Local distortions

Oil is fed to meshing zones by wide jets or sprayers, and uniform distribution across the tooth faces is necessary to avoid local distortion. Clearly, the rate of flow is important the effects of too little oil are easily imagined. A sound practice is to position an extra jet on the exit or disengagement side of a meshing zone, where the teeth are at their highest temperature. If gears run in either direction, sprayers must be installed on both sides. 

A cost-effective model concentrates on the smallest elements at areas of highest stress. This configuration provides greater detail in areas of major stress and distortion, and minimizes computer time in analyzing regions of the component where stresses and local distortions are smaller. 

Barton and coworkers have shown that proteins can in fact modulate the DNA electron transfer [168]. Methyltransferases are enzymes that recognize distinct DNA sequences, e.g., 5 -G CGC-3, and effect methylation by extrading the target base cytosine ( C) completely out of the DNA duplex while the remainder of the double helix is left intact. The methyltransferase Hha 1-DNA complex is a well-characterized example, revealing that the structure of the DNA is significantly but locally distorted [169,170]. In a recent study, Raj ski et al. used DNA duplex 20 containing the M.Hha I binding site between two oxidizable 5 -GG-3 sites [168] (Fig. 20). The duplex contains a complementary strand, selectively 5 -modified with a Rh intercalator that can function as a photooxidant. Upon... 

Various other interactions have been considered as the driving force for spin-state transitions such as the Jahn-Teller coupling between the d electrons and a local distortion [73], the coupling between the metal ion and an intramolecular distortion [74, 75, 76] or the coupling between the d electrons and the lattice strain [77, 78]. At present, based on the available experimental evidence, the contribution of these interactions cannot be definitely assessed. Moreover, all these models are mathematically rather ambitious and do not show the intuitively simple structure inherent in the effect of a variation of molecular volume considered here. Their discussion has to be deferred to a more specialized study. 

Fig. 8.16 Fe Mossbauer spectra of [Fe2 (PMAT)2](BF4)4-DMF at selected temperatures. At 298 K, the only quadrupole doublet is characteristic of iron(II) in the HS state. SCO from HS to LS occurs at one Fe(II) site of the dinuclear complex at ca. 225 K. The second Fe(II) site remains in the HS state, but feels the spin state conversion of the neighboring atom by local distortions communicated through the rigid bridging ligand, giving rise to a new quadrupole doublet (dark gray), i.e., HS in [HS-LS], in the Mossbauer spectrum. The intensity ratio of the resonance signals of HS in [HS-LS] to that of LS (black) in [HS-LS] is close to 1 1 at all temperatures (from [32])...

Fig. 9 Long-range oxidative damage in DNA is regulated by the structure of the DNA n-stack. Photoexcited [Rh(phi)2(bpy )]3+ intercalated within B-DNA oxidizes guanine doublets positioned 17 A and 40 A away with approximately equal efficiency. When a bulge is introduced in the DNA oxidation at the distal guanine doublet is inhibited. As shown by the NMR structure, bulges introduce local distortions in the DNA r-stack, although the kinking of the helical actually positions the distal guanine closer to the Rh(III) photooxidant...

Phase transitions of the PS-fo-PI system have been extensively studied. The morphological transition from the I phase to the G phase proceeds through nucleation and growth. The difference in the geometrical characteristics of these two phases induces considerable local distortion of both morphologies... 

In the real world the stress tensor never vanishes and so requires a nonvanishing curvature tensor under all circumstances. Alternatively, the concept of mass is strictly undefined in flat Minkowski space-time. Any mass point in Minkowski space disperses spontaneously, which means that it has a space-like rather than a time-like world line. In perfect analogy a mass point can be viewed as a local distortion of space-time. In euclidean space it can be smoothed away without leaving any trace, but not on a curved manifold. Mass generation therefore resembles distortion of a euclidean cover when spread across a non-euclidean surface. A given degree of curvature then corresponds to creation of a constant quantity of matter, or a constant measure of misfit between cover and surface, that cannot be smoothed away. Associated with the misfit (mass) a strain field appears in the curved surface. 

Kambara presented a ligand field theoretical model for SCO in transition metal compounds which is based on the Jahn-Teller coupling between the d-electrons and local distortion as the driving force for a spin transition [193]. The author applied this model also to interpret the effect of pressure on the ST behaviour in systems with gradual and abrupt transitions [194]. By considering the local molecular distortions dynamically this model turned out to be suited to account for cooperative interactions during the spin transition [195]. 

As discussed above, the Si(001) surface is reconstructed into dimers, a side view of which is shown in Fig. 7. In addition to the reconstruction of the surface atoms there is significant distortion of the subsurface region. This distortion blocks channels which enter into the bulk, and causes an excess of backscattered ions over what would be expected from atomic rows in the ideal crystal. This local distortion is the property monitored by backscattered ion intensities. The dimer pairs also tend to form in rows, which is the source of the (2 X 1) LEED pattern observed for this surface. 

Both of these are considered to arise from the different orientation of fer-roelastic domains below Ta and local distortion due to multidomaining. The inset in Fig. 13a shows An for the (llO)c face measured under three conditions (i) no electrode, (ii) with sputtered Au, and (iii) with pasted Ag. These results imply that even the sputtered Au on the 7 x 0.3 mm side can affect multidomaining below Ta. These results suggest that attention must be paid to ensure the single-domain state below Ta. 

This indicates that even in amorphous samples, in which the uniaxial Ki terms are expected to dominate due to the local distortions from cubic symmetry, there is still a significant contribution from the K4 cubic anisotropy terms. It is interesting to contrast this with the numerical simulations for a-TbFe2 which have shown that the fourth-order anisotropy eneigy per atom was an order of magnitude smaller than the second-order anisotropy energy per atom, albeit that the fourth-order term was of the same order of magnitude... 

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