50 research outputs found
Changes in volatile compounds and oil quality with the method of olive tree propagation and saline water irrigation
The main goal of this study was to investigate the effects of moderate saline water irrigation on the composition and quality of olive oil of the “Chemlali” olive cultivar in comparison to a control plot grown under rain-fed conditions from two methods of olive tree propagation (suckers and cuttings). The antioxidant compounds, oxidative stability and volatile compounds of virgin olive oil samples were determined and reported. The irrigation did not affect free acidity and peroxide value and specific ultraviolet absorbance (K232, K270). Whereas, fatty acid composition, oxidative stability, total phenol, total chlorophyll and carotenoid contents were affected by irrigation. Rain-fed virgin olive oils showed a statistically significant higher content of oleic and linoleic acids. However, olive oil samples obtained from fruit of irrigated trees from suckers had a higher content of (E)-2 hexenal (67.2%) and a higher content of total phenols (860 mg kg–1). Interestingly, more stable oil was obtained from moderate saline water irrigated trees from suckers compared to olives from cuttings
The response of young pistachio trees grown under saline conditions depends on the rootstock
-------------------------------------------------------------------------------------------------------------------------- To cite th is article / Pou r citer cet article Individual trunk cross-sectional area and growth of scion shoots were determined on all trees as well as proline and soluble sugar foliar contents. Results showed that tree growth was affected by both salinity and rootstock. Indeed, trees grafted on P. atlantica rootstock showed a slight early growth advantage compared with those having P. vera as rootstock. For all the treatments, the principal and axillaries shoot length, vegetative bud number and diameter of the trunk cross-sectional areas of stocks were higher on P. atlantica rootstock. On both rootstocks, the salinity at 5 dS/m stimulated the length and bud numbers of axillaries shoots and at 12 dS/m, the growth parameters declined significantly. In highly stressed plants budded on P. vera, proline and soluble sugars contents were higher than control all over the seasons. Keywords. P. vera -P. atlantica
XMCD studies and magnetic properties of ZnTe doped with Ti, Cr, Mn and Co
Using the full potential linear augmented plane wave (FP-LAPW) method as implemented in the WIEN2K code in connection with the Generalized Gradient Approximation (GGA). We study the magnetic properties of ZnTe doped with some transition metals elements. In addition, to the X-ray absorption spectra (XAS) and X-ray Magnetic circular dichroism (XMCD) calculations to compute the orbital and spin moments separately. Two principal examples will be given: The induced magnetic moments ZnTe of the light and heavy 3d elements (Ti, Cr and Mn, Co) can be determined by the XMCD sum rules analysis at the L2,3 edges. Moreover, it has been found that for the lighter 3d elements the spin-orbit splitting of the transitions 2P1/2 and 2P3/2 states reduces toward, which has a consequence that two excitations are coupled
Oil quality and aroma composition of 'Chemlali' olive trees (Olea europaea L.) under three irrigation regimes
The present work focused on the chemical composition of monovarietal virgin olive oil from the cultivar Chemlali cultivated in the South of Tunisia: sub-arid zone under three different irrigation regimes: stressed, moderate and well irrigation treatment with the restitution of 50, 75 and 100% of crop evapotranspiration (ETc), respectively. Quality characteristics (acidity and peroxide value) and chemical data (antioxidant compound, fatty acids volatile compounds and oxidative stability) were studied in addition to the pomological characteristic of olive fruit. Results show that there were significant differences observed in oil composition according to the irrigation regime applied. Total phenols, bitterness intensity and LOX products content showed the highest values for low irrigation regime, whereas polyunsaturated fatty acid and oxidative susceptibility values had highest values for olive oil from well irrigated trees. Analytic characteristic of fruits showed the highest values of pulp/stone ratios from olive trees irrigated by the highest amount of wate
The Ferromagnetic and half metallic behaviors of Fe- and Co- doped SnO2 within Local Density Approximation and Self-Interaction-Corrected
Using ab-initio calculation based on the Korringa-Kohn-Rostoker Coherent Potential Approximation (KKR-CPA) method in connection with the local density approximation without and within self-interaction-corrected (LDA and LDA-SIC), we represent a theoretical study of the SnO2 doped system with transition metals (TM) which are Iron (Fe) and Cobalt (Co). In this system, the stability of the ferromagnetic state compared with the spin-glass state is investigated by comparing their total energies. The Ferromagnetic and half metallic behaviors was observed and conformed with the local-moment-disordered (LMD) state energy for LDA (local density approximation) and LDA-SIC (local density approximation-self-interaction correction) approximation in [Sn0.95TM0.05(Fe or Co)]O2 . Based on mean field method, the Curie temperature is estimated. To explain the origin of magnetic behavior, we give information about total and atom projected density of states functions of Fe and Co elements and we propose a model which describes magnetic interaction in [Sn0.95TM0.05(Fe or Co)]O2
Composición química de aceites de oliva virgen de la variedad Chamlali en relación con el método de propagación del olivo
