Safer water for poorer nations.In the world's developing nations, more than 400 children die every hour from diseases such as cholera, typhoid fever typhoid fever acute, generalized infection caused by Salmonella typhi. The main sources of infection are contaminated water or milk and, especially in urban communities, food handlers who are carriers. , dysentery dysentery (dĭs`əntĕr'ē), inflammation of the intestine characterized by the frequent passage of feces, usually with blood and mucus. , and hepatitis, which they contract by drinking contaminated water. To stem this threat, Ashok J. Gadgil, a physicist at the Lawrence Berkeley (Calif.) National Laboratory, and his colleagues have built a simple device that uses ultraviolet light Ultraviolet light A portion of the light spectrum not visible to the eye. Two bands of the UV spectrum, UVA and UVB, are used to treat psoriasis and other skin diseases. to rid water of pathogens. The tabletop system takes in water from a well or hand pump, for example, bathes it with ultraviolet radiation from a mercury-vapor lamp, and sends it out free of germs. Ultraviolet light has the "highest germicidal germicidal /ger·mi·ci·dal/ (jer?mi-si´d'l) antimicrobial (1). germicidal destructive to pathogenic microorganisms. efficiency" at a wavelength of 254 nanometers, he says. The current model can disinfect To remove the virus code that has attached itself to a legitimate file. Sometimes, the antivirus program cannot untangle the code, and the infected file has to be deleted. See quarantine. 15 gallons per minute at a cost of 2 cents per metric ton of water. It weighs 15 pounds, costs $300, draws only 40 watts of power supplied by solar cells, and can run unsupervised in remote locations. Serving a community of 1,000 in the developing world, one unit could prevent 15 infant deaths and 150 cases of stunted growth during its service life of 15 years, Gadgil estimates. |
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