Thermodynamic Information Research Articles

The hydrate-based separation of hydrogen and ethylene from fluid catalytic cracking dry gas in presence of n-octyl-β-d-glucopyranoside

Hydrate-based gas separation (HBGS) needs a kinetic promoter to increase its economic value. The kinetic promoters for HBGS should have low foaming ability, high performance on increasing the conversion rate of the water into hydrate (RWH) and little thermodynamic inhibition on hydrate formation. However, no reported kinetic promoter meets all above requirements at same time. According to the experimental results in this work, n-octyl-β-d-glucopyranoside (OGP) met all those requirements of HBGS. For that reason, OGP was proposed as a new kinetic promoter for HBGS, and its effects on HBGS were revealed by investigating the HBGS of hydrogen and ethylene from fluid catalytic cracking dry gas in presence of OGP in this work. OGP enhanced the HBGS performance by increasing RWH from less than 64% to higher than 84%. By one-step separation, the hydrogen concentration was increased from 26.0 mol% to about 46.8 mol% while the ethylene concentration was increased from 52.0 mol% to about 74.4 mol%. The effect of the initial OGP concentration in liquid phase (wp,0) on HBGS increased with the increase in RWH, and the optimum wp,0 was 0.20 mass%. The processing capacity of the OGP solution in the HBGS was about 350 NL feed gas/L. OGP enhanced the promotion of increasing pressure on the HBGS performance. A new model was proposed to predict the thermodynamic equilibrium hydrate formation pressures of the experimental systems: the maximum relative deviation is 5.08% and the average relative deviation is 2.61%.

Uniqueness and stability of equilibrium states for random non-uniformly expanding maps

Abstract We consider a robust class of random non-uniformly expanding local homeomorphisms and Hölder continuous potentials with small variation. For each element of this class we develop the thermodynamical formalism and prove the existence and uniqueness of equilibrium states among non-uniformly expanding measures. Moreover, we show that these equilibrium states and the random topological pressure vary continuously in this setting.

Nonlinear thermodynamic formalism for flows

ABSTRACT We introduce a version of the nonlinear thermodynamic formalism for flows. Moreover, we discuss the existence, uniqueness, and characterization of equilibrium measures for almost additive families of continuous functions with tempered variation. We also consider with some care the special case of additive families for which it is possible to strengthen some of the results. The proofs are mainly based on multifractal analysis.

Phase equilibria of SiO2–Ce2O3–CaO-25 wt %Al2O3 system at 1673 K–1773 K

The utilization of rare earth resources, especially secondary resources (e.g., RE-oxide system slag), has been limited by the lack of thermodynamic information. In order to supplement and improve the thermodynamic data related to rare earth, the equilibrium experiments of SiO2–Ce2O3–CaO-25 wt %Al2O3 system phase diagram was carried out at 1673 K and 1773 K by the high-temperature isothermal equilibration/quenching technique in current paper. The composition of seven phase regions were determined by FE-SEM, XRD, EPMA and XRF analysis on the samples obtained by high temperature equilibrium technology at 1673 K and 1773 K, including the primary crystal regions of three compounds (C2AS, 2CaO·SiO2, CaO·2Ce2O3·3SiO2) and three three-phase coexistence regions (L + C2AS + 2CaO·SiO2, L + C2AS + CaO·2Ce2O3·3SiO2, L + CaO·2Ce2O3·3SiO2+CeAl11O18) and a liquid region. The phase relations and isotherms of SiO2–Ce2O3–CaO-25 wt %Al2O3 system obtained in current work are beneficial to the recycling of rare earth resources containing cerium.

Transition State Theory-Inspired Neural Network for Estimating the Viscosity of Deep Eutectic Solvents.

The lack of accurate methods for predicting the viscosity of solvent materials, especially those with complex interactions, remains unresolved. Deep eutectic solvents (DESs), an emerging class of green solvents, have a severe lack of viscosity data, resulting in their application still staying at the stage of random trial and error, and it is difficult for them to be implemented on an industrial scale. In this work, we demonstrate the successful prediction of the viscosity of DESs based on the transition state theory-inspired neural network (TSTiNet). The TSTiNet adopts multilayer perceptron (MLP) for the transition state theory-inspired equation (TSTiEq) parameters calculation and verification using the most comprehensive DESs viscosity data set to date. For the energy parameters of the TSTiEq, the constant assumption and the fast iteration with the help of MLP can allow TSTiNet to achieve the best performance (the average absolute relative deviation on the test set of 6.84% and R2 of 0.9805). Compared with the traditional machine learning methods, the TSTiNet has better generalization ability and dramatically reduces the maximum relative deviation of prediction under the constraints of the thermodynamic formulation. It requires only the structural information on DESs and is the most accurate and reliable model available for DESs viscosity prediction.

A Curvilinear-Path Umbrella Sampling Approach to Characterizing the Interactions Between Rapamycin and Three FKBP12 Variants.

Rapamycin is an immunosuppressant macrolide that exhibits anti-proliferative properties through inhibiting the mTOR kinase. In fact, the drug first associates with the FKBP12 enzyme before interacting with the FRB domain of its target. Despite the availability of structural and thermodynamic information on the interaction of FKBP12 with rapamycin, the energetic and mechanistic understanding of this process is still incomplete. We recently reported a multiple-walker umbrella sampling simulation approach to characterizing the protein–protein interaction energetics along curvilinear paths. In the present paper, we extend our investigations to a protein-small molecule duo, the FKBP12•rapamycin complex. We estimate the binding free energies of rapamycin with wild-type FKBP12 and two mutants in which a hydrogen bond has been removed, D37V and Y82F. Furthermore, the underlying mechanistic details are analyzed. The calculated standard free energies of binding agree well with the experimental data, and the roles of the hydrogen bonds are shown to be quite different for each of these two mutated residues. On one hand, removing the carboxylate group of D37 strongly destabilizes the association; on the other hand, the hydroxyl group of Y82 is nearly unnecessary for the stability of the complex because some nonconventional, cryptic, indirect interaction mechanisms seem to be at work.

Computation-Based Investigation of Motion and Dynamics of Lithium in Phase Separated Silicon-Oxide Anode Materials

Si attracts significant attention as an alternative anode material to replace the conventional graphite anode in lithium-ion batteries (LIBs). Si offers extremely high theoretical energy-storage capacity of 4200 mAh/g for Li4.4Si, while the theoretical energy-storage capacity of graphite is only 372 mAh/g for Li/C6. In addition, Si is abundant, eco-friendly, and non-toxic, and it also has a safe thermodynamic potential with an average voltage of about 0.4 V vs. Li+/Li, making them attractive candidates for LIB anodes. However, the capacity of the Si anode exhibits a relatively high initial charge capacity and then rapidly decreases as the charge/discharge cycle proceeds, hampering its extensive application. This rapid performance degradation can be attributed to the poor connection between the active material and the current collector resulting from the severe volume expansion and contraction of the Si particles during the repeated charge and discharge cycles, respectively.Controlled addition of O to Si is often taken as a viable approach to utilize Si as an anode material. Silicon suboxides (SiOx, 0 < x < 2), compared with Si, offer a low energy capacity but a high stability against volume expansion. As a result, silicon monoxide (SiO) anodes are indeed commercialized by being blended with graphite. However, only low amounts (about 5 wt%) of SiO are blended with graphite because of the poor first cycle efficiency of SiO. During the charge process, SiOx reacts with Li and produces in-situ byproducts such as Li2O and Li-silicates, which are irreversible in following discharge cycles. This irreversible Li consumption is known to decrease the initial Coulombic efficiency (ICE) of SiO, typically below 75%. The low ICE of SiOx along with its inherently poor electronic conductivity leads to poor rate performance and increased capacity decay, hindering its substantial application in LIBs. To realize more extensive application of SiOx for LIB anodes, physical properties of SiOx should be improved in a direction to mitigate the low ICE issue.In this study, we investigate the motion and dynamics of a Li atom in SiOx by performing a series of first principles-based atomistic simulations. To this end, we perform Monte Carlo simulations within a continuous random network model to generate realistic SiOx structures with varying O-to-Si ratios. Then, we implement a density-functional theory calculation-based path sampling scheme to obtain detailed thermodynamic information when a Li atom penetrates a SiO matrix. Subsequent electronic structure analysis reveals that the thermodynamic stability of a Li atom is determined by local Si-O network environment surrounding Li. The identified thermodynamic information regarding the Li dynamics in SiO provides additional insight into the origin and solutions of the low ICE, highlighting the importance of controlling the SiO morphology during the synthesis of SiO. This fundamental understanding can be an important theoretical basis for developing practically applicable high-ICE silicon suboxide-based anode materials. Figure 1

