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Ji-ho Yoon - One of the best experts on this subject based on the ideXlab platform.
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Spectroscopic identification and conversion rate of gaseous guest-loaded Hydroquinone clathrates
Chemical Physics Letters, 2012Co-Authors: Jong-won Lee, Ki Jong Choi, Yongjae Lee, Ji-ho YoonAbstract:Abstract The formation of Hydroquinone clathrates with CO 2 , CH 4 , N 2 , and H 2 was investigated using X-ray diffraction, Raman spectroscopy, and solid-state 13 C NMR spectroscopy. Of the Hydroquinones prepared at 5.0 MPa, the CH 4 - and CO 2 -loaded Hydroquinones show complete conversion to β-form Hydroquinone clathrates while the N 2 -loaded Hydroquinone shows only partial conversion; there is no indication of the formation of Hydroquinone clathrate with H 2 . The CO 2 -loaded Hydroquinone is fully converted to the β-form Hydroquinone clathrate even at 1.0 MPa. Solid-state 13 C NMR measurements of the Hydroquinone clathrate samples prepared at different pressures reveal that the conversion rate for the formation of clathrate compounds from CH 4 and N 2 decreases with decreasing pressure.
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Characterization of Hydroquinone clathrates by THz time-domain spectroscopy
2009 34th International Conference on Infrared Millimeter and Terahertz Waves, 2009Co-Authors: Ji-ho Yoon, Jin-seok Jang, Tae-in JeonAbstract:Using terahertz time-domain spectroscopy (THz-TDS), we have measured the absorption spectra of α-Hydroquinone and methane- and methanol-loaded β-Hydroquinone clathrates up to 3 THz frequency range. The α-Hydroquinone exhibits 11 resonances whereas methane- and methanol-loaded β-Hydroquinone clathrates show only 1 resonance. The observed THz resonances represent the intermolecular and lattice vibrations of the Hydroquinone frameworks, but seem to be insensitive to the encaged guest species. The indices of refraction are found to be ca. 1.6 for α-Hydroquinone and methane-loaded β-Hydroquinone clathrate and 1.7 for methanol-loaded β-Hydroquinone clathrate, and the anomalous dispersions are well defined at the resonance frequencies.
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Characterization of α-Hydroquinone and β-Hydroquinone clathrates by THz time-domain spectroscopy
Chemical Physics Letters, 2009Co-Authors: Jin-seok Jang, Tae-in Jeon, Ji-ho YoonAbstract:Abstract We have measured the absorption spectra of α-Hydroquinone and methane- and methanol-loaded β-Hydroquinone clathrates up to 3 THz frequency range using terahertz time-domain spectroscopy (THz-TDS). The α-Hydroquinone exhibits 11 resonances whereas methane- and methanol-loaded β-Hydroquinone clathrates show only 1 resonance. The observed THz resonances represent the intermolecular and lattice vibrations of the Hydroquinone frameworks, but seem to be insensitive to the encaged guest species. The indices of refraction are found to be ca. 1.6 for α-Hydroquinone and methane-loaded β-Hydroquinone clathrate and 1.7 for methanol-loaded β-Hydroquinone clathrate, and the anomalous dispersions are well-defined at the resonance frequencies.
Jin-seok Jang - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Hydroquinone clathrates by THz time-domain spectroscopy
2009 34th International Conference on Infrared Millimeter and Terahertz Waves, 2009Co-Authors: Ji-ho Yoon, Jin-seok Jang, Tae-in JeonAbstract:Using terahertz time-domain spectroscopy (THz-TDS), we have measured the absorption spectra of α-Hydroquinone and methane- and methanol-loaded β-Hydroquinone clathrates up to 3 THz frequency range. The α-Hydroquinone exhibits 11 resonances whereas methane- and methanol-loaded β-Hydroquinone clathrates show only 1 resonance. The observed THz resonances represent the intermolecular and lattice vibrations of the Hydroquinone frameworks, but seem to be insensitive to the encaged guest species. The indices of refraction are found to be ca. 1.6 for α-Hydroquinone and methane-loaded β-Hydroquinone clathrate and 1.7 for methanol-loaded β-Hydroquinone clathrate, and the anomalous dispersions are well defined at the resonance frequencies.
