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Novel manganese (III) porphyrin containing peripheral [RuCl(dppb)(X-bipy)](+) cations [dppb=1,4-bis(diphenylphosphino) butane and X = -CH3, -OMe, -Cl]. X-ray structure of the cis-[RuCl(dppb)(bipy)(4-Mepy)]PF6 complex

ROMUALDO, Lincoln Lucilio; BOGADO, Andre Luis; VALLE, Eliana M. A.; MOREIRA, Icaro S.; ELLENA, Javier; CASTELLANO, Eduardo Ernesto; ARAUJO, Marcio P. de; BATISTA, Alzir A.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
Português
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New tetraruthenated manganese (III) porphyrins were synthesized and characterized (P-31 NMR, cyclic voltammetry, UV-Vis). This new system presents four units of cationic ``[RuCl(dppb)(X-bipy)](+)``. The electrochemical and catalytic properties of the central manganese (III) show dependence on the characteristics of the peripheral ruthenium complexes as evidenced by the Mn-(III)/Mn-(II) reduction potential. The catalytic oxidation reactions of olefins, cyclohexene and cyclohexane, were carried out in the presence of tetrapyridyl manganese (III) porphyrins containing cationic ruthenium complex and using iodosylbenzene as oxygen donor. The performance of these new tetraruthenated porphyrins systems were evaluated and compared with the manganese porphyrin. (C) 2007 Elsevier Ltd. All rights reserved.

Reciclagem de pilhas: recuperação do manganês na forma do dióxido de manganês eletrolítico.; Recycling of batteries: recovery of manganese in the form of electrolytic manganese dioxide.

Roriz, Elizabeth Rodrigues Rangel
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/12/2009 Português
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Neste trabalho, buscou-se verificar a possibilidade de, com a utilização do processo eletrolítico, se obter dióxido de manganês a partir da reciclagem de pilhas e baterias exauridas, visto a grande demanda por produtos que utilizam esse mineral. Utilizou-se, para tanto, uma solução eletrolítica que continha os íons metálicos: Ca (270mg/L), Ni (3000 mg/L), Co (630 mg/L), Mn(115300 mg/L), Ti (400 mg/L) e Pb (20 mg/L) em meio de ácido sulfúrico, sintetizada, seguindo-se dados de pesquisa anterior. A produção do dióxido de manganês eletrolítico (DME) foi realizada galvanostaticamente, com a utilização de uma fonte estabilizada que monitorava o potencial do eletrodo de trabalho. Utilizaram-se, preliminarmente, um eletrodo de trabalho de chumbo e dois contra-eletrodos de grafite, à temperatura de 98 ºC (±2ºC) e densidade de corrente de 1,69 A.dm-2. Após a verificação preliminar da possibilidade de obtenção do DME, repetiu-se sistematicamente o processo, aplicando-se variações de densidade de corrente (0,61 A.dm-2 a 1,93 A.dm-2) e de pH (0,00 a 1,20). O material obtido com essas variações foi analisado através dos processos de espectrometria de fluorescência de raios-X, difração de raios-X, área superficial específica pelo método BET e microscopia eletrônica de varredura (MEV). Os melhores resultados quanto a eficiência de corrente...

Development of an electrochemical sensor based on nanostructured hausmannite-type manganese oxide for detection of sodium ions

Machini, Wesley B.S.; Martin, Cibely S.; Martinez, Murilo T.; Teixeira, Silvio R.; Gomes, Homero M.; Teixeira, Marcos F.S.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 674-680
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The preparation and electrochemical characterization of hausmannite-type manganese oxide to use as a sensing material for sodium ion is described. This paper reports a new via synthetic to obtain of the hausmannite-type manganese oxide and its application in the construction of modified electrode as a voltammetric sensor. The electrochemical activity of hausmannite-type manganese oxide is controlled by intercalation/deintercalation of the sodium ions within the oxide lattice. The detection is based on the measurement of anodic current generated by oxidation of MnIII-MnIV at electrode surface. The best electrochemical response was obtained for a sensor composition of 20% (w/w) hausmannite oxide in the paste, a TRIS buffer solution of pH 6.0-7.0 and a scan rate of 50 mV s-1. A sensitive linear voltammetric response for sodium ions was obtained in the concentration range of 2.01 × 10 -5-2.09 × 10-4 mol L-1 with a slope of 355 μA L mmol-1 and a detection limit of 7.50 × 10 -6 mol L-1 using cyclic voltammetry. The use of hausmannite has significantly improved the selectivity of the sensor compared to the birnessite-type manganese oxide modified electrode. Under the working conditions, the proposed method was successfully applied to determination of sodium ions in urine samples. © 2013 Elsevier B.V.

