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Aqueous solubility of some natural phenolic compounds / Fatima L. Mota in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5182–5189 Titre : Aqueous solubility of some natural phenolic compounds Type de document : texte imprimé Auteurs : Fatima L. Mota, Auteur ; António J. Queimada, Auteur ; Simao P. Pinho, Auteur ; Eugénia A. Macedo, Auteur Année de publication : 2008 Article en page(s) : p. 5182–5189 Note générale : Bibliogr. p. 5188-5189 Langues : Anglais (eng) Mots-clés : Hydroxybenzoic  acids;  Phenylpropenoic  acids;  Shake-flask  method Résumé : In this work, the aqueous solubilities of two hydroxybenzoic acids (gallic and salicylic acid) and three phenylpropenoic acids (trans-cinnamic, ferulic, and caffeic acids) are addressed. Measurements were performed, as a function of temperature, between 288.15 and 323.15 K, using the shake-flask method for generating the saturated aqueous solutions, followed by compositional analysis by spectrophotometric and gravimetric methods. The pH values of the saturated aqueous solutions were measured by potentiometry. Additional thermodynamic properties, which are fundamental for a better understanding of the solubilization process, as well as necessary for the modeling studies, such as melting temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC). Apparent acid dissociation constants (Ka) were obtained by potentiometry titration. The measured data were modeled with the cubic-plus-association (CPA) equation of state (EoS). This EoS is applied, for the first time, for multifunctional associating molecules, and the results indicate that it can adequately be used to represent the measured and other literature data with satisfactory accuracy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071452o [article] Aqueous solubility of some natural phenolic compounds [texte imprimé] / Fatima L. Mota, Auteur ; António J. Queimada, Auteur ; Simao P. Pinho, Auteur ; Eugénia A. Macedo, Auteur . - 2008 . - p. 5182–5189. Bibliogr. p. 5188-5189 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5182–5189 Mots-clés : Hydroxybenzoic  acids;  Phenylpropenoic  acids;  Shake-flask  method Résumé : In this work, the aqueous solubilities of two hydroxybenzoic acids (gallic and salicylic acid) and three phenylpropenoic acids (trans-cinnamic, ferulic, and caffeic acids) are addressed. Measurements were performed, as a function of temperature, between 288.15 and 323.15 K, using the shake-flask method for generating the saturated aqueous solutions, followed by compositional analysis by spectrophotometric and gravimetric methods. The pH values of the saturated aqueous solutions were measured by potentiometry. Additional thermodynamic properties, which are fundamental for a better understanding of the solubilization process, as well as necessary for the modeling studies, such as melting temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC). Apparent acid dissociation constants (Ka) were obtained by potentiometry titration. The measured data were modeled with the cubic-plus-association (CPA) equation of state (EoS). This EoS is applied, for the first time, for multifunctional associating molecules, and the results indicate that it can adequately be used to represent the measured and other literature data with satisfactory accuracy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071452o

Evaluation of group-contribution methods to predict VLE and odor intensity of fragrances / Miguel A. Teixeira in Industrial & engineering chemistry research, Vol. 50 N° 15 (Août 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 15 (Août 2011) . - pp. 9390-9402 Titre : Evaluation of group-contribution methods to predict VLE and odor intensity of fragrances Type de document : texte imprimé Auteurs : Miguel A. Teixeira, Auteur ; Oscar Rodriguez, Auteur ; Fatima L. Mota, Auteur Année de publication : 2011 Article en page(s) : pp. 9390-9402 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Odor  Group  contribution  method Résumé : Several predictive GE methods based on the group-contribution concept have been tested for prediction of multicomponent vapor-liquid equilibria (VLE) of fragrance mixtures. The evaluation covered 24 binary, 20 ternary, and 21 quaternary mixtures combining six different fragrances typically used in perfume formulation and ethanol as the solvent. The selected predictive methods are the original UNIFAC (updated to the last revision), the UNIFAC-Dortmund, the ASOG, and the A-UNIFAC. The equilibrium compositions were experimentally measured at 23 °C by headspace gas chromatography (HS-GC). For each liquid composition, the corresponding