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Yuanzhi Song - One of the best experts on this subject based on the ideXlab platform.
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Theoretical study on the electrochemical behavior of norepinephrine at Nafion multi-walled carbon nanotubes modified pyrolytic graphite Electrode.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2006Co-Authors: Yuanzhi SongAbstract:Abstract DFT-B3LYP/6-31G (d, p) and HF/6-31G (d, p) calculations are performed for deoxidized norepinephrineat (NP (R) ) and its oxidized form (NP (O) ). The electrochemistry of norepinephrineat (NP) was studied by cyclic voltammetry (CV) at a pyrolytic graphite Electrode modified by Nafion multi-walled carbon nanotubes (MWNTs) in phosphate buffers at pH 6.0, showing that the Standard Electrode Potential of half reaction for NP (O) , H + /NP (R) is 0.75l V. This experimental Standard Electrode Potential of half reaction is consistent with that calculated using the energies of solvation and sum of electronic and thermal free energies of NP (R) and NP (O) . The frontier orbital theory and Mulliken charges of moleculer explain the electrochemical behavior of CV at modified Electrode well. The singlet vertical excited states for NP (R) and NP (O) are also discussed.
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Theoretical studies on electrochemistry of p-aminophenol.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2006Co-Authors: Yuanzhi SongAbstract:Geometric parameters, vibrational frequencies and thermochemical values of p-quinonimine (p-Q) and p-aminophenol (p-AP) were computed by ab initio calculation (HF) and density function theory (DFT) with the 6-31G(d,p) basis set. Cyclic voltammetry with a goldren Electrode of p-AP solutions in phosphate buffers at pH 7.30 showed that Standard Electrode Potential of half reaction for (p-Q) and (p-AP) is 0.728V. Standard Electrode Potential of half reaction for p-Q and p-AP were calculated using the sum of electronic and thermal free energies of p-Q and p-AP with normal hydrogen Electrode (NHE) as a reference Electrode. The results show that the theoretical Standard Electrode Potential of half reaction for p-Q and p-AP is 0.682V at B3LYP/6-31G(d,p) level and 0.622V at HF/6-31G(d,p) level, respectively, indicating that computed Standard Electrode Potential at B3LYP/6-31G(d,p) level are more reliable than that at HF/6-31G(d,p) level.
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Experimental and theoretical study of the electrochemical behavior of N-protonated dopamine at Nafion multiwalled carbon nanotubes (MWNTs) modified glassy carbon (GCE) Electrode
Canadian Journal of Chemistry, 2006Co-Authors: Yuanzhi Song, Yang SongAbstract:The electrochemistry of N-protonated dopamine (DAH+) was studied by cyclic voltammetry (CV) at a glassy carbon Electrode modified by Nafion multiwalled carbon nanotubes (MWNTs) in phosphate buffers (pH 5.50) and the results show that the Standard Electrode Potential of half reaction for DAH+(O),H+/ DAH+(R) is 0.74 V. Calculations are performed using DFT B3LY/6-31G(d,p) for nine conformers of N-protonated dopamine (DAH+(R)) and three conformers of oxidized N-protonated dopamine (DAH+(O)). The energies of solvation and sum of electronic and thermal free energies of DAH+(R), DAH+(O), p-benzoquinone (p-BQ), and p-hydroquinone (p-HQ) are calculated at same level. The theoretical weighted average of the Standard Electrode Potential (0.732 V) for DAH+(O),H+/ DAH+(R), using the transformed Gibbs free energies of the stable DAH+(R) and DAH+(O) with a p-BQ, H+/p-HQ reference Electrode, is consistent with the experimental one of 0.74 V.Key words: dopamine, DFT, cyclic voltammetry, Standard Electrode Potential.
