Y-process

Other results are that the strength of the y process is too small to reach a strong conclusion about phase origin from this decriptor. However tan 5max is consistent with amorphous origin. Very interestingly, the a process... 

For example, let us consider that Y contains (or can create) a product Q which binds, signals, to informs and regulates a catalyst, E, of the overall X — Y process (Figure 3.12) but is not engaged in the process itself. The X — Y reaction can then be enhanced or inhibited by this reaction. While Q could be an enhancer or inhibitor of... 

Rate of change /Input variable — Output variable output variable J y Process time constant... 

Relaxation dispersion data for water on Cab-O-Sil, which is a monodis-perse silica fine particulate, are shown in Fig. 2 (45). The data are analyzed in terms of the model summarized schematically in Fig. 3. The y process characterizes the high frequency local motions of the liquid in the surface phase and defines the high field relaxation dispersion. There is little field dependence because the local motions are rapid. The p process defines the power-law region of the relaxation dispersion in this model and characterizes the molecular reorientations mediated by translational displacements on the length scale of the order of the monomer size, or the particle size. The a process represents averaging of molecular orientations by translational displacements on the order of the particle cluster size, which is limited to the long time or low frequency end by exchange with bulk or free water. This model has been discussed in a number of contexts and extended studies have been conducted (34,41,43). 

Fig. 3. Schematic representation of the topological space of hydration water in silica fine-particle cluster (45). The processes responsible for the water spin-lattice relaxation behavior are restricted rotational diffusion about an axis normal to the local surface (y process), reorientations mediated by translational displacements on the length scale of a monomer (P process), reorientations mediated by translational displacements in the length scale of the clusters (a process), and exchange with free water as a cutoff limit.

The determination of whether the multiple exchange occurs by an a-a, a-/3, or a-y process is obviously an important step in the elucidation of the mechanism. Careful examination of the initial distributions of products can be most useful both in this connection and in providing evidence about the types of adsorbed species responsible for the exchange reaction. This examination may be carried out in two ways, either (a) the comparison... 

Fig. 32 shows the effect of varying the frequency. In this case the secondary mechanical y process normally considered characteristic of a chain containing four or more methylenes is clearly visible. 

In Equation 1, R and V refer to the relaxed (low frequency) and unrelaxed (high frequency) dielectric constants, and AH is the measured activation energy for the y process. The latter was nearly independent of blend composition an average value of 8.7 kcal/mole was used. The integral in Equation 1 was found to be approximately independent of frequency in the range studied. The loss peak in absolute terms is rather weak, and values of eR — V were of the order of 10"2 and less. From these values, it was also possible to calculate the apparent dipolar density, Np2, using the Onsager relation (9) ... 

Fig. 2.56 Arrhenius plots for the a dielectric relaxation of ( ) P24DFBM, ( ) P25DFBM and (o) P26DFBM and the y processes of (o) P24DFBM, and ( ) P26DFBM.

Zhang, Z., Gekhtman, D., Dresselhaus, M. S., and Ying, J. Y., Processing and characterization of single-crystalline ultrafine bismuth nanowires. Chem. Mater. 11,1659 (1999). 

Given a method of preparing Mo organometallic compounds, the p decay transformation of Mo to Tc could be studied. The decay of Mo to Tc yields a nuclide with much lower recoil energy than that formed in the molybdenum (n, y ) process. However, this decay produces a cascade of Auger electrons see Auger Spectroscopy) which can cause bond disruption. These studies are difficult, because the technetium-99m product is produced at radiochemical tracer levels. Macroscopic quantities of products are not available for spectroscopic characterization. 

Eguchi, K., Akasaka, N., Mitsuyasu, H., and Nonaka, Y., Process of solid state reaction between doped ceria and zirconia, Solid State Ionics, 2000, 135, 589-594. 

Brakch, N., Rist, B., Beck-Sickinger, A. G., et al. (1997) Role of prohormone convertases in pro-neuropeptide Y processing coexpression and in vitro kinetic investigations. Biochemistry 36, 16,309-16,320. 

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