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OBJECTIVES: Elderly patients show a higher incidence of ischemic and bleeding events after percutaneous transluminal coronary intervention (PCI). We sought to investigate outcomes in elderly patients treated with antithrombotic strategy guided by bleeding and ischemic risks after revascularization with last generation everolimus-eluting stent (EES).; METHODS: Prospective multicenter registry including patients over 75 years revascularized with EES and antithrombotic therapy guided by clinical presentation, PCI complexity and PRECISE DAPT score. Co-primary safety endpoints were: (1) composite of cardiac death, myocardial infarction and stent thrombosis and; (2) bleeding (BARC 2-5). Primary efficacy endpoint was target lesion revascularization. A matched group of patients revascularized with current drug-eluting stents and no such tailored antithrombotic therapy was used as control.; RESULTS: Finally, 1064 patients were included in SIERRA-75 cohort, 80.8 ± 4.2 years, 36.6% women, 71% acute coronary syndromes (ACS) and 53.6% complex PCI. Co-primary safety endpoint of major adverse cardiovascular events was met in 6.2%, co-primary safety endpoint of bleeding in 7.8% and primary efficacy endpoint of TKLR in 1.5%. The multivariable adjusted model showed no significant association of the prescribed short/long dual antiplatelet therapy (DAPT) durations with any endpoint suggesting a well tailored therapy. No stent thrombosis reported in the subgroup with 1-3 months DAPT duration. As compared to control group, bleeding BARC 2-5 was significantly lower in SIERRA-75 group (7.4% vs. 10.2%, P = 0.04) as well as the net safety-efficacy endpoint (14.3% vs. 18.5%, P = 0.02).; CONCLUSIONS: In elderly population, the application of this risks-adjusted antithrombotic protocol after revascularization with last generation EES seems to be associated with an improved prognosis in terms of ischemic and bleeding outcomes. Copyright and License information: Journal of Geriatric Cardiology 2022.

MICROSCOPIE+ATARI:CARE:ECI2D+GFE:MAO:FCA:CGE:SLO:PVE; International audience; The shape, size and electronic properties of Pt nanoparticles supported on ceria have been tailored during model redox sequences based on successive H2 (reduction) and O2 (oxidation) 1 hour treatments at moderate temperatures (250 °C and 500 °C). Raft shaped Pt nanoparticles of around 1 nm size are produced on the surface, in strong interaction with ceria, then boosting the oxygen transfer from the oxide towards Pt. In situ techniques establish the presence of Pt cations in an intermediate oxidation state, probably Pt2+, in interaction with peroxo oxygen species.

MICROSCOPIE+ATARI:CARE:ECI2D+GFE:MAO:FCA:CGE:SLO:PVE; International audience; 1.IntroductionThe tailoring of Pt based diesel oxidation catalysts is crucial to enhance the efficiency of the diesel vehicles after treatment. For instance, specific interactions between Pt and ceria can improve the thermal stability of Pt nanoparticles (NPs) in an oxidizing atmosphere as in diesel exhausts, through the formation of rigid Pt-O-Ce bonds.1 More recently, Jones et al.2 have evidenced stabilization of Pt single atoms and clusters on ceria surface steps, strongly suggesting the doping of ceria subsurface by Pt cations in good agreement with DFT studies3 which also predict Pt2+ cations incorporation between surface oxygen ions species of the support. We have recently demonstrated the dynamic nature of Pt NPs on ceria under reducing/oxidizing sequences at temperatures below 500 °C.4 Lean/rich pulses can be used to control the formation of Pt NPs and enhance their catalytic activity for CO oxidation.4 This study aims at getting new insights into the impact of redox sequences on the Pt and CeO2 interactions.2.Experimental/methodsCeria provided by Solvay Special Chem. Company was dry impregnated with Pt (0.9 wt %) and calcined 4 h at 500 °C. Before each characterization or catalytic test, the catalyst was systematically pretreated in O2 for 1 h at 500 °C to get a reference state. Model redox sequences were composed of a first reduction step of 1 h in 10% H2 followed by an oxidation one also of 1 h in 20% oxygen. They were performed at different temperatures: 500/500 °C (reduction/oxidation), 