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A. Abouimrane K. Sbai K. El Kababi A. Lahmidi A. Atibi Serge Vilminot 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):605-619
The dehydration of ZnRb 4 (P 3 O 9 ) 2 ·;6H 2 O was investigated, between 25 and 600°;C, by TG-DTA, X-ray diffraction, IR. It leads, between 300 and 500°;C, to a mixture of long chain polyphosphates RbPO 3 and ZnRb 2 (PO 3 ) 4 which stays stable until its melting point. The IR (1400-30 cm m 1 ) and Raman spectra (1400-100 cm m 1 ) of ZnRb 4 (P 3 O 9 ) 2 ·;6H 2 O are reported and assignments of fundamental modes proposed and compared with theoretical results obtained via the MNDO method for P 3 O 9 ring with C s symmetry. (La déshydratation, sous pression atmosphérique, du cyclotriphosphate ZnRb 4 (P 3 O 9 ) 2 ·;6H 2 O, a ét´;e effectuée, entre 25 and 600°;C, par spectrométrie IR, diffraction des rayons X, ATG et ATD. Elle conduit, entre 300 and 500°;C, au mélange de polyphosphates RbPO 3 et ZnRb 2 (PO 3 ) 4 qui reste stable jusqu'à la fusion. Les spectres vibrationnels IR (1400-30 cm m 1 ) et Raman (1400-100 cm m 1 ) du sel étudié ont été interprétés dans le domaine des vibrations de valence et de déformation du cycle P 3 O 9 et comparés avec les résultats des calculs théoriques par la méthode MNDO pour un cycle isolé de symétrie C s .) 相似文献
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Kacem Sbai Azzeddine Atibi Ali Abouimrane Mohamed Hliwa Abdelmjid Lahmidi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):909-932
The cyclotriphosphate hexahydrate of manganese and silver, MnAg 4 (P 3 O 9 ) 2 .6H 2 O, was prepared by Boullé's process. MnAg 4 (P 3 O 9 ) 2 .6H 2 O crystallizes in the triclinic system, P-1, Z = 1 and its structure was determined by Rietveld's method. The refinement of 54 parameters by this method, using 1752 independent reflections leads to Rw p = 0.098, R p = 0.065 and R B = 0.033 on the basis of its isotype NiAg 4 (P 3 O 9 ) 2 .6H 2 O. The unit cell parameters of this salt are the following a = 8.824(1)Å, b = 8.485(1)Å, c = 6.609(1)Å, f = 90.30(1)°;, g = 92.89(1)°; and n = 107.28(1)°;. The thermal behavior of this new compound was studied, between 25 and 600°;C, under atmospheric pressure by infrared spectrometry, X-ray diffraction, thermal analyses TGA and DTA coupled. This study allows us the identification and the crystallographic characterization of a new phase, MnAg 2 (PO 3 ) 4 isotype of ZnRb 2 (PO 3 ) 4 , obtained between 350 and 450°;C, mixed with the long-chain polyphosphate of silver AgPO 3 . The kinetic characteristics of the dehydration of MnAg 4 (P 3 O 9 ) 2 .6H 2 O and the thermal phenomena accompanying this dehydration were determined and discussed on the basis of the proposed crystalline structure. The vibrational spectrum of the, MnAg 4 (P 3 O 9 ) 2 .6H 2 O, was examined and interpreted in the domain of the stretching vibrations of the P 3 O 9 rings, on the basis of the proposed crystalline structure and in the light of the calculation of the thirty fundamental IR frequencies for the idealized D 3h symmetry. 相似文献
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Abdelmjid Zouahri Azzeddine Elmidaoui 《Journal of polymer science. Part A, Polymer chemistry》1996,34(9):1793-1798
Hydrophilic carboxyl-containing fluoromembranes were obtained by preirradiation grafting of acrylic acid onto ethylene-tetrafluoroethylene film. The dependence of the grafting reaction on temperature, monomer concentration, nature and concentration of inhibitor, crosslinking agent, solvent, and on the preirradiation dose was investigated. The grafting rates increase with temperature, whereas the saturation degree of grafting (SDG) decreases. Addition of inhibitor minimizes homopolymerization and at the same time hinders the grafting reaction. The SDG increases markedly with monomer concentration until it reaches a maximum and thereafter decreases. The grafting rates increase with preirradiation dose. Addition of crosslinking agent initially decreases the SDG, and thereafter increases. The highest grafting rates are obtained using water as solvent followed by methanol and ethanol. The results are discussed on the basis of various parameters: interaction between monomer diffusibility and the viscosity of the monomer bath, the mutual reactivity of monomer, and the crosslinking agent. An agreement is observed between the values of the electrical resistance and the saturation degree of grafting. © 1996 John Wiley & Sons, Inc. 相似文献
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Jean-Claude Champarnaud-Mesjard Bernard Frit Abdeslam Chagraoui Abdelmjid Taïri 《无机化学与普通化学杂志》1996,622(11):1907-1912
Bi2Te2WO10 crystallises in the monoclinic system (space group C2/c, Z = 4) with a = 12.4972(7) Å, b = 5.6414(3) Å, c = 12.2705(6) Å and β = 91.38(3)°. The structure has been solved by means of single crystal X-ray diffraction data analysis. The reliability factors are R1 = 0.030 and wR2 = 0.065 for 1258 structure factors and 70 parameters. The Bi2Te2WO10 crystal structure can be described as a regular stacking along the Ox axis of polyhedral layers with the stereochemically active lone pairs E of the BiIII and TeIV atoms all located between these layers. The cohesion of the three-dimensional network is therefore only ensured between succesive layers by weak Bi? O(5) bonds. 相似文献
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Mohamed Nohair Ouafae Britel Nabil Souaf Driss Zakarya Abdelmjid Hafid Noura Mallouk 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1772-1781
