oxides
111duricrust — /door i krust , dyoor /, n. a hard crust that forms on or in soil in semiarid climates owing to cementation of soil particles. Cf. caliche, hardpan (defs. 1, 2). [ < L dur(us) hard + I + CRUST] * * * ▪ geology Introduction surface or near… …
112motorcycle — motorcyclist /moh teuhr suy klist/, n. /moh teuhr suy keuhl/, n., v., motorcycled, motorcycling. n. 1. a motor vehicle similar to a bicycle but usually larger and heavier, chiefly for one rider but sometimes having two saddles or an attached… …
113nitrogen — /nuy treuh jeuhn/, n. Chem. a colorless, odorless, gaseous element that constitutes about four fifths of the volume of the atmosphere and is present in combined form in animal and vegetable tissues, esp. in proteins: used chiefly in the… …
114Selected International Environmental Agreements — Air Pollution see Convention on Long Range Transboundary Air Pollution Air Pollution Nitrogen Oxides see Protocol to the 1979 Convention on Long Range Transboundary Air Pollution concerning the Control of Emissions of Nitrogen Oxides or Their… …
115Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity. Computer scientist Manindra Agrawal of the… …
116copper processing — Introduction use of smelting or leaching, usually followed by electrolytic refining or recovery, to turn the ore into a form from which products can be fashioned. Included in this article also is a discussion of the mining of copper and of its… …
117iron processing — Introduction use of a smelting process to turn the ore into a form from which products can be fashioned. Included in this article also is a discussion of the mining of iron and of its preparation for smelting. Iron (Fe) is a… …
118mineral deposit — Introduction aggregate of a mineral in an unusually high concentration. About half of the known chemical elements (chemical element) possess some metallic (metal) properties. The term metal, however, is reserved for those chemical… …
119respiratory disease — ▪ human disease Introduction any of the diseases and disorders that affect human respiration (respiration, human). Diseases of the respiratory system may affect any of the structures and organs that have to do with breathing, including the… …
120Freshwater environmental quality parameters — are the natural and man made chemical, biological and microbiological characteristics of rivers, lakes and ground waters, the ways they are measured and the ways that they change. The values or concentrations attributed to such parameters can be… …
