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1.
N. Zekri M. Schreiber R. Ouasti R. Bouamrane A. Brezini 《Zeitschrift für Physik B Condensed Matter》1995,99(3):381-386
A Kronig-Penney model with a constant electric field is used to study the transmission properties of a non-interacting electron one-dimensional (1D) ordered and disordered systems with uniformly distributed negative strengths of δ-function potentials (wells). In ordered systems we examine the origin of the jumps of the transmission coefficient and the short-range localization (occurring before the first jump) observed previously. For disordered wells, we also examine the phase-diagram in the energy-disorder plane. The short-range localization is observed as a peak in the inverse participation ratio and as a minimum in the localization length. We found that the two distinctive behaviours correspond to a negative differential resistance and to a resonance at particular points corresponding to the edges of the Brillouin zones. Further discussions of these behaviours are included. 相似文献
2.
Dabaki Youssef Khaldi Chokri ElKedim Omar Fenineche Nouredine Lamloumi Jilani 《Journal of Solid State Electrochemistry》2022,26(2):457-468
Journal of Solid State Electrochemistry - In this paper, we study systematically the effect of ball/powder weight ratio on the morphological, structural, and electrochemical properties of... 相似文献
3.
Nadia Zekri Nadia Handaq Abdelhamid El Caidi Touria Zair Mohamed Alaoui El Belghiti 《Research on Chemical Intermediates》2016,42(3):1639-1649
Essential oils proved their efficiency as natural insecticides to fight many pests of stored products and crops whereas the hydrosols have not been evaluated yet. The objective of this work is to assess the insecticidal effect of hydrosols extracted from Mentha suaveolens Ehrh. and Mentha pulegium L. toward an insect pest of citrus, Toxoptera aurantii (Homoptera, Aphididae). The extraction of hydrosols was carried out by hydro-distillation using Clevenger apparatus and then the chemical composition was identified by gas chromatography coupled with mass spectrometry. The chemical composition of two hydrosols revealed the abundance of hydrophilic and oxygenated compounds as piperitenone oxide and carvacrol. Different concentrations of each hydrosol were separately diluted in distilled water and applied topically to aphids. The results of this investigation have shown a high insecticidal effect, and the M. suaveolens hydrosol is more effective against citrus pests than that of M. pulegium L. Consequently, these natural compounds can be used in the management of aphids on citrus. 相似文献
4.
In the detection of bearing faults the so much desired objective remains the extraction of the defect vibratory signature
from the measured signal in which immerses the random noise and other components of the machine. In this article a denoising
method of the measured signals is presented. Based on the optimization of wavelet multiresolution analysis, it uses the kurtosis
as an optimization and evaluation criterion, several parameters were then selected. The experimental results show the validity
of this method within the detection of several defects simulated on ball bearings. The various configurations, in which the
signals were measured, allow leading to optimum conditions of its application. The application of WMRA on filtered signals
allows better results than its application on wide bands signals or a simple band pass filtering. 相似文献
5.
An organic‐inorganic heterogeneous catalyst based on Keplerate polyoxometalates for oxidation of dibenzothiophene derivatives with Hydrogen peroxide
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Reza Fareghi‐Alamdari Negar Zekri Ahmad Jamali Moghadam Khadijeh Tavakoli Hafshajani Mostafa Riahi Farsani 《应用有机金属化学》2018,32(4)
An organic‐inorganic material (NH4)2(MimAM)40[Mo132O372(CH3COO)30(H2O)72] have been synthesized by reacting [(NH4)42[MoVI72 MoV60O372(CH3COO)30(H2O)72] with the ionic liquid 3‐Aminoethyl‐1‐methylimidazolium bromide. The catalyst showed remarkably a high catalytic performance in the oxidation of dibenzothiophene (DBT) derivatives with H2O2 35% as a safe and green oxidant. The main parameters affecting the process including catalyst, acid additive, hydrogen peroxide amounts and temperature have been investigated in detail. Sulfur removal of DBT in n‐heptane reached to 98.3% yield at 40 °C using 2.5 mmol H2O2 and 100 mg of (NH4)2(MimAM)40[Mo132O372(CH3COO)30(H2O)72] after 90 min. Under the optimal conditions, BT (benzothiophene), DBT (dibenzothiophene) and 4,6‐DMDBT (4,6‐dimethyl‐dibenzothiophene) achieved high desulfurization efficiency. Our results showed that the reactivity order of different model sulfur compounds are thiophene <4,6‐dimethyl dibenzothiophene< dibenzothiophene. The catalysts could be easily separated from the reaction solution by simple filtration and recycled for several times without loss of activity. 相似文献
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7.
