نتایج جستجو برای: alkali metal cations
تعداد نتایج: 230847 فیلتر نتایج به سال:
K+ is a competitive inhibitor of the uptake of the other alkali metal cations by yeast. Rb+ is a competitive inhibitor of K+ uptake, but Li+, Na+, and Cs+ act like H+. At relatively low concentrations they behave as apparent noncompetitive inhibitors of K+ transport, but the inhibition is incomplete. At higher concentrations they inhibit the remaining K+ transport competitively. Ca++ and Mg++ i...
We report a combined experimental and computational study of the whey protein β-lactoglobulin (BLG) in different electrolyte solutions. Vibrational sum-frequency generation (SFG) and ellipsometry were used to investigate the molecular structure of BLG modified air-water interfaces as a function of LiCl, NaCl, and KCl concentrations. Molecular dynamics (MD) simulations and thermodynamic integrat...
The shift with increasing concentration of alkali-metal cations of the potentials of both the spike and the hump observed in the cyclic voltammograms of Pt(111) electrodes in sulfuric acid solutions is shown to obey the simple model recently developed by us to explain the effect of non-covalent interactions at the electrical double layer. The results suggest that the model, originally developed...
Alkali metal compounds have been known since antiquity. In 1807, Sir Humphry Davy surprised everyone by electrolytically preparing (and naming) potassium and sodium metals. In 1808, he noted their interaction with ammonia, which, 100 years later, was attributed to solvated electrons. After 1960, pulse radiolysis of nearly any solvent produced solvated electrons, which became one of the most stu...
Macropolycyclic ligands containing appropriate binding sites and cavities of suitable size and shape, may be designed so as to display molecular recognition in the formation of selective inclusion complexes, cryptates, with metal cations, but also with anions and molecules. Macrobicyclic ligands B form highly stable and selective alkali and alkaline-earth cryptates, displaying a pronounced cryp...
A series of adamantane functionalized diaza-lariat ethers 1–6 have been prepared and alkali metal picrate extraction profiles determined. The ability of aza-crown ethers 1–6 to extract the alkali metal picrates was compared with that of diaza-18-crown-6 (7) and N,N '-dibenzodiaza-18-crown-6 (8). Na and K transport across bulk liquid membrane was also measured. The results of alkali metal cation...
Alkali metal cations can interact with Fe-N2 complexes, potentially enhancing back-bonding or influencing the geometry of the iron atom. These influences are relevant to large-scale N2 reduction by iron, such as in the FeMoco of nitrogenase and the alkali-promoted Haber-Bosch process. However, to our knowledge there have been no systematic studies of a large range of alkali metals regarding the...
The peptidocalixarenes 1–3 bearing tryptophan, phenylglycine and leucil units at the lower rim and their complexes with alkali-metal (Li, Na, K, Rb, Cs) and selected lanthanide cations (La, Ce, Eu, Yb) were analyzed by ESI MS. The influences of the solvent (acetonitrile, methanol, addition of formic acid or sodium acetate) and the calixarene:cation molar ratio on signal intensities were investi...
K(+) is a competitive inhibitor of the uptake of the other alkali metal cations by yeast. Rb(+) is a competitive inhibitor of K(+) uptake, but Li(+), Na(+), and Cs(+) act like H(+). At relatively low concentrations they behave as apparent noncompetitive inhibitors of K(+) transport, but the inhibition is incomplete. At higher concentrations they inhibit the remaining K(+) transport competitivel...
Cation-assisted interactions between N-containing heterocycles (NHCs) and CO2 have been systematically studied by using density functional theory (DFT). For neutral and anionic (non-carbenoid) NHCs, the effects of monovalent cations (i.e., alkali metal ions) are moderate to small (the NHC-CO2 binding energy change, ΔBE usually < 25 kJ mol(-1)). However, for NHC carbenes, due to their strong bas...
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