Phase transitions of fluorotelomer alcohols at the water|alkane interface studied via molecular dynamics simulation.

Fluorosurfactants are long-lasting environmental pollutants that accumulate at interfaces ranging from aerosol droplet surfaces to cell membranes. Modeling of adsorption-based removal technologies for fluorosurfactants requires accurate simulation methods which can predict their adsorption isotherm and monolayer structure. Fluorotelomer alcohols with one or two methylene groups adjacent to the alcohol (7 : 1 FTOH and 6 : 2 FTOH, respectively) are investigated using the OPLS-AA force field at the water|hexane interface, varying the interfacial area per surfactant. The acquired interfacial pressure isotherms and monolayer phase behavior are compared with previous experimental results. The results are consistent with the experimental data inasmuch as, at realistic adsorption densities, only 7 : 1 FTOH shows a phase transition between liquid-expanded (LE) and 2D crystalline phases. Structures of the LE and crystalline phases are in good agreement with the sticky disc and Langmuir defective crystal models, respectively, used previously to interpret experimental data. Interfacial pressure of the LE phase agrees well with experiment, and sticky disc interaction parameters indicate no 2D LE-gas transition is present for either molecule. Conformation analysis reveals 7 : 1 FTOH favors conformers where the OH dipole is perpendicular to the molecular backbone, such that the crystalline phase is stabilized when these dipoles align.

Near fatal desquamative interstitial pneumonia with bilateral recurrent tension pneumothorax.

Desquamative interstitial pneumonia (DIP) is an uncommon form of interstitial lung disease demonstrating good response to corticosteroid therapy and favorable prognosis. In rare cases, patients with DIP fail to respond to corticosteroid therapy, and may progress to end-stage fibrotic lung disease with respiratory failure. For such patients, well defined treatment regimen does not exist until now. We report a rare case of near fatal DIP with recurrent bilateral tension pneumothorax despite of corticosteroid maintenance therapy. Clinical and radiological findings improved with surgical intervention in addition to combination therapy with prednisolone and clarithromycin. The patient has remained in an improved state and has been receiving prednisolone and clarithromycin for 9 months.