Context Of Thermodynamics Research Articles

Correlative Activation Free Energy (CAFE) Model: Application to Viscous Processes in Inorganic Oxide Glass-Formers

We explore the concept of correlative activation free energy (CAFE) for the analysis and interpretation of viscosity data of a collection of 847 inorganic oxide glass formers that exhibit various degrees of non-Arrhenius behavior. The CAFE model formalism is strictly based on transition state theory and accounts for the variation in the activation barrier for the viscous dissipation due to the structural evolution the system undergoes upon traversing the glass transition regime. Thus, fitting parameters are meaningful in a statistical thermodynamic context. Compared to the VFT and MYEGA equations, fits using the CAFE model are more robust when extrapolating to infinite temperature because the latter encodes non-enthalpic contributions to the rate coefficient more realistically. The CAFE model-based analysis reveals a strong connection between melt fragility and the degree of change in the potential energy landscape with temperature. Accordingly, while the average ground-state potential energy of the glass forming liquid gradually increases with temperature, the energy of the activated state remains relatively invariant. Our analysis also allows one to estimate the number of atoms involved in the viscous relaxation process, which ranges from approximately 10 to 50 atoms for the oxide glass formers studied. We observe that thermally activated dynamic phenomena exhibited by glassy networks, such as the mixed alkali effect, persist into the supercooled liquid state.

Generalized Itô’s lemma and the stochastic thermodynamics of diffusion with resetting

Abstract Methods from the theory of stochastic processes are increasingly being used to extend classical thermodynamics to mesoscopic non-equilibrium systems. One characteristic feature of these systems is that averaging the stochastic entropy with respect to an ensemble of stochastic trajectories leads to a second law of thermodynamics that quantifies the degree of departure from thermodynamic equilibrium. A well known mechanism for maintaining a diffusing particle out of thermodynamic equilibrium is stochastic resetting. In its simplest form, the position of the particle instantaneously resets to a fixed position x 0 at a sequence of times generated from a Poisson process of constant rate r. Within the context of stochastic thermodynamics, instantaneous resetting to a single point is a unidirectional process that has no time-reversed equivalent. Hence, the average rate of entropy production calculated using the Gibbs–Shannon entropy cannot be related to the degree of time-reversal symmetry breaking. The problem of unidirectionality can be avoided by considering resetting to a random position or diffusion in an intermittent confining potential. In this paper we show how stochastic entropy production along sample paths of diffusion processes with resetting can be analyzed in terms of extensions of Itô’s formula for stochastic differential equations (SDEs) that include both continuous and discrete processes. First, we use the stochastic calculus of jump-diffusion processes to calculate the rate of stochastic entropy production for instantaneous resetting, and show how previous results are recovered upon averaging over sample trajectories. Second, we formulate single-particle diffusion in a switching potential as a hybrid SDE and develop a hybrid extension of Itô’s stochastic calculus to derive a general expression for the rate of stochastic entropy production. We illustrate the theory by considering overdamped Brownian motion in an intermittent harmonic potential. Finally, we calculate the average rate of entropy production for a population of non-interacting Brownian particles moving in a common switching potential. In particular, we show that the latter induces statistical correlations between the particles, which means that the total entropy is not given by the sum of the 1-particle entropies.

The theory of thermodynamic relativity.

