International Journal of Modern Physics B

Unusual DNA elasticity has been observed in a few recent experiments for DNA under tight bending conditions. Here we present new experimental evidence demonstrating unusual DNA bending elasticity by analyzing the atomic force microscope (AFM) images of DNA minicircles of sizes 189 and 378 base-pairs that are relaxed on 2D surface. The DNA shape distributions are found in disagreement with the canonical 50 nm persistence length based worm-like chain (WLC) model. Instead, they are found in agreement with the recently proposed flexible defect excitation model and linear subelastic chain (LSEC) model.

First principles total energy calculations within the density functional formalism have been used to investigate the electronic, mechanical, and optical properties of pseudocubic-Si₃P₄ and Ge₃P₄. Considering the technological importance of the Si/Ge-Group-V elements, we have concentrated mainly on the comparatively less studied, but energetically more favorable pseudocubic-Si₃P₄ and Ge₃P₄ structures of the Si and Ge phosphides. We find that the electronic band structures show that pseudocubic-Si₃P₄ and Ge₃P₄ are both indirect band semiconductors with very low density functional band gaps of 0.24 eV and 0.13 eV, respectively. We also calculate mechanical properties of the materials, such as the bulk modulus, elastic constants, shear modulus, and Vickers hardness of the two phosphides. We find that the bulk and shear modulus of pseudocubic-Si₃P₄ and Ge₃ P₄ are 76.18 GPa and 58.37 GPa, and 59.99 GPa and 46.92 GPa, respectively. Pseudocubic-Si₃P₄ and Ge₃ P₄ have low Vickers hardness, nearly 18.88 and 16.86 GPa, respectively. Moreover, optical parameters, including dielectric function, refractive index, optical absorption, energy loss function, and plasma frequency are also studied.

This article summarizes the uniformity law of spatial physics kinematic systems, and studies the chaos and bifurcation behavior of the uniform system in space. In particular, it also fully explains the relation among the uniform system, the coupled map lattice model which has attracted considerable interest currently, and one-dimensional nonlinear dynamical systems.

Using the equivalent single-particle multi-channel network and the Landauer formula, we theoretically study anti-resonances in conductance of a normal metal–superconductor junction with a side-coupled quantum dot. The transport properties depend on the interplay between the Coulomb blockade effect and the Andreev reflection. It is found that the calculated dependence of the conductance on the gate voltage of dot exhibits two anti-resonant conductance dips. This behavior is caused by the destructive interference of the wave directly transmitted through the normal metal–superconductor junction and the wave reflected from the dot. Moreover, we find that the shape of two anti-resonance profile is symmetric, due to the Andreev reflection, depending on the strength of coupling between the quantum dot and normal metal.

Based on parameter identification, an observer is presented to identify the unknown parameter of hyperchaotic Chen system, then the useful information modulated in the parameter can be recovered successfully. In the improved scheme, an approximate observer is adopted for more security. Numerical simulations show the effectiveness of our method.

In this paper, we reported highly conductive p-type microcrystalline silicon (μc-Si:H) films deposited on amorphous silicon (a-Si:H) surface by very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) technique. Hydrogen plasma treatment of amorphous silicon surface and nucleation layers were introduced prior to μc-Si:H films deposition. The film properties were investigated by using Raman spectra, scanning electron microscope (SEM), optical transmission and reflection, as well as dark conductivity measurements. The influence of plasma treatment and nucleation layer on the growth and properties of the thin p-type μc-Si:H films was studied. It is demonstrated that the hydrogen plasma treatment of a-Si:H films gives rise to the deposition of μc-Si:H on the a-Si:H surface. Also, the growth and properties of the μc-Si:H films are strongly dependent on the nucleation layer. The dark conductivity (σ_d) and crystalline fraction increase with the plasma treatment time and attain high values at about 600 s. A p-type μc-Si:H film with conductivity of 0.0875 Scm^-1 at a thickness of 30 nm was obtained. The film was introduced as window layers for flexible solar cells. An efficiency of about 7.15% was obtained.

In this paper, a synchronous totally asymmetric simple exclusion process (TASEP) with a shortcut under open boundary conditions is investigated. The shortcut is located in the bulk and characterized by shortcut probability q. The phase diagram and density profiles of the model are obtained. It is found that the phase diagram of the model includes three regions, similar to the normal synchronous TASEP. Interestingly, the phase diagram does not change with q. Monte Carlo simulations are used to obtain the bulk density of different phases and they are in good agreement with the approximate stationary state solutions of the model.

We report an ordinary homodyne method for detection of amplitude-squared squeezing in any state by measuring the higher-order moments of the number operator in light obtained by homodyning with intense coherent light.

Both pure Fe₃O₄ magnetic fluids and containing polystyrene sphere composite magnetic fluids have been prepared. The magneto-optical characteristics such as magnetic birefringence and linear dichroism of both magnetic fluids and composite magnetic fluids have been investigated by the magneto-optically modulated double-frequency method. The results reveal that the order structure of nonmagnetic spheres and the interactions between the spheres and the neighbor magnetic chains of Fe₃O₄ particles in the composite magnetic fluids strongly affect the magneto-optical properties. The magneto-optical properties from the study can be used for further development of related new optical devices.

