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| Registros recuperados: 20 | |
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| Thoby, Mary. |
| The redox conditions of the oceans evolved considerably during the Precambrian. This is mainly due to the arrival of the oxygen, at first generating oxygen oases, and then accumulating in the atmosphere during the Great Oxidation Event (GOE) ca. 2.45 Ga. However, the earliest traces of free oxygen during these periods, and the mechanisms of their sedimentary expression, remain poorly understood. For over a decade, the isotopic composition of molybdenum (δ98Mo) in sediments has been used as a global marine redox proxy.An elemental and isotopic study of the different phases constituting carbonate rocks was carried out using sequential digestions performed on carbonates of different ages and depositional environments. The results show that Mo is primarily... |
| Tipo: Text |
Palavras-chave: Redox; Précambrien; Carbonates; Molybdène; Isotopes; Attaque séquentielle; Sequential digestion; Precambrian; Molybdenum. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00663/77462/79129.pdf |
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| Nahas,Ely. |
| ABSTRACTThis work studied the acid phosphatase (APase) activity from culture medium (extracellular, eAPase) and mycelial extract (intracellular, iAPase) ofAspergillus niger F111. The influence of fungus growth and phosphate concentration of the media on the synthesis and secretion of phosphatase was demonstrated. The effects of pH, substrate concentration and inorganic and organic compounds added to the reaction mixture on APase activity were also studied. Both enzymes were repressed by high concentrations of phosphate. Overexpression of iAPase in relation to eAPase was detected; iAPase activity was 46.1 times higher than eAPase. The maximal activity of eAPase was after 24h of fungus growth and for iAPase was after 96h. Optimal pH and substrate... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Enzyme inhibitors; Molybdenum; Overexpression; Phosphate; Soil chemical characteristics. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132015000500658 |
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| Quaggio,J. A.; Gallo,P. B.; Owino-Gerroh,C.; Abreu,M. F.; Cantarella,H.. |
| Liming acid soils is considered to assure the availability of Mo in crops. Additionally, in peanuts (Arachis hypogaea L.) the positive response to liming is associated to a better supply of Ca+2, Mo for the nitrogenase-complex activity, and other non-nitrogen fixing activities of the crop. This study was thus undertaken to assess the effect of lime, Mo, and the lime-Mo interaction on peanut crop, on an acid Ultisol at the Mococa Experimental Station, Instituto Agronômico, São Paulo State, Brazil, from 1987 to 1990. A randomized complete block design with four replications, in a 4 x 4 factorial arrangement, was used in the study. The factors included four lime rates (0, 2, 4, and 6 t ha-1) broadcast and incorporated into the soil, and Mo (0, 100, 200, and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Arachis hypogaea; Liming; Molybdenum; Nitrogen fixation. |
| Ano: 2004 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832004000400008 |
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| Ribera,Alejandra E; Mora,Maria de la Luz; Ghiselini,Vanessa; Demanet,Rolando; Gallardo,Felipe. |
| We studied the phosphorous (P) and molybdenum (Mo) relationship in soil and red clover (Trifoliumpratense L.) in a non limed and limed acid Andisol of Southern Chile. In soil, we evaluated the effect of different liming (0 and 2000 mg kg-1), P (0, 200 and 400 mg kg-1), and Mo (0, 0.58 and 0.96 mg kg-1) doses supply on soil available Mo. In addition, the availability of P and Calcium (Ca) in treated soils was determinated. In red clover, we studied the Mo and P shoot concentrations and dry matter yield in response to the different treatments applied to the soil. Also, we measured the changes produced by Mo uptake in shoot Cu concentrations. The results showed that both, lime and more strongly P and Mo additions significantly (P ≥ 0.05) increased... |
| Tipo: Journal article |
Palavras-chave: Phosphorous; Molybdenum; Andisol; Red clover. |
| Ano: 2010 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912010000100008 |
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| Picco,Sebastián; Ponzzinibio,M. Virginia; Mattioli,Guillermo; Rosa,Diana; Minatel,Leonardo; Fazzio,Luis; Seoane,Analía. |
| Molybdenosis is a disease caused by the depressing effect of molybdenumn (Mo) on the physiological availability of Copper (Cu). The present study was carried out in order to analyze the ability of Mo to cause damage on the DNA integrity and changes in membrane fatty acids by oxidative damage. Holstein male calves were fed a Mo-supplemented diet for 9 months. Variables evaluated were plasma Cu concentration, erythrocyte Cu content and SOD activity, comet assay and analysis of the fatty acid composition of erythrocyte membranes. The statistical design was a completely randomized with one single factor and two replications. Copper plasma concentration, erythrocyte copper concentration and Cu/Zn SOD activity were analyzed using the t test. Chi-square test was... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Molybdenum; Copper deficiency; Oxidative damage; DNA damage; Bos taurus; SOD activity. |
| Ano: 2012 |
URL: http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1405-31952012000200002 |
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| Van Langenhove, Leandro; Depaepe, Thomas; Vicca, Sara; Van Den Berge, Joke; Stahl, Clement; Courtois, Elodie; Weedon, James; Urbina, Ifigenia; Grau, Oriol; Asensio, Dolores; Peñuelas, Josep; Boeckx, Pascal; Richter, Andreas; Van Der Straeten, Dominique; Janssens, Ivan A.. |
