Temperature-dependent Interaction Research Articles

Temperature-dependent hydrogen-induced crack propagation behaviour and mechanism in polycrystalline α-iron: Insights from molecular dynamics simulations

Understanding the interactions between hydrogen and material integrity in polycrystalline α-Fe is essential for advancing the reliability of critical infrastructure and energy systems. In this study, molecular dynamics simulations were implemented to pinpoint the crack propagation behaviour and mechanism in polycrystalline α-Fe under various hydrogen concentrations and temperatures. The results show that a phase transition from body-centred cubic to face-centred cubic structure first occurs at the crack tip, followed by grain boundary-mediated plasticity activities at room temperature devoid of hydrogen. A limited amount of hydrogen atoms (H/Fe atomic ratio<1%) induces twinning emission from the tip, and increasing temperature further enhances dislocation plasticity as a consequence of decreased unstable stacking fault energy, thereby leading to the blunting of the crack tip. At high hydrogen concentrations (H/Fe atomic ratio>1%), the formed hydrides ahead of the crack tip suppress the phase transition, and concurrently temperature-enhanced dislocation plasticity disappears. As a consequence, the crack propagation proceeds via grain boundary cavity nucleation and growth, and ultimately evolves into intergranular fracture. These findings provide an atomistic-level explanation for temperature-dependent hydrogen-crack interaction mechanisms, and reveal a transition in the fracture mode from ductile transgranular to intergranular failure associated with locally high hydrogen concentrations found in the experiments.

Fluid Phase Equilibria Carbon Dioxide + Decane + Hexadecane Ternary System

The interest in understanding reservoir fluids' phase behavior is to increase hydrocarbon production without any flow assurance issues. Due to its opacity, the evident complexity of determining phase equilibrium data revolves around the thermodynamic modeling of model systems. The article presents experimental phase equilibrium data and thermodynamic modeling for the CO2 + decane + hexadecane ternary system at 283.15, 298.15, and 323.15 K and pressures up to 20 MPa. The transitions observed during this study were liquid-liquid (LL), vapor-liquid (VL), and vapor-liquid-liquid (VLL). The Peng-Robinson equation of state was used to model this ternary system for various compositions. The temperature-dependent binary interaction parameters (kij) for the CO2 + n-alkane mixtures were adjusted to the experimental data. Additionally, a binary interaction parameter for the n-C16H34/n-C10H22 pair, independent of temperature, was obtained through the critical volume of the components. The results reveal complex behaviors as the mixture's composition of hexadecane progressively increases. Adding this longer-chain linear hydrocarbon influences the phase behavior, leading to the emergence of liquid-liquid transitions and barotropic inversion in the system. This study contributes valuable data on model systems representing crude oil, highlighting complex behaviors in ternary systems with high carbon dioxide content.

Temperature-dependent Spike-ACE2 interaction of Omicron subvariants is associated with viral transmission.

The continued evolution of severe acute respiratory syndrome 2 (SARS-CoV-2) requires persistent monitoring of its subvariants. Omicron subvariants are responsible for the vast majority of SARS-CoV-2 infections worldwide, with XBB and BA.2.86 sublineages representing more than 90% of circulating strains as of January 2024. To better understand parameters involved in viral transmission, we characterized the functional properties of Spike glycoproteins from BA.2.75, CH.1.1, DV.7.1, BA.4/5, BQ.1.1, XBB, XBB.1, XBB.1.16, XBB.1.5, FD.1.1, EG.5.1, HK.3, BA.2.86 and JN.1. We tested their capacity to evade plasma-mediated recognition and neutralization, binding to angiotensin-converting enzyme 2 (ACE2), their susceptibility to cold inactivation, Spike processing, as well as the impact of temperature on Spike-ACE2 interaction. We found that compared to the early wild-type (D614G) strain, most Omicron subvariants' Spike glycoproteins evolved to escape recognition and neutralization by plasma from individuals who received a fifth dose of bivalent (BA.1 or BA.4/5) mRNA vaccine and improve ACE2 binding, particularly at low temperatures. Moreover, BA.2.86 had the best affinity for ACE2 at all temperatures tested. We found that Omicron subvariants' Spike processing is associated with their susceptibility to cold inactivation. Intriguingly, we found that Spike-ACE2 binding at low temperature was significantly associated with growth rates of Omicron subvariants in humans. Overall, we report that Spikes from newly emerged Omicron subvariants are relatively more stable and resistant to plasma-mediated neutralization, present improved affinity for ACE2 which is associated, particularly at low temperatures, with their growth rates.IMPORTANCEThe persistent evolution of SARS-CoV-2 gave rise to a wide range of variants harboring new mutations in their Spike glycoproteins. Several factors have been associated with viral transmission and fitness such as plasma-neutralization escape and ACE2 interaction. To better understand whether additional factors could be of importance in SARS-CoV-2 variants' transmission, we characterize the functional properties of Spike glycoproteins from several Omicron subvariants. We found that the Spike glycoprotein of Omicron subvariants presents an improved escape from plasma-mediated recognition and neutralization, Spike processing, and ACE2 binding which was further improved at low temperature. Intriguingly, Spike-ACE2 interaction at low temperature is strongly associated with viral growth rate, as such, low temperatures could represent another parameter affecting viral transmission.

