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First-principles study and electronic structures of Mn-doped ultrathin ZnO nanofilms

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Chinese Physics B 2012年第10期21卷 362-368页

作者： E.Salmani A.Benyoussef H.Ez-Zahraouy E.H.Saidi O.Mounkachi LMPHE(URAC 12) Departement de PhysiqueFacult'e des SciencesUniversit'e Mohammed V-AgdalRabatMorocco LPHE Departement de PhysiqueFacult'e des SciencesUniversit'e Mohammed V-AgdalRabatMorocco Institute of Nanomaterials and Nanotechnology MAScIRRabatMorocco

The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO *** band structure calculation shows that the band gaps of ZnO films with 2,4,and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film ***,the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively,while they exhibit spin glass phases for higher Mn *** is also found,on the one hand,that the spin glass phase turns into the ferromagnetic one,with the substitution of nitrogen atoms for oxygen atoms,for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film *** the other hand,the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities,while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk ***,it is shown that using the effective field theory for ferromagnetic system,the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida（RKKY） interaction.

关键词： ultra thin film ZnO ab initio electronic structure magnetic properties effective field theory

Stabilization and Evaluation of Modified Nanofiber Flour Wood on the Properties of Cement-Baszd Mortar

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Journal of Renewable Materials 2019年第8期7卷 763-774页

作者： Fadhel Aloulou Sabrine Alila Habib Sammouda Laboratory of Energy and Materials(LabEM):LR11ES34 Higher School of Science and Technology of Hammam SousseUniversity of SousseSousseTunisia Laboratoire sciences des Matériaux et Environnement:LMSE Facultédes Sciences de SfaxUniversity of SfaxSfaxTunisia

The influence of nanofiberwood on the properties of the fresh condition of cement based mortars is not known in detail,despite recent advances in nanocellulose technology and it is related composite *** wood from industrial waste,produced by high-pressure homogenization,was used as cement partial replacement for cement paste at a content ranging from 0%to 2%by weight of *** effect of the nanofiber wood content on the porosity,the compressive strength and the degree of hydration of the cement was *** have shown an improvement in the compressive strength by more than 50%with 1%of added fiber *** chemical modification of nanofibers wood by grafting of chains alkyls in their surfaces can reduce the quantity of water absorbed by the *** addition of an anionic additive(SDBS)in the water of mixing improves of more the surface of samples by minimizing the size of pores by emulsion effect,from where the absorption of water *** degree of hydration of the cement has increased with the cellulose content containing *** analyze revealed that the presence of nanofiber wood favored the hydration of the cement by producing more calcium silicate gel and portlandite,probably the main reason for this improvement in compressive strength.

关键词： Cement nano-fiber adjuvant surfactant emulsion hydratation thermal conductivity

Evaluation of stress intensity factors for bi-material interface cracks using displacement jump methods

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Acta Mechanica Sinica 2017年第6期33卷 1051-1064页

作者： K. C. Nehar B. E. Hachi F. Cazes M. Haboussi Laboratoire de développement en mécanique et matériaux (LDMM) Université de Djelfa PB 3117 Djelfa Algeria Laboratoire des sciences des Procédés et des Matériaux (LSPM) UPR 3407 CNRS Université Paris 13 Paris France

The aim of the present work is to investigate the numerical modeling of interfacial cracks that may appear at the interface between two isotropic elastic materials. The extended finite element method is employed to analyze brittle and bi-material interfacial fatigue crack growth by computing the mixed mode stress intensity factors(SIF). Three different approaches are introduced to compute the SIFs. In the first one, mixed mode SIF is deduced from the computation of the contour integral as per the classical J-integral method,whereas a displacement method is used to evaluate the SIF by using either one or two displacement jumps located along the crack path in the second and third approaches. The displacement jump method is rather classical for mono-materials,but has to our knowledge not been used up to now for a bimaterial. Hence, use of displacement jump for characterizing bi-material cracks constitutes the main contribution of the present study. Several benchmark tests including parametric studies are performed to show the effectiveness of these computational methodologies for SIF considering static and fatigue problems of bi-material structures. It is found that results based on the displacement jump methods are in a very good agreement with those of exact solutions, such as for the J-integral method, but with a larger domain of applicability and a better numerical efficiency(less time consuming and less spurious boundary effect).

关键词： Bi-material interface crack Mixed mode stress intensity factor Displacement jump X-FEM Fatigue crack growth

盐酸溶液中钢铁腐蚀的绿色缓蚀剂柠檬油精(英文)

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物理化学学报 2009年第7期25卷 1254-1258页

作者： CHAIEB E. BOUYANZER A. HAMMOUTI B. BERRABAH M. Laboratoire de Chimie Appliquée et Environnement Faculté des Sciences

The inhibition of steel corrosion in hydrochloric acid solutions by limonene, which was extracted from citrus and orange fruit, was studied using measurements of mass loss, electrochemical polarisation and electrochemical impedance spectroscopy (EIS) methods. Naturally, the substance reduced the rate of corrosion. The linearity of the cathodic curves for all concentrations indicated that the law of Tafel was followed. The effectiveness of inhibition increased with the increase in concentration of limonene and this exceeded 72% at 0.220 g·L-1. The inhibition efficiency is temperature independent in the temperature range of 298-328 K. Adsorption of the substance on the surface of steel obeys the Frumkin isotherm model.

关键词：钢腐蚀金属氯化氢 EIS

Satellite monitoring of land-use and land-cover changes in northern Togo protected areas

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Journal of Forestry Research 2014年第2期25卷 385-392页

作者： Fousseni Folega Chun-yu Zhang Xiu-hai Zhao Kperkouma Wala Komlan Batawila Hua-guo Huang Marra Dourma Koffi Akpagana The Key Laboratory for Silviculture and Conservation of Ministry of Education Beijing Forestry University Université de Lomé Laboratoire de botanique et écologie végétaleFaculté des sciences

Remote-sensing data for protected areas in northern Togo, obtained in three different years （2007, 2000, and 1987）, were used to assess and map changes in land cover and land use for this drought prone zone. The normalized difference vegetation index （NDVI） was applied to the images to map changes in vegetation. An unsupervised classification, followed by classes recoding, filtering, identifications, area computing and post-classification process were applied to the composite of the three years of NDVI images. Maximum likelihood classification was applied to the 2007 image （etM＋2007） using a supervised classification process. Seven vegetation classes were defined from training data sets. The seven classes included the following biomes： riparian forest, dry forest, flooded vegetation, wooded savanna, fallows, parkland, and water. For these classes, the overall accuracy and the overall kappa statistic for the classi- fied map were 72.5% and 0.67, respectively. Data analyses indicated a great change in land resources; especially between 1987 and 2000 proba- bly due to the impact of democratization process social, economic, and political disorder from 1990. Wide-scale loss of vegetation occurred during this period. However, areas of vegetation clearing and regrowth were more visible between 2000 and 2007. The main source of confusion in the contingency matrix was due to heterogeneity within certain classes. It could also be due to spectral homogeneity among the classes. This research provides a baseline for future ecological landscape research and for the next management program in the area.

关键词： land change NDVI land cover protected areas Northern Togo

Comparative Study of Entanglement and Wigner Function for Multi-Qubit GHZ-Squeezed State

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Communications in Theoretical Physics 2017年第12期67卷 729-734页

作者： Fatima-Zahra Siyouri Laboratoire de Physique Thèorique Département de Physique Faculté des Sciences Université Mohammed Ⅴ-Agdal

In this paper we address the possibility of using the Wigner function to capture the quantum entanglement present in a multi-qubit system. For that purpose, we calculate both the degree of entanglement and the Wigner function for mixed tripartite squeezed states of Greenberger–Horne–Zeilinger(GHZ) type then we compare their behaviors. We show that the role of Wigner function in detecting and quantifying bipartite quantum correlation [Int. J. Mod. Phys. B30(2016) 1650187] may be generalized to the multipartite case.