| Background and aims Biological fixation of atmospheric nitrogen (N2) is the main pathway for introducing N into unmanaged ecosystems. While recent estimates suggest that free-living N fixation (FLNF) accounts for the majority of N fixed in mature tropical forests, the controls governing this process are not completely understood. The aim of this study was to quantify FLNF rates and determine its drivers in two tropical pristine forests of French Guiana. Methods We used the acetylene reduction assay to measure FLNF rates at two sites, in two seasons and along three topographical positions, and used regression analyses to identify which edaphic explanatory variables, including carbon (C), nitrogen (N), phosphorus (P) and molybdenum (Mo) content, pH, water... |
| Tipo: Text |
Palavras-chave: Free-living nitrogen fixation; Tropical forest; French Guiana; Nutrients; Phosphorus; Molybdenum. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00487/59901/63083.pdf |
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| Paolicchi,F.; Perea,J.; Cseh,S.; Morsella,C.. |
| To study the deficiency of minerals and its relationship with Paratuberculosis, blood, serum, and fecal samples were obtained from 75 adult bovines without clinical symptoms of the disease and from two bovines with clinical symptoms of the disease, from two beef herds with a previous history of Paratuberculosis in the Province of Buenos Aires, Argentina. Serum samples were processed by ELISA and feces were cultured in Herrolds medium. Copper, zinc and iron in serum were quantified by spectrophotometry and selenium was measured by the activity of glutathione peroxidase. We also determined copper, zinc, iron and molybdenum concentrations in pastures and the concentration of sulfate in water. Mycobacterium avium subsp paratuberculosis (Map) was isolated from... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Paratuberculosis; Micronutrients; Selenium; Molybdenum; Copper. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822013000100022 |
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| Chagas,Eduardo; Araújo,Adelson Paulo; Alves,Bruno José Rodrigues; Teixeira,Marcelo Grandi. |
| Seeds with a high concentration of P or Mo can improve the growth and N accumulation of the common bean (Phaseolus vulgaris L.), but the effect of enriched seeds on biological N2 fixation has not been established yet. This study aimed to evaluate the effect of seeds enriched with P and Mo on growth and biological N2 fixation of the common bean by the 15N isotope dilution technique. An experiment was carried out in pots in a 2 x 3 x 2 x 2 factorial design in randomized blocks with four replications, comprising two levels of soil applied P (0 and 80 mg kg-1), three N sources (without N, inoculated with rhizobia, and mineral N), two seed P concentrations (low and high), and two seed Mo concentrations (low and high). Non-nodulating bean and sorghum were used... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Molybdenum; Nodulation; Phaseolus vulgaris. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832010000400009 |
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| Lacombe, Marielle; Garcon, Veronique; Thouron, Daniele; Le Bris, Nadine; Comtat, Maurice. |
| From the study of molybdenum oxidation in aqueous solutions we developed a semi-autonomous method to detect silicate in aqueous samples. Molybdenum oxidation was used to form molybdate in acidic media. The silicomolybdic complex formed with silicate is detectable by amperometry or cyclic voltammetry. The new electrochemical method is in good agreement with the method conventionally used for environmental water silicate analysis. In the second stage, a completely reagentless method was developed using molybdate and proton produced during molybdenum oxidation. Reproducibility tests show a precision of 2.6% for a concentration of 100 mu mol L-1. This new method will be Very Suitable for the development of new autonomous silicate sensors easy to handle and... |
| Tipo: Text |
Palavras-chave: Cyclic voltammetry; Amperometry; Reagentless; Silicate; Molybdenum. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6114.pdf |
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| Reitz, Anja; Thomson, John; De Lange, Gert J.; Hensen, Christian. |
| [ 1] The residual dark unit of the most recent eastern Mediterranean sapropel (S1) is usually overlain by sediments with enhanced concentrations of MnO(x) in two separated layers. The variability and magnitude of the Mn enrichment at different locations and water depths indicate that Mn must have been added preferentially to sediments at intermediate ( 1 - 2 km) water depths. We propose a two-stage mechanism for the Mn enrichment that involves decreasing oxygenation with increasing water depth. This mechanism involves the loss of reduced Mn(2+) from the deepest sediments (> 2 km water depth) into overlying anoxic waters and a variable gain of MnOx in sediments in contact with oxygenated waters at shallower depth. In the S1 unit that receives the extra... |
| Tipo: Text |
Palavras-chave: Manganese; Sapropel S1; Eastern Mediterranean; Molybdenum; Lithium. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34529/33426.pdf |
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| Wang, Xudong; Bayon, Germain; Kim, Jung-hyun; Lee, Dong-hun; Kim, Dahae; Guéguen, Bleuenn; Rouget, Marie-laure; Barrat, Jean-alix; Toffin, Laurent; Feng, Dong. |
| Seeping of methane-rich fluids at submarine cold seeps drives intense microbial activity and precipitation of authigenic carbonates. Some trace elements play an important role in the biogeochemical processes operating at cold seeps, especially as specific enzymatic co-factors related to methanogenesis and the anaerobic oxidation of methane (AOM). However, it is unclear whether microbial trace metal utilization can be traced by the geochemical composition of seep carbonates. In this study, we analyzed a series of authigenic carbonate samples recovered from various seep settings worldwide and report for the first time trace element concentrations for total lipid fractions, combined with biomarker analyses and determination of elemental abundances in... |
| Tipo: Text |
Palavras-chave: Seep carbonate; Lipid compounds; Trace elements; Tungsten; Nickel; Cobalt; Molybdenum. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00511/62311/66562.pdf |
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| Registros recuperados: 20 | |
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