Some Old and New Problems in Thermodynamic Formalism of Infinite State Markov Chains

Some Old and New Problems in Thermodynamic Formalism of Infinite State Markov Chains

An analytical approach to the anomalous density of water

Water, which is essential for the existence of life, has almost a hundred properties that distinguish it from other liquids. In this paper, we will focus on its density, which, unlike the absolute majority of other liquids, increases with increasing temperature in the vicinity of the solid–liquid transition, for a wide range of pressures, including ambient pressure. Our approach will present an analytical thermodynamic formulation for this problem that has, as a novelty, the introduction of a variable exclusion volume. The excluded volume will be considered a thermodynamic variable, that is, it depends on the system's thermal conditions. This approach will be applied to the two-liquid theory of water, which claims that water molecules can be assembled into two different kinds of clusters. At a given state, the relative numbers of these aggregates can be very sensitive to thermal variations, and, as the excluded volume for each of them is different, when their relative number changes, the total excluded volume also changes. We will show how to gather the ideas of a non-constant excluded volume with the two-liquid theory of water into a new, elegant, and non-trivial analytical expression for the density of water. In the end, we compare our expression with experimental data and show that it provides an exact understanding of the anomalous behavior of water density.

The laws of thermodynamics for quantum dissipative systems: A quasi-equilibrium Helmholtz energy approach.

By using the quasi-equilibrium Helmholtz energy, which is defined as the thermodynamic work in a quasi-static process, we investigate the thermal properties of both an isothermal process and a transition process between the adiabatic and isothermal states (adiabatic transition). Here, the work is defined by the change in energy from a steady state to another state under a time-dependent perturbation. In particular, the work for a quasi-static change is regarded as thermodynamic work. We employ a system-bath model that involves time-dependent perturbations in both the system and the system-bath interaction. We conduct numerical experiments for a three-stroke heat machine (a Kelvin-Planck cycle). For this purpose, we employ the hierarchical equations of motion (HEOM) approach. These experiments involve an adiabatic transition field that describes the operation of an adiabatic wall between the system and the bath. Thermodynamic-work diagrams for external fields and their conjugate variables, similar to the P-V diagram, are introduced to analyze the work done for the system in the cycle. We find that the thermodynamic efficiency of this machine is zero because the field for the isothermal processes acts as a refrigerator, whereas that for the adiabatic wall acts as a heat engine. This is a numerical manifestation of the Kelvin-Planck statement, which states that it is impossible to derive the mechanical effects from a single heat source. These HEOM simulations serve as a rigorous test of thermodynamic formulations because the second law of thermodynamics is only valid when the work involved in the operation of the adiabatic wall is treated accurately.