Asymmetry in Polymer-Solvent Interactions Yields Complex Thermoresponsive Behavior.

We introduce a lattice framework that incorporates elements of Flory-Huggins solution theory and the q-state Potts model to study the phase behavior of polymer solutions and single-chain conformational characteristics. Without empirically introducing temperature-dependent interaction parameters, standard Flory-Huggins theory describes systems that are either homogeneous across temperatures or exhibit upper critical solution temperatures. The proposed Flory-Huggins-Potts framework extends these capabilities by predicting lower critical solution temperatures, miscibility loops, and hourglass-shaped spinodal curves. We particularly show that including orientation-dependent interactions, specifically between monomer segments and solvent particles, is alone sufficient to observe such phase behavior. Signatures of emergent phase behavior are found in single-chain Monte Carlo simulations, which display heating- and cooling-induced coil-globule transitions linked to energy fluctuations. The framework also capably describes a range of experimental systems. Importantly, and by contrast to many prior theoretical approaches, the framework does not employ any temperature- or composition-dependent parameters. This work provides new insights regarding the microscopic physics that underpin complex thermoresponsive behavior in polymers.

Frustration—no frustration crossover and phase transitions in 2D spin models with zig-zag structures

Three 2D spin models made of frustrated zig-zag chains with competing interactions which, by exact summation with respect to some degrees of freedom, can be replaced by an effective temperature-dependent interaction, were considered. The first model, exactly solvable Ising chains coupled by only four-spin interactions, does not exhibit any finite temperature phase transition; nevertheless, temperature can trigger a frustration–no frustration crossover accompanied by gigantic specific heat. A similar effect was observed in several two-leg ladder models (Weiguo 2020 arXiv:2006.08921v2; 2020 2006.15087v1). The anisotropic Ising chains coupled by a direct interchain interaction and, competing with it, indirect interaction via spins located between chains, are analyzed using the exact Onsager’s equation and linear perturbation renormalization group (LPRG). Depending on the parameter set, such a model exhibits one antiferromagnetic (AF) or ferromagnetic (FM) phase transition or three phase transitions with a re-entrant disordered phase between AF and FM ones. The LPRG method was also used to study coupled uniaxial XXZ chains which, for example, can be a minimal model to describe the magnetic properties of compounds in which uranium and rare earth atoms form zig-zag chains. As with the Ising model, for a certain set of parameters, the model can undergo three phase transitions. However, both intrachain and interchain plain interactions si,jxsk,lx+si,jysk,ly can eliminate the re-entrant disordered phase, and then only one transition takes place. Additionally, the XXZ model can undergo temperature-induced metamagnetic transition.

Temperature-induced migration of electro-neutral interacting colloidal particles

Migration of colloidal particles induced by temperature gradients is commonly referred to as thermodiffusion, thermal diffusion, or the (Ludwig-)Soret effect. The thermophoretic force experienced by a colloidal particle that drives thermodiffusion consists of two distinct contributions: a contribution resulting from internal degrees of freedom of single colloidal particles, and a contribution due to the interactions between the colloids. We present an irreversible thermodynamics based theory for the latter collective contribution to the thermophoretic force. The present theory leads to a novel “thermophoretic interaction force” (for uncharged colloids), which has not been identified in earlier approaches. In addition, an N-particle Smoluchowski equation including temperature gradients is proposed, which complies with the irreversible thermodynamics approach.A comparison with experiments on colloids with a temperature dependent attractive interaction potential over a large concentration and temperature range is presented. The comparison shows that the novel thermophoretic interaction force is essential to describe data on the Soret coefficient and the thermodiffusion coefficient.

