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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.
Approximately 500,000 babies are born each year in the United States to teenage mothers.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
In the United States, an estimated 50 million unnecessary antibiotics are prescribed for viral respiratory infections.
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.