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RISS 인기검색어
- 검색키워드
- 저자 : Ali Meghdari (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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Hossein Nejat Pishkenari,Ali Meghdari 한국물리학회 2010 Current Applied Physics Vol.10 No.2
This paper is devoted to the characterization of the surface defects using a recently developed AFM technique called frequency and force modulation AFM (FFM–AFM). The simulated system includes a recently developed gold coated AFM probe which interacts with a sample including single-atom vacancy and impurities. In order to examine the behavior of the above system on different transition metals, the molecular dynamics (MD) simulation with Sutton–Chen (SC) inter-atomic potential is used. In this study,an online imaging simulation of the probe and sample is performed, and the effects of the horizontal scan speed, the effective frequency set-point, the cantilever stiffness, the tip-sample rest position and the cantilever quality factor on the resulting images are investigated. Using a proposed optimum controlling scheme for the excitation force amplitude, the cantilever horizontal speed can be increased.
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A close look at the motion of C60 on gold
Hossein Nejat Pishkenari,Alireza Nemati,Ali Meghdari,Saeed Sohrabpour 한국물리학회 2015 Current Applied Physics Vol.15 No.11
In this paper, we have studied the motion of buckminsterfullerene (C60) on a gold surface by analyzing its potential energy and using classical molecular dynamics method. The results can be employed to investigate the motion of C60-based nanocars which have been made in recent years. For this purpose, we have studied the translational and rotational motions of C60 molecule independently. First, we have calculated the potential energy of a C60 molecule on a gold surface in different orientations and positions and employed this data to predict fullerene motion by examining its potential energy. Then we have simulated the motion of C60 at different temperatures using classical molecular dynamics methods. Specifying the regime of the motion at different temperatures is one of main goals of this paper.We have found that the rotational motion of C60 molecule on the gold substrate, was easier than its sliding (translational) motion. Also, the regime of motion of fullerene depended on temperature. The results demonstrate that three different regimes of motion, dependent on temperature, could be observed: rare jumps to adjacent cells, frequent jumps, and continuous motion. Employing the results of this paper not only helps to understand the C60 motion on the gold surface but also provides an appropriate tool for realizing motion of the thermally-driven fullerene-based nanocars.
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Study of Biomolecules Imaging Using Molecular Dynamics Simulations
Mohsen Kheirodin,Hossein Nejat Pishkenari,Ali Moosavi,Ali Meghdari 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.7
The process of imaging a biomolecule by atomic force microscope (AFM) is modeled using molecular dynamics (MD) simulations. Since the large normal force exerted by the tip on the biosample in contact and tapping modes may damage the sample structure and produce irreversible deformation, the noncontact mode of AFM (NC-AFM) is employed as the operating mode. The biosample is scanned using a carbon nanotube (CNT) as the AFM probe. CNTs because of their small diameter, high aspect ratio and high mechanical resistance attract many attentions for imaging purposes. The tip–sample interaction is simulated by the MD method. The protein, which has been considered as the biomolecule, is ubiquitin and a graphene sheet is used as the substrate. The effects of CNT's geometric parameters such as the CNT height, the diameter, the tilt angle, the flexibility and the number of layers on the image quality have been evaluated.
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Cellular Injection Using Carbon Nanotube: A Molecular Dynamics Study
Seyed Hanif Mahboobi,Alireza Taheri,Hossein Nejat Pishkenari,Ali Meghdari,Mahya Hemmat 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.2
Determination of an injection condition which is minimally invasive to the cell membrane is of great importance in drug and gene delivery. For this purpose, a series of molecular dynamics (MD) simulations are conducted to study the penetration of a carbon nanotube (CNT) into a pure POPC cell membrane under various injection velocities, CNT tilt angles and chirality parameters. The simulations are nonequilibrium and all-atom. The force and stress exerted on the nanotube, deformation of the lipid bilayer, and strain of the CNT atoms are inspected during the simulations. We found that a lower nanotube velocity results in successfully entering the membrane with minimum disruption in the CNT and the lipid bilayer, and CNT's chirality distinctly affects the results. Moreover, it is shown that the tilt angle of the CNT influences the nanotube's buckling and may result in destroying the membrane structure during the injection process.
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