Fig. 1. Physical property diagrams of the three different preparations. (A) The graph shows the surface spreading rate. The equilibrium surface tension measurements obtained within 10 seconds were similar to those of Surfacten® and the synthetic surfactant protein C pulmonary surfactant (sSP-C PS); however, a lower value was obtained with purified natural bovine surfactant (PNBS). (B) The graph shows the surface adsorption rate curve. Both Surfacten® and PNBS reached rapid adsorption equilibrium surface tension within one minute, while sSP-C PS required more than one minute to reach equilibrium. (C) The graph shows the surface tension-area diagram. All three surfactant preparations exhibited reproducible hysteresis curves.