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Calculation of Standard Electrode Potential of half reaction for benzoquinone and hydroquinone.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2006Co-Authors: Yuanzhi Song, Jimin Xie, Yang Song, Huoming Shu, Ganqing Zhao, Wen XieAbstract:Abstract Geometric parameters, the vibrational frequencies and thermochemical values of benzoquinone and hydroquinone were computed using ab initio molecular orbital calculations (HF) and density function theory (B3LYP) methods with the 6-31G(d) basis set, respectively. The calculated frequencies for benzoquinone and hydroquinone were used for the assignment of the IR frequencies observed in the experimental IR spectrum. Cyclic voltammetry with a glassy carbon Electrode of hydroquinone solutions in phosphate buffers at pH 7.0 showed that Standard Electrode Potential of half reaction for benzoquinone and hydroquinone is 0.714 V. Standard Electrode Potential of half reaction for benzoquinone and hydroquinone was calculated using the sum of electronic and thermal free energies, enthalpies of sublimation and energies of solvation for benzoquinone and hydroquinone.
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The electrochemical behavior of dopamine at glassy carbon Electrode modified by nafion multiwalled carbon nanotubes
Russian Journal of Physical Chemistry, 2006Co-Authors: Yuanzhi Song, Yang Song, Wen Xie, Deqing ShiAbstract:DFT (B3LY/6-31G (d, p) and B3LYP/cc-PVDZ) calculations are performed for deoxidized dopamine (DA(R)) and its oxidized form (DA(O)). The electrochemistry of dopamine (DA) was studied by cyclic voltammetry (CV) at a glassy carbon Electrode modified by Nafion multiwalled carbon nanotubes (MWNTs) in phosphate buffers at pH 5.4, showing that the Standard Electrode Potential of a half reaction for DA(O), H+/DA(R) is 0.74 V. This experimental Standard Electrode Potential of the half reaction is consistent with those of 0.65 and 0.69 V calculated using the energies of solvation and the sum of the electronic and thermal free energies of DA(R) and DA(O). The frontier orbital theory and Mulliken charges of molecules explain the electrochemical behavior of CV at a modified Electrode well. The effects of oxygen on DA(R) in blood and drug are also discussed according to equilibrium theory. The modified Electrode was successful for determination of the content of pharmaceutical DA.
Sang Yoon Lee - One of the best experts on this subject based on the ideXlab platform.
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investigating addition effect of hafnium in inzno thin film transistors using a solution process
Applied Physics Letters, 2010Co-Authors: Woong Hee Jeong, Gun Hee Kim, Hyun Soo Shin, Byung Du Ahn, Hyun Jae Kim, Myungkwan Ryu, Kyungbae Park, Jongbaek Seon, Sang Yoon LeeAbstract:The effects of adding Hf into a InZnO (IZO) system, particularly the electrical characteristics of their thin film and thin film transistors (TFTs), were investigated as a function of atomic concentration from 0 to 10 at. % of Hf and Ga/Zn. Because Hf has a high affinity for oxygen in IZO system, the Hf suppresses carrier generation more effectively than does Ga. At 10 at. % of Hf/Zn atomic concentration, the HfInZnO TFTs showed wider on-to-off ratios than those of GaInZnO TFTs due to the low Standard-Electrode-Potential of Hf and sharp subthreshold swings due to low trap density.
Dmitry V. Matyushov - One of the best experts on this subject based on the ideXlab platform.
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Standard Electrode Potential, Tafel equation, and the solvation thermodynamics
The Journal of chemical physics, 2009Co-Authors: Dmitry V. MatyushovAbstract:Equilibrium in the electronic subsystem across the solution-metal interface is considered to connect the Standard Electrode Potential to the statistics of localized electronic states in solution. We argue that a correct derivation of the Nernst equation for the Electrode Potential requires a careful separation of the relevant time scales. An equation for the Standard metal Potential is derived linking it to the thermodynamics of solvation. The Anderson-Newns model for electronic delocalization between the solution and the Electrode is combined with a bilinear model of solute-solvent coupling introducing nonlinear solvation into the theory of heterogeneous electron transfer. We therefore are capable of addressing the question of how nonlinear solvation affects electrochemical observables. The transfer coefficient of Electrode kinetics is shown to be equal to the derivative of the free energy, or generalized force, required to shift the unoccupied electronic level in the bulk. The transfer coefficient thus directly quantifies the extent of nonlinear solvation of the redox couple. The current model allows the transfer coefficient to deviate from the value of 0.5 of the linear solvation models at zero Electrode overPotential. The Electrode current curves become asymmetric in respect to the change in the sign of the Electrode overPotential.
