“…As in [8], observe that in problem (1.1) the singular source term may become singular if u(x, t) → 1 − as (x, t) → (x * , T ), where x * is a quenching point in [0, 1] and T is a quenching time in (0, ∞). On the other hand, the outflux −u −β (1, t) may also become singular in some finite time (see [2], [3] and [9]). Here, we discuss the second situation.…”