Revista Mexicana de Física

Thermodynamic properties and coherent states for the harmonic oscillator in cosmic string space-time with dislocation

M. Salazar Ramírez, R. D. Mota, M. R. Cordero-López, S. de J. Guatemala Marín — Thu, 01 May 2025 00:00:00 +0000

We study the problem of a quantum harmonic oscillator in the presence of a repulsive inverse-square potential within a cosmic string spacetime that contains a dislocation. Also, we study how a rotational frame affects the quantum harmonic oscillator plus the repulsive potential within this space-time geometry. For both problems, we find three operators for the radial part of each problem and show that they close the su(1, 1) Lie algebra. From the theory of unitary irreducible representations of the su(1, 1) Lie algebra, we obtain the energy spectrum from an algebraic point of view. Also, we obtain the wave functions, the radial coherent states, and their time evolution. Finally, we calculate the thermodynamic properties for each of these problems.

Exact solutions for small systems: urns models

M. E. Hernández-García, J. Velázquez-Castro — Thu, 01 May 2025 00:00:00 +0000

In this study, we analyzed urn models by solving the discrete-time master equation using an expansion in moments. This approach is a viable alternative to conventional methods, such as system-size expansion, allowing for the determination of analytical expressions for the mean and variance in an exact form and thus valid for any system size. In particular, this approach was used to study Bernoulli-Laplace and Ehrenfest urns, for which analytic expressions describing its evolution were found. This approach and the results will contribute to a more comprehensive understanding of stochastic systems and statistical physics for small-sized systems, where the thermodynamic limit cannot be assumed.

Investigating phase portraits and extraction of new solitary wave solutions related to the generalized resonant nonlinear Schrödinger equation

A. Rashid Butt, N. Akram, N. Raza — Thu, 01 May 2025 00:00:00 +0000

This research dissects solitary wave solutions of generalized resonant nonlinear Schrödinger equation, whose primary uses include the transmission of light across nonlinear optical fibers. To generate bright, dark, kink-type, and singular kink-type solitary waves that rely on the intensity of the propagating pulse, an extended direct algebraic technique with symbolic computation is used. For different values of the parameters, the propagation of some specific solutions in a graphically detailed report has also been demonstrated. Then the bifurcation structures of the heeded model have been determined using a planer dynamical system and phase portraits.

Enhancing heat transfer performance: A comprehensive review of perforated obstacles

M. Menni, N. Kaid, M. A. Alkhafaji, M. Bayram, O. M. Ikumapayi, A. J. Chamkha — Thu, 01 May 2025 00:00:00 +0000

Heat exchangers (HEs) play a pivotal role in numerous industrial processes and thermal management systems, where efficient heat transfer (HT) is essential for optimal performance. This review paper examines the utilization of perforated obstacles as a means to enhance HT within HEs, integrating insights from both numerical simulations and experimental studies. The assessment entails a thorough analysis of the diverse geometric features of the perforated obstacles, encompassing perforation shape, size, arrangement, and spacing, alongside operational parameters. This examination vividly illustrates their profound influence on overall HE performance. Our investigation strongly underscores the efficacy of perforated obstacles in augmenting HT rates and reducing pressure drop, as evidenced by notable improvements in HT coefficients. Moreover, the varied industrial applications of perforated obstacles are investigated, encompassing HVAC systems, automotive cooling, refrigeration, and process industries, thus emphasizing their versatility and scalability. Overall, this review provides a comprehensive understanding of the potential of perforated obstacles in revolutionizing HT efficiency within HEs, paving the way for advancements in thermal engineering and industrial processes.

Scaling the fluctuation of the flow capacity of core logs in a formation in southeastern Mexico

Thu, 01 May 2025 00:00:00 +0000

This study evaluates flow capacity fluctuations in well cores from a southeastern Mexico formation using pdpk records. Petrophysical measurements provide wellbore wall flow capacity data, used to identify trends. Applying a dynamic scaling approach akin to the Family-Vicsek method, we analyze discrete kh* records. In particular, the order parameter structure function q was applied to the flow capacity records, and the exponents characterizing dynamic scaling α, β, z were identified, revealing self-affine scalings for fluctuations. Data collapse of flow capacities occurs in the northern zone with higher fractures and oil production, contrasting with the poorly collapsed flow capacity in the southern zone. This suggests superior flow capacity in fractal reservoir media compared to Euclidean counterparts.

