Thermodynamical Basis Research Articles

Electrical energy input efficiency limitations in CO2‐to‐CO electrolysis and attempts for improvement

AbstractElectrochemical CO2 reduction is a potentially up‐coming technology to convert anthropogenic emitted CO2 into chemical feedstock. Due to alkaline operating conditions of CO2‐electrolyis in gas diffusion electrodes, exothermal hydroxide ion neutralization with the excess of supplied CO2 leads to unavoidable electricity‐to‐heat conversion at the cathode, therefore limiting electrical energy input efficiency. The decomposition reaction of carbonates by protons from water oxidation completes the inherent CO2 transport at the anode. In this work, different production routes to CO are thermodynamically examined and experimentally validated. Using formic acid as an intermediate towards CO the electrical energy input efficiency can rise to 71% on a thermodynamical basis. Additionally, the possibility of altering the mechanism of CO2 reduction under acidic conditions is investigated, which would lead to even larger electrical energy input efficiencies. The concept was investigated by pH series measurements (pH = 0–6) at 50 mA/cm2 where Pb derived from Pb3O4 was used as a CO2 reduction catalyst. The reduction to formic acid under acidic bulk electrolyte pH is stable at FEHCOOH = 70% down to pH ≈ 1, while HER is becoming dominant below. Even under such acidic bulk electrolyte conditions no change in reduction mechanism could be forced, which is reflected in invariant cell voltages in the model experiment.

Cooperation between a T Domain and a Minimal C-Terminal Docking Domain to Enable Specific Assembly in a Multiprotein NRPS.

Non‐ribosomal peptide synthetases (NRPS) produce natural products from amino acid building blocks. They often consist of multiple polypeptide chains which assemble in a specific linear order via specialized N‐ and C‐terminal docking domains (N/CDDs). Typically, docking domains function independently from other domains in NRPS assembly. Thus, docking domain replacements enable the assembly of “designer” NRPS from proteins that normally do not interact. The multiprotein “peptide‐antimicrobial‐Xenorhabdus” (PAX) peptide‐producing PaxS NRPS is assembled from the three proteins PaxA, PaxB and PaxC. Herein, we show that the small CDD of PaxA cooperates with its preceding thiolation (T1) domain to bind the NDD of PaxB with very high affinity, establishing a structural and thermodynamical basis for this unprecedented docking interaction, and we test its functional importance in vivo in a truncated PaxS assembly line. Similar docking interactions are apparently present in other NRPS systems.

Thermodynamic features of dioxins’ adsorption

In this paper, the six more poisonous species among all congeners of dioxin group are taken into account, and the P-T diagram for each of them is developed. Starting from the knowledge of vapour tensions and thermodynamic parameters, the theoretical adsorption isotherms are calculated according to the Langmuir’s model. In particular, the Langmuir isotherm parameters (K and wmax) have been validated through the estimation of the adsorption heat (ΔHads), which varies in the range 20–24kJ/mol, in agreement with literature values. This result will allow to put the thermodynamical basis for a rational design of different process units devoted to dioxins removal.

Onsagerian Quantum Mechanics

We describe the basic quantum-mechanical categories and properties of the thermodynamical basis of Onsager’s theorem. 3 basic principles are used: 1. energy dissipation; 2. Hamiltonian formalism; 3. Onsager’s linearity. We obtain the 2 characteristic values of the observables, their main-value and the deviation, the first and second momentums of the probability distribution function, which we also derived also from the same principles.Â

Multi-scale modeling of chemo-mechanical coupling in muscle contraction and applications to cardiac modeling

We propose a muscle chemo-mechanical model by which myosin heads - that can chemically bind to actin, thus creating so-called cross-bridges producing contraction forces in sarcomeres at the subcellular level - are considered as special chemical entities having internal mechanical variables pertaining to the actual geometric configuration. This provides a thermodynamical basis for modeling the complex interplay of chemical and mechanical phenomena at the sarcomere level. The resulting model is in the form of stochastic equations governing the dynamics of these microscopic mechanical variables in a Langevin framework. Equivalently, Fokker-Planck equations can be derived to describe the evolution of the associated probability densities. Under certain assumptions the corresponding moment equations can be closed, thus directly providing access to macroscopic quantities that can be incorporated in the overall constitutive equations of the muscle tissue. The underlying thermodynamical framework also enables the derivation of compatible numerical schemes, in particular in terms of energy balances. These modeling and discretization ingredients can be integrated in a global model of the cardiac system, to represent physiological and pathological phenomena in various medical applications.

