Enhancing cation mobility

A second approach to promoting high cationic transport is to choose a molecular solvent which has the ability to interact with anions than cations. A number of electron deficient borates such as 

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ZEBRA 567 energy efficiency 15 enhancement factor, lithium alloys 367 enhancing cation mobility 518 enthalpy 9... 

The low frequency absorption II originates from the Maxwell-Wagner effect already observed in dehydrated X-type zeolites (8). In the presence of water the enhanced cationic mobility intensifies this effect. This interpretation disagrees with that of Matron et al. (10). They ascribed their low frequency a-process to cations on site I and site II. This is improbable in view of the correspondence with the Maxwell-Wagner effect in dehydrated X-type zeolites, observed by us (8). 

High cation mobility leading to enhanced diffusion and ionic conduction. 

Because the effect of neutralization by monovalent cations on the mechanical relaxations presents interesting features, it is also of interest to explore the effect of divalent cations. A preliminary study of this kind was conducted by Kyu and coworkers (58). Nafion acid of 1155 EW was neutralized with an appropriate BaCl2 solution to prepare a Ba-salt sample. The torsion pendulum results in the form of G, G" and tan 6 versus temperature are depicted in Figure 32. A peak is evident at approximately -90°C in the tan 6 and G" curves. Judging from the peak temperature, this y relaxation is probably caused by the same mechanism as in the acid and the monovalent salt samples described before. The 6 peak occurs at approximately -2O C and thus overlaps slightly with the y peak. The observation of the 6 region at such a low temperature may be due to the presence of residual water which would reduce ionic interactions within the ionic domains and in turn would enhance backbone mobility. 

Chromium (III) and Pu (III/IV) cations are sorbed to soil constituents and, thus, immobile in most aqueous and soil environments. On the other hand, Cr(VI) and Pu(VI) are quite mobile in soils and aqueous systems, because they are not sorbed by soil components to any extent. Therefore, in the hexavalent form, these elements are readily bioavailable (Amacher and Baker, 1982) and are of concern in food chain contamination. Chromium(III) and Pu(in/IV) can be oxidized to Cr(VI) and Pu(VI) by Mn(III/IV) oxides (Cleveland, 1970 Amacher and Baker, 1982). Manganese oxides can, thus, enhance the mobility and toxicity of Cr and Pu in soil and associated environments. 

These early papers already hint that two essential elements may play important roles in this reaction (i) oxygen vacancies, and the consequently enhanced oxygen mobility increased by the partial substitution of La by Sr (ii) the redox ability of the transition-metal cation. This subject was developed in more detail in the papers published afterwards. 

The influence of high-thermal treatment could be explained by the enhancement of iron cation mobility, which facilitated the introduction of iron cations into channels resulting in the formation of a-sites. The concentration and strength of protonic acidic sites significantly influences the rate of deactivation of Fe-ZSM-5 catalysts. 

In the present experiments, MTX markedly increased the tissue Ca content, Ca uptake, and intracellular free Ca concentration of smooth or cardiac mus cles. These Ca -mobilizing effects of MTX as well as its vasoconstrictive, cardio tonic, and cardiotoxic effects were profoundly suppressed or abolished by Ca entry blockers, polwalent cations, or Ca -free medium. It has been reported that MTX produces Ca -dependent excitatory effects on neuronal (10,11,18) or pituitary (26) cells and smooth (12,13), cardiac (14,15,17), or skeletal (16) muscles, and that all these actions of MTX were antagonized by Ca antagonists or polyvalent cations. These observations suggest that the enhanced Ca influx and the subsequent increase in cytoplasmic free Ca concentration play a dominant role in the excitatory effects of MTX. 

There are three broad categories of materials that have been utilized in this endeavor. In the first, even in fully stoichiometric compounds, the ionic conductivity is high enough to be useful in devices because the cation or anion substructure is mobile and behaves rather like a liquid phase trapped in the solid matrix. A second group have structural features such as open channels that allow easy ion transport. In the third group the ionic conductivity is low and must be increased by the addition of defects, typically impurities. These defects are responsible for the enhancement of ionic transport. 

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