Director mode

Because the equilibrium order in heterophase systems is characterized by only one nonzero degree of freedom of the order parameter tensor, the fluctuation modes of all five degrees of freedom are uncoupled. Due to the uniaxial symmetry of the phase the two biaxial modes are degenerate and so are the two director modes. If a nematic layer is bounded by walls characterized by a strong surface interaction and a bulk-like value of the preferred degree of order, the fluctuation modes /3j s are sine waves, and their relaxation rates may be cast into... 

Director modes are, as opposed to biaxial fluctuations, excited very easily in the nematic phase, where their Hamiltonian is purely elastic, whereas in the isotropic phase they are characterized by a finite correlation length. This implies that their wetting-induced behavior should be quite the inverse of that of biaxial modes. Thus, in the disordering geometry, the director modes are forced out of the substrate-induced isotropic boundary layer into the nematic core (see Fig. 8.6 bottom). The lowest mode is a Goldstone mode. In the paranematic phase a few lowest director modes are confined to the nematic boundary layer, whereas the upper ones extend over the whole sample and are more or less the same as in the perfectly isotropic phase. 

Control System Autopilot/Flight Director Modes Autothrotde Modes... 

A major simplification in Gmi,( ) is achieved [6.5, 6.8] by separately averaging the director modes and molecules reorientation. This is possible if the time scales for these motions are very different and becomes... 

The Orsay Liquid Crystal Group [28] determined a model of director modes of fluctuation based on the hydrodynamic description of nematic phases by Leslie [29] and Ericksen [30]. This approach developed the subject of dynamic light scattering in liquid crystals, and allows viscoelastic ratios to be deduced from light scattering data. For singly scattered light from a material, the time... 

For q perpendicular to the director, Bq, the second sound mode again disappears, becoming a shear mode and a layer undulation mode. In this case the mode plays the same role in the SmA phase as the director Mode 1 does in nematic liquid crystals. 

H. K. M. Vithana, G. Xu, D. L. Johnson, Dynamics of the lowest order bend-twist director mode near nematic-smectic-A criticality, Phys. Rev. E 1993, 47, 3441-3455. 

Fig. 6.1 Pictorial representation of the polymer chains inserted into the liquid crystal layers. The free volumes are represented by the dark ellipses inside the polymeric chains. This figure demonstrates the trapped director mode over the surface of the nano volumes...

Taken from the three spontaneous symmetry-breaking events leading to this layer structure [formation of layers with long-range orientational order of the director (Sm), tilt of the director from the layer normal (C), and polar orientation of the molecular arrows (P)], we term phases of this type SmCP. All of the complex textures and EO behavior of NOBOW in the B 2 phase can be understood in terms of various stacking modes of SmCP layers as shown in Figure 8.23. 

Pyrroles and indoles have one further unique mode of lateral lithiation—deprotonation of an Af-methyl group (also an a lithiation). The reaction works particularly weU with an aldehyde director, temporarily protected as the a-amino alkoxide 565 (Scheme 228)°° . 

Abelli, Mode to( 1859-1911). Ital scientist who specialized in expls. Was director for a numberofyears of the Nobel Dynamite Plant at Avigliana... 

The super birefringent effect (SBE-LCD) reported by Scheffer and Nehring from Brown Boveri in Baden, Switzerland, uses the optical interference of two normal, elliptically polarised modes of transmitted light generated by a high-tilt, highly-twisted nematic structure viewed between two polarisers set in an unusual way, i.e. the input polarisation direction is not parallel to the nematic director at either substrate surface and the polarisers are not crossed at 90°, see Figure 3.10. 

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