Efeitos da exposição sub-aguda de manganês sobre a marcha em ratos; Effects of sub-acute manganese exposure on gait in the rats

Samantha Faim Ferreira
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/06/2014 Português
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A neurotoxicidade por manganês (Manganismo) leva a uma disfunção neurológica caracterizada pelo desenvolvimento de ataxia, hipocinesia, rigidez e tremores. Evidências sugerem que os astrócitos desempenham um papel importante na disfunção cerebral nesta desordem, pois acumulam manganês e sequestram o metal na mitocôndria, o que inibe a oxidação fosforilativa. A exposição aguda ao manganês leva ao acúmulo focal do metal e perda neuronal no cerebelo. No entanto, a relação entre esta deposição localizada de manganês e as manifestações neurológicas não são claras. Neste estudo, foram caracterizados os efeitos do manganês na marcha e no equilíbrio após um tratamento subagudo em ratos adultos da linhagem Sprague-Dawley (CEMIB ¿ UNICAMP). Os animais foram divididos em três grupos: Controle; tratado com Mn e tratado com Mn + NAC (N - acetilcisteína), um anti-oxidante. Os ratos do grupo Mn receberam cloreto de manganês (II) (50 mg/kg de peso corporal, i.p.) diariamente durante 4 dias, enquanto os ratos do grupo Mn + NAC foram co-tratados diariamente com o cloreto de manganês (II) e NAC (163 mg/kg, i.p.). Na análise da marcha o grupo tratado com Mn demonstrou alteração na marcha, vizualizados pela diminuição da área da impressão plantar (comprimento x largura)...

Batch removal of manganese from acid mine drainage using bone char

Sicupira,D. C.; Silva,T. Tolentino; Leão,V. A.; Mansur,M. B.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2014 Português
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The present study investigated batch kinetics and the batch equilibrium of manganese removal from acid mine drainage (AMD) using bone char as an adsorbent. Equilibrium tests revealed that the Langmuir-based maximum manganese uptake capacity was 22 mg g-1 for AMD effluents and 20 mg g-1 for laboratory solutions at a pH ranging from 5.5 to 5.7. The pseudo-second order model best described the manganese kinetics within bone char. Manganese removal was mainly influenced by the operating variables of the solid/liquid ratio and the pH of the aqueous phase. In fact, metal uptake was favored at nearly neutral pH values. The effect of particle size and temperature proved to be insignificant for the investigated operating range. This work also evaluated the mechanism for manganese removal using bone char. Results showed that intraparticle diffusion is the main rate-limiting step; however, additional contributions from boundary layer diffusion may well affect this removal when particles of smaller sizes are used. The final concentration of fluoride and other metals present in the AMD effluent was in agreement with the concentration limit set forth by Brazilian legislation. The present study demonstrated that bone char is a suitable material to be used for the removal of manganese from AMD effluents.

Synthesis of coloured ceramic pigments by using chromite and manganese ores mixtures