250/250 °C and 250 °C/RT. Catalytic performances were measured for CO and propylene oxidation in a lean mixture (10% O2, 1000 ppm CO, 500 ppm NO, 500 ppm C3H6, 10% H2O in He) that simulates diesel exhaust gas. Temperature-Programmed Reduction (TPR) experiments were conducted with a Inficon JPC400 mass spectrometer. STEM observations were performed with an Environmental Transmission Electron Microscope (Ly-ETEM, FEI TITAN ETEM operated at 300 kV). The spatial distribution of surface oxygen electrophilic species and PtOx clusters were assessed by Raman spectroscopy mapping at the micrometric level (200 µm x 200 µm) recorded at RT under oxygen flow. HRXANES was also implemented to in situ follow the oxidation degree of Ce cations in the catalyst.3.Results and discussionAs previously observed with rich/lean pulses,4 model redox sequences can achieve outstanding catalytic performances for CO and C3H6 oxidation, much higher than those recorded at the reference state. TPR experiments have shown that model redox sequences increase the reducibility of ceria. The H2 consumption only starts above 150 °C on the first TPR, suggesting the absence of Pt NPs able to chemisorb H2 below this temperature, as confirmed by STEM observations. Successive redox sequences (TPR 2 and TPR 3) promote the formation of Pt NPs in strong interaction with ceria as shown by the excellent reducibility of the support as early as the room temperature. The lower the temperature of the redox sequences, the greater the reducibility. Variations of the Raman band associated with PtOx at 690 cm-1 demonstrate that such species evolve upon redox sequences with stabilization of Pt cations in another oxidation state, probably Pt2+, as suggested by XPS measurements and DFT calculations.3 These Pt2+ cations are in interaction with peroxo oxygen species (Raman bands at 860 cm-1). No Ce3+ cations were detected both by electronic Raman spectroscopy and HR-XANES measurements, confirming that these oxygen peroxo species did not re-oxidized ceria but are stabilized on the surface.The shape of the Pt NPs was followed along the redox sequences. After the first reduction step, only raft shaped particles or single atoms are observed on the surface (Fig. 1c). This morphology is not modified after a subsequent oxidation step but the surface mean diameter of Pt rafts slightly increases from 1.0 to 1.3 nm, maybe due to Pt oxidation. Statistics on the ratio between the number of rafts and single atoms were tricky to estimate. However, CO chemisorption performed after each reduction step shows no significant modification of the Pt dispersion along the redox cycles.4.ConclusionsThis work showed that raft shaped Pt nanoparticles in closed interaction with ceria can be stabilized by model redox sequences at mild temperatures. This maximizes the Pt/ceria interface, promoting the oxygen transfer from the support towards Pt which is a key step in the CO oxidation mechanism. Pt cations are stabilized in an intermediate oxidation state, probably Pt2+, in interaction with peroxo oxygen species, confirming the high availability of oxygen species for oxidation reactions.AcknowledgementFrench National Research agency ‘Agence Nationale de la Recherche’ (ANR), project ORCA (ANR-14-CE22-0011-02) and German Federal Ministry for Economic Affairs and Energy (BMWi) are acknowledged for their financial support. The authors thank Solvay Special Chem Company for material contribution and the CLYM for access to the Ly-EtTEM.References[1]Y. Nagai, K. Dohmae, Y. Ikeda, N. Takagi, T. Tanabe, N. Hara, G. Guilera, S. Pascarelli, M.A. Newton, O. Kuno, H. Jiang, H. Shinjoh, S. Matsumoto, Angew. Chem., 2008, 47, 9303-9306.[2]J. Jones, H. Xiong, A.T. DeLaRiva, E.J. Peterson, H. Pham, S.R. Challa, G. Qi, S. Oh, M.H. Wiebenga, X.I. Pereira Hernández, Y. Wang, A.K. Datye, Science, 2016, 353, 6295.[3]A. Bruix, Y. Lykhach, I. Matolínová, Armin Neitzel, T. Skála, N. Tsud, M. Vorokhta, V. Stetsovych, K. Ševčiková, J. Mysliveček, R. Fiala, M. Václavů, K.C. Prince, S. Bruyère, V. Potin, F. Illas, V. Matolin, J. Libuda, K.M. Neyman, Angew. Chem., 2014, 53, 10525-10530.[4]A.M. Gänzler, M., Casapu, P. Vernoux, S. Loridant, F.J.C.S. Aires, T. Epicier, B. Betz, R. Hoyer, J.D. Grunwaldt, Angew. Chem., 2017, 56, 13078-13082.

