following results. We demonstrated the uptake of trace elements like iron and manganese. In addition, we found direct evidence for the uptake of potassium into the pitcher tissue. Potassium and manganese were absorbed to virtually 100% if offered in physiological concentrations or below in Cephalotus. Analysis of pitcher fluid collected in the natural habitat showed that uptake was performed here as efficiently as in the laboratory. The absorption of nutrients is an active process depending on living glandular cells in the pitcher epidermis and can be inhibited by azide. Unphysiologically high amounts of nutrients were taken up for a short time, but after a few hours the absorbing cells were damaged, and uptake stopped. Absorption rates of pitcher leaves from plants under controlled conditions varied highly, indicating that each trap is functionally independent. The comparison of minerals in typical prey with the plants' tissues showed that a complete coverage of the plants' needs by prey capture is improbable. PMID:19428263

Adlassnig, Wolfram; Steinhauser, Georg; Peroutka, Marianne; Musilek, Andreas; Sterba, Johannes H; Lichtscheidl, Irene K; Bichler, Max

2009-12-01

106

EVALUATION OF IRON ON CADMIUM UPTAKE BY TOMATO, MOREL AND LEAF RED BEET IN HYDROPONIC CULTURE  

Microsoft Academic Search

The objective of this research was to determine the effect of iron (Fe) deficiency on the uptake of cadmium (Cd) by three plants: tomato (Lycopersicon esculentum Mill.), morel (Solanum nigrum L.), and leaf red beet (Beta vulgaris var.cicla L.) in hydroponic culture. We also investigated the influence of Fe deficiency on rhizosphere pH, bioconcentration factor (BCF), and translocation factor (TF)

T. Bao; L.-N. Sun; T.-H. Sun

2010-01-01

107

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

Microsoft Academic Search

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

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

1990-01-01

108

Plant uptake of cadmium, zinc, and manganese from four contrasting soils amended with Cd-enriched sewage sludge.  

PubMed

Studies on the uptake of cadmium, zinc and manganese from Cd-enriched sewage sludge (0-80 mg Cd kg(-1)) amended Ultisol, Alfisol, Entisol and Vertisol by maize (Zea mays L.) followed by mung bean (Phaseolus aureus Roxb.) revealed that in general, there was a progressive reduction in the dry matter yield of both the crops due to enhanced Cd concentrations in the soil-sludge mixture in all the soils except Ultisol. Significant enhancement in the Cd content of shoots of both the crops with increased sludge Cd was also noticed. Both native and Cd-enriched sewage sludge amendments enhanced the Zn content significantly but resulted in variable uptake of Mn by maize and mung bean shoots. Data on DTPA extractable Cd from soils (Ultisol, Alfisol and Entisol) after first crop (maize) harvest correlated significantly with forage Cd of second crop (mung bean) which indicated significant residual levels of Cd available for plant uptake. PMID:15328696

Ramachandran, V; Dsouza, T J

2002-08-01

109

The photochemistry of manganese and the origin of banded iron formations  

NASA Technical Reports Server (NTRS)

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.

1992-01-01

110

[Urinary excretion of 3-methoxy-4-hydroxymandelic acid, 17-hydroxycorticosteroids and 17-ketosteroids in workers producing iron-manganese alloys].  

PubMed

Excretion of suprarenal hormones' metabolites was examined in workers producing ferro-manganese alloys. The subjects were exposed to manganese, iron , chromium compounds, thermal radiation, high temperature and noise. In comparison to the control group, those examined workers had increased excretion of 3-methoxy-4-hydroxy-mandelic acid and 17-hydroxycorticosteroids. It can be assumed that this increase results from organism's physiological adaptation to negative environmental and working conditions. PMID:1806754

Misiewicz, A; Radwan, K; Januszewska, B

1991-01-01

111

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

PubMed

Concentrations of arsenic, cadmium, chromium, lead, manganese, mercury and selenium were examined in the down feathers and eggs of female common eiders (Somateria mollissima) from Amchitka and Kiska Islands in the Aleutian Chain of Alaska to determine whether there were (1) differences between levels in feathers and eggs, (2) differences between the two islands, (3) positive correlations between metal levels in females and their eggs, and (4) whether there was more variation within or among clutches. Mean levels in eggs (dry weight) were as follows: arsenic (769 ppb, ng/g), cadmium (1.49 ppb), chromium (414 ppb), lead (306 ppb), manganese (1,470 ppb), mercury (431 ppb) and selenium (1,730 ppb). Levels of arsenic were higher in eggs, while chromium, lead, manganese, and mercury were higher in feathers; there were no differences for selenium. There were no significant interisland differences in female feather levels, except for manganese (eider feathers from Amchitka were four times higher than feathers from Kiska). Levels of manganese in eggs were also higher from Amchitka than Kiska, and eider eggs from Kiska had significantly higher levels of arsenic, but lower levels of selenium. There were no significant correlations between the levels of any metals in down feathers of females and in their eggs. The levels of mercury in eggs were below ecological benchmark levels, and were below human health risk levels. However, Aleuts can seasonally consume several meals of bird eggs a week, suggesting cause for concern for sensitive (pregnant) women. PMID:17934788

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

2008-08-01

112

The photochemistry of manganese and the origin of Banded Iron Formations.  

PubMed

The photochemical oxidation of Fe(2+) -hydroxide complexes dissolved in anoxic Precambrian oceans has been suggested as a mechanism to explain the deposition of Banded Iron Formations (BIFs). Photochemical studies have not yet addressed the low levels of manganese in many of these deposits, which probably precipitated from solutions bearing similar concentrations of Fe2+ and Mn2+. Depositional models must also explain the stratigraphic separation of iron and manganese ores in manganiferous BIFs. In this study, solutions containing 0.56 M NaCl and approximately 180 micromoles MnCl2 with or without 3 to 200 micromoles FeCl2 were irradiated with filtered and unfiltered UV light from a medium-pressure mercury-vapor lamp for up to 8 hours. The solutions were deaerated and buffered to pH approximately 7, and all experiments were conducted under O2-free (< 1 ppm) atmospheres. In experiments with NaCl + MnCl2, approximately 20% of the Mn2+ was oxidized and precipitated as birnessite in 8 hours. Manganese precipitation was only observed when light with lambda < 240 nm was used. In experiments with NaCl + MnCl2 + FeCl2, little manganese was lost from solution, while Fe2+ was rapidly oxidized to Fe3+ and precipitated as gamma-FeOOH or as amorphous ferric hydroxide. The Mn:Fe ratio of these precipitates was approximately 1:50, similar to the ratios observed in BIFs. A strong upper limit on the rate of manganese photo-oxidation during the Precambrian is estimated to be 0.1 mg cm-2 yr-1, a factor of 10(3) slower than the rate of iron photo-oxidation considered reasonable in BIF depositional basins. Thus, a photochemical model for the origin of oxide facies BIFs is consistent with field observations, although models that invoke molecular O2 as the oxidant of Fe2+ and Mn2+ are not precluded. Apparently, oxide facies BIFs could have formed under anoxic, as well as under mildly oxygenated atmospheres. PMID:11537803

Anbar, A D; Holland, H D

1992-07-01

113

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

PubMed Central

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 effect. A characterization of metal radioisotope accumulation showed that manganese competes with iron accumulation in a dose-dependent manner. Conversely, iron competes with manganese accumulation but to a lesser extent. The mutant showed a pronounced reduction (>90%) of 54Mn accumulation, showing that MtsABC is also involved in Mn transport. Using paraquat and hydrogen peroxide to induce oxidative stress, we show that the mutant has an increased susceptibility to reactive oxygen species. Moreover, activity of the manganese-cofactored superoxide dismutase in the mutant is reduced, probably as a consequence of reduced intracellular availability of manganese. The enzyme functionality was restored by manganese supplementation during growth. The mutant was also attenuated in virulence, as shown in animal experiments. These results emphasize the role of MtsABC and trace metals, especially manganese, for S. pyogenes growth, susceptibility to oxidative stress, and virulence.

Janulczyk, Robert; Ricci, Susanna; Bjorck, Lars

2003-01-01

114

The influence of curcumin and manganese complex of curcumin on cadmium-induced oxidative damage and trace elements status in tissues of mice.  

PubMed

Curcumin (diferuoyl methane) from turmeric is a well-known biologically active compound. It has been shown to ameliorate oxidative stress and it is considered to be a potent cancer chemopreventive agent. In our previous study the antioxidative effects of curcumin in cadmium exposed animals were demonstrated. Also manganese exerts protective effects in experimental cadmium intoxication. The present study examined the ability of the manganese complex of curcumin (Mn-curcumin) and curcumin to protect against oxidative damage and changes in trace element status in cadmium-intoxicated male mice. Curcumin or Mn-curcumin were administered at equimolar doses (0.14 mmol/kg b.w.) for 3 days, by gastric gavages, dispersed in methylcellulose. One hour after the last dose of antioxidants, cadmium chloride (33 micromol/kg) was administered subcutaneously. Both curcumin and Mn-curcumin prevented the increase of hepatic lipid peroxidation -- expressed as MDA level, induced by cadmium intoxication and attenuated the Cd-induced decrease of hepatic GSH level. No change in hepatic glutathione peroxidase or catalase activities was found in Cd-exposed mice. A decreased GSH-Px activity was measured in curcumin and Mn-curcumin alone treated mice. Neither curcumin nor Mn-curcumin treatment influenced cadmium distribution in the tissues and did not correct the changes in the balance of essential elements caused by Cd-treatment. The treatment with Mn-curcumin increased the Fe and Mn content in the kidneys of both control and Cd-treated mice and Fe and Cu content in the brain of control mice. In conclusion, regarding the antioxidative action, introducing manganese into the curcumin molecule does not potentiate the studied effects of curcumin. PMID:16345010

Eybl, Vladislav; Kotyzová, Dana; Lesetický, Ladislav; Bludovská, Monika; Koutenský, Jaroslav

2006-01-01

115

Conformational studies of the manganese transport regulator (MntR) from Bacillus subtilis using deuterium exchange mass spectrometry  

Microsoft Academic Search

The manganese transport regulator (MntR) of Bacillus subtilis is a metalloregulatory protein responsible for regulation of genes involved in manganese uptake by this organism. MntR belongs\\u000a to the iron-responsive DtxR family, but is allosterically regulated by manganese and cadmium ions. Having previously characterized\\u000a the metal binding affinities of this protein as well as the DNA-binding activation profiles for the relevant

Misha Golynskiy; Sheng Li; Virgil L. Woods; Seth M. Cohen

2007-01-01

116

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

NASA Astrophysics Data System (ADS)

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

Flynn, Michael John

117

[Results of spirometric examinations in workers engaged in production of iron-manganese alloys].  

PubMed

Spirometric examinations were performed in 205 workers engaged in production of iron-manganese alloys. It was found that mean values of FEV1, FEV1%, PEFR, MEF25%-75% VC and MMF were significantly lower in persons above 40 years of age, smokers and in those suffering from chronic bronchitis in comparison with people below the age of 40, non-smokers and persons free from chronic bronchitis. No relationship between the length of employment and the ventilation capacity was found. PMID:8007822

Misiewicz, A

1994-01-01

118

ORGANOMETALLIC HETEROCYCLES AND ACENE-QUINONE COMPLEXES OF RUTHENIUM, IRON AND MANGANESE  

Microsoft Academic Search

A variety of organometallic-fused heterocycles and acene quinones were prepared and characterized. This work was divided into three parts: first, the synthesis of 5,5-fused heterocyclic complexes of tricarbonylmanganese and (1’,2’,3’,4’,5’-pentamethylcyclopentadienyl)ruthenium; second, the synthesis of 1,2-diacylcyclopentadienyl p-cymene complexes of ruthenium(II); and third, synthesis of cyclopentadienyl-fused polyacenequinone complexes of ruthenium, iron and manganese.\\u000aThe first examples of the convenient, versatile and symmetric

Uttam Raj Pokharel

2012-01-01

119

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

120

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

121

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

122

Modified clinoptilolite in the removal of iron and manganese from water  

NASA Astrophysics Data System (ADS)

It is necessary to treat water intended for drinking purposes in many cases to meet the requirements of the Regulation of the Government of the Slovak Republic No. 496/2010 on Drinking Water. There is a tendency to look for technology with new, more efficient and cost-effective materials and technologies. The goal of this study is to compare activated natural zeolite known as clinoptilolite (rich deposits of clinoptilolite were found in the region of East Slovakia Region in the 1980s) with the imported Greensand and Cullsorb materials in the removal of iron and manganese from water. The results obtained from experiments carried out at WTP Kúty prove that Klinopur-Mn is suitable for the removal of iron and manganese from water and is comparable with the imported materials.

Barloková, D.; Ilavský, J.

2012-11-01

123

The Proteome of Copper, Iron, Zinc, and Manganese Micronutrient Deficiency in Chlamydomonas reinhardtii*  

PubMed Central

Trace metals such as copper, iron, zinc, and manganese play important roles in several biochemical processes, including respiration and photosynthesis. Using a label-free, quantitative proteomics strategy (MSE), we examined the effect of deficiencies in these micronutrients on the soluble proteome of Chlamydomonas reinhardtii. We quantified >103 proteins with abundances within a dynamic range of 3 to 4 orders of magnitude and demonstrated statistically significant changes in ?200 proteins in each metal-deficient growth condition relative to nutrient-replete media. Through analysis of Pearson's coefficient, we also examined the correlation between protein abundance and transcript abundance (as determined via RNA-Seq analysis) and found moderate correlations under all nutritional states. Interestingly, in a subset of transcripts known to significantly change in abundance in metal-replete and metal-deficient conditions, the correlation to protein abundance is much stronger. Examples of new discoveries highlighted in this work include the accumulation of O2 labile, anaerobiosis-related enzymes (Hyd1, Pfr1, and Hcp2) in copper-deficient cells; co-variation of Cgl78/Ycf54 and coprogen oxidase; the loss of various stromal and lumenal photosynthesis-related proteins, including plastocyanin, in iron-limited cells; a large accumulation (from undetectable amounts to over 1,000 zmol/cell) of two COG0523 domain-containing proteins in zinc-deficient cells; and the preservation of photosynthesis proteins in manganese-deficient cells despite known losses in photosynthetic function in this condition.

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

2013-01-01

124

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

PubMed

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

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

2013-01-01

125

Kinetics and thermodynamics of cadmium ion removal by adsorption onto nano zerovalent iron particles  

Microsoft Academic Search

Nano zerovalent iron (nZVI) is an effective adsorbent for removing various organic and inorganic contaminants. In this study, nZVI particles were used to investigate the removal of Cd2+ in the concentration range of 25–450mgL?1. The effect of temperature on kinetics and equilibrium of cadmium sorption on nZVI particles was thoroughly examined. Consistent with an endothermic reaction, an increase in the

Hardiljeet K. Boparai; Meera Joseph; Denis M. O’Carroll

2011-01-01

126

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

PubMed Central

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

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

2012-01-01

127

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

PubMed

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

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

2012-06-01

128

Diffusion zone between high-chromium cast iron and high-manganese steel during electric-slag facing  

Microsoft Academic Search

1.When 8% of Mn is introduced into a high-chromium cast iron of hypereutectic composition, the austenite becomes the predominant phase of the carbide eutectic; this contributes to increased strength properties of the alloys with an insignificant reduction in their wear resistance.2.During the electric-slag facing of a high-chromium cast iron containing 8% of Mn on high-manganese steel 110G13L diffusion equalization of

V. P. Ponomarenko; A. Ya. Shvartser; G. V. Stroganova

1985-01-01

129

Kinetics of oxidation of carbon in liquid iron-carbon-silicon-manganese-sulfur alloys by carbon dioxide in nitrogen  

Microsoft Academic Search

The oxidation of carbon with the simultaneous oxidation of silicon, manganese, and iron of liquid alloys by carbon dioxide\\u000a in nitrogen and the absorption of oxygen by the alloys from the gas were studied using 1-g liquid iron droplets levitated\\u000a in a stream of the gas at 1575 C to 1715 C. Oxidation of carbon was favored over oxidation of

Haiping Sun; Robert D. Pehlke

1995-01-01

130

Minimizing interferences associated with cadmium reduction determination of soil nitrate  

Microsoft Academic Search

Metals can cause an interference with the cadmium reduction determination of nitrate (NO3). This study was conducted to compare ethylenedinitrilotetraacetic acid (EDTA) and diethylenetrinitrilopentaacetic acid (DTPA) as to their effectiveness in reducing metal interference with the cadmium reduction of NO3. Soil NO3 was extracted with the Bray P1 extract and spiked with NO3. Metals [iron as Fe, manganese as Mn,

Byron Vaughan; John Howe; Mark Peplinski

1993-01-01

131

Comparative study of serum zinc, copper, manganese, and iron in preeclamptic pregnant women.  

PubMed

Preeclampsia complicates 2-8 % of all pregnancies and it is one of the leading causes of maternal mortality and pre-term delivery in the world. Unfortunately, there is scarcity of document discussing the circulating level of several essential trace elements in preeclampsia patients in Bangladesh. The present study was designed to evaluate the serum concentration of four trace elements, namely zinc, copper, manganese, and iron, in preeclamptic pregnant women. The study was conducted as a case-control study with 50 preeclamptic pregnant women as cases and 58 normotensive pregnant women as controls. Obstetric, anthropometric, and clinical data were collected at routine obstetric visits. Serum trace elements were determined by flame atomic absorption spectroscopy. Independent sample t test and Pearson's correlation test were done for the statistical analysis using the statistical software package SPSS, version 16.0 (SPSS Inc., Chicago, IL). We observed significant differences for gestational age, body mass index, and systolic and diastolic blood pressure between patient and control groups (p??0.05) except the correlation between zinc and iron in preeclampsia patients (p?manganese, and iron compared to the healthy pregnant women. PMID:23749478

Sarwar, Md Shahid; Ahmed, Salma; Ullah, Mohd Shahid; Kabir, Humayun; Rahman, G K M Mustafizur; Hasnat, Abul; Islam, Mohammad Safiqul

2013-07-01

132

[Malonyl dialdehyde concentration in red blood cells of workers engaged in the production of iron-manganese alloys].  

PubMed

The increased concentration of malonyl dialdehyde (MDA) in peripheral blood red cells of workers engaged in the production of iron-manganese alloyes was found. That provide evidence that increased peroxidation of red blood cell lipids induced by the production of free radicals is due to factors present in the occupational environment. PMID:10582205

Misiewicz, A; Radwan, K; Misiewicz, A; Dziewit, T

1999-01-01

133

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

134

Kinetic model for simultaneous leaching of zinc sulfide and manganese dioxide in the presence of iron-oxidizing bacteria  

Microsoft Academic Search

The effect of iron-oxidizing bacteria on the simultaneous leaching of zinc sulfide and manganese dioxide was studied. Some researchers have reported the enhancement of the leaching rate during the simultaneous leaching of metal oxides and metal sulfides. In the present study, we examined the effect of the presence of Thiobacillus ferrooxidans in the simultaneous leaching. We also examined the reaction

Takami Kai; Yo-ich Suenaga; Atsuko Migita; Takeshige Takahashi

2000-01-01

135

Effects of selenium on liver and muscle contents and urinary excretion of zinc, copper, iron and manganese.  

PubMed

Selenium is a main component of glutathione peroxidase (GPX), a key antioxidant enzyme. Other elements, such as zinc, copper, manganese and iron, are also involved in the pathogenesis of oxidative damage as well as in other important metabolic pathways. The effects of selenium supplementation on the metabolism of these elements have yield controversial results .The aim of this study is to analyse the effects of selenium supplementation on liver, muscle and urinary excretion of zinc, copper, iron and manganese in a situation of oxidative stress, such as protein deficiency. The experimental design included four groups of adult male Sprague-Dawley rats, which received the Lieber-DeCarli control diet, an isocaloric 2 % protein-containing diet and another similar two groups to which selenomethionine (6 mg/l liquid diet) was added. After sacrifice (5 weeks later), muscle, liver and serum selenium were determined, as well as muscle, liver and urinary zinc, copper, manganese and iron and liver GPX activity and liver malondialdehyde. Selenium addition led to decreased liver copper, increased muscle copper, increased copper excretion and increased liver iron, whereas zinc and manganese parameters were essentially unaltered. Muscle, liver and serum selenium were all significantly correlated with liver GPX activity. PMID:24622908

Monedero-Prieto, María José; González-Pérez, José María; González-Reimers, Emilio; Hernández-Pérez, Onán; Monereo-Muñoz, María; Galindo-Martín, Luis; Quintero-Platt, Geraldine; Abreu-González, Pedro

2014-05-01

136

Preorganized assembly of three iron(II) or manganese(II) ?-diketiminate complexes using a cyclophane ligand.  

PubMed

A trinucleating cyclophane bearing three ?-diketimine arms, and the corresponding iron(II) and manganese(II) complexes have been synthesized and characterized. The three metal ions are oriented towards the internal void space, and are coordinated by a N2Br2 donor set, in which a unique combination of ?(3), ?, and terminal coordination modes are observed for the halide donors. PMID:23775328

Guillet, Gary L; Sloane, Forrest T; Ermert, David M; Calkins, Matthew W; Peprah, Marcus K; Knowles, Elisabeth S; ?ižmár, Erik; Abboud, Khalil A; Meisel, Mark W; Murray, Leslie J

2013-07-28

137

A PILOT STUDY FOR ARSENIC REMOVAL FROM WATER BY ADSORPTION IN NATURAL ZEOLITE ADSORPTION IN PRESENCE OF IRON AND MANGANESE  

Microsoft Academic Search

The possibility of removing soluble arsenic from water during the application of a treatment for the removal of iron and manganese contained in that same water, has been reported by several authors. In spite of this, it is not yet possible to know in a precise manner the efficiency of removal to be accomplished in a specific case, which is

M. L. RIVERA; M. PIÑA

138

Chemiluminescent emission spectra of lead, chromium, ruthenium, iron, manganese, rhenium, osmium and tungsten in the reactive flow detector  

Microsoft Academic Search

Spectra have been measured of the chemiluminescent emissions produced by various organometallic compounds passing through the reactive flow detector (RFD). The RFD spectra of osmium, rhenium and tungsten each display a broad continuum from approximately 400 to 800 nm, whose emitting species remain unidentified. The luminescence spectra of lead, chromium, ruthenium, iron and manganese in the reactive flow are each

Kevin B. Thurbide; Walter A. Aue

2002-01-01

139

Performance characteristics of magnesium--manganese dioxide\\/nickel--cadmium hybrid system. Technical report  

Microsoft Academic Search

Improvements in the operating characteristics of the 14.4-volt section of Magnesium Battery BA-4386\\/PRC-25 are obtained by utilizing the battery in parallel directly with nine sealed 250 mAh capacity nickel--cadmium cells in series. Magnesium Battery BA-4386\\/PRC-25 contains a 3-volt section as well as the 14.4-volt section; however, the 3-volt section was not considered in this experiment. The anticipated power requirements of

Wood

1973-01-01

140

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

141

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

2011-12-01

142

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

PubMed

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

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

2013-01-01

143

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

PubMed

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

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

2013-11-01

144

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

PubMed Central

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

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

2014-01-01

145

Structure of Highly Divided Nonstoichiometric Iron Manganese Oxide Powders Fe 3? x Mn x ? 3 ?\\/4 O 4+ ?  

