In-situ Raman spectroscopy study of Ru/TiO2 catalyst in the selective methanation of CO

Raman spectroscopic technique has been used to characterize a Ru/TiO2 catalyst and to follow in situ their structural changes during the CO selective methanation reaction (S-MET). For a better comprehension of the catalytic mechanism, the in-situ Raman study of the catalysts activation (reduction) process, the isolated CO and CO2 methanation reactions and the effect of the composition of the reactive stream (H2O and CO2 presence) have been carried out. Raman spectroscopy evidences that the catalyst is composed by islands of TiO2¿RuO2 solid solutions, constituting Ru¿TiO2 interphases in the form of RuxTi1 xO2 rutile type solid solutions. The activation procedure with H2 at 300 °C promotes the reduction of the RuO2¿TiO2 islands generating Ruo ¿Ti3+ centers. The spectroscopic changes are in agreement with the strong increase in chemical reactivity as increasing the carbonaceous intermediates observed. The selective methanation of CO proceeds after their adsorption on these Ruo ¿Ti3+ active centers and subsequent C-O dissociation throughout the formation of CHx/CnHx/CnHxO/CHx-CO species. These intermediates are transformed into CH4 by a combination of hydrogenation reactions. The formation of carbonaceous species during the methanation of CO and CO2 suggests that the CO presence is required to promote the CO2 methanation. Similar carbonaceous species are detected when the selective CO methanation is carried out with water in the stream. However, the activation of the catalysts occurs at much lower temperatures, and the carbon oxidation is favored by the oxidative effect of water.España Mineco ENE2012- 37431-C03-03Unión Europea Junta de Andalucia FEDER TEP-819

Acute Pain and a Motivational Pathway in Adult Rats: Influence of Early Life Pain Experience

The importance of neonatal experience upon behaviour in later life is increasingly recognised. The overlap between pain and reward pathways led us to hypothesise that neonatal pain experience influences reward-related pathways and behaviours in adulthood

Investigating heinrich events : a continuum model of iceberg drift and sedimentation

Records from the North Atlantic reveal high deposition rates of ice-rafted sediments from the Laurentide ice sheet during at least six distinct periods. Known as Heinrich events, these episodes of rapid deposition are attributed to massive iceberg calving promoted by unstable behavior of the ice sheet. The exact mechanisms causing these occurrences of high iceberg flux are not well understood. As a means of elucidating and exploring the freshwater and sediment fluxes associated with Heinrich events, a computer model has been developed which attempts to simulate iceberg drift during these periods of massive calving. This enables reconstruction of the marine sedimentation pattern and provenance-labeled marine core stratigraphy. Using finite-difference methods over a discretized problem domain, the model treats the armada of icebergs as a continuum rather than tracking an ensemble of perhaps thousands of individual trajectories. In this manner the drift of the model icebergs in a multi-layer ocean is governed by advective, diffusive and Coriolis forces as well as being subject to melting. The stochastic nature of iceberg drift is dealt with using a tensorial diffusion coefficient to approximate the effects of heterogeneity, such as different shapes, which strongly influence iceberg drift.Science, Faculty ofEarth, Ocean and Atmospheric Sciences, Department ofGraduat

Will the circle be unbroken?: Aboriginal communities, restorative justice, and the challenges of conflict and change

Embraced with zeal by a wide array of activists and policymakers, the restorative justice movement has made promises to reduce the disproportionate rates of Aboriginal involvement in crime and the criminal justice system and to offer a healing model suitable to Aboriginal communities. Such promises should be the focus of considerable critical analysis and evaluation, yet this kind of scrutiny has largely been absent. 'Will the Circle be Unbroken?' explores and confronts the potential and pitfalls of restorative justice, offering a much-needed critical perspective. Drawing on their shared experiences working with Aboriginal communities, Jane Dickson-Gilmore and Carol LaPrairie examine the outcomes of restorative justice projects, paying special attention to such prominent programs as conferencing, sentencing circles, and healing circles. They also look to Aboriginal justice reforms in other countries, comparing and contrasting Canadian reforms with the restorative efforts in New Zealand, Australia, and the United States. 'Will the Circle be Unbroken?' provides a comprehensive overview of the critical issues in Aboriginal and restorative justice, placing these in the context of community. It examines the essential role of community in furthering both Aboriginal and non-Aboriginal aspirations for restorative justice

Adaptation des végétaux à la sécheresse

Sous l’effet du changement climatique, les épisodes de sécheresse risquent de devenir de plus en plus fréquents dans nos régions. L’adaptation de nos systèmes fourragers à ce type d’évènement nécessite de bien comprendre les différents mécanismes impliqués dans l’utilisation de l’eau par la plante. Cet article passe en revue quelques notions de physiologie afin de mieux comprendre les relations entre l’eau et les espèces prairies

le desherbage des légumineuses

Les stratégies de désherbage actuelles sont largement basées sur le recours aux produits de protection des plantes (PPP) qui permettent le contrôle de nombreuses adventices. Les herbicides sont des molécules, de synthèse ou non, dont l‘activité sur le métabolisme des plantes entraîne leur mort. Ceux-ci peuvent être classés notamment en fonction de leur sélectivité : antidicotylées, antigraminées.

La prairie temporaire améliore la fertilité : introduire une prairie temporaire dans la rotation culturale : quels impacts sur la fertilité du sol ?

L’introduction d’une prairie temporaire durant 3-4 ans dans la rotation présente plusieurs avantages tels que la production d’un fourrage riche en protéine, une conduite culturale aisée et la protection de la ressource en eau. La prairie temporaire présente également l’avantage d’avoir des répercussions positives sur la fertilité du sol se traduisant notamment par un potentiel de minéralisation accru l’année suivant le retournement. La quantité globale d’azote libéré peut ainsi atteindre jusqu’à 400 kg N/ha, ce qui implique toutefois un risque de lessivage non négligeable. Le respect de certaines précautions dans le choix de la rotation permettra néanmoins d’optimiser la valorisation de cet azote