Design de composites verts pour la dépollution des terres agricoles : expérience et théorie

Layered silicates like smectites are important soil components. Many works have been devoted to functionalize these materials in order to increase their chelating properties which may help retain heavy metals. It is well known that Cd2+, Hg2+, Pb2+, Co2+ and Zn2+ forms stable complexes with sulfur-containing organic ligands like cysteine. The first step of this work was the preparation of cysteine-montmorillonite composite through procedures that are well mastered. The second step was the study of the capacity of these composite materials to adsorb heavy metal cations. The chemical data demonstrates that the amount of cysteine detected on montmorillonite increases rapidly during the first few hours to attain a plateau after 24h. A comparison between the chelating properties of the resulting hybrid inorganic-organic materials and the pure montmorillonite was carried out for the following heavy metal cations Cd2+, Hg2+, Pb2+, Co2+ and Zn2+. It appears that the adsorption capacity of both materials is comparable. However, in release experiments, the heavy metal cations are more strongly retained by the hybrid material. Thermogravimetric analysis shows a special behavior with mercury and copper cations. Interactions between the hybrid clay mineral and the inorganic hosts were studied by spectroscopic methods such as solid-state NMR and FTIR. The experimental data were interpreted and supported by the use of theoretical periodic DFT calculations. Experiments with co-adsorption of heavy metal cations and emergent pollutants were also conducted. Interactions between the pollutants and the composite were highlighted by spectroscopic techniques.Des matériaux verts biodégradables à base de Montmorillonite et de cystéine ont été préparés dans le but de co-adsorber des cations de métaux lourds et des polluants émergeants en combinant l’expérience et la théorie (calculs DFT). Les analyses thermiques différentielles ont permis d’estimer le pourcentage d’eau et de matière organique, informations indispensables permettant de lancer les calculs théoriques. La première étape a consisté en l’adsorption des cations de métaux lourds tels que Pb2+, Cu2+, Co2+, Zn2+ et Hg2+ par le composite montmorillonite-cystéine et leurs caractérisations physico-chimiques. La deuxième étape a consisté à co-adsorber le sulfadiazine dans le composite montmorillonite-cystéine-cation de métal lourd. La spectroscopie de résonance magnétique du 13C nous a permis d’identifier les composites où une réaction de complexation s’est produite : En effet des décalages importants dans le déplacement chimique sont observés dans ce dernier cas. Parallèlement à cette partie expérimentale, la modélisation moléculaire nous a permis de calculer les énergies des différents complexes formés. Nous avons ainsi pu estimer le complexe le plus stable à partir des énergies obtenues. Un bon accord entre les résultats expérimentaux et théoriques a été obtenu. Des études de relargage à force ionique contrôlée ont été effectuées. Les résultats ont montré une bonne rétention des divers polluants en présence de cystéine

Design of green composite for the decontamination of agricultural land : experimental and theoretical

Des matériaux verts biodégradables à base de Montmorillonite et de cystéine ont été préparés dans le but de co-adsorber des cations de métaux lourds et des polluants émergeants en combinant l’expérience et la théorie (calculs DFT). Les analyses thermiques différentielles ont permis d’estimer le pourcentage d’eau et de matière organique, informations indispensables permettant de lancer les calculs théoriques. La première étape a consisté en l’adsorption des cations de métaux lourds tels que Pb2+, Cu2+, Co2+, Zn2+ et Hg2+ par le composite montmorillonite-cystéine et leurs caractérisations physico-chimiques. La deuxième étape a consisté à co-adsorber le sulfadiazine dans le composite montmorillonite-cystéine-cation de métal lourd. La spectroscopie de résonance magnétique du 13C nous a permis d’identifier les composites où une réaction de complexation s’est produite : En effet des décalages importants dans le déplacement chimique sont observés dans ce dernier cas. Parallèlement à cette partie expérimentale, la modélisation moléculaire nous a permis de calculer les énergies des différents complexes formés. Nous avons ainsi pu estimer le complexe le plus stable à partir des énergies obtenues. Un bon accord entre les résultats expérimentaux et théoriques a été obtenu. Des études de relargage à force ionique contrôlée ont été effectuées. Les résultats ont montré une bonne rétention des divers polluants en présence de cystéine.Layered silicates like smectites are important soil components. Many works have been devoted to functionalize these materials in order to increase their chelating properties which may help retain heavy metals. It is well known that Cd2+, Hg2+, Pb2+, Co2+ and Zn2+ forms stable complexes with sulfur-containing organic ligands like cysteine. The first step of this work was the preparation of cysteine-montmorillonite composite through procedures that are well mastered. The second step was the study of the capacity of these composite materials to adsorb heavy metal cations. The chemical data demonstrates that the amount of cysteine detected on montmorillonite increases rapidly during the first few hours to attain a plateau after 24h. A comparison between the chelating properties of the resulting hybrid inorganic-organic materials and the pure montmorillonite was carried out for the following heavy metal cations Cd2+, Hg2+, Pb2+, Co2+ and Zn2+. It appears that the adsorption capacity of both materials is comparable. However, in release experiments, the heavy metal cations are more strongly retained by the hybrid material. Thermogravimetric analysis shows a special behavior with mercury and copper cations. Interactions between the hybrid clay mineral and the inorganic hosts were studied by spectroscopic methods such as solid-state NMR and FTIR. The experimental data were interpreted and supported by the use of theoretical periodic DFT calculations. Experiments with co-adsorption of heavy metal cations and emergent pollutants were also conducted. Interactions between the pollutants and the composite were highlighted by spectroscopic techniques

