[1] Univ Politehn Bucuresti, Fac Engn Foreign Languages, 313 Splaiul Independentei, Bucharest 060042, Romania
[2] Univ Politehn Bucuresti, Fac Appl Chem & Mat Sci, Dept Sci & Engn Oxide Mat & Nanomat, 1-7 Gheorghe Polizu St, Bucharest 011061, Romania
[3] Natl Inst Lasers Plasma & Radiat Phys, Lasers Dept, 409 Atomistilor St, Magurele 077125, Romania
[4] Univ Med & Pharm Craiova, Res Ctr Microscop Morphol & Immunol, 2 Petru Rares St, Craiova 200349, Romania