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dermatitis

(Encyclopedia)dermatitis dûrˌmətīˈtĭs [key], nonspecific irritation of the skin. The causative agent may be a bacterium, fungus, or parasite; it can also be a foreign substance, known as an allergen. Contact ...

pheromones

(Encyclopedia)pheromones, any of a variety of substances, secreted by many animal species, that alter the behavior of individuals of the same species. Sex attractant pheromones, secreted by a male or female to attr...

conduction

(Encyclopedia)conduction, transfer of heat or electricity through a substance, resulting from a difference in temperature between different parts of the substance, in the case of heat, or from a difference in elect...

tracer

(Encyclopedia)tracer, an identifiable substance used to follow the course of a physical, chemical, or biological process. In chemistry the ideal tracer has the same chemical properties as the molecule it replaces a...

marcasite

(Encyclopedia)marcasite märˈkəsīt [key] or white iron pyrites, a mineral closely resembling and having the same chemical composition (FeS2) as pyrite. It differs from pyrite in that it is paler in color, become...

functional group

(Encyclopedia)CE5 functional group, in organic chemistry, group of atoms within a molecule that is responsible for certain properties of the molecule and reactions in which it takes part. Organic compounds are f...

polymorphism

(Encyclopedia)polymorphism, of minerals, property of crystallizing in two or more distinct forms. Calcium carbonate is dimorphous (two forms), crystallizing as calcite or aragonite. Titanium dioxide is trimorphous;...

Epsom salts

(Encyclopedia)Epsom salts, common name for magnesium sulfate heptahydrate, MgSO4·7H2O, a water-soluble bitter-tasting compound that occurs as white or colorless needle-shaped crystals. It was first prepared from t...

Kraft, Adam

(Encyclopedia)Kraft or Krafft, Adam both: äˈdäm kräft [key], c.1455–1509, German sculptor of Nuremberg. He moved from an ornamental late Gothic style toward clarity, symmetry, and a powerful use of rounded, o...

white alder

(Encyclopedia)white alder, deciduous shrub or small tree (Clethra alnifolia) native to the Appalachians, named for the resemblance of its leaves to those of the unrelated true alders. It is cultivated as an ornamen...