Phenomenology and physical origin of shear-localization and shear-banding in complex fluids

We review and compare the phenomenological aspects and physical origin of shear-localization and shear-banding in various material types, namely emulsions, suspensions, colloids, granular materials and micellar systems. It appears that shear-banding, which must be distinguished from the simple effect of coexisting static-flowing regions in yield stress fluids, occurs in the form of a progressive evolution of the local viscosity towards two significantly different values in two adjoining regions of the fluids in which the stress takes slightly different values. This suggests that from a global point of view shear-banding in these systems has a common physical origin: two physical phenomena (for example, in colloids, destructuration due to flow and restructuration due to aging) are in competition and, depending on the flow conditions, one of them becomes dominant and makes the system evolve in a specific direction.Comment: The original publication is available at http://www.springerlink.co

Experimental and theoretical investigation of molecular structure and charge transfer within some transfer within some 8-hydroxyquinoline derivatives

A serie of novel 8-hydroxyquinoline derivatives: 5-HHQ, 5-MHQ, 5-EHQ and 5-PHQ were synthesized and characterized by means of IR, 1H and 13C NMR spectroscopic analysis. The crystal structures of 5-EHQ and 5-PHQ were solved by X-ray diffraction measurements on single crystal, the two others on powder samples. The UV–Visible spectra of molecules were performed in acetonitrile and ethanol. Density Functional Theory (DFT) and Hartree Fock (HF) methods have been used to determine its optimized geometrical parameters. Theoretical calculations such as HOMO-LUMO energies in fundamental state, in acetonitrile and ethanol, electronic dipole moments and atomic charges distribution were carried out for the title molecules using DFT (B3LYP) method at 6-311G (d, p) set. The results give us some explanation on the molecular structures, the intra charge transfer, relationships between the number of carbons connected to 5-hydroxymethyl-8-hydroxyquinoline and the bioactivity of selected derivatives

Experimental and theoretical investigation of molecular structure and charge transfer within some transfer within some 8-hydroxyquinoline derivatives

International audienceA serie of novel 8-hydroxyquinoline derivatives: 5-HHQ, 5-MHQ, 5-EHQ and 5-PHQ were synthesized and characterized by means of IR, 1H and 13C NMR spectroscopic analysis. The crystal structures of 5-EHQ and 5-PHQ were solved by X-ray diffraction measurements on single crystal, the two others on powder samples. The UV–Visible spectra of molecules were performed in acetonitrile and ethanol. Density Functional Theory (DFT) and Hartree Fock (HF) methods have been used to determine its optimized geometrical parameters. Theoretical calculations such as HOMO-LUMO energies in fundamental state, in acetonitrile and ethanol, electronic dipole moments and atomic charges distribution were carried out for the title molecules using DFT (B3LYP) method at 6-311G (d, p) set. The results give us some explanation on the molecular structures, the intra charge transfer, relationships between the number of carbons connected to 5-hydroxymethyl-8-hydroxyquinoline and the bioactivity of selected derivatives

Instabilities across the scales - Preface

No abstract

A comparison of Multiple Non-linear regression and neural network techniques for sea surface salinity estimation in the tropical Atlantic ocean based on satellite data

Using measurements of Sea Surface Salinity and Sea Surface Temperature in the Western Tropical Atlantic Ocean, from 2003 to 2007 and 2009, we compare two approaches for estimating Sea Surface Salinity : Multiple Non-linear Regression and Multi Layer Perceptron. In the first experiment, we use 18,300 in situ data points to establish the two models, and 503 points for testing their extrapolation. In the second experiment, we use 15,668 in situ measurements for establishing the models, and 3,232 data points to test their interpolation. The results show that the Multiple Non-linear Regression is an admissible solution whether it be interpolation or extrapolation. Yet, the Multi Layer Perceptron can be used only for interpolation