Narrow Results

This paper focuses on the examination of various thermodynamic properties of RN-AdS black hole surrounded by quintessence, which is considered as one of the most widely accepted models of dark energy. The investigation involves the determination of temperature, entropy, heat capacity, pressure, equation of state, and Gibbs free energy for this particular black hole. By employing the laws of thermodynamics pertaining to black holes and considering the influence of quintessence, the impact on these quantities is thoroughly analyzed. Additionally, graphical representations of these quantities are depicted, and based on the critical points obtained, the stability and phase transition of the system are assessed. The study further delves into the examination of stability, instability, and the Swallowtail behavior of the system. Notably, due to the discontinuity in the heat capacity, a phase transition occurs within the system, resembling Van der Waals-like phase transitions that transpire between small, intermediate, and large black holes.

This paper presents a simple numerical method to calculate the eutectic mixture composition and melting temperature. Using a Newton–Raphson method to solve the nonlinear problem, the calculation is possible for n-component eutectic. We tested this algorithm on inorganic and organic mixtures. A better correlation between experimental and numerical results has been found for organic compound.

The plane-wave pseudo-potential method, which is based on density functional theory, is used to determine the structure, elastic constants and phase transition properties of transition metal nitride (TMN; TM = Ti, Zr, Hf, V, Nb and Ta) nanocomposite films under external pressures. Enthalpy–pressure and volume–energy relations of TMNs with different structures are calculated, and their relative stability is discussed. Mechanical stability of external pressure is calculated, and changes in elastic constants with external pressure are analyzed. The present study obtains influence of external pressure on the mechanical properties of material. By analyzing total energy–volume relation, enthalpy–pressure relation and mechanical stability, phase transition law of TMNs under external pressure is obtained.

The structural, electronic, magnetic properties of Mn₃XC (X=Al, Zn and Ga) antiperovskites have been investigated using first principles calculations based on Full-Potential Linearized Augmented Plane-Wave (FP-LAPW) method. Generalized Gradient Approximation with parameterization by Perdew (GGA-PBESol) is used to take into account the electron exchange–correlation interaction. Structural optimization is performed by fitting calculated data (energy-volume) to Birch–Murnaghan equation of state. Lattice constants increase in the order Mn₃AlC$\to$Mn₃GaC$\to$Mn₃ZnC. Electronic results show that there is no bandgap near the Fermi level. While the magnetism in these compounds is derived mainly from Mn atom. Finally, thermodynamic properties, including bulk modulus, heat capacities, thermal expansion and Grüneisen parameter, are computed using quasi-harmonic Debye model and analyzed in detail.

In this work, the first-principles density functional calculations of the structural, elastic, electronic, magnetic, thermal and thermoelectric properties of NiVSn half-Heusler compound are carried out. The exchange and correlation potential are treated by using Generalized Gradient approximation of Perdew, Burke and Ernzerhof (GGA-PBE), GGA plus Tran–Blaha-modified Becke–Johnson (mBJ-GGA) approach and mBJ-GGA+U where U is the Hubbard on-site Coulomb interaction correction (mBJ-GGA+U). Structural calculations revealed that NiVSn is stable in type 1 structure ferromagnetic state. Elastic properties show that our compound is mechanically stable, ductile and anisotropic. The results of the band structures and density of states display a half metallic behavior of NiVSn with an indirect bandgap of 0.476, 0.508 and 0.845 eV by using GGA-PBE, mBJ-GGA, and mBJ-GGA+U, respectively. The total magnetic moment calculated is integer of 1 $\mu$B confirming a half metallic behavior of NiVSn and follows the well-known Slater–Pauling rule (${\mu }_{\mathrm{\text{tot}}}=Z_{\mathrm{\text{tot}}}-18$); therefore, the studied compound is suitable for application in spintronic fields. The thermodynamic properties such as bulk modulus, the heat capacity, the Debye temperature, and the thermal expansion coefficient are investigated using quasi-harmonic Debye model (QHDM). The thermal results show that NiVSn can be applied in extreme temperature and pressure conditions. The thermoelectric properties are studied employing the BoltzTrap code. The calculated transport properties are very interesting for the spin-down channel with high electrical conductivity, high Seebeck coefficient, and figure of merit value approaching unity. As a result, the half-Heusler alloy NiVSn is a promoter for conventional thermoelectric materials.

