Variational inequalities with varying obstacles: The general form of the limit problem

When minimizing a functional of the calculus of variations with varying constraints of obstacle type, it may happen that, in the limit problem (when it exists), the constraint is no longer of obstacle type; it may take a “relaxed” form. This situation is analysed in this paper. Following De Giorgi's Γ-convergence approach, a class of functionals is constructed which is compact and which contains the obstacle constraint functionals. In this sense, this class of problems has been closed.     

Analyse par spectrométrie d'absorption infrarouge jusqu'à - 180 °C,de la structure cristalline des mélanges chloroforme-acétonitrile et chloroforme-propionitrile

A study, by infrared spectroscopy between 5000 and 200 cm^?1, in the liquid and solid states down to ? 180 °C, confirms the results obtained by thermal analysis: there is a complex in the case of ethyl cyanide-chloroform mixtures, whereas in the case of methyl cyanide-chloroform mixtures a eutectic is obtained. Furthermore we show, by the analysis of vibrations of the molecular lattice obtained, that, in this eutectic, the chloroform influences the crystalline structure of methyl cyanide.     

Dispositif de prelevement microanalytique de produits alterables

A small glass device is described for microanalytical or submicroanalytical sampling of unstable solid or liquid substances, in an argon atmosphere.

Zusammenfassung

Ein kleines Glasgerät wird beschrieben, das die Probenahme für die Mikrooder Submikroanalyse instabiler fester oder flüssiger Substanzen in Argonatmosphäre erlaubt.     

Etude de l'action de l'oxyde d'azote (III) sur l'indène et ses homologues

Addition of nitrogen trioxide to indene and alkylindenes N₂O₃ adds to indene and homologous yelding pseudonitrosites which are converted to aminoindanes. Treatment of the pseudonitrosites with alcoholic potassium hydroxide gives the correspondent nitroindenes.     

Dextran-coated silica nanoparticles for calcium-sensing

This article describes the synthesis and characterisation of fluorescent composite nanoparticles consisting of a silica core and a dextran shell. The silica core contains a rhodamine-based reference dye, which allows ratiometric measurements and the dextran shell is labelled with the Ca(2+)-sensitive dye Fluo-4. The nanoparticles have an average hydrodynamic diameter of 95 nm, good colloidal stability and show a 2.9-fold increase in fluorescence intensity upon binding to Ca(2+) ions. The apparent dissociation constant of K'(d) ≈ 520 nM is well suited for measurements in the physiological range.     

Rational design of lanthanide binding peptides

Lanthanide-binding peptides are very attractive for the design of bioprobes. Indeed, they combine the amazing properties of lanthanide ions, such as their time-resolved luminescence (Eu, Tb) or electronic relaxation (Gd) to the characteristics of the peptide scaffold, such as large solubility in water and ability to recognize biological substrates. Peptides derived from natural amino acids are reviewed in a first section. Some of their lanthanide complexes have already demonstrated their efficiency in determining protein structures and functions. Then, we will show how insertion of chelating unnatural amino acids modulates peptide-lanthanide complexes properties, such as luminescence and stability.     

Transformation of Receptor Tyrosine Kinases into Glutamate Receptors and Photoreceptors

Receptor tyrosine kinases (RTKs) are key regulators of cellular functions in metazoans. In vertebrates, RTKs are mostly activated by polypeptides but are not naturally sensitive to amino acids or light. Taking inspiration from Venus kinase receptors (VKRs), an atypical family of RTKs found in nature, we have transformed the human insulin (hIR) and hepatocyte growth factor receptor (hMET) into glutamate receptors by replacing their extracellular binding domains with the ligand‐binding domain of metabotropic glutamate receptor type 2 (mGluR2). We then imparted light sensitivity through covalent attachment of a synthetic glutamate‐based photoswitch via a self‐labelling SNAP tag. By employing a Xenopus laevis oocyte kinase activity assay, we demonstrate how these chimeric RTKs, termed light‐controlled human insulin receptor (LihIR) and light‐controlled human MET receptor (LihMET), can be used to exert optical control over the insulin or MET signaling pathways. Our results outline a potentially general strategy to convert RTKs into photoreceptors.     

DNA–Polymer Nanostructures by RAFT Polymerization and Polymerization‐Induced Self‐Assembly

Nanostructures derived from amphiphilic DNA–polymer conjugates have emerged prominently due to their rich self‐assembly behavior; however, their synthesis is traditionally challenging. Here, we report a novel platform technology towards DNA–polymer nanostructures of various shapes by leveraging polymerization‐induced self‐assembly (PISA) for polymerization from single‐stranded DNA (ssDNA). A “grafting from” protocol for thermal RAFT polymerization from ssDNA under ambient conditions was developed and utilized for the synthesis of functional DNA–polymer conjugates and DNA–diblock conjugates derived from acrylates and acrylamides. Using this method, PISA was applied to manufacture isotropic and anisotropic DNA–polymer nanostructures by varying the chain length of the polymer block. The resulting nanostructures were further functionalized by hybridization with a dye‐labelled complementary ssDNA, thus establishing PISA as a powerful route towards intrinsically functional DNA–polymer nanostructures.