Discovery of a palladium-platinum-gold-mercury bitumen in the Boss mine, Clark County, Nevada

A bitumen containing high concentrations of sulfur, palladium, platinum, gold, and mercury has been found in the Boss mine, Clark County, Nevada, where rich ores of 'invisible' palladium and platinum were mined from 1916 to 1919. The bitumen, analyzed with X-ray energy dispersive spectrometry on areas devoid of discrete particles down to a 40 Å limit, contains 2.74 wt percent Pd + Pt + Au (Pd = 1.85%) and 5.83 wt percent Hg. It is associated with particulate potarite (Pd, Au, Pt) Hg, native gold, plumbojarosite, hydronium jarosite, argentojarosite, florencite, and bismuth oxides. The first four mineral species are also found included in the bitumen. The paragenesis was derivation and formation of bitumen from the local limestone, followed by interaction with the hydrothermal potarite and the supergene jarosite. This type of organic material, highly enriched in platinum group elements, previously had been reported only in Polish Kupferschiefer thucholite.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

TiO2-supported Rh nanoparticles: From green catalyst preparation to application in arene hydrogenation in neat water

45-4 FIELD Section Title:Industrial Organic Chemicals, Leather, Fats, and Waxes 67 Ecole Nationale Superieure de Chimie de Rennes, UMR 6226, CNRS, Rennes, Fr. FIELD URL: written in EnglishInternational audienceTiO2-supported Rh(0) nanoparticles were prepd. by an easy method under mild conditions in neat water. They proved to be highly active catalysts for arene hydrogenation in water with TOFs up to 33 333 h-1. [on SciFinder(R)

Using Prussian blue analogue nanoparticles confined into ordered mesoporous silica monoliths as precursors of oxides

International audiencePowdered Prussian blue analogues (PBAs) and PBAs confined in ordered mesoporous silica monoliths were used as oxide precursors through thermal treatment under an oxidizing atmosphere. The study focuses on the transformation of the alkali cation-free CoCo PBA of chemical formula K0.1CoII4[CoIII(CN)6]2.7·20 H2O. The compounds were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), IR spectroscopy and small-angle X-ray scattering (SAXS), and the magnetic properties of the calcined samples were investigated. In both cases, powdered and confined PBAs, the coordination polymers are transformed into well-crystallized Co3O4 spinel oxide. In the case of the confined PBA, isolated Co3O4 single crystals confined within the ordered mesoporosity of the monoliths were evidenced by HRTEM. A preliminary study shows an effect of particle size and confinement on the magnetic properties of the confined oxide particles

From mesoporous alumina to Pt/Al2O3 catalyst: A comparative study of the aluminas synthesis in aqueous medium, physicochemical properties and stability

International audienc

Co, Fe and CoFe oxide nanoparticle assemblies within an ordered silica matrix: effects of the metal ions and synthesis pathway on the microstructure and magnetic properties

The magnetic properties of nanoparticle assemblies strongly depend on the structural and morphological characteristics of the individual nanoparticles as well as on their organization within the assembly. Here, we present the synthesis of cobalt and/or iron oxide nanoparticles within the ordered mesoporosity of a silica monolith by two different synthesis pathways (using either Prussian blue analogues or nitrate salts as a precursor). We describe the influence of the nature of the metal ion and of the synthesis pathway on the morphology of the nanoparticles. With respect to these observations, we present and discuss the temperature-dependent magnetic behaviors of the final nanocomposites

Facile synthesis of palladium nanowires by a soft templating method

International audienceVery long and thin monocrystalline Pd nanowires were synthesized by decomposition using hydrazine vapour treatment of Pd2(DBA)3 confined in the oil phase of a hexagonal mesophase. The mesophase is composed of toluene-swollen tubes, doped with the Pd precursor, stabilized by a monolayer of surfactant and cosurfactant molecules, and arranged on a triangular lattice in water. Our synthesis is selective and the experiments show that both the confinement and the nature of the surfactant are essential to obtain these Pd nanowires

Fluorescent core-shell nanoparticles and nanocapsules using comb-like macromolecular RAFT agents: synthesis and functionalization thereof

International audienceFluorescent nanoparticles and nanocapsules (FNPs) were synthesized via a one-pot RAFT miniemulsion process copolymerizing BODIPY-methacrylate and styrene in water. Ultra-bright sub-100 nm core–shell nanoparticles could be obtained with BODIPY covalently linked in the core, and possessing various shells. The nature and architecture of the particle shells could be tuned by using different macromolecular RAFT (macro-RAFT) agents in the miniemulsion polymerization process. The macro-RAFT agents were composed of poly(ethylene oxide) acrylate (PEOA) and/or acrylic acid (AA), owing to their biocompatibility and functionality respectively, in different proportions. Interestingly, with comb-like macro-RAFT agents comprising a high number of PEOA, nanocapsules were formed, while with linear macro-RAFT agents or with those exhibiting a high number of AA, full core–shell nanoparticles were obtained. For all the structures the control over the polymerization, the size, morphology, and zeta-potential as well as the photophysical properties were measured and compared with FNPs exhibiting a linear PEO-b-PAA block copolymer shell structure (C. Grazon, J. Rieger, R. Méallet-Renault, G. Clavier and B. Charleux, Macromol. Rapid Commun., 2011, 32, 699). Regardless of the shell structures, the brightness of the formed nanoparticles was estimated to be 100–1000 times higher than that of quantum dots. Ultimately, the shell of the different FNPs was functionalized with a second fluorophore via the AA's carboxyl groups. Thus, water-soluble ultra-bright FNPs with two fluorophores in distinct environments (water and in polystyrene) were obtained. They should have great potential for bioimaging applications

Crystallization of β-MnO 2 Nanowires in the Pores of SBA-15 Silicas: In Situ Investigation Using Synchrotron Radiation

International audienceAn original preparation method, called “two solvents” method, allows the production ofMnO2 nanowires patterned by SBA-15 silicas under mild conditions, with a preserved twodimensionalhexagonal structure, a 97% filling of the porosity by oxide nanowires, and acontrolled microstructure. A comparison is made with Mn-loaded SBA-15 prepared by moreconventional adsorption methods. In the latter case, MnOx particles inside and outside thesilica grains, empty and filled mesopores, and several Mn oxides (MnO2, Mn2O3, and Mn3O4)were identified. Once the preparation method of Mn-loaded SBA-15 optimized, various X-rayscattering and adsorption techniques using synchrotron radiation were used to observe salientfeatures of the MnO2 nanowires crystallization in situ upon calcination. X-ray absorption atthe Mn K edge shows that the oxidation state of manganese increases from (II) to (IV)between 80 and 120 °C. The oxidation of the Mn(II) salt occurs at a temperature lower thanthat necessary for bulk manganese nitrate (200 °C), which confirms its confinement withinthe SBA-15 pores. â-MnO2 nanowires of defective pyrolusite type are identified by wideanglediffraction. The comparison between diffraction results and simulations demonstratesthat the nanowire diameter is similar to the mesopore diameter of the silica host. A smallcontraction of unit-cell parameters occurs upon the crystallization of â-MnO2 nanowires. Aparallel overall intensity increase observed in small-angle X-ray diffraction is the fingerprintof a homogeneously filled porosity