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A nanoscale thin film of niobium oxide on a platinum substrate was evaluated for its influence on the electronic and chemical properties of the underlying platinum towards the oxygen reduction reaction with applications to proton exchange membrane fuel cells. The nanoscale thin film of niobium oxide was deposited using atomic layer deposition onto the platinum substrate. A film of niobium oxide is a chemically stable and electronically insulating material that can be used to prevent corrosion and electrochemical degradation when layers are several nanometers thick. These layers can be insulating if sufficiently thick and may not be sufficient to protect the platinum from corrosion if too thin. An ~3 nm thin film of niobium oxide was fabricated on the platinum surface to determine its influence on the electronic and chemical properties at the interface of these materials. The atomic layer deposition process enabled a precise control over the material composition, structure, and layer thickness. The niobium oxide film was evaluated using cyclic voltammetry and electrochemical impedance spectroscopy to evaluate whether a balance could be found between the inhibition of platinum degradation and electronic insulation of the platinum for use in proton exchange membrane fuel cells. The 3 nm thin niobium oxide film was found to be sufficiently thin to permit electronic conductivity while reducing the incidence of platinum dissolution. Key words: proton exchange membrane fuel cell, atomic layer deposition, niobium oxide, platinum, degradation. Nous avons etudie un film mince d'oxyde de niobium, depose a l'echelle nanometrique sur un substrat de platine, afin d'evaluer son influence sur les proprietes electroniques et chimiques du platine sous-jacent lors de la reaction de reduction de l'oxygene, ainsi que ses applications a des piles a combustible a membrane echangeuse de protons. Nous avons forme le film mince d'oxyde de niobium a l'echelle nanometrique par depot de couches atomiques sur le substrat de platine. Un film d'oxyde de niobium est un materiau chimiquement stable et electroniquement isolant qui, lorsqu'il est depose en couches d'une epaisseur de plusieurs nanometres, peut etre utilise pour prevenir la degradation electrochimique et la corrosion. Cependant, si ces couches sont trop epaisses, elles peuvent etre isolantes; et si elles sont trop minces, elles pourraient etre insuffisantes pour proteger le platine de la corrosion. Nous avons fabrique un film mince d'oxyde de niobium d'environ 3 nm a la surface du platine afin de determiner comment il influence les proprietes electroniques et chimiques a la surface de ces materiaux. La methode de depot en couches atomiques a permis de regler avec precision la composition et la structure du materiau ainsi que l'epaisseur du film. Nous avons evalue le film d'oxyde de niobium par voltamperometrie cyclique et spectroscopie d'impedance electrochimique afin de voir s'il etait possible de trouver un equilibre entre l'inhibition de la degradation du platine et son isolation electronique qui puisse convenir a une utilisation dans des piles a combustible a membrane echangeuse de protons. Nos resultats montrent que le film d'oxyde de niobium de 3 nm d'epaisseur etait suffisamment mince pour permettre une conductivite electronique tout en reduisant l'incidence de la dissolution du platine. [Traduit par la Redaction] Mots-cles : pile a combustible a membrane echangeuse de protons, depot de couches atomiques, oxyde de niobium, platine, degradation., Introduction To ensure competitiveness in the growing alternative energy sector for automotive applications, the next generation of proton exchange membrane fuel cells (PEMFCs) must exhibit enhanced durability under a variety [...]

CD161++ CD8+ T cells represent a novel subset that is dominated in adult peripheral blood by mucosal-associated invariant T ( MAIT) cells, as defined by the expression of a variable-α chain 7.2 ( Vα7.2)- Jα33 TCR, and IL-18 Rα. Stimulation with IL-18+ IL-12 is known to induce IFN-γ by both NK cells and, to a more limited extent, T cells. Here, we show the CD161++ CD8+ T-cell population is the primary T-cell population triggered by this mechanism. Both CD161++ Vα7.2+ and CD161++ Vα7.2− T-cell subsets responded to IL-12+ IL-18 stimulation, demonstrating this response was not restricted to the MAIT cells, but to the CD161++ phenotype. Bacteria and TLR agonists also indirectly triggered IFN-γ expression via IL-12 and IL-18. These data show that CD161++ T cells are the predominant T-cell population that responds directly to IL-12+ IL-18 stimulation. Furthermore, our findings broaden the potential role of MAIT cells beyond bacterial responsiveness to potentially include viral infections and other inflammatory stimuli. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) store latent heat energy as they melt and release it upon freezing. However, they suffer from chemical instability and poor thermal conductivity, which can be improved by encapsulation. Here, we encapsulated a salt hydrate PCM (Mg(NO 3 ) 2 ·6H 2 O) within all-silica nanocapsules using a Pickering emulsion template. Electron microscopy analysis demonstrated robust silica-silica (RSS) shell formed inner silica layer of approximately 45 nm thickness, with silica Pickering emulsifiers anchored to the surface. The RSS nanostructured capsules are 300-1000 nm in size and have far superior thermal and chemical stability compared with that of the bulk salt hydrate. Differential scanning calorimetry showed encapsulated PCMs were stable over 500+ melt/freeze cycles (equivalent to 500+ day/night temperature difference) with a latent heat of 112.8 J·g -1 . Thermogravimetric analysis displayed their impressive thermal stability, with as little as 37.2% mass loss at 800 °C. Raman spectroscopy proved the presence of salt hydrate within RSS capsules and illustrated the improved chemical stability compared to non-encapsulated Mg(NO 3 ) 2 ·6H 2 O. Energy capsule behavior compared with the bulk material was also observed at the macroscale with thermal imaging, showing that the melting/freezing behavior of the PCM is confined to the nanocapsule core. The thermal conductivity of the silica shell measured by laser flash thermal conductivity method is 1.4 ± 0.2 W·(m·K) -1 , which is around 7 times more than the thermal conductivity of the polymer shell (0.2 W·(m·K) -1 ). RSS capsules containing PCMs have improved thermal stability and conductivity compared to polymer-based capsules and have good potential for thermoregulation or energy storage applications.

