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Your search keyword '"Siquet, Christophe"' showing total 16 results
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16 results on '"Siquet, Christophe"'

7. Lipophilic phenolic antioxidants: Correlation between antioxidant profile, partition coefficients and redox properties

Author

Roleira, Fernanda M.F., primary, Siquet, Christophe, additional, Orrù, Elizabeta, additional, Garrido, E. Manuela, additional, Garrido, Jorge, additional, Milhazes, Nuno, additional, Podda, Gianni, additional, Paiva-Martins, Fátima, additional, Reis, Salette, additional, Carvalho, Rui A., additional, Silva, Elisiário J. Tavares da, additional, and Borges, Fernanda, additional

Published
2010
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12. Insights into CO2and CH4Adsorption by Pristine and Aromatic Amine-Modified Periodic Mesoporous Phenylene-Silicas

Author

Lourenço, Mirtha A. O., Siquet, Christophe, Santos, João, Jorge, Miguel, Gomes, José R. B., and Ferreira, Paula

Abstract

The synthesis and characterization of pristine and amine-functionalized periodic mesoporous phenylene-silicas having different pore sizes are reported. We explore the potential of these materials for CO2/CH4separation, by studying the adsorption of pure CO2and pure CH4gases. The aminated periodic mesoporous phenylene-silica with the smallest pore size is the best adsorbent to CO2, presenting a Henry’s constant of 0.56 mol·kg–1·bar–1at 35 °C. However, the corresponding Henry’s constant for CH4is extremely low (0.06 mol·kg–1·bar–1at 35 °C). There is a direct correlation between the % of T2SMPsilanols species and the values of the Henry’s constants, which may be used to theoretically predict experimental CO2Henry’s constants of potential adsorbents.

Published
2016
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13. Interaction of CO2and CH4with Functionalized Periodic Mesoporous Phenylene–Silica: Periodic DFT Calculations and Gas Adsorption Measurements

Author

Lourenço, Mirtha A. O., Siquet, Christophe, Sardo, Mariana, Mafra, Luís, Pires, João, Jorge, Miguel, Pinto, Moisés L., Ferreira, Paula, and Gomes, José R. B.

Abstract

Nonfunctionalized and functionalized periodic mesoporous phenylene–silicas (Ph–PMOs) with different kinds of amine groups were prepared and their capacity to uptake CO2and CH4molecules were experimentally evaluated considering biogas upgrading. It was found that aminopropyl groups grafted to the free silanols of the Ph–PMO displayed the highest selectivity for CO2gas, adsorbing 26.1 times more CO2than CH4at 25 °C. The interaction effect of the surface of these materials with the CO2or CH4molecules was obtained through the calculation of the Henry constants, and the adsorption mechanisms involved were elucidated from density functional theory calculations. The good synergy between experimental gas adsorption and computational studies suggests that the latter can be used to guide the experimental synthesis of more effective materials. Thus, our computational studies were extended to PMOs with other functional groups having different polarity for predicting interaction energies with CO2and thus identifying the most promising candidates for experimental synthesis.

Published
2016
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16. Sensitive sequential injection determination of naproxen based on interaction with β-cyclodextrin

Author

Zisiou, Eftychia-Pavlina, Pinto, Paula C.A.G., Saraiva, M. Lúcia M.F.S., Siquet, Christophe, and Lima, José L.F.C.

Subjects
*SEQUENTIAL injection analysis, *NAPHTHALENEACETIC acid, *NONSTEROIDAL anti-inflammatory agents, *ANTIPYRETICS
Abstract

Abstract: A sensitive sequential injection analysis (SIA) methodology for the fluorimetric determination of naproxen is proposed. The developed automatic analytical procedure is based on the complexation of naproxen with β-cyclodextrin (β-CD) yielding an enhanced fluorimetric signal (λ ex =280nm, λ em =356nm). Linear calibration plots were obtained for naproxen concentrations up to 1×10−5 moll−1. The developed methodology exhibited a good precision, with a R.S.D.<2.1% (n =15). The detection limit of the determination was 1.9×10−7 moll−1 with a sampling rate of about 70h−1. The automatic method was applied to the determination of naproxen in pharmaceutical formulations. The obtained results were compared with those furnished by the reference procedure and the relative deviations were lower than 3.6%. No interference was found from the excipients usually used in solid pharmaceutical formulations. [Copyright &y& Elsevier]

Published
2005
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