In this paper, by applying the generalized uncertainty principle (GUP) at the final stage of black hole evaporation, we have proposed a thermodynamic explanation for the minimal scale of quantum gravity, i.e. it may stem from the basic requirements of the third law of thermodynamics for quantum gravitation system. At the same time, we have interestingly found that the third law of black hole thermodynamics acts as a supervisor in quantum gravity spacetime to ensure the causality of the spacetime as that does in classical gravity.

In this paper, titanium dioxide methylene blue molecularly imprinted polymer (TiO₂-MB-MIP) was prepared by using MB-MIP as supported carrier. Through the study of its adsorption performance and photodegradability, it was found that the prepared TiO₂-MB-MIP has both the adsorption capacity and the photodegradation capacity on MB. The static adsorption experiment shows that its adsorption and photodegradation capacity can reach 1202.1mg⋅g${}^{-1}$ when the original concentration of MB is 5.0mg⋅mL${}^{-1}$. In addition, the degradation ability of the material in MB aqueous solutions was studied under varying light conditions. By analyzing the nitrogen and carbon content in the adsorbed solutions, the degradation process was found that the carbon and heteroatoms nitrogen in MB can be degraded to CO₂, and NH${}_4^{+}$ or NO${}_3^{-}$, respectively. The adsorption isotherm thermodynamics and kinetics model study found that the adsorption process conforms to the Langmuir isotherm equation and the quasi-secondary kinetic model, indicating that the adsorption is basically monolayer adsorption and the adsorption process is the chemical rate control step. The TiO₂-MB-MIP can be used to protect our environment by treating pigment wastewater efficiently.

In this paper, the thermodynamical properties and the phase transitions of the charged accelerating anti-de Sitter (AdS) black holes are investigated in the framework of the $f(R)$ gravity. By studying the conditions for the phase transitions, it has been shown that the $P-V$ criticality and the van der Waals like phase transitions can be achieved for $T\approx T_c$. The Joule–Thomson expansion effects are also examined for the charged accelerating AdS black holes of the $f(R)$ gravity. Here, we derive the inversion temperatures as well as the inversion curves. Then, we determine the position of the reverse point for different values of mass $M$ and parameter $b$ for the corresponding black hole. At this point, the Joule–Thompson coefficient is zero. So, in such case, we can say that such point is very important for the finding of cooling–heating regions. Finally, we calculate the ratio of minimum inversion temperature and critical temperature for such black hole.

If gel swells in binary solvents, two unusual phenomena may appear. Two solvents with relatively low swelling ability may become a good solvent for the polymer with high swelling ability when mixed, which is known as a cosolvency effect. In contrast, a cononsolvency effect indicates polymer is less soluable in solvent mixtures than it is in each of the cosolvents. In this work, we develop a thermodynamic theory to describe the equilibrium swelling behaviors of gels in binary solvents based on the Flory–Huggins lattice model. The model can reproduce both cosolvency and cononsolvency effects, showing that these effects are caused by the preferential absorption of the solvent by polymer together with solvent–solvent interactions. The model is also applied to describe experimentally observed cosolvency and cononsolvency effects in the literature, which shows an acceptable agreement.

