Contribution to the statistical analysis of incomplete longitudinal ordinal data

Doctoral thesis (2013)

Photon correlation spectroscopy for molecular self-assembly investigations

Conference (2013, April 11)

The molecular self-assembly performance is among the most important functionalities of amphiphilic compounds in colloidal system areas. This aptitude is required in numerous applications, depending on ... [more ▼]

The molecular self-assembly performance is among the most important functionalities of amphiphilic compounds in colloidal system areas. This aptitude is required in numerous applications, depending on solubilization, hydrotropy, rheology, separation, loading and delivery, encountered in biological and industrial processes. The main physicochemical parameter predicting the capacity of amphiphiles to self-assembly in bulk liquid, aqueous (normal micelles) or non-aqueous phase (reverse micelles), is the pair critical micelle concentration (CMC) and temperature (CMT). A variety of methods based on surface tension, spectral changes, and electrical conductivity are commonly used for determining the value of CMC. The choice usually depends on the ionic or non-ionic nature of the amphiphilic compounds. In this communication, a standard Photon Correlation Spectroscopy (PCS), also known Light Scattering-based technique for CMC determination will be theoretically and practically described in details. Its particular interest for measuring the performance of non-ionic and very high hydrophobic tail, mono or disubstituted carbohydrate-based compounds, from C16 alkyl chain, will be demonstrated. Such a method is advantageous regarding the time, amount, and resolution required, but also for additional information on micelle size, aggregate number, and stability it may provide, compared to surface tension and electrical conductivity-based measurements. [less ▲]

- Fundamental property and functional aptitude relationships in emulsion and foam applications of amphiphilic compounds

Conference (2013, April 11)

Amphiphilic compounds are issued of a combination of two opposite entities, covalently assemblied within a single structure. By the diversity of the origin, class, number of monomer and substitute, size ... [more ▼]

Amphiphilic compounds are issued of a combination of two opposite entities, covalently assemblied within a single structure. By the diversity of the origin, class, number of monomer and substitute, size, linker or spacer, stereochemistry of the molecular entities, their chemical structure may be very different but also close each other. However, they may fulfill the same role in reducing surface and interfacial free energy in dynamic or static ways, ensuring especially the formation of dispersed systems like emulsion and foam. If the relationships between the structural variable and fundamental properties are strictly chemical residue dependent, those between fundamental and functional aptitudes are not necessarily. In this case, general and universal rules may exist, whatever the kind of amphiphilic compounds. In order to achieve a rational design for any expected functionality, we attempt to find out some predictive and conception rules from a lot of screening data of fundamental and functional properties. In this communication, some correlations between fundamental data related to surface and interfacial properties, measured by molecule adsorption or spreading under dynamic or static mode, in compression or dilation of adsorbed or spread film, and emulsifying and foaming performances of various bio-based surfactants will be presented. [less ▲]

Changes of soil structure and earthworm community under different agricultural management

Conference (2013, April 11)

The living soil is represented by soil biota that interacts with aboveground biota and with the abiotic constructs of soil, represented as soil structure, organic matter, and nutrients. Maintenance of ... [more ▼]

The living soil is represented by soil biota that interacts with aboveground biota and with the abiotic constructs of soil, represented as soil structure, organic matter, and nutrients. Maintenance of soil organic matter through integrated soil fertility management is necessary for soil quality and agricultural productivity. Earthworms are key actors in soil structure formation through the formation of casts and the incorporation of soil organic matter in the soil. Little is known about the interactive effects of various tillage and crop residue management practices on earthworm populations and physical properties of soil. To investigate the impacts of two tillage management systems and two cropping systems on earthworms populations and soil stucture dynamics, we carried out a three years study of the earthworm communities in experimental site having for experimental treatments : two tillage management systems and two cropping systems. In consequence, the aims of this experimentation were to determine the effects of the tillage systems on the abundance, biomass and diversity of earthworms and examine temporal variation of soil structure and dynamics of nutrient elements. The first results reveal that tillage management had a significant affect on earthworm abundance and biomass. However, crop residue management did not affect abundance, biomass and diversity of earthworms. The analyze of nutrient element dynamics showed that some nutrient elements (phosphore,…) decrease with tillage practice. This study has shown that soil structure was variable within the fields and between them, although the successive cultivation operations and the equipement used for wheat cropping were identical in the study site. [less ▲]