SSCI-VIDE+CARE:ECI2D+GFE:SLO:PVE; National audience; Depuis plusieurs années, les normes européennes des émissions de NOx des véhicules diesel ne cessent de se renforcer. Parmi les solutions développées par les équipementiers, le procédé NOxTrap consiste à stocker et réduire les NOx au cours de cycles redox entre un mélange gazeux pauvre (échappement diesel) et riche en hydrocarbures. Les catalyseurs Pt/CeO2 servant à oxyder les imbrulés (CO, hydrocarbures) doivent être adaptés à l’application de ces cycles. Nous avons récemment montré la nature dynamique des nanoparticules (NP) de Pt sur l'oxyde de cérium lors de séquences réductrices/oxydantes à des températures inférieures à 500 °C. En outre, les impulsions pauvres/riches peuvent être utilisées pour contrôler la formation de Pt et améliorer leur activité catalytique pour l'oxydation de CO. Dans ce travail, les cycles redox sont simulés en alternant des traitements sous 10%H2 et 20%O2 à différentes températures. Parmi différentes techniques de caractérisation utilisées in situ, la spectroscopie Raman s’est avérée être clé pour mieux comprendre les évolutions structurales des catalyseurs Pt/CeO2 au cours de ces cycles redox. En particulier, la cartographie Raman in situ a permis de suivre la distribution des particules PtOx à l’échelle micrométrique. Cette méthodologie appliquée pour la première fois à l’étude de catalyseurs hétérogènes permet d’obtenir à la fois une information spatiale (Figure 1A) et statistique (Figure 1B) sur un paramètre spectroscopique donné. Il a ainsi été montré que les processus de dispersion et formation de particules s’opèrent à l’échelle micrométrique. De plus, l’évolution des bandes correspondant aux clusters PtOx (690 cm-1), des espèces oxygène peroxo (830 cm-1), de la bande de diffusion Raman électronique des cations Ce3+ (2100 cm-1) ont permis de mettre en évidence la stabilisation d’un état d’oxydation intermédiaire du Pt, probablement Pt2+, l’absence de cations Ce3+ et l’apparition d’espèces peroxo en surface de la cérine au cours de cycles redox. Cette stabilisation permettrait d’augmenter fortement l’activité oxydante des catalyseurs Pt/CeO2.RemerciementsLes auteurs remercient l‘Agence Nationale de la Recherche’ (ANR) pour le financement du projet ORCA (ANR-14-CE22-0011-02).Références1.A.M. Gänzler, M., Casapu, P. Vernoux, S. Loridant, F.J.C.S. Aires, T. Epicier, B. Betz, R. Hoyer, J.D. Grunwaldt, Angew. Chem., 2017, 56, 13078–13082.2.M. Daniel, S. Loridant, J. Raman Spectrosc. 2012, 43, 1312–1319.

