1. Department of Chemical Engineering, Faculty of Engineering, Sebelas Maret University, Jl. Ir. Sutami 36 A, Surakarta, Central Java, 57126 Indonesia
2. Department of Physics, Faculty of Mathematic and Natural Science, Diponegoro University, Jl. Prof. H. Soedarto SH, Semarang, Central Java, 50275 Indonesia
3. Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739-8527, Japan