Time filter

Source Type

Settat, Morocco

Jebbouj R.,Hassan 1er University | El Yousfi B.,French National Institute for Agricultural Research
European Journal of Plant Pathology

Knowledge of pathotype diversity and virulence in local populations of Pyrenophora teres is a prerequisite to screening for durable resistance to net blotch. The current study aimed to quantify the virulence level of Moroccan isolates, identify and designate existing pathotypes, and select resistant genotypes. We developed a method for virulence quantification of P. teres isolates based on a conversion of infection responses into frequencies for use in correspondence analysis. Coordinates of the first axis of this analysis had a virulence spectrum and ranked isolates from virulent to avirulent. Mixed model analysis was also devised for virulence quantification. Coordinates of the first dimension of correspondence analysis were linearly correlated to BLUPs (Best Linear Unbiased Predictors) of the mixed model. A genotype by genotype by environment model (GGE) coupled with cluster analysis differentiated P. teres isolates into ten and nine pathotypes for net- and spot-forms respectively. Populations of these two forms were dissimilar in terms of classes of virulence. For P. teres f. maculata, avirulent, moderately virulent and highly virulent isolates represented one-third of the population, whereas 90% of P. teres f. teres population was composed of avirulent to moderately avirulent isolates. Barley differential sets were subsequently reduced to two new sets that simplified pathotyping through a key code based on resistant or susceptible reactions. Dendrograms of cluster analysis based on GGE analysis depicted the stability of a genotype's reactions across all isolates, and using only resistant cultivars as sources of resistance to control net blotch disease would, based on this analysis, fail to control all pathotypes. Therefore, we propose an alternative breeding strategy to control net blotch effectively. © 2010 KNPV. Source

El Majdoub K.,Hassan II University | Ouadi H.,Hassan II University | Touati A.,Hassan 1er University
International Review on Modelling and Simulations

This paper discuss the problem of controlling quarter-car semi-active suspension system. Presently, the suspension system involves a magnetorheological (MR) damper with a hysteretic behavior captured through the Bouc-Wen model. This device can be integrated in the electric or hybrid electric vehicle. The control objective is to regulate well the chassis vertical position despite the road irregularities. In addition to these irregularities, the difficulty of the control problem lies in the nonlinearity of the system model and the inaccessibility to measurements of the hysteresis internal state variable. The control design is performed using the LQR theory and Lyapunov control design tools; it includes an observer providing online estimates of the hysteresis internal state. The controller is formally shown to meet the desired control objectives. This theoretical result is confirmed by several simulations. The latter illustrate the performances of the LQR method and compare them with those of the passive suspension. © 2014 Praise Worthy Prize S.r.l. - All rights reserved. Source

Barka N.,Hassan 1er University | Abdennouri M.,Hassan 1er University | El Makhfouk M.,Equipe de Recherche Analyse controle et environnement ERACE | Qourzal S.,University Ibn Zohr
Journal of Environmental Chemical Engineering

The biosorption of cadmium (II) and lead (II) ions onto a natural, plentiful and low-cost biosorbent developed from cactus cladodes was investigated in batch mode. Experiments were carried out as a function of average biosorbent particle size, pH, biosorbent mass, contact time, initial metal concentration and temperature. The experimental results indicate that, the percentage of biosorption increases with an increase in the biosorbent dosage and the decrease of particle size. The equilibrium uptake was increased with an increase in the initial metal concentration in solution. The maximum biosorption occurred at pH of 5.8 and 3.5, respectively for cadmium (II) and lead (II) ions. Biosorption kinetic data were properly fitted with the pseudo-second-order kinetic model. The equilibrium data fitted very well to the Langmuir model with a maximum monolayer biosorption capacity of 30.42 and 98.62 mg/g, respectively for cadmium (II) and lead (II) ions. The biosorption yield decreases with an increase in solution temperature. The FTIR analysis of unloaded and metal loaded biosorbent indicated the involvement of CO, OC and COC groups in metal binding. © 2013 Elsevier Ltd. All rights reserved. Source