MICROSCOPIE+ATARI:CARE:ECI2D+GFE:MAO:FCA:CGE:SLO:PVE; International audience; Due to European regulation on car exhausts, NOx emissions must be cut down. NOxTrap system stores NOx during lean phase as nitrates and during short rich phase triggered by pulses of gasoil, nitrates are decomposed and NOx reduced into N2. Our objective is to combine DOC (Diesel Oxidation Catalyst) and NOx storage-reduction in one catalytic system. This study reports the effect of redox rich/lean cycles on the catalytic activity of a model catalyst, Pt/CeO2. This activation step provokes a huge improvement of the catalytic performances for hydrocarbon and CO oxidation. Raman and ETEM experiments indicate a modification of platinum nanoparticles (NPs) dispersion on ceria at both micrometric and nanometric scales.1. ScopeEuropean environmental regulations on NOx emissions of mobile sources are becoming more and more severe. NOxTrap catalyst is one of the solution to reduce NOx into N2 under lean-burn conditions, such as for diesel engines. NOxTrap system works in cyclic gas-composition conditions. During the first step (lean phase), NOxTrap catalyst stores emitted NOx as nitrates until the surface reaches the saturation threshold. Then a pulse of fuel post-injection triggers the short second step (rich phase), during which the reducing conditions lead to nitrates decomposition, release as well as subsequent NOx reduction into N2 and surface regeneration. NOxTrap catalysts are commonly composed of Pt for its oxidative properties during lean phases; Rh to reduce NOx during rich phases; an alkaline compound as barium oxide and an oxide support. Ceria offers a high specific surface area support for metal dispersion, especially Pt, even at high temperature due to the strong interaction between Pt and CeO2.1 At low temperature (below 200 °C) its NOx storage capacity is higher than that of barium oxide.2 Our objective is to combine the oxidation function (DOC) and the NOx reduction ability into a single catalytic system through a fine NOxTrap catalyst formulation tuning. This study aims to understand the effect of redox rich/lean cycles at 250°C on the catalytic activity of a model catalyst, Pt/CeO2 (1wt% Pt) through in-situ characterizations. 2. Results and discussionCeria provided by Solvay Special Chem. Company was impregnated with platinum (1 wt %) by Umicore and then calcined 2 h at 500 °C. Catalytic performances show an important shift to lower temperatures of CO and C3H¬6 conversion after 1 h of cycles between lean (90 sec, 10% O2, 500 ppm NO, 1000 ppm CO, 500 ppm C3H6, 10 %H2O in He) and rich (30 sec, 2% CO in He) at 250 °C (figure 1) which simulates the NOxTrap process. Similar activation steps were achieved for lean/rich sequences up to 500°C. The origin of this activation was studied by in-situ Raman spectroscopy and Environmental Transmission Electron Microscopy (ETEM, FEI TITAN ETEM G2 80-300 kV and DENS Solution heating sampled holder) after rich/lean sequences at 500°C. Ceria defect band and platinum oxide dispersion was assessed by Raman spectroscopy mapping at the micrometric level (200 µm x 200 µm). Platinum oxides re-dispersion and increase of lattice defect in ceria were both highlighted after lean/rich sequences (Figure 2). ETEM was complementary used to in-situ follow the Pt NPs dispersion on ceria during lean (O2, 10 mBar)/rich (H2, 10 mBar) sequences at 500°C. Several areas of the catalyst were observed to achieve statistical data on the Pt NPs size distribution (Figure 3). Under O2, we have observed the disappearance of most of the small Pt NPs while the consecutive rich sequence evidenced their reappearance but not necessary at the same position. The comparison of the Pt NPs size distribution highlights the impact of lean/rich treatments on the Pt/CeO2 interactions. 3. ConclusionsIn-situ characterizations of a Pt/CeO2 catalyst by using Raman spectroscopy and Environmental TEM have clearly shown that rich/lean sequences can strongly modify the Pt NPs distribution on the support both at the micrometric and nanometric levels. Such a redox sequence seems to optimize the Pt dispersion on the ceria and consecutively improve the catalytic properties.Figure 2 : Comparison of the intensity distributions during mapping of (A) the PtOx band area at 690 cm-1 and (B) the lattice defect band area at 250 cm-1 at initial oxidized state (blue) and after two cycles of reduction ( 10% H2 – 500 °C – 1 h ) and oxidation (20 % O2 – 500 °C – 1 h) (orange). Figure 3 : ETEM pictures of one catalyst area during lean/rich sequences at 500 °C. White arrows indicate relevant NPs modifications.AcknowledgmentFrench National Research agency ‘Agence Nationale de la Recherche’ (ANR), project ORCA (ANR-14-CE22-0011-02) and German Federal Ministry for Economic Affairs and Energy (BMWi) are acknowledged for their financial support. The authors thank Solvay Special Chem. Company for material contribution and the CLYM for access to the Ly-EtTEM. References 1. R. Hoyer, A. Schuler, S. Franoschek, T.R. Pauly, G. Jeske, WO 2013/149881 A1, October 22, 20142. E. Rohart, V. Bellière-Baca, K. Yokota, V. Harlé, C. Pitois, Top. Catal. 2007, 42-43, 71–75.

