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Rekhila G.,University of Science and Technology Houari Boumediene | Bessekhouad Y.,University of Science and Technology Houari Boumediene | Bessekhouad Y.,National Veterinary School of Algiers | Trari M.,University of Science and Technology Houari Boumediene
International Journal of Hydrogen Energy | Year: 2013

The spinel type compounds represent a new family of photocatalysts that can be used as photoelectrodes capable to produce hydrogen under visible light. In the current study, the NiFe2O4 spinel, which is prepared by the sol-gel method, is investigated as a possible candidate, and the structure, opto-electronic, electrochemical and photoactive properties are characterized. NiFe2O4 exhibits a p-type semiconductor behaviour with a hole mobility of 1.57 × 10-10 cm2 (V s)-1. The conduction at 300 K is found to take place by electron-hopping mechanism with an activation energy ΔEσ1=0.12ev, and the lowest optical transition is observed at 1.56 eV. The valence band is of cationic character and derives from the Ni-3d orbital (5.23 eV/vacuum). On the other hand, the conduction band, ECB = -1.62 VSCE, is located above the H2O/H2 potential (-0.98 V SCE), which allows for the H2-evolution under illumination. The effects of NiFe2O4 amount, pH level and S2O3 2- concentration are optimized. Under these ideal conditions, the rate of H2 involvement attains 0.68 × 10-3 mL mg-1 min-1 with a quantum efficiency η(H2) = 0.53%. Electrochemical impedance spectroscopy is also used to model the photosystem and an electronic equivalent circuit is proposed. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Denis S.,IRD Montpellier | Carla M.,New University of Lisbon | Khatima A.-O.,National Veterinary School of Algiers
International Journal for Parasitology: Drugs and Drug Resistance | Year: 2012

Leishmania drug resistance and particularly antimony resistance still continues to emerge in different part of the world. Because visceral and cutaneous leishmaniasis are transmitted in foci with zoonotic or anthroponotic life-cycles, the link between chemotherapeutic resistance and the selection for drug resistance, through drug consumption, cannot be as obvious for all forms of leishmaniasis. The underlying factors that trigger the selection of antimony resistant parasites are poorly studied in regard to environmental aspects. Recently, a correlation between the emergence of antimony unresponsiveness in India and water arsenic contamination has been raised. The presence of some yet unidentified environmental factors driving the selection of antimony resistant Leishmania populations in a zoonotic context of leishmaniasis is also currently questioned. The identification of key molecules involved in the selection of antimony resistance and their importance in the selective process have to be re-evaluated in light of the environment were all the hosts of Leishmania (mammalian and arthropod) evolved. These new insights will help to (i) address the risk of therapeutic failure associated with the emergence of drug-resistance and (ii) propose new therapeutic protocols to aim at reducing the risk of resistance in endemic areas. © 2012.

Helaili N.,University of Science and Technology Houari Boumediene | Bessekhouad Y.,University of Science and Technology Houari Boumediene | Bessekhouad Y.,National Veterinary School of Algiers | Bouguelia A.,University of Science and Technology Houari Boumediene | Trari M.,University of Science and Technology Houari Boumediene
Solar Energy | Year: 2010

The p-Cu2O/n-ZnO system is studied for its potential use as a photoactive heterojunction able to highly perform under visible light. The main application deals with the degradation of organic dyes such as Orange II and the effects of Cu2O amount, Orange II concentration and light intensity are investigated. Results show that the kinetics of degradation follows a pseudo-first order and the optimum sensitization effect is obtained using a 70% concentration of Cu2O. The degradation rate reaches its maximum (Rinitial = 22.45 × 10-2 mg l-1 min-1) at 15 mg l-1 of Orange II. The effect of the irradiation intensity is also investigated taking the electrical energy consumption per order of magnitude (EE/O) as a figure of merit. The highest efficiency is obtained at an irradiation intensity of ∼122 × 10-5 kW with kOBS = 14.97 × 10-3 min-1 and EE/O, which corresponds to 12.54 kW h m-3 of energy consumption. This heterojunction allows a ∼25% saving of electrical energy in comparison to the p-Cu2O/n-TiO2 system, demonstrating the important role of the collector. © 2010 Elsevier Ltd. All rights reserved.

