Etude a haute temperature des systemes formes par le sesquioxyde de neodyme avec les sesquioxydes d'yttrium et d'ytterbium

The systems formed by neodymium sesquioxide with respectively yttrium sesquioxide and ytterbium sesquioxide showed several very extended solid solutions at high temperature, near the melting point. The phases determined “in situ” at high temperature are often different of those obtained in annealed or quenched samples.     

Mutational equations of the morphological dilation tubes

The present paper provides some differential results dealing with the morphological dilation of a compact set in the nonregular case. Indeed the evolution of dilated sets with respect to time is characterized through mutational equations which are new mathematical tools extending the concept of differential equations to the metric space of all nonempty compact sets of ⁿ . Using this new tool, we prove that the mutation of the dilation is the normal cone which is a generalization of the classical notion of normal. This result clearly establishes that the dilation transforms this initial set in the direction of the normal at any point of the set. Furthermore, it does not require any regularity assumptions on the compact set.     

Characterization of mesoporous alumina prepared by surface alumination of SBA-15

Mesoporous aluminas of controlled pore sizes were synthesized by multiple grafting of Al isopropoxide in organic solvents on mesoporous silica SBA-15. These materials were characterized by N₂ physisorption, TEM, XRD, ²⁷Al NMR and their surface chemical properties were probed by DRIFT, cumene cracking and MoO₃ thermal spreading. The results show that the chemical nature of the Al-grafted materials varies continuously with the number of grafting from pure silica to pure alumina. Typically, after three graftings, this original method of synthesis allows one to prepare ordered mesoporous aluminas with specific surface areas above 300 m² g⁻¹ and a narrow pore size distribution centered on ca. 60 Å. In addition to the characterizations, different models were developed to understand the evolution of the specific surface area and to discard a possible pore blocking.     

Preparation of Ru metal nanoparticles in mesoporous materials: influence of sulfur on the hydrogenating activity

Hydrogenating catalysts were prepared by inserting Ru into the pores of mesoporous Al-MCM-41 materials by selective adsorption of [Ru(NH₃)₆]³⁺. Ru/support catalysts were obtained after reduction with H₂. The activities of these catalysts in hydrogenation reactions were compared to those of Ru/HY and Ru/SiO₂. The catalytic properties in the absence of sulfur were tested in benzene hydrogenation, and the intrinsic activities of all the catalysts (either supported on mesoporous materials or on zeolites) were identical. It was concluded from this result that the dispersion of the Ru metallic phase was similar for all these catalysts. These samples were tested in the tetralin hydrogenation in pure H₂ and in the presence of H₂S (330 ppm of H₂S in H₂). They were found to be much less active than the zeolite-supported catalysts in the presence of H₂S. It is proposed that the lower activity of the catalysts supported on mesoporous materials is either due to their milder acidity, as evidenced by NH₃-TPD, cumene cracking and pyridine desorption experiments, or to the localization of the Ru nanoparticles on alumina islands.     

Technical properties improvement of engineered flooring through hardening by acrylate surface impregnation and in-situ electron beam polymerization

European Journal of Wood and Wood Products - Engineered hardwood floors are taking more and more market shares but remain underused in non-residential buildings such as public, heavy traffic areas...     

The design of Cloudworks: Applying social networking practice to foster the exchange of learning and teaching ideas and designs

This paper describes a new social networking site, Cloudworks, which aims to provide a dynamic environment for finding, sharing and discussing learning and teaching ideas and designs. The paper begins by discussing the mismatch between the potential application of technologies in education and their actual use in practice. It considers some of the reasons for this and suggests ways in which this gap might be addressed. It goes on to outline the vision behind the development of Cloudworks, the phases of development and findings to date. It then contextualises this work theoretically drawing in particular on the notion of ‘social objects’ and a framework for sociality. The paper concludes with a discussion of the implications of this work and future research plans.     

Characterizing short-range vs. long-range spatial correlations in dislocation distributions

Hard X-ray diffraction experiments have provided evidence of a strongly heterogeneous distribution of dislocation densities along the axis of cylindrical ice single crystals oriented for basal slip in torsion creep. The dislocation arrangements showed a complex scale-invariant character, which was analyzed by means of statistical and multifractal techniques. A trend to decreasing autocorrelation of the dislocation distribution was observed as deformation proceeds. At low strain levels, long-range spatial correlations control the distribution, but short-range correlations in relation with cross-slip progressively prevail when strain increases. This trend was reproduced by a model based on field dislocation dynamics, a theory accounting for both long-range elastic interactions and short-range interactions through transport of dislocation densities.     

Relationships between soil organic matter, nutrients, bacterial community structure, and the performance of microbial fuel cells

Microbial fuel cells (MFCs) offer the potential for generating electricity, mitigating greenhouse gas emissions, and bioremediating pollutants through utilization of a plentiful renewable resource: soil organic carbon. We analyzed bacterial community structure, MFC performance, and soil characteristics in different microhabitats within MFCs constructed from agricultural or forest soils in order to determine how soil type and bacterial dynamics influence MFC performance. Our results indicated that MFCs constructed from agricultural soil had power output about 17 times that of forest soil-based MFCs and respiration rates about 10 times higher than forest soil MFCs. Agricultural soil MFCs had lower C:N ratios, polyphenol content, and acetate concentrations than forest soil MFCs. Bacterial community profile data indicate that the bacterial communities at the anode of the high power MFCs were less diverse than in low power MFCs and were dominated by Deltaproteobacteria, Geobacter, and to a lesser extent, Clostridia, while low-power MFC anode communities were dominated by Clostridia. These results suggest that the presence of organic carbon substrate (acetate) was not the major limiting factor in selecting for highly electrogenic bacterial communities, while the quality of available organic matter may have played a significant role in supporting high performing bacterial communities.     

Investigation of a Sequential Three-Dimensional Process for Back-Illuminated CMOS Image Sensors With Miniaturized Pixels

A new 3-D CMOS image sensor architecture is presented as a potential candidate for submicrometer pixels. To overcome the scaling challenge related to miniaturized pixel design rules, far beyond traditional 3-D stacking alignment capabilities, a sequential construction is applied. This paper gives a technical overview of this 3-D scheme and validates a part of its building blocks. As a consequence of a sequential process, the thermal budget is limited to ensure bottom device immunity. Subsequently, high-quality SOI film transfer above the first layer by direct bonding and etch back is demonstrated. Finally, the low-temperature processing of HfO₂/TiN fully depleted silicon-on-insulator readout transistors is detailed and evaluated from a low frequency noise point of view.