Quantum scattering as a work source

We consider a collision between a moving particle and a fixed system, each having internal degrees of freedom. We identify the regime where the motion of the particle acts as a work source for the joint internal system, leading to energy changes which preserve the entropy. This regime arises when the particle has high kinetic energy and its quantum state of motion is broad in momentum and narrow in space, whether pure or mixed. In this case, the scattering map ruling the dynamics of the internal degrees of freedom becomes unitary and equivalent to that of a time-dependent interaction between the internal degrees of freedom of the colliding systems. It follows that the kinetic energy lost by the particle during the autonomous quantum collision coincides with the work performed by the time-dependent interaction. Recently, collisions with particles were shown to act as heat sources under suitable conditions; here we show that they can also act as work sources. This opens interesting perspectives for quantum thermodynamics formulations within scattering theory.

Microbial maintenance energy quantified and modeled with microcalorimetry

Refining the energetic costs of cellular maintenance is essential for predicting microbial growth and survival in the environment. Here, we evaluate a simple batch culture method to quantify energy partitioning between growth and maintenance using microcalorimetry and thermodynamic modeling. The constants derived from the batch culture system were comparable to those that have been reported from meta-analyses of data derived from chemostat studies. The model accurately predicted temperature-dependent biomass yield and the upper temperature limit of growth for Desulfovibrio alaskensis G20, suggesting the method may have broad application. An Arrhenius temperature dependence for the specific energy consumption rate, inferred from substrate consumption and heat evolution, was observed over the entire viable temperature range. By combining this relationship for specific energy consumption rates and observed specific growth rates, the model describes an increase in nongrowth associated maintenance at higher temperatures and the corresponding decrease in energy available for growth. This analytical and thermodynamic formulation suggests that simply monitoring heat evolution in batch culture could be a useful complement to the recognized limitations of estimating maintenance using extrapolation to zero growth in chemostats.

Biodiesel Production through Acid Catalyst In Situ Reactive Extraction of Chlorella vulgaris Foamate

A method of biodiesel production from the freshwater microalgae Chlorella vulgaris based on the conversion of the dewatered algal biomass from a foam column (“foamate”) was investigated. The foam column collected and concentrated the microalgae. The foam was generated by passing air through a pool of algae, to which a collector/surfactant cetyltrimethylammonium bromide (CTAB) had been added. To produce biodiesel, the resultant “foamate” was esterified in situ using sulfuric acid and methanol. The effect of reaction temperature (30–70 °C), reaction time (30–120 min) and methanol/oil molar ratio (100–1000), were examined in a single-stage extraction–transesterification experiment on biodiesel yield at concentration of the catalyst H2SO4/oil molar ratio of (8.5/1). The thermodynamics and kinetics of transesterification of the microalgae oil were also investigated. The maximum biodiesel yield (96 ± 0.2%) was obtained at a reaction temperature of 70 °C, a reaction time of 90 min and methanol/oil molar ratio of 1000/1. Reaction kinetic parameters were determined that fitted the experimental data at all temperatures. A reversible reaction with first order forward and second order backward kinetics were found to be a good match for the experimental results. The kinetic model fitted experiments well under various temperatures and methanol/oil mole ratios. Under the most suitable conditions of reaction temperature, reaction time and methanol/oil molar ratio, the apparent activation energy was found to be 18.7 kJ/mol and pre-exponential factor 51.4 min−1. The activation entropy (ΔS), change in Gibbs free energy (ΔG) and variation in activation enthalpy (ΔH) revealed that the transesterification reaction is endergonic and unspontaneous, while the endothermic nature of the reaction was confirmed by the positive value (16.6 kJ/mol) of the ΔH. The thermodynamic information and kinetic model reported here will provide valuable insight into the understanding of the in situ transesterification process from algae foamate to biodiesel.