关键词： negativity of Wigner function entanglement squeezed states tripartite GHZ non-classicality

COMBINED EFFECTS IN A SEMILINEAR POLYHARMONIC PROBLEM IN THE UNIT BALL

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Acta Mathematica Scientia 2014年第5期34卷 1404-1416页

作者： Zagharide Zine EL ABIDINE Dpartement de Mathmatiques Facult des Sciences de TunisCampus Universitaire2092 Tunis Tunisia

Let m be a positive integer and B be the unit ball of Rn （n≥2）. We investigate the existence, uniqueness and the asymptotic behavior of a positive continuous solution to the following semilinear polyharmonic boundary value problem （-△）mu=a1（x）uα1＋a2（x）uα2 , lim｜x｜→1 u（x）（1-｜x｜）m-1 =0, where α1,α2∈（-1, 1） and a1, a2 are two nonnegative measurable functions on B satisfying some appropriate assumptions related to Karamata regular variation theory.

关键词： Kato class positive solution nonlinear polyharmonic equation asymptoticbehavior schauder fixed point theorem

Phenolic profiling in ten apricot clones using an efficient method(Thioacidolysis-UFLC)and determination of their antioxidant potential

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Food Bioscience 2022年第5期49卷 1117-1123页

作者： Jamal Ayour Jean-Marc Audergon Catherine M.G.C.Renard Mohamed Benichou Carine Le Bourvellec facult´e des sciences Universit´e Cadi AyyadLaboratoire Sciences des AlimentsM-40090MarrakechMorocco UMR408 S´ecurit´e et Qualit´e des Produits d’Origine V´eg´etale INRAEF-84000AvignonFrance Universit´e d’Avignon et des Pays du Vaucluse UMR408 S´ecurit´e et Qualit´e des Produits d’Origine V´eg´etaleF-84000AvignonFrance INRAE UR1052 G´en´etique et Am´elioration des Fruits et L´egumesF-84143MontfavetFrance

The polyphenols of ten Moroccan apricot clones were analyzed using a Thioacidolysis-UFLC combination technology in order to evaluate their evolution pattern and their contribution to antioxidant activity during *** were the predominant polyphenol class with concentrations varied from 30 to 1091 mg kg􀀀1 in M1(commercial stage)and from 398 to 1411 mg kg􀀀1 in M2(consumption stage).Procyanidins with catechins,the two classes constitute the principal contributors to antioxidant activity of studied *** impact of ripening was very limited compared to genotype,especially for size and skin color of the *** Thioacidolysis-UFLC technology highlighted the contribution of procyanidins to antioxidant activity of apricot and established a typology based on the clone skin ***,dark red and orange apricots had higher phenolic contents and antioxidant activities than clear *** indicates the importance of fruit color to predict apricot bioactive compounds and the crucial role of phenolic compounds in the antioxidant activity of these fruits.

关键词： Thioacidolysis Prunus armeniaca Maturity Phenolic compounds Antioxidant Skin color

Physico-chemical and mechanical properties of Ti_3SiC_2-based materials elaborated from SiC/Ti by reactive spark plasma sintering

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Journal of Advanced Ceramics 2019年第1期8卷 47-61页

作者： Faten TURKI Houyem ABDERRAZAK Frédéric SCHOENSTEIN Florent TêTARD Mohieddine ABDELLAOUI Noureddine JOUINI Laboratoire des Matériaux Utiles Institut National de Recherche et d’Analyse Physico-chimique Laboratoire de sciences des Procédés et Matériaux Université Paris 13 Sorbonne Paris Cité CNRS

In this paper, the synthesis of Ti_3 SiC_2 from SiC/Ti powder using reactive spark plasma sintering(R-SPS) in the temperature range of 1300-1400 ℃ is reported. The results show that the purity of Ti_3 SiC_2 is improved up to 75 wt% when the holding time is increased from 10 to 20 min at1400 ℃. The thermodynamic and experimental results indicate that Ti_3 SiC_2 formation takes place via the reaction of a pre-formed TiC phase with the silicides, formed from the eutectic *** analysis of mechanical behaviour indicates that samples with higher percentage of secondary phases exhibit higher microhardness and better resistance compared to the near single phase Ti_3 SiC_2.

关键词： Ti3SiC2 reactive spark plasma sintering(R-SPS) density mechanical properties