Papers by Keyword: Manganese

Abstract: Nine new quaternary R₃MnAl₃Ge₂ alumogermanides (R = Sm, Gd-Lu) were synthesized by arc melting and their crystal structures were studied by X-ray powder diffraction. All of the compounds crystallize in hexagonal Y₃NiAl₃Ge₂-type structures: Pearson symbol hP9, space group P-62m. The unit-cell parameters of the isotypic compounds decrease with decreasing radius of the rare-earth metal. The hexagonal structure type Y₃NiAl₃Ge₂ (Z = 1) is a quaternary ordering variant of the binary type Fe₂P (Z = 3) and the ternary types β₁-K₂UF₆, Lu₃CoGa₅, Zr₃Cu₄Si₂ (Z = 1), ZrNiAl (Z = 3). It belongs to the family of structures with trigonal prismatic coordination of the small atoms.

Abstract: The importance of the research is due to the lack of potable water (~1.6 million m³ per year) in a rapidly developing city in the Urals. One way to solve this problem is to purify water from the spent copper mine with a debit of ~4.4 million m³ of water per year. The most advanced techniques recently used for obtaining drinking water of a high quality are based on ion exchange and reverse osmosis, which can ensure an obtainment of water with initial contents of impurities much below the maximum permissible values. Based on the real experience the article compares sorption and membrane technologies in terms of water purification efficiency and cost of potable water production. The large-scale tests of mine water purification were carried out at sorption and reverse osmosis pilot plants with the capacity of 1 m³ per hour for the incoming flow. The source water had the following composition, mg/dm³: 0.5–0.9 Mn; 1.0–1.7 Ni; 80-140 Ca; 30-40 Na; 40-70 Mg; 0.2–0.6 Cu; 8.1–9.5 Si; 0.01–0.03 Zn; 0.01–1.70 Fe; <0.01 Al; < 0.005 As; < 0.005 Pb. At the same time the salinity was 640–680 mg/dm³, the water hardness was 9.5–11.5 mmol/dm³ and pH was 7.0-7.5. The content of non-mentioned impurities was below the detection limit. The resulting treated water met the requirements for the quality of potable water for both purification techniques. It was concluded, that the best option for treatment of mine water is ion exchange.

Abstract: In this article the time and heat dependence of the nitrogen distribution upon steel alloying of 04Cr20Ni6Mn11Mo2NVNb steel grade by the nitrided manganese of Mn85N10 grade at the holding in the air atmosphere from 2 to 30 minutes in the temperature range 1450-1550 °С was experimentally determined. It was determined that the highest degree of nitrogen transition into steel is 99% and is observed with a short holding time of 2 min (after the introduction of nitrided manganese into the steel melt) in the low-temperature region ~ 1450 °С. Further holding and / or temperature growth results in the release of nitrogen in the gaseous form, due to the thermal dissociation of the nitrogen-containing compounds contained in the melt and removal of nitrogen from the melt into the gas phase, which leads to a decrease in the degree of nitrogen transition to the steel. The key possibility for obtaining a steel of the indicated grades group with a nitrogen content of 0.45-0.6% is shown when alloying in an air atmosphere in a low-temperature region (1450-1500°C), while optimizing the holding time.

Abstract: The paper presents the results of modelling of phosphorus interaction with substitutional (Cr, Mn, P) and interstitial (C) impurity atoms in bcc iron in the framework of density functional theory using WIEN2k software. It is found that a repulsion exists of a phosphorus atom in the three first spheres of coordination of carbon, chromium and phosphorus atoms, while for manganese such repulsion of phosphorus takes place only in the second sphere. This repulsion is a consequence of an abrupt change of magnetic moment of manganese atom, so the solution energy of phosphorus almost does not change. On the contrary, chromium decreases phosphorus solubility in iron, in agreement with other data.

Abstract: Polypyrrole (PPy) and manganese (Mn) due their remarkable properties offers a good performance for electrochemical capacitors. Manganese modified polypyrole (Mn-modified PPy) thin films were chronoamperometically (CA) deposited on the platinum-titanium crystal resonator as a part of the electrochemical quartz crystal microbalance (EQCM). The performances of the thin films were then examined for performance using cyclic voltammetry (CV). The effects of pyrrole monomer and manganese oxides concentrations were also investigated in this study.

