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Richard E. Riman - One of the best experts on this subject based on the ideXlab platform.
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Phase-sequenced deposition of calcium titanate/hydroxyapatite films with controllable crystallographic texture onto Ti6Al4V by Triethyl Phosphate-regulated hydrothermal crystallization
Crystal Growth & Design, 2009Co-Authors: Daniel J. Haders, Alexander Burukhin, Yizhong Huang, David J. H. Cockayne, Richard E. RimanAbstract:The aim of this study was to investigate the use of Triethyl Phosphate (TEP) to regulate the hydrothermal crystallization of hydroxyapatite (HA) films onto Ti6Al4V substrates. The growth mechanism of the HA film and the development of [0001] HA crystallographic texture were studied. Films were crystallized in a 0.232 m Ca(NO3)2−0.232 m EDTA−0.187 m TEP−1.852 m KOH−H2O chemical system with a final isothermal temperature of 200 °C, and then evaluated at synthesis times from 0 to 46 h by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and X-ray pole figures. Thermodynamic phase stability diagrams were calculated to validate experimental findings. XRD, FESEM, TEM, and EDX results demonstrated the crystallization of a CaTiO3 film below 180 °C and a HA film above 180 °C. FESEM and X-ray pole figure analysis revealed a refinement of the orientation of the (0002) HA crystallographic plane and the c-axis o...
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phase sequenced deposition of calcium titanate hydroxyapatite films with controllable crystallographic texture onto ti6al4v by Triethyl Phosphate regulated hydrothermal crystallization
Crystal Growth & Design, 2009Co-Authors: Daniel J. Haders, Alexander Burukhin, Yizhong Huang, David J. H. Cockayne, Richard E. RimanAbstract:The aim of this study was to investigate the use of Triethyl Phosphate (TEP) to regulate the hydrothermal crystallization of hydroxyapatite (HA) films onto Ti6Al4V substrates. The growth mechanism of the HA film and the development of [0001] HA crystallographic texture were studied. Films were crystallized in a 0.232 m Ca(NO3)2−0.232 m EDTA−0.187 m TEP−1.852 m KOH−H2O chemical system with a final isothermal temperature of 200 °C, and then evaluated at synthesis times from 0 to 46 h by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and X-ray pole figures. Thermodynamic phase stability diagrams were calculated to validate experimental findings. XRD, FESEM, TEM, and EDX results demonstrated the crystallization of a CaTiO3 film below 180 °C and a HA film above 180 °C. FESEM and X-ray pole figure analysis revealed a refinement of the orientation of the (0002) HA crystallographic plane and the c-axis o...
Subith Vasu - One of the best experts on this subject based on the ideXlab platform.
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Theoretical Calculation of Reaction Rates and Combustion Kinetic Modeling Study of Triethyl Phosphate (TEP).
The journal of physical chemistry. A, 2019Co-Authors: Sneha Neupane, Ramees K Rahman, Artem E Masunov, Subith VasuAbstract:Triethyl Phosphate (TEP) is an organophosphorus compound used as a simulant for highly toxic nerve agents such as sarin GB. A high temperature decomposition pathway during TEP pyrolysis has been proposed previously and takes place via seven concerted elimination reactions. A computational study to investigate the kinetics of these seven reactions was carried out at the CBS-QB3 level of theory. The transition state optimization was done at the B3LYP/6-311G(2d,d,p) theory level, and CanTherm was used to derive the Arrhenius coefficients. The pre-exponential factors of the rate constant of these reactions were found to be up to 50 times lower than the estimated values from the literature. In addition, kinetics of reaction of the trioxidophosphorus radical (PO3) with H2 (H2 + PO3 → HOPO2 + H), which is one of the important reactions in predicting CO formation during TEP decomposition, was also investigated computationally at the same theory level. The new kinetic parameters derived from the computational study were used with the TEP kinetic model proposed recently by our group. In addition, an alternative decomposition pathway for TEP decomposition via H-abstraction, radical decomposition, and recombination reactions was added. The proposed mechanism was validated with the literature's experimental data, that is, intermediate CO time-history data from pyrolysis and oxidation experiments and ignition delay times. Fairly good agreement with experiments was obtained for pyrolysis and oxidation CO yield within 1200-1700 K. The model was able to predict the ignition times of the rich TEP mixture (φ = 2) within 25% of the experimental results, while the discrepancies for stoichiometric and rich mixtures were larger. Discussions on results of sensitivity and reaction pathway analysis are presented to identify the important phosphorus reactions and to understand the effect of addition of the alternative TEP decomposition pathway.
