Pb(II) cations have long been associated with lone-pairs which can help to enhance the optical anisotropic birefringence. In this paper, the contribution of lead cations to birefringence has been investigated using first-principles and real-space atom-cutting methods. The results show that the contribution of lead cations to birefringence is determined by the degree of stereochemical activity, ...

chemical nature, thermodynamic and kinetic properties of metal cations in aqueous solutions are described and discussed in terms of structural factors controlling physical properties of the systems. The structure of hydrated cations, reaction mechanism of water exchange on the cations, hydrolytic phenomena and acidity of the cations are presented. Correlations between coordination states of the...

Many large organic cations are potent blockers of K(+) channels and other cation-selective channels belonging to the P-region superfamily. However, the mechanism by which large hydrophobic cations enter and exit the narrow pores of these proteins is obscure. Previous work has shown that a conserved Lys residue in the DEKA locus of voltage-gated Na(+) channels is an important determinant of Na(+...

The substrate specificity of the avian renal organic cation exchanger was examined in isolated renal brush-border membrane vesicles. Endobiotic and xenobiotic organic cations (OCs) were tested at a concentration of 100 microM for cis-inhibition of 14C-tetraethylammonium (TEA)/H+ exchange and at 1 mM for trans-stimulation of 14C-TEA efflux. The xenobiotic cations amiloride, cimetidine, mepiperph...

We propose to detect isomorphisms of algebraic modular speci cations, by representing speci cations as diagrams over a category C0 of base speci cations and speci cation morphisms. We start with a formulation of modular speci cations as terms, which are interpreted as diagrams. This representation has the advantage of being more abstract, i.e. less dependent of one speci c construction than ter...

The properties of the cGMP-dependent channel present in membrane vesicles prepared from intact isolated bovine rod outer segments (ROS) were investigated with the optical probe neutral red. The binding of neutral red is sensitive to transport of cations across vesicular membranes by the effect of the translocated cations on the surface potential at the intravesicular membrane/water interface (S...