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Characterization of α-Hydroquinone and β-Hydroquinone clathrates by THz time-domain spectroscopy
Chemical Physics Letters, 2009Co-Authors: Jin-seok Jang, Tae-in Jeon, Ji-ho YoonAbstract:Abstract We have measured the absorption spectra of α-Hydroquinone and methane- and methanol-loaded β-Hydroquinone clathrates up to 3 THz frequency range using terahertz time-domain spectroscopy (THz-TDS). The α-Hydroquinone exhibits 11 resonances whereas methane- and methanol-loaded β-Hydroquinone clathrates show only 1 resonance. The observed THz resonances represent the intermolecular and lattice vibrations of the Hydroquinone frameworks, but seem to be insensitive to the encaged guest species. The indices of refraction are found to be ca. 1.6 for α-Hydroquinone and methane-loaded β-Hydroquinone clathrate and 1.7 for methanol-loaded β-Hydroquinone clathrate, and the anomalous dispersions are well-defined at the resonance frequencies.
Francisco Guillen - One of the best experts on this subject based on the ideXlab platform.
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oxidation of Hydroquinones by the versatile ligninolytic peroxidase from pleurotus eryngii
FEBS Journal, 2001Co-Authors: Victor Gomeztoribio, Angel T Martinez, Maria Jesus Martinez, Francisco GuillenAbstract:Formation of H2O2 during the oxidation of three lignin-derived Hydroquinones by the ligninolytic versatile peroxidase (VP), produced by the white-rot fungus Pleurotus eryngii, was investigated. VP can oxidize a wide variety of phenols, including Hydroquinones, either directly in a manner similar to horseradish peroxidase (HRP), or indirectly through Mn3+ formed from Mn2+ oxidation, in a manner similar to manganese peroxidase (MnP). From several possible buffers (all pH 5), tartrate buffer was selected to study the oxidation of Hydroquinones as it did not support the Mn2+-mediated activity of VP in the absence of exogenous H2O2 (unlike glyoxylate and oxalate buffers). In the absence of Mn2+, efficient Hydroquinone oxidation by VP was dependent on exogenous H2O2. Under these conditions, semiquinone radicals produced by VP autoxidized to a certain extent producing superoxide anion radical ( –) that spontaneously dismutated to H2O2 and O2. The use of this peroxide by VP produced quinone in an amount greater than equimolar to the initial H2O2 (a quinone/H2O2 molar ratio of 1 was only observed under anaerobic conditions). In the presence of Mn2+, exogenous H2O2 was not required for complete oxidation of Hydroquinone by VP. Reaction blanks lacking VP revealed H2O2 production due to a slow conversion of Hydroquinone into semiquinone radicals (probably via autooxidation catalysed by trace amounts of free metal ions), followed by – production through semiquinone autooxidation and – reduction by Mn2+. This peroxide was used by VP to oxidize Hydroquinone that was mainly carried out through Mn2+ oxidation. By comparing the activity of VP to that of MnP and HRP, it was found that the ability of VP and MnP to oxidize Mn2+ greatly increased Hydroquinone oxidation efficiency.
