UV-nanoimprint lithography and large area roll-to-roll texturization with hyperbranched polymer nanocomposites for light-trapping applications

Light-trapping textures were produced in hyperbranched polymer (HBP) silica nanocomposites using a UV-nanoimprint lithography (UVNIL) replication method, either in batch or roll-to-roll processes. The hardness of the HBP was found to increase by a factor of 2.5 with the addition of 50 vol% of nanoparticles. A nickel master with random sub-micron pyramidal structures was used to imprint nanocomposites containing up to 20 vol% of silica on a polyethylene naphthalate (PEN) substrate. The influence of nanoparticle fraction and pressure on the texture morphology and light scattering properties of the replicas was studied using scanning electron microscopy and optical analysis. The roughness and coherence length of the textures were similar to those of the master for all investigated compositions and process pressures. Likewise, the light scattering performance of aluminum-coated texturized nanocomposites was identical to that of the metal template, with a haze of 90% over the 400–800 nm spectral range. Thin film amorphous silicon solar cells were deposited on the texturized substrates using a large-area roll-to-roll process. The photocurrent of these devices was found to be 23% higher than the reference value of a flat cell

Niche-specific regulation of central metabolic pathways in a fungal pathogen

To establish an infection, the pathogen Candida albicans must assimilate carbon and grow in its mammalian host. This fungus assimilates six-carbon compounds via the glycolytic pathway, and two-carbon compounds via the glyoxylate cycle and gluconeogenesis. We address a paradox regarding the roles of these central metabolic pathways in C. albicans pathogenesis: the glyoxylate cycle is apparently required for virulence although glyoxylate cycle genes are repressed by glucose at concentrations present in the bloodstream. Using GFP fusions, we confirm that glyoxylate cycle and gluconeogenic genes in C. albicans are repressed by physiologically relevant concentrations of glucose, and show that these genes are inactive in the majority of fungal cells infecting the mouse kidney. However, these pathways are induced following phagocytosis by macrophages or neutrophils. In contrast, glycolytic genes are not induced following phagocytosis and are expressed in infected kidney. Mutations in all three pathways attenuate the virulence of this fungus, highlighting the importance of central carbon metabolism for the establishment of C. albicans infections. We conclude that C. albicans displays a metabolic program whereby the glyoxylate cycle and gluconeogenesis are activated early, when the pathogen is phagocytosed by host cells, while the subsequent progression of systemic disease is dependent upon glycolysis

Multi-functional magnetic photoluminescent photocatalytic polystyrene-based micro- and nano-fibers Obtained by electrospinning

This work reports on the implementation of electrospinning (ES) as a facile route to encapsulate nano-engineered materials in a polystyrene (PS) matrix. We applied ES to co-encapsulate two kinds of nanoparticles, i.e., upconversion nanophosphors (UCNPs) and superparamagnetic iron oxide nanoparticles (SPIONs), in polystyrene (PS)-based micro- and nano-fibers (PSFs). This approach made it possible to integrate near-infrared (NIR) light-sensitive 500-nm β-NaYF₄:Yb, Er UCNPs with 10-nm γ-Fe₂O₃ SPIONs in PS fibers. During the ES process, PSFs were additionally loaded with a well-established singlet oxygen (¹∆g) photosensitizer, rose bengal (RB). The thus obtained PSFs revealed the promising features of prospective multi-functional magnetic photoluminescent photocatalytic nano-constructs

Combined Cr and S poisoning in solid oxide fuel cell cathodes

This work aims to compare the effect of combined chromium and sulfur contaminating conditions to the Cr contamination alone on the Cr poisoning mechanisms in (La,Sr)MnO3-(Zr,Y)O-2 solid oxide fuel cell (SOFC) cathodes. Whereas Cr2O3 and (Cr,Mn)(3)O-4 are found at active triple phase boundaries under the Cr-poisoning condition, the formation of SrCrO4 is promoted under combined Cr and S contaminating conditions, where Cr accumulations act as getters incorporating sulfur, to form Sr(Cr,S)O-4 compounds. The identification of this phase is validated on the synthesized and simulated species by scanning/transmission electron microscopy (SEM/TEM) techniques; its possible formation is predicted by thermodynamic analysis of the stability of perovskite compounds in the presence of combined Cr and S polluting conditions. In contrast, sulfur alone is not found to poison active sites in these composite cathodes. These findings suggest that the Cr poisoning degradation mechanism is altered when (La,Sr)MnO3 is exposed to Cr vapors in the presence of sulfur contamination; the access to electrochemical active sites may be hindered by the formation of Sr(Cr,S)O-4 in a similar manner to a Cr-getter effect in (La,Sr)(Co,Fe)O-3 cathodes. (C) 2011 Elsevier B.V. All rights reserved

Démonette-2, une base de données dérivationnelle du français à large couverture lexicale munie de descriptions morphologiques détaillées

International audienceMorphological databases play an important role in linguistic research today. While several exist for the study of inflectional morphology in French, there is still a lack of resources for derivational morphology. This article presents Démonette-2, a new release of the French derivational morphology database Démonette. Developed in the context of the Démonext project, this database provides a framework in which it is possible to integrate various existing derivational resources. Démonette is characterized by its relational nature, which makes it possible to describe an extensive set of word formation patterns, including suffixation, prefixation, and a variety of non-canonical derivational processes such as conversion and parasynthetic formations. It reconciles broad coverage and fine-grained descriptions and is suitable for different audiences: morphologists working in different theoretical frameworks, teachers, speech therapists, NLP specialists, etc. The article presents in detail the structure and content of Démonette, its evolution since the first version, and its query interface.Les bases de données morphologiques jouent aujourd’hui un rôle important dans les recherches en linguistique. S’il en existe plusieurs pour les études de morphologie flexionnelle pour le français, l’offre reste insuffisante pour la morphologie dérivationnelle. Cet article présente Démonette-2, une nouvelle version de la base de données morphologique dérivationnelle du français Démonette. Développée dans le cadre du projet Démonext, cette base offre un cadre dans lequel il est possible d’intégrer diverses ressources dérivationnelles existantes. Démonette se caractérise par sa nature relationnelle qui permet d’y décrire un ensemble étendu de constructions morphologiques qui inclut les procédés de suffixation, de préfixation, et une grande variété de dérivations non canoniques comme la conversion et les constructions parasynthétiques. Elle concilie couverture étendue et finesse des descriptions et est adaptée à différents publics cibles : morphologues travaillant dans différents cadres théoriques, enseignants, orthophonistes, spécialistes de TAL, etc. L’article présente en détail la structure et le contenu de Démonette, son évolution depuis la première version et son interface d’interrogation