High Amounts Of Manganese Research Articles

Influence of different soil uses in the Pampa biome, southern Brazil, on fungal communities

Anthropogenic activities in any natural ecosystem cause changes that affect the physical and biological environment, causing degradation. Likewise, these activities can cause significant changes in the chemical and physical factors of the soil, also impacting the microbiological community. The study aimed to evaluate the influence of soil biochemical and physicochemical characteristics on the development of fungal communities in three different soils of the Pampa biome. The soil types selected were: native forest, Eucalyptus plantation and pasture area, in two distinct periods: hot and cold. Microbiological, physicochemical and biochemical analyses of the soils were carried out. The following genera and species of fungi were identified:Aspergillus sp., Aspergillus niger, Fusarium sp., Geotrichum sp., Isaria sp., Penicillium sp., Scedosporium sp., Trichoderma sp., Verticilliumsp. The results showed that the fungal community is being affected by soil composition characteristics, regardless of the sampled areas. Aspergillus sp. is associated with higher amounts of manganese, boron and the Ca+Mg/K ratio in the soil, while A. niger and Trichodermasp. have a negative relationship with these variables. Aspergillus sp. showed a high ability to tolerate Mn. The most diverse area was pasture in the warm period, and the least diverse was Eucalyptus plantation in the cold period. The analyzed taxa had a reduction in the cold period compared to the warm one, except for Aspergillussp. in the Eucalyptus area, which presented a greater amount in the cold period compared to the hot period. It can be seen that the use of soil in the Pampa biome for planting monocultures or for generating pastures interferes with its characteristics and distinctly affects the fungal community.

Biosorption of heavy metals in automobile panel workshop effluent using Bacillus safensis LAU13

Heavy metals are natural constituents of the environment, but improper application for human activities has altered their geochemical compositions and biochemical balance. There is a need to remediate heavy metals released into natural resources through anthropogenic activities. This paper centers on remediation by biosorption as an effective technique for reduction in the concentration of Mn, Co, Cu, Fe, Zn, Hg, Se, Cr, Pb and Cd using Bacillus safensis LAU13.Wastewater samples were obtained from Gbade automobile panel workshop, Grammar School area, Ogbomoso, Nigeria. Initial concentrations of heavy metals in the effluent samples after digestion were determined through Atomic Absorption Spectrometery (AAS). The glucose enriched wastewater samples were autoclaved, the inoculums cultured and subjected to bio-treatment using 250, 500, 750 and1000 µL dosages of Bacillus safensis LAU 13 (Gen Bank accession number KJ461434), a Gram-positive, mesophilic, spore-forming, aerobic and chemo- heterotrophic bacterium. Optical density of inoculated samples was determined through spectrophotometer and the growth monitored for 48hrs. Residual pellets were subjected to Scanning Electron Microscopy (SEM). Results showed that 100% removal was achieved for Mn2+ and Co3+. Chromium was reduced to a very minimal concentration, Zn2+, Cu3+, Pb4+and Se4+ were above average in the irremediation. Fe2+and Cd2+were remediated below average but very low remediation of Hg2+ with less than one percent removal. Optical density increased significantly showing rapid growth of micro-organism irrespective of glucose supplement, and 250 µL inoculum dosage has the optimum performance. SEM micrographs indicate certain accumulated aggregates taken as remediated heavy metals. The study confirmed efficiency of biosorption technique as an alternative to the conventional treatment methods of huge cost, and high precipitates and slurry. B. safensis LAU13 is therefore recommended as a bio-remediating agent in treating automobile workshop effluents with high amount of manganese, cobalt, chromium, zinc, copper, lead and selenium.

Effect of Polishing on Electrochemical Behavior and Passive Layer Composition of Different Stainless Steels.

