1,2-DipalmitoylphosphatidylcholinePulmonary SurfactantsPhosphatidylcholinesLiposomesPhospholipidsLipid BilayersCalorimetry, Differential ScanningMolecular ConformationGlycerylphosphorylcholinePhosphatidylglycerolsPalmitic AcidsMembranes, ArtificialPhosphatidylethanolaminesSurface TensionGelsTemperaturePhase TransitionSurface PropertiesDimyristoylphosphatidylcholineX-Ray DiffractionWaterAirMembrane LipidsThermodynamicsAdsorptionCholesterolFluorescence PolarizationProteolipidsMembrane FluidityBiophysicsSurface-Active AgentsSpin LabelsBiophysical PhenomenaPressurePulmonary AlveoliCrystallizationSpectrometry, FluorescenceKineticsLungPolyethylene GlycolsElectron Spin Resonance SpectroscopyMathematicsStructure-Activity RelationshipMolecular StructureLipidsFatty AcidsCattleMagnetic Resonance SpectroscopyMicroscopy, Electron