Ait-Oudhia K.,National Veterinary School of Algiers | Gazanion E.,IRD Montpellier | Vergnes B.,IRD Montpellier | Oury B.,IRD Montpellier | Sereno D.,MIVEGEC UM1 CNRS 5290 IRD 224
Parasitology Research | Year: 2011

Leishmania is the causative agent of various forms of leishmaniasis, a significant cause of morbidity and mortality. The clinical manifestations of the disease range from self-healing cutaneous and mucocutaneous skin ulcers to a fatal visceral form named visceral leishmaniasis or kala-azar. In the absence of any effective vaccine, the only means to treat and control leishmaniasis is affordable medication. The treatment choice is essentially directed by economic considerations; therefore, for a large majority of countries, chemotherapy relies only on the use of cheaper antimonial compounds. The emergence of antimonial therapy failure in India linked to proven parasite resistance has stressed questions about selective factors as well as transmission risk of drug resistance. Unfortunately, in most parts of the world, the frequency of parasite antimony resistance linked to treatment failure is unknown because of a lack of information on Leishmania antimony susceptibility. This information is crucial for addressing the risk of selection and transmission of drug-resistant parasites, particularly in areas where antimony is the only chemotherapeutic alternative. However, the poor knowledge about factors that favor selection of resistant parasites, the multiplicity of the agents that can play a role in the in vivo antileishmanial activity of antimony, and the lack of a standard protocol to diagnose and survey parasite resistance all contribute to insufficient monitoring of antimony resistance. In this review, we discuss on the factors potentially involved in the selection of antimony resistance in the field and discuss on the methods available for its diagnosis. © Springer-Verlag 2011.

da Cruz J.C.M.,Embrapa Goat and Sheep Research Center | Singh D.K.,Winston-Salem State University | Lamara A.,National Veterinary School of Algiers | Chebloune Y.,Joseph Fourier University
Viruses | Year: 2013

Zoonotic events of simian immunodeficiency virus (SIV) from non-human primates to humans have generated the acquired immunodeficiency syndrome (AIDS), one of the most devastating infectious disease of the last century with more than 30 million people dead and about 40.3 million people currently infected worldwide. Human immunodeficiency virus (HIV-1 and HIV-2), the two major viruses that cause AIDS in humans are retroviruses of the lentivirus genus. The genus includes arthritis-encephalitis virus (CAEV) and Maedi-Visna virus (MVV), and a heterogeneous group of viruses known as small ruminant lentiviruses (SRLVs), affecting goat and sheep. Lentivirus genome integrates into the host DNA, causing persistent infection associated with a remarkable diversity during viral replication. Direct evidence of mixed infections with these two closely related SRLVs was found in both sheep and goats. The evidence of a genetic continuum with caprine and ovine field isolates demonstrates the absence of an efficient species barrier preventing cross-species transmission. In dual-infected animals, persistent infections with both CAEV and MVV have been described, and viral chimeras have been detected. This not only complicates animal trade between countries but favors the risk that highly pathogenic variants may emerge as has already been observed in the past in Iceland and, more recently, in outbreaks with virulent strains in Spain. SRLVs affecting wildlife have already been identified, demonstrating the existence of emergent viruses adapted to new hosts. Viruses adapted to wildlife ruminants may acquire novel biopathological properties which may endanger not only the new host species but also domestic ruminants and humans. SRLVs infecting sheep and goats follow a genomic evolution similar to that observed in HIV or in other lentiviruses. Lentivirus genetic diversity and host factors leading to the establishment of naturally occurring virulent versus avirulent infections, in addition to the emergence of new strains, challenge every aspect of SRLV control measures for providing efficient tools to prevent the transmission of diseases between wild ungulates and livestock. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

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