Exploring the competition between α-decay and proton radioactivity: A comparative study of proximity potential formalisms

We have conducted a comprehensive and systematic study of the proton radioactivity and α-decay half-lives of neutron-deficient nuclei. This investigation involved the utilization of various Proximity potentials and also considered the incorporation of thermal effects. For the half-life calculations, we employed both temperature-independent and temperature-dependent interaction potentials. We observed that proton radioactivity serves as the dominant mode of decay for nuclides situated very close to the proton drip-line. We explored a universal curve that examines the correlation between the decimal logarithm of experimental half-lives and the negative decimal logarithm of the penetrability for both proton radioactivity and α-decay.

Solubility study of carbon dioxide in pentaerythritol esters: Based on SAFT-VR-Mie equation of state

Lubricants are almost necessary for carbon dioxide systems in the energy, chemical, and refrigeration industries. The study of the solubility behavior of lubricants with working fluids requires a proper equation of state as necessary tools. The solubility of CO2 in synthetic precursors for polyol esters lubricants has been investigated by SAFT-VR-Mie EoS with variable fluid potential, including pure component pentaerythritol esters (PEC) molecules and CO2-PECs mixed system. The correlations between the molecular parameters in SAFT-VR-Mie EoS and mass of PECs with different branched lengths are given under the constraints of experimental PρT data. According to the parameterized molecular model, the prediction of the critical point and the constant-pressure specific heat of the PECs is introduced in this work. The dissolution balance model of CO2 in PECs was developed by the quantitative model of temperature and molecular mass dependent molecular interaction factor kij. The explanation for the variation of the interaction factors is given by the analysis of the intermolecular volume differences effect, and the extension of this model to commercial lubricants still proves to be valid and accurate.

A possible coexistence of spontaneous magnetic order and thermal entanglement in a spin-1/2 Ising–Heisenberg diamond-decorated square lattice

The spin-1/2 Ising–Heisenberg model on a diamond-decorated square lattice is exactly solved by the decoration-iteration transformation, which establishes an exact mapping correspondence with the spin-1/2 Ising model on a square lattice with an effective temperature-dependent interaction between the nearest-neighbor spins. Exact results for the pair correlation function and spontaneous magnetization of the Heisenberg spins gained from the exact mapping equivalence allow a straightforward implementation of the concurrence, which may serve as a measure of the bipartite entanglement within decorating Heisenberg spin pairs. It is evidenced that the concurrence gradually diminishes upon increase of temperature above a disordered monomer-dimer ground state until it completely vanishes at a threshold temperature, while the concurrence is either always zero above a spontaneously ordered ferrimagnetic ground state or it shows a peculiar thermally assisted reentrance accompanied with a mutual coexistence of the spontaneous ferrimagnetic long-range order and the thermal entanglement.

A comprehensive thermodynamic modeling of the solubility of sugar alcohols in ionic liquids

Environmental regulations have recently drawn attention from fossil sources to green materials, among which sugar alcohols (SA) have particular importance due to their vast use in the nutrition, pharmaceutical, and chemical industries. Their properties and equilibrium conditions, including the extraction and solubility behavior utilizing novel solvents such as ionic liquids (ILs), are essential for developing further processes and their optimization. On account of this, the present study aims to develop a comprehensive thermodynamic approach based on simple and accurate tools such as activity coefficient models (ACMs) and equations of state (EoSs), which have not been hitherto addressed. To this end, eleven calculation schemes based on these two approaches were applied to the largest databank investigated thus far (13 SAs, 21 ILs, and 653 data points), and the performance of the models was analyzed. NRTL, free-volume Flory-Huggins (FVFH), and Redlich-Kister (RK) ACMs with different schemes, as well as athermal and ideal solution models, were evaluated and compared against well-known cubic EoSs such as Peng-Robinson (PR) and Valderrama-Patel-Teja (VPT). Benefitting from three adjustable parameters and a simple form, the three-parameter RK model yielded the best results with a 0.82 % (2.77 K) deviation in the entire databank. Moreover, employing temperature-dependent interaction parameters with FVFH ACM (3.55 K, 1.05 %), PR EoS (3.60 K, 1.07 %), and VPT EoS (3.66 K, 1.08 %) improved the accuracy of the calculations remarkably. The results of this contribution prove that thermodynamic models based on NRTL, FVFH, and RK ACMs are the best options for calculating solid–liquid conditions equilibrium of SA-IL systems with a simple and precise calculation procedure, and can therefore be employed for the simulation and optimization tools. This study investigates the most extensive SA-IL databank, a large number of models from different routes, and the nature of SA-IL pairs employing the obtained parameters.