Aly,M. H; Ismael,I. S; Bondioli,F
Fonte: Associação Brasileira de Cerâmica Publicador: Associação Brasileira de Cerâmica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2010 Português
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The aim of this work is not only the synthesis of black ceramic pigment with spinel structure using local and inexpensive minerals (chromite and manganese ores) but also throw some light on the relations between the structure and the colour of obtained pigment. Ultimate utilization spinel solid solution in ceramic materials is mostly due to their structure characteristics, their thermal and chemical stability. In this study colour pigments were ned by calcinations at 1250 ºC starting from a mixture of chromite and manganese oxide. Different compositions were tested containing 30, 40 and 50 wt.% of manganese oxide (low and high content respectively). The phase composition and microstructure characterization of both raw material and obtained pigments were evaluated by X-ray diffraction, X-ray fluorescence, polarizing microscope and scanning electron microscope. Furthermore, the colour measurements of the obtained pigments and tiles were evaluated. Composition of all pigments reveal the spinel structure with Cr2FeO4; hematite was also recorded in the mixture of low manganese. The degree of lightness is relatively same in the pigments mixtures of both manganese types. However, tiles could be considered lightness compared with its pigments...

Pharmacokinetic Evaluation of the Equivalency of Gavage, Dietary, and Drinking Water Exposure to Manganese in F344 Rats

Foster, Melanie L.; Bartnikas, Thomas B.; Johnson, Laura C.; Herrera, Carolina; Pettiglio, Michael A.; Keene, Athena M.; Taylor, Michael D.; Dorman, David C.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
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Concerns exist as to whether individuals may be at greater risk for neurotoxicity following increased manganese (Mn) oral intake. The goals of this study were to determine the equivalence of 3 methods of oral exposure and the rate (mg Mn/kg/day) of exposure. Adult male rats were allocated to control diet (10 ppm), high manganese diet (200 ppm), manganese-supplemented drinking water, and manganese gavage treatment groups. Animals in the drinking water and gavage groups were given the 10 ppm manganese diet and supplemented with manganese chloride (MnCl2) in drinking water or once-daily gavage to provide a daily manganese intake equivalent to that seen in the high-manganese diet group. No statistically significant difference in body weight gain or terminal body weights was seen. Rats were anesthetized following 7 and 61 exposure days, and samples of bile and blood were collected. Rats were then euthanized and striatum, olfactory bulb, frontal cortex, cerebellum, liver, spleen, and femur samples were collected for chemical analysis. Hematocrit was unaffected by manganese exposure. Liver and bile manganese concentrations were elevated in all treatment groups on day 61 (relative to controls). Increased cerebellum manganese concentrations were seen in animals from the high-manganese diet group (day 61...

Associations of Early Childhood Manganese and Lead Coexposure with Neurodevelopment

Henn, Birgit Claus; Schnaas, Lourdes; Lamadrid-Figueroa, Héctor; Hernández-Avila, Mauricio; Hu, Howard; Téllez-Rojo, Martha María; Ettinger, Adrienne S; Schwartz, Joel David; Amarasiriwardena, Chitra J.; Bellinger, David C.; Wright, Robert O.
Fonte: National Institute of Environmental Health Sciences Publicador: National Institute of Environmental Health Sciences
Tipo: Artigo de Revista Científica
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Background: Most toxicologic studies focus on a single agent, although this does not reflect real-world scenarios in which humans are exposed to multiple chemicals. Objectives: We prospectively studied manganese–lead interactions in early childhood to examine whether manganese–lead coexposure is associated with neurodevelopmental deficiencies that are more severe than expected based on effects of exposure to each metal alone. Methods: Four hundred fifty-five children were enrolled at birth in an longitudinal cohort study in Mexico City, provided blood samples, and were followed until 36 months of age. We measured lead and manganese at 12 and 24 months and assessed neurodevelopment at 6-month intervals from 12 to 36 months of age using Bayley Scales of Infant Development–II. Results: Mean (± SD) blood concentrations at 12 and 24 months were, respectively, 24.7 ± 5.9 μg/L and 21.5 ± 7.4 μg/L for manganese and 5.1 ± 2.6 μg/dL and 5.0 ± 2.9 μg/dL for lead. Mixed-effects models, including Bayley scores at five time points, showed a significant interaction over time: highest manganese quintile × continuous lead; mental development score, β = –1.27 [95% confidence interval (CI): –2.18, –0.37]; psychomotor development score...

Role of manganese in the pathogenesis of portal-systemic encephalopathy.