In the present paper, the effect of different polishing methods (mechanical and electrochemical) on passive layer chemistry and the corrosion behavior of stainless steels is investigated. It was found that CrNiMo austenites have a substantially better corrosion behavior than CrMnN ones. The nickel is enriched underneath the passive layer, while manganese tends to be enriched in the passive layer. It was also noted that immersion of manganese into an electrolyte preferentially causes its dissolution. It was found that high amounts of chromium (27.4%), molybdenum (3.3%), nickel (29.4%), with the addition of manganese (2.8%) after mechanical grinding, generates a better corrosion resistance than after electrochemical polishing. This is most likely because of the introduction of phosphates and sulfates into its structure, which is known for steels with a high amount of manganese. For highly alloyed CrNiMo steels, which do not contain a high amount of manganese, the addition of phosphates and/or sulphates via the electropolishing process results in a decrease in pitting corrosion resistance, which is also observed for high manganese steels. Electropolished samples show detrimental corrosion properties when compared to mechanically polished samples. This is attributed to substantial amounts of sulfate and phosphate from the electropolishing electrolyte present in the surface of the passive layer.

Manganese spreads neurodegeneration

Neurodegeneration Chronic exposure to high amounts of manganese, such as that experienced by welders, is associated with symptoms of Parkinson's disease. A hallmark of the disease is aggregation of the protein α-synuclein, which is toxic to neurons. Harischandra et al. found that exosomes isolated from serum collected from welders contained misfolded α-synuclein. In cultured cells and mouse models, exposure to manganese or isolated manganese-induced exosomes promoted the transfer of α-synuclein between neurons and microglia, which induced inflammation and neuronal cell death. Sci. Signal. 12 , eaau4543 (2019).

Room temperature grain boundary sliding behavior of fine-grained Mg-Mn alloys

The impact of chemical composition, i.e., the manganese element, on room-temperature mechanical properties and its deformation behavior was examined using a series of Mg-Xat% (X = 0.05, 0.1, 0.3, 0.45, 0.6 and 0.8) Mn binary alloys. The average grain size of these alloys was controlled to be 2–3 µm by extrusion temperature. The manganese segregates at grain boundaries, and the fraction of dispersed particles increases with increasing manganese addition. The results obtained from tensile tests reveal that the chemical composition is unlikely to affect the strain rate dependence, which is the major deformation mechanism. The strain rate sensitivity (m-value) is calculated to be ~ 0.1 and ~ 0.2–0.3 in the quasi-static and in the low strain rate regimes, respectively, for all the alloys. This indicates that the contribution of grain boundary sliding on deformation increases at lower strain rates. On the other hand, the elongation-to-failure in tension is clearly influenced by manganese concentration. The chemical composition of 0.3 at% manganese brings about a good ductility of nearly 95% and 145% in the strain rates of 1 × 10−3 and 1 × 10−5 /s, respectively; however, a further manganese addition leads to a decrease in the elongation-to-failure. Deformed microstructural observations show that cavities nucleate at the interface between matrix and particles without any deformation twin formation, and they are the origin of fracture. A high amount of manganese causes formation of the dispersed particles; as a result, it is ineffective to improve the ductility.

Assessment of metal pollution in the Anzali Wetland sediments using chemical partitioning method and pollution indices

Metal pollution in aquatic ecosystems is of immense importance. Under various environment circumstances, the metal contents of sediments can enter into the overlying water body leading to severe toxicity. This study aims to determine metal concentrations in sediments of Anzali International Wetland in Iran. Chemical partitioning method is used to determine the portion of anthropogenic pollution and the mobility potential of each metal. The intensity of metal pollution in sediments of the wetland is assessed using three reliable indices. The results of chemical partitioning reveal that cadmium bear the highest risk of being released into the aquatic environment and high amount of manganese in sulfide bond phase implies the initiation of redox state in aquatic environment of the Anzali Wetland. The results of chemical partitioning studies show that Pb, Cd, Mn and As have the highest anthropogenic portion. Cluster analysis also confirms the results of chemical partitioning and indicates that the mentioned metals can be originated from anthropogenic sources. Sediment pollution indices, including, Igeo, IPOLL, and m-ERM-Q reveal that metals are in the range of low to moderate pollution and also show that the highest metal pollution is in the eastern and central parts of the wetland. This can be ascribed to rivers which are the recipient of industrial, agricultural and municipal wastewaters and flow into these parts of the wetland.