The effect of temperature-dependent interfacial interaction on the stick–slip behavior of polyamide-66/zinc-coated steel

The stick–slip behavior of polymer/metal is a complex frictional issue since the properties of polymers are highly temperature-sensitive. The present study aimed to shed light on the key factors influencing the stick–slip behavior of polyamide-66/zinc-coated steel by conducting experiments at varying temperatures. The results revealed that the stick–slip behavior and interfacial interaction are temperature-dependent. The friction behavior transitioned from stick-slip to smooth sliding at 40 °C. The transition in the interfacial interaction from adhesion to plastic deformation with increased temperature was responsible for the reduction in stick–slip intensity. The reductions in both the potential energy and static friction force were believed to cause the decreased stick–slip intensity, as evidenced by the in-situ observation of the friction pairs through the digital image correlation (DIC) method. The present study could provide a comprehensive and targeted approach to suppressing the stick–slip behavior of polymer/metal over a wide range of temperatures.

Viscosity database for ternary Cu–Cr–X (X=Ni, Si, Zr) alloys based on CALPHAD-type modeling

A viscosity model with composition and temperature dependence for the liquid alloys of the Cu–Cr–X (X = Ni, Si, Zr) systems was developed using the CALPHAD (CALculation of PHAse Diagrams) approach. Based on the critical review of the available experimental data for pure metal viscosity, the viscosities of pure liquid Cu, Cr, Zr, Ni and Si were simulated with the Arrhenius formula. The viscosities of the binary liquid alloys of the Cu–Ni, Cu–Si, Cu–Zr, Cr–Ni, Cr–Si and Ni–Zr systems at different temperatures were evaluated using the CALPHAD-type formalism. The non-linear viscosity behavior resulting from chemical short-range order was described using temperature-dependent binary interaction parameters. The viscosities of the Cu–Cr and Cr–Zr liquid alloys were predicted employing the Hirai equation. The viscosities of the Cu–Cr–Zr, Cu–Cr–Ni and Cu–Cr–Si ternary liquids were directly extrapolated using the Redlish-Kister-Muggianu equation from the parameters of the binary systems. A comprehensive understanding of the temperature-composition-solidification phase-viscosity relationship was established for ternary melts. The satisfactory agreement observed between calculations and experimental data validates the use of CALPHAD-type viscosity modeling, supporting the suitability of the constructed viscosity database for predicting the viscosity of high-performance Cu-based alloys.

Temperature dependent interaction of hydrogen with PdAg nanocomposite thin films revealed by in-situ synchrotron XRD

PdAg nanocomposite alloy thin films were synthesized using a DC magnetron sputtering process to study the structural changes that occur in the alloy film during the process of hydrogenation and dehydrogenation at different temperatures. The atomic composition of the nano-composite film is 88 at % Pd and 12% at Ag, as determined by the EDAX analysis. In-situ synchrotron X-ray diffraction (XRD) has been used to monitor the subtle structural changes that occurred throughout the hydrogenation and dehydrogenation cycles at an interval of 10 s. This aspect has not been addressed so far. In-situ XRD studies reveal that the XRD peak shifts towards a lower angle due to the lattice expansion in the alloy due to hydrogenation. The change in peak shift is found to be different for different temperatures. The present study also shows no hysteresis during the hydrogen absorption and desorption processes. In addition, the results show that (i) the phase segregation has been observed at 250 °C, (ii) the peak shift during the hydrogenation process at higher temperatures is not significant, whereas the peak shift throughout the process is more rapid and pronounced at ambient temperature.

