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)
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
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, ââ 25 ”m wide, and ââ 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, ââ 25 ”m wide, andâ â 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
We develop the basis of the two dimensional generalized quantum statistical
systems by using results on -generalized Fibonacci sequences. According to
the spin value of the 2d-quasiparticles, we distinguish four classes of
quantum statistical systems indexed by , ,
and . For quantum gases of quasiparticles
with , , we show that the statistical weights densities
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
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
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
We study the basic features of BPS quiver mutations in 4D
supersymmetric quantum field theory with gauge symmetries.\ We show,
for these gauge symmetries, that there is an isotropy group
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 isomorphic to the discrete
dihedral groups contained in Coxeter with 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 gauge theories. We
also build the matrix realization of these mutation groups from which we read directly the electric-magnetic
charges of the BPS and anti-BPS states of QFT 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 is contained in
; and isomorphic to the infinite Coxeter
. Other issues such as building
and are also
studied.Comment: LaTeX, 98 pages, 18 figures, Appendix I on groupoids adde
Kyste neurentĂ©rique intra dural extra mĂ©dullaire: Ă propos dâun cas
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. Lâimagerie a objectivĂ© une lĂ©sion kystique prĂ© mĂ©dullaire en regardde C1-C2-C3. Le patient a bĂ©nĂ©ficiĂ© dâune Ă©vacuation kystique et lâhistologie avait conclu Ă un kyste neurentĂ©rique. LâĂ©volution 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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