Abstract: In this study, the modification effects and mechanism of manganese (Mn) and ultrasonic vibration (USV) on the needle-like Fe-containing intermetallic compounds of Al-20Si-xFe-2.0Cu-0.4Mg-1.0Ni (x=1, 2 wt.%) alloy have been studied respectively. The effect of Fe-containing phases on volume fraction of hard phases is also investigated. The results show that the mechanism and effect of Fe-containing intermetallic compounds improved by Mn are in close relationship with Fe content. Mn can promote to form less harmful α-Al₁₅(Fe,Mn)₃Si₂ phase, or replace some Fe atoms of β-Al₅FeSi and δ-Al₄FeSi₂ according to different Fe content. When USV was applied to this alloy containing 2%Fe near liquidus temperature, most of the acicular β phases formed in traditional process are substituted by fine plate δ phases. With the combined effects of 0.5%Mn and USV, the acicular β phases are almost repressed and the Fe-containing phases exist in form of fine Al₄(Fe,Mn)Si₂ and Al₅(Fe,Mn)Si particles about 20~30μm. Consequently, the total volume fraction of hard phases which are composed of primary silicon particles and Fe-containing phases increases significantly.

Abstract: Titanium (Ti) exhibits many attractive properties that enable practical applications. It is also considered to be a ubiquitous element, since it has the ninth highest Clarke number among all the elements. However, the principal beta-stabilizing elements for Ti, molybdenum and vanadium, can be very expensive, and so many Ti alloys are also costly. For this reason, less expensive alloying elements would be preferable. Iron (Fe) and manganese (Mn) are beta stabilizers for Ti alloys that are readily available, since they have the fourth and eleventh highest Clarke numbers, respectively. Furthermore, since Fe has a large diffusion coefficient in the beta phase of Ti, precipitation of the omega phase occurs more quickly when Fe is added. The behaviors of Ti-Mn and Mn-Fe alloys during heat treatment have been investigated and it has been found that, in some alloys, the isothermal omega phase is precipitated. Because this phase can lead to brittleness of the alloy, it is very important to suppress its precipitation. Since it is well known that aluminum (Al) suppresses isothermal omega precipitation, the present work investigated the effects of Al content on the phase constitution and heat treatment behavior of Ti-8.5 mass%Mn-1 mass%Fe-0, 1.5, 3.0 and 4.5 mass%Al alloys using electrical resistivity, Vickers hardness, and X-ray diffraction measurements. In the case of each of these alloys, whether solution-treated or water-quenched, only the beta phase was identified. The resistivities at room and liquid nitrogen temperatures were found to increase monotonically with Al content, while the Vickers hardness decreased up to 3 mass% Al and then remained constant. The addition of Al was found to suppress omega precipitation.

Abstract: Bio-templates such as proteins, lipids offer rich structural and functional diversity for the synthesis of nanoparticles by controlling their shape, size and orientation. In this work we have exploited a pH dependent folding-refolding feature of Horse Spleen Apoferritin (HsAFr) to synthesize copper and manganese oxide nanoparticles in a controlled manner. Two methods of preparation were used in this study. In the first method, Copper Sulphate (100 mM) and Manganese Chloride (4.8 mM) have been incubated with the protein and the pH dynamically adjusted for homogeneous incorporation of the metal ions into the HsAFr shell. The second study involved the incorporation of Cu²⁺ and Mn²⁺ inside HsAFr cavity and subsequent designing of nanoclusters of the respective oxides. UV, fluorescence and far-UV circular dichroism (far-UV CD) spectroscopic techniques have been used to study the mineralization effect of the metal inside the HsAFr cavity. Size determination carried out using XRD suggested an average size ranging from 20-30 nm. The EPR of the nanoclusters show that incorporation of Mn²⁺ leads to a characteristic magnetoferritin behavior.

Abstract: Combination between oxidation and filtration can be used for removing iron and manganese from groundwater especially when the concentrations of these metals were high. This study focused on the effectiveness of the cascade aerator and the size of the limestone filter media to remove iron and manganese from groundwater. Water samples used for this study were collected from orphanage home, Rumah Nur Kasih, Taiping. Universiti Sains Malaysia (USM) has provided a tube well of 15 m depth and 150 mm diameter for the orphanage home. However, the water cannot be used for domestic consumption due to high amount of iron and manganese at 6.48 and 1.9 mg/L which exceeded the drinking water standard of 0.3 and 0.1 mg/L respectively. Using laboratory physical model, the study has shown that the removals of iron and manganese have reduce the concentration until 0.17 and 0.2 mg/L respectively. Thus, the results from this study which utilize cascade aerator and limestone roughing filter could be implemented on site for the community to use the ground water for domestic purposes.

Abstract: This paper reports about the method of modified nanomaterials. The aluminum oxyhydroxide was modified by manganese ions (II) during the synthesis. It was shown that modified aluminum oxyhydroxide has new function properties such as catalytic properties. It was shown that the modified aluminum oxyhydroxide with the high concentration of manganese ions (II) could be used in the reaction of the oxidation of methane.