[1] Univ Fed Parana, Dept Fis, BR-81531990 Curitiba, Parana, Brazil
[2] Univ Johannesburg, Dept Appl Chem, ZA-2028 Doornfontein, South Africa
[3] Univ Witwatersrand, Inst Mol Sci, Sch Chem, DST NRF Ctr Excellence Strong Mat, ZA-2050 Johannesburg, South Africa