Discriminant of a generic projection of a minimal normal surface singularity

Let (S,0) be a rational complex surface singularity with reduced fundamental cycle, also known as a minimal singularity. Using a fundamental result of M. Spivakovsky, we explain how to describe the equisingularity type of the discriminant curve for a generic projection of (S,0) onto $\text{(}\text{C}{}^2\text{,0)}$ from the resolution of (S,0). To cite this article: R. Bondil, C. R. Acad. Sci. Paris, Ser. I 337 (2003).     

Efficient indirect electrochemical in-situ regeneration of nadh:electrochemically driven enzymatic reduction of pyruvate catalyzed by d-ldh

Using [Cp(Me)₅Rh(bipy)C1]C1 (1) as redox catalyst for the continous NADH regeneration it was possible to perform an electrochemically driven enzymatic reduction of pyruvate to D-lactate catalyzed by D-LDH at a rate of 5 turnovers per hour. This is by a factor of 20 faster than the best results obtained until now. Current yields of 50 to 70 % may be obtained.     

Catalyseurs Zieger-Natta supportés sur MgCl2 pour la polymérisation stéréorégulée du propène. II. Système catalytique simple: Solide binaire MgCl2-TiCl4 et solution cocatalytique triéthylaluminium,benzoate d'ethyle

The kinetics of propene polymerization in heptane slurry at 1–4 bars was studied with a catalytic system that consisted of a solid catalyst prepared by adsorption of TiCI₄ on pure porous MgCl₂ (by dehydrating MgCl₂, 6 H₂O with thionyl chloride) and a cocatalytic, heptanic solution of ethylbenzoate (BE) and triethylaluminium (TEA). At a temperature approaching 60°C/polymerization began immediately after the introduction of the monomer. The polymerization rate decreased continuously during the reaction. The loss in activity, however, was not due to a diffusional effect (e.g., blocking of the catalyst by the growing polymer). Studies of the ageing of the catalytic system showed a deactivation of the catalytic system itself as a function of the time of contact between the catalyst and the cocatalyst. The product of the thermal decomposition of the complex 1:2 formed by the reaction of BE with TEA was not associated with the deactivation process or stereospecific control, which depend on the BE/AI ratio and the presence of the complex.     

Colorful Friedel-Crafts chemistry of meso-tetraarylporphyrins. An unexpected route to porphyrinic spiro dimers

Under Friedel-Crafts conditions, meso-tetraarylporphyrins give porphyrin spiro dimers in good yield. This reaction involves acylation, acid-catalyzed cyclization, and dimerization. A stable dimer possessing three additional six-membered rings could be isolated and its structure determined. By modifying the substrate and reagents, intermediates could be isolated and characterized. The reactivity of the substrates, the side-reactions, and the concentration requirements to form the dimers, all explain why this reaction remained apparently unexplored in the widely used meso-tetraarylporphyrin series. [reaction: see text]     

Heptakis-6-(5-methylene-thioureido-5′-methyl-2,2′-bipyridyl)-β-cyclodextrin: synthesis and metal complexation study

A new heptapode heptakis-6-(5-methylene-thioureido-5′-methyl-2,2′-bipyridyl)-β-cyclodextrin was prepared and its complexation properties towards metal cations were investigated. Substituting the urea functions by the corresponding thioureas promoted the inversion of the metal coordination selectivity. Preliminary results showed the heptapode unable to complex lanthanides but authorise selective complexation of ‘soft’ and ‘borderline’ metal cations.     

Ultrasensitive single-cell proteomics workflow identifies >1000 protein groups per mammalian cell

We report on the combination of nanodroplet sample preparation, ultra-low-flow nanoLC, high-field asymmetric ion mobility spectrometry (FAIMS), and the latest-generation Orbitrap Eclipse Tribrid mass spectrometer for greatly improved single-cell proteome profiling. FAIMS effectively filtered out singly charged ions for more effective MS analysis of multiply charged peptides, resulting in an average of 1056 protein groups identified from single HeLa cells without MS1-level feature matching. This is 2.3 times more identifications than without FAIMS and a far greater level of proteome coverage for single mammalian cells than has been previously reported for a label-free study. Differential analysis of single microdissected motor neurons and interneurons from human spinal tissue indicated a similar level of proteome coverage, and the two subpopulations of cells were readily differentiated based on single-cell label-free quantification.

The combination of nanodroplet sample preparation, ultra-low-flow nanoLC, high-field asymmetric ion mobility spectrometry (FAIMS) and latest-generation mass spectrometry instrumentation provides dramatically improved single-cell proteome profiling.     

A new symmetrically modified α-cyclodextrin tripode: selective metal complexation and fluorescence properties

A new tripodal α-cyclodextrin having three ureido-bipyridyl tethers symmetrically distributed on its upper rim was prepared in one step by the polymer supported ‘phosphine imide’ reaction in a medium yield. As expected, the highly selective complexation properties towards ‘hard’ and ‘soft’ cations were maintained with regards to the URFT-Cd (upper rim fully tethered) family previously investigated. Its Eu^III and Tb^III lanthanide complex fluorescence behaviour clearly indicates that a limited number of tethers allow a better bis-heterocyclic antenna self-organisation around the cation leading to enhanced fluorescence properties.     

Channel-Type Molecular Structures. Part 2. Synthesis of Bouquet-Shaped Molecules Based on a β-Cyclodextrin Core

A new series of channel-type molecules presenting the features of potential transmembrane structures is described. They result from the grafting of amphiphilic side chains on a β-cyclodextrin derivative 3 that constitutes the organizing core. They belong to the ‘bouquet’ family (B). Compounds bearing poly(oxyethylene) side chains, B 16 and 17 , and their polymethylene analogues B 18 and 19 , were synthesized. The properties investigated emphasize the suitability of such molecules to be incorporated into lipid bilayer membranes.