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The reheating era of inflationary universe can be parameterized by various parameters like reheating temperature T re , reheating duration N re and average equation of state parameter ω ¯ re , which can be constrained by observationally feasible values of scalar power spectral amplitude A s and spectral index n s . In this work, by considering the quadratic chaotic inflationary potential with logarithmic correction in mass, we examine the reheating era in order to place some limits on model's parameter space. By investigating the reheating epoch using Planck 2018+BK18+BAO data, we show that even a small correction can make the quadratic chaotic model consistent with latest cosmological observations. We also find that the study of reheating era helps to put much tighter constraints on model and effectively improves accuracy of model. [ABSTRACT FROM AUTHOR]

We introduce a new, well-mannered and stable model. To create the model, we used well-known Finch–Skea [1] ansatz for the metric potential . For our model, we look into a number of physical variables, including the energy density, pressures, mass, anisotropy factor, gravitational redshifts, energy conditions, and stability analysis by utilizing graphs. This made sure that our suggested solutions behave as expected and represent physically plausible models for anisotropic matter distributions. We consider compact stars to compare our model with observational data: SAX J1808.4-3658, Her X-1, 4U 1608-52, PSR B1913 16, Cen X-3, LMC X-4, PSR J1614-2230, 4U1538-52, PSR J1903 327, SMC X-1, 4U 1820-30, Vela X-1. [ABSTRACT FROM AUTHOR]

We demonstrate a new anisotropic solution to the Einstein field equations in Finch–Skea space-time. The physical features of a stellar configuration have been studied in previous investigations. We create a model that meets all physical plausibility conditions for a variety of stars and plot graphs for 4U 1820-30. [ABSTRACT FROM AUTHOR]

Semiclassical Einstein equations are used to describe the interaction of the back-reaction of the classical gravitational field with quantum matter fields in semiclassical gravity. We in our previous studies have made use of the semiclassical approximation to demonstrate the phenomenon of particle production, commonly called as preheating/reheating of the universe, which occurs after the inflationary epoch during the oscillatory phase of two-mode quantised massive scalar field of the chaotic inflationary model. We have previously used the language of two-mode coherent and squeezed quantum optical states formalisms to represent the massive scalar field; therefore, it would be useful to examine whether the field states exhibits classical or nonclassical nature in the cosmological context. In the present article, we will examine the nonclassical nature of two-mode quantum optical states in the cosmological context. We have made use of the criterion suggested by Lee in quantum optics, for the existence of nonclassical effects in two-mode states and calculated the equivalent Lee's D 12 (2) parameter with the associated cosmological parameters, to examine the nonclassical nature of the states after inflation during the oscillatory phase of the scalar field. [ABSTRACT FROM AUTHOR]

Semiclassical Einstein equations are used to describe the interaction of the back-reaction of the classical gravitational field with quantum matter fields in semiclassical gravity. We in our previous studies have made use of the semiclassical approximation to demonstrate the phenomenon of particle production, often called preheating/reheating of the universe, which occurs after the inflationary epoch during the oscillatory phase of two-mode quantized scalar field of chaotic inflationary model. During this oscillatory phase, back-reaction effects from the created particles, on account of the quantum nature of the states considered, could be significant and one might be concerned about the validity of the semiclassical approximation in these two-mode quantum optical states. The validity of the semiclassical approximation in these states is examined and it is presented how the magnitude of states parameter draws limit on the applicability and reliability of semiclassical theory of gravity. It is argued that semiclassical theory to gravity is a good approximation for states which are closer to coherent states i.e., with coherent parameters greater than unity and with squeezed parameter much smaller than unity. [ABSTRACT FROM AUTHOR]

We used coherent thermal and squeezed thermal vacuum states to represent the massive inflaton field in the semi-classical gravity; therefore, it would be useful to examine whether the field exhibits classical or nonclassical nature in the cosmological context. In the present article, we examine the non-classical nature of thermal quantum optical states in the cosmological context using Mandel's Q parameter. [ABSTRACT FROM AUTHOR]

