1. National Institute of Materials Physics, Atomistilor Street, No. 405A, 077125 Magurele, Romania
2. National Centre for Micro and Nanomaterials, University Politehnica of Bucharest, 060042 Bucharest, Romania
3. Department of Physics, Norwegian University of Science and Technology (NTNU), Realfagbygget E3-124 Høgskoleringen 5, NO 7491 Trondheim, Norway
4. Faculty of Electronics and Computer Science, Koszalin University of Technology, Śniadeckich 2, PL 75-453 Koszalin, Poland
5. Faculty of Horticulture, University of Agronomic Sciences and Veterinary Medicine, 59 Marasti Boulevard, 011464 Bucharest, Romania
6. Faculty of Land Reclamation and Environmental Engineering, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 59 Marasti Boulevard, 011464 Bucharest, Romania