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141.
Md. Mahmudul Hasan Md. Elius Hossain M.A. Mamun M.Q. Ehsan 《Journal of Saudi Chemical Society》2012,16(2):145-151
The redox behavior of Cd(II) and the interaction of Cd(II) with cyclic amino acid, proline, have been studied in 0.1 M KCl, 0.1 M NaClO4 and acetate buffer of different pH. The CVs were recorded at glassy carbon electrode within the potential window 200 and ?1500 mV. The reference and counter electrode used were Ag/AgCl and Pt wire, respectively. The cyclic voltammograms show one pair of cathodic and anodic peaks for the Cd(II)/Cd(0) system indicating the involvement of two electron transfer processes. The peak potential shift and charge transfer rate constant (kf) values strongly support the interaction between metal and ligand. The higher value of peak current ratio and peak potential separation (ΔE) indicate that the systems are quasireversible. The effect of supporting electrolyte and concentration of electro active species on the interaction were also studied. 相似文献
142.
We have developed a new method for the preparation of unsymmetrical imides using liquid carboxylate salts via a Ritter-type process. The reactions were carried out with nitriles and n-butylammonium carboxylates as ionic liquids in the presence of triflic anhydride (Tf2O) as the promoter. Mild reaction conditions, simplicity of the procedure, and proton-free conditions are the main advantages of this procedure. 相似文献
143.
Ehsan Ghazanfari Sibel Pamukcu Mesut Pervizpour Zuleima Karpyn 《Transport in Porous Media》2014,105(1):235-253
Evaluation of relative permeability coefficients is one of the key steps in reliable simulation of two-phase flow in porous media. An extensive body of work exists on evaluation of these coefficients for two-phase flow under pressure gradient. Oil transport under an applied electrical gradient in porous media is also governed by the principles of two-phase flow, but is less understood. In this paper, relative permeability coefficients under applied electric field are evaluated for a specific case of two- phase fluid flow in water-wet porous media, where the second fluid phase is oil. It is postulated that the viscous drag on the oil phase, exerted by the electro-osmotic flow of the water phase, is responsible for the transport of oil in the absence of a pressure gradient. Reliable prediction of the flow patterns necessitates accurate representation and determination of the relative permeability coefficients under the electrical gradient. The contribution of each phase to the flow is represented mathematically, and the relative permeability coefficients are evaluated through electro-osmotic flow measurements conducted on oil bearing rock cores. 相似文献
144.
Ehsan Momtahan 《代数通讯》2013,41(11):4167-4171
A well-known result by Y. Utumi states: Every right or left self-injective ring is von Neumann regular modulo its Jacobson radical. In this note, we give an example of a commutative ?0-self-injective ring which is not von Neumann regular modulo its Jacobson radical. 相似文献
145.
Laurent Beaudou Adrian Bondy Xiaomin Chen Ehsan Chiniforooshan Maria Chudnovsky Vašek Chvátal Nicolas Fraiman Yori Zwols 《Combinatorica》2013,33(6):633-654
One of the De Bruijn-Erd?s theorems deals with finite hypergraphs where every two vertices belong to precisely one hyperedge. It asserts that, except in the perverse case where a single hyperedge equals the whole vertex set, the number of hyperedges is at least the number of vertices and the two numbers are equal if and only if the hypergraph belongs to one of simply described families, near-pencils and finite projective planes. Chen and Chvátal proposed to define the line uv in a 3-uniform hypergraph as the set of vertices that consists of u, v, and all w such that {u;v;w} is a hyperedge. With this definition, the De Bruijn-Erd?s theorem is easily seen to be equivalent to the following statement: If no four vertices in a 3-uniform hypergraph carry two or three hyperedges, then, except in the perverse case where one of the lines equals the whole vertex set, the number of lines is at least the number of vertices and the two numbers are equal if and only if the hypergraph belongs to one of two simply described families. Our main result generalizes this statement by allowing any four vertices to carry three hyperedges (but keeping two forbidden): the conclusion remains the same except that a third simply described family, complements of Steiner triple systems, appears in the extremal case. 相似文献
146.
E Kabiri Rahni T Hajzargarbashi T Kundu 《The Journal of the Acoustical Society of America》2012,132(2):718-727
The ultrasonic field generated by a point focused acoustic lens placed in a fluid medium adjacent to a solid half-space, containing one or more spherical cavities, is modeled. The semi-analytical distributed point source method (DPSM) is followed for the modeling. This technique properly takes into account the interaction effect between the cavities placed in the focused ultrasonic field, fluid-solid interface and the lens surface. The approximate analytical solution that is available in the literature for the single cavity geometry is very restrictive and cannot handle multiple cavity problems. Finite element solutions for such problems are also prohibitively time consuming at high frequencies. Solution of this problem is necessary to predict when two cavities placed in close proximity inside a solid can be distinguished by an acoustic lens placed outside the solid medium and when such distinction is not possible. 相似文献
147.
