Entomopathogenic fungus Beauveria: Host specificity, ecology and significance of morpho-molecular characterization in accurate taxonomic classification

Abdessamad Imoulan,Muzammil Hussain,Paul M. Kirk,Abdellatif El Meziane,Yi-Jian Yao 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.4

Beauveria species are the most common cosmopolitan insect-pathogenic fungi which parasitize over 700 insect species. Since the establishment of the Beauveria genus in 1912 by Vuillemin, its taxonomy status was relied particularly on classical morphological characters. Although easily distinguishable as a genus, species identification remains definitely complicated because of the lack of distinctive morphological features. Furthermore, the extensive overlap in conidia shape and dimensions among Beauveria species has limited their utility as key taxonomic structures. Species identification using only ITS region of rDNA as a DNA barcode reached its resolution limit within Beauveria. Recently, there is a tendency to move towards an integrative multi-locus delimitation system for closely related species. Up until now, a total of 17 Beauveria species have been established essentially reliant on the multi-genes barcode approach of four nuclear genes, i.e., RPB1, RPB2, TEF-1α and intergenic Bloc, adapting genealogical concordance phylogenetic species recognition criterion. This report reviews the taxonomic history of Beauveria species using both morphological and molecular data over the past century.

Neutron activation analysis: Modelling studies to improve the neutron flux of Americiume-Beryllium source

Abdessamad Didi,Ahmed Dadouch,Otman Jaï,Jaouad Tajmouati,Hassane El Bekkouri 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.4

Americiumeberyllium (Am-Be; n, γ) is a neutron emitting source used in various research fields such as chemistry, physics, geology, archaeology, medicine, and environmental monitoring, as well as in the forensic sciences. It is a mobile source of neutron activity (20 Ci), yielding a small thermal neutron flux that is water moderated. The aim of this study is to develop a model to increase the neutron thermal flux of a source such as Am-Be. This study achieved multiple advantageous results: primarily, it will help us perform neutron activation analysis. Next, it will give us the opportunity to produce radio-elements with short half-lives. Am-Be single and multisource (5 sources) experiments were performed within an irradiation facility with a paraffin moderator. The resulting models mainly increase the thermal neutron flux compared to the traditional method with water moderator.

FACTORS EXPLAINING THE ATTRACTIVENESS OF TOURISM: TOWARDS A SINGLE EXPLANATORY MODEL? THE CASE OF THE MEDITERRANEAN BASIN

Nathalie Montargot,Abdessamad Ouchen 글로벌지식마케팅경영학회 2018 Global Marketing Conference Vol.2018 No.07

This study tries to explain through a single model the number of tourist arrivals, using “the human development index” and “the political stability and absence of violence/terrorism index”, for a panel of Mediterranean countries. The sample is composed of seven countries in the Mediterranean region, namely: France, Spain, Italy, Egypt, Morocco, Croatia and Tunisia. In order to explain the attractiveness of tourism, Ritchie and Zins (1978) attached great importance to social and cultural characteristics and to attitude towards tourists. These two attributes are intimately linked to the explanatory variables of our model. These explanatory variables also have common dimensions regarding the three following attributes: hosting infrastructure, destination culture and reception of the local population and security, Ritchie and Zins (1978), Kim (1998), Gallarza et al. (2002), Enright and Newton (2004), Cracolici and Nijkamp (2008) and Jin et al. (2012) consider them as strong attributes of tourist attractiveness. Our panel data model includes the Travel and Tourism Competitiveness Index (TTCI) (2013). This index essentially takes into account the following dimensions: safety and security, health and hygiene, education, training and availability of skilled workers. These dimensions are fully reflected in the two explanatory variables of our model: the index of political stability and absence of violence / terrorism and the index of human development. However, our research is original in comparison with the World Economic Forum's (2013) Travel and Tourism Competitiveness Index (TTCI). Indeed, the econometric model of panel data, presents the advantage of simultaneously studying several countries over a period and using homogeneity and Hausman tests. It constitutes a practical tool to build a single model, valid for several countries and useful forecasting tourist flows. Validated on a statistical and econometric basis with a good predictive quality, our panel data model, i.e. the random effect model, shows that the political stability and absence of violence/terrorism and the human development indexes act positively on the number of tourist arrivals. Thus, it considers safety and security, health and hygiene, education, training and availability of skilled workers and standard of living, as strong attributes to explain the attractiveness of a country.

