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. 2005 Apr 15;89(1):266–273. doi: 10.1529/biophysj.104.052092

FIGURE 1.

FIGURE 1

Surface shear viscosity, ηs, as a function of surface pressure, π, for Langmuir monolayers of POPG, PA, DPPC, DPPC/POPG 4:1, DPPC/POPG/PA 68:22:8 (wt/wt) at 25°C. The POPG monolayer remains in the fluid state at all π, thus ηs remains low. The PA monolayer undergoes a transition from a tilted to a nontilted phase at 22 mN/m, which triggers a dramatic increase of ηs. DPPC surface viscosity in the LE phase (below ∼15 mN/m) is similar to POPG. In the LC phase, ηs increases exponentially. Both DPPC/POPG (bottom inset image) and DPPC/POPG/PA (top inset image) films show coexistence between solid phase islands (black in inset images) and a continuous fluid phase (bright in inset images) for surface pressures >10 mN/m. Both images shown are taken at 30 mN/m; PA increases the fraction of solid phase at a given π, which also increases ηs.