International Journal of Modern Physics B

Reasons have been found for thinking that the minimum diameter of channels of a given length to support superconductivity through films of oxidized atactic polypropylene (OAPP) at room temperature is considerably larger than that found in a model for Bose condensation in an array of nanofilaments [D. M. Eagles, Philos. Mag.85, 1931 (2005)] used previously. This model was introduced to interpret experimental results dating from 1988 on OAPP. The channels are thought to be of larger diameter than believed before because, for an N–S–N system where the superconductor consists of an array of single-walled carbon nanotubes, the resistance, for good contacts, is R_Q/2N, where N is the number of nanotubes and R_Q = 12.9 kΩ [see e.g., M. Ferrier et al., Solid State Commun.131, 615 (2004)]. We assume this would be 2R_Q/N for a triplet superconductor with all spins in the same direction and no orbital degeneracy, which may be the case for nanofilaments in OAPP. Hence one may infer a minimum number of filaments for a given resistance. In the present model, the E(K) curve for the bosons is taken to be of a Bogoliubov form, but with a less steep initial linear term in the dispersion at T_c than the one at low T. This form is different from the simple linear plus quadratic dispersion, with a steeper initial slope, used in my 2005 paper. A combination of theory and experimental data has been used to find approximate constraints on parameters appearing in the theory.

We have investigated the effects of in-plane and interplane nearest neighbor overlap integrals (s₀ and ) and the site energy difference (Δ) between atoms in two different sublattices in the same graphene layer on the electronic dispersion of bilayer graphene within tight binding model. We then extended the calculation to include the in-plane next nearest neighbor interactions (γ₁, s₁) and next to next nearest neighbor interactions (γ₂, s₂) for bilayer graphene bands. It is observed that introduces further asymmetry in energy values of top conduction band and bottom valence band at the K point in addition to the asymmetry due to Δ. In general there is noticeable electron–hole asymmetry in the slope of the bands away from the K point, and also the changes in band widths due to as well as the other in-plane coupling parameters. The density of states of bilayer graphene has also been calculated within the same model.

A growth model for co-deposition of Sn and In on Si(100) at room-temperature was simulated using Kinetic Monte Carlo methods to shed light on the chemical selectivity and lack of dimer ordering seen in [Jure et al., Appl. Surf. Sci.162, 638 (2000)], a Scanning Tunneling Microscopy (STM) study. In this work, the experimental observation that the number of mixed In–Sn dimers is unaffected even when the relative flux rates are adjusted to favor In over Sn (by 100:1) — a manifestation of some sort of chemical selectivity — was investigated. Our simulations reveal that this phenomenon is ultimately related to the fact that the number of Sn-terminated chains is largely unaffected by the relative flux rate. Finally, we found that the attraction between metal dimers (whether of the same or different species) within a Si dimer row has only negligible effect on the apparent lack of dimer ordering seen in the STM study. Instead, dimer ordering is controlled by the detachment barriers in dimer-terminated islands.

We present results of the dynamics of a single polymer, anchored at both ends and subjected to a periodic oscillatory force at a middle segment. Via Brownian dynamics simulations, the influences of the periodicity of the forcing on the shape of the orbit in the position-force plane have been investigated for flexible and semiflexible polymer. The shape of the orbit exhibits in the form of hysteresis cycle or a single curve.

Self-assembled films of organic dye Chicago Sky Blue 6B (CSB) have been fabricated onto solid substrate by electrostatic alternate adsorption of polycation ploy(allylamine hydrochloride) (PAH) and CSB. UV–Vis absorption spectroscopic studies reveal the successful incorporation of CSB molecules into Layer-by-Layer (LbL) films and consequent formation of aggregates. This view is supported by FTIR spectroscopic studies. Scanning electron microscope picture confirms the formation of nanocrystalline aggregates in the LbL films. About 15 min is required to complete the electrostatic interaction between PAH and CSB molecules in one bilayer LbL film.

We study the magnetic field dependences of the conductivity in heavily doped, strongly disordered 2D quantum well structures within wide conductivity and temperature ranges. We show that the exact analytical expression derived in our previous paper [S. A. Alavi and S. Rouhani, Phys. Lett. A320, 327 (2004)], is in better agreement with the existing equation, i.e., Hikami et al. expression [ Prog. Theor. Phys.63, 707 (1980)] and Littman and Schmid expression [J. Low Temp. Phys.69, 131 (1987)], with the experimental data even in low magnetic field for which the diffusion approximation is valid. On the other hand from theoretical point of view we observe that our equation is also rich because it establishes a strong relationship between quantum corrections to the conductivity and the quantum symmetry Su_q(2). It is shown that the quantum corrections to the conductivity is the trace of Green function made by a generator of Su_q(2) algebra. Using this fact we show that the quantum corrections to the conductivity can be expressed as a sum of an infinite number of Feynman diagrams.

A method for constructing the solutions of nonlinear evolution equations by using the Weierstrass elliptic function and its first-order derivative was presented. This technique was then applied to Burgers and Klein–Gordon equations which showed its efficiency and validality for exactly some solving nonlinear evolution equations.

Plasma-polymerized 1-benzyl-2-methylimidazole (PPBMI) thin films have been deposited onto glass substrates by glow discharge technique. Scanning electron micrographs reveal that the surface morphology of PPBMI thin films is uniform and flawless. Fourier transform infrared spectroscopy analysis shows that the chemical composition of PPBMI films is different from that of the BMI. From the ultraviolet-visible spectra direct and indirect transition energy gaps were determined to be between 3.10 and 3.35 eV and 1.80 and 1.95 eV, respectively, for as-deposited PPBMI thin films of different thicknesses. Both direct and indirect transition energy gaps increase with increasing thickness and decrease upon heat treatment.

This paper investigates antisynchronization of identical and nonidentical Φ⁶ Van der Pol oscillators (VDPOs) and Φ⁶ Duffing oscillators (DOs) with both parametric and external excitations based on adaptive backstepping technique. The technique is applied to achieve complete antisynchronization between identical Φ⁶ (VDPOs), identical Φ⁶ (DOs), and nonidentical Φ⁶ oscillators comprising the Φ⁶ (VDPO) and Φ⁶ (DO). Numerical simulations are implemented to verify the feasibility and effectiveness of the antisynchronization technique.

The editorial board discovered that the data points in several sections of the Mossbauer spectra as given in Figs. 3(a) and 3(b) are exactly identical. This is impossible and nonphysical for the measurement of two different samples (or for that matter not even for the same sample!). The only conclusion we can draw from this figure is that some of the data is fabricated. As a result, the results and conclusions as described in the paper are unacceptable. This article is retracted from its publication in Int. J. Mod. Phys. B.