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International audience; The adsorption of Ir adatoms on Al(100) has been investigated under various exposures and temperature conditions. The experimental and theoretical results reveal a diffusion of Ir adatoms within the Al(100) surface selvedge already at 300 K. Above 593 K, two domains of a (√ 5× √ 5)R26.6 • phase are identified by low energy electron diffraction (LEED) and scanning tunneling microscopy measurements. This phase corresponds to the initial growth of an Al 9 Ir 2 compound at the Al(100) surface. The Al 9 Ir 2 intermetallic domains are terminated by bulklike pure Al layers. The structural stability of Al 9 Ir 2 (001) grown on Al(100) has been analyzed by density functional theory based calculations. Dynamical LEED analysis is consistent with an Ir adsorption leading to the growth of an Al 9 Ir 2 intermetallic compound. We propose that the epitaxial relationship Al 9 Ir 2 (001)Al(100) and Al 9 Ir 2 [100]Al[031]/[013] originates from a matching of Al atomic arrangements present both on Al(100) and on pure Al(001) layers present in the Al 9 Ir 2 compound. Finally, the interface between Al 9 Ir 2 precipitates and the Al matrix has been characterized by transmission electron microscopy measurements. The cross-sectional observations are consistent with the formation of Al 9 Ir 2 (001) compounds. These measurements indicate an important Ir diffusion within Al(100) near the surface region. The coherent interface between Al 9 Ir 2 and the Al matrix is sharp.

SSCI-VIDE+ECI2D+LPI; International audience; Replacing noble metal catalysts with inexpensive substitutes is a big challenge for the chemical industry. Several complex Al-based intermetallic compounds have already been identified as promising catalysts for hydrogenation reactions [1,2]. The understanding of theunderlying processes requires a precise determination of the surface structure, as well as (i) the thermodynamic quantities related to the adsorption of molecules involved in the reaction and (ii) the energy barriers of the elemental processes. In this work, a precise surface model for Al5Co2 is deduced from a combination of calculations based on the Density Functional Theory (DFT) and surface sciences techniques [3], including Surface X-Ray Diffraction experiments (Synchrotron SOLEIL). A thermodymamic model is built, powered by theoretical adsorption energies, in order to take into account the reaction conditions (pressure and temperature). The calculated favorablereaction conditions are then compared to the experimental conditions.This work illustrates the complementarity of experimental and theoretical approaches for theunderstanding of the reactivity of complex intermetallic surfaces. It also paves the way to investigations of more complex systems, like the quasicrystalline approximants Al13TM4.[1] M. Armbrüster et al., Nat. Mater., 2012, 11, 690–693.[2] L. Piccolo, Chem. Commun., 2013, 49, 9149[3] M. Meier et al., Phys. Rev. B 93, 075412 (2016)

International audience; We have investigated the structure of the Al13Fe4(010) surface using both experimental and ab initio computational methods. The results indicate that the topmost surface layers correspond to incomplete puckered (P) planes present in the bulk crystal structure. The main building block of the corrugated termination consists of two adjacent pentagons of Al atoms, each centered by a protruding Fe atom. These motifs are interconnected via additional Al atoms referred to as "glue" atoms which partially desorb above 873 K. The surface structure of lower atomic density compared to the bulk P plane is explained by a strong Fe-Al-Fe covalent polar interaction that preserves intact clusters at the surface. The proposed surface model with identified Fe-containing atomic ensembles could explain the Al13Fe4 catalytic properties recently reported in line with the site-isolation concept [M. Armbrüster et al., Nat. Mater. 11, 690 (2012)].

De resultaten van het monitoringprogramma voor prioritaire afvalstoffen zijn weergegeven voor 1994. In het rapport zijn de rapportages van 26 prioritaire afvalstoffen gebundeld. Per afvalstof worden de belangrijkste gegevens betreffende de hoeveelheden (onder meer naar herkomst en verwerkingsmethode) en samenstelling volgens een standaard opzet gepresenteerd en toegelicht. De gegevens zijn vastgesteld op basis van een werkwijze en met behulp van bronnen die beschreven zijn in meetprotocollen. Verder bevat het rapport een overzichtstabel waarin voor de prioritaire afvalstoffen de hoeveelheden per verwerkingsmethode voor 1993 en 1994 zijn weergegeven. Het blijkt dat ten opzichte van 1993 geen grote veranderingen vastgesteld kunnen worden in het aanbod van afval. Wel is sprake van meer hergebruik en minder storten van afval.

