(1974). Thorax, 29,[407][408][409][410][411][412][413][414][415][416]. Bronchiectasis: results of surgical and conservative management. A review of 393 cases. A consecutive series of 393 cases of bronchiectasis referred to a thoracic surgical unit has been followed up for one to 15 years. About two-thirds were managed surgically and one-third conservatively. The progress of the patients is analysed and the results of treatment are evaluated. The role of associated bronchitis is considered and indications for surgery are defined. It is our opinion that the current bias towards conservative management is unjustified.

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An all-new sealing system for a rotating shaft, which specializes in excellent separation between water and air, has been developed for installation in an ocean current or tidal power generator. Two seal lips made of a polyvinyl formal (PVF) were attached to a rotating shaft, and an aqueous solution of 3.0 wt% polyethylene glycol (PEG), a non-Newtonian fluid with a molecular weight of 2.0 million, was supplied between two lips for lubrication. Expected lubrication modes between the dynamic seal surfaces were hydration lubrication, softelastohydrodynamic lubrication, and weeping lubrication, similar to that observed in a natural synovial joint. Using PVF with a small porous diameter of 8 m and continuously porous structure promoted hydration lubrication between seal surfaces at the molecular level, and low leakage of water, less than 0.05 ml/h, throughout the experiment. Mean frictional torque was lower than that found in the mechanical and oil seals that are generally used for industrial components. Frictional torque had been stable; the friction was independent of the shaft rotational speed, and the stick-slip friction that might lead to leakage of water was moderated in comparison with the conventional sealing systems.

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