Rotation of domains

Assuming an increase in the temperature of the tested samples under applied ac fields possibly due to the rapid rotation of domains, thermal expansion of the PLZT ceramic can be contributing to the strain. Therefore, equation (7) can be modified as follows ... 

Finally, we refer to work by Alloul (1979a, b) on zero-field NMR on Cu in CuMn alloys (Mn concentrations from 0.4% to 4.7%) at low temperatures T 0.2 T(, who finds no evidence for independent domain structure. The enhancement factor 7] of the rf-field and NMR signal intensity, associated with the rotation of domain magnetization, is found roughly proportional to the remanent magnetization and is negligible when the sample is ZFC. These results contradict the independent spin-cloud model, for which 17 should be independent of M. A similar conclusion has also been reached from the square hysteresis loops observed well below Tf in CwMn (Monod et al. 1979) and is corroborated by computer simulations of CwMn alloys (Walker and Walstedt 1980). 

The catalytic subunit then catalyzes the direct transfer of the 7-phosphate of ATP (visible as small beads at the end of ATP) to its peptide substrate. Catalysis takes place in the cleft between the two domains. Mutual orientation and position of these two lobes can be classified as either closed or open, for a review of the structures and function see e.g. [36]. The presented structure shows a closed conformation. Both the apoenzyme and the binary complex of the porcine C-subunit with di-iodinated inhibitor peptide represent the crystal structure in an open conformation [37] resulting from an overall rotation of the small lobe relative to the large lobe. 

Fig. 8. Principle of the magnetooptical read-out of domain patterns by the polar Kerr effect. The polarisation plane of the incoming laser beam is rotated clock- or counterclockwise according to the orientation (up or down) of the magnetic moments.

It generally is accepted that the mechanism of coercivity in the Alnicos is incoherent rotation of single-domain particles of the a -phase based on shape anisotropy. As coercivity increases, the larger the aspect ratio of the tods and the smoother thek surface becomes the difference between the saturation polarizations of the two phases also increases. It is thought that Ti increases the coercivity of Alnico because of an increased aspect ratio of the rods and a smoother surface. 

AppHcations of soHd-state nmr include measuring degrees of crystallinity, estimates of domain sizes and compatibiHty in mixed systems from relaxation time studies in the rotating frame, preferred orientation in Hquid crystalline domains, as weU as the opportunity to characterize samples for which suitable solvents are not available. This method is a primary tool in the study of high polymers, zeoHtes (see Molecular sieves), and other insoluble materials. 

The lattice parameters a and b become different during the transition from the tetragonal to the orthorhombic structure. Either a > b or a < b results, depending on the direction of the rotation of the octahedra strands. During the phase transition both directions of rotation occur at random domains appear, in which either a > b or a < b. The obtained crystal is a twinned crystal or twin, consisting of intergrown domains. The twin domains are... 

Ferroelasticity is the mechanical analogon to ferroelectricity. A crystal is ferroelastic if it exhibits two (or more) differently oriented states in the absence of mechanical strain, and if one of these states can be shifted to the other one by mechanical strain. CaCl2 offers an example (Fig. 4.1, p. 33). During the phase transition from the rutile type to the CaCl2 type, the octahedra can be rotated in one or the other direction. If either rotation takes place in different regions of the crystal, the crystal will consist of domains having the one or the other orientation. By exerting pressure all domains can be forced to adopt only one orientation. 

The estimated correlation times for the loop domains of the order of 10 4 s are obtained for the suppressed peaks in the [l-13C]amino-acid-labelled bR, including Gly, Ala, and Leu residues as shown in Figure 24C. The loop dynamics can be also examined by measurements of the 13C-1H dipolar couplings by DIPSHIFT experiment in which fluctuations of the Co,-Cp vector result in additional motional averaging as order parameters, in addition to the rotation of Ala methyl groups which scales the dipolar... 

Fig. 10 Shear deformation of a domain shown in Figs. 5 and 6 results in a rotation of the chain axes and in a relative displacement x of the chains, which is proportional to the shear angle or the shear strain 2(0-0)...

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