Caractérisation physico-chimique des sables usés de la fonderie de Tiaret (Algérie), en vue de leur valorisation

Liés avec des argiles ou des résines, les sables de fonderie sont utilisés pour confectionner des moules et des noyaux dans lesquels sont coulés les métaux en fusion. Après l’opération de démoulage des pièces métalliques, une grande partie des sables est réutilisée sur place par régénération, tandis que les sables usés de fonderie résiduaires (nommés également « sables rejetés », « vieux sables » ou « sables brûlés ») doivent être éliminés. Ces déchets peuvent en effet présenter un risque pour l’homme et l’environnement. Ce travail se propose de caractériser les sables usés de la fonderie de Tiaret (Algérie), en vue de leur valorisation. Les sables étudiés et qui ne peuvent être réaffectés à l’activité de fonderie sont constitués de sabled’origine naturelle mélangé à des liants comme : l’argile, le silicate de soude, et la résine furanique.Mots-clés : sables usés de fonderie, déchets, environnement, développement durable, valorisation

Optimization of the Electronic Driver and Thermal Management of LEDs Lighting Powered by Solar PV

AbstractThe developments of efficient photovoltaic (PV) standalone systems requires advanced technology for PV cells and modules for high performance but also the application of components or loads of use with low energy consumption. In this context, the development of lighting systems using solar energy and electroluminescent components like high power white Light Emitting Diodes (LEDs) is proposed. The integration of the light fixture with the choice of best technologies for high efficiency LEDs and the design of an ultra-economic driver as the PWM driver permit us to obtain a high lighting efficiency. Our study has taken in consideration thermal aspect and the choice of adequate heat sinks for thermal management. This study, allowed us to consider both effects of thermal and electronic order and allowed us to the achievement of a high efficiency lighting powered by solar energy. With the implementation of the PWM electronic controls, we should reach an energy efficiency of the LEDs Driver from 85 to 90%

Al Concentration Effect on ZnO Based Thin Films: For Photovoltaic Applications

AbstractIn this work, we prepared aluminum-doped (Al) zinc oxide (ZnO) thin films using the sol-gel method, glass substrates have been used with zinc acetate as cations source and 2-methoxiethanol as solvent. The obtained experimental results show that the ZnO deposited films are relatively uniform. Optical measurements demonstrate that the deposited ZnO layers have a band gap of 3.26eV which is close to that of the monocrystalline ZnO, about 3.3eV. It was found that the roughness decreases by increasing the dopants concentration. Whatever the used substrate, transmission was observed between 75% and 99% for films deposited on ZnO:Al. Robust solar cells can be performed using from this study

Effet de la température sur la structure d’un puit quantique à base de GaN/AlxGa1-xN

Dans ce travail nous avons étudié des structures à puits quantique contraint à base de GaN/AlxGa1-xN. Nous avons étudié l’énergie de la bande interdite, le confinement des porteurs dans le puits et l’énergie de transition. L’étude est basée sur l’effet de la contrainte, l’épaisseur de la zone active, la concentration d’aluminium et l’injection des porteurs sur le gain optique. L’effet de la température sur la structure est pris en considération. Nous constatons que lorsque la densité de porteurs augmente de 6 à 8.1025m-3 le gain optique et la largeur spectrale augmentent de 25% et 1.3% respectivement. L’accroissement de la température décroit le gain optique. A partir de cette structure nous pouvons réaliser des composants optoélectroniques fiables et stables en température

Determination of VCSEL laser structures based InGaAsN / GaAs for fiber optic communication

The objective of this work is to study the electronic properties of GaInNAs semiconductor alloy in order to obtain quantum well GaInNAs/GaAs structures emitting at wavelengths around 1.3 μm to 1.55 μm, to use as active layers in laser diodes for fiber-optic communication. The incorporation of nitride in the GaInAs alloy gave very particular and attractive properties, the most important being the reduction of the energy of band gap. The anticrossing band model describes these properties; using this model, we determined the effect of nitrogen on the conduction band and the energy gap. We observed that the incorporation of nitrogen decreases the energy of the band gap and increases the emission wavelength. We found a compromise between the concentrations of In and N in order to determine the optimal structures for use in fiber-optic communication

mTOR is a selective effector of the radiation therapy response in androgen receptor-positive prostate cancer

Ionizing radiation (IR) is used frequently in the management of multiple tumor types, including both organ-confined and locally advanced prostate cancer (PCa). Enhancing tumor radiosensitivity could both reduce the amount of radiation required for definitive treatment and improve clinical outcome. Androgen suppression therapy improves clinical outcomes when combined with radiation therapy but is associated with significant acute and chronic toxicities; hence, there is a clear need for alternative means to increase the therapeutic window of radiotherapy. Herein, it is demonstrated that the mammalian target of rapamycin (mTOR) inhibitors rapamycin (sirolimus) and temsirolimus limit both hormone therapy (HT)-sensitive and castration-resistant PCa (CRPC) cell proliferation as single agents and have a profound radiosensitization effect when used in combination with IR. Importantly, the observed radiosensitization was influenced by the treatment schedule, in which adjuvant administration of mTOR inhibitors was most effective in limiting PCa cell population doubling. This schedule-dependent influence on in vitro treatment outcome was determined to be the result of relative effects on the cell cycle kinetics. Finally, adjuvant administration of either mTOR inhibitor tested after IR significantly decreased clonogenic cell survival of both HT-sensitive and CRPC cells compared with IR alone. Taken together, these data demonstrate that inhibition of mTOR confers a radiosensitization phenotype that is dependent on relative cell cycle kinetics and provide a foundation for clinical assessment

Alternative Splicing at a NAGNAG Acceptor Site as a Novel Phenotype Modifier

Approximately 30% of alleles causing genetic disorders generate premature termination codons (PTCs), which are usually associated with severe phenotypes. However, bypassing the deleterious stop codon can lead to a mild disease outcome. Splicing at NAGNAG tandem splice sites has been reported to result in insertion or deletion (indel) of three nucleotides. We identified such a mechanism as the origin of the mild to asymptomatic phenotype observed in cystic fibrosis patients homozygous for the E831X mutation (2623G>T) in the CFTR gene. Analyses performed on nasal epithelial cell mRNA detected three distinct isoforms, a considerably more complex situation than expected for a single nucleotide substitution. Structure-function studies and in silico analyses provided the first experimental evidence of an indel of a stop codon by alternative splicing at a NAGNAG acceptor site. In addition to contributing to proteome plasticity, alternative splicing at a NAGNAG tandem site can thus remove a disease-causing UAG stop codon. This molecular study reveals a naturally occurring mechanism where the effect of either modifier genes or epigenetic factors could be suspected. This finding is of importance for genetic counseling as well as for deciding appropriate therapeutic strategies