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theoretical calculation of reaction rates and combustion kinetic modeling study of Triethyl Phosphate tep
Journal of Physical Chemistry A, 2019Co-Authors: Sneha Neupane, Ramees K Rahman, Artem E Masunov, Subith VasuAbstract:Triethyl Phosphate (TEP) is an organophosphorus compound used as a simulant for highly toxic nerve agents such as sarin GB. A high temperature decomposition pathway during TEP pyrolysis has been pr...
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Shock Tube/Laser Absorption and Kinetic Modeling Study of Triethyl Phosphate Combustion.
The journal of physical chemistry. A, 2018Co-Authors: Sneha Neupane, Artem E Masunov, Frank Barnes, Samuel Barak, Erik Ninnemann, Zachary Loparo, Subith VasuAbstract:Pyrolysis and oxidation of Triethyl Phosphate (TEP) were performed in the reflected shock region at temperatures of 1462-1673 K and 1213-1508 K, respectively, and at pressures near 1.3 atm. CO concentration time histories during the experiments were measured using laser absorption spectroscopy at 4580.4 nm. Experimental CO yields were compared with model predictions using the detailed organophosphorus compounds (OPC) incineration mechanism from the Lawrence Livermore National Lab (LLNL). The mechanism significantly underpredicts CO yield in TEP pyrolysis. During TEP oxidation, predicted rate of CO formation was significantly slower than the experimental results. Therefore, a new improved kinetic model for TEP combustion was developed, which was built upon the AramcoMech2.0 mechanism for C0-C2 chemistry and the existing LLNL submechanism for phosphorus chemistry. Thermochemical data of 40 phosphorus (P)-containing species were reevaluated, either using recently published group values for P-containing species or by quantum chemical calculations (CBS-QB3). The new improved model is in better agreement with the experimental CO time histories within the temperature and pressure conditions tested in this study. Sensitivity analysis was used to identify important reactions affecting CO formation, and future experimental/theoretical studies on kinetic parameters of these reactions were suggested to further improve the model. To the best of our knowledge, this is the first study of TEP kinetics in a shock tube under these conditions and the first time-resolved laser-based species time history data during its pyrolysis and oxidation.
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shock tube laser absorption and kinetic modeling study of Triethyl Phosphate combustion
Journal of Physical Chemistry A, 2018Co-Authors: Sneha Neupane, Artem E Masunov, Frank Barnes, Samuel Barak, Erik Ninnemann, Zachary Loparo, Subith VasuAbstract:Pyrolysis and oxidation of Triethyl Phosphate (TEP) were performed in the reflected shock region at temperatures of 1462–1673 K and 1213–1508 K, respectively, and at pressures near 1.3 atm. CO concentration time histories during the experiments were measured using laser absorption spectroscopy at 4580.4 nm. Experimental CO yields were compared with model predictions using the detailed organophosphorus compounds (OPC) incineration mechanism from the Lawrence Livermore National Lab (LLNL). The mechanism significantly underpredicts CO yield in TEP pyrolysis. During TEP oxidation, predicted rate of CO formation was significantly slower than the experimental results. Therefore, a new improved kinetic model for TEP combustion was developed, which was built upon the AramcoMech2.0 mechanism for C0-C2 chemistry and the existing LLNL submechanism for phosphorus chemistry. Thermochemical data of 40 phosphorus (P)-containing species were reevaluated, either using recently published group values for P-containing speci...
Sneha Neupane - One of the best experts on this subject based on the ideXlab platform.
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Theoretical Calculation of Reaction Rates and Combustion Kinetic Modeling Study of Triethyl Phosphate (TEP).
The journal of physical chemistry. A, 2019Co-Authors: Sneha Neupane, Ramees K Rahman, Artem E Masunov, Subith VasuAbstract:Triethyl Phosphate (TEP) is an organophosphorus compound used as a simulant for highly toxic nerve agents such as sarin GB. A high temperature decomposition pathway during TEP pyrolysis has been proposed previously and takes place via seven concerted elimination reactions. A computational study to investigate the kinetics of these seven reactions was carried out at the CBS-QB3 level of theory. The transition state optimization was done at the B3LYP/6-311G(2d,d,p) theory level, and CanTherm was used to derive the Arrhenius coefficients. The pre-exponential factors of the rate constant of these reactions were found to be up to 50 times lower than the estimated values from the literature. In addition, kinetics of reaction of the trioxidophosphorus radical (PO3) with H2 (H2 + PO3 → HOPO2 + H), which is one of the important reactions in predicting CO formation during TEP decomposition, was also investigated computationally at the same theory level. The new kinetic parameters derived from the computational study were used with the TEP kinetic model proposed recently by our group. In addition, an alternative decomposition pathway for TEP decomposition via H-abstraction, radical decomposition, and recombination reactions was added. The proposed mechanism was validated with the literature's experimental data, that is, intermediate CO time-history data from pyrolysis and oxidation experiments and ignition delay times. Fairly good agreement with experiments was obtained for pyrolysis and oxidation CO yield within 1200-1700 K. The model was able to predict the ignition times of the rich TEP mixture (φ = 2) within 25% of the experimental results, while the discrepancies for stoichiometric and rich mixtures were larger. Discussions on results of sensitivity and reaction pathway analysis are presented to identify the important phosphorus reactions and to understand the effect of addition of the alternative TEP decomposition pathway.
