Elaboration par chimie douce et caractérisations de semi-conducteurs nanométriques à base de sulfures (de type CuInS2) et d'oxydes (de type CuMoO4)

L'intérêt porté sur la miniaturisation des systèmes par la communauté scientifique est grand, que ce soit pour des raisons d'économie d'énergie, de mobilité ou d'innovation technologique. Le travail présenté dans ce manuscrit concerne l'élaboration par chimie douce et la caractérisation structurale, morphologique et physiques des semi-conducteurs à base de: - Sulfures métalliques CuInS2, CuIn(1-x)GaxS2, Cu2SnZnS4, - Oxydes métalliques CuMoO4, CuMo(1-x)WxO4. La première partie de cette thèse est consacrée à l'élaboration des nanoparticules de CuInS2 et Cu2ZnSnS4. Deux méthodes de synthèse ont été considérées pour l'élaboration de ces sulfures, purs ou dopés, sous la forme de poudre nanométrique. La première méthode consiste à faire réagir les chlorures métalliques dans un milieu de thiocyanate de potassium fondu (400°C), méthode utilisée pour la première fois pour la synthèse de CuInS2 et Cu2ZnSnS4. Dans la seconde voie nous avons employé le procédé polyol, qui consiste en une précipitation en milieu éthylène glycol à 200°C suivi d'un traitement thermique en milieu thiocyanate de potassium fondu. La deuxième partie de ce travail concerne l'étude du molybdates CuMo(1-x)WxO4 (avec 0 = x = 0,12). Quatre voies de synthèse ont été utilisées pour l'élaboration de ces molybdates: la voie solide, le procédé glycine - nitrate (G.N.P), la voie acrylate (prise au piège stérique) et la voie citrate. Les conditions optimales de synthèse ont été déterminées par la diffraction des rayons X et par d'analyse thermique. La granulométrie et la morphologie des poudres obtenues dépende de plusieurs paramètres: la méthode de synthèse, les conditions opératoires (la source de cuivre, pH, rapport acide citrique/cuivre (Cit/Cu), et température de calcination) et la concentration en tungstène. La dernière partie de ce travail est consacrée à l'étude de frittage des poudres de molybdate de cuivre. Deux méthodes de frittage ont été étudiées: le frittage conventionnel et le frittage par Spark Plasma Sintering(SPS). Les densifications obtenues pour molybdate non dopé sont respectivement de 95% et 99%. La céramique obtenue par SPS présente une taille des grains (0,5 micromètre) largement inférieur à celle obtenue de façon conventionnelle (2 micromètre).This manuscript decals with the elaboration by soft chemistry and the structural, morphological and physical characterization of semi-conductors based on: - Metallic sulfides CuInS2, CuIn(1-x)GaxS2, Cu2SnZnS4. - Metallic oxides CuMoO4, CuMo(1-x)WxO4. These materials exhibit potential applications on the field of photovoltaic conversion. The first part is concerned with the elaboration of nanoparticles of CuInS2 and Cu2SnZnS4. Tow synthesis methods are considered for the elaboration of these pure or doped sulfides, in the shape of nanometrical powders. The first method involves the reaction of metallic chlorides with a molten potassium thiocyanate medium (400°C). It is used for the first time for the synthesis of CuInS2 and Cu2SnZnS4. The second one is the polyol process. The precipitation occurs in ethylene glycol medium at 200°C. It is followed by a thermal treatment in molten potassium thiocyanate. The second part is devoted to the study of molybdates CuMo(1-x)WxO4 (With 0 = x= 0.12). Four synthesis routes were used for the elaboration of these molybdates: solid state reactions, the Glycine-nitrate process (G.N.P), the acrylate way (steric trapping) and the citrate route. The syntheses were optimized and the powders obtained characterized by XRD and thermal analysis. The granulometry and the morphology of powders are dependent upon several parameters: The synthesis method, the source of copper, the pH, the citric acid/Cu ratio (Cit/Cu), the calcinations temperature and the concentration in tungsten. The gap of powders, evaluated by UV-visible absorption spectroscopy varies between 2.02 eV for the molybdate a-CuMoO4 and 1.67 eV of the molybdate γ-CuMo0,88W0,12O4. The last part of this work is dedicated to the sintering processes were investigated: conventional sintering and spark plasma sintering (SPS). The relative densities obtained for the non doped molybdate are respectively 95 and 99%. The SPS sintered ceramic exhibits a grain size (0,5 micrometre) significantly lowers than that (2 micrometre) of the conventionally sintered ore. A preliminary study of the sintering of CuMo(1-x)WxO4 (With 0 = x= 0.12) has shown that the structure and the microstructure of the ceramics obtained is dependent upon the sintering method and the tungsten content

An ant colony based model to optimize parameters in industrial vision

Industrial vision constitutes an efficient way to resolve quality control problems. It proposes a wide variety of relevant operators to accomplish controlling tasks in vision systems. However, the installation of these systems awaits for a precise parameter tuning, which remains a very difficult exercise. The manual parameter adjustment can take a lot of time, if precision is expected, by revising many operators. In order to save time and get more precision, a solution is to automate this task by using optimization approaches (mathematical models, population models, learning models...). This paper proposes an Ant Colony Optimization (ACO) based model. The process considers each ant as a potential solution, and then by an interacting mechanism, ants converge to the optimal solution. The proposed model is illustrated by some image processing applications giving very promising results. Compared to other approaches, the proposed one is very hopeful.Industrial vision constitutes an efficient way to resolve quality control problems. It proposes a wide variety of relevant operators to accomplish controlling tasks in vision systems. However, the installation of these systems awaits for a precise parameter tuning, which remains a very difficult exercise. The manual parameter adjustment can take a lot of time, if precision is expected, by revising many operators. In order to save time and get more precision, a solution is to automate this task by using optimization approaches (mathematical models, population models, learning models...). This paper proposes an Ant Colony Optimization (ACO) based model. The process considers each ant as a potential solution, and then by an interacting mechanism, ants converge to the optimal solution. The proposed model is illustrated by some image processing applications giving very promising results. Compared to other approaches, the proposed one is very hopeful.Industrial vision constitutes an efficient way to resolve quality control problems. It proposes a wide variety of relevant operators to accomplish controlling tasks in vision systems. However, the installation of these systems awaits for a precise parameter tuning, which remains a very difficult exercise. The manual parameter adjustment can take a lot of time, if precision is expected, by revising many operators. In order to save time and get more precision, a solution is to automate this task by using optimization approaches (mathematical models, population models, learning models...). This paper proposes an Ant Colony Optimization (ACO) based model. The process considers each ant as a potential solution, and then by an interacting mechanism, ants converge to the optimal solution. The proposed model is illustrated by some image processing applications giving very promising results. Compared to other approaches, the proposed one is very hopeful

An Evaluation of Perceptual Classification led by Cognitive Models in Traffic Scenes

The objects extraction and recognition constitute the most important link in the image processing and understanding, and it cannot be achieved without a solid objects organization during the processing through the learning mechanisms. Most often, both the response time and the accuracy are undeniable criteria for applications in this field. Actually, a vision system need to take into consideration these criteria, either in the structural, the methodological or in the algorithmic aspect. Thus, we consider that the ontological study at the domain and task levels, in the vision systems, has become essential in order to provide a substantial assistance to the multitudes of applications in image processing. Concerning the domain knowledge, several patterns for structuring were proposed to improve the objects representation and organization, they often advocate the precision aspect on time and on effort devoted to the recognition. In practical terms, clustering methods only focus on the accuracy aspect within a category, without considering the recognition aspect [1]. Thus, we propose in this study a new procedure of object categorization, which uses, according to the expertise in the domain, a fit evaluation that is able to adjust the level of partitioning. As a result, this procedure will find a compromise between the accuracy on the categories and the reduction of the supplied effort in recognition.  

Psoriasis and staphylococcus aureus skin colonization in Moroccan patients

Psoriatic lesions are rarely complicated by recurrent infections. The aim of our study is to determine skin colonisation and nasal carriage of Staphylococcus aureus in patients with psoriasis and in healthy  persons. Patients and methods: a comparative study that include 33 patients with psoriasis and 33  healthy persons.Samples were taken from lesional and non lesional psoriatic skin and from healthy skin of control group. For S. aureus nasal carriage, we used sterile cotton tipped swabs. Out of165 samples (66 skin samples and 33 nasal swabs), 26 S. Aureus strains were isolated in 26 persons, 57.69% in the  control group and 42.3% in the psoriasisgroup. S. aureus skin colonization was found in one case (3%) inlesional psoriatic skin vs 9 cases (27.3%) in control skin OR=0.08 IC 95% (0.01-0.70) p=0.02 and in 12,1% in non lesional soriatic skin vs 27, 3% in control skin (p =0,13). This colonization was less important in lesional psoriatic skin (3%) than in non lesional psoriatic skin (12.1%) p= 0.20. Nasal screening identified (7/33) 21, 21% S. aureus carriers in psoriasis group and in control group. Our results are in consensus withliterature findings. They have confirmed the importance of antimicrobial peptides in Innateimmunity of human skin. These peptides are normally produced bykeratinocytes in response to inflammatory stimuli such as psoriasis. Their high  expression in psoriasis skin reduces the risk of skin infection and skin colonization with S. Aureus.Key words: Antimicrobial peptides, innate immunity, nasal carriage, psoriasis, skin colonization, staphylococcus aureu

Synthesis and physicochemical characterization of pigments based on molybdenum «ZnO-MoO3: Co2+»

International audienceMolybdatesZn1-xCoxMoO4(0≤ x ≤0.3) were elaborated by the Sol-Gel method with pH=3.The results obtained by DRX show a single-phase domain startingfrom 500°C for x ≤ 0.3 isostructural to ZnMoO4.The powder ofZn0.7Co0.3MoO4treated at 500°C and 700°C is formed by nano-sized primary crystallitesof size between 80 and 160nm. The colorimetric parameters (L a* b*) of powders obtained at 700°C present adegree of high bluing

Case Series

Au Maroc peu d'études ont été menées concernant les facteurs pronostiques du mélanome.L'objectif de cette étude était d'identifier les facteurs de survenue de métastases viscérales à distance à 1an et de mortalité à 2ans chez des patients atteints de mélanome cutané épais. Ont été colligés rétrospectivement tous les cas de mélanomes suivis au service de dermatologie et d'oncologie du CHU de Casablanca de 2006 à 2010.On été inclus les patients qui présentaient un mélanome à localisation  cutanée et/ou muqueuse buccogénitale, confirmés histologiquement ayant un Breslow>2mm. Ont été exclus les patients présentant des métastases viscérales à distance au moment du diagnostic. Les  données sociodémographiques, cliniques et thérapeutiques ont été recueillies au niveau des dossiers; celles relatives à l'évolution ont été complétées par contact téléphonique. L'analyse statistique était de type uni et bivarié. Soixante patients ont été inclus:41hommes et19femmes (sexe ratio de 2,15).La moyenne d'âge était de 60 ans (17-96). L'indice de Breslow était en moyenne de10mm+/-7et78%des  patients(32) avaient un Breslow>4mm. Vingt trois patients (38,3%) avaient des adénopathies  régionales. Quatorze patients ont présenté des métastases à distance après 1an (23,3%) et13patients étaient décédés après 2ans d'évolution (21,7%). Les facteurs associés à la survenue de métastases à distance étaient l'indice de Breslow. Des métastases à 1an ont été retrouvées chez 61,5%des patients avec un Breslow >10mm contre18,8% avec un BreslowKey words: Mélanome, épais, métastases, mortalité, Breslo

Sol–gel synthesis and sintering of submicronic copper molybdate (α-CuMoO4) powders

A sol–gel method was proposed to prepare copper II molybdate α-CuMoO4 powders. A gel was first obtained via the polymerizable complex method, using citric acid as complexing and polymerizing agent, dried at 120 °C and decomposed at 300 °C. A calcination in the temperature range 400–500 °C for 2 h led to the pure phase α-CuMoO4. The different powders obtained were characterized by X ray diffraction analysis and by transmission (TEM) and scanning (SEM) electron microscopies. Ceramics were prepared using conventional sintering and spark plasma sintering (SPS) techniques. A maximal relative density of 94.8% was reached after conventional sintering at 520 °C for 2 h. In the case of SPS, the densification was optimized by varying the temperature, the time and the applied pressure. Higher densities, up to 98.7%, were obtained at very low temperature, i.e., 300 °C, for 5 min only under a pressure of 225 MPa

Synthesis of CuInS2 nanometric powder by reaction in molten KSCN

CuInS2 was synthesized, with a yield of 70% by reaction in molten KSCN at 400 °C of CuCl2 and InCl3 with a ratio KSCN/Cu=15. The homogeneous powder obtained is constituted of nano-sized grains (70–100 nm), with a specific surface area of 6 m2/g and a band gap Eg of 1.5 eV

Molten Salt Synthesis and Characterization of CuIn(1-x)GaxS2 (x ≤0.3) Nanoparticles.

Solid solutions CuIn(1-x)GaxS2 (x ≤ 0.3)were synthesized, with a yield of 70%, by reaction in molten KSCN at 400°C for 24h of CuCl2, InCl3 and GaCl3 with a ratio KSCN/Cu=15. The homogeneous solid solutions obtained are formed of nano-sized grains (70–100nm), with a specific surface area of 6.5 m2/g and a band gap between 1.5 and 1.8 eV

Structural and microstructural characterization of CuMo(1-x)WxO4 (x ≤ 0.12) ceramics sintered by spark plasma sintering

Cupric molybdate CuMoO4is an interesting material due to their rich electrical, optical and magnetic properties. In this work, Solid solutions CuMo(1-x)WxO4(x≤0.12) were obtained by pyrolysis at 400 -700°C for 2 hours of a polymeric precursors elaborated by polymerizable complex method. For x ≤ 0.075, they were isostructural with α-CuMoO4 and for 0.075<x≤0.12, they were isostructural with γ-CuMoO4. Spark Plasma Sintering (SPS) at 300°C for 5 min under an applied pressure of 200 MPa led to variety CuMoO4-III for tungsten contents in the range 0.075-0.12