Propriétés structurales, optiques et électriques des couches minces de TiO2 dopé Cu obtenues par voie Sol-gel

Des couches minces de TiO<sub>2</sub> dope au cuivre ont ete preparees par la methode Sol-Gel et deposees selon le procede dip-coating sur des substrats en verre. Les proprietes structurales, optiques et electriques des echantillons monocouches dopes 0, 3 et 7 % at. cuivre ont ete analysees par diffraction des rayons X (DRX), microscopie a force atomique (AFM), la spectroscopie ellipsometrique (SE) et spectroscopie UV-Visible. La structure des films est celle d¡¦une phase anatase avec une orientation preferentielle suivant l¡¦axe (101). La transmittance est de l¡¦ordre de 75 % dans le visible et l¡¦energie de la bande optique interdite varie de 3,3 a 2,97 eV. Les valeurs de l¡¦indice de refraction et de la densite de remplissage augmentent avec l¡¦augmentation du dopage en cuivre qui se situe dans l¡¦intervalle 0 a 7 % at. La caracterisation  electrique, realisee a l'aide de la technique de deux pointes, a donne une conductivite electrique maximale de 1,29 (ƒÇcm)-1 obtenue pour le film dope a 7 % Cu.Mots-cles : TiO<sub>2</sub>, anatase, indice de refraction, gap optique, sol-gel

Estimation of Properties of Liquid-Vapor Mixture of Some Refrigerants at High Pressure for Solar-Photovoltaic Refrigeration

Abstract. In this work, a hybrid method based on neural network and particle swarm optimization is applied to literature data to develop and validate a model that can predict with precision vapor-liquid equilibrium data for the binary systems (hexafluoroethane (R116(1)), 1,1,1,2-tetrafluoroethane (R134a) and R1234ze) . ANN was used for modelling the non-linear process. The PSO was used for two purposes: replacing the standard back propagation in training the ANN and optimizing the process. The training and validation strategy has been focused on the use of a validation agreement vector, determined from linear regression analysis of the predicted versus experimental outputs, as an indication of the predictive ability of the neural network model. Statistical analysis of the predictability of the optimized neural network model shows excellent agreement with experimental data (coefficient of correlation equal to 0.998). Furthermore, the comparison in terms of average relative deviation (AARD%) between, the predicted results for the whole temperature and pressure range shows that the ANN-PSO model can predict far better the mixture properties than cubic equations of state

Removal of antibiotics from aqueous solution by bioadsorbant

In this study, dehydrated wheat bran, which is a natural product grows in the north of Algeria has been used as bioadsorbant for antibiotics removal from aqueous solution. Experimental data showed that the sorption of Tylosin increased with increasing the amount of adsorbent and decreased at high temperature. ∆H◦ and ∆S◦ were calculated from the slope and intercept of plots of ln(kd) versus 1/T, the adsorption process was found to be exothermic and more favourable at low temperature

Unravelling the mechanisms that determine the uptake and metabolism of magnetic single and multicore nanoparticles in a Xenopus laevis model.

Multicore superparamagnetic nanoparticles have been proposed as ideal tools for some biomedical applications because of their high magnetic moment per particle, high specific surface area and long term colloidal stability. Through controlled aggregation and packing of magnetic cores it is possible to obtain not only single-core but also multicore and hollow spheres with internal voids. In this work, we compare toxicological properties of single and multicore nanoparticles. Both types of particles showed moderate in vitro toxicity (MTT assay) tested in Hep G2 (human hepatocellular carcinoma) and Caco-2 (human colorectal adenocarcinoma) cells. The influence of surface chemistry in their biological behavior was also studied after functionalization with O,O′-bis(2-aminoethyl) PEG (2000 Da). For the first time, these nanoparticles were evaluated in a Xenopus laevis model studying their whole organism toxicity and their impact upon iron metabolism. The degree of activation of the metabolic pathway depends on the size and surface charge of the nanoparticles which determine their uptake. The results also highlight the potential of Xenopus laevis model bridging the gap between in vitro cell-based assays and rodent models for toxicity assessment to develop effective nanoparticles for biomedical applications

Application of multilayer perceptron for prediction of the rat acute toxicity of insecticides

International audienceWith the growing number of insecticides that can potentially contaminate the environment, the determination of their acute mammalian toxicity is of prime importance in risk assessment. Chemoinformatics presents an alternative to animal testing because laboratory tests are costly in time and money and actively opposed by animal rights activists. In this work, the Quantitative Structure-Toxicity Relationship (QSTR) model established by using the artificial neural network (ANN) has been used for estimating the acute oral toxicity (LD50) of these insecticides to male rats. The 123 insecticides of the training set and the sixteen insecticides of external testing set have been described by means of using molecular descriptors. The QSTR model was validated internally and externally. A good results (Q2 =0.96 and Q2ext =0.95) were obtained. The prediction results are in good agreement with the experimental values of LD50. © 2017 The Authors. Published by Elsevier Ltd

New approach of the fouling process modeling in tangential filtration on cake

International audienceThis work developed a new theoretical approach for modeling the membrane cross-flow filtration and described the importance of surface energy in the fouling process. In the case of zeta potential membranes, the cake formation results from surface phenomena caused by various interactions at the molecular and the macroscopic level, and is characterized by the surface energy resulting from the action of both gravitational and mechanical forces. The results of the experimental application of the new model revealed that the surface phenomena and the surface forces are the major factors in the fouling process. The new model had undergone various statistical tests to determine its performances and for its comparison with existing models used in wastewater or in drinking water treatment. The considered statistical parameters were the absolute relative error, squared correlation coefficient, the error probability of the experimental points, the distribution function and the correlation coefficient. In this study, two important parameters namely the fouling power Ψ and the overall surface energy γ have been developed; they constituted the contribution of this study in the understanding of the mechanism of membrane fouling. The obtained results showed the impact of the surface interactions, especially at particle wall of the filtering membrane. The level forming the deposit fouling demonstrated that the fouling process from zeta potential membrane is relatively intrinsic from the quantity of surface energy, the characteristic of membrane and the conditions of filtration. © 2017 Desalination Publications. All rights reserved

TiO2 waveguides thin films prepared by sol-gel method on glass substrates with and without ZnO underlayer

TiO2 thin films have been deposited on glass substrates with and without ZnO underlayer by sol-gel dip coating process. XRD patterns show the formation of anatase phase with the diffraction lines (1 0 1) and (2 0 0) in TiO2/glass sample. In TiO2/(ZnO/glass) sample, TiO2 is composed of anatase phase with the diffraction line (2 0 0) but the diffraction peaks of ZnO wurtzite are also well-defined. The determination of the refractive index and the thickness of the waveguiding layers has been performed by m-lines spectroscopy. The thickness of TiO2 thin films deduced by Rutheford Backscattering Geometry (RBS) agrees well with that obtained by m-lines spectroscopy. TiO2/glass sample exhibits one guided TE0 and TM0 polarized modes. In TiO2/(ZnO/glass) sample, only, TE0 single mode has been excited due to cutoff condition

Adsorptive removal of amoxicillin from wastewater using wheat grains: equilibrium, kinetic, thermodynamic studies and mass transfer

International audienceWheat grains are natural products which grow in the north of Algeria. In this study, they were used as adsorbent to remove amoxicillin antibiotic from wastewater. Adsorption isotherm of amoxicillin on both crude and modified wheat grains with 20% tartaric acid was investigated in batch tests. A model was developed regarding both the kinetic partitioning and the mechanism governing the forward transfer of amoxicillin. Results were interpreted in terms of a two-film theory for flat interface. The percentage of maximum adsorption capacity of amoxicillin was found to be 84% for the following optimal conditions: amoxicillin concentration of 4 mg/L, 5 min contact time, pH 7, temperature 25°C, and 0.24 g/L initial amoxicillin concentration and 150 μg particle size. The pseudo-first-order, pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data, and the rate constants were evaluated. It was found that the pseudo-second-order model provides the most adequate correlation of experimental data. The rate parameters of the intraparticle diffusion model for adsorption were also evaluated and to identify the adsorption mechanisms. The adsorption constants were evaluated by using the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D–R) adsorption isotherm models. The results showed that Temkin isotherm agrees with experimental data better than other adsorption models for the adsorption of amoxicillin. The thermodynamic parameters (ΔG, ΔH, and ΔS) showed that the process was feasible, spontaneous, and exothermic. © 2016 Balaban Desalination Publications. All rights reserved