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Organotinsulfides Sn 4 S 4 R 6 (R = methyl, n-butyl and phenyl) were employed as single-source precursors for nanometric tin sulfides. The residues obtained after pyrolysis in hydrogen, nitrogen and oxygen were characterized by X-ray diffraction, 119 Sn Mössbauer spectroscopy, scanning electron microscopy and X-ray electron probe microanalysis. The results clearly showed the formation of tetragonal SnO 2 (rutile-type structure) in oxygen and pure phase orthorhombic γ -Sn 2 S 3 in nitrogen when Sn 4 Bu 4 S 6 (2) was employed as precursor. The 119 Sn Mössbauer spectroscopic results were very important in the elucidation of the decomposition process. Compound 2 is the best starting material for the process.

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Selenized Saccharomyces cerevisiae cells are used as a nutritional supplement for humans and animals since they contain large amounts of selenomethionine. Although it has been discussed less frequently, they also have a considerable quantity of selenium nanoparticles (Se-NP). Se-NP were generated inside cells after 48 h of incubation with sodium selenite; these nanoparticles were shown to have a spherical morphology, with an estimated size of 20-30 nm, and were mainly made up of Se. The type of Se-NP produced inside the cells depends on the new protein synthesis. They are amorphous, and are generated regardless of the presence of light or oxygen. After its intracellular generation, Se-NP move to the extracellular compartment, without compromising membrane integrity in aerobic conditions. The release of Se-NP from cells was time dependent.