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231.
232.
A. Kovacs L. Wojnarovits M. Baranyai A. Moussa I. Othman W. L. McLaughlin 《Radiation Physics and Chemistry》1999,55(5-6):795-798
The radiolytic reactions of the ditetrazolium salt nitro blue tetrazolium chloride (NBTCl2) were studied by pulse radiolysis technique in aqueous solution under reducing and oxidising conditions with the aim of potential dosimetry application. Under reducing conditions the fast formation of the tetrazolinyl radical is observed that is followed by the appearance of monoformazan (MF+), i.e. one of the tetrazolium rings is reduced to formazan. The formation of the water-insoluble diformazan, i.e. the result of the second reduction step was not observed in pulse radiolysis. Formazan formation was not found under oxidative conditions. 相似文献
233.
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235.
Othman M.K. Alsmadi Zaer. S. Abo-Hammour Adnan M. Al-Smadi 《Applied Mathematical Modelling》2011,35(9):4620-4629
This paper presents a new technique for model order reduction (MOR) that is based on an artificial neural network (ANN) prediction. The ANN-based MOR can be applied for different scale systems with substructure preservation. In the proposed technique, the ANN is implemented for predicting the unknown elements of the reduced order model. Prediction of the ANN architecture is based on minimizing the cost function obtained by the difference between the actual and desired system behaviour. The ANN prediction process is pursued while maintaining the full order substructure in the reduced model. The proposed ANN-based model order reduction method is compared to recently published work on MOR techniques. Simulation results verify the validity of the new MOR technique. 相似文献
236.
Sameh H. Othman Azza H. Ali Nabil A. Mansour Bahgat E. El-Anadouli 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):685-698
In this study, a new mathematical model was suggested to account for the effect of internal and external diffusion on fluid–solid
noncatalytic reactions. The special features of this model are the combination of the transport processes and the chemical
reaction kinetics with the added factor due to the structural properties of the solid reactant. The model was examined theoretically
and experimentally. A reactive cloth filter that separates radionuclides from radioactive waste solutions is used as a practical
application for the model. Analyses of the respective rate data in accordance with another two theoretical models showed that
process is controlled by the rate of the diffusion step. The external and internal mass transfer constants across the liquid
film and the resin matrix were determined from the graphical representation of the proposed model. The practical validation
with the theoretical results offered satisfactory agreement at most of the process stages. 相似文献
237.
Liliana Boiaryna Dr. Mohamed Kamal El Mkaddem Dr. Catherine Taillier Prof. Vincent Dalla Dr. Mohamed Othman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(44):14192-14200
Gold catalysts have been applied in cascade‐type reactions for the synthesis of different nitrogen‐based compounds. The reactions likely proceed by a new gold‐catalyzed cascade intermolecular α‐amidoalkylation/intramolecular carbocyclization cascade process by unifying both the σ‐ and π‐Lewis acid properties of the gold salts. In the first part of this report we show that the σ‐Lewis acidity of gold(I) and gold(III) could be exploited to efficiently catalyze the nucleophilic substitution of various alkoxy‐ and acetoxylactams. The reaction was found to be applicable to a wide range of cyclic N‐acyliminium ion precursors and various nucleophiles, including allyltrimethylsilane, silyl enol ethers, arenes, and active methylene derivatives. As a logical progression of this study, a combined hard/soft binary catalytic gold system was then used to implement an unprecedented tandem intermolecular Friedel–Crafts amidoalkylation/intramolecular hydroarylation sequence allowing an expedient access to new, complex, fused polyheterocyclic structures from trivial materials. 相似文献
238.
Imran Ali Zeid A. AL‐Othman Norikaju Nagae Vinay D. Gaitonde Kamlesh K. Dutta 《Journal of separation science》2012,35(23):3235-3249
New generation columns, i.e. packed with superficially porous silica particles are available as trade names with following manufacturers: Halo, Ascentis Express, Proshell 120, Kinetex, Accucore, Sunshell, and Nucleoshell. These provide ultra‐fast HPLC separations for a variety of compounds with moderate sample loading capacity and low back pressure. Chemistries of these columns are C8, C18, RP‐Amide, hydrophilic interaction liquid chromatography, penta fluorophenyl (PFP), F5, and RP‐aqua. Normally, the silica gel particles are of 2.7 and 1.7 μm as total and inner solid core diameters, respectively, with 0.5‐μm‐thick of outer porous layer having 90 Å pore sizes and 150 m2/g surface area. This article describes these new generation columns with special emphasis on their textures and chemistries, separations, optimization, and comparison (inter and intra stationary phases). Besides, future perspectives have also been discussed. 相似文献
239.
Za'er S. Abo-Hammour Othman M.K. Alsmadi Adnan M. Al-Smadi Maha I. Zaqout Mohammad S. Saraireh 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(2):201-221
A new method for simultaneously determining the order and the parameters of autoregressive moving average (ARMA) models is presented in this article. Given an ARMA (p, q) model in the absence of any information for the order, the correct order of the model (p, q) as well as the correct parameters will be simultaneously determined using genetic algorithms (GAs). These algorithms simply search the order and the parameter spaces to detect their correct values using the GA operators. The proposed method works on the principle of maximizing the GA fitness value relying on the deviation between the actual plant output, with or without an additive noise, and the estimated plant output. Simulation results show in detail the efficiency of the proposed approach. In addition to that, a practical model identification and parameter estimation is conducted in this article with results obtained as desired. The new method is compared with other well-known methods for ARMA model order and parameter estimation. 相似文献
240.
In addition to the conversion from p-type to n-type conductivity that occurs in Ge–Se–Bi thin films when Bi is incorporated in a certain concentration. We found that, when these films were illuminated to UV light, after being annealed at glass transition temperature T g, the photobleaching is dominant for Ge20Se80?x Bi x (x=0, 2.5, and 5 at.%), while for Ge20Se72.5Bi7.5 photodarkening is dominant. The photoinduced changes in the optical constants were studied. The refractive index (n) has been analysed according to the Wwmple–DiDominico single oscillator model and the values of E o and E d for exposed and unexposed films were determined, respectively. The photostructural effects were discussed in the light of single–double well model proposed by Tanaka and chemical bond approach. 相似文献