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theoretical calculation of reaction rates and combustion kinetic modeling study of Triethyl Phosphate tep
Journal of Physical Chemistry A, 2019Co-Authors: Sneha Neupane, Ramees K Rahman, Artem E Masunov, Subith VasuAbstract:Triethyl Phosphate (TEP) is an organophosphorus compound used as a simulant for highly toxic nerve agents such as sarin GB. A high temperature decomposition pathway during TEP pyrolysis has been pr...
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Theoretical Calculation of Reaction Rates and Combustion Kinetic Modeling Study of Triethyl Phosphate (TEP)
2019Co-Authors: Sneha Neupane, Ramees K Rahman, Artem E Masunov, Subith S. VasuAbstract:Triethyl Phosphate (TEP) is an organophosphorus compound used as a simulant for highly toxic nerve agents such as sarin GB. A high temperature decomposition pathway during TEP pyrolysis has been proposed previously and takes place via seven concerted elimination reactions. A computational study to investigate the kinetics of these seven reactions was carried out at the CBS-QB3 level of theory. The transition state optimization was done at the B3LYP/6-311G(2d,d,p) theory level, and CanTherm was used to derive the Arrhenius coefficients. The pre-exponential factors of the rate constant of these reactions were found to be up to 50 times lower than the estimated values from the literature. In addition, kinetics of reaction of the trioxidophosphorus radical (PO3) with H2 (H2 + PO3 → HOPO2 + H), which is one of the important reactions in predicting CO formation during TEP decomposition, was also investigated computationally at the same theory level. The new kinetic parameters derived from the computational study were used with the TEP kinetic model proposed recently by our group. In addition, an alternative decomposition pathway for TEP decomposition via H-abstraction, radical decomposition, and recombination reactions was added. The proposed mechanism was validated with the literature’s experimental data, that is, intermediate CO time-history data from pyrolysis and oxidation experiments and ignition delay times. Fairly good agreement with experiments was obtained for pyrolysis and oxidation CO yield within 1200–1700 K. The model was able to predict the ignition times of the rich TEP mixture (φ = 2) within 25% of the experimental results, while the discrepancies for stoichiometric and rich mixtures were larger. Discussions on results of sensitivity and reaction pathway analysis are presented to identify the important phosphorus reactions and to understand the effect of addition of the alternative TEP decomposition pathway
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Shock Tube/Laser Absorption and Kinetic Modeling Study of Triethyl Phosphate Combustion.
The journal of physical chemistry. A, 2018Co-Authors: Sneha Neupane, Artem E Masunov, Frank Barnes, Samuel Barak, Erik Ninnemann, Zachary Loparo, Subith VasuAbstract:Pyrolysis and oxidation of Triethyl Phosphate (TEP) were performed in the reflected shock region at temperatures of 1462-1673 K and 1213-1508 K, respectively, and at pressures near 1.3 atm. CO concentration time histories during the experiments were measured using laser absorption spectroscopy at 4580.4 nm. Experimental CO yields were compared with model predictions using the detailed organophosphorus compounds (OPC) incineration mechanism from the Lawrence Livermore National Lab (LLNL). The mechanism significantly underpredicts CO yield in TEP pyrolysis. During TEP oxidation, predicted rate of CO formation was significantly slower than the experimental results. Therefore, a new improved kinetic model for TEP combustion was developed, which was built upon the AramcoMech2.0 mechanism for C0-C2 chemistry and the existing LLNL submechanism for phosphorus chemistry. Thermochemical data of 40 phosphorus (P)-containing species were reevaluated, either using recently published group values for P-containing species or by quantum chemical calculations (CBS-QB3). The new improved model is in better agreement with the experimental CO time histories within the temperature and pressure conditions tested in this study. Sensitivity analysis was used to identify important reactions affecting CO formation, and future experimental/theoretical studies on kinetic parameters of these reactions were suggested to further improve the model. To the best of our knowledge, this is the first study of TEP kinetics in a shock tube under these conditions and the first time-resolved laser-based species time history data during its pyrolysis and oxidation.