Abboussi O.,Hassan 1er University | Paizanis E.,University of Caen Lower Normandy | El Ganouni S.,Hassan 1er University
Pharmacology Biochemistry and Behavior

Several epidemiological studies show an increase in cannabis use among adolescents, especially in Morocco for being one of the major producers in the world. The neurobiological consequences of chronic cannabis use are still poorly understood. In addition, brain plasticity linked to ontogeny portrays adolescence as a period of vulnerability to the deleterious effects of drugs. The aim of this study was to investigate the behavioral neurogenic effects of chronic exposure to the cannabinoid agonist WIN55,212-2 during adolescence, by evaluating the emotional and cognitive performances, and the consequences on neurogenesis along the dorso-ventral axis of the hippocampus in adult rats. WIN55,212 was administered intraperitoneally (i.p.) once daily for 20 days to adolescent (27-30 PND) and adult Wistar rats (54-57 PND) at the dose of 1 mg/kg. Following a 20 day washout period, emotional and cognitive functions were assessed by the Morris water maze test and the two-way active avoidance test. Twelve hours after, brains were removed and hippocampal neurogenesis was assessed using the doublecortin (DCX) as a marker for cell proliferation. Our results showed that chronic WIN55,212-2 treatment significantly increased thigmotaxis early in the training process whatever the age of treatment, induced spatial learning and memory deficits in adolescent but not adult rats in the Morris water maze test, while it had no significant effect in the active avoidance test during multitrial training in the shuttle box. In addition, the cognitive deficits assessed in adolescent rats were positively correlated to a decrease in the number of newly generated neurons in dorsal hippocampus. These data suggest that long term exposure to cannabinoids may affect more potently spatial learning and memory in adolescent compared to adult rats via a negative action on hippocampal plasticity. © 2014 Elsevier Inc. Source

Barka N.,Hassan 1er University | Abdennouri M.,Hassan 1er University | Makhfouk M.E.,Equipe de Recherche Analyse controle et environnement ERACE
Journal of the Taiwan Institute of Chemical Engineers

The biosorption of Methylene Blue (MB), Eriochrome Black T (EBT) and Alizarin S (AS) from aqueous solutions by dried prickly pear cactus cladodes as a low-cost, natural and eco-friendly biosorbent was investigated. The study was carried out under various parameters, such as average biosorbent particle size, pH, biosorbent dosage, contact time, initial dye concentration and temperature. The experimental results show that, the percentage of biosorption increases with an increase in the biosorbent dosage, and the decrease of particle size. The biosorption was pH dependent with a high biosorption of cationic dye (MB) in basic range and a high biosorption of anionic dyes (EBT and AS) in acidic range. The equilibrium uptake was increased with an increase in the initial dye concentration in solution. Biosorption kinetic data were properly fitted with the pseudo-second-order kinetic model. The experimental isotherm data were analyzed using Langmuir, Freundlich, Redlich-Peterson, Temkin and Toth isotherm equations. The best fit was obtained by the Redlich-Peterson model and the Langmuir model with a Langmuir maximum monolayer biosorption capacity of 189.83. mg/g for Methylene Blue, 200.22. mg/g for Eriochrome Black T and 118.35. mg/g for Alizarin S. The biosorption was exothermic in nature (ΔH° = -31.035 kJ/mol for MB, -10.25 kJ/mol for EBT and -11.69 kJ/mol for AS). The reaction was accompanied by a decrease in entropy (ΔS° = -94.76 J/K mol for MB, -38.44 J/K mol for EBT and -41.93 J/K mol for AS). The Gibbs energy (ΔG°) increased when the temperature was increased from 25 to 60. °C indicating a decrease in feasibility of biosorption at higher temperatures. © 2012 Taiwan Institute of Chemical Engineers. Source

Discover hidden collaborations