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991.
Hossein Eshghi Elham SafaeiSeyed Mohamad Seyedi Tahereh Eshghi 《Comptes Rendus Chimie》2014,17(11):1088-1093
Fe(HSO4)3·SiO2 is used to catalyze the condensation of β-diketones and β-keto esters with aromatic and aliphatic diamines in solvent-free conditions at room temperature. This afforded the corresponding bis-(β-enaminones) and bis-(β-enamino esters) in very good to excellent yields. Short reaction times, easy work-up procedure, and reusability of the catalyst are the merits of this study. 相似文献
992.
Nargess Mehdipour Neda Mousavian Hossein Eslami 《Journal of the Iranian Chemical Society》2014,11(1):47-52
A new molecular dynamics simulation technique for simulating fluids in confinement [H. Eslami, F. Mozaffari, J. Moghadasi, F. Müller-Plathe, J. Chem. Phys. 129 (2008) 194702] is employed to simulate the diffusion coefficient of nanoconfined Lennard-Jones fluid. The diffusing fluid is liquid Ar and the confining surfaces are solid Ar fcc (100) surfaces, which are kept frozen during the simulation. In this simulation just the fluid in confinement is simulated at a constant temperature and a constant parallel component of pressure, which is assumed to be equal to the bulk pressure. It is shown that the calculated parallel (to the surfaces) component of the diffusion coefficients depends on the distance between the surfaces (pore size) and shows oscillatory behavior with respect to the intersurface separations. Our results show that on formation of well-organized layers between the surfaces, the parallel diffusion coefficients decrease considerably with respect to the bulk fluid. The effect of pressure on the parallel diffusion coefficients has also been studied. Better organized layers, and hence, lower diffusion coefficients are observed with increasing the pressure. 相似文献
993.
A novel ‘ionic liquid-mediated multi-walled carbon nanotube (MWCNT)-poly(dimethylsiloxane) (PDMS)’ hybrid coating was prepared by the covalent functionalization of MWCNTs with hydroxyl-terminated PDMS using the sol–gel technique. The prepared fiber was successfully used for the separation and determination of trace amounts of polycyclic aromatic hydrocarbon compounds (PAHs) in four urine samples using head-space solid-phase microextraction coupled to gas chromatography-flame ionization detection. The proposed fiber has high thermal stability and long durability and it can be used more than 210 times without any significant change in its sorption properties. The effects of important parameters such as the exposure time, sampling temperature, sample ionic strength and stirring rate on the extraction efficiency have been studied and optimized. Under the optimal conditions, the method detection limits (S/N = 3) were in the range of 0.0005–0.004 ng mL?1 and the limits of quantification (S/N = 10) between 0.002 and 0.01 ng mL?1. The relative standard deviations for one fiber (repeatability, n = 5) were 4.9–7.5 % and for the fibers obtained from different batches (reproducibility, n = 3), 6.1–8.9 %. The developed method was successfully applied to determine trace levels of PAHs in real urine samples. The obtained relative recoveries for the spiked samples with 0.05 ng mL?1 of each of the PAH compounds were 89.3–107.2 %. 相似文献
994.
Hossein Mahmoodi Darian Reza Bozorgpour Maziar Shafaee 《Numerical Methods for Partial Differential Equations》2019,35(6):2375-2406
In the present paper, a hybrid filter is introduced for high accurate numerical simulation of shock‐containing flows. The fourth‐order compact finite difference scheme is used for the spatial discretization and the third‐order Runge–Kutta scheme is used for the time integration. After each time‐step, the hybrid filter is applied on the results. The filter is composed of a linear sixth‐order filter and the dissipative part of a fifth‐order weighted essentially nonoscillatory scheme (WENO5). The classic WENO5 scheme and the WENO5 scheme with adaptive order (WENO5‐AO) are used to form the hybrid filter. Using a shock‐detecting sensor, the hybrid filter reduces to the linear sixth‐order filter in smooth regions for damping high frequency waves and reduces to the WENO5 filter at shocks in order to eliminate unwanted oscillations produced by the nondissipative spatial discretization method. The filter performance and accuracy of the results are examined through several test cases including the advection, Euler and Navier–Stokes equations. The results are compared with that of a hybrid second‐order filter and also that of the WENO5 and WENO5‐AO schemes. 相似文献
995.
Motivated by considerable interests of Myers–Perry black holes, we employ the perturbative method to obtain a family of extremal charged rotating black hole solutions in odd dimensional Einstein–Born–Infeld-dilaton gravity. We start with an extremal Myers–Perry black hole with equal angular momenta, and then by adding the dilaton field and the nonlinear Born–Infeld electrodynamics, we find an extremal nonlinearly charged rotating black holes. The perturbative parameter is assumed to be the electric charge q and the perturbations are performed up to the third order. We then study the physical properties of these Born–Infeld-dilaton black holes. In particular, we show that the perturbative parameter, q, the dilaton coupling constant, α, and the Born–Infeld parameter, β, modify the Smarr formula and the values of the gyromagnetic ratio of the extremal charged rotating black holes. 相似文献
996.
Hossein Shirani IL Beigi 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(9):1537-1541
DFT calculations are applied for some stable C60, C59Si, and C59N hetero fullerenes. Sn and Ge atoms are doped at the same position of C60. Computations are carried out at the B3LYP/cc pVDZ levels. In this work the effects of the heteroatoms, Si and N, on the structural properties of the fullerene have been studied. The structure, energetic and relative stabilities of the compounds were compared and analyzed with each other. In addition, vibrations spectra of proposed stable neutral species, as well as the infrared intensities are calculated. From the data obtained from calculation, we found that there is strong correlation between the stability of pure C60 fullerene molecule and the numbers of different C-C bonds. 相似文献
997.
An isocyanide‐catalyzed reaction between tetracyanoethylene and various activated CH‐acid compounds to afford the corresponding pyran annulated heterocyclic ring systems, in high yield at room temperature within a few minutes, is described. To the best of our knowledge, this is the first example in which isocyanide functions as only a catalyst but not a reagent. 相似文献
998.
Hossein A. Oskooie Negar M. Javadi Khadijeh Bakhtiari Fatemeh F. Bamoharram 《合成通讯》2013,43(17):2864-2869
Condensation of a variety of β-dicarbonyl compounds with primary and secondary amines carried out in the presence of catalytic amounts of K7[PW11CoO40]. From this reaction N-substituted β-enamino esters and ketones were obtained in high yields. 相似文献
999.
Triphenylphosphine, dialkyl acetylenedicarboxylates, and phthalic anhydride react in one pot to afford novel spirocyclic compounds in fairly good yields at room temperature. 相似文献
1000.
Firouz Matloubi Moghaddam Seyedeh Maryam DokhtTaimoory Hossein Ismaili Ghasem Rezanejade Bardajee 《合成通讯》2013,43(23):3599-3607
KF/Al2O3 efficiently catalyzes N‐alkylation of heterocyclic, primary, and secondary amines and S‐alkylation of thiols with a variety of alkyl halides. The N‐alkylation and S‐alkylation adducts were produced in good to excellent yields and in short times. 相似文献