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shock tube laser absorption and kinetic modeling study of Triethyl Phosphate combustion
Journal of Physical Chemistry A, 2018Co-Authors: Sneha Neupane, Artem E Masunov, Frank Barnes, Samuel Barak, Erik Ninnemann, Zachary Loparo, Subith VasuAbstract:Pyrolysis and oxidation of Triethyl Phosphate (TEP) were performed in the reflected shock region at temperatures of 1462–1673 K and 1213–1508 K, respectively, and at pressures near 1.3 atm. CO concentration time histories during the experiments were measured using laser absorption spectroscopy at 4580.4 nm. Experimental CO yields were compared with model predictions using the detailed organophosphorus compounds (OPC) incineration mechanism from the Lawrence Livermore National Lab (LLNL). The mechanism significantly underpredicts CO yield in TEP pyrolysis. During TEP oxidation, predicted rate of CO formation was significantly slower than the experimental results. Therefore, a new improved kinetic model for TEP combustion was developed, which was built upon the AramcoMech2.0 mechanism for C0-C2 chemistry and the existing LLNL submechanism for phosphorus chemistry. Thermochemical data of 40 phosphorus (P)-containing species were reevaluated, either using recently published group values for P-containing speci...
M T Rodgers - One of the best experts on this subject based on the ideXlab platform.
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Infrared multiple photon dissociation action spectroscopy and theoretical studies of Triethyl Phosphate complexes: effects of protonation and sodium cationization on structure.
Journal of the American Society for Mass Spectrometry, 2011Co-Authors: B S Fales, N O Fujamade, J Oomens, M T RodgersAbstract:The gas-phase structures of protonated and sodium cationized complexes of Triethyl Phosphate, [TEP + H](+) and [TEP + Na](+), are examined via infrared multiple photon dissociation (IRMPD) action spectroscopy using tunable IR radiation generated by a free electron laser, a Fourier transform ion cyclotron resonance mass spectrometer with an electrospray ionization source, and theoretical electronic structure calculations. Measured IRMPD action spectra are compared to linear IR spectra calculated at the B3LYP/6-31 G(d,p) level of theory to identify the structures accessed in the experimental studies. For comparison, theoretical studies of neutral TEP are also performed. Sodium cationization and protonation produce changes in the central Phosphate geometry, including an increase in the alkoxy ∠OPO bond angle and shortening of the alkoxy P-O bond. Changes associated with protonation are more pronounced than those produced by sodium cationization.
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Modeling metal cation-Phosphate interactions in nucleic acids: activated dissociation of Mg+, Al+, Cu+, and Zn+ complexes of Triethyl Phosphate.
Journal of the American Chemical Society, 2009Co-Authors: Chunhai Ruan, M T RodgersAbstract:Threshold collision-induced dissociation techniques are employed to determine the activation energies (AEs) and bond dissociation energies (BDEs) of metal cation-Triethyl Phosphate complexes, M(+)(TEP), where M(+) = Mg(+), Al(+), Cu(+), and Zn(+). Activated dissociation resulting in loss of ethene, C(2)H(4), corresponds to the primary and lowest energy pathway for all four systems examined. Sequential loss of additional C(2)H(4) molecules and loss of the intact TEP ligand is also observed at elevated energies. Theoretical calculations at the B3LYP/6-31G* level of theory are used to determine the structures, vibrational frequencies, and rotational constants of neutral TEP and the M(+)(TEP) complexes, transition states, intermediates, and products of the activated dissociation of these complexes. Theoretical AEs and BDEs are determined from single point energy calculations at the B3LYP/6-311+G(2d,2p) level using the B3LYP/6-31G* optimized geometries. The agreement between the calculated and measured AEs for elimination of C(2)H(4) is excellent for all four systems. In contrast, less satisfactory agreement between theory and experiment is found for the M(+)-TEP BDEs and may indicate limitations in the competitive model used to analyze these high energy dissociation pathways. The influence of the valence orbital occupation of the metal cation on the binding and activation propensities for elimination of ethene from TEP is examined. The binding of metal cations to TEP is compared to that of the nucleobases to assess the binding preferences of metal cations to nucleic acids.