Impact of manual thrombectomy on myocardial reperfusion as assessed by ST-segment resolution in STEMI patients treated by primary PCI

SummaryBackgroundIn STEMI patients treated by primary PCI, damage of the microvascular circulation caused by distal embolization of thrombotic material affects the quality of myocardial reperfusion. Important controversies remain concerning the usefulness of the manual thrombectomy to improve myocardial perfusion. The aim of this study is to evaluate the impact of manual thrombectomy on ST resolution as a surrogate of reperfusion extent.MethodsTwo hundred and thirty-nine consecutive STEMI patients with an <12hours onset of symptoms, were enrolled in an observational registry. Patients were divided into two cohorts according to the reperfusion strategy: manual thrombectomy before primary PCI (n=102) or conventional-PCI (n=137). The primary endpoint was the post procedural frequency of complete (>70%) resolution of ST segment elevation.ResultsA complete resolution of ST segment elevation occurred in 51.4% of patients in the thrombectomy group and in 35,6% of those in the conventional-PCI group (P=0.018). Thrombectomy strategy was associated with a lower use of stents. Multivariate analysis identified manual thrombectomy (HR=2.08 IC 95% (1.01–4.26); P=0.046), inferior location and short ischemic delay (<180min) as independent predictors of ST resolution. The cumulative Kaplan-Meier estimate of MACE was not significantly different between the two groups at one, three years follow-up.ConclusionIn STEMI patients, manual thrombectomy improves myocardial reperfusion as assessed by the percentage of ST segment resolution and a lower use of stents. However, in this cohort of limited size, this strategy did not translate into an improved cardiovascular outcome at one year follow-up

Cysteine-montmorillonite composites for heavy metal cation complexation: A combined experimental and theoretical study

International audienceGreen composites based on montmorillonite (Mt) and cysteine, were prepared for heavy metal removal. A comparison between the adsorption properties of the resulting hybrid inorganic-organic materials and the pure montmorillonite was carried out for the following heavy metal cations Cd2+, Hg2+, Pb2+, Co2+ and Zn2+. It appears that the adsorption capacity is higher on the composite. Moreover, in release experiments, the heavy metal cations are more strongly retained by the hybrid material. Interactions between the hybrid clay mineral and the inorganic hosts were studied by spectroscopic methods such as solid-state NMR (Nuclear Magnetic Resonance) and FTIR (Fourier Transform Infrared). The experimental data were in agreement with the theoretical periodic DFT (Density Functional Theory) calculations where a molecular picture of the adsorption complex is proposed

Adsorption of l-DOPA Intercalated in Hydrated Na-Saponite Clay: A Combined Experimental and Theoretical Study

International audienceThe intercalation of L-DOPA into the interlayer space of saponite, a 2:1 phyllosilicate, and the nature of host−guest interactions are investigated by a combined experimental and theoretical approach. L-DOPA zwitterions are accommodated vertically in the interlayer region as a bilayer of partially interdigitated species. The hydration state of the nanocomposite as well as the interaction geometry of L-DOPA molecules in the clay interlayer, are determined by periodic DFT calculations and found to be in agreement with experimentally obtained data. New insights into the transport properties for biomolecules in saponite are discussed