Cation-Transport Properties

The mobility of lithium ions in cells based on cation intercalation reactions is clearly a crucial factor in terms of fast and/or deep discharge, energy density, and 

1 and 6 1. Solid symbols represent experimental data after subtraction of the spectrum corresponding to the pure polymer. Solid curves represent a three-component fit. Broken curves represent the individual fitted components, (b) Relative Raman intensities 

For a fully dissociated salt, all techniques should give the same values of transport number, t. Transference number measurements are appropriate for electrolytes containing associated species, and any technique within one of the three groups wiU give a similar response, but values of across the groups may vary. 

Name Polymer matrix Concentration range G/ti References 

For DC polarization studies, the ratio of steady-state to initial current is not the transport number but determines the limiting current fraction, the maximum fraction of the initial current which may be maintained at steady-state (in the absence of interfractional resistances). Variations observed in this parameter with salt concentration and temperature must result from changes in the state of the electrolyte and are compatible with changes in ionic species contributing to the steady-state current. These may include mobile neutral species [73]. 

Of all the techniques, it is those of Group 1 that are likely to give the most realistic data, simply because they measure transport of charged species only. They are not the easiest experimental techniques to perform on polymeric systems and this probably explains why so few studies have been undertaken. The experimental difficulties associated with the Tubandt-Hittorf method are in maintaining nonadherent thin-film compartments. One way is to use crosslinked films [79], while an alternative has been to use a redesigned Hittorf cell [80]. Although very succesful experimentally, the latter has analytical problems. Likewise, emf measurements can be performed with relative ease [81, 82] it is the necessary determination of activity coefficients that is difficult. 

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VI. Correlation of Thermodynamic Stability with Cation Transport Properties. 183... 

In all, the question of which process is rate limiting in atmospheric corrosion depends on many factors, including metal ion and cation transport properties through the corrosion products, and the access of oxygen through the aqueous phase. 

Table 2 also shows that thiophene-bearing crown ether fi is an excellent carrier for Pb ion. The replacement of oxygen atoms in the carrier 4 by sulfug atoms in the carrier decreased transport rates for hard and Ba ions, but offered fast transport of soft Pb ion. Since the coordination character of the pendant donor group clearly reflected on the cation transport properties, further modifications of "arm" donor groups may offer new and unique transport selectivities. 

A certain crown ether having additional coordination sites for a trasition metal cation (71) changes the transport property for alkali metal cations when it complexes with the transition metal cation 76) (Fig. 13). The fact that a carrier can be developed which has a reversible complexation property for a transition metal cation strongly suggests that this type of ionophore can be applied to the active transport system. 

Nerve growth factor snake venoms zinc, 6, 613 Neurospora crassa calcium transport, 6, 571 cation transport, 6, 559 Neurosporin, 6, 676 Neurotransmitters secretion calcium, 6, 595 Neutral complexes electrical properties, 6, 143 Neutron absorbers... 

The effect of highly polarizable cations on transport properties has scarcely been studied. Since the nitrate melts of Ag and TL are stable and have high polarizabilities, as shown in Table 5, their internal mobilities in binary mixtures containing one or both of these cations have been measured frequently. The isotherms are shown for and m,., in Figs. 10 and 11,... 

The primary conclusion that follows from the effect of base sequence on the efficiency of radical cation migration through duplex DNA is that base pairs cannot be considered in isolation. For example, the effect of placing a T in a sequence of purines depends critically on the nature and number of purines. In this regard, the effect of base sequence on radical cation transport emerges from examination of collective properties of the DNA. This is a clear indication that the charge is delocalized over several base pairs, a conclusion that is supported by extensive quantum calculations. 

Busch, A. E., et al. Electrogenic properties and substrate specificity of the polyspecific rat cation transporter rOCTl. /. Biol. Chem. 1996, 271, 32599-32604. 

The transport behavior of Li+ across membranes has been the focus of numerous studies, the bulk of which have concentrated upon the human erythrocyte for which the Li+ transport pathways have been elucidated and are summarized below. The movement of Li+ across cell membranes is mediated by transport systems which normally transport other ions, therefore the normal intracellular and subcellular electrolyte balance is likely to be disturbed by this extra cation. Additionally, Li+ has been shown to increase membrane phospholipid unsaturation in rat brain, leading to enhanced fluidity in the membrane, which could have repercussions for membrane-associated proteins and for membrane transport properties. 

Weber WJ, Griffin CW, and Bates JL. Effects of cation substitution on electrical and thermal transport properties of Y0rO3 and LaCr03. J. Am. Ceram. Soc. 1987 70 265-270. 

We shall briefly discuss the electrical properties of the metal oxides. Thermal conductivity, electrical conductivity, the Seebeck effect, and the Hall effect are some of the electron transport properties of solids that characterize the nature of the charge carriers. On the basis of electrical properties, the solid materials may be classified into metals, semiconductors, and insulators as shown in Figure 2.1. The range of electronic structures of oxides is very wide and hence they can be classified into two categories, nontransition metal oxides and transition metal oxides. In nontransition metal oxides, the cation valence orbitals are of s or p type, whereas the cation valence orbitals are of d type in transition metal oxides. A useful starting point in describing the structures of the metal oxides is the ionic model.5 Ionic crystals are formed between highly electropositive... 

If the membrane has cation exchange properties the transport t will be functions of concentration. In fact... 

As has already been pointed out, the solubility properties of the anion, its lipophilicity, are extremely important for the dissolution of the complex in solvents of low polarity. Large and soft inorganic and, much more so, organic anions very strongly increase the solubility. Anion activation and cation transport processes both depend on such anion effects. 

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