The nature of the active sites involved in the gold catalyzed Sonogashira cross-coupling reaction between iodobenzene and phenylacetylene, and in the competitive homocoupling reactions, has been investigated by means of DFT calculations, kinetic measurements, and synthesis of catalysts with different gold surface species. Several catalyst models have been theoretically investigated to simulate gold nanoparticles of different size either isolated, supported on inert materials, or supported on CeO 2 . The mechanistic studies show that IB dissociation occurs on low coordinated Au 0 atoms present in small gold nanoparticles, either isolated or supported, while PA is preferentially adsorbed and activated on Au δ+ species existing at the metal−support interface. When this occurs, the activation energy of the rate-determining step of the Sonogashira reaction, which has been found experimentally to be the bimolecular coupling, is minimized. The product distribution obtained with Au/CeO 2 catalysts containing different ratios of Au 0 /Au δ+ sites confirms the positive role played by cationic gold in the Sonogashira cross-coupling reaction. Importantly, only metallic Au 0 atoms present in gold nanoparticles are required to perform the homocoupling of iodobenzene.

An electron microscopy study, in combination with modeling and image simulation, of four different reconstituted ferritin samples: recombinant human H and L homopolymers, and H and L heteropolymers of native L-subunit-rich horse spleen and H-subunit-rich human heart ferritins, points out the existence of a correlation between iron core shape and protein shell.

A strong focus on Superparamagnetic Iron Oxide Nanoparticles (SPIOs) has been appreciated recently especially for their use in Magnetic Resonance Imaging (MRI). However, some questions are being raised over these particles due to their long-term toxicity related to the production of toxic free iron during their biodegradation. Here we show by Electron Microscopy how SPIOs (P904) (Guerbet, Paris) are degraded after they are taken up by macrophages, so that iron from the SPIO core is progressively incorporated into the iron-storing protein ferritin (a nontoxic form of iron).

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Ti-5Al-5V-5Mo-3Cr (Ti5553) is a metastable β titanium alloy with a high potential use in the aeronautic industry due to its high strength, excellent hardenability, fracture toughness and high fatigue resistance. However, recent research shows this alloy has a limited weldability. Different welding technologies have been applied in the literature to weld this alloy, such as electron beam welding (EBW), gas tungsten arc welding (GTAW) or laser beam welding (LBW) under keyhole regime. Thus, in tensile tests, joints normally break at the weld zones, the strength of the welds being always lower than that of the base metal. In the present work, a novel approach, based on the application of LBW under conduction regime (with a High-Power Diode Laser, HPDL), has been employed for the first time to weld this alloy. Microstructure, microhardness and strength of obtained welds were analyzed and reported in this paper. LBW under conduction regime (LBW-CR) leads to welds with slightly higher values of Ultimate Tensile Strength (UTS) than those previously obtained with other joining processes, probably due to the higher hardness of the fusion zone and to lower porosity of the weld.