A New Approach to Analyse the Consolidation of Soft Soils Improved by Vertical Drains and Submitted to Progressive Loading

Fouzia Kassou,Jamal Benbouziyane,Abdessamad Ghafiri,Abdelhak Sabihi 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.1

Prefabricated vertical drains combined with preloading and staged construction is a frequently used technique to accelerate consolidation in soft soils. Nevertheless, an installed vertical drain discharge capacity rapidly reduces over consolidation. Most reasons are the lateral confining pressure, the drain deformation and filter clogging. This greatly affects the rate of consolidation by increasing well resistance. This article presents an exact solution under equal-strain consolidation case of progressive loading. Total vertical stress increase caused by loading is principally modelled as a linear curve depending on time and depth. The discharge capacity of the drain is supposed to lower linearly with depth and inversely with time. The smear effect is also considered by assuming constant permeabilities of the soil in both smear zone and undisturbed zone. Excess pore-water pressure at any arbitrary point in soil is assessed, and the global average degree of consolidation is found. Comparisons are made with an available solution from the literature. The suggested solution is then applied to three pre-loading embankments of the Moroccan high-speed railway project. A good agreement is found between the solution and measured data from field monitoring.

Study of the ageing mechanisms of activated carbon supercapacitors by electrothermal simulation and experimental analysis

Erradi Amine,Touhtouh Samira,El Ballouti Abdessamad,Hajjaji Abdelowahed 한국탄소학회 2021 Carbon Letters Vol.31 No.6

In view of the growing need for clean energy, supercapacitors (SC), especially those based on activated carbon (AC) and organic electrolyte are attracting great attention for their theoretically infnite life span. However, they still age much faster than expected due to certain mechanisms. Several researches is being conducted to understand these mechanisms, but so far, the chemical reactions at the phase boundary of the activated carbon electrodes and organic electrolyte have been very unclear. Some pathways have not yet been investigated; there is no research on the reactions that can take place between acetonitrile in the vapor phase and the oxides presented on the surface of activated carbons. For this reason, in this study, divided into two parts, the frst based on a thermal simulation and the second based on an experimental study, we have systematically described the ageing mechanisms by determining the gas-phase reactions that can occur at the electrode–electrolyte interface. On the one hand, a thermal model of a supercapacitor cell using activated carbon and organic electrolyte technology has been developed. This model allowed us to study the temperature distribution of supercapacitors, and thus to determine the thermodynamic parameters related to the phenomena produced at the electrode–electrolyte interface. On the other hand, a thermo-gravimetric analysis coupled with gas phase infrared spectroscopy on the activated carbons of an aged supercapacitor of the same technology as that used in the simulation was carried out. The results obtained made it possible to identify the chemical groups produced by ageing.

On the Maximal Output Admissible Set for a Class of Bilinear Discrete-time Systems

Youssef Benfatah,Amine El Bhih,Mostafa Rachik,Abdessamad Tridane 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.11

Given a discrete-time controlled bilinear systems with initial state x0 and output function yi, we investigate the maximal output set Θ(Ω) = {x0 ∈ Rn, yi ∈ Ω, ∀ i ≥ 0} where Ω is a given constraint set and is a subset of Rp. Using some stability hypothesis, we show that Θ(Ω) can be determined via a finite number of inequations. Also, we give an algorithmic process to generate the set Θ(Ω). To illustrate our theoretical approach, we present some examples and numerical simulations. Moreover, to demonstrate the effectiveness of our approach in real-life problems, we provide an application to the SI epidemic model and the SIR model.

Pro-Apoptotic and Immunostimulatory Tetrahydroxanthone Dimers from the Endophytic Fungus Phomopsis longicolla

Rö,nsberg, David,Debbab, Abdessamad,Má,ndi, Attila,Vasylyeva, Vera,Bö,hler, Philip,Stork, Bjö,rn,Engelke, Laura,Hamacher, Alexandra,Sawadogo, Richard,Diederich, Marc,Wray, Vict American Chemical Society 2013 Journal of organic chemistry Vol.78 No.24

