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Interactions of insoluble micro- and nanoparticles with the air-liquid interface of the model pulmonary fluids

Dobrowolska K., Jabłczyńska K., Kondej D., Sosnowski T. R.

Physicochemical Problems of Mineral Processing

2018

Vol. 54, iss. 1

151--162

The work discusses physicochemical phenomena related to interactions between the inhaled particles and the surface of pulmonary fluid which contains the lung surfactant. Dynamic surface phenomena which arise due to periodical variations of the interfacial area during breathing cycle are the extraordinary feature of this system and they are strictly related to the mechanics of ventilation and the pulmonary mass transfer processes. Presence of foreign material such as inhaled micro- and nanoparticles with different size, surface properties and morphology may alter these phenomena which may have some health consequences. This effect is discussed on two examples: mineral particles (CeO2) and carbonaceous particles emitted from diesel engine running on two different fuels. Two experimental methods of research in this field are presented: the Langmuir balance and the oscillating pendant drop. The results show the sensitivity of dynamic surface properties of the lung surfactant on exogenous materials which may be introduced to the respiratory system by inhalation of dusty air. Some physicochemical interpretation of these results is presented.

Mathematical modelling of airway reopening

Kuraszkiewicz B.

Biocybernetics and Biomedical Engineering

2004

Vol. 24, no. 3

67-75

The theoretical and experimental investigations of the airway reopening by simulation of the progression of airflow through a fluid or liquid-filled rigid-walled tube (an initial model of pulmonary airway reopening) were performed. Positive pressure drove the "finger" of the air forward to displace the liquid and to obtain the interfacial movement. The air-liquid interface was assumed to be a simple axisymmetric meniscus. In this study the rigid tube radius was R and the "finger" of the air was (1-m)1/2R, where m was a fraction of the viscous fluid left behind on the walls of the tube. The liquid had constant surface tension and viscosity. The capillary number defined the state of the system (the air-liquid interface). This number is the dimensionless velocity that represents the ratio of the viscous to the capillary stresses. A quasi-steady state solution as a function of this parameter using the flow analysis was examined. A semi-empirical formula for the interface was generated by dimensional analysis. The results suggested that the pressures, required to reopen the collapsible airway and non-collapsible airway with the same radius, are similar in the magnitude. These studies showed that the air-liquid interface in the airway collapsible tube model could be sumulated by the meniscus of the air-liquid flow in a rigid circular tube model of the same radius.