Fractal Description of Electron Scattering in Solids: Several New Results and a Simple Modelization of the Fractal Dimension

The fractal behaviour of electron scattering in solids is studied with electron trajectories simulated by Monte Carlo simulations. More precisely, the Hausdorff-Besicovitch dimension is determined for several electrons trajectories simulated in solids of different compositions. Then, a simple model to compute the fractal dimension of electron trajectories in solids is presented, a model which raises a question concerning the maximum value of the backscattering coefficient. Results of Monte Carlo simulations of electron trajectories in several elements with total randomness for the polar and azimuthal angles of scattering are presented as a tentative answer to this question. Finally, the multi fractal behaviour of the energy distribution of backscattered electrons is presented

Resistless electron beam lithography process for the fabrication of sub-50 nm silicide structures

We report on a study of the fabrication of submicron silicide structures with a resistless lithography technique. Several different metals can be used as a basis for producing silicide using this method; in this work, results will be discussed for both platinum and nickel silicide. The feasibility of producing nanostructures using polycrystalline silicon as a base growth layer for metal–oxide– semiconductor, and other device applications have also been demonstrated. Threshold doses for this method for submicron lines (<50 nm) and square areas were obtained in order to establish a framework for the fabrication of more complex devices. Preliminary electrical measurements were carried out which indicate that the resistivity of the silicide is 45 [mu omega] cm, and that the barrier height of the silicide/(high resistivity silicon) interface is 0.56 eV

Brachystemma calycinum

Objective. The aim of this randomized placebo-controlled trial was to evaluate the beneficial effect of a whole plant extract of Brachystemma calycinum D. Don (BCD) in naturally occurring osteoarthritis (OA) in dogs. Methods. Dogs had stifle/hip OA and poor limb loading based on the peak of the vertically oriented ground reaction force (PVF) measured using a force platform. At baseline, PVF and case-specific outcome measure of disability (CSOM) were recorded. Dogs (16 per group) were then assigned to receive BCD (200 mg/kg/day) or a placebo. The PVF was measured at week (W) 3 and W6. Locomotor activity was recorded throughout the study duration using collar-mounted accelerometer, and CSOM was assessed biweekly by the owner. Results. BCD-treated dogs had higher PVF at W3 and W6 when compared to Baseline (P<0.001) and at W6 when compared to placebo-treated dogs (P=0.040). Higher daily duration (P=0.024) and intensity (P=0.012) of locomotor activity were observed in BCD-treated dogs compared to baseline. No significant change was observed in either group for CSOM. Conclusions. Treatment with BCD improved the limb impairment and enhanced the locomotor activity in dogs afflicted by naturally-occurring OA. Those preclinical findings provide interesting and new information about the potential of BCD as an OA therapeutic

Contribution à l'étude de la polymérisation : formation, propriétés et constitution des polyindènes, en particulier du "triindène"

Québec Université Laval, Bibliothèque 201

Traitement homéopathique des otites de l'enfant

CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Etude chimiotaxonomique des espèces du genre Psiadia et Melicope endémiques de l’île de La Réunion: isolement et identification de trois nouveaux terpènes.

International audienceLe Laboratoire de Chimie des Substances Naturelles et des Sciences des Aliments (LCSNSA) et l’Unité Mixte de Recherche C53 « Peuplement Végétaux et Bioagresseurs en Milieu Tropical (PVBMT) sont impliqués depuis 2005 dans un vaste programme relatif à la gestion et à la conservation de la biodiversité de l’île de la Réunion, haut lieu (hotspot) de la biodiversité mondiale. Dans ce cadre, ils ont mis en place un important projet de reconnaissance et de classification des plantes endémiques de l’île. Ce projet s’inscrit dans le domaine de l’écologie évolutive, dont la finalité est de mettre en évidence l’influence des mécanismes de l’évolution (sélection naturelle, mutation, hasard, migration…) sur le devenir des populations végétales et animales, leur type d’organisation et leur mode d’adaptation à l’environnement. Afin d’aboutir à une classification juste et précise des espèces végétales endémiques de l’île, le choix des chercheurs s’est fixé sur la mise en œuvre d’une étude scientifique combinant à la fois des données chimiques, botaniques et de phylogénie biomoléculaire.Ce vaste projet a débuté avec l’étude des espèces des genres Psiadia (Astéracées) et Melicope (Rutacées). L’analyse de leurs huiles essentielles a conduit en particulier à l’isolement et l’identification par spectrométrie de masse et résonance magnétique nucléaire mono- et bidimensionnelle de trois nouveaux terpènes : un monoterpène acétylé dérivé du alpha-pinène, l’acétate de 6-(7,7-diméthyl-2-méthylène-bicyclo[3.1.1])heptanoyle (1) ; un alcool sesquiterpénique au squelette tricyclique inhabituel, le 6,6,8,9-tétraméthyl-tricyclo[3.3.3.0]undéc-7-én-2-ol (2) ; et un sesquiterpène dioxygéné, le 2-hydroxy-6,10-diméthyl-6-vinylundéca-2,9-dièn-4-one (mélicopénol) (3). Les composés (1) et (2) ont été détectés en forte proportion dans les huiles essentielles de quatre des espèces du genre Psiadia (P. anchusifolia, P. argentea, P. boivinii et P. salaziana). Le composé (3) quant à lui, constitue le composé majoritaire de l’huile essentielle de Melicope obscura.En raison de leur forte proportion et de l’originalité de leur structure, il a été envisagé pour ces trois nouveaux composés, la possibilité d’un rôle de marqueurs chimiotaxonomiques

Consolidation of Al2O3/Al Nanocomposite Powder by Cold Spray

While the improvement in mechanical properties of nanocomposites makes them attractive materials for structural applications, their processing still present significant challenges. In this paper, cold spray was used to consolidate Al\u2082O\u2083/Al nanocomposite powders obtained from mechanical milling. The microstructure and nanohardness of the feedstock powders as well as of the resulting coatings were analysed. The results show that the large increase in hardness of the Al powder after mechanical milling is preserved after cold spraying. Good quality coating with low porosity is obtained from milled Al. However, the addition of Al\u2082O\u2083 to the Al powder during milling decreases the powder nanohardness. This lower hardness is attributed to non-optimised milling parameters for proper Al\u2082O\u2083 embedding and dispersion in Al and results in a lower coating hardness compared with the milled Al coating. The coating produced from the milled Al\u2082O\u2083/Al mixture also shows lower particle cohesion and higher amount of porosity. The overall results are promising and it is believed that an optimization of Al milling with Al\u2082O\u2083 will allow production of sound coatings with improved hardness.Peer reviewed: YesNRC publication: Ye

Fabrication and properties of mechanically milled alumina/aluminum nanocomposites

The reinforcement agglomeration in nanocomposites is a key issue that needs to be solved in order to fully benefit of the gain in strength and ductility associated with the decrease in reinforcement size from microscale to nanoscale. In this study, mechanical milling has been used successfully to disperse nanometric alumina (n-Al2O3) in an aluminum matrix. Al2O3/Al nanocomposite powders have been produced for various alumina sizes and concentrations. The 10 vol% n-Al2O3/Al powders display hardness values near five times higher than pure unmilled Al. A decrease in the Al2O3 particle size from 400 to 4 nm has increased the nanocomposite powder hardness by 11%. The microhardness and compression properties of an Al2O3/Al nanocomposite compact consolidated by hot pressing were measured. Comparison with modeled values and literature results indicates that the higher experimental yield strength obtained with the addition of n-Al2O3 versus micron size Al2O3 is due to in situ matrix strengthening.Peer reviewed: YesNRC publication: N