Center National Of Lenergie
Center National Of Lenergie
Ziti S.,Mohammed V University |
Aouini S.,Mohammed V University |
Labrim H.,Center National Of Lenergie |
Bahmad L.,Mohammed V University
Materials Research Express | Year: 2017
We study the magnetic layering transitions in a polyamidoamine (PAMAM) dendrimer nano-structure, under the effect of an external magnetic field. We examine the magnetic properties, of this model of the spin S = 1 Ising ferromagnetic in real nanostructure used in several scientific domains. For T = 0, we give and discuss the ground state phase diagrams. At non null temperatures, we applied the Monte Carlo simulations giving important results summarized in the form of the phase diagrams. We also analyzed the effect of varying the external magnetic field, and found the layering transitions in the polyamidoamine (PAMAM) dendrimer nano-structure. © 2017 IOP Publishing Ltd.
Mabit L.,International Atomic Energy Agency |
Benmansour M.,Center National Of Lenergie |
Abril J.M.,University of Seville |
Walling D.E.,University of Exeter |
And 7 more authors.
Earth-Science Reviews | Year: 2014
Increasing anthropogenic pressures coupled with climate change impacts on natural resources have promoted a quest for innovative tracing techniques for understanding soil redistribution processes and assessing the environmental status of soil resources. Among the different existing tracers, the fallout component of the radioisotope lead-210, also termed unsupported or excess lead-210 (210Pbex) when referring to its presence in soil or sediment, arguably offers the broadest potential for environmental applications, due to its origin and relatively long half-life. For more than five decades, 210Pbex has been widely used for dating sediments, to investigate sedimentation processes and, since the 1990s, to provide information on the magnitude of soil and sediment redistribution.The aim of this review is to provide a comprehensive evaluation and discussion of the various applications of 210Pbex as a tracer in terrestrial and aquatic environments, with particular emphasis on catchment sediment budget investigations. This paper summarizes the state-of-the-art related to the use of this tracer, the main assumptions, the requirements (including the need for accurate analytical measurements and for parallel validation), and the limitations which must be recognised when using this fallout radionuclide as a soil and sediment tracer. Lessons learned and current and future research needs in the environmental and radiochronological application of 210Pbex are also presented and discussed. © 2014 Elsevier B.V.
Qmichou Z.,Center National Of Lenergie |
Qmichou Z.,Laboratoiore Of Microbiologie |
Khyatti M.,Institute Pasteur du Maroc |
Berraho M.,Laboratoire dEpidemiologie |
And 7 more authors.
BMC Infectious Diseases | Year: 2013
Background: Worldwide, cervical cancer is the second most common cancer in women. High-risk human papillomavirus (HPV) play a crucial role in the etiology of cervical cancer and the most prevalent genotype is HPV16. HPV 16 intratypic variants have been reported to differ in their prevalence, biological and biochemical properties. The present study was designed to analyze and identify HPV type 16 E6 variants among patients with cervical cancer in Morocco.Methods: A total of 103 HPV16 positive samples were isolated from 129 cervical cancer cases, and variant status was subsequently determined by DNA sequencing of the E6 gene.Results: Isolates from patients were grouped into the European (E), African (Af) and North-American (NA1) phylogenetic clusters with a high prevalence of E lineage (58.3%). The Af and NA1 variants were detected in 31.1% and 11.6% of the HPV16 positive specimens, respectively, whereas, only 3% of cases were prototype E350T. No European-Asian (EA), Asian (As) or Asian-American (AA) variants were observed in our HPV16-positive specimens. At the amino acid level, the most prevalent non-synonymous variants were L83V (T350G), H78Y (C335T), E113D (A442C), Q14D (C143G/G145T) and R10I (G132T), and were observed respectively in 65%, 41.8%, 38.8%, 30.1% and 23.3% of total samples.Moreover, HPV16 European variants were mostly identified in younger women at early clinical diagnosis stages. Whereas, HPV16 Af variants were most likely associated with cervical cancer development in older women with pronounced aggressiveness.Conclusion: This study suggests a predominance of E lineage strains among Moroccan HPV 16 isolates and raises the possibility that HPV16 variants have a preferential role in progression to malignancy and could be associated with the more aggressive nature of cervical cancer. © 2013 Qmichou et al.; licensee BioMed Central Ltd.
