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91.
Oussama Kamal Tarik Eljaddi El Houssine EL Atmani Imane Touarssi Laurent Lebrun Miloudi Hlaïbi 《先进技术聚合物》2017,28(4):541-548
To conduct experiments related to the facilitated extraction phenomenon and recovery of vanadium ions VO2+, two grafted polymer membranes were prepared; containing respectively cholic acid and azithromycin as extractive agents and the obtained membranes were characterized. All experiments for the facilitated extraction phenomenon of these ions were carried out. Kinetic and thermodynamic models, based on the interaction of the substrate S (VO2+) with the extractive agent T, and the diffusion of the formed entity (TS) through the membrane were developed, to determine the macroscopic parameters, permeability P and initial fluxes J0, and the microscopic parameters, association constants Kass and apparent diffusion coefficients D*, related to the formation of entities TS and their diffusion. A clear evolution of these parameters, depending on various factors (substrate concentration C0, extractive agent concentration and feed and receiving phases temperature), and high permeabilities for this extraction phenomenon of VO2+ ions were observed for this membrane type. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
92.
A. A. Stolbov A. G. Lyapin S. V. Popova V. V. Brazhkin E. L. Gromnitskaya O. V. Stal'GOROVA 《高压研究》2013,33(1-2):187-190
We present the systematic study of the elastic shear G and bulk B moduli in amorphous and crystalline metastable ternary solid solutions (GaSb)1?x Ge2x . It is found that the moduli of crystalline phases initially decrease with Ge concentration, falling down to minimum values at 20-30% Ge. The minimal values of elastic moduli for amorphous samples are observed at 50-60% Ge. Elastic softness of crystalline solid solutions is assumed to be related to the increase of chemical disorder and, consequently, of static (non-thermal) geometrical disorder in positions of atoms. An additional topological disorder in amorphous solid solutions leads to additional elastic softening. 相似文献
93.
LAILA H. ABDEL‐RAHMAN RAFAT M. EL‐KHATIB LOBNA A. E. NASSR AHMED M. ABU‐DIEF 《国际化学动力学杂志》2014,46(9):543-553
The reactivity of few novel high‐spin Fe(II) complexes of Schiff base ligands derived from 2‐hydroxynaphthaldehyde and some variety of amino acids with the OH? ion has been examined in an aqueous mixture at the temperature range from 10 to 40°C. Based on the kinetic investigations, the rate law and a plausible mechanism were proposed and discussed. The general rate equation was suggested as follows: rate = kobs[complex], where kobs. = k1 + k2[OH?]. Base‐catalyzed hydrolysis kinetic measurements imply pseudo–first‐order doubly stage rates due the presence of mer‐ and fac‐isomers. The observed rate constants kobs are correlated with the effect of substituent R in the structure of the ligands. From the effect of temperature on the rate base hydrolysis reaction, various thermodynamic parameters were evaluated. The evaluated rate constants and activation parameters are in a good agreement with the stability constants of the investigated complexes. Moreover, the reactivity of the investigated complexes toward DNA was examined and found to be in a good agreement with the reported binding constants. 相似文献
94.
In this paper, a new hybridized mixed formulation of weak Galerkin method is studied for a second order elliptic problem. This method is designed by approximate some operators with discontinuous piecewise polynomials in a shape regular finite element partition. Some discrete inequalities are presented on discontinuous spaces and optimal order error estimations are established. Some numerical results are reported to show super convergence and confirm the theory of the mixed weak Galerkin method. 相似文献
95.
In this paper, the authors aim at proving two existence results of fractional differential boundary value problems of the form(P_(a,b)){D~αu(x) + f(x, u(x)) = 0, x ∈(0, 1),u(0) = u(1) = 0, D~(α-3)u(0) = a, u(1) =-b,where 3 α≤ 4, Dαis the standard Riemann-Liouville fractional derivative and a, b are nonnegative constants. First the authors suppose that f(x, t) =-p(x)t~σ, with σ∈(-1, 1)and p being a nonnegative continuous function that may be singular at x = 0 or x = 1and satisfies some conditions related to the Karamata regular variation theory. Combining sharp estimates on some potential functions and the Sch¨auder fixed point theorem, the authors prove the existence of a unique positive continuous solution to problem(P_(0,0)).Global estimates on such a solution are also obtained. To state the second existence result, the authors assume that a, b are nonnegative constants such that a + b 0 and f(x, t) = tφ(x, t), with φ(x, t) being a nonnegative continuous function in(0, 1)×[0, ∞) that is required to satisfy some suitable integrability condition. Using estimates on the Green's function and a perturbation argument, the authors prove the existence and uniqueness of a positive continuous solution u to problem(P_(a,b)), which behaves like the unique solution of the homogeneous problem corresponding to(P_(a,b)). Some examples are given to illustrate the existence results. 相似文献
96.
The influence of low-energy Ar ion beam irradiation on both electrical and optical properties of low-density polyethylene (LDPE) films is presented. The polymer films were bombarded with 320 keV Ar ions with fuences up to 1×1015 cm?2. Electrical properties of LDPE films were measured and the effect of ion bombardment on the DC conductivity, dielectric constant and loss was studied. Optically, the energy gap, the Urbach’s energy and the number of carbon atoms in a cluster were estimated for all polymer samples using the UV–Vis spectrophotometry technique. The obtained results showed slight enhancement in the conductivity and dielectric parameters due to the increase in ion fluence. Meanwhile, the energy gap and the Urbach’s energy values showed significant decrease by increasing the Ar ion fluence. It was found that the ion bombardment induced chain scission in the polymer chain causing some carbonization. An increase in the number of carbon atoms per cluster was also observed. 相似文献
97.
98.
El Houcein EL Abdalaoui 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2000,36(6):81
It is shown that there is a class of Ornstein transformations, distinct from the Ornstein mixing class, which are almost surely weak mixing 相似文献
99.
A.M. EL Sherbini A.M. Aboulfotouh S.H. Allam Th.M. EL Sherbini 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010,65(12):1041-1046
The diode laser atomic absorption spectroscopy (DLAAS) technique has been utilized to assess the degree of optical opacity of plasma at the wavelength of the Hα-line. The plasma is produced at atmospheric conditions by focusing a 6 ns Nd:YAG laser pulse at 1.064 μm on different solid target materials including aluminum, iron and titanium as major elements as well as flat pieces of plastic and wood characterized by a high content of hydrogen. The optical depth was investigated as a function of delay times ranging from 0 to 5 μs, and at laser fluences ranging from 7 to 19 J/cm2, all at a fixed gate time of 1 μs. The results show that the plasma associated with metallic targets is almost optically thin at the Hα-line over all fluences and at delay times ≥ 1 μs, but rather thick for hydrogen-rich targets (plastic and wood) over all delay times and fluences. 相似文献
100.