We introduce the theory of thermodynamic relativity, a unified theoretical framework for describing both entropies and velocities, and their respective physical disciplines of thermodynamics and kinematics, which share a surprisingly identical description with relativity. This is the first study to generalize relativity in a thermodynamic context, leading naturally to anisotropic and nonlinear adaptations of relativity; thermodynamic relativity constitutes a new path of generalization, as compared to the "traditional" passage from special to general theory based on curved spacetime. We show that entropy and velocity are characterized by three identical postulates, which provide the basis of a broader framework of relativity: (1) no privileged reference frame with zero value; (2) existence of an invariant and fixed value for all reference frames; and (3) existence of stationarity. The postulates lead to a unique way of addition for entropies and for velocities, called kappa-addition. We develop a systematic method of constructing a generalized framework of the theory of relativity, based on the kappa-addition formulation, which is fully consistent with both thermodynamics and kinematics. We call this novel and unified theoretical framework for simultaneously describing entropy and velocity "thermodynamic relativity". From the generality of the kappa-addition formulation, we focus on the cases corresponding to linear adaptations of special relativity. Then, we show how the developed thermodynamic relativity leads to the addition of entropies in nonextensive thermodynamics and the addition of velocities in Einstein's isotropic special relativity, as in two extreme cases, while intermediate cases correspond to a possible anisotropic adaptation of relativity. Using thermodynamic relativity for velocities, we start from the kappa-addition of velocities and construct the basic formulations of the linear anisotropic special relativity; e.g., the asymmetric Lorentz transformation, the nondiagonal metric, and the energy-momentum-velocity relationships. Then, we discuss the physical consequences of the possible anisotropy in known relativistic effects, such as, (i) matter-antimatter asymmetry, (ii) time dilation, and (iii) Doppler effect, and show how these might be used to detect and quantify a potential anisotropy.

Effects of particle creation rate in two-fluid interacting cosmologies

ABSTRACT In this work, a two-fluid interacting model in a flat FLRW universe has been studied considering particle creation mechanism with a particular form of particle creation rate $\Gamma =\Gamma _0 H+\frac{\Gamma _1}{H}$ from different aspects. Statistical analysis with a combined data set of SNe Ia (Supernovae Type Ia) and Hubble data is performed to achieve the best-fitting values of the model parameters, and the model is compatible with current observational data. We also perform a dynamical analysis of this model to get an overall qualitative description of the cosmological evolution by converting the governing equations into a system of ordinary differential equations considering a proper transformation of variables. We find some non-isolated sets of critical points, among which some usually are normally hyperbolic sets of points that describe the present acceleration of the universe dominated by dark energy mimicking cosmological constant or phantom fluid. Scaling solutions are also obtained from this analysis, and they can alleviate the coincidence problem successfully. Statefinder diagnosis is also carried out for this model to compare it with the ΛCDM, and any other dark energy models byfinding various statefinder parameters. Finally, the thermodynamic analysis shows that the generalized second law of thermodynamics is valid in an irreversible thermodynamic context.

Ruppeiner geometry and the fluctuation of the RN-AdS black hole in framework of the extensive thermodynamics

In this study, the Ruppeiner geometry and fluctuations of a four-dimensional charged Anti-de Sitter (AdS) black hole within the context of extensive thermodynamics have been investigated. By fixing the AdS radius in Vissers' construction, an extensive thermodynamics description of the RN-AdS black hole is established, with the central charge playing the role of the particle number, introducing the concept of a subsystem into black hole thermodynamics. By employing the density of thermodynamic variables, the phase transition of the black hole is reexamined, and this result holds for black holes with different AdS backgrounds. Furthermore, the authors delve into a detailed analysis of the Ruppeiner geometry using fluctuation theory. Interestingly, an increase in the particle number of the smaller subsystem is found to induce a reduction in the thermodynamic curvature scalar.

Analytical approximation of optimal thermoeconomic efficiencies for a Novikov engine with a Stefan–Boltzmann heat transfer law

From a semi-analytical method, analytical expressions for the optimal thermoeconomic efficiencies are found for a Novikov model using a radiative heat transfer law. All this is within the context of finite-time thermodynamics for the three modes of operation: maximum power, ecological regime, and efficient power regime. The analysis includes fuel-related costs and operation and maintenance costs of the power plants that can be studied from the model considered. The obtained expressions are a reasonable approximation compared with the optimum efficiencies numerical results.

Protein Stability─Analysis of Heat and Cold Denaturation without and with Unfolding Models.

