Coupling factors

Piezocomposite ceramic can be tailored to our needs in contrast to conventional piezoceramic. The first parameter we can modify is the ceramic volume fraction. Fig. 2 indicates that the thickness coupling factor of the 1-3 composite is higher over a wide range of ceramic volume fraction between 15% and 95% than the coupling factor for PZT of about 0.52. Between 25% and 70% of volume fraction it is nearly constant at a high level of approximately 0.65. 

Fig. 2 Coupling factor as function of ceramic volume fraction...

Within this range we can modify the volume fraction without losses in the coupling factor and thereby can adjust the acoustic impedance to our demands. 

The contribution to the stress from electromechanical coupling is readily estimated from the constitutive relation [Eq. (4.2)]. Under conditions of uniaxial strain and field, and for an open circuit, we find that the elastic stiffness is increased by the multiplying factor (1 -i- K ) where the square of the electromechanical coupling factor for uniaxial strain, is a measure of the stiffening effect of the electric field. Values of for various materials are for x-cut quartz, 0.0008, for z-cut lithium niobate, 0.055 for y-cut lithium niobate, 0.074 for barium titanate ceramic, 0.5 and for PZT-5H ceramic, 0.75. These examples show that electromechanical coupling effects can be expected to vary from barely detectable to quite substantial. 

Aluminum nitride with a large piezoelectric coupling factor and a high surface acoustic wave velocity (5650 m/sec) (see Ch. 10). 

Younis, H.M., Boyer, J.S. Govindjee (1979). Conformation and activity ofchloro-plast coupling factor exposed to low chemical potential of water in cells. Biochimica et Biophysica Acta, 548, 328-40. 

Younis, H.M., Weber, G. Boyer, J.S. (1983). Activity and conformational changes in chloroplast coupling factor induced by ion binding Formation of a magnesium-enzyme-phosphate complex. Biochemistry, 22, 2505-12. 

Newgard CB, McGarry JD Metabolic coupling factors in pancreatic beta-cell signal transduction. Annu Rev Biochem 1995 64 689. 

To emphasize the coupling caused by intermediate Aj, the term coupling factor, Fg, was introduced by Medalia and defined as... 

In Pseudomonas putida, the hydroxylation of 4-hydroxyphenylacetate to 3,4-dihydroxy-phenylacetate is carried out by an enzyme that consists of a flavoprotein and a coupling factor (Arunachalam et al. 1992). At least in Escherichia coli, it has been suggested that the large component is an FADH2-utilizing monooxygenase (Xun and Sandvik 2000 Chaiyen et al. 2001). 

Adolfson, R., and Moudrianokis, E.N. (1976) Molecular polymorphism and mechanisms of activation and deactivation of the hydrolytic function of the coupling factor of oxidative phosphorylation. Biochemistry 15, 4164—4170. 

Baird, B.A., and Hammes, G.G. (1976) Chemical cross-linking studies of chloroplast coupling factor 1. J. Biol. Chem. 251, 6953-6962. 

Moroney, J.V., Wamcke, K., and McCarthy, R.F. (1982) The distance between thiol groups in the gamma subunit of coupling factor 1 influences the protein permeability of thylakoid membranes. J. Bioenerg. Biomembr. 14, 347. 

Vuckovic, J., Painter, O., Xu, Y., Yariv, A., and Scherer, A., 1999, Finite-difference time-domain calculation of the spontaneous emission coupling factor in optical microcavities, IEEE J. Quantum. Electron. 35(8) 1168- 1175. 

In Fig. 6.22 the results of a viscosity scahng by f— fxT/rj (T) of the relaxation data are shown. Such a scaling is motivated by the Rouse model and should hold for the a-relaxation. The pure PPO data (right) behave according to this expectation in contrast the PP0-IiC104 curves deviate considerably. This indicates that the coupling factor between microscopic friction and viscosity depends on temperature, possibly due to transient cross-linking via Li-ions. 

Since the values of i/ depend on several factors noted above, in the absence of additional data such as the temperature dependence of the electron transfer rate constants for i-2 it is difficult to analyze the apparent difference between i/ for the charge separation reaction and that of the radical ion pair recombination reaction. However, the difference between these two values of u is not unreasonable given that the charge separation involves oxidation of an excited state of the donor, while radical ion pair recombination involves two ground state radicals. Small changes in the nuclear coordinates of the donor and acceptor for these two reactions should be sufficient to produce the observed difference in i/. The electronic coupling factor between ZnTPP and AQ should be different than that between ZnTPP " and AQ". 

Fig. 11. A pictorial representation of the mitochondrial ATP synthesizing coupling factor interacting with the mitochondrial membrane. F, contains five polypeptide chains a, (3, 7, 8, and e and is readily solubilized. The stalk is probably made up of three polypeptide chains, 8, OSCP, and Ffi, which interact with a small group of hydrophobic polypeptides, CF0, embedded in the membrane.

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