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M. Samet G. Boiteux G. Seytre A. Kallel A. Serghei 《Colloid and polymer science》2014,292(8):1977-1988
The dielectric properties of composite materials consisting of a host matrix filled with spherical particles are investigated as a function of frequency by means of numerical calculations. Two different cases are analyzed: (a) composites with a conductive matrix and insulating fillers and (b) composites with an insulating matrix and conductive fillers. In both situations, dielectric dispersions due to interfacial polarization effects are observed in the dielectric spectra. In the present contribution, the characteristic frequencies of interfacial polarization effects are systematically analyzed in dependence on the volume fraction of the spherical fillers and on the conductivity values of the composite phases. The resulting scaling laws are discussed in detail. 相似文献
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Soraa Bouattour Wannes Kallel Ana Maria Botelho do Rego L.F. Vieira Ferreira I. Ferreira Machado Sami Boufi 《应用有机金属化学》2010,24(10):692-699
This work reports on the synthesis of Li‐doped TiO2 nanoparticles using the sol–gel process and solid‐state sintering, and investigates their potential use as a photocatalyst for degradation under sunlight excitation of different organic model compounds in aqueous solution. The structure of the nanocrystals was examined by X‐ray diffraction, UV‐vis ground state diffuse reflectance absorption spectra and X‐ray photoelectron emission spectroscopy. Results showed that samples prepared by sol–gel process and calcined at 400 °C are composed of a mixture of anatase and rutile phases, in contrast to the one prepared by solid‐state sintering, which exhibits an anatase phase with Li being involved in a spinel phase. The photocatalytic degradation of aqueous solutions of different aromatic compounds was successfully achieved under sunlight excitation in presence of Li‐doped TiO2 prepared via sol–gel process. It was shown that the calcination temperature and the preparation mode greatly affect the photocatalytic efficiency. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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We relate the brace products of a fibration with section tothe differentials in its Serre spectral sequence. In the particularcase of free loop fibrations, we establish a link between thesedifferentials and Browder operations in the fiber. Applicationsand several calculations (for the particular cases of spheresand wedges of spheres) are given. 2000 Mathematical SubjectClassification: 55P35, 55Q15, 55R05, 55R20. 相似文献
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Saoussen Turki Atef Ayed Néjib Chalghoumi Frederic Weekers Philippe Thonart Héla Kallel 《Applied biochemistry and biotechnology》2010,160(5):1371-1385
Yarrowia lipolytica LgX64.81 is a non-genetically modified mutant that was previously identified as a promising microorganism for extracellular
lipase production. In this work, the development of a fed-batch process for the production of this enzyme in this strain was
described. A lipolytic activity of 2,145 U/mL was obtained after 32 h of batch culture in a defined medium supplemented with
10 g/L of tryptone, an enhancer of lipase expression. To maximize the volumetric productivity, two different fed-batch strategies
had been investigated. In comparison to batch process, the intermittent fed-batch strategy had not improved the volumetric
lipase productivity. In contrast, the stepwise feeding strategy combined with uncoupled cell growth and lipase production
phases resulted in a 2-fold increase in the volumetric lipase productivity, namely, the lipase activity reached 10,000 U/mL
after 80 h of culture. Furthermore, this lipase was purified to homogeneity by anion exchange chromatography on MonoQ resin
followed by gel filtration on Sephacryl S-100. This process resulted in an overall yield of 72% and a 3.5-fold increase of
the specific lipase activity. The developed process offers a great potential for an economic production of Lip2 at large scale
in Y. lipolytica LgX64.81. 相似文献
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Samir Kallel 《Potential Analysis》2014,41(1):143-169
In this work we consider the Dunkl operator on the real line, defined by $$ {\cal D}_kf(x):=f'(x)+k\dfrac{f(x)-f(-x)}{x},\,\,k\geq0. $$ We define and study Dunkl–Sobolev spaces \(L^p_{n,k}(\mathbb{R})\) , Dunkl–Sobolev spaces \({\cal L}^p_{\alpha,k}(\mathbb{R})\) of positive fractional order and generalized Dunkl–Lipschitz spaces \(\wedge^k_{\alpha,p,q}(\mathbb{R})\) . We provide characterizations of these spaces and we give some connection between them. 相似文献
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Abstract [(CH3)4N]2cdI4 exhibits a phase transition at 233 K from Pnma to P2 1/c as shown by single-crystal X-ray measurements and differential scanning calorimetry. The observed entropy change amounts to approximately 8.4 J.mole?1 K?1 and the spontaneous strain is about – 18.10?3. The symmetry change can be interpreted in the framework of the Landau theory. 相似文献
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R. Ben Hassen A. Ben Salah A. Kallel A. Daoud J. Jaud 《Journal of chemical crystallography》2002,32(11):427-430
CH3NH3CdBr3 crystallizes in the space group Ccm21, a = 13.693(1) Å, b = 7.906(1) Å, c = 6.886(1) Å, V = 745.46(15) Å3, Z = 4, D
x
= 3.42 Mg m–3. The structure of the title compound is one-dimensional consisting of infinite chains made of face sharing CdBr6 octahedra. The methylammonium groups are situated in the space between chains. The cations and anions are joined by hydrogen bonding. 相似文献
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