Ion localization

Local anesthetics produce anesthesia by blocking nerve impulse conduction in sensory, as well as motor nerve, fibers. Nerve impulses are initiated by membrane depolarization, effected by the opening of a sodium ion channel and an influx of sodium ions. Local anesthetics act by inhibiting the channel s opening they bind to a receptor located in the channel s interior. The degree of blockage on an isolated nerve depends not only on the amount of dmg, but also on the rate of nerve stimulation (153—156). 

Stelzer R, Lehmann H. Recent developments in electron microscopical techniques for studying ion localization in plant cells. Plant Soil 1993 155 33-43. 

Hodson MJ. Ion localization and x-ray microanalysis, in Methods in Plant Cell Biology, Part A, (Galbraith DW, Bohnert HJ, Bourque DP, eds.), Academic Press, London. Methods Cell Biol 1995 49 21-31. 

Hajibagheri MA, Flowers TJ. Use of freeze-substitution and molecular distillation drying in the preparation of Dunaliella parva for ion localization studies by x-ray microanalysis. Microsc Res Technol 1993 24 395-399. 

Key words EPR, powder sample, g-factor, Cu2+ ion, local surrounding, ground state,... 

Answer. Assuming an ionic Zintl-Klemm model and the common oxidation state of these metals, we have C23- ions locally in the octahedral cavities formed from the... 

In some related ions localization is found, e.g., in 18-F-II, while in 18-F-III, which is unsymmetrical, the localization is such that Rum is at the pentammine end. 

The absence of HFS in the EPR spectrum of 10 min activated mixture points to the appearance of weak exchange interaction between V ions (localized centres), probably, through electron gas (delocalized electrons) - C-S-C relaxation [80,81]. 

Arylamines have a larger positive AG° for protonation and are therefore less basic than alkylamines, primarily because of resonance stabilization of their ground state. Electrostatic potential maps show that lone-pair electron density is delocalized in aniline compared to cyclohexylamine but that the corresponding ammonium ions localize charge in the same way. 

Fig. 5.29. Structure data of Fe-Sb metallic glasses 5.22]. Pure Sb is taken from [5.50], a) Structure factor b) pair-distribution function. Vertical lines in both figures indicate 2kF or rj, respectively. ZFe = 1 e/a was used for their calculation c) ion (local moment) positions vs. composition, compared with the position of minima in eff(r) and maxima of Jaf(r) calculated with ZFe = 1.0-1.1 e/a (thin solid curves). The thin dashed curve indicates a favourable antiferromagnetic position of local moments. The thin vertical lines in c) indicate approximately the composition where the Nagel-Tauc criterion is best fulfiled... 

Repair of the calcium gate/block due to diffusion occurs equally simply because of ionic depletion and competitive association. In particular, relaxation of the sodium or potassium ionic gradient in the vicinity of the open channel mouth quickly brings the levels of these ions locally to that of calcium. At that point, calcium competes effectively to bind to the phosphate. The system repairs to its resting state. The monovalent cations then can build up the concentration gradients observed through diffusion. 

In 2-17 compounds, the atoms located in the dumb-bell sites make a strong contribution to the anisotropy. These sites are preferentially occupied by the substituents when Co is partially replaced by other TM atoms, and this can even change the sign of 7C1, inducing EA behavior (Deportes et al. 1976). This effect has also been described in terms of a single-ion, local crystal-field model but certain results seem to require that band-structure changes also be considered (Perkins and Strassler 1977) i.e., that 3d-electrons be treated as collectivized. 

Under aerobic environments containing active IB and a significant amount of bicarbonate ions, localized corrosion on buried ductile cast iron was observed. 

Adsorption of H2 at 77 K on Li-LSX zeolite with DRIFT control of perturbation of adsorbed molecules has discriminated three different types of adsorption sites. Two of them were ascribed to H2 adsorption on Li ions localized in supercages of the zeolite framework at Sm and Sill sites, while the latter one most likely belongs to H2 adsorption on Li ions at Sn sites. Adsorption of N2 by Li ions at Sm and Sm sites is the strongest resulting in a decrease of intensity of the corresponding DRIFT bands from adsorbed H2. N2 dsorption by Li at Sn sites is very much weaker. 

This subclass of crystalline hydrates has its water localized in a two- dimensional order, or plane. Figure 18 shows the packing diagram for sodium ibuprofen, where the waters of hydration are associated with the sodium ions localized in the a-c plane of the lattice. A similar structure has been reported for nedocromil zinc [23]. In both cases the water is ion associated, but there is no obvious reason that such structures require this to be the case. In the case of nedocromil zinc, the long axis of the crystal is perpendicular to the hydration plane, and under crossed polarizing microscopic optics was observed to dehydrate... 

Research and development was mainly focnsed on the Ga-doped powders and thin ZnO film systems (Bourret-Courchesne et al. 2009, Choi et al. 2008, Derenzo et al. 2002, Ehrentraut et al. 2006, Makino et al. 2005, Neal et al. 2006, Yen et al. 2010) due to the aforementioned Ga-induced scintillation efficiency increase in the UV region and diminished reabsorption problem. An important improvement in the scintillation efficiency of the Ga-doped ZnO was reported recently (Bourret-Courchesne et al. 2007, 2009). Namely, when the annealing in an Ar-H2 atmosphere at a temperature of about 800°C is applied as the last step of the postpreparation treatment of the Zn-vacancy containing ZnO powder, the intensity of UV emission increases dramatically (Figure 4.5). The effect is interpreted as the UV radiative transition caused by the recombination of the Ga + donor-band electrons and the holes trapped at shallow acceptors. The latter are ascribed to H+ ions localized in Zn vacancies. 

---