Anisotropic nature

The principal dilTerence from liquid-state NMR is that the interactions which are averaged by molecular motion on the NMR timescale in liquids lead, because of their anisotropic nature, to much wider lines in solids. Extra infonnation is, in principle, available but is often masked by the lower resolution. Thus, many of the teclmiques developed for liquid-state NMR are not currently feasible in the solid state. Furthemiore, the increased linewidth and the methods used to achieve high resolution put more demands on the spectrometer. Nevertheless, the field of solid-state NMR is advancing rapidly, with a steady stream of new experiments forthcoming. 

This calculation, which holds true for most metals, is generally applicable to TPs. However, the designer is to be familiar with the inherently nonlinear, anisotropic nature of most plastics, particularly the fiber-reinforced and liquid crystal plastics (Chapter 6). 

The molecular structures of many common liquid crystals are long and rodlike. In addition, they contain polar groups. Explain how both characteristics of liquid crystals contribute to their anisotropic nature. 

Following usual conventions, repeated indices indicate summation and fy denotes df/dXj. The permutation S5mibol is used to present the vector cross product in indicial notation. Due to the anisotropic nature, traction and body couples can exist, and thus the angular momentum equation must be considered. For purely viscous fluids this equation says simply that the deviatoric stresses are symmetric. 

Explosive research activity is going on in micellar photochemistry. This is related to the development of artificial photosynthetic systems, and the anisotropic nature of globular micelles and bilayer membranes is used for conservation of excitation energy. The subject has been recently reviewed (Kalyanasundaram, 1978). 

A very useful development of water/metal potential energy functions, which takes into account the anisotropic nature of the water/metal interactions, has been recently presented by Zho and Philpott." They used a fit to the ab initio binding energy of water on several metal surfaces and applied some simplifying assumptions to develop potentials for the inter-... 

The most characteristic feature of alkaline solution etching is its anisotropic nature [13]. For example, in 20% KOH at room temperature, the etch rate at the OCP of the (100) plane is a hundredfold higher than the (111) plane. In general, because of the anisotropic etching process, the morphology of the surface shows smooth ideal (111) sidewalls thus forming micropyramids on (100) wafers, as shown in Fig. 12. 

The anisotropic nature of the dipolar, quadrupolar and chemical shift anisotropy interactions requires that the isotropy of molecular orientation relative to the applied magnetic field be broken in order to allow their direct observation in terms of shifts in the frequencies of resonances.20,32,38 40 For high resolution NMR studies this has meant, thus far, that some degree of alignment of the molecule needs to be established. Almost all molecules will align to a small extent due to the anisotropy of their magnetic... 

There are experimental results that show the anisotropic nature of diffusion of methane in silicalite (24, 77). From a stochastic jump model of the diffusion process, Karger et al. (24) found that the ratio of the rate of diffusion in the direction of the two channel systems should not be less than 4.4 times that in the orthogonal direction ... 

PG and HOPG materials play an important role in understanding carbon electrode structure and reactivity due to their anisotropic nature [2]. In some special cases, basal plane HOPG and EPG electrodes are of particular value in electroanalytical applications for both fundamental and pragmatic reasons. Examples are shown in Figures 10.7 to 10.9. Figure 10.7 shows the voltammetry... 

Of importance in catalytic studies, is that the anisotropic nature of the recoil-free fraction can be deduced also for samples where the orientation of the surface is not known (e.g., powdered samples), as noted earlier (Section I, C, 5). In this case, the recoil-free fraction is not measured directly, but its... 

The finite volume methods have been used to discretised the partial differential equations of the model using the Simple method for pressure-velocity coupling and the second order upwind scheme to interpolate the variables on the surface of the control volume. The segregated solution algorithm was selected. The Reynolds stress turbulence model was used in this model due to the anisotropic nature of the turbulence in cyclones. Standard fluent wall functions were applied and high order discretisation schemes were also used. 

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