The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform
Fumio Kukita - One of the best experts on this subject based on the ideXlab platform.
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K^+ Channels of Squid Giant Axons Open by an Osmotic Stress in Hypertonic Solutions Containing Nonelectrolytes
The Journal of Membrane Biology, 2011Co-Authors: Fumio KukitaAbstract:In hypertonic solutions made by adding Nonelectrolytes, K^+ channels of squid giant axons opened at usual asymmetrical K^+ concentrations in two different time courses; an initial instantaneous activation ( I _IN) and a sigmoidal activation typical of a delayed rectifier K^+ channel ( I _D). The current–voltage relation curve for I _IN was fitted well with Goldman equation described with a periaxonal K^+ concentration at the membrane potential above −10 mV. Using the activation–voltage curve obtained from tail currents, K^+ channels for I _IN are confirmed to activate at the membrane potential that is lower by 50 mV than those for I _D. Both I _IN and I _D closed similarly at the holding potential below −100 mV. The logarithm of I _IN/ I _D was linearly related with the osmolarity for various Nonelectrolytes. Solute inaccessible volumes obtained from the slope increased with the nonelectrolyte size from 15 to 85 water molecules. K^+ channels representing I _D were blocked by open channel blocker tetra-butyl ammonium (TBA) more efficiently than in the absence of I _IN, which was explained by the mechanism that K^+ channels for I _D were first converted to those for I _IN by the osmotic pressure and then blocked. So K^+ channels for I _IN were suggested to be derived from the delayed rectifier K^+ channels. Therefore, the osmotic pressure is suggested to exert delayed-rectifier K^+ channels to open in shrinking rather hydrophilic flexible parts outside the pore than the pore itself, which is compatible with the recent structure of open K^+ channel pore.
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k channels of squid giant axons open by an osmotic stress in hypertonic solutions containing Nonelectrolytes
The Journal of Membrane Biology, 2011Co-Authors: Fumio KukitaAbstract:In hypertonic solutions made by adding Nonelectrolytes, K+ channels of squid giant axons opened at usual asymmetrical K+ concentrations in two different time courses; an initial instantaneous activation (I IN) and a sigmoidal activation typical of a delayed rectifier K+ channel (I D). The current–voltage relation curve for I IN was fitted well with Goldman equation described with a periaxonal K+ concentration at the membrane potential above −10 mV. Using the activation–voltage curve obtained from tail currents, K+ channels for I IN are confirmed to activate at the membrane potential that is lower by 50 mV than those for I D. Both I IN and I D closed similarly at the holding potential below −100 mV. The logarithm of I IN/I D was linearly related with the osmolarity for various Nonelectrolytes. Solute inaccessible volumes obtained from the slope increased with the nonelectrolyte size from 15 to 85 water molecules. K+ channels representing I D were blocked by open channel blocker tetra-butyl ammonium (TBA) more efficiently than in the absence of I IN, which was explained by the mechanism that K+ channels for I D were first converted to those for I IN by the osmotic pressure and then blocked. So K+ channels for I IN were suggested to be derived from the delayed rectifier K+ channels. Therefore, the osmotic pressure is suggested to exert delayed-rectifier K+ channels to open in shrinking rather hydrophilic flexible parts outside the pore than the pore itself, which is compatible with the recent structure of open K+ channel pore.
Yuan H Zhao - One of the best experts on this subject based on the ideXlab platform.
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characterisation of the water o nitrophenyl octyl ether system in terms of the partition of Nonelectrolytes and of ions
Physical Chemistry Chemical Physics, 2005Co-Authors: Michael H. Abraham, Yuan H ZhaoAbstract:The Abraham linear free energy relationship, or solvation equation, has been applied to literature data on the partition of Nonelectrolytes in the water to o-nitrophenyl octyl ether (NPOE) system. The resulting equation is compared to equations for other water to solvent systems using the D-parameter of Abraham and Martins and the θ-parameter of Ishihama and Asakawa. It is shown that as a solvent in partitioning systems, NPOE quite resembles nitrobenzene and 1,2-dichloroethane, and that the latter does not resemble an alkane-like solvent. Using descriptors for simple ions that we have previously obtained, we show that ions and Nonelectrolytes can be included in the same linear free energy relationship.
