Articles publicats (Química, Física, Ciències Ambientals i del Sòl)
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- ItemOpen AccessEvolution of soil porosity in loess-palaeosol sequences of the Ebro Valley, NE Iberia(Elsevier, 2023) Torres guerrero , Carlos Alberto; Álvarez Morales, D.; Preusser, F.; Olarieta, José Ramón; Poch, Rosa M.Structure development and porosity evolution are closely related key processes in the formation of soils on loess. In order to better understand changes in soil porosity with time, four loess-palaeosol sequences (LPS) of the Ebro Valley were investigated using micromorphological and multiscalar images of soil thin sections combined with luminescence dating. Scanned and high-resolution mosaic images of thin sections using circular polarized light and backscattered electron scanning images were used to characterize the structural and textural porosity. The results were compared with physical and chemical analyses, and detailed micromorphological descriptions. The main results of our research revealed that 1) the change in loess particle packing, from enaulic to porphyric coarse/fine (c/f) related distribution, is the first process giving cohesion to the loess material and 2) that soil development during stabilization periods is associated with higher bioporosity. Gypsum accumulation is also a relevant process contributing to the increase of packing porosity within channels and chambers in the studied soils. Our results provide new insights into soil formation processes in Mediterranean loess and open new fields of research such as the possibility of using the quantification of bioporosity as an additional palaeoenvironmental marker.
- ItemOpen AccessGeneralized interacting Barrow Holographic Dark Energy: Cosmological predictions and thermodynamic considerations(Elsevier, 2023) Luciano, Giuseppe Gaetano; Giné, JaumeWe construct a generalized interacting model of Barrow Holographic Dark Energy (BHDE) with infrared cutoff being given by the Hubble horizon. We analyze the cosmological evolution of a flat Friedmann–Lemaître–Robertson–Walker Universe filled by pressureless dark matter, BHDE and radiation fluid. The interaction between the dark sectors of the cosmos is assumed of non-gravitational origin and satisfying both the second law of thermodynamics and Le Chatelier–Braun principle. We study the behavior of various model parameters, such as the BHDE density parameter, the equation of state parameter, the deceleration parameter, the jerk parameter and the square of sound speed. We also investigate cosmological perturbations in the linear regime on sub-horizon scales, studying the growth rate of matter fluctuations for clustering dark matter and a homogeneous dark energy component. We show that our model satisfactorily retraces the thermal history of the Universe and is consistent with current observations for certain values of model parameters, providing an eligible candidate to describe dark energy. We finally explore the thermodynamics of our framework, with special focus on the validity of the generalized second law.
- ItemOpen AccessConstraining barrow entropy-based cosmology with power-law inflation(Springer, 2023) Luciano, Giuseppe GaetanoWe study the inflationary era of the Universe in a modified cosmological scenario based on the gravity-thermodynamics conjecture with Barrow entropy instead of the usual Bekenstein–Hawking one. The former arises from the effort to account for quantum gravitational effects on the horizon surface of black holes and, in a broader sense, of the Universe. First, we extract modified Friedmann equations from the first law of thermodynamics applied to the apparent horizon of a Friedmann–Robertson–Walker Universe. Assuming a power-law behavior for the scalar inflaton field, we then investigate how the inflationary dynamics is affected in Barrow cosmological setup. We find that the inflationary era may phenomenologically consist of the slow-roll phase, while Barrow entropy is incompatible with kinetic inflation. By demanding observational consistency of the scalar spectral index and tensor-to-scalar ratio with recent Planck data, we finally constrain Barrow exponent to Δ≲O(10−4), which is the most stringent bound in so-far literature.
- ItemOpen AccessGeneralized Heisenberg Uncertainty Principle due to the quantum gravitational effects in the Schwarzschild spacetime(Elsevier, 2023) Chemisana Villegas, Daniel; Giné, Jaume; Madrid, JaimeIn non-relativistic quantum mechanics, the Heisenberg Uncertainty Principle states a fundamental limit to the accuracy in the measurement of pairs of conjugate variables, such as position and momentum. Based on a semiclassical geometric approach, it has been recently proposed a generalization of the uncertainty principle under the relativistic case, which could be extended to General Relativity. This formalism was applied to the Schwarzschild and de Sitter spacetime, showing that the uncertainty relations obtained can be mapped into deformations of Generalized Heisenberg principles well-known in the literature and obtained from the different models of quantum gravity proposed. In the present study, the generalized Heisenberg Principle is derived from the commutator relation, and has been applied to the classical gravitational tests and the derived consequences are framed and analyzed.
- ItemOpen AccessSaez–Ballester gravity in Kantowski–Sachs Universe: A new reconstruction paradigm for Barrow Holographic Dark Energy(Elsevier, 2023) Luciano, Giuseppe GaetanoWe reconstruct Barrow Holographic Dark Energy (BHDE) within the framework of Saez–Ballester Scalar Tensor Theory. As a specific background, we consider a homogeneous and anisotropic Kantowski–Sachs Universe filled up with BHDE and dark matter. By assuming the Hubble radius as an IR cutoff, we investigate both the cases of non-interacting and interacting dark energy scenarios. We analyze the evolutionary behavior of various model parameters, such as skewness parameter, Equation-of-State parameter, deceleration parameter, jerk parameter and squared sound speed. We also draw the trajectories of ωD − ω′ D phase plane and examine statefinder diagnosis. Observational consistency is discussed by inferring the current value of Hubble’s parameter through the best fit curve of data points from Differential Age (DA) and Baryon Acoustic Oscillations (BAO) and commenting on cosmological perturbations and growth rate of matter fluctuations in BHDE. We show that our model satisfactorily retraces the history of the Universe, thus providing a potential candidate explanation for dark energy. Comparison with other reconstructions of BHDE is finally analyzed.