Pomier-Layrargues, Gilles; Rose, Christopher F.; Spahr, Laurent; Zayed, Joseph; Normandin, Louise; Butterworth, Roger F.
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Artigo de Revista Científica
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Amongst the potential neurotoxins implicated in the pathogenesis of hepatic encephalopathy, manganese emerges as a new candidate. In patients with chronic liver diseases, manganese accumulates in blood and brain leading to pallidal signal hyperintensity on T1-weighted Magnetic Resonance (MR) Imaging. Direct measurements in globus pallidus obtained at autopsy from cirrhotic patients who died in hepatic coma reveal 2 to 7-fold increases of manganese concentration. The intensity of pallidal MR images correlates with blood manganese and with the presence of extrapyramidal symptoms occurring in a majority of cirrhotic patients. Liver transplantation results in normalization of pallidal MR signals and disappearance of extrapyramidal symptoms whereas transjugular intrahepatic portosystemic shunting induces an increase in pallidal hyperintensity with a concomitant deterioration of neurological dysfunction. These findings suggest that the toxic effects of manganese contribute to extrapyramidal symptoms in patients with chronic liver disease. The mechanisms of manganese neurotoxicity are still speculative, but there is evidence to suggest that manganese deposition in the pallidum may lead to dopaminergic dysfunction. Future studies should be aimed at evaluating the effects of manganese chelation and/or of treatment of the dopaminergic deficit on neurological symptomatology in these patients.

Improvement of screening for manganese efficiency by producing seed with similar manganese content in different genotypes and genetic stocks

Khabaz Saberi, Hossein; Graham, Robin David
Fonte: Marcel Dekker Publicador: Marcel Dekker
Tipo: Artigo de Revista Científica
Publicado em //2002 Português
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Genetic improvement of manganese efficiency of crops demands a precise bioassay that avoids the confounding effect of seed manganese on the bioassay for the trait, for a proper comparison of the genotypes the seed manganese content must be similar. Variation in seed manganese can be minimized by the addition of manganese to individual seeds to be planted providing the effect of seed manganese content on early growth and development for the chosen genotype has been determined. It was hypothesized that growing the plants as mono-culms in very small pots under subclinical manganese deficiency would limit grain yield and yield attribute among genotypes, resulting in seed with less variation in manganese content across genotypes. The effect on yield and components of soil fertility ranging from University of California (UC) potting mix, fortified with Osmocote, to 100% manganese-deficient calcareous sand from Wangary, South Australia (Psamment) was determined for 20 bread wheat genotypes and breeding lines. It was observed that a mix of 70% UC and 30% Calcareous Wangary sand from South Australia in small pots minimized variation in grain yield and its components (number of tillers, number of seeds/head, weight of seed) and also lowered variation in seed manganese content among wheat genotypes. This was confirmed in pots of 70/30 UC-sand mix for five bread wheat cultivars...

Extracellular zinc competitively inhibits manganese uptake and compromises oxidative stress management in Streptococcus pneumoniae

Eijkelkamp, B.; Morey, J.; Ween, M.; Ong, C.L.; McEwan, A.; Paton, J.; McDevitt, C.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
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Streptococcus pneumoniae requires manganese for colonization of the human host, but the underlying molecular basis for this requirement has not been elucidated. Recently, it was shown that zinc could compromise manganese uptake and that zinc levels increased during infection by S. pneumoniae in all the niches that it colonized. Here we show, by quantitative means, that extracellular zinc acts in a dose dependent manner to competitively inhibit manganese uptake by S. pneumoniae, with an EC50 of 30.2 µM for zinc in cation-defined media. By exploiting the ability to directly manipulate S. pneumoniae accumulation of manganese, we analyzed the connection between manganese and superoxide dismutase (SodA), a primary source of protection for S. pneumoniae against oxidative stress. We show that manganese starvation led to a decrease in sodA transcription indicating that expression of sodA was regulated through an unknown manganese responsive pathway. Intriguingly, examination of recombinant SodA revealed that the enzyme was potentially a cambialistic superoxide dismutase with an iron/manganese cofactor. SodA was also shown to provide the majority of protection against oxidative stress as a S. pneumoniae ΔsodA mutant strain was found to be hypersensitive to oxidative stress...

