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cataract

(Encyclopedia)cataract, in medicine, opacity of the lens of the eye, which impairs vision. In the young, cataracts are generally congenital or hereditary; later they are usually the result of degenerative changes b...

refrigeration

(Encyclopedia)CE5 Compression system of refrigeration refrigeration, process for drawing heat from substances to lower their temperature, often for purposes of preservation. Refrigeration in its modern, portabl...

smog

(Encyclopedia)smog smŏg [key] [smoke+fog], dense, visible air pollution. Smog is commonly of two types. The gray smog of older industrial cities like London and New York derives from the massive combustion of coal...

aerosol dispenser

(Encyclopedia)aerosol dispenser, device designed to produce a fine spray of liquid or solid particles that can be suspended in a gas such as the atmosphere. The dispenser commonly consists of a container that holds...

dry cleaning

(Encyclopedia)dry cleaning, process of cleaning fabrics without water. Special solvents and soaps are used so as not to harm fabrics and dyes that will not withstand the effects of ordinary soap and water. Dry clea...

ultraviolet radiation

(Encyclopedia)ultraviolet radiation, invisible electromagnetic radiation between visible violet light and X rays; it ranges in wavelength from about 400 to 4 nanometers and in frequency from about 1015 to 1017 hert...

mass extinction

(Encyclopedia)mass extinction, the extinction of a large percentage of the earth's species, opening ecological niches for other species to fill. There have been at least ten such events. The five greatest were thos...

sunburn

(Encyclopedia)sunburn, inflammation of the skin caused by actinic rays from the sun or artificial sources. Moderate exposure to ultraviolet radiation is followed by a red blush, but severe exposure may result in bl...

endoderm

(Encyclopedia)endoderm ĕnˈdədûrmˌ [key], in biology, inner layer of tissue formed in the gastrula stage of the developing embryo. At the end of the blastula stage, cells of the embryo are arranged in the form ...

Schönbein, Christian Friedrich

(Encyclopedia)Schönbein, Christian Friedrich krĭsˈtyän frēˈdrĭkh shönˈbīn [key], 1799–1868, German chemist. From 1828 he taught at the Univ. of Basel (as professor from 1835). He discovered ozone (1840)...