liquid crystal

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liquid crystal

A substance that alters its color or changes from opaque to transparent when subjected to changes in temperature, electric current, pressure, or electromagnetic waves, or when impurities are present. Liquid crystals have been used to detect temperature fluctuation in infants and may be divided into two general classes: cholestric, which change color; and nematic, which can change back and forth from transparent to opaque.
See also: crystal
References in periodicals archive ?
In this work, we investigate the problem of a flat membrane with coupled nematic order when defects of the +1 kind appear.
Because of the identical hydrodynamics of the nematic director and elongated particles, there is a close analogy between the Larson-Doi polydomain model for liquid crystal polymers and the Folgar-Tucker fiber orientation model widely used in composites manufacturing (18).
Cotter, M.A.; Hard spherocylinders in an anisotropic mean field: A simple model for a nematic liquid crystal, Journal Chemical Physics: 66 (3), 1098-1106 (1977)
A nematic liquid crystal has a molecular architecture which makes it a medium with a direction-dependent refractive index [5].
The simplest theory is the Ericksen model (11), which provides an evolution equation for the nematic director, n, (which indicates the direction about which molecules are spontaneously ordered in the liquid crystalline state) under applied flow:
Chiccoli et al., "Nematics with quenched disorder: pinning out the origin of memory," Physical Review Letters, vol.
PDLCs consist of micron-size droplets of a low-molar-mass nematic liquid crystal dispersed in a polymer matrix.
More specifically, we consider how the polarization azimuth affects the reorientational dynamics of the electrically assisted light-induced azimuthal gliding of the easy axis that takes place on photoaligned azo-dye layers when irradiation of nematic LC (NLC) cells with LPUV light is combined with the application of ac in-plane electric field [13].
A number of different chiral BN derivatives were recently successfully used as effective chiral dopants for low-molar-mass LCs giving chiral nematic phases (9, 13, 14).
This complex rheology can give rise to peculiar viscoelastic results, including the following (although not always observed): the viscosity drops abruptly at the transition from the isotropic to the liquid crystalline nematic phase; three distinct regions can be detected in the curve of the viscosity vs.
In the nematic phase, the molecules are inherently locally aligned.
A new configurational transition in inhomogeneous nematics. Liquid Crystals, 16(4):713-718, 1994.