Prediction of shear stress imposed on alveolar epithelium of healthy and diseased lungs.

Lung alveoli are modeled as spherical caps, lined internally by a thin surfactant-laden liquid film, and the periodic wall shear stress exerted along the epithelium during small-amplitude radial oscillations of their wall is computed. A novel set of boundary conditions, applied at the rim, reveals the dominant role of Marangoni stresses. These stresses develop along the air/liquid interface due to spatial gradients of interfacial surfactant concentration and are transported to the wall by the action of viscosity.

Application of a One-Dimensional Computational Model for the Prediction of Deposition from a Dry Powder Inhaler.

Background: Accurate prediction of the regional deposition of inhaled dry powders as a function of powder properties and breathing pattern is a long-term research goal for pulmonary drug delivery. In the present work, deposition along the respiratory tract of dry powders of Fluticasone propionate and Salmeterol is predicted.

Methods: A one-dimensional particle transport and deposition model is used, whose novelty is in the treatment of the alveolar space of each airway generation as an efficient mixing chamber.

Prediction of particle deposition in the lungs based on simple modeling of alveolar mixing.

A simplified model of particle deposition in the lungs has been developed and implemented, based on the hypothesis that perfect mixing takes place in the alveolar volume of each airway generation. This key idea is combined with purely convective transport along airways, driven by steady alveolar expansion and contraction, and results in an analytically tractable model. Predictions of the model, and in particular pulmonary deposition, are found in very good agreement with detailed benchmark data in the literature for particle diameters d ≥ 0.

Measurements of liquid film flow as a function of fluid properties and channel width: evidence for surface-tension-induced long-range transverse coherence.

We study experimentally the influence of the transverse dimension on film flow in relatively wide channels with sidewalls. Large deviations from two-dimensional predictions are observed in the primary instability and in the post-threshold traveling waves, and the deviations are presently shown to depend strongly on fluid physical properties. Measurements for a wide range of fluid properties are found to correlate with the Kapitza number, which represents the ratio of capillary to viscous stresses.

Decolorization kinetics of Procion H-exl dyes from textile dyeing using Fenton-like reactions.

The decolorization kinetics of three commercially used Procion H-exl dyes was studied using a Fenton-like reagent. The effect of the major system parameters (pH, concentration of H(2)O(2) and Fe(3+) and initial dye concentration) on the kinetics was determined. For comparison, the effect of the use of UV irradiated Fenton-like reagent and of Fenton reagent on the kinetics was also examined.