Vol. 66 No. 3 May-Jun (2020): Revista Mexicana de Fìsica

Cobalt ferrite nanopowders were successfully synthesized by the coprecipitation method and subsequent calcinations at 873 and 1073 K. The effects of the thermal treatments on the crystal structure, particle size and magnetic properties of the nanocompounds were investigated. The particle sizes were determined from transmission electron microscopy and an increase in sizes with the increment in calcination temperature was observed. The mean particle sizes were 29 and 42 nm, for samples calcined at 873 and 1073 K, respectively. By X-ray diffraction it was determined that the nanoparticles crystallized in the cubic spinel structure. Additionally, Fourier transform infrared spectroscopy studies confirms the presence of spinel metal oxide. The magnetization measurements as a function of the temperature and the applied magnetic field suggested that a large part of the nanoparticles calcined at 873 K present a superparamagnetic behavior at room temperature, while those calcined at 1073 K are mainly in the blocked regime at temperatures below 320 K. In addition, remarkably high coercivities of approximately 10.7 and 12.4 kOe were observed at low temperatures, for the nanopowders calcined at 873 and 1073 K, respectively.

A detailed analysis of the hydration shells of the 9.26 molal LiCl aqueous solution at the intermediate metastable thermodynamic state between the liquid (300 k) and the glass (120 k). The structural modelling of the LiCl6H2O at the supercooled-liquid state is conducted employing the Hybrid Reverse Monte Carlo (HRMC) simulation in combination with the neutron scattering data. The obtained pair distribution functions and the running coordination number are used as interpretive tools to examine the repartition of the water molecules around ions of lithium and chloride. HRMC represents a powerful tool to get provide detailed information on the hydration shell structures through the obtained pair correlations.

Investigation of band structure and thermo-physical response of the d⁰ new quaternary Heusler compounds KSrCZ (Z = P, As, Sb) within the frame work of density functional theory with full potential linearized augmented plane wave method has been analyzed. Results showed that type-Y3 is the most favorable atomic arrangement. All the compounds are found to be half-metallic ferromagnetic materials with an integer magnetic moment of 2.00 μB and a half-metallic gap E_HM of 0.292, 0.234, and 0.351 eV, respectively. The half-metallicity of KSrCZ (Z = P, As, Sb) compounds can be kept in a quite large hydrostatic strain. Thermoelectric properties of the KSrCZ (Z = P, As, Sb) materials are additionally computed over an extensive variety of temperature and it is discovered that all compounds demonstrates higher figure of merit. The properties of half-metallicity and higher Seebeck coefficient makes these materials a promising candidates for thermoelectric and spintronic device applications.

 

Numerous laboratory studies and field application tests have shown that polymer flooding is an effective method to improve the oil recovery by displacing residual oil after water flooding. In this work, a series of visual model displacement experiments was conducted in Hele-Shaw cells to determine the effectiveness of polymer flooding in homogeneous and fractured media with a fracture parallel or perpendicular to the flow direction. The matrix with parallel fracture to the flow direction presented a delay in the oil production process during water and polymer flooding with respect to the homogeneous medium and the one with perpendicular fracture, where the highest recovery numbers during waterflooding and polymer flooding were achieved for the medium with perpendicular fracture to the flow direction, reaching 56 % of cumulative oil recovery. The displacement results and multiphasic simulation show that the homogeneous medium is an attractive candidate for additional recovery application with polymer flooding after water flooding when the oil production reached almost zero, although the production rate is lower than the one obtained for a porous medium with a fracture perpendicular to the flow direction.

A new analytic model of fractal imbibition in porous media is derived. The topological Hausdorff dimension is used as a fractal parameter in
the proposed model. The fractal formulation is based on the model introduced by Li and Zhao to predict the production rate by spontaneous
imbibition. Cantor Tartans and Menger sponge fractals are used to simulate fractal porous media with different ramifications. Results of
illustrative examples are presented in the form of a set of curves, which reveal the features of enhanced oil recovery of the model under
consideration. The results are compared with the experimental behaviour found on core samples of previous publications.

This paper studies highly dispersive optical solitons, having Kerr law of refractive index, numerically. The adopted scheme is Laplace-Adomian decomposition method. Bright soliton solutions are displayed along with their respective error analysis.

In this study, new extended direct algebraic method is successfully implemented to acquire new exact wave solution sets for symmetric regularized-long-wave (SRLW) equation which arise in long water flow models. By the help of Mathematica symbolic calculation package, the method produced a great number of analytical solutions. We also presented a few graphical illustrations for some surfaces. The fractional derivatives are considered in the conformable sense. All of the solutions were checked by substitution to ensure the reliability of the method. Obtained results confirm that the method is straightforward, powerful and effective method to attain exact solutions for nonlinear fractional differential equations. Therefore, the method is a good candidate to take part in the existing literature.

In this paper we use the Dunkl derivative with respect to time to construct the
Wigner-Dunkl-Newton mechanics with time-reversal symmetry. We deflne the WignerDunkl-Newton velocity and Wigner-Dunkl-Newton acceleration and construct the WignerDunkl-Newton equation of motion. We also discuss the Hamiltonian formalism in the
Wigner-Dunkl-Newton mechanics. We discuss some deformed elementary functions such
as the ”-deformed exponential functions, ”-deformed hyperbolic functions and ”-deformed
trigonometric functions. Using these we solve some problems in on dimensional WignerDunkl-Newton mechanics mechanics.