<P>Four tetrahydroxanthone dimers (<B>1</B>–<B>4</B>) and four biogenetically related monomers (<B>5</B>–<B>8</B>), including the new derivatives <B>4</B>–<B>6</B>, were isolated from the endophyte Phomopsis longicolla. The absolute configurations of <B>2</B>–<B>4</B> were established for the first time by TDDFT electronic circular dichroism calculations, and that of phomoxanthone A (<B>1</B>) was revised by X-ray crystallography. Phomoxanthone A (<B>1</B>) showed the strongest pro-apoptotic activity when tested against a panel of human cancer cell lines, including cisplatin-resistant cells, whereas it was up to 100-fold less active against healthy blood cells. It was also the most potent activator of murine T lymphocytes, NK cells, and macrophages, suggesting an activation of the immune system in parallel to its pro-apoptotic activity. This dual effect in combating cancer cells could help in fighting resistance during chemotherapy. Preliminary structure–activity studies of isolated compounds and derivatives obtained by semisynthesis (<B>9a</B>–<B>11</B>) hinted at the location of the biaryl axis and the presence of acetyl groups as important structural elements for the biological activity of the studied tetrahydroxanthones.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2013/joceah.2013.78.issue-24/jo402066b/production/images/medium/jo-2013-02066b_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo402066b'>ACS Electronic Supporting Info</A></P>

Protein Kinase and HDAC Inhibitors from the Endophytic Fungus <i>Epicoccum nigrum</i>

El Amrani, Mustapha,Lai, Daowan,Debbab, Abdessamad,Aly, Amal H.,Siems, Karsten,Seidel, Carole,Schnekenburger, Michael,Gaigneaux, Anthoula,Diederich, Marc,Feger, Daniel,Lin, Wenhan,Proksch, Peter American Chemical Society and American Society of 2014 Journal of natural products Vol.77 No.1

<P>A chemical investigation of the endophytic fungus <I>Epicoccum nigrum</I> isolated from leaves of <I>Mentha suaveolens</I> collected in Morocco resulted in the isolation of five new polyketides, epicocconigrones A and B (<B>1</B> and <B>2</B>), 3-methoxyepicoccone B (<B>3</B>), 3-methoxyepicoccone (<B>4</B>), and 2,3,4-trihydroxy-6-(methoxymethyl)-5-methylbenzaldehyde (<B>5</B>), together with five known compounds (<B>6</B>–<B>10</B>). The structures of the new compounds were unambiguously determined by extensive analysis of the 1D and 2D NMR and mass spectroscopic data. Compounds <B>1</B> and <B>10</B> showed potent inhibition of at least 15 protein kinases with IC<SUB>50</SUB> values ranging from 0.07 to 9.00 μM. Moreover, compounds <B>1</B> and <B>10</B> inhibited histone deacetylase (HDAC) activities with IC<SUB>50</SUB> values of 9.8 and 14.2 μM, respectively. A preliminary structure–activity relationship is discussed. Interestingly, compounds <B>1</B> and <B>10</B> exert mainly cytostatic effects in human lymphoma RAJI and U-937 cell lines.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jnprdf/2014/jnprdf.2014.77.issue-1/np4005745/production/images/medium/np-2013-005745_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/np4005745'>ACS Electronic Supporting Info</A></P>

Friction and wear performance of disc brake pads and pyroelectric energy harvesting

Yassine Tabbai,Amine Alaoui-Belghiti,Reddad El Moznine,Fouad Belhora,Abdelowahed Hajjaji,Abdessamad El Ballouti 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.2

Due to the perpetual development of new technologies in the transportation industry, vehicles become more powerful and faster. As a result, the braking systems have to simultaneous follow this same rate of progression. The brake, a major safety organ, gets significant interest of engineers and researchers. The main purpose of this paper is to present a study based on numerical modelling coupling the thermodynamic and the thermoelectrical behaviours of an automobile brake disc for the prediction of the wear of disc brake pads and the time to be changed, as well as the harvesting of the thermal energy resulting from the braking operation. Firstly, an analysis of the thermal phenomena operating in a brake disc in service (heat fl ow generated by friction, high thermal gradients, temperature rise, and the speed of rotation of the disc) is presented. The proposed modelling is carried out taking into account the influence of different parameters such as the type of braking, the cooling mode, and the design materials. Then, the studies are focused on the use of a smart material for heat recovery due to the contact between the disc and the pads, this material has a capability of converting thermal energy into exploitable electric energy, as a consequence, we can predict the state of health and proper time to change the pads. This study is based on the pyroelectric effect, for a good prediction of the proper time to change the pads. The magnitudes of the voltage generated and the energy density harvested are shown as a function of the pads thicknesses, the speed and the temperature traversed by the pyroelectric material PZT.