Indentation of Highly Charged PSPM Brushes Measured by Force Spectroscopy: Application of a Compressible Fluid Model

Highly charged dense poly(sulfopropyl methacrylate) polyelectrolyte brushes were indented with an atomic force microscopy (AFM) tip as well as with an 8 μm silica colloidal probe at different ionic strengths ranging from Millipore water to 1 M NaCl. The force response during indentation was fitted to a phenomenological equation analogous to the equation of state of a compressible fluid. In this way, internal energy and brush thickness were obtained as a function of ionic strength. Long-range forces decayed exponentially with distance. The characteristic decay lengths were much larger than the Debye screening lengths at the respective ionic strengths. It was therefore concluded that long-range repulsion was due to compression of a loose corona of polymers in front of the dense part of the brush. The size of the indentor determines which region of the brush can be explored by AFM. The tip probes the denser parts of the brush, while with the colloidal probe the corona of the brush can be investigated. The obtained fits of the experimentally measured force distance curves were used as regularization tools for obtaining the brush swelling pressure or “force per unit area” as a function of brush compression. The swelling pressure as a function of brush thickness, h, followed over a wide range a power law close to ∼h–2. This approach allowed deriving fundamental brush parameters on a thermodynamical basis like the compressibility as a function of thickness.

Universal Property of Quantum Gravity implied by Bekenstein-Hawking Entropy and Boltzmann formula

We search for a universal property of quantum gravity. By "universal", we mean the independence from any existing model of quantum gravity (such as the super string theory, loop quantum gravity, causal dynamical triangulation, and so on). To do so, we try to put the basis of our discussion on theories established by some experiments. Thus, we focus our attention on thermodynamical and statistical-mechanical basis of the black hole thermodynamics: Let us assume that the Bekenstein-Hawking entropy is given by the Boltzmann formula applied to the underlying theory of quantum gravity. Under this assumption, the conditions justifying Boltzmann formula together with uniqueness of Bekenstein-Hawking entropy imply a reasonable universal property of quantum gravity. The universal property indicates a repulsive gravity at Planck length scale, otherwise stationary black holes can not be regarded as thermal equilibrium states of gravity. Further, in semi-classical level, we discuss a possible correction of Einstein equation which generates repulsive gravity at Planck length scale.

A discrete network model for bond failure and frictional sliding in fibrous materials

Discrete network models and lattice models using trusses or beams can be used to mechanically model fibrous materials, since the discrete elements represent the individual fibers or yarns at the mesoscale of these materials. Consequently, local mesoscale phenomena, such as individual fiber failure and interfiber bond failure, can be incorporated. Only a few discrete network models in which bond failure is incorporated include frictional fiber sliding that occurs after bond failure has taken place, although this occurs in the mechanical behaviour of several fibrous materials. In this paper, a spring network model for interfiber bond failure and subsequent frictional fiber sliding is developed, which is formulated in a thermodynamical setting. The thermodynamical basis ensures that performed mechanical work is either stored in the network or dissipated due to bond failure and subsequent sliding. A numerical implementation of the framework is proposed in which the kinematic and internal variables are simultaneously solved, because the internal variables are directly coupled in the framework. Variations in network connectivity, bond strength, fiber length and anisotropy are implemented in the framework. The results show amongst others that the macroscopic yield point scales with the bond strength and that the macroscopic stiffness and the macroscopic yield point scale with the fiber length. The presented results also show that the macroscopic yield point becomes significantly less pronounced for an increase of the fiber length.

