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Influences of nanoparticles and chain length on thermodynamic and electrical behavior of fluorine liquid crystals

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Chinese Physics B 2022年第10期31卷 410-416页

作者： Ines ben amor Lotfi Saadaoui Abdulaziz N.Alharbi Talal M.Althagafi Taoufik Soltani Université Tunis El Manar Laboratoire de Physique de la Matiére Molle et de la Modélisation Electromagnétique2092 Tunis Physics Department College of ScienceTaif UniversityP.O.Box 11099Taif 21944Saudi Arabia

Hydrogen-bonded polar nematic liquid crystal series with the general formula n OBAF(n = 7-12) is studied. The mesomorphic characterization is demonstrated through differential scanning calorimetry(DSC) and polarized optical microscopy(POM). The complexes with short alkyl chains(n = 7, 8) present a wide nematic range and monotropic smectic F mesophase, whereas the longer alkyl chain(n = 10-12) analogues show high melting and low clearing mesomorphic liquid crystals. The thermal range of the mesophase and the birefringence increase with chain length decreasing. Furthermore, the effect of the nanoparticles(LiNbO_(3)) on the thermal and the electrical behavior of 8OBAF are investigated. The presence of LiNbO_(3) nanoparticles increases the conductivity and reduces the resistivity of the complex.

关键词： fluorine liquid crystal polar nematic ferroelectric nanoparticles thermal stability dielectric behavior

The Heat Equation for the Dirichlet Fractional Laplacian with Negative Potentials:Existence and Blow-up of Nonnegative Solutions

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Acta Mathematica Sinica,English Series 2017年第7期33卷 981-995页

作者： Ali ben amor Tarek KENZIZI Department of Mathematics Faculty of Sciences of GabèsUniversity GabèsGabès 6072Tunisia Department of Mathematics Faculty of Sciences of TunisUniversity Tunis EIManarTunis 1001Tunisia

We establish conditions ensuring either existence or blow-up of nonnegative solutions for the heat equation generated by the Dirichlet fractional Laplacian perturbed by negative potentials on bounded sets. The elabora... 详细信息

关键词： Fractional Laplacian heat equation Dirichlet form blow-up

Karyological and morphometric variation of the North African green frog Pelophylax saharicus (Anura) in northeastern Africa

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Current Zoology 2010年第6期56卷 678-686页

作者： Nabil amor Sarra FARJALLAH Slim ben-YacouB Paolo MERELLA Khaled SAID Unité de Recherche:Génétique Biodiversité et Valorisation des Bioressources UR/09-30Institut Supérieur de Biotechnologie de Monastir Dipartimento di Biologia Strutturale e Funzionale Università di Napoli Federico Ⅱ Laboratory of Terrestrial and Aquatic Systems Ecology. University BADJI Mokhtar Annaba Sezione di Parassitologia e Malattie Parassitarie Dipartimento di Biologia Animale Università degli Studi di Sassar

Morphometric variation of Pelophylax saharicus was analysed using univariate and multivariate statistics, with bothtraditional and geometric morphometries, based on 148 specimens from four different geographical localities in Tunisia and *** results show the existence of three morphotypes in Tunisia and one in Algeria, and indicate a significant degree of variationin morphometric characters between regions. Specimens from the southernmost region have the smallest body size and thegreatest morphometric divergence from other populations. This pattern of morphometric variation probably results from phenotypicplasticity in response to local environmental factors. The results of our chromosomal study (C-, Ag-NOR-, endonucleasedigestion, DAPI, CMA_3 and Q-banding) reveal this species to exhibit the plesiomorphic Pelophylax karyotype of 2n = 26 biarmedchromosomes and NORs on the eleventh pair. Similarities and differences of the North African green frog are discussed in relationto the different forms of data collected (chromosomal, morphometric, ecological)

关键词：染色体核型形态变化非洲无尾目东北部阿尔及利亚多元统计分析蛙

Kinetics of the Anti-oxidant Response to Salinity in the Halophyte Cakile maritima

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Journal of Integrative Plant Biology 2007年第7期49卷 982-992页

作者： Nader ben amor Ana Jimenez Wided Megdiche Marianne Lundqvist Francisca Sevilla Chedly Abdelly Centre de Biotechnologie a la Technopole de Borj Cedna Laboratoire d'Adaptation des Plantes sux Stress Abiotiques BP 901 Hammam-Lif 2050 Tunisia Department of Plant Stress Biology and Pathology Centro de Edafologia y Biologia Aplicada del Segura Consejo Superior de Investigaciones Cientificas (CSIC) Apdo. 164 E-30100 Murcia Spain

