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Vaccines and medicines need to be stored in cool places—not so easy to
find in parts of the world with no access to electricity. To preserve vaccines
in hot conditions, scientists at the University of Jordan have designed a
cooling cabinet that runs on solar energy. The unit uses the familiar ammonia
absorption cycle for refrigeration—ammonia is driven out of an aqueous
solution by the Sun’s heat, and is then condensed and circulated back into
solution through an evaporator. The designers particularly want to improve
healthcare for nomadic tribes.