Particulate matter-bound manganese in the Santander bay (northern Spain): emission sources and air levels; Manganeso en material particulado en la bahía de Santander (norte de España): fuentes de emisión y niveles en aire ambiente

Di Gianvito, Alessandra
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: Dissertação de Mestrado
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ABSTRACT: The present study deals with the particulate matter-bound manganese in the Santander Bay (Northern Spain). The purpose of this project is to analyze the industrial manganese emission sources located in this area to obtain air manganese levels by CALPUFF modelling. Air pollution is characterized by the suspension of fine, solid and liquid particles, known as aerosol. The presence of heavy metals is due to very small particles that can be inhaled and affect human health. Particle-bound metals are mainly emitted from anthropogenic activities, for instance industrial factories as well as combustion of fuel. These pollutants tend to be transported moving from the emission point to farther zones where humans live and can be adversely affected by their concentration. In fact many studies that identify effects of high manganese levels on human health have been developed. However a specific European Directive about manganese limits in the air does not exist yet because it is not considered a carcinogenic element. Only some guidelines have been proposed by world organizations such us WHO and USEPA, but they are not compulsory values. The present work aims at obtaining Mn concentration values in the Santander Bay (Alto Maliaño and Guarnizo sites) by the use of a dispersion modeling system...

ADSORPTION OF MANGANESE FROM ACID MINE DRAINAGE EFFLUENTS USING BONE CHAR: CONTINUOUS FIXED BED COLUMN AND BATCH DESORPTION STUDIES

Sicupira,D. C.; Tolentino Silva,T.; Ladeira,A. C. Q.; Mansur,M. B.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2015 Português
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AbstractIn the present study, continuous fixed bed column runs were carried out in an attempt to evaluate the feasibility of using bone char for the removal of manganese from acid mine drainage (AMD). Tests using a laboratory solution of pure manganese at typical concentration levels were also performed for comparison purposes. The following operating variables were evaluated: column height, flow rate, and initial pH. Significant variations in resistance to the mass transfer of manganese into the bone char were identified using the Thomas model. A significant effect of the bed height could only be observed in tests using the laboratory solution. No significant change in the breakthrough volume could be observed with different flow rates. By increasing the initial pH from 2.96 to 5.50, the breakthrough volume was also increased. The maximum manganese loading capacity in continuous tests using bone char for AMD effluents was 6.03 mg g-1, as compared to 26.74 mg g-1 when using the laboratory solution. The present study also performed desorption tests, using solutions of HCl, H2SO4, and water, aimed at the reuse of the adsorbent; however, no promising results were obtained due to low desorption levels associated with a relatively high mass loss. Despite the desorption results...

A Child with Chronic Manganese Exposure from Drinking Water

Woolf, Alan David; Wright, Robert O.; Amarasiriwardena, Chitra J.; Bellinger, David C.
Fonte: U.S. Department of Health and Human Services & National Institute of Environmental Health Sciences Publicador: U.S. Department of Health and Human Services & National Institute of Environmental Health Sciences
Tipo: Artigo de Revista Científica
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The patient's family bought a home in a suburb, but the proximity of the house to wetlands and its distance from the town water main prohibited connecting the house to town water. The family had a well drilled and they drank the well water for 5 years, despite the fact that the water was turbid, had a metallic taste, and left an orange-brown residue on clothes, dishes, and appliances. When the water was tested after 5 years of residential use, the manganese concentration was elevated (1.21 ppm; U.S. Environmental Protection Agency reference, < 0.05 ppm). The family's 10-year-old son had elevated manganese concentrations in whole blood, urine, and hair. The blood manganese level of his brother was normal, but his hair manganese level was elevated. The patient, the 10-year-old, was in the fifth grade and had no history of learning problems; however, teachers had noticed his inattentiveness and lack of focus in the classroom. Our results of cognitive testing were normal, but tests of memory revealed a markedly below-average performance: the patient's general memory index was at the 13th percentile, his verbal memory at the 19th percentile, his visual memory at the 14th percentile, and his learning index at the 19th percentile. The patient's free recall and cued recall tests were all 0.5-1.5 standard deviations (1 SD = 16th percentile) below normal. Psychometric testing scores showed normal IQ but unexpectedly poor verbal and visual memory. These findings are consistent with the known toxic effects of manganese...