Positron Annihilation Parameters in Connection to Surface Phenomenon of Liquids

Surface tension is an important property of liquid, the bulk surface tension concept changes considerably when minute volume of a given liquid (drop let radius<10nm) is considered. Although an extensive thermodynamical treatment and theoretical basis have been considered in the past on the curvature dependence of surface tension, yet its experimental evaluation is deemed necessary and it has been shown hither to that positronium annihilation parameters serve faithfully to this purpose. However, the drastic lowering of surface tension with the dispersion of surfactant in the liquid phase display a different phenomenon altogether and has been dealt separately by positron annihilation results.

Thermodynamical basis for the radical-scavenging activity of flavonoids revealed with Hartree-Fock computations and thermochemical deduction

Thermodynamical basis for the radical-scavenging activity of flavonoids revealed with Hartree-Fock computations and thermochemical deduction

On the Generalized Thermal Lagging Behavior: Refined Aspects

A fractional hyperbolic two-temperature (FHTT) model, that replaces the well-known one derived by Qiu and Tien (HTT), and results in a model revealing other possible sub-cases in the energy transport in both the photon–electron and electron–phonon interaction processes, is proposed in the present work. The hyperbolicity of HTT-model is accommodated. Tzou idea (the thermal lagging behavior) is modified through an alternative definition that also captures the microstructural effects and the hyperbolic nature of energy transport by electrons. Hence, a fractional Tzou law is suggested, and again, direct correlations are established with the FHTT-model. Ignaczak conditions are modified, fractional generalized Gibbs equation is introduced and some restrictions are imposed on the entropy source term in order to put a rigorous thermodynamical basis for the fractional Qiu–Tien and Tzou models. The Danilovskaya problem is revisited in the framework of the modified dual-phase-lag-thermoelasticity based on the proposed fractional Tzou law.

Long-range dependencies in reading memory pages in the man-computer system interaction

The modern computer systems consist of many interdependent subsystems. There are two possible approaches to their analysis. The first one is based on the idea of reductionism proposed by Descrates[1] and can be considered as a still ruling paradigm in the case of computer science and engineering. The second one can be related to the still new idea of the complex systems approach, where in order to understand the behaviour of such systems one needs to have the knowledge about the behaviour of system components and also, that is more important, how they act together [2, 3, 4, 5, 6, 7, 8]. This specific paradigm change can be even shown in the case of the idea of Turing machines and new approach for consideration in the case of interactive processing – even the opinion that “the computer engineering is not a mathematical science” was presented [9]. It should be noted that the Turing machine is a mathematical idea [10] while its implementations are the physical ones [11], but if the physical nature of computer systems was indicated, there is a need to have an appropriate physical (thermodynamical) basis for deliberations in such a case. In [12] it has been shown that the analysis of processes in the computer systems can be based on non-extensive thermodynamics. However, this analysis considers only spatial correlations, meanwhile in this paper we will focus on time dependencies leading to a long-memory effect. The paper is divided into 5 sections. In Section 2 the conception of the hierarchical structure of memory system in the computer is presented. This proposal was given in [11] where its influence on computer thermodynamics was discussed. In Section 3 there is a short survey about long-range dependencies whereas Section 4 discusses practical usage of theoretical considerations. The last section concludes the paper.

Long-range dependencies in reading memory pages in the man-computer system interaction

The modern computer systems consist of many interdependent subsystems. There are two possible approaches to their analysis. The first one is based on the idea of reductionism proposed by Descrates[1] and can be considered as a still ruling paradigm in the case of computer science and engineering. The second one can be related to the still new idea of the complex systems approach, where in order to understand the behaviour of such systems one needs to have the knowledge about the behaviour of system components and also, that is more important, how they act together [2, 3, 4, 5, 6, 7, 8]. This specific paradigm change can be even shown in the case of the idea of Turing machines and new approach for consideration in the case of interactive processing – even the opinion that “the computer engineering is not a mathematical science” was presented [9]. It should be noted that the Turing machine is a mathematical idea [10] while its implementations are the physical ones [11], but if the physical nature of computer systems was indicated, there is a need to have an appropriate physical (thermodynamical) basis for deliberations in such a case. In [12] it has been shown that the analysis of processes in the computer systems can be based on non-extensive thermodynamics. However, this analysis considers only spatial correlations, meanwhile in this paper we will focus on time dependencies leading to a long-memory effect. The paper is divided into 5 sections. In Section 2 the conception of the hierarchical structure of memory system in the computer is presented. This proposal was given in [11] where its influence on computer thermodynamics was discussed. In Section 3 there is a short survey about long-range dependencies whereas Section 4 discusses practical usage of theoretical considerations. The last section concludes the paper.

