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961.
Mostafa Hossein Beyki Mohammad Javad Aghagoli 《International journal of environmental analytical chemistry》2017,97(3):201-216
In the present work, synthesis of polymer wrapped flower-like MgAl layered double hydroxide was done through condensation of 1,4 phenylenediamine and resorcinol by p-formaldehyde. The nanocomposite was characterised with X-ray diffraction analysis, fourier transform infrared spectroscopy, thermogravimetric analysis and field emission scanning electron microscopy techniques and employed for effective adsorption of Cr(VI) from aqueous solution prior to flame atomic absorption spectrometer determination. Optimum level of effective parameters (pH, reaction time and adsorbent dosage) and their interaction was determined by response surface methodology. To investigate applicability of method for trace heavy metal adsorption, the method was employed for preconcentration of Cr(VI) in water samples. At the optimum conditions, pH = 4.5, shaking time of 15 min and adsorbent dosage of 20 mg, analytical performance of the method was evaluated and results showed that calibration curve is linear in the concentration range of 2–100 μg L?1. Moreover, limit of detection was 0.22 µg L?1 and relative standard deviation of six replicate experiments at initial concentration of 0.1 mg L?1 was 3.3%. Isotherm study showed that Freundlich model can better describe adsorption behaviour as well as the sorbent showed the adsorption capacity of 62.5 mg g?1. Moreover, thermodynamic study revealed that chromate adsorption was spontaneous and followed the endothermic path. Regeneration of sorbent was performed using 1.0 mol L?1 of NaOH solution. The sorbent was employed for Cr(VI) determination from food additives and seawater samples. 相似文献
962.
Sultan Maha A. El-Alamin Maha M. Abou Atia Mostafa A. Aboul-Enein Hassan Y. 《平面色谱法杂志一现代薄层色谱法》2017,30(1):68-74
JPC – Journal of Planar Chromatography – Modern TLC - Rapid and sensitive thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC)—densitometry... 相似文献
963.
964.
Seyyed Mostafa Hoseini 《Physics and Chemistry of Liquids》2017,55(5):559-569
Knowledge of the volumetric or pressure–volume–temperature (PVT) profile of molten polymers is important for both engineering and polymer physics. Ihm–Song–Mason (ISM) equation of state (EOS) has been employed to predict the volumetric properties of 12 molten polymers. The significance of the present paper is three temperature-dependent parameters of the ISM EOS to be determined using corresponding states correlations based on the molecular scaling constants, dispersive energy parameters between segments/monomers (ε) and segment diameter (σ) rather than bulk properties, e.g. the liquid density and temperature both at normal boiling point. The ability of the ISM EOS has been evaluated by comparing the results with 1390 literature datapoints for the specific volumes over the temperature range from 293 to 603.5 K and pressure range from 0.1 to 200 MPa. The average absolute deviation (AAD) of the calculated specific volumes from literature data was found to be 0.52%. The isothermal compressibility coefficients, κT values of molten polymers have also been predicted using the ISM EOS. From 684 datapoints examined, the AAD of estimated κT was equal to 7.55%. Our calculations on the volumetric and thermodynamic properties of studied polymers reproduce the literature data with reasonably good accuracy. 相似文献
965.
Anglina El Ghaziri Vronique Cariou Douglas N. Rutledge El Mostafa Qannari 《Journal of Chemometrics》2016,30(8):420-429
ComDim analysis was designed to assess the relationships between individuals and variables within a multiblock setting where several variables, organized in blocks, are measured on the same individuals. An overview of this method is presented together with some of its properties. Furthermore, we discuss a new extension of the method of analysis to the case of (K+1) datasets. More precisely, the aim is to explore the relationships between a response dataset and K other datasets. An illustration of this latter strategy of analysis on the basis of a case study involving Time Domain ‐ Nuclear Magnetic Resonance data is outlined and the outcomes are compared with those of Multiblock Partial Least Squares regression. 相似文献
966.
Mostafa Mbekhta 《Proceedings of the American Mathematical Society》2007,135(11):3613-3619
Let be an infinite-dimensional separable complex Hilbert space and the algebra of all bounded linear operators on . In this paper we characterize surjective linear maps preserving the set of Fredholm operators in both directions. As an application we prove that preserves the essential spectrum if and only if the ideal of all compact operators is invariant under and the induced linear map on the Calkin algebra is either an automorphism, or an anti-automorphism. Moreover, we have, either or for every Fredholm operator .
967.
In this paper, the effects of variable thermal conductivity and radiation on the flow and heat transfer of an electrically conducting micropolar fluid over a continuously stretching surface with varying temperature in the presence of a magnetic field are considered. The surface temperature is assumed to vary as a power-law temperature. The governing conservation equations of mass, momentum, angular momentum and energy are converted into a system of non-linear ordinary differential equations by means of similarity transformation. The resulting system of coupled non-linear ordinary differential equations is solved numerically. The numerical results show that the thermal boundary thickness increases as the thermal conductivity parameter S increases, while it decreases as the radiation parameter F increases. Also, it was found that the Nusselt number increases as F increases and decreases as S increases. 相似文献
968.