This paper reports for the first time a discrimination study based on the antioxidant compounds, oxidative stability and volatile compounds of virgin olive oil samples obtained from fruits of the main Tunisian olive cultivar (Chemlali) using two methods of olive tree propagation (suckers and cuttings). There were significant differences between the oils from the two methods. Olive oil samples obtained from the fruits of trees from suckers had a higher content of oleic acid (63.8%), higher contents of chlorophyll and carotenoids (3.01 mg/ kg and 1.9 mg/kg respectively), a higher content of (E)-2 hexenal (66.1%) and a higher content in total phenols (890 mg/kg). Interestingly, more stable oil was obtained from the olives from suckers compared to the olives from cuttings. These results can be used to discriminate and to characterize the Chemlali olive oils from each origin of olive tree.En este trabajo se presenta por primera vez un estudio de discriminación basado en compuestos antioxidantes, estabilidad oxidativa y compuestos volátiles de muestras de aceites de oliva virgen obtenidos de frutos de la principal variedad de aceitunas tunecinas (Chemlali) a partir de dos métodos de propagación del olivo (chupones y estaquillas herbáceas). Se han encontrado diferencias significativas entre los aceites obtenidos por los dos métodos. Las muestras de aceites de oliva obtenidas de frutos de árboles de chupones tenían una mayor proporción de ácido oleico (63,8%), un mayor contenido de clorofila y de carotenoides (3,01 mg/kg y 1,9 mg/kg, respectivamente), un mayor contenido de (E)-2 hexenal (66,1%) y un mayor contenido en fenoles totales (890 mg/kg). Curiosamente, el aceite más estable se ha obtenido de las aceitunas de árboles de chupones, en comparación con las aceitunas de árboles de estaquillas herbáceas. Estos resultados pueden ser utilizados para discriminar y caracterizar los aceites de oliva Chamlali según el origen del olivo
Dynamique de la conductance hydraulique chez l'olivier de table (Olea europaea L., cv Meski)
Hydraulic Conductance Dynamic in Olive Table Tree (Olea europaea L. cv Meski). Cette étude expose les effets de l'aménagement des pâturages par la digue filtrante sur la dynamique de la végétation. Dans les régions sahéliennes, de nombreuses techniques sont appliquées sur les sols pour la restauration des parcours dégradés. La digue filtrante s'intéresse particulièrement aux axes de drainage ou bas-fonds en dégradation. La méthode d'étude a consisté à évaluer l'impact des digues filtrantes par l'inventaire de la végétation, la mesure de la biomasse produite, et l'analyse chimique d'échantillons de fourrage et de sol. Ces observations ont été faites à la fois sur l'espace aménagé et sur un espace témoin représentatif en deux fois durant cinq ans. Les observations sur l'espace aménagé (stations d'observation d'un ha) ont été faites en fonction du gradient par rapport à la digue filtrante tandis que sur le témoin (station d'observation d'un ha), les mesures ont été homogénéisées sur l'ensemble de la parcelle. Les résultats obtenus des inventaires de végétation montrent un effet positif de l'aménagement sur la dynamique de la végétation qui se maintient après cinq années. Les effets concernent la composition floristique pour laquelle certaines espèces connaissent une amélioration. Il s'agit de Panicum laetum (+ 5,9% en 1999 et + 1,9% en 2003), Setaria pallide fusca (+ 2,4 à + 8,6%), Cassia obtusifolia (+ 13,6% à + 9,3%) et Zornia glochidiata (- 2,9% à + 1,7 %). Les espèces en régression sont surtout composées de Schoenefeldia gracilis (+ 1,7% à - 12%) et Microchloa indica (- 28,9% à - 12,1% entre 1999 et 2003). L'écart de recouvrement du sol entre la parcelle aménagée et le témoin a été de -0,4% en 1999 contre + 14,6% en 2003. La biomasse produite et la capacité de charge ont connu une expansion allant de 3,14 à 4,5 fois par rapport à l'espace non aménagé. Cependant, des suivis doivent encore être maintenus en associant surtout les effets de l'exploitation (fauche et pâture) pour mieux préciser l'efficacité et la durabilité de ces aménagements sur les zones pastorales en même temps que des stratégies sont définies au niveau village sur la gestion de ces espaces restaurés
On the Autocorrelation Properties of Truncated Maximum-Length Sequences and Their Effect on the Power Spectrum
Truncated maximum-length binary sequences are studied in this paper. The impact of truncation on their autocorrelation properties and power spectral density is investigated. Several new analytical results are given and validated through simulation. The first- and second-order statistics of the periodic autocorrelation function and the spectral peak amplitudes over the ensemble of all possible starting seeds are analyzed. Explicit bounds are found for the mean square of the periodic autocorrelation function. An analytical technique for evaluating the maximum spectral peak values is derived. As a case study, high data rate space links using LFSR randomizers are considered. Truncation may induce high peaks in the spectrum, requiring suitable margins to comply with power flux density constraints. The new results allow to analytically estimate the margin, providing useful information for the link desig
Impact of truncation on the statistical properties of LFSR sequences
This paper investigates some theoretical issues related with the truncation of maximum length sequences. It is shown that truncation can have a significant impact on the autocorrelation properties, mining the applicability of these sequences in practical applications. First and second order statistics for the autocorrelation function are considered, and some new relations are presented that simplify computation. As an example of practical impairment, we focus on space communication links and we consider the changes that occur in the transmitted waveform power spectral density when truncated sequences are used for data randomizatio