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modeling metal cation Phosphate interactions in nucleic acids activated dissociation of mg al cu and zn complexes of Triethyl Phosphate
Journal of the American Chemical Society, 2009Co-Authors: Chunhai Ruan, M T RodgersAbstract:Threshold collision-induced dissociation techniques are employed to determine the activation energies (AEs) and bond dissociation energies (BDEs) of metal cation-Triethyl Phosphate complexes, M+(TEP), where M+ = Mg+, Al+, Cu+, and Zn+. Activated dissociation resulting in loss of ethene, C2H4, corresponds to the primary and lowest energy pathway for all four systems examined. Sequential loss of additional C2H4 molecules and loss of the intact TEP ligand is also observed at elevated energies. Theoretical calculations at the B3LYP/6-31G* level of theory are used to determine the structures, vibrational frequencies, and rotational constants of neutral TEP and the M+(TEP) complexes, transition states, intermediates, and products of the activated dissociation of these complexes. Theoretical AEs and BDEs are determined from single point energy calculations at the B3LYP/6-311+G(2d,2p) level using the B3LYP/6-31G* optimized geometries. The agreement between the calculated and measured AEs for elimination of C2H4 i...
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Modeling metal cation-Phosphate interactions in nucleic acids in the gas phase via alkali metal cation-Triethyl Phosphate complexes.
Journal of Physical Chemistry A, 2007Co-Authors: Chunhai Ruan, H Huang, M T RodgersAbstract:Threshold collision-induced dissociation techniques are employed to determine the bond dissociation energies (BDEs) of complexes of alkali metal cations, Na+, K+, Rb+, and Cs+, to Triethyl Phosphate (TEP). The primary and lowest energy dissociation pathway in all cases is the endothermic loss of the neutral TEP ligand. Theoretical electronic structure calculations at the B3LYP/6-311+G(2d,2p)//B3LYP/6-31G* level of theory are used to determine the structures, molecular parameters, and theoretical estimates for the BDEs of these complexes. For the complexes to Rb+ and Cs+, theoretical calculations were performed using hybrid basis sets in which the effective core potentials and valence basis sets of Hay and Wadt were used to describe the alkali metal cation, while the standard basis sets were used for all other atoms. The agreement between theory and experiment is excellent for the complexes to Na+ and K+ and is somewhat less satisfactory for the complexes to the heavier alkali metal cations, Rb+ and Cs+, w...
Daniel J. Haders - One of the best experts on this subject based on the ideXlab platform.
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Phase-sequenced deposition of calcium titanate/hydroxyapatite films with controllable crystallographic texture onto Ti6Al4V by Triethyl Phosphate-regulated hydrothermal crystallization
Crystal Growth & Design, 2009Co-Authors: Daniel J. Haders, Alexander Burukhin, Yizhong Huang, David J. H. Cockayne, Richard E. RimanAbstract:The aim of this study was to investigate the use of Triethyl Phosphate (TEP) to regulate the hydrothermal crystallization of hydroxyapatite (HA) films onto Ti6Al4V substrates. The growth mechanism of the HA film and the development of [0001] HA crystallographic texture were studied. Films were crystallized in a 0.232 m Ca(NO3)2−0.232 m EDTA−0.187 m TEP−1.852 m KOH−H2O chemical system with a final isothermal temperature of 200 °C, and then evaluated at synthesis times from 0 to 46 h by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and X-ray pole figures. Thermodynamic phase stability diagrams were calculated to validate experimental findings. XRD, FESEM, TEM, and EDX results demonstrated the crystallization of a CaTiO3 film below 180 °C and a HA film above 180 °C. FESEM and X-ray pole figure analysis revealed a refinement of the orientation of the (0002) HA crystallographic plane and the c-axis o...
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phase sequenced deposition of calcium titanate hydroxyapatite films with controllable crystallographic texture onto ti6al4v by Triethyl Phosphate regulated hydrothermal crystallization
Crystal Growth & Design, 2009Co-Authors: Daniel J. Haders, Alexander Burukhin, Yizhong Huang, David J. H. Cockayne, Richard E. RimanAbstract:The aim of this study was to investigate the use of Triethyl Phosphate (TEP) to regulate the hydrothermal crystallization of hydroxyapatite (HA) films onto Ti6Al4V substrates. The growth mechanism of the HA film and the development of [0001] HA crystallographic texture were studied. Films were crystallized in a 0.232 m Ca(NO3)2−0.232 m EDTA−0.187 m TEP−1.852 m KOH−H2O chemical system with a final isothermal temperature of 200 °C, and then evaluated at synthesis times from 0 to 46 h by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and X-ray pole figures. Thermodynamic phase stability diagrams were calculated to validate experimental findings. XRD, FESEM, TEM, and EDX results demonstrated the crystallization of a CaTiO3 film below 180 °C and a HA film above 180 °C. FESEM and X-ray pole figure analysis revealed a refinement of the orientation of the (0002) HA crystallographic plane and the c-axis o...
