“…During the progress of the experiments, the current displayed the same tendency in both Test 1 and Test 2; that is, to increase up to a maximum value, and then decrease until reaching a steady state. This was similar to the findings reported in some previous studies (Reddy et al, 2006;Al-Hamdan and Reddy, 2008;Tsai et al, 2010;Lu et al, 2012). In Test 1, the electric current increased during the first 72 hr after the voltage had been applied, decreased between 72 and 96 hr, and then plateaued after 96 hr (3.4-8.9 mA).…”