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Tahar Dahame, Bachir Bentria, Houda Faraoun, Ali Benghia and A.H. Reshak

Abstract

We have calculated the electronic structure and physical properties of metal thiophosphate compounds InPS4 and AlPS 4by means of pseudopotential density functional theory (DFT) coupled with the modern theory of polarization. The targeted physical properties are first and second order optical properties as well as elastic, piezoelectric and electro-optic coefficients. Furthermore, population analysis is presented in order to evaluate the covalent-ionic character of the constituent bonds. The calculated elastic constants, refractive indices and second order optical coefficients of InPS4 are in good agreement with experimental values. With the absence of any theoretical or experimental physical properties of AlPS4, we predict that this compound has high piezoelectric coefficients with d14 = − 73.82 pm/V, d25 = − 10.96 pm/V and d36 = 28.19 pm/V.

Open access

Ali Brahmia, Nafaa Brinis and Tahar Nouar

Abstract

This work was conducted on 23 samples distributed between springs, wells and boreholes tapping the shallow and deep aquifer in the M’Daourouch-Drea area located in extreme northeast of Algeria. Ca2+, Mg2+, Na+, K+, Cl, SO4 2−, HCO3 and NO3 were analysed. The interpretation of the geological-geophysical data allowed us to highlight two aquifers. The first consists of conglomerates, sandstones, gravels, sands, marls, limestones, lacustrine and alluvial deposits varying in thickness from a few tens to a few hundred meters, representing Neogene-Quaternary filling of the studied basin. The second is more important localized in the cracked and karstified limestones of upper Cretaceous age; these limestones are outcropped on the flanks of the syncline and the borders of the basin. The first aquifer sometimes rests directly on the second which allows hydraulic communication between them. The hydogeochemical and statistical study, with the combination of numerous tools, indicates that the chemistry of groundwater in the M’Daourouch-Drea Plain is controlled both by the dissolution of the minerals of the evaporite formations and those of the carbonate formations.

Open access

Noureddine Merniz, Ali Tahar and Amine M. Benmehaia

Abstract

In the present study, time series for annual, monthly rainfall and number of rainy days per year were analysed to quantify spatial variability and temporal trends for 22 rainfall stations distributed in northeastern Algeria for the period 1978–2010. The Mann–Kendall test and the Sen’s slope estimator were applied to assess the significance and magnitude of the trend. The results showed that precipitation decreases spatially from North to South and from East to West. The application of the Mann–Kendall test (for 0.05% threshold) to the time series data showed that for annual precipitation, no station showed statistically significant trends, unlike the number of rainy days, where there was a significant negative trend in four stations (Jijel, Constantine, Oum El Bouaghi and Tébessa). For the monthly time series, significant positive trends were observed during the months of September in the coastal stations and July for the plateaus and southern Saharan Atlas stations, while significant negative trends were recorded during the months of February and March for the stations of the extreme East in the study area. These results revealed that for the period analysed, there was no significant climate change in northeastern Algeria but there is a seasonal delay having important agroecological implications.

Open access

Ouroud Fellah, Samir Hameurlaine, Noureddine Gherraf, Amar Zellagui, Tahar Ali, Abdennabi Abidi, Muhammed Altun, Ibrahim Demirtas and Ayse SahinYaglioglu

Abstract

The aerial parts of T. gallica collected from three different locations (arid, humid and semi-arid) were extracted using ethyl acetate. The crude extracts were subjected to phenolic appraisal and antiproliferative activity using ELISA and xCELLigence assays. The total phenolic and flavonoids were evaluated using appropriate techniques to give a yield of total phenolics ranging between 238.46 and 348.56 mg GAE (Gallic acid equivalent)/g dry weight extract. The flavonoids yield was found to vary from 36.6 to 103.14 mg QE (quercetin equivalent)/g dry weight extract. Moreover, the extracts were tested against rat brain tumor (C6) and human cervix carcinoma (HeLa) cell lines and displayed important differences in activity. These disparities highlighted the effect of climatic factors as quality determinants of secondary metabolites and therefore as a key control of the biological therapeutic effect.