Cation shifts

Figure 11-6 defines the transport problem in a quasi-binary ionic system (A,B)X with a miscibility gap, if both chemical (V/i,) and electrical (Vp) driving forces act simultaneously (case 3)). If the chemical force is negligible, we are dealing with case 2) and the electrical drift flux of the cations shifts the boundary b in the direction of the flux. We can conclude that, in agreement with Figure 11-5 a, the boundary morphology is unstable if... 

These changes in the chemical shifts recall those caused by complex formation with paramagnetic cations (shift reagents) and are being studied. 

Fig. 21 a-c Crystal structure of Yb2 75C60 [76]. a Undistorted/cc structure of Yb3C60. The arrow indicates that 1/8 of tetrahedral cations is missing, b The doubled supercell of Yb2.75C6o, caused by the ordering of the tetrahedral vacancy. The octahedral cations are shifted towards the vacant tetrahedral site, c The vacancy and octahedral cation shift induce orientational order and distortion of C60 molecules. There are three inequivalent C60 molecules in the lattice... 

ATP depletion, cation shifts and oxygen-derived free radical injury Site of renal ischemia-reperfusion injury A link between proximal and distal tubular injury and recovery Tubuloglomerular feedback and autoregulation Endothelin in ischemia-reperfusion injury Treatment of ischemic acute kidney injury Nephrotoxic injury Cyclosporine... 

ATP depletion, cation shifts and oxygen-derived free radical injury... 

Stability constants for [Ln(dotp)] complexes have been determined log K ranges from 27.6 (La) to 29.6 (Lu) (dotp = 1,4,7,10-tetraazaccyclododecane-l,4,7,10-tetrakis(methylenephosphonic acid). In view of its use as a cation-shift reagent, it is notable that Na-NMR studies show NH4+ and K+ compete effectively with Na" " for the binding sites on [Tm(dotp)] . Ca " " and Mg also complex with [Tm(dotp)]. ... 

The plane of basal oxygen atoms approaches the tetrahedral cation in flattened tetrahedra (the distance between the tetrahedral cation and the basal oxygen-atom plane decreases with respect to the T-Oapkai distance), whereas the tetrahedral cation shifts toward the tetrahedral apex (the distance between the tetrahedral cation and basal-oxygen atom plane increases with respect to the T-Oapkai distance) in elongated tetrahedra. In preiswerkite and in boromuscovite the tetrahedral cation shifts from its ideal position toward the plane of basal oxygen atoms (x < 109.47°). In the brittle mica clintonite, the tetrahedral cation more closely approaches the center of the tetrahedron (x <= 109.47°), whereas in other micas the cation shifts toward the tetrahedral apex (x > 109.47°). The maximum shift was observed in norrishite (Tyrna and Guggenheim 1991) and in polylithionite (Takeda and Burnham 1969). 

Thus, for a regular tetrahedron Tdisp. is zero. If the tetrahedral cation shifts from the center of mass of the tetrahedron Tdisp. differs from zero and relates to the modulus of the shift. 

The polarographic half-wave potentials of dissolved cations shift in the more negative direction with an increase in the stabilities of the complexes, including solvate complexes, whereas with anions stronger solvation results in a shift of the half-wave potential in the more positive direction [Ko 57]. However, the comparison of half-wave potentials measured in different solvents is accompanied by extreme difficulties because of the large solvent dependence of the potential of the reference electrode [Sc 55]. 

However. (CHj)4N- - silicate solutions differ from the sodium silicate solutions in that even at 1.0 ratio, colloid still persists along with HSiOj". Likewise, in 3.3 ratio solutions, there is much more colloid in the (CH3)4N based solutions than with sodium base. The authors conclude that TMA cation shifts the equilibrium to a mixture of low and high species. It is likely that the colloid phase is stabilized by an adsorbed monolayer of (CH3)4N . 

The carbocation (53), formed under super-acid conditions from the phenyl-substituted tetracyclic alcohol (50), appears to be destabilized relative to (52), formed from (49) under similar conditions. Thus, for example, (53) could only be formed from (50) in FSO3H-SO2CIF at below — 100 "C, whereas (52) can be studied at — 50 °C. Above that temperature rearrangement occurs to give a pair of bicyclo-[3,3,0]octyl allylic cations. Shift data on (53) indicate that the methyl-bearing carbon aioms at the base of the pyramid are more electron deficient than their counterparts... 

The distortions are much more pronounced than in the superstructures of IT—TaS2, the cation shifts being almost an order of magnitude larger. In TaTe2, the originally equivalent distances become Tai—Tai=h = 3.65A, Tai—Tan = 3.32 A, Tan—Tan = 4.51 A. The shortened metal-metal distances as emphasized... 

Table 2 Shift reagents for alkali metal cations Shift reagent Acid anion [Dy(PPP)2] Tripolyphosphate...

If the electrolyte contains an ion specifically adsorbed, the intersection point of the ao = f (pH) curves shifts and no longer represents the PZC determined with indifferent , or non-specifically adsorbed ions. Specific adsorption of cations shifts the intersection towards lower pH anions shift it towards higher pH. For example,... 

Next, we compare l-butyl-3-methylimidazolium [BMIm] based ILs with a series of hexafluoropnictogenate anions ([XFa]" X is P, As, or Sb) (Shirota et al., 2009). As discussed above, the substitution of C by Si in the cation shifts the first moment of the low-frequency spectrum of an IL to a lower value. However, a change in the dipole moment of an ion caused by atom substitution gives a difference in the spectra. Because the hexafluoropnictogenate anion is octahedral, the substitution of a center atom affects the mass and volume (mean polarizability) of the ion, but does not affect the shape (dipole moment and polarizability anisotropy). Thus, it is more ideal to simply examine the atom substitution effects caused by the mass and volume on the interionic vibration in the ILs. 

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