Microsoft Academic Search

Highly divided iron manganese oxide powders, Fe3?xMnx?3?\\/4O4+?, were prepared at low temperature (T?560°C) by the thermal decomposition of mixed oxalate precursors Fe1??Mn?C2O4, 2H2O (?=x\\/3). The manganese-rich compounds (x?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 Fe3O4–Mn3O4 phase diagram at

Sophie Guillemet-Fritsch; Sophie Viguié; Abel Rousset

1999-01-01

146

Cadmium, Environmental Exposure, and Health Outcomes  

PubMed Central

Objectives We provide an update of the issues surrounding health risk assessment of exposure to cadmium in food. Data sources We reviewed epidemiologic studies published between 2004 and 2009 concerning the bioavailability of cadmium in food, assessment of exposure, and body burden estimate, along with exposure-related effects in nonoccupationally exposed populations. Data extraction and synthesis Bioavailability of ingested cadmium has been confirmed in studies of persons with elevated dietary exposure, and the findings have been strengthened by the substantial amounts of cadmium accumulated in kidneys, eyes, and other tissues and organs of environmentally exposed individuals. We hypothesized that such accumulation results from the efficient absorption and systemic transport of cadmium, employing multiple transporters that are used for the body’s acquisition of calcium, iron, zinc, and manganese. Adverse effects of cadmium on kidney and bone have been observed in environmentally exposed populations at frequencies higher than those predicted from models of exposure. Increasing evidence implicates cadmium in the risk of diseases that involve other tissues and organ systems at cadmium concentrations that do not produce effects on bone or renal function. Conclusions Population data raise concerns about the validity of the current safe intake level that uses the kidney as the sole target in assessing the health risk from ingested cadmium. The data also question the validity of incorporating the default 5% absorption rate in the threshold-type risk assessment model, known as the provisional tolerable weekly intake (PTWI), to derive a safe intake level for cadmium.

Satarug, Soisungwan; Garrett, Scott H.; Sens, Mary Ann; Sens, Donald A.

2010-01-01

147

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

148

Arabidopsis thaliana nicotianamine synthase 4 is required for proper response to iron deficiency and to cadmium exposure.  

PubMed

The nicotianamine synthase (NAS) enzymes catalyze the formation of nicotianamine (NA), a non-proteinogenic amino acid involved in iron homeostasis. We undertook the functional characterization of AtNAS4, the fourth member of the Arabidopsis thaliana NAS gene family. A mutant carrying a T-DNA insertion in AtNAS4 (atnas4), as well as lines overexpressing AtNAS4 both in the atnas4 and the wild-type genetic backgrounds, were used to decipher the role of AtNAS4 in NA synthesis, iron homeostasis and the plant response to iron deficiency or cadmium supply. We showed that AtNAS4 is an important source for NA. Whereas atnas4 had normal growth in iron-sufficient medium, it displayed a reduced accumulation of ferritins and exhibited a hypersensitivity to iron deficiency. This phenotype was rescued in the complemented lines. Under iron deficiency, atnas4 displayed a lower expression of the iron uptake-related genes IRT1 and FRO2 as well as a reduced ferric reductase activity. Atnas4 plants also showed an enhanced sensitivity to cadmium while the transgenic plants overexpressing AtNAS4 were more tolerant. Collectively, our data, together with recent studies, support the hypothesis that AtNAS4 displays an important role in iron distribution and is required for proper response to iron deficiency and to cadmium supply. PMID:23759098

Koen, Emmanuel; Besson-Bard, Angélique; Duc, Céline; Astier, Jérémy; Gravot, Antoine; Richaud, Pierre; Lamotte, Olivier; Boucherez, Jossia; Gaymard, Frédéric; Wendehenne, David

2013-08-01

149

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

150

Chemically Modified Carbon Electrodes. XVII. Metallation of Immobilized Tetra(Aminophenyl)Porphyrin with Manganese, Iron, Nickel, Copper and Zinc, and Electrochemistry of Diprotonated Tetraphenylporphyrin.  

National Technical Information Service (NTIS)

Tetra(aminophenyl)porphyrin can be amide-bonded to oxidized glassy carbon surfaces following activation with acetyl chloride or thionyl chloride, with the latter affording higher coverage. The immbolized porphyrin can be metallated with manganese, iron, c...

R. D. Rocklin R. W. Murray

1979-01-01

151

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

PubMed Central

Ribonucleotide reductase (RNR) catalyzes the rate limiting step in DNA synthesis where ribonucleotides are reduced to the corresponding deoxyribonucleotides. Class Ib RNRs consist of two homodimeric subunits: R1E, which houses the active site; and R2F, which contains a metallo cofactor and a tyrosyl radical that initiates the ribonucleotide reduction reaction. We studied the R2F subunit of B. cereus reconstituted with iron or alternatively with manganese ions, then subsequently reacted with molecular oxygen to generate two tyrosyl-radicals. The two similar X-band EPR spectra did not change significantly over 4 to 50 K. From the 285 GHz EPR spectrum of the iron form, a g1-value of 2.0090 for the tyrosyl radical was extracted. This g1-value is similar to that observed in class Ia E. coli R2 and class Ib R2Fs with iron-oxygen cluster, suggesting the absence of hydrogen bond to the phenoxyl group. This was confirmed by resonance Raman spectroscopy, where the stretching vibration associated to the radical (C-O, ?7a?=?1500 cm?1) was found to be insensitive to deuterium-oxide exchange. Additionally, the 18O-sensitive Fe-O-Fe symmetric stretching (483 cm?1) of the metallo-cofactor was also insensitive to deuterium-oxide exchange indicating no hydrogen bonding to the di-iron-oxygen cluster, and thus, different from mouse R2 with a hydrogen bonded cluster. The HF-EPR spectrum of the manganese reconstituted RNR R2F gave a g1-value of ?2.0094. The tyrosyl radical microwave power saturation behavior of the iron-oxygen cluster form was as observed in class Ia R2, with diamagnetic di-ferric cluster ground state, while the properties of the manganese reconstituted form indicated a magnetic ground state of the manganese-cluster. The recent activity measurements (Crona et al., (2011) J Biol Chem 286: 33053–33060) indicates that both the manganese and iron reconstituted RNR R2F could be functional. The manganese form might be very important, as it has 8 times higher activity.

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

2012-01-01

152

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

PubMed Central

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

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

2013-01-01

153

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

2013-04-01

154

Mesoporous iron–manganese oxides for sulphur mustard and soman degradation  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? New nanodispersive materials based on Fe and Mn oxides for degradations of warfare agents. ? The best activities for the degradation of sulphur mustard (97.9% in 64 min) and soman (97.9% in 64 min). ? One pot synthesis with friendly transformed to industrial conditions. -- Abstract: Substituted iron(III)–manganese(III, IV) oxides, ammonio-jarosite and birnessite, were prepared by a homogeneous hydrolysis of potassium permanganate and iron(III) sulphate with 2-chloroacetamide and urea, respectively. Synthesised oxides were characterised using Brunauer–Emmett–Teller (BET) surface area and Barrett–Joiner–Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), Raman spectroscopy and scanning electron microscopy (SEM). The oxides were taken for an experimental evaluation of their reactivity against sulphur mustard (HD) and soman (GD). When ammonio-jarosite formation is suppressed by adding urea to the reaction mixture, the reaction products are mixtures of goethite, schwertmannite and ferrihydrite, and their degradation activity against soman considerably increases. The best activities for the degradation of sulphur mustard (97.9% in 64 min) and soman (97.9% in 64 min) were observed for FeMn{sub 7}5 with 32.6 wt.% Fe (36.8 wt.% Mn) and FeMn{sub 3}7U with 60.8 wt.% Fe (10.1 wt.% Mn) samples, respectively.

Štengl, Václav, E-mail: stengl@iic.cas.cz [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR, v.v.i., 250 68 ?ež (Czech Republic) [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR, v.v.i., 250 68 ?ež (Czech Republic); J.E. Purkyn? University in Ústí nad Labem, Faculty of Environment, 400 96 Ústí nad Labem (Czech Republic); Grygar, Tomáš Matys [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR, v.v.i., 250 68 ?ež (Czech Republic) [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR, v.v.i., 250 68 ?ež (Czech Republic); J.E. Purkyn? University in Ústí nad Labem, Faculty of Environment, 400 96 Ústí nad Labem (Czech Republic); Bludská, Jana [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR, v.v.i., 250 68 ?ež (Czech Republic)] [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR, v.v.i., 250 68 ?ež (Czech Republic); Opluštil, František; N?mec, Tomáš [Military Technical Institute of Protection Brno, Vesla?ská 230, 628 00 Brno (Czech Republic)] [Military Technical Institute of Protection Brno, Vesla?ská 230, 628 00 Brno (Czech Republic)

2012-12-15

155

Liver and kidney concentrations of strontium, barium, cadmium, copper, zinc, manganese, chromium, antimony, selenium and lead in cats  

PubMed Central

Background In order to provide new knowledge on the storage of strontium (Sr), barium (Ba), cadmium (Cd), copper (Cu), zinc (Zn), manganese (Mn), chromium (Cr), antimony (Sb), selenium (Se) and lead (Pb) in the feline organism, we measured the concentrations of these elements in the liver, renal cortex and renal medulla, evaluating also the impact of age, sex or the occurrence of a chronic kidney disease (CKD). The element concentrations in the tissues of 47 cats (22 male; 25 female; aged between 2 months and 18 years) were measured using inductively coupled plasma mass spectrometry. Results Cu, Zn and Mn were the highest in the liver, followed by the renal cortex and the renal medulla. The Cd concentrations were lower in the renal medulla compared to the renal cortex and the liver, and Sr was higher in the renal medulla compared to the liver. The Se concentrations in the cortex of the kidneys were higher than in the medulla of the kidneys and in the liver. Higher Cd concentrations were measured in the renal cortex of female cats, while no further gender-related differences were observed. Except for Cr, Sb and Se, age-dependencies were detected for the storage of all elements. The occurrence of a CKD also affected the storage of the elements, with lower concentrations of Ba (renal medulla), Zn (renal cortex; renal medulla) and Mn (liver; renal medulla), but higher Cd concentrations (liver; renal cortex) in diseased cats. Conclusions In conclusion, the present results provide new information on the accumulation of specific elements in the feline liver and kidneys, demonstrating a dependency on age and an impaired kidney function, but not on the sex of the animals.

2014-01-01

156

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

PubMed

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

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

2012-01-01

157

Evaluation of iron and manganese-coated pumice application for the removal of as(v) from aqueous solutions.  

PubMed

Arsenic contamination of water has been recognized as a serious environmental issue and there are reports on its epidemiological problems to human health. The objective of this study was to evaluate the performances of iron-coated pumice and manganese-coated pumice as the adsorbents for removing arsenate from aqueous solutions. The effect of various parameters such as adsorbent dose, contact time, pH and initial concentration on removal efficiency of arsenate were evaluated in batch mode. The data obtained from the kinetic studies were analyzed using kinetic models of pseudo-first-order and pseudo-second-order. In addition, two isotherm models of Freundlich and Langmuir were used to fit the experimental data. The results showed that the optimum dosage of iron-coated pumice and manganese-coated pumice for arsenate removal were 40 and 80 g/L whereas the adsorption process reached equilibrium after 80 and 100 min, respectively. The maximum removal efficiency of arsenate using the two adsorbents were both recorded in pH=3 as the removal efficiency gradually declined following every increase in pH values of the solution. Iron-coated pumice also showed to have high removal efficiency when the initial concentration of arsenate was high while the low concentration of arsenate was efficiently removed by manganese-coated pumice. Moreover, it was depicted that the adsorption kinetics by both adsorbents followed pseudo-second order equation and the uptake data of arsenate were well fitted with Langmuir isotherm model. Therefore, it could be concluded that iron and manganese-coated pumice could be considered as suitable adsorbents for arsenate removal from aqueous solutions. PMID:23369510

Far, Leila Babaie; Souri, Bubak; Heidari, Masoumeh; Khoshnavazi, Roshan

2012-01-01

158

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

159

Regional distributions of manganese, iron, copper, and zinc in the brains of 6-hydroxydopamine-induced parkinsonian rats  

Microsoft Academic Search

Time courses of changes in manganese, iron, copper, and zinc concentrations were examined in regions of the brain of a 6-hydroxydopamine\\u000a (6-OHDA)-induced rat model of Parkinson’s disease using inductively coupled plasma mass spectrometry (ICP-MS). The concentrations\\u000a were simultaneously determined in brain section at the level of the substantia nigra 1, 3, 7, 10, 14, and 21 days after the\\u000a 6-OHDA treatment

Tohru Tarohda; Yasushi Ishida; Keiichi Kawai; Masayoshi Yamamoto; Ryohei Amano

2005-01-01

160

Impact of orchard and tillage management practices on soil leaching of atrazine, potassium, magnesium, manganese, iron, ammonium, nitrates and phosphates  

Microsoft Academic Search

The experiments were carried out on an Orthic Luvisol developed from loess, over limestone, at the experimental field of Lublin Agricultural University in Felin (51o15'N, 22o35'E), Poland. The investigation deals with the problems of leaching's rate of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,2,3-triazine), potassium, magnesium, manganese, iron, ammonium, nitrates and phosphates from two management systems of soil: (i) conventionally tilled field with main tillage

L. Szajdak; J. Lipiec; A. Siczek; U. Kotowska; A. Nosalewicz

2009-01-01

161

Kinetics of oxidation of carbon in liquid iron-carbon-silicon-manganese-sulfur alloys by carbon dioxide in nitrogen  

NASA Astrophysics Data System (ADS)

The oxidation of carbon with the simultaneous oxidation of silicon, manganese, and iron of liquid alloys by carbon dioxide in nitrogen and the absorption of oxygen by the alloys from the gas were studied using 1-g liquid iron droplets levitated in a stream of the gas at 1575 °C to 1715 °C. Oxidation of carbon was favored over oxidation of silicon and manganese when cast iron (3.35 pct C, 2.0 pct Si, 0.36 pct Mn, and 0.05 pct S) reacted with CO2/N2 gas at 1635 °C. An increase in the flow rate of CO2/N2 gas increased the decarburization rate of cast iron. The rate of carbon oxidation by this gas mixture was found to be independent of temperature and alloying element concentrations (in the range of silicon = 0 to 2.0 pct manganese = 0 to 0.36 pct and sulfur = 0 to 0.5 pct) within the temperature range of the present study. Based on the results of a kinetic analysis, diffusion of CO2 in the boundary layer of the gas phase was found to be the rate-limiting step for the reactions during the earlier period of the reaction when the contents of carbon, silicon, and manganese are higher. However, the limiting step changed to diffusion of the elements in the metal phase during the middle period of the reaction and then to the diffusion of CO in the gas phase during the later period of the reaction when the content of the elements in the metal were relatively low. For the simultaneous oxidation reactions of several elements in the metal, however, the diffusion of CO2 in the gas phase is the primary limiting step of the reaction rate for the oxidation of carbon during the later period of reaction.

Sun, Haiping; Pehlke, Robert D.

1995-04-01

162

Evaluation of iron and manganese-coated pumice application for the removal of as(v) from aqueous solutions  

PubMed Central

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

2012-01-01

163

Neutron and Charged-Particle Induced Cross Sections for Radiochemistry for Isotopes of Scandium, Titanium, Vanadium, Chromium, Manganese, and Iron  

SciTech Connect

We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Local systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron and proton induced nuclear reaction cross sections in the mass region of scandium, titanium, vanadium, chromium, manganese, and iron (21 {le} Z {le} 26, 20 {le} N {le} 32).

Kelley, K; Hoffman, R D; Dietrich, F S; Bauer, R; Mustafa, M

2004-11-30

164

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

PubMed

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

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

2004-03-01

165

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

2013-09-01

166

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

167

Early diagenetic processes generate iron and manganese oxide layers in the sediments of Lake Baikal, Siberia.  

PubMed

Distinct layers of iron(III) and manganese(IV) (Fe/Mn) oxides are found buried within the reducing part of the sediments in Lake Baikal and cause considerable complexity and steep vertical gradients with respect to the redox sequence. For the on-site investigation of the responsible biogeochemical processes, we applied filter tube samplers for the extraction of sediment porewater combined with a portable capillary electrophoresis instrument for the analyses of inorganic cations and anions. On the basis of the new results, the sequence of diagenetic processes leading to the formation, transformation, and dissolution of the Fe/Mn layers was investigated. With two exemplary cores we demonstrate that the dissolution of particulate Fe and Mn is coupled to the anaerobic oxidation of CH? (AOM) either via the reduction of sulphate (SO?(2-)) and the subsequent generation of Fe(II) by S(-II) oxidation, or directly coupled to Fe reduction. Dissolved Fe(II) diffuses upwards to reduce particulate Mn(IV) thus forming a sharp mineral boundary. An alternative dissolution pathway is indicated by the occurrence of anaerobic nitrification of NH?(+) observed at locations with Mn(IV). Furthermore, the reasons and consequences of the non-steady-state sediment pattern and the resulting redox discontinuities are discussed and a suggestion for the burial of active Fe/Mn layers is presented. PMID:24619231

Torres, Natascha T; Och, Lawrence M; Hauser, Peter C; Furrer, Gerhard; Brandl, Helmut; Vologina, Elena; Sturm, Michael; Bürgmann, Helmut; Müller, Beat

2014-04-01

168

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

169

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

170

Nutrient composition of selected wheats and wheat products. VI. Distribution of manganese, copper, nickel, zinc, magnesium, lead, tin, cadmium, chromium, and selenium as determined by atomic absorption spectroscopy and colorimetry  

Microsoft Academic Search

Magnesium and eight trace mineral elements, manganese, copper, nickel, zinc, lead, tin, cadmium, and chromium, were determined by atomic absorption spectroscopy in 11 known wheats or wheat blends, 20 commercially prepared flours from these wheats, and 25 specially prepared products from the flours. The same minerals were determined in ten consumer products from ten different cities. There was significant variation

E. G. Zook; F. E. Greene; E. R. Morris

1970-01-01

171

Iron deposition at mineralization fronts and osteoid formation following chronic cadmium exposure in ovariectomized rats.  

PubMed

To investigate whether chronic exposure of cadmium (Cd) chloride induces osteomalacic lesions similar to Itai-itai disease (IID), ovariectomized rats were injected intravenously with the cadmium at doses of 0.05 and 0.5 mg/kg/day, 5 days per week, for 50 weeks. In six rats in the 0.5 mg/kg group, the administration was continued for up to 70 weeks. In the 0.5 mg/kg group, the plasma concentration of calcium was similar in the treatment and control groups throughout the treatment period. The urinary excretion of calcium increased from 20 weeks and the increase became marked from 40 weeks. Histopathologically, osteoid seams in the femur, tibia, and humerus were increased from 50 weeks, and these changes became prominent at 70 weeks. Hypertrophy and hyperplasia of chief cells in the parathyroid were also observed from 50 weeks. The osteoid morphometry of the trabecular bone of the femur and sternum revealed a dose-dependent increase in osteoid/bone volumes. Roentgenographs of the antebrachial and metacarpal bones taken at 70 weeks showed so-called paper bone. The bone Cd content markedly increased until 25 weeks, but thereafter decreased linearly for up to 70 weeks. In contrast to the Cd content, the iron content decreased until 25 weeks, but thereafter increased until 70 weeks. Undecalcified section of the humerus showed the deposition of iron and formation of osteoid at mineralization fronts. Our data suggest that osteomalacic lesions were caused by chronic Cd intoxication, and that iron, as well as Cd, was involved in osteoid formation. PMID:9144451

Hiratsuka, H; Katsuta, O; Toyota, N; Tsuchitani, M; Akiba, T; Marumo, F; Umemura, T

1997-04-01

172

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

173

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

174

Synthesis, characterization and chemical properties of 1-((E)-2-pyridinylmethylidene)semicarbazone manganese(II) and iron(II) complexes  

NASA Astrophysics Data System (ADS)

Manganese(II) perchlorate and iron(II) chloride react with 2-formylpyridine semicarbazone (HCSpy) in boiling ethanol to produce [Mn II(HSCpy) 2](ClO 4) 2·C 2H 5OH and [Fe IICl(HSCpy)]Cl. The distorted octahedral manganese complex crystallizes in the triclinic system with space group P(-1). The ligand HSCpy is tridentate and is coordinated through two nitrogen and one oxygen atoms. Comparison of the bond distances with analogous transition metal complexes that have the same geometry revealed longer bonds for the manganese derivative, an outcome that correlates well with the radius of the metal ions. The iron(II) ion is tetracoordinated to one semicarbazone and one chloride. Mass spectrometry, conductivity measurements, Mössbauer, UV-VIS, FTIR and elemental analysis were all in accordance with the proposed composition and the plausible geometry of [FeCl(HSCpy)]Cl. Mass spectrometry unequivocally detected the presence of the [FeCl(HSCpy)] + ion with a m/ z of 254.97 and intensity of 2 × 10 5.

Garbelini, Ellery Regina; Martin, Maria da Graça M. B.; Back, Davi Fernando; Evans, David John; Müller-Santos, Marcelo; Ribeiro, Ronny Rocha; Lang, Ernesto Schulz; Nunes, Fábio Souza

2012-01-01

175

Chemiluminescent photon yields measured in the flame photometric detector on chromatographic peaks containing sulfur, phosphorus, manganese, ruthenium, iron or selenium  

NASA Astrophysics Data System (ADS)

Photon yields — the number of photons generated per analyte atom — are of obvious analytical and mechanistic importance in flame chemiluminescence. However, such numbers are unavailable for spectral detectors in gas chromatography (as well as for most conventional spectroscopic systems). In this study, photon yields have been determined for the chemiluminescence of several elements in the flame photometric detector (FPD). The number of photons generated per atom of FPD-active element was 2×10 -3 for sulfur (emitter S 2*, test compound thianaphthene), 3×10 -3 for phosphorus [HPO*, tris(pentafluorophenyl)phosphine], 8×10 -3 for manganese (Mn*, methylcyclopentadienyl manganese tricarbonyl), 3×10 -3 for ruthenium (emitter unknown, ruthenocene), 4×10 -5 for iron (Fe*, ferrocene) and 2×10 -4 for selenium (Se 2*, dimethylbenzselenazole). Total flows, maximum thermocouple temperatures, and visible flame volumes have also been estimated for each element under signal/noise-optimized conditions in order to provide a database for kinetic calculations.

