Entre les Murs et L\u27exclusion: L\u27echec du Systeme Educatif Francais

This thesis examines the issues of the modern French education system through an analysis of the film, Entre Les Murs (2008) and French education\u27s socio-historical and political context. The study finds that the way in which France thinks about authority, language, and multiculturalism leads to the exclusion of certain students from the learning process. The aim of the study is to critically rethinks these issues in light of theories on race, identity, and postcolonialism in order to eventually propose solutions so that all students may fully flourish in modern French society

Study of rheological and mechanical properties of ternary blends of iPP/LDPE/EPDM

Compatible blends of isotactic polypropylene (iPP)/low density polyethylene (LDPE)/ethylene-propylene-diene monomer (EPDM) were prepared by reactive blending in the presence of dicumyl peroxide (DCP). The blends were characterized using different techniques: dynamical rheological analysis (DRA), differential scanning calorimetry (DSC), optical microscopy (OM) and scanning electron microscopy (SEM), dynamical mechanical thermal analysis (DMTA), viscosity and impact strength, to evaluate their properties. Results revealed that the presence of the peroxide in LDPE/EPDM blends gives rise to crosslinking reactions, as is the case in iPP/LDPE/EPDM blends. However, in the latter case, scission reactions of the iPP component also take place. As a consequence of the whole process, morphological changes arise mainly in the amorphous regions, without affecting the degree of crystallinity of the components. The mechanical properties of the blends are consequently improved, due to the crosslinked network thus formed in the blends.Peer reviewe

Nanostructure and morphology of poly(vinylidene fluoride)/polymethyl (methacrylate)/clay nanocomposites: correlation to micromechanical properties

11 pags., 7 figs., 2 tabs.Nanocomposites based on poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) with untreated clay were prepared in one step by reactive melt extrusion. Chemical reactions took place between the polymer matrices, the inorganic clay particles, and three reactive agents, leading to the PVDF/PMMA/clay nanocomposites. The microstructure characterizations were carried out by differential scanning calorimetry and wide-angle X-ray scattering (WAXS). The mechanical behavior was investigated by tensile experiments, impact tests, and microhardness measurements. The morphological characterization was carried out by optical and atomic force microscopy (AFM). The decrease of the melting and crystallization temperatures of the PVDF with the increasing PMMA content is attributed to the interactions between the oxygen of the PMMA carbonyl group and the PVDF’s hydrogen atom. WAXS analysis shows that there is neither an intercalation step nor total exfoliation in any composition. As the PMMA content increases, WAXS diagrams show either the PVDF α-crystallographic form, both, α- and β-forms, or only the β-form. For PMMA contents higher than 40 wt%, the materials became amorphous. The microhardness of the samples decrease for a PMMA content up to 20 wt%. The study by optical microscopy and AFM illustrates the significant effect in the presence of clay on the film’s surface morphology.FJBC gratefully acknowledges the MINECO, Spain (Grant MAT 2013–47898-C2-1-R) for the generous support of this work.Peer Reviewe

Study of nanoclay blends based on poly(ethylene terephthalate)/poly(ethylene naphthalene 2,6-dicarboxylate) prepared by reactive extrusion

Copyright © 2011-2014 by Walter de Gruyter GmbH. The success of processing compatible blends, based on poly(ethylene terephthalate) (PET)/ poly(ethylene naphthalene 2,6-dicarboxylate) (PEN)/clay nanocomposites in one step by reactive melt extrusion is described. Untreated clay was first purified and functionalized >in situ> with a compound based on an organic peroxide/ sulfur mixture and (tetramethylthiuram disulfide) as the activator for sulfur. The PET and PEN materials were first separately mixed in the molten state with functionalized clay. The PET/4 wt% clay and PEN/7.5 wt% clay compositions showed total exfoliation. These compositions, denoted nPET and nPEN, respectively, were used to prepare new nPET/nPEN nanoblends in the same mixing batch. The nPET/nPEN nanoblends were compared to neat PET/PEN blends. The blends and nanocomposites were characterized using various techniques. Microstructural and nanostructural properties were investigated. Fourier transform infrared spectroscopy (FTIR) results showed that the exfoliation of tetrahedral clay nanolayers is complete and the octahedral structure totally disappears. It was shown that total exfoliation, confirmed by wide angle X-ray scattering (WAXS) measurements, contributes to the enhancement of impact strength and tensile modulus. In addition, WAXS results indicated that all samples are amorphous. The differential scanning calorimetry (DSC) study indicated the occurrence of one glass transition temperature Tg, one crystallization temperature Tc and one melting temperature Tm for every composition. This was evidence that both PET/PEN and nPET/nPEN blends are compatible in the entire range of compositions. In addition, the nPET/nPEN blends showed lower Tc and higher Tm values than the corresponding neat PET/PEN blends. In conclusion, the results obtained indicate that nPET/nPEN blends are different from the pure ones in nanostructure and physical behavior.FJBC gratefully acknowledges the MINECO, Spain (Grant FIS2010-18069), for the generous support of this investigation. SB, FZ, DB, FJBC and MEC thank the financial support from the CSIC of the Project I-COOP0123 between the CSIC and the University of Sétif.Peer Reviewe

