Arsenite (As(III)) oxidation by manganese oxides (Mn-oxides) serves to detoxify and, under many conditions, immobilize arsenic (As) by forming arsenate (As(V)). As(III) oxidation by Mn(IV)-oxides can be quite complex, involving many simultaneous forward reactions and subsequent back reactions. During As(III) oxidation by Mn-oxides, a reduction in oxidation rate is often observed, which is attri...

Zinc sorption to hydrous manganese oxide (HMO)-coated clay was investigated macroscopically, kinetically, and spectroscopically. Adsorption edges and isotherms revealed that the affinity and capacity of the HMO-coated montmorillonite was greater than that of montmorillonite, and when normalized to the oxide present, the coatings behaved similarly to the discrete Mn oxide. Over two pH conditions...

A nanocomposite comprising cerium oxide nanoparticles (CeO2 NPs) and polypyrrole (PPy) was fabricated onto a microelectrode for cholesterol sensing application. The oxidase (ChOx) immobilized on the CeO2 NPs/PPy/electrode by physical adsorption route. structure morphology of NPs/PPy were characterized X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy...

Hexagonal turbostratic birnessite, with the characteristics of high contents of vacancies, varying amounts of structural and adsorbed Mn3+, and small particle size, undergoes strong adsorption reactions with trace metal (TM) contaminants. While the interactions of TM, i.e., Zn2+, with birnessite are well understood, the effect of birnessite structural characteristics on the coordination and sta...

The preparation and characterisation of synthetic enzyme complexes simulating those usually encountered in soil were investigated. Complexes were prepared at 308C by the interaction of acid phosphatase and tannic acid in the presence and absence of Fe and Mn ions (as chlorides) and oxides, with and without montmorillonite. In comparison with phosphatase–tannic acid complexes, the enzymatic comp...

Open cell foams consisting of Fe and Fe-Mn oxides are prepared from metallic Fe and Mn powder precursors by the replication method using porous polyurethane (PU) templates. First, reticulated PU templates are coated by slurry impregnation. The templates are then thermally removed at 260 °C and the debinded powders are sintered at 1000 °C under N₂ atmosphere. The morphology, structure, and magne...

Electric-field control of ferromagnetism in magnetic semiconductors at room temperature has been actively pursued as one of the important approaches to realize practical spintronics and non-volatile logic devices. While Mn-doped III-V semiconductors were considered as potential candidates for achieving this controllability, the search for an ideal material with high Curie temperature (T(c)>300 ...

Action of Manganese on Puberty. (May 2007) Bo Yeon Lee, B.S., Chonnam National University Chair of Advisory Committee: Dr. W. Les Dees Manganese (Mn) is considered important for normal growth and reproduction. Because Mn can cross the blood brain barrier and accumulate in the hypothalamus, and because it has been suggested that infants and children are potentially more sensitive to Mn than adul...

Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic an...