International audience

SSCI-VIDE+ATARI:CARE:ECI2D+PVE:GFE:SLO:FCA; International audience; None

MICROSCOPIE+ATARI:CARE:ECI2D+GFE:MAO:FCA:CGE:SLO:PVE; National audience; Depuis plusieurs années, les normes européennes des émissions de NOx des véhicules diesel ne cessent de se renforcer. Plusieurs solutions ont été mises en place par les équipementiers pour relever le défi de la réduction des NOx en N2 dans l’environnement oxydant des échappements diesel. Le système de stockage et réduction des NOx, appelé NOxTrap, est un procédé cyclique entre des phases de stockage des NOx sous forme de nitrates (phase pauvre) jusqu’à saturation de la surface du catalyseur et des phases riches de quelques secondes déclenchées par une post-injection de gazole qui permettent la décomposition des nitrates et la réduction des NOx en N2 en régénérant ainsi la surface. Les catalyseurs NOxTrap sont généralement composés de Pt pour la fonction oxydation lors des phases pauvres, de Rh pour réduire les NOx au cours des phases riches, d’un composé basique pour le stockage des NOx comme l’oxyde de baryum et d’un support oxyde. L’utilisation de la cérine comme support offre l’avantage d’assurer une bonne dispersion des métaux, notamment du Pt, même à haute température grâce à la forte interaction Pt/CeO2. D’autre part, la cérine permet un stockage des NOx plus important que l’oxyde de baryum à des températures inférieures à 200 °C. Notre objectif technologique est de regrouper la fonction d’oxydation des imbrulés (DOC : Diesel Oxidation Catalyst) avec celle de réduction des NOx dans une seule brique catalytique en adaptant la formulation d’un catalyseur NOxTrap. Cette étude expose l’impact des cycles pauvre/riche du système NOxTrap sur la fonction d’oxydation catalytique des imbrûlés (hydrocarbures, CO) d’un catalyseur modèle Pt/CeO2 (1% Pt). La mesure des performances catalytiques a montré une forte diminution de la température de conversion du CO et du C3H6 après une séquence d’une heure de cycles pauvre (90 s) /riche (30 s) à 250 °C sensée simuler le fonctionnement NOxTrap. L’origine de cette activation a été étudiée in-situ par microscopie électronique en transmission environnementale (ETEM) et par spectroscopie Raman. L’ETEM a mis en évidence la redispersion des nanoparticules de Pt à l’échelle nanométrique suite aux enchainements de phases riches et pauvres. Des cartographies Raman in-situ réalisées au cours des cycles redox ont permis de montrer que les processus de diffusion liés à la redispersion des atomes de platine à la surface de la cérine s'opéraient à l'échelle micrométrique et induisaient une augmentation de la quantité de ses défauts structuraux. Une séquence redox à 250 °C permet d’optimiser la dispersion du Pt sur la cérine et par conséquent d’augmenter significativement l’activité catalytique du catalyseur pour les réactions d’oxydation.