Bainite Formation at Low Temperatures in High C-Si Steel and its Mechanical Behavior

A significant amout of stabilized austenite can be obtained in high carbon steel containing high amounts of manganese and silicon (1.5-2 %). At relatively low temperatures the bainite plates formed are extremely thin, making the material very strong. In this study, the influence of the thermal cycle of austempering on the mechanical behavior of a spring steel 0.56C-1.43Si-0.58Mn-0.47Cr (wt. %), with TRIP effect was investigated. The thermal cycle consisted of heating three groups of hot-rolled wire steel at austenite field of 900°C for 300 s, and quickly transferring those to a metallic bath maintained at 200, 220 or 270°C, respectively, for different heat treatment times. The samples were then tested in tension and their microstructures were examined by scanning and transmission electron microscopy. The samples treated at 220°C showed higher elongation, yield strength and tensile strength than those maintained at 200 or 270°C. The high level of strength and ductility is due to a mixture of martensite and very fine bainitic ferrite with interlath film of retained austenite. The temperature has shown a strong influence on bainite formation kinetics. The fracture behavior of the steel was also evaluated using SEM fractography.

Bainite Formation at Low Temperatures in High C-Si Steel and its Mechanical Behavior

Abstract A significant amount of stabilized austenite can be obtained in high carbon steel containing high amounts of manganese and silicon (1.5–2%). At relatively low temperatures the bainite plates formed are extremely thin; as a result the material becomes very strong. In this study, the influence of austempering on the mechanical behavior of a spring steel 0.56C-1.43Si-0.58Mn-0.47Cr (wt.%), with TRIP effect, was investigated. The thermal cycle consisted of heating two groups of hot-rolled steel at the austenite field of 900°C for 300 s, and transferring it to a metallic bath maintained at 220 or 270°C, respectively, for different isothermal treatment times. The samples were then tested in tension, and their microstructures were examined by optical and scanning electron microscopy. According to the results, the samples treated at 220°C showed higher elongation, yield point, and tensile strength than those maintained at 270°C. The high level of strength and ductility is due to a mixture of martensite and very fine bainite formation.

Alloy compositions and mechanical properties of 9–12% chromium steels with martensitic–austenitic microstructure

Nitrogen alloyed 9–12% chromium steels with high amounts of manganese and nickel have been investigated. The steels are of a lamellar duplex microstructure, consisting of tempered martensite and about 30 vol.% austenite. The martensite is precipitation hardened with fine and homogeneously distributed vanadium nitrides. A good combination of strength and toughness has been achieved, with a room temperature yield strength level of up to 1000 MPa. As will be shown even at temperatures up to 550°C the new steels exhibit outstanding strength and ductility properties. Two different steels have been investigated. One steel was solely nitrogen alloyed, while in the other one parts of the nitrogen have been replaced by carbon. The steel which was alloyed with nitrogen only showed marked embrittlement after long-term ageing. Small carbon additions prevented ageing embrittlement. This is explained by the different precipitation behaviours.

Properties of blast-furnace slags containing high amounts of manganese

This paper presents results of tests performed to characterize the physical and chemical properties of five blast-furnace slags having MnO content up to 21%. The interactions between ordinary Portland cement or calcium oxide and each slag were investigated by X-ray diffraction, scanning electron microscopy, and thermoanalysis. Mortars and concretes using these slags were cast. When ground to a Blaine surface area of 300 m 2/kg, the slags were utilized in road binders in combination with calcium oxide or Portland cement. When ground to a Blaine surface area of 600 m 2/kg, the slags were introduced into the composition of different concretes instead of fly ash or silica fume. Based on the resulting high strengths, fine grinding of manganese-rich slag for use in concrete appears to be a good way of beneficiation.

