1. Department of Chemical Engineering, National Taiwan University, No. 1 Sec. 4 Roosevelt Rd., Taipei 106, Taiwan
2. Nanotechnology Center of Excellence, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia
3. Department of Industrial Chemistry, College of Applied Sciences, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia