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181.
Fatima El Bachraoui Zakaria Chchiyai Youssef Tamraoui Hassan El Moussaoui Jones Alami Bouchaib Manoun 《中国稀土学报(英文版)》2022,40(4):652-659
Structural, optical and magnetic properties are reported for new synthesized perovskite materials. Ba0.3La0.7Ti0.3Fe0.7O3 and Ba0.1La0.9Ti0.1Fe0.9O3 compositions were prepared via solid state reaction. X-ray analysis confirms that both compositions show feature of perovskite structure. Rietveld refinement method was used to confirm the phase formation and investigate the structure and space group. The study demonstrates the formation of orthorhombic structure with Pnma space group for Ba0.3La0.7Ti0.3Fe0.7O3 while the composition Ba0.1La0.9Ti0.1Fe0.9O3 structure adopts Pbnm symmetry. UV–vis spectroscopy measurements show very broad and intense UV–visible light absorption, the estimated band gap ranges between 2.07 and 2.15 eV. Magnetic measurements were carried out for the compositions Ba0.3La0.7Ti0.3Fe0.7O3 and Ba0.1La0.9Ti0.1Fe0.9O3. The hysteresis loops of both samples at 300 and 10 K show a strong ferromagnetic behavior. The temperature dependent magnetization at 0.05 T under field-cooled (FC) and zero field cooled (ZFC) modes shows magnetic frustration or spin glass-like behavior. 相似文献
182.
Youssef Douini Jamal Riffi Adnane Mohamed Mahraz Hamid Tairi 《Signal, Image and Video Processing》2017,11(7):1321-1328
Image registration is defined as an important process in image processing in order to align two or more images. A new image registration algorithm for translated and rotated pairs of 2D images is presented in order to achieve subpixel accuracy and spend a small fraction of computation time. To achieve the accurate rotation estimation, we propose a two-step method. The first step uses the Fourier Mellin Transform and phase correlation technique to get the large rotation, then the second one uses the Fourier Mellin Transform combined with an enhance Lucas–Kanade technique to estimate the accurate rotation. For the subpixel translation estimation, the proposed algorithm suggests an improved Hanning window as a preprocessing task to reduce the noise in images then achieves a subpixel registration in two steps. The first step uses the spatial domain approach which consists of locating the peak of the cross-correlation surface, while the second uses the frequency domain approach, based on low-frequency (aliasing-free part) of aliased images. Experimental results presented in this work show that the proposed algorithm reduces the computational complexities with a better accuracy compared to other subpixel registration algorithms. 相似文献
183.
Mnica Yorlady Alzate Zuluaga Begoa Miras-Moreno Sonia Monterisi Youssef Rouphael Giuseppe Colla Luigi Lucini Stefano Cesco Youry Pii 《International journal of molecular sciences》2022,23(22)
Increased soil salinity is one of the main concerns in agriculture and food production, and it negatively affects plant growth and crop productivity. In order to mitigate the adverse effects of salinity stress, plant biostimulants (PBs) have been indicated as a promising approach. Indeed, these products have a beneficial effect on plants by acting on primary and secondary metabolism and by inducing the accumulation of protective molecules against oxidative stress. In this context, the present work is aimed at comparatively investigating the effects of microbial (i.e., Azospirillum brasilense) and plant-derived biostimulants in alleviating salt stress in tomato plants by adopting a multidisciplinary approach. To do so, the morphological and biochemical effects were assessed by analyzing the biomass accumulation and root characteristics, the activity of antioxidant enzymes and osmotic stress protection. Furthermore, modifications in the metabolomic profiles of both leaves and root exudates were also investigated by ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS). According to the results, biomass accumulation decreased under high salinity. However, the treatment with A. brasilense considerably improved root architecture and increased root biomass by 156% and 118% in non-saline and saline conditions, respectively. The antioxidant enzymes and proline production were enhanced in salinity stress at different levels according to the biostimulant applied. Moreover, the metabolomic analyses pointed out a wide set of processes being affected by salinity and biostimulant interactions. Crucial compounds belonging to secondary metabolism (phenylpropanoids, alkaloids and other N-containing metabolites, and membrane lipids) and phytohormones (brassinosteroids, cytokinins and methylsalicylate) showed the most pronounced modulation. Overall, our results suggest a better performance of A. brasilense in alleviating high salinity than the vegetal-derived protein hydrolysates herein evaluated. 相似文献
184.
Majida Mcheik Joumana Toufaily Bachar Haj Hassan Tayssir Hamieh Marie Therese Abi Saab Youssef Rouphael Enrico Ferracin Berardo da shio Ibrahim Bashabshah Luna Al Hadidi 《Water and Environment Journal》2017,31(4):552-558
In this study, we present the results of scenarios where secondary‐treated municipal wastewater was used for table grapes irrigation in the region of Ablah, Bekaa valley in Lebanon, and fodder crops irrigation (vetch and barley) in the region of Ramtha in Jordan. In Lebanon, we carried out experiments to assess the response of drip‐irrigated table grapes grown under two water quality regimes (Freshwater (FW) and treated wastewater (TW) and two water levels (100% of evapotranspiration (ETc) and 75% of ETc). While in Jordan, we carried out experiments to assess the response of drip‐irrigated fodder crops considering 4 irrigation levels (Q1: Rain fed; Q2: 80% of ETc; Q3: 100% of ETc; Q4: 120% of ETc) and three crop patterns (C1: Barley 100%; C2: Vetch 100%; C3: Mix 50% barley and 50% vetch). Based on the production and quality components, table grapes were successfully grown on plots that are supplied with TW. Fodder crops were successfully grown using TW with remarkable increase in biomass and grain yield production for the irrigated treatments. 相似文献
185.
186.
Sofiene Jelassi Habib Youssef Christian Hoene Guy Pujolle 《Telecommunication Systems》2012,49(1):17-34
The perceptual quality of VoIP conversations depends tightly on the pattern of packet losses, i.e., the distribution and duration
of packet loss runs. The wider (resp. smaller) the inter-loss gap (resp. loss gap) duration, the lower is the quality degradation.
Moreover, a set of speech sequences impaired using an identical packet loss pattern results in a different degree of perceptual
quality degradation because dropped voice packets have unequal impact on the perceived quality. Therefore, we consider the
voicing feature of speech wave included in lost packets in addition to packet loss pattern to estimate speech quality scores. We distinguish
between voiced, unvoiced, and silence packets. This enables to achieve better correlation and accuracy between human-based subjective and machine-calculated objective scores. 相似文献
187.
Rodrigo Serna-Guerrero Youssef Belmabkhout Abdelhamid Sayari 《Chemical engineering science》2010,65(14):4166-4172
This work deals with the behavior of amine-grafted mesoporous silica (referred to as TRI-PE-MCM-41) throughout adsorption–desorption cycles in the presence of 5% CO2/N2 using various regeneration conditions in batch experiments. The criteria proposed to determine the optimum regeneration conditions are the working adsorption capacity, the rate of desorption and the change of adsorption capacity between consecutive cycles. Using a 23 factorial design of experiments, the impact on the performance of the adsorbent of different levels of temperature, pressure, and flow rate of purge gas during desorption was determined. It was found that all the parameters under study have a statistically significant influence on the working adsorption capacity, but only temperature is influential with respect to desorption rate. Regeneration using temperature swing was found to be attractive, as the highest CO2 adsorption capacity (1.95 mmol g?1) and the fastest desorption rate (9.82×10?4 mmol g?1 s?1) occurred when desorption was carried out at 150 °C. However, if vacuum is applied, regeneration can be achieved at a temperature as low as 70 °C with only a 13% penalty in terms of working adsorption capacity. It was also demonstrated that under the proper regeneration conditions, TRI-PE-MCM-41 is stable over 100 adsorption–desorption cycles. 相似文献
188.
Aditya Rastogi Souhail R. Al-Abed Dionysios D. Dionysiou 《Applied catalysis. B, Environmental》2009,85(3-4):171-179
Polychlorinated biphenyls (PCBs) in the environment pose long-term risk to public health because of their persistent and toxic nature. This study investigates the degradation of PCBs using sulfate radical-based advanced oxidation processes (SR-AOPs). These processes are based on the generation of sulfate radicals through iron (Fe(II), Fe(III)) mediated activation of peroxymonosulfate (KHSO5, PMS) or persulfate (Na2S2O8, PS). This study is the first instance for coupling of Fe(II)/Fe(III) with PMS for PCB degradation in aqueous and sediment systems. The high oxidation efficiencies of the free radicals (SO4−), in combination with the slow rate of consumption of the oxidants, make these processes very effective for the degradation of recalcitrant organic compounds. The effectiveness of the process was evaluated based on the degradation of a model polychlorinated biphenyl, 2-chlorobiphenyl and total organic carbon (TOC) removal. The kinetics of 2-chlorobiphenyl degradation along with the effect of oxidant and catalyst concentrations on the degradation efficiency was studied. Near complete removal of 2-chlorobiphenyl was observed when Fe(II) was used with PMS or PS. Fe(II) acts as a sulfate radical scavenger at higher concentrations indicating that there is an optimum concentration of Fe(II) that leads to most effective degradation of the target contaminant. A chelating agent, sodium citrate, was used to control the quantity of iron in the solution for activation of the oxidant. For the first time, we studied the feasibility of the activation of PMS using iron citrate complexes for PCB degradation. In the presence of sodium citrate, increase in degradation efficiency was observed up to a metal:ligand ratio of 1:2, after which the increase in citrate concentration led to a decrease in removal efficiency. Fe(II)/PMS systems were found to be very effective in degrading PCB in a sediment-slurry system with more than 90% PCB removal being observed within 24 h. 相似文献
189.
In this work, we discuss the piezoelectric activity of lithium tantalite (LiTaO3) thin layers and to more understand this phenomenon we have developed a model for our LiTaO3 resonators based on mason model and simulated the hyper frequency behavior. Our LiTaO3 resonators are made from three layers staked on silicon substrates. The aluminum thin film constitutes the external electrode, the platinum forms the internal electrode and the lithium tantalite constitutes the piezoelectric layer. Each element of these layers is represented by an arrangement of impedances. The simulation shows the reflection coefficient, ρ, as a function of the frequency. We observe a resonant frequency that decreases with the increase of the thickness of the piezoelectric LiTaO3 layers. A slight variation of this resonant frequency is obtained when comparing it with that of the uncharged piezoelectric device, which is due to the different layers loading the system. Over oscillations superposing to the envelope are observed and found to be related to the propagation of the acoustic wave in the silicon substrate. From these over oscillations one can see that this system can be used as an efficient method to calculate the thickness of any substrate. 相似文献
190.
H. A. Youssef N. A. Shaltot K. F. El Nemr A. A. El Miligy 《Journal of Polymer Research》2009,16(2):199-212
Acrylonitrile-butadiene rubber (NBR) has been reinforced with different content of PET up to 25 phr. Vulcanization of prepared
composites as will as the unreinforced ones have been induced by ionizing radiation of accelerated electron beam of varying
dose up to 150 kGy. Evaluations of the vulcanized composites have been followed up through the measurement of mechanical,
physical and thermal properties. Also, scanning electron microscope (SEM) was performed. Mechanical properties, namely tensile
strength (TS) and hardness were found to increase with the increase of irradiation dose as well as the increase in the content
of PET up to 25 phr. Also, elongation at break (ε
b) was found to decrease with the increase of irradiation dose; however, the decrease in εb is not consistence with the increase in fibers loading. Young’s modulus (E) and tensile modulus at 25% elongation (E25) were found to increase with the increase of irradiation dose and fiber loading
up to 20 phr. Also, the volume fraction of swollen rubber increases as irradiation dose and/or fiber content increased; it
was more influenced by irradiation rather than fiber loading. Anisotropic swelling increased with irradiation and fiber loading
up to 20 phr. SEM photomicrograph showed that irradiation causes adhesion between PET fiber and NBR where less pulling out
and less pitting on the surface were observed. The thermal properties of the composite irradiated at 100 kGy reveal that the
activation energy (E
a) increases up to 10 phr fiber content. When the composite that contains 10 phr fiber irradiated at doses higher than100 kGy,
Ea decreased. 相似文献