Electrochemical Properties of Over‐stoichiometric ZrMn1 − x V xNi1.4 + y Alloys with C15 Laves Phase

The hydrogen storage performance and electrochemical properties of (x = 0.5, 0.7; y = 0.0, 0.2, 0.4, and 0.6) alloys, one type with a high amount of manganese, i.e., x = 0.5, and the other with a small amount of manganese, i.e., x = 0.7, were investigated. The relationship between discharge performance and alloy characteristics such as crystallographic parameters, surface morphology, reaction surface area, and exchange current density is also discussed. All of these alloys were found to have mainly a C15‐type Laves phase structure by x‐ray diffraction analysis. The equilibrium hydrogen pressure of the alloy increased as the amount of Ni increased in both types of alloys. In the case of (y = 0.0, 0.2, 0.4, and 0.6) alloys, the discharge efficiency and the rate capability decreased as the amount of Ni increased, while these values increased for the (y = 0.0, 0.2, 0.4, and 0.6) alloys. After measuring the specific reaction surface area and exchange current density to identify the reason why the electrode properties had a reverse tendency between the two systems, we confirmed that for the (y = 0.0, 0.2, 0.4, and 0.6) alloys the major factor controlling the electrode properties was the specific reaction surface area, not the exchange current density, while, in the case of (y = 0.0, 0.2, 0.4, and 0.6) alloys, mainly the exchange current density, not the specific reaction surface area, controlled the electrode properties.

Effects of organic amendments on manganese toxicity in potatoes as measured by sand and soil culture studies

Soil and sand culture studies were carried out in the greenhouse to investigate the influence of organic amendments on the rate of mineralization of manganese and iron in different soil types of Quebec. Potatoes (Early Rose variety which is resistant to manganese toxicity) grown in culture solution containing 100 ppm of manganese produced flowers two weeks in advance of those grown in 0.5 ppm. The yields of tubers were increased two-fold by the combined treatment of humic compounds and high concentration of manganese. Due to microbial competition, the introduction of carbohydrates, alcohols, etc, decreased the yields of tubers. The yields recorded with the Keswick variety (susceptible to manganese toxicity) and different organic amendments on St. Andre soil (low pH and organic matter and high manganese) were in the following order: humate > compost > compost and peat > peat > control. A somewhat different order was recorded on De l'Anse (low pH and manganese and high organic matter): compost > humate > peat > compost and peat > control. The presence of sodium humate in the nutrient solution reduced the manganese content of potato leaves but increased that of stems. The addition of carbohydrates slightly depressed the content of manganese in potato leaves. Glycerine favored the accumulation of high amounts of manganese in potato stems. The Ca/Mn ratio should be around 360 in the leaves and 400 in the stems of normal plants. Plants showed manganese toxicity symptoms when the Ca/Mn ratio fell below 70, or when the Mn/Fe ratio was about 0.2 in the leaves and 0.6 in the stems of normal plants. The sum of Mn/Fe and Ca/Mn ratios remained the same in potato stems regardless of the organic amendments and the soil types. As the Mn/Fe ratio increased, the manganese toxicity symptoms became more severe and the Ca/Mn ratio narrower. The addition of organic amendments generally decreased the Mn/Fe ratio as well as toxicity symptoms. Various regression equations are formulated to establish the correlations between plant and soil data. The most interesting findings are as follows: 1 Organic matter, total nitrogen and C/N ratio in the soil were found to be negatively correlated with exchangeable manganese. 2 A positive correlation was found between the Mn/Fe ratio of soil and that of plants, and also between the manganese content of potatoes and the manganese toxicity indexes. 3 Manganese toxicity indexes were positively correlated with Mn/Fe ratios and negatively with the Ca/Mn ratios in plants. 4 There was a definite tendency for the yields of the Keswick variety (susceptible to manganese toxicity) to decrease as the manganese content of the soil increased. However, the yields of Early Rose variety (tolerant to manganese toxicity) were higher with 100 ppm of manganese than with 0.5 ppm in the culture solutions. Therefore, Early Rose appears to be a good variety for acid soils containing high levels of exchangeable manganese.