For the Nyquist plots of Fig. 6 the authors should be observe the correct representation of Nyquist. A correct way to represent the Nyquist plot is for example: x-axis of 10 cm (Z’ 0 - 100 (ohm)) and y-axis 10 cm (Z’’ 0 - 100 (ohm)) or x-axis 5 cm (Z’ 0 - 50 (ohm)) and y-axis 10 cm (Z’’ 0 - 100 (ohm)).