experimental and predicted vapor compositions were compared. This study confirmed that the UNIFAC method is the best predictive model for prediction of VLE, while the A-UNIFAC performed poorer than other evaluated methods for the mixtures studied in this work. Moreover, from the vapor composition the odor intensity and character of the fragrance mixtures was calculated using a previous developed model which considers the Stevens' power law for the olfaction intensity scale and the stronger component model for quality perception. In this way, the odor intensity and character of fragrance mixtures was predicted and compared to experimental and sensorial evaluations. From this work it can be concluded that the UNIFAC and UNIFAC-Dortmund methods allow obtaining optimal predictions of the character of the fragrance mixtures with an agreement of 95.4% when compared to experimental measurements. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24395884 [article] Evaluation of group-contribution methods to predict VLE and odor intensity of fragrances [texte imprimé] / Miguel A. Teixeira, Auteur ; Oscar Rodriguez, Auteur ; Fatima L. Mota, Auteur . - 2011 . - pp. 9390-9402. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 15 (Août 2011) . - pp. 9390-9402 Mots-clés : Odor  Group  contribution  method Résumé : Several predictive GE methods based on the group-contribution concept have been tested for prediction of multicomponent vapor-liquid equilibria (VLE) of fragrance mixtures. The evaluation covered 24 binary, 20 ternary, and 21 quaternary mixtures combining six different fragrances typically used in perfume formulation and ethanol as the solvent. The selected predictive methods are the original UNIFAC (updated to the last revision), the UNIFAC-Dortmund, the ASOG, and the A-UNIFAC. The equilibrium compositions were experimentally measured at 23 °C by headspace gas chromatography (HS-GC). For each liquid composition, the corresponding experimental and predicted vapor compositions were compared. This study confirmed that the UNIFAC method is the best predictive model for prediction of VLE, while the A-UNIFAC performed poorer than other evaluated methods for the mixtures studied in this work. Moreover, from the vapor composition the odor intensity and character of the fragrance mixtures was calculated using a previous developed model which considers the Stevens' power law for the olfaction intensity scale and the stronger component model for quality perception. In this way, the odor intensity and character of fragrance mixtures was predicted and compared to experimental and sensorial evaluations. From this work it can be concluded that the UNIFAC and UNIFAC-Dortmund methods allow obtaining optimal predictions of the character of the fragrance mixtures with an agreement of 95.4% when compared to experimental measurements. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24395884

Kinetic and stability study of the peroxidase inhibition in ionic liquids / Aristides P. Carneiro in Industrial & engineering chemistry research, Vol. 48 N° 24 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 10810–10815 Titre : Kinetic and stability study of the peroxidase inhibition in ionic liquids Type de document : texte imprimé Auteurs : Aristides P. Carneiro, Auteur ; Oscar Rodriguez, Auteur ; Fatima L. Mota, Auteur Année de publication : 2010 Article en page(s) : pp. 10810–10815 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Kinetic--Stability--Peroxidase--Inhibition--Ionic--Liquids Résumé : The activity and stability of peroxidase in aqueous solutions of two ionic liquids (ILs) have been studied. The ILs selected were 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate, [emim][MDEGSO4], and 1-ethyl-3-methylimidazolium ethylsulfate, [emim][EtSO4]. Experiments were performed at room temperature using concentrations of ILs between 5 and 50% (v/v) and pH values in the range from 5 to 9. The initial activity of the enzyme in these ILs at optimized conditions (pH 7 and 5−10% IL) was similar or higher than that achieved with buffer solution. Kinetic studies showed that maximum reaction velocity (Vmax) decreased with increasing concentration of IL. The effect of [emim][EtSO4] concentration on the decrease of Vmax was higher than that of [emim][MDEGSO4]. It was found that [emim][EtSO4] was a more potent inhibitor on peroxidase activity. The peroxidase studied was active in the ILs investigated, and the enzyme exhibited a higher stability in ILs at the optimized conditions. Kinetic studies showed that inhibition was a noncompetitive type in both ILs. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9007612 [article] Kinetic and stability study of the peroxidase inhibition in ionic liquids [texte imprimé] / Aristides P. Carneiro, Auteur ; Oscar Rodriguez, Auteur ; Fatima L. Mota, Auteur . - 2010 . - pp. 10810–10815. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 10810–10815 Mots-clés : Kinetic--Stability--Peroxidase--Inhibition--Ionic--Liquids Résumé : The activity and stability of peroxidase in aqueous solutions of two ionic liquids (ILs) have been studied. The ILs selected were 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate, [emim][MDEGSO4], and 1-ethyl-3-methylimidazolium ethylsulfate, [emim][EtSO4]. Experiments were performed at room temperature using concentrations of ILs between 5 and 50% (v/v) and pH values in the range from 5 to 9. The initial activity of the enzyme in these ILs at optimized conditions (pH 7 and 5−10% IL) was similar or higher than that achieved with buffer solution. Kinetic studies showed that maximum reaction velocity (Vmax) decreased with increasing concentration of IL. The effect of [emim][EtSO4] concentration on the decrease of Vmax was higher than that of [emim][MDEGSO4]. It was found that [emim][EtSO4] was a more potent inhibitor on peroxidase activity. The peroxidase studied was active in the ILs investigated, and the enzyme exhibited a higher stability in ILs at the optimized conditions. Kinetic studies showed that inhibition was a noncompetitive type in both ILs. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9007612

Kinetic and stability study of the peroxidase inhibition in ionic liquids / Aristides P. Carneiro in Industrial & engineering chemistry research, Vol. 48 N° 24 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 10810–10815 Titre : Kinetic and stability study of the peroxidase inhibition in ionic liquids Type de document : texte imprimé Auteurs : Aristides P. Carneiro, Auteur ; Oscar Rodriguez, Auteur ; Fatima L. Mota, Auteur Année de publication : 2010 Article en page(s) : pp. 10810–10815 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ionic  liquids  Peroxidase  Kinetic  study  Stability  study Résumé : The activity and stability of peroxidase in aqueous solutions of two ionic liquids (ILs) have been studied. The ILs selected were 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate, [emim][MDEGSO4], and 1-ethyl-3-methylimidazolium ethylsulfate, [emim][EtSO4]. Experiments were performed at room temperature using concentrations of ILs between 5 and 50% (v/v) and pH values in the range from 5 to 9. The initial activity of the enzyme in these ILs at optimized conditions (pH 7 and 5−10% IL) was similar or higher than that achieved with buffer solution. Kinetic studies showed that maximum reaction velocity (Vmax) decreased with increasing concentration of IL. The effect of [emim][EtSO4] concentration on the decrease of Vmax was higher than that of [emim][MDEGSO4]. It was found that [emim][EtSO4] was a more potent inhibitor on peroxidase activity. The peroxidase studied was active in the ILs investigated, and the enzyme exhibited a higher stability in ILs at the optimized conditions. Kinetic studies showed that inhibition was a noncompetitive type in both ILs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9007612 [article] Kinetic and stability study of the peroxidase inhibition in ionic liquids [texte imprimé] / Aristides P. Carneiro, Auteur ; Oscar Rodriguez, Auteur ; Fatima L. Mota, Auteur . - 2010 . - pp. 10810–10815. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 10810–10815 Mots-clés : Ionic  liquids  Peroxidase  Kinetic  study  Stability  study Résumé : The activity and stability of peroxidase in aqueous solutions of two ionic liquids (ILs) have been studied. The ILs selected were 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate, [emim][MDEGSO4], and 1-ethyl-3-methylimidazolium ethylsulfate, [emim][EtSO4]. Experiments were performed at room temperature using concentrations of ILs between 5 and 50% (v/v) and pH values in the range from 5 to 9. The initial activity of the enzyme in these ILs at optimized conditions (pH 7 and 5−10% IL) was similar or higher than that achieved with buffer solution. Kinetic studies showed that maximum reaction velocity (Vmax) decreased with increasing concentration of IL. The effect of [emim][EtSO4] concentration on the decrease of Vmax was higher than that of [emim][MDEGSO4]. It was found that [emim][EtSO4] was a more potent inhibitor on peroxidase activity. The peroxidase studied was active in the ILs investigated, and the enzyme exhibited a higher stability in ILs at the optimized conditions. Kinetic studies showed that inhibition was a noncompetitive type in both ILs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9007612