Vol. 66 No. 2 Mar-Apr (2020): Revista Mexicana de Física

Structural, elastic, electronic and magnetic properties of the Nickel-based magnetic shape memory alloys (MSMA) Ni₂MnSb, Ni₂MnSn and Ni₂MnSb_0.5Sn_0.5, are investigated using the full-potential linearized plane wave plus local orbital method (FP-LAPW+lo). With Perdew-Burke-Ernzerhof (PBE) exchange-correlation, generalized gradient approximation (GGA) is used to describe the electronic exchange correlations energy. Equilibrium lattice constant, bulk modulus, and its pressure derivative are calculated and compared with available data. Using the total energy versus strain in the framework of the FP-LAPW+lo approach, we compute the elastic constants of the studied compounds in their austenite structure. Good agreement is found with other calculations both for Ni₂MnSb and Ni₂MnSn. Magnetic moments agree well with available results.

The effect of adding three different layered clays, a sodium montmorillonite and two commercial modified montmorillonites, on the morphology and molecular dynamics of natural rubber characterized by Transmission Electron Microscopy and Thermally Stimulated Depolarization Currents (TSDC) was studied. Carbon black was employed as reinforcing filler in a standard compound prepared and used for comparison purposes. The morphological results revealed that the sample with Cloisite\circledR 15A displays the highest degree of exfoliation, which suggests a stronger compatibility between the organic and inorganic phases. When the dispersion degree increases, a decrease of the activation energy was found from the quantitative analysis of the space charge dielectric relaxations.  From the qualitative analysis of the dipolar dielectric relaxations around $T_{g}$, changes in  the dielectric relaxation profile and in the peak localization were attributed to probable interactions between the nanofillers and the elastomer in the glass transition region of the NR.

Because the development of techniques for pumping parallel flows in miniaturized systems are required, in the present investigation, a semi-analytical solution based in the matrix inverse method and by Laplace transform for the transient flow of multi-layer immiscible fluids in a narrow capillary, under electroosmotic and pressure driven effects, is obtained. The dimensionless mathematical model to solve the electric potential distribution and the velocity field in the start-up of flow, consist on the Poisson-Boltzmann and momentum equations, respectively. Here, the transported fluids are considered symmetrical electrolytes and because the interfaces between them are polarizable and impermeable to charged particles, interesting interfacial effects appear on the velocity profiles when an external electric field is applied. The results show graphically the influence of the different dimensionless parameters involved in the dynamics of the fluid flow. This study demonstrates that by considering electrical interfacial effects, produce velocity jumps at liquid-liquid interfaces, whose magnitude and direction depend on the concentration and polarity of electric charges in those regions; finally, it is observed that the time to reach the steady-state regime of the fluid flow is only controlled by the dimensionless viscosity ratios. This investigation is a theoretical contribution to simulate transient multi-layer fluid flows under electric interfacial effects, covering different implications that emerge in the design of small devices into the chemical, biological and clinical areas.

The objective of the current research paper is to investigate the effects of surface roughness on magnetohydrodynamic nonlinear mixed convection nanofluid flow over vertically moving plate. The highly coupled dimensional nonlinear partial differential equations (NPDE) are converted into dimensionless NPDE along with the boundary conditions with the help of non-similar transformations. The resulting set of dimensionless nonlinear PDE’s are solved by using Quasilinearization technique and implicit finite difference method. Impacts of various dimensionless parameters, namely, Brownian diffusion (Nb), nonlinear mixed convection ( ), nanoparticle buoyancy ratio (Nr), Lewis number (Le), thermophoresis (Nt), frequency (n), magnetic (M) and small parameter ( ) are studied in detail on profiles as well as gradients. The results reveal that increasing values of  increase the velocity profile, while increasing values of Nr decrease the same. Further, increasing values of and n exhibit sinusoidal variations on skin-friction coefficient, heat and nanoparticle mass transfer rates. Moreover, the presence of nonlinear mixed convection parameter has significant effects on fluid flow compared to its absence. In addition to this, rate of heat transfer is analyzed in presence and absence of nanoparticles.

The scenario of this attempt is to elucidate the nature of hydrodynamic hybrid nanofluid over a moving frame. Solar radiation and the spherical shape particle are implemented. The implication of suitable transformation corresponds to self-similarity equations. Least square and RKF 45^th-order techniques are employed to evaluate these non-dimensional equations. For better understanding of the problem, energy and flow features are demonstrated for distinct physical constraints. It is recognized that the transfer of fluid heat is pronounced for enhancing  but dismisses in rising values of . The larger   generates more heat in liquid that results in improvement of temperature.

A viscous flow is maintained over a porous and rotating disk. The porous disk is stretched (shrunk) with the non-uniform velocity in the radial direction. Note that the viscous fluid is injected (blown) normally with non-uniform velocity. The study is under taken by considering the combined and individual effects of injection (suction), stretching (shrinking) and rotation. The kinematics properties associated with the disk are depending upon the radial coordinate. The governing partial differential equations (PDE’s) are simplified and transformed into a new system of DE’s. The set of boundary value ODE’s is solved with the help of a numerical method. The transformed equations (presented over here) are new and to the best of authors knowledge, the equations are not published in literature. In particular cases, the modeled equations may reduce to the classical problems of rotating disk flows. The previous models of rotating disk flows with or without porosity and stretching (shrinking) effects are summarized into a single model. For fixed value of the governing parameters and different sizes of "infinity", no increase/decrease in the thickness of boundary layer is seen but the profiles of velocity components and pressure are significantly changed with the different levels of "infinity".