Mucosal-associated invariant T (MAIT) cells are an abundant innate-like T cell subset in humans, enriched in mucosal tissues and the liver. MAIT cells express a semi-invariant T cell receptor (TCR) and recognize microbial-derived riboflavin metabolites presented on the MHC Class I-like molecule MR1. In addition to activation via the TCR, MAIT cells can also be activated in response to cytokines such as IL-12 and IL-18, in contrast to conventional T cells. Here we describe TCR-dependent and -independent methods for MAIT cell activation. The TCR-dependent approaches include stimulation with microbead- or plate-bound anti-CD3/anti-CD28 antibodies, and with 5-OP-RU or paraformaldehyde (PFA)-fixed E. coli in the presence of antigen-presenting cells (APCs). The latter method includes a combination of TCR- and cytokine-mediated stimulation. The TCR-independent methods include direct stimulation with the recombinant cytokines IL-12 and IL-18, and indirect stimulation with TLR-4/TLR-8 agonists or influenza A virus in the presence of APCs. Finally, we outline a protocol to analyze activated MAIT cells using flow cytometry.

Nanophotonics, dealing with the properties of light interacting with nanometer scale materials and structures, has emerged as a sought after platform for sensing and imaging applications, and is impacting fields that include advanced information technology, signal processing circuits, and cryptography. Lithium niobate (LiNbO 3 ) is a unique photonic material, often referred to as the "silicon of photonics" due to its excellent optical properties. In this article, we introduce a solution-phase method to prepare single-crystalline LiNbO 3 nanoparticles with average diameters of 7 nm. This one-pot approach forms well-dispersed LiNbO 3 nanocrystals without additional organic additives ( e.g. , surfactants) to control growth and aggregation of the nanoparticles. Formation of these LiNbO 3 nanocrystals proceeds through a non-aqueous sol-gel reaction, in which lithium hydroxide and niobium hydroxide species were generated in situ . The reaction proceeded through both a condensation and crystallization of these reactants to form the solid nanoparticles. These nanocrystals of LiNbO 3 were active for optical second harmonic generation (SHG) with a tunable response from 400 to 500 nm. These nanoparticles could enable further development of non-linear optical techniques such as SHG microscopy for bioimaging, which requires the dimensions of nanoparticles to be well below 100 nm., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

CD161(++) CD8(+) T cells represent a novel subset that is dominated in adult peripheral blood by mucosal-associated invariant T (MAIT) cells, as defined by the expression of a variable-α chain 7.2 (Vα7.2)-Jα33 TCR, and IL-18Rα. Stimulation with IL-18+IL-12 is known to induce IFN-γ by both NK cells and, to a more limited extent, T cells. Here, we show the CD161(++) CD8(+) T-cell population is the primary T-cell population triggered by this mechanism. Both CD161(++) Vα7.2(+) and CD161(++) Vα7.2(-) T-cell subsets responded to IL-12+IL-18 stimulation, demonstrating this response was not restricted to the MAIT cells, but to the CD161(++) phenotype. Bacteria and TLR agonists also indirectly triggered IFN-γ expression via IL-12 and IL-18. These data show that CD161(++) T cells are the predominant T-cell population that responds directly to IL-12+IL-18 stimulation. Furthermore, our findings broaden the potential role of MAIT cells beyond bacterial responsiveness to potentially include viral infections and other inflammatory stimuli., (© 2013 The Authors. European Journal of Immunology published by Wiley-VCH Verlag GmbH & Co. KGaA Weinheim.)