(A) Surface density, Γ, versus surface pressure, Π, for several deposited amounts of Survanta, (B) surface density, Γ, compressed (▲) and expanded (Δ) and surface pressure, Π, compressed () and expanded () of 0.8 mg of Survanta in buffer (NaCl 150mM, NaHCO3 0.2mM and pH=7.0) at room temperature (22°C) on a Langmuir trough and (C) surface density, Γ, versus surface pressure, Π, for compressed films of 0.8 mg Survanta (▲) and DPPC (□). Dashed lines in (A) and (C) show the Langmuir equation of state for an excluded molecular area ωS = 45 Å2 and ωS = 40 Å2, respectively. The Π plateau in (C) at Π ~ 40 mN/m is indicative of the collapse of unsaturated lipids from the air-water interface and the plateau at Π ~ 65 mN/m is the collapse of the entire film.