Detailed abundances of the wide pairs of stars with and without planets: the binary systems 16 Cyg and HD 219542

ABSTRACT We present results of the comparative analysis of the two wide binary systems – 16 Cyg, with a giant gas planet orbiting around 16 Cyg B, and HD 219542 without planet detected. Atmospheric parameters of the binary components and the Sun were determined using their high-resolution spectra and the sme tools for automatic spectral analysis. By applying the synthetic spectrum method, we derived abundances of 29 and 23 chemical elements in 16 Cyg and HD 219542, respectively. For 19 of these elements, our results are based on the non-local thermodynamic equilibrium line formation. For both 16 Cyg and HD 219542, we obtained a small abundance difference between the A and B components: +0.019 ± 0.012 and −0.014 ± 0.019, respectively, suggesting only a weak influence of the giant gas planet formation on chemical composition of the host star atmosphere. For HD 219542 A and B, trends of the relative-to-solar abundances with the dust condensation temperature are similar to the literature data for the solar analogues without detected planets. The components of 16 Cyg reveal very similar behaviour of [X/H] with the condensation temperature; however, it is different from that for HD 219542. This indicates a specific chemical composition of the cloud from which the 16 Cyg binary system formed.

Verification of Information Thermodynamics in a Trapped Ion System.

Information thermodynamics has developed rapidly over past years, and the trapped ions, as a controllable quantum system, have demonstrated feasibility to experimentally verify the theoretical predictions in the information thermodynamics. Here, we address some representative theories of information thermodynamics, such as the quantum Landauer principle, information equality based on the two-point measurement, information-theoretical bound of irreversibility, and speed limit restrained by the entropy production of system, and review their experimental demonstration in the trapped ion system. In these schemes, the typical physical processes, such as the entropy flow, energy transfer, and information flow, build the connection between thermodynamic processes and information variation. We then elucidate the concrete quantum control strategies to simulate these processes by using quantum operators and the decay paths in the trapped-ion system. Based on them, some significantly dynamical processes in the trapped ion system to realize the newly proposed information-thermodynamic models is reviewed. Although only some latest experimental results of information thermodynamics with a single trapped-ion quantum system are reviewed here, we expect to find more exploration in the future with more ions involved in the experimental systems.

Molecular-Based Description of the Osmotic Second Virial Coefficients of Electrolytes: Rigorous Formal Links to Solute-Solvent Interaction Asymmetry, Virial Expansion Paths, and Experimental Evidence.

We introduce a molecular-based route to the evaluation of the osmotic second virial coefficients of dissociative solutes in dilute binary solutions, according to a general molecular thermodynamic solvation formalism of electrolyte solutions. We discuss the underlying solvation fundamentals and derive rigorous expressions leading to (i) the functional relationship among the osmotic second virial coefficients and the limiting composition behavior of the non-Coulombic contribution to the Kirkwood-Buff integral of the solute-solute interactions, the corresponding composition slope of the mean activity coefficient of the electrolyte solute, and a precisely defined solute-solvent intermolecular interaction asymmetry that characterizes unambiguously the solution non-ideality; (ii) the self-consistent calculation of the osmotic second virial coefficients of electrolytes as defined by the composition expansion along different thermodynamic paths and/or composition variables; (iii) the microstructural interpretation of Hill's isobaric-isothermal osmotic second virial coefficient in terms of Kirkwood-Buff correlation function integrals and its relationships to other osmotic coefficients from composition expansions along alternative thermodynamic paths; and (iv) the identification of drawbacks in the implementation of previous methods, originally intended for non-electrolyte systems, to systems involving dissociative solutes. The proposed formalism provides the fundamentally based foundations to the determination of the osmotic second virial coefficients of any type of electrolyte solute, whose thermodynamic expressions converge naturally to the non-electrolyte ones by setting to unity the solute stoichiometric coefficient ν. Following the formal results, we illustrate the formalism with the calculation of a variety of osmotic second virial coefficients involving a wide selection of aqueous solutions at ambient conditions and comprising a wide range of anion-cation type combinations characterized by 2 ≤ ν ≤ 6. Finally, we interpret the behavior of the resulting osmotic virial coefficients in terms of the solute-solvent intermolecular interaction asymmetry, discuss the experimental data requirements for the accurate evaluation of the osmotic second virial coefficients, and provide some observations as well as their modeling implications.

