1. Department of Mathematics, National Institute of Technology Manipur, Langol, Imphal 795004, Manipur, India
2. Chemistry Doctoral School, Babeş-Bolyai University, 400084 Cluj, Romania
3. Department of Physics and Chemistry, Technical University of Cluj-Napoca, B.-dul Muncii nr. 103-105, 400641 Cluj-Napoca, Romania
4. Department of Chemistry and Biology, North University Center at Baia Mare, Technical University of Cluj-Napoca, 430122 Baia Mare, Romania