**Funding statement**

This work was published under the frame of a national grant financed by Romanian National Authority for Scientific Research (UEFISCDI) project number PN-III-P2-2.1-PED-2016-1002, 186PED, 01/09/2017. The work of Dumitriţa Ruginǎ is sustained by the National Fellowship Program L'Oréal-UNESCO-For Women in Science.
