Physics and Astronomy

The Role of Methods for Applying Cucurbit[6]uril to Hydroxyapatite for the Morphological Tuning of Its Surface in the Process of Obtaining Composite Materials

Mon, 01 Jan 2024 00:00:00 GMT

The Role of Methods for Applying Cucurbit[6]uril to Hydroxyapatite for the Morphological Tuning of Its Surface in the Process of Obtaining Composite Materials Burkhanbayeva, Tolkynay; Ukhov, Arthur; Assylbekova, Dina; Mussina, Zukhra; Kurzina, Irina; Abilkasova, Sandugash; Bakibaev, Abdigali; Issabayeva, Manar; Yerkassov, Rakhmetulla; Shaikhova, Zhanat In this work, composite materials were obtained for the first time using various methods and the dependences of the resulting surface morphologies were investigated. This involves modifying the surface with cucurbit[n]urils, which are highly promising macrocyclic compounds. The process includes applying cucurbit[6]uril to the hydroxyapatite surface in water using different modification techniques. The first method involved precipitating a dispersion of CB[6] in undissolved form in water. The second method involved using fully dissolved CB[6] in deionized water, after which the composite materials were dried to constant weight. The third method involved several steps: first, CB[6] was dissolved in deionized water, then, upon heating, a dispersion of CB[6] was formed on the surface of HA. The fourth method involved using ultrasonic treatment. All four methods yielded materials with different surface morphologies, which were studied and characterized using techniques such as infrared (IR) spectroscopy and scanning electron microscopy (SEM). Based on these results, it is possible to vary the properties and surface morphology of the obtained materials. Depending on the method of applying CB[6] to the surface and inside the HA scaffold, it is possible to adjust the composition and structure of the target composite materials. The methods for applying CB[6] to the hydroxyapatite surface enhance its versatility and compatibility with the body’s environment, which is crucial for developing new functional composite materials. This includes leveraging supramolecular systems based on the CB[n] family. The obtained results can be used to model the processes of obtaining biocomposite materials, as well as to predict the properties of future materials with biological activity.

Thermodynamics of a newly constructed black hole coupled with nonlinear electrodynamics and cloud of strings

Mon, 01 Jan 2024 00:00:00 GMT

Thermodynamics of a newly constructed black hole coupled with nonlinear electrodynamics and cloud of strings Sudhanshu, Himanshu Kumar; Singh, Dharm Veer; Upadhyay, Sudhaker; Myrzakulov, Yerlan; Myrzakulov, Kairat This paper finds an exact singular black hole solution in the presence of nonlinear electrodynamics as the source of matter field surrounded by a cloud of strings in 4D AdS spacetime. Here, the presence of the cloud of string, the usual Bardeen solution, becomes singular. The obtained black hole solution interpolates with the AdS Letelier black hole in the absence of both the deviation parameter and magnetic charge and interpolates with the AdS Bardeen black hole in the absence of the deviation parameter and a cloud of strings parameter. We analyse the horizon structure and thermodynamics properties, including the stability of the resulting black hole, numerically and graphically. Thermodynamical quantities associated with the black hole get modified due to the nonlinear electrodynamics and cloud of strings. Moreover, we study the effect of a cloud of strings parameter, magnetic charge and deviation parameter on critical points and phase transition of the obtained black hole where the cosmological constant is treated as the thermodynamics pressure. The critical radius increases with increasing deviation parameter values and magnetic charge values. In contrast, the critical pressure and temperature decrease with increasing deviation parameters and magnetic charge values.

Thermodynamic constraints and observational validation of the deceleration parameter

Wed, 01 Jan 2025 00:00:00 GMT

Thermodynamic constraints and observational validation of the deceleration parameter Myrzakulov, Y.; Donmez, O.; Koussour, M.; Muminov, S.; Dauletov, A.; Rayimbaev, J. In this work, we propose a two-parameter parametrization for the deceleration parameter q(z) grounded in thermodynamic constraints and applied it to explore the evolution of the universe. The second law of thermodynamics imposes essential conditions to ensure that the system approaches equilibrium in late times, requiring q(z)≥−1 and [Formula presented] as z→−1. These constraints ensure that entropy does not decrease, stabilize the system, and facilitate a smooth transition from deceleration to acceleration, consistent with the observed cosmic expansion. Furthermore, the model avoids the phantom regime (ω<−1), preventing catastrophic future scenarios such as the Big Rip. Using the combined CC, Pantheon, SH0ES, and BAO datasets, we constrain the model parameters and compare the results with the standard ΛCDM model. Our findings indicate H0=70.82±0.88, with a transition redshift of zt=0.597±0.214, suggesting an earlier onset of acceleration compared to ΛCDM. The present deceleration parameter, q0=−0.364±0.032, implies a weaker acceleration than in ΛCDM. Moreover, we analyze the evolution of total energy density, pressure, and the effective equation of state parameter, confirming a quintessence-like behavior with ω0=−0.570±0.056. Our results provide a thermodynamically consistent framework for cosmic expansion, supporting a dark-energy-driven acceleration.

Thermodynamic behavior and phase transitions of black holes with a cloud of strings and perfect fluid dark matter

Wed, 01 Jan 2025 00:00:00 GMT

Thermodynamic behavior and phase transitions of black holes with a cloud of strings and perfect fluid dark matter Singh, Dharm Veer; Upadhyay, Sudhaker; Myrzakulov, Yerlan; Myrzakulov, Kairat; Singh, Bhupendra; Kumar, Manish This paper presents an exact black hole solution within a cloud of strings (CoS) and a perfect fluid dark matter (PFDM) field. The derived black hole solution interpolates between the AdS-charged Letelier black hole in the absence of the PFDM field and the AdS Reissner-Nordström black hole in the limiting case of the PFDM and CoS parameters. The thermodynamic properties of the black hole, including temperature, entropy, heat, and free energy, are modified in the presence of the PFDM field and CoS parameter. Furthermore, we investigate the black hole's critical points and phase structure in an extended phase space. We find that the critical temperature and pressure decrease with the CoS parameter but increase with the PFDM field. The Gibbs free energy versus temperature plot reveals a swallow-tail behavior, indicating a first-order phase transition, which terminates at a second-order phase transition.