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221.
Souhila Bendenia Kheira Marouf-Khelifa Isabelle Batonneau-Gener Zoubir Derriche Amine Khelifa 《Adsorption》2011,17(2):361-370
The ionic exchange of the NaX zeolite by Ni2+ and Cr3+ cations was progressively driven and studied by adsorption of nitrogen and carbon dioxide. For each cation-exchanged X zeolite
sample, the development of characteristics such as profile of isotherms, RI criterion, isosteric adsorption heat and microporous
volume using both the Dubinin–Radushkevich (DR) equation and the t-plot, was followed through the nitrogen adsorption. Results show that the cationic exchange process, in the case of Cr3+ introduced at middle degree, is accompanied by a textural damage for Cr(x)X, in contrast to Ni2+-exchanged X zeolites. This degradation occurs without significant presence of mesopores, because the RI criterion values
were found to be much lower than 2.2. The CO2 adsorption isotherms were measured at intervals of 30 K from 273 K and the equilibrium pressures ranged from 0.5 to 600 Torr.
The experimental data were correlated by the Toth model. The associated three adjustable parameters were estimated by nonlinear
least-squares analysis. The effect of temperature on the model parameters and the Henry’s law slope, K
H
, represented by the product of Toth parameters, are discussed. 相似文献
222.
Amine Mahjoub Johnatan E. Pecero Sánchez Denis Trystram 《Computational Optimization and Applications》2011,48(2):369-398
New distributed computing platforms (grids) are based on interconnections of a large number of processing elements. A most
important issue for their effective utilization is the optimal use of resources through proper task scheduling. It consists
of allocating the tasks of a parallel program to processors on the platform and to determine at what time the tasks will start
their execution. As data may be subject to uncertainties or disturbances, it is practically impossible to precisely predict
the input parameters of the task scheduling problem. 相似文献
223.
Mohamed Amine Cherif Toufic El Arwadi Hassan Emamirad Jean-Marc Sac-épée 《Semigroup Forum》2014,88(3):753-767
The first aim of this paper is to illustrate numerically that the Dirichlet-to-Neumann semigroup represented by P. Lax acts as a magnifying glass. In this perspective, we used the finite element method for discretizing of the correspondent boundary dynamical system using the implicit and explicit Euler schemes. We prove by using the Chernoff’s Theorem that the implicit and explicit Euler methods converge to the exact solution and we use the (P1)-finite elements to illustrate this convergence through a FreeFem++ implementation which provides a movie available online. In the Dirichlet-to-Neumann semigroup represented by P. Lax the conductivity \(\gamma \) is the identity matrix \(I_n\) , but for a different conductivity \(\gamma \) , the authors of Cornean et al. (J Inverse Ill-posed Prob 12:111–134, 2006) supplied an estimation of the operator norm of the difference between the Dirichlet-to-Neumann operator \(\Lambda _\gamma \) and \(\Lambda _1\) , when \(\gamma =\beta I_n\) and \(\beta =1\) near the boundary \(\partial \Omega \) (see Lemma 2.1). We will use this result to estimate the accuracy between the correspondent Dirichlet-to-Neumann semigroup and the Lax semigroup, for \(f\in H^{1/2}(\partial \Omega )\) . 相似文献
224.
Sadeek A. Sadeek Ewais M. M. Moussa Mohamed A. El-Sayed Maisa M. Amine 《Journal of Dispersion Science and Technology》2014,35(7):926-933
A new chelating resin (glycidyl methacrylate/divinylbenzene/pentaethylenehexamine (GMA/DVB/PEHA)) for uranium(VI) and thorium(IV) has been developed by functionalizing GMA/DVB with PEHA. The adsorption of U(VI) and Th(IV) ions onto the functionalized GMA/DVB/PEHA were investigated as a function of pH value, contact time, and temperature using batch adsorption technique. The results showed that U(VI) and Th(IV) adsorption onto GMA/DVB/PEHA was strongly dependent on pH. Kinetic studies revealed that the adsorption process achieved equilibrium within 15 and 90 minutes for Th(IV) and U(VI), respectively, and followed a pseudo-second-order rate equation. The isothermal data correlated with the Langmuir model better than the Freundlich model. Thermodynamic data indicated the spontaneous and endothermic nature of the process. The maximum adsorption capacity of U(VI) and Th(IV) were found to be 114 and 78 mg/g, respectively. Quantitative recovery of uranium and thorium were achieved by desorbing the loaded GMA/DVB/PEHA with 0.5 M HNO3 相似文献
225.
In this work, we reported a new strategy based on DNA strands hydrolysis in combination with the employment of functionalized carbon black modified screen-printed electrode (f-CB/SPE) for guanine detection. Using glass microbeads as a solid substrate of ssDNA probe fixation, and under appropriate conditions of temperature, time, and hydrochloric acid concentration, DNA hydrolysis has been successfully used to release the guanine, allowing its oxidation at f-CB/SPE using differential pulse voltammetry. The selectivity was successfully tested with a non-complementary sequence, and a detection limit of 0.7 nM of the target DNA has been reached. 相似文献
226.
