Spectroscopic investigation of Titania-supported gold nanoparticles prepared by a modified deposition/precipitation method for the oxidation of CO

The spectroscopic characterization of a material is a fundamental tool for understanding the structure–activity correlation for catalytic purposes. Regarding supported nanoparticles, this perspective has acquired more relevance in recent years and several techniques have been employed. In this work diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), coupled with CO adsorption, was used to investigate a modified deposition/precipitation method (DP-UC) for the preparation of supported gold nanoparticles with very low metal loading (0.1–0.5 wt %). This promising synthetic route involves the use of urea as basic agent and NaBH4 as chemical reductant in contrast to the traditional high-temperature reduction step. The systematic IR spectroscopic study of the Au loading was combined with CO oxidation catalytic tests. The evaluation of the results was also supported by several other techniques, such as X-ray photoelectron spectroscopy, N2 physisorption, and transmission electron microscopy. Particular attention was given to the evaluation of the gold electronic state, surface dispersion, particle size, and the corresponding structure–activity relationship

Glycerol Oxidation Using MgO‐and Al2O3‐supported Gold and Gold–Palladium Nanoparticles Prepared in the Absence of Polymer Stabilizers

Au and AuPd nanoparticles supported on MgO and Al2O3 supports were employed for the selective aqueous phase oxidation of glycerol under basic conditions. Catalysts were prepared by sol-immobilisation without the addition of a stabilizing agent such as polyvinyl alcohol (PVA), which is generally added to stabilize the noble metal sol prior to immobilisation on. The obtained materials prepared with and without stabilizing agent were active for glycerol oxidation and showed similar catalytic performances - implying that the stabilizing polymer is not required to obtain active materials. Depending on the support used, it was possible to tailor the selectivity towards desired oxidation products by using catalysts prepared with or without stabilizing agent. PVA-free Au/ Al2O3 exhibited a remarkably high selectivity towards tartronic acid (40% at 97% conversion), which was not observed for the analogous sample prepared with PVA. Selective glycerol oxidation performed under base-free conditions over AuPd/MgO catalysts also corroborated the previous results that the presence of a stabilizing polymer is not required to prepare active catalysts by sol-immobilisation. Thus, a facile way is presented herein to circumvent the inherent drawbacks encountered by the use of polymer stabilizers during catalyst preparation and the experimental results in fact suggest that the presence of the polymer stabilisers can affect the reaction pathways and control selectivity

Améliorer l'accès à l'innovation par la pénétration des biosimilaires : exemple du trastuzumab

Face à l’arrivée d’innovations thérapeutiques de plus en plus coûteuses la promotion des biosimilaires est devenue un enjeu de santé publique. Cette stratégie a pour but d’améliorer l’accès à un traitement déjà existant tout en limitant les dépenses de santé, et ainsi libérer des ressources pour financer les nouvelles innovations. Dans ce travail, nous nous sommes intéressés au trastuzumab. L’état des lieux national de son utilisation a révélé que la pénétration du trastuzumab biosimilaire était encourageante (36%) et associée à une diminution significative des dépenses liées au trastuzumab (16%) malgré une consommation en hausse (21%). Nous avons pu également identifier un frein à la progression des biosimilaires du trastuzumab. En effet, l’Herceptin SC est utilisé de façon non pertinente en association avec d’autres chimiothérapies IV (26%). Face à ces constats, une étude médico-économique a été réalisée afin de déterminer la stratégie optimale à adopter afin de favoriser la pénétration des biosimilaires tout en limitant l’impact sur l’organisation des HDJ. Une première simulation a permis de mesurer les conséquences du remplacement de l’Herceptin SC utilisé en polychimiothérapie par un biosimilaire. Les économies générées ont été évaluées à 874€/patient/an associées à augmentation du temps de séjour en HDJ de 10 minutes/patient/an. Dans une seconde simulation, nous avons associé à la première simulation le remplacement en monothérapie du trastuzumab IV par de l’Herceptin SC. Cela a permis de générer une économie de 704€/patient/an associée à une diminution du temps de séjour en HDJ de 78 minutes/patient/an. Ces études ont mis en évidence le cout-efficacité de la valorisation des biosimilaires dans les établissements de santé. D’autres pistes telles que l’administration de l’Herceptin SC en HAD ou les auto-administrations pourraient être explorées

El hombre ante la medicina

Port. a dúas tinta

Le fournil. : Du grain au pain, aux Moulins Bourgeois (Verdelot, Seine-et-Marne, France)

Mouette BARBOFF, docteur en ethnologie de l'EHESS - Ecole des Hautes Etudes en Sciences Sociales de Paris, et Présidente de l'association "L'Europe, Civilisation du Pain", nous entraîne ici à la découverte d'une minoterie familiale en Ile-de-France, Les Moulins Bourgeois. De la sélection des blés - achetés dans un rayon de 150 km autour du moulin (Brie, Gâtinais, Beauce, Champagne) -, précédant la production de farine - livrée à près de 500 artisans-boulangers, situés en zone rurale et urbaine, dans un rayon de 200 km autour du moulin -, jusqu'aux stages proposés pour former des artisans-boulangers d'Ile-de-France aux savoir-faire de la boulangerie traditionnelle et dispensés par un expert sur le site, les Moulins Bourgeois apparaissent comme un outil de production moderne, en constante évolution technique pour garantir qualité, sécurité et traçabilité des produits

CO 2 ‐to‐HCOOH Electrochemical Conversion on Nanostructured Cu x Pd 100−x /Carbon Catalysts

International audienceSelective electrochemical conversion of CO2 to HCOOH is obtained at the surface of a carbon-supported bimetallic cathode material composed of copper and palladium nanoparticles. Polycrystalline copper or large copper particles are well-known to catalyze CO2 reduction to hydrocarbons at relatively negative potentials, or when their surface is covered by copper oxides (Cu2O and CuO). Cu-based materials modified by various palladium contents (0<×<100), were synthesized by using the microwave-assisted polyol method to serve as a cathode in the selective CO2-into-HCOOH transformation. Herein, we developed a targeted preparation route toward the metal content/catalytic activity relationship correlating atomic ratio with faradaic efficiency (FE) to formate formation (ca. 60 % FE) at −0.72 V vs. RHE, which represents a 703 mV overpotential at pH=7. Consequently, the occurrence of this reduction reaction slows down the parallel H2 production from the solvent consumption, while the neighboring Cu−Pd provides excellent activity and a good efficiency toward CO2 reduction via the hydridation of the CO2 molecule to orientate the reaction to formate rather than carbon monoxide or H2 evolution

New Preparation of PdNi/C and PdAg/C Nanocatalysts for Glycerol Electrooxidation in Alkaline Medium

International audienc

Electrochemical activity of ruthenium and iridium based catalysts for oxygen evolution reaction

International audiencedecomposition process. The suitable heat treatment of the polymeric precursors allowed to recover metal oxides free from organic carbon, which can be oxidized to carbon dioxide during H2O splitting at elevated potentials. The materials were examined by various physicochemical techniques in order to understand their electrochemical behavior as anodes in a 5 cm(2) single proton exchange membrane water electrolyzer. Although the presence of Ir in the electrocatalyst composition contributes undoubtedly to its stability against ruthenium dissolution and the Faradaic efficiency of the PEM electrolysis cell, its great amount increases the overpotential value. The activity of the home made RuxIr1-xO2 anodes towards the oxygen evolution reaction occurs at ca. 1.5 Vat 25 degrees C