Manganese deficiency in peach trees: prognosis and fruit quality

Val Falcón, Jesús; Montañés García, Luis; Sanz Encinas, Manuel
Fonte: International Society for Horticultural Science Publicador: International Society for Horticultural Science
Tipo: Comunicación de congreso Formato: 18106 bytes; application/pdf
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The definitive version is available at: http://www.actahort.org/; In previous studies was pointed out that it may be possible to detect subclinical manganese deficiencies in the field before visual symptoms have developed. In this work, by in situ fluorescence measurements, we demonstrate that it is possible to predict, at the beginning of the season, which trees will develop manganese deficiency several months later. Fo/Fm ratio of young manganese deficient leaves without visible symptoms was higher than the measured in the equivalent control leaves. More than 80% of concordance, between the initial measurements and the symptoms lately developed was reached. This facts made us to believe that it could be possible to predict manganese deficiency just when the first leaves appeared and therefore apply effective correcting measures to prevent manganese deficiency in peach trees. Economical repercussions of manganese deficiency, in terms of yield and fruit characteristics, are also discussed.; Peer reviewed

Manganese micro-nodules on ancient brick walls

López-Arce, Paula; García-Guinea, Javier; García Fierro, José Luis
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 465076 bytes; application/pdf
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8 pages.-- Printed version published on 20 Jan 2003.; Romans, Jews, Arabs and Christians built the ancient city of Toledo (Spain) with bricks as the main construction material. Manganese micro-nodules (circa 2 μm in diameter) have grown under the external bio-film surface of the bricks. Recent anthropogenic activities, such as, industrial emissions, foundries or traffic and housing pollution have further altered these old bricks. The energy-dispersive X-ray microanalyses (XPS) of micro-nodules shows Al, Si, Ca, K, Fe and Mn, with some carbon species. Manganese atoms are present only as Mn4+ (pyrolusite phase, MnO2) and iron as Fe3+ (FeOOH-Fe2O3 mixtures). The large concentration of algae biomasses of the River Tagus and the Torcón and Guajaraz reservoirs suggest manganese micro-nodules are formed either from water solutions rich in anthropogenic MnO4K in a reduction environment (from Mn7+ to Mn4+) or by oxidation mechanisms from dissolved Mn2+ (from Mn2+ to Mn4+) linked to algae biofilm onto the ancient brick surfaces. Ancient wall surfaces were also studied by scanning electron microscopy (SEM-EDS) and X-ray diffraction (XRD). Chemical and biological analyses of the waters around Toledo are also analysed for possible sources of manganese. Pyrolusite micro-nodules on ancient brick walls are good indicators of manganese pollution.; The Spanish DGICYT PB98-0501 and European PNICYDT 1FD97-0959-C03-01 projects supported the work.; Peer reviewed

Early indications for manganese oxidation state changes during photosynthetic oxygen production: A personal account

Wydrzynski, Thomas
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
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One of the major questions yet to be answered in photosynthesis research today is what is the chemical mechanism for the oxidation of water into molecular oxygen. It is well established that an inorganic cluster of four manganese ions and at least one calcium ion form the catalytic core. As the oxidation potential generated by the Photosystem II reaction center is accumulated over the four sequential steps needed to produce O2, changes in the oxidation state of the catalytic manganese occur, though the formal oxidation states that are involved are still a matter of considerable debate. Much of what is currently known has come from direct measurements of the catalytic manganese using electron paramagnetic resonance (EPR) and X-ray spectroscopy. However, in the early attempts to attack this problem, the catalytic manganese was monitored indirectly by its paramagnetic effect on the nuclear magnetic resonance (NMR) relaxation rates of solvent water protons. In this contribution, a description of the proton relaxation rate phenomenon and its use to indicate manganese oxidation state changes during O2 production is presented.

