First approach to the use of liquid crystal elastomers for chemical sensors

Liquid crystalline thin films elastomers that are able to bind pesticides have been developed. The synthesis involves grafting mesogen and crosslinkable groups on a polysiloxane chain in the presence of a template molecule. The molecular imprinted material is obtained after thin film deposition, UV crosslinking and washing. Experiments of readsorption of pesticide are presented. Development of a multisensor platform based on thermal and capacitive sensors is described and tests of deposition of the polymer film are presented.     

Representation, searching and discovery of patterns of bases in complex RNA structures

We describe a graph theoretic method designed to perform efficient searches for substructural patterns in nucleic acid structural coordinate databases using a simplified vectorial representation. Two vectors represent each nucleic acid base and the relative positions of bases with respect to one another are described in terms of distances between the defined start and end points of the vectors on each base. These points comprise the nodes and the distances the edges of a graph, and a pattern search can then be performed using a subgraph isomorphism algorithm. The minimal representation was designed to facilitate searches for complex patterns but was first tested on simple, well-characterised arrangements of bases such as base pairs and GNRA-tetraloop receptor interactions. The method performed very well for these interaction types. A survey of side-by-side base interactions, of which the adenosine platform is the best known example, also locates examples of similar base rearrangements that we consider to be important in structural regulation. A number of examples were found, with GU platforms being particularly prevalent. A GC platform in the RNA of the Thermus thermophilus small ribosomal subunit is in an analogous position to an adenosine platform in other species. An unusual GG platform is also observed close to one of the substrate binding sites in Haloarcula marismortui large ribosomal subunit RNA.     

Surjectivité de l'application restriction à un compact dans des classes de fonctions ultradifférentiables

Résumé Etant donnée {M _p } _p0 une suite de réels strictement positifs, on considère la classe de CarlemanC{p!M _p } (resp. BeurlingB{p!M _p }) des fonctionsf indéfiniment dérivables sur ⁿ . SoitE un sous ensemble compact de ⁿ ; on peut associer à la classeC{p!M _p } (resp.B{p!M _p }) la classe des jets de Whitney surE,C _E {p!M _p }, (resp.B _E {p!M _p }) et on a une application de restriction naturelle deC{p!M _p } dansC _E {p!M _p } (resp.B{p!M _p } dansB _E {p!M _p }).Dans ce travail, on donne des conditions sur deux suites {M _p } _p0 et {M _p } _p0 pour que l'on ait les inclusions suivantes ou Ceci est, en quelque sorte, une généralisation du problème de prolongement de Whitney.

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1-AZA-1,3-dienes. Diels-alder reactions with α, β-unsaturated hydrazones.

The α,β unsaturated hydrazone $\text{3}$ reacts regioselectivity with a wide range of dienophiles to give the corresponding [4+2] adducts. Reductive cleavage of the NN bond in the adducts gives tetrahydropyridines.     

Synthesis of hybrid dendrimer-star polymers by the RAFT process

A first generation phosphorus-containing dendrimer with twelve terminal benzyl dithiobenzoate functions was designed and subsequently used as a multifunctional agent to derive hybrid star copolymers consisting of a dendritic core surrounded by twelve polystyrene branches by reversible addition-fragmentation chain transfer (RAFT).     

Pedicelloside,nouveau phtalide isole de gentiana pedicellata wall.

The title compound, isolated from $\text{Gentiana pedicellata}$ leaves, is a new alkyl-3-phthalide characterized by an acylated side chain. It has been identified by spectral analysis as [3-(1-β-D-glucosyloxy)-2-hydroxy]benzoyl 3-(3-phthalidyl)-propyl ester.     

An ab initio study of the proton affinities of some heteroatomic rings: Imidazole,oxazole, and thiazole

The proton affinities of imidazole, oxazole, and thiazole rings, relevant to the binding of lexitropsins that contain these rings to the minor groove of DNA, are calculated using ab initio (Hartree–Fock) calculations. It is found that the proton affinities decrease in the order imidazole, oxazole, thiazole and that a methyl group substituent increases the proton affinity of imidazole, while a peptidic group decreases it.     

Assembly and mechanical properties of phosphorus dendrimer/polyelectrolyte multilayer microcapsules

We report the preparation, characterization, and mechanical properties of polyelectrolyte/phosphorus dendrimer multilayer microcapsules. The shells of these microcapsules are composed either by alternating poly(styrenesulfonate) (PSS) and positively charged dendrimer G4(NH+Et2Cl-)96 or by alternating poly(allylamine hydrochloride) (PAH) and negatively charged dendrimer G4(CH-COO-Na+)96. The same multilayers were constructed on planar support to examine their layer-by-layer growth and to measure the multilayer thickness. Surface plasmon resonance spectroscopy (SPR) showed regular linear growth of the assembly upon each bilayer deposited. We probe the mechanical properties of these polyelectrolyte/dendrimer microcapsules by measuring force-deformation curves with the atomic force microscope (AFM). The experiment suggests that they are much softer than PSS/PAH microcapsules studied before. This softening is attributed to an enhanced permeability of the polyelectrolyte/dendrimer multilayer shells as compared with multilayers formed by linear polyelectrolytes. In contrast, Young's modulus of both dendrimer-based multilayers was found to be on the same order as that of PSS/PAH multilayers.     

Theoretical analysis of the influence of the adsorption process on the voltammetric curves in the case of a second order adsorption step followed by a first order charge transfer reaction: Part III. Variation of the transfer coefficient and application to semiconductor electrodes in l.p.s.v. and s.s.c.v.

The kinetic behaviour of a two-step sequential reaction including a 2nd order adsorption process is treated theoretically in the case of semiconductor electrodes. It is shown that the electronic structure of the semiconductor can be taken into account in some simplified cases by introducing a formal transfer coefficient comprised between 0 and 1 and potential independent. In both linear potential sweep voltammetry and steady state cyclic voltammetry, the usual characteristic features (E_M, _M, i_M) of the voltammetric curves are calculated as a function of the sweep rate for different values of the transfer coefficient.