Solvent Parameters and the Thermodynamics of Mobile Disorder in Liquids

According to the basis ideas of Gutmann, specific cohesion forces are in many cases more important for solvent effects than non-specific interactions. In this work the fundamental differences between H-bonds or n-σ EDA bonds and non-specific dipole-dipole interactions are outlined: stechiometry, directionality, and especially the essential difference between the two active sites. As a consequence the capacity of a solvent to form specific bonds with the solute cannot be described by a single parameter. As pointed out by Gutmann, two different capacities of the solvent have to be considered. The solvents can be classed according to the presence in their molecule of active sites of one or another kind. The theoretical ground for the use of solvent parameters is studied in the frame of the thermodynamics of the Mobile Disorder in liquids developed by Huyskens and Siegel. A new solvent parameter based on the ratio of the molar volumes of solute and solvent PVB/VS is introduced which is equal to (0.5 — rS)(vB/vS) + 0.5 ln(VB/VS) - 0.5. rS takes the value of one for amphiphilic solvents with one proton donor site, of two for the solvents with two hydroxylic protons and of zero for the others. For amphiphilic solutes (with one OH group) rS has to be added to the former expression. This purely entropic parameter is independent of all the others. A positive value of PVB/VS corresponds to a decrease of μB/RT and a stabilization of the solute in the solution. At high dilution the solute-solvent specific forces decrease μB/RT by an amount ln(1 + K/VS) where K is the stability constant of the bond. The latter depends on both the solvent and the solute. The values ln(1 + Kref/VS) of various solvents can be compared for some reference solute. This constitutes the thermodynamical basis for the use of solvent parameters. The acceptor and the donor parameters AN and DN of Gutmann are discussed from this point of view.

Non-Extensive Statistical Mechanics - a Possible Basis for Modelling Processes in Computer Memory System

Tsallis definition of non-extensive entropy introduced in 1988 has been considered to obtain new possibilities to construct generalized thermodynamical basis for statistical physics expanding classical Boltzmann‐Gibbs thermodynamics for nonequilibrium states. During the last two decades this q-generalized theory has been successfully applied to considerable number of physically interesting complex phenomena. In the paper the possible thermodynamical basis of processes will be presented in nowadays computer systems in the case of memory behaviour.

TOWARDS POSSIBLE NON-EXTENSIVE THERMODYNAMICS OF ALGORITHMIC PROCESSING — STATISTICAL MECHANICS OF INSERTION SORT ALGORITHM

Tsallis entropy introduced in 1988 is considered to have obtained new possibilities to construct generalized thermodynamical basis for statistical physics expanding classical Boltzmann–Gibbs thermodynamics for nonequilibrium states. During the last two decades this q-generalized theory has been successfully applied to considerable amount of physically interesting complex phenomena. The authors would like to present a new view on the problem of algorithms computational complexity analysis by the example of the possible thermodynamical basis of the sorting process and its dynamical behavior. A classical approach to the analysis of the amount of resources needed for algorithmic computation is based on the assumption that the contact between the algorithm and the input data stream is a simple system, because only the worst-case time complexity is considered to minimize the dependency on specific instances. Meanwhile the article shows that this process can be governed by long-range dependencies with thermodynamical basis expressed by the specific shapes of probability distributions. The classical approach does not allow to describe all properties of processes (especially the dynamical behavior of algorithms) that can appear during the computer algorithmic processing even if one takes into account the average case analysis in computational complexity. The importance of this problem is still neglected especially if one realizes two important things. The first one: nowadays computer systems work also in an interactive mode and for better understanding of its possible behavior one needs a proper thermodynamical basis. The second one: computers from mathematical point of view are Turing machines but in reality they have physical implementations that need energy for processing and the problem of entropy production appears. That is why the thermodynamical analysis of the possible behavior of the simple insertion sort algorithm will be given here.

