Mechanical,thermal, and UV‐shielding behavior of silane surface modified ZnO‐reinforced phthalonitrile nanocomposites

In the present work, zinc oxide nanoparticles were treated with aminopropyl trimethoxy silane‐coupling agent and used as a new kind of reinforcement for a typical high performance bisphenol‐A‐based phthalonitrile resin. The resulted nanocomposites were characterized for their mechanical, thermal, and optical properties. Results from the tensile test indicated that the tensile strength and modulus as well as the toughness state of the matrix were all enhanced with the increasing of the nanoparticles amount. Thermogravimetric analysis showed that the starting decomposition temperatures and the residual weight at 800°C were highly improved upon adding the nanofillers. At 6 wt% nanoloading, the glass transition temperature and the storage modulus were considerably enhanced reaching about 359°C and 3.7 GPa, respectively. The optical tests revealed that the neat resin possesses excellent UV‐shielding properties, which were further enhanced by adding the nanofillers. Furthermore, the fractured surfaces of the nanocomposites analyzed by scanning electron microscope exhibited homogeneous and rougher surfaces compared with that of the pristine resin. Finally, the good dispersion of the reinforcing phase into the matrix was confirmed by a high resolution transmission electron microscope. Copyright © 2015 John Wiley & Sons, Ltd.     

Ab initio calculation of the electronic structure of the strontium hydride ion (SrH+)

The potentials, spectroscopic properties and electric dipole moments of SrH⁺ are computed for 63 molecular states dissociating up to Sr²⁺ + H^? using an ab initio approach. The ab initio formalism is based on large basis sets, nonempirical atomic pseudopotential for strontium core, correlation treatment for core valence through the effective core polarization potentials and for valence through full valence configuration interaction. Our theoretical molecular constants match published values very well and a large amount of new results is produced. Unusual potential shapes are found in ¹Σ⁺ states often caused by avoided crossing series between them and imprinted by the ionic state Sr²⁺H^?. The high potential energy curves suggest, it is possible to form H^? or at least to neutralize H⁺ in collisions with strontium. © 2014 Wiley Periodicals, Inc.     

Influence of iterated Gram–Schmidt orthonormalization in the asymptotic numerical methodInfluence de l'orthonormalisation itérative de Gram–Schmidt dans la méthode asymptotique numérique

In this paper we discuss the influence of Gram–Schmidt orthonormalization for the computation of the rational representation in the asymptotic numerical method. Classical, modified and iterated Gram–Schmidt algorithms are compared using the ordinary and the mass scalar products. The accuracy of the proposed algorithms are tested on elastic shells. To cite this article: R. Jamai, N. Damil, C. R. Mecanique 331 (2003).     

Cathodic reduction of diazonium salts in aprotic medium

Cathodic reduction of diazonium salts in acetonitrile led to the formation of azobenzenes, in good to moderate yields, and diarylamines as minoritary products. The reactions were carried out at the second reduction potential of the diazonium salts, involving aryl anions in the formation of the products.     

A generalized collapsing sandpile model

In this paper, we introduce a new model for the collapsing sandpile and we prove existence and uniqueness of a solution for the corresponding initial value problem. Moreover, we prove the convergence of the time-stepping approximation of the solution. We use subgradient flows for variational problems with time dependent gradient constraints. These gradient constraints are interpreted as the critical angles of the sandpile. In particular, our model produces an evolution in time of avalanches in a drying of a sandpile, rather than instantaneous collapse.     

Aurasperone F--a new member of the naphtho-gamma-pyrone class isolated from a cultured microfungus, Aspergillus niger C-433

A novel dimeric naphtho-gamma-pyrone, named aurasperone F (1), was isolated from the fermentation broth of the culture extracts of Aspergillus niger C-433, isolated from grapes, along with the known compounds fonsecin (2), aurasperone B (3), aurasperone C (4), aurasperone D (5) and aurasperone E (6). The chemical structure of the new natural product was established by extensive one- and two-dimensional NMR spectroscopic studies (1H, 13C, COSY, HMQC, 1D NOE spectra), as well as on the UV, MS and IR spectral analysis.