MICROSCOPIE+ATARI:CARE:ECI2D+FCA:MAO:GFE:SLO:CGE:PVE:LMA:PGE; International audience; High spatial resolution studies of ceria and ceria based catalysts by aberration corrected Environmental Transmission Electron MicroscopyF.J. Cadete Santos Aires1, T. Epicier2, M. Bugnet2, M. Aouine1, Z.Wu3, A. Gänzler4, G. Ferré1, M. Casapu4, J.D. Grunwaldt4, S. Loridant1, C. Geantet1, P. Vernoux1, L. Massin1, P. Gélin11 Université de Lyon, UCBL Lyon 1, IRCELYON UMR 5256 CNRS, 2 Avenue Albert Einstein, 69626– Villeurbanne Cedex, France.2 Université de Lyon, INSA-Lyon, UCBL Lyon 1, MATEIS UMR 5510 CNRS, 7 Avenue Jean Capelle, 69626 – Villeurbanne Cedex, France.3 Chemical Science Division, Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.4 Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), Engesserstraße 20, 76131 Karlsruhe, Germany.Ceria (CeO2) is a rather versatile material extensively used in catalysis (as a catalyst or as a catalyst support) due to its redox properties and oxygen mobility capabilities. Despite exhaustive literature on its structural and chemical properties, in depth atomic scale surface analysis in environmental (realistic) conditions is lacking. This is essential to gain crucial, and otherwise unavailable, insight into the surface reactivity mechanisms driving the catalytic performance (activity, selectivity, stability, active sites and species, …). The advent of environmental transmission electron microscopes (ETEM) equipped withadvanced accessories such as an aberration corrector and a high speed camera opened these perspectives. It is now possible to follow in situ (variable P and T), almost in real-time and at subnanometer resolution the evolution of the morphology, the structure and the chemistry of the supported nanoparticles, of the support and of their interface. In particular, the termination of the surfaces, the mobility of the surface atoms, the local chemical composition and the redox state can be analysed down to the atomic level in most favourable cases.Here we present dynamic in situ studies dealing with issues directly related with the surface termination and mobility of ceria and with the evolution of metallic species supported on ceria for different catalyticapplications:(i) Atomic scale study of the surface mobility of CeO2 nanocubes under gaseous environments;(ii) Tuning in situ the noble metal dispersion in Pt/CeO2 diesel oxidation catalysts;(iii) Evolution of Ir/CeO2 catalysts during methane steam reforming.The studies were performed within the Ly-EtTEM (Lyon Environmental and tomographic Transmission Electron Microscope), a 80-300 kV TITAN objective lens Cs-corrected Environmental TEM from FEI, equipped with a GATAN high resolution Imaging Filter (GIF), a SDD XMaxN EDX spectrometer (Oxford Instruments) and a high-speed CCD Gatan OneViewTM camera, in varying pressure and temperature conditions using a Wildfire sample holder and SiNx nanochips from DENS Solutions.The authors are thankful for funding from INSA Lyon through a BQR project THERMOS, from the IMUST project at University of Lyon and IFPen (Solaize, F), from the German Federal Ministry for Economic Affairs and Energy (BMWi: 19U15014B) as well as from the DFG (High-Output Catalyst Development Platform, INST 121384/16-1), from the French National Research Agency for financial support of the ORCA and 3DCLEAN projects 14-CE22-0011-02 and 15-CE09-0009-0 respectively) and from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division. The electron microscopy work presented here was performed on a FEI Titan ETEM at the Centre Lyon–St-Etienne de Microscopie (www.clym.fr).

International audience

RX+CARE:ECI2D+GFE:AWS:FBS:SLO:CGE:PVE; International audience; 1. IntroductionEnvironmental regulations on NOx emissions of mobile sources are becoming increasingly demanding. The NOx storage-reduction (NSR) catalytic technology is one of the solution lean-burn engines. NSR catalysts work in cyclic gas-composition conditions. During the first step (lean phase), NSR materials store emitted NOx as nitrates until the surface reaches the saturation threshold. A pulse of fuel post-injection then triggers the short second step (rich phase), during which the reducing conditions lead to nitrate decomposition and release as well as subsequent NOx reduction into N2 and surface regeneration. Ceria is an interesting material since it plays a double function first as a high specific surface area support [1] for