http://depot.umc.edu.dz/handle/123456789/7647 Wed, 17 Jun 2026 14:03:18 GMT 2026-06-17T14:03:18Z http://depot.umc.edu.dz/handle/123456789/14840 Contribution à l'élaboration de l'oxyde de titane par le procédé sol-gel Bouachiba, Yassine; Bouabellou, Abderrahamane The present work consists in the elaboration and the characterization of TiO2 thin films by sol-gel method. Particular attention is paid to the influence of temperatures, the annealing atmosphere, the thickness, the nature of the substrates and doping with Fe element on the different structural, morphological, optical, dielectric and chemical properties. The different samples are characterized by the X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy, FTIR spectroscopy, spectroscopic ellipsometry, UV-Visible spectroscopy, m-lines spectroscopy and hydrophilic measurements. The structural study shows that the crystallization of the films occurs for critical thicknesses. The thermal annealing under various atmospheres (air and oxygen) and the presence of buffer layers between the TiO2 film and the substrate are important factors affecting the formation and improving the structure of anatase and rutile phases. The phase transformation anatase-rutile occurs at high temperature (800°C). The SnO2 interfacial layer and the high doping level (7% at.) have the effect of decreasing the temperature of this transformation. The morphological study shows, in general, a uniform growth with relatively low roughness, which bodes the optical quality of the films obtained. The optical study shows that the values of the refractive indices derived using the sem-infinite, Fourouhi-Bloomer and EMA models are in good agreement with those of the literature. The study of the optical gap obtained by spectroscopic ellipsometry and the UV-visible spectroscopy reveals some variation depending on various parameters. The waveguiding measurements show that TiO2 films deposited directly on the glass behave as single-mode waveguides in the two polarizations (TM and TE). When SnO2 and ZnO films are used as buffer layers, we note the disappearance of TM modes. The dielectric study shows that the approach based on the Kramers-Kronig analysis and Maxwell's equations is proved acceptable in comparison with other known models. The analysis of wetting water shows the super-hydrophilicity of TiO2/verre and TiO2/(ZnO/glass) samples. Thu, 08 May 2014 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14840 2014-05-08T00:00:00Z http://depot.umc.edu.dz/handle/123456789/14830 Investigation phytochimique et biologique de la propolis Algérienne. Daikh, Amina; Segueni, Narimane Our study is interested in the investigation of the chemical composition and the biological activities of Algerian propolis. In the first part of our study we examined several propolis harvested from Algerian East in order to compare their antibiofilm and cytotoxicity activities, In addition, the UPLC-ESI-MS/MS analysis of the most active extracts was also evaluated. In the second part we studied the antioxidant capacity of two other propolis by five different methods. The total phenolic and flavonoid contents were evaluated. Propolis of Mila exhibited the highest antioxydant activity. This result encouraged us to study the cytotoxicity activity of the extracts of this propolis. This propolis acts on MDA-MB- 231 cells by inducing apoptosis by increasing the concentrations of Bax, caspase 3 and p53 proteins as well and decreasing Bcl2 and CDK-4 proteins. These results are confirmed by the study of mRNA and cDNA. In the last part of our work we were interested in the chemical composition of Algerian propolis. After extraction, separation and purification, we obtained 6 pure flavonoids 5,4'-dihydroxy-6,7-dimethoxyflavone (Cirsimaritine), 7-methoxy 3,5 dihydroxyflavonol (Galangine 7-methoxy), 4',5,7-trihydroxy-3-methoxyflavone (isokampferide), 5,7-dihydroxy-flavanone (Pinocembrine), Apigenin 7-methoxy (Genkwanin) and Apigenin. Our study demonstrated that all the studied propolis are probably of t poplar type. Thu, 07 Dec 2023 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14830 2023-12-07T00:00:00Z http://depot.umc.edu.dz/handle/123456789/14828 Synthèse, caractérisation, etude structurale par diffraction des rayons X et réactivité thermique des carboxylates à base d’alcalino-terreux. Bendjellal, Nassima; Boudaren, Chaouki The main purpose of this thesis is based on the synthesis and characterization of new coordination compounds based on alkaline-earth metals. Two synthesis methods were used to prepare these materials: synthesis by way of chemistry in solution and by solvothermal route. The structural study and physico-chemical characterization of these compounds was achieved by several techniques such as: spctroscopie IR, UV spectroscopy, X-ray fluorescence, crystal structures of materials hybrids have been solved by X-ray single crystal and thermal behaviors were studied by thermogravimetry, has fully describe the mechanisms of the decomposition of the solid. Likewise, the influence of the bond strength within the hydrogen-bonding network on both the structure stability has been evidenced within these architectures. Initially, the synthesis and the structural characterization by X-ray diffraction as well as the study of the physico-chemical and photophysical properties and the thermal stability by the use of cinnamic acid associated with the Co-ligand 1, 10’-phenthroline led to the production of four coordination polymers. In a second step, we describe the preparation of a dicarboxylate ligand on imidazolium H(S,S-diLeuIm) and the synthesis of three complexes by aqueous solution method based on K, Sr, Ba and characterized by methods IR, RMN spectroscopy and EM-MS mass. Tue, 20 Jun 2023 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14828 2023-06-20T00:00:00Z http://depot.umc.edu.dz/handle/123456789/14823 Généralisation de certaines inégalités intégrales non linéaires avec retard et applications. Kriket, Salah; Boudeliou, Ammar Gronwall-Bellman inequalities and their various generalizations that give explicit bounds on unknown functions provide a very useful and important device in the study of many qualitative properties of solutions of differential equations, integral equations and integrodifferential equations. The purpose of this work is to give an exposition of some classical and modern results about integral inequalities, and establish some new nonlinear integral inequalities with delay in two independent variables, which generalize some known inequalities recently obtained. These results can be used as handy tools to study the boundedness of solutions of Volterra integral equations. Applications are given to illustrate how our results can be applied to study the boundedness of the solutions of certain Volterra equations. The research on this topic is also large and continues until now, the impressive number of publications on this subject testifies to this. Thu, 16 Nov 2023 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14823 2023-11-16T00:00:00Z