Interobserver variability study for daily cone beam computed tomography registration of prostate volumetric modulated arc therapy

Purpose. - This work evaluated the interobserver variability in cone beam computed tomography (CBCT) registration for prostate cancers treated with intensity-modulated radiotherapy. Material and methods. - Twelve technologists realized 286 CBCT/CT registrations (bone registration followed by prostate to prostate registration). The registration results were compared to those obtained by two radiation oncologists (reference). Each technologist reported the shifts calculated by the software in all three axes. A statistical analysis allowed us to calculate the minimum threshold under which 95% of the observers found similar values. A variance analysis followed by the post hoc test were used to find differences in interobserver registration variability and determine whether any individual users performed registrations which differed significantly from those of the other users. Results. - The registration differences compared to the reference in the three directions in terms of 95th percentile are: 2.1 mm left-right, 3.5 mm target-gun, 7.3 mm anterior-posterior. In the posterior direction, 4% of the observers have found differences superior to 8 mm, margin used in routine without the use of a daily CBCT. The variance test revealed a P-value <0.05 only for target-gun and for all observers there was no significant difference compared to the reference. Conclusion. - This study confirmed the interest of a 3D tissue registration for prostate treatments. The registration study showed a good interobserver reproducibility. This showed the importance of a daily CBCT/CT registration in prostate treatment with the possibility of a planning target volume margin reduction in the three directions. An evaluation of a partial delegation of registration to technologists should be done by the radiation oncologists. (C) 2015 Societe francaise de radiotherapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved

Nanostructural characterization of poly (vinylidene fluoride)-clay nanocomposites prepared by a one-step reactive extrusion process

10 pags.; 8 figs.; 5 tabs.Poly (vinylidene fluoride) (PVDF)-untreated clay nanocomposites were successfully prepared using an innovative one-step reactive melt extrusion process. Through specific temperature and shear conditions, the chemical reactions took place between the polymer matrix, the inorganic clay particles, and three main reactive agents: an organic peroxide, sulfur, and a specific activator led finally to the PVDF-clay nanocomposites. The materials were formulated with various amounts of clay in order to identify the best conditions, enabling to obtain the optimal particle exfoliation in the polymer matrix at the nanometric scale. The microstructure and nanostructure modifications were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and wide- and small-angle X-ray scattering (WAXS and SAXS). The relationship between nanostructure and mechanical behavior was investigated by tensile experiments, impact tests, and microhardness measurements. The FTIR results suggest that there is a chemical interaction between the clay and the polymer. Furthermore, the WAXS study shows that no intercalation step takes place in any composition. In addition to this, the sample with 2.5 wt.% clay could present a total exfoliation of the clay particles. The PVDF matrix is found to be exclusively of the α-form in all compositions. The final microhardness slightly increases with both nanoclay content and degree of crystallinity.F.J.B.C. gratefully acknowledges the MINECO, Spain (Grant FIS2010-18069), for the generous support of this investigation. F.J.B.C. also wishes to acknowledge the Alexander von Humboldt Foundation for the generous support during this work. S.B. and M.E.C. thank the Agencia Española de Cooperación Internacional para el Desarrollo (AECID) (Grant C/032183/10) for financial support and also the cooperation project between the Spanish CSIC and the University of Sétif, Algeria (Grant I-COOP0123).Peer Reviewe

Sintering of anorthite based ceramics prepared from kaolin DD2 and calcite

Abstract In this work, the preparation of anorthite based ceramics using a modified milling system and 80 wt% kaolin (DD2 type) and 20 wt% calcium oxide extracted from CaCO3 is shown. The choice of these raw materials was dictated by their natural abundance. Previous studies have shown that a simple and vibratory multidirectional milling system using a bimodal distribution of highly resistant ceramics can be successfully used for obtaining fine powders. The prepared samples were sintered at different temperatures ranging between 800 and 1100 °C. It has been found that the relative density of samples sintered at 900 °C for 1 h with a heating rate of 5 °C/min was about 96% of the theoretical density of anorthite (2.75 g/cm3). Finally, the prepared samples were also characterized by scanning electron microscopy, X-ray diffraction and Raman spectroscopy