Amphiphilic Polymethacrylate‐ and Polystyrene‐Based Chemical Delivery Systems for Damascones

Amphiphilic polystyrene‐ and polymethacrylate‐based β‐acyloxy ketones were investigated as potential delivery systems for the controlled release of damascones by retro‐1,4‐addition in applications of functional perfumery. A series of random copolymers being composed of the hydrophobic damascone‐release unit and a second hydrophilic monomer were obtained by radical polymerization in organic solution by using 2,2′‐azobis[2‐methylpropanenitrile] (AIBN) as the radical source (Schemes 2 and 3). A first evaluation of the polymer conjugates in acidic or alkaline buffered aqueous solution, and in the presence of a surfactant, showed that polymethacrylates and polystyrenes having a carboxylic acid function as hydrophilic group are particularly interesting for the targeted applications (Table 2). The release of δ‐damascone ( 1 ) from polymers with poly(methacrylic acid) and poly(vinylbenzoic acid) comonomers in different stoichiometric ratios was thus followed over several days at pH 4, 7, and 9 by comparison of fluorescence probing, solvent extraction, and particle‐size measurements (Tables 3 and 4). In acidic media, the polymers were found to be stable, and almost no δ‐damascone ( 1 ) was released. In neutral or alkaline solution, where the carboxylic acid functions are deprotonated, the concentration of 1 increased over time. In the case of the polymethacrylates, the fluorescence probing experiments showed an increasing hydrophilicity of the polymer backbone with increasing fragrance release, whereas in the case of the polystyrene support, the hydrophilicity of the environment remained constant. These results suggest that the nature of the polymer backbone may have a stronger influence on the fragrance release than the ratio of hydrophilic and hydrophobic monomers in the polymer chain.     

More results on the Ashkin-Teller model

We analyze the low-temperature phase diagram of the Ashkin-Teller model for real values of the quadratic and quartic coupling constants.     

Set-valued mapping monotonicity as characterization of D.C functions

In this paper, using a result of Kung-Ching Chang [6], we give a characterization of locally Lipschitz functions which are differences of convex functions defined on a Banach space (not necessarily Asplund) in terms on maximal cyclically monotone set-valued mappings. A subdifferential integration of locally D.C functions. is also given.     

Optimality conditions for pessimistic bilevel problems using convexificator

Positivity - The purpose of this paper is to study the pessimistic version of bilevel programming problems in finite-dimensional spaces. Problems of this type are intrinsically nonsmooth (even for...     

Theq-state Potts model in the standard Pirogov-Sinai theory: Surface tensions and Wilson loops

Theq-state Potts model (both scalar and gauge versions) is rewritten, with the help of the duality transformation, into a form of the Pirogov-Sinai theory with noninteracting contours that can be controlled by cluster expansions onceq is large enough. This is then used in a new proof of the existence of a unique transition (inverse) temperature _t , where the mean internal energy is discontinuous. Moreover, we prove for the scalar model (again forq large enough) that there are discontinuities at _t of the magnetization and of the mass gap, with the magnetization vanishing below _t and the mass gap vanishing above _t . We also show that the surface tensions between ordered stable phases are strictly positive up to _t , and the surface tension between an ordered phase and the disordered one is strictly positive at _t . For the three-dimensional gauge model, the Wilson parameter exhibits a direct transition from an area law decay (quark confinement) to a perimeter law decay (deconfinement).On leave from ENS Rabat, Morocco.     

New thermally irreversible and fluorescent photochromic diarylethenes

A photokinetic investigation is here carried out on four newly synthesized diarylethenes with the aim to test their performance as photoreversible chromogenic and light emitting materials. The pentatomic ring, which fixes these diarylethenes in the cis conformation, contains a Si atom or a PO group. The 1,2 positions at the ethenic bond are symmetrically substituted with thienyl or benzothienyl groups. The results are compared with those for the structurally related and widely studied 1,2-bis(2-methyl-benzo[b]thiophen-3-yl)perfluorocyclopentene (BTF6), investigated here under the same experimental conditions. Spectra of the colorless and colored forms and photoreaction quantum yields were determined; temperature, excitation wavelength and viscosity effects were explored. Compounds containing benzothienyl substituents were found to be good bistable photochromes, with high photochemical yields of both the cyclization and cycloreversion reactions, and to display appreciable fluorescence emission from the colored forms, which is a rare and desirable property for photochromes. In contrast, the molecules not bearing the benzene condensed rings were found unsuitable as photochromes because of side degradation processes occurring in competition with cyclization.     

Necessary optimality conditions for set-valued optimization problems via the extremal principle

The paper concerns first-order necessary optimality conditions for set-valued optimization problems. Based on the extremal principle developed by Mordukhovich [21], we derive fuzzy/approximate necessary optimality conditions. An example that illustrates the usefulness of our results is given.     

Nouvelle approche du théorème de ABB

This Note presents a density result of the ABB theorem type for a strong topology of a Banach space equipped with the preorder associated to a convex well-based cone. The hypothesis of compactness is relaxed. Here the technique used is based on properties of the Bishop–Phelps cone, and does not require any property of the Hening dilating cone. To cite this article: A. Bourass, L. Lafhim, C. R. Acad. Sci. Paris, Ser. I 347 (2009).