Mohamed El Amine Benmalti Abdelghani Krallafa Najeh Rekik Mostefa Belhakem 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(1):58-66
A full quantum theoretical model is proposed to study the νO–H experimental IR line shapes of polarized crystalline glutaric and 1-naphthoic acid dimer crystals at room and liquid nitrogen temperatures. This work is an application of a previous model [M. E-A. Benmalti, D. Chamma, P. Blaise, and O. Henri-Rousseau, J. Mol. Struct. 785 (2006) 27–31] by accounting for Fermi resonances. The approach is dealing with the strong anharmonic coupling, Davydov coupling, multiple Fermi resonances between the first harmonics of some bending modes and the first excited state of the symmetric combination of the two νO–H modes and the quantum direct and indirect relaxation.Numerical results show that mixing of all these effects allows to reproduce satisfactorily the main features of the experimental IR line shapes of crystalline hydrogenated and deuterated glutaric and 1-naphthoic acid crystals and are expected to provide efficient of Fermi resonances effects. 相似文献
227.
Sulfone-based electrolytes have been investigated as electrolytes for lithium-ion cells using high-voltage positive electrodes, such as LiMn2O4 and LiNi0.5Mn1.5O4 spinels, and Li4Ti5O12 spinel as negative electrode. In the presence of imide salt (LiTFSI) and ethyl methyl sulfone or tetramethyl sulfone (TMS) electrolytes, the Li4Ti5O12/LiMn2O4 cell exhibited a specific capacity of 80 mAh g?1 with an excellent capacity retention after 100 cycles. In a cell with high-voltage LiNi0.5Mn1.5O4 positive electrode and 1 M LiPF6 in TMS as electrolyte, the capacity reached 110 mAh g?1 at the C/12 rate. When TMS was blended with ethyl methyl carbonate, the Li4Ti5O12/LiNi0.5Mn1.5O4 cell delivered an initial capacity of 80 mAh g?1 and cycled fairly well for 1000 cycles under 2C rate. The exceptional electrochemical stability of the sulfone electrolytes and their compatibility with the Li4Ti5O12 safer and stable anode were the main reason behind the outstanding electrochemical performance observed with high-potential spinel cathode materials. These electrolytes could be promising alternative electrolytes for high-energy density battery applications such as plug-in hybrid and electric vehicles that require a long cycle life. 相似文献
228.
Messaoud Fatmi Brahim Ghebouli Mohamed Amine Ghebouli Abdelmadjid Bouhemadou Saad Binomran 《Journal of Physics and Chemistry of Solids》2012,73(1):1-7
A theoretical study of the structural, electronic, optical and thermodynamic properties of NaxRb1?xH and NaxK1?xH ternary alloys in NaCl phase has been carried out using the first-principles method. We modeled the alloys at some selected compositions with ordered structures described in terms of periodically repeated supercells. The dependences on the composition of the lattice constant, band gap, dielectric constant, refractive index, Debye temperature, mixing entropy and heat capacities were analyzed for x=0, 0.25, 0.50, 0.75 and 1. The lattice constants of NaxRb1?xH and NaxK1?xH exhibit a marginal deviation from Vegard's law. A strong deviation of the bulk modulus from linear concentration dependence was observed for both alloys. We found that the composition dependence of the energy band gap is highly non linear and the large bowing coefficient for NaxRb1?xH is sensitive to the composition. Using the approach of Zunger and co-workers, the microscopic origins of the gap bowing were detailed and explained. The thermodynamic stability of these alloys was investigated by calculating the phase diagram. The thermal effect on some macroscopic properties was investigated using the quasi-harmonic Debye model. There is a good agreement between our results and the available experimental data for the binary compounds, which is a support for those of the ternary alloys that we report for the first time. 相似文献
229.
Mohamed Amine Berkal Quentin Palas Estelle Ricard Christine Lartigau-Dagron Luisa Ronga Jean-Jacques Toulmé Corinne Parat Corinne Nardin 《Macromolecular bioscience》2023,23(8):2200508
N-phosphonomethyle-glycine (glyphosate) is the most widely used pesticide worldwide due to its effectiveness in killing weeds at a moderate cost, bringing significant economic benefits. However, owing to its massive use, glyphosate and its residues contaminate surface waters. On site, fast monitoring of contamination is therefore urgently needed to alert local authorities and raise population awareness. Here the hindrance of the activity of two enzymes, the exonuclease I (Exo I) and the T5 exonuclease (T5 Exo) by glyphosate, is reported. These two enzymes digest oligonucleotides into shorter sequences, down to single nucleotides. The presence of glyphosate in the reaction medium hampers the activity of both enzymes, slowing down enzymatic digestion. It is shown by fluorescence spectroscopy that the inhibition of ExoI enzymatic activity is specific to glyphosate, paving the way for the development of a biosensor to detect this pollutant in drinking water at suitable detection limits, i.e., 0.6 nm . 相似文献