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Characterisation of the water/o-nitrophenyl octyl ether system in terms of the partition of Nonelectrolytes and of ions.
Physical chemistry chemical physics : PCCP, 2005Co-Authors: Michael H. Abraham, Yuan H ZhaoAbstract:The Abraham linear free energy relationship, or solvation equation, has been applied to literature data on the partition of Nonelectrolytes in the water to o-nitrophenyl octyl ether (NPOE) system. The resulting equation is compared to equations for other water to solvent systems using the D-parameter of Abraham and Martins and the theta-parameter of Ishihama and Asakawa. It is shown that as a solvent in partitioning systems, NPOE quite resembles nitrobenzene and 1,2-dichloroethane, and that the latter does not resemble an alkane-like solvent. Using descriptors for simple ions that we have previously obtained, we show that ions and Nonelectrolytes can be included in the same linear free energy relationship.
Zhichang Wang - One of the best experts on this subject based on the ideXlab platform.
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relationship among the raoult law zdanovskii stokes robinson rule and two extended zdanovskii stokes robinson rules of wang
Journal of Chemical & Engineering Data, 2009Co-Authors: Zhichang WangAbstract:In this paper, the Raoult law (C. R. Acad. Sci. Ser. C 1887, 104, 1430), the Zdanovskii−Stokes−Robinson (ZSR) rule (Trudy Solyanoi Laboratorii Akad. Nauk SSSR 1936, No. 6, 5; J. Phys. Chem. 1966, 70, 2126), and two extended ZSR rules of Wang (Acta Metall. Sinica 1980, 16, 195; Ber. Bunsen-Ges. Phys. Chem. 1998, 102, 1045) are presented in a unified way. Similar to the Raoult law, which was first noted empirically in pyridine solutions, the ZSR rule for isopiestic mixed electrolyte and nonelectrolyte aqueous solutions can be extended to every kind of liquid and solid solutions such as organic mixtures, aqueous and nonaqueous electrolyte and nonelectrolyte solutions, liquid and solid alloys, molten salt mixtures, slags, and nonstoichiometric solid solutions, resulting in two extended ZSR rules of Wang. Although the solutions obeying the Raoult law (or the related classically ideal solution model) are very few as compared with the classically nonideal solutions, one classically ideal solution {B+C+...+Z} may...
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Relationship Among the Raoult Law, Zdanovskii−Stokes−Robinson Rule, and Two Extended Zdanovskii−Stokes−Robinson Rules of Wang†
Journal of Chemical & Engineering Data, 2009Co-Authors: Zhichang WangAbstract:In this paper, the Raoult law (C. R. Acad. Sci. Ser. C 1887, 104, 1430), the Zdanovskii−Stokes−Robinson (ZSR) rule (Trudy Solyanoi Laboratorii Akad. Nauk SSSR 1936, No. 6, 5; J. Phys. Chem. 1966, 70, 2126), and two extended ZSR rules of Wang (Acta Metall. Sinica 1980, 16, 195; Ber. Bunsen-Ges. Phys. Chem. 1998, 102, 1045) are presented in a unified way. Similar to the Raoult law, which was first noted empirically in pyridine solutions, the ZSR rule for isopiestic mixed electrolyte and nonelectrolyte aqueous solutions can be extended to every kind of liquid and solid solutions such as organic mixtures, aqueous and nonaqueous electrolyte and nonelectrolyte solutions, liquid and solid alloys, molten salt mixtures, slags, and nonstoichiometric solid solutions, resulting in two extended ZSR rules of Wang. Although the solutions obeying the Raoult law (or the related classically ideal solution model) are very few as compared with the classically nonideal solutions, one classically ideal solution {B+C+...+Z} may...
Michael H. Abraham - One of the best experts on this subject based on the ideXlab platform.
