International Journal of Modern Physics B

Three cases are reviewed of radioactive material with anomalous decay after ultrasound irradiation. In the pure element thorium-228 in distilled water, the radioactivity decreased faster after cavitation than the natural decay. The more complex molecule of Nickel Nitrate, made of radioactive nickel-63, in solution of nitric acid and distilled water was investigated before and after ultrasound irradiation. The X-rays produced by Bremsstrahlung of the electrons from the beta decay of Ni-63 were recorded and a 13% decrease of intensity was measured after 100 s of sonication. A decrease of nickel and an increase of other elements was detected by mass spectrometry in the sonicated sample. The Cobalt-57 decay was investigated by detecting the gamma and X-ray intensity from the Iron-57 resulting after its beta emission. In this third case too, an anomalous decay was observed after sonication. These three cases of anomalous behavior can be explained at the light of the Deformed Space–Time theory. It assumes that a suitable sudden variation of energy density can induce a local deformation of space–time, thus violating the Local Lorentz Invariance. This variation can be created by the ultrasounds in the matter, thus, allowing reactions that cannot occur in a flat (Minkowskian) space–time. The “neutralization” of a radionuclide occurs when it undergoes a DST transformation changing the radionuclide into non-radioactive nuclides.

In this paper, we consider the influence of magnetic pump field on the propagation of three-dimensional ultrashort optical pulse with Airy cross-section in a medium of a photonic crystal made of carbon nanotubes (CNTs). It is shown, that the pulse remains localized in a limited region of space and propagates quasi-stable. The possibility of efficient generation of high harmonics under the influence of an external magnetic field that were initially absent is observed.

Exploiting the analogy between ultracold atomic gases and the system of triplons, we study magneto-thermodynamic properties of dimerized quantum magnets in the framework of Bose–Einstein condensation (BEC). Particularly, introducing the inversion (or Joule–Thomson) temperature $T_{\mathrm{\text{JT}}}$ as the point where Joule–Thomson coefficient of an isenthalpic process changes its sign, we show that for a simple paramagnet, this temperature is infinite, while for three-dimensional (3D) dimerized quantum magnets it is finite and always larger than the critical temperature $T_c$ of BEC. Below the inversion temperature $T<T_{\mathrm{\text{JT}}}$, the system of triplons may be in a liquid phase, which undergoes a transition into a superfluid phase at $T\le T_c<T_{\mathrm{\text{JT}}}$. The dependence of the inversion temperature on the external magnetic field $T_{\mathrm{\text{JT}}}(H)$ has been calculated for quantum magnets of TlCuCl₃ and Sr₃Cr₂O₈.

Using a separable many-body variational wavefunction, we formulate a self-consistent effective Hamiltonian theory for fermionic many-body system. The theory is applied to the two-dimensional (2D) Hubbard model as an example to demonstrate its capability and computational effectiveness. Most remarkably for the Hubbard model in 2D, a highly unconventional quadruple-fermion non-Cooper pair order parameter is discovered.

A method has been proposed to reason the choice among the known optimized models for methods for estimating chlorophyll (Chl) concentration in the seawater according to the information-logarithmic criterion, which provides a comparison of theoretical models by the SeaWiFS data. It has been shown that the most appropriate means is to determine the Chl concentration, since the concentration of Chl in seawater is systematically investigated by marine ships or remote sensing. All optimized models of the optical properties of seawater can be verified by checking the simulated and measured Chl concentration data.

In this study, we consider conformable type Coudrey–Dodd–Gibbon–Sawada–Kotera (CDGSK) equation. Three powerful analytical methods are employed to obtain generalized solutions of the nonlinear equation of interest. First, the sub-equation method is used as baseline where generalized closed form solutions are obtained and are exact for any fractional order $\alpha$. Furthermore, residual power series method (RPSM) and $q$-homotopy analysis method ($q$-HAM) are then applied to obtain approximate solutions. These are possible using some properties of conformable derivative. These approximate methods are very powerful and efficient due to the absence of the need for linearization, discretization and perturbation. Numerical simulations are carried out showing error values, $\hslash$-curve for $q$-HAM and the effects of fractional order on the solution profiles.

