Structural investigation of (111) oriented (BiFeO3)(1-x){\Lambda}/(LaFeO3)x{\Lambda} superlattices by X-ray diffraction and Raman spectroscopy

(BiFeO3)(1-x){\Lambda}/(LaFeO3)x{\Lambda} superlattices (SLs) with varying x have been grown by pulsed laser deposition on (111) oriented SrTiO3 substrates. In order to obtain good epitaxy and flat samples a conducting SrRuO3 buffer has been deposited prior to the superlattices to screen the polar mismatch for such (111) SrTiO3 orientation. X-ray diffraction reciprocal space mapping on different family of planes were collected and evidenced a room temperature structural change at x=0.5 from a rhombohedral/monoclinic structure for rich BiFeO3 to an orthorhombic symmetry for rich LaFeO3. This symmetry change has been confirmed by Raman spectroscopy and demonstrates the different phase stability compared to similar SLs grown on (100) SrTiO3. The strongly anisotropic strain and oxygen octahedral rotation/tilt system compatibility at the interfaces probably explain the orientation dependence of the phase stability in such superlattices.Comment: 17 pages, 3 figure

A minimal HIV-AIDS infection model with general incidence rate and application to Morocco data

We study the global dynamics of a SICA infection model with general incidence rate. The proposed model is calibrated with cumulative cases of infection by HIV-AIDS in Morocco from 1986 to 2015. We first prove that our model is biologically and mathematically well-posed. Stability analysis of different steady states is performed and threshold parameters are identified where the model exhibits clearance of infection or maintenance of a chronic infection. Furthermore, we examine the robustness of the model to some parameter values by examining the sensitivity of the basic reproduction number. Finally, using numerical simulations with real data from Morocco, we show that the model predicts well such reality.Comment: This is a preprint of a paper whose final and definite form is with 'Statistics Opt. Inform. Comput.', Vol. 7, No 2 (2019). See [http://www.IAPress.org]. Submitted 16/Sept/2018; Revised 10 & 15/Dec/2018; Accepted 15/Dec/201

Possibilité de lutte préventive contre Phoracantha semipunctata L. par la sélection d'espèces d'eucalyptus

Phoracantha semipunctata est un coléoptère xylophage qui s'attaque à des arbres en déséquilibre physiologique. Cette étude tente d'évaluer la résistance à l'égard de ce coléoptère par le taux de survie de certaines espèces plantées dans les différentes stations au Maroc

Hydrochemical characterization of groundwater in the Nekor basin located in the North-East of the Rif of Morocco

 In order to evaluate the physicochemical quality of the groundwater of the Nekor watershed (central Rif area in Morocco) and to explain the origin of the mineralization of these waters, we have analyzed the major elements and traces in water samples taken from 17 wells distributed along the basin. This study showed that the samples of water are very charged with a very important mineralization (≥ 1500 mg / l). The Piper diagram allowed us to define dominant Ca-SO4 or Mg-SO4 hydrochemical facies in upstream of the basin. In downstream of the basin Na-SO4 or Na-Cl is the dominant facies. The analyzes of the trace elements show very high levels of manganese, aluminum and iron with contents exceeding those set by the WHO recommendations.The geochemical study shows that the water-rock interaction is predominant in the aquifer. The water saturation indices indicate that these waters are supersaturated in carbonate minerals.The Principal Component Analysis (PCA) and the analysis of the reports of the major elements allowed us the classification of the waters and the determination of the correlation between the various parameters. Two major phenomena in the acquisition of mineralization of water have been put in evidence. The main phenomenon is the dissolution of the rock by the contact water rock due to the important residence time in the aquifer. The second phenomenon is associated to the supply of nutrients and therefore with the exchange and recharge of the aquifer. The use of hierarchical cluster analysis (HCA) technique revealed three homogeneous groups.

Dysphagia caused by a lateral medullary infarction syndrome (Wallenberg’s syndrome)

A 68-year-old man was referred to our hospital for a dysphagia evolving for 10 days. Clinical examination had found neurological signs ascontralateral Horner’s syndrome, ipsilateral palatal paresis, gait ataxia and hoarseness. Video-fluoroscopy showed a lack of passage of contrastmedium to the distal esophagus. Esogastroduodenoscopy was normal. The cranial MRI had shown an acute ischemic stroke in the left lateral medullar region and the diagnosis of Wallenberg syndrome (WS) was established. WS remains an unknown cause of dysphagia in the clinical practice of the gastroenterologist.Key words: Dysphagia, lateral medullary infarction, Wallenberg’s syndrome, deglutitio

Rapid Determination of Olive Oil Chlorophylls and Carotenoids by Using Visible Spectroscopy

The determination of total chlorophylls and total carotenoids in olive oil by using visible spectroscopy (VIS) is reported. The proposed technique has been compared with the determination of these pigments by near infrared spectroscopy (NIRS) and VIS together with NIRS. Several procedures for multivariate regression were tested. The reference methods used were the determination of the extinction coefficient K670 for total chlorophylls and K470 for total carotenoids. A total of 258 samples were tested. The optimization of the calibration for total chlorophylls was set by using multiple linear regression (MLR) from the wavelengths 670¿686 nm exclusively visible. Its satisfactory performance was proven from the model coefficients standard error of calibration SEC 2.63 and R2 0.97, and the residual predictive deviation (RPD) 5.76 from the external validation. For the total carotenoids the best VIS calibration was fit by using the window of 465¿475 nm and partial least squares (PLS), which provided an RPD of 3.68. However, the model built using the entire spectrum VIS-NIRS available (350¿2,500 nm) was slightly better for this last pigment, showing an RPD of 3.86. Hence, this study showed that the proposed VIS technique can be advantageous for the determination of total chlorophylls in olive oils while it is also suitable for determining total carotenoids.The authors are indebted to the Junta de Andalucía (project AGR-6456) for its financial support, and gratefully acknowledge Antonio Montero, of the Instituto de Recursos Naturales y Agrobiología (CSIC) for his technical assistance. Our thanks are also due to the group Quality and Purity of Oils, of the Instituto de la Grasa (CSIC), for the use of the chromatographic equipmentPeer Reviewe

Nanomechanical properties of nanoconfined polystyrene nanoparticles in nanoblends

The role of nanoconfinement on the glass transition temperature (Tg) of polymers has been extensively studied in the thin film geometry. This work looks at the Tg of nanoconfined polystyrene in spherical nanoparticles (27- 200 nm), individually dispersed in crosslinked polybuthylmethacrylate matrices. A reduction of Tg compared to the bulk was observed in PS nanospheres via neutron scattering-mechanical tests and was found to decrease with decreasing diameter for D< 50nm. The general trend of Tg depression in nanospheres was found to be similar to the results on thin film geometry