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61.
Abdelhamid El-Shaer Mahmoud Abdelfatah Ali Basuni Mohsen Mosaad 《Chinese Journal of Physics (Taipei)》2018,56(3):1001-1009
In this work, ZnO nanorods (NRs) were fabricated using a low cost chemical bath deposition (CBD) method. The effect of the potassium hydroxide concentration on the fabricated ZnO nanostructures was studied in depth. The optical, structure, and surface morphology properties of the fabricated ZnO nanostructures were investigated using Uv-vis spectroscopy, XRD, and SEM. The results indicate that the formation of hexagonally structured ZnO nanorods with different lengths and diameters was dependent on the KOH concentration. The sample prepared with 2 M of KOH was the best one for optoelectronic applications, since it has the smallest diameters. This sample was annealed at different temperatures (473 K–1073 K). Positron Annihilation Lifetime Spectroscopy was used to determine the defects in the ZnO nanorods. The results show that the positron mean lifetime (τm) decreased as the annealing temperature increased, which means that the overall defects in the ZnO nanorods decreased with increasing temperature. Consequently, higher performance semiconductor devices based on ZnO nanorods could be fabricated after high annealing of the ZnO nanorods. 相似文献
62.
A comprehensive study was conducted to investigate the stability of a wide variety of mesoporous silica-supported amine-containing adsorbents in the presence of carbon dioxide under dry conditions. CO(2)-induced degradation of grafted primary and secondary monoamines (pMono, sMono), diamines with one primary and one secondary amines (Diamine) and triamine with one primary and two secondary amines (TRI) as well as different impregnated polyamines such as branched and linear polyethylenimine (BPEI and LPEI) and polyallylamine (PALL) was investigated using extensive CO(2) adsorption-desorption cycling as well as diffuse reflectance infrared Fourier transform (DRIFT) and (13)C CP MAS NMR measurements. Except for sMono, all other supported amines underwent significant deactivation in the presence of dry CO(2) under mild conditions. In all cases, the decrease in CO(2) uptake was associated with the formation of urea linkages at the expense of amine groups. The urea-containing species were identified, and the deactivation pathways were delineated. 相似文献
63.
Magda F. Mohamed Mervat S. Mohamed Samia A. Shouman Mohamed M. Fathi Ismail Abdelshafy Abdelhamid 《Applied biochemistry and biotechnology》2012,168(5):1153-1162
A newly synthesized series of chalcone derivatives containing pyrazole rings were synthesized and evaluated for their cytotoxic activities in vitro against several human cancer cell lines. Most of the prepared compounds showed potential cytotoxicity against human breast cancer cell lines MCF-7, HEPG-2, and HCT-116. Also the compounds were evaluated as antimicrobial agents. The three compounds 3, 4, and 5 were proved to be better anticancer agents than the positive standard doxorubicin with IC50 values (4.7, 4.4, and 3.9???g/ml) against the same human cancer cell lines, whereas compounds 5 and 6 showed the most active antimicrobial compounds in comparison to the other chalcones. 相似文献
64.
Sihem Khaddar-Zine Abdelhamid Ghorbel Claude Naccache 《Journal of Sol-Gel Science and Technology》2000,19(1-3):637-641
Alumina or silica supported chromium oxide catalysts prepared by sol-gel technique have been investigated by X-ray diffraction, BET analysis, combined diffuse reflectance spectroscopy, EPR and reduction-extraction by ethane 1,2 diol. The results reveal the presence of Cr3+, Cr5+ and Cr6+ ions. Chromium species Cr6+ are isolated and atomically dispersed on the alumina support as free chromate CrO
4
2–
while on silica, dichromate or polychromate species like Cr2O
7
2–
or Cr3O
10
2–
predominate. Chromium oxide exhibits a better catalytic properties for paraxylene partial oxidation, when it is supported on alumina. The difference of oxidation states and degree of oligomerisation of chromium on the two supports affects the catalytic properties. 相似文献
65.
Shemseddine Fessi Abdelhamid Ghorbel 《Journal of Sol-Gel Science and Technology》2000,19(1-3):417-420
The chemical reactivity of the aluminium-sec-butoxide (ASB) and the palladium acetylacetonate Pd(acac)2, used as precursors for the preparation of the alumina supported palladium catalysts by sol-gel method was investigated by the spectroscopic study of the precursor mixture during ageing, using FTIR, UV-VIS and 27Al NMR. The obtaind results showed that acetylacetonate ligands were linked to aluminum when the mixture was aged at 40°C. This was proved by the bands observed at 1530 and 1600 cm–1 in the FTIR spectra, the band obtained at 289 nm in the UV-VIS spectra and the 27Al NMR sharp peak at 3 ppm. Furthermore, in order to avoid the Pd(acac)2 reduction to metallic palladium by the SB occurring when the mixture is aged for 3 h, an optimum ageing time should be selected. The precursors modification and the preservation of the palladium oxidation state during ageing could be the required conditions to create a bond between palladium and aluminium during the gelation step. This should be the reason of the thermal stability improvement of the alumina supported palladium catalyst prepared by the sol-gel method. 相似文献
66.
