The Experts below are selected from a list of 254214 Experts worldwide ranked by ideXlab platform
I. Deniau - One of the best experts on this subject based on the ideXlab platform.
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determination of kinetic parameters and simulation of early co2 production from the boom clay kerogen under low thermal stress
Applied Geochemistry, 2005Co-Authors: I. Deniau, C. Beaucaire, Claude Largeau, Francoise Behar, Pierre De Canniere, H. PitschAbstract:Abstract The main purpose of the present study is to evaluate the nature and amount of gaseous compounds that would be generated from the Boom Clay kerogen due to the foreseen thermal stress associated with the geological disposal of high Activity Nuclear waste. To this end, pyrolysis experiments were carried out on this low maturity, O-rich kerogen with focus on mild conditions, including Rock–Eval and closed pyrolyses using a wide range of temperature/time conditions. The residual kerogen recovered after the closed pyrolyses was re-examined by Rock–Eval and elemental analyses and the components of the gas fractions were identified and quantified by gas chromatography. These experiments showed substantial production of CO 2 (corresponding to ca. 1/5 of the total O content of the kerogen) under mild thermal stress. The kinetic parameters (frequency factor and distribution of activation energy) of this early production of CO 2 were determined and used to simulate the possible consequences for the deep disposal of highly radioactive waste. Extrapolation to thermal stresses, corresponding to 80 and 100 °C over 1 ka, indicated that this production of CO 2 might influence the geochemistry and perhaps therefore the effectiveness of the geological barrier. For example, unless diffusion out of the heated zone counterbalances the effect of CO 2 generation, significant acidification and large changes in bicarbonate concentration may take place, in the interstitial water of the clay, at a time scale of only tens to a few hundred years.
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simulation of thermal stress influence on the boom clay kerogen oligocene belgium in relation to long term storage of high Activity Nuclear waste i study of generated soluble compounds
Applied Geochemistry, 2005Co-Authors: I. Deniau, Sylvie Derenne, C. Beaucaire, H. Pitsch, Claude LargeauAbstract:Abstract Closed pyrolyses were performed on the Boom Clay kerogen to simulate the weak thermal stress applied during the in situ CERBERUS heating experiment (80 °C for 5 a). Two stronger thermal stresses, encompassing the range generally considered for the long-term disposal of high-Activity Nuclear waste (80 °C for 1 ka and 120 °C for 3 ka), were also simulated. Quantitative and qualitative studies were carried out on the products thus generated with a focus on the C12+ fraction, especially on its polar components. It thus appeared that the soluble C12+ fractions generated during these simulation experiments comprise a wide variety of polar O- and/or N-containing compounds, including carboxylic acids and phenols. The nature and/or the relative abundance of these polar compounds exhibit strong variations, with the extent of the thermal stress, reflecting the primary cracking of different types of structures with different thermal stability and the occurrence of secondary degradation reactions. These observations support the idea that the compounds, generated upon exposure of the Boom Clay kerogen to a low to moderate thermal stress, may affect the effectiveness of the geological barrier upon long-term storage of high-Activity Nuclear waste.
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Occurrence and nature of thermolabile compounds in the Boom Clay kerogen (Oligocene, underground Mol Laboratory, Belgium)
Organic Geochemistry, 2004Co-Authors: I. Deniau, Sylvie Derenne, C. Beaucaire, H. Pitsch, Claude LargeauAbstract:Abstract The Boom Clay Formation has been selected as a model for studying the long term disposal of high Activity Nuclear waste in clay. During the resulting storage, the immature kerogen in the clay would be subjected to thermal stress and some of the products which could be generated might affect the efficiency of the geological barrier. The kerogen isolated from a representative clay sample, collected in the underground laboratory of the Nuclear Energy Research Centre at Mol (Belgium), was subjected to short heating at 300 °C to examine the thermolabile fraction released. The fraction contains a wide variety of components including hydrocarbons, ketones, alkanoic acids, phenols, furans and pyrroles. Information about the origin of these compounds was obtained through comparison with the bitumen and with the previously examined pyrolysis products generated from the kerogen at higher temperature (400 °C). The thermolabile fraction appears to correspond to “free” compounds trapped in the macromolecular structure of the kerogen and “labile” moieties linked by covalent bonds with a relatively low thermal stability. The study affords additional information on the sources and composition of the kerogen. Furthermore, the thermolabile components in the Boom Clay kerogen might affect the effectiveness of the clay barrier when subjected to thermal stress, especially through the release of oxygen-containing products, like carboxylic acids and phenols, that might complex released radioactive elements.
Claude Largeau - One of the best experts on this subject based on the ideXlab platform.
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improved kinetic modeling of the early generation of co2 from the boom clay kerogen implications for simulation of co2 production upon disposal of high Activity Nuclear waste
Organic Geochemistry, 2008Co-Authors: Francois Lorant, Claude Largeau, Francoise Behar, Pierre De CanniereAbstract:Abstract A new kinetic model accounting for the generation of “early” CO 2 from kerogen within the Boom Clay Formation (Oligocene, Belgium) was developed and calibrated using a large set of experimental pyrolysis data. The model also was constrained by the present day temperature of the clay where no CO 2 generation is assumed. The kinetic scheme involved three competitive reactions characterized by relatively low activation energies, i.e., E a 2 per gram of organic carbon. Focusing on the fastest reaction specifically, this study showed that the earliest stage of CO 2 formation is associated with the thermal decomposition of moieties containing activated carboxylic acid functions present in the thermolabile fraction of the kerogen. Considering the temperature elevation within the Boom Clay Formation that would be imposed by the presence of a Nuclear waste repository, the kinetic model predicts that (i) CO 2 release would start about 1 year after disposal, and might reach the limits of the clay layer after about 100 years and (ii) for each meter length of gallery, the absolute cumulative mass of CO 2 generated in a radius of 50 m around the gallery might reach ca. 3 tons.
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determination of kinetic parameters and simulation of early co2 production from the boom clay kerogen under low thermal stress
Applied Geochemistry, 2005Co-Authors: I. Deniau, C. Beaucaire, Claude Largeau, Francoise Behar, Pierre De Canniere, H. PitschAbstract:Abstract The main purpose of the present study is to evaluate the nature and amount of gaseous compounds that would be generated from the Boom Clay kerogen due to the foreseen thermal stress associated with the geological disposal of high Activity Nuclear waste. To this end, pyrolysis experiments were carried out on this low maturity, O-rich kerogen with focus on mild conditions, including Rock–Eval and closed pyrolyses using a wide range of temperature/time conditions. The residual kerogen recovered after the closed pyrolyses was re-examined by Rock–Eval and elemental analyses and the components of the gas fractions were identified and quantified by gas chromatography. These experiments showed substantial production of CO 2 (corresponding to ca. 1/5 of the total O content of the kerogen) under mild thermal stress. The kinetic parameters (frequency factor and distribution of activation energy) of this early production of CO 2 were determined and used to simulate the possible consequences for the deep disposal of highly radioactive waste. Extrapolation to thermal stresses, corresponding to 80 and 100 °C over 1 ka, indicated that this production of CO 2 might influence the geochemistry and perhaps therefore the effectiveness of the geological barrier. For example, unless diffusion out of the heated zone counterbalances the effect of CO 2 generation, significant acidification and large changes in bicarbonate concentration may take place, in the interstitial water of the clay, at a time scale of only tens to a few hundred years.
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simulation of thermal stress influence on the boom clay kerogen oligocene belgium in relation to long term storage of high Activity Nuclear waste i study of generated soluble compounds
Applied Geochemistry, 2005Co-Authors: I. Deniau, Sylvie Derenne, C. Beaucaire, H. Pitsch, Claude LargeauAbstract:Abstract Closed pyrolyses were performed on the Boom Clay kerogen to simulate the weak thermal stress applied during the in situ CERBERUS heating experiment (80 °C for 5 a). Two stronger thermal stresses, encompassing the range generally considered for the long-term disposal of high-Activity Nuclear waste (80 °C for 1 ka and 120 °C for 3 ka), were also simulated. Quantitative and qualitative studies were carried out on the products thus generated with a focus on the C12+ fraction, especially on its polar components. It thus appeared that the soluble C12+ fractions generated during these simulation experiments comprise a wide variety of polar O- and/or N-containing compounds, including carboxylic acids and phenols. The nature and/or the relative abundance of these polar compounds exhibit strong variations, with the extent of the thermal stress, reflecting the primary cracking of different types of structures with different thermal stability and the occurrence of secondary degradation reactions. These observations support the idea that the compounds, generated upon exposure of the Boom Clay kerogen to a low to moderate thermal stress, may affect the effectiveness of the geological barrier upon long-term storage of high-Activity Nuclear waste.
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Occurrence and nature of thermolabile compounds in the Boom Clay kerogen (Oligocene, underground Mol Laboratory, Belgium)
Organic Geochemistry, 2004Co-Authors: I. Deniau, Sylvie Derenne, C. Beaucaire, H. Pitsch, Claude LargeauAbstract:Abstract The Boom Clay Formation has been selected as a model for studying the long term disposal of high Activity Nuclear waste in clay. During the resulting storage, the immature kerogen in the clay would be subjected to thermal stress and some of the products which could be generated might affect the efficiency of the geological barrier. The kerogen isolated from a representative clay sample, collected in the underground laboratory of the Nuclear Energy Research Centre at Mol (Belgium), was subjected to short heating at 300 °C to examine the thermolabile fraction released. The fraction contains a wide variety of components including hydrocarbons, ketones, alkanoic acids, phenols, furans and pyrroles. Information about the origin of these compounds was obtained through comparison with the bitumen and with the previously examined pyrolysis products generated from the kerogen at higher temperature (400 °C). The thermolabile fraction appears to correspond to “free” compounds trapped in the macromolecular structure of the kerogen and “labile” moieties linked by covalent bonds with a relatively low thermal stability. The study affords additional information on the sources and composition of the kerogen. Furthermore, the thermolabile components in the Boom Clay kerogen might affect the effectiveness of the clay barrier when subjected to thermal stress, especially through the release of oxygen-containing products, like carboxylic acids and phenols, that might complex released radioactive elements.
Michael Karin - One of the best experts on this subject based on the ideXlab platform.
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ionizing radiation and short wavelength uv activate nf κb through two distinct mechanisms
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Michael KarinAbstract:We examined the mechanisms by which two different types of photonic radiation, short wavelength UV (UV-C) and γ radiation, activate transcription factor NF-κB. Exposure of mammalian cells to either form of radiation resulted in induction with similar kinetics of NF-κB DNA binding Activity, Nuclear translocation of its p65(RelA) subunit, and degradation of the major NF-κB inhibitor IκBα. In both cases, induction of NF-κB Activity was attenuated by proteasome inhibitors and a mutation in ubiquitin-activating enzyme, suggesting that both UV-C and γ radiation induce degradation of IκBs by means of the ubiquitin/proteasome pathway. However, although the induction of IκBα degradation by γ rays was dependent on its phosphorylation at Ser-32 and Ser-36, UV-C-induced IκBα degradation was not dependent on phosphorylation of these residues. Even the “super repressor” IκBα mutant, which contains alanines at positions 32 and 36, was still susceptible to UV-C-induced degradation. Correspondingly, we found that γ radiation led to activation of IKK, the protein kinase that phosphorylates IκBα at Ser-32 and Ser-36, whereas UV-C radiation did not. Furthermore, expression of a catalytically inactive IKKβ mutant prevented NF-κB activation by γ radiation, but not by UV-C. These results indicate that γ radiation and UV-C activate NF-κB through two distinct mechanisms.
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ionizing radiation and short wavelength uv activate nf kappab through two distinct mechanisms
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Michael KarinAbstract:We examined the mechanisms by which two different types of photonic radiation, short wavelength UV (UV-C) and γ radiation, activate transcription factor NF-κB. Exposure of mammalian cells to either form of radiation resulted in induction with similar kinetics of NF-κB DNA binding Activity, Nuclear translocation of its p65(RelA) subunit, and degradation of the major NF-κB inhibitor IκBα. In both cases, induction of NF-κB Activity was attenuated by proteasome inhibitors and a mutation in ubiquitin-activating enzyme, suggesting that both UV-C and γ radiation induce degradation of IκBs by means of the ubiquitin/proteasome pathway. However, although the induction of IκBα degradation by γ rays was dependent on its phosphorylation at Ser-32 and Ser-36, UV-C-induced IκBα degradation was not dependent on phosphorylation of these residues. Even the “super repressor” IκBα mutant, which contains alanines at positions 32 and 36, was still susceptible to UV-C-induced degradation. Correspondingly, we found that γ radiation led to activation of IKK, the protein kinase that phosphorylates IκBα at Ser-32 and Ser-36, whereas UV-C radiation did not. Furthermore, expression of a catalytically inactive IKKβ mutant prevented NF-κB activation by γ radiation, but not by UV-C. These results indicate that γ radiation and UV-C activate NF-κB through two distinct mechanisms.
H. Pitsch - One of the best experts on this subject based on the ideXlab platform.
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determination of kinetic parameters and simulation of early co2 production from the boom clay kerogen under low thermal stress
Applied Geochemistry, 2005Co-Authors: I. Deniau, C. Beaucaire, Claude Largeau, Francoise Behar, Pierre De Canniere, H. PitschAbstract:Abstract The main purpose of the present study is to evaluate the nature and amount of gaseous compounds that would be generated from the Boom Clay kerogen due to the foreseen thermal stress associated with the geological disposal of high Activity Nuclear waste. To this end, pyrolysis experiments were carried out on this low maturity, O-rich kerogen with focus on mild conditions, including Rock–Eval and closed pyrolyses using a wide range of temperature/time conditions. The residual kerogen recovered after the closed pyrolyses was re-examined by Rock–Eval and elemental analyses and the components of the gas fractions were identified and quantified by gas chromatography. These experiments showed substantial production of CO 2 (corresponding to ca. 1/5 of the total O content of the kerogen) under mild thermal stress. The kinetic parameters (frequency factor and distribution of activation energy) of this early production of CO 2 were determined and used to simulate the possible consequences for the deep disposal of highly radioactive waste. Extrapolation to thermal stresses, corresponding to 80 and 100 °C over 1 ka, indicated that this production of CO 2 might influence the geochemistry and perhaps therefore the effectiveness of the geological barrier. For example, unless diffusion out of the heated zone counterbalances the effect of CO 2 generation, significant acidification and large changes in bicarbonate concentration may take place, in the interstitial water of the clay, at a time scale of only tens to a few hundred years.
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simulation of thermal stress influence on the boom clay kerogen oligocene belgium in relation to long term storage of high Activity Nuclear waste i study of generated soluble compounds
Applied Geochemistry, 2005Co-Authors: I. Deniau, Sylvie Derenne, C. Beaucaire, H. Pitsch, Claude LargeauAbstract:Abstract Closed pyrolyses were performed on the Boom Clay kerogen to simulate the weak thermal stress applied during the in situ CERBERUS heating experiment (80 °C for 5 a). Two stronger thermal stresses, encompassing the range generally considered for the long-term disposal of high-Activity Nuclear waste (80 °C for 1 ka and 120 °C for 3 ka), were also simulated. Quantitative and qualitative studies were carried out on the products thus generated with a focus on the C12+ fraction, especially on its polar components. It thus appeared that the soluble C12+ fractions generated during these simulation experiments comprise a wide variety of polar O- and/or N-containing compounds, including carboxylic acids and phenols. The nature and/or the relative abundance of these polar compounds exhibit strong variations, with the extent of the thermal stress, reflecting the primary cracking of different types of structures with different thermal stability and the occurrence of secondary degradation reactions. These observations support the idea that the compounds, generated upon exposure of the Boom Clay kerogen to a low to moderate thermal stress, may affect the effectiveness of the geological barrier upon long-term storage of high-Activity Nuclear waste.
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Occurrence and nature of thermolabile compounds in the Boom Clay kerogen (Oligocene, underground Mol Laboratory, Belgium)
Organic Geochemistry, 2004Co-Authors: I. Deniau, Sylvie Derenne, C. Beaucaire, H. Pitsch, Claude LargeauAbstract:Abstract The Boom Clay Formation has been selected as a model for studying the long term disposal of high Activity Nuclear waste in clay. During the resulting storage, the immature kerogen in the clay would be subjected to thermal stress and some of the products which could be generated might affect the efficiency of the geological barrier. The kerogen isolated from a representative clay sample, collected in the underground laboratory of the Nuclear Energy Research Centre at Mol (Belgium), was subjected to short heating at 300 °C to examine the thermolabile fraction released. The fraction contains a wide variety of components including hydrocarbons, ketones, alkanoic acids, phenols, furans and pyrroles. Information about the origin of these compounds was obtained through comparison with the bitumen and with the previously examined pyrolysis products generated from the kerogen at higher temperature (400 °C). The thermolabile fraction appears to correspond to “free” compounds trapped in the macromolecular structure of the kerogen and “labile” moieties linked by covalent bonds with a relatively low thermal stability. The study affords additional information on the sources and composition of the kerogen. Furthermore, the thermolabile components in the Boom Clay kerogen might affect the effectiveness of the clay barrier when subjected to thermal stress, especially through the release of oxygen-containing products, like carboxylic acids and phenols, that might complex released radioactive elements.
C. Beaucaire - One of the best experts on this subject based on the ideXlab platform.
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determination of kinetic parameters and simulation of early co2 production from the boom clay kerogen under low thermal stress
Applied Geochemistry, 2005Co-Authors: I. Deniau, C. Beaucaire, Claude Largeau, Francoise Behar, Pierre De Canniere, H. PitschAbstract:Abstract The main purpose of the present study is to evaluate the nature and amount of gaseous compounds that would be generated from the Boom Clay kerogen due to the foreseen thermal stress associated with the geological disposal of high Activity Nuclear waste. To this end, pyrolysis experiments were carried out on this low maturity, O-rich kerogen with focus on mild conditions, including Rock–Eval and closed pyrolyses using a wide range of temperature/time conditions. The residual kerogen recovered after the closed pyrolyses was re-examined by Rock–Eval and elemental analyses and the components of the gas fractions were identified and quantified by gas chromatography. These experiments showed substantial production of CO 2 (corresponding to ca. 1/5 of the total O content of the kerogen) under mild thermal stress. The kinetic parameters (frequency factor and distribution of activation energy) of this early production of CO 2 were determined and used to simulate the possible consequences for the deep disposal of highly radioactive waste. Extrapolation to thermal stresses, corresponding to 80 and 100 °C over 1 ka, indicated that this production of CO 2 might influence the geochemistry and perhaps therefore the effectiveness of the geological barrier. For example, unless diffusion out of the heated zone counterbalances the effect of CO 2 generation, significant acidification and large changes in bicarbonate concentration may take place, in the interstitial water of the clay, at a time scale of only tens to a few hundred years.
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simulation of thermal stress influence on the boom clay kerogen oligocene belgium in relation to long term storage of high Activity Nuclear waste i study of generated soluble compounds
Applied Geochemistry, 2005Co-Authors: I. Deniau, Sylvie Derenne, C. Beaucaire, H. Pitsch, Claude LargeauAbstract:Abstract Closed pyrolyses were performed on the Boom Clay kerogen to simulate the weak thermal stress applied during the in situ CERBERUS heating experiment (80 °C for 5 a). Two stronger thermal stresses, encompassing the range generally considered for the long-term disposal of high-Activity Nuclear waste (80 °C for 1 ka and 120 °C for 3 ka), were also simulated. Quantitative and qualitative studies were carried out on the products thus generated with a focus on the C12+ fraction, especially on its polar components. It thus appeared that the soluble C12+ fractions generated during these simulation experiments comprise a wide variety of polar O- and/or N-containing compounds, including carboxylic acids and phenols. The nature and/or the relative abundance of these polar compounds exhibit strong variations, with the extent of the thermal stress, reflecting the primary cracking of different types of structures with different thermal stability and the occurrence of secondary degradation reactions. These observations support the idea that the compounds, generated upon exposure of the Boom Clay kerogen to a low to moderate thermal stress, may affect the effectiveness of the geological barrier upon long-term storage of high-Activity Nuclear waste.
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Occurrence and nature of thermolabile compounds in the Boom Clay kerogen (Oligocene, underground Mol Laboratory, Belgium)
Organic Geochemistry, 2004Co-Authors: I. Deniau, Sylvie Derenne, C. Beaucaire, H. Pitsch, Claude LargeauAbstract:Abstract The Boom Clay Formation has been selected as a model for studying the long term disposal of high Activity Nuclear waste in clay. During the resulting storage, the immature kerogen in the clay would be subjected to thermal stress and some of the products which could be generated might affect the efficiency of the geological barrier. The kerogen isolated from a representative clay sample, collected in the underground laboratory of the Nuclear Energy Research Centre at Mol (Belgium), was subjected to short heating at 300 °C to examine the thermolabile fraction released. The fraction contains a wide variety of components including hydrocarbons, ketones, alkanoic acids, phenols, furans and pyrroles. Information about the origin of these compounds was obtained through comparison with the bitumen and with the previously examined pyrolysis products generated from the kerogen at higher temperature (400 °C). The thermolabile fraction appears to correspond to “free” compounds trapped in the macromolecular structure of the kerogen and “labile” moieties linked by covalent bonds with a relatively low thermal stability. The study affords additional information on the sources and composition of the kerogen. Furthermore, the thermolabile components in the Boom Clay kerogen might affect the effectiveness of the clay barrier when subjected to thermal stress, especially through the release of oxygen-containing products, like carboxylic acids and phenols, that might complex released radioactive elements.