Aue, Walter A.; Singh, Hameraj

2001-05-01

176

Role of the iron transporter OsNRAMP1 in cadmium uptake and accumulation in rice.  

PubMed

The heavy metal cadmium (Cd) is toxic to humans, and its accumulation in rice grains is a major agricultural problem. Rice has seven putative metal transporter NRAMP genes, but microarray analysis showed that only OsNRAMP1 is highly up-regulated by iron (Fe) deficiency. OsNRAMP1 localized to the plasma membrane and transported Cd as well as Fe. OsNRAMP1 expression was observed mainly in roots and was higher in the roots of a high-Cd-accumulating cultivar (Habataki) than in those of a low-Cd-accumulating cultivar (Sasanishiki). The amino acid sequence of OsNRAMP1 in the Sasanishiki and Habataki cultivars was found to be 100% identical. These results suggest that OsNRAMP1 participates in cellular Cd uptake and that the differences observed in Cd accumulation among cultivars are because of differences in OsNRAMP1 expression levels in roots. PMID:22067109

Takahashi, Ryuichi; Ishimaru, Yasuhiro; Nakanishi, Hiromi; Nishizawa, Naoko K

2011-11-01

177

High-nuclearity manganese and iron complexes with the anionic ligand methyl salicylimidate.  

PubMed

The three novel clusters [Mn6O4(OMe)2(OAc)4(Mesalim)4] (3), [Mn8O2(OH)2(OMe)12(OAc)2(Mesalim)4] (4), and [Fe10O4(OMe)14Cl2(Mesalim)6] (5) have been synthesized from a simple bidentate ligand HMesalim (HMesalim = methyl salicylimidate). Starting from the mononuclear complex [Mn(Mesalim)2(OAc)(MeOH)].MeOH (1), either the hexanuclear complex 3 or the octanuclear complex 4 is obtained after recrystallization, depending upon the reaction conditions and solvents used. Similarly, starting from the purple-colored mononuclear complex [Fe(Mesalim)2Cl] (2), the orange-colored decanuclear iron(III) cluster 5 has been obtained upon recrystallization from methanol. Complex 3, which could also be prepared directly from manganese acetate and the ligand, has a face-sharing double-cubane [Mn6O6] core, unique in transition metal chemistry. Compounds 4 and 5 are composed of [M3O4] partial cubanes. All complexes belong to a class of oxo-bridged cubic close-packed molecular clusters resembling the metal oxide/hydroxide ores. Complex 4 exhibits intramolecular ferromagnetic interactions, as evidenced from dc magnetic susceptibility studies (1.8-300 K), resulting in a high-spin ground state, probably with S(T) = 8. Complex 4 displays single molecule magnet behavior as indicated by frequency and temperature dependences of its ac susceptibility. An Arrhenius plot gave relatively large experimental activation energy of 36.0 K. The magnetic properties of complexes 3 and 5 are dominated by antiferromagnetic interactions leading to zero-spin ground states. PMID:16903727

Godbole, Meenal D; Roubeau, Olivier; Mills, Allison M; Kooijman, Huub; Spek, Anthony L; Bouwman, Elisabeth

2006-08-21

178

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

179

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

180

Determination of iron, copper, manganese, zinc, lead, and cadmium in mushroom samples from Tokat, Turkey  

Microsoft Academic Search

Contents of Fe, Cu, Mn, Zn, Pb, and Cd in 10 mushrooms species from Tokat, Turkey were determined by atomic absorption spectrometry. The results indicate that Fe, Cu, Mn, and Pb levels in the species Fomes fementarius were the highest with means of 3904±307 mg\\/kg, 54±4 mg\\/kg, 64±5 mg\\/kg, 2.7±2.0 mg\\/kg, respectively. The highest level of Zn was 122±11 mg\\/kg

Ibrahim Turkekul; Mahfuz Elmastas; Mustafa Tüzen

2004-01-01

181

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

PubMed

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

Ammendola, Serena; Cerasi, Mauro; Battistoni, Andrea

2014-08-01

182

Iron and manganese controlled sulfur cycling recorded in sulfur and oxygen isotopes of pore water sulfate in glacial fjord sediments of west Svalbard  

NASA Astrophysics Data System (ADS)

The sulfur and oxygen isotope composition of pore water sulfate from glacial fjords of Svalbard record extensive, glacially coupled, cycling of sulfur in Arctic sediments. During August 2008 a regionally comprehensive sampling campaign aboard the RV Farm collected pore water samples from Smeerenburgfjorden, van Mijenfjorden, and Kongsfjorden. The focus of the study is to address how glacially delivered sulfate, reactive iron, and manganese influence the biogeochemical cycling of sulfur within Arctic fjords as recorded in the sulfate ?34S and ?18O records preserved in the pore waters. Sampling focused on transects from proglacial regions to areas distal to glacial influences within each fjord. First results show both spatial and depth variability in oxygen and sulfur isotope composition of pore water sulfate. Pore water sulfate concentrations do not systematically decrease with depth in most of our sample locations, however, among sample sites the relative sulfate concentrations decrease between 3 to 11%. Coupled to these measurable depletions in sulfate concentrations, the sulfur isotope compositions fluctuate from +19.0 to 22.2‰ (V-CDT) and oxygen isotopes vary from 7.7 to 11.2‰ (V-SMOW). Within individual fjords the isotopic variation appears to be coupled to the availability of reactive iron and manganese delivered by detrital glacial inputs. Additionally, the sulfur isotopic composition of pore water sulfate in the core tops appears to be influenced by glacially derived sulfate. This indicates that the detrital input of reactive iron and manganese may alter the isotopic composition of pore water sulfate, specifically the oxygen isotope composition. Organoclastic sulfate reduction in the fjord sediments leads to the production of acid-volatile sulfides (AVS) depleted in 34S. The sulfides are reoxidized by the available reactive iron- and manganese- oxide containing minerals. This includes the reoxidation of reduced iron by manganese and subsequent oxidation of AVS by these oxidized iron species. These processes lead to the recycling of sulfide to sulfate through sulfur intermediates and concomitantly resupplying the sulfate reservoir with 32S. Overall, these reactions lead to the observed minor sulfur isotope changes in pore water sulfate. However, these same processes can lead to 18O enrichment of pore water sulfate. Reoxidation of reduced sulfur either directly coupled to reduction by iron oxides or as a by-product of the reaction of reduced iron with reactive manganese, produces sulfur intermediates that are available for microbial disproportionation. Disproportionation of sulfur intermediates, such as elemental sulphur, thiosulfate or sulfite produces sulfate that is likely to be enriched in 18O. The 18O enrichments coupled with minor variations in ?34S of sulfate observed throughout the fjords of Svalbard are indicative of extensive iron and manganese driven sulfur cycling in Arctic sediments.

Formolo, M.; Brunner, B.; Hubert, C.; Ferdelman, T. G.; Jørgensen, B.

2009-12-01

183

Effect of Anions on the Binding and Oxidation of Divalent Manganese and Iron in Modified Bacterial Reaction Centers  

PubMed Central

Abstract The influence of different anions on the binding and oxidation of manganous and ferrous cations was studied in four mutants of bacterial reaction centers that can bind and oxidize these metal ions. Light-minus-dark difference optical and electron paramagnetic resonance spectroscopies were applied to monitor electron transfer from bound divalent metal ions to the photo-oxidized bacteriochlorophyll dimer in the presence of five different anions. At pH 7, bicarbonate was found to be the most effective for both manganese and iron binding, with dissociation constants around 1 ?M in three of the mutants. The pH dependence of the dissociation constants for manganese revealed that only bicarbonate and acetate were able to facilitate the binding and oxidation of the metal ion between pH 6 and 8 where the tight binding in their absence could not otherwise be established. The data are consistent with two molecules of bicarbonate or one molecule of acetate binding to the metal binding site. For ferrous ion, the binding and oxidation was facilitated not only by bicarbonate and acetate, but also by citrate. Electron paramagnetic resonance spectra suggest differences in the arrangement of the iron ligands in the presence of the various anions.

Tang, Kai; Williams, JoAnn C.; Allen, James P.; Kalman, Laszlo

2009-01-01

184

Insights into the iron-ome and manganese-ome of ?mtm1 Saccharomyces cerevisiae Mitochondria  

PubMed Central

Biophysical spectroscopies and LC-ICP-MS were used to evaluate the iron-ome and manganese-ome of mitochondria from ?mtm1 yeast cells. Deleting the mitochondrial carrier gene MTM1 causes Fe to accumulate in mitochondria and Mn superoxide dismutase (SOD2) activity to decline. One explanation for this is that some accumulated Fe misincorporates into apo-Sod2p. Mössbauer spectroscopy revealed that most of the accumulated Fe was FeIII nanoparticles which are unlikely to misincorporate into apo-Sod2p. Under anaerobic conditions, Fe did not accumulate yet SOD2 activity remained low, suggesting that the two phenomena are independent. Mn concentrations were two-fold higher in ?mtm1 mitochondria than in WT mitochondria. Soluble extracts from such samples were subjected to size-exclusion LC and fractions were analyzed with an on-line ICP-MS. Two major Mn peaks were observed, one due to MnSod2p and the other to a Mn species with a mass of 2–3 kDa (called Mn2–3). Mn2–3 may deliver Mn into apo-Sod2p. Most Mn in WT mitochondria was associated with MnSod2p, whereas most Mn in ?mtm1 mitochondria was associated with Mn2–3. The [Mn2–3] increased in cells grown on high MnCl2 while the MnSod2p concentration remained unchanged. Corresponding Fe traces showed numerous peaks, including a complex of ~ 3 kDa which may be the form of Fe that misincorporates, and an Fe peak with the molecular mass of Sod2p that may correspond to FeSod2p. The intensity of this peak suggests that deleting MTM1 probably diminishes SOD2 activity by some means other than Fe misincorporation. A portion of Sod2p in ?mtm1 mitochondria might be unfolded or immature. Mtm1p may import a species required for apo-Sod2p maturation, activity or stability.

Park, Jinkyu; McCormick, Sean P.; Chakrabarti, Mrinmoy

2013-01-01

185

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

PubMed Central

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

Yebra, M. Carmen

2012-01-01

186

The role of genotypes on phosphorus, zinc, manganese and iron status and their relations in leaves of maize on hydromorphic soil  

Microsoft Academic Search

Hydromorphy is a major soil fertility constraint in Europe and North America causing specific nutritional imbalance in soils and crops. The objectives of this study were to examine the differences among maize hybrids in phosphorus (P), zinc (Zn), manganese (Mn) and iron (Fe) status in leaves, and to investigate the interrelationship among these micronutrients as well as the interrelationship between

V. Kova?evi?; I. Brki?; D. Šimi?; G. Bukvi?; M. Rast?a

2004-01-01

187

Origin of Iron-Rich Montmorillonite from the Manganese Nodule Belt of the North Equatorial Pacific  

Microsoft Academic Search

Clay minerals in the upper 50 cm of sediment that surround the Cu- and Ni-rich manganese nodules in the North Equatorial Pacific form two fractions: terrigenous (mostly eolian) illite, chlorite, and kaolinite, and authigenic smectite. Smectite increases with depth in box cores from 26 to 39% and from 53 to 66% in the easternmost and westernmost areas respectively, and with

James R. Hein; HSUEH-WEN YEH; ELAINE ALEXANDER

1979-01-01

188

A Comparison of Strontium Sorption to Hydrous Aluminum, Iron, and Manganese Oxides  

Microsoft Academic Search

Strontium sorption to hydrous aluminum (HAO) and manganese (HMO) oxides was studied using macroscopic studies on short- and long-term bases. These studies were compared with previous results for strontium sorption to hydrous ferric oxide (HFO). Sorption to these microporous oxides can be described as a two-step process: a rapid and reversible adsorption reaction to the external surface including the macropores

Paras Trivedi; Lisa Axe

1999-01-01

189

[Excretion of hydroxyproline in the urine of workers engaged in the production of iron-manganese alloys].  

PubMed

Statistically significant increase of the excretion of hydroxyproline with urine has been found to occur in workers employed in iron-manganese alloy manufacture, compared with the excretion of hydroxyproline in urine of the control group. Besides, the workers employed for 10 years and longer were characterized by statistically significantly increased excretion of hydroxyproline with urine as compared to the workers employed for shorter periods. No significant differences in excretion of hydroxyproline with urine, however, were detected among workers with chronic bronchitis and among those with smoking factor less than or equal to 10 and smoking factor greater than 10. (Smoking factor = number of packages of cigarettes smoked per day times years of smoking). PMID:1808446

Misiewicz, A

1991-01-01

190

Two-, three-, and four-component magnetic multilayer onion nanoparticles based on iron oxides and manganese oxides.  

PubMed

Magnetic multilayered, onion-like, heterostructured nanoparticles are interesting model systems for studying magnetic exchange coupling phenomena. In this work, we synthesized heterostructured magnetic nanoparticles composed of two, three, or four components using iron oxide seeds for the subsequent deposition of manganese oxide. The MnO layer was allowed either to passivate fully in air to form an outer layer of Mn(3)O(4) or to oxidize partially to form MnO|Mn(3)O(4) double layers. Through control of the degree of passivation of the seeds, particles with up to four different magnetic layers can be obtained (i.e., FeO|Fe(3)O(4)|MnO|Mn(3)O(4)). Magnetic characterization of the samples confirmed the presence of the different magnetic layers. PMID:21973012

Salazar-Alvarez, German; Lidbaum, Hans; López-Ortega, Alberto; Estrader, Marta; Leifer, Klaus; Sort, Jordi; Suriñach, Santiago; Baró, Maria Dolors; Nogués, Josep

2011-10-26

191

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

192

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

PubMed

Conducted with the participation of 50 students of military educational study the effect of various vitamin and mineral complexes for the provision by the body naturally iron, copper and manganese on the immune and physical status. Found that diets enriched BMV was accompanied by a significant delay in the micro-elements, mainly iron, which indicates a deficiency of these bioelements in chickens Santo during the summer. Under the influence of vitamin-mineral complexes significantly increased rates of natural and specific immunity. As the delay increases significantly increased iron medical indicators of immunological reaction efficiency and physical performance. PMID:22686030

Za?tseva, I P; Nosolodin, V V; Za?tsev, O N; Gladkikh, I P; Koznienko, I V; Beliakov, R A; Arshinov, N P

2012-03-01

193

Structure of Highly Divided Nonstoichiometric Iron Manganese Oxide Powders Fe3- xMnx□3delta\\/4O4+delta  

Microsoft Academic Search

Highly divided iron manganese oxide powders, Fe3- xMnx□3delta\\/4O4+delta, were prepared at low temperature (T<=560 degC) by the thermal decomposition of mixed oxalate precursors Fe1-alphaMnalphaC2O4, 2H2O (alpha=x\\/3). The manganese-rich compounds (x>=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 Fe3O4-Mn3O4 phase

Sophie Guillemet-Fritsch; Sophie Viguié; Abel Rousset

1999-01-01

194

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

NASA Astrophysics Data System (ADS)

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

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

1995-12-01

195

In Vivo Self-Hydroxylation of an Iron-Substituted Manganese-Dependent Extradiol Cleaving Catechol Dioxygenase  

PubMed Central

The homoprotocatechuate 2,3-dioxygenase from Arthrobacter globiformis (MndD) catalyzes the oxidative ring cleavage reaction of its catechol substrate in an extradiol fashion. While this reactivity is more typically associated with nonheme iron enzymes, MndD exhibits an unusual specificity for manganese(II). MndD is structurally very similar to the iron(II)-dependent homoprotocatechuate 2,3-dioxygenase from Brevibacterium fuscum (HPCD), and we have previously shown that both MndD and HPCD are equally active towards substrate turnover with either Fe(II) or Mn(II) [J P Emerson, et al. (2008) Proc Natl Acad Sci USA, 105: 7347–7352]. However, expression of MndD in E. coli under aerobic conditions in the presence of excess iron results in the isolation of inactive blue-green Fe-substituted MndD (BG-FeMndD). Spectroscopic studies indicate that this form of Fe-substituted MndD contains an Fe(III) center with a bound catecholate, which is presumably generated by in vivo self-hydroxylation of a second-sphere tyrosine residue, as found for other self-hydroxylated nonheme iron oxygenases,. The absence of this modification in either the native Mn-containing MndD or Fe-containing HPCD suggests that the metal center of Fe-substituted MndD is able to bind and activate O2 in the absence of its substrate, employing a high-valent oxoiron oxidant to carry out the observed self-hydroxylation chemistry. These results demonstrate that the active site metal in MndD can support two dramatically different O2 activation pathways, further highlighting the catalytic flexibility of enzymes containing a 2-His-1-carboxylate facial triad metal binding motif.

Farquhar, Erik R.; Emerson, Joseph P.; Koehntop, Kevin D.; Reynolds, Mark F.; Trmcic, Milena

2011-01-01

196

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

197

[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

198

Seasonal and locational effects on serum, milk, liver and kidney chromium, manganese, copper, zinc, and iron concentrations of dairy cows.  

PubMed

Chromium (Cr), manganese (Mn), copper (Cu), zinc (Zn), and iron (Fe) concentrations were quantified in serum (n = 112), milk (n = 112), liver (n = 70), and kidney samples (n = 67) of dairy cows from an iron-steel processing region (Payas-Iskenderun) and from an area free of industrial pollution (Antakya) in Hatay, located in Southern Turkey. Samples were collected in the summer and winter and element determinations were carried out by inductively coupled plasma-atomic emission spectrometry. The mean concentrations of selected elements in serum were found to be similar in both regions. Milk samples collected from the nonindustrial region in the summer had higher Cr, Mn, and Zn concentrations than the polluted region. The liver Cu and kidney Mn levels of samples taken from the industrial region in winter were higher than samples of the unpolluted region. Copper and Fe concentrations in milk, Cr, Mn, Zn, and Fe levels in the liver, and Cr, Cu, Zn, and Fe levels in kidney samples were not found to be different among the regions in both seasons. Copper concentrations were below the critical level in the 25% of serum and 32% of liver samples analyzed in this study. Fifteen percent of serum samples and most of the liver samples had lower amounts of Zn than other reported studies. Although slight differences were observed between the industrial and nonindustrial regions, industrial activities and seasonal changes had no significant effect on selected element concentrations on cows and their milk. PMID:15051900

Erdogan, Suat; Celik, Sefa; Erdogan, Zeynep

2004-04-01

199

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

NASA Astrophysics Data System (ADS)

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

Morales Toro, Juan Eduardo

200

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

201

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

Microsoft Academic Search

The effect of resuspension on benthic fluxes of oxygen (O2), ammonium (NH4+), nitrate (NO3?), phosphate (PO43?), silicate (Si(OH)4), dissolved inorganic carbon (DIC), total dissolved iron (Fe) and total dissolved manganese (Mn) was studied at three different stations in the Gulf of Finland (GoF), Baltic Sea during three cruises in June–July 2003, September 2004 and May 2005. The stations were situated

Elin Almroth; Anders Tengberg; Johan H. Andersson; Svetlana Pakhomova; Per O. J. Hall

2009-01-01

202

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

203

Variations of chemical forms of iron, manganese and zinc in suspended sediments from the Elbe and Weser rivers during estuarine mixing  

Microsoft Academic Search

Distribution of iron, manganese and zinc in the easily and moderately reducible phases of suspended solids (determined by sequential leaching with hydroxylamine hydrochloride and oxalate buffer solutions) was compared with the longitudinal profiles of salinity, pH? and Eh?values in the estuarine mixing zone of the Elbe and Weser Rivers in Northern Germany. The ratios of both fractions (FeERP\\/MRP) in the

Jürgen Schoer; Y. T. Hong; Ulrich Förstner

1983-01-01

204

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

PubMed

Recent studies suggested the probable involvement of an apical iron (Fe(2+)) transporter, the divalent metal transporter-1 (DMT1), in the uptake of several divalent metals in fish. The present study examined the gastrointestinal expression of the DMT1 gene, and investigated the kinetics of Fe(2+) uptake and its interactions with cadmium and lead in isolated enterocytes of freshwater rainbow trout (Oncorhynchus mykiss). The expressions of two DMT1 isoforms (Nramp-beta and -gamma) were recorded along the entire gastrointestinal tract of fish as well as in the enterocytes. Fe(2+) uptake in isolated enterocytes was saturable and sensitive to the proton gradient and membrane potential, suggesting DMT1-mediated transport. Both cadmium and lead inhibited Fe(2+) uptake in isolated enterocytes in a concentration-dependent manner, and lead appeared to be a stronger inhibitor than cadmium. The kinetic characterization of Fe(2+) uptake revealed that the apparent affinity of uptake was significantly decreased (increased K(m)) in the presence of either cadmium or lead, whereas the maximum uptake rate (J(max)) remained unchanged-indicating that the interaction between Fe(2+) and cadmium or lead is competitive in nature. Overall, our study suggests that the uptake of dietary cadmium and lead may occur via the iron-transporting pathway in fish. PMID:20541816

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

2010-09-01

205

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

NASA Astrophysics Data System (ADS)

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

Jia, K.; Beckie, R. D.

2013-12-01

206

Alterations of serum zinc, copper, manganese, iron, calcium, and magnesium concentrations and the complexity of interelement relations in patients with obsessive-compulsive disorder.  

PubMed

The purpose of the present study was to evaluate the status of serum trace elements: zinc, copper, manganese, iron, calcium, and magnesium concentrations in obsessive-compulsive disorder patients. Forty-eight obsessive-compulsive disorder patients and 48 healthy volunteers were included in this study. Patients were recruited from Bangabandhu Sheikh Mujib Medical University by random sampling. Serum trace element concentrations were determined using flame atomic absorption spectroscopy (for zinc, copper, iron, calcium, and magnesium) as well as graphite furnace atomic absorption spectroscopy (for manganese). Data were analyzed using independent t test, Pearson's correlation analysis, regression analysis, and ANOVA. Statistical analysis of these data showed a definite pattern of variation among certain elements in patients with obsessive-compulsive disorder compared to controls. In patients' serum, zinc, iron, and magnesium concentrations decreased significantly (p<0.05) compared to the controls. Serum manganese and calcium concentrations were significantly higher (p<0.05) in patients compared to the controls. These data showed a definite imbalance in the interelement relations in obsessive-compulsive disorder patients compared to controls and therefore suggest a disturbance in the element homeostasis. PMID:22383079

Shohag, Hasanuzzaman; Ullah, Ashik; Qusar, Shalahuddin; Rahman, Mustafizur; Hasnat, Abul

2012-09-01

207

Distribution and genetic diversity of the microorganisms in the biofilter for the simultaneous removal of arsenic, iron and manganese from simulated groundwater.  