Abdou O. Abdelhamid Sobhi M. Gomha Waleed A. M. A. El‐Enany 《Journal of heterocyclic chemistry》2019,56(9):2487-2493
Sodium salt of 3‐hydroxy‐1‐(1‐aryl‐5‐methylpyrazolyl)propenone derivatives was used as a precursor for synthesis of various fused azolopyrimidine ring systems as pyrazolopyrimidines, triazolopyrimidines, and pyrimidobenzimidazoles following many procedures. The identity of the prepared compounds was elucidated by their spectral data and elemental analyses. The in vitro antimicrobial activity of 13 new compounds was evaluated, and many derivatives showed good to moderate activity. 相似文献
67.
Imane Boubezari Ali Zazoua Franois Bessueille Abdelhamid Errachid Nicole Jaffrezic‐Renault 《Electroanalysis》2020,32(7):1642-1650
Instant determination of glucose levels is necessary to monitor the treatment of diabetes. The next generation of electrochemical sensors aims to eliminate the use of enzymes because of their lack of stability and the complex procedure to immobilize them on the electrode. In this paper Pr1.92Ba0.08Ni0.95Zn0.05O4+δ perovskite, a A2BO4+δ type, was tested, for the first time for non enzymatic detection of glucose. It was synthesized by a sol‐gel method. The obtained crystallized powder was structurally characterized by XRD, morphologically characterized by SEM and EDX and electrochemically characterized. A monoclinic crystallographic system was formed. The presence of Pr2O3 during synthesis and calcination is in agreement with the formation of defects in the crystalline network and the disproportionation of NiIII sites into NiII and NiIV, due to the substitution of Pr by Ba. The oxido‐reduction of NiII sites is observed by cyclic voltammetry. The electrocatalytic oxidation of glucose through the electrooxidized NiII site was observed on a gold electrode, at 481 mV. The analytical performance of this glucose sensor is good in comparison to previously published ABO3 perovskite modified electrodes, in terms of dynamic range (1.5 μM–7000 μM) and detection limit (0.5 μM). Its application to human serum shows that there is no interference for glucose detection. 相似文献
68.
The present work is a first step for the implementation and the development of a rapid and quantitative measurement technique using the UV broadband-lamp absorption spectroscopy. This technique is applied to detect nitric oxide molecules inside the combustion chamber of a methane-fueled spark-ignition engine. The ability of this technique to detect NO in very harsh thermodynamic conditions is proved under certain engine operating conditions. In spite of the broadband absorption, mainly due to the hot CO2 and H2O, clear NO absorption γ-bands are observed when the engine is skip-fired or when NO is added at the intake port. It was however, not possible to detect any nitric oxide absorption during the combustion time when each cycle was ignited and no nitric oxide was added. Finally, using the skip-ignition mode, the acquired NO absorption spectra allowed to conclude that evacuation of the in-cylinder residual gases can be complete at the end of the sixth cycle. 相似文献
69.
Nancy Joumaa Prisca Toussay Muriel Lansalot Abdelhamid Elaissari 《Journal of polymer science. Part A, Polymer chemistry》2008,46(1):327-340
A new strategy relying on the use of a phosphate‐based macromonomer (PAM200) to modify the surface of iron oxide nanoparticles was developed for the synthesis of submicrometer polystyrene (PS) magnetic particles. First, iron oxide nanoparticles were synthesized using the coprecipitation of ferrous and ferric salts in alkaline medium. Besides the classical oleic acid (OA)/octane‐based ferrofluid, styrene‐based ferrofluids were elaborated with either OA or PAM200 as the stabilizer. In all cases, maghemite (γ‐Fe2O3) was clearly identified, with nanoparticles rather spherical in shape but exhibiting broad particle size distribution (PSD). Both OA and PAM200 led to stable maghemite‐based ferrofluids showing superparamagnetic properties. Further use of these ferrofluids in styrene miniemulsion polymerization resulted in inhomogeneous distribution of maghemite among and inside the polymer particles with OA‐based ferrofluids, whereas PAM200/styrene‐based ferrofluids led to magnetic particles with homogeneous distribution of maghemite inside PS particles. Broad PSD and small nonmagnetic particles were however observed. The true mechanisms operating in these systems are still to elucidate, but this study validates PAM200 as an efficient compatibilizing agent between hydrophilic maghemite and hydrophobic PS. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 327–340, 2008 相似文献
70.
S. Ben Nasrallah G. Arnaud A. Trad 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1985,36(1):105-119
Résume On étudie l'évaporation en convection naturelle laminaire sur une plaque plane verticale humide chauffée à densité de flux variable suivant la hauteur. Cette étude faite sous des hypothèses restrictives est conduite par des méthodes semi-analytiques et une méthode numérique. Des comparaisons entre les différentes méthodes et des résultats dans le cas de l'évaporation de l'eau dans l'air pour différentes valeurs du rapportN des poussées d'Archimède à la paroi sont obtenus. Une méthode approchée rapide de détermination deN est ensuite présentée.
Evaporation by laminar natural convection on a wet vertical flate plate heated with a height dependent heat flux is studied. This study, made under restrictive assumptions, is achieved by semi-analytical methods and a numerical method. Comparaison between these methods are made and results are obtained for the case of water evaporation in air for different values ofN; ratio of the buoyancy forces at the wall. Then, a fast approximate method for the determination ofN is presented.相似文献