De la microstructure du polymère à ses propriétés rhéologiquesFrom the microstructure of polymers towards their rheological properties

We extend the previous work by Benallal et al. on the relationship between structure and rheological properties of linear polymer melts. The aim of this paper is to quantify the effect of the chemical structure on the viscoelastic properties. We show that these properties are governed by the monomer dimensions and the interaction energy. To cite this article: A. Allal et al., C. R. Physique 3 (2002) 1451–1458.     

Adsorption of O-Phospho-L-Serine and L-Serine onto Poorly Crystalline Apatite

The adsorption of phosphoserine and serine was studied to determine the effect of amino acid functional groups on the surface reactivity of synthetic poorly crystalline apatite similar to bone mineral. The experimental results for phosphoserine and serine uptake agree respectively with the Langmuir and Freundlich models. Phosphoserine exhibits stronger adsorption capacity and a higher affinity constant for the surface crystals compared to serine molecules. The enhanced adsorption capacity noted for phosphoserine might be related to the presence of phosphate groups in the molecule, which are specific attachment sites. This observation suggests that the strength of phosphate bonds to the solid surface, especially to calcium ions, is higher than that of carboxyl and hydroxyl ones. Spectroscopic observations provide evidence of an adsorption mechanism involving the anionic species of the amino acids and the surface of the crystals. Thus, a change in the position of the band of carboxyl groups occurred for the adsorbed molecules compared to the native amino acids. This revealed that the molecular residues do interact with apatite surface calcium. The shift noted in the frequencies of the bands associated with carboxylate vibrations is more pronounced for phosphoserine, confirming the stronger interaction noted for this molecule. Based on these results, one can conclude that the sorbent and sorbate charged species play an important role in the mechanism of uptake of the amino acids onto crystal surfaces. This may contribute to a better understanding of the mechanism by which phosphoproteins could influence mineralization processes and caries. Copyright 2001 Academic Press.     

Modelling and analysis of Canadian Forces strategic lift and pre-positioning options

This paper presents analysis of some of the strategic lift and pre-positioning issues within the context of rapid deployability to failed and failing states conducted for the Canadian Forces (CF). A simulation framework was developed to study the effectiveness of a variety of pre-positioning options. An aircraft loading optimization model based on a genetic annealing algorithm with a novel convex hull-based measure of effectiveness was also developed to analyse different strategic lift options. The model was used both to provide insights into the optimal mix of airlift capabilities and to conduct sensitivity analysis. Historical CF deployments provided a baseline performance measure against which several movement solutions were compared and contrasted. Analysis indicates that pre-positioning of equipment and supplies at various strategic locations and use of efficient mix of transport aircraft could be potential strategies for improvement of the CF's strategic lift capability.     

A class of generalized complex Hermite polynomials

A class of generalized complex polynomials of Hermite type, suggested by a special magnetic Schrödinger operator, is introduced and some related basic properties are discussed.     

Modeling and analysis of a Canadian Forces Geomatics division workflow

This paper addresses workflow issues of a Geomatics division in the Canadian Forces. This division is dedicated to the production of Geomatics Information under the US National Geospatial-Intelligence Agency’s Foundation Based Operations concept. This paper outlines a methodology for modeling and analyzing the workflow of the Canadian Forces Geomatics division. A discrete event simulation model is developed and applied to measure the performance of the workflow system for developing Geomatics products. A hybrid queueing network/optimization model is also developed to support the simulation model. The objective of the queueing network/optimization formulation is to provide the optimal configuration of the Geomatics division. The paper successfully addresses a complex workflow problem in the context of real world system and provides insights into the performance of the Canadian Forces Geomatics processing.