Avenier P Lesage A Taoufik M Baudouin A Mallmann AD Fiddy S Vautier M Veyre L Basset JM Emsley L Quadrelli EA 《Journal of the American Chemical Society》2007,129(1):176-186
The MCM-41 supported hydrides [([triple bond]SiO)(2)TaH(3)], 1a, and [([triple bond]SiO)(2)TaH(3)], 1b, cleave N-H bonds of ammonia at room temperature to yield the well-defined imido amido surface complexes [([triple bond]SiO)(2)Ta(NH)(NH(2))], 2, and 2xNH(3). Additionally, the surface silanes [[triple bond]Si-H] that exist in close proximity to 1a and 1b also react with ammonia at room temperature to give the surface silylamido [Si-NH(2)]. Such reaction is tantalum assisted: surface silanes were synthesized independently and in absence of tantalum by reaction of highly strained silica, SiO(2-1000), with SiH(4) and no reaction with ammonia was observed. Surface-supported complexes 2, 2xNH(3), and [[triple bond]Si-NH(2)] have been characterized by, inter alia, solid-state NMR, IR, and EXAFS and independent synthesis of [[triple bond]Si-NH(2)]. The NMR studies on the fully 15N-labeled samples have led to unambiguous discrimination between imido, amido, and amino resonances of 2*, 2*x(15)NH(3), and [[triple bond]Si-15NH(2)] through the combination of solid-state magic angle spinning (MAS), heteronuclear correlation (HETCOR), 2D proton double-quantum (DQ) single-quantum (SQ) correlation, and 2D proton triple-quantum (TQ) single-quantum (SQ) correlation spectra. The in situ IR monitoring of the reaction of 1a and 1b with regular NH(3) and 15NH(3), and after H/D exchange has yielded the determination of all the NH(x) vibration and deformation modes, with their respective H/D and 14N/15N isotopic shifts. EXAFS study yielded the bond distances in 2 of 1.79(2) Angstrom for Ta=N, 1.89(1) Angstrom for Ta-O, and 1.98(2) Angstrom for Ta-N. 相似文献
969.
Mostafa Ahmadi Roghieh Jamjah Mehdi Nekoomanesh Gholam Hossein Zohuri Hassan Arabi 《大分子反应工程》2007,1(6):604-610
A Ziegler‐Natta/metallocene hybrid catalyst was produced and utilized in the polymerization of ethylene with the aim of producing bimodal polyethylene. The MgCl2 adduct was prepared by a melt quenching method and Cp2ZrCl2 and TiCl4 catalysts were loaded, respectively, after treating the surface with TiBAl. The polymerization kinetics involved an induction period, followed by fragmentation and expansion of particles. SEM micrographs revealed that the spherical morphology was retained through the initial mild reaction conditions of induction period. The polymers produced showed bimodal molecular weight distribution patterns, suggesting that both components of the hybrid catalyst were active over the support.
970.
Sk Hafijur Rahaman Doyel Bose Rajarshi Ghosh Golam Mostafa Hoong-Kun Fun Barindra K. Ghosh 《Structural chemistry》2007,18(2):237-244
Reaction of copper(II) perchlorate with N,N′-{bis(pyridin-2-yl)benzylidene}butane-1,4-diamine (bpbd) yielded monoclinic crystals of bluish green [Cu(bpbd)(ClO4)]ClO4 (1), and a similar reaction in presence of azide anion, N3 ? formed monoclinic crystals of dark green [Cu(bpbd)(N3)]2ClO4 (2). Crystal data for 1: space group P21/c, Z=4, a=17.3968(4) Å, b=9.3182(2) Å, c=17.6794(4) Å, β=102.149(1)°. The geometry around Cu(II) centre is distorted square pyramidal with axial site occupied by O atom of perchlorate and in plane Cu is bonded to four N atoms of the organic ligand. The intermolecular C–H...π stacking in 1 forms a zigzag chain (1D) supramer. Crystal data for 2: space group C2/c, Z=4, a=22.3109(4) Å, b=17.7832(3) Å, c=14.3389(2) Å, β=92.553(1)°. In dinuclear 2, Cu(II) has tetragonally distorted octahedral geometry coordinated by four N atoms of bpbd, with the fifth and sixth positions occupied by N atoms of two end-on bridging azides. The π...π interaction leads to a two dimensional (2D) sheet within which the counter anions are embedded. Both the compounds 1 and 2 show simple paramagnetism. Cyclic voltammetry and fluorescence spectra are also reported. 相似文献