S A Ketabi
Articles written in Pramana – Journal of Physics
Volume 69 Issue 4 October 2007 pp 661-668 Research Articles
Using a tight-binding model and a transfer-matrix technique, we numerically investigate the effects of the coupling strength and the role of solitons on the electronic transmission through a system in which trans-polyacetylene (
Volume 72 Issue 6 June 2009 pp 1023-1036 Research Articles
In this paper, based on the tight-binding Hamiltonian model and within the framework of a generalized Green's function technique, the electronic conduction through the poly(GACT)–poly(CTGA) DNA molecule in SWNT/DNA/SWNT structure has been numerically investigated. In a ladder model, we consider DNA as a planar molecule containing 𝑀 cells and four further sites (two base pair sites and two backbone sites) in each cell, sandwiched between two semi-infinite single-walled carbon nanotubes (SWNT) as the electrodes. Having relied on Landauer formalism, we focussed on studying the current–voltage characteristics of DNA, the effect of the coupling strength of SWNT/DNA interface and the role of tube radius of nanotube contacts on the electronic transmission through the foregoing structure. Finally, a characteristic time was calculated for the electron transmission, which measures the delay caused by the tunnelling through the SWNT/DNA interface. The results clearly show that the calculated characteristic time and also the conductance of the system are sensitive to the coupling strength between DNA molecule and nanotube contacts.
Volume 74 Issue 1 January 2010 pp 143-152 Research Articles
A numerical study is presented to investigate the role of solitons in the electronic states of double-stranded DNA (dsDNA) molecule in the metal/DNA/metal system. Based on tight-binding Hamiltonian model and within the framework of a generalized Green’s function technique, we consider a ladder model for poly(dG)-poly(dC) DNA molecule containing M cells with four sites (two base pair sites and two backbone sites) in each cell. In the presence of a sublattice of solitons, our results show that the homogeneous soliton distributions induce the electronic states in the band gap of DNA molecule. In addition, the room temperature current–voltage characteristic of the system shows a linear and ohmic-like behaviour.
Volume 77 Issue 4 October 2011 pp 679-688 Research Articles
In this work, some structural and optical properties of the zinc oxide (ZnO) nanoparticles were studied. The highly crystalline ZnO nanoparticles were produced by the hydrothermal and sol–gel methods. The analyses of the XRD patterns, STEM images and UV spectroscopy showed that the size of the nanoparticles prepared by oxalic acid was smaller than the ones by urea. The properties of oxalic acid and urea were also investigated to determine the most effective crystallization process of ZnO nanoparticles. It has been shown that pH, decomposition temperature and activity coefﬁcient of the complexing agent have certain effects on crystallization process.
Volume 93 | Issue 5
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