PubMed

A biofilter was developed in this study, which showed an excellent performance with the simultaneous removal of AsIII from 150 to 10mg L(-1) during biological iron and manganese oxidation. The distribution and genetic diversity of the microorganisms along the depth of the biofilter have been investigated using DGGE. Results suggested that Iron oxidizing bacteria (IOB, such as Gallionella, Leptothrix), Manganese oxidizing bacteria (MnOB, such as Leptothrix, Pseudomonas, Hyphomicrobium, Arthrobacter) and AsIII-oxidizing bacteria (AsOB, such as Alcaligenes, Pseudomonas) are dominant in the biofilter. The spatial distribution of IOB, MnOB and AsOB at different depths of the biofilter determined the removal zone of FeII, MnII and AsIII, which site at the depths of 20, 60 and 60cm, respectively, and the corresponding removal efficiencies were 86%, 84% and 87%, respectively. This process shows great potential to the treatment of groundwater contaminated with iron, manganese and arsenic due to its stable performance and significant cost-savings. PMID:24507582

Yang, Liu; Li, Xiangkun; Chu, Zhaorui; Ren, Yuhui; Zhang, Jie

2014-03-01

208

Trithiocyanurate complexes of iron, manganese and nickel and their anticholinesterase activity.  

PubMed

The complexes of Fe(II), Mn(II) and Ni(II) with a combination of a Schiff base, nitrogen-donor ligand or macrocyclic ligand and trithiocyanuric acid (ttcH3) were prepared and characterized by elemental analysis and spectroscopies. Crystal and molecular structures of the iron complex of composition [Fe(L1)](ttcH2)(ClO4)·EtOH·H2O (1), where L1 is Schiff base derived from tris(2-aminoethyl)amine and 2-pyridinecarboxaldehyde, were solved. It was found that the Schiff base is coordinated to the central iron atom by six nitrogens forming deformed octahedral arrangement, whereas trithiocyanurate(1-) anion, perchlorate and solvent molecules are not coordinated. The X-ray structure of the Schiff base sodium salt is also presented and compared with the iron complex. The anticholinesterase activity of the complexes was also studied. PMID:24717551

Kopel, Pavel; Dolezal, Karel; Langer, Vratislav; Jun, Daniel; Adam, Vojtech; Kuca, Kamil; Kizek, Rene

2014-01-01

209

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

SciTech Connect

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

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

1985-04-01

210

Investigation of Wear Resistance of Austenitic Manganese Cast Iron During Sliding Friction Without a Lubricant.  

National Technical Information Service (NTIS)

A study was made of the wear resistance of an austenitic Mn cast iron contg. total C 3.50, combined C 1.12, graphitic C 2.38, Mn 10.67, Si 3.69, P O. 135, and S O. 021 percent in conditions of sliding friction without lubricant under a specific pressure o...

L. Bon-Gir

1970-01-01

211

Iron deficiency enhances cadmium uptake and translocation mediated by the Fe transporters OsIRT1 and OsIRT2 in rice  

Microsoft Academic Search

Cadmium (Cd) accumulation in rice grains is enhanced if ponded water is released from paddy fields during the reproductive stage (intermittent irrigation). The release of ponded water creates aerobic soil conditions under which Cd becomes soluble and iron (Fe) solubility decreases. We hypothesized that Fe shortage in rice induces Fe uptake and translocation and that Cd is also taken up

Hiromi Nakanishi; Ippei Ogawa; Yasuhiro Ishimaru; Satoshi Mori; Naoko K. Nishizawa

2006-01-01

212

Evaluation of air sparging and vadose zone aeration for remediation of iron and manganese-impacted groundwater at a closed municipal landfill.  

PubMed

High concentrations of iron (Fe(II)) and manganese (Mn(II)) reductively dissolved from soil minerals have been detected in groundwater monitoring wells near many municipal solid waste landfills. Air sparging and vadose zone aeration (VZA) were evaluated as remedial approaches at a closed, unlined municipal solid waste landfill in Florida, USA. The goal of aeration was to oxidize Fe and Mn to their respective immobile forms. VZA and shallow air sparging using a partially submerged well screen were employed with limited success (Phase 1); decreases in dissolved iron were observed in three of nine monitoring wells during shallow air sparging and in two of 17 wells at VZA locations. During Phase 2, where deeper air sparging was employed, dissolved iron levels decreased in a significantly greater number of monitoring wells surrounding injection points, however no radial pattern was observed. Additionally, in wells affected positively by air sparging (mean total iron (FeTOT) <4.2mg/L, after commencement of air sparging), rising manganese concentrations were observed, indicating that the redox potential of the groundwater moved from an iron-reducing to a manganese-reducing environment. The mean FeTOT concentration observed in affected monitoring wells throughout the study was 1.40mg/L compared to a background of 15.38mg/L, while the mean Mn concentration was 0.60mg/L compared to a background level of 0.27mg/L. Reference wells located beyond the influence of air sparging areas showed little variation in FeTOT and Mn, indicating the observed effects were the result of air injection activities at study locations and not a natural phenomenon. Air sparging was found effective in intercepting plumes of dissolved Fe surrounding municipal landfills, but the effect on dissolved Mn was contrary to the desired outcome of decreased Mn groundwater concentrations. PMID:24704954

Pleasant, Saraya; O'Donnell, Amanda; Powell, Jon; Jain, Pradeep; Townsend, Timothy

2014-07-01

213

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

214

Rapid Removal and Separation of Iron(II) and Manganese(II) from Micropolluted Water Using Magnetic Graphene Oxide.  

PubMed

A novel two-dimensional carbon-based magnetic nanomaterial, magnetic graphene oxide (MGO), was prepared and then used as an efficient adsorbent. MGO showed rapid and complete removal of iron(II) (Fe) and manganese(II) (Mn) from micropolluted water bodies over a wide pH range. After saturated adsorption, MGO could be rapidly separated from water under an external magnetic field. Results of the adsorption equilibrium study indicated that the adsorption of Fe and Mn by MGO took place via monolayer heterogeneous and spontaneous processes resulting from the heterogeneity of the MGO surface as well as from the electrostatic interactions between surface acidic groups of MGO and metal ions. In addition, both the Fe and Mn uptake of MGO was very slightly affected by NaCl, although it decreased with increased humic acid in solutions. In an Fe/Mn binary aqueous system, both metal ions can be efficiently removed at low concentrations, but MGO showed preferential adsorption of Fe in a concentrated aqueous mixture. The adsorption behavior in the binary system was due to different affinities of surface oxygen-containing functional groups on MGO to Fe and Mn. Finally, unlike traditional approaches in recycling and reusing an adsorbent, the Fe- and Mn-loaded MGO can be directly applied as a new adsorbent to achieve the efficient removal of fluoride from aqueous solutions. PMID:24787443

Yan, Han; Li, Haijiang; Tao, Xue; Li, Kun; Yang, Hu; Li, Aimin; Xiao, Shoujun; Cheng, Rongshi

2014-06-25

215

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

216

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

217

Bioavailability of Iron, Lead, and Cadmium Via Gastrointestinal Absorption: A Review.  

National Technical Information Service (NTIS)

Numerous factors may act to increase or decrease the biologic availability of heavy metals. The precise mechanisms controlling gastrointestinal absorption are unknown, even for an essential element as extensively studied as iron. For iron there is substan...

H. A. Ragan

1981-01-01

218

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

PubMed Central

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

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

2008-01-01

219

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

SciTech Connect

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

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

1992-02-01

220

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

USGS Publications Warehouse

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

Whitney, P. R.

1975-01-01

221

Iron as a possible aggravating factor for osteopathy in itai-itai disease, a disease associated with chronic cadmium intoxication  

SciTech Connect

Itai-itai disease is thought to be the result of chronic cadmium (Cd) intoxication. We examined 23 autopsy cases of itai-itai disease and 18 cases of sudden death as controls. Urine and blood samples from 10 patients were collected before they died and revealed the presence of severe anemia and renal tubular injuries. Undecalcified sections of iliac bone were stained with Aluminon reagent, and ammonium salt of aurintricarboxylic acid, and Prussian blue reagent in all cases of itai-itai disease. These two reagents reacted at the same mineralization fronts. X-ray microanalysis revealed the presence of iron at mineralization fronts in itai-itai disease. Five patients showed evidence of hemosiderosis in the liver, spleen, and pancreas, probably as a result of post transfusion iron overload. Renal calculi and calcified aortic walls were also stained with Prussian blue reagent in several patients. Neither ferritin nor transferrin were visualized at mineralization fronts in itai-itai disease by immunohistochemical staining. These results suggest that iron is bound to calcium or to calcium phosphate by a physicochemical reaction. A marked osteomalacia was observed in 10 cases of itai-itai disease by histomorphometry. Regression analyses of data from cases of itai-itai disease suggested that an Aluminon-positive metal inhibited mineralization and that renal tubules were injured. Since bone Cd levels were increased in itai-itai disease, it is likely that renal tubules were injured by exposure to Cd. Therefore, stainable bone iron is another possible aggravating factor for osteopathy in itai-itai disease, and a synergistic effect between iron and Cd on mineralization is proposed.

Noda, M.; Yasuda, M.; Kitagawa, M. (Toyama Medical and Pharmaceutical Univ. (Japan))

1991-03-01

222

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

PubMed

Lipoxygenases (LOX) oxidize polyunsaturated fatty acids to hydroperoxides, which are generated by proton coupled electron transfer to the metal center with Fe(III)OH(-) or Mn(III)OH(-). Hydrogen abstraction by Fe(III)OH(-) of soybean LOX-1 (sLOX-1) is associated with a large deuterium kinetic isotope effect (D-KIE). Our goal was to compare the D-KIE and other kinetic parameters at different temperatures of sLOX-1 with 13R-LOX with catalytic manganese (13R-MnLOX). The reaction rate and the D-KIE of sLOX-1 with unlabeled and [11-(2)H2]18:2n-6 were almost temperature independent with an apparent D-KIE of ?56 at 30°C, which is in agreement with previous studies. In contrast, the reaction rate of 13R-MnLOX increased 7-fold with temperature (8-50°C), and the apparent D-KIE decreased linearly from ?38 at 8°C to ?20 at 50°C. The kinetic lag phase of 13R-MnLOX was consistently extended at low temperatures. The Phe337Ile mutant of 13R-MnLOX, which catalyzes antarafacial hydrogen abstraction and oxygenation in analogy with sLOX-1, retained the large D-KIE and its temperature-dependent reaction rate. The kinetic differences between13R-MnLOX and sLOX-1 may be due to protein dynamics, hydrogen donor-acceptor distances, and to the metal ligands, which may not equalize the 0.7V-gap between the redox potentials of the free metals. PMID:24857825

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

2014-08-01

223

The Abundance of Iron-Peak Elements and the Dust Composition in eta Carinae: Manganese  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

224

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

USGS Publications Warehouse

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

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

2014-01-01

225

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

PubMed Central

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

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

2014-01-01

226

Zinc, Iron, Manganese and Copper Uptake Requirement in Response to Nitrogen Supply and the Increased Grain Yield of Summer Maize  

PubMed Central

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

Xue, Yanfang; Yue, Shanchao; Zhang, Wei; Liu, Dunyi; Cui, Zhenling; Chen, Xinping; Ye, Youliang; Zou, Chunqin

2014-01-01

227

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

PubMed

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

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

2014-01-01

228

Reactive iron and manganese distributions in seabed sediments near small mountainous rivers off Oregon and California (USA)  

NASA Astrophysics Data System (ADS)

We examined the spatial distribution of sedimentary reactive iron (FeR) and manganese (MnR) along the continental shelf near the mouth of the Umpqua River, Oregon (USA). A well-defined muddy (silt+clay) depocenter of fluvial origin characterizes this part of the Oregon margin. Reactive Fe and Mn contents are elevated within the silt-rich landward edge of the depocenter. Away from this depocenter, sediments are predominantly sandy both along the inner-shelf (<˜100 m depth) and mid-shelf (˜100-150 m depth) and have lower concentrations of reactive metals compared to the depocenter. Sediments are also muddy along the slope (>˜150 m depth) and have elevated FeR and MnR. Based on their correlation with sediment grain size, it appears that FeR and to a lesser extent MnR, are associated with mud size sediments. Reactive metal concentration is also positively correlated with organic carbon (OC) content, indicating a potentially common source. Seabed sediments from five other small, mountainous river systems (Klamath, Eel, Navarro, Russian, and Salinas) located south of Umpqua show the same general relationship between FeR and OC. Although both FeR and MnR exhibit similar relationships to grain size and OC, the relationships with MnR exhibit considerable scatter. Comparison of Umpqua River suspended sediment data with the seabed data suggests that MnR is more prone to loss from sediment particles during transit to the seabed as compared to FeR, and this difference explains why FeR maintains a reasonably tight relationship with organic carbon and particle size along the seafloor relative to MnR.

Roy, Moutusi; McManus, James; Goñi, Miguel A.; Chase, Zanna; Borgeld, Jeffry C.; Wheatcroft, Robert A.; Muratli, Jesse M.; Megowan, Meghan R.; Mix, Alan

2013-02-01

229

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

PubMed Central

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

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

2014-01-01

230

THE DETERMINATION OF ALUMINUM, IRON, AND SILICON IN SILVER-CADMIUM-INDIUM ALLOYS  

Microsoft Academic Search

Aluminum, iron, and silicon were determined by standard procedures with ; the modifications required by the nature of the matrix material. Aluminum and ; iron were determined colorimetrically wiih 8-quinolinol and orthophenanthrolene, ; reapectively, after appropriate separations. Silicon was determined ; gravimetrically. The methods have been tested on synthetic samples of known ; corposition and found to give acceptable results.

Ciaranello

1959-01-01

231

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

232

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

PubMed

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

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

2014-01-27

233

Hydrochloric acid (0.1M) and dtpa extractable and total iron and manganese in basaltic soil profiles of the Nigerian savanna  

Microsoft Academic Search

The contents of 0.1 M HCl and DTPA extractable and total iron (Fe) and manganese (Mn) were determined in soil profiles developed on four groups of basaltic parent materials, namely, the Newer?, Older?, Lateritized?Older?, and Biu?basalts. HCl?and DTPA?extractable and total Fe in the soils ranged from 15.0 to 66.3 mg\\/kg, 1.1 to 26. 7 mg\\/kg, and 4.50 to 10.50%, respectively,

T. Kparmwang; V. O. Chude; I. E. Esu

1995-01-01

234

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

235

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

PubMed

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

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

2002-01-01

236

Anti-oxidant and pro-oxidant reactivities of copper(II), manganese(II) and iron(III) 3,5-di- i -propylsalicylate chelates during peroxidation of alkylbenzenes  

Microsoft Academic Search

Bioactive copper(II), iron(III), and manganese(II) 3,5-di-i-propylsalicylate (3,5-DIPS) chelates were investigated in order to determine their ability to inhibit the free radical initiated chain reactions leading to the peroxidation of isopropylbenzene (i-PrPh) and ethylbenzene (EtPh). Quantitative kinetic studies of these chelates established the following order of anti-oxidant reactivities: manganese(II)-(3,5-DIPS)2>iron(III)(3,5-DIPS)3>copper(II)2(3,5-DIPS)4> > 3,5-DIPS acid. The mechanism of anti-oxidant reactivity of these three chelates

Levon A. Tavadyan; Gegham Z. Sedrakyan; Seyran H. Minasyan; Frederick T. Greenaway; John R. J. Sorenson

2004-01-01

237

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

2013-03-01

238

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

239

Electronic structures of iron(III) and manganese(IV) (hydr)oxide minerals: Thermodynamics of photochemical reductive dissolution in aquatic environments  

NASA Astrophysics Data System (ADS)

Sunlight-induced reduction and dissolution of colloidal Fe-Mn (hydr)oxide minerals yields elevated concentrations of Fe 2+ and Mn 2+ in natural waters. Since these elements may be biolimiting micronutrients, photochemical reactions might play a significant role in biogeochemical cycles. Reductive photodissolution of Fe (hydr)oxide minerals may also release sorbed metals. The reactivity of Fe-Mn (hydr)oxide minerals to sunlight-induced photochemical dissolution is determined by the electronic structure of the mineral-water interface. In this work, oxygen K-edge absorption and emission spectra were used to determine the electronic structures of iron(III) (hydr)oxides (hematite, goethite, lepidocrocite, akaganeite and schwertmannite) and manganese(IV) oxides (pyrolusite, birnessite, cryptomelane). The band gaps in the iron(III) (hydr)oxide minerals are near 2.0-2.5 eV; the band gaps in the manganese (IV) oxide phases are 1.0-1.8 eV. Using published values for the electrochemical flat-band potential for hematite together with experimental pH pzc values for the (hydr)oxides, it is possible to predict the electrochemical potentials of the conduction and valence bands in aqueous solutions as a function of pH. The band potentials enable semiquantitative predictions of the susceptibilities of these minerals to photochemical dissolution in aqueous solutions. At pH 2 (e.g., acid-mine waters), photoreduction of iron(III) (hydr)oxides could yield millimolal concentrations of aqueous Fe 2+ (assuming surface detachment of Fe 2+ is not rate limiting). In seawater (pH 8.3), however, the direct photo-reduction of colloidal iron(III) (hydr)oxides to give nanomolal concentrations of dissolved, uncomplexed, Fe 2+ is not thermodynamically feasible. This supports the hypothesis that the apparent photodissolution of iron(III) (hydr)oxides in marines systems results from Fe 3+ reduction by photochemically produced superoxide. In contrast, the direct photoreduction of manganese oxides should be energetically feasible at pH 2 and 8.3.

Sherman, David M.

2005-07-01

240

Cloud point extraction and graphite furnace atomic absorption spectrometry determination of manganese(II) and iron(III) in water samples.  

PubMed

Cloud point extraction (CPE) was applied as a preconcentration step prior to graphite furnace atomic absorption spectrometry (GFAAS) determination of manganese(II) and iron(III) in water samples. After complexation with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), the analytes could be quantitatively extracted to the phase rich in the surfactant p-octylpolyethyleneglycolphenylether (Triton X-100) and be concentrated, then determined by GFAAS. The parameters affecting the extraction efficiency, such as solution pH, concentration of PMBP and Triton X-100, equilibration temperature and time, were investigated in detail. Under the optimum conditions, preconcentration of 10 ml of sample solution permitted the detection of 0.02 ng ml(-1) of Mn(II) and 0.08 ng ml(-1) of Fe(III) with enrichment factors of 31 and 25 for Mn(II) and Fe(III), respectively. The proposed method was applied to determination of trace manganese(II) and iron(III) in water samples with satisfactory results. PMID:17010364

Liang, Pei; Sang, Hongbo; Sun, Zhimei

2006-12-15

241

KEY COMPARISON: Final report on key comparison CCQM-K42: Determination of chromium, copper, iron, manganese and zinc in aluminium alloy  

NASA Astrophysics Data System (ADS)

The CCQM key comparison K42 was organized by the inorganic analysis working group of CCQM to test the abilities of metrological institutes to measure the mass fractions of the components of an aluminium alloy. Chosen elements were chromium (Cr), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn). The BAM Federal Institute for Materials Research and Testing (BAM Bundesanstalt für Materialforschung und -prüfung) in Berlin, Germany acted as the pilot laboratory. CCQM-K42 demonstrates the abilities of metrological institutes to measure the mass fractions of minor and trace components (mass content about 0.05% to 0.2%) of an aluminium alloy for chromium (Cr), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn). The analytical methods used were neutron activation analysis (NAA), x-ray fluorescence spectrometry (XRF) using the reconstitution technique, ICP-OES and ICP-MS. The scope of the key comparison extends to non-ferrous alloys comprising the same or similar constituents when analysed using the technique(s) applied by a participant in obtaining the results submitted for CCQM-K42. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Noack, Siegfried; Matschat, Ralf

2008-01-01

242

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--(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

2013-01-01

243

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

PubMed

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

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

2014-07-01

244

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

NASA Astrophysics Data System (ADS)

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 ?g g -1 DW) than in the central GBR lagoon (Fe range: 4.0-40.0 mg g -1 DW; Mn range: 99-496 ?g g -1 DW), reflecting generally smaller grain size and higher rates of terrigenous runoff from the Fly River and associated river systems onto the adjacent Papuan shelf as well as dilution by calcium carbonate and a decline in terrestrial input across the GBR shelf. Dissolved metal concentrations in the porewaters were usually very low (Fe range: 0.1-28.0 ?M; Mn range: 0.1-97.0 ?M) and not significantly different between shelves. Vertical profiles of dissolved and solid-phase Fe and Mn either did not vary with sediment depth or were irregular at most stations. The dissolved Mn/Fe (molar) ratio varied greatly among stations, but was generally higher in the Papuan sediments (range: 1.2-46.4) than in the GBR deposits (range: 0.3-18.1). The solid-phase Mn/Fe (molar) ratio varied little among stations, ranging from 0.01 to 0.03. Solid-phase metal concentrations correlated negatively with calcium carbonate content. When this relationship was held constant (partial correlation analysis), solid-phase Fe and Mn correlated negatively with grain size and positively with total N (Fe only) and P. Metal solutes in the porewater correlated negatively with redox potential and grain size (Mn only) and positively with porewater NH 4+ (Mn only). Rates of Fe and Mn solute flux across the sediment-water interface were, at most stations, undetectable. Measurable fluxes ranged from -609 to +125 ?mol m -2 day -1 for iron and from -218 to +400 ?mol m -2 day -1 for manganese. The distribution and diagenesis of Fe and Mn in these tropical shelf sediments are more similar to their behavior in hemipelagic and pelagic deep-sea clays than in sediments of comparable grain size on temperate shelves. The lack of vertical structure, low porewater concentrations, and undetectable or slow rates of sediment-water solute exchange at most stations may be attributed to several factors, including moderate redox conditions, low reactivity of advected detritus, moderate to high production rates of hydrolytic and fermentative bacteria, and frequent physical disturbances.

