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heat

(Encyclopedia)heat, nonmechanical energy in transit, associated with differences in temperature between a system and its surroundings or between parts of the same system. The study of heat and its relationship ...

sulfur

(Encyclopedia)CE5 Sulfur crystals sulfur or sulphur sŭlˈfər [key], nonmetallic chemical element; symbol S; at. no. 16; interval in which at. wt. ranges 32.059–32.076; m.p. 112.8℃ (rhombic), 119.0℃ (mon...

blood clotting

(Encyclopedia)blood clotting, process by which the blood coagulates to form solid masses, or clots. In minor injuries, small oval bodies called platelets, or thrombocytes, tend to collect and form plugs in blood ve...

dissociation

(Encyclopedia)dissociation, in chemistry, separation of a substance into atoms or ions. Thermal dissociation occurs at high temperatures. For example, hydrogen molecules (H2) dissociate into atoms (H) at very high ...

carbon

(Encyclopedia)CE5 The three solid forms of pure carbon: In the diamond crystal each carbon atom is surrounded symmetrically by four other carbons (at each of the four corners of a tetrahedron). In the graphite c...

combustion

(Encyclopedia)combustion, rapid chemical reaction of two or more substances with a characteristic liberation of heat and light; it is commonly called burning. The burning of a fuel (e.g., wood, coal, oil, or natura...

nitrate

(Encyclopedia)nitrate, chemical compound containing the nitrate (NO3) radical. Nitrates are salts or esters of nitric acid, HNO3, formed by replacing the hydrogen with a metal (e.g., sodium or potassium) or a radic...

radioimmunoassay

(Encyclopedia)radioimmunoassay (RIA), highly sensitive laboratory technique used to measure minute amounts of substances including antigens, hormones, and drugs present in the body. The substance or antigen (a fore...

density

(Encyclopedia)density, ratio of the mass of a substance to its volume, expressed, for example, in units of grams per cubic centimeter or pounds per cubic foot. The density of a pure substance varies little from sam...

lipids

(Encyclopedia)lipids, a broad class of organic products found in living systems. Most are insoluble in water but soluble in nonpolar solvents. The definition excludes the mineral oils and other petroleum products o...