Using single-mode squeezed and coherent thermal states formalism, we analyzed the validity of the semiclassical Einstein equation (SCEE) in the flat Friedmann–Robertson–Walker universe by analyzing the density fluctuations in terms of a massive inflaton. In a single-mode squeezed thermal states the density fluctuations are too large; consequently, the semiclassical theory of gravity (SCTG) does not hold good, for squeezing parameter greater than unity, i.e., r s > 1 ; however, the theory is valid when this related squeezing parameter is smaller than the unity, i.e., r s < < 1 and r s < 1 . Also, it is noted that the SCEE is dependable on coherent thermal state formalism. The current study provides a description of the density fluctuations as a result of the quantum and thermal effects in the SCTG. [ABSTRACT FROM AUTHOR]

By using single-mode squeezed thermal states prescription, we study the particle production due to thermal black hole. We analyze that thermal squeezing for a black hole can also be a possible mechanism in order to compute the variation of entropy and mass parameter. We also find a relation of Hawking's temperature with thermal squeezing parameter. [ABSTRACT FROM AUTHOR]

Fullerene-based bi-functional nanocomposite thin film (Ag nanoparticles embedded in fullerene C matrix) is synthesized by thermal co-deposition method. Thermal stability of Ag-C nanocomposite is investigated by annealing the nanocomposite thin film at different temperatures from 80 to 350 °C for 30 min. Optical and structural properties of nanocomposite thin film with respect to high temperature are studied by UV-visible spectroscopy and x-ray diffraction, respectively. Transmission electron microscopy is performed to observe the temperature-dependent size evolution of Ag nanoparticles in fullerene C matrix. A large growth of Ag nanoparticles is observed with temperature especially above 200 °C due to enhanced diffusion of Ag in fullerene C at higher temperature and Ostwald ripening. The properties of metal-fullerene nanocomposite is not significantly affected up to a temperature of 150 °C. With a further increase in temperature, a major blue shift of ~ 33 nm in SPR wavelength is seen at a temperature of 300 °C due to the thermal induced structural transformation of fullerene C matrix into amorphous carbon. A very large-sized Ag nanoparticle with a wide size distribution varying from 27.8 ± 0.6 to 330.0 ± 4.5 nm is seen at 350 °C and due to which, a red shift of ~ 16 nm is obtained at this temperature. This study throws light on the thermal stability of the devices based on metal-fullerene bi-functional nanocomposite. [ABSTRACT FROM AUTHOR]

We study the two-mode thermal squeezed states formalism to examine the particle creation by black holes.We also study the entropy generation and derive an equation for Hawking temperature in terms of squeezed parameter and an associated temperature dependent parameters. [ABSTRACT FROM AUTHOR]

The free standing and dimensionally stable gel polymer electrolyte films of polyacrylonitrile (PAN): potassium iodide (KI) of different compositions, using ethylene carbonate as a plasticizer and dimethyl formamide as solvent, are prepared by adopting 'solution casting technique' and these films are examined for their conductivities. The structural, miscibility and the chemical rapport between PAN and KI are investigated using X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry methods. The conductivity is enhanced with the increase in KI concentration and temperature. The maximum conductivity at 30°C is found to be 2.089 × 10 S cm for PAN:KI (70:30) wt%, which is nine orders greater than that of pure PAN (< 10 S cm). The conductivity-temperature dependence of these polymer electrolyte films obeys Arrhenius behaviour with activation energy ranging from 0.358 to 0.478 eV. The conducting carriers of charge transport in these polymer electrolyte films are identified by Wagner's polarization technique and it is found that the charge transport is predominantly due to ions. The better conducting sample is used to fabricate the battery with configuration K/PAN + KI/I+ C + electrolyte and good discharge characteristics of battery are observed. [ABSTRACT FROM AUTHOR]

The anatomy of the mature embryo and 34-day old seedling of Picea smithiana (Wall) Boiss. has been described. The organization of the shoot and root apices in both is similar. The shoot apex shows five cytohistological zones, where the entire surface layer shows periclinal divisions and a small subapical initials zone. In the radicular and root apices there is a common initiating zone for the stele and columella in the centre surrounded by another common initiating zone for the cortex and peripheral region of the root cap. In the mature embryo the kappe divisions of the protoderm resulting in the peripheral region of the cap can be noted, which, however, disappear in the root of the seedling. The 34-day old seedling shows a root-hypocotyl-cotyledon vasculature without any connection with the shoot, where no vasculature has yet developed. [ABSTRACT FROM AUTHOR]