Alongi, Daniel M.; Tirendi, Frank; Christoffersen, Paul

1993-02-01

245

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

246

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

2012-05-01

247

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

Microsoft Academic Search

Highly divided iron manganese oxide powders, Fe{sub 3-x}Mn{sub x{open_square}{sub 3δ\\/4}}O{sub 4+δ}, were prepared at low temperature (T ⤠560 C) by the thermal decomposition of mixed oxalate precursors Fe{sub 1-α}Mn{sub α}CâOâ, 2HâO (α = x\\/3). The manganese-rich compounds (x ⥠1.5) have a complex structure that can be cubic, tetragonal, or a mixture of both tetragonal and cubic spinel phases

S. Guillemet-Fritsch; S. Viguie; A. Rousset

1999-01-01

248

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

PubMed

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

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

2009-03-01

249

[Certain inhibitors of proteolysis in blood serum of workers engaged in production of iron-manganese alloys].  

PubMed

In metallurgic workers exposed to manganese, ferric oxides, chromates, noise, thermal radiation and enhanced temperature in surroundings, a lower level of alpha 2-macroglobulin at an unlowered level of alpha 1-antitrypsin was observed. There was no relationship between either the length of employment or chronic bronchitis and level of alpha 1-antitrypsin and alpha 2-macroglobulin in the blood of workers under study. PMID:7516462

Misiewicz, A; Warkocka-Szo?tysek, B; Radwan, K; Dziewit, T; Gonciarz, R

1994-01-01

250

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

251

Molecular mechanism of distorted iron regulation in the blood-CSF barrier and regional blood-brain barrier following in vivo subchronic manganese exposure  

PubMed Central

Previous studies in this laboratory indicated that manganese (Mn) exposure in vitro increases the expression of transferrin receptor (TfR) by enhancing the binding of iron regulatory proteins (IRPs) to iron responsive element-containing RNA. The current study further tested the hypothesis that in vivo exposure to Mn increased TfR expression at both blood–brain barrier (BBB) and blood–cerebrospinal fluid (CSF) barrier (BCB), which contributes to altered iron (Fe) homeostasis in the CSF. Groups of rats (10–11 each) received oral gavages at doses of 5 mg Mn/kg or 15 mg Mn/kg as MnCl2 once daily for 30 days. Blood, CSF, and choroid plexus were collected and brain capillary fractions were separated from the regional parenchyma. Metal analyses showed that oral Mn exposure decreased concentrations of Fe in serum (?66%) but increased Fe in the CSF (+167%). Gel shift assay showed that Mn caused a dose-dependent increase of binding of IRP1 to iron responsive element-containing RNA in BCB in the choroid plexus (+70%), in regional BBB of capillaries of striatum (+39%), hippocampus (+56%), frontal cortex (+49%), and in brain parenchyma of striatum (+67%), hippocampus (+39%) and cerebellum (+28%). Real-time RT-PCR demonstrated that Mn exposure significantly increased the expression of TfR mRNA in choroid plexus and striatum with concomitant reduction in the expression of ferritin (Ft) mRNA. Collectively, these data indicate that in vivo Mn exposure results in Fe redistribution in body fluids through regulating the expression of TfR and ferritin at BCB and selected regional BBB. The disrupted Fe transport by brain barriers may underlie the distorted Fe homeostasis in the CSF.

Li, G. Jane; Choi, Byung-Sun; Wang, Xueqian; Liu, Jie; Waalkes, Michael P.; Zheng, Wei

2014-01-01

252

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

253

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

SciTech Connect

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

Tatum, T.L.

1992-01-01

254

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

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

255

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

NASA Astrophysics Data System (ADS)

The effect of resuspension on benthic fluxes of oxygen (O 2), ammonium (NH 4+), nitrate (NO 3-), phosphate (PO 43-), silicate (Si(OH) 4), dissolved inorganic carbon (DIC), total dissolved iron (Fe) and total dissolved manganese (Mn) was studied at three different stations in the Gulf of Finland (GoF), Baltic Sea during three cruises in June-July 2003, September 2004 and May 2005. The stations were situated on different bottom types in the western, central and eastern part, respectively, of the open GoF. The fluxes were measured in-situ using the autonomous Göteborg benthic lander. To simulate resuspension events, the stirring speed was increased in two of the four chambers of the lander after approximately half of the incubation time. The other two chambers were used as control chambers. Clear effects of resuspension were observed on the oxygen fluxes where an increase of the consumption was observed in 88% of the cases and on average with 59% (stdev=53). The NH 4+ fluxes were affected in 50% of the cases (4 out of 8 incubations) at stations with low bottom water oxygen concentrations, but in no cases where the bottom water was oxygenated (0 out of 9 incubations). The NH 4+ fluxes decreased by 26±27% in 2005 and by 114±19% in 2003. There was no clear effect of resuspension on the fluxes of any of the other solutes in this study. Thus, resuspension events did not play a significant role in release/uptake of NO 3-, PO 43-, Si(OH) 4, DIC, Fe and Mn in GoF sediments. However, increased oxygen consumption as a result of resuspension may lead to spreading of anoxic/suboxic bottom water conditions, and thus indirectly to increased benthic release of phosphate, ammonium and iron.

Almroth, Elin; Tengberg, Anders; Andersson, Johan H.; Pakhomova, Svetlana; Hall, Per O. J.

2009-03-01

256

Extracellular norepinephrine, norepinephrine receptor and transporter protein and mRNA levels are differentially altered in the developing rat brain due to dietary iron deficiency and manganese exposure.  

PubMed

Manganese (Mn) is an essential trace element, but overexposure is characterized by Parkinson's like symptoms in extreme cases. Previous studies have shown that Mn accumulation is exacerbated by dietary iron deficiency (ID) and disturbances in norepinephrine (NE) have been reported. Because behaviors associated with Mn neurotoxicity are complex, the goal of this study was to examine the effects of Mn exposure and ID-associated Mn accumulation on NE uptake in synaptosomes, extracellular NE concentrations, and expression of NE transport and receptor proteins. Sprague-Dawley rats were assigned to four dietary groups: control (CN; 35 mg Fe/kg diet), iron-deficient (ID; 6 mg Fe/kg diet), CN with Mn exposure (via the drinking water; 1 g Mn/L) (CNMn), and ID with Mn (IDMn). (3)H-NE uptake decreased significantly (R=-0.753, p=0.001) with increased Mn concentration in the locus coeruleus, while decreased Fe was associated with decreased uptake of (3)H-NE in the caudate putamen (R=0.436, p=0.033) and locus coeruleus (R=0.86; p<0.001). Extracellular concentrations of NE in the caudate putamen were significantly decreased in response to Mn exposure and ID (p<0.001). A diverse response of Mn exposure and ID was observed on mRNA and protein expression of NE transporter (NET) and alpha(2) adrenergic receptor. For example, elevated brain Mn and decreased Fe caused an approximate 50% decrease in NET and alpha(2) adrenergic receptor protein expression in several brain regions, with reductions in mRNA expression also observed. These data suggest that Mn exposure results in a decrease in NE uptake and extracellular NE concentrations via altered expression of transport and receptor proteins. PMID:19481535

Anderson, Joel G; Fordahl, Steven C; Cooney, Paula T; Weaver, Tara L; Colyer, Christa L; Erikson, Keith M

2009-07-24

257

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

SciTech Connect

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

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

2008-01-15

258

The Thermoelectromotive Force of Copper-Manganese Alloys  

Microsoft Academic Search

Thermoelectromotive Force of Alloys of Copper with 5 to 23 Per Cent, Manganese for the Range 0° to 100° C.-The alloys were prepared from electrolytic copper and thermite manganese but contained as impurity about one fiftieth as much iron as manganese. The alloys were cast and then drawn to fine wires. After they had been annealed at 200° C. for

Skezug Kimura; Zunehachi Isawa

1922-01-01

259

Iron  

Microsoft Academic Search

Iron poisoning causes its metabolic effects in proportion to the concentrations of free iron. Toxicity is therefore related to dose ingested. The amount of iron in different salts varies, and iron concentrations may rise and fall, making plasma concentrations difficult to interpret in acute poisoning. Clinical features include severe gastrointestinal irritation, cardiovascular collapse and direct organ damage to liver and

D. Nicholas Bateman

2007-01-01

260

Cadmium and iron-stress-inducible gene expression in the green alga Chlamydomonas reinhardtii : evidence for H43 protein function in iron assimilation  

Microsoft Academic Search

Early transcriptional responses of a cell wall-deficient mutant of the green alga Chlamydomonas reinhardtii to heavy-metal stress have been investigated using the method of mRNA differential display. We have identified, sequenced, and quantified the induction of a number of transcripts that are up-regulated by a brief (2-h) exposure to 25 µm cadmium chloride, including one transcript which is also highly

Peter Rubinelli; Surasak Siripornadulsil; Fei Gao-Rubinelli; Richard T. Sayre

2002-01-01

261

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

PubMed

The United States Clean Air Act Amendments of 1990 reflected increasing concern about potential effects of low-level airborne metal exposure on a wide array of illnesses. Here we summarize results demonstrating that the New York City (NYC) subway system provides an important microenvironment for metal exposures for NYC commuters and subway workers and also describe an ongoing pilot study of NYC transit workers' exposure to steel dust. Results from the TEACH (Toxic Exposure Assessment, a Columbia and Harvard) study in 1999 of 41 high-school students strongly suggest that elevated levels of iron, manganese, and chromium in personal air samples were due to exposure to steel dust in the NYC subway. Airborne concentrations of these three metals associated with fine particulate matter were observed to be more than 100 times greater in the subway environment than in home indoor or outdoor settings in NYC. While there are currently no known health effects at the airborne levels observed in the subway system, the primary aim of the ongoing pilot study is to ascertain whether the levels of these metals in the subway air affect concentrations of these metals or related metabolites in the blood or urine of exposed transit workers, who due to their job activities could plausibly have appreciably higher exposures than typical commuters. The study design involves recruitment of 40 transit workers representing a large range in expected exposures to steel dust, the collection of personal air samples of fine particulate matter, and the collection of blood and urine samples from each monitored transit worker. PMID:15738337

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

2005-03-01

262

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

263

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

USGS Publications Warehouse

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

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

2012-01-01

264

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

NASA Astrophysics Data System (ADS)

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

Tresintsi, Sofia; Simeonidis, Konstantinos; Mitrakas, Manassis

2013-04-01

265

Accumulation and distribution of iron, cadmium, lead and nickel in cucumber plants grown in hydroponics containing two different chelated iron supplies.  

PubMed

Cucumber plants grown in hydroponics containing 10 ?M Cd(II), Ni(II) and Pb(II), and iron supplied as Fe(III) EDTA or Fe(III) citrate in identical concentrations, were investigated by total-reflection X-ray fluorescence spectrometry with special emphasis on the determination of iron accumulation and distribution within the different plant compartments (root, stem, cotyledon and leaves). The extent of Cd, Ni and Pb accumulation and distribution were also determined. Generally, iron and heavy-metal contaminant accumulation was higher when Fe(III) citrate was used. The accumulation of nickel and lead was higher by about 20% and 100%, respectively, if the iron supply was Fe(III) citrate. The accumulation of Cd was similar. In the case of Fe(III) citrate, the total amounts of Fe taken up were similar in the control and heavy-metal-treated plants (27-31 ?mol/plant). Further, the amounts of iron transported from the root towards the shoot of the control, lead- and nickel-contaminated plants were independent of the iron(III) form. Although Fe mobility could be characterized as being low, its distribution within the shoot was not significantly affected by the heavy metals investigated. PMID:21342715

Csog, Árpád; Mihucz, Victor G; Tatár, Eniko; Fodor, Ferenc; Virág, István; Majdik, Cornelia; Záray, Gyula

2011-07-01

266

MODIFYING IRON REMOVAL PROCESSES TO INCREASE ARSENIC REMOVAL  

EPA Science Inventory

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

267

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

268

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

2010-12-15

269

Manganese and iron porphyrins catalyze peroxynitrite decomposition and simultaneously increase nitration and oxidant yield: implications for their use as peroxynitrite scavengers in vivo.  

PubMed

Twelve substituted metalloporphyrins (MPs), some of which have been previously characterized with respect to superoxide dismutase and peroxynitrite decomposing activities, were evaluated for their ability to scavenge peroxynitrite in vitro at 37 degrees C. Because the overall effectiveness of MPs as catalytic peroxynitrite scavengers is a function of (1) how fast they react with peroxynitrite, (2) how fast they cycle back to the starting compound, and (3) how well they contain or quench the reactive intermediates generated, all of these properties were evaluated and compared directly under the same conditions. Of the various MPs tested, only the iron and manganese porphyrins showed significant reactivity with peroxynitrite. The Mn(IV) intermediates resulting from oxidation by peroxynitrite were relatively stable and rereduction to the Mn(III) forms was rate-limiting to catalytic decomposition of peroxynitrite. However, in the presence of oxidizeable substrates like phenolics, rereduction of Mn(IV) forms occurred very rapidly and both the Mn- and Fe-porphyrins catalyzed nitration and oxidation by peroxynitrite. Mn- and Fe-porphyrins enhanced the yield of nitrated phenolics by peroxynitrite as much as 5-fold at pH 7.4 and up to 12-fold at pH 9. 1, while total oxidative yield was more than doubled. Nitration enhancement by MPs was effectively inhibited by ascorbate, glutathione, or serum, although much higher concentrations of ascorbate were required to inhibit nitration catalyzed by either Mn or Fe tetramethylpyridyl porphyrin. Catalysis of peroxynitrite nitration by MPs appears to proceed via a radical-mediated reaction mechanism whereby the phenolic substrate rapidly reduces Mn(IV) = O or Fe[IV] = O to the +3 state to yield phenoxyl radical which then combines with the other primary product, nitrogen dioxide. Based on the rate constants and the proposed reaction mechanism, it is reasonable to suggest that Mn and Fe porphyrins could detoxify peroxynitrite in vivo by efficiently trapping the relatively unreactive peroxynitrite anion and, in effect, channeling it into a single reaction pathway which could then be more effectively scavenged by cellular reductants like ascorbate. PMID:10525288

Crow, J P

1999-11-01

270

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

271

Parallels and contrasts between iron and copper metabolism.  

PubMed

This paper reviews the Second International Workshop on Iron and Copper Homeostasis, held in Pucón, Chile 10-13 November, 2001. We cover the presentations and papers published (this issue) with the intent to point out parallels, contrasts and cutting edge areas rather than to say something about every paper. Iron and copper metabolism have been intertwined for nearly 150 years and the interrelationship is growing with advances in understanding the role of ceruloplasmin as one example and the probable role of hephaestin as another. The transporter DMT1 (divalent metal transporter 1) clearly plays a major part in iron uptake and trafficking. Emerging evidence suggests that it plays a lesser role in manganese, cadmium and copper transport; but it is still being evaluated there. Yet another interaction may come from the IRE/IRP (Iron Responsive Element/Iron Regulatory Protein) story where a paradigmatic role in iron homeostasis is well established, but interaction with copper is only now emerging. Parallels include the nutrient status of both metals based on their utility for redox reactions as well as their toxicity primarily via reactive oxygen species. The workshop also revealed that alternate splicing of pre-mRNAs for iron and copper related proteins and tissue specific responses are additional similarities. Regulation of gene expression and excretion offered contrasts between the two metals. The workshop also considered a series of continuing and emerging issues. PMID:12572661

Garrick, Michael D; Núñez, Marco T; Olivares, Manuel; Harris, Edward D

2003-03-01

272

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

273

Identification of rice cultivars with low brown rice mixed cadmium and lead contents and their interactions with the micronutrients iron, zinc, nickel and manganese.  

PubMed

Paddy fields in mining areas are usually co-contaminated by a cocktail of mixed toxic heavy metals (e.g., Cd and Pb in Pb/Zn mines). However, previous studies on rice cultivars screened for effective metal exclusion have mostly focused on individual metals, and have been conducted under pot-trial or hydroponic solution conditions. This study identified rice cultivars with both low Cd and Pb accumulation under Cd- and Pb-contaminated field conditions, and the interactions of the toxic elements Cd and Pb with the micronutrient elements Fe, Zn, Mn and Ni were also studied. Among 32 rice cultivars tested, there were significant differences in Cd (0.06-0.59 mg/kg) and Pb (0.25-3.15 mg/kg) levels in their brown rice, and similar results were also found for the micronutrient elements. Significant decreases in concentrations of Fe and Mn were detected with increasing Cd concentrations and a significant elevation in Fe, Mn and Ni with increasing Pb concentrations. A similar result was also shown by Cd and Ni. Three cultivars were identified with a combination of low brown rice Cd and Pb, high micronutrient and grain yield (Wufengyou 2168, Tianyou 196 and Guinongzhan). Present results suggest that it is possible to breed rice cultivars with low mixed toxic element (Cd, Pb) and high micronutrient contents along with high grain yields, thus ensuring food safety and quality. PMID:23520849

Li, Bing; Wang, Xun; Qi, Xiaoli; Huang, Lu; Ye, Zhihong

2012-01-01

274

[Activity of glucose-6-phosphate dehydrogenase in erythrocytes of workers at the smelting works plant for manufacture of iron and manganese alloys].  

PubMed

Decreased glucose-6-phosphate dehydrogenase activity has been shown in the red cells of workers employed in the works producing ferro-manganese alloys in comparison with that in the control group. Tobacco smoking and duration of the occupation did not affect the activity of glucose-6-phosphate dehydrogenase in red cells. PMID:1669091

Misiewicz, A; Karmoli?ski, M; Radwan, K; Januszewska, B

275

Utilization of hydrogen bonds to stabilize M-O(H) units: synthesis and properties of monomeric iron and manganese complexes with terminal oxo and hydroxo ligands.  

PubMed

Non-heme iron and manganese species with terminal oxo ligands are proposed to be key intermediates in a variety of biological and synthetic systems; however, the stabilization of these types of complexes has proven difficult because of the tendency to form oxo-bridged complexes. Described herein are the design, isolation, and properties for a series of mononuclear Fe(III) and Mn(III) complexes with terminal oxo or hydroxo ligands. Isolation of the complexes was facilitated by the tripodal ligand tris[(N'-tert-butylureaylato)-N-ethyl]aminato ([H(3)1](3-)), which creates a protective hydrogen bond cavity around the M(III)-O(H) units (M(III) = Fe and Mn). The M(III)-O(H) complexes are prepared by the activation of dioxygen and deprotonation of water. In addition, the M(III)-O(H) complexes can be synthesized using oxygen atom transfer reagents such as N-oxides and hydroxylamines. The [Fe(III)H(3)1(O)](2-) complex also can be made using sulfoxides. These findings support the proposal of a high valent M(IV)-oxo species as an intermediate during dioxygen cleavage. Isotopic labeling studies show that oxo ligands in the [M(III)H(3)1(O)](2-) complexes come directly from the cleavage of dioxygen: for [Fe(III)H(3)1(O)](2-) the nu(Fe-(16)O) = 671 cm(-1), which shifts 26 cm(-1) in [Fe(III)H(3)1((18)O)](2-) (nu(Fe-(18)O) = 645 cm(-1)); a nu(Mn-(16)O) = 700 cm(-1) was observed for [Mn(III)H(3)1((16)O)](2-), which shifts to 672 cm(-1) in the Mn-(18)O isotopomer. X-ray diffraction studies show that the Fe-O distance is 1.813(3) A in [Fe(III)H(3)1(O)](2-), while a longer bond is found in [Fe(III)H(3)1(OH)](-) (Fe-O at 1.926(2) A); a similar trend was found for the Mn(III)-O(H) complexes, where a Mn-O distance of 1.771(5) A is observed for [Mn(III)H(3)1(O)](2-) and 1.873(2) A for [Mn(III)H(3)1(OH)](-). Strong intramolecular hydrogen bonds between the urea NH groups of [H(3)1](3-) and the oxo and oxygen of the hydroxo ligand are observed in all the complexes. These findings, along with density functional theory calculations, indicate that a single sigma-bond exists between the M(III) centers and the oxo ligands, and additional interactions to the oxo ligands arise from intramolecular H-bonds, which illustrates that noncovalent interactions may replace pi-bonds in stabilizing oxometal complexes. PMID:14982465

MacBeth, Cora E; Gupta, Rajeev; Mitchell-Koch, Katie R; Young, Victor G; Lushington, Gerald H; Thompson, Ward H; Hendrich, Michael P; Borovik, A S

2004-03-01

276

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

PubMed

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

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

2013-04-01

277

Dried leaves — Novel reductant for acid leaching of manganese ore  

Microsoft Academic Search

In the present investigation results on the use of dried leaves as a reductant for manganese ore leaching is reported. A complete\\u000a flow-sheet consisting of steps such as reductive acid leaching, enrichment of leach solution by recycling, iron removal and\\u000a crystallization has been developed for the preparation of manganese sulphate monohydrate from manganese ore of Gujarat Mineral\\u000a Development Corporation (GMDC),

D. Hariprasad; M. K. Ghosh; S. Anand

2009-01-01

278

Iron, copper, zinc, and manganese transport and regulation in pathogenic Enterobacteria: correlations between strains, site of infection and the relative importance of the different metal transport systems for virulence.  

PubMed

For all microorganisms, acquisition of metal ions is essential for survival in the environment or in their infected host. Metal ions are required in many biological processes as components of metalloproteins and serve as cofactors or structural elements for enzymes. However, it is critical for bacteria to ensure that metal uptake and availability is in accordance with physiological needs, as an imbalance in bacterial metal homeostasis is deleterious. Indeed, host defense strategies against infection either consist of metal starvation by sequestration or toxicity by the highly concentrated release of metals. To overcome these host strategies, bacteria employ a variety of metal uptake and export systems and finely regulate metal homeostasis by numerous transcriptional regulators, allowing them to adapt to changing environmental conditions. As a consequence, iron, zinc, manganese, and copper uptake systems significantly contribute to the virulence of many pathogenic bacteria. However, during the course of our experiments on the role of iron and manganese transporters in extraintestinal Escherichia coli (ExPEC) virulence, we observed that depending on the strain tested, the importance of tested systems in virulence may be different. This could be due to the different set of systems present in these strains, but literature also suggests that as each pathogen must adapt to the particular microenvironment of its site of infection, the role of each acquisition system in virulence can differ from a particular strain to another. In this review, we present the systems involved in metal transport by Enterobacteria and the main regulators responsible for their controlled expression. We also discuss the relative role of these systems depending on the pathogen and the tissues they infect. PMID:24367764

Porcheron, Gaëlle; Garénaux, Amélie; Proulx, Julie; Sabri, Mourad; Dozois, Charles M

2013-01-01

279

Iron, copper, zinc, and manganese transport and regulation in pathogenic Enterobacteria: correlations between strains, site of infection and the relative importance of the different metal transport systems for virulence  

PubMed Central

For all microorganisms, acquisition of metal ions is essential for survival in the environment or in their infected host. Metal ions are required in many biological processes as components of metalloproteins and serve as cofactors or structural elements for enzymes. However, it is critical for bacteria to ensure that metal uptake and availability is in accordance with physiological needs, as an imbalance in bacterial metal homeostasis is deleterious. Indeed, host defense strategies against infection either consist of metal starvation by sequestration or toxicity by the highly concentrated release of metals. To overcome these host strategies, bacteria employ a variety of metal uptake and export systems and finely regulate metal homeostasis by numerous transcriptional regulators, allowing them to adapt to changing environmental conditions. As a consequence, iron, zinc, manganese, and copper uptake systems significantly contribute to the virulence of many pathogenic bacteria. However, during the course of our experiments on the role of iron and manganese transporters in extraintestinal Escherichia coli (ExPEC) virulence, we observed that depending on the strain tested, the importance of tested systems in virulence may be different. This could be due to the different set of systems present in these strains, but literature also suggests that as each pathogen must adapt to the particular microenvironment of its site of infection, the role of each acquisition system in virulence can differ from a particular strain to another. In this review, we present the systems involved in metal transport by Enterobacteria and the main regulators responsible for their controlled expression. We also discuss the relative role of these systems depending on the pathogen and the tissues they infect.

