Similarity of orientation

Fig. 17. Composite structural motions of subunits can be described with translation, libration, and screw-axis (TLS) analysis of the NCP. Analysis of the histone subunits are shown here, (a) Composite motion of histones H2A (blue) and H2B (blue) considered as individual elements and combined as H2A H2B dimer (red). Note for the individual histones that the axis of motion is parallel with the medial a-helix of the histone. The origin of the TLS axes are within the structural positions of the histone. The composite motion for the H2A H2B dimer is dominated by the motion of H2A, as is seen in the similarity of orientation and position of the two axes, (b) The orientation and motion of the two H2A H2B dimers appear symmetric across the dyad axis of the NCP. (c) H3 H4 composite motions when considered as dimers (blue) and as the tetramer (red). Interpretation is more complex because of the asymmetric magnitude of motion for the two dimers, and the different position in the axis of primary motion for the tetramer. These motions are most likely the consequence of packing interactions, described in greater detail in the text.

S transforms o i 0 2 Q3 0 4 as r f into the symmetry coordinate basis X)r). Normalization factors are included in S but omitted from X),), as is usually the case in character tables. For the reason given in the text, in this group a4 0 5 are used to define similarity of orientation in the doubly degenerate E representation. 

But since K is symmetric, [gy] vanishes in this point group (and, in fact, in all the uniaxial C v point groups). (Note the importance of similarity of orientation in reaching the correct conclusions in this example.)... 

The allocation of vector and tensor components to IRs and similarity of orientation have already been determined for the point group C3v in Exercise 15.3-1. Therefore the linear equations relating the vector xy z and the symmetric T(2) o are... 

Nylon-6,6 and nylon-6 have competed successfully ia the marketplace siace their respective commercial iatroductioas ia 1939 and 1941, and ia the 1990s share, about equally, 90% of the total polyamide market. Their chemical and physical properties are almost identical, as the similarity of their chemical stmcture might suggest the amide functions are oriented ia the same directioa aloag the polymer chain for ayloa-6, but are altematiag ia directioa for ayloa-6,6. 

Hence, the main aim of the technological process in obtaining fibres from flexible-chain polymers is to extend flexible-chain molecules and to fix their oriented state by subsequent crystallization. The filaments obtained by this method exhibit a fibrillar structure and high tenacity, because the structure of the filament is similar to that of fibres prepared from rigid-chain polymers (for a detailed thermodynamic treatment of orientation processes in polymer solutions and the thermokinetic analysis of jet-fibre transition in longitudinal solution flow see monograph3. ... 

According to a recent report, the unit cell of cellotetraose hemihydrate in single crystals contains two antiparallel chains, which are conformationally distinct—especially in the sugar geometries.74 However, all hydroxymethyl groups adopt similar gt orientations. Whether this oligosaccharide morphology can be implemented for cellulose II in fibers remains to be seen. 

For oriented systems, the determination of molecular conformation is a complex problem because Raman spectra contain signals inherently due to both molecular conformation and orientation. To extract only the information relative to the conformation, one has to calculate a spectrum that is independent of orientation, in a similar way to the A0 structural absorbance of IR spectroscopy (Section 4). Frisk et al. [57] have shown that for a uniaxial sample aligned along the Z-axis, a spectrum independent of orientation (so-called isotropic spectrum), fso, can be calculated from the following linear combination of four polarized spectra [57]... 

Platt, D. E., and D. Silverman. 1996. Registration, Orientation, and Similarity of Molecular Electrostatic Potentials Through Multipole Matching. J. Comp. Chem. 17, 358. 

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