1 By convention a normal lens on a 35mm film camera (and thus a full-frame EOS digital SLR) has a focal length of 50mm or so. 2  A lens with a focal length of 35mm is considered ânormalâ for a cropped-frame EF-S camera.
Aspirin. One of the best known aromatic acetates is acetylsalicylic acid, or aspirin, which is prepared by the esterification of the phenolic hydroxyl group of salicylic acid. Aspirin possesses a number of properties that make it the most often recommended drug.
Aspirin is chemically designated as acetylsalicylic acid and has a chemical structure that is comprised of three chemical groupsan aromatic ring, an ester group, and a carboxylic acid group. Aspirin is prepared by chemical synthesis from salicylic acid by acetylation with acetic anhydride.spirin acts by preventing the formation of prostaglandins. The name prostaglandin comes from the old belief that this hormone was produced by the prostate gland. It is now known that prostaglandins come in several different forms (named by the letters A through I) and are produced in almost all mammalian cells.