Inelastic neutron scattering due to acoustic vibrations confined in nanoparticles: theory and experiment

The inelastic scattering of neutrons by nanoparticles due to acoustic vibrational modes (energy below 10 meV) confined in nanoparticles is calculated using the Zemach-Glauber formalism. Such vibrational modes are commonly observed by light scattering techniques (Brillouin or low-frequency Raman scattering). We also report high resolution inelastic neutron scattering measurements for anatase TiO2 nanoparticles in a loose powder. Factors enabling the observation of such vibrations are discussed. These include a narrow nanoparticle size distribution which minimizes inhomogeneous broadening of the spectrum and the presence of hydrogen atoms oscillating with the nanoparticle surfaces which enhances the number of scattered neutrons.Comment: 3 figures, 1 tabl

Global population structure of the stable fly (Stomoxys calcitrans) inferred by mitochondrial and nuclear sequence data

Stomoxys calcitrans (Diptera: Muscidae: Stomoxyini), a synanthropic fly with a worldwide distribution, is recognized to have an important medical and veterinary impact. We conducted a phylogeographic analysis based on several populations from five major zoogeographic regions of the world in order to analyse population genetic structure of S. calcitrans and to trace its global dispersion. Results from mitochondrial (COI, Cyt-b and ND1-16S) and nuclear (ITS2) DNA show a substantial differentiation of Oriental populations (first lineage) from the Afrotropical, Palearctic, Nearctic, Neotropical and Oceanian populations (second lineage). The divergence time analyses suggest the separation between the two lineages approximately in mid-Pleistocene. Oriental populations are isolated and would not have participated in the colonization of other regions, unlike the Afrotropical one which seems to be the source of S. calcitrans dispersion towards other regions. Demographic analyses indicate that Oriental, Afrotropical and Palearctic regions have undergone a population expansion during late Pleistocene-early Holocene. The expansion time of this cosmopolitan species could have been influenced by continental human expansions and by animal domestication. © 2010 Elsevier B.V

Art and Science in Word and Image: Exploration and Discovery

International audienceArt and Science in Word and Image investigates the theme of ‘riddles of form’, exploring how discovery and innovation have functioned inter-dependently between art, literature and the sciences. Using the impact of evolutionary biologist D’Arcy Thompson’s On Growth and Form on Modernist practices as springboard into the theme, contributors consider engagements with mysteries of natural form in painting, photography, fiction, etc., as well as theories about cosmic forces, and other fields of knowledge and enquiry. Hence the collection also deals with topics including cultural inscriptions of gardens and landscapes, deconstructions of received history through word and image artworks and texts, experiments in poetic materiality, graphic re-mediations of classic fiction, and textual transactions with animation and photography

Hydrolyse basique du polyurethane irradie identification des produits de degradation et interaction avec l'europium(III)

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Lixiviation des polymères irradiés caractérisation de la solution et complexation des actinides

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Correlation Between the Reactivity Towards Oxygen and the Coercitivity in Submicron Vanadium Ferrite Spinels

Nanometric powders of Fe2VO4 and Fe1.84V0.92Co0.23O4 have been synthetised by "chimie douce" process. The cations in the spinel structure can oxidize at low temperatures without any phase transformation leading to cationdeficient spinel with formula Fe2VO4+δ and Fe1.84V0.92Co0.23O4+δ, where δ is the deviation from stoichiometry, due to a change of the anion-cation ratio, consecutive to formation of vacancies. The oxidation, investigated by thermogravimetry, involves several stages, each stage corresponding to the oxidation of one oxidizable cation, Fe2+, V2+, V3+ on B (octahedral) or A (tetrahedral) sites. Coercivity has also been studied, revealing that the coercive field increases with the rate of oxidation

Thermally activated delayed fluorescence evidence in non-bonding transition electron donor-acceptor molecules

International audienceThe exhibition of thermally activated delayed fluorescence on triazine derivative by the introduction of a nonbonding part is demonstrated. Two molecules containing triazine core as acceptor and carbazole part as donor has been synthesized and characterized. One of these molecules bears an additional nonbonding part by the means of a phenoxy group. The results indicated that the molecule bearing the nonbonding molecular part (phenoxy) exhibit thermally activated delayed fluorescence while not on molecule free of non-bonding group. The results are supported by, photoluminescence, spectral analysis time-resolved fluorescence and time-dependent density functional estimation

A FTIR and SEM study of PS radiation grafted fluoropolymers: influence of the nature of the ionizing radiation on the film structure

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