Potential plateau

The potential plateau (pitting potential) is said to be insensitive to pH changes in the medium-pH region.67 This is in line with the model suggesting the accumulation of hydrogen ions at the O/S interface to very high concentrations, when the very small initial concentration (at pH above 2) becomes irrelevant. 

When aluminum is anodically dissolved in halide solutions, the rate of hydrogen evolution linearly increases with increasing current density as shown in Fig. 25. This phenomenon is historically, and somewhat misleadingly, termed the negative difference effect 124 (NDE). It is contrary to what one would normally expect, for hydrogen evolution should subside with the potential going positive (as indeed is observed in alkaline solutions) or at least stay constant at a constant-potential plateau. 

In nonalloyed metal, impurities affect the OCP and the corrosion behavior, while they have little effect on the potential plateau of active dissolution. 

Coulombic efficiency in the first charging cycle comparable to that of the commercial electrolytes for lithium ion cells.The potential plateau at 0.80 V, characteristic of the reductive decomposition of PC, was completely eliminated due to the presence of ClEC, while a new process was observed at 1.70 V. When taking the irreversible capacity in the first cycle as a metric, the optimum concentration of ClEC was determined to be 30 vol although in a... 

Termination of phase 2 of the action potential plateau occurs when time-dependent, voltage-dependent, and intracellular Ca++-dependent inactivation of Ica results in the unopposed repolarizing effects of the outward K+ currents. The combination of these effects results in rapid repolarization with a return to the hyperpolarized resting membrane potential. Pharmacological interventions that inhibit Ik prolong the membrane action potential by de-... 

Most calcium channels become activated and inactivated in what appears to be the same way as sodium channels, but in the case of the most common type of cardiac calcium channel (the "L" type), the transitions occur more slowly and at more positive potentials. The action potential plateau (phases 1 and 2) reflects the turning off of most of the sodium current, the waxing and waning of calcium current, and the slow development of a repolarizing potassium current. 

The potential programme used for this electrolysis consists in a potential plateau at 1.18 V/RHE during 30 s followed by a rapid triangular sweep, between 0 and 1.8 V/RHE at 500 mV s 1 (see insert in Fig.l). Recording of the intensity vs. potential curves i(E), the so-called voltammograms, allows us to follow qualitatively the evolution of the solution composition with time (Fig.l). 

Fig. 1. Evolution of the voltammograms of a platinum electrode recorded during the prolonged electrolysis of glyoxal at a potential plateau Ep=1.18 V/RHE. The main oxidation peaks are labelled A, B and C. The potential programme is shown in the insert. Time of electrolysis (—) 0 hr, (.) 25 hrs, (---) 50 hrs.

Figure 5.9a compares the experimental E versus (1 -f 5) dependencies (open and closed circles) and the curve calculated by the Monte Carlo method (solid line), taking /, - 0.110. J. - OS, /, 0.005, E = 1.777, and e, = 1.677 eV at T = 298 K for Lil + olTis/sLii/ijOi. The theoretical curve shows a wide potential plateau in the range of (1 -F 5) = 1.06 1.94, which coincides well with the experimental data. Figure 5.9a also shows that the theoretically calculated lithium content in the 8(a) sites, (1 -F 8)8(a), decreases with increasing (1 + 8) in the potential plateau region, whereas lithium content in the 16(c) sites (1 + 8)i6(c) increases. 

When elevated concentrations of calcium inhibitory compounds are used, the plateau phase of the action potential is dramatically abbreviated resulting in reductions in action potential duration during all phases of repolarization. Depending upon the cardiac fiber type (Purkinje fiber or ventricular muscle) and concentration of the calcium inhibitory compound under investigation, quantitative and qualitative changes in action potential plateau and repolarization are to be expected, although contractile force is invariably reduced. 

V/RHE and held 15 s.The third potential pulse was fixed at 1.6 V/RHE, during 0.5 s, allowing to reactivate the electrode by clearing out the poisoning species formed during the potential plateau. The oxidation products detected during this electrolysis and their chemical yield are represented in table 2 ... 

The changes in the equilibrium phase with lithium content are given in Eigures l(a)-(e). Specifically, two different phases coexist in the lithium content range where the potential plateau appears. For the details about the chemical and physical properties of the equilibrium... 

Similarly to the case of Lin-g[Ti5/3Li /3]04, the (quasi-) current plateau appears in the CTs obtained with other intercalation compounds as well. For instance, the logarithmic cathodic CTs (Figure 7a) obtained with a LisV20j electrode show a single current plateau in the same manner as the curves obtained with Lii+8[Ti5/3Lii/3]04, at the potential drops from 3.45 to 3.35, 3.45 to 3.30, and 3.45 to 3.25 V vs. Li/cC, which passed only through one potential plateau at 3.40 V v. LifLi. On the other hand, the CTs for the potential drops from 3.45 to 3.20 and 3.45 to 3.15 V v. Li/Li", which involve the effect of two potential plateaus at 3.40 and 3.21 V s. Li/Li, are characterized by double (quasi-) current plateaus. 

In the case of Li5V20s, the current plateaus are not so clear as those in Lii+g[Ti5/3Lii/3]04. The most plausible reason for this deviation from an ideal current plateau is the combined effect of the relatively narrow potential plateau region and the size distribution of the oxide particles, which makes the onset/end time of the phase transformation quite ambiguous. 

The intact interface is characterized by an anodic potential plateau. This plateau results from the high electronic conductivity of the oxide-covered iron sur-... 

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