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Doped ceria is known for its high ionic conductivity which is limited by the creation of defect clusters. We investigate using Molecular Dynamics the evolution of the structure and oxygen diffusivity of the Ce 0.9 M 0.1 O 1.95 (M = Gd, Sm) doped and co-doped CeO 2 systems. Two configurations concerning the introduction of the doping ions and oxygen vacancies inside the structure are generated and compared, the random one (R) and the neighbor one (N). The pair potential parameter set is chosen among three sets by comparison with experimental data. The pair correlation function first peak is fitted by a lognormal function to take into account the asymmetry. The evolution of the coefficient of thermal expansion, the coordination number and the bond lengths of the different ion pairs with the temperature, is presented. The influence of the local C-type sesquioxide M 2 O 3 structure on those parameters is discussed. No significant positive co-doping effect on the oxygen diffusion process is revealed. The random configuration of the defects leads to the highest oxygen diffusivity and to the lower activation energy whatever the doping ion (Gd, Sm or Gd/Sm). [ABSTRACT FROM AUTHOR]

In Chad, hard-rock aquifers are the main source of drinking water for the population located on basement areas. In these basement aquifers, and in particular those of the Guéra region, water drilling failure rates remain high despite research on one- and two-dimensional electrical resistivity techniques and lineaments as a means to improve access to the resource, mainly because these techniques are only used on an observational and structural basis to locate fractures. This study combines electrical resistivity tomography (ERT) with geology, hydrogeology and geomorphology, in order to characterise the structure and geometry of the aquifer system, assess borehole productivity and determine the factors controlling it. After validating the large dataset and its representativeness, 315 high- and low-yield wells, of which 41 have complete geophysical datasets, were selected. This large dataset allows a multi-parameter approach to (1) better characterise each facies according to its electrical resistivity and (2) clearly identify the main formations constituting the local conceptual hydrogeological model. The most suitable areas for productive boreholes are characterised by the presence of an overburden of <20 m depth, well-developed weathered and fractured horizons of granites and biotite granites (preferably) containing little or no clay, and a nearby drainage network. The most substantial flow rates are found in the first 30 m of the fissured horizon, below the base of the alterites. The experience gained from the present study will guide future analysis of ERT sections in order to reduce the probability of drilling dry wells. [ABSTRACT FROM AUTHOR]

Abstract: Phosphatidylinositol 5-monophosphate (PtdIns5P), one of the latest phosphoinositides discovered, has been suggested to play important cellular functions. Here, we report the presence of higher levels of this lipid in cells expressing the oncogenic tyrosine kinase nucleophosmin anaplastic lymphoma kinase (NPM-ALK), a chimeric protein found in the large majority of anaplastic large cell lymphomas (ALCLs). In addition, we describe that a pool of PtdIns5P is located in the membrane extensions characteristic of NPM-ALK-transformed cells. Finally, we show that the increase of PtdIns5P is controlled by the kinase PIKfyve, which is known for its role in vesicular trafficking. These data suggest for the first time a role of PtdIns5P and PIKfyve in oncogenesis, potentially linking intracellular trafficking to cancer. [Copyright &y& Elsevier]

The majority of anaplastic large cell lymphomas (ALCLs) express the nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) fusion protein, which is oncogenic due to its constitutive tyrosine kinase activity. Transformation by NPM-ALK not only increases proliferation, but also modifies cell shape and motility in both lymphoid and fibroblastic cells. We report that the Rac1 GTPase, a known cytoskeletal regulator, is activated by NPM-ALK in ALCL cell lines (Karpas 299 and Cost) and transfected cells (lymphoid Ba/F3 cells, NIH-3T3 fibroblasts). We have identified Vav3 as one of the exchange factors involved in Rac1 activation. Stimulation of Vav3 and Rac1 by NPM-ALK is under the control of Src kinases. It involves formation of a signaling complex between NPM-ALK, pp60c-src, Lyn and Vav3, in which Vav3 associates with tyrosine 343 of NPM-ALK via its SH2 domain. Moreover, Vav3 is phosphorylated in NPM-ALK positive biopsies from patients suffering from ALCL, demonstrating the pathological relevance of this observation. The use of Vav3-specific shRNA and a dominant negative Rac1 mutant demonstrates the central role of GTPases in NPM-ALK elicited motility and invasion.Oncogene (2008) 27, 2728–2736; doi:10.1038/sj.onc.1210921; published online 12 November 2007 [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a direct measurement method for optical properties of different materials at cryogenic temperatures from 20K to 200K. It has been developed within the framework of the design of Planck program. Planck is a satellite of the European Space Agency (ESA) that will be launched in 2008. The scientific goal of the Planck mission is to make observations of the temperature anisotropy and polarisation of the Cosmic Microwave Background. The equivalent temperature of the observed radiation is about 3K and the telescope baffle temperature should not exceed 60K in order to work properly. The large Planck telescope is passively cooled by radiating to the Deep Space, so that a good knowledge of the thermo-optical properties of its coating is of utmost importance for thermal modelling. However, up to now, few measurements have been done at such low temperatures. We derived a direct measurement method for the total directional emissivity of various coatings of interest for satellites applications. The effective spectral range chosen the measurements covers 6–800μm. We will describe the design of the measurement apparatus and present results for several coatings. [Copyright &y& Elsevier]