Chemical Vapor Deposition of Al13 Fe4 Highly Selective Catalytic Films for the Semi-Hydrogenation of Acetylene

Catalytic properties of coatings containing the Al13Fe4 intermetallic phase are tested in the reaction of semi-hydrogenation of acetylene. The selectivity to ethylene is found as high as 74% close to the reported values for pure,unsupported Al13Fe4. The initial conversion of acetylene to ethylene is 84% and rapidly drops due to the catalytic formation of carbon-based by-products on secondary Al-Fe phases. Coatings are processed through sequential chemical vapor deposition (CVD) of aluminum (5 Torr, 180 °C) and iron(40 Torr, 140 °C) layers, followed by in situ annealing for 60 min at 575 °C.Deposition proceeds at high growth rate, resulting in 15 μm thick films. After annealing, coatings are composed of the Al13Fe4 phase, co-existing with minor secondary Al-Fe intermetallic phases. Overall, it is shown that films containing complex Al-Fe intermetallic phases can be processed by CVD, opening new routes to the engineering of pure, supported Al13Fe4 catalysts on 3D or porous supports

Solvent contribution to the stability of a physical gel characterized by quasi-elastic neutron scattering

The dynamics of a physical gel, namely the Low Molecular Mass Organic Gelator {\textit Methyl-4,6-O-benzylidene-$\alpha$ -D-mannopyranoside ($\alpha$-manno)} in water and toluene are probed by neutron scattering. Using high gelator concentrations, we were able to determine, on a timescale from a few ps to 1 ns, the number of solvent molecules that are immobilised by the rigid network formed by the gelators. We found that only few toluene molecules per gelator participate to the network which is formed by hydrogen bonding between the gelators' sugar moieties. In water, however, the interactions leading to the gel formations are weaker, involving dipolar, hydrophobic or $\pi-\pi$ interactions and hydrogen bonds are formed between the gelators and the surrounding water. Therefore, around 10 to 14 water molecules per gelator are immobilised by the presence of the network. This study shows that neutron scattering can give valuable information about the behaviour of solvent confined in a molecular gel.Comment: Langmuir (2015

Clinical standards for the diagnosis and management of asthma in low- and middle-income countries

BACKGROUND: The aim of these clinical standards is to aid the diagnosis and management of asthma in low-resource settings in low- and middle-income countries (LMICs). METHODS: A panel of 52 experts in the field of asthma in LMICs participated in a two-stage Delphi process to establish and reach a consensus on the clinical standards. RESULTS: Eighteen clinical standards were defined: Standard 1, Every individual with symptoms and signs compatible with asthma should undergo a clinical assessment; Standard 2, In individuals (>6 years) with a clinical assessment supportive of a diagnosis of asthma, a hand-held spirometry measurement should be used to confirm variable expiratory airflow limitation by demonstrating an acute response to a bronchodilator; Standard 3, Pre- and post-bronchodilator spirometry should be performed in individuals (>6 years) to support diagnosis before treatment is commenced if there is diagnostic uncertainty; Standard 4, Individuals with an acute exacerbation of asthma and clinical signs of hypoxaemia or increased work of breathing should be given supplementary oxygen to maintain saturation at 94–98%; Standard 5, Inhaled short-acting beta-2 agonists (SABAs) should be used as an emergency reliever in individuals with asthma via an appropriate spacer device for metered-dose inhalers; Standard 6, Short-course oral corticosteroids should be administered in appropriate doses to individuals having moderate to severe acute asthma exacerbations (minimum 3–5 days); Standard 7, Individuals having a severe asthma exacerbation should receive emergency care, including oxygen therapy, systemic corticosteroids, inhaled bronchodilators (e.g., salbutamol with or without ipratropium bromide) and a single dose of intravenous magnesium sulphate should be considered; Standard 8, All individuals with asthma should receive education about asthma and a personalised action plan; Standard 9, Inhaled medications (excluding dry-powder devices) should be administered via an appropriate spacer device in both adults and children. Children aged 0–3 years will require the spacer to be coupled to a face mask; Standard 10, Children aged <5 years with asthma should receive a SABA as-needed at step 1 and an inhaled corticosteroid (ICS) to cover periods of wheezing due to respiratory viral infections, and SABA as-needed and daily ICS from step 2 upwards; Standard 11, Children aged 6–11 years with asthma should receive an ICS taken whenever an inhaled SABA is used; Standard 12, All adolescents aged 12–18 years and adults with asthma should receive a combination inhaler (ICS and rapid onset of action long-acting beta-agonist [LABA] such as budesonide-formoterol), where available, to be used either as-needed (for mild asthma) or as both maintenance and reliever therapy, for moderate to severe asthma; Standard 13, Inhaled SABA alone for the management of patients aged >12 years is not recommended as it is associated with increased risk of morbidity and mortality. It should only be used where there is no access to ICS. The following standards (14–18) are for settings where there is no access to inhaled medicines. Standard 14, Patients without access to corticosteroids should be provided with a single short course of emergency oral prednisolone; Standard 15, Oral SABA for symptomatic relief should be used only if no inhaled SABA is available. Adjust to the individual’s lowest beneficial dose to minimise adverse effects; Standard 16, Oral leukotriene receptor antagonists (LTRA) can be used as a preventive medication and is preferable to the use of long-term oral systemic corticosteroids; Standard 17, In exceptional circumstances, when there is a high risk of mortality from exacerbations, low-dose oral prednisolone daily or on alternate days may be considered on a case-by-case basis; Standard 18. Oral theophylline should be restricted for use in situations where it is the only bronchodilator treatment option available. CONCLUSION: These first consensus-based clinical standards for asthma management in LMICs are intended to help clinicians provide the most effective care for people in resource-limited settings

