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排序方式: 共有129条查询结果,搜索用时 31 毫秒
1.
Anderson PE Badlani RN Mayer J Mabrouk PA 《Journal of the American Chemical Society》2002,124(35):10284-10285
This contribution reports the first synthesis of conducting polymers (CPs), specifically, polyaniline (PAn) and polypyrrole (PPy), in supercritical carbon dioxide (scCO2). CPs synthesized electrochemically in scCO2 were characterized with cyclic voltammetry (CV), four-point probe conductivity, scanning electron microscopy (SEM), and UV-vis spectroscopy. Preliminary data indicate that CPs synthesized by this method exhibit novel morphology and high conductivity comparable to that synthesized by traditional methods. 相似文献
2.
I. S. Shehatta A. M. Hassanein E. M. Mabrouk 《Monatshefte für Chemie / Chemical Monthly》1995,126(8-9):851-862
Summary UV spectra, dc polarograms, cyclic voltammetry and coulometry measurements of salicylaldehyde-4-(2-pyridyl)-3-thiosemicarbazone (H2
SPT) were recorded inBritton-Robinson buffer solutions ofpH 2–12. The dissociation constants of H2
SPT evaluated spectrophotometrically and potentiometrically in a 5% (v/v)DMF-water mixture are concordant. The dc-polarograms in solutions ofpH<8.5 exhibit a single 4-electron diffusion-controlled polarographic wave, whereas in solutions ofpH>8.5 two waves are observed. The cyclic voltammograms give a single cathodic peak in acidic and neutral solutions, whereas two cathodic peaks can be identified in alkaline ones. An electrode mechanism is proposed and discussed. The effect of temperature on the dissociation constants and the polarographic data was also investigated; the corresponding thermodynamic parameters were derived and are discussed.
Thermodynamische und voltammetrische Untersuchungen an Salicylaldehyd-4-(2-pyridyl)-3-thiosemicarbazon
Zusammenfassung UV-Spektroskopische, dc-polarographische, voltammetrische und coulometrische Messungen an Salicylaldehyd-4-(2-pyridyl)-3-thiosemicarbazon (H2 SPT) inBritton-Robinson-Pufferlösungen (pH 2–12) wurden durchgeführt. Die spektrophotometrisch und potentiometrisch ermittelten Dissoziationskonstanten von H2 SPT in 5% (v/v)DMF/Wasser stimmen überein. In Lösungen mit einempH-Wert unter 8.5 zeigen die dc-Polarogramme eine einzelne diffusionskontrollierte polarographische Welle (4e–), während in Lösungen mit einempH-Wert von über 8.5 zwei Wellen zu beobachten sind. Die cyclischen Voltammogramme weisen in sauren und neutralen Lösungen einen, in basischen Lösungen hingegen zwei kathodische Peaks auf. Ein Elektrodenmechanismus wird vorgeschlagen und diskutiert. Der Effekt der Temperatur auf die Dissoziationskonstanten und die polarographischen Ergebnisse wurde ebenfalls untersucht. Die entsprechenden thermodynamischen Größen wurden bestimmt und werden diskutiert.相似文献
3.
A Pluta polarizing interference microscope with a fibre stretching device attached was used to detect the changes in molecular structure that occur during the fibre cold drawing process. Fibres drawn with low draw ratios show different types of deformation mechanisms. The interference patterns recorded at different draw ratios are used to relate the deformation mechanisms with the measured structural parameters. Some optical parameters are measured such as; refractive indices nand n birefringence n, the polarizability per unit volume , the orientation distribution function f(θ), the angle θ between the stretching direction and the chain axis, and the angle θm which the transition dipole moment of the molecular species makes with the molecular axis (chain axis). Three polymeric fibres (Polyethylene terephthalate PET, Polypropylene PP and Polyamide PA) were used in this study and their interferograms are illustrated. 相似文献
4.
Ayman Ben Mabrouk Hamid Kaddami Sami Boufi Fouad Erchiqui Alain Dufresne 《Cellulose (London, England)》2012,19(3):843-853
The microstructure and chemical composition of alfa (Stipa tenacissima) were investigated. The polysaccharide and lignin contents were around 70 and 20 wt%, respectively. From the bleached and
delignified fibers, two types of nanosized cellulosic particles were extracted, namely cellulose nanocrystals and microfibrillated
cellulose (MFC). The former correspond typically to the elementary crystallite units of the cellulose fibers, with a rod-like
morphology and an aspect ratio of about 20. The latter, mechanically disintegrated from oxidized bleached fibres, presents
an entangled fibrillar structure with widths in the range 5-20 nm. The reinforcing potential of the ensuing nanoparticles
was investigated by casting a mixture of acrylic latex and aqueous dispersion of cellulose nanoparticles. Thermo-mechanical
analysis revealed a huge enhancement of the stiffness above the glass transition of the matrix. Significant differences in
the mechanical reinforcing capability of the nanoparticles were reported. 相似文献
5.