We numerically study the percolation in 3D porous materials, populated by pores with random sizes at 3D grid of variable sizes. We identify the clusters for each grid as well the infinite cluster that is defined by the critical probability through the neighborhood hybrid structure method. Also we determine the characteristic size of each cluster in the material as well the volume of the infinite cluster that allows optimizing the percolation step at our simulation. In this work several tests were performed by variation the size of the grid. This allows us to determine the optimal size and how it affects the percolation by the simulating grids. Our main results show that in systems with pores having random radius the critical probability increases when size of grid L>40 (that correspond to typical size system about 4000 nm) with respect of the inform pores case.

Available experimental angular distributions for ⁶Li elastically scattered from ¹⁶O nucleus in the energy range 13.0–50.0 MeV are reanalyzed within the framework of optical potential, double folding optical potential as well as cluster folding potential. Special interest was paid to the cluster folding based on the well-known cluster structure of ⁶Li. Elastic scattering data for ⁶Li+¹⁶O system plotted as a function of momentum transfer showed that the real Coulomb nuclear interference region independent of the bombarding energy. This structural behavior for the data could be used to define the interaction potential with some certainty and to extract reliable values for the renormalization factors.  

The nuclear Gamow-Teller (GT) transition strength distributions B(GT)
have been studied for some sd-shell nuclei in the (3He, t) charge-exchange
reactions. The shell model calculations were performed by employing the
USDA and USDB effective interactions in the sd-model space. The re
sults of B(GT) calculations reproduce the the experimental Gamow-Teller
strength distributions well, while the calculated distribution of summed
GT transition strengths were closely reproduce the observed ones.

The elastic scattering angular distributions of 32S projectile by 12C, 27Al, 40Ca, 48Ca, 48Ti, 58Ni, 63Cu, 64Ni, 76Ge, 96Mo and 100Mo targets over the energy range 83.3 - 180 MeV are analyzed in the framework of the double folding model based on the optical model. The real part of the optical model potential is obtained by using double folding model for eight different density distributions of 32S which consist of Ngo, SP, 2pF, G1, G2, S, 3pF, and HFB. The imaginary part of the optical model potential is accepted as the Woods-Saxon (WS) potential. The theoretical results successfully reproduce the experimental data over both a wide energy and a wide target nucleus. Finally, simple and useful formulas which predict imaginary potential depths of each density are derived based on the elastic scattering results.

We adapt nonlinear stimulated Raman exact passage (NL-STIREP) technique first proposed by Dorier et
al. [Phys. Rev. Lett. 119, 243902 (2017)] to fractional population transfer in configurations and extend it
to nonlinear N-pod systems. We use NLF-STIRAP technique in a system and indicate that, NLF-STIREP
technique can guide the dynamics of the system as efficiently as a NLF-STIRAP but with considerably smaller
Rabi frequency amplitudes. We implement NLF-STIREP technique in fractional creation of ground molecular
Bose-Einstein condensates (BECs) from atomic BECs and show that, this technique is robust with respect to
changes in the time delay between the pulses and pulse intensity.

This work presents a novel derivation of the expressions that  describe the distortions of the CMB curve due to the interactions between photons and the electrons present in dilute ionized systems. In this approach, a simplified a one-dimensional evolution  equation for the photon number occupation is applied  in order to describe the aforemationed interaction. This methodology allows to emphasize the physical features ot the Sunyaev-Zeldovich effect and suggests the existence of links between basic statistical physics and complex applications involving radiative processes.

We study thermal dense coding in a two-spin model under an external magnetic eld. Its depen-
dencies on magnetic eld, strength of the spin squeezing and temperature are presented in detail.
Our main goal now is to study how we can increase the thermal dense coding capacity in the presence
of magnetic eld, strength of the spin squeezing and temperature. It shows that the dense coding
tend to valid value by setting the value of the input quantum correlations. Our most important
motive for this study is to examine the relationship between the thermal properties of super quan-
tum discord (SQD) and dense coding. The results show that the thermal properties of the SQD on
our channel enable us to determine when and under what conditions the system is suitable for valid
dense coding. Our proposals could be lead to that this scheme is efficient for quantum information
processing.

In this paper, the encryption improvement via modulation of the fractional order chaotic oscillators state variables, is presented. A network of N-coupled fractional order Lü chaotic oscillators, is synchronized. A voice message is encrypted via additive encryption, by using a state variable of the synchronized network. The selected state variable is modulated and used to encrypt the message again. The results are compared.

It is well known that the genus of strange attractors change if the control parameters of the dynamical system are modified. It is shown that the genus of strange attractors can also depend on the order of the system and that such changes generate different strange attractors. Topological tools are used to know the genus of the strange attractor.

In quantum information theory, effects of quantum noise on teleportation are undeniable. Hence,
we investigate the effect of noisy channels including amplitude damping, phase damping, depolarizing and phase ip on the teleported state between Alice and Bob where they share an entangled state by using atom-eld interaction state. We analyze the delity and quantum correlations as a function of decoherence rates and time scale of a state to be teleported. We observe that the average delity
and quantum correlations accurately depend on types of noise acting on quantum channels. It is found that atom-eld interaction states are affected by amplitude damping channel are more useful for teleportation than when the shared qubites are affected by noisy channels such as AD channel and phase ip. We also observe that if the quantum channels is subject to phase ip noise, the average delity reproduces initial quantum correlations to possible values. On the other hand,
not only all the noisy quantum channels do not always destroy average delity but also they can yield the highest delity in noisy conditions. In the current demonstration, our results provide that the average delity can have larger than 2/3 in front of the noise of named other channels with increasing decoherenc strength. Success in quantum states transfer in the present noise establishes the important of studing noisy channels.