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limiting diffusion coefficients for ions and Nonelectrolytes in solvents water methanol ethanol propan 1 ol butan 1 ol octan 1 ol propanone and acetonitrile at 298 k analyzed using abraham descriptors
Journal of Solution Chemistry, 2019Co-Authors: Michael H. Abraham, William E AcreeAbstract:We have used literature data on the conductivity of single ions to obtain limiting diffusion coefficients (Do) of ions in water, alcohols, propanone and acetonitrile. We then used literature data on limiting diffusion coefficients of Nonelectrolytes in order to set up linear free energy relationships that combine data for ions and Nonelectrolytes, as log10 (Do) in the same equation, all values being at 298 K. These equations are for solvents water (N = 377, SD = 0.0474), methanol (N = 96, SD = 0.0332), ethanol (N = 96, SD = 0.0666), propan-1-ol (N = 71, SD = 0.0487), butan-1-ol (N = 53, SD = 0.0600), octan-1-ol (N = 61, SD = 0.0684), propanone (N = 86, SD = 0.0366) and acetonitrile (N = 74, SD = 0.0438) where N is the number of data points, that is ions plus Nonelectrolytes, and SD is the standard deviation in log10 (Do). It is shown that solute hydrogen bond acidity, solute hydrogen bond basicity and solute volume all lower the diffusion constants of ions and Nonelectrolytes in the various solvents studied.
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characterisation of the water o nitrophenyl octyl ether system in terms of the partition of Nonelectrolytes and of ions
Physical Chemistry Chemical Physics, 2005Co-Authors: Michael H. Abraham, Yuan H ZhaoAbstract:The Abraham linear free energy relationship, or solvation equation, has been applied to literature data on the partition of Nonelectrolytes in the water to o-nitrophenyl octyl ether (NPOE) system. The resulting equation is compared to equations for other water to solvent systems using the D-parameter of Abraham and Martins and the θ-parameter of Ishihama and Asakawa. It is shown that as a solvent in partitioning systems, NPOE quite resembles nitrobenzene and 1,2-dichloroethane, and that the latter does not resemble an alkane-like solvent. Using descriptors for simple ions that we have previously obtained, we show that ions and Nonelectrolytes can be included in the same linear free energy relationship.
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Characterisation of the water/o-nitrophenyl octyl ether system in terms of the partition of Nonelectrolytes and of ions.
Physical chemistry chemical physics : PCCP, 2005Co-Authors: Michael H. Abraham, Yuan H ZhaoAbstract:The Abraham linear free energy relationship, or solvation equation, has been applied to literature data on the partition of Nonelectrolytes in the water to o-nitrophenyl octyl ether (NPOE) system. The resulting equation is compared to equations for other water to solvent systems using the D-parameter of Abraham and Martins and the theta-parameter of Ishihama and Asakawa. It is shown that as a solvent in partitioning systems, NPOE quite resembles nitrobenzene and 1,2-dichloroethane, and that the latter does not resemble an alkane-like solvent. Using descriptors for simple ions that we have previously obtained, we show that ions and Nonelectrolytes can be included in the same linear free energy relationship.
Everett L Shock - One of the best experts on this subject based on the ideXlab platform.
