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Cachan, France

He Z.,Institute Navier | Dormieux L.,Institute Navier | Djimedo K.,Institute dAlembert
13th International Conference on Fracture 2013, ICF 2013 | Year: 2013

In the present study, we investigate the strength properties of ductile porous materials reinforced by rigid particles. The microporous medium is constituted of a Drucker-Prager solid phase containing spherical voids; its behaviour is described by means of an elliptic criterion (issued from a modified secant moduli approach) whose corresponding support function is determined. The later is then implemented in a limit analysis approach in which a careful attention is paid for the contribution of the inclusion matrix-interface. This delivers parametric equations of the effective strength properties of the porous material reinforced by rigid particles. The predictions are compared to available results obtained by means of variationnal homogenization methods successively applied for micro-to-meso and then for meso-to-macro scales transitions. Moreover, we discuss in detail the predictions of the material strength under isotropic mechanical loadings. To this end, additional static solutions are derived and compared to the kinematics limit analysis ones. Finally, we derive an approximate closed-form expression of the macroscopic strength which proves to be very accurate. Source


Abid J.-P.,Institute dAlembert | Frigoli M.,University of Versailles | Pansu R.,Ecole Normale Superieure de Cachan | Szeftel J.,Institute dAlembert | And 3 more authors.
Langmuir | Year: 2011

Azobenzene-coated polymer nanoparticles in the 16-nm-diameter range act as phototriggered nanomotors combining photo to kinetic energy conversion with optical control through light intensity gradients. The grafted dyes act as molecular propellers: their photoisomerization supplies sufficient mechanical work to propel the particles in an aqueous medium toward the intensity minima with velocities of up to 15 μm/s. It is shown that nanoparticles can be driven over tens of micrometers by translating the intensity gradients in the plane. The analysis of the particles motion demonstrates the decisive role of photoisomerization in the transport with a measured driving force that is 3 to 4 orders of magnitude higher than optical forces. © 2011 American Chemical Society. Source


Bryndal I.,Wroclaw University of Economics | Ledoux-Rak I.,Institute dAlembert | Lis T.,Wroclaw University | Ratajczak H.,Wroclaw University
Journal of Molecular Structure | Year: 2014

Two proton transfer hydrogen-bonded complexes of 5-sulfosalicylic acid (3-carboxy-4-hydroxybenzenesulfonic acid, 5-SSA) with the aromatic amides: nicotinamide (NA) and isonicotinamide (INA), are characterized by X-ray diffraction and spectroscopic studies. In the crystal structures of nicotinamidium 3-carboxy-4-hydroxybenzenesulfonate, 1, and isonicotinamidium 3-carboxy-4-hydroxybenzenesulfonate monohydrate, 2, the ions are linked into three dimensional frameworks by a combination of O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds and cation-anion π-π stacking interactions. The hydrogen-bonding behavior of the pyridine N atom is different in the two crystals, bonding to a sulfonate O atom of anion in 2 but to a carbonyl O atom of cation in 1. The complex 1 shows relatively efficient second harmonic frequency generation. © 2014 Elsevier B.V. All rights reserved. Source


Ratajczak H.M.,Wroclaw University | Bryndal I.,Wroclaw University of Economics | Ledoux-Rak I.,Institute dAlembert | Barnes A.J.,University of Salford
Journal of Molecular Structure | Year: 2013

Two molecular complexes of amides (nicotinamide and isonicotinamide) with 3-nitrophenol are characterized by X-ray diffraction and spectroscopic studies. Crystal structure analyses at 100 K revealed different features to distinguish the co-crystals. The asymmetric unit of the crystal structure of nicotinamide-3-nitrophenol (1:1), 1, consists of two symmetry-independent nicotinamide molecules and two symmetry-independent 3-nitrophenol molecules. The crystal structure of 1 displays an extended hydrogen bond network generated by OAH O, NAH O and NAH N interactions. The structure of isonicotinamide-3- nitrophenol (1:1), 2, contains OAH N hydrogen bonds engaging the pyridine N atom. In 2, the amide forms a R22 (8) homodimer which is absent in 1. The complex 1 shows relatively efficient second harmonic frequency generation. © 2013 Elsevier B.V. All rights reserved. Source


Fortuna C.G.,University of Catania | Bonaccorso C.,University of Catania | Qamar F.,Institute dAlembert | Anu A.,Institute dAlembert | And 2 more authors.
Organic and Biomolecular Chemistry | Year: 2011

The synthesis and characterisation of new trans 2-(thiophen-2-yl)vinyl pyridinium, imidazolium and quinoilinium iodides is reported together with their solvatochromic shifts and EFISH characterization. 2-{(E)-2-[5′- (dibutylamino)-2,2′-bithien-5-yl]vinyl}-1-methyl pyridinium and quinolinium iodides display high μ.βvec values up to 1200 × 10-48 esu. The promising non-linear optical (NLO) properties of this new family of chromophores, which can be further improved by the design of highly efficient systems exploiting the donor and acceptor properties of both heteroaromatic rings and substituents, make them suitable candidates for second harmonic generation imaging with interesting biological applications. © The Royal Society of Chemistry 2011. Source

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