International Journal of Modern Physics B

Nanowires grown by electrodeposition using nanoporous template have attracted much attention due to the simplicity of this technique for preparing nano-scaled materials. We present here a standard way to fabricate lead or tin nanowire arrays. We also present some of their superconducting properties directly affected by the reduced dimensions; these are the magnetic flux penetration and confinement in nanowires having a diameter only a few times the magnetic penetration length, as well as the formation of phase-slips centres in nanowires having a diameter smaller than the coherence length.

Internal haemorrhage, often leading to cardio-vascular arrest happens to be one of the prime sources of high fatality rates in mammals. We propose a simplistic model of fluid flow in our attempt to specify the location of the haemorrhagic spot, which, if located accurately, could possibly be operated leading to an instant cure. The model we employ for the purpose is basically fluid mechanical in origin and consists of a viscous fluid, pumped by a periodic force and flowing through an elastic tube. The analogy is with that of blood, pumped from the heart and flowing through an artery or vein. Our results, aided by graphical illustrations, match reasonably well with experimental observations.

Intelligent states in the sense of field intensity dependent squeezing for a closed and symmetric algebra which interpolates between the Heisenberg Weyl algebra W₃ and su(1,1) algebra are constructed. The explicit expressions of these states in terms of Laguerre polynomials are derived and their quantum statistical properties are investigated.

In this work we apply Thompson's scaling approach (of dimensions) to study the scalar field theories Φⁿ. This method can be considered as a simple and alternative way to the renormalization group (RG) approach and when applied to the Φⁿ Lagrangian is able to obtain the coupling constant behavior g(μ), namely the dependence of g on the energy scale μ. The calculations are evaluated just at , where the dimension d_c is similar to a kind of upper critical dimension of the problem, or in other words the dimension where the Φⁿ theory becomes renormalizable, so that we obtain logarithmic behavior of the coupling g at d_c. Due to the universal logharithmic behavior of the coupling g at d_c for any value of n in the Φⁿ theory, we are able to estimate a certain β_n function given in a closed form, which is a novelty obtained by the present method.

It is demonstrated that the apex of a circular biconcave vesicle of fluid membrane can shift toward to (or away from) the center depending on the increase (or decrease) of the osmotic pressure.

The mechanical properties of single-walled nanotubes (SWNTs) filled with small fullerenes (C20, C36 and C60) were investigated using molecular dynamics (MD) simulation. The interaction between carbon atoms was described by a combination of the many-body Brenner potential with a two-body pair potential. We found that below the critical value of the strain, the stress of SWNT increases linearly with the strain and the Young's modulus of certain SWNT with different filling densities is almost the same for small strain. It was also observed that the buckling force, which corresponds to the critical strain, becomes higher as the filling density of SWNT is increased in general. However, in the case of SWNT of larger radius filled with smaller fullerenes, the dependence of the buckling force on the filling density is expected to be different, which was attributive to the long-distance attractive interaction between atoms of fullerene and those of SWNT.

The effect of partial substitution of Ca by x = 0.02 La on the electrical and magnetically properties of two (Bi,Pb):2223 superconductor ceramic S1 and S2 (with different Pb and Sr atomic concentration) were investigated by using electrical resistance and AC magnetic susceptibility measurements. The parameters from linear resistivity data in the normal state and superconducting transition are sensitive to the compounds stoechiomerty. The intergrain critical current density J_cJ(T) dependence near T_c obtained from immaginary AC susceptibility data agrees with the assumption of SNS intergrain junctions.

Since the Wigner function (WF) is related to a Lindard-constant type linear dielectric function derived in the symmetric gauge,⁷ it is expected to show de Haas-van Alphen (dHvA) oscillations. Starting with the symmetric eigenfunctions, we derived the pure-state WF in a magnetic field, whose plots in phase space and in term of B^-1 for increasing n are consistent with the dHvA effect. Furthermore the asymptotic expansion of WF at large n show periodic oscillations with a period related to the Fermi energy. The phase space plots of WF also show that dHvA and similar oscillations could be a consequence of Nature's strategy for increasing the effective spatial range without violating the uncertainty principle. Properties of the symmetric eigenfunctions were derived. The dynamics of WF can be obtained from the solution of the time-dependent Schrödinger equation (SE). A new method to solve the SE in a magnetic field in the interaction picture based on expansion in term of symmetric eigenfunctions has been developed. The matrix element for a Gaussian potential were derived explicitly, plotted against B^-1, and showed oscillations. The total WF was shown to be a linear combination of the diagonal pure-state WF's by using the orthogonality for symmetric eigenfunctions. The no-special-point property for WF was confirmed, which is important for the construction of a numerical algorithm to solve the SE in a magnetic field.

The pre-existing literature on phenomena at the mesoscopic scale concern among other things phase coherent transport. Phase coherent transport dominates at very low temperatures. With increasing in temperature, as the system size becomes comparable to the inelastic mean free path phase incoherence sets in. This incoherence further leads to dephasing, and as a consequence purely quantum effects in electron transport give way to classical macroscopic behavior. In this work we consider two distinct phenomenological models of incoherent transport, the Coherent Absorption and Wave Attenuation models. We reveal some physical problems in the Coherent Absorption model as opposed to the Wave Attenuation model. We also compare our proposed model with experiments in case of the much studied peak to valley ratios in resonant tunneling diodes, magneto-conductance oscillations and Fano resonances in case of Aharonov–Bohm rings.

To gain insight into the electronic properties of PrFe₄P₁₂ filled skutterudite, band electronic structure calculations, total and projected density of states, crystal orbital overlap population and Mulliken population analysis were performed. The energy bands yield a semi-metallic behavior with a direct gap (at Γ) of 0.02 eV. Total and Projected Density of States provided information of the contribution from each orbital of each atom to the total Density of States. Moreover, the bonding strength between some atoms within the unit cell was obtained. Mulliken Population Analysis suggests ionic behavior for this filled skutterudite.