The effects of NaCl stress on the activity of anti-oxidant enzymes （superoxide dismutase, catalase （CAT）, peroxidase （POD）, ascorbate peroxidase （APX）, monodehydroascorbate reductase, dehydroascorbate reductase （DHAR）, and glutathione reductase （GR））, anti-oxidant molecules （ascorbate and glutathione）, and parameters of oxidative stress （malondialdehyde （MDA）, electrolyte leakage, and H2O2 concentrations） were investigated in Cakile maritima, a halophyte frequent along the Tunisian seashore. Seedlings were grown in the presence of salt （100, 200, and 400 mmol/L NaCl）. Plants were harvested periodically over 20 days. Growth was maximal in the presence of 0-100 mmol/L NaCl. At 400 mmol/L NaCl, growth decreased significantly. The salt tolerance of C. maritima, at moderate salinities, was associated with the lowest values of the parameters indicative of oxidative stress, namely the highest activities of POD, CAT, APX, DHAR, and GR and high tissue content of ascorbate and glutathione. However, prolonged exposure to high salinity resulted in a decrease in anti-oxidant activities and high MDA content, electrolyte leakage, and H2O2 concentrations. These results suggest that anti-oxidant systems participate in the tolerance of C. maritima to moderate salinities.

关键词： anti-oxidant activities ascorbate glutathione halophyte lipid peroxidation salt tolerance.

Magnetic and specific heat studies of the frustrated Er_2Mn_2O_7 compound

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Journal of Rare Earths 2013年第1期31卷 54-59页

作者： N.ben amor M.Bejar E.Dhahri M.A.Valente P.Lachkar E.K.Hlil Laboratory of Applied Physics Faculty of Sciences of SfaxBP 1171University of Sfax I3N and Physics Department University of Aveiro MCMF Néel InstitutCNRS25 avenue des MartyrsBuilding FBP 16638042 Grenoble cedex 9France MCBT Institut NéelCNRS25 avenue des MartyrsBuilding EBP 16638042 Grenoble cedex 9France

A new ErzMn207 compound was synthesized by the ceramic method and its crystal structure was characterized LJsing powder X-ray diffraction （XRD） and observed by scanning electron microscopy （SEM）. The magnetic properties were investigated using a BS2 magnetometer and the heat capacity was studied using a quantum design （PPMS）. The structural study revealed that this compound was monophasic and crystallized in the monoclinic system with the P2/M space group. Magnetization measurements were carried out in the temperature range of 1.8-200 K under an applied magnetic field of 0.05 T. A crossover from a room temperature para- magnetic phase to an antiferromagnetic one at low temperature was detected from the magnetic study. The magnetic susceptibility, in the paramagnetic region above 40 K, was found to present a simple Curie-Weiss type behavior. From the specific heat （G,） measurements in magnetic fields up to 5 T, we noted the presence of a wide peak characteristic of a second order magneto-structural transition.

关键词： magnetic frustration magnetic phase transition specific heat rare earths

Lower Bifidobacteria counts in both duodenal mucosa-associated and fecal microbiota in irritable bowel syndrome patients

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World Journal of Gastroenterology 2009年第23期15卷 2887-2892页

作者： Angèle PM Kerckhoffs Melvin Samsom Michel E van der Rest Joris de Vogel Jan Knol Kaouther ben-amor Louis MA Akkermans Gastrointestinal Research Unit Department of Gastroenterology and Surgery University Medical Center Utrecht Heidelberglaan 100 F02.618 3584CX Utrecht The Netherlands BioVisible BV LJ Zielstraweg 1 9713 GX Groningen The Netherlands Danone Research-Centre for Specialized Nutrition Bosrandweg 20 6704PH Wageningen The Netherlands

AIM: To determine the composition of both fecal and duodenal mucosa-associated microbiota in irritable bowel syndrome (IBS) patients and healthy subjects using molecular-based techniques. METHODS: Fecal and duodenal mucosa brush samples were obtained from 41 IBS patients and 26 healthy subjects. Fecal samples were analyzed for the composition of the total microbiota using fluorescent in situ hybridization (FISH) and both fecal and duodenal brush samples were analyzed for the composition of bif idobacteria using real-time polymerase chain reaction. RESULTS: The FISH analysis of fecal samples revealed a 2-fold decrease in the level of bifidobacteria (4.2 ± 1.3 vs 8.3 ± 1.9, P < 0.01) in IBS patients compared to healthy subjects, whereas no major differences in other bacterial groups were observed. At the species level, Bifidobacterium catenulatum levels were significantly lower (6 ± 0.6 vs 19 ± 2.5, P < 0.001) in the IBS patients in both fecal and duodenal brush samples than in healthy ***: Decreased bifidobacteria levels in both fecal and duodenal brush samples of IBS patients compared to healthy subjects indicate a role for microbiotic composition in IBS pathophysiology.