International audience; The growth and stability of Bi thin films on the Al13Co4(100) surface has been investigated from the submonolayer to high-coverage regime by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) for temperatures ranging from 57 to 633 K. Initially, Bi adsorption leads to the formation of a pseudomorphic monolayer, followed by the growth of islands of different heights with increasing coverage. The in-plane structure, island height, and island morphology indicate that these islands adopt either a pseudocubic (110) or hexagonal (111) orientation normal to the surface. The (110)-oriented islands correspond to bilayer stacking (either two or four monolayers in height) while the (111)-oriented islands correspond to either three- or four-layer stacking. The in-plane orientation of (110) islands with respect to the substrate is random, while (111) islands adopt one of four possible orientations. In addition, the (111) islands show a moiré structure. The fact that Bi islands grow with either (110) or (111) orientation simultaneously on the same substrate relates to a subtle energy balance between both orientations according to ab initio calculations, allowing both structures to coexist. The island density dependence versus both deposition temperature and flux, their most frequent structure type, reshaping effects, and chemical reactivity of the different allotropes are also discussed in this paper.

Screening for asymptomatic carotid artery stenosis in the general population is discussed in many countries because of the benefits of carotid endarterectomy in the three trials. Many factors influence the cost-effectiveness of screening. These factors are the prevalence of carotid stenosis, the costs of the screening tool, the sensitivity and the specificity of the screening tool and the benefits of the treatments. We found that prevalence-numbers are not easy to extract from literature, and after performing an IPD-meta-analysis, we found that severe asymptomatic carotid artery stenosis is uncommon in the general population. This prevalence ranges from zero percent to 1.7%. Another factor that influences whether screening is worthwhile is the screening tool. Screening performed by DUS in the general population followed by endarterectomy when severe stenosis was found is worthwhile in 65-year old men, when the prevalence is at least 3%. In 75-year-old women screening by Duplex followed by endarterectomy when a severe stenosis was found is was worthwhile when the prevalence of severe asymptomatic carotid artery stenosis was at least 5%. When screening is followed by cardiovascular risk factor management when a moderate stenosis was found and followed by endarterectomy when a severe stenosis was found, screening is worthwhile in men aged 45 when the prevalence of severe asymptomatic carotid artery stenosis is at least 0.01%. In 50-year old women screening followed by cardiovascular risk factor management when moderate stenosis was found was worthwhile, when the prevalence was at least 0.01%. Additionally, we found that endarterectomy decreased the QALY gain and thus increased the incremental cost-effectiveness ratio. Finally we intended to identify individuals for whom one-time screening for ACAS might be cost-effective. We developed a prediction rule for the presence of severe (>70%) stenosis and moderate (>50%) stenosis. We used individual participant data from four population-based studies (MDCS, Tromso, CAPS and CHS). The presence of moderate stenosis was related to age, sex, HDL cholesterol, LDL cholesterol, systolic and diastolic blood pressure, body mass index, waist to hip ratio and smoking. The presence of severe stenosis was related to age, sex, HDL cholesterol, LDL cholesterol, systolic and diastolic blood pressure and smoking. Both models discriminated and calibrated well. We were able to identify subgroups for which screening followed by endarterectomy was worthwhile. Population based screening for asymptomatic carotis stenosis is not cost-effective considering detection of severe stenosis followed by endarterectomy only. We can however identify people at high risk of having severe stenosis for which screening might be cost-effective. In further research our prediction rule should be validated and evaluated in a cost-effectiveness-analysis. When also cardiovascular risk factor management is offered, carotid endarterectomy is no longer appropriate, i.e., carotid endarterectomy made the cost-effectiveness even worse. For now, population based screening for carotid artery stenosis should not be implemented.

International audience; We present a detailed study of the (110) surface of the γ-Al4Cu9 crystal using both experimental methods and first-principles calculations based on density-functional theory. Our experimental approach, using low-energy electron diffraction, scanning tunneling microscopy (STM) images, and x-ray photoelectron spectroscopy highlights the presence of two types of surface terminations. Combining experimental results and simulations provides many arguments to match the two observed surfaces with the two puckered terminations built from bulk truncation: (i) calculations show that these two puckered terminations present lower surface energies compared to another conceivable flat termination obtained also from bulk truncation, (ii) step height measurements are consistent with calculated interlayer spacings and (iii) simulated STM images are in reasonable agreement with the experimental ones and mirror the experimental voltage dependence.