Towards possible [formula omitted]-generalizations of the Malthus and Verhulst growth models

Tsallis entropy introduced in 1988 based on the equation S q = 1 − ∑ i p i q q − 1 has been considered to obtain new possibilities for constructing a generalized thermodynamical basis for statistical physics, expanding classical Boltzmann–Gibbs thermodynamics for non-equilibrium states. During the last two decades this q -generalized theory has been successfully applied to a considerable amount of physically interesting complex phenomena. The authors wish to present a mathematical analysis of the possible q -generalizations of the Malthus and the Verhulst growth models based on Tsallis definitions of the q -logarithm and the q -exponential.

High affinity binding strategies for bacterial lectins interacting with eukaryotic carbohydrates

Lectin-carbohydrate interactions are generally characterised by a low affinity for monovalent ligands, a drawback balanced by multivalency that provides high avidity for substrates with several potential ligands available, such as complex glycans or cell surfaces. In general, a millimolar affinity is observed for lectin binding to monosaccharides. Better affinity is obtained for longer ligand, i.e. oligosaccharides, and the interactions are typified by a favourable enthalpy term, due to the high number of hydrogen bonds, that is offset by an unfavourable entropy contribution. Recent interest in bacterial lectins involved in pathogenesis and host recognition has been accompanied by thermodynamic characterisation that demonstrated much higher affinity than that observed for plant or animal lectins. Calcium–dependent lectins from opportunistic pathogens Pseudomonas aeruginosa, Chromobacterium violaceaum and Ralstonia solanacearum all display sub-micromolar range affinity towards their carbohydrate ligands. We used combined titration microcalorimetry and x-ray crystallography approaches to decipher the thermodynamical and structural basis for high affinity binding of bacterial lectins to host carbohydrates. Research funded by CNRS, Association “Vaindre la Mucoviscidose” and Mizutani foundation for Glycosciences

Side chain interactions determine the amyloid organization: a single layer β-sheet molecular structure of the calcitonin peptide segment 15–19

In this paper we present a detailed atomic model for a protofilament, the most basic organization level, of the amyloid fibre formed by the peptide DFNKF. This pentapeptide is a segment derived from the human calcitonin, a natural amyloidogenic protein. Our model, which represents the outcome of extensive explicit solvent molecular dynamics (MD) simulations of different strand/sheet organizations, is a single β-sheet filament largely without a hydrophobic core. Nevertheless, this structure is capable of reproducing the main features of the characteristic amyloid fibril organization and provides clues to the molecular basis of its experimental aggregation behaviour. Our results show that the side chains' chemical diversity induces the formation of a complex network of interactions that finally determine the microscopic arrangement of the strands at the protofilament level. This network of interactions, consisting of both side chain–side chain and backbone–side chain interactions, confers on the final single β-sheet arrangement an unexpected stability, both by enhancing the association of related chemical groups and, at the same time, by shielding the hydrophobic segments from the polar solvent. The chemical physical characterization of this protofilament provides hints to the possible thermodynamical basis of the supra molecular organization that allows the formation of the filaments by lateral association of the preformed protofibrils. Its regular, highly polarized structure shows how other protofilaments can assemble. In terms of structural biology, our results clearly indicate that an amyloid organization implies a degree of complexity far beyond a simple nonspecific association of peptide strands via amide hydrogen bonds.

Irreversible thermodynamics, parabolic law and self-similar state in grain growth

The formalism of the thermodynamic theory of irreversible processes is applied to grain growth to investigate the nature of the self-similar state and its corresponding parabolic law. Grain growth does not reach a steady state in the sense that the entropy production remains constant. However, the entropy production can be written as a product of two factors: a scale factor that tends to zero for long times and a scaled entropy production. It is suggested that the parabolic law and the self-similar state may be associated with the minimum of this scaled entropy production. This result implies that the parabolic law and the self-similar state have a sound irreversible thermodynamical basis.