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381.
Mohammad T. Baei Ali Reza Soltani Parviz Torabi Ali Varasteh Moradi 《Monatshefte für Chemie / Chemical Monthly》2011,51(12):979-984
Abstract
The behavior of the thiocyanate anion (SCN−) adsorbed on the external surface of H-capped (6,0), (7,0), (8,0), and Al-doped (6,0) zigzag single-walled carbon nanotubes was studied by using density functional calculations. Geometry optimizations were carried out at the B3LYP/6-31G* level of theory using the Gaussian 03 suite of programs. We present the nature of the SCN− interaction in selected sites of the nanotubes. Our results show that the pristine carbon nanotubes cannot significantly detect SCN−. The calculated binding energy of the Al-doped (6,0) single-walled carbon nanotubes indicated that SCN− can be adsorbed significantly on the C and Al sites and these nanotubes can therefore be used for SCN− storage. Binding energies corresponding to adsorption of SCN− on the Al site in the Al-doped (6,0) single-walled carbon nanotubes was calculated as −286.38 kJ mol−1. The calculated binding energies for SCN− in N-down orientation are higher than those in S-down orientation for all of the configurations. More efficient binding could not be achieved by increasing the nanotube diameter. We also report the effects of SCN− adsorption on the electronic properties of the nanotubes. 相似文献382.
Mohammad T. Baei Parviz Torabi Ali Varasteh Moradi Masoumeh Moghimi 《Monatshefte für Chemie / Chemical Monthly》2011,18(3):783-788
Abstract
Nuclear magnetic resonance (NMR) parameters including isotropic and anisotropic chemical shielding parameters and electronic structures were calculated using density functional theory (DFT) for silicon–carbide-doped boron phosphide nanotubes. Geometry optimizations were carried out at the B3LYP/6-31G* level of theory using the Gaussian 03 program suite. The isotropic and anisotropic chemical shielding parameters were calculated for the sites of various 13C, 29Si, 11B, and also 31P atoms in pristine and SiC-doped (6,0) zigzag boron phosphide nanotube models. The calculations indicated that doping of 11B and 31P atoms by C and Si atoms had a more significant influence on the calculated shielding tensors than did doping of the B and P atoms by Si and C atoms. In comparison with the pristine model, Si- and C-doping of P and B sites of the zigzag nanotubes reduces the energy gaps of the nanotubes and increases their electrical conductance. 相似文献383.
Sourabh V. Apte Krishnan Mahesh Michael Gorokhovski Parviz Moin 《Proceedings of the Combustion Institute》2009,32(2):2257-2266
Large-eddy simulation of an atomizing spray issuing from a gas-turbine injector is performed. The filtered Navier–Stokes equations with dynamic subgrid scale model are solved on unstructured grids to compute the swirling turbulent flow through complex passages of the injector. The collocated grid, incompressible flow algorithm on arbitrary shaped unstructured grids developed by Mahesh et al. (J. Comp. Phys. 197 (2004) 215–240) is used in this work. A Lagrangian point-particle formulation with a stochastic model for droplet breakup is used for the liquid phase. Following Kolmogorov’s concept of viewing solid particle-breakup as a discrete random process, the droplet breakup is considered in the framework of uncorrelated breakup events, independent of the initial droplet size. The size and number density of the newly produced droplets is governed by the Fokker–Planck equation for the evolution of the pdf of droplet radii. The parameters of the model are obtained dynamically by relating them to the local Weber number and resolved scale turbulence properties. A hybrid particle-parcel is used to represent the large number of spray droplets. The predictive capability of the LES together with Lagrangian droplet dynamics models to capture the droplet dispersion characteristics, size distributions, and the spray evolution is examined in detail by comparing it with the spray patternation study for the gas-turbine injector. The present approach is computationally efficient and captures the global features of the fragmentary process of liquid atomization in complex configurations. 相似文献
384.
Yasser Khalili Nematollah Kadkhoda Dumitru Baleanu 《Mathematical Methods in the Applied Sciences》2020,43(12):7143-7151
In the present work, we consider the inverse problem for the impulsive Sturm–Liouville equations with eigenparameter-dependent boundary conditions on the whole interval (0,π) from interior spectral data. We prove two uniqueness theorems on the potential q(x) and boundary conditions for the interior inverse problem, and using the Weyl function technique, we show that if coefficients of the first boundary condition, that is, h1,h2, are known, then the potential function q(x) and coefficients of the second boundary condition, that is, H1,H2, are uniquely determined by information about the eigenfunctions at the midpoint of the interval and one spectrum or partial information on the eigenfunctions at some internal points and some of two spectra. 相似文献
385.
