Current developments [ 4 ] of thermometers operating below a few micrometers and with high spatial resolution include: Ga-fi lled carbon/MnO nanotubes, [ 2 ] temperature-dependent conformation modifi cations of molecular spring superstructures, [ 3 ] Raman [ 10 ] and infrared [ 11 ] spectroscopic probing, scanning thermal microscopy probes, [ 6 ] and luminescence-based measurements. [ 5–9 , 12–...

in the present work a ph-dependent cloud point extraction procedure using ph-sensitive hydrogel polymer was applied for preconcentration and spectrophotometric determination of the hg(ii) as its thio micher's ketone complex. central composite design (ccd) and response surface method were applied to design the experiments and find out the optimum conditions. four factors entitled concentration o...

Inhibition by polyvalent cations is a defining characteristic of voltage-gated proton channels. The mechanism of this inhibition was studied in rat alveolar epithelial cells using tight-seal voltage clamp techniques. Metal concentrations were corrected for measured binding to buffers. Externally applied ZnCl 2 reduced the H 1 current, shifted the voltage-activation curve toward positive potenti...

AB STRACT The effects of external Zn+2 and other divalent cations on K channels in squid giant axons were studied. At low concentration (2 mM) Zn+2 slows opening kinetics without affecting closing kinetics . Higher concentrations (5-40 mM) progressively slow opening and speed channel closing to a lesser degree. In terms of "shifts," opening kinetics are strongly shifted to the right on the volt...

The antiaromaticity of fluorenyl cations is dependent on the magnitude of the charge of the system. Theoretical assessments of antiaromaticity and charge were supported by experimental NMR chemical shifts. Delocalization was related to antiaromaticity, and evaluated through the standard deviation of the charges on carbons of the fluorenyl systems.

Kir channels display voltage-dependent block by cytosolic cations such as Mg2+ and polyamines that causes inward rectification. In fact, cations can regulate K channel activity from both the extracellular and intracellular sides. Previous studies have provided insight into the up-regulation of Kir channel activity by extracellular K+ concentration. In contrast, extracellular Mg2+ has been found...

We report the isolation of a mutant of the cellular slime mold Dictyostelium discoideum that is highly resistant to the lethal action of the nonionic detergent Triton X-100. The resistance is completely dependent on the presence of divalent cations, of which Ca2+ is the most effective.

Background Cl channels in neurons and skeletal muscle are significantly permeable for alkali cations when tested with asymmetrical concentrations of the same salt. Both anion and cation permeation were proposed to require binding of an alkali cation with the pore (Franciolini, F., and W. Nonner. 1987. Journal of General Physiology. 90:453-478). We tested this hypothesis by bilaterally substitut...