|
|
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
Coca-Cola originally used coca leaves and caffeine from the African kola nut. It was advertised as a therapeutic agent and "pickerupper." Eventually, its formulation was changed, and the coca leaves were removed because of the effects of regulation on cocaine-related products.
Every 10 seconds, a person in the United States goes to the emergency room complaining of head pain. About 1.2 million visits are for acute migraine attacks.
The lipid bilayer is made of phospholipids. They are arranged in a double layer because one of their ends is attracted to water while the other is repelled by water.