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91.
Mohamed Amine Didi Didier Villemin Omar Abderrahim Abdelkrim Azzouz 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1191-1198
In this paper, extractants that have the potential to be sustainably regenerated, are proposed for thorium(IV) removal from nitrate aqueous phases. These extractants are oleic (OA), palmitic (PA) and lauric (LA) acids. The advantages of using these acids are their sustainability, their biocompatibility and their non-toxicity, this makes these simpler and greener compared to other extractants (organophosphorus, azote derivatives, macrocyclic crown, etc…) used for metal extraction. These acids were applied as chelating agent for Th(IV) liquid–liquid extraction. The extractions were carried out in chloroform as an organic phase through the formation of thorium–OA, thorium–PA and thorium–LA complexes. The synergistic extraction of Th(IV) with these extractants in the presence of tributhylphosphine (TBP) has been investigated. The effect of different variables, such as time contact, pH of the aqueous phase, concentration of fatty acid, TBP addition on fatty acids, ionic strength and temperature, is reported. The results showed that the extraction kinetics using LA and OA were fast than with PA. The KNO3 addition does not seem to highly influence the extraction yield, and no important synergy effect was noticed in the presence of TPB. Thermodynamic data for Th(IV) solvent extraction are also reported in this paper. 相似文献
92.
Harald Hofmeier Abdelkrim El‐Ghayoury Ulrich S. Schubert 《Journal of polymer science. Part A, Polymer chemistry》2004,42(16):4028-4035
Terpolymers bearing terpyridine as well as (meth)acrylates as free radical curable groups (UV‐curing) or hydroxyl groups (thermal curing with bis‐isocyanates) were synthesized and characterized using 1H NMR, IR and UV‐vis spectroscopy as well as GPC. Subsequently, the ability of covalent crosslinking via the UV‐initiated polymerization of the acrylate groups was investigated. Moreover, the thermal covalent crosslinking via the reaction of hydroxyl functionalized terpolymer and bis‐isocyanate compounds could be successfully achieved. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4028–4035, 2004 相似文献
93.
Abdelkrim El‐ghayoury Chouaib Boukaftane Barteld de Ruiter Rob van der Linde 《Journal of polymer science. Part A, Polymer chemistry》2003,41(4):469-475
A dual‐cure process consisting of two subsequent ultraviolet‐initiated radical and cationic polymerizations was investigated. The process was studied with two acrylate oxetane monomers, one of them having a spacer between the two polymerizable moieties. It was shown by Fourier transform infrared (FTIR) that the first (radical) step was performed successfully for both systems. As for the second (cationic) step, only the monomer with the spacer was able to polymerize, allowing the crosslinking of the polyacrylic chains generated by the first step. The efficiency of the process was confirmed by differential scanning calorimetry because the glass‐transition temperatures of the cured films were ?16 and + 34 °C after the first and second steps, respectively. The dual cure of this system was further analyzed by real‐time FTIR, which showed that 86% of the acrylate and 80% of the oxetane moieties were converted after 20 and 50 s of light exposure, respectively. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 469–475, 2003 相似文献
94.
Mohamed El Kodadi Abdelkrim Ramdani Malek Fouad Driss Eddike Monique Tillard Claude Belin 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(12):o735-o737
The crystal structure of the title compound, C18H23N5O·H2O, shows molecules containing a phenol group linked perpendicularly to a roughly planar fragment comprising two pyrazole rings. Molecules are stacked perpendicular to the [101] direction, with their phenol groups disposed alternately. The molecular packing in the crystal is stabilized by hydrogen bonding involving water molecules. 相似文献
95.
Abdelkrim Meddour Ccile Canlet Luis Blanco Jacques Courtieu 《Angewandte Chemie (International ed. in English)》1999,38(16):2391-2393
Unambiguous assignment of the resonances of different diastereomers in a nonracemic mixture is possible with 1H-decoupled 2H NMR spectroscopy in a chiral liquid crystalline solvent. This is demonstrated with, for example, the α,α′-dideuterated diol shown in the picture. Even diastereomers with centers of chirality up to nine bonds apart can be discriminated. 相似文献
96.
Control over crystal structure, size, shape, and organization of TiO2 nanocrystals has been achieved by means of wet chemistry. Hydrolysis and polycondensation of titanium alkoxide [Ti(OR)4] has been performed in the presence of tetramethylammonium hydroxide (Me4NOH). This base both catalyzes the reaction and provides an organic cation that stabilizes the anatase polyanionic cores formed in this medium. These anatase clusters are organized so as to favour self-assembly into intermediate nanocrystals, which, in turn, self-assemble into superlattices. This self-assembling process has been exploited for the processing of highly structured titania films. Furthermore, larger anatase TiO2 nanocrystals of different sizes and shapes have been obtained by adjusting the relative concentrations of titanium alkoxide and Me4NOH, the reaction temperature, and the pressure. HRTEM, XRD, and EXAFS have been used to characterize the various samples and to elucidate the growth of titania anatase. Our observations are in accordance with theoretically predicted condensation and growth pathways. The formation of mesoscopic structures through a self-assembling process of the multiply charged polytitanate anions in the presence of Me4N+ is also discussed. 相似文献
97.
98.
Synthesis and affliations of oxophosphonates in organic chemistry. This work devoted to oxophosphonates deals with three different series of compounds: the α-ketophosphonates, the β-ketophosphonates and finally the γ- and δ-ketophosphonates which were considered as one series of compounds. For each type of products, the various synthetic methods as well as their reactivity were presented. In the last part, we have developed different methods of reduction, nucleophilic addition and substitution reactions. Particular attention was focused on sulfur and nitrogen containing derivatives as well as fluorinated and chlorinated compounds. 相似文献
99.
Aerosols are defined in the simplest form as a mixture of solid or liquid particles suspended in a gas [1]. Brake dust is an aerosol, generated as a result of erosion between brake disc and brake pad. The aerosols can cause visual disorder, heart and lung diseases, short term acute symptoms like asthma, bronchitis and long term chronic irritation and inflammation of the respiratory track, which can lead to cancer. Therefore, it is important to know which factors are affecting the erosion rate of brakes. The main objective of this work is to measure the erosion rate of brake discs and brake pads, depending on temperature changes and deformation by performing experiments and simulations at varying velocities and load conditions. The general purpose, commercially available finite element solver Abaqus is used for performing the thermomechanically coupled simulations. Archad's Wear Law is used for the wear calculation. Experiments are conducted by using a pin on disc test bench. Temperature changes are measured by using thermocouples and erosion rates by measuring the total volume loss. At the end, relationships between erosion rates and temperature changes for different brake disc velocities and load conditions are investigated and experimental and simulation results are compared and discussed. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
100.
We consider bounded 2-metric spaces satisfying an additional axiom, and show that a contractive mapping has either a fixed point or a fixed line. 相似文献