Yang Song - One of the best experts on this subject based on the ideXlab platform.
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Theoretical and experimental studies of the electrochemistry of p-aminophenol on a golden Electrode
Russian Journal of Physical Chemistry A, 2007Co-Authors: Yanhua Song, J. M. Xie, Yang SongAbstract:The geometric parameters, vibrational frequencies, and thermochemical values of p-quinonimine (p-AQ) and p-aminophenol (p-AP) were computed ab initio (IIF) and by the density functional theory (DFT) method with the 6-31G(d, p) basis set. Cyclic voltammetry with a golden Electrode of p-AP solutions in phosphate buffers at pH 7.30 showed that the Standard Electrode Potential of half reaction for p-QI and p-AP was 0.728 V. The Standard Electrode Potentials of half reactions for p-QI and p-AP were calculated using the free energies and solvation energies of p-QI, p-AP, p-benzoquinone (p-BQ), and hydroquinone (p-HQ). The results showed that the Standard Electrode Potential of half reaction for p-QI and p-AP was 0.743 V at the B3LYP/6-31G(d, p) level and 0.755 V at the HF/6-31G(d, p) level. The Standard Electrode Potentials computed at the B3LYP/6-31G(d, p) and HF/6-31G(d, p) levels were close to their experimental values.
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Experimental and theoretical study of the electrochemical behavior of N-protonated dopamine at Nafion multiwalled carbon nanotubes (MWNTs) modified glassy carbon (GCE) Electrode
Canadian Journal of Chemistry, 2006Co-Authors: Yuanzhi Song, Yang SongAbstract:The electrochemistry of N-protonated dopamine (DAH+) was studied by cyclic voltammetry (CV) at a glassy carbon Electrode modified by Nafion multiwalled carbon nanotubes (MWNTs) in phosphate buffers (pH 5.50) and the results show that the Standard Electrode Potential of half reaction for DAH+(O),H+/ DAH+(R) is 0.74 V. Calculations are performed using DFT B3LY/6-31G(d,p) for nine conformers of N-protonated dopamine (DAH+(R)) and three conformers of oxidized N-protonated dopamine (DAH+(O)). The energies of solvation and sum of electronic and thermal free energies of DAH+(R), DAH+(O), p-benzoquinone (p-BQ), and p-hydroquinone (p-HQ) are calculated at same level. The theoretical weighted average of the Standard Electrode Potential (0.732 V) for DAH+(O),H+/ DAH+(R), using the transformed Gibbs free energies of the stable DAH+(R) and DAH+(O) with a p-BQ, H+/p-HQ reference Electrode, is consistent with the experimental one of 0.74 V.Key words: dopamine, DFT, cyclic voltammetry, Standard Electrode Potential.
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Calculation of Standard Electrode Potential of half reaction for benzoquinone and hydroquinone.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2006Co-Authors: Yuanzhi Song, Jimin Xie, Yang Song, Huoming Shu, Ganqing Zhao, Wen XieAbstract:Abstract Geometric parameters, the vibrational frequencies and thermochemical values of benzoquinone and hydroquinone were computed using ab initio molecular orbital calculations (HF) and density function theory (B3LYP) methods with the 6-31G(d) basis set, respectively. The calculated frequencies for benzoquinone and hydroquinone were used for the assignment of the IR frequencies observed in the experimental IR spectrum. Cyclic voltammetry with a glassy carbon Electrode of hydroquinone solutions in phosphate buffers at pH 7.0 showed that Standard Electrode Potential of half reaction for benzoquinone and hydroquinone is 0.714 V. Standard Electrode Potential of half reaction for benzoquinone and hydroquinone was calculated using the sum of electronic and thermal free energies, enthalpies of sublimation and energies of solvation for benzoquinone and hydroquinone.