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oxidation of Hydroquinones by the versatile ligninolytic peroxidase from pleurotus eryngii h2o2 generation and the influence of mn2
FEBS Journal, 2001Co-Authors: Victor Gomeztoribio, Angel T Martinez, Maria Jesus Martinez, Francisco GuillenAbstract:Formation of H2O2 during the oxidation of three lignin-derived Hydroquinones by the ligninolytic versatile peroxidase (VP), produced by the white-rot fungus Pleurotus eryngii, was investigated. VP can oxidize a wide variety of phenols, including Hydroquinones, either directly in a manner similar to horseradish peroxidase (HRP), or indirectly through Mn3+ formed from Mn2+ oxidation, in a manner similar to manganese peroxidase (MnP). From several possible buffers (all pH 5), tartrate buffer was selected to study the oxidation of Hydroquinones as it did not support the Mn2+-mediated activity of VP in the absence of exogenous H2O2 (unlike glyoxylate and oxalate buffers). In the absence of Mn2+, efficient Hydroquinone oxidation by VP was dependent on exogenous H2O2. Under these conditions, semiquinone radicals produced by VP autoxidized to a certain extent producing superoxide anion radical (O2*-) that spontaneously dismutated to H2O2 and O2. The use of this peroxide by VP produced quinone in an amount greater than equimolar to the initial H2O2 (a quinone/H2O2 molar ratio of 1 was only observed under anaerobic conditions). In the presence of Mn2+, exogenous H2O2 was not required for complete oxidation of Hydroquinone by VP. Reaction blanks lacking VP revealed H2O2 production due to a slow conversion of Hydroquinone into semiquinone radicals (probably via autooxidation catalysed by trace amounts of free metal ions), followed by O2*- production through semiquinone autooxidation and O2*- reduction by Mn2+. This peroxide was used by VP to oxidize Hydroquinone that was mainly carried out through Mn2+ oxidation. By comparing the activity of VP to that of MnP and HRP, it was found that the ability of VP and MnP to oxidize Mn2+ greatly increased Hydroquinone oxidation efficiency.
Tae-in Jeon - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Hydroquinone clathrates by THz time-domain spectroscopy
2009 34th International Conference on Infrared Millimeter and Terahertz Waves, 2009Co-Authors: Ji-ho Yoon, Jin-seok Jang, Tae-in JeonAbstract:Using terahertz time-domain spectroscopy (THz-TDS), we have measured the absorption spectra of α-Hydroquinone and methane- and methanol-loaded β-Hydroquinone clathrates up to 3 THz frequency range. The α-Hydroquinone exhibits 11 resonances whereas methane- and methanol-loaded β-Hydroquinone clathrates show only 1 resonance. The observed THz resonances represent the intermolecular and lattice vibrations of the Hydroquinone frameworks, but seem to be insensitive to the encaged guest species. The indices of refraction are found to be ca. 1.6 for α-Hydroquinone and methane-loaded β-Hydroquinone clathrate and 1.7 for methanol-loaded β-Hydroquinone clathrate, and the anomalous dispersions are well defined at the resonance frequencies.
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Characterization of α-Hydroquinone and β-Hydroquinone clathrates by THz time-domain spectroscopy
Chemical Physics Letters, 2009Co-Authors: Jin-seok Jang, Tae-in Jeon, Ji-ho YoonAbstract:Abstract We have measured the absorption spectra of α-Hydroquinone and methane- and methanol-loaded β-Hydroquinone clathrates up to 3 THz frequency range using terahertz time-domain spectroscopy (THz-TDS). The α-Hydroquinone exhibits 11 resonances whereas methane- and methanol-loaded β-Hydroquinone clathrates show only 1 resonance. The observed THz resonances represent the intermolecular and lattice vibrations of the Hydroquinone frameworks, but seem to be insensitive to the encaged guest species. The indices of refraction are found to be ca. 1.6 for α-Hydroquinone and methane-loaded β-Hydroquinone clathrate and 1.7 for methanol-loaded β-Hydroquinone clathrate, and the anomalous dispersions are well-defined at the resonance frequencies.
Victor Gomeztoribio - One of the best experts on this subject based on the ideXlab platform.
