Figure 5.

(a) Line tension, λ, and (b) the square of the dipole density difference, (Δμ)² = (Δm)²/4πεε₀ plotted as a function of surface pressure for Survanta lipids (solid squares) and Survanta lipids with 5 wt % SP-B protein (open diamonds). Both λ and (Δμ)² are roughly independent of surface pressure for the Survanta lipids alone. SP-B increases both λ and (Δμ)² compared to the lipids alone, but the difference decreases with surface pressure, consistent with SP-B being gradually removed with increasing surface pressure.