platinum group metal (PGM) dispersion and secondly as a NOx trap at low temperature until 350°C. Below 200°C, the NOx storage capacity of ceria is higher than that of barium which is commonly used as a storing agent [2]. In addition, ceria can limit the thermal sintering of Pt nanoparticles [3]. This study aims to deeply characterize the impact of the nature of dopant (Zr and Pr) on the redox properties of ceria-based oxides.2. Experimental/methodologyDifferent compositions of commercial ceria-based oxides were provided by the Solvay Special Chem Company : CeO2, Ce0.49Zr0.51O2 (CZ)) and Ce0,80Pr0,20O2 (CP20). All samples have been calcined at 800°C for 2 h. In-situ X-Ray Diffraction measurements were carried out in an atmosphere-controlled Anton Paar XRK 900 reactor chamber, either under air, N2 or H2, using a Versatile Panalytical X’Pert Pro MPD Diffractometer equipped with a diffracted beam graphite monochromator (Cu Kα radiation) and a 1-dimensional multistrip detector (X’Celerator). Diffractograms were collected at several temperatures from 25 to 750°C and crystallographic parameters were determined by the Rietveld method. Surface and bulk reducibility was characterized by Temperature-Programmed Reduction (TPR) in H2 from room temperature up to 850°C. Oxygen-Temperature-Programmed Desorption (TPD) experiments were also performed to quantify the surface reactivity of the different oxides toward oxygen. Oxygen was adsorbed at 500°C while the desorption was followed in He from RT up to 800°C with an heating ramp of 10°C/min. In-situ Raman spectroscopy was used to determine structural/electronic defects and surface oxygen species of the samples after reducing/oxidizing treatments. Spectra were recorded with a LabRam HR Raman spectrometer (Horiba-Jobin Yvon) at low temperature after oxidation or reduction at 525°C. Three exciting wavelengths were used (514, 633 and 785 nm) and the laser spot was focused using a ×50 long working distance objective. The in-situ Raman spectra were recorded using a THMS600 cell (Linkam) between -196°C and 525°C under 10 % H2-N2, N2 and 10% O2-N2.3. Results and discussionXRD patterns have evidenced the cubic structure (Fm-3m) for CeO2 and CP20 while CZ alsocontains a t’ tetragonal phase. The lattice parameters were extracted from in-situ patterns inair, N2 and H2 as a function of the temperature. The increase of the lattice parameter withrespect to the one measured in air at a given temperature was used to estimate the bulkreducibility. Figure 1a clearly shows that CP20 is reduced in pure H2 from 300°C, instead of400°C for CZ and above 700°C for CeO2. These results are in good agreement with TPRexperiments which evidenced that the surface reduction of doped ceria is promoted by theinsertion of Pr. By the same way during O2-TPD experiments, a low O2 desorption peakbelow 400°C was only observed on CP20. In addition, the capacity of the ceria oxide tochemisorb oxygen was strongly improved in the presence of Pr.Beyond confirming the XRD structural characterization, Raman mappings evidenced a highhomogeneity at the micrometer scale. Furthermore, structural defects and oxygen specieswere observed with this technique. In particular, Raman spectra of CP20 oxide highlighted adefects band at 570 cm-1 (Figure 1B) which can be explained by a resonance effect involvinga particular defect stabilized at the oxidized state. The reduction of cations contained in suchdefect modifies its electronic properties inhibiting the resonance effect. Concerning CZsupport, a typical band of Ce3+ was visible after reduction whereas peroxo species wereobserved after re-oxydation contrarily to the other solids.Figure 1. (A) Variation of the fluorite lattice parameter as a function of temperature in pure H2 (B) Evidence of a newdefects band enhanced by Raman Resonance effect for CP20.4. ConclusionStructure, surface and bulk properties of three different ceria oxides have been deeplyinvestigated in both oxidized and reduced states. The role of the dopants, i.e. Pr and Zr, onthe redox properties in cycling lean/rich conditions encountered in NSR processes will bediscussed.5. References[1] Z. Say, E.I. Vovk, V.I. Bukhtiyarov, E. Ozensoy, Appl. Catal. B Environ. 142-143 (2013) 89–100.[2] E. Rohart, V. Bellière-Baca, K. Yokota, V. Harlé, C. Pitois, Top. Catal. 42-43 (2007) 71–75.[3] Y. Nagai, T. Hirabayashi, K. Dohmae, N. Takagi, T. Minami, H. Shinjoh, S. Matsumoto, J. Catal. 242 (2006) 103–109.

