Thermodynamic Properties Research Articles

Comparative analysis of multi-effect evaporators in an ammonium acetate concentration process for L-methionine production

The process of treating an acetic acid aqueous solution generated during L-methionine production with ammonia and recovering a highly concentrated ammonium acetate aqueous solution using a multi-effect evaporator process was studied. The electrolyte non-random two-liquid model was applied to calculate the activity in the electrolyte solution, and the Hayden-O’Connell model was used to consider the dimerization reaction of acetic acid in the vapor phase. The dissociation equilibrium constant of acetic acid was modeled based on experimental values, and all other thermodynamic property models and parameters were used as implemented in the Aspen Plus software. Economic evaluation was carried out with various sensitivity tests, considering the loss of acetic acid and ammonia, as well as the steam cost. Evaporator operation was found to be more economical when the molar ratio of acetic acid to ammonia was equal, feed concentration was high, feed flow rate was low, and evaporator temperature was low. These results were confirmed in actual plant operations, with significant correlations between the feed flow rate and evaporator temperature. Our findings have significant implications for the development of sustainable and economical L-methionine production methods that enable the recycling of ammonium acetate.

The disordering effect of SARMs on a biomembrane model.

From medicine to sport, selective androgen receptor modulators (SARMs) have represented promising applications. The ability of SARMs to selectively interact with the androgen receptor (AR) indicates that this kind of molecule can interfere with numerous physiological and pathological processes controlled by the AR regulatory mechanism. However, critical concerns in relation to safety and potential side effects of SARMs remain under discussion and investigation. SARMs, being hydrophobic/organic compounds, can be subjected to hydrophobic interactions. In this perspective, we hypothesize that SARMs interact with lipid membranes, producing significant physical and chemical changes that could be associated with several effects that SARMs represent in biological systems. In this context, the effect of SARMs on lipid membranes mediated by non-specific interactions is little explored. Here, we report significant information related to the changes that ostarine, ligandrol, andarine, and cardarine produce in the thermodynamic properties of a lipid biomembrane model. Physical changes and chemical interactions of the systems were investigated by differential scanning calorimetry (DSC), dynamic light scattering (DLS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and theoretical calculations implementing density functional theory (DFT). We demonstrate that ostarine, ligandrol, andarine, and cardarine can strongly interact with a lipid biomembrane model composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and accordingly, these molecules can be incorporated into the polar/hydrophobic regions of the lipid bilayer. By employing theoretical calculations, we gained insights into the possible electrostatic interactions between SARMs and phospholipid molecules, enhancing our understanding of the driving forces behind the interactions of SARMs with lipid membranes. Overall, this investigation provides relevant knowledge related to the biophysical-chemical effects that SARMs produce in biomembrane models and could be of practical reference for promising applications of SARMs in medicine and sport.

First-principles Calculation of Cumene: Molecular Structure, Electronic Structures, Spectroscopic Analysis, and Thermodynamic Properties

This study uses the DFT method for the investigation of optimized structure, electronic structures, charge analysis, FT-IR, FT-Raman spectroscopic analysis and thermodynamic properties. The optimized energy and dipole moment are 9531.775 eV and 0.3818 Debye. The bond lengths of C1-C2 and C1-H7 molecules inside the benzene ring are observed to be 1.39 Å and 1.08 Å respectively. The bond angle of C1-C2-C3 and C2-C1-C6 are found to be 120.10 Å and 119.36 Å. The HOMO-LUMO energy gap is 6.331 eV which corresponds very close to the energy gap of 6.321 eV obtained from density of states. The global parameters with ionization energy value 6.747 eV, electron affinity with 0.4152 eV, chemical potential with -3.5811 eV, electronegativity with 3.5811 eV, global hardness with 3.1659 eV, softness with 0.3148 eV-1 and electrophilicity index with 2.0253 eV are obtained. The Mulliken charges analysis indicate that most of the carbon atoms except C4 and C12 are found to carry negative charges where all of the H-atoms are found having positive charge. The molecular electrostatic potential, electrostatic potential and electron density identify different electrophilic and nucleophilic region and its reactive natures. The FT-IR spectroscopy shows strong C-H vibrations at 3186-3093 cm-1, methyl group vibration at 3091-3078 cm-1 and the ring vibrations at 1641-1482 cm-1. The heat capacity at constant volume and at constant pressure, internal energy, enthalpy, entropy increase with increasing temperature. However, Gibb’s free energy shows opposite nature providing very important insights according to the change in temperature.

Crystal Structure Prediction and Performance Assessment of Hydrogen Storage Materials: Insights from Computational Materials Science

Hydrogen storage materials play a pivotal role in the development of a sustainable hydrogen economy. However, the discovery and optimization of high-performance storage materials remain a significant challenge due to the complex interplay of structural, thermodynamic and kinetic factors. Computational materials science has emerged as a powerful tool to accelerate the design and development of novel hydrogen storage materials by providing atomic-level insights into the storage mechanisms and guiding experimental efforts. In this comprehensive review, we discuss the recent advances in crystal structure prediction and performance assessment of hydrogen storage materials from a computational perspective. We highlight the applications of state-of-the-art computational methods, including density functional theory (DFT), molecular dynamics (MD) simulations, and machine learning (ML) techniques, in screening, evaluating, and optimizing storage materials. Special emphasis is placed on the prediction of stable crystal structures, assessment of thermodynamic and kinetic properties, and high-throughput screening of material space. Furthermore, we discuss the importance of multiscale modeling approaches that bridge different length and time scales, providing a holistic understanding of the storage processes. The synergistic integration of computational and experimental studies is also highlighted, with a focus on experimental validation and collaborative material discovery. Finally, we present an outlook on the future directions of computