Laboratoire Materiaux

Al Marsá, Tunisia

Laboratoire Materiaux

Al Marsá, Tunisia

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Baazaoui M.,UR Physico Chimie des Materiaux Solides | Baazaoui M.,University of Carthage | Bejaoui I.,UR Physico Chimie des Materiaux Solides | Bejaoui I.,University of Carthage | And 4 more authors.
RSC Advances | Year: 2016

New cationic amphiphilic β-cyclodextrins (β-CD) were investigated for their surface-active properties and self-association. β-Cyclodextrin was mono- or per-substituted at its narrow rim by short (butyl) or long (dodecyl) aliphatic chains. The mono-substituted β-CDs are classical surfactants having a single hydrophobic tail and a single hydrophilic head; the per-substituted β-CDs have seven hydrophobic tails and seven hydrophilic heads. A comparative study of their surface-active properties at air/water and oil/water interfaces and of the formation of aggregates was achieved. All cationic β-CD surfactants show surface activity and self-assemble above a well-defined concentration referred to as the cmc because of the interactions between their hydrophobic tails. The inclusion of the alkyl chain inside the hydrophobic cavity did not cause other types of self-association. Though the main features of the surface-activity look similar to classical surfactants, such amphiphilic β-CDs show several specificities. The short-chained butyl derivatives behave as classical long-chained surfactants do. The head-tail interaction between the long dodecyl chain and the β-CD cavity of mono-substituted β-CD causes the formation of an intramolecular inclusion complex that weakens its hydrophobic character. The seven dodecyl chains of per-substituted β-CD tightly pack together, lowering the contact area with water and weakening their hydrophobic character. Part of the counterions of multi-charged per-substituted β-CD is associated as ion pairs with the cationic groups of the amphiphilic β-CD. A close analogy with the behavior of gemini surfactants is worth noticing. © The Royal Society of Chemistry 2016.


Benhammou A.,Laboratoire Materiaux | Benhammou A.,Cadi Ayyad University | El Hafiane Y.,Laboratoire Materiaux | Nibou L.,Laboratoire Materiaux | And 5 more authors.
Ceramics International | Year: 2013

The structural and morphological evolutions of cordierite-based ceramics produced from stevensite/andalusite mixture sintered from 1150 to 1350 °C were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical behavior was investigated by three-point bending and Brazilian tests. The elastic properties were evaluated using ultrasonic non-destructive testing (NDT). XRD results revealed that the main crystalline phase formed at 1300 and 1350 °C was cordierite with traces of mullite. A linear-elastic behavior followed by brittle fracture was observed in three-point bending test with the presence of multiple discontinuities. Flexural and diametral compression strength values of cordierite sintered at 1300 °C were 39.4±4 and 21.8±2 MPa, respectively. The elastic properties such as Young's modulus (38.7-45.1 GPa), shear modulus (17.90-19.42 GPa) and Poisson ratio (0.08-1.6) of cordierite-based ceramics produced at 1350 and 1300 °C were also determined. © 2012 Elsevier Ltd and Techna Group S.r.l.


Abourriche A.K.,Laboratoire Materiaux | Oumam M.,Equipe des Materiaux Thermostructuraux | Hannache H.,Equipe des Materiaux Thermostructuraux | Birot M.,CNRS Institute of Molecular Sciences | And 6 more authors.
Journal of Supercritical Fluids | Year: 2013

In the present work, the effect of solvent on the sub and supercritical extraction of the organic matter from Tarfaya's oil shales was studied. The experimental results revealed that the extraction yield obtained by the phenol is very high compared to that obtained by the toluene or without solvent. In addition, the solvent had a significant effect on the yield and the composition of the obtained oil. The analyses carried out on the recovered oils allowed us to establish that the phenol is a very efficient solvent for oil shale extraction, giving a better quality of the oils extracted containing a large proportion of maltenes and aromatics compounds and fewer amounts of sulphur and paraffin compounds. © 2013 Elsevier B.V. All rights reserved.


Mammeri A.,CNRS Heterogeneous Materials Study Group | Mammeri A.,Béchar University | Mammeri A.,Laboratoire Materiaux | Ulmet L.,CNRS Heterogeneous Materials Study Group | And 2 more authors.
International Journal of Pavement Engineering | Year: 2015

This study aims to experimentally validate a 2D finite element model (FEM) in the transient thermal state of a multilayer pavement structure at each given depth. Data model inputs include 15-min values for solar radiation, air temperature and dew temperature, as well as daily values of wind speed obtained from the GEMH-Egletons Laboratory's weather station. This FEM highlights the importance of solar radiation and night-time cooling parameters. A comparison of numerical and experimental results indicates that night-time cooling, despite being often neglected in the literature, is a key parameter for a good surface temperature model, particularly in an arid zone. Also a parameter analysis of this model with various thermal parameters has been made in order to evaluate sensitivity and the main input parameters. The pavement surface is subjected to the strongest temperature variation; hence a good surface temperature assessment provides a key factor for further thermal cracking modelling. © 2014 Taylor & Francis.


Laiarinandrasana L.,MINES ParisTech Center of materials | Devilliers C.,MINES ParisTech Center of materials | Devilliers C.,Veolia | Oberti S.,Veolia | And 3 more authors.
International Journal of Pressure Vessels and Piping | Year: 2011

In order to characterize the mechanical behavior of HDPE pipes, the ASTM D 2290-04 standard recommends carrying out tensile tests on notched rings, cut out from the pipe. This very simple test is also utilized to investigate the aging effect of the pipe by determining the strain at failure. Comparison between full ring and notched ring mechanical responses are discussed. Constitutive modeling including strain rate effects was performed by finite element analysis. This allowed a better understanding of the stress state in the cross section perpendicular to the loading direction. Additionally, the influence of a thin layer of oxidized HDPE in the inner wall of the ring was studied in the light of the finite element results. © 2010 Elsevier Ltd.


Ouerdane A.,University of Khemis Miliana | Ouerdane A.,Laboratoire Materiaux | Hachoun Z.,University of Khemis Miliana
IOP Conference Series: Materials Science and Engineering | Year: 2016

The knowledge of influence of nitrogen on optical transition energies in InGaAsN Quantum Wells (QWs) or Quantum Dots (QDs) structures is very important due to the possibility of adjustment of the optical transition energies to the telecommunication wavelength range when the system GaAsN is submitted to further indium elements giving rise to the quaternary alloys (In)GaAsN. We add a computational method in quantum mechanics to study the Schrodinger equation for one and many quantum wells configurations. The photoluminescence PL measurement obtained by simulated technique is used to predict the different lines and energy levels of our compound. The simulated results are followed by solving the coupled nonlinear rate equations describing the complex electric field and the carrier density in a simple model of the GaNxAs1-x or (In)GaAsN semiconductor laser. © Published under licence by IOP Publishing Ltd.


Bouyer F.,French Institute of Health and Medical Research | Moretto J.,French Institute of Health and Medical Research | Pertuit D.,Unite de Molecules dInteret Biologique | Szollosi A.,Unite de Molecules dInteret Biologique | And 4 more authors.
Journal of Inorganic Biochemistry | Year: 2012

In order to improve the pharmacological profile of the anticancer drug cisplatin, several new acridine-based tethered (ethane-1,2-diamine)platinum(II) complexes connected by a polymethylene chain were synthetized. Activity-structure relationship between amide or ester functionalities was explored by changing acridine-9-carboxamide into acridine-9-carboxylate chromophore. The in vitro cytotoxicity of these new complexes was assessed in human colic HCT 116, SW480 and HT-29 cancer cell lines. Series of complexes bearing the acridine-9-carboxylate chromophore displayed higher cytotoxic effect than acridine-9-carboxamide complexes, with gradual effect according to the size of the polymethylene linker. © 2012 Elsevier Inc. All rights reserved.