Spatio-temporal dynamics of demersal exploited species in the Gulf of Lions : potential usefulness of Marine Protected Areas

Les espèces démersales représentent 50% des captures des pêcheries françaises du golfe du Lion, dont la plupart sont pleinement exploitées, voir surexploitées depuis plusieurs décennies. Cette thèse évalue la pertinence d'aires marines protégées (AMPs) comme outil de gestion et de conservation de ces populations. Jusqu'à présent de telles zones ont été uniquement mises en place le long des côtes pour protéger des espèces très peu mobiles. Le problème est plus complexe pour les espèces vivant en haute mer car leur habitat est plus large et plus diffus. Pour ce faire, la distribution spatiale de 12 espèces démersales exploitées clés ont été étudiées de 1994 à 2010, à l'aide d'observations scientifiques et d'outils statistiques ad hoc. Une approche géostatistique a permis de détecter des structures d'auto-corrélation spatiale pour l'ensemble des espèces, et de produire des cartes de distributions annuelles de chaque espèce. Ces distributions sont apparues très stables sur les dix-sept années, mis à part un phénomène d'expansion/ rétraction avec le niveau d'abondance totale sur la région. Par ailleurs une approche par modèle linéaire généralisé a révélé des associations importantes de ces espèces à un habitat stable dans le temps. Ces résultats sont en accord avec la théorie du bassin de MacCall selon laquelle l'association d'une espèce à un habitat est densité-dépendant, et l'augmentation de la densité d'individus dans une zone serait à l'origine de la colonisation d'habitats sub-optimaux. Protéger l'habitat optimal d'une espèce permettrait alors de constituer un habitat «source», si la zone est judicieusement choisie ; en effet le report de l'effort de pêche à l'extérieur de l'AMP peut au contraire rendre cette mesure inefficace voir délétère. Par ailleurs les populations adultes occupaient généralement des zones plus concentrées et incluses dans l'aire de répartition des juvéniles. Ces zones communes d'habitats essentiels (reproduction et nourriceries) peuvent être potentiellement intéressantes à protéger dans un cadre monospécifique. L'hétérogénéité observée des répartitions d'une espèce à l'autre implique l'instauration de zones très clairsemées, et rend la gestion difficile dans une cadre pluri-spécifique. Une zone de taille raisonnable a tout de même été identifiée, représentant 20% de la population de chaque espèce et représentative de la diversité des habitats de cette région.Demersal species represent 50% of French fisheries catches in theGulf of Lions, most of which are fully exploited, or overfished for decades. This thesis evaluates the relevance of marine protected areas (MPAs) as a tool for conservation and management of these populations. So far these areas have been implemented only along the coast to protect the very few mobile species. The problem is more complex for deep sea species because their habitat is broader and more diffuse. To do this, the spatial distribution of 12 key demersal species exploited were studied from 1994 to 2010, with scientific observations and ad hoc statistical tools. A geostatistical approach allowed to detect spatial autocorrelation structures for all species, and produce maps of annual distributions of each species. These distributions appeared very stable over 17 years, apart from a phenomenon of expansion/ contraction with the level of total abundance in the region. In addition, a generalized linear model approach revealed significant associations of these species to a temporally stable habitat. These results are consistent with MacCall basin theory, according which habitat suitability is a density-dependent thus the increase of individuals in an area make them colonize sub-optimal habitats. An optimal habitat under protection could thus be "source" habitat, if the area is carefully chosen. Indeed reporting the fishing effort outside the MPA can instead make this measure ineffective or deleterious. The adult population were generally in more concentrated areas and included in the spatial range of juveniles. These common areas of essential habitat (breeding and nursery) may be potentially interesting to protect a single species . However, the heterogeneity of distributions of a species to another involves the introduction of very sparse areas, making the management difficult. However an area of ​​reasonable size has been identified, covering 20% ​​of the population of each species and representative of the diversity of bottom habitats in the region

Modèle hiérarchique bayésien pour analyser les contenus stomacaux de prédateurs marins : application aux thons tropicaux

International audienceNous présentons une méthode pour modéliser le comportement d'un prédateur marin chassant sur bancs de proies, à partir de l'observation de son contenu stomacal. Le prédateur marin choisi pour l'étude est le thon tropical. Notre observation, le nombre de proies contenues dans un estomac de thon, est le résultat de deux phénomènes inobservables et aléatoires: la rencontre du prédateur avec un agrégat de proies, et le nombre de proies ingérées sur cet agrégat. Ces données stomacales comportant une forte proportion de zéros (données " zero-inflated "), nous avons utilisé un modèle de Poisson Composé comme modèle initial. Ce modèle a ensuite été amélioré par l'introduction de différents facteurs explicatifs tels que la taille et l'espèce du thon, ainsi que la structuration en bancs des thons. Pour estimer les paramètres de ce modèle hiérarchique, une inférence bayésienne et des algorithmes de simulations MCMC (" Metropolis Within Gibbs ") ont été mis en place. Des applications sur données simulées ont permis de vérifier la fiabilité des algorithmes ainsi que l'importance de la prise en compte de la structuration en bancs des prédateurs dans la précision des distributions a posteriori. Enfin des applications sur des données réelles illustrent les différentes possibilités d'utilisations de ce modèle, et ont permis de mieux comprendre le comportement alimentaire du thon tropical

Infection à chikungunya (synthèse des connaissances et perspectives après l'épidémie réunionnaise)

LYON1-BU Santé (693882101) / SudocSudocFranceF