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81.
82.
I. Hashim M.S.M. Noorani R. Ahmad S.A. Bakar E.S. Ismail A.M. Zakaria 《Chaos, solitons, and fractals》2006,28(5):1149-1158
In this paper, the Adomian decomposition method (ADM) is applied to the famous Lorenz system. The ADM yields an analytical solution in terms of a rapidly convergent infinite power series with easily computable terms. Comparisons between the decomposition solutions and the fourth-order Runge–Kutta (RK4) numerical solutions are made for various time steps. In particular we look at the accuracy of the ADM as the Lorenz system changes from a non-chaotic system to a chaotic one. 相似文献
83.
Chitosan acetate–adipic acid film polymer electrolytes have been prepared by the solution cast technique. The highest conductivity
is 1.4 × 10−9 S cm−1 for 35 wt.% of adipic acid at room temperature. The sample with highest conductivity has the lowest activation energy. Calculations
using the Rice and Roth model provide number of mobile ions, η. The conductivity is dependent on the diffusion coefficient and mobility. 相似文献
84.
This Note deals with the identifiability of non-smooth defects by boundary measurements. We prove the uniqueness of the detection by two measurements for arbitrary closed sets satisfying quasi-everywhere a conductivity assumption. This assumption is satisfied by a large class of compact sets, including all the sets which can be written as an arbitrary union of continua of positive diameter. The conductivity is a new regularity concept which is related to the thickness of the set and is to be compared to the Wiener regularity. In order to rigorously justify the numerical approach by the finite element method, we provide a stability result without any a priori smoothness assumptions. To cite this article: Z. Belhachmi, D. Bucur, C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
85.
Bouhadjar Boukoussa Zahira Kibou Zakaria Abid Rachida Ouargli Noureddine Choukchou-Braham Didier Villemin Abdelkader Bengueddach Rachida Hamacha 《Chemical Papers》2018,72(2):289-299
Mesoporous silica Si-MCM-41 was prepared by hydrothermal method using TEOS and CTAB as the source of silica and structuring agent, respectively. The surface of the as-synthesized material was treated using HCl/ETOH solvent to remove the CTA surfactant instead of using the calcination. Characterization of the catalysts was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen sorption at 77 K, scanning and transmission electronic microscopy (SEM, TEM), and thermogravimetric analysis TGA. The catalytic properties of the prepared materials in the condensation of acetophenone with ethyl cyanoacetate were studied. The effects of the catalyst type, Si/Al ratio, reaction kinetics, and reaction temperature were also investigated to find an optimal parameter. The results show that an interesting yield was obtained (about 96%) in a short reaction time; it is found that the yields of products depend not only on the amount of surfactant inside the mesopores but also on the Si/Al ratio. The catalyst reuse shows that this catalyst can be used up to five cycles, and at temperatures higher than 50 °C, the yield of products decreases due to the slight destruction of the catalyst as confirmed by the XRD analysis. Based on the results obtained, a possible mechanism of the condensation reaction of acetophenone was proposed. 相似文献
86.
87.
Starting with 3,5-diphenylcyclohex-2-en-1-one, 3,5-diphenylcyclohex-2-en-1-semicarbazone, 1-chloro-3,5-diphenylcyclohex-2-en-2-carbaldehyde, and 3,5-diphenylcyclohex-2-en-1-hydrazone were synthesized via the reactions with semicarbazide hydrochloride, POCl3/ dimethylformamide, and hydrazine hydrate, respectively. These products were used as key intermediates for the preparation of novel series of tetrahydrobenzothiadiazol-1-oxide, indazole, benzo-thiazepines, pentahydroxyhexylidene and N-thiazines. Some of these derivatives exhibit high antibacterial activity against Gram-positive bacteria. 相似文献
88.
Mohammadreza Gharibreza John Kuna Raj Ismail Yusoff Zainudin Othman Wan Zakaria Wan Muhamad Tahir Muhammad Aqeel Ashraf 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):1715-1730
The Bera Lake basin is a lacustrine mire system and the largest natural lake in Peninsular Malaysia. Three cores were collected from the lake sediments in order to assess sediment quality and ecological risks for aquatic life and human health. An index analysis approach (C f , C d , E r , and IR) and fallout 210Pb and 137Cs radioisotopes were applied to assess the impacts of environmental evolutionary changes. Sediment chronology was determined using the Constant Rate of Supply model with the resultant ages verified by 137Cs horizons. Although the general contamination factors indicate low risk conditions in Bera Lake the risks associated with individual layers ranged from moderate to considerable. Five deforestation phases can be identified in the dated sediment cores with distinct variations in heavy metal influxes since 1972. These phases are in excellent agreement with the dates of land clearance and development projects undertaken over the past four decades. This study has highlighted the capability of contamination factors and chronological methods in environmental evolutionary studies where catchments have experienced extensive land use changes. The destiny of heavy metal influxes into a lake can also be revealed using this methodology. 相似文献
89.
Zakaria H. Aiube Sabah T. Najiam Abdul Amir H. Kadhum 《Research on Chemical Intermediates》2013,39(6):2351-2355
The compounds (E)-1,2-diphenyl-2-(phenylimino)ethanol, (E)-1,2-diphenyl-2-(p-tolylimino)ethanol, and (E)-2-((4-chlorophenyl)imino)-1,2-diphenylethanol) were synthesized by reaction of a p-substituted aniline with benzoin then oxidized with chromium trioxide–triethylamine in chloroform to give (E)-1,2-diphenyl-2-(phenylimino)ethanone, (E)-1,2-diphenyl-2-(p-tolylimino)ethanone, and (E)-2-((4-chlorophenyl)imino)-1,2-diphenylethanone in very high yield. The products were characterized by IR and NMR spectral analysis. 相似文献
90.
The adsorption of Cu(II) ions onto the chitosan derived Schiff bases obtained from the condensation of chitosan with salicyaldehyde (polymer I), 2,4-dihydroxybenzaldehyde (polymer II) and with 4-(diethylamino) salicyaldehyde (polymer III) in aqueous solutions was investigated. Batch adsorption experiments were carried out as a function of contact time, pH, and polymer mass. The amount of metal-ion uptake of the polymers was determined by using atomic absorption spectrometry (AAS) and the highest Cu(II) ions uptake was achieved at pH 7.0 and by using sodium perchlorate as an ionic strength adjuster for polymers I, II, and III. The isothermal behavior and the kinetics of adsorption of Cu(II) ions on these polymers with respect to the initial mass of the polymer and temperature were also investigated; adsorption isothermal equilibrium data could be clearly explained by the Langmuir equation. The experimental data of the adsorption equilibrium from Cu(II) solution correlates well with the Langmuir isotherm equation. 相似文献