Protein stability is important in many areas of life sciences. Thermal protein unfolding is investigated extensively with various spectroscopic techniques. The extraction of thermodynamic properties from these measurements requires the application of models. Differential scanning calorimetry (DSC) is less common, but is unique as it measures directly a thermodynamic property, that is, the heat capacity Cp(T). The analysis of Cp(T) is usually performed with the chemical equilibrium two-state model. This is not necessary and leads to incorrect thermodynamic consequences. Here we demonstrate a straightforward model-independent evaluation of heat capacity experiments in terms of protein unfolding enthalpy ΔH(T), entropy ΔS(T), and free energy ΔG(T)). This now allows the comparison of the experimental thermodynamic data with the predictions of different models. We critically examined the standard chemical equilibrium two-state model, which predicts a positive free energy for the native protein, and diverges distinctly from the experimental temperature profiles. We propose two new models which are equally applicable to spectroscopy and calorimetry. The ΘU(T)-weighted chemical equilibrium model and the statistical-mechanical two-state model provide excellent fits of the experimental data. They predict sigmoidal temperature profiles for enthalpy and entropy, and a trapezoidal temperature profile for the free energy. This is illustrated with experimental examples for heat and cold denaturation of lysozyme and β-lactoglobulin. We then show that the free energy is not a good criterion to judge protein stability. More useful parameters are discussed, including protein cooperativity. The new parameters are embedded in a well-defined thermodynamic context and are amenable to molecular dynamics calculations.

Entropy, Ecology and Evolution: Toward a Unified Philosophy of Biology.

Darwin proposed that the capacity of organisms to produce more offspring that can be supported by the environment would lead to a struggle for existence, and individuals that are most fit for survival and reproduction would be selected through natural selection. Ecology is the science that studies the interaction between organisms and their environment within the context of Darwinian evolution, and an ecosystem is defined as a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. One topic that has been very much understudied and largely ignored in evolutionary biology is the overarching context of thermodynamics in controlling all biological processes and the evolution of life. Most fundamentally, organisms are self-replicating dissipative structures. Evolution is the process whereby variation in the structure of organisms have differential fitness in terms of their effectiveness at building and maintaining their structure, efficiently consuming free energy, and effectively reproducing and passing on those heritable variations, leading to change in the frequency of genetic variation and associated change in the characteristics in the population. The central process is dissipation of free energy according to the second law of thermodynamics, and evolution therefore is better conceptualized as the emergence of self-replicating dissipative structures that through natural selection become increasingly more efficient at degrading free energy. Ecosystems are linked series of dissipative structures with heat engine dynamics driven by random dissipation of energy and increasing entropy. The structure and composition of ecosystems across scales are emergent dissipative structures driven by the flow of energy and the increase in entropy. Communities and ecosystems are emergent properties of a system that has evolved to most efficiently dissipate energy and increase entropy. By focusing on the fundamental entity (energy), and the fundamental process (dissipation and disordering of energy and increasing of entropy), we are able to have a much clearer and powerful understanding of what life is, from the level of biochemistry, to evolution, to the nature of the organism itself, and to the emergent structures of ecosystems, food webs and communities.

Thermo-economic optimization of irreversible Novikov power plant models including a proposal of dissipation cost

The main component of the cost–benefit ratio of the electricity generation market relates to the finite energy capacity of macroscopic systems to perform conversion processes. Within the context of Finite-Time Thermodynamics (FTT), we aim to introduce an economic feature analysis of a non-endoreversible power plant model, the so-called Chambadal–Novikov model. We emulate the irreversible energy conversion processes of real-world power plants via the non-endoreversibility parameter (R) and heat transfer laws such as the Newtonian, Dulong–Petit and Stefan–Boltzmann. We find a connection between two maximum economic-energetic optimization criteria: The power output and the generalized ecological one with the economic Π function. Furthermore, we show that the maximum power output regime can be considered as a short-term recovery regime; however, it produces considerably more dissipated energy towards the atmosphere. With the help of these economic regimes, we introduce a proposal of “dissipation cost” through the total running cost function, and it can lead us to propose an ecological tariff expressed as the difference between the ratio of the capitalization of fuel consumption cost and incomes.