Thin films of topological insulator (TI) Bi₂Se₃ were grown onto the surfaces of FeSe₂ layers of different thicknesses on Si (100) substrates by magnetron sputtering, forming bilayer films with smooth surface. Magnetic and transport measurements indicate ferromagnetism in these bilayer samples. Large coercive fields at low-temperatures and a room-temperature magnetic order were observed. Moreover, nonsaturated high-filed linear magnetoresistance (MR) and weak anti-localization effect were found in these bilayer thin films. These results indicate that the bilayer samples could have both strong spin–orbit coupling and ferromagnetic proximity effect, which are the desired features.

In this paper, we determine the application of the Fractional Elzaki Projected Differential Transform Method (FEPDTM) to develop new efficient approximate solutions of coupled nonlinear fractional KdV equations analytically and computationally. Numerical solutions are obtained, and some major characteristics demonstrate realistic reliance on fractional-order values. The basic tools, properties and approaches introduced in He’s fractional calculus are utilized to explain fractional derivatives. The consistency of FEPDTM and the reduction in computational time give FEPDTM extensive applicability. Furthermore, the calculations concerned in FEPDTM are too simple and straightforward. It is verified that FEPDTM is an influential and efficient technique to handle fractional partial differential equations. It is being observed that FEPDTM is more efficient than known analytical and computational methods.

The movement of large amounts of ions (e.g., potassium, sodium and calcium) in the nervous system triggers time-varying electromagnetic fields that further regulate the firing activity of neurons. Accordingly, the discharge states of a modified Hindmarsh–Rose (HR) neuron model under an electric field are studied by numerical simulation. By using the Matcont software package and its programming, the global basins of attraction for the model are analyzed, and it is found that the model has a coexistence oscillation pattern and hidden discharge behavior caused by subcritical Hopf bifurcation. Furthermore, the model’s unstable branches are effectively controlled based on the Washout controller and eliminating the hidden discharge states. Interestingly, by analyzing the two-parametric bifurcation analysis, we also find that the model generally has a comb-shaped chaotic structure and a periodic-adding bifurcation pattern. Additionally, considering that the electric field is inevitably disturbed periodically, the discharge states of this model are more complex and have abundant coexisting oscillation modes. The research results will provide a useful reference for understanding the complex dynamic characteristics of neurons under an electric field.

In this paper, we will solve the (3 + 1)-dimensional Yu–Toda–Sassa–Fukuyama equation (YTSFE) which widely investigates the dynamics of solitons and nonlinear wave arising in a fluid dynamics, plasma physics and weakly dispersive media. The Paul-Painlevé approach (PPA) is used for the first time to achieve the soliton solutions of this equation. Furthermore, the numerical solutions of this equation have been proposed by using the variational iteration method (VIM).

An optical waveguide is an important dielectric device that guides the propagation of light waves. Ion implantation is a competitive waveguide preparation technique with advantages including reliance, simpleness and flexibility. In this work, a 400-keV helium ion implantation with a fluence of $6.0\times 10^{16}$ ions/cm² was carried out to manufacture a planar waveguide on the surface of the fused silica glass. The formation mechanism of the waveguide was analyzed by the nuclear energy deposition based on the SRIM 2013 and the refractive index distribution with the help of the reflectivity calculation method (RCM). The geometry structure and the guiding performance of the waveguide were studied by the metallographic microscope and the end-face coupling system, respectively. The investigation on the fabrication and characteristics of fused silica glass optical waveguides is of great significance for the development of passive devices in the field of optical communications.