Porcheron, Gaelle; Garenaux, Amelie; Proulx, Julie; Sabri, Mourad; Dozois, Charles M.

2013-01-01

280

Cadmium toxicity  

PubMed Central

Cadmium is a well-known environmental pollutant with distinctly toxic effects on plants. It can displace certain essential metals from a wealth of metalloproteins, and thus disturb many normal physiological processes and cause severe developmental aberrant. The harmful effects of cadmium stress include, but are not limited to: reactive oxygen species overproduction, higher lipid hydroperoxide contents, and chloroplast structure change, which may lead to cell death. Plants have developed diverse mechanisms to alleviate environmental cadmium stress, e.g., cadmium pump and transporting cadmium into the leaf vacuoles. This mini-review focuses on the current research into understanding the cellular mechanisms of cadmium toxicity on cytoskeleton, vesicular trafficking and cell wall formation in plants.

Wan, Lichuan; Zhang, Haiyan

2012-01-01

281

Cloud point extraction of copper, lead, cadmium, and iron using 2,6-diamino-4-phenyl-1,3,5-triazine and nonionic surfactant, and their flame atomic absorption spectrometric determination in water and canned food samples.  

PubMed

A cloud point extraction procedure was optimized for the separation and preconcentration of lead(II), cadmium(II), copper(II), and iron(III) ions in various water and canned food samples. The metal ions formed complexes with 2,6-diamino-4-phenyl-1,3,5-triazine that were extracted by surfactant-rich phases in the nonionic surfactant Triton X-114. The surfactant-rich phase was diluted with 1 M HNO3 in methanol prior to its analysis by flame atomic absorption spectrometry. The parameters affecting the extraction efficiency of the proposed method, such as sample pH, complexing agent concentration, surfactant concentration, temperature, and incubation time, were optimized. LOD values based on three times the SD of the blank (3Sb) were 0.38, 0.48, 1.33, and 1.85 microg/L for cadmium(II), copper(II), lead(II), and iron(III) ions, respectively. The precision (RSD) of the method was in the 1.86-3.06% range (n=7). Validation of the procedure was carried out by analysis of National Institute of Standards and Technology Standard Reference Material (NIST-SRM) 1568a Rice Flour and GBW 07605 Tea. The method was applied to water and canned food samples for determination of metal ions. PMID:22970587

Citak, Demirhan; Tuzen, Mustafa

2012-01-01

282

Cadmium Oxide.  

National Technical Information Service (NTIS)

These data sheets present a compilation of a wide range of electronic properties for cadmium oxide. Electrical properties include conductivity, dielectric constant, Hall coefficient, and mobility. Emission data have been broken down into the varied electr...

M. Neuberger

1966-01-01

283

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

Microsoft Academic Search

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.

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

1963-01-01

284

Paramagnetic complexes of manganese(II), iron(III), and gadolinium(III) as contrast agents for magnetic resonance imaging. The influence of stability constants on the biodistribution of radioactive aminopolycarboxylate complexes  

SciTech Connect

Paramagnetic complexes of manganese(II), iron(III), and gadolinium(III) with many ligands appear to undergo ligand substitution in vivo, producing biodistribution data similar to the hydrated metal ions. To identify ligands likely to be valuable in the preparation of paramagnetic contrast agents, a series of aminopolycarboxylate complexes with stability constants increasing in the order iminodiacetic acid (IDA) less than nitrilotriacetic acid (NTA) less than EDTA less than CDTA less than or equal to DTPA was prepared with /sup 54/Mn(II), /sup 59/Fe(III), and /sup 153/Gd(III) at both tracer and carrier levels. Biodistribution studies in mice suggested that complexes remained unchanged in vivo if their stability constants (K1) were approximately greater than 10(16) for Mn(II) and Gd(III) and greater than 10(22) for Fe(III) complexes at tracer levels. Metal complexes with added carrier appeared to be effectively more stable in vivo, possibly due to dissociation and saturation of metal-binding sites. To avoid the accumulation of metal ions in tissues, new paramagnetic contrast agents containing these metal ions will require stability constants equal to or greater than those identified here.

Fornasiero, D.; Bellen, J.C.; Baker, R.J.; Chatterton, B.E.

1987-04-01

285

Chronic manganese intoxication  

SciTech Connect

We report six cases of chronic manganese intoxication in workers at a ferromanganese factory in Taiwan. Diagnosis was confirmed by assessing increased manganese concentrations in the blood, scalp, and pubic hair. In addition, increased manganese levels in the environmental air were established. The patients showed a bradykinetic-rigid syndrome indistinguishable from Parkinson's disease that responded to treatment with levodopa.

Huang, C.C.; Chu, N.S.; Lu, C.S.; Wang, J.D.; Tsai, J.L.; Tzeng, J.L.; Wolters, E.C.; Calne, D.B. (Chang Gung Medical College Hospital, Taipei, Taiwan (China))

1989-10-01

286

Solidphase 31 P NMR spectra of peat and mineral soils, humic acids and soil solution components: influence of iron and manganese  

Microsoft Academic Search

Solid-phase31P nuclear magnetic resonance (NMR) offers a direct means to determine the chemical environment of P present in soil and soil\\u000a fractions. Iron is often a major component in soil and it has been thought that the presence of paramagnetic Fe and Mn in\\u000a soil components is responsible for loss of resolution in NMR spectra. We have found that the

C. A. Shand; M. V. Cheshire; C. N. Bedrock; P. J. Chapman; A. R. Fraser; J. A. Chudek

1999-01-01

287

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

288

Current status of cadmium as an environmental health problem  

Microsoft Academic Search

Cadmium is a toxic metal occurring in the environment naturally and as a pollutant emanating from industrial and agricultural sources. Food is the main source of cadmium intake in the non-smoking population. The bioavailability, retention and toxicity are affected by several factors including nutritional status such as low iron status. Cadmium is efficiently retained in the kidney (half-time 10–30 years) and

Lars Jaerup; Agneta Åkesson

2009-01-01

289

On the effect of silicon and phosphorus during the precipitation of kappa-carbide in Iron-Manganese-Aluminium-Carbon alloys  

NASA Astrophysics Data System (ADS)

Implementation of lightweight high manganese and aluminum steels for use in high energy absorbing applications requires a detailed knowledge of how alloying additions and impurities affect age hardening and high strain rate fracture properties. Dynamic fracture toughness is an important design criterion but has not been reported previously in these alloys. In addition, previous studies have shown that silicon and phosphorus increased the strength and aged hardness; however, the mechanism was unknown. This research mainly focuses on the effect of silicon and phosphorus on the precipitation of kappa-carbide and alloy partitioning during aging. Short range ordering, SRO, of Fe-Al-C into relative atomic positions described by the E21 superlattice structure preceded and occurred concurrent to spinodal decomposition. Short range diffusion of phosphorus increased the kinetics of ordering resulting in a decrease in the time required for subsequent spinodal decomposition and an increase the amplitude of carbon concentration with time. Silicon increased the strength and hardness as a result of increased carbon partitioning into the kappa-carbide during aging. Dynamic fracture toughness was found to depend upon aluminum and carbon. Increasing the amount of solid solution carbon increased the dynamic fracture toughness in solution treated specimens. However, increasing carbon in aged specimens increased the amount of kappa-carbide and produced brittle fracture. Additions of aluminum from three to nine weight percent decreased toughness regardless of the heat treatment. Dynamic fracture toughness was a strong function of AlN content. A good combination of high strength and dynamic toughness with a corresponding density reduction of 10 to 12% is obtained with aluminum additions between 6 and 7% and carbon below 1.2%.

Bartlett, Laura Nicole

290

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

291

Passivation of cracking catalysts with cadmium and tin  

Microsoft Academic Search

A method for passivating the adverse catalytic effects of metal contaminants, such as nickel, vanadium and iron, which become deposited on cracking catalyst is disclosed. A passivation promoter comprising elemental tin and\\/or a tin compound in combination with elemental cadmium and\\/or a cadmium compound is deposited on the catalyst and the catalyst is passed through a passivation zone having a

Bertch

1985-01-01

292

Geochemistry of the Palæoproterozoic Mooidraai Formation: Fe-rich limestone as end member of iron formation deposition, Kalahari Manganese Field, Transvaal Supergroup, South Africa  

NASA Astrophysics Data System (ADS)

The Mooidraai Formation forms the uppermost portion of the Palæoproterozoic Transvaal Supergroup in Griqualand West, Northern Cape Province, South Africa and is developed immediately above the Mn-bearing Hotazel Formation. Though previously described as a (cherty) dolomite, the portion of the Mooidraai succession investigated here contains microcrystalline calcite as the sole carbonate constituent. Variable amounts of magnetite and quartz are commonly present in the rock, giving it a mineralogical/geochemical character that approaches, at times, that of the underlying Hotazel iron formation. Bulk rock and rare earth element data compare well with those of the Hotazel iron formation and suggest that the Mooidraai Formation constitutes the end member of chemical precipitation that produced the cyclic Fe-Mn sequence of the Hotazel Formation. Calcite C and O isotope data indicate a diagenetic origin for the carbonate component with deviations from typical marine bicarbonate isotope values proportionally related to the amount of Fe present. The Mooidraai data thus support models of organic matter oxidation-ferric Fe reduction, as observed in modern O deficient diagenetic environments.

Tsikos, H.; Moore, J. M.; Harris, C.

2001-01-01

293

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

294

[Effect of an occupational environment containing manganese on granulocyte adherence].  

PubMed

Workers employed in the manufacture of iron/manganese alloys were exposed primarily to manganese, but also to noise and other factors. Neutrophilic erythrocytes of those workers displayed significantly higher adherence compared to that determined in the control group. Duration of employment, occurrence of chronic bronchitis and the intensity of tobacco smoking did not affect the adhesive properties of neutrophilic granulocytes in peripheral blood. PMID:1293473

Misiewicz, A; Jele?, B; Radwan, K

1992-01-01

295

Manganese laser using manganese chloride as lasant  

NASA Technical Reports Server (NTRS)

A manganese vapor laser utilizing manganese chloride as a lasant has been observed and investigated. Lasing is attained by means of two consecutive electrical discharges. The maximum laser output is obtained at a vapor pressure of about 3 torr, a temperature of 680 C, and a time delay between electrical discharges of 150 microsec. The maximum energy density is 1.3 microjoule per cu cm.

Chen, C. J.

1974-01-01

296

Role of trace elements in cadmium chloride uptake in hepatoma cell lines  

Microsoft Academic Search

Cadmium coexists with other metals in various products. Releases of cadmium in the environment occur in parallel to the release of other metals including copper, iron and zinc which also have an essential role in human homeostasis as they participate in various biochemical pathways. We studied the interaction of iron, copper, zinc and calcium channel blockers (nifedipine and verapamil) with

George Fotakis; John A. Timbrell

2006-01-01

297

Hydrogen, acetate, and lactate as electron donors for microbial manganese reduction in a manganese-rich coastal marine sediment.  

PubMed

The role of hydrogen, acetate, and lactate as electron donors for microbial manganese reduction was investigated in manganese-rich marine sediment from Gullmar Fjord (Sweden). Here, manganese reduction accounted for 50% of the anaerobic carbon oxidation at 0-15 cm sediment depth. In anoxic incubations from 0 to 5 cm depth, where manganese reduction dominated completely as terminal electron-accepting process, the combined contribution of acetate and lactate as electron donors for manganese reducers corresponded to < ¼ of the electron flow. The concentrations, ¹?C-radiotracer turnover rates, and contributions to carbon oxidation of acetate and lactate associated with manganese reduction were similar to those found in deeper horizons dominated by concomitant iron and sulfate reduction and sulfate reduction alone, respectively. By contrast, hydrogen concentrations increased considerably with sediment depth, indicating thermodynamic control of the competition between the electron-accepting processes, and hydrogen may have contributed substantially to the > 75% of the electron flow that did not involve acetate and lactate. Alternatively, the oxidation of more complex organic substrates could be involved. Our study provides the first direct evidence of substrate utilization by a natural manganese-reducing community and indicates similar mechanisms of thermodynamic control and competition for electron donors as known from sediments dominated by iron reduction, sulfate reduction, or methanogenesis. PMID:24266405

Vandieken, Verona; Finke, Niko; Thamdrup, Bo

2014-03-01

298

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

299

A series of trinuclear sandwich-like cyanide-bridged iron(III)-manganese(II) complexes: synthesis, crystal structures, and magnetic properties  

Microsoft Academic Search

Four pyridinecarboxamide iron dicyanide building blocks and one Mn(III) compound have been employed to assemble cyanide-bridged\\u000a heterometallic complexes, resulting in a series of trinuclear cyanide-bridged FeIII–MnII complexes: {[Mn(DMF)2 (MeOH)2][Fe(bpb)(CN)2]2}·2DMF (1), {[Mn(MeOH)4][Fe(bpmb)(CN)2]2}·2MeOH·2H2O (2), {[Mn(MeOH)4][Fe(bpdmb)(CN)2]2}·2MeOH·2H2O (3) and {[Mn(MeOH)4][Fe(bpClb)(CN)2]2}·4MeOH (4) (bpb2? = 1,2-bis(pyridine-2-carboxamido)benzenate, bpmb2? = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpdmb2? = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate, bpClb2? = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate). Single-crystal X-ray diffraction analysis shows their similar sandwich-like\\u000a structures, in which the two cyanide-containing building blocks act as monodentate

Daopeng Zhang; Lifang Zhang; Xia Chen; Zhonghai Ni

2011-01-01

300

Iron, lanthanum and manganese oxides loaded on gamma-AI2O3 for selective catalytic reduction of NO with NH3 at low temperature.  

PubMed

A series of Mn/Al2O3, La-Mn/Al2O3 and Fe-La-Mn/Al2O3 catalysts were prepared by an impregnation method and investigated for selective catalytic reduction of NO with NH3 at low temperature. The experimental results revealed that NO conversion over La-Mn/Al2O3 was obviously improved after La doping. Addition of Fe increased both NO conversion and the resistance to H2O and SO2. The catalyst Fe0.04La0.03Mn0.06/Al2O3 with a load mass of MnO2 = 6%, La2O3 = 3% and Fe2O3 = 4% exhibited relatively high catalytic activity and yielded 98% NO conversion at 260 degrees with a space velocity of 15,000 h(-1). Meanwhile, the catalytic activity was slightly decreased in the presence of H2O and SO2. Moreover, the catalysts were characterized by N2 adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy. The results showed that the doping of La enhanced the dispersion and oxidation states of Mn on the surface of Al2O3. On the surface of the Fe0.04La0.03Mn0.06/Al2O3 catalyst, La was highly dispersed and a mixed oxidation state of Mn existed, while iron ions were only in the Fe3+ state. The mechanism of selective catalytic reduction over these catalysts is also discussed. In this experiment, metal oxides loaded on the support were catalytic centres which served as electron transfer during NO reduction. The electron transfer between Mn3+ and Fe3+ might also exist and the mixture oxidation states of Mn on the surface of the Fe0.04La0.03Mn0.06/Al2O3 catalyst contributed to the SCR activity. PMID:23530318

Zhao, Weiwei; Li, Caiting; Lu, Pei; Wen, Qingbo; Zhao, Yapei; Zhang, Xing; Fan, Chunzhen; Tao, Shasha

2013-01-01

301

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

302

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

303

Proteins involved in iron metabolism in beef cattle are affected by copper deficiency in combination with high dietary manganese, but not by copper deficiency alone.  

PubMed

A 493-d study was conducted to determine the impact of a severe, long-term Cu deficiency on Fe metabolism in beef cattle. Twenty-one Angus calves were born to cows receiving one of the following treatments: 1) adequate Cu (+Cu), 2) Cu deficient (-Cu), and 3) Cu deficient plus high Mn (-Cu+Mn). Copper deficiency was induced through the addition of 2 mg of Mo/kg of DM. After weaning, calves remained on the same treatment as their dam through growing (basal diet analyzed 7 mg of Cu/kg of DM) and finishing (analyzed 4 mg of Cu/kg of DM) phases. Plasma Fe concentrations were positively correlated (P < 0.01; r = 0.49) with plasma Cu concentrations. Liver Fe concentrations were greater (P = 0.05) in -Cu vs. +Cu calves and further increased (P = 0.07) in -Cu+Mn vs. -Cu calves. There was a negative relationship (P < 0.01; r = -0.31) between liver Cu and Fe concentrations. This relationship is likely explained by less (P < 0.01) plasma ceruloplasmin activity in -Cu than +Cu calves. As determined by real-time reverse transcription-PCR, relative expression of hepatic hepcidin was significantly downregulated (>1.5 fold) in -Cu compared with +Cu calves (P = 0.03), and expression of hepatic ferroportin tended (P = 0.09) to be downregulated in -Cu vs. +Cu. In the duodenum, ferritin tended to be upregulated in -Cu. vs. +Cu calves (P < 0.06). No significant change (P > 0.2) due to Cu-deficiency was detected at the transcriptional level for either isoform of divalent metal transporter 1 (DMT1 mRNA with or without an iron responsive element; dmt1IRE and dmt1-nonIRE) in liver or intestine. Duodenal expression of hephaestin and ferroportin protein was not affected by dietary treatment (P > 0.20). However, duodenal expression of DMT1 protein was less (P = 0.04) in -Cu+Mn steers vs. -Cu steers. In summary, Cu deficiency alone did affect hepatic gene expression of hepcidin and ferroportin, but did not affect duodenal expression of proteins important in Fe metabolism. However, the addition of 500 mg of Mn/kg of DM to a diet low in Cu reduced duodenal expression of the Fe import protein DMT1. PMID:19820055

Hansen, S L; Trakooljul, N; Liu, H-C S; Hicks, J A; Ashwell, M S; Spears, J W

2010-01-01

304

BIOLOGICAL EFFECTS OF MANGANESE  

EPA Science Inventory

The biological effects of manganese were studied in a town on the coast of Dalmatia in which a ferromanganese plant has been operating since before World War II. The study focused on the question of whether the exposure to manganese can cause a higher incidence of respiratory dis...

305

Biomarkers of Manganese Intoxication  

PubMed Central

Manganese (Mn), upon absorption, is primarily sequestered in tissue and intracellular compartments. For this reason, blood Mn concentration does not always accurately reflect Mn concentration in the targeted tissue, particularly in the brain. The discrepancy between Mn concentrations in tissue or intracellular components means that blood Mn is a poor biomarker of Mn exposure or toxicity under many conditions and that other biomarkers must be established. For group comparisons of active workers, blood Mn has some utility for distinguishing exposed from unexposed subjects, although the large variability in mean values renders it insensitive for discriminating one individual from the rest of the study population. Mn exposure is known to alter iron (Fe) homeostasis. The Mn/Fe ratio (MIR) in plasma or erythrocytes reflects not only steady-state concentrations of Mn or Fe in tested individuals, but also a biological response (altered Fe homeostasis) to Mn exposure. Recent human studies support the potential value for using MIR to distinguish individuals with Mn exposure. Additionally, magnetic resonance imaging (MRI), in combination with noninvasive assessment of ?-aminobutyric acid (GABA) by magnetic resonance spectroscopy (MRS), provides convincing evidence of Mn exposure, even without clinical symptoms of Mn intoxication. For subjects with long-term, low-dose Mn exposure or for those exposed in the past but not the present, neither blood Mn nor MRI provides a confident distinction for Mn exposure or intoxication. While plasma or erythrocyte MIR is more likely a sensitive measure, the cut-off values for MIR among the general population need to be further tested and established. Considering the large accumulation of Mn in bone, developing an X-ray fluorescence spectroscopy or neutron-based spectroscopy method may create yet another novel non-invasive tool for assessing Mn exposure and toxicity.

Zheng, Wei; Fu, Sherleen X.; Dydak, Ulrike; Cowan, Dallas M.

2010-01-01

306

Manganese toxicity upon overexposure  

PubMed Central

Manganese (Mn) is a required element and a metabolic byproduct of the contrast agent mangafodipir trisodium (MnDPDP). The Mn released from MnDPDP is initially sequestered by the liver for first-pass elimination, which allows an enhanced contrast for diagnostic imaging. The administration of intravenous Mn impacts its homeostatic balance in the human body and can lead to toxicity. Human Mn deficiency has been reported in patients on parenteral nutrition and in micronutrient studies. Mn toxicity has been reported through occupational (e.g. welder) and dietary overexposure and is evidenced primarily in the central nervous system, although lung, cardiac, liver, reproductive and fetal toxicity have been noted. Mn neurotoxicity results from an accumulation of the metal in brain tissue and results in a progressive disorder of the extrapyramidal system which is similar to Parkinson's disease. In order for Mn to distribute from blood into brain tissue, it must cross either the blood–brain barrier (BBB) or the blood–cerebrospinal fluid barrier (BCB). Brain import, with no evidence of export, would lead to brain Mn accumulation and neurotoxicity. The mechanism for the neurodegenerative damage specific to select brain regions is not clearly understood. Disturbances in iron homeostasis and the valence state of Mn have been implicated as key factors in contributing to Mn toxicity. Chelation therapy with EDTA and supplementation with levodopa are the current treatment options, which are mildly and transiently efficacious. In conclusion, repeated administration of Mn, or compounds that readily release Mn, may increase the risk of Mn-induced toxicity.