This work presents the experimental evaluation of the energy performance of transcritical CO₂ refrigeration and heat pump systems. The optimal gas cooler pressures and the optimal COP have been analyzed from a thermodynamic point of view. The systems used a new dual expansion valve and a balance CO₂ liquid receiver adjustment device, which can control high and low side pressure effectively. Moreover, we demonstrate the influence of the internal heat exchanger (IHX) on the systems' performances, on the basis of the analysis of the relative COP index RCOPI, the compressor power index RP_CI and other parameters which can confirm the truth of. The experimental evaluation covers five evaporating levels (-10 to 10°C) and in a wide range of gas cooler pressures (75 to 120 bar). It is concluded that with the IHX system, compressor power is relatively low when the high side pressure is over 100 bar, and the evaporation temperature is below 0°C. The COP of the system without the IHX is slightly higher than the system with the IHX; it is increasing about 3% to 5%, when the evaporation temperature is over 5°C. Relative to the single expansion process, the dual expansion cycle can decrease the influence of pressure fluctuations of CO₂ supercritical fluid and liquid mixture on the systems.

Research Highlights

• •Electronic, magnetic, elastic and thermoelectric properties of RbCrC alloy are investigated.
• •Material is half-metallic, ductile and anisotropic in nature.
• •The total magnetic moment (3$\mu$B) obeys the Slater–Pauling rule.
• •The HM RbCrC compound is identified as potential candidate for spintronic applications.
• •ZT calculated values of 0.89 and 0.94 make RbCrC a promising thermoelectric material candidate for use in future devices.

The aim of this work is to investigate the half-metallicity behavior, elastic, thermodynamic and thermoelectric (TE) properties of the Heusler compound RbCrC using the generalized gradient approximation (GGA-PBE96) and the modified Becke–Johnson (mBJ) approach. The electronic band structures and density of states reveal that RbCrC is a half-metallic ferromagnet (HMF). The calculated total magnetic moment of 3$\mu$B follows the Slater–Pauling rule ($M_{\mathrm{\text{tot}}}=Z_{\mathrm{\text{tot}}}-8$). The half-metallicity character can be maintained in the 5.4–7.4 Å lattice constants range and the 0.8–1.2 $c$/$a$ ratio range. Existence of half-metallic ferromagnetism in RbCrC makes it a promising material for practical applications in the spintronic field. Also, the RbCrC exhibits a ductile and anisotropic behavior. The quasi-harmonic Debye model (QHDM) is used to calculate the thermodynamic properties. The BoltzTraP code which is based on semi-classical Boltzmann theory (SCBT) is applied for calculating TE properties. According to the obtained figure of merit values (ZT between 0.89 and 0.94 from 50 K to 800 K), the RbCrC alloy remains a good candidate for thermoelectric applications.

The adsorption behavior of acetic acid on zeolite 13X was studied at 25°C, 35°C and 45°C in a batch experiment. Experimental data were applied to pseudo-first-order and pseudo-second-order adsorption kinetic models, and tested against Langmuir and Freundlich isotherms. Thermodynamic parameters (ΔG, ΔH and ΔS) of adsorption were also calculated. The data fit the pseudo-second-order kinetic model and Freundlich isotherm well. The calculated values of ΔG, ΔH and ΔS indicate that the adsorption is spontaneous and endothermic; it causes an increased extent of randomness at the solid-solution interface.

Previous work by the author [David Sands 2008 Eur. J. Phys. 29 129 doi:10.1088/0143-0807/29/1/013] has compared the Boltzmann entropy, k lnW, with the thermodynamic entropy, ClnT, in the case of a temperature-independent heat capacity, C. The simple form of both entropy expressions allows for a simple expression for W and a physical interpretation on the accessible states behind this expression was presented. For the case when C varies with temperature, as in a solid below the Debye temperature, it is not so obvious that this interpretation applies. If there is no simple interpretation of the accessible states it is by no means clear that the Boltzmann entropy is the same as the thermodynamic entropy. In this paper the accessible states of more complex systems is examined. It is shown that the same idea of the accessible states can be applied, but that a real difference between the Boltzmann and thermodynamic entropies is implied by this interpretation.