1,055 research outputs found
Nano-building block based-hybrid organicâinorganic copolymers with self-healing properties
New dynamic materials, that can repair themselves after strong damage, have been designed by hybridization of polymers with structurally well-defined nanobuilding units. The controlled design of cross-linked poly(n-butyl acrylate) (pBuA) has been performed by introducing a very low amount of a specific tin oxo-cluster. Sacrificial domains with non-covalent interactions (i.e. ionic bonds) developed at the hybrid interface play a double role. Such interactions are strong enough to cross-link the polymer, which consequently exhibits rubber-like elasticity behavior and labile enough to enable, after severe mechanical damage, dynamic bond recombination leading to an efficient healing process at room temperature. In agreement with the nature of the reversible links at the hybrid interface, the healing process can speed up considerably with temperature. 1H and 119Sn PFG NMR has been used to evidence the dynamic nature of these peculiar cross-linking nodes
Study on the big purse seiners fishery in the Java Sea : 3 : the fishing method
Apparue dans les annĂ©es 1970 en mer de Java, la senne tournante et coulissante est l'un des principaux engins pour la pĂȘche des petits poissons pĂ©lagiques de cette mer. Elle Ă©quipe les grands senneurs de la cĂŽte nord de l'Ăźle de Java, objets de cette Ă©tude. La pĂȘche est rĂ©alisĂ©e essentiellement autour de radeaux ancrĂ©s, de nuit et sur des aggrĂ©gations de poissons concentrĂ©es Ă la lumiĂšre. La mĂ©thode employĂ©e reste trĂšs archaĂŻque et ne semble pas Ă©voluer malgrĂ© les changements observĂ©s dans la pĂȘcherie. L'engin de pĂȘche prĂ©sente un plan standard mĂȘme si le montage et l'assemblage sont rĂ©alisĂ©s par les patrons eux-mĂȘmes. Le nombre de radeaux et de calĂ©es varient avec synchronisme suivant les saisons. Les maxima sont observĂ©s en mars-avril et les minima en octobre-novembre. Ces premiers rĂ©sultats doivent ĂȘtre confirmĂ©s par une extension des enquĂȘtes et la dĂ©livrance de journaux de bord auprĂšs des patrons pĂȘcheurs. (RĂ©sumĂ© d'auteur
Study on the big purse seiners fishery in the Java Sea : 7 : environment of the Java Sea
Les phénomÚnes hydroliques (sic) sont essentiels dans la répartition des espÚces pélagiques et leur abondance en certains secteurs. L'hydrologie de la mer de Java est mal connue, car nous ne possédons pas de données recouvrant plusieurs cycles annuels. La synthÚse des travaux réalisés depuis 1910 nous permet d'affirmer que malgré son caractÚre relativement fermé la mer de Java est le siÚge d'importants mouvements d'eaux, dépendant du régime des moussons, qui modifient profondément son hydrologie. Les fluctuations de salinité sont élevées alors que celles de la température sont faibles. La richesse en sels nutritifs y semble moyenne. (Résumé d'auteur
Study on the big purse seiners fishery in the Java sea : 1 : the main pelagic species caught
Les grands senneurs qui exploitent la mer de Java dĂ©barquent dans six ports de la cote nord de l'ile de Java d'importantes quantitĂ©s de poissons pĂ©lagiques. Onze espĂšces reprĂ©sentent 90% des apports, soit environ 100 000 tonnes en 1985. Mais le systĂšme de collecte de donnĂ©es statistiques varie selon les ports ou les rĂ©gions. La mĂȘme espĂšce peut ĂȘtre identifiĂ©e sous plusieurs noms communs ou bien ĂȘtre confondue avec une autre. Des critĂšres visuels de reconnaissance sont donnĂ©s et des solutions sont proposĂ©es pour une meilleure collecte et une meilleure utilisation des donnĂ©es statistiques. (RĂ©sumĂ© d'auteur
Hodge polynomials of some moduli spaces of Coherent Systems
When , we study the coherent systems that come from a BGN extension in
which the quotient bundle is strictly semistable. In this case we describe a
stratification of the moduli space of coherent systems. We also describe the
strata as complements of determinantal varieties and we prove that these are
irreducible and smooth. These descriptions allow us to compute the Hodge
polynomials of this moduli space in some cases. In particular, we give explicit
computations for the cases in which and is even,
obtaining from them the usual Poincar\'e polynomials.Comment: Formerly entitled: "A stratification of some moduli spaces of
coherent systems on algebraic curves and their Hodge--Poincar\'e
polynomials". The paper has been substantially shorten. Theorem 8.20 has been
revised and corrected. Final version accepted for publication in
International Journal of Mathematics. arXiv admin note: text overlap with
arXiv:math/0407523 by other author
Seasonal and interannual variations of the sea surface temperatures (SST) in the Banda and Arafura sea area
Identification of the major tRNAPhe binding domain in the tetrameric structure of cytoplasmic phenylalanyl-tRNA synthetase from baker's yeast
AbstractNative cytoplasmic phenylalanyl-tRNA synthetase from baker's yeast is a tetramer of the α2ÎČ2 type. On mild tryptic cleavage it gives rise to a modified âĄ2ÎČâČ2 form that has lost the tRNAPhe binding capacity but is still able to activate phenylalanine. In this paper are presented data concerning peptides released by this limited proteolytic conversion as well as those arising from exhaustive tryptic digestion of the truncated ÎČâČ subunit. Each purified peptide was unambiguously assigned to a unique stretch of the ÎČ subunit amino acid sequence that was recently determined via gene cloning and DNA sequencing. Together with earlier results from affinity labelling studies the present data show that the Lys 172âIle 173 bond is the unique target of trypsin under mild conditions and that the N-terminal domain of each ÎČ subunit (residues 1â172) contains the major tRNAPhe binding sites
Unit-cell for dual-circular polarisation reflectarrays
International audienceâA new unit-cell composed of two layers for dual-CP reflectarrays is proposed for the first time with the unique capability to reflect independently and simultaneously the two incident circular polarisations at the same frequency. The experimental results demonstrate that this unit-cell exhibits a 3.8% bandwidth around 8.4 GHz for a phase resolution better than 1.92 bits in LHCP and in RHCP. As a first step towards a reflectarray in dual-CP, this innovative unit-cell is studied in an array configuration. To increase the value of the maximum incidence angle up to 30°, a matching dielectric layer is placed over the cell
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