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correlation strategy for determining the parameters of the revised helgeson kirkham flowers model for aqueous Nonelectrolytes
Geochimica et Cosmochimica Acta, 2001Co-Authors: Andrey V Plyasunov, Everett L ShockAbstract:Abstract The main goal of this study is to revise the correlation algorithm for estimating parameters of the revised Helgeson-Kirkham-Flowers (HKF) model for aqueous nonelectrolyte solutes. The basis for the revision is the analysis of a large body of experimental values of the standard partial molar heat capacities and volumes of aqueous Nonelectrolytes published mainly during the last decade. Unlike earlier estimation methods, we show that one of the most useful properties for developing correlations for uncharged species is the standard Gibbs energy of hydration of a solute at 298.15 K and 0.1 MPa, ΔhGo, which reflects the strength of water-solute interactions. Explicit correlations with ΔhGo seem to provide reliable means to estimate the “solvation” parameter ω and the “caloric” parameter c2 in the revised HKF model. “Volumetric” parameters a1 to a4 depend on both the size of a solute and its standard Gibbs energy of hydration. It is expected that the revised estimation strategy will improve the reliability of predictions of thermodynamic properties of aqueous Nonelectrolytes in the framework of the revised HKF model. A related problem is the temperature and density ranges of the applicability of the model for uncharged species. A comparison of experimental properties and those fitted in the framework of the revised HKF model made in this study or in articles published elsewhere shows that the model can be used along the saturation vapor-liquid curve of pure water in the density region sufficiently remote from the critical point of water, say up to 630 K. At densities above 500 to 600 kg · m−3 the range of applicability of the revised HKF model for uncharged species may extend up to higher temperatures. At temperatures up to 500 K at pressures up to 50 MPa, the revised HKF model is capable of excellent description of the standard thermodynamic properties of aqueous Nonelectrolytes, except in the narrow temperature range below 280–290 K.
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the temperature dependence of the standard state thermodynamic properties of aqueous Nonelectrolytes
Geochimica et Cosmochimica Acta, 2001Co-Authors: Mitchell D Schulte, Everett L Shock, Robert H WoodAbstract:Abstract Recent experimental studies of the standard-state heat capacities of aqueous Nonelectrolytes at high temperatures make it possible to test predictions made with theoretical equations of state and correlation algorithms. Existing predictive methods are qualitatively correct and produce quantitative results that are in reasonable agreement with the new experimental data at temperature ≤ 350°C, but much better results are possible using new data. Regression of the new data for CO 2 (aq), H 2 S(aq), CH 4 (aq), NH 3 (aq), and SO 2 (aq) leads to revised parameters for the revised Helgeson-Kirkham-Flowers (HKF) equation of state. New correlations based on these parameters allow revised regressions of older data for Xe(aq), Ar(aq), and C 2 H 4 (aq) and lead to new predictions for several other aqueous Nonelectrolytes. These predictions are tested against experimentally determined equilibrium constants for reactions involving several other aqueous Nonelectrolytes, including He(aq), Ne(aq), Kr(aq), Rn(aq), H 2 (aq), N 2 (aq), O 2 (aq), and CO(aq). The correlations developed are used to make predictions for a variety of other aqueous Nonelectrolytes, allowing incorporation of these species into models of geochemical processes.
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estimation of the krichevskii parameter for aqueous Nonelectrolytes
Journal of Supercritical Fluids, 2001Co-Authors: Andrey V Plyasunov, Everett L ShockAbstract:Abstract The Krichevskii parameter determines the sign and magnitude of the near-critical divergence of the partial molar thermodynamic properties of infinitely dilute solutions. Estimation of the values of the Krichevskii parameter, A Kr , would be helpful in improving the quality of predictions of the infinite dilution partial molar properties of aqueous Nonelectrolytes at near-critical and supercritical conditions. In this paper, we discuss the methods to obtain values of A Kr from various types of experimental information on the thermodynamic properties of binary systems, and use these methods to evaluate the Krichevskii parameter for more than 30 aqueous Nonelectrolytes. The possibility of calculating the values of the Krichevskii parameter for solutes at infinite dilution in water from the van der Waals and Peng–Robinson equations of state was also checked. It is shown that the classical cubic equations of state may be used to predict the values of A Kr for small nonpolar solutes in water, but grossly overestimate A Kr for larger compounds. As an alternative, we propose an empirical correlation between the Krichevskii parameter and the Gibbs energy of hydration at 298.15 K and 0.1 MPa for the corresponding compound. This correlation seems to hold for solutes with values of the Krichevskii parameter ranging from −200 to +200 MPa, and values of the Gibbs energy of hydration extending over 100 kJ mol −1 , and appears to be useful for estimating values of the Krichevskii parameter for many solutes of different sizes and polarities, from inert gases to aqueous silica. Predictions, related to the sign of the Krichevskii parameter for a number of aqueous inorganic and organic Nonelectrolytes, are made, which can be verified experimentally.