1. MATHEMATICAL MODELING FOR THE CRYSTALLIZATION PROCESS OF HYDROXYAPATITE OBTAINED BY PRECIPITATION IN AQUEOUS SOLUTION. Authors: VALENTINA R. DEJEU, BARABÁS RÉKA, POP ALEXANDRU, BOGYA ERZSÉBET SÁRA, PAUL ŞERBAN AGACHI.2. GROWTH RATE OF HYDROXYAPATITE CRYSTALS OBTAINED BY PRECIPITATION. Authors: PAUL ŞERBAN AGACHI, BOGYA ERZSÉBET SÁRA, ANA-MARIA CORMOŞ, REKA BARABAS, VALENTINA ROXANA DEJEU.3. KINETIC STUDIES OF SORPTION OF COPPER(II) IONS ONTO DIFFERENT CALCIUM-HYDROXYAPATIE MATERIALS. Authors: VALENTINA ROXANA DEJEU, GRAZIELLA L. TURDEAN, ALEXANDRA CSAVDÁRI, BARABÁS RÉKA, IOAN BÂLDEA, BOGYA ERZSÉBET SÁRA.