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71.
Choudhury M. Zakaria George Ferguson Alan J. Lough Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(7):m271-m274
Hexamethylenetetramine, C6H12N4, and ferrocenecarboxylic acid, C11H10FeO2, form a 1:2 adduct, (I), which is a salt, viz. hexamethylenetetraminium(2+) bis(ferrocenecarboxylate), (C6H14N4)[Fe(C5H5)(C6H4O2)]2. The dication in (I) is disordered with two orientations at a site of mm2 symmetry in space group Fmm2, while the anion lies across a mirror plane with its unsubstituted cyclopentadienyl ring disordered over two sets of sites. With ferrocene‐1,1′‐dicarboxylic acid, C12H10FeO4, hexamethylenetetramine forms a 1:1 adduct, (II), in which both components are neutral, viz. hexamethylenetetramine–ferrocene‐1,1′‐dicarboxylic acid (1/1), [Fe(C6H5O2)2]·C6H12N4. The amine component in (II) is disordered with two orientations at a site of mm2 symmetry in space group Cmcm, while the acid component is disordered with two orientations at a site of 2/m symmetry. The components in (I) are linked into a finite three‐ion aggregate by a single N—H⃛O hydrogen bond, while the components of (II) are linked into continuous chains by a single O—H⃛N hydrogen bond. 相似文献
72.
George Ferguson Alan J. Lough David M. Smith Choudhury M. Zakaria Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(8):922-923
In the title compound, [Na(C2H3N2O3)], the Na+ cation lies on a centre of inversion in space group P21/m and all the atoms of the anion lie on a mirror plane. Na is octahedrally coordinated by four O and two N atoms from six different anions and each anion is coordinated to six different Na+ cations, forming chains of confacial octahedra which link the anion layers. Within these layers, the individual anions are linked by both O—H?O and C—H?O hydrogen bonds. 相似文献
73.
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75.
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
76.
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
77.
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
78.
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
79.
80.
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