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201.
Mohamed Ali Ben Aissa Sabri Hassen Youssef Arfaoui 《International journal of quantum chemistry》2019,119(6):e25837
Chalcogen bonding is a noncovalent interaction, highly similar to halogen and hydrogen bonding, occurring between a chalcogen atom and a nucleophilic region. Two density functional theory (DFT) approaches B3LY-D3 and B97-D3 were performed on a series of complexes formed between CX2 (X = S, Se, Te) and diazine (pyridazine, pyrimidine and pyrazine). Chalcogen atoms prefer interacting with the lone pair of a nitrogen atom rather than with the π-cloud of an aromatic ring. CTe2 and CSe2 form a stronger chalcogen bond than CS2. The electrostatic potential of CX2 (X = S, Se and Te) reveals the presence of two equivalent σ-holes, one on each chalcogen atom. These CX2 molecules interact with diazine giving rise to supramolecular interactions. Wiberg bond index and second-order perturbation theory analysis in NBO were performed to better understand the nature of the chalcogen bond interaction. 相似文献
202.
The undesirable cycling performance caused by soluble poly sulfides shuttling between anode and cathode has been considered as the main challenge that has hindered its practical applications for lithium-sulfiir(Li-S) batteries. To solve tliis issue effectively, a nitrogen-containing porous carbon, namely JUC-Z2-900,developed from a porous organic framework, namely JUC-Z2, bearing a high surface area(805 m^2/g),small pore size(0.5 mil) and nitrogen doping(2.15%, mass fraction), has been used as a host material for Li-S batteries. The micropores of JUC-Z2-900 can confine the smaller sulfur molecules S2-4, which can essentially alleviate the critical problem of poly sulfide dissolution.Furthermore, nitrogen-containing JUC-Z2-900 can promote chemical adsorption of sulfur. The above two factors can improve the electrochemical performance of Li-S batteries effectively. To compare the eftects of sulfur contents and melt-difiusion strategy in JUC-Z2-900/S composites, a series of JUC-Z2-900/S composites was synthesized and tlieir electrochemical perfbnnances were explored, indicating good rate performance and excellent cycling stability of the composites contributed by both appropriate mass percentage of sulfiir and its confinement in the micropores. 相似文献
203.
Ghazi Hassen 《International Journal of Solids and Structures》2010,47(7-8):1040-1047
A multiphase model for assessing the macroscopic behavior of earth structures reinforced by two-dimensional inclusions in the context of elastoplasticity is presented and incorporated into a finite element based numerical tool with an appropriate return mapping algorithm. The obtained numerical tool is applied to the stability analysis of an axisymmetric reinforced soil-structure and a parametric study is then considered for different interaction conditions between the soil and the reinforcing membranes, corresponding to a perfect bonding assumption, a perfectly smooth interface and an intermediate case. The stability factors quantified by this study for the different cases are then compared to those obtained by a yield design analysis. 相似文献
204.
Hassen M. Ouakad 《International Journal of Non》2010,45(7):704-713
In this paper, we investigate the dynamic behavior of clamped-clamped micromachined arches when actuated by a small DC electrostatic load superimposed to an AC harmonic load. A Galerkin-based reduced-order model is derived and utilized to simulate the static behavior and the eigenvalue problem under the DC load actuation. The natural frequencies and mode shapes of the arch are calculated for various values of DC voltages and initial rises. In addition, the dynamic behavior of the arch under the actuation of a DC load superimposed to an AC harmonic load is investigated. A perturbation method, the method of multiple scales, is used to obtain analytically the forced vibration response of the arch due to DC and small AC loads. Results of the perturbation method are compared with those obtained by numerically integrating the reduced-order model equations. The non-linear resonance frequency and the effective non-linearity of the arch are calculated as a function of the initial rise and the DC and AC loads. The results show locally softening-type behavior for the resonance frequency for all DC and AC loads as well as the initial rise of the arch. 相似文献
205.
Ibtissem Fraj Tarek Hidouri Faouzi Saidi Lotfi Bouzaiene Larbi Sfaxi Hassen Maaref 《Current Applied Physics》2017,17(1):1-5
In0.21Ga0.79As multiple quantum wells MQW, with different well thickness L, are grown on [001] and [113] A GaAs growth directions by molecular beam epitaxy MBE. An asymmetric photoluminescence PL line shape denoted LEA and LEB in the lower energies side has been observed in both structures. These emissions of deep localized states can be related to the energy potential modulation associated to Indium cluster formation. Temperature dependence of photoluminescence properties has been reported. Localized state ensemble LSE model has investigated atypical behaviors of PL peak energies and the full width at half maximum FWHM of both emissions. These abnormal behaviors are explained by carriers captured by localized recombination centers. Competition processes between localized and delocalized excitons have been occurred to interpret the PL properties. The degree of localization induced by quantum-dot-like states and critical temperatures between different temperatures regions increase as far as away [001] growth direction. 相似文献
206.
Mosbah Jemmali Rached Ben Hassen Siwar Walha Petricek Vaclac 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(7):i73-i75
The crystal structure of potassium cerium(III) bis(sulfate) monohydrate, KCe(SO4)2·H2O, is built up from irregular independent SO4 tetrahedra, CeO9 polyhedra in the form of distorted tricapped trigonal prisms and K+ ions. Hydrogen bonding between the free water molecule and sulfate groups supplement the ionic bonds characteristic of the rest of the structure. 相似文献
207.
Lazim H Josephsen J Ben Hassen A Belhadj O Limam F 《Applied biochemistry and biotechnology》2005,125(3):189-199
Various strains of Escherichia coli, isolated from different patients, were screened for type II restriction endonuclease activity. In 1 out of 23 patients,
a type II restriction endonuclease activity was found. The restriction endonuclease designated Eco1524I was purified to near
homogeneity, based on hydroxyapatite and heparin sepharose chromatography. Eco1524I exhibited endonuclease restriction activity
in the pH range from 6.0 to 10.0 (maximum level at pH 8.0) and required Mg2+ as divalent cation. The enzyme was stable till temperature 55°C and pH range from 6.0 to 10.0. Eco1524I recognized the sequence
6-bp palindromic 5′AGG↑CCT 3′, producing blunt end and is found to be an isoschizomer of Stu I. 相似文献
208.
209.
210.
Mohamed Dhib Hassen Aroui 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,107(3):372-384
The shift coefficients and line-mixing parameters of rovibrational-inversion transitions in the ν4 band of ammonia (NH3) perturbed by nitrogen (N2) have been measured at room temperature with a high-resolution Fourier transform spectrometer. The collisional shift and line mixing are obtained from the non-linear least-square multi-pressure fitting techniques. Comparison is made with the results of theoretical calculation based on semi-classical model extended to the case of symmetric top molecule with inversion motion. The shifts and the line-mixing parameters are calculated using, respectively the approach developed by Robert and Bonamy and the state-to-state cross-section. The agreement is satisfactory on the average. Good agreement is also obtained for line mixing with previous measurements. 相似文献