Preparation of thin-sections of painting fragments: Classical and innovative strategies

For more than a century, the analyses of painting fragments have been carried out mainly through the preparation of thick resin-embedded cross-sections. Taking into account the development of innovative micro-analytical imaging techniques, alternatives to this standard preparation method are considered. Consequently, dedicated efforts are required to develop preparation protocols limiting the risks of chemical interferences (solubilisation, reduction/oxidation or other reactions) which modify the sample during its preparation, as well as the risks of analytical interferences (overlap of detected signals coming from the sample and from materials used in the preparation). This study focuses particularly on the preparation of thin-sections (1–20 μm) for single or combined fourier transform infrared (FTIR) spectroscopy and X-ray 2D micro-analysis. A few strategies specially developed for the μFTIR analysis of painting cross-sections have already been reported and their potential extrapolation to the preparation of thin-sections is discussed. In addition, we propose two new specific methods: (i) the first is based on a free-embedding approach, ensuring a complete chemical and analytical neutrality. It is illustrated through application on polymeric design objects corpus; (ii) the second is based on a barrier coating approach which strengthens the sample and avoids the penetration of the resin into the sample. The barrier coating investigated is a silver chloride salt, an infrared transparent material, which remains malleable and soft after pellet compression, enabling microtoming. This last method was successfully applied to the preparation of a fragment from a gilded Chinese sculpture (15th C.) and was used to unravel a unique complex stratigraphy when combining μFTIR and μXRF.     

Importance of temporal-envelope speech cues in different spectral regions

This study investigated the ability to use temporal-envelope (E) cues in a consonant identification task when presented within one or two frequency bands. Syllables were split into five bands spanning the range 70-7300 Hz with each band processed to preserve E cues and degrade temporal fine-structure cues. Identification scores were measured for normal-hearing listeners in quiet for individual processed bands and for pairs of bands. Consistent patterns of results were obtained in both the single- and dual-band conditions: identification scores increased systematically with band center frequency, showing that E cues in the higher bands (1.8-7.3 kHz) convey greater information.     

Zur Bestimmung des Nickels als Nickeldioxyd

Ohne Zusammenfassung     

Structure of a Complex Formed by a Protein and a Helical Aromatic Oligoamide Foldamer at 2.1 Å Resolution

In the search of molecules that could recognize sizeable areas of protein surfaces, a series of ten helical aromatic oligoamide foldamers was synthesized on solid phase. The foldamers comprise three to five monomers carrying various proteinogenic side chains, and exist as racemic mixtures of interconverting right‐handed and left‐handed helices. Functionalization of the foldamers by a nanomolar ligand of human carbonic anhydrase II (HCA) ensured that they would be held in close proximity to the protein surface. Foldamer–protein interactions were screened by circular dichroism (CD). One foldamer displayed intense CD bands indicating that a preferred helix handedness is induced upon interacting with the protein surface. The crystal structure of the complex between this foldamer and HCA could be resolved at 2.1 Å resolution and revealed a number of unanticipated protein–foldamer, foldamer–foldamer, and protein–protein interactions.     

A practical mild, one-pot, regiospecific synthesis of 2,3-disubstituted indoles via consecutive Sonogashira and Cacchi reactions

[Structure: see text] A practical one-pot, regiospecific three-component process for the synthesis of 2,3-disubstituted indoles was developed via consecutive Pd-catalyzed Sonogashira coupling, amidopalladation, and reductive elimination.