The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
José Paulo Pinheiro - One of the best experts on this subject based on the ideXlab platform.
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Addressing temperature effects on metal chemodynamics studies using stripping electroanalytical techniques. Part 1: Lability of small complexes
Journal of Electroanalytical Chemistry, 2015Co-Authors: Elise Rotureau, Yves Waldvogel, Romain M. Présent, José Paulo PinheiroAbstract:Abstract Temperature effects on metal speciation dynamics were studied using Stripping Chronopotentiometry at Scanned deposition Potential (SSCP). The temporal and spatial scales of this study are respectively O(10−1 s) and O(10−5 M), characteristics of the thin mercury film rotating disk, used as working electrode. The lability degree and the Association Rate Constant were evaluated in the temperature interval of 15–40 °C for a significantly non-labile system, cadmium binding by nitrilotriacetic acid, and a quasi-labile system, lead binding by iminodiacetic acid. The results for both systems reveal that the lability of the metal complex significantly increases with temperature. This lability gain results from the thermal augmentation of the Association Rate Constant and the broadening of the diffusion layer thickness. An evaluation of the metal calibration methodology for SSCP at different temperatures was conducted. It was found that although the variation of diffusion layer thickness can be correctly predicted, changes in standard reduction potential of the metals cannot, thus a calibration must be performed for each temperature studied. This work constitutes a first step toward the comprehension of the effect of temperature on metal chemodynamics.
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Addressing temperature effects on metal chemodynamics studies using stripping electroanalytical techniques. Part 1: Lability of small complexes
Journal of Electroanalytical Chemistry, 2015Co-Authors: Elise Rotureau, Yves Waldvogel, Romain M. Présent, José Paulo PinheiroAbstract:Temperature effects on metal speciation dynamics were studied using Stripping Chronopotentiometry at Scanned deposition Potential (SSCP). The temporal and spatial scales of this study are respectively O(10(-1) s) and O(10(-5) M), characteristics of the thin mercury film rotating disk, used as working electrode. The lability degree and the Association Rate Constant were evaluated in the temperature interval of 15-40 degrees C for a significantly non-labile system, cadmium binding by nitrilotriacetic acid, and a quasi-labile system, lead binding by iminodiacetic acid. The results for both systems reveal that the lability of the metal complex significantly increases with temperature. This lability gain results from the thermal augmentation of the Association Rate Constant and the broadening of the diffusion layer thickness. An evaluation of the metal calibration methodology for SSCP at different temperatures was conducted. It was found that although the variation of diffusion layer thickness can be correctly predicted, changes in standard reduction potential of the metals cannot, thus a calibration must be performed for each temperature studied. This work constitutes a first step toward the comprehension of the effect of temperature on metal chemodynamics.
Elise Rotureau - One of the best experts on this subject based on the ideXlab platform.
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Addressing temperature effects on metal chemodynamics studies using stripping electroanalytical techniques. Part 1: Lability of small complexes
Journal of Electroanalytical Chemistry, 2015Co-Authors: Elise Rotureau, Yves Waldvogel, Romain M. Présent, José Paulo PinheiroAbstract:Abstract Temperature effects on metal speciation dynamics were studied using Stripping Chronopotentiometry at Scanned deposition Potential (SSCP). The temporal and spatial scales of this study are respectively O(10−1 s) and O(10−5 M), characteristics of the thin mercury film rotating disk, used as working electrode. The lability degree and the Association Rate Constant were evaluated in the temperature interval of 15–40 °C for a significantly non-labile system, cadmium binding by nitrilotriacetic acid, and a quasi-labile system, lead binding by iminodiacetic acid. The results for both systems reveal that the lability of the metal complex significantly increases with temperature. This lability gain results from the thermal augmentation of the Association Rate Constant and the broadening of the diffusion layer thickness. An evaluation of the metal calibration methodology for SSCP at different temperatures was conducted. It was found that although the variation of diffusion layer thickness can be correctly predicted, changes in standard reduction potential of the metals cannot, thus a calibration must be performed for each temperature studied. This work constitutes a first step toward the comprehension of the effect of temperature on metal chemodynamics.