Energetic optimization and local stability of heliothermal plant models under three thermo-economic performance regimes

Solar power plants have the advantage of not producing greenhouse gases into the atmosphere. In their operation, some design and construction parameters can be identified for improving their performance. In this work within the context of Finite-Time Thermodynamics (FTT), we analyze a Müser–Curzon–Ahlborn heat engine model by maximizing economic-objective functions which not only provide optimal operation modes, but also they can reduce the energy dissipated in the form of heat towards the atmosphere. In our thermo-economic study we take into account both investment as well as operation and maintenance (O&M) costs. From operation data of three commercial tower-power plants: Eurelios, Gemasolar and Ivanpah, we find optimal values of solar concentration (Ci) for each economic-operation regime, accounting for the effect of internal irreversibilities (through a lumped parameter R). The Ci-values that we found are in the range of current reported values for the three power plants aforementioned. Besides, we present a local stability analysis for the three aforementioned solar plants and we show that for large size plants, disturbed isothermal branches return faster to their respective steady states, in less dissipative regimes, (e.g. the ecological regime).

On geometry of multiscale mass action law and its fluctuations

The classical mass action law in chemical kinetics is put into the context of geometric multiscale thermodynamics, which allows for description of chemical reactions with inertial effects. The kinetics is extended to an enlarged state space with reaction rates as new state variables, and it has the structure a Lie-algebroid dual. Subsequently, the dynamics is lifted to the Liouville description within kinetic theory of the enlarged state space, so that we can include also dynamics of fluctuations. The lifted kinematics has the geometric structure of a matched pair, which allows for reduction to moments by a Lie-algebra homomorphism, as in the Grad hierarchy. In particular, the first and second moments then lead to evolution equations for chemical kinetics with inertia and for correlations between composition and reaction rates. Finally, dissipation is added in the extended state space which leads to the classical mass action law when the moments relax to their respective quasi-equilibria. We demonstrate, for instance, the possibility of oscillating homogeneous chemical reactions, and how correlations between composition and reaction rates contribute to the chemical kinetics.

Optimization Criteria and Efficiency of a Thermoelectric Generator.

The efficiency of a thermoelectric generator model under maximum conditions is presented for two optimization criteria proposed under the context of finite-time thermodynamics, namely, the efficient power criterion and the Omega function, where this last function represents a trade-off between useful and lost energy. The results are compared with the performance of the device at maximum power output. A macroscopic thermoelectric generator (TEG) model with three possible sources of irreversibilities is considered: (i) the electric resistance R for the Joule heating, (ii) the thermal conductances Kh and Kc of the heat exchangers between the thermal baths and the TEG, and (iii) the internal thermal conductance K for heat leakage. In particular, two configurations of the macroscopic TEG are studied: the so-called exoreversible case and the endoreversible limit. It shows that for both TEG configurations, the efficiency at maximum Omega function is always greater than that obtained in conditions of maximum efficient power, and this in turn is greater than that of the maximum power regime.

Classicality of the heat produced by quantum measurements

Quantum measurement is ultimately a physical process, resulting from an interaction between the measured system and a measuring apparatus. Considering the physical process of measurement within a thermodynamic context naturally raises the following question: How can the work and heat be interpreted? In the present paper we model the measurement process for an arbitrary discrete observable as a measurement scheme. Here the system to be measured is first unitarily coupled with an apparatus and subsequently the compound system is objectified with respect to a pointer observable, thus producing definite measurement outcomes. The work can therefore be interpreted as the change in internal energy of the compound system due to the unitary coupling. By the first law of thermodynamics, the heat is the subsequent change in internal energy of this compound due to pointer objectification. We argue that the apparatus serves as a stable record for the measurement outcomes only if the pointer observable commutes with the Hamiltonian and show that such commutativity implies that the uncertainty of heat will necessarily be classical.

High-throughput nitride and interstitial nitrogen analysis in ferritic/martensitic steels via time-of-flight secondary ion mass spectrometry

