${\mathrm{Pr}}^{3+}$ -doped $\mathrm{PbO}\text{–}{\mathrm{GeO}}_2$ (PGO) glasses containing silver nanoparticles (NPs) were prepared and their spectroscopic characteristics were studied. The PGO samples and the nucleation of silver NP were obtained melting the starting oxide powders, quenching and annealing. Transmission electron microscopy was used to characterize the NP size distribution. Isolated silver particles with average diameter of 2 nm and aggregates with dimensions smaller than 100 nm were observed. Optical absorption and luminescence experiments were performed to investigate the properties of the composite system. Enhancement of the ${\mathrm{Pr}}^{3+}$ ions’ luminescence was observed due to the presence of the silver NP.

$\mathrm{Te}{\mathrm{O}}_2–\mathrm{Pb}\mathrm{O}–\mathrm{Ge}{\mathrm{O}}_2$ glass samples containing silver nanoparticles (NPs) and complex nanostructures were prepared and characterized. Nucleation of NPs and formation of NP structures were obtained following the procedure of powder fusion and thermal annealing at $350°\mathrm{C}$ . Electron microscopy revealed the diffusion paths of the silver NP during the heat-treatment process. Optical experiments were performed to investigate properties of the composite system. Large enhancement of the luminescence from $\approx 430\text{to}\approx 750\mathrm{nm}$ , associated to aggregates of ${\mathrm{Pb}}^{2+}$ ions, was observed due to the presence of the silver NPs and their nanostructures.

Microbiological processes were used for chitin and chitosan production by Mucor circinelloides (UCP 050) grown in yam bean (Pachyrhizus erosus L. Urban) medium. The polysaccharides were extracted by alkali–acid treatment and structural investigations by X-ray diffraction, Fourier transform IR analysis, viscosity and thermal analysis by TG, DTG, and DTA were done. The highest biomass yield (20.7 g/L) was obtained at 96 hours. The highest levels of chitosan (64 mg/g) and chitin (500 mg/g) were produced at 48 and 72 hours, respectively. It was demonstrated that yam bean shows great potential as an economic medium and it is possible to achieve a good yield of chitosan with chemical properties that enable its use in biotechnological applications.