10 research outputs found
A benzoxazine/substituted borazine composite coating: A new resin for improving the corrosion resistance of the pristine benzoxazine coating applied on aluminum
Get PDFIn this paper, laboratory synthesized Phenol-paraPhenyleneDiAmine (P-pPDA) benzoxazine containing different amounts of B-trimesityl-N-triphenylborazine was applied by spin coating on aluminum and thermally cured. The addition of the borazine derivative (borazine 1) does not appear to modify the curing characteristics of the P-pPDA matrix itself as shown by FTIR, DSC and DEA analyses; however, some interactions - chemical and/or physical (co-crystallization) – between P-pPDA and borazine 1 cannot be excluded. The microstructure of the composites is characterized by a two phase system consisting of a dispersion of nanosized (10–20 nm) clusters for the lowest borazine 1 concentration (0.5 wt%), evolving towards bigger (100–200 nm), agglomerated clusters for higher borazine 1 concentrations (3 wt%) and finally, continuous, dendritic structures within the P-pPDA matrix for the highest borazine 1 concentration (10 wt%). The benzoxazine composite coating containing 0.5 wt% trimesitylborazine derivative showed a largely increased and durable ability to protect the aluminum substrate. It is shown that a highly capacitive behavior and durable barrier properties can be obtained for P-pPDA coatings containing such a low amount of borazine derivative homogeneously dispersed in the benzoxazine matrix. For concentrations of 3 wt%, as agglomeration took place and dendrites appeared for the highest concentration of borazine derivative (10 wt%), the corrosion resistance decreased with time
Contribution à l'étude des systèmes de transmission multi-antennes (codage spatio-temporel) [et] des turbo-codes associés à des modulations à haute efficacité spectrale
No full textCe document de thèse s'attache d'abord à étudier les performances de schémas de codage de type turbo associés à des modulations à hautes efficacité spectrale (MDP8, MAQ16). Nous distinguons principalement les cas d'un entrelacement au niveau de bits et d'un entrelacement au niveau de symboles. Nous détaillons le principe de fonctionnement de chacun des schémas et comparons leurs performances pour des transmissions sur des canaux de Gauss et des canaux de Rayleigh non sélectifs en fréquence. Puis, nous abordons le contexte des transmissions multi-antennes. Un premier chapitre est consacré à l'étude de la capacité des systèmes MIMO et met bien en évidence l'accroissement potentiel très important apporté par ce type d'architecture. Cependant pour bien profiter de la diversité spatiale offerte par les systèmes MIMO, il faut pouvoir en réception éliminer les signaux interférents. Nous proposons et étudions plusieurs techniques depuis la plus simple architecture de type VBLAST jusqu'aux codes spatio-temporels de type STBC ou STTC. En particulier, dans le cadre des codes STBC, nous avons développé un calcul original de borne supérieure très précise, et dans le cadre de l'étude des codes STTC, nous avons proposé un nouveau type de code qui combine l'avantage en diversité des codes STBC avec le gain de codage STTCLIMOGES-BU Sciences (870852109) / SudocSudocFranceF
hnRNP H/F drive RNA G-quadruplex-mediated translation linked to genomic instability and therapy resistance in glioblastoma
No full textRNA G-quadruplexes (RG4s) are four-stranded structures known to control mRNA translation of cancer relevant genes. RG4 formation is pervasive in vitro but not in cellulo, indicating the existence of poorly characterized molecular machinery that remodels RG4s and maintains them unfolded. Here, we performed a quantitative proteomic screen to identify cytosolic proteins that interact with a canonical RG4 in its folded and unfolded conformation. Our results identified hnRNP H/F as important components of the cytoplasmic machinery modulating the structural integrity of RG4s, revealed their function in RG4-mediated translation and uncovered the underlying molecular mechanism impacting the cellular stress response linked to the outcome of glioblastoma
