Evaluation de la bioaccumulation du plomb dans les espèces animales marines et identification des sources de contamination métallique par une analyse multiélémentaire en métaux (Al, Cd, Cr, Cu, Pb) dans les eaux côtières du Bénin

Différentes études complémentaires ont été menées sur le littoral de l’Océan Atlantique et l’estuaire du Chenal de Cotonou au Bénin, deux zones qui ont des profils et activités différents. La bioconcentration du plomb a été évaluée chez les poissons herbivores (Sphyraena afra, Lutjanus goreensis, Elops lacerta, Lutjanus goreensis et Decapterus rhonchus), les carnivores (Acanthurus monrovia et Pseudupeneus prayensis) et les crevettes (Penaus nottialis). Les concentrations les plus fortes de plomb (ANOVA,

Performance environnementale et economique dans la production de la grande morelle (Solanum macrocarpon) au Sud du Benin : Une evaluation des efficacites technique, allocative, economique

L’objectif de cette étude est d’analyser les efficacités technique, allocative et économique dans la production de la grande morelle. Pour cela, une  étude descriptive et analytique a été réalisée sur un échantillon de 126 maraîchers des sites de production de Houéyiho, de Sèmè-Kpodji et de  Ouidah au sud du Bénin. Les efficacités technique et économique ont été estimées respectivement à l’aide des modèles frontières stochastiques translogarithmique et fonction de coût dual avec la spécification Cobb-Douglas. Le modèle de régression tobit a été utilisé afin d’identifier les facteurs déterminants les efficacités des producteurs. Les résultats obtenus montrent que les facteurs main-d’oeuvre et engrais chimique sont sur-utilisés, ce qui entraîne des inefficacités dans la production. Les efficacités technique, allocative et économique sont respectivement en moyenne de 0,689 ; 0,882 et de 0,607. L’âge du producteur, la superficie emblavée, la contribution de la grande morelle dans le revenu, le niveau d’instruction et la formation technique sont les principaux déterminants des efficacités technique, allocative et économique des producteurs de la grande morelle. Sur la base des résultats obtenus, il importe d’améliorer l’efficacité des producteurs et augmenter ainsi leur profit par la recherche de moyens de lutte efficace et le renforcement de l’encadrement technique des producteurs. Mots clés : efficacités, frontières stochastiques, fonctions translog, fonction Cobb-Douglas, Solanum macrocarpon. English title: Environmental and economic performance in the production of the great nightshade (<i>Solanum Macrocarpon</i>) in southern Benin: An assessment of technical, allocative and economic efficiencies The objective of this study is to analyse the technical, allocative and economic efficiencies in the production of Solanum macrocarpon in Southern-Benin. For this purpose, a descriptive and analytical study was conducted among 126 Solanum macrocarpon growers in Cotonou, Sèmè-kpodji and Ouidah. The technical and economic efficiencies were estimated respectively using translogarithmic stochastic frontier models and dual cost function with the Cobb-Douglas specification. The Tobit regression model was used to identify the determinants of producers efficiencies. The results show that labor and chemical fertilizers are overused, leading to inefficiencies in production. The averages of technical, allocative and economic efficiencies are 0.689; 0.882 and 0.607 respectively. The age of the producer, the surface grown, the contribution of solanum in the income, the educational level and the training in farming are the principal determinants of the technical, allocative and economic efficiencies of the solanum’s producers. On the basis of result obtained, it is important to improve the efficiency of the producers and thus to increase their profit by the search for effective means of pest control and the reinforcement of producer’s technical framing. Key words: efficiency, stochastic frontier analysis, translog function, Cobb-Douglas function, Solanum macrocarpon

Microstructural evolution and characterization of super-induced MgO composite on zinc-rich coatings

The effect of Zn-MgO deposition prepared through direct electrolytic co-deposition on mild steel was studied.The experiment was conducted at current density between 0.5 and 1 A/cm−2. The morphologies of the coated surfaces were characterized using Atomic Force Microscope (AFM), high resolution Nikon Optical Microscope (OPM) and Scanning Electron Microscopy attached with Energy Dispersive Spectrometer (SEM/EDX). The corrosion behavior was studied using linear potentiodynamic polarization method in 3.5% simulated environment. The phase change was evaluated using X-ray Diffractogram (XRD). The microhardness characteristics of the obtained deposits were analyzed with dura scan hardness tester. The stability of the ceramic composite was determined using heat-treatment processes at 200 oC for 4 h. The results show that the structural behavior and corrosion resistance of the coating is dependent on the composite induced particulate and applied current density. It is found that increasing MgO contents beyond optimum level does not cause increase in microhardness progression. A decrease in applied current maximally influences the deposit adhesion characteristics. The enhanced thermal stability of 236.4 HVN for Zn- 20MgO at 0.5 A/cm2 alloy and increase corrosion behavior was thus attributed to its chemical composition, phase content and the synergistic effect of Zn and MgO on the carbon steel