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oxidation of Hydroquinones by the versatile ligninolytic peroxidase from pleurotus eryngii
FEBS Journal, 2001Co-Authors: Victor Gomeztoribio, Angel T Martinez, Maria Jesus Martinez, Francisco GuillenAbstract:Formation of H2O2 during the oxidation of three lignin-derived Hydroquinones by the ligninolytic versatile peroxidase (VP), produced by the white-rot fungus Pleurotus eryngii, was investigated. VP can oxidize a wide variety of phenols, including Hydroquinones, either directly in a manner similar to horseradish peroxidase (HRP), or indirectly through Mn3+ formed from Mn2+ oxidation, in a manner similar to manganese peroxidase (MnP). From several possible buffers (all pH 5), tartrate buffer was selected to study the oxidation of Hydroquinones as it did not support the Mn2+-mediated activity of VP in the absence of exogenous H2O2 (unlike glyoxylate and oxalate buffers). In the absence of Mn2+, efficient Hydroquinone oxidation by VP was dependent on exogenous H2O2. Under these conditions, semiquinone radicals produced by VP autoxidized to a certain extent producing superoxide anion radical ( –) that spontaneously dismutated to H2O2 and O2. The use of this peroxide by VP produced quinone in an amount greater than equimolar to the initial H2O2 (a quinone/H2O2 molar ratio of 1 was only observed under anaerobic conditions). In the presence of Mn2+, exogenous H2O2 was not required for complete oxidation of Hydroquinone by VP. Reaction blanks lacking VP revealed H2O2 production due to a slow conversion of Hydroquinone into semiquinone radicals (probably via autooxidation catalysed by trace amounts of free metal ions), followed by – production through semiquinone autooxidation and – reduction by Mn2+. This peroxide was used by VP to oxidize Hydroquinone that was mainly carried out through Mn2+ oxidation. By comparing the activity of VP to that of MnP and HRP, it was found that the ability of VP and MnP to oxidize Mn2+ greatly increased Hydroquinone oxidation efficiency.
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oxidation of Hydroquinones by the versatile ligninolytic peroxidase from pleurotus eryngii h2o2 generation and the influence of mn2
FEBS Journal, 2001Co-Authors: Victor Gomeztoribio, Angel T Martinez, Maria Jesus Martinez, Francisco GuillenAbstract:Formation of H2O2 during the oxidation of three lignin-derived Hydroquinones by the ligninolytic versatile peroxidase (VP), produced by the white-rot fungus Pleurotus eryngii, was investigated. VP can oxidize a wide variety of phenols, including Hydroquinones, either directly in a manner similar to horseradish peroxidase (HRP), or indirectly through Mn3+ formed from Mn2+ oxidation, in a manner similar to manganese peroxidase (MnP). From several possible buffers (all pH 5), tartrate buffer was selected to study the oxidation of Hydroquinones as it did not support the Mn2+-mediated activity of VP in the absence of exogenous H2O2 (unlike glyoxylate and oxalate buffers). In the absence of Mn2+, efficient Hydroquinone oxidation by VP was dependent on exogenous H2O2. Under these conditions, semiquinone radicals produced by VP autoxidized to a certain extent producing superoxide anion radical (O2*-) that spontaneously dismutated to H2O2 and O2. The use of this peroxide by VP produced quinone in an amount greater than equimolar to the initial H2O2 (a quinone/H2O2 molar ratio of 1 was only observed under anaerobic conditions). In the presence of Mn2+, exogenous H2O2 was not required for complete oxidation of Hydroquinone by VP. Reaction blanks lacking VP revealed H2O2 production due to a slow conversion of Hydroquinone into semiquinone radicals (probably via autooxidation catalysed by trace amounts of free metal ions), followed by O2*- production through semiquinone autooxidation and O2*- reduction by Mn2+. This peroxide was used by VP to oxidize Hydroquinone that was mainly carried out through Mn2+ oxidation. By comparing the activity of VP to that of MnP and HRP, it was found that the ability of VP and MnP to oxidize Mn2+ greatly increased Hydroquinone oxidation efficiency.
