Mohammedi Z.,University of Mascara |
Atik F.,Abou Bekr Belkaid University Tlemcen
International Journal of Pharma and Bio Sciences | Year: 2011
Secondary metabolites of an arabo-saharan tree Tamarix aphylla (L.) Karst. Were extracted from dry powdered leaves with different solvents: aqueous methanol; aqueous ethanol, aqueous acetone and distilled water. Total phenolic content of the four extracts were determined by Folin Ciocalteu method and their antioxidant activity was assayed through in vitro radical scavenging activity using DPPH· assay. The results showed that mixture water-methanol was better than water-ethanol, wateracetone and water for extraction bioactive compounds in particularly total polyphenols from Tamarix aphylla leaves. The average total phenol content of aqueous methanol extract was 262.26mg GAE/100g dry weight lyophilized extract. However, all extracts were free-radical inhibitors but aqueous acetone extract was more potent than aqueous ethanol extract and two others extracts. In order of effectiveness (EC50), the potent inhibitors were from water-acetone extract (0.080mg/ml) > water-ethanol extract (0.140mg/ml)>water extract (0.173mg/ml)> Water-methanol (0.911mg/ml).
Benyoucef M.,University of Mascara |
Meister C.,Natural History Museum of Geneva
Cretaceous Research | Year: 2015
Fifteen stratigraphic sections located in different parts of the Guir basin (Southwest Algeria) have been measured bed-by-bed and sampled in great detail, to study the stratigraphy, describe and interpret the facies and characterize the depositional environment of the Cenomanian-Turonian succession. Based on their stratigraphic ranges, lithofacies, regional distributions and depositional settings, the Cenomanian-Turonian succession is subdivided into three lithostratigraphic formations that are bounded by a regional scale discontinuity: the "Grès rouges" Formation attributed to the lower Cenomanian; the "Marnes à gypse inférieures" Formation assigned to the lower-middle Cenomanian and the "Calcaires de Sidi Mohamed Ben Bouziane" Formation placed in the upper Cenomanian-lower Turonian. Analyses of litho-, bio-, and microfacies resulted in the recognition of 25 facies types for this succession. These facies types have been grouped into seven facies associations (AF1 to AF7). The facies represented range from clastic, to evaporitic to carbonate, and were deposited in four major depositional environments: fluvial, siliciclastic costal, sabkha and homoclinal carbonate ramp settings. The main factors controlling depositional environments were eustatic sea-level fluctuations combined with environmental influences such as autochthonous carbonate productivity and siliciclastic supply. © 2014 Elsevier Ltd.
Ghelamallah M.,University of Mascara |
Granger P.,CNRS Laboratory of Catalysis and Solid State Chemistry
Fuel | Year: 2012
The dry reforming of CH 4 by CO 2 has been studied, between 300 and 900°C, over monometallic platinum and rhodium based catalysts supported on α-Al 2O 3 doped with La 2O 3 and BaO. Those catalysts were prepared by conventional wet impregnation and characterized by various physicochemical techniques (nitrogen adsorption, X-ray diffraction, XPS analysis and H 2- temperature-programmed experiments). It was found that Pt and Rh incorporation leads to different types of interactions with La and Ba-modified α-Al 2O 3. As observed, Pt would preferentially interact with Ba inducing an inhibiting effect on the rate of the CH 4/CO 2 reaction reflected by a significant increase in the apparent activation energy. On the other hand, the preferential interaction of Rh with lanthanum oxide after Ba incorporation leads to the preservation of the catalyst activity. Such changes in catalytic properties have been discussed in the light of surface characterization and previous mechanistic information related to the occurrence of a bi-functional mechanism involving the metal/support interface. © 2012 Elsevier Ltd. All rights reserved.
Bachir R.G.,University of Mascara |
Benali M.,University Djilali Liabes
Asian Pacific Journal of Tropical Biomedicine | Year: 2012
Objective: To examine the in vitro antimicrobial activities of essential oil of the leaves of Eucalyptus globulus (E. globulus). Methods: The essential oils of this plant were obtained by the hydrodistillation method. The inhibitory effects of this essential oil were tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by using agar disc diffusion and dilution broth methods. Results: The results obtained showed that essential oil of the leaves of E. globulus has antimicrobial activity against gram negative bacteria (E. coli) as well as gram positive bacteria (S. aureus). Conclusions: The encouraging results indicate the essential oil of E. globulus leaves might be exploited as natural antibiotic for the treatment of several infectious diseases caused by these two germs, and could be useful in understanding the relations between traditional cures and current medicines. © 2012 Asian Pacific Tropical Biomedical Magazine.
Fergoug T.,University of Mascara |
Bouhadda Y.,University of Mascara
Fuel | Year: 2014
1H & 13C NMR experiments were conducted to investigate the structural parameters of asphaltene molecules derived from Algerian Hassi Messaoud oil field. By coupling known aromatic and aliphatic analyses with alpha carbon abundance evaluation, the asphaltene of this field was found to contain approximately seven condense aromatic rings attached with short aliphatic chains of 4-6 carbons. The spectral analysis also suggests the aromatic fragments to contain an average of one pendant aliphatic chain per hexagon. © 2013 Elsevier Ltd. All rights reserved.
