Potential pinned

Heller CM, Campbell IH, Smith DL, Barashkov NN, Ferraris JP (1997) Chemical potential pinning due to equilibrium electron transfer at metal/C o-doped polymer interfaces. J Appl Phys 81 3227... 

We now consider the formulation of the equations of motion for a rigid body pinned at its center of mass and acted on by a (possibly nonlinear) potential field. The Lagrangian in this case is... 

Table 11-2 shows the built-in potential in metal/MEH-PPV/metal structures measured by either electroabsorption [15] or photocurrenl techniques [37] for a variety of contact metals. The uncertainty in both the work function differences and the built-in potential measurements is about 0.1 eV. For all of the structures except the Pt-Ca and Al-Sm devices there is good agreement between the metal work function difference, AW, and the built-in potential, Vhi. This indicates that for a wide range of metal contacts the Schottky energy barrier between the metal and MEH-PPV is well approximated by the ideal Schottky model and that state chaiging, which pins the Schottky energy barrier, is not significant. A built-in potential smaller than the difference between the contact work functions implies that... 

The practice of molding inserts in place is usually employed to provide good holding power for plastic products, but there are drawbacks to this method. It normally takes a pin to support the insert, and since this pin is small in relation to the cored hole for the insert, it is easily bent or sheared under the influence of injection pressure. Should the insert fall out of position, there is danger of mold damage. Also, the hand placement of inserts contributes to cycle variation and with it potentially product quality degradation. Some of these problems can be overcome by higher mold expenditures,... 

Figure 5.46 shows clearly how the application of potential changes the brightness and thus the workfunction O, of the grounded Pt catalyst-electrode (windows 2 and 3) and of the YSZ surface, (window 1), in accordance to the above discussed alignment (pinning) of the two Fermi levels. 

Equation (7.32) underlines the pinning of the Fermi levels of metal electrodes with the solid electrolyte and reminds the fact that the absolute electrode potential is a property of the solid electrolyte and of the gaseous composition but not of the electrode material.21... 

Consequently the absolute potential is a material property which can be used to characterize solid electrolyte materials, several of which, as discussed in Chapter 11, are used increasingly in recent years as high surface area catalyst supports. This in turn implies that the Fermi level of dispersed metal catalysts supported on such carriers will be pinned to the Fermi level (or absolute potential) of the carrier (support). As discussed in Chapter 11 this is intimately related to the effect of metal-support interactions, which is of central importance in heterogeneous catalysis. 

By comparing Figure 11.9 and the characteristic Po2(Uwr) rate breaks of the inset of Fig. 11.9 one can assign to each support an equivalent potential Uwr value (Fig. 11.10). These values are plotted in Figure 11.11 vs the actual work function G>° measured via the Kelvin probe technique for the supports at po2-l atm and T=400°C. The measuring principle utilizing a Kelvin probe and the pinning of the Fermi levels of the support and of metal electrodes in contact with it has been discussed already in Chapter 7 in conjunction with the absolute potential scale of solid state electrochemistry.37... 

Following the approach similar to that of the atomic-scale model, the evolution of the system state and the lateral force on the asperity can be determined in terms of AUldrj = 0. If we chose V rj)= VQ cos ir rj) as the potential function for the repulsive and attractive pinning center, respectively, the lateral force F=-dy/d7 can be plotted as a function of the traveling distance p, as shown in Fig. 17. 

U-pin is most comparable to a six-ring hairpin polyamide, likely due to a loss of two hydrogen bond donors upon removal of the y-turn element. Thus, the dimeric Py-lm U-turn element may be thought of as a C,G-specific replacement for the y-tum (Fig. 3.4). In combination with removal of the /9-Ala tail (see below), H-pin and U-pin polyamides could potentially bind purely G,C sites, a sequence type that has been difficult to target with other polyamide motifs. 

Fig. 3.4 Polyamide-DNA binding motifs with equilibrium association constants K,). Hairpin amino-substitution at the a-position of the y-turn residue leads to enhanced binding affinity (10-fold) without loss of specificity, and with higher orientational selectivity and offers potential for further substitution. Cycle Cyclic polyamides show higher affinity than analogous hairpin molecules with the same number of cationic groups and eliminate all possibility of extended 1 1 binding. H-pin and U-pin compared to their non-linked analogs, H-pins and U-pins exhibit higher binding affinity. The black and open circles represent Im and Py rings, respectively diamonds repre-...

Degeneracy can be introduced not only by heavy doping, but also by high density of surface states in a semiconductor electrode (pinning of the Fermi level by surface states) or by polarizing a semiconductor electrode to extreme potentials, when the bands are bent into the Fermi level region. 

Chia We have looked at the potential phosphorylation sites of Insc, and this is the only apical complex component for which the functional domain has been defined. All the putative Cdc2 phosphorylation sites lie outside the region required for function (at least using an over-expression paradigm). For the other two known components, Baz and Pins, we don t know which the functional parts of the molecule are. It seems more appealing to think in terms of effects on the cytoskeleton, and in particular actin. 

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