排序方式: 共有65条查询结果,搜索用时 15 毫秒
51.
Vali Parvaneh Mahmoud Shariati Amir Masood Majd Sabeti 《European Journal of Mechanics - A/Solids》2009,28(6):1072-1078
In this paper, the influence of various vacancy defects on the critical buckling loads and strains in carbon nanotubes under axial compression is investigated via a new structural model in ABAQUS software. The necessity of desirable conditions and expensive tests for experimental methods, in addition to the time expenditure required for atomic simulations, are the motivation for this work, which, in addition to yielding accurate results, avoids the obstacles of the previous methods. In fact, this model is a combination of other structural models designed to eliminate the deficiencies inherent in individual approaches. Because the present model is constructed in the CAE space of ABAQUS, there is no need to program for different loading and boundary conditions. A nonlinear connector is considered for modeling of stretching and torsional interactions, and a nonlinear spring is used for modeling of the angle variation interactions. A Morse potential is employed for stretching and bending potentials, and a periodic type of bond torsion is used for torsion interactions. The effect of different types of vacancy defects at various locations on the critical buckling loads and strains is studied for zigzag and armchair nanotubes with various aspect ratios (Length/Diameter). Comparison of our results with those of buckling of shells with cutouts indicates that vacancy defects in the carbon nanotubes can most likely be modeled as cutouts of the shells. Finally, results of the present structural model are compared with those from molecular dynamics (MD) simulation and show good agreement between our model and the MD model. 相似文献
52.
Kazem Karami Ali Reza Allafchian Razieh Amiri Fatemeh Shirani Parvaneh Bayat Behzad Rezaei 《应用有机金属化学》2019,33(6)
The Glucose amount of human blood is very vital because in higher levels than allowed value the corporal biological system was hampered. Therefore, in this study, the Cu2O was deposited on the reduced Graphene oxide (RGO) by polydopamin (PDA) as linker. The new RGO‐PDA‐Cu2O nanocomposite was deposited on the glassy carbon electrode (GCE) surface after its characterization by UV–Visible, fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), Energy‐dispersive X‐ray (EDX), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) techniques. The electroanalysis of the new electrode was investigated by the cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) methods. The obtained detection limit of glucose (Glu) showed that the deposited GCE by RGO‐PDA‐Cu2O nanocomposite has a high potential for its diagnosis. In addition, this electrode was applied to the Glu detection as biosensor in real samples in order to utilize in commercial applications. 相似文献
53.
The effect of electric field and Al doping on the sensitivity of hexa‐peri‐hexabenzocoronene nanographene to chloropicrin 下载免费PDF全文
Akram Hosseinian Arezoo Gharachorloo Tarlan Mohazzab Lighvani Parvaneh Delir Kheirollahi Nezhad Esmail Vessally 《应用有机金属化学》2018,32(10)
It has been previously reported that the recently synthesized hexa‐peri‐hexabenzocoronene (HBC) nanographene cannot detect toxic chloropicrin (CP) gas. To overcome this problem, we examined the effect of Al doping and applying an electric field on the sensitivity of HBC towards CP gas by means of density functional theory calculations. We found that the Al‐doping process significantly increases the adsorption energy of CP gas from ?7.1 to ?39.9 kcal mol?1 but decreases the sensitivity of HBC. By applying an electric field, the HBC is polarized with two different electrostatic potentials on its different surfaces, which increases the adsorption energy. By increasing the electric field strength, the adsorption energy and electronic sensitivity of HBC are increased. We predicted that in the presence of an electric field of about ?0.025 au, HBC can act as an electronic senor or a work function‐type sensor with a short recovery time. At this field, the electrical conductivity of HBC is significantly increased on CP adsorption which generates an electrical signal. Increasing the electric field to higher intensities is not favourable because of increasing recovery times, and decreasing it to lower intensities reduces the sensitivity of HBC. 相似文献
54.
A rapid, environmental friendly and low-cost method to prepare hydroxyapatite nanoparticles is proposed. In this method, hydroxyapatite is produced in a sonicated pseudo-body solution. The sonication time was found effective in the formation of the crystalline phase of nanoparticles. In our experimental condition, 15 min sonication resulted in the most pure hydroxyapatite phase. Also it was shown that growth temperature is a crucial factor and hydroxyapatite crystallizes only at 37 °C. The particles formed by sonication were generally smaller and more spherical than those obtained without sonication. Sonication increased the hydroxyapatite crystal growth rate up to 5.5 times compared to non-sonication condition. The comparison between the specific surface area of hydroxyapatite nanoparticles obtained by sonication and without sonication demonstrated that sonication increased the specific surface area from 63 m2/g to 107 m2/g and decreased the size of nanoparticles from 30 nm to 18 nm. Analysis on the pore structure demonstrated that the fractal structures obtained with and without sonication were considerably different. 相似文献
55.
Jamshid Sabbaghzadeh Parvaneh Jafarkhani Siamak Dadras Mohammad Javad Torkamany 《Applied Physics A: Materials Science & Processing》2009,94(2):293-297
Synthesis of multi-wall carbon nanotubes in a 1473 K furnace using a copper vapor laser (CVL) is reported. The operating parameters
of this laser, i.e. a high fluence at the focal point and an extremely high frequency of 10 kHz, distinguished it from common
laser sources in the synthesis of CNTs. Therefore, the unexpected experimental findings, the formation of MWNTs instead of
the generally reported SWNTs, would be verified by these two notable parameters. Electron microscopy beside Raman spectroscopy
illustrates the presence of multi-wall carbon nanotubes in the resulting product. 相似文献
56.