PubMed | Mohammed V University, CIRAD - Agricultural Research for Development, Center National Of Lenergie and French National Institute for Agricultural Research
Type: | Journal: Frontiers in plant science | Year: 2016
Hirschfeldia incana, a pseudometallophyte belonging to the Brassicaceae family and widespread in the Mediterranean region, was selected for its ability to grow on soils contaminated by lead (Pb). The global comparison of gene expression using microarrays between a plant susceptible to Pb (Arabidopsis thaliana) and a Pb tolerant plant (H. incana) enabled the identification of a set of specific genes expressed in response to lead exposure. Three groups of genes were particularly over-represented by the Pb exposure in the biological processes categorized as photosynthesis, cell wall, and metal handling. Each of these gene groups was shown to be directly involved in tolerance or in protection mechanisms to the phytotoxicity associated with Pb. Among these genes, we demonstrated that MT2b, a metallothionein gene, was involved in lead accumulation, confirming the important role of metallothioneins in the accumulation and the distribution of Pb in leaves. On the other hand, several genes involved in biosynthesis of ABA were shown to be up-regulated in the roots and shoots of H. incana treated with Pb, suggesting that ABA-mediated signaling is a possible mechanism in response to Pb treatment in H. incana. This latest finding is an important research direction for future studies.
Fortunato R.S.,Institute Biofisica Carlos Chagas Filho |
De Souza E.C.L.,Institute Biofisica Carlos Chagas Filho |
Ameziane-el Hassani R.,Center National Of Lenergie |
Boufraqech M.,Institute Gustave Roussy |
And 9 more authors.
Journal of Clinical Endocrinology and Metabolism | Year: 2010
Context: Thyroperoxidase (TPO) and dual oxidase (DUOX) are present at the apical membrane of thyrocytes, where TPO catalyzes thyroid hormone biosynthesis in the presence of H2O2 produced by DUOX. Both enzymes are colocalized and associated, but the consequences of this interaction remain obscure. Objective: The objective of this study was to evaluate the functional consequences of TPO-DUOX interaction at the plasma membrane. Design: The functional consequences of DUOX-TPO interaction were studied by measuring extracellular H2O2 concentration and TPO activity in a heterologous system. For this purpose, HEK293 cells were transiently transfected with a combination of human TPO with human DUOX1 or DUOX2 in the presence of their respective maturation factors, DUOXA1 or DUOXA2. The effect of human DUOX2 mutants in which cysteine residues in the N-terminal domain were replaced by glycines was also analyzed. Results: We observed that production of H 2O2 decreases both TPO and DUOX activities. We show that TPO presents a catalase-like effect that protects DUOX from inhibition by H 2O2. This catalase-like effect depends on the association between both enzymes, which probably occurs through the DUOX peroxidase-like domain because this effect was not observed with human DUOX2 mutants. Conclusion: The DUOX-TPO association at the plasma membrane is relevant for normal enzyme properties. Normally, TPO consumes H2O2 produced by DUOX, decreasing the availability of this substance at the apical membrane of thyrocytes and, in turn, probably decreasing the oxidative damage of macromolecules. Copyright © 2010 by The Endocrine Society.
Belhaj A.,Center National Of Lenergie |
Segui A.,University of Zaragoza
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010
Using D-brane configurations on the K3 surface, we give six-dimensional type IIA stringy realizations of the Quantum Hall Effect (QHE) in 1+2 dimensions. Based on the vertical and horizontal lines of the K3 Hodge diamond, we engineer two different stringy realizations. The vertical line presents a realization in terms of D2 and D6-branes wrapping the K3 surface. The horizontal one is associated with hierarchical stringy descriptions obtained from a quiver gauge theory living on a stack of D4-branes wrapping intersecting 2-spheres embedded in the K3 surface with deformed singularities. These geometries are classified by three kinds of the Kac-Moody algebras: ordinary, i.e. finite dimensional, affine and indefinite. We find that no stringy QHE in 1+2 dimensions can occur in the quiver gauge theory living on intersecting 2-spheres arranged as affine Dynkin diagrams. Stringy realizations of QHE can be done only for the finite and indefinite geometries. In particular, the finite Lie algebras give models with fractional filling fractions, while the indefinite ones classify models with negative filling fractions which can be associated with the physics of holes in the graphene. © 2010.
Naji S.,Mohammed V University |
Naji S.,Ibb University |
Belhaj A.,Sultan Moulay Slimane University |
Labrim H.,Center National Of Lenergie |
And 5 more authors.
Journal of Physical Chemistry C | Year: 2014
Inspired by Lie symmetries, we study the electronic and magnetic properties of cobalt (Co) and nickel (Ni) adatom adsorption on the graphene material using density functional theory calculations. The system we consider here consists of a static single layer of graphene interacting with transition-metal (TM) atoms. This system shows a nice geometrical shape having a double hexagonal structure appearing in the G2 Lie algebra. This structure is associated with 25% concentration corresponding to a coverage of 0.666 monolayers placed at H sites. This new symmetry forces the derived Co material to behave like a ferromagnetic metal with a strong spin polarization. However, the derived Ni material remains a nonmagnetic metal. For the Co case, we show that the magnetic mechanism responsible for such behavior is the interaction between the Co atoms. In fact, there are two interaction types. The first one is associated with the direct interaction between the Co atoms, while the second one corresponds to the indirect interaction via the carbon atoms. Using Monte Carlo simulation, the Curie temperature for the Co material is estimated to be around 438 K. This value could be explored in nanomagnetic applications. © 2014 American Chemical Society.