RX+CARE:ECI2D+GFE:AWS:FBS:SLO:CGE:PVE; International audience; Environmental regulations on NOx emissions of mobile sources are becoming increasingly demanding. The NOx storage-reduction (NSR) catalytic technology is one of the solution lean-burn engines. NSR catalysts work in cyclic gas-composition conditions. During the first step (lean phase), NSR materials store emitted NOx as nitrates until the surface reaches the saturation threshold. A pulse of fuel post-injection then triggers the short second step (rich phase), during which the reducing conditions lead to nitrate decomposition and release as well as subsequent NOx reduction into N2 and surface regeneration. Ceria is an interesting material since it plays a double function first as a high specific surface area support1 for platinum group metal (PGM) dispersion and secondly as a NOx trap at low temperature until 350°C. Below 200°C, the NOx storage capacity of ceria is higher than that of barium which is commonly used as a storing agent2. In addition, ceria can limit the thermal sintering of Pt nanoparticles3. This study aims to deeply characterize the impact of the nature of dopant (Zr and Pr) on the redox properties of ceria-based oxides.

L’analyse des emplois prépositionnels et des emplois conjonctifs d’ “excepté”, de “sauf” et d’ “hormis” permet d’envisager les trois prépositions/conjonctions comme le pivot d’un binôme, comme la plaque tournante d’une structure bipolaire. Placées au milieu du binôme, ces prépositions sont forcées par leur sémantisme originaire dûment métaphorisé de jouer le rôle de marqueurs d’inconséquence systématique entre l’élément se trouvant à leur gauche et celui qui se trouve à leur droite. L’opposition qui surgit entre les deux éléments n’est donc pas une incompatibilité naturelle, intrinsèque, mais extrinsèque, induite. Dans la plupart des cas (emplois limitatifs), cette opposition prend la forme d’un rapport entre une « classe » et le « membre (soustrait) de la classe », ou bien entre un « tout » et une « partie » ; dans d’autres (emplois exceptifs), cette opposition se manifeste au contraire comme une attaque de front portée par un « tout » à un autre « tout ». De plus, l’inconséquence induite mise en place par la préposition/conjonction paraît, en principe, tout à fait insurmontable. Dans l’assertion « les écureuils vivent partout, sauf en Australie » (que l’on peut expliciter par « Les écureuils vivent partout, sauf [qu’ils ne vivent pas] en Australie »), la préposition semble en effet capable d’impliquer le prédicat principal avec signe inverti, et de bâtir sur une telle implication une sorte de sous énoncé qui, à la rigueur, est totalement inconséquent avec celui qui le précède (si « les écureuils ne vivent pas en Australie », le fait qu’ils « vivent partout » est faux). Néanmoins, l’analyse montre qu’alors que certaines de ces oppositions peuvent enfin être dépassées, d’autres ne le peuvent pas. C’est, respectivement, le cas des relations limitatives et des relations exceptives. La relation limitative, impliquant le rapport « tout » - « partie », permet de résoudre le conflit dans les termes d’une somme algébrique entre deux sous énoncés pourvus de différent poids informatif et de signe contraire. Les valeurs numériques des termes de la somme étant déséquilibrées, le résultat est toujours autre que zéro. La relation exceptive, au contraire, qui n’implique pas le rapport « tout » - « partie », n’est pas capable de résoudre le conflit entre deux sous énoncés pourvus du même poids informatif et en même temps de signe contraire : les valeurs numériques des termes de la somme étant symétriques et égales, le résultat sera toujours équivalent à zéro.

To significantly increase the sampling rate of an ADC, timeinterleaved ADC (TIADC) is an efficient solution. Due to the manufacturing process, the main drawback of a TIADC system is that the M ADCs, which compose this end, are not exactly the same. This means that offset, gain and time mismatch errors are introduced. These errors cause distortions in the output sampled signal and introduce unwanted tones and noise, and hence, reduce the spurious free dynamic range (SFDR) as well as the signal to noise ratio (SNR). In this paper, we propose a new orthogonal digital calibration implementation, for timing skew, offset and gain mismatches, based on Code Division Multiple Access (CDMA) technique. Our calibration is online, this means that errors can be estimated while the ADC is running. Since most of the calibration processes are carried out on the digital outputs, very little change is needed on the analog part of the ADC. Simulation and implementation results show respectively the efficiency of our proposed calibration algorithm and our hardware implementation.

Publication in the conference proceedings of EUSIPCO, Poznan, Poland, 2007