The correlation energies in a singlet and in a triplet state of a two-electron quantum dot in a finite barrier square well potential are computed. Closed analytical expressions are obtained in the perturbation method. Effects of band non-parabolicity and polaronic correction are included. Effects of hydrostatic pressure on the correlation energies are computed. Our results show that (i) the correlation energies in the triplet state are negative, reflecting the exchange interaction, (ii) both the singlet and triplet state correlation energies approach zero as the dot size approaches infinity, (iii) while the band non-parabolicity and the polaronic effects are not significant in the estimation of correlation energies, they however decrease the total confined energies to a maximum of 43% in the triplet state, and (iv) the hydrostatic pressure affects the confined energies appreciably for narrow dots only. The interesting cross-over behavior of the triplet and the singlet state energies at a particular dot radius is explained physically.

We study ground-state pairwise entanglement of spins in mean field clusters of spin-one particles interacting via the Ising interaction in the presence of longitudinal and transverse crystal fields. A general result is found that for all kinds of the spin-one Ising models, the pairwise negativities are symmetric with respect to the zero values of the applied transverse or longitudinal magnetic fields. For models considered in this paper, we show numerically that the crystal fields can serve as an alternative tool to create "on-demand" ground-state entanglement for small clusters of spins.

We study a path integral approach to a system of particles in a PT-symmetric harmonic potential: V(x)=mω²(x²±2iεx)/2. The eigenvalues and eigenstates of the system have been calculated. We find that the total energy of the system is real. The connection between the non-Hermitian and Hermitian Hamiltonians has been discussed and we also establish this connection in the context of path integrals via a considering model.

This paper presents an attempt to use kenaf fibres as reinforcement for tribo-polymeric composite. Kenaf fibres reinforced epoxy (KFRE) composite was fabricated using a closed mould technique associated with vacuum system. Adhesive wear and frictional behaviour of the composite and neat epoxy (NE) were studied against polished stainless steel counterface using a newly developed block-on-disc (BOD) machine at 50N applied load, sliding distances (0–4.2 km) and sliding velocities of 2.8 m/s. The morphology of the worn surfaces of the composite and NE was studied using a scanning electron microscope (SEM). The result revealed that the longer the sliding distance is, the higher the weight loss. Up to 70% reduction in the weight loss was achieved when the epoxy was reinforced with the kenaf fibres. The wear mechanism was predominated by plastic deformation, in the resinous regions and debonding of fibres.

Si field emission arrays (FEAs) were produced using simple optical lithography and plasma dry etching. By optimizing plasma etching conditions, we achieved uniform ultra-sharp emitters with 50 nm radius, 3.6 μm height, 60^° cone angle, and 1.38×10⁶tips/cm² packing density. For the fabricated FEAs, it was found that turn-on voltage was 850 V and the field emission current was 24 μA at 1100 V. It was also found that field enhancement factor γ of the fabricated Si FEAs was approximately 58. Nanomechanical characterization of Si necked tips array was performed by nanoindentation technology. The critical buckling load and critical stress of the Si necked tips array were 570 μN and 1.192 GPa, respectively.

Based on the effects that signal light has on car-following behavior, this paper developed a new signal light model. Numerical tests show that our model can reproduce the cluster, the dissipation and the propagation of the stopping waves and starting waves resulted by signal light. Finally, linear stability analysis and simulation show that our model is always stable.

Ag-sheathed (Bi_1.6Pb_0.4)Sr₂Ca₂Cu₃O₁₀(Bi–2223) high temperature superconductor tapes with 0.1 wt% nano Cr₂O₃ were fabricated using the powder-in-tube method. The effects of intermediate rolling and sintering temperature on the transport critical current density (J_c) under self-field and applied magnetic field were studied. The X-ray patterns showed a dominant Bi–2223 phase (~80%). A decrease in J_c in applied magnetic field, parallel or perpendicular to the sample wide surface was observed for all tapes. Intermediate rolling improved the self-field J_c(T=77 K) of the tapes by 25%. Both J_c versus applied field curves and normalized pinning force density F_p/F_pmax versus applied field curves showed that the pinning strength was significantly enhanced with thermo-mechanical treatments. SEM micrographs showed improvements in the grain alignment of tapes with intermediate rolling. Enhancement in J_c was observed in the nano Cr₂O₃ added tapes.

This paper investigates properties of synchronization of trigonometric coupled maps. These maps have some advantages, such as an invariant measure, ergodicity and the possibility of Kolmogorov–Sinai (KS) entropy calculation. Moreover, an encryption algorithm based on a synchronized coupled map is suggested and described in detail. Also, some security analyses are presented to illustrate the effectiveness of the proposed scheme. The cryptosystem's speed is analyzed as well. Results of the various types of analysis are encouraging and it can be concluded that the proposed image encryption technique is a suitable choice for practical applications.