A fluorescence approach to investigate repartitioning of coalescing agents in acrylic polymer emulsions

Repartitioning of co-solvents between particles of latex emulsions was investigated by means of a fluorescence method based on the detection of the amount of co-solvent via the solvatochromic shift of the emission maximum of a fluorescent probe, copolymerized at a low concentration. Complete repartitioning of co-solvents between particles of latex materials with a low Tg (ca. 25 °C) occurred within minutes. For a hydrophilic latex with a Tg of 68 °C, equilibration was achieved within an hour. Repartitioning was faster for more hydrophobic co-solvents. For a hydrophobic latex of similar Tg, co-solvent repartitioning took place on the same time scale, but complete equilibration was not reached. Possibly, there is an additional slow component in the repartitioning, or the prolonged presence of co-solvent causes a structural change in the latex particles that affects the outcome of the experiment

External carotid endarterectomy for amaurosis fugax in the presence of internal carotid artery occlusion

Two patients with occlusion of the internal carotid artery who were experiencing repeated episodes of transient monocular blindness in the ipsilateral eye were successfully treated with external carotid endarterectomy. The mechanisms for the production of symptoms in the presence of an internal carotid occlusion are discussed, including the anatomical pathways for embolization through collaterals between the internal and external carotid arteries. The indications, technique and results of external carotid endarterectomy are reviewed