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51.
This work deals with the concept of satisfactory solution for Stochastic Multiobjective Programming (SMP) problems. Based on previous literature, we will introduce different concepts of satisfactory solutions for SMP problems, define a new concept of solution (where the decision maker (DM) sets his/her preferences in terms of two aspiration levels for the stochastic objective and two probabilities to reach those levels), and establish some relationship between these concepts. The results will aim at featuring these concepts and determine the differences between them. Moreover, the paper proposes a new step by step procedure to exchange information between the analyst and DM prior to solving the problem. Thus, the DM will be able to choose the transformation criterion for each stochastic objective and the aspiration level. 相似文献
52.
N. E. Fouad 《Journal of Thermal Analysis and Calorimetry》2000,60(2):541-547
The thermal behaviour of CrO3 on heating up to 600°C in dynamic atmospheres of air, N2 and H2 was examined by thermogravimetry (TG), differential thermal analysis (DTA), IR spectroscopy and diffuse reflectance spectroscopy
(DRS). The results revealed three major thermal events, depending to different extents on the surrounding atmosphere: (i)
melting of CrO3 near 215°C (independent of the atmosphere), (ii) decomposition into Cr2(CrO4)3 at 340–360°C (insignificantly dependent), and (iii) decomposition of the chromate into Cr2O3 at 415–490°C (significantly dependent). The decomposition CrO3 → Cr2(CrO4)3 is largely thermal and involves exothermic deoxygenation and polymerization reactions, whereas the decomposition Cr2(CrO4)3 → Cr2O3 involves endothermic reductive deoxygenation reactions in air (or N2) which are greatly accelerated and rendered exothermic in the presence of H2. TG measurements as a function of heating rate (2–50°C min−1) demonstrated the acceleratory role of H2, which extended to the formation of Cr(II) species. This could sustain a mechanism whereby H2 molecules are considered to chemisorb dissociatively, and then spillover to induce the reduction. DTA measurements as a function
of the heating rate (2–50°C min−1) helped in the derivation of non-isothermal kinetic parameters strongly supportive of the mechanism envisaged.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
53.
Rene S. Schwartz Norman G. Lederman Fouad Abd‐El‐Khalick 《School science and mathematics》2000,100(4):181-193
This report describes an evaluation project that aimed to assess the potential of two elementary science specialists, as compared to elementary classroom teachers, to realize the reforms vision for science instruction in elementary classrooms. Participant science specialist background, views of elementary science teaching, and planning and assessment practices were compared to those of regular elementary classroom teachers in the specialist district, as well as in a comparable district not employing specialists. Specialists' views and practices were better aligned with those envisioned by current national reform documents in science education. Despite the constraints imposed by the nature of a program evaluation, the present report provides evidence to suggest that students taught by the science specialists (a) were engaged in open‐ended, inquiry‐oriented, science‐based activities of the kind often advocated, but mostly absent, in elementary school, and (b) demonstrated problem solving and higher order and critical thinking skills. This report is the first to provide empirical support for the advocated “effectiveness” of elementary science specialists in achieving the visions espoused by current reform efforts. 相似文献
54.
Seda Kzlel Víctor H. Prez‐Luna Fouad Teymour 《Macromolecular theory and simulations》2006,15(9):686-700
Summary: A general mathematical model has been developed to describe the surface initiated photopolymerization of PEG‐DA forming crosslinked hydrogel membranes upon the surface of a substrate. Such membranes are formed by photopolymerizing a PEG‐DA prepolymer solution by initiation with eosin‐Y‐functionalized surfaces and TEA using VP as accelerator. Experimental measurements of the thickness of hydrogel membranes compare well with the model. The model is developed by using the pseudo‐kinetic approach and the method of moments, and is capable of predicting the crosslink density and thickness of the hydrogel membrane. Parametric sensitivity of the effects of PEG‐DA, VP and coinitiator TEA concentration towards the crosslink density and the thickness of the hydrogel is also investigated. The results obtained for different PEG‐DA and VP concentrations suggest that the concentration ratio of these two monomers is a key parameter in controlling the gel thickness and permeability. This model can also be applied to systems where drugs, proteins or cells are encapsulated through surface initiated photopolymerization to predict the growth and crosslink density profiles of the encapsulating membrane. In a previous study we have experimentally demonstrated that these membranes could be made to attach covalently to the surface of the underlying substrate.
55.
O. A. Fouad 《Crystal Research and Technology》2006,41(9):880-884
Nanostructured tin oxide have been synthesized in one‐step process by a novel simple thermal reduction‐oxidation route. The results show that tin oxide nanowires and nanorods could be synthesized via thermal treatment of a mixture of tin oxide and charcoal powder in air at 1000‐1250°C. At a relatively low temperature, 1000°C, and time, 30 min, the tin oxide structure was found to be a bundle of dense nanorods. By increasing the reaction time to 180 min at the same temperature (1000°C), the bundles separated to form liberated individuals nanowires with almost round cross sectional view. With the increase of temperature and time, the morphology of tin oxide nanostructures varied from nanowires to well‐defined tetragonal rods. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
56.