Allahvirdinesbat Maryam Fozi Mohaddeseh Safa Kazem D. Alyari Maryam Nakhostin Panahi Parvaneh Niaei Aligholi 《Research on Chemical Intermediates》2017,43(4):2653-2668
Research on Chemical Intermediates - An improved one-pot and ecofriendly approach to tri- and tetraaryl imidazoles through three- and four-component coupling reactions under neutral and... 相似文献
57.
Karim Asadpour‐Zeynali Mir Reza Majidi Parvaneh Najafi‐Marandi Zinalabedin Norysaray 《中国化学会会志》2013,60(10):1253-1259
We report a new and simple approach based on an experimental design method for the preparation of pencil‐lead electrode modified with bismuth thin film. The fabrication process consists of reduction of bismuth on the surface of electrode with potentiostate method. Response surface methodology was developed as experimental strategies for modeling and optimization of the influence of some variables on the performance of modified electrode. The electrocatalytic behavior of this modified electrode was exploited as a sensitive detection system for the mercury‐free reduction and determination of metronidazole in pharmaceutical and biological samples by using differential pulse voltammetry and amperometry methods. 相似文献
58.
Ezzat Rafiee Mohammad Joshaghani Parvaneh Ghaderi-Shekhi Abadi 《Research on Chemical Intermediates》2018,44(4):2503-2522
Transition metal compounds have emerged as suitable catalysts for organic reactions. Magnetic compounds as soft Lewis acids can be used as catalysts for organic reactions. In this report, the Fe3O4 nanostructures were obtained from Fe2+ and Fe3+-salts, under an external magnetic field (EMF) without any protective agent. The X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy tools were used to characterize these magnetic compounds. The two-dimensional (2-D, it showed nanometric size in the two dimensions, nanorod structure) Fe3O4 compound showed high catalytic activity and stability in N- and C-alkylation reactions. A diverse range of N- and C-alkylation products were obtained in moderate to high yield under green and mild conditions in air. Also the N- and C-alkylation products can be obtained with different selectivity and yield by exposure reactions with EMF. Results of alkylation reactions showed that the presence of Fe(II) and Fe(III) species on the surface of magnetic catalysts (phase structure of magnetic compounds) are essential as very cheap active sites. Also, morphology of magnetic catalysts had influence on their catalytic performances. After the reaction, the catalyst/product(s) separation could be easily achieved with an external magnet and more than 95% of catalyst could be recovered. The catalyst was reused at least four times without any loss of its high catalytic activity for N- and C-alkylation reactions. 相似文献
59.
Parvaneh Shafieyoon Hosein Tavakol 《Phosphorus, sulfur, and silicon and the related elements》2018,193(5):324-328
The [N-(2-pyridyl)] para-styrene sulfonamide (PSS) was prepared as a monomer, from the reaction of para-styrene sulfonyl chloride and 2-amino pyridine in the presence of potassium hydroxide solution 0.5 M as a base, and CH3Cl. Polystyrene [N-(2-pyridyl) sulfonamide] (PPSS) was synthesized from the polymerization of [N-(2-pyridyl)] para-styrene sulfonamide (PSS). The Polystyrene bis [N-(2-pyridyl) sulfonamide] palladium (II) as a polymer- supporting palladium complex was also prepared from the reaction of PdCl2 (CH3CN)2 with PPSS in the presence of KOH 0.5 M. Polystyrene bis [N-(2-pyridyl) sulfonamide] palladium (II) is produced as a novel heterogeneous catalyst for coupling reactions for C-C bond formation. This method includes higher yield and has an easier work-up procedure. The structures of the monomer, polymer and its Pd complex were confirmed by using FT-IR and 1H-NMR spectroscopy. Elemental analysis of Pd by inductively coupled plasma (ICP) technique and hot filtration test showed loading of the metal into solution from the catalyst The heterogeneous catalyst was recycled without any loss in its properties. 相似文献
60.
Parvaneh Nakhostin Panahi Gérard Delahay 《Russian Journal of Applied Chemistry》2017,90(10):1627-1633
In this work three different supports (γ-Al2O3, ZSM-5, and SAPO-34) of varying degree of acid sites and textural properties were used to evaluate the influence of support specifics in the Cu/supported nanocatalysts on NO conversion. The nanocatalysts were prepared by homogeneous deposition precipitation (HDP) method and characterized by N2 pore size distribution, TEM, H2-TPR for investigation the reducibility of the copper species and acidity measurement by NH3 adsorption. The Cu/ZSM-5 and Cu/SAPO-34 catalysts were more active for NO conversion than Cu/γ-Al2O3 catalyst. The characterization and conversion differences in the copper supported on different types of support indicated that these differences arise from the differences in surface area, pore size distribution, and acidity of the supports. The higher SCR-DeNO activity of Cu/ZSM-5 and Cu/SAPO-34 nano-catalysts can be explained by higher surface area and acidity of ZSM-5 and SAPO-34 supports. These catalysts also have larger amount of reducible Cu species compared to Cu/γ-Al2O3 which correlates with the structure of the support used. Considering these findings, the NO conversion ability of Cu/supported catalysts has been correlated with support structure and acidity. 相似文献