Self-organized states of quasi-two-dimensional turbulence in an oceanic basin with topography

Luis Zavala Sansón — Thu, 01 May 2025 00:00:00 +0000

The evolution of oceanic-scale, quasi-two-dimensional turbulent flows in a closed basin with topography in a rotating system is studied using a shallow-water model. The basin is nearly flat in the central region and has a sloping coastal topography adjacent to the lateral walls. Two problems are analysed for basins in the northern hemisphere (positive Coriolis parameter). The first problem is the slow decay of an initially disordered flow. The main results are (1) the formation of a steady, anticlockwise flow around the basin that follows the topographic contours and (2) the spontaneous generation of an anticyclonic vortex at the nearly flat central part of the domain. This ‘preferred’ configuration was repeatedly found for arbitrary initial conditions with zero circulation and different Reynolds numbers. The well-defined current around the basin is associated with the direction of propagation of topographic Rossby waves along the contours of constant depth. However, when the initial circulation is sufficiently negative, the resulting flow configuration tends to be anticyclonic over the whole domain, including the coastal regions with topography. The second problem is the evolution of an initial flow at rest that is continuously forced until reaching a quasi-stationary turbulent state. In the presence of random forcing (with no preferential direction in time or space), the flow always tends to the preferred configuration found for decaying flows. The results are discussed in light of recent oceanographic observations in different basins. The limitations of the idealised simulations are outlined, together with recommendations for future studies.

Optical emission spectroscopy and modeling of DC CO2−N2−He mixture plasma

Thu, 01 May 2025 00:00:00 +0000

In this study, a direct current carbon dioxide-helium-nitrogen CO_2-N_2-He mixture plasma was studied to evaluate its dependence on pressure. Optical emission spectroscopy (OES), and a Langmuir probe analysis were used to characterize the plasma. The ion number density and electron temperature were determined by a dual Langmuir probe; both values exhibited a slight dependence on the pressure. The species observed via OES exhibited a slight dependence on pressure, and the results were in good agreement with the behavior of the electron temperature and ion density measurements. The N₂/N⁺₂ , N/N₂, and N/N⁺₂ ratios as a function of pressure (obtained via OES measurements) were quantitatively correlated with the electron impact excitation and dissociation cross sections ratios. The carbon monoxide/oxygen CO/O₂ ratio as a function of pressure (obtained via OES) indicated that more CO than O₂ was produced, which corresponded with the most important process pertaining to CO₂ splitting. This paper also presents the calculated electron transport coefficients, rate coefficients, electron energy distribution functions, and electron temperatures to support the trends observed during the experiment using BOLSIG+, a two-term Boltzmann solver. The rate coefficient due to excitation of the CO₂, N₂, and He obtained by BOLSIG+ are in good agreement with the present OES observation.

Evaluación experimental de la distribución espacial de la concentración de Radón 222 , utilizando detectores LR 115- tipo 2

Vanessa Guevara Rojas — Thu, 01 May 2025 00:00:00 +0000

El Radón-222 es un carcinógeno pulmonar reconocido al que la exposición humana debe ser limitada. Los principales emisores de Radón-222 en los ambientes se encuentran en el suelo y en los materiales de construcción, por contener cantidades diminutas de Uranio y Radio, que se descomponen radiactivamente en gas Radón-222. En este trabajo de investigación se determinó experimentalmente la distribución espacial de la concentración de Radón-222 en una oficina donde se pudo colocar un arreglo de 15 puntos de medición. En cada punto de medición se colocaron dos detectores a una altura desde el piso de: 40, 100 y 160 cm. Los detectores se colocaron por un periodo de 168 días. Se determinó que la distribución de concentración de Rn-222 en un recinto no es homogénea; habiendo mayores niveles de concentración en las zonas del recinto donde hay poca circulación de aire (valor máximo encontrado 113.21 Bq/m3) y niveles de concentración casi nulas en las zonas donde hay mayor circulación de aire. De esto concluimos que evaluar la concentración de Radón-222 en un recinto, considerando un solo punto de medición, el resultado obtenido no es representativo del lugar, puesto que sus valores pueden cambiar drásticamente si se escogiese otro punto de medición ubicado en el mismo recinto. Además, este rango de 0 a 45.60 Bq/m3 no supera el nivel de tolerancia más estricto de concentración de radón-222 de 150 Bq/m3, que hemos adoptado en este trabajo.