The following work focuses on characterizing nitrogen in several modified alloys of the precipitation strengthened ferritic/martensitic steel HT9 (12Cr-1MoWV (wt%)). Alloy HT9 is a candidate material for fuel rod cladding and ductwork in the core of the Versatile Test Reactor and other next-generation nuclear fast reactors. Nitrogen content has been shown to have a significant effect on irradiated properties in alloy HT9. To explore that theory, a more comprehensive assessment of the location of nitrogen must be performed; however, locating nano-precipitates, such as nitrides and light interstitial elements like nitrogen in steel, has proven difficult. To begin answering questions surrounding the location of nitrogen, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) was employed as a primary analysis technique, together with extensive transmission electron microscopy, internal friction testing, and thermodynamic simulations, providing verification and context to trends found in the ToF-SIMS data. For the first time, ToF-SIMS was demonstrated to reliably measure relative differences in the vanadium carbonitride precipitate volume fraction across several chemistries and heat treatments of ferritic/martensitic steels. Additionally, associating matrix elements (iron and chromium) to nitrogen-containing ion clusters significantly reduced the ‘matrix effect that biases nitrogen detection towards nitride precipitates, providing a potential, high-throughput method for the measurement of relative interstitial nitrogen content in steels with ToF-SIMS. • ToF-SIMS provided a new high-throughput analysis method for microalloy precipitate and microstructure design. • ToF-SIMS was employed for semi-quantitative, bulk detection and measurement of nitrides and interstitial nitrogen in steel. • S/TEM provided a quantitative comparison of nitride content, while internal friction testing provided a semi-quantitative comparison of interstitial N.

Black hole thermodynamics in the presence of nonlinear electromagnetic fields

As the interaction between the black holes and highly energetic infalling charged matter receives quantum corrections, the basic laws of black hole mechanics have to be carefully rederived. Using the covariant phase space formalism, we generalize the first law of black hole mechanics, both "equilibrium state" and "physical process" versions, in the presence of nonlinear electrodynamics fields, defined by Lagrangians depending on both quadratic electromagnetic invariants, $F_{ab}F^{ab}$ and $F_{ab}\,{\star F}^{ab}$. Derivation of this law demands a specific treatment of the Lagrangian parameters, similar to embedding of the cosmological constant into thermodynamic context. Furthermore, we discuss the validity of energy conditions, several complementing proofs of the zeroth law of black hole electrodynamics and some aspects of the recently generalized Smarr formula, its (non-)linearity and relation to the first law.

The Sabatier Principle in Electrocatalysis: Basics, Limitations, and Extensions

The Sabatier principle, which states that the binding energy between the catalyst and the reactant should be neither too strong nor too weak, has been widely used as the key criterion in designing and screening electrocatalytic materials necessary to promote the sustainability of our society. The widespread success of density functional theory (DFT) has made binding energy calculations a routine practice, turning the Sabatier principle from an empirical principle into a quantitative predictive tool. Given its importance in electrocatalysis, we have attempted to introduce the reader to the fundamental concepts of the Sabatier principle with a highlight on the limitations and challenges in its current thermodynamic context. The Sabatier principle is situated at the heart of catalyst development, and moving beyond its current thermodynamic framework is expected to promote the identification of next-generation electrocatalysts.

Local and global stability analysis of a Curzon–Ahlborn model applied to power plants working at maximum [formula omitted]-efficient power

The analysis of the effect of noisy perturbations on real heat engines working on the well-known steady-state regimes (maximum power output, maximum efficient power, etc.), has been a topic of interest within the context of Finite-Time Thermodynamics (FTT). In general, the small perturbation stability dynamics has been studied by considering some of the above-mentioned performance regimes. In this work, we intrinsically corroborate that the concepts of thermodynamic optimization and stability are not uncorrelated. On the other side, due to global stability dynamics opened an extension for the general study of thermal disturbances in endoreversible heat engines, we present a study of local and global stability analysis of a power plant model (the Curzon–Ahlborn model) operating on a generalized performance regime called k-efficient power. We also construct the Lyapunov functions to prove the global asymptotically stable behavior of this steady-state for the isothermal branches. In our study, we consider a Newtonian heat transfer law as well as the role of the k parameter in the evolution of perturbations to the heat fluxes. In general, the so-called restructured operation conditions show a better thermal stability dynamics than the original ones.

Deciphering Reaction Determinants of Altered-Activity CYP2D6 Variants by Well-Tempered Metadynamics Simulation and QM/MM Calculations.