Ali Rostamnejadi Hadi Salamati Parviz Kameli Hossein Ahmadvand 《Journal of magnetism and magnetic materials》2009,321(19):3126-3131
Magnetic nanoparticles of La0.67Sr0.33MnO3 (LSMO) manganite were prepared by sol-gel method. Phase formation and crystal structure of the synthesized powder were examined by the X-ray diffraction (XRD) using the Rietveld analysis. The mean particle size was determined by the transmission electron microscopy (TEM). Infrared transmission spectroscopy revealed that stretching and bending modes are influenced by calcinations temperature. The temperature dependence of the ac magnetic susceptibility was measured at different frequencies and ac magnetic fields in the selected ranges of 40-1000 Hz and 80-800 A/m, respectively. The temperature dependence of ac susceptibility shows a characteristic maxima corresponding to the blocking temperature near room temperature. The frequency dependence of the blocking temperature is well described by the Vogel-Fulcher law. By fitting the experimental data with this law, the relaxation time τ0=1.7×10−12 s, characteristic temperature T0=262±3 K, anisotropy energy Ea/k=684±15 K and effective magnetic anisotropy constant keff=2.25×104 erg/cm3 have been obtained. dc Magnetization measurement versus magnetic field shows that some of LSMO nanoparticles are blocked at 293 K. The role of magnetic interparticle interactions on the magnetic behavior is also investigated. 相似文献
386.
Nasim Baimani Parviz Aberoomand Azar Syed Waqif Husain Homayon Ahmad Panahi Ali Mehramizi 《Journal of separation science》2019,42(7):1468-1476
We developed an approach for the use of polyester dendrimer during the imprinting process to raise the number of recognized sites in the polymer matrix and improve its identification ability. Photoresponsive molecularly imprinted polymers were synthesized on modified magnetic nanoparticles involving polyester dendrimer which uses the reactivity between allyl glycidyl ether and acrylic acid for the high‐yielding assembly by surface polymerization. The photoresponsive molecularly imprinted polymers were constructed using methylprednisoloneacetate as the template, water‐soluble azobenzene involving 5‐[(4, 3‐(methacryloyloxy) phenyl) diazenyl] dihydroxy aniline as the novel functional monomer, and ethylene glycol dimethacrylate as the cross‐linker. Through the evaluation of a series of features of spectroscopic and nano‐structural, this sorbent showed excellent selective adsorption, recognition for the template, and provided a highly selective and sensitive strategy for determining the methylprednisoloneacetate in real and pharmaceutical samples. In addition, this sorbent according to good photo‐responsive features and specific affinity to methylprednisoloneacetate with high recognition ability, represented higher binding capacity, a more extensive specific area, and faster mass transfer rate than its corresponding surface molecularly imprinted polymer. 相似文献
387.
A planar laser-induced fluorescence (PLIF) technique for visualizing gas–liquid mass transfer and wake structure of rising
gas bubbles is described. The method uses an aqueous solution of the pH-sensitive dye Naphthofluorescein and CO2 as a tracer gas. It features a high spatial resolution and frame rates of up to 500 Hz, providing the ability to capture
cinematographic image sequences. By steering the laser beam with a set of two programmable scanning mirrors, sequences of
three-dimensional LIF images can be recorded. The technique is applied to freely rising bubbles with diameters between 0.5
and 5 mm, which perform rectilinear, oscillatory or irregular motions. The resulting PLIF image sequences reveal the evolution
of characteristic patterns in the near and far wake of the bubbles and prove the potential of the technique to provide new
and detailed insights into the spatio-temporal dynamics of mass transfer of rising gas bubbles. The image sequences further
allow the estimation of bubble size and rise velocity. The analysis of bubble rise velocities in the Naphthofluorescein solution
indicates that surfactant-contaminated conditions are encountered. 相似文献
388.
The ‘optical spring’ results from dynamical back-action and can be used to improve the sensitivity of cavity-enhanced gravitational-wave detectors. The effect occurs if an oscillation of the cavity length results in an oscillation of the intra-cavity light power having such a phase relation that the light's radiation pressure force amplifies the oscillation of the cavity length. Here, we analyse a Michelson interferometer whose optical-spring cavity includes an additional optical-parametric amplifier with adjustable phase. We find that the phase of the parametric pump field is a versatile parameter for shaping the interferometer's spectral density. 相似文献
389.
Tianshu Liu Jacob Nink Parviz Merati Tian Tian Yong Li Tom Shieh 《Experiments in fluids》2010,48(6):1037-1057
The fluid mechanics of the deposition of micron liquid (olive oil) droplets on a glass wall in an impinging turbulent air
jet is studied experimentally. The spatial patterns of droplets deposited on a wall are measured by using luminescent oil
visualization technique, and the statistical data of deposited droplets are obtained through microscopic imagery. Two distinct
rings of droplets deposited on a wall are found, and the mechanisms of the formation of the inner and outer rings are investigated
based on global diagnostics of velocity and skin friction fields. In particular, the intriguing effects of turbulence, including
large-scale coherent vortices and small-scale random turbulence, on micron droplet deposition on a wall and coalescence in
the air are explored. 相似文献