892 research outputs found

    Effects of sulfonation process on thermal behavior and microstructure of sulfonated polysulfone membranes as a material for Proton Exchange Membrane (PEM)

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    This paper reports the effect of sulfonation processon thermal behavior and microstrucutre of sulfonated polysulfone membrane. Various degree of sulfonation reactin has been conducted and the sulfonated membranes were characterized by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), x-ray diffraction (XRD) and scanning electron microscopy (SEM). Modifications of the origin polysulfone polymer resulted in an increment value of glass transition temperature (Tg) due to the introduction of sulfonic acid group to the polymer backbone. However, due to some hindrance such as trace amount of organic solvent left during solvent evaporation and high hydrophilicity of the produced sulfonated membranes resulted in decreasing values of Tg. The polymer membrane showed lower degradation temperature as a function of degree of sulfonation. From XRD analysis, it was found that the membrane shows slight crystalline behavior after the sulfonation reaction. Detail discussions and observation of the alteration in microstructure of the sulfonated membrane were supported by SEM micrograph

    Some larval morphological characteristics of Camelostrongylus mentulatus and Nematodirus spathiger

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    Monitoring of gastrointestinal nematode parasites in ruminants (domestic and wild) is often based on fecal examination techniques, looking for excreted eggs and larval forms using morphological keys. These, are more available in domestic ruminants, in which helminths are widely studied, than in wild ruminants.  This study tried to provide certain morphological elements that will help to recognize the L3 larvae of Camelostrongylus mentulatus and Nematodirus spathiger that could parasite either domestic or wild ruminants. For that, we resorted first to the culture of L3 larvae from fecal samples taken from African antelopes, and second by the microscopic characterization of each isolated larval morphological pattern previously identified by sequencing of its internal transcribed spacer (ITS-2) regions of the ribosomal DNA. The results of different microscopic captured images showed that Camelostrongylus mentulatus larva is 16 intestinal cells that measuring approximately 820 ”m length, ‎≈ 25 ”m wide, and ‎≈ 47 ”m for its sheath tail extension and by this be closer to Teladorsagia circumcincta characteristics.  For Nematodirus spathiger, it possesses 8 gut cells and measuring about 1020 ”m long, ‎≈ 25 ”m wide, and‎ ≈ 143 ”m for its sheath tail extension with specific tail appendages. Have done this, we were able to get some clarifications on the morphology of the studied larvae, and we believe thus that this study will contribute to the establishment of morphological identification keys especially for parasitic nematodes of wild ruminants

    Fractional Statistics in terms of the r-Generalized Fibonacci Sequences

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    We develop the basis of the two dimensional generalized quantum statistical systems by using results on rr-generalized Fibonacci sequences. According to the spin value ss of the 2d-quasiparticles, we distinguish four classes of quantum statistical systems indexed by s=0,1/2:mod(1) s=0,1/2:mod(1), s=1/M:mod(1)s=1/M:mod(1), s=n/M:mod(1)s=n/M:mod(1) and 0≀s≀1:mod(1)0\leq s\leq 1:mod(1). For quantum gases of quasiparticles with s=1/M:mod(1)s=1/M:mod(1), M≄2,M\geq 2,, we show that the statistical weights densities ρM\rho_M are given by the integer hierarchies of Fibonacci sequences. This is a remarkable result which envelopes naturally the Fermi and Bose statistics and may be thought of as an alternative way to the Haldane interpolating statistical method.Comment: Late

    On Black Attractors in 8D and Heterotic/Type IIA Duality

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    Motivated by the study of black attractors in 8D supergravity with 16 supersymmetries, we use the field theory approach and 8D supersymmetry with non trivial central charges to shed light on the exact duality between heterotic string on T^2 and type IIA on real connected and compact surfaces {\Sigma}2. We investigate the two constraints that should be obeyed by {\Sigma}2 and give their solutions in terms of intersecting 2-cycles as well their classification using Dynkin diagrams of affine Kac-Moody algebras. It is shown as well that the moduli space of these dual theories is given by SO(1,1)x((SO(2,r+2))/(SO(2)xSO(r+2))) where r stands for the rank of the gauge symmetry G_{r} of the 10D heterotic string on T^2. The remarkable cases r=-2,-1,0 as well as other features are also investigated.Comment: LaTex, 18 pages, 2 figures, To appear in JHE