Solubility modeling of hydrogen sulfide in aqueous sodium salt solutions

Accurate solubility prediction of hydrogen sulfide in aqueous electrolyte solutions is critical for gas exploitation and geological storage. However, there is a lack of electrolyte Equation of State model that can accurately calculate the solubilities of hydrogen sulfide in aqueous electrolyte solutions over wide ranges of temperature, pressure, and salt molality. This work presents a modeling study on the solubilities of hydrogen sulfide in pure water and several aqueous sodium salt solutions. The thermodynamic framework used in this work is an electrolyte version of Cubic-Plus-Association Equation of State. The model’s temperature-dependent ion-gas binary interaction parameters are obtained by regressing the experimental solubilities in the aqueous electrolyte solutions. The modeling results show that the electrolyte Cubic-Plus-Association Equation of State can satisfactorily correlate the solubilities of hydrogen sulfide in aqueous electrolyte solutions over wide ranges of temperature, pressure, and salt molality. For the typical water–sodium chloride–hydrogen sulfide system, the model can satisfactorily correlate the gas solubilities with the mean relative deviation being 6.2%, with the temperature up to 593.95 K, pressure up to 32.30 MPa, and salt molality up to 6.0 mol⋅kg−1 water. Moreover, the salting-out effects and model adaptability are analyzed and discussed.

Lone Pair Rotation and Bond Heterogeneity Leading to Ultralow Thermal Conductivity in Aikinite.

Understanding the relationship between the crystal structure, chemical bonding, and lattice dynamics is crucial for the design of materials with low thermal conductivities, which are essential in fields as diverse as thermoelectrics, thermal barrier coatings, and optoelectronics. The bismuthinite-aikinite series, Cu1-x□xPb1-xBi1+xS3 (0 ≤ x ≤ 1, where □ represents a vacancy), has recently emerged as a family of n-type semiconductors with exceptionally low lattice thermal conductivities. We present a detailed investigation of the structure, electronic properties, and the vibrational spectrum of aikinite, CuPbBiS3 (x = 0), in order to elucidate the origin of its ultralow thermal conductivity (0.48 W m-1 K-1 at 573 K), which is close to the calculated minimum for amorphous and disordered materials, despite its polycrystalline nature. Inelastic neutron scattering data reveal an anharmonic optical phonon mode at ca. 30 cm-1, attributed mainly to the motion of Pb2+ cations. Analysis of neutron diffraction data, together with ab-initio molecular dynamics simulations, shows that the Pb2+ lone pairs are rotating and that, with increasing temperature, Cu+ and Pb2+ cations, which are separated at distances of ca. 3.3 Å, exhibit significantly larger displacements from their equilibrium positions than Bi3+ cations. In addition to bond heterogeneity, a temperature-dependent interaction between Cu+ and the rotating Pb2+ lone pair is a key contributor to the scattering effects that lower the thermal conductivity in aikinite. This work demonstrates that coupling of rotating lone pairs and the vibrational motion is an effective mechanism to achieve ultralow thermal conductivity in crystalline materials.

Mixing properties of liquid Al-Au alloys

The thermodynamic and structural properties of liquid Al-Au alloy have been studied in frame-work of R-K polynomial using temperature-dependent energy interaction parameters at different temperatures. Thermodynamic properties, excess free energy of mixing and activity, and in structural properties, concentration fluctuation in long wave-length limit have been computed at temperatures 1338 K, 1500 K and 1600 K. The properties, such as surface tension and surface concentration of the system have been computed at above mentioned temperatures using Butler model. The system shows transformation from segregating to ordering in nature with increase in concentration of Au.

Beyond activity coefficients with pairwise interacting surface (COSMO-type) models

Pairwise interacting surface models, like COSMO-RS and COSMO-SAC, are getting popular in the prediction of activity coefficients when experimental data is scarce. In this work an alternative derivation of the COSMO-SAC model is presented and pair contact probabilities as well as nonrandom factors are compared with classic models. By using these probabilities one can readily calculate the system internal energy (or enthalpy). The case of temperature dependent interaction energies and the potential inconsistencies in this case are discussed in detail. Many properties of the resulting equations are discussed, including the issue of distinguishable or indistinguishable segment types. An accompanying open-source code favoring readability over efficiency is also provided.