Relationship between the Synthesis of Prussian Blue Pigments, Their Color, Physical Properties, and Their Behavior in Paint Layers

in Journal of Physical Chemistry C (2013), 117(19), 96939712

Prussian blue pigments, highly insoluble mixed-valence iron(III) hexacyanoferrate(II) complexes of typical stoichiometry Fe4III[FeII(CN)6]3·xH2O or KFeIII[FeII(CN)6]·xH2O, have been used as pigments in ... [more ▼]

Prussian blue pigments, highly insoluble mixed-valence iron(III) hexacyanoferrate(II) complexes of typical stoichiometry Fe4III[FeII(CN)6]3·xH2O or KFeIII[FeII(CN)6]·xH2O, have been used as pigments in oil paintings and watercolors for 300 years. For poorly understood reasons, these pigments often fade with time. Although the preparation methods have been recognized since the mid-eighteenth century as a contributory factor in the fading of the pigment, the spectral and physical properties of Prussian blue that vary with the type of synthesis were not precisely identified. Several Prussian blue pigments have been prepared by different methods and characterized by thermogravimetric analyses, high-energy powder X-ray diffraction, atomic absorption and flame emission, UV–visible, iron-57 Mössbauer, iron K-edge X-ray absorption, and Raman spectroscopy. The type of synthesis influences the hue, tinting strength, and hiding power properties of the Prussian blue pigments. Two major features appear to be strongly dependent on the preparative methods, the particle size and the local disorder. Both a nitrogen atmosphere and an intermediate aging step of the Berlin white, Fe2II[FeII(CN)6], during the synthesis are required to obtain a highly colored pigment through the optimization of particle size, minimization in the perturbations to the FeII–CN–FeIII intervalence electron transfer pathway, and the minimization of disordered vacancies. The potassium containing Prussian blue structure has been revisited. It can be described with the Pm3m space group, where approximately one-quarter of the [FeII(CN)6]4– sites are vacant and where the potassium cation is located at a zeolitic-like position inside the lattice cavities. The degree of ordering of the [FeII(CN)6]4– vacancies in all Prussian blues was quantified using atomic pair distribution analysis, an ordering that is consistent with the iron K-edge X-ray absorption spectra. The presence of strain in the crystals is observed by both powder X-ray diffraction and Mössbauer spectroscopy. The structural similarity between the alkali-free, improperly referred to as “insoluble”, and the alkali containing, “soluble”, Prussian blues may explain why the two varieties are almost undistinguishable by spectroscopic techniques. [less ▲]

Les ruminants sont des émetteurs importants de gaz à effet de serre : que faire pour les atténuer ?

Scientific conference (2013, April 10)

Occupational activity and cognitive reserve: implications in terms of prevention of cognitive aging and Alzheimer’s disease

in Clinical Interventions in Aging (2013), 8

This paper investigates the relationship between the concept of activity (including both professional and nonprofessional) and cognitive functioning among older European individuals. In this research, we ... [more ▼]

