“…This instrument tests the dynamic surface properties of surfactants at a spherical interface and can be pulsated at high speeds. This would be relevant to the lung surfactant system as pulsation at a high speed of 40 cpm would correspond to the respiratory rate of neonates (Schubring et al, 1976;Yu and Possmayer, 1993) and also to the frequency of ventilator settings used for neonates (Koyabashi et al, 1990). The minimum surface tension, static surface tension at a bubble of maximum sizeas a measure of the adsorption to an air-liquid interface, and stability index of liposomal suspensions of the main phospholipids of pulmonary surfactant and their binary mixed films, in the ratio of 2 parts of PC with 3 parts of PE or PG, forming the mixtures PCPE and PCPG, respectively, are studied both in the absence and in the presence of eucalyptus.…”