Development of a TQM-based Framework for Product Infant Failure Assessment

Product infant failures have been traced to the product development and production stage. Researchers and practitioners have opined that total quality management (TQM) can be used to properly managed these failures. While their suggestions have helped in this regard, there is limited information on how to scientifically aggregate criteria that can be used to specifically identify the most suitable TQM technique for product infant failure improvement, especially at the development stage. Hence, this study proposes a fuzzy-based multi-criteria framework for this problem. The framework uses intuitionistic fuzzy set to handle vague and imprecise judgment and Vlsekriterijumska Optimizacija I Kompromisno Resenje (VIKOR) to rank selected TQM techniques.  Real-world data sets were used to evaluate the framework performance, while TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) was used to validate the framework performance. Based on the results obtained, the IFWG-VIKOR and TOPSIS methods rank the most and least suitable TQM practices as TM4 and TM11, respectively. The framework can be used to provides insights into the management of techniques that can address infant product failure issues at the early stage of product development.

Effect of Avogadro Oil as Corrosion Inhibitor of Thermally Pre-aged Al-Si-Mg Alloy in Sodium Chloride Solution

The corrosion inhibition of thermally pre-aged Aluminium-Silicon-Magnesium (Al-Si-Mg) alloy in 3.5 % NaCl solution with natural Avogadro oil of varying concentrations has been studied using linear polarization techniques. From the results obtained, the corrosion rate decreased with an increase in Avogadro oil concentration. An inhibitor efficiency of 46.7, 58 and 71 % were obtained at 1.5, 3.0, 4.5 g/v Avogadro oil addition in a 3.5 % NaCl solution respectively for the conventional alloy. Results from the linear polarization technique indicate a higher potential value with an increase in the polarization resistance (Rp) and lower current density in the inhibited samples than the uninhibited Al-Si-Mg alloy as obtained from the Tafel plot extrapolation. There exist some levels of correlation in the inhibitor efficiency between the conventional and the thermally pre-aged Al-Si-Mg alloy/Avogadro oil in 3.5 % NaCl solution

Study of Influence of Zinc Plated Mild Steel Deterioration in Seawater Environment

The corrosion resistance of electrolytic zinc-coating on mild steel in seawater was investigated. Mild steel samples were zinc electroplated at voltage varied (0.6, 0.8, 1.0, 1.5 V) and for plating time also varied (20, 30, 40, 50, 60 minutes). Focused ion-beam scanning electron microscopy was used to observe the surface morphology of the plated surface. The visual observation of plated samples revealed that samples plated at 0.6 V for 20 and 60 minutes; 0.8 V for 30 minutes and 1.0 V for 40 minutes showed the best physical properties such as colour, brightness, fineness, streak and strong adhesion. The plated samples were then subjected to seawater environment for 30 days. The electro-potentials mV (SCE) was measured daily. Weight loss was determined at intervals of five days for the duration of the exposure period. Experimental result showed little corrosion attack on the zinc-plated samples on the fifteenth and twenty-fifth day’s exposure. The severity of attack decreases with increasing weight of zinc coated on substrate. Significant increases in the corrosion resistance were achieved for the plated samples compared with that of the substrate. The pH of the seawater became more alkaline at the end of the thirty days test

Effects of bone particle on the properties and microstructure of polypropylene/bone ash particulate composites

The effects of uncarbonized (fresh) and carbonized bone particles on the microstructure and properties of polypropylene composites have been studied. The addition of the bone particles ranges from 5 to 25 wt% in uncarbonized and carbonized forms in the polypropylene matrix. The physical and mechanical properties were used as criteria for the evaluation of the composites. Microstructures of the composites were assessed with scanning electron microscopy (SEM/EDS). The results revealed that the addition of carbonized bone particles reinforcement has superior properties than uncarbonized bone particles composite based materials with an increase in the compressive strength, hardness values, tensile strength and flexural strength by 53%, 45% and 35% respectively, and a decrease in the % elongation and impact energy by 75% and 32%, respectively at 25 wt% carbonized bone, with 28% increase in tensile strength at 15 wt% carbonized bone addition. The increase in strength and hardness values was attributed to the distribution of hard phases of bone particles in the ductile polypropylene matrix