This paper investigates the relationship between the concept of activity (including both professional and nonprofessional) and cognitive functioning among older European individuals. In this research, we used data collected during the first wave of SHARE (Survey on Health, Ageing and Retirement in Europe), and a measurement approach known as stochastic frontier analysis, derived from the economic literature. SHARE includes a large population (n . 25,000) geographically distributed across Europe, and analyzes several dimensions simultaneously, including physical and mental health activity. The main advantages of stochastic frontier analysis are that it allows estimation of parametric function relating cognitive scores and driving factors at the boundary and disentangles frontier noise and distance to frontier components, as well as testing the effect of potential factors on these distances simultaneously. The analysis reveals that all activities are positively related to cognitive functioning in elderly people. Our results are discussed in terms of prevention of cognitive aging and Alzheimer’s disease, and regarding the potential impact that some retirement programs might have on cognitive functioning in individuals across Europe. [less ▲]

Dynamic Stall and Stall Flutter Simulations for a 2D Airfoil Using Viscous-Inviscid Coupling

in Proceedings of the 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (2013, April 10)

An interactive boundary layer model has been developed and coupled with a pitch plunge airfoil in 2d in order to solve the unsteady flow around the airfoil when undergoing light dynamic stall. The ... [more ▼]

An interactive boundary layer model has been developed and coupled with a pitch plunge airfoil in 2d in order to solve the unsteady flow around the airfoil when undergoing light dynamic stall. The inviscid problem is solved by means of a panel method, by the discretization of the airfoil into vortex panels. The boundary layer is solved in a mixed manner, starting the solution in a direct way by imposing the external velocity and continuing it in an inverse way by imposing the displacement thickness. The solution of the boundary layer equations is carried out using a finite volume scheme. Viscous-inviscid coupling is preformed through the imposition of a permeation velocity on the skin panels of the airfoil and the addition of a free wake at each separation point. [less ▲]

Validation of the Structural-Thermal-Model of the Small Earth Observation Satellite Flying Laptop

Poster (2013, April 10)

Thorough thermal design and testing is compulsory for every satellite mission. A well-known thermal behavior of the entire satellite system is therefore indispensable and needs to be verified during the ... [more ▼]

Thorough thermal design and testing is compulsory for every satellite mission. A well-known thermal behavior of the entire satellite system is therefore indispensable and needs to be verified during the spacecraft development. A Structural-Thermal-Model (STM) was constructed for the Flying Laptop, a satellite currently being developed at the Institute of Space Systems (IRS) of the University of Stuttgart, which enables the validation of mechanical and thermal simulations for the satellite’s Flight-Model. The STM was vibration and thermal-vacuum tested at the Centre Spatial Liège (CSL). This paper will de-scribe the design and construction of the STM as well as the facilities and test equipment used for the tests. Conclusions will be drawn from the actual test results. [less ▲]

On women’s bodies. Religion and female circumcision in Egypt

Scientific conference (2013, April 10)

Among discourses about female circumcision, frequent are those which attribute it to religious beliefs, in particular Islamic ones. An ethnographic research conducted in Egypt, lead me to deconstruct such ... [more ▼]

Among discourses about female circumcision, frequent are those which attribute it to religious beliefs, in particular Islamic ones. An ethnographic research conducted in Egypt, lead me to deconstruct such simplistic association, in order to explore how we can (and if is it possible to) consider such a practice as a performing of religion on women’s bodies. In fact, in the context considered, first of all not only the Islamic religion is called into question, but also the Christian one; secondly, social dynamics are deeply intertwined with spiritual beliefs. In this framework, female circumcision has a precise role in the definition of the healthy sexuality of the couple and in the maintaining of the very same social order insofar it reflects a cosmic one. As a matter of fact, on the one hand religion is functional to legitimize a practice exerted upon women’s bodies which is perceived as essential to regulate social interactions, in the domestic context as well as in the public space. On the other hand, discourses and acts promoting and abandonment of female circumcision rely they themselves on religious precepts. These complex dynamics need to be deeply explored, in order to produce a wider knowledge about a controversial practice. The aim of my paper is to give voice to the literature on the subject and to the social actors involved in my ethnographic experience, among which several women themselves, so as to highlight in which ways religion (Islamic and Christian ones) and the practice of female circumcision are connected. [less ▲]