关键词：微生物利用双歧杆菌肠粘膜综合征粪便患者微生物组成样本分析

Wastewater treatment by catalytic wet air oxidation process over AI-Fe pillared clays synthesized using microwave irradiation

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Frontiers of Environmental Science & Engineering 2018年第1期12卷 57-63页

作者： Halima Sassi Gwendoline Lafaye Hedi ben Jacques amor Abdelaziz Gannouni Mohamed Razak Jeday Barbier-Jr

Microwave irradiation has been used to prepare AI, Fe-pillared clays from a natural Tunisian smcctitc from the E1 Hicha deposit （province of Gabes）. Chemical analysis, XRD spectra and surface properties evidenced the success of pillaring process. The obtained solids present higher surthce area and pore volume than conventionally prepared A1-Fe pillared clays. The main advantages of the microwave methodology are the considerable reduction of the synthesis time and the consumption of water. The microwave-derived AI-Fe pillared clays have been tested tbr catalytic wet air oxidation （CWAO） of phenol in a stirred tank at 160℃ and 20 bar of pure oxygen pressure. These materials are efficient for CWAO of phenol and are highly stable despite the severe operating conditions （acidic media, high pressure, high temperature）. The catalyst deactivation was also significantly hindered when compared to conventionally prepared clays. A1-Fe pillared clays prepared by microwave methodology are promising as catalysts for CWAO industrial water treatment.

关键词： WaterCatalytic wet air oxidationPillared claysMicrowavePhenol

Episodic Sedimentation of Heavy Metals and Iron in Bizerte Lagoon, Northern Tunisia

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International Journal of Geosciences 2013年第1期4卷 24-35页

作者： amor ben Garali Mohamed Ouakad Moncef Gueddari Faculté des Sciences de Bizerte Laboratoire de Sédimentologie et Géochimie Marine Bizerte Tunisie Faculté des Sciences de Tunis Université El Manar Tunis Tunisie

The correlations between various sedimentological and geochemical parameters permit to identify the main sedimenta tion phases of pollution carriers, especially those related to the sediment cores lithology in Bizerte Lagoon. A close re lationship exists between the TOC distribution and the fine fraction (r = 0.70;threshold 5%). This is to identify the for mation of organic minerals aggregates. Significant correlations between specific organic matter and heavy metals have been identified. Indeed, the calculated correlation coefficient varies between 0.4 for Zn and 0.85 for Mn. The enrich ment of the intermediate horizons in heavy metals result in specific sedimentations episodes of the prodeltaic zones. Under these conditions, the surface sediments profit from a “salting-out” phenomenon, which explains the excess of lead observed on the surface. The enriched zones in manganese and zinc correspond to the strongest contents of kaolin ite and in smectite, thus, there would be an association with the finest phyllosilicates and/or the colloidal oxyhydroxy des. This is primarily due to the formation of an organic minerals complex via the trapping phenomenon of the argilla ceous particles (smectite) and the organic matter of anthropogenic origin. It is to be specified that the presence of metal elements of natural origin (Mn) or anthropogenic origin (Fe, Zn, Pb and Ni) which induce the consolidation of these organic minerals complexes.

关键词： Core Clay Minerals Organic Matters Heavy Metals Bizerte Lagoon Tunisia

Finite Element Methods Applied to the Tubular Linear Stepping Motor

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Journal of Electromagnetic Analysis and Applications 2013年第5期5卷 219-222页

作者： Walid El Fezzani Abdessattar ben amor Unité de Recherche en Automatique et Informatique Industrielle de l’Institut National des Sciences Appliquées et de Technologie Tunis Tunisie.

In this paper proposes a Finite Element Methods analyzing applied to the linear tubular stepping actuator. The linear displacement is modeled by means of a layer of finite elements placed in the air gap. The design of the linear stepper motor for achieving a specific performance requires the choice of appropriate tooth geometry. The magnetic field of the actuator has been analyzed using the finite element method over a current-displacement variation. The magneto static field and electromagnetic force was introduced in order to predict before construction, the inductance values according to the displacement and the currents into the coils. The results were obtained for the magnetic flux density distribution and the electromagnetic force for different positions and current.

关键词： Finite Element Methods Linear Tubular Stepping Actuator Mesh Repartition