    Two Dimensional Fractional Supersymmetry from the Quantum Poincare Group at Roots of Unity

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    A group theoretical understanding of the two dimensional fractional supersymmetry is given in terms of the quantum Poincare group at roots of unity. The fractional supersymmetry algebra and the quantum group dual to it are presented and the pseudo-unitary, irreducible representations of them are obtained. The matrix elements of these representations are explicitly constructed.Comment: 10 pages. Some misprints are corrected. To appear in J. Phys.

    Mutation Symmetries in BPS Quiver Theories: Building the BPS Spectra

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    We study the basic features of BPS quiver mutations in 4D N=2\mathcal{N}=2 supersymmetric quantum field theory with G=ADEG=ADE gauge symmetries.\ We show, for these gauge symmetries, that there is an isotropy group GMutG\mathcal{G}_{Mut}^{G} associated to a set of quiver mutations capturing information about the BPS spectra. In the strong coupling limit, it is shown that BPS chambers correspond to finite and closed groupoid orbits with an isotropy symmetry group GstrongG\mathcal{G}_{strong}^{G} isomorphic to the discrete dihedral groups Dih2hGDih_{2h_{G}} contained in Coxeter(G)(G) with % h_{G} the Coxeter number of G. These isotropy symmetries allow to determine the BPS spectrum of the strong coupling chamber; and give another way to count the total number of BPS and anti-BPS states of N=2\mathcal{N}=2 gauge theories. We also build the matrix realization of these mutation groups GstrongG% \mathcal{G}_{strong}^{G} from which we read directly the electric-magnetic charges of the BPS and anti-BPS states of N=2\mathcal{N}=2 QFT4_{4} as well as their matrix intersections. We study as well the quiver mutation symmetries in the weak coupling limit and give their links with infinite Coxeter groups. We show amongst others that Gweaksu2\mathcal{G}_{weak}^{su_{2}} is contained in GL(2,Z){GL}({2,}\mathbb{Z}) ; and isomorphic to the infinite Coxeter I2∞{I_{2}^{\infty}}. Other issues such as building G\mathcal{G}%_{weak}^{so_{4}} and Gweaksu3\mathcal{G}_{weak}^{su_{3}} are also studied.Comment: LaTeX, 98 pages, 18 figures, Appendix I on groupoids adde

    Kyste neurentĂ©rique intra dural extra mĂ©dullaire: Ă  propos d’un cas

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    Le kyste neurentĂ©rique (KNE) est une malformation congĂ©nitale rare du systĂšme nerveux central (SNC) entrant dans le cadre des notochordodysraphies. Nous rapportons un nouveau cas de KNE de localisation intra durale extra mĂ©dullaire chez un patient de 16 ans, admis dans un tableau de compression mĂ©dullaire cervicale haut Ă©voluant depuis 4 mois. L’imagerie a objectivĂ© une lĂ©sion kystique prĂ© mĂ©dullaire en regardde C1-C2-C3. Le patient a bĂ©nĂ©ficiĂ© d’une Ă©vacuation kystique et l’histologie avait conclu Ă  un kyste neurentĂ©rique. L’évolution Ă©tait marquĂ©e par le dĂ©cĂšs du patient par des complications neurovĂ©gĂ©tatives graves. MalgrĂ© sa bĂ©nignitĂ© histologique, le kyste neurentĂ©rique de localisation cervicale haute peut se compliquer de troubles neurovĂ©gĂ©tatifs parfois imprĂ©visibles pouvant aboutir Ă  une Ă©volution dramatique
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