Cherif A.,University of Sousse | Jomni S.,Laboratoire Materiaux | Hannachi R.,University of Sousse | Hannachi R.,Laboratoire Materiaux | And 2 more authors.
Physica B: Condensed Matter | Year: 2013

Porous silicon based Al/porous Si/p+-Si heterojunction with porous silicon layer was fabricated on low-resistivity crystalline silicon substrate by electrochemical anodisation. Measurements of the current-voltage I(V) characteristics and capacitance-voltage C(V) at various frequencies were used for the investigation of the electrical properties of this heterojunction. The forward bias I(V) dependencies exhibited a high value of the quality factor close to 7. This was attributed to the existence of interfacial layer and interface states which cause the forward I(V) characteristic not to obey the ideal Schottky diode characteristic. Therefore, it was demonstrated that the current has a square root dependence on the forward bias and it was governed by the Richardson-Schottky conduction mechanism. Furthermore, an ideality factor near the unity has been obtained in the reverse current and the I(V) characteristics were governed by the porous Si/Si heterojunction. The C(V) measurement was performed at different frequencies and revealed that the capacitance behavior was typical of material with interface states. The density of interface states was found to vary from 2×1010 eV -1cm-2 to 1.1×1011 eV-1cm -2 as a function of the interface states energy level position in the band gap of the porous silicon. © 2012 Elsevier B.V.


Virginie M.,Laboratoire Materiaux | Courson C.,Laboratoire Materiaux | Kiennemann A.,Laboratoire Materiaux
Comptes Rendus Chimie | Year: 2010

Tar produced during biomass steam reforming is a complex mixture of single to multiple ring aromatic compounds and it is necessary to eliminate them in order to prevent any condensation-polymerisation problem. Tar steam reforming leads to additional hydrogen that improves gas production. Previous works have shown that olivine was active in tar removal during biomass gasification and the iron distribution into the mineral different phases has a real influence on its efficiency. A Fe/olivine catalytic system has been designed to study tar steam reforming. This work presents the Fe/olivine catalyst characterizations (XRD, Mössbauer, TPR) and compares the Fe/olivine and olivine reactivity in toluene steam reforming, a tar model molecule. At 850 °C, an important conversion (95%) was observed for Fe/olivine during 7 h. The strong interaction between iron and olivine, and the equilibrium between Fe0/Fe II/FeIII seem to be responsible of the catalyst activity and stability in toluene steam reforming. © 2010 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.


Saghrouni H.,University of Sousse | Hannachi R.,University of Sousse | Jomni S.,Laboratoire Materiaux | Beji L.,University of Sousse
Physica B: Condensed Matter | Year: 2013

The electrical properties of Au/n+-GaAs and Au/n-porous GaAs metal-semiconductor structures were investigated using room temperature current-voltage I(V) and capacitance-voltage C(V) measurements. The electrical parameters of these structures such as ideality factor, barrier height potential, series resistance have been calculated. The obtained parameters of Au/n-porous GaAs structure were discussed and compared to those of Au/n +-GaAs structure. The series resistances and ideality factors of the two structures were seen to have approximately the same values. Furthermore, the shunt resistance and the barrier height potential values for the Au/n-porous GaAs structure were found to be different than the ones of Au/n+-GaAs structure. Furthermore the two structures showed a non-ideal I(V) behavior with an ideality factor greater than unity. Such non ideal behavior was suggested to be due to the existence of high density of trap and the forward I(V) characteristics which were governed by space charge limited conductivity, characterized by single and exponential trapping levels in both structures (SCLC). A model based upon TFE tunneling of carriers at reverse current was used to explain the non-saturation of reverse current of the structures. The high frequency C(V) characteristics of the structure reveal the presence of an anomalous behavior at the forward bias. Though the capacitance reaches a peak, it remarkably decreases with an increasing bias voltage suggested by the presence of interface states. Furthermore, the energy distribution of interface density in the structures was determined by the forward bias C(V) measurement as well as using ideality factor and barrier height potential values obtained from forward bias I(V) and reverse bias C-2(V) characteristics, respectively. An estimated energy band diagram for the Au/n+-GaAs and Au/n-porous GaAs structures are presented. © 2013 Elsevier B.V.

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