Publications Scientifiques
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Item Effect of Fe content on the structural and magnetic properties of ternary (Ni 60 Co 40 ) 100-x Fe x nanomaterials synthesized by hydrothermal route(World Scientific, 2024) Gaci, Yacine; Guittoum, Abderrahim; Hemmous, Messaoud; Martínez-Blanco, David; Gorria, Pedro; Blanco, Jesús A.; Aouaroun, TaharThe effect of iron content on the structure, morphology and magnetic properties of (Ni60Co40)100-xFex powders synthesized by hydrothermal method has been studied. Several samples have been elaborated for different Fe content (x = 0, 3, 5, 7, 10 and 13.5). The as- prepared samples have been characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometry (VSM). From XRD spectra and for all Fe content, we have shown the presence of both face centered cubic (FCC) and Hexagonal (HCP) nanosized phases. The lattice parameter increases with increasing Fe content and the grains size varies with Fe content to reach a minimum value of 32 nm for (Co40Ni60)90Fe10. From hysteresis curves, we have extracted the saturation magnetization, Ms, and the coercivity, Hc. We noticed that Ms increases and then decreases as a function of Fe content. The values of Hc vary from 156 Oe to 186 Oe depending on the particles shape.Item Sex differences in adrenal cortex beta-catenin immunolocalisation of the Saharan gerbil, Libyan jird (Meriones libycus, Lichtenstein, 1823)(Via Medica, 2023) Aknoun-Sail, Naouel; Zatra, Yamina; Sahut-Barnola, Isabelle; Benmouloud, Abdelouafi; Kheddache, Arezki; Khaldoun, Mounira; Charallah, Salima; Khammar, Farida; Martinez, Anne Marie Lefrançois; Amirat, ZaïnaBackground: The adrenal cortex provides adequate steroidogenic responses to environmental changes. However, in desert rodents, the adrenocortical activity varies according to several factors especially sex, age, and seasonal variations. Herein, we examined the sex differences in the adrenal cortex activity and explored the involvement of sex hormones in the regulation of this function in Libyan jird Meriones libycus. Materials and methods: Twenty-four adult male and female animals weighing 109–110 g were captured in the breeding season and equally assigned into control and gonadectomised groups. Animal euthanasia was performed 50 days after the gonadectomy. Adrenal gland was processed for structural and immunohistochemistry study of b-catenin, whereas plasma was used for cortisol assay. Results: The results showed that female adrenal gland weight was heavier than male and gonadectomy reduced this dimorphism. The adrenal cortex thickness was greater in the female than in the male, mainly due to significant development of the zona fasciculata. Females presented higher cell density in fasciculata and reticularis zones. The plasma cortisol was higher in females than in males. The immunolocalisation of b-catenin showed that the expression was particularly glomerular in both sexes. However, in the female, the immunostaining was present in the zona reticularis while it was absent in the control male. Orchiectomy reduced zona glomerulosa cell density and induced hypertrophy of zona reticularis characterised by strong b-catenin immunoreactivity. However, ovariectomy leads to hyperplastic expansion and high b-catenin expression in the zona glomerulosa associated with zona fasciculata and reticularis hypoplasia distinguished by weak b-catenin immunostaining. Conclusions: Results indicated that sex hormones had a major role in the regulation of the Saharan gerbil’s adrenal homeostasis by modulating b-catenin signalling. Androgens seem to inhibit the Wnt-b-catenin pathway and oestrogens are activators of the adrenal inner zones.Item Hydrothermal synthesis of co nanoparticles : structure, morphology and magnetic properties(World Scientific, 2021) Bouelkreb, I.; Guittoum, A.; Hemmous, M.; Martínez-Blanco, D.; Gorria, P.; Blanco, J. A.; Boukherroub, N.We have investigated the crystal structure, the microstructural and morphological characteristics, as well as the magnetic properties of Co nanoparticles (NPs) synthesized by a hydrothermal method. A series of samples has been elaborated for different concentrations of sodium hydroxide. The analysis of X-ray diffraction patterns, using two different wavelengths, has evidenced the coexistence of both α-Co and β-Co phases in the samples. The lattice parameter for both phases is in good agreement with those values expected for their bulk Co counterparts; the grain sizes of NPs were found to be dependent on the NaOH concentration. The scanning electron microscope micrographs show that Co NPs are agglomerated forming micrometer-sized entities whose shape evolves, indicating that the synthesis process affects the morphology of the powdered samples. Magnetic measurements indicate that the coercivity is slightly larger, HC>200 Oe, for Co NPs with dendritic-like shape, probably due to an increase in the magnetocrystalline anisotropyItem Parametric study of the mechanical properties of nanocrystalline TiN/CrN multilayer coatings with a special focus on the effect of coating thickness and substrate roughness(Elsevier, 2021) Atmani, Taous Doria; Gaceb, M.; Aknouche, Hamid; Nouveau, C.; Bouamrene, M.S.In a plot to improve the performance of steel mechanical parts subject to aggressive friction solicitations, three batches of deposits of TiN and CrN layers on steel substrates with two different roughnesses have been obtained using reactive DC magnetron sputtering. The present study was conducted to determine the effect of varying TiN/CrN multilayer coatings thickness (varying modulated period Λ and interlayer thickness), on their mechanical and tribological properties. The morphological and the structural properties were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The nanoindentation measurements displayed improvement in hardness (> 40 GPa) and Young's modulus (> 600 GPa) for the coating with Λ ≅ 12 nm (TiN Λ/2 ≅ 7.5 nm + CrN Λ/2 ≅ 4.5 nm) thickness and the higher number (300) of interfaces, deposited on the rougher substrate. Its low coating damage under the scratch test, associated with its estimated adhesion work (Wad), indicated a good cohesive/adhesive strength and improved structural and mechanical propertiesItem Contribution of the organo-montmorillonite/graphene pair to the rheological and mechanical properties of polyethylene matrix based nanocomposites(Elsevier, 2017) Rahmaoui, Fath Eddine Zakaria; Mederic, Pascal; Aït Hocine, Nourredine; Aït Saada, Aïcha; Poirot, Nathalie; Belaidi, IdirItem Relationship between the fractal structure with the shear complex modulus of montmorillonite suspensions(Elsevier, 2016) Gareche, Mourad; Allal, A.; Zeraibi, Noureddine; Roby, F.; Azril, N.; Saoudi, L.Item Classification de structures arborescentes : cas de documents XML = Classification of tree structures: case of the XML documents(2009) Ait El hadj, Ali; Mezghiche, Mohamed; Souam, F.