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The electrochemical behavior of dopamine at glassy carbon Electrode modified by nafion multiwalled carbon nanotubes
Russian Journal of Physical Chemistry, 2006Co-Authors: Yuanzhi Song, Yang Song, Wen Xie, Deqing ShiAbstract:DFT (B3LY/6-31G (d, p) and B3LYP/cc-PVDZ) calculations are performed for deoxidized dopamine (DA(R)) and its oxidized form (DA(O)). The electrochemistry of dopamine (DA) was studied by cyclic voltammetry (CV) at a glassy carbon Electrode modified by Nafion multiwalled carbon nanotubes (MWNTs) in phosphate buffers at pH 5.4, showing that the Standard Electrode Potential of a half reaction for DA(O), H+/DA(R) is 0.74 V. This experimental Standard Electrode Potential of the half reaction is consistent with those of 0.65 and 0.69 V calculated using the energies of solvation and the sum of the electronic and thermal free energies of DA(R) and DA(O). The frontier orbital theory and Mulliken charges of molecules explain the electrochemical behavior of CV at a modified Electrode well. The effects of oxygen on DA(R) in blood and drug are also discussed according to equilibrium theory. The modified Electrode was successful for determination of the content of pharmaceutical DA.
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Density-functional theory studies on Standard Electrode Potentials of half reaction for L-adrenaline and adrenalinequinone.
Bioorganic & medicinal chemistry letters, 2005Co-Authors: Yuanzhi Song, Yang Song, Jian-feng Zhou, Yongge Wei, Hong WangAbstract:DFT (B3LY/6-31G(d) and B3PW91/6-31G(d)) calculations are performed for L-adrenaline and adrenalinequinone. The calculated IR spectrum of L-adrenaline is used for the assignment of IR frequencies that are observed in the experimental IR spectrum. Cyclic voltammetry with a platinum Electrode of L-adrenaline solutions in phosphate buffers at pH 1 shows that Standard Electrode Potential of half reaction for L-adrenaline and adrenalinequinone is 0.803 V. Standard Electrode Potential of half reaction for L-adrenaline and adrenalinequinone is calculated using the energies of solvation and the sum of electronic and thermal free energies of L-adrenaline and adrenalinequinone.
Hamid R. Zare - One of the best experts on this subject based on the ideXlab platform.
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Electrochemistry of chlorogenic acid : experimental and theoretical studies
Electrochimica Acta, 2005Co-Authors: Mansoor Namazian, Hamid R. ZareAbstract:Abstract Cyclic voltammetry, chronoamperometry and rotating disk Electrode voltammetry as well as quantum chemical methods, are used for electrochemical study of chlorogenic acid, as an important biological molecule. The Standard formal Potential, diffusion coefficient, and heterogeneous electron transfer rate constant of chlorogenic acid in aqueous solution are investigated. Acidic dissociation constant of chlorogenic acid is also obtained. Quantum mechanical calculations on oxidation of chlorogenic acid in aqueous solution, using density functional theory are presented. The change of Gibbs free energy and entropy of oxidation of chlorogenic acid are calculated using thermochemistry calculations. The calculations in aqueous solution are carried out with the use of polarizable continuum solvation method. Theoretical Standard Electrode Potential of chlorogenic acid is achieved to be 0.580 V versus Standard calomel Electrode (SCE) which is in agreement with the experimental value of 0.617 V obtained experimentally in this work. The difference is consistent with the values we previously reported for other quinone derivatives.
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Computational Electrode Potential of a coumestan derivative: Theoretical and experimental studies
Biophysical Chemistry, 2005Co-Authors: Mansoor Namazian, Hamid R. ZareAbstract:Abstract Electrode Potential of a coumestan derivative, an important biological molecule, in aqueous solution is computed theoretically using Self-Consistent Field (SCF) theory at the level of Hartree–Fock and employing 6-31G(d) basis set and also obtained experimentally by employing electrochemical technique of cyclic voltammetry (CV). Frequency calculations have been carried out and thermal corrections and entropies have been taken into account. Polarizable continuum model is used to describe the solvent. The theoretical and experimental values for the Standard Electrode Potential of the studied coumestan are in excellent agreement with each other and there is only 0.001 V discrepancy between experiment and theory. The agreement mutually verifies the accuracy of experimental method and the validity of mathematical model.