21.   They include sand flies, stress and chemical reactions between insecticides and a drug given to troops as protection against nerve gas.

22.   Was there a reaction between kava and other medications?

23.   Zinc-air batteries, which generate power through a chemical reaction between zinc and oxygen, are common in hearing aids, for example.

24.   A fuel cell creates electricity through a reaction between hydrogen and oxygen.

25.   And the industry is headed to fuel cells, which produce energy from a chemical reaction between hydrogen and oxygen.

26.   EPD officials said the pollution was from chemical reactions between vehicle pollutants, like nitrogen oxides and hydrocarbons, and ozone in the atmosphere.

27.   Fuel cells create electricity from a reaction between hydrogen and oxygen, with water vapor the only tailpipe emission.

28.   Fuel cells, first used by NASA in the space program, create electricity through a chemical reaction between hydrogen and oxygen.

29.   Fuel cells create electricity through a chemical reaction between hydrogen and oxygen.

30.   Fuel cells generate electricity using a chemical reaction between hydrogen and oxygen.