Modern Physics Letters B

The wave function of a dilute hard sphere Bose gas at low temperatures is revisited. Errors in an early 1957 paper are corrected. The pair distribution function is calculated for two values of .

Integrable couplings are presented by coupling given integrable couplings. It is shown that such coupled integrable couplings can possess zero curvature representations and recursion operators, which yield infinitely many commuting symmetries. The presented zero curvature equations are associated with Lie algebras, each of which has two sub-Lie algebras in form of semi-direct sums of Lie algebras.

The conformational transition of DNA is studied by considering electron–electron interaction and coupling to the environment. It is shown that the effect of counterions on DNA can be expressed approximately by the change of elasticity constant of the DNA backbone. We set up the coupled nonlinear equations to describe the interaction between the longitudinal displacement of DNA backbone and the electronic wave function as well as the solvent effect. It is also proved that the longitudinal displacement of DNA statistics the ϕ⁴ field form. With the help of the ϕ⁴ statistics properties, it is illustrated that the salt concentration and electron correlation plays an important role in the structural phase transition of DNA.

Uniaxial loading tests of copper with inter-atomic potential finite-element model are carried out to determine the corresponding ideal tension and compression strength using the modified Born stability criteria. The influence of biaxial stresses applied perpendicularly to the [100] loading axis, on the ideal strength is investigated, and tension-compression asymmetry in ideal strength under [100] loading is also studied. The results suggest that asymmetry for yielding strength of [100] nanowires may result from anisotropic character of crystal instability. Moreover, the results also reveal that the critical resolved shear stress in the direction of slip is not an accurate criterion for the ideal strength since it cannot capture the dependence on the loading conditions and hydrostatic stress components for the ideal strength.

From a single process, GaN layers were laterally overgrown on maskless stripe-patterned (111) silicon-on-insulator (SOI) substrates by metalorganic chemical vapor deposition. The influence of stress on the behavior of dislocations at the coalescence during growth was observed using transmission electron microscopy (TEM). Improvement of the crystalline quality of the GaN layer was demonstrated by TEM and micro-Raman spectroscopy. Furthermore, the benefits of SOI substrates for GaN growth are also discussed.

This letter considers the functional projective synchronization problem for Genesio–Tesi chaotic systems. Based on our earlier work, a new control scheme, which consists of a linear dynamic controller and a nonlinear static feedback controller, is applied to achieve the synchronization. A numerical simulation is presented to show the usefulness of the proposed control scheme.

Some magnetic characteristics of Nd-Fe-B sintered magnets have been clarified, especially in the near vicinity within three times their length for cylindrical magnets. The flux densities as a function of distance (z) along the z-axis from the center of a single magnet were determined by utilizing Hall sensors. The repulsions between two magnets possessing identical shape were directly measured, also as a function of z, by using a home-made apparatus adopting piezoelectric device. The respective result has turned out well, coinciding with that of corresponding finite element method analysis and some analytical solutions. Also in this investigation, the correct formula directly applicable to the near H-field strength along the magnetic moment of a cylindrical magnet has been determined to be the exact solution that defies all confusing approximations or assumptions in theory, which were seen in textbooks or published in papers. Furthermore an analytical solution for the repulsion of magnet twins (cylindrical or hexagonal in shape), which can be handy in designing a variety of superconducting and/or electromagnetic devices, has been derived basically from Biot–Savart Law.

This paper studies the adaptive full state hybrid projective synchronization method. Based on the Lyapunov stability theory, an adaptive controller is designed. It is proved theoretically that the controller can make the states of the dynamical system and the response system with known or unknown parameters asymptotically full state hybrid projective synchronized. A unified chaotic system is used as an example and numerical simulations show the effectiveness of the scheme.

Taking the influences of piezoelectricity and spontaneous polarization into consideration, the nonlinear optical Kerr effect in a nitride semiconductor coupling double quantum well (DQW) has been theoretically investigated by using the compact density matrix approach and iterative treatment. The electronic eigenstates in a nitride DQW are exactly solved based on the built-in electric field model already constituted in recent reference. The band non-parabolicity effect of nitride heterostructures has been taken into account. A typical wurtzite GaN/AlGaN DQW is chosen to perform numerical calculations. The calculated results reveal that the optical Kerr coefficients sensitively depend on the structural parameters of the coupling DQW system. Moreover, a strong optical Kerr effect can be realized in the nitride DQW by choosing a group of optimum structural parameters and doped fraction.

In this letter, we discuss an application of the variational iteration method on obtaining series solution and exact solution of Helmholtz equation with initial conditions. The suggested algorithms are quite efficient and are practically well-suited for use in this class of equation. The proposed iterative schemes find the solution without any need to discretize the variables. The results reveal the advantages of the method for Helmholtz equation.

The solid solutions of Pb_1-xSm_x(Zr_0.50Ti_0.50)_1-x/4O₃ (PSZT), x = 0.00, 0.03, 0.06 and 0.09 were prepared by a mixed oxide method at high temperature (sintering temperature 1200°C). Preliminary X-ray structural analysis suggests the formation of single-phase compounds at room temperature in tetragonal crystal system. The microstructural SEM analysis shows that the grains of the materials are almost spherical and also uniformly distributed over the surface. Detailed studies of dielectric properties (ε, tanδ and σ) of the materials in a wide temperature range (30–500°C) at different frequencies (10³–10⁶ Hz) reveal that the compounds have transition temperatures well above the room temperature. The analysis of the diffusivity of the dielectric peaks in these compounds provides values between 1 and 2, where the higher values indicate great disorder in the system. The temperature dependence of ac conductivity and the value of activation energy in different regions suggest that the conduction process is of mixed type (i.e. singly ionized in ferroelectric region and doubly ionized in paraelectric phase).