The state of the art of cubic equations of state with temperature-dependent binary interaction coefficients: From correlation to prediction

Cubic equations of state (CEoSs) are extensively used in academia and industry for their consistency, reliability, even under extrapolation conditions, and capacity to predict phase-equilibrium and energetic properties with acceptable accuracy. The optimal parametrization of a pure-component CEoS, a prerequisite for the development of any CEoS for mixtures, is discussed first. The binary interaction parameter (BIP) involved in the Van der Waals mixing rules of CEoSs is introduced with special attention to the temperature-dependent functions used to express it. The following questions are addressed: what is the physical meaning of the BIP? How does this parameter reveal deviations from ideal mixtures? What are the connections between Van der Waals and advanced (EoS/gE) mixing rules? What are the best methods to correlate this parameter? How can we predict it? In conclusion, the limitations and performances of models involving Van der Waals mixing rules, including BIPs, are examined and compared to the CEoSs based on advanced mixing rules.

Evaluation of cubic, PC-SAFT, and GERG2008 equations of state for accurate calculations of thermophysical properties of hydrogen-blend mixtures

Hydrogen (H2) is a clean fuel and key enabler of energy transition into green renewable sources and a method of achieving net-zero emissions by 2050. Underground H2 storage (UHS) is a prominent method offering a permanent solution for a low-carbon economy to meet the global energy demand. However, UHS is a complex procedure where containment security, pore-scale scattering, and large-scale storage capacity can be influenced by H2 contamination due to mixing with cushion gases and reservoir fluids. The literature lacks comprehensive investigations of existing thermodynamic models in calculating the accurate transport properties of H2-blend mixtures essential to the efficient design of various H2 storage processes. This work benchmarks cubic equations of state (EoSs), namely Peng–Robinson (PR) and Soave Redlich–Kwong (SRK) and their modifications by Boston–Mathias (PR-BM) and Schwartzentruber–Renon (SR-RK), for their reliability in predicting the thermophysical properties of binary and ternary H2-blend mixtures, including CH4, C2H6, C3H8, H2S, H2O, CO2, CO, and N2, in addition to Helmholtz-energy-based EoSs (i.e., PC-SAFT and GERG2008). The benchmarked models are regressed against the experimental data for vapor–liquid equilibrium (VLE) that covers a wide range of pressures (0.01 to 101 MPa), temperatures (92 K to 367 K), and mole fractions (0.001 to 0.90) of H2. The novelty of this work is in benchmarking and optimizing the parameters of the mentioned EoSs to study VLE envelopes, densities, and other critical transport properties, such as heat capacity and the Joule–Thomson coefficient of H2 mixtures in a wide range of associated conditions. The results highlight the significant effect of the temperature-dependent binary interaction parameters on the calculations of thermophysical properties. The SR-RK EoS demonstrated the highest agreement with VLE data among the cubic EoSs with a low root mean square error and absolute average deviation. The PC-SAFT VLE models demonstrated results comparable to the SR-RK. The sensitivity analysis highlighted the high influence of impurity on changing the thermophysical behavior of H2-blend streams during the H2 storage process.

High Temperature Stability of K-Pb Liquid Alloy

The study explores the thermo-physical properties of complex binary liquid potassium-lead alloy at temperature 848 K as a function of concentration by considering complex using different model equations. The Quasi Chemical approximation and the R-K equation are used to investigate features such as free energy, heat of mixing, chemical activity, and concentration fluctuation in the long wave limit at temperature of 848 K. However, at 900 K and 1000 K, these are exclusively examined using the R-K equation. The temperature dependent exponential interaction parameters proposed by Kaptay are taken into account in the RK equation. The study goes on to look at the alloy's viscosity and surface tension using the Budai-Benko-Kaptay model and the Kaptay's improved derivation of Butler equation. The mixing nature of the system is investigated in depth, with a focus on the interaction energy parameters between the alloy's surrounding atoms. The work investigates the fact that the liquid alloy has a moderately interacting as well as ordering character throughout a whole concentration range, and the computed theoretical thermodynamic facts are in reasonable agreement with the corresponding experimental data at 848 K. At greater temperatures, the alloy's tendency goes from ordering to segregating. The alloy's viscosity and surface tension decrease as the temperature rises.