Twist angle

The desire to improve sharjDness and viewing angle range led to the development of supertwisted nematic displays name suggests, STN displays have higher twist angles than the TN display, typically 220-270°. They are widely us laptop computers. 

Calculations show that the deviation from planarity leads to greater conformational stability for the phenylthiazoles (143, 145). In particular, the potential energy minimum is achieved at a twist angle of about 30° for 4-phenylthiazole, 40° for 2-phenylthiazole, and 45° for 5-phenylthiazole. 

Figure 7 shows these results schematically for both twist and tilt crack deflections. Thus, for the stress intensity factor required to drive a crack at a tilt or twist angle, the appHed driving force must be increased over and above that required to propagate the crack under pure mode 1 loading conditions. Twist deflection out of plane is a more effective toughening mechanism than a simple tilt deflection out of plane. 

Figure 9.9. Relative boundary energy versus misorienlalion angle for boundaries in copper related by various twist angles about [1 0 0] (after Miura et at. 1990).

Figure 11.S Possible conformations of N2H4 with pyramidal N. Hydrazine adopts the gauche C l form with N N 145 pm, H-N- II 108°. and a twist angle of 95 as shown in the lower diagram.

In Fig. 4 are shown anion and neutral potential curves, as functions of the twist angle of the H2C-C bond in a typical enolate anion (2,4e) such as... 

Therefore, for a rough surface, although it is smooth macro-scopically, the friction coefficient is greatly affected by its surface morphology. For a smooth surface on atomic scale, 0 can be neglected and the friction coefficient is only related to the twist angle of the cantilever. 

X-ray structure analysis showed that macrocycle 57 was essentially planar, with the twist angle of the benzene rings from the plane of the macrocycle being less than 2°. Most of the strain was seemingly contained in the triple bonds, as these were bent from linearity by 10.1° to 12.3°. Despite its strained nature, the macrocycle showed remarkable stability. Decomposition occurred above 300°C on attempted melting. No reaction was observed between 57 and cyclopenta-diene at room temperature. 

The tacit assumption above is that the monodromy matrix is defined with respect to the primitive unit cell, with sides (5v, 8fe) = (0,1) and (1, 0), because the twist angle that determines the monodromy is given by A9 = — (Sv/Sfe)j.. However, situations can arise where other choices are more convenient. For example, the energy levels within a given Fermi resonance polyad are labeled by a counting number v = 0,1,... and an angular momentum that takes only even or only odd values. Thus the convenient elementary cell has sides (8v, 8L) = (0,2) and (1, 0), and the natural basis, say, y, is related to the primitive basis, x, by... 

The nature of the above distortion leads to an associated multivaluedness in the vibrational quantum number, which can be attributed to the fact that the twist angle of the classical invariant tori increases 2n on a cycle around the critical singularity. 

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