The hot and degassed solutions prepared as described in Section 2.2.1 were cooled down to 55 ◦C, to be spread over glass plates, using an automatic knife film applicator (Sheen model 1132N, UK),at constant speed(0.3m/s).The plates with dimensions 400mm×270mm were pre-heated at 55 ◦C to avoid agar gelation when spreading the film-forming solutions.