Intrinsic contributions

The intrinsic contribution, accounted for by the diene rule, seems to be easily outweighed by the perturbations arising from the allylic axial substituents, which in turn define the allylic axial chirality rule. This latter can be formulated in two ways The olefin-picture , where chirality is referred to the nearest double bond, and the diene-picture ,... 

A simplihed approach to the description of AV starts from the statement made by Hamann [270] that the partial molar volume of any dissolved species in solution is the sum of the intrinsic volume of the species, corresponding to its van der Waals radius (intrinsic contribution), and of the contribution due to interaction with the solvent and with the other dissolved species (environmental... 

Jenner [275] has presented a thorough description of several possible contributions to both the intrinsic and the environmental parts of the activation volumes, based on accurate experimental observation of pressure effect on reactions in solutions. The intrinsic contribution to the activation volume essentially derives from the differences in structure between the transition state and the reacting species, so it is directly related to the partial cleavage and formation of chemical bonds in the transition state. In cases where the environmental contribution is negligible, the activation volume variation gives a direct insight in the molecular mechanism [275, 280]. In this case in fact, considering... 

The negative VCD observed in dilute solution at the urethane C==0 stretching frequency, and the negative bias observed at higher concentrations is due to an intrinsic contribution from the urethane carbonyl stretch. In either the cis or trans conformation, the urethane C=0 stretch can generate current around an... 

To proceed further it is necessary to make some assumptions about the interrelations of the - G terms. Such assumptions will be extrathermodynamic in nature. It will be assumed that each Hi term can be split into an intrinsic contribution from the bare ion and a term from the solvation process. Thus... 

The total polarization of dielectric material results from all the contributions discussed above. The contributions from the lattice are called intrinsic contributions, in contrast to extrinsic contributions. 

Two types of contributions to dielectric and piezoelectric properties of ferroelectric ceramics are usually distinguished [6], [9-12], One type is called an intrinsic contribution, and it is due to the distortion of the crystal lattice under an applied electric field or a mechanical stress. The second type is called an extrinsic contribution, and it results from the motion of domain walls or domain switching [8], To provide an understanding of material properties of pzt, several methods to separate the intrinsic and extrinsic contributions were proposed. These methods are indirect, and are based on measurements of the dielectric and piezoelectric properties of ferroelectric ceramics [8], [10-12], In the experiments reported in this paper a different approach is adopted, which is based on measurements of high-resolution synchrotron X-ray powder diffraction. The shift in the positions of the diffraction peaks under applied electric field gives the intrinsic lattice deformation, whereas the domain switching can be calculated from the change in peak intensities [13,14],... 

The present work summarizes opportunities of using high-resolution synchrotron and standard xrd techniques for structural characterization as well as for investigations of structure-property-relationships. xrd will be used to determine quantitatively the phase content of morphotropic pzt. Temperature dependent measurements provide information about the phase transformation of morphotropic donor doped pzt ceramics and high-resolution synchrotron X-ray diffraction gives information about the extrinsic and intrinsic contributions to the electric field induced strain, xrd results are finally compared with electrical measurements to analyze the interactions among microstructure, phase content and properties. 

It is important to note that the form effect is proportional to the square of the dielectric contrast, Ae, and will always be positive for prolate particles (Ll > L2), and negative for oblate shapes (L2 > Lx). The intrinsic contribution can change sign depending on the relative magnitudes of the principal values of the polarizability tensor of the particle. 

As will be discussed in section 7.3, since the form contribution is proportional to r = R/ JW Ka instead of r2 (as is the case for the intrinsic contribution), this effect will... 

Values of the optical anisotropy F2 calculated from equation 3 are given in Table I. These values were resolved into an intrinsic contribution F2° =... 

On top of these intrinsic contributions to 17 there may be additional ones, like capillary suction (exerted on the ends of the film) and external fields such as gravity. 

For substitution reactions, the measured volume of activation, as obtained from equation (1), is usually considered to be the sum of an intrinsic contribution, resulting from changes in intemuclear distances within... 

The ability to reduce reorganization energies seems to be an important property of enzymes [29,2], For a given chemical reaction step, part of the energy barrier can be viewed as an intrinsic contribution that does not de-... 

The partial molar volume consists of a fairly large intrinsic contribution and a contribution due to solute-solvent interactions. The intrinsic part becomes zero or close to zero when partial molar... 

Reaction and activation volumes are in general considered to consist of solvational and intrinsic contributions that arise from changes in electros-triction and changes in bond lengths and angles during the chemical process, respectively. It follows from the above given relationships that a volume... 

Hi is called the intrinsic contribution to the chemical potential. Eqs. (36) and (37) are the most important in the applications of classical DFT to the theory of inhomogeneous fluids. We have discussed the formalism in terms of f(r), which is valid only for atomic fluids the extension to molecular fluids has been presented elsewhere [48]. 

---