1. Department of Physical Chemistry, Faculty of Science, P.J. Šafárik University, Moyzesova 11, SK-04154 Košice, Slovakia
2. Institute of Materials Research, Slovak Academy of Science, Watsonova 47, SK-04353 Košice, Slovakia
3. Institute of Geotechnics, Slovak Academy of Science, Watsonova 47, SK-04353 Košice, Slovakia