A method to replace lightning strike tests by ball impacts in the design process of lightweight composite aircraft panels

Composite material aircrafts are protected against lightning on the basis of complex and expansive lightning strike experimental plans aiming at designing optimal protections. The paper aims at reducing the number of lightning strike tests on protected and painted composite panels. An analytical calculation is presented that gives the characteristics of an equivalent mechanical impact configuration based on an assessment of the typical time scale of energy deposit and kinematic behaviour during a lightning strike test. The paper presents our analytical hypotheses and calculations, as well as experimental lighting strikes and mechanical impact settings and results. The method is shown to give an acceptable approximation of both the kinematics and the delamination surface

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Mise au point de nouveaux catalyseurs de dimerisation du propylene a base de complexes supportes du nickel : controle de la stabilite et de la selectivite par effet de ligands : influence electronique sterique et mecanistique

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Préface

Depuis plus d’un siècle l’Inspection générale des Finances cultive son histoire et sa mémoire collective, avec une première commémoration officielle, en 1908, du centenaire de l’arrêté de Mollien, une deuxième, en 1931, du centenaire des ordonnances du baron Louis, une troisième, plus modeste, en 1967, du cent cinquantenaire de l’arrêté de 1816. En 1976, l’Association des membres de l’Inspection lance le projet de rédiger l’histoire de l’Inspection. C’est donc peu de dire que ce Dictionnaire ..

QTAIM and ELF topological analyses of zinc-amido complexes

International audienceThe structures of three dinuclear zinc-amido complexes, involved in the very first step of the preparation of zinc oxide nanoparticles via an organometallic route, have been investigated by density functional theory computational studies. The various zinc–nitrogen and zinc–cyclohexyl bonds are finely characterized using quantum theory of atoms in molecules and electron localization function (ELF) topological analyses. The results are compared to the topological analyses of parent zinc-amido or zinc-alkyl complexes, for which an experimental structure has been already reported. The original two-component dative zinc-amido bond is unravelled by ELF topological analysis. Fukui indices condensed on the ELF basins allow for the comparison of the chemical reactivity of the three dinuclear zinc-amido complexes. The larger sensitivity to electrophilic attack of the terminal zinc-amido bonds with respect to the bridging intracyclic zinc-amido bonds or with respect to the terminal zinc–cyclohexyl bonds is evidenced

Topological Analysis of Hydroxyquinoline Derivatives Interacting with Aluminum Cations or with an Al(111) Surface

International audienceThe reactivity of hydroxyquinoline derivatives (native molecules (Hq) and modified species (HqX, X = Br, SO3H, or SO3–)) is investigated either (i) with aluminum cations for the formation of chelates or (ii) with aluminum surfaces for their adsorption properties, in the framework of the dispersion-corrected Density Functional Theory (DFT-D). It is shown that the substituent X has no influence on the complexation to the aluminum cation of the deprotonated active form, i.e., the one exhibiting a phenolate moiety and referred to as q– for the native Hq and qXn– (n = 1 or 2) for its derivatives. The formation energies of the Alq3 and Al(qX)3 complexes, taking values of −60.87 ± 3.10 eV in vacuum and −24.30 ± 0.29 eV in water, are indicative of a strong chelating affinity of the q– and qXn– (n = 1 or 2) anions for the aluminum cations. ELF and QTAIM topological analyses on these complexes evidence that the bonding of the deprotonated species with the Al3+ ion is ionic with a very weak covalence degree. The para or ortho substituent X of the phenolate moiety of the qXn– (n = 1 or 2) derivatives modifies the electronic structure only locally and thus does not influence their O- or N-coordinating properties. The adsorption properties of the latter on an Al(111) surface have also been studied within periodic DFT-D calculations. The adsorbed species are strongly interacting with the Al(111) surface, as shown by the value of the adsorption energy of −3.69 ± 0.21 eV for the most stable geometries. Various adsorption modes of the q– and qXn– (n = 1 or 2) derivatives are characterized on the Al surface, depending on stabilizing or destabilizing interactions with the substituents X. On the basis of QTAIM descriptors, the bonding of the hydroxyquinoline species on the aluminum surface is characterized as ionic with a weak covalent character

Coordination complexes of 4-methylimidazole with Zn-II and Cu-II in gas phase and in water: a DFT study

International audienceA quantum chemistry study of mononuclear metal coordination with four 4-methylimidazole ligands (4-MeIm) was investigated. The four complexes [Cu(4-MeIm)(4)](2+), [Cu(4-MeIm)(4), H2O](2+), [Zn(4-MeIm)(4)](2+) and [Zn(4-MeIm)(4), H2O](2+) were studied with particular attention to the N pi or N tau possible coordinations of the 4-MeIm ring with the metals, using different DFT methods. The results suggest that the N tau coordination of 4-MeIm ring to Zn-II or Cu-II is more favorable whatever the level of calculation. In contrast, the addition of one water molecule in the first coordination sphere of the metal ions provides five-coordinated complexes showing no N pi or N tau preferences. There is good agreement between the DFT-calculated structure and those available experimentally. When metal ions are four-fold coordinated, they adopt a tetrahedral geometry. When Cu-II and Zn-II are five-fold coordinated, highly symmetric structures or intermediate structures are calculated. Similar energies are calculated for different structures, suggesting flat potential energy surfaces. The addition of implicit solvent modifies the calculated first coordination sphere, especially for [Cu(4-MeIm)(4), H2O](2+) structures. The QTAIM and ELF topological analyses of the interaction between Cu-II and the neutral ligands, clearly indicate a dative bonding with a strong ionic character