Inversion(redirected from sexual inversion)
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in chemistry. (1) A change in the conformation of a cyclic molecule as a result of which the orientation of the substituent with respect to the ring changes. For example, methylcyclohexane exists in the form of an equilibrium mixture of two conformations, form II predominating (see Figure 1).
The frequency of inversion depends on the nature of the substituents and on temperature.
(2) The conversion of the configuration of a molecule containing a trivalent “pyramidal” atom (for example, nitrogen or arsenic) into the mirror image. Thus, for a molecule with a trivalent atom, forms I and II are the optical antipodes:
where a, b, and c are different atoms or groups of atoms. The energy barrier for inversion is usually low and depends on the temperature and the nature of a, b, and c. For the carbon atom (a “tetrahedral” atom), the term “configuration reversal” is usually used.
(3) The inversion of sugar is the hydrolysis of a saccharose (such as beet sugar) accompanied by a change in the direction of rotation of the plane of a polarized beam of light by a sugar solution.
B. L. DIATKIN
(1) In geometry, inversion with respect to a given circle of radius R with a center O is a transformation (see Figure 1) in which a point P is converted to a point P ′ (in Figure 1 the points Pand P ′ are given with numerical subscripts), which lies on a radial line OP at a distance OP ′ = R2/OP from the center O; the number R2 is called the inversion factor. Upon inversion, straight lines and circles become straight lines and circles, and circles, for example, may become straight lines and vice versa. Inversion in space with reference to a sphere is defined similarly. The transformation of an inversion has numerous applications in geometry (the interpretation of Lobachevskii’s geometry, the theory of geometric constructions) and in the theory of mechanisms—so-called inversors.
(2) In combinatorial analysis, inversion is the disruption of the normal sequence of two elements in a permutation regardless of whether these two terms stand together or are separated from each other by some other elements, for example, in the permutation eacbd the terms a and e, c and e, b and e, d and e, and b and c form an inversion if abcde is considered to be the normal order.
a change in the usual word order in a sentence. Inversion is generally used to accentuate the rearranged element in the sentence and to give the entire sentence special meaning. In languages with fixed word order, inversion has a grammatical function—for example, to form interrogative sentences in Russian, English, and French. It is one of the aspects of the actual division of a sentence—for example, Russian Videl ia otsa (“Saw I Father”) and German Den Sohn liebt die Mutter (literally, “The son [accusative] loves the mother [nominative],” that is, “The mother loves the son”).
Frequently, inverted forms that are not accepted in everyday speech are used in poetry. For example, A. S. Pushkin: Minutnykh zhizni vpechatlenii / Ne sokhranit dusha moia (roughly, “The fleeting impressions of life/ My soul does not retain”) and Pod vecher, osen ‘iu nenastnoi, / V dalekikh deva shla mestakh (roughly, “Toward evening, in rainy autumn, / In far-off places a maiden walked”).