Fahr M.,Mohammed V University |
Fahr M.,Center National Of Lenergie |
Fahr M.,Montpellier University |
Laplaze L.,Montpellier University |
And 6 more authors.
Frontiers in Plant Science | Year: 2013
Lead (Pb) is one of the most widespread heavy metal contaminant in soils. It is highly toxic to living organisms. Pb has no biological function but can cause morphological, physiological, and biochemical dysfunctions in plants. Plants have developed a wide range of tolerance mechanisms that are activated in response to Pb exposure. Pb affects plants primarily through their root systems. Plant roots rapidly respond either (i) by the synthesis and deposition of callose, creating a barrier that stops Pb entering (ii) through the uptake of large amounts of Pb and its sequestration in the vacuole accompanied by changes in root growth and branching pattern or (iii) by its translocation to the aboveground parts of plant in the case of hyperaccumulators plants. Here we review the interactions of roots with the presence of Pb in the rhizosphere and the effect of Pb on the physiological and biochemical mechanisms of root development. © 2013 Fahr, Laplaze, Bendaou, Hocher, El Mzibri, Bogusz and Smouni.
Ele Abiama P.,Institute of Geological and Mining Research |
Ele Abiama P.,University of Yaounde I |
Owono Ateba P.,University of Yaounde I |
Ben-Bolie G.H.,University of Yaounde I |
And 2 more authors.
Journal of Environmental Radioactivity | Year: 2010
The aim of this work is to determine the radioactivity concentration of 226Ra, 232Th and 40K in sub-surface (0-5cm) soil samples collected from Awanda, Bikoué, Ngombas in the southwestern region of Cameroon, to assess their contribution to the external dose exposure relative to the United Nation Scientific Committee on Effects of Atomic Radiation (UNSCEAR) data. An HPGe p-type detector coupled to a multichannel analyzer was used to perform measurements and data processing. The activity concentrations of 226Ra varied from 0.06±0.01 to 0.27±0.02kBqkg-1 with a mean value of 0.13±0.01kBqkg-1 wet weight. The activity concentrations of 232Th varied from 0.10±0.01 to 0.70±0.05kBqkg-1 with a mean value of 0.39±0.03kBqkg-1 wet weight, and 40K concentrations varied from 0.37±0.02 to 1.53±0.11 kBqkg-1 with a mean value of 0.85±0.07kBqkg-1 wet weight, respectively. The mean value of outdoor annual effective doses were estimated to be 0.48mSvy-1, 0.39mSvy-1 and 0.38mSvy-1 from Ngombas, Awanda and Bikoué, respectively. The studied areas can be said to have a high background radiation level. © 2010 Elsevier Ltd.
Berrada N.,Center National Of Lenergie
Cellular and molecular biology (Noisy-le-Grand, France) | Year: 2012
The CpG promoter methylation has been reported to occur frequently in bladder cancer. Moreover, analysis of gene methylation has been shown to be feasible from voided urine and can be detected with a high degree of sensitivity. The aim of this present study is to determine how methylation patterns of APC, RARβ and Survivin genes change during bladder carcinogenesis and to evaluate whether DNA methylation could be detected in urine sediment. Using the sensitive assay of MSP, we explored the promoter methylation status for the three genes in tumor specimens and urine sediment DNA from 32 bladder cancer patients. Methylation frequencies of the tested genes in tumor specimens were 100%, 75% and 84.4% for APC, RARβ and Survivin, respectively. Hypermethylation of APC was found in all pathological grades and stages of bladder cancer. More frequent promoter hypermethylation of RARβ and Survivin was observed in high grade tumors and the hypermethylation increased from low to high stages, but there was no significant correlation between stages/grades and hypermethylation of these two gene promoters. In order to investigate clinical usefulness for noninvasive bladder cancer detection, we further analyzed the methylation status in urine samples of bladder cancer patients. Methylation of the tested genes in urine sediment DNA was detected in the majority of cases that were hypermethylated in tumor samples (93.7%) and the frequencies were 79.3% 70.8% and 96.3% for APC, RARβ and Survivin, respectively. Our results indicate that methylation of APC, RARβ and Survivin gene promoters is a common finding in patients with bladder carcinoma. The ability to detect methylation not only in bladder tissue, but also in urine sediments, suggests that methylation markers are promising tools for noninvasive detection of bladder cancer.