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91.
Khemaies Brahim Amira Soussi-Baatout Ismail Khattech Mohamed Jemal 《Journal of Thermal Analysis and Calorimetry》2017,129(2):701-708
A thermochemical study of hydrochloric acid attack of synthetic fluorapatite was performed by a DRC. The calculated thermogenesis curves show one peak. The plot of the heat quantity as a function of the dissolved mass undergoes only one straight segment, and the thermogenesis curves present a single peak, suggesting the occurrence of a one-step dissolution process. The dissolution kinetics was examined according to the heterogeneous reaction models and showed that the dissolution is controlled by the product layer diffusion process with a reaction rate expressed by the following semiempirical equation; \(\left[ {1 + 2(1 - X) - 3(1 - X)^{{\frac{2}{3}}} } \right] = 3195 \times 10^{ - 2} C^{0.145} \left( {\frac{S}{L}} \right)^{ - 0.628} e^{{ - \frac{2600}{\text T}}} t\). The activation energy was determined as 21.6 ± 1.5 kJ mol?1 相似文献
92.
Ismail AA 《Journal of colloid and interface science》2008,317(1):288-297
Mesostructured materials show promise in fabricating ordered sensing systems in a reproducible manner. Here, the fabrication of optically selective and sensitive sensors up to subnanomolar concentrations of Sb(III) ions was reported via simple and reproducible techniques in which the hexagonal mesoporous silicas in powder and monolith forms were used as probe carriers. Evidence of successful fabrication of the optical sensors was investigated by extensive characterizations using powder X-ray diffraction, nitrogen adsorption/desorption isotherms, 29Si NMR spectroscopy, and transmission electron microscopy. The mesostructured features allowed high adsorption capacity and accessibility of probe molecules and efficient transport of toxic species via much more direct and easier diffusion to the network sites without significant alteration of their physical characteristics, leading to excellent sensing systems in terms of stability and sensitivity with rapid response time of detection. In addition, the high performance of the hexagonal sensors was dependent on key factors such as the number of support-based sensors, the reaction temperature, and the pH value that led to possible naked-eye detection of Sb(III) ion concentration with a detection limit as low as 3x10(-9) mol/dm3 and a wide detection range of 1 ppb-2 ppm. Of particular interest was that our mesostructured sensor design provided control over the retention of the potential functionality of the naked-eye sensing system of Sb(III) ions upon the storage and even after several regeneration and reuse cycles, indicating large-scale reversibility of sensing systems. 相似文献
93.
M. R. Ismail M. M. El-Fass H. A. Abd-El-Rahman A. A. El-Milligy 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(1):141-146
The influence of methyl metharcylate and gamma exposure dose on the physico-chemical and mechanical properties of polymer-alite
composite have been investigated. The hardened alite samples were impregnated with a methyl methacrylate monomer and then
subjected to γ irradiation doses from 10–50 KGy. The effect of polymer loading (%), compressive strength, bulk density and
the microstructure (scanning electron microscopy SEM), in addition IR spectra were studied. The results indicate that, polymer
loading, compressive strength and bulk density increase with increasing absorbed dose. This is attributed to the deposition
of the polymer in the pores of the samples. SEM showed the voids between the particles in the samples before the impregnation,
whereas, the formation of new products in the pores appeared after impregnation. 相似文献
94.
