Section(redirected from perineal section)
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in architecture, the frontal projection of a building or an architectural detail that is arbitrarily cut by a plane or a system of planes. The configuration of architectural details, volumes, or interior spaces can be symbolized by a section drawing. A section also characterizes the form and configuration of a structure.
in botany, a taxonomic category intermediate between a subgenus and a series. The name of a section is designated by a noun. A section that includes the type species of a given subgenus has the same name as the subgenus. For example, in the genus Carex (sedge) the designation Vignea is used for both the subgenus and the section that includes the type species of the subgenus (Carex arenaria). Thus, the name used to indicate the section to which the species belongs is Carex (sect. Vignea) arenaria.
(1) A division or subdivision of an organization or institution.
(2) A group of delegates chosen to work on a set of questions at congresses or meetings.
in geology, a thin, flat piece of rock, mineral, or fossil coal used in microscopic studies. The most commonly used sections are thin sections—flat pieces 0.02–0.03 mm in thickness prepared mainly from silicate rocks. At such a thickness, most minerals are translucent, which makes it possible to study them with a polarizing microscope to determine the optical properties of the minerals, the crystal structure, the nature of interrelationships, and other aspects of minerals. The study of thin sections is one of the primary techniques of petrography. Sections 0.005–0.035 mm in thickness are used to study fossil coals. Sections are made by grinding one side of a fragment of rock or mineral of any thickness on a special grinding machine, cementing the polished side to a glass slide with Canadian balsam or some other organic resin, and then grinding the other surface until the section reaches the proper thickness.
Polished translucent sections, in which the upper surface of the section is polished with special care, are made to study the composition of minerals by spectral X-ray analysis. For opaque minerals, mostly ores, polished sections are used, which are usually 0.5–1.0 cm in thickness, polished on one side, and mounted on a glass slide with mastic or modeling clay. The study of polished sections of ore minerals is the task of mineragraphy, or mineralo-graphy, an important branch of mineralogy.
A. M. BORSUK