Sophie Peeterbroeck Fouad Laoutid Benjamin Swoboda Jos‐Marie Lopez‐Cuesta Nicolas Moreau Janos B. Nagy Michaël Alexandre Philippe Dubois 《Macromolecular rapid communications》2007,28(3):260-264
Nanocomposites based on an ethylene–vinyl acetate copolymer (27 wt.‐% vinyl acetate) and multiwall carbon nanotubes (MWNTs) have been prepared by melt blending and their thermal degradation and flame retardant properties have been evaluated. Special attention has been paid to the influence of the nanotube nature on the flammability properties and more particularly on the time to ignition (TTI) as measured by cone calorimetry. It has been shown that there is a strong influence of the nature of carbon nanotubes on the fire behaviour of the composites, especially previous MWNTs crushing proved to substantially delay the TTI while maintaining much reduced heat release rate (HRR). Such a remarkable behaviour might be explained by the chemical reactivity of radical species present at the surface/extremities of crushed MWNTs during the combustion process.
57.
Fouad M. Soliman Ahmed A. El-Kateb Ibtisam T. Hennawy Hoda A. Abdel-Malek 《Heteroatom Chemistry》1994,5(2):121-124
1,2,3-Indantrione ( 1 ), diphenylpropanetrione( 6 ), and alloxan ( 8 ) can be converted by reactions with ketenylidene-( 2a ) and thioketenylidenetriphenylphosphorane ( 2b ) into phosphoranylidenecyclobutanes ( 5 , 7 , and 9 ). The structures of the new cyclic compounds were confirmed on the basis of elemental analysis and spectral studies. 相似文献
58.
Production of hybrid organic/inorganic complexes such as lanthanide phosphors in the nanodomain for human fingerprint visualization and anti‐counterfeiting ink under biocompatible UVA and blue light has not yet been studied that thoroughly. This paper presents the preparation of novel, bifunctional, green and red nanophosphors based on Eu3+ and Tb3+ complexes with quinolinone ligand (H2L). They have been prepared and characterized for latent fingerprint detection and anti‐counterfeiting ink applications. The analytical data confirm that the ligand acts in a monoanionic bidentate manner through OO donor sites, forming mononuclear complexes, formulated as [Ln(HL)3(C2H5OH)3] (Ln = Eu3+ or Tb3+; L = 1‐ethyl‐4‐hydroxy‐3‐(nitroacetyl)quinolin‐2‐(1H)‐one). The Eu3+ and Tb3+ complexes have nanospherical morphologies with average particle sizes of 17 and 5 nm, respectively. Pure red and green photoluminescence with long lifetime values has been obtained from the Eu3+ and Tb3+ complexes, respectively, under non‐harmful UVA and blue illumination. Latent fingerprint details, including their characteristic three levels, have been clearly identified from various forensic (non‐porous, semi‐porous, highly fluorescent porous) substrates using red (Eu3+) and green (Tb3+) nanophosphors. The green nanophosphor powder has a greater capability for visualizing latent fingerprints from highly fluorescent porous surfaces as compared to the red one. Both nanophosphor complexes have been used to develop luminescent ink for anti‐counterfeiting applications. 相似文献
59.
60.
El‐Refaie Kenawy Fouad I. Abdel‐Hay Abd El‐Raheem R. El‐Shanshoury Mohamed H. El‐Newehy 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2384-2393
Antimicrobial copolymers bearing quaternary ammonium and phosphonium salts based on a copolymer of glycidyl methacrylate and 2‐hydroxyethyl methacrylate were synthesized. Poly(glycidyl methacrylate‐co‐2‐hydroxyethyl methacrylate) was modified for the introduction of chloromethyl groups by its reaction with chloroacetyl chloride. The chloroacetylated copolymer was modified for the production of quaternary ammonium or phosphonium salts. The antimicrobial activity of the obtained copolymers was studied against gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella sp., and Salmonella typhae), gram‐positive bacteria (Bacillus subtilus and B. cereus), and the fungus Trichophyton rubrum by the cut‐plug method. The results showed that the three copolymers had high antimicrobial activity. A control experiment was carried out on the main polymer without ammonium or phosphonium groups. The copolymer bearing quaternary salt made from tributyl phosphine was the most effective copolymer against both gram‐negative and gram‐positive bacteria and the fungus T. rubrum. The diameters of the inhibition zones ranged between 20 and 60 mm after 24 h. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2384–2393, 2002 相似文献