Measuring thermodynamic preferences to form non-native conformations in nucleic acids using ultraviolet melting

Thermodynamic preferences to form non-native conformations are crucial for understanding how nucleic acids fold and function. However, they are difficult to measure experimentally because this requires accurately determining the population of minor low-abundance (<10%) conformations in a sea of other conformations. Here, we show that melting experiments enable facile measurements of thermodynamic preferences to adopt nonnative conformations in DNA and RNA. The key to this "delta-melt" approach is to use chemical modifications to render specific minor non-native conformations the major state. The validity and robustness of delta-melt is established for four different non-native conformations under various physiological conditions and sequence contexts through independent measurements of thermodynamic preferences using NMR. Delta-melt is faster relative to NMR, simple, and cost-effective and enables thermodynamic preferences to be measured for exceptionally low-populated conformations. Using delta-melt, we obtained rare insights into conformational cooperativity, obtaining evidence for significant cooperativity (1.0 to 2.5 kcal/mol) when simultaneously forming two adjacent Hoogsteen base pairs. We also measured the thermodynamic preferences to form G-C+ and A-T Hoogsteen and A-T base open states for nearly all 16 trinucleotide sequence contexts and found distinct sequence-specific variations on the order of 2 to 3 kcal/mol. This rich landscape of sequence-specific non-native minor conformations in the DNA double helix may help shape the sequence specificity of DNA biochemistry. Thus, melting experiments can now be used to access thermodynamic information regarding regions of the free energy landscape of biomolecules beyond the native folded and unfolded conformations.

Thermodynamic Formation Properties of Point Defects in Germanium Crystal.

Point defects are crucial in determining the quality of germanium crystals. A quantitative understanding of the thermodynamic formation properties of the point defects is necessary for the subsequent control of the defect formation during crystal growth. Here, molecular dynamics simulations were employed to investigate the formation energies, total formation free energies and formation entropies of the point defects in a germanium crystal. As far as we know, this is the first time that the total formation free energies of point defects in a germanium crystal have been reported in the literature. We found that the formation energies increased slightly with temperature. The formation free energies decreased significantly with an increase in temperature due to the increase in entropy. The estimated total formation free energies at the melting temperature are ~1.3 eV for self-interstitial and ~0.75 eV for vacancy, corresponding to a formation entropy of ~15 kB for both types of point defects.

New Paradigm in Thermodynamic Formulation of Dynamic Redox Systems

New Paradigm in Thermodynamic Formulation of Dynamic Redox Systems

Tunable fluorescence of Imidazo[1,2‐a]pyridine derivatives with additional proton transfer sites Harnessing excited-state intramolecular double proton transfer: Theoretical insight

Electronic properties and excited-state intramolecular proton transfers of a new designed series of doubly intramolecular hydrogen bonding molecules having imidazo[1,2-a]pyridines as proton acceptors with different types of proton donors (hydroxy-type, amino-type, and mixing-type) and their derivatives have been theoretically evaluated for fluorescent probes. Overall, all designed molecules are photoexcited at ∼420 nm and give fluorescence in the NIR region with large Stokes shifts. The fluorescence of NH- and Mixed-type molecules are notably longer than that of OH-type molecules, and those of the derivatives with a π-conjugated spacer are slightly longer than those of their analogues. Based on the kinetic and thermodynamic information, all designed molecules could not exhibit the double proton transfer (DPT) process but only single proton transfer (SPT) is preferred. Moreover, the dynamic simulations on the excited-state confirm that only SPT is allowed but not DPT in accordance with the predicted PT barriers and reaction energies, leading only NT* fluorescence but their NT* fluorescence maxima are still in the NIR region (600–900 nm) with large Stokes shifts (∼300 nm). The NIR fluorescence is caused by an additional PT unit and a π-conjugated spacer induce the ICT character evidenced by the EDD maps. Therefore, these designed molecules exhibiting NIR tautomer emission with large Stokes shifts could be potential candidates for NIR fluorescent probes with avoiding self-absorption and less photo-damage.