Electrochemical strain microscopy time spectroscopy: Model and experiment on LiMn2O4

Electrochemical Strain Microscopy (ESM) can provide useful information on ionic diffusion in solids at the local scale. In this work, a finite element model of ESM measurements was developed and applied to commercial lithium manganese (III,IV) oxide (LiMn2O4) particles. ESM time spectroscopy was used, where a direct current (DC) voltage pulse locally disturbs the spatial distribution of mobile ions. After the pulse is off, the ions return to equilibrium at a rate which depends on the Li diffusivity in the material. At each stage, Li diffusivity is monitored by measuring the ESM response to a small alternative current (AC) voltage simultaneously applied to the tip. The model separates two different mechanisms, one linked to the response to DC bias and another one related to the AC excitation. It is argued that the second one is not diffusion-driven hut is rather a contribution of the sum of several mechanisms with at least one depending on the lithium ion concentration explaining the relaxation process. With proper fitting of this decay, diffusion coefficients of lithium hosts could be extracted. Additionally, the effect of phase transition in LiMn2O4 is taken into account, explaining some experimental observations. (C) 2015 AIP Publishing LLC

Temporary use of a coastal ecosystem by the fish, Pomadasys corvinaeformis (Perciformes: Haemulidae), at Guaratuba Bay, Brazil

Pomadasys corvinaeformis is Qne ofthe most abundant species found in Guaratuba Bay, an Atlantic coastal, estuarine ecosystem in Paraná, Brazil. We tested whether this species comprises a resident or migratorial population. Abundance, size distribution, and gonad development of individuaIs captured during the year show that pre-adults enter the system when salinities are greater (autumn and early winter). During this time, they are mostly associated with mangroves and adjacent areas. When salinities begin to fall (late spring and summer) these now maturing individuaIs return to the sea where they spawn. Thus, P. corvinaeformis is migratorial and estuarine-dependent and uses this area prior to sexual maturity. During the period in this bay, P. corvinaeformis presents a great plasticity of feeding habits, that include inainly Crustacea, MoIlusca and Thaliacea.Pomadasys corvinaeformis é uma das espécies de maior representatividade na ictiofauna da Baía de Guaratuba, litoral do Estado do Paraná. Este trabalho investigou se a espécie compõe ali uma população permanente, residente no sistema, ou se é migratória, fteqüentando-o apenas em épocas determinadas. Resultados de 12 meses sobre variações de abundância, distribuição de tamanho e aspectos reprodutivos indicam que indivíduos subadultos ingressam no sistema quando a salinidade é maior (outono, começo de inverno). Nesta época, os indivíduos utilizam a área de manguezal e suas adjacências. Quanto a salinidade começa a cair (final de primavera, verão), estes indivíduos agora em maturação gonadal retomam para o mar, onde desovam. P. corvinaeformis é, portanto, uma espécie migratória e estuarino-dependente que utiliza a Baía em período anterior ao de maturidade gonadal. Ali, apresenta uma dieta muito variada, constituída basicamente de Crustacea, MoIlusca e Thaliacea

Jefferies, R.L. & Davy, A. J. (Editors). — Ecological Processes in Coastal Environments. The First European Ecological Symposium and the 19th Symposium of the British Ecological Society, Norwich, 12-16 September 1977

Amanieu M. Jefferies, R.L. & Davy, A. J. (Editors). — Ecological Processes in Coastal Environments. The First European Ecological Symposium and the 19th Symposium of the British Ecological Society, Norwich, 12-16 September 1977. In: Revue d'Écologie (La Terre et La Vie), tome 34, n°3, 1980. pp. 475-476

Propriétés chitinolytiques du liquide exuvial du ver à soie (Bombyx mori L.)

The authors add further confirmation to the hypothesis of the role played by a chitinase during the process of moulting. By ligaturing Bomy x mori-larvae between head and thorax, accumulation of moulting fluid takes place between head and thorax, accumulation of moulting fluid takes place between the larval and nymphal cuticles, swallowing of this fluid being prevented. The chitinolytic properties of this moulting fluid are demonstrated in vitro. The activity of chitinase at different pH is investigated : the optimum pH lying at about n5-4

Mise en évidence d'une chitinase dans le liquide exuvial de Bombyx Mori L;

Des chenilles de Bombyx mori L. sont ligaturées 48 heures avant la mue nymphale, entre la tête et le thorax, pour permettre l'accumulation de liquide exuvial entre la vieille cuticule et le tégument nymphal. Ce liquide exuvial renferme une chitinase très active dont le pH optimum est situé aux environs du pH 5.4. La courbe d'activité en fonction du pH est fort semblable à celle des chitinases de Helix pomatia et aspersa, et à celle de l'exochitinase du filtrat de culture d'un Actinomycète chitinolytique isolé du sol ; elle diffère nettement de c elle figurée par Hamamura et al. (1940, 1954) pour la chitinase d'un extrait aqueux d'exuvies larvaires de B. mori L

Organisation et evolution des peuplements lagunaires

The analysis of the community structures of a Danish fjord macrofauna and of various Mediterranean lagoons results in the same interpretation of the organization of communities which start from meroplankton, leading to the formation of disorganized communities. The biotic and abiotic lagoon environment puts these populations under stress, causing gradual organization into structured one-species communities. Such an interpretation suggests that the degree of organization is measured by the species diversity or more precisely by one species alone. Each population has to develop and adapt strategy which favors migratory behavior. When this is not possible, a waste economy develops where the speed of the generation cycles corrects the catastrophic losses resulting from climatic stress. The arguments are reasonably convincing when only the eco-ethologic behavior of the monospecific populations are studied. It is more difficult to accept them when we try to apply the same reasoning to pluri-specific communities

RICHESSE ET DIVERSITÉDE LA MACROFAUNE BENTHIQUED'UNE LAGUNE LITTORALE MÉDITERRANÉENNE

International audienc

ÉVOLUTION STRUCTURALE DES PEUPLEMENTS DE LA MACROFAUNE BENTHIQUE DES ÉTANGS PALAVASIENS

International audienc

RICHESSE ET DIVERSITÉDE LA MACROFAUNE BENTHIQUED'UNE LAGUNE LITTORALE MÉDITERRANÉENNE

International audienc

ÉVOLUTION STRUCTURALE DES PEUPLEMENTS DE LA MACROFAUNE BENTHIQUE DES ÉTANGS PALAVASIENS

International audienc