Radon-222 is a recognized lung carcinogen to which human exposure should be limited. The main emitters of radon-222 in the environment are found in soil and building materials, because they contain minute amounts of uranium and radium, which radioactively decay into radon-222 gas. In this research work, the spatial distribution of radon-222 concentration was experimentally determined in an office where an array of 15 measurement points could be placed. At each measurement point, two detectors were placed at a height from the floor of: 40, 100 and 160 cm. The detectors were placed for a period of 168 days. The average values of radon-222 concentration found in this work range from 0 to 45:60 Bq/m3. It was determined that the distribution of radon-222 concentration in an enclosure is not homogeneous; There are higher concentration levels in areas of the room where there is little air circulation and almost zero concentration levels in areas where there is greater air circulation. From this we conclude that evaluating the concentration of radon-222 in a room, considering a single measurement point, the result obtained is not representative of the place, since its values can change drastically if one or another measurement point located in the same room were chosen. In addition, this range from 0 to 45.60 Bq/m3 does not exceed the strictest tolerance level of radon-222 concentration of 150 Bq/m3, which we have adopted in this work.

Numerical phase shift analysis of nucleon-nucleon systems with Hellmann plus spin dependence

B. Khirali, B. Swain, S. Laha, D. Naik, U. Laha — Thu, 01 May 2025 00:00:00 +0000

The scattering phase shifts for quantum mechanical potential scattering by local interaction can be computed without solving the Schrödinger equation. This can be done by numerically solving the phase equation from the origin to the asymptotic region. Phase Function Method (PFM) is regarded as a resourceful method for calculating scattering phase shifts in quantum mechanics. We utilize the PFM to handle the Hellmann plus spin-orbit interaction. Our approach uses a five-parameter potential model to compute the scattering phase shift. Our results for nucleon-nucleon systems closely match previous findings.

Monte Carlo algorithm for calculating pre-neutron fragment mass and kinetic energy distributions from measurements using the 2E Technique for reaction 235U(nth,f)

M. Montoya, M. Alvarez — Thu, 01 May 2025 00:00:00 +0000

A nuclear fission event of an actinide results in the formation of two complementary primary fragments with masses (A, A'), which subsequently acquire kinetic energies (E, E') due to Coulomb repulsion. Following this, they emit (n, n') prompt neutrons, isotropically relative to their respective centers of mass, each with their respective kinetic energies. Consequently, due to recoil effects, the fragments reach the detectors with altered kinetic energies (e, e'). This study simulates an experiment using the 2E technique, intending to measure the distribution of (e, e') and (n, n'), from which it aims to infer the distribution of A, E and the average prompt neutron multiplicity as a function of pre-neutron fragment mass. For this purpose, a distribution of primary quantities is assumed as input to a Monte Carlo simulation algorithm of the experiment, whose output data should reproduce the values observed in that experiment.

Observation of nucleon transfer and deuteron breakup on d+13C system

Thu, 01 May 2025 00:00:00 +0000

The advanced computational methods continuum-discretized coupled-channel (CDCC) and coupled-reaction channel (CRC) approaches were used to analyze several sets of experimental data, including the angular distributions of ¹³C(d,d)¹³C at deuteron energy, E_d = 14.5 MeV, ¹³C(d,p)¹⁴C neutron stripping reaction obtained at E_d = 15.3 MeV, and data sets for ¹³C(d,t)¹²C neutron pickup reaction at E_d = 13.6 MeV and ¹³C(d,n)¹⁴N proton stripping reaction at E_d = 15.7 MeV. The analysis revealed that while forward scattering angles were well-described by parameter-free CDCC calculations accounting for deuteron breakup, backward angles were significantly influenced by virtual effects from proton and neutron transfer reactions. Notably, the impacts of neutron and proton stripping reactions were substantial, reflecting their large cross sections, whereas the contribution from neutron pickup-transfer reactions was less significant.