Majdi Mabrouk Mickael Marchand Jean-Marie Baronnet Florent Lemont 《Plasma Chemistry and Plasma Processing》2016,36(4):1085-1110
This work deals with incineration of organic liquid wastes using an oxygen thermal plasma jet, submerged in water. The results presented here concern incineration of trichloroethylene (TCE). During a trial run, the CO2 and CO content in the exhaust gas is continuously measured; samples taken periodically from the solution are analyzed by appropriate methods: total organic carbon and chlorine content are measured. Process efficiency during tests with a few L/h of TCE is given by the mineralization rate. The trapping rate of chlorine as HCl is near 100 %. The TCE destruction and removal efficiency, measured by MS/GC, is better than 99.9999 %. A simplified kinetic model of gas quenching was constructed from a single-phase plug-flow reactor model taking into account 14 species and 34 reactions. It satisfies the requirements of heat balance and major components analysis, and reveals the major role of the OH radical on the concentrations of CO as well as HCl and/or Cl2 in the off-gas stream. 相似文献
6.
Walid Mabrouk Ridha Lafi Jean Franois Fauvarque Amor Hafiane Cyrille Sollogoub 《先进技术聚合物》2021,32(1):304-314
The purpose of this work is to study the desalination of brackish water using a new ion exchange membrane, made from sulfochlorated polyethersulfone (Cl‐PES), and crosslinked using aminated polyethersulfone (NH2‐PES) as a crosslinking reagent. This membrane, named ClNH2 membrane, has been obtained by reaction between Cl‐PES with 1.3 SO2Cl groups per monomer unit and 0.2 equivalent amount of NH2‐PES. ClNH2 membrane has been characterized in terms of contact angle, transport number, intrinsic conductivity, and water uptake (as a function of temperature). Electrodialysis performances of the newly synthetized membranes have been measured using an electrodialysis cell at a laboratory scale and compared to commercial membranes. All the experiments have been performed using synthetic brackish water solutions prepared from sodium chloride salts with different concentrations (varying from 0.5 to 5.0 g/L). The concentration of different water samples obtained has been found to be below the amount recommended by the World Health Organization (WHO) for drinking water. 相似文献
7.
We compute the asymptotic wave profiles for the exterior problemin elasticity with homogeneous Neumann condition. We give preciseresults on the asymptotic distribution of the elastic energyin various subsets of space. These results are obtained viathe use of a recently developed extension of the scatteringtheory of C. Wilcox (Mabrouk & Helali, 2002). 相似文献
8.
Khalifa El Mabrouk 《Potential Analysis》2003,19(4):399-400
Volume Contents
Volume Contents 相似文献9.
We consider the homogenization of a time-dependent heat transfer problem in a highly heteregeneous periodic medium made of two connected components having finite heat capacities cα(x) and heat conductivities aα(x), α=1,2, of order one, separated by a third material with thickness of order ε the size of the basic periodicity cell, but with conductivity λa3(x) where a3=O(1) and λ tends to zero with ε. Assuming only that ci(x)?0 a.e., such that the problem can degenerate (parabolic-elliptic), we identify the homogenized problem following the values of δ=limε→0ε2/λ. To cite this article: M. Mabrouk, A. Boughammoura, C. R. Mecanique 331 (2003). 相似文献
10.
A simple, rapid, and sensitive RP-HPLC method using photodiode array detection was developed and validated for the simultaneous determination of granisetron hydrochloride, 1-methyl-1H-indazole-3-carboxylic acid (the main degradation product of granisetron), sodium benzoate, methylparaben, propylparaben, and 4-hydroxybenzoic acid (the main degradation product of parabens) in granisetron oral drops and solutions. The separation of the compounds was achieved within 8 min on a SymmetryShield RP18 column (100 x 4.6 mm id, 3.5 microm particle size) using the mobile phase acetonitrile--0.05 M KH2PO4 buffered to pH 3 using H3PO4 (3+7, v/v). The photodiode array detector was used to test the purity of the peaks, and the chromatograms were extracted at 240 nm. The method was validated, and validation acceptance criteria were met in all cases. The robust method was successfully applied to the determination of granisetron and preservatives, as well as their degradation products in different batches of granisetron oral drops and solutions. The method proved to be sensitive for determination down to 0.04% (w/w) of granisetron degradation product relative to granisetron and 0.03% (w/w) 4-hydroxybenzoic acid relative to total parabens. 相似文献