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Samira Benmouloud Rachid Echarghaoui Si. Mohammed Sbaï 《Journal of Mathematical Analysis and Applications》2012,396(1):375-385
In this paper, by using the Lusternik–Schnirelmann category, we obtain a multiplicity result for a quasilinear elliptic system with both concave and convex nonlinearities and critical growth terms in bounded domains. 相似文献
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Jallal Zoubir Chaimae Radaa Nadia Bougdour Abderrahim Idlahcen Widad El Hayaoui Naoual Tajat Wail El Mouhri Iliass Nadif Samir Qourzal Malika Tamimi Ali Assabbane Idriss Bakas 《印度化学会志》2022,99(8):100590
Nitrofurazone is a nitrofuran-family synthetic chemical that has been used to treat bacterial infections since 1993. Silver nanoparticles synthesized by the thermal technique on graphite carbon sheets under optimal conditions were used to develop a highly sensitive electrochemical sensor. The main experimental characteristics are optimized to assure that this sensor functions correctly. Scanning electron microscope, X-ray diffraction, infrared spectroscopy were used to determine the chemical composition and morphology of the prepared pastes. With a maximal reduction peak of La nitrofurazone observed at ?0.57V/Ag-NPs@CPE versus Ag/AgCl, this sensor demonstrated good electrocatalytic activity for the reduction of La nitrofurazone. The influence of phosphate buffer solution pH indicates that the numbers of protons and electrons in the reaction at the surface of our constructed sensor were the same. The LOD and LOQ were calculated to be 1.2 × 10?8 M and 1.3 × 10?7 M, respectively. Using the differential pulse voltammetry technique, the calibration curve was established in the concentration range of 10?4 M to 2 × 10?7 M. Our Ag-NPs@CPE sensors were evaluated in order to detect nitrofurazone in real contaminated samples tap water, commercial milk, and human urine, in particular. The electroanalysis results show a very high recovery rate of more than 96% on average, permitting us to determine that our sensors are functional under optimum working conditions. 相似文献
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M'Hamed Esseffar Malika El Messaoudi Widad Bouab 《Journal of Physical Organic Chemistry》2009,22(10):913-918
Intermolecular charge‐transfer (CT) spectra of 3‐thioxo‐5‐oxo‐, 5‐thioxo‐3‐oxo‐, and 3,5‐dithioxo‐ derivatives of 2,7‐dimethyl‐[1,2,4]‐triazepine 1:1 molecular complexes with molecular iodine were studied in the UV‐visible region. Equilibrium constants and free energy changes of the formed complexes were determined in solution. Ab initio calculations at HF/LANL2DZ* and MP2/LANL2DZ* were carried out to establish the nature of the complexation site, to determine the complex structures, and to examine the basicity of these compounds toward molecular iodine. The 3,5‐dithioxo‐2,7‐dimethyl‐[1,2,4]‐triazepine is the most basic one toward molecular iodine. In all cases, the complexation takes place at the heteroatom attached to position 3 of the triazepine. Hence, although in general, thiocarbonyls are stronger bases than carbonyls in the gas phase, 5‐thioxo‐2,7‐dimethyl‐[1,2,4]‐triazepin‐3‐one behaves as an oxygen base towards I2. Experimental free energies in solution and gas‐phase computational values are linearly correlated. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Aggregation of hydrophobically modified polysaccharides in solution and at the air-water interface 总被引:3,自引:0,他引:3
Henni W Deyme M Stchakovsky M LeCerf D Picton L Rosilio V 《Journal of colloid and interface science》2005,281(2):316-324
The present article focuses on the comparative study of physicochemical properties of two ionic pullulan derivatives modified by 10 or 35 C8 chains per 100 anhydroglucose units, named CMP10C8 and CMP35C8, respectively. In aqueous solutions, these derivatives exhibited an associative behavior as evidenced by pyrene fluorescence spectroscopy. This phenomenon, which stems from intra- and/or intermolecular interactions between the hydrophobic groups grafted on the polymer backbone, results in the formation of more or less condensed aggregates depending on the C8 ratio and the ionic strength of the media. The hydrophobically modified pullulans also displayed surface properties. Their adsorption at the air-solution interface was assessed from surface tension measurements. The results showed that both hydrophobized polymers adsorb in a coil conformation occupying a large interfacial molecular area. The comparison of these molecular areas indicated that CMP35C8 adopts a more shrunken conformation at the interface than CMP10C8, due to stronger intramolecular interactions. The stability of the adsorbed monolayer under bulk dilution was investigated by ellipsometric measurements. Whereas bulk dilution had no effect on the stability of the adsorbed CMP35C8 film, it provoked significant changes in the adsorbed CMP10C8 monolayer. The stability of the CMP35C8 monolayers was attributed to the existence of intermolecular associations between the adsorbed coils. 相似文献
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Influence of alkyl chains length on the conformation and solubilization properties of amphiphilic carboxymethylpullulans 总被引:1,自引:0,他引:1
Widad Henni-Silhadi Michel Deyme Marta Ruiz de Hoyos Didier Le Cerf Luc Picton Véronique Rosilio 《Colloid and polymer science》2008,286(11):1299-1305
The existence of inter- and/or intramolecular interactions in aqueous solutions of hydrophobically modified polysaccharides
induces specific macromolecular conformations at the air–solution interface and in the bulk, where hydrophobic microdomains
may be formed. The present work focuses on the interfacial and solubilizing properties of amphiphilic pullulans (CMP12C8, CMP7C14, and CMP4C16) differing in the length and percentage of alkyl chains grafted to the anhydroglucose units. The surface tension studies
of these polymers evidence a marked difference between the interfacial properties of CMP12C8 on one hand and those of CMP7C14 and CMP4C16 on the other hand. Pyrene fluorescence spectroscopy and benzophenone solubilization experiments demonstrate a similar partition.
Increasing alkyl chains length from eight up to 14 or 16 carbons improves the solubilization properties of nonpolar molecules,
even though at the same time, the average number of grafted chains per 100 anhydroglucose units is decreased from 12 down
to seven and four for the three compounds, respectively. 相似文献
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Widad Bouamama 《Rendiconti del Circolo Matematico di Palermo》2004,53(3):313-324
Résumé Les opérateurs pseudo-Fredholm ont été introduits et étudiés par M. Mbekhta dans le cas des espaces de Hilbert. Dans ce travail
on se propose d’étendre l’étude de cette classe au cadre plus général des espaces de Banach. Notamment, nous montrons que
cette classe reste stable par des petites perturbations. Ce dernier résultat donne une généralisation à un Théorème de P.
Aiena et M. Mbekhta
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