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Addressing temperature effects on metal chemodynamics studies using stripping electroanalytical techniques. Part 1: Lability of small complexes
Journal of Electroanalytical Chemistry, 2015Co-Authors: Elise Rotureau, Yves Waldvogel, Romain M. Présent, José Paulo PinheiroAbstract:Temperature effects on metal speciation dynamics were studied using Stripping Chronopotentiometry at Scanned deposition Potential (SSCP). The temporal and spatial scales of this study are respectively O(10(-1) s) and O(10(-5) M), characteristics of the thin mercury film rotating disk, used as working electrode. The lability degree and the Association Rate Constant were evaluated in the temperature interval of 15-40 degrees C for a significantly non-labile system, cadmium binding by nitrilotriacetic acid, and a quasi-labile system, lead binding by iminodiacetic acid. The results for both systems reveal that the lability of the metal complex significantly increases with temperature. This lability gain results from the thermal augmentation of the Association Rate Constant and the broadening of the diffusion layer thickness. An evaluation of the metal calibration methodology for SSCP at different temperatures was conducted. It was found that although the variation of diffusion layer thickness can be correctly predicted, changes in standard reduction potential of the metals cannot, thus a calibration must be performed for each temperature studied. This work constitutes a first step toward the comprehension of the effect of temperature on metal chemodynamics.
Donald J. Winzor - One of the best experts on this subject based on the ideXlab platform.
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Allowance for antibody bivalence in the determination of Association Rate Constants by kinetic exclusion assay
Analytical biochemistry, 2013Co-Authors: Donald J. WinzorAbstract:Abstract This investigation completes the amendment of theoretical expressions for the characterization of antigen–antibody interactions by kinetic exclusion assay—an endeavor that has been marred by inadequate allowance for the consequences of antibody bivalence in its uptake by the affinity matrix (immobilized antigen) that is used to ascertain the fraction of free antibody sites in a solution with defined total concentrations of antigen and antibody. A simple illustration of reacted site probability considerations in action confirms that the square root of the fluorescence response ratio, RAg/Ro, needs to be taken in order to determine the fraction of unoccupied antibody sites, which is the parameter employed to describe the kinetics of antigen uptake in the mixture of antigen and antibody with defined initial composition. The approximately 2-fold underestimation of the Association Rate Constant (ka) that emanates from the usual practice of omitting the square root factor gives rise to a corresponding overestimate of the equilibrium dissociation Constant (Kd)—a situation that is also encountered in the thermodynamic characterization of antigen–antibody interactions by kinetic exclusion assay.
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Demonstration of an upper limit to the range of Association Rate Constants amenable to study by biosensor technology based on surface plasmon resonance.
Analytical biochemistry, 1996Co-Authors: Damien Hall, John R. Cann, Donald J. WinzorAbstract:Abstract Numerical simulation of BIAcore sensorgrams has highlighted the need for concern about an assumption, inherent in current determinations of Rate Constants for macromolecular interactions, that the concentration of solute in the flowing phase remains Constant at its injected value. This assumption is shown to be valid for systems with effective Association Rate Constants equal to or less than 10 5 M −1 s −1 , values characteristic of antibody interactions with protein antigens. However, the assumption loses validity when the effective Association Rate Constant is raised to 10 7 M −1 s −1 . The basic correctness of the latter prediction is verified by an experimental study of the interaction between soybean trypsin inhibitor and immobilized β-trypsin, a system with comparable reaction kinetics.
Kihyung Song - One of the best experts on this subject based on the ideXlab platform.