The xenobiotic metabolizing enzyme CYP2D6 is the P450 cytochrome family member with the highest rate of polymorphism. This causes changes in the enzyme activity and specificity, which can ultimately lead to adverse reactions during drug treatment. To avoid or lower CYP-related toxicity risks, prediction of the most likely positions within a molecule where a metabolic reaction might occur is paramount. In order to obtain accurate predictions, it is crucial to understand all phenomena within the active site of the enzyme that contribute to an efficient substrate recognition and the subsequent catalytic reaction together with their relative weight within the overall thermodynamic context. This study aims to define the weight of the driving forces upon the C-H bond activation within CYP2D6 wild-type and a clinically relevant allelic variant with increased activity (CYP2D6*53) featuring two amino acid mutations in close vicinity of the heme. First, we investigated the steric and electrostatic complementarity of the substrate bufuralol using well-tempered metadynamics simulations with the aim to obtain the free energy profiles for each site of metabolism (SoM) within the different active sites. Second, the stereoelectronic complementarity was determined for each SoM within the two different active-site environments. Relying on the well-tempered metadynamics simulation energy profiles of each SoM, we identified the binding mode that was closest to the preferred transition-state geometry for efficient C-H bond activation. The binding modes were then used as starting structures for the quantum mechanics/molecular mechanics calculations performed to quantify the corresponding activation barriers. Our results show the relevance of the steric component in orienting the SoM in an energetically accessible position toward the heme. However, the corresponding intrinsic reactivity and electronic complementarity within the active site must be accurately evaluated in order to obtain a meaningful reaction prediction, from which the predominant SoM can be determined. The F120I mutation lowered the activation barrier for the major site and one of the minor SoMs. However, it had an impact neither on the CYP2D6 enantioselectivity preference of the oxidation reaction nor on the stereoselectivity from the substrate point of view.

Dynamic and Renormalization-Group Extensions of the Landau Theory of Critical Phenomena.

We place the Landau theory of critical phenomena into the larger context of multiscale thermodynamics. The thermodynamic potentials, with which the Landau theory begins, arise as Lyapunov like functions in the investigation of the relations among different levels of description. By seeing the renormalization-group approach to critical phenomena as inseparability of levels in the critical point, we can adopt the renormalization-group viewpoint into the Landau theory and by doing it bring its predictions closer to results of experimental observations.

A thermodynamic description of the glass state and the glass transition

Many properties of solids, such as the glass state, hysteresis, and memory effects, are commonly treated as nonequilibrium phenomena, which involve numerous conceptual difficulties. However, few studies have addressed the problem of understanding equilibrium itself. Equilibrium is often assessed based on the assumption that its thermodynamic state should be solely determined using temperature and pressure. However, this assumption must be fundamentally reappraised from the beginning because no rigorous proof for this assumption exists. Previous work showed that for solids, the time-averaged positions of all constituent atoms of the solid are thermodynamic coordinates (TCs). In this study, this conclusion is further elaborated starting from the principles of solid-state physics. This theory is applied to glass materials, for which many challenges remain. Results show that first, the glass state, which is the state after freezing, is an equilibrium state under given constraints. Accordingly, the properties of a glass can be solely described using the present time-averaged atom positions, irrespective of their history, which is consistent with the definition of a state in the thermodynamic context. Any quantity that is determined using TCs can be used as an order parameter. Second, although the traditional view that the transition state during the glass transition is a nonequilibrium state is correct, whether it reaches the supercooled-liquid state given sufficient time is highly questionable. The final state must be an inhomogeneous mixture of solid and liquid phases. In the liquid phase, the atom positions are missing from the set of TCs. The degeneration of the state space occurs, which corresponds to an increase in configuration entropy. Conversely, when the phonon and structural parts of the atom positions are well separated, the time-averaged atom positions in the solid part remain as TCs. In this manner, the transition state can be described using a reduced set of TCs as a function of time. An important outcome of this theory is that the hysteresis of the glass transition can be described using the present values of TCs through the structural-dependent energy barrier. Complicated response functions describing the history, which are widely used in glass literature, are unnecessary. The expense of this simplification is that, in a rigorous sense, all the atom positions are needed for TCs. However, in most cases, only a few TCs are sufficient to describe the transition state, if these TCs are suitably chosen.