Effect of high bandgap $0.5$ nm AlAs on the electronic and optical properties of the ${\mathrm{\text{In}}}_{0.70}{\mathrm{\text{Ga}}}_{0.30}\mathrm{\text{As}}$/${\mathrm{\text{Al}}}_{0.60}{\mathrm{\text{In}}}_{0.40}\mathrm{\text{As}}$ superlattice is investigated by using effective mass approximation under the electric field. Electronic transitions are obtained as 0.403 eV and 0.023 eV for $E_{32}$ and $E_{21}$ in the gain region. Thin AlAs increases electron confinement in the superlattice and prevents electron leakage in the gain region which mostly results in higher absorption/emission in the superlattice. AlAs has no major effects on transitions energies in the gain region but it is effectively decreasing the total absorption in the injector region and preventing the internal absorption. AlAs also makes the superlattice optically more stable by decreasing the high refractive index change in the injector region by factor 5.

The prime objective of this paper is to obtain the exact soliton solutions by applying the two mathematical techniques, namely, Lie symmetry analysis and generalized exponential rational function (GERF) method to the (2+1)-dimensional generalized Camassa–Holm–Kadomtsev–Petviashvili (g-CHKP) equation. First, we obtain Lie infinitesimals, possible vector fields, and commutative product of vectors for the g-CHKP equation. By the means of symmetry reductions, the g-CHKP equation reduced to various nonlinear ODEs. Subsequently, we implement the GERF method to the reduced ODEs with the help of computerized symbolic computation in Mathematica. Some abundant exact soliton solutions are obtained in the shapes of different dynamical structures of multiple-solitons like one-soliton, two-soliton, three-soliton, four-soliton, bell-shaped solitons, lump-type soliton, kink-type soliton, periodic solitary wave solutions, trigonometric function, hyperbolic trigonometric function, exponential function, and rational function solutions. Consequently, the dynamical structures of attained exact analytical solutions are discussed through 3D-plots via numerical simulation. A comparison with other results is also presented.

In this work, we developed a technology for growing a single crystal of a ternary compound, using the Atomic Force Microscope (AFM), we studied the surface microrelief in 2D and 3D modes, using X-ray diffraction (XRD) analysis, determined the parameters of the unit cell of this phase and revealed that it crystallizes in tetragonal symmetry with lattice parameters $a=8.345$ Å and $c=6.8352$ Å, space group I4/mcm. Using the density functional method, using the ABINIT software package, using the Troiller–Martins pseudopotentials in the basis of plane waves, the band structure was calculated, the origin of the valence and conduction bands was determined. It was revealed that this phase is a direct-gap semiconductor with a bandgap of 0.56 eV. The parameters of the InGaTe₂ unit cell were calculated by the pseudopotential and linearized attached plane wave (LAPW) methods, the theoretical and experimental values of the lattice parameters are in good agreement. Based on the band structure, the effective masses of electrons and holes are determined. It is shown that the tensors of the inverse effective mass for both extreme have a diagonal form.

Motivated by the controversial bright exciton splittings in inorganic cesium lead halide perovskite nanocrystals, we studied excitation state of perovskite CsPbBr₃ by four-band model Hamiltonian. With spin–orbit coupling, the calculated band structure shows that the double degeneracy of each band around $\mathrm{\Gamma }(0,0,0)$ point is removed because of broken spatial inversion symmetry (SIS). With broken SIS, ring-shaped valence band maximum is formed in the band structure of ground state, and SU(2) vector potential in momentum is created with the excitation of one electron from valence band to conduction band by photon absorption. In the case of low density carrier, our theory also predicts that the energy splitting between the four binding electron-hole states by the vector potential is proportional to the power of laser light which certainly stimulates further experimental work in this intriguing topic.

All we know that the Burgers-KdV equation is extensively used to study the liquid flow with bubbles and the liquid moving flow in the elastic pipes. In this paper, we obtain the Lie point symmetries, self-nonlinear adjointness of a generalized Burgers-KdV equation (GB-KdVE) are obtained, it follows that the conservation laws are worked out. As a reduction of the GB-KdVE, a Burgers equation with general coefficients is presented, whose new strong symmetry and new nonlocal symmetries are generated, respectively. Furthermore, the noninvariant solutions of the GB-KdVE are produced as well. Finally, we propose the double linear differential constraints for GB-KdVE-type so that some soliton solutions are singled out.