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Role of the Surface Site in the Kinetics of H-Atom Association with Diamond Surfaces
Journal of Physical Chemistry B, 1998Co-Authors: Pascal De Sainte Claire, William Hase, Kihyung SongAbstract:The reaction path Hamiltonian model and the MAPS/HDIAM analytic potential energy function were used in a canonical variational transition state theory (CVTST) study of H atom Association with diamond surfaces. CVTST Rate Constants are compared for H atom Association with a terrace site on the diamond {111} surface and two ledge sites on this surface. The CVTST Association Rate Constant is largest for the terrace site and is 3.9 and 2.4 times larger than the Rate Constant for one of the ledge sites at 300 and 2000 K, respectively. Nonbonded interactions between the associating H atom and surface H atoms decrease the attractiveness and increase the repulsiveness of the radial and angular potentials, respectively, along the Association reaction path. The CVTST Rate Constants are found to be in good agreement with classical trajectory Rate Constants, also calculated for the MAPS/HDIAM potential. This study shows how nonbonded interactions and steric effects may affect Rate Constants for diamond surfaces.
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Comparison of ab Initio and Empirical Potentials for H-Atom Association with Diamond Surfaces
The Journal of Physical Chemistry, 1996Co-Authors: Pascal De Sainte Claire, William L. Hase, Kihyung Song, D. W. BrennerAbstract:Canonical variational transition-state theory (CVTST) is used to compare H + CH{sub 3} and H + diamond [111] Association Rate Constants calculated from the Brenner empirical potential function and molecular anharmonic potentials written with switching (MAPS) functions. Previous work has shown that the MAPS function, derived from ab initio calculations, give Rate Constants in agreement with experiment. For the 300-2000 K temperature range, the Brenner potential function gives CVST H + CH{sub 3} and H + diamond [111] Association Rate Constants which are 159-30 and 49-7 times smaller, respectively, than the values from the MAPS functions. An analysis of the Brenner potential function shows that it inaccuRately represents the intermediate and long-range H- - -C Association potential, which controls the structure of the variational transition state and the CVTST Rate Constant. The MAPS functions give H + CH{sub 3} and H + diamond [111] variational transition states with similar properties. Angular momentum and external rotation have no effect on the H + diamond [111] Association Rate Constant, which makes it approximately an order-of-magnitude smaller than that for H + CH{sub 3} Association. 59 refs., 6 figs., 3 tabs.
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Comparison of ab Initio and Empirical Potentials for H-Atom Association with Diamond Surfaces
The Journal of physical chemistry, 1996Co-Authors: Pascal De Sainte Claire, William Hase, Kihyung Song, D. BrennerAbstract:Canonical variational transition-state theory (CVTST) is used to compare H + CH3 and H + diamond {111} Association Rate Constants calculated from the Brenner empirical potential function and molecular anharmonic potentials written with switching (MAPS) functions. Previous work [J. Am. Chem. Soc. 1987, 109, 2916; J. Chem. Phys. 1994, 101, 2476] has shown that the MAPS functions, derived from ab initio calculations, give Rate Constants in agreement with experiment. For the 300−2000 K temperature range, the Brenner potential function gives CVTST H + CH3 and H + diamond {111} Association Rate Constants which are 159−30 and 49−7 times smaller, respectively, than the values from the MAPS functions. An analysis of the Brenner potential function shows that it inaccuRately represents the intermediate and long-range H- - -C Association potential, which controls the structure of the variational transition state and the CVTST Rate Constant. The MAPS functions give H + CH3 and H + diamond {111} variational transition states with similar properties. Angular momentum and external rotation have no effect on the H + diamond {111} Association Rate Constant, which makes it approximately an order-of-magnitude smaller than that for H + CH3 Association.
