Examinando por Autor "Hochberg, D."

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Restringido
Does Pressure Break Mirror‐Image Symmetry? A Perspective and New Insights.
(Chemistry Europe: European Chemical Societies Publishing, 2020-01-03) Hochberg, D.; Cintas, P.; European Development Regional Fund (ERDF); Agencia Estatal de Investigación (AEI); 0000-0002-2608-3604; 0000-0002-0411-019X; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
This paper is aimed at dissecting and discussing the effect of high pressure on chirogenesis, thus unveiling the role of this universal force in astrochemical and primeval Darwinian scenarios. The first part of this contribution revisits the current status and recent experiments, most dealing with crystalline racemates, for which generation of metastable conglomeratic phases would eventually afford spontaneous resolution and hence enantioenriched mixtures. We then provide an in‐depth thermodynamic analysis, based on previous studies of non‐electrolyte solutions and dense mixtures accounting for the existence of positive excess volume upon mixing, to simulate the mirror symmetry breaking, the evolution of entropy production and dissipation due to enantiomer conversion. Results clearly suggest that mirror symmetry breaking under high pressure may be a genuine phenomenon and that enantioenrichment from initial scalemic mixtures may also take place.
Acceso Abierto
Entropic analysis of bistability and the general evolution criterion
(Royal Society of Chemistry, 2021-06-01) Hochberg, D.; Ribó, J. M.; Agencia Estatal de Investigación (AEI), MINEC; Hochberg, D. [0000-0002-0411-019X]; Ribó, J. M. [0000-0001-6258-1726]
We present a detailed study of the entropy production, the entropy exchange and the entropy balance for the Schlögl model of chemical bi-stability for both the clamped and volumetric open-flow versions. The general evolution criterion (GEC) is validated for the transitions from the unstable to the stable non-equilibrium stationary states. The GEC is the sole theorem governing the temporal behavior of the entropy production in non-equilibrium thermodynamics, and we find no evidence for supporting a “principle” of maximum entropy production. We use stoichiometric network analysis (SNA) to calculate the distribution of the entropy production and the exchange entropy over the elementary flux modes of the clamped and open-flow models, and aim to reveal the underlying mechanisms of dissipation and entropy exchange.
Restringido
Spontaneous mirror symmetry breaking: an entropy production survey of the racemate instability and the emergence of stable scalemic stationary states.
(Royal Society of Chemistry, 2020-06-08) Ribo, J. M.; Hochberg, D.; Agencia Estatal de Investigación (AEI); Ribó, J. M. [0000-0001-6258-1726]; Hochberg, D. [0000-0002-0411-019X]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We study the emergence of both stable and unstable non-equilibrium stationary states (NESS), as well as spontaneous mirror symmetry breaking (SMSB) provoked by the destabilization of the racemic thermodynamic branch, for an enantioselective autocatalytic reaction network in an open flow system, and for a continuous rangenof autocatalytic orders. The system possesses a range of double bi-stability and also tri-stability depending on the autocatalytic order. We carry out entropy production and entropy flow calculations, from simulations of ordinary differential equations, stoichiometric network analysis (SNA), and consider a stability analysis of the NESS. The simulations provide a correct description of the relationship between energy state functions, the isothermal dissipated heat, entropy production and entropy flow exchange with the surroundings, and the correct solution of the balance of the entropy currents at the NESS. The validity of the General Evolution Criterion (GEC) is in full agreement with all the dynamic simulations.
Acceso Abierto
The Coordinate Reaction Model: An Obstacle to Interpreting the Emergence of Chemical Complexity
(Chemistry Europe: European Chemical Societies Publishing, 2021-07-14) Ribó, J. M.; Hochberg, D.; Agencia Estatal de Investigación (AEI); Ribó, J. M. [0000-0001-6258-1726]; Hochberg, D. [0000-0002-0411-019X]
The way chemical transformations are described by models based on microscopic reversibility does not take into account the irreversibility of natural processes, and therefore, in complex chemical networks working in open systems, misunderstandings may arise about the origin and causes of the stability of non-equilibrium stationary states, and general constraints on evolution in systems that are far from equilibrium. In order to be correctly simulated and understood, the chemical behavior of complex systems requires time-dependent models, otherwise the irreversibility of natural phenomena is overlooked. Micro reversible models based on the reaction-coordinate model are time invariant and are therefore unable to explain the evolution of open dissipative systems. The important points necessary for improving the modeling and simulations of complex chemical systems are: a) understanding the physical potential related to the entropy production rate, which is in general an inexact differential of a state function, and b) the interpretation and application of the so-called general evolution criterion (GEC), which is the general thermodynamic constraint for the evolution of dissipative chemical systems.