P. P. Povinec M. K. Pham J. A. Sanchez-Cabeza G. Barci-Funel R. Bojanowski T. Boshkova W. C. Burnett F. Carvalho B. Chapeyron I. L. Cunha H. Dahlgaard N. Galabov L. K. Fifield J. Gastaud J. -J. Geering I. F. Gomez N. Green T. Hamilton F. L. Ibanez M. Ibn Majah M. John G. Kanisch T. C. Kenna M. Kloster M. Korun L. Liong Wee Kwong J. La Rosa S. -H. Lee I. Levy-Palomo M. Malatova Y. Maruo P. Mitchell I. V. Murciano R. Nelson A. Nouredine J. -S. Oh B. Oregioni G. Le Petit H. B. L. Pettersson A. Reineking P. A. Smedley A. Suckow T. D. B. van der Struijs P. I. Voors K. Yoshimizu E. Wyse 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):383-393
A reference material designed for the determination of anthropogenic and natural radionuclides in sediment, IAEA-384 (Fangataufa
Lagoon sediment), is described and the results of certification are presented. The material has been certified for 8 radionuclides
(40K, 60Co, 155Eu, 230Th, 238U, 238Pu, 239+240Pu and 241Am). Information values are given for 12 radionuclides (90Sr, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 232Th, 234U, 235U, 239Pu, 240Pu and 241Pu). Less reported radionuclides include 228Th, 236U, 239Np and 242Pu. The reference material may be used for quality management of radioanalytical laboratories engaged in the analysis of radionuclides
in the environment, as well as for the development and validation of analytical methods and for training purposes. The material
is available from IAEA in 100 g units.
Retired from IAEA in 2003. 相似文献
8.
Water is a very limited resource in Tunisia, both in quantity and in quality. Problems of quality are related to urban, industrial and agricultural activity. Erosion is causing dams to silt up and is leading to phosphorus accumulation in water. The use of agrochemicals, primarily nitrogen and phosphorus, is causing problems of eutrophication. This paper presents the results of a study of sediment and nitrate pollution. The methodology used is based on the EPIC simulation model and a multiobjective programming model (MOPM). The data generated by EPIC are input for the MOPM together with the economic variables. These tools are applied to a 486 ha farm located in northern Tunisia which includes an irrigated area of 300 ha. The study considers three objectives: maximization of gross margin, minimization of erosion, and minimization of nitrate losses. The noninferior set estimation method is implemented to generate the tradeoff curves between the objectives. Results show that nitrate losses are important for both rainfed and irrigated land. The same conclusion is valid for erosion. It is shown that the farmer can reduce the environmental burden without decreasing gross margin, since he is operating below the efficiency curve. 相似文献
9.
Djakaou Iya-Sou Ghezzar Rédouane Mouffok Zekri Mohamed El-Mehdi Abdelmalek Fatiha Cavadias Simeon Ognier Stéphanie 《Plasma Chemistry and Plasma Processing》2015,35(1):143-157
Plasma Chemistry and Plasma Processing - The aim of this work is the modeling of plasma-chemical reactions taking place between highly oxidizing gaseous species (·OH, ·NO and... 相似文献
10.
Lotfi ZekriAhmed Kaiss Jean-Pierre ClercBernard Porterie Nouredine Zekri 《Physics letters. A》2011,375(3):346-351
Percolation properties and d.c. conductivity were determined for an L2×h-random resistor network model of metal-insulator composite films. The effects of the thickness h on the percolation threshold and conductivity were studied numerically in the limit of an infinite size of the L2-plane parallel to the film. For thicknesses ranging from h/L=0.01 to h/L=0.24, a crossover between a finite-size regime and a saturation regime was observed at h/L≈0.1. In the finite-size regime (h/L?0.01), the percolation threshold scales as pc(h)−pc3∝h−1/x, the exponent x being compatible with that of the critical exponent of the 3D correlation length, ν3. The conductivity exponent t appeared to depend linearly on the ratio h/L with a slope νD compatible with 2+ν2, where ν2 is the 2D correlation length exponent. In the saturation regime, a scaling correction for the percolation threshold was found with an exponent 1+1/ν3. In this regime we also observed a logarithmic dependence of the conductivity exponent on h/L. 相似文献