Biochars from various biomass types as anodes for sodium-ion batteries

Until now, the applications targeted for biochars have mostly been focused in the field of energy, as combustion fuel, or of agronomy, as soil amendment. However, high-added value materials in the field of electrochemistry are now more and more mentioned as promising applications to investigate (Deng et al. 2016). At the moment, one major topic in electrochemistry is the development of alternative to lithium-ion battery in order to solve the issue of lithium supply. One of the most mature options is sodium-ion battery (Wang et al. 2016). In such battery, anode is generally made up of hard carbon, that has surface area below 10 m2.g-1 and subnanometric pores. Please click on the file below for full content of the abstract

RETRATO DE MILITARES [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

Electrochemical Method for Direct Deposition of Nanometric Bismuth and Its Electrochemical Properties vs Li

We report that nanometric bismuth can directly be electrodeposited at room temperature without the use of a nanoporous template. The morphology, microstructure, and purity of the as-prepared electrodeposits were characterized by scanning electron microscopy, transmission electron microscopy, and infrared spectroscopy. Typically, well-crystallized nanometer-sized particles of Bi ranging from 10 to 20 nm are obtained. The key to success of such a process lies in the electrochemical coreduction of pyrocatechol violet during the bismuth deposition, which disturbs the electrocrystallization process. As a first possible application, we show that Bi/Cu nanoarchitectured electrodes exhibit interesting rate capabilities when used as electrode material vs Li

Description et modélisation des chaînes de référence. Le projet ANR Democrat (2016-2020) et ses avancées à mi-parcours

International audienceLe projet ANR Democrat vise à développer les recherches sur la langue et la structuration textuelle du français via l’analyse détaillée et contrastive des chaînes de références (instanciations successives d’une même entité) dans un corpus diachronique de textes écrits entre le 9ème et le 21ème siècle, avec des genres textuels variés. Il réunit des chercheurs issus des laboratoires Lattice, LiLPa, ICAR et IHRIM. Il a été lancé en mars 2016 et l’essentiel des efforts porte actuellement sur l’annotation (manuelle) d’un corpus. Plusieurs expérimentations d’annotation ont eu lieu, de manière à tester différentes procédures. La procédure retenue alterne des phases manuelles et des phases automatiques pour compléter les annotations, via le lancement de scripts

Argumentation et narration

À travers des contributions de diverses disciplines, cette enquête montre très concrètement que la puissance heuristique de la narration est un levier indispensable à toute pratique de l’argumentation. Elle montre aussi que si les deux registres concourent ensemble à une rationalité pleinement incarnée, ils ne se confondent jamais totalement

Selective top-down control of epiphytic biomass by amphipods from Posidonia oceanica meadows: implications for ecosystem functioning

Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipod crustaceans that graze on epiphytes. However, their actual significance for ecosystem functional processes is hard to estimate, due to the lack of adequate data. Here, a field microcosm-based inclusion experiment was used to test if three of the dominant taxa of the amphipod community (Apherusa chiereghinii, Dexamine spiniventris and Gammarus spp.) could exert top-down control on seagrass leaf epiphytes. Influence of amphipod activity on nutrient availability for the host species was also investigated. All grazer taxa significantly reduced biomasses of erect macroalgae and erect sessile animals present on leaves. None of them consumed encrusting epiflora or epifauna. This selective top-down control could have important implications for the structure of the epiphytic community of P. oceanica leaves, which is one of the most diverse and abundant of all seagrass species. Grazing activity of all taxa caused higher N content of seagrass leaves, likely through amphipod excretion and/or sloppy feeding. Since P. oceanica meadows often grow in oligotrophic zones where plant growth can be nutrient-limited, this N enrichment could enhance seagrass production. Overall, the ecological interaction between P. oceanica and amphipods could be seen as a facultative mutualistic relationship. Our results suggest that amphipod mesograzers are key-elements in some of the functional processes regulating these complex and yet endangered ecosystems, which are essential components of Mediterranean coastal zones

3D printing of solid polymer electrolytes by Fused Filament Fabrication: challenges towards in-space manufacturing

Abstract A new chapter of space exploration is opening with future long-duration space missions toward the Moon and Mars. In this context, the European Space Agency (ESA) is developing out-of-the-earth manufacturing abilities, to overcome the absence of regular supplies for astronauts’ vital needs (food, health, housing, energy). Additive manufacturing is at the heart of this evolution because it allows the fabrication of tailorable and complex shapes, with a considerable ease of process. Fused Filament Fabrication (FFF), the most generalized 3D printing technique, has been integrated into the International Space Station (ISS) to produce polymer parts in microgravity. Filament deposition printing has also a key role to play in Li-ion battery (LIB) manufacturing. Indeed, it could reduce manufacturing cost & time, through one-shot printing of LIB, and improve battery performances with suitable 3D architectures. Thus, additive manufacturing via FFF of LIB in microgravity would open the way to In-Space Manufacturing (ISM) of energy storage devices. However, as liquid and volatile species are not compatible with a space station-confined environment, solvent-free 3D printing of polymer electrolytes is a necessary step to make battery printing in microgravity feasible. This is a challenging stage because of a strong opposition between the mechanical requirements of the feeding filament and electrochemical properties. Nowadays, polymer electrolyte manufacturing remains a hot topic and lots of strategies are currently being studied to overcome their poor ionic conductivity at room temperature. This work firstly gives a state of the art on the 3D printing of Li-ion batteries by FFF. Then, a summary of ionic conduction mechanisms in polymer electrolytes permits to understand the several strategies studied to enhance polymer electrolytes performances. Thanks to the confrontation with the specifications of FFF printing and the microgravity environment, polymer blends and composite electrolytes turn out to be the most suitable strategies to 3D print a lithium-ion polymer battery in microgravity

