Gold-Silver Mineralization in Submarine Hydrothermal Sulphides: INAA Results After Ten Years of Intense Prospecting

During the last twenty years, IFREMER has organized many diving cruises to collect geological, mineralogical and geochemical data on submarine hydrothermal mineralization. Gold and chalcophile trace elements have been determined by instrumental neutron activation analysis (INAA) in Pierre Süe Laboratory. Particularly for gold and silver determination, but also for In, As, Sb, Se, INAA is the most sensitive instrumental procedure. Typically, the East-Pacific Rise (EPR) deposits are gold-poor compared with the Mid-Atlantic Ridge (MAR) and the Lau Basin deposits. Our INAA data plotted in a Au-Ag diagram support the difference between back-are basin mineralization and spreading oceanic ridges. The most interesting samples for gold prospecting have been discovered in the Logatchev hydrothermal field at 14°45 N on the Mid-Atlantic Ridge: they show an exceptionally high mean content of gold, about 9 ppm, with a maximum of 56 ppm for one sample which contains significant amounts of native gold and electrum. It is the first conclusive evidence of a primary gold-copper association in seafloor sulphides. This may be compared with fossil hydrothermal deposits from the Oman ophiolitic complex.     

Chelation‐Assisted Cross‐Coupling of Anilines through In Situ Activation as Diazonium Salts with Boronic Acids under Ligand‐, Base‐, and Salt‐Free Conditions

We describe the coupling of anilines with aryl boronic acids, under ligand‐, base‐, and salt‐free conditions at room temperature. This new reaction proceeds through the formation of an aryl palladium alkoxo complex, which allows the transmetalation step with aryl boronic acids without any external base. Importantly, this sustainable procedure generates only environmentally friendly byproducts such as tBuOH, H₂O, N₂, and B(OH)₃. The reaction mechanism has been deeply investigated through experimental and theoretical studies.     

Comparison between experimental and 2-D numerical studies of multiple scattering in Inconel600® by means of array probes

Ultrasonic non-destructive testing of polycrystalline structures can be disturbed by scattering at grain boundaries. Understanding and modeling this so-called “structural noise” is crucial for characterization as well as detection purposes. Structural noise can be considered as a fingerprint of the material under investigation, since it contains information about its microstructure. The interpretation of experimental data necessitates an accurate comprehension of complex phenomena that occur in multiple scattering media and thus robust scattering models. In particular, numerical models can offer the opportunity to realize parametrical studies on controlled microstructures. However, the ability of the model to simulate wave propagation in complex media must be validated. In that perspective, the main objective of the present work is to evaluate the ability of the finite-element code ATHENA 2D to reproduce typical features of multiple wave scattering in the context of ultrasonic non-destructive evaluation, with an array of sources and receivers. Experiments were carried out with a 64-element array, around 2 MHz. The sample was a mock-up of Inconel600® exhibiting a coarse grain structure with a known grain size distribution. The numerical model of this microstructure is based on Voronoi diagrams. Two physical parameters were used to compare numerical and experimental data: the coherent backscattering peak, and the singular value distribution of the array response matrix. Though the simulations are 2-D, a good agreement was found between simulated and experimental data.     

Exploration of cardanol-based phenolated and epoxidized resins by size exclusion chromatography and MALDI mass spectrometry

Cardanol and cardanol derivatives are among the most important biobased materials currently investigated in green chemistry, as renewable and promising building blocks in lieu of traditional raw materials from non renewable resources, in particular owing to the olefinic linkages on the C15 alkyl side-chain. Despite the increasing interest they arouse, analytical chemistry dedicated to cardanol and associated resins has been rarely reported in the literature, found even poorer when dealing with chromatography and mass spectrometry. In this work, a thorough molecular characterization was conducted using matrix assisted laser desorption ionization (MALDI) mass spectrometry, size exclusion chromatography (SEC), and SEC–MALDI coupling to gain insights into the composition of phenolated, epoxidized, and epoxidized phenolated cardanol. A nomenclature was proposed to properly describe the numerous species found in these materials, while simulations of the unsaturation patterns and their comparison with the detected patterns in MALDI-MS gave useful details about the phenolation treatment expected to occur on the polyunsaturated C15 side chain. Finally, the SEC–MALDI off-line coupling allowed SEC peaks to be deconvoluted by mass spectrometry and MALDI artefacts related to matrix adduction to be pointed out.