Phase transition study of some selected azine compounds
Abstract The dielectric constants (real and imaginary) of benzaldazine and its hydroxy derivatives have been measured at different frequencies up to 100 kHz. The measurements were also carried out at different temperatures up to near the melting point of each sample. Two phase transitions were obtained during measurements at 320 and 370 K. The rotation of the benzene ring around the -CN- axis was responsible for these transitions. The effect of variation of the OH substituent between o-, p- and w-positions on the dielectric loss was discussed. The a.c. conductivities for the different samples were measured and explained.
Alkaliphilic bacterial strains producing the enzyme cyclodextrin glucanotransferase were cultivated on solid agar medium containing an indicator system detecting the enzyme. The growth of the colony and the surrounding diffusion zone, due to the enzyme, were measured by the image analysis during the cultivation. It was possible to differentiate between relatively similar clones by observing quantitatively the changes at and around the colony. Optimal experimental conditions for such measurements are discussed. The image analysis technique provides a potential tool for characterizing microbes grown on solid media.