Evolution of non-covalent derivatives of pioglitazone with salicylic acid and its impact on crystallite characteristics and dissolution

M. Das, S. Panigrahy, R. Dash, Sk Habibullah, T. Das, S. Mallick — Thu, 01 May 2025 00:00:00 +0000

The bioavailability of a molecule is considerably influenced by its crystalline nature and behaviour, depending on various factors such as internal structure within its crystal lattice. This study aims to develop pioglitazone (PIO) eutectics with co-former salicylic acid (SA). And its effect on crystallite properties as well as drug dissolution has been studied. Pioglitazone-salicylic acid eutectic formulations i.e., PS1, PS2, and PS3 using different molar ratios of 1:1, 2:1, and 1:2 respectively were prepared using the ethanolic solvent evaporation method. DSC study showed a broad peak at 117.696 °C, which is lower than the melting peaks of PIO (195.61°C) as well as SA (158.69°C) confirming the formation of eutectic. Carbonyl-thiazolidine non-covalent bond or pi-pi attraction might have been involved for the formation of eutectics of PIO-SA having the docking score of -2.5 Kcal/M rather than co-crystals. Having a maximum value of strain (12.69 ± 8.04) in PS2 possibly due to higher deformity within the molecular layer when compared to other formulations and raw PIO. Further, the crystallite size of PS2 (18.57 ± 9.91 nm) was found to be smaller than the others (32.19 to 70.77 nm). All eutectic formulations presented improvement in drug dissolution. PS2 (PIO-SA as 2:1 molar ratio) resulted in drug release more quickly (86.90 %) than pure PIO (44.50 %) and other formulations (62.76 to 72.15 %) at 5 h. Consequently, creating eutectic formulations may be a useful tactic for enhancing PIO solubility.

Synthesis of hydrophilic carbon nanotubes via chemical vapor deposition using silicon oxide nanoparticles as seeds with potential biomedical applications

Thu, 01 May 2025 00:00:00 +0000

The research presented in this paper explores the synthesis of hydrophobic carbon nanotubes using silicon oxide nanoparticles as seeds through chemical vapor deposition. The study demonstrates the successful production of uniform-sized carbon nanotubes, essential for controlling their properties in diverse applications. By employing silicon oxide nanoparticles as catalysts, the pro- cess yields carbon nanotubes with specific characteristics suitable for potential biomedical applications. The investigation also highlights the dispersion in the size of silicon oxide nanoparticles and its potential influence on their collective behavior, empha- sizing the importance of this factor for future research endeavors. These findings contribute valuable insights to the field of carbon nanotubes, particularly in the context of biomedical applications, facilitating further advancements in this area.

Ion-induced atomic excitation in Vanadium

A. Bachrak, L. Jadoual, K. Bria, M. Ait El Fqih — Thu, 01 May 2025 00:00:00 +0000

Light emission from pure vanadium in the presence and in the absence of oxygen under 5 keV Kr⁺ ions bombardment is studied. Neutral V I (318.3 nm) spectral line shows a transient at beam-off conditions. The transient curve follows the characteristic of an oxide sputtering. Sputtering yields of adsorbed oxygen on V are calculated using SRIM and SDTrimSP from the spectral line V I 318.3 nm line with the assumptions that a monolayer of oxygen is adsorbed on vanadium with its surface exposed to the oxygen flux and that negligible recoil implantation of oxygen in vanadium is taking place. The tendency of sputtering yields is supposed to be due to the overlapping of individual collision cascades generated in the interaction of various components of Kr⁺ projectile with the vanadium surface.

The effect of standoff distance on the electrochemical corrosion behavior of Zn-Al pseudo alloy coating by arc spray on low carbon steel in a seawater environment

S. djerourou, Y. Mebdoua — Thu, 01 May 2025 00:00:00 +0000

An experimental study of Zn-Al pseudo alloy coatings prepared by twin dissimilar Zn and Al wires using the arc spray process at a different standoff distance, in order to protect low carbon steel substrates from marine corrosion has been undertaken in the present paper. The corrosion behavior of a Zn-Al pseudo alloy coating in a seawater solution collected from the Mediterranean Sea (Algerian coast), was evaluated by open circuit potential (OCP), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) tests. The obtained results reveal that all prepared Zn-Al pseudo alloy coatings can protect the substrate, but the coating obtained at 100 mm standoff distance with 55.73% Zn and 44.27% Al presents a better performance in corrosion protection when exposed to seawater solution compared to Zn-Al pseudo alloy coatings prepared at 120 and 140 mm standoff distances, respectively. A strong correlation is also observed between corrossion data, porosity fraction, and hardness.

