1. Turning or movement of a body round its axis. 2. A recurrence in regular order of certain events, such as the symptoms of a periodic disease. [L. rotatio, fr. roto, pp. rotatus, to revolve, rotate]
intestinal r. See malrotation.
molecular r. one hundredth of the product of the specific r. of an optically active compound and its molecular weight.
optical r. the change in the plane of polarization of polarized light of a given wavelength upon passing through optically active substances; measured in terms of specific rotation by polarimetry, an important tool in chemical structural work, especially on carbohydrates.
specific optical r. ([a]) the arc through which the plane of polarized light is rotated by 1 gram of a substance per milliliter of water when the length of the light path through the solution is 1 decimeter, typically using light corresponding to the D line of sodium.
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