Ehsan Mohammadpour Mokhtar Awang 《Applied Physics A: Materials Science & Processing》2012,106(3):581-588
An effective finite-element (FE) approach for modeling the structure and the deformation of single-walled carbon nanotubes
(SWCNTs) and multi-walled carbon nanotubes (MWCNTs) is presented. An individual tube was modeled using a frame-like structure
with beam elements. The effect of van der Waals forces, crucial in MWCNTs, was modeled by spring elements. The success of
this new carbon nanotube (CNT) modeling approach was verified by comparing the simulation results for single- and multi-walled
nanotubes and graphene with other experimental and computational results available in the literature. Simulations of final
deformed configurations were in excellent agreement with the atomistic models for various deformations. The proposed approach
successfully predicts the experimentally observed values for mechanical behavior of SWCNTs and MWCNTs. The results demonstrated
that the proposed FE technique could provide a valuable tool for studying the mechanical behavior of different types of nanotubes,
as well as their effectiveness as load-bearing entities in nanocomposite materials. 相似文献
148.
The working tube is a main part of vortex tube which the compressed fluid is injected into this part tangentially. An appropriate design of working tube geometry leads to better efficiency and performance of vortex tube. In the experimental investigation, the parameters are focused on the working tube angle, inlet pressure and number of nozzles. The effect of the working tube angle is investigated in the range of θ = 0–120°. The experimental tests show that we have an optimum model between θ = 0 and θ = 20°. The most objective of this investigation is the demonstration of the successful use of CFD in order to develop a design tool that can be utilized with confidence over a range of operating conditions and geometries, thereby providing a powerful tool that can be used to optimize vortex tube design as well as assess its utility in the field of new applications and industries. A computational fluid dynamics model was employed to predict the performances of the air flow inside the vortex tube. The numerical investigation was done by full 3D steady state CFD-simulation using FLUENT6.3.26. This model utilizes the Reynolds stress model to solve the flow equations. Experiments were also conducted to validate results obtained for the numerical simulation. First purpose of numerical study in this case was validation with experimental data to confirm these results and the second was the optimization of experimental model to achieve the highest efficiency. 相似文献
149.
Niloofar Naeemabadi Javad Seyfi Ehsan Hejazi Iman Hejazi Hossein Ali Khonakdar 《先进技术聚合物》2019,30(4):1027-1035
The main aim was to study the roles of structural homogeneity and superhydrophobicity on the adhesion of SW colon cancer cells on the surface of polyvinyl chloride (PVC) nanocomposites. Concurrent use of a proper nonsolvent (ethanol) and silica nanoparticles resulted in superhydrophobic behavior and also different surface structures. The effect of added‐ethanol content on the surface properties of PVC nanocomposites was also studied. The synergetic combination of silica and ethanol has led to the formation of a porous surface layer resulting in a considerable boost in the hydrophobic behavior. The scanning electron microscopy, roughness, and X‐ray photoelectron spectroscopy (XPS) analysis results were all in total agreement indicating the substantial change in surface morphology, topography, and composition once the ethanol content was increased to 50 vol.%. The surface structure was notably changed by the addition of polyhedral oligomeric silsesquioxanes (POSS) nanoparticles. It was found that the induced inhomogeneity as a result of POSS addition had an adverse effect on the surface properties. In conclusion, superhydrophobicity could be regarded as a prerequisite for achieving cell‐repellent behavior, but it cannot guarantee a cell repellent surface especially if the surface layer possesses structural inhomogeneity. 相似文献
150.
Setareh Habibzadeh Ghasem Firouzzadeh Pasha Mahmood Tajbakhsh Nasim Amiri Andi Ehsan Alaee 《中国化学会会志》2019,66(8):934-944
A new solid acid catalyst, consisting of 12‐phosphotungstic heteropoly acid (HPW) supported on graphene oxide/silica nanocomposite (GO@SiO2), has been developed via immobilizing HPW onto an amine‐functionalized GO/SiO2 surface through coordination interaction (GO@SiO2‐HPW). The GO@SiO2‐HPW nanocomposite was characterized by Fourier transform infrared (FT‐IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and powder X‐ray diffraction (XRD). The prepared nanocomposite could be dispersed homogeneously in water and further used as a heterogeneous, reusable, and efficient catalyst for the synthesis of benzimidazoles and benzothiazoles by the reaction of 1,2‐phenelynediamine or 2‐aminothiophenol with different aldehydes. 相似文献