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Comparison of molecular dynamics and variational transition-state-theory calculations of the Rate Constant for H-atom Association with the diamond {111} surface
Physical Review B: Condensed Matter and Materials Physics (1998-2015), 1995Co-Authors: Kihyung Song, Pascal De Sainte Claire, William Hase, K. HassAbstract:The quasiclassical trajectory method was used to study the dynamics and kinetics of H-atom Association with a C-atom radical site on the diamond {111} surface. The calculations employed an analytic potential-energy surface derived previously [P. de Sainte Claire, P. Barbarat, and W. L. Hase, J. Chem. Phys. 101, 2476 (1994)] from high-level ab initio calculations. The trajectory Rate Constant calculated here of 1.7±0.3×1013 cm3 mol-1 s-1 for temperatures of 1000 and 2000 K is in excellent agreement with the one calculated previously on the same analytic potential-energy surface using canonical variational transition-state theory. For H atoms impinging perpendicularly and directly onto the C-atom radical site, the Association probability is sensitive to the frequencies of the diamond lattice and the treatment of the lattice's zero-point energy. However, trajectories with this orientation make a negligible contribution to the thermal Rate Constant, which is found to be nearly insensitive to the lattice frequencies and zero-point energy. Trajectories, for which H atoms move toward the surface with a small angle relative to the surface plane and pass above the C-atom radical site before associating, make an important contribution to the Association Rate Constant.
Yves Waldvogel - One of the best experts on this subject based on the ideXlab platform.
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Addressing temperature effects on metal chemodynamics studies using stripping electroanalytical techniques. Part 1: Lability of small complexes
Journal of Electroanalytical Chemistry, 2015Co-Authors: Elise Rotureau, Yves Waldvogel, Romain M. Présent, José Paulo PinheiroAbstract:Abstract Temperature effects on metal speciation dynamics were studied using Stripping Chronopotentiometry at Scanned deposition Potential (SSCP). The temporal and spatial scales of this study are respectively O(10−1 s) and O(10−5 M), characteristics of the thin mercury film rotating disk, used as working electrode. The lability degree and the Association Rate Constant were evaluated in the temperature interval of 15–40 °C for a significantly non-labile system, cadmium binding by nitrilotriacetic acid, and a quasi-labile system, lead binding by iminodiacetic acid. The results for both systems reveal that the lability of the metal complex significantly increases with temperature. This lability gain results from the thermal augmentation of the Association Rate Constant and the broadening of the diffusion layer thickness. An evaluation of the metal calibration methodology for SSCP at different temperatures was conducted. It was found that although the variation of diffusion layer thickness can be correctly predicted, changes in standard reduction potential of the metals cannot, thus a calibration must be performed for each temperature studied. This work constitutes a first step toward the comprehension of the effect of temperature on metal chemodynamics.
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Addressing temperature effects on metal chemodynamics studies using stripping electroanalytical techniques. Part 1: Lability of small complexes
Journal of Electroanalytical Chemistry, 2015Co-Authors: Elise Rotureau, Yves Waldvogel, Romain M. Présent, José Paulo PinheiroAbstract:Temperature effects on metal speciation dynamics were studied using Stripping Chronopotentiometry at Scanned deposition Potential (SSCP). The temporal and spatial scales of this study are respectively O(10(-1) s) and O(10(-5) M), characteristics of the thin mercury film rotating disk, used as working electrode. The lability degree and the Association Rate Constant were evaluated in the temperature interval of 15-40 degrees C for a significantly non-labile system, cadmium binding by nitrilotriacetic acid, and a quasi-labile system, lead binding by iminodiacetic acid. The results for both systems reveal that the lability of the metal complex significantly increases with temperature. This lability gain results from the thermal augmentation of the Association Rate Constant and the broadening of the diffusion layer thickness. An evaluation of the metal calibration methodology for SSCP at different temperatures was conducted. It was found that although the variation of diffusion layer thickness can be correctly predicted, changes in standard reduction potential of the metals cannot, thus a calibration must be performed for each temperature studied. This work constitutes a first step toward the comprehension of the effect of temperature on metal chemodynamics.