Chergui M.I.,University of Mascara
Turkish Journal of Electrical Engineering and Computer Sciences | Year: 2016
This paper deals with two different techniques of vector method-related direct torque control: The conventional (DTC-C) and the space vector modulation (DTC-SVM). Both are used for an induction motor in the photovoltaic pumping system. Based on instantaneous space vector theory, and with an optimal selection of the space voltage vectors in each sampling period, the DTC achieves effective control of the stator flux and torque. Consequently, the number of space voltage vectors and switching frequency directly influence the performance of the DTC control system, giving an advantage for a rotor position free control system. In order to improve the efficiency of the photovoltaic generator, maximum power point tracking techniques are investigated. The incremental conductance (Inc-MPPT) algorithm is applied to the system with variable temperature and irradiance conditions. DTC associated with Inc-MPPT allows the system to operate at its maximum power, with a good performance and fast response without overshoot. Comparing the two control techniques of torque, it appears that DTC-SVM optimizes not only the photovoltaic conversion efficiency but also the losses in the induction motor, and it improves the water flow quantity. © TÜBİTAK.
Mohammedi Z.,University of Mascara
Research Journal of Medicinal Plant | Year: 2016
Several of experimental studies and molecular investigations highlight the power of herbs to evidence-based medicine. In Algeria, a number of medicinal plants have been studied for the treatment of diabetes such as Atriplex halimus L., xerohallophyte species, growing in arid and subarid areas, known for its hypoglycemic activity and widely used by the local population as remedy to treat diabetes mellitus. The objective of this review is to give value to this important traditional medicinal plant as antidiabetic, to set other biological and nutritional properties and its importance as resistant shrubs and good forage in severe environmental conditions. © 2016 Academic Journals Inc.
Mechab I.,University of Mascara |
Mechab B.,University Djilali Liabes |
Benaissa S.,University Djilali Liabes
Composites Part B: Engineering | Year: 2013
This study presents the analytical solutions of static and dynamic analysis of functionally graded plates using Four-variable refined plate theory. The objective of this paper is to develop a model to employ the new function ψ(z) for analysis the static and dynamic of functionally graded plates. The validity of the theory is shown by comparing the present results with those of the classical, the first-order, and the other higher-order theories. The results are in good agreement with solution of Reddy. © 2012 Elsevier Ltd. All rights reserved.
Bouderba B.,University Djilali Liabes |
Houari M.S.A.,University Djilali Liabes |
Houari M.S.A.,University of Mascara |
Tounsi A.,University Djilali Liabes
Steel and Composite Structures | Year: 2013
The present work deals with the thermomechanical bending response of functionally graded plates resting on Winkler-Pasternak elastic foundations. Theoretical formulations are based on a recently developed refined trigonometric shear deformation theory (RTSDT). The theory accounts for trigonometric distribution of transverse shear stress, and satisfies the free transverse shear stress conditions on the top and bottom surfaces of the plate without using shear correction factor. Unlike the conventional trigonometric shear deformation theory, the present refined trigonometric shear deformation theory contains only four unknowns as against five in case of other shear deformation theories. The material properties of the functionally graded plates are assumed to vary continuously through the thickness, according to a simple power law distribution of the volume fraction of the constituents. The elastic foundation is modelled as twoparameter Pasternak foundation. The results of the shear deformation theories are compared together. Numerical examples cover the effects of the gradient index, plate aspect ratio, side-to-thickness ratio and elastic foundation parameters on the thermomechanical behavior of functionally graded plates. It can be concluded that the proposed theory is accurate and efficient in predicting the thermomechanical bending response of functionally graded plates.
Khalfi Y.,University Djilali Liabes |
Houari M.S.A.,University Djilali Liabes |
Houari M.S.A.,University of Mascara |
Tounsi A.,University Djilali Liabes
International Journal of Computational Methods | Year: 2014
A refined and simple shear deformation theory for thermal buckling of solar functionally graded plate (SFGP) resting on two-parameter Pasternak's foundations is developed. The displacement field is chosen based on assumptions that the in-plane and transverse displacements consist of bending and shear components, and the shear components of in-plane displacements give rise to the parabolic variation of shear strain through the thickness in such a way that shear stresses vanish on the plate surfaces. Therefore, there is no need to use shear correction factor. The number of independent unknowns of present theory is four, as against five in other shear deformation theories. It is assumed that the material properties of the plate vary through the thickness of the plate as a power function. The neutral surface position for such plate is determined, and the present plate theory based on exact neutral surface position is employed to derive the governing stability equations. The nonlinear strain-displacement relations are also taken into consideration. The boundary conditions for the plate are assumed to be simply supported in all edges. Closed-form solutions are presented to calculate the critical buckling temperature, which are useful for engineers in design. The effects of the foundation parameters, plate dimensions, and power law index are presented comprehensively for the thermal buckling of solar functionally graded plates. © 2014 World Scientific Publishing Company.