We have used a new, robust model mapping technique—a Bayesian-regularized neural network—to develop a quantitative relationships model for the synthesis of the phosphocalcic hydroxyapatite by precipitation from a calcium carbonate solution and a phosphoric acid solution. This model was preformed by using a set of factors consisting on the pH of reactional medium, the Ca/P molar ratio of the reagents, reaction time, and the initial concentration of calcium. The results show that the method is robust and gives satisfied results. The Levenberg–Marquardt's algorithm implemented in the neural network Matlab's toolbox allowed a drastic improvement of the performance of the model. Very satisfactory results are then obtained by testing the validity by cross-validation technique. We have also turned our interests to the explanatory capacities of our methodology to explore the relative contribution and/or the contribution profile of the input factors by using Garson weight portioning method. 相似文献
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Abdeslam Chagraoui Abdelmjid Tairi 《Journal of Physics and Chemistry of Solids》2006,67(11):2241-2252
The new Bi2Te5WO16 compound has been prepared and its structure has been determined by single crystal X-ray diffraction: space group: P2/n (no. 13) with unit cell parameters , , , β=116.68(1)° and Z=2 formula units. The structure was determined from 1975 reflections, the final R1 and Rw indices are 0.037 and 0.071, respectively. The structure derives from the fluorite structure MX2. It can be described as [Bi2Te3O12] layers parallel to (−1 0 1) alternating in the direction [1 0 −1] by WO6 octahedron. The lone pairs of tellurium, active, localised in the pseudo-rectangular tunnels are oriented parallel to Oy-axis between [Bi2Te3O12] layers. 相似文献
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Output controllability and optimal output control of positive fractional order linear discrete system with multiple delays in state, input and output 下载免费PDF全文
Mouhcine Naim Fouad Lahmidi Abdelwahed Namir 《Journal of Applied Analysis & Computation》2019,9(6):2169-2189
The article concerns output controllability and optimal output control of positive fractional order discrete linear systems with multiple delays in state, input and output. Necessary and sufficient conditions for output reachability (output controllability from zero initial conditions) and null output controllability (output controllability to zero final output) are given and proven. We also prove that the positive system is output controllable if it is output reachable and null output controllable with the output reachability index is equal or less than the null output controllability index. Sufficient conditions for the solvability of the optimal output control problem are given. Numerical examples are presented to illustrate the theoretical results. 相似文献
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Soumia Ramdani Amina Amar Kamal Belhsaien Souad El Hajjaji Said Ghalem Abdelmjid Zouahri 《Analytical letters》2018,51(15):2468-2487
In Algeria, few studies have been conducted on the evaluation of roadside soil pollution. A total of 34 soil samples (28 roadside and 6 off-road) was obtained at 0–20?cm depth along the RN 35 national road. Heavy metal (Cd, Cr, Cu, Fe, Ni, Pb, and Zn) contents were extracted using aqua regia digestion and determined using atomic absorption spectrometry. Background values of heavy metal contents were determined using the robust statistical method of median plus two times the median absolute deviation. Single- and multi-element pollution and ecological risk indices were calculated. The results showed that background values were 2.5?±?0.3, 64.9?±?8.1, 28.0?±?4.1, 29371.5?±?4403.0, 32.9?±?4.4, 72.2?±?12.8, and 445.1?±?62.9?mg/kg for Cd, Cr, Cu, Fe, Ni, Pb, and Zn, respectively. The results were all higher than their corresponding median values. Single-element pollution indices (enrichment factor and geoaccumulation index) showed that the pollution is primarily due to Pb and Zn. Multi-element pollution index (Nemerow index) indicated that only 3% of the soil samples are strongly contaminated, whereas 23% are seriously contaminated. The potential ecological risk index showed that Cd is the most harmful element, followed by Pb and Zn. 65% of the soil samples had moderate potential ecological risk, while only 3% had considerable potential ecological risk. This study may be used as a baseline for future monitoring and as a tool for decision-making regarding environmental protection policies and sustainability of this semiarid agroecosystem. 相似文献
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Sanae Lahmidi El Hassane Anouar Mohamed El Hafi Otman El-Guourrami El Mokhtar Essassi Hanane Benzeid Abdulrahman I. Alharthi Joel T. Mague 《Journal of heterocyclic chemistry》2021,58(6):1268-1277
The incorporation of the piperidine ring into drugs may play an interesting role to fulfill significant tasks and act as an active ingredient in various treatments. Herein, three novel derivatives of 3-acetyl-2-hydroxybenzoic acid ( 3-5 ) containing a piperidine ring were synthesized through the rearrangement of triacetic acid lactone in the presence of piperidine. Their molecular structures were characterized by 1H and 13C NMR and single crystal X-ray diffraction techniques. The experimental data were compared with the predicted ones obtained in the polarizable continuum model at the B3LYP/6-311++G(d,p) level of theory. Relatively good correlations were obtained between the experimental data (spectral and Z-matrix coordinates) and the predicted ones, with correlation coefficients higher than 97%. The intercontacts between the closest units of 3-5 were identified through the analysis of the Hirshfeld surface and electrostatic potentials (ESP) maps. Hirshfeld surface and ESPs analyses reveal that the closest interactions between the units of the compounds are between hydrogen atoms (59%-67%). The antioxidant activity of 3-5 was evaluated using DPPH free radical scavenging and ABTS assays. They exhibit moderate antioxidant activity, which probably is attributable to the presence of a phenolic moiety in their basic skeleton. Molecular docking calculations suggest that 3-5 may mainly bind to the active binding site of peroxiredoxin 5 through strong and weak intermolecular hydrogen bonds. 相似文献
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