The role played by non-inertial frames in physics is one of the most interesting subjects that we can study when dealing with a physical theory. It does not matter whether we are studying classical theories such as special relativity or quantum theory, the idea of an accelerated frame is always one of the first ideas to come to our minds. In the case of special relativity, a problem with the concept of rigidity emerged as soon as Max Born gave a reasonable definition of rigid motion: the Herglotz-Noether theorem imposes a strong restriction on the possible rigid motions. In this paper, the equivalence of this theorem with another one that is formulated with the help of Frenet-Serret formalism is proved, showing the connection between the rigid motion and the curvatures of the observer's trajectory in spacetime. In addition, the Dirac equation in the Frenet-Serret frame for an arbitrary observer is obtained and applied to the rotating observers. The solution in the rotating frame is given in terms of that of an inertial one.

In this contribution, a simple analytical method (which is an elegant combination of a well known methods; perturbation method and Laplace method) for solving non-linear and non-homogeneous fractional differential equations is pro- posed. In particular, the proposed method was used to analysed the fractional Duffing oscillator.The technique employed in this method can be used to analyse other nonlinear fractional differential equations, and can also be extended to non- linear partial fractional differential equations.The performance of this method is reliable, effective and gives more general solution.

In this paper, we obtain the exact solutions of Duffin-Kemmer-Petiau equation spin-1 in the
presence of the Aharonov-Bohm and Coulomb potential in the gravitational field of cosmic string
and a global monopole, we are study the DKP equation in commutative space-time, We separated
the variables with the help of Wigner functions and the parity operator, We solved the system of
the second order differential equation in the case of P = (−1) j+1 , but in the case of P = (−1) j we
solved the system in j = 0. The spectrum of energy in the gravitational field of cosmic string and a
global monopole are different, and the commutation relation of the angular momentum are obviously
different from Pauli criterion in the Aharonov-Bohm effect, in spin-0 and spin-1 we have the non-
commutativity energy by the perturbation theory, the energy is transition from commutative to
non-commutative spac

From the Wheeler Dewitt solutions, the scale factor of the initial universe is discussed. In this study scale factors from Wheeler Dewitt solutions, loop quantum gravity, and phantom energy dominated stages are compared. Certain modifications have been attempted in scale factor and quantum potentials driven by canonical quantum gravity approaches. Their results are discussed in this work. Despite increment of phantom energy density avoidance of big rip is reported. Scale factors predicted from various models is discussed in this work. Relationship between scale factors and smooth continuation of aeon is discussed by the application of conformal cyclic cosmology. Quantum potentials for various models are correlated and a correction parameter is included on the cosmological constant. Phantom energy dominated, final stage non-singular evolution of the universe is reported. Eternal increment of phantom energy density without interacting with dark matter is reported for the consequence of evolution of the future universe. Also, the non-interacting solutions of phantom energy and dark matter are explained. As the evolution continues even after the final singularity is approached, the validity of conformal cyclic cosmology is predicted. Non zero values for the scale factor for the set of eigenvalues are reported with a graph

It has been proved that the integer order dierential equation does not
represent the real behaviour of nature for the Newton's law of cooling.
Then, we solve the Newton's cooling law using the conformable deriva-
tive, as result we obtain the Kohlrausch stretched exponential function.
Due to the free parameter 0 < 1, we can t this function with the
graph of the experimental data set. It is shown that the experimental data
coincide with those theoretical when = 0:77269 and k = 0:018765.

A Fake Calibration Attack process for a Continuous Variable-Quantum Key Distribution system using a Beam Sampler is presented. The Fake Calibration Attack allows a calibration that balances the Standard Quantum Limit for all the optical path in the experiment (differential Standard Quantum Limit is ≈ 0.39 dB) allowing Eve to acquire ≈ 0.0671 for a particular information quadrature which establishes a Quantum Bit Error Rate ≈ 5.8%. As a final result, the balancing of the Standard Quantum Limit for both states of polarization signals allows maintaining the overall Quantum Bit Error Rate at a particular value ≈ 3%, which implies an important basis for detecting a potential spy considering the minimum Quantum Bit Error Rate.

In this study, half-value thicknesses and mass attenuation coefficients of polyethylene absorber have been measured experimentally using the beta sources ⁹⁹Tc, ¹⁴⁷Pm, ¹³⁷Cs, ²⁰⁴Tl, ²¹⁰Pb and ³⁶Cl. There is an inconsistency between experimental and calculated values of half value thicknesses obtained with the help of standard attenuation equation. In order to overcome this discrepancy, the fractional attenuation equation which was redefined and resolved using Caputo fractional derivative has been used. The theoretical results obtained according to this new equation are in agreement with experimental results around 0.3 value of the order of fractional derivative.

The performance of quantum computers today can be studied by analyzing the
eect of errors in the result of simple quantum algorithms. The modeling and char-
acterization of these errors is relevant to correct them, for example, with quantum
correcting codes. In this article we characterize the error of the ve qubits quantum
computer ibmqx4 (IBM Q), using a Deutsch algorithm and modeling the error by
Generalized Amplitude Damping (GAD) and a unitary misalignment operation.

The cosmetic industry has turned its attention to using vegetable products; the number of different vegetable oils used in the cosmetic industry has risen in the last years. In this work, the so-called photopyroelectric techniques are used for studying the thermal effusivity and diffusivity of wheat germ, mamey seed, walnut, coconut, and linseed oils. The thermal conductivity was calculated using a mathematical relationship and density was measured. Therefore, full thermal characterization is achieved. The obtained values for the studied oils are closed to other vegetable oils already reported. This similarity is partially a consequence of the similar chemical structure presented in this type of materials.

Rev. Mex. Fis. 66 (2) 2020

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