Nanostructured YAG:Ce3+ and Y2O3:Eu3+ were synthesized by low temperature (320°C) aerosol synthesis-LTAS and high temperature (900°C) aerosol synthesis-HTAS, respectively. The synthesis included aerosol generation from a nitrate precursor solution by an ultrasonic atomizer (1.3 MHz). The obtained aerosol was introduced into a tubular flow reactor, using air as the carrier gas, where successively, on a droplet level, evaporation/drying, precipitation and thermolysis occurred. The obtained powders were collected and thermally treated at different temperatures (900-1200°C). The phase development and the morphology were investigated by the X-ray powder diffraction method (XRPD) and scanning electron microscopy combined with energy dispersive spectrometry (SEM/EDS). Structural refinement was performed using the Rietveld method with the Fullprof and Koalariet programs. The average crystallite size for the Y2O3:Eu system was calculated using the Profit program. It was shown that 89 wt.% of Y3Ai5Oi2:Ce was obtained by annealing (1000°C/6 h) the as prepared, amorphous powder, synthesized by the low temperature aerosol method (LTAS). High temperature spray pyrolysis (HTAS) at 900°C led to the formation of the targeted cubic phase of Y2O3:Eu3+. The microstructural parameters of the asprepared samples of the Y2O3:Eu3+ system indicate the formation of nanostructures with crystallite size smallest than 20 nm. The substitution of luminescent centers (Ce3+, Eu3+) into a host lattice (YAG, Y2O3, respectively) was confirmed by changes in the crystal lattice parameters. Also, it was shown in both systems that good morphological characteristics (non-a­gglomerated, spherical, submicron particles) were obtained enabling improved luminescent characteristics.

Studies of protolytic equilibria and investigations of stability of flavonoids at different acidities are necessary to better understand their antioxidant efficiencies and autoxidation characteristics. The protonation constant of carbonyl group and dissociation constants of OH groups of quercetin in aqueous solutions were determined spectrophotometrically. The distribution diagram of ionic species in aqueous solutions of various acidities was calculated. Study of the effects of UV irradiation on quercetin at pH 5.00, 7.50 and 10.00 indicated that UV irradiation accelerated quercetin autoxidation via the formation of the oxidation product. The stability of quercetin and oxidation product was investigated as a function of irradiation time by using spectrophotometric and HPLC techniques. The apparent pseudofirst-order rate constants for quercetin degradation and oxidation product formation were calculated and discussed.

Tiling modification in fullerene modeling can be achieved by some map operations. In this respect, sequences of classical operations, or single generalized operations, were used to obtain corannulene-like azulenic patterns. The aromaticity of such cages tessellated by "corazulenic" supra-faces is discussed in terms of several criteria. Particularly, the number of Kekulé valence structures, was considered as a rough measure of the fullerene aromaticity and implicitely of their stability. The covering was given as a pi-electron partition within some Kekulé valence structures. The well-known geometric index of aromaticity HOMA (harmonic oscillator model of aromaticity) enabled the evaluation of local aromaticity of the discussed supra-faces and brought evidence for several dominant Kekulé valence structures.