Almost all evaluations of convection schemes reported in the literature are conducted using simple problems on uniform orthogonal grids; thus, having limited contribution when solving industrial computational fluid dynamics (CFD), where the grids are usually non‐orthogonal with distortions. Herein, several convection schemes are assessed in uniform and distorted non‐orthogonal grids with emphasis on industrial applications. Linear and nonlinear (TVD) convection schemes are assessed on analytical benchmarks in both uniform and distorted grids. To evaluate the performance of the schemes, four error metrics are used: dissipation, phase and L1 errors, and the schemes' effective order of accuracy. Qualitative and quantitative deterioration of these error metrics as a function of the grid distortion metrics are investigated, and rigorous verifications are performed. Recommendations for effective use of the convection schemes based on the range of grid aspect ratio (AR), expansion ratio (ER) and skewness (Q) are included. A ship hydrodynamics case is studied, involving a Reynolds averaged Navier–Stokes simulation of a bare‐hull KVLCC2 tanker using linear and nonlinear convection schemes coupled with isotropic and anisotropic Reynolds‐stress (ARS) turbulence models using CFDShip‐Iowa v4. Predictions of local velocities and turbulent quantities from the midships to the nominal wake plane are compared with experimental fluid dynamics (EFD), and rigorous verification and validation analyses for integral forces and moments are performed for 0° and 12° drift angles. Best predictions are observed when coupling a second‐order TVD scheme with the anisotropic turbulence model. Further improvements are observed in terms of prediction of the vortical structures for 30° drift when using TVD2S‐ARS coupled with DES. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
95.
Using57Mössbauer spectroscopy and neutron activation analysis, various kinds of environmental samples have been studied, in order to demonstrate that the combination of a phase sensitive and a multi-element technique is a powerful tool for studying environmental problems. 相似文献
96.
Cationic polyelectrolytes containing quaternary nitrogen atoms within the main chain were prepared via condensation polymerization of epichlorhydrin (ECH) with benzyl amine (BA). Polyelectrolytes having different molecular weights were obtained by varying the ECH/BA mole ratio. Cationic polymers were characterized by 1H-NMR and gel permeation chromatography. The antimicrobial activity of the polymers was tested against bacteria, yeast, and fungi. 相似文献
97.
Mourad E. H. Ismail 《The Ramanujan Journal》2006,11(3):349-353
We give short elementary proofs of a formula of Ramanujan as interpreted by Bradley, and a companion formula originally proved
by W. Chu. We also give an elementary proof of a generalization of an identity originally proved using modular functions and
used to study a generating function for the number of partitions with specified crank.
Research partially supported by NSF grant DMS 99-70865.
2000 Mathematics Subject Classification Primary—39A70, 11P83; Secondary—33C20 相似文献
98.
Vignesh Nayak Mannekote Shivanna Jyothi Prof. R Geetha Balakrishna Dr. Mahesh Padaki Prof. Ahmad Fauzi Ismail 《ChemistryOpen》2015,4(3):278-287
Herein we present a new approach for the complete removal of CrVI species, through reduction of CrVI to CrIII, followed by adsorption of CrIII. Reduction of chromium from water is an important challenge, as CrIV is one of the most toxic substances emitted from industrial processes. Chitosan (CS) thin films were developed on plain polysulfone (PSf) and PSf/TiO2 membrane substrates by a temperature-induced technique using polyvinyl alcohol as a binder. Structure property elucidation was carried out by X-ray diffraction, microscopy, spectroscopy, contact angle measurement, and water uptake studies. The increase in hydrophilicity followed the order: PSf < PSf/TiO2 < PSf/TiO2/CS membranes. Use of this thin-film composite membrane for chromium removal was investigated with regards to the effects of light and pH. The observations reveal 100 % reduction of CrVI to CrIII through electrons and protons donated from OH and NH2 groups of the CS layer; the reduced CrIII species are adsorbed onto the CS layer via complexation to give chromium-free water. 相似文献
99.
Ali Heba Ismail N. Amin M. S. Mekewi Mohamed 《Journal of Solid State Electrochemistry》2017,21(6):1605-1613
Journal of Solid State Electrochemistry - Efficient photoanodes are designed of vertically aligned anatase TiO2 nanotube arrays (anatase TNTAs) decorated with different shaped rutile TiO2... 相似文献
100.
Leibniz algebras are certain generalization of Lie algebras. In this paper, we give the classification of four-dimensional non-Lie nilpotent Leibniz algebras. We use the canonical forms for the congruence classes of matrices of bilinear forms and some other techniques to obtain our result. 相似文献