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1.
B. A. Mansour S. E. Demian H. Shaban F. El Akkad 《Journal of Materials Science: Materials in Electronics》1994,5(1):38-40
The room temperature photoelectric response of undoped and lithium-doped Zn1–xMgxTe (0 x 0.50) alloys has been measured in the wavelength range 0.50 3.0 m. The response curve for undoped samples is characterized by a single peak in the band edge region. The peak shifts with composition in accordance with the expected shift in the energy band gap. Lithium-doped samples show an additional peak centred at 1.04 eV for all compositions. This peak is attributed to photo-generated holes in the split-off band created as the result of electronic transitions to shallow acceptor impurities. 相似文献
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Xia Liu Xuemei Pan Demian I. Njoku Kelechi J. Uwakwe Yugui Zheng 《Journal of Adhesion Science and Technology》2020,34(19):2047-2074
AbstractThe corrosion inhibition and adsorption behavior of glutamic acid (Glu), glutamine (Gln), and their cerium complexes: cerium glutamate (Ce(Glu)) and cerium glutamine (Ce(Gln)) on mild steel in 0.5?M HCl solutions were studied at 25 and 55?°C and concentration range of 25–200?ppm using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopic (EIS) techniques. The inhibition efficiency was found to be dependent on the concentration and temperature of the system. The potentiodynamic polarization results suggest that the compounds act as mixed-type inhibitors with dominant cathodic inhibition. The mechanism of adsorption deduced from the variation of inhibition efficiency with temperature, as well as the activation parameters, suggest significant physisorption of the inhibitor molecules on the metal surface. The experimental data adhere to the Langmuir and El-Awady et al. kinetic adsorption models. The extent of inhibition was found to be Ce-Gln?>?Gln and Ce-Glu?>?Glu. The scanning electron microscope was employed for the morphological studies and the characteristic of the protective layer on the steel surface verified using UV-Vis spectroscopy and FTIR spectroscopy. Adsorption of the inhibitors on Fe (110) surface was evaluated theoretically. 相似文献
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D. Garcia-Alonso N. Serres C. Demian S. Costil C. Langlade C. Coddet 《Journal of Thermal Spray Technology》2011,20(4):719-735
Lasers have been used to improve the ultimate performance of thermal spray coatings for specific applications, but the full
potential of additional laser treatments must be further explored. Laser treatments (auxiliary processes) can be applied before,
during or after thermal spraying (main process), leading to a wide range of coating improvements (microstructure, adhesion,
etc.). The aim of this review is to introduce the most significant laser treatments for thermal spray applications. The potential
improvements for thermal spray coatings are illustrated by a selection of representative research cases. Laser pretreatments
(ablation and texturing) promote coating/substrate adhesion and are suitable to prepare the surface of sensitive substrates
such as aluminum, titanium, or magnesium alloys. The use of these techniques, which leads to several benefits such as surfaces
free of grit-particle inclusions, directly improves the quality of coatings. Laser treatments applied simultaneously during
the spraying process deeply modify the coatings microstructure. These hybrid technologies allow in situ laser melting of coatings,
resulting in improved mechanical properties and enhanced wear and corrosion behaviors. Finally, laser posttreatments can improve
coatings density and adhesion, and also induce phase transformations and structure refinement. As a summary, laser treatments
seem particularly promising for improving the thermal spray coating microstructure and the coating/substrate adhesion. In
addition, they offer a more environmentally friendly alternative to the conventional surface preparation treatments. 相似文献
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This paper investigates the use of text analysis techniques to measure relevance between objects in product models. This relevance measure is used to support design reuse from an archive of product models from previous projects. We consider several techniques from the field of information retrieval for comparing documents. Next, we explore whether we can improve the performance of the relevance measure by considering contextual building model elements. The paper concludes with an evaluation and discussion of the techniques considered. We conclude that relatively good retrieval results can be achieved with short texts and sparse building models such as those that occur in current industry practice. 相似文献
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H. H. Afify S. A. Nasser S. E. Demian 《Journal of Materials Science: Materials in Electronics》1991,2(3):152-156
The influence of substrate temperature on the structural, optical and electrical properties of ZnO films prepared by the spray pyrolysis method using aqueous solution of zinc acetate has been investigated. The films are polycrystalline and X-ray diffraction measurements show a strong preferred orientation along the [002] plane which is strongly dependent on the substrate temperature. Optical absorption spectra, show high transparency of the film (90–95% transmission) in the visible range, with a sharp absorption edge around 375 nm wavelength of light which closely corresponds to the intrinsic band gap of ZnO (3.3 eV). ZnO films with the lowest resistivity, which is due to the increased mobility resulting from the improvement of the crystallinity of the films, can be prepared at a substrate temperature of 490 °C. 相似文献
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B. A. Mansour S. E. Demian H. A. Zayed 《Journal of Materials Science: Materials in Electronics》1992,3(4):249-252
An investigation was made of the plasma reflection of light and the results were used to find the effective mass of highly degenerate copper selenide,p>1020 cm–3, as a function of carrier concentrationp. The study of the temperature dependence of effective mass, electrical conductivity, thermoelectric power and Hall mobility carried out in the present work gives an idea of the nature of the valence bands in these materials. 相似文献
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Daniela P. F. Bonfim Cssia S. Santana Marcelo S. Batista Demian P. Fabiano 《化学工程与技术》2019,42(4):882-888
CuO/[Si]MCM‐41 catalysts with various Si/Cu molar ratios were prepared and characterized by X‐ray diffraction, nitrogen physisorption, temperature‐programmed reduction by H2, and UV‐vis and Raman spectroscopy. The effects of copper loading and pH on their activity in the decolorization of methyl orange were studied in a heterogeneous Fenton‐like process. With decreasing Si/Cu ratio, dye decolorization increased from 18 to 75 % at pH 3. CuO/[Si]MCM‐41 catalysts showed 75, 50, and 40 % conversion of methyl orange at pH 3, 5, and 7, respectively. This is a significant improvement to Fenton‐like reactions involving copper, and thus CuO/[Si]MCM‐41 catalysts are quite promising for pollutant degradation. 相似文献
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Camelia Demian Sophie Costil Pierre Sallamand Adriana Soveja Hanlin Liao Simone Matteï 《Surface & coatings technology》2012
Mechanical bonding and interface behaviour play a key role for any materials deposited on different substrates. Usually, a post-spray heat treatment is required to improve the coating morphology and to enhance mechanical properties of thermal-sprayed polymeric coating. The effects of YAG, CO2 and diode laser radiations on as-sprayed PEEK coating deposited on stainless steel and aluminum substrates were investigated. The results revealed a good coating densification and interface behavior. A correlation between coating and substrate absorption coefficients, their thermophysical properties and laser operating parameters was shown. Besides, the finite element modeling based on IR temperature measurements during diode laser irradiation demonstrated that the densification of organic coating occurs above its melting point. 相似文献
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