Contrôle de la structure en domaines dans des super-réseaux ferroélectriques bicolores et tricolores

L objectif de ce travail a été d étudier la structure en domaines dans des super-réseaux bicolores et tricolores, composés des matériaux PbTiO3, PbZr1-xTixO3 (PbZr0,2Ti0,8O3 ou PbZr0,1Ti0,9O3) et SrTiO3. Cette étude a consisté à élaborer ces super-réseaux par ablation laser puis à étudier leur structure en domaines ferroélectriques par diffraction de rayons X, microscopie électronique en transmission et microscopie à force atomique en mode piézoréponse. Pour chaque famille de super-réseaux, les paramètres ont été ajustés pour modifier les contraintes mécaniques et en déterminer les effets sur la structure en domaines. Dans les super-réseaux bicolores PbTiO3/PbZr0,2Ti0,8O3, les tensions mécaniques sont relaxées en une structure en domaines à 90. Nous avons mis en évidence que cette relaxation peut être supprimée si la période du super-réseau et l épaisseur du film restent en deçà de valeurs critiques que nous avons déterminées. Par ailleurs nous montrons que la stabilisation d une structure monodomaine est plus favorable lorsque le désaccord de paramètre de maille entre PbTiO3 et PbZr1-xTixO3 diminue, ainsi que nous l avons observé dans les super-réseaux PbTiO3/PbZr0,1Ti0,9O3. Dans les super-réseaux tricolores PbTiO3/SrTiO3/ PbZr1-xTixO3, une couche ultrafine du matériau paraélectrique SrTiO3 a été insérée à chaque interface entre les couches ferroélectriques. Nous avons démontré l existence d un effet de champ dépolarisant qui est induit dans les couches ferroélectriques par SrTiO3. Dans les super-réseaux PbTiO3/ SrTiO3/PbZr0,2Ti0,8O3, cet effet de champ dépolarisant inhibe la relaxation en domaines à 90 et provoque la formation d une structure en domaines à 180.The aim of this work has been to study the domain structure in bicolour and tricolour superlattices based on PbTiO3, PbZr1-xTixO3 PZT: PbZr0,2Ti0,8O3 and PbZr0,1Ti0,9O3) and SrTiO3. The samples were grown by pulsed laser deposition and the ferroelectric domain structure was studied by X-ray diffraction, transmission electron microscopy, and atomic force microscopy in the piezoresponse mode. For each family of superlattices, the superlattice parameters were adjusted to modify the mechanical strains and to determine their effects on the domain structure. In the bicolour superlattices PbTiO3/ PbZr0,2Ti0,8O3, mechanical strain is relaxed by 90 domain formation. We have demonstrated that this relaxation can be suppressed if the superlattice period and the sample thickness are below certain critical values. In addition we show that the stabilization of the monodomain structure is more favourable when the mismatch between PbTiO3 and PbZr1-xTixO3 diminishes as demonstrated by our results on PbTiO3/ PbZr0,1Ti0,9O3 superlattices. In the tricolour superlattices PbTiO3/SrTiO3/PbZr1-xTixO3, we have shown that a depolarization field exists in the ferroelectric materials induced by the 1 nm in thickness SrTiO3 layers. In the PbTiO3/PbZr0,2Ti0,8O3 superlattices, we have demonstrated that this depolarization field suppress the 90 domain structure and induces the formation of a 180 domain structure.AMIENS-BU Sciences (800212103) / SudocSudocFranceF

Impact of grazing by amphipods on the epiphytic cover of the Posidonia oceanica leaves: an in situ experiment.

It is now established that several species of amphipods associated to Mediterranean Posidonia oceanica meadows consume the macro-epiphytes present on the leaves of the seagrass. Moreover, under controlled in vitro conditions, three amphipod taxa (Apherusa chiereghinii,Dexamine spiniventris and Gammarus spp.) are able to drastically deplete the biomass of erected algae, thus influencing the epiphytic cover in both a quantitative and a qualitative way. Here, we tried to assess whether this strong and complex trophic interaction was realized in the field. We designed an in situ experiment that used microcosms placed directly in the meadow, at a depth of 10m, to estimate the impact of grazing by the aforementioned amphipod taxa on the dynamics of the epiphytic cover. Both Gammarus spp. and Dexamine spiniventris caused a significant decrease of the biomass of erected algae and erected animals (bryozoans and hydrozoans). Impact of grazing by Apherusa chiereghinii on these two epiphytic groups was less important, although strong but marginally non-significant (0,1>p>0,05) trends to lower biomasses were present. None of the considered taxa seemed to consume encrusting macro-epiphytes. In addition, assimilation of epiphyte-derived carbon and nitrogen by grazers was monitored using stable isotopes (13C and 15N), and epiphyte elemental content (C & N) was measured. Our results shed light on trophic interactions between the amphipods from Posidonia oceanica meadows and the seagrass epiphytic cover, and thus enhance our understanding of the role of these grazers in the functioning of the meadow as an ecosystem