Genesis of manganese oxide mineralization in the Boleo region and Concepción Peninsula, Baja California Sur: constraints from Pb-Sr isotopes and REE geochemistry

Del Rio-Salas,Rafael; Ochoa-Landín,Lucas; Eastoe,Christopher J.; Ruiz,Joaquín; Meza-Figueroa,Diana; Valencia-Moreno,Martín; Zúñiga-Hernández,Hugo; Zúñiga-Hernández,Luis; Moreno-Rodríguez,Verónica; Mendívil-Quijada,Héctor
Fonte: Instituto de Geología, UNAM Publicador: Instituto de Geología, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 Português
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Manganese oxide mineralization on the eastern coast of Baja California Sur is intimately related to the Neogene tectonic evolution of the Gulf of California. Manganese is closely associated with the Cu-Co-Zn mineralization of the Boleo district and nearby deposits of Santa Rosalía region and Concepción peninsula. Trace element and rare earth element geochemistry of the manganese oxides provides clear evidence of a hydrothermal origin and excludes the hydrogenous nature for these deposits. Lead isotope data suggest that metal sources for the manganese mineralization along the eastern coast Baja California Sur are mostly the Miocene Andesite of Sierra Santa Lucía volcanics and the Peninsular Ranges batholith rocks. The strontium isotope data indicate that the mineralizing fluids involved in the manganese mineralization from Boleo district resulted from the interaction of two end-members: (1) the Sierra Santa Lucía volcanic rocks and (2) the gypsum member of the Boleo Formation. The geological observations and the available isotope and geochronological data suggest a southward migration of the hydrothermal processes in response to the evolving tectonic context of the opening of the Gulf of California.

The manganese ferroalloys industry in southern Africa

Steenkamp,J.D.; Basson,J.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 Português
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Southern Africa has a history rich in the pyrometallurgical processing of ores. Two of the alloys produced are high-carbon ferromanganese (74-83 per cent Mn) and silicomanganese (59-67 per cent Mn and 14-31 per cent Si). The largest land-based manganese ore deposit in the world is based in the Northern Cape Province of South Africa. In 2010, 6.3 Mt of ore from the deposit was exported, mainly to China, Norway, Japan, and India, and an estimated 1.1 Mt beneficiated locally to produce manganese ferroalloys. In southern Africa the producers of manganese ferroalloys are Metalloys and Assmang, and of silicomanganese Transalloys, Mogale Alloys, and Match Corporation. Submerged arc furnace technology is utilized in the production of high-carbon ferromanganese (HCFeMn) and silicoman-ganese, applying the discard slag practice in both instances. The carbon content of HCFeMn is reduced using converter technology and that of SiMn using the Perrin process. Ninety per cent of the world's manganese ferroalloys production is consumed by the steel industry. The consumption (and production) of manganese ferroalloys therefore closely follows worldwide steel production. From 2001 to 2010, the doubling of the worldwide production of manganese ferroalloys can be attributed to an increase in production capacity in Asia and Oceania...

The recovery of manganese products from ferromanganese slag using a hydrometallurgical route

Baumgartner,S.J.; Groot,D.R.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2014 Português
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The ferromanganese industry is under pressure to deal with the slag arising from the production of ferromanganese, which is discarded in landfills or slag heaps. This material poses an environmental and health risk to surrounding ecosystems and communities, and disposal costs are increasing. Ferromanganese slag contains an appreciable amount of residual manganese metal, which can be exploited. Previous work has shown that the slag can be leached fully, while rejecting the silica to a residue. The methods that were investigated to recover manganese from the leach solution included hydroxide precipitation to upgrade the leach solution followed by manganese carbonate precipitation to produce a pure manganese carbonate product or a manganese carbonate furnace feed material, which would be recycled to increase manganese recoveries in the production of ferromanganese. In addition, electrowinning of electrolytic manganese dioxide from the leach solution was studied. The methods were compared in terms of selectivity, costs, and product quality. Co-recovery of the leach residue, which is a potential cement additive, is discussed. Among the methods investigated to upgrade the pregnant leach solution, hydroxide precipitation utilizing ammonia to adjust the pH appears to be the most effective in removing major impurities such as iron...