Friction coefficient behaviour between rubber wheel and hydraulic concrete under different contact conditions

N. Santander Reyes, E. Gallardo-Hernández, E. E. Vera Cardenas — Thu, 01 May 2025 00:00:00 +0000

Currently, some countries are implementing the Bus Rapid Transit (BRT) system which combines the efficiency and quality of the Metro system and offers flexibility and low cost of infrastructure. To ensure the safety of users, the study of friction in pneumatic wheels in different environmental contaminants must be prove for these vehicles, since they carry out some fundamental functions like driving transmission, traction and braking. In this study, the behaviour of the coefficient of friction between SBR rubber and hydraulic concrete MR 48 was analysed in different contact conditions. Properties of SBR rubber were obtained with a universal testing machine and a durometer shore A, while the properties of concrete MR 48 were obtained with a compression testing machine. The friction experiments were performed by using the British pendulum method. Micrographs of the rubber surface were obtained by scanning electron microscope. The results showed that high values of coefficient of friction are obtained in dry condition and even higher at high temperature. Contrary, the lowest coefficients of friction were seen in wet condition and with contaminants. However, for the wet condition the coefficient of friction can recover after applying silica sand.

Avenues for a number density interpretation of dihadron fragmentation functions

T. Rogers, A. Courtoy — Thu, 01 May 2025 00:00:00 +0000

In this letter, we reassess the underlying physics of the number sum rule for dihadron fragmentation functions. We will argue that, currently, there are no settled constraints on what constitutes a valid number density interpretation for multihadron fragmentation functions. Imposing overly restrictive criteria might lead to misinterpretating the data. Most importantly, and on the basis of phenomenological analyses, the slightly varying definitions used in previous work are not excluded from possessing legitimate number density interpretations (up to the usual issues with ultraviolet divergences and renormalization), so long as they are paired with appropriate factorization theorems. We advocate for further theoretical analyses to be challenged with experimental data, available at JLab or at the future EIC.

Relating the free particle with the harmonic oscillator

Gerardo Francisco Torres del Castillo — Thu, 01 May 2025 00:00:00 +0000

We show that by means of a coordinate transformation in the extended configuration space the problem of a free particle can be related to that of a harmonic oscillator in classical mechanics and in quantum mechanics.

Wigner function under changes of reference frames

J. Berra Montiel, G. F. Torres del Castilo — Thu, 01 May 2025 00:00:00 +0000

We investigate the transformation laws of the Wigner function under changes of reference frames. By employing the coordinate transformation of the wave functions, we derive an integral representation for the transformed Wigner function in both position and momentum representations. To illustrate our results, we include some basic examples.

Thermodynamic analysis and mass spectra of heavy mesons via the generalized fractional Klein-Gordon equation

M. Abu-Shady, H. M. Fath-Allah — Thu, 01 May 2025 00:00:00 +0000

By employing the generalized fractional Nikiforov-Uvarov (GF-NU) method, we successfully derive solutions of the generalized fractional Klein-Gordon (GF-KG) equation for both the screened Kratzer and a specific class of Yukawa potentials. These solutions yield the generalized fractional energy eigenvalues across both the relativistic and non-relativistic domains. Furthermore, the corresponding generalized fractional eigenfunctions can be obtained. We employed the derived solutions to calculate the heavy-meson masses of Charmonium (cc) and Bottomonium (bb), along with those of heavy-light mesons (cs, cq, bs, bq). Notably, the Charmonium and Bottomonium masses were plotted as functions of the orbital and angular quantum numbers, reduced mass, and fractional parameter. Similarly, the heavy-light meson masses were plotted in relation to their orbital and angular quantum numbers. Additionally, a thermodynamic analysis of the heavy-light mesons was conducted. The obtained results demonstrate a high degree of concordance with established experimental data and the findings of other researchers