Crossgrove, Janelle; Zheng, Wei

2014-01-01

307

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

308

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

PubMed Central

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

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

2013-01-01

309

Effect of natural organic materials on cadmium and neptunium sorption  

SciTech Connect

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

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

1994-10-01

310

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

PubMed

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

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

2012-02-01

311

The Overlapping Roles of Manganese and Cu/Zn SOD in Oxidative Stress Protection  

PubMed Central

In various organisms, high intracellular manganese provides protection against oxidative damage through unknown pathways. Herein we use a genetic approach in S. cerevisiae to analyze factors that promote manganese as an anti-oxidant in cells lacking Cu/Zn superoxide dismutase (sod1?). Unlike certain bacterial systems [1], oxygen resistance in yeast correlates with high intracellular manganese without a lowering of iron. This manganese for anti-oxidant protection is provided by the Nramp transporters Smf1p and Smf2p, with Smf1p playing a major role. In fact, loss of manganese transport by Smf1p together with loss of the Pmr1p manganese pump is lethal to sod1? cells in spite of normal manganese SOD2 activity. Manganese-phosphate complexes are excellent superoxide dimustase mimics in vitro [2], yet through genetic disruption of phosphate transport and storage, we observed no requirement for phosphate in manganese suppression of oxidative damage. If anything, elevated phosphate correlated with profound oxidative stress in sod1? mutants. The efficacy of manganese as an anti-oxidant was drastically reduced in cells that hyper-accumulate phosphate without effects on MnSOD activity. Non-SOD manganese can provide a critical backup for Cu/Zn SOD1, but only under appropriate physiologic conditions.

Reddi, Amit R.; Jensen, Laran T.; Naranuntarat, Amornrat; Rosenfeld, Leah; Leung, Edison; Shah, Rishita; Culotta, Valeria C.

2009-01-01

312

The overlapping roles of manganese and Cu/Zn SOD in oxidative stress protection.  

PubMed

In various organisms, high intracellular manganese provides protection against oxidative damage through unknown pathways. Herein we use a genetic approach in Saccharomyces cerevisiae to analyze factors that promote manganese as an antioxidant in cells lacking Cu/Zn superoxide dismutase (sod1 Delta). Unlike certain bacterial systems, oxygen resistance in yeast correlates with high intracellular manganese without a lowering of iron. This manganese for antioxidant protection is provided by the Nramp transporters Smf1p and Smf2p, with Smf1p playing a major role. In fact, loss of manganese transport by Smf1p together with loss of the Pmr1p manganese pump is lethal to sod1 Delta cells despite normal manganese SOD2 activity. Manganese-phosphate complexes are excellent superoxide dismutase mimics in vitro, yet through genetic disruption of phosphate transport and storage, we observed no requirement for phosphate in manganese suppression of oxidative damage. If anything, elevated phosphate correlated with profound oxidative stress in sod1 Delta mutants. The efficacy of manganese as an antioxidant was drastically reduced in cells that hyperaccumulate phosphate without effects on Mn SOD activity. Non-SOD manganese can provide a critical backup for Cu/Zn SOD1, but only under appropriate physiologic conditions. PMID:18973803

Reddi, Amit R; Jensen, Laran T; Naranuntarat, Amornrat; Rosenfeld, Leah; Leung, Edison; Shah, Rishita; Culotta, Valeria C

2009-01-15

313

Globally sustainable manganese metal production and use.  

PubMed

The "cradle to grave" concept of managing chemicals and wastes has been a descriptive analogy of proper environmental stewardship since the 1970s. The concept incorporates environmentally sustainable product choices-such as metal alloys utilized steel products which civilization is dependent upon. Manganese consumption is related to the increasing production of raw steel and upgrading ferroalloys. Nonferrous applications of manganese include production of dry-cell batteries, plant fertilizer components, animal feed and colorant for bricks. The manganese ore (high grade 35% manganese) production world wide is about 6 million ton/year and electrolytic manganese metal demand is about 0.7 million ton/year. The total manganese demand is consumed globally by industries including construction (23%), machinery (14%), and transportation (11%). Manganese is recycled within scrap of iron and steel, a small amount is recycled within aluminum used beverage cans. Recycling rate is 37% and efficiency is estimated as 53% [Roskill Metals and Minerals Reports, January 13, 2005. Manganese Report: rapid rise in output caused by Chinese crude steel production. Available from: http://www.roskill.com/reports/manganese.]. Environmentally sustainable management choices include identifying raw material chemistry, utilizing clean production processes, minimizing waste generation, recycling materials, controlling occupational exposures, and collecting representative environmental data. This paper will discuss two electrolytically produced manganese metals, the metal production differences, and environmental impacts cited to date. The two electrolytic manganese processes differ due to the addition of sulfur dioxide or selenium dioxide. Adverse environmental impacts due to use of selenium dioxide methodology include increased water consumption and order of magnitude greater solid waste generation per ton of metal processed. The use of high grade manganese ores in the electrolytic process also reduces the quantity of solid wastes generated during processing. Secondary aluminum facilities have reported hazardous waste generation management issues due to baghouse dusts from rotary furnaces processing selenium contaminated manganese alloys. Environmental impacts resulting from industry are represented by emission inventories of chemical releases to the air, water, and soil. The U.S. metals industry releases reported to EPA Toxic Release Inventory indicate the primary metals industry is the major source of metal air toxic emissions, exceeding electric utility air toxic emissions. The nonferrous metals industry is reported to be the Organization for Economic Co-operation and Development (OECD) most intensive airborne and land pollution source of bioaccumulative metals. However, total waste emissions from industries in the OECD countries have declined due to improving energy consumption. Emission registers and access are improving around the world. However, environmental databases for metal particulates have low confidence ratings since the majority of air toxic emissions are not reported, not monitored, or are estimated based on worst-case emission factors. Environmental assessments including biological monitoring are necessary to validate mandated particulate metal emission reductions and control technologies during metal processing. PMID:19467569

Hagelstein, Karen

2009-09-01

314

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

315

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

316

Hot coal gas desulfurization with manganese-based sorbents  

SciTech Connect

The focus of work being performed on Hot Coal Gas Desulfurization 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 higher temperatures than zinc ferrite or zinc titanate. This presentation gives the thermodynamic background for consideration of manganese-based sorbents as an alternative to zinc ferrite. To date the work which has been in progress for nine months is limited at this stage to thermogravimetric testing of four formulations of manganese-alumina sorbents to determine the optimum conditions of pelletization and induration to produce reactive pellets.

Lynch, D.; Hepworth, M.T.

1993-09-01

317

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

318

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

319

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

Microsoft Academic Search

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

Derek W. Spencer; Peter G. Brewer

1971-01-01

320

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

321

Cadmium and the kidney.  

PubMed Central

The paper is a review of certain aspects of importance of cadmium and the kidney regarding the assessment of risks and understanding of mechanisms of action. The review discusses the following topics: history and etiology of cadmium-induced kidney dysfunction and related disorders; cadmium metabolism, metallothionein and kidney dysfunction; cadmium in urine as indicator of body burden, exposure and kidney dysfunction; cadmium levels in kidney and liver as indicators of kidney dysfunction; characteristics of early kidney dysfunction; the critical concentration concept; critical concentrations of cadmium in kidney cortex; and prognosis.

Friberg, L

1984-01-01

322

Oscillator strengths for ionized iron and manganese  

NASA Technical Reports Server (NTRS)

The observed strengths of interstellar absorption lines of Fe II and Mn II in the spectra of alpha Vir, beta Cen, pi Sco, and zeta Oph along with laboratory f values of some of these lines between 2343 and 2606 A have been used to determine curves of growth for these ions and the f-values of ten lines of Fe II and three lines of Mn II between 1055 and 1261 A. The Fe and Mn abundances are derived.

De Boer, K. S.; Pottasch, S. R.; Morton, D. C.; York, D. G.

1974-01-01

323

Manganese and iron in Indian Ocean waters  

SciTech Connect

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

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

1989-09-01

324

Manganese and iron in Indian Ocean waters  

NASA Astrophysics Data System (ADS)

The first vertical profiles of dissolved Mn and Fe for the (NW) Indian Ocean are reported. The area is characterized by seasonal upwelling and a broad oxygen minimum zone in intermediate waters. The dissolved Fe-profile exhibits a maximum (5.1 nM) in the oxygen minimum zone, with low values both in surface waters (0.3 nM) and deep waters (around 1 nM). Mn concentrations in the surface waters are elevated (2.0-4.3 nM), and decrease rapidly in an offshore direction. Below the first 25 m, concentrations decrease dramatically (0.5-1.3 nM), indicating removal by oxidation and particle scavenging. Further down, various Mn maxima are observed which can be related to hydrographic features (sigma-?): 1. Intermediate water originating from the Red Sea lost its dissolved O 2 while flowing northward along the Omani coast and exhibits a strong Mn maximum (4.6-6.5 nM) coincident with the deep O 2 minimum. 2. At the two inshore stations in the Gulf of Oman this is overlain by relatively modest Mn maxima (±2.7 nM) related to Arabian Gulf overflow water. 3. Finally the strong Mn maxima (4.4-5.6 nM) in the oxygen minimum zone at the two offshore stations are related to yet another watermass. Below these various maxima, concentrations decrease gradually to values as low as 90 pM at 2000 meters depth. Towards the seafloor concentrations increase again, leading to a modest bottom water maximum (0.7-1.5 nM). The overall vertical distributions of Mn and Fe are strikingly similar, also in actual concentrations, to those previously reported for the eastern equatorial Pacific, an area also characterized by an extensive O 2-minimum zone.

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

1989-09-01

325

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

326

Silver(I), Mercury(II), Cadmium(II), and Zinc(II) Target Exposed Enzymic Iron-Sulfur Clusters when They Toxify Escherichia coli  

PubMed Central

The toxicity of soft metals is of broad interest to microbiologists, both because such metals influence the community structures in natural environments and because several metals are used as antimicrobial agents. Their potency roughly parallels their thiophilicity, suggesting that their primary biological targets are likely to be enzymes that contain key sulfhydryl moieties. A recent study determined that copper poisons Escherichia coli in part by attacking the exposed [4Fe-4S] clusters of dehydratases. The present investigation sought to test whether other soft metals also target these enzymes. In vitro experiments revealed that low-micromolar concentrations of Ag(I) and Hg(II) directly inactivated purified fumarase A, a member of the dehydratase family. The enzyme was also poisoned by higher levels of Cd(II) and Zn(II), but it was unaffected by even millimolar concentrations of Mn(II), Co(II), Ni(II), and Pb(II). Electron paramagnetic resonance analysis and measurements of released iron confirmed that damage was associated with destruction of the [4Fe-4S] cluster, and indeed, the reconstruction of the cluster fully restored activity. Growth studies were then performed to test whether dehydratase damage might underlie toxicity in vivo. Barely toxic doses of Ag(I), Hg(II), Cd(II), and Zn(II) inactivated all tested members of the [4Fe-4S] dehydratase family. Again, activity was recovered when the clusters were rebuilt. The metals did not diminish the activities of other sampled enzymes, including NADH dehydrogenase I, an iron-sulfur protein whose clusters are shielded by polypeptide. Thus, the data indicate that dehydratases are damaged by the concentrations of metals that initiate bacteriostasis.

Xu, Fang Fang

2012-01-01

327

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

328

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

329

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

330

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

331

Occupational exposure to manganese.  

PubMed Central

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

Saric, M; Markicevic, A; Hrustic, O

1977-01-01

332

Effects of sediment composition on cadmium bioaccumulation in the clam Meretrix meretrix Linnaeus.  

PubMed

Sediment particulates can be ingested by benthic animals, and the bioavailability of associated metals strongly depends on their speciation in the sediments. Different sedimentary components have distinct physiochemical characteristics and result in different biological responses from animals. Therefore, the bioaccumulation of particle-bound trace metals may be different. In the present study, bioaccumulation of cadmium adsorbed on various (hydr)oxide minerals, that is, ferric hydroxide, aluminum hydroxide, and manganese dioxide, in the clam Meretrix meretrix Linnaeus was studied. The results showed that the accumulation rate of cadmium varied for different mineral-adsorbed cadmium. The bioaccumulation of metal (hydr)oxide-adsorbed cadmium in M. meretrix followed the order Cd-MnO2 ?>?Cd-Al(OH)3 ?>?Cd-Fe(OH)3 . The type of mineral determines both the assimilation efficiency and ingestion rate, and consequently controls the bioaccumulation of adsorbed cadmium. PMID:23355485

Wu, Xing; Xie, Lingtian; Xu, Liying; Wang, Shaofeng; Jia, Yongfeng

2013-04-01

333

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

2011-08-01

334

The ubiquity of iron.  

PubMed

The importance of iron in living systems can be traced to the many complexes within which it is found, to its chemical mobility in undergoing oxidation-reduction reactions, and to the abundance of iron in Earth's crust. Iron is the most abundant element, by mass, in the Earth, constituting about 80% of the inner and outer cores of Earth. The molten outer core is about 8000 km in diameter, and the solid inner core is about 2400 km in diameter. Iron is the fourth most abundant element in Earth's crust. It is the chemically functional component of mononuclear iron complexes, dinuclear iron complexes, [2Fe-2S] and [4Fe-4S] clusters, [Fe-Ni-S] clusters, iron protophorphyrin IX, and many other complexes in protein biochemistry. Metals such as nickel, cobalt, copper, and manganese are present in the crust and could in principle function chemically in place of iron, but they are scarce in Earth's crust. Iron is plentiful because of its nuclear stability in stellar nuclear fusion reactions. It seems likely that other solid planets, formed by the same processes as Earth, would also foster the evolution of life and that iron would be similarly important to life on those planets as it is on Earth. PMID:22845493

Frey, Perry A; Reed, George H

2012-09-21

335

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

336

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...

337

Evaluation of the potential carcinogenicity of cadmium, cadium acetate, cadmium bromide, cadmium chloride. Final report  

SciTech Connect

Cadmium is a probable human carcinogen, classified as weight-of-evidence Group B1 under the EPA Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1986a). Evidence on potential carcinogenicity from animal studies is Sufficient, and the evidence from human studies is Limited. The potency factor (F) for cadmium is estimated to be 57.9/(mg/kg/day) (based on epidemiology data for cadmium workers), placing it in potency group 2 according to the CAG's methodology for evaluating potential carcinogens (U.S. EPA, 1986b). Cadmium weight of evidence and potency are based on epidemiology data for cadmium workers exposed to cadmium oxide and/or cadmium fume. Although human data for cadmium salts are lacking, due to the responsiveness of animals to soluble cadmium compounds, especially cadmium chloride, the weight of evidence and potency for cadmium acetate, cadmium bromide and cadmium chloride are considered to be the same as those cadmium compounds to which workers are exposed. Thus, cadmium acetate, cadmium bromide, and cadmium chloride are all classified as weight-of-evidence Group and the potency group, cadmium, cadmium acetate, cadmium bromide, and cadmium chloride are assigned MEDIUM hazard rankings for the purposes of RQ adjustment. Combining the weight-of-evidence group and the potency group, carbon tetrachloride is assigned a MEDIUM hazard ranking for the purposes of RQ adjustment.

Not Available

1988-06-01

338

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

339

Managing the manganese: molecular mechanisms of manganese transport and homeostasis.  

PubMed

Manganese (Mn) is an essential metal nutrient for plants. Recently, some of the genes responsible for transition metal transport in plants have been identified; however, only relatively recently have Mn2+ transport pathways begun to be identified at the molecular level. These include transporters responsible for Mn accumulation into the cell and release from various organelles, and for active sequestration into endomembrane compartments, particularly the vacuole and the endoplasmic reticulum. Several transporter gene families have been implicated in Mn2+ transport, including cation/H+ antiporters, natural resistance-associated macrophage protein (Nramp) transporters, zinc-regulated transporter/iron-regulated transporter (ZRT/IRT1)-related protein (ZIP) transporters, the cation diffusion facilitator (CDF) transporter family, and P-type ATPases. The identification of mutants with altered Mn phenotypes can allow the identification of novel components in Mn homeostasis. In addition, the characterization of Mn hyperaccumulator plants can increase our understanding of how plants can adapt to excess Mn, and ultimately allow the identification of genes that confer this stress tolerance. The identification of genes responsible for Mn2+ transport has substantially improved our understanding of plant Mn homeostasis. PMID:16101910

Pittman, Jon K

2005-09-01

340

Characterization of haul road dust in an Indian opencast iron ore mine  

NASA Astrophysics Data System (ADS)

Vehicular traffic on unpaved haul roads of the opencast mines has been identified as the most prolific source of fugitive dust. An intensive study was carried out in Noamundi Iron ore mines of Tata Iron and Steel Co. in January-February 1994 to characterize the airborne aerosol mainly contributed from unpaved haul road, traffic exhaust and re-entrained dust from the other activities of the mine. Percentage of suspended particulate matter at the various size ranges and free silica content of each of the size ranges of haul road dust were determined. Concentrations of eight trace elements, namely, zinc, copper, lead, manganese, cobalt, nickel, cadmium and iron were determined and found to be varying in the range 13.92-16.34, 0.06-0.09, 0.71-0.79, 0.14-0.15, 0.08-0.11, 0.15-0.17, 0.003-0.004 and 390-401.20 ?g m -3, respectively. A study on enrichment factor and varimax rotated factor analysis indicates the four major sources namely soil/road dust, vehicle exhaust, metallic corrosion and, galvanized material, tire wear and zinc compound in rubber material which appear to contribute trace elements to airborne aerosol.

Sinha, Subrato; Banerjee, S. P.

341

A SCHEME FOR THE RAPID ANALYSIS OF URANIUM-ORE ACID LEACH SOLUTIONS. DETERMINATION OF ALUMINIUM, ARSENIC, CALCIUM, CADMIUM, COBALT, COPPER, MAGNESIUM, NICKEL, AND ZINC IN PRESENCE OF EXCESS IRON AND MANGANESE  

Microsoft Academic Search

A scheme for the rapid quantitative analysis of uraniumore acid leach ; solutions or solutions of similar composition is described. As, Cd, Co, Cu, Ni, ; and Zn are determined polarographically, Al, Fe, and Mn colorimetrically, and Ca ; and Mg by titration with EDTA. The scheme for the sepa- ration of Al, Cd, ; Ca, Co, Mg and Zn

L. Jarman; M. Matic

1962-01-01

342

Prediction of cadmium concentration in selected home-produced vegetables.  

PubMed

Soil contaminated with cadmium presents a potential hazard for humans, animals and plants. The latter play a major role in the transfer of cadmium to the food chain. The uptake of cadmium and its accumulation by plants is dependent on various soil, plants and environmental factors. In order to identify soil properties with statistically significant influence on cadmium concentration in vegetables and to reduce the collection of data, time and costs, regression models can be applied. The main objective of this research was to develop regression models to predict the concentration of cadmium in 9-vegetable species: zucchini, tomato, cabbage, onion, potato, carrot, red beet, endive and chicory, based on soil properties. Soil samples were collected from 123 home gardens of the Municipality of Celje and 59 of these gardens were also included in vegetable sampling. The concentration of elements (e.g. arsenic, cadmium, copper, lead, and zinc) in the samples was determined by Inductively Coupled Plasma Mass Spectrometry. Single (for cabbage, potato, red beet and chicory) and multiple (for tomato, onion, carrot and endive) linear regression models were developed. There was no statistically significant regression model for zucchini. The most significant parameter for the influencing the cadmium concentration in vegetables was the concentration of cadmium in soil. Other important soil properties were the content of organic matter, pH-value and the concentration of manganese. It was concluded that consuming carrots, red beets, endives, onions, potatoes and chicory which are grown in gardens with Cd concentrations (mgkg(-1) DW) above 2.4, 3.2, 6.3, 7.9, 8.3 and 10.9, respectively, might represent an important contribution to dietary Cd exposure. PMID:23886800

Bešter, Petra Karo; Lobnik, Franc; Eržen, Ivan; Kastelec, Damijana; Zupan, Marko

2013-10-01

343

The possible role of gradual accumulation of copper, cadmium, lead and iron and gradual depletion of zinc, magnesium, selenium, vitamins B2, B6, D, and E and essential fatty acids in multiple sclerosis.  

PubMed

Multiple sclerosis (MS) has a much higher incidence among caucasians that in any other race. Furthermore: females are much more susceptible than males and white females living in colder, wetter areas are much more susceptible than those living in warmer areas. On the other hand, menstruating women have increased copper (Cu) absorption and half-life, so they tend to accumulate more Cu than males. Moreover, rapidly growing girls have an increased demand for zinc (Zn), but their rapidly decreasing production of melatonin results in impaired Zn absorption, which is exacerbated by the high Cu levels. The low Zn levels result in deficient CuZnSuperoxide dismutase (CuZnSOD), which in turn leads to increased levels of superoxide. Menstruating females also often present with low magnesium (Mg) and vitamin B6 levels. Vitamin B6 moderates intracellular nitric oxide (NO) production and extracellular Mg is required for NO release from the cell, so that a deficiency of these nutrients results in increased NO production in the cell and reduced release from the cell. The trapped NO combines with superoxide to form peroxinitrite, an extremely powerful free radical that leads to the myelin damage of MS. Iron (Fe), molybdenum (Mo) and cadmium (Cd) accumulation also increase superoxide production. Which explains MS in males, who tend to accumulate Fe much faster and Cu much less rapidly than females. Since vitamin D is paramount for Mg absorption, the much reduced exposure to sunlight in the higher latitudes may account for the higher incidence in these areas. Moreover, vitamin B2 is a cofactor for xanthine oxidase, and its deficiency exacerbates the low levels of uric acid caused by high Cu levels, resulting in myelin degeneration. Finally Selenium (Se) and vitamin E prevent lipid peroxidation and EPA and DHA upregulate CuZnSOD. Therefore, supplementation with 100 mg MG, 25 mg vit B6, 10 mg vit B2, 15 mg Zn and 400 IU vit D and E, 100 microg Se, 180 mg EPA and 120 mg DHA per day between 14 and 16 years of age may prevent MS. PMID:10985916

Johnson, S

2000-09-01

344

Marine manganese tailings concrete: advantages and drawbacks  

Microsoft Academic Search

Korea, India and China are moving ahead with plans to develop a marine manganese nodule industry. This industry or a related manganese crust, hydrothermal manganese or existing terrestrial manganese industry will dispose millions of tons of fine grained manganese waste. This disposal presents a significant environmental liability. An ideal solution would be to use this material for a beneficial purpose.

John C. Wiltshire; Kathleen A. Moore

1999-01-01

345

Cadmium and manganese transport in Staphylococcus aureus membrane vesicles.  

PubMed Central

The presence of plasmid gene cadB did not affect Cd2+ accumulation, whereas plasmid gene cadA reduced Cd2+ accumulation by whole cells but not by membrane vesicles. Membrane vesicle studies indicated that Cd2+ uptake occurred via the Mn2+ transport system which was energized by the membrane electrical potential. Mn2+ and Cd2+ were competitive inhibitors of each other's transport, with Km's of 0.95 microM Mn2+ and 0.2 microM Cd2+. The kinetic parameters were nearly identical with vesicles prepared from sensitive and resistant cells, indicating that the cadA-encoded Cd2+ efflux system was inoperative in membrane vesicle preparations. Experiments with energy-inhibited cells indicated that the cadB gene product may bind Cd2+.

Perry, R D; Silver, S

1982-01-01

346

Functional assessment of Nramp-like metal transporters and manganese in Caenorhabditis elegans  

Microsoft Academic Search

Nramp1 (natural resistance-associated macrophage protein-1) is a functionally conserved iron–manganese transporter in macrophages. Manganese (Mn), a superoxide scavenger, is required in trace amounts and functions as a cofactor for most antioxidants. Three Nramp homologs, smf-1, smf-2, and smf-3, have been identified thus far in the nematode Caenorhabditis elegans. A GFP promoter assay revealed largely intestinal expression of the smf genes

Jaya Bandyopadhyay; Hyun-Ok Song; Byung-Jae Park; Gunasekaran Singaravelu; Ju Lee Sun; Joohong Ahnn; Jeong Hoon Cho

2009-01-01

347

Cadmium--a metallohormone?  

PubMed

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

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

2009-08-01

348

Process for removing technetium from iron and other metals  

DOEpatents

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

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

1999-03-23

349

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

350

Cadmium exposure and nephropathy in a 28-year-old female metals worker.  

PubMed Central

A 28-year-old female presented for evaluation of left flank pain and polyuria after having been exposed to cadmium in the jewelry manufacturing industry for approximately 3 years. This patient possessed both elevated 24-hr urinary ss2-microglobulin and elevated blood cadmium levels. Approximately 6 months after initial presentation, the patient resigned from her job due to shortness of breath, chest pain, and anxiety. Exposure to cadmium in the jewelry industry is a significant source of occupational cadmium exposure. Other occupational sources include the manufacture of nickel-cadmium batteries, metal plating, zinc and lead refining, smelting of cadmium and lead, and production of plastics. Cadmium is also an environmental pollutant that accumulates in leafy vegetables and plants, including tobacco. Major toxicities anticipated from cadmium exposure involve the renal, pulmonary, and, to a lesser extent, gastrointestinal systems. These include the development of renal proximal tubular dysfunction, glomerular damage with progressive renal disease, and respiratory symptoms including pneumonitis and emphysema. Low-level cadmium exposure has also been associated with increased urinary calcium excretion and direct bone toxicity, effects that recent research suggests may result in the development of osteoporosis. The body burden of cadmium, over half of which may reside in the kidneys, is most often measured through the use of urinary cadmium levels. Blood cadmium measurements generally reflect current or recent exposure and are especially useful in cases with a short exposure period and only minimal accumulation of cadmium in the kidneys. Both ss2-microglobulin and alpha1-microglobulin serve as organ-specific, early-effect biomarkers of tubular proteinuria and thus play a role in identifying early signs of cadmium-induced renal damage in those with potential exposures. In addition to ensuring workplace compliance with Occupational Safety and Health Administration-mandated monitoring and screening measures, it is prudent for those with cadmium exposure to maintain adequate intake of both iron and calcium, appropriate measures even in the absence of exposure.

Wittman, Richard; Hu, Howard

2002-01-01

351

21 CFR 582.5446 - Manganese chloride.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Manganese chloride. 582.5446 Section 582.5446 Food...Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use. This...

2013-04-01

352

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

353

Manganese accumulation in striatum of mice exposed to toxic doses is dependent upon a functional dopamine transporter.  

PubMed

The objective of this study was to determine the importance of the dopamine transporter (DAT) in manganese transport. Excessive manganese exposure is associated with a neurotoxicological disease known as manganism characterized by a specific accumulation of manganese in dopamine-rich brain regions. It has been hypothesized that the DAT mediates this specific transport, but its role in manganese neurotoxicity has not been directly examined. We examined brain tissues from manganese-exposed dopamine transporter knockout (DAT-KO) and wild-type (WT) mice. There was significantly less (p<0.05) manganese in the striatum of exposed DAT-KO mice compared to WT. However, the absence of a functioning DAT did not affect manganese accumulation in other brain regions examined. Furthermore, both iron and divalent metal transporter levels (two known modulators of brain manganese) were similar between DAT-KO and WT mice in all brain regions. These studies demonstrate that the DAT is involved in the facilitation of striatal manganese accumulation and that it may play a critical role in mediating manganese neurotoxicity. PMID:21783617

Erikson, Keith M; John, Carrie E; Jones, Sara R; Aschner, Michael

2005-11-01

354

Bacteriology of Manganese Nodules  

PubMed Central

A cell-free extract from Arthrobacter 37, isolated from a manganese nodule from the Atlantic Ocean, exhibited enzymatic activity which accelerated manganese accretion to synthetic Mn-Fe oxide as well as to crushed manganese nodule. The reaction required oxygen and was inhibited by HgCl2 and p-chloromercuribenzoate but not by Atebrine dihydrochloride. The rate of enzymatic action depended on the concentration of cell-free extract used. The enzymatic activity had a temperature optimum around 17.5 C and was destroyed by heating at 100 C. The amount of heat required for inactivation depended on the amount of nucleic acid in the preparation. In the cell-free extract, unlike the whole-cell preparation, peptone could not substitute for NaHCO3 in the reaction mixture. An enzyme-containing protein fraction and a nucleic acid fraction could be separated from cell extract by gel filtration, when prepared in 3% NaCl but not in seawater. The nucleic acid fraction was not required for enzymatic activity.

Ehrlich, H. L.

1968-01-01

355

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

356

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

357

The genesis of manganese concretions in the Igarra area, Southwestern Nigeria  

NASA Astrophysics Data System (ADS)

An unusual supergene manganese enrichment occurs in the Igarra Formation within the schist belt of southwestern Nigeria. The manganese occurs mainly as peanut-size pisolitic grains or spherical concretions in the weathered schistose units within the formation. The mineralogy of the weathered schists consists of irregularly shaped quartz grains of varying sizes embedded in a matrix composed mainly of sheet-silicates, organic materials and heavy minerals (mostly oxides) which have been almost completely replaced by todorokite. The most abundant of these heavy minerals was probably ilnenite (FeTiO 3) which has now been transformed into pseudo-rutile (Fe 2Ti 3O 9) by the leaching of iron. Ore microscopic studies reveal that the concretions have essentially the same mineralogy as the weathered host rock. But in addition, they also contain some plant remains in the form of decomposing cellular tissues which are generally either completely or partly replaced by todorokite which also replaces the surrounding cement. Microprobe analysis of relicts of the original cement indicates that it was initially thuringitic to chamositic in composition, with FeO content of about 38 weight %. Manganese replacement of the cement was at various stages. The final product of the enrichment process contained over 70 % MnO while the FeO value decreased to only about 2 %. The unusual aspect of this enrichment is the reversal in the usual process of separation of manganese from iron. The reversal is explained as resulting from the transportation of the two elements in the supergene solution in the form of organo-metallic complexes. The manganese complex, being less stable than the iron complex, was precipitated around spots defined by relicts of decomposing plant materials whcih formed a geochemical manganese barrier, while the more stable iron complex still remained in solution. Subsequent erosion concentrated the manganese-rich spots into resistant concretions paving the present surface of the area.

Bafor, B. E.; Mücke, A.

358

Corrosion-induced release of the main alloying constituents of manganese-chromium stainless steels in different media.  

PubMed

The main focus of this paper is the assessment of release rates of chromium, nickel, iron and manganese from manganese-chromium stainless steel grades of low nickel content. The manganese content varied between 9.7 and 1.5 wt% and the corresponding nickel content between 1 and 5 wt%. All grades were exposed to artificial rain and two were immersed in a synthetic body fluid of similar pH but of different composition and exposure conditions. Surface compositional studies were performed using X-ray photoelectron spectroscopy (XPS) in parallel to correlate the metal release process with changes in surface oxide properties. All grades, independent of media, revealed a time-dependent metal release process with a preferential low release of iron and manganese compared to nickel and chromium while the chromium content of the surface oxide increased slightly. Manganese was detected in the surface oxide of all grades, except the grade of the lowest manganese bulk content. No nickel was observed in the outermost surface oxide. Stainless steel grades of the lowest chromium content (approximately 16 wt%) and highest manganese content (approximately 7-9 wt%), released the highest quantity of alloy constituents in total, and vice versa. No correlation was observed between the release rate of manganese and the alloy composition. Released main alloy constituents were neither proportional to the bulk alloy composition nor to the surface oxide composition. PMID:18728902

Herting, Gunilla; Wallinder, Inger Odnevall; Leygraf, Christofer

2008-09-01

359

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

360

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

PubMed

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, 2805, 77871 were mg Kg-1, respectively. Optimal experimental conditions for analysis were investigated. The calibration curves were drawn for different elements. The concentrations determined with our Laser-Induced Breakdown Spectrometers were compared with the results obtained using Inductively Coupled Plasma (ICP) emission spectroscopy. Our study demonstrates that LIBS could be highly appropriate for rapid online analysis of iron slag waste. The relative accuracy of our LIBS system for various elements as compared with ICP method is in the range of 0.001-0.049 at 2.5% error confidence. Limits of detection (LOD) of our LIBS system were also estimated for the elements noted here. The hazardous effects of some of the trace elements present in iron slag exceeding permissible safe limits are also discussed. PMID:17474003

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

2007-05-01

361

29 CFR 1926.1127 - Cadmium.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Cadmium. 1926.1127 Section 1926.1127...Hazardous Substances § 1926.1127 Cadmium. (a) Scope. This standard applies to all occupational exposures to cadmium and cadmium compounds, in all...

2009-07-01

362

29 CFR 1926.1127 - Cadmium.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Cadmium. 1926.1127 Section 1926.1127...Hazardous Substances § 1926.1127 Cadmium. (a) Scope. This standard applies to all occupational exposures to cadmium and cadmium compounds, in all...

2010-07-01

363

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

364

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

365

Passivation of cracking catalysts with cadmium and tin  

SciTech Connect

A method for passivating the adverse catalytic effects of metal contaminants, such as nickel, vanadium and iron, which become deposited on cracking catalyst is disclosed. A passivation promoter comprising elemental tin and/or a tin compound in combination with elemental cadmium and/or a cadmium compound is deposited on the catalyst and the catalyst is passed through a passivation zone having a reducing a atmosphere maintained at an elevated temperature to decrease the adverse catalytic effects of the metal contaminants. The present method is of particular utility where the residence time of the cracking catalyst in the passivation zone is relatively short.

Bertch, C. F.

1985-03-12

366

Tellurium content of marine manganese oxides and other manganese oxides  

USGS Publications Warehouse

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

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

1963-01-01

367

[The influence of occupational exposure to manganese on levels of serum lysozyme].  

PubMed

The serum lysozyme level of workers engaged in the production of iron-manganese alloys was observed. The lysozyme level was statistically significantly increased compared with the control group. There was no evidence with age and years of work. PMID:8834628

Misiewicz, A; Jele?, B; Radwan, K; Karmoli?ski, M; Dziewit, T

1995-01-01

368

Trace Metal Associations with Manganese-Rich Surface Coatings of Lead Service Lines  

EPA Science Inventory

Analysis of lead service line samples from U. S. Environmental Protection Agency?s long-term research program to evaluate control and metal release from domestic drinking water service lines has revealed that Manganese-rich solids also contain Iron and sometimes Aluminum have fre...

369

Manganese oxidation model for rivers  

USGS Publications Warehouse

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

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

1989-01-01

370

FATE OF METHYLCYCLOPENTADIENYL MANGANESE TRICARBONYL  

EPA Science Inventory

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

371

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

PubMed

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

Pribil, R; Adam, J

1973-01-01

372

Cadmium migration in aerospace nickel cadmium cells  

NASA Technical Reports Server (NTRS)

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

Mcdermott, P. P.

1976-01-01

373

Novel MntR-Independent Mechanism of Manganese Homeostasis in Escherichia coli by the Ribosome-Associated Protein HflX.  

PubMed

Manganese is a micronutrient required for activities of several important enzymes under conditions of oxidative stress and iron starvation. In Escherichia coli, the manganese homeostasis network primarily constitutes a manganese importer (MntH) and an exporter (MntP), which are regulated by the MntR dual regulator. In this study, we find that deletion of E. coli hflX, which encodes a ribosome-associated GTPase with unknown function, renders extreme manganese sensitivity characterized by arrested cell growth, filamentation, lower rate of replication, and DNA damage. We demonstrate that perturbation by manganese induces unprecedented influx of manganese in ?hflX cells compared to that in the wild-type E. coli strain. Interestingly, our study indicates that the imbalance in manganese homeostasis in the ?hflX strain is independent of the MntR regulon. Moreover, the influx of manganese leads to a simultaneous influx of zinc and inhibition of iron import in ?hflX cells. In order to review a possible link of HflX with the ? phage life cycle, we performed a lysis-lysogeny assay to show that the Mn-perturbed ?hflX strain reduces the frequency of lysogenization of the phage. This observation raises the possibility that the induced zinc influx in the manganese-perturbed ?hflX strain stimulates the activity of the zinc-metalloprotease HflB, the key determinant of the lysis-lysogeny switch. Finally, we propose that manganese-mediated autophosphorylation of HflX plays a central role in manganese, zinc, and iron homeostasis in E. coli cells. PMID:24794564

Kaur, Gursharan; Sengupta, Sandeepan; Kumar, Vineet; Kumari, Aruna; Ghosh, Aditi; Parrack, Pradeep; Dutta, Dipak

2014-07-15

374

77 FR 21870 - National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List...  

Federal Register 2010, 2011, 2012, 2013

...Note: Toxicity, Conductivity, and Aluminum were listed but were not given an action...phenolics, total organic halogens, nitrates, chloride, conductivity, nickel, aluminum, iron, manganese, cadmium, and...

2012-04-12

375

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

376

Polarization of IRON-REGULATED TRANSPORTER 1 (IRT1) to the plant-soil interface plays crucial role in metal homeostasis.  

PubMed

In plants, the controlled absorption of soil nutrients by root epidermal cells is critical for growth and development. IRON-REGULATED TRANSPORTER 1 (IRT1) is the main root transporter taking up iron from the soil and is also the main entry route in plants for potentially toxic metals such as manganese, zinc, cobalt, and cadmium. Previous work demonstrated that the IRT1 protein localizes to early endosomes/trans-Golgi network (EE/TGN) and is constitutively endocytosed through a monoubiquitin- and clathrin-dependent mechanism. Here, we show that the availability of secondary non-iron metal substrates of IRT1 (Zn, Mn, and Co) controls the localization of IRT1 between the outer polar domain of the plasma membrane and EE/TGN in root epidermal cells. We also identify FYVE1, a phosphatidylinositol-3-phosphate-binding protein recruited to late endosomes, as an important regulator of IRT1-dependent metal transport and metal homeostasis in plants. FYVE1 controls IRT1 recycling to the plasma membrane and impacts the polar delivery of this transporter to the outer plasma membrane domain. This work establishes a functional link between the dynamics and the lateral polarity of IRT1 and the transport of its substrates, and identifies a molecular mechanism driving polar localization of a cell surface protein in plants. PMID:24843126

Barberon, Marie; Dubeaux, Guillaume; Kolb, Cornelia; Isono, Erika; Zelazny, Enric; Vert, Grégory

2014-06-01

377

Separation, preconcentration, and determination of cadmium in drinking waters.  

PubMed

A fast method for separation, preconcentration and determination of cadmium in drinking (source, well, tap) and water for irrigation is described. Iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)3, has the role of colloid precipitate flotation collector. The determination of cadmium in final water solutions preconcentrated by flotation can be performed by flame (FAAS) or electrothermal atomic absorption spectrometry (ETAAS). The method applied, either FAAS or ETAAS, depends of the concentration level of analyte in the water sample investigating. The AAS results are compared with inductively coupled plasma-atomic emission spectrometric measurements (ICP-AES) as an independent method. The ETAAS detection limit of cadmium is 0.002 microgram/L. PMID:11460328

Stafilov, T; Pavlovska, G; Cundeva, K; Zendelovska, D; Paneva, V

2001-05-01

378

Reducing acid leaching of manganiferous ore: Effect of the iron removal operation on solid waste disposal  

Microsoft Academic Search

The process of reducing acid leaching of manganiferous ore is aimed at the extraction of manganese from low grade manganese ores. This work is focused on the iron removal operation. The following items have been considered in order to investigate the effect of the main operating conditions on solid waste disposal and on the process costs: (i) type and quantity

Ida De Michelis; Francesco Ferella; Francesca Beolchini; Francesco Vegliò

2009-01-01

379

The NRAMP6 metal transporter contributes to cadmium toxicity.  

PubMed

NRAMP (natural resistance-associated macrophage protein) homologues are evolutionarily conserved bivalent metal transporters. In Arabidopsis, AtNRAMP3 and AtNRAMP4 play a key role in iron nutrition of the germinating plantlet by remobilizing vacuolar iron stores. In the present paper we describe the molecular and physiological characterization of AtNRAMP6. AtNRAMP6 is predominantly expressed in the dry seed embryo and to a lesser extent in aerial parts. Its promoter activity is found diffusely distributed in cotyledons and hypocotyl, as well as in the vascular tissue region of leaf and flower. We show that the AtNRAMP6 transcript coexists with a partially spliced isoform in all shoot cell types tested. When expressed in yeast, AtNRAMP6, but not its misspliced derivative, increased sensitivity to cadmium without affecting cadmium content in the cell. Likewise, Arabidopsis transgenic plants overexpressing AtNRAMP6 were hypersensitive to cadmium, although plant cadmium content remained unchanged. Consistently, a null allele of AtNRAMP6, named nramp6-1, was more tolerant to cadmium toxicity, a phenotype that was reverted by expressing AtNRAMP6 in the mutant background. We used an AtNRAMP6::HA (where HA is haemagglutinin) fusion, shown to be functional in yeast, to demonstrate through immunoblot analysis of membrane fractions and immunofluorescence localization that, in yeast cells, AtNRAMP6 is targeted to a vesicular-shaped endomembrane compartment distinct from the vacuole or mitochondria. We therefore propose that AtNRAMP6 functions as an intracellular metal transporter, whose presence, when modified, is likely to affect distribution/availability of cadmium within the cell. PMID:19545236

Cailliatte, Rémy; Lapeyre, Bruno; Briat, Jean-François; Mari, Stéphane; Curie, Catherine

2009-09-01

380

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

381

Development of High-Manganese Steels.  

National Technical Information Service (NTIS)

Nonmagnetic properties, high toughness and low cost are the principal characteristics of high-manganese austenitic steels. Taking advantage of these characteristics, three different types of high-manganese austenitic steels suited for different applicatio...

H. Masumoto H. Yoshimura T. Akasawa S. Ohba T. Harada

1983-01-01

382

On the manganese content of cosmic flakes from deep-sea sediments  

NASA Technical Reports Server (NTRS)

Cosmic flakes belong to the category of cosmic microparticles. They occur together with cosmic spherules in sediments. These flakes appear to represent ablation products of iron meteorites burnt away during the passage of a meteorite through the atmosphere by friction against air molecules. Microprobe analyses of flakes from deep sea deposits proved the particles to consist of magnetite which in most cases had been altered into maghemite in the outer zones. This is in agreement with the assumption that they represent fragments of fusion crust of iron meteorites. Most of the flakes, however, contained a small percentage of manganese. This element is not a common constituent of iron meteorites. An attempt is made to explain the presence of manganese in flakes and its absence in cosmic spherules.

Utech, K.

1973-01-01

383

Erosive wear characteristics of spheroidal carbides cast iron  

Microsoft Academic Search

In the present investigation, the authors reported erosive wear property of spheroidal carbides cast irons (SCI). SCI was obtained at the temperature of 1700–1800°C by adding about 10% vanadium to crystallize vanadium spheroidal carbides in the structure. Erosive wear tests were performed on high manganese cast iron with spheroidal carbides (SCI–VMn), high V–Cr–Ni cast iron with spheroidal carbides (SCI–VCrNi) and

Xinba Yaer; Kazumichi Shimizu; Hideto Matsumoto; Tadashi Kitsudo; Tadashi Momono

2008-01-01

384

Features of phase transformations in high-chromium cast irons  

Microsoft Academic Search

1.In contrast to cast irons with 12–14% Cr, in cast irons with 29–30% Cr transformation by bainitic and martensitic mechanisms is prevalent.2.With increasing content of carbon and manganese there is an increase in austenite stability in both the pearlitic and intermediate regions.3.From hardenability diagrams plotted it is possible to select cast iron compositions providing maximum hardness in a given cross

E. V. Rozhkova; S. S. Mikhailovskaya; I. I. Tsypin

1983-01-01

385

Corrosion resistant gray cast iron graphite flake alloys  

SciTech Connect

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, and boron may also be included. Both hardenable and non-hardenable alloys are provided.

Betts, B. A.

1985-10-22

386

Metallation State of Human Manganese Superoxide Dismutase Expressed in Saccharomyces cerevisiae  

PubMed Central

Human manganese superoxide dismutase (Sod2p) has been expressed in yeast and the protein purified from isolated yeast mitochondria, yielding both the metallated protein and the less stable apoprotein in a single chromatographic step. At 30 °C growth temperature, more than half of the purified enzyme is apoprotein that can be fully activated following reconstitution, while the remainder contains a mixture of manganese and iron. In contrast, only fully metallated enzyme was isolated from a similarly constructed yeast strain expressing the homologous yeast manganese superoxide dismutase. Both the manganese content and superoxide dismutase activity of the recombinant human enzyme increased with increasing growth temperatures. The dependence of in vivo metallation state on growth temperature resembles the in vitro thermal activation behavior of human manganese superoxide dismutase observed in previous studies. Partially metallated human superoxide dismutase is fully active in protecting yeast against superoxide stress produced by addition of paraquat to the growth medium. However, a splice variant of human manganese superoxide dismutase (isoform B) is expressed as insoluble protein in both Escherichia coli and yeast mitochondria and did not protect yeast against superoxide stress.

Whittaker, Mei M.; Whittaker, James W.

2012-01-01

387

Manganese pavements on the blake plateau.  

PubMed

Dredge samples and photographs from the Blake Plateau, off the southeast coast of the United States, indicate that a layer of manganese oxide forms pavement that may be continuous over an area af about 5000 square kilometers. The manganese pavement grades into round manganese nodules to the south and east and into phosphate nodules to the west. The Gulf Stream probably maintains a very unusual environment that prohibits deposition of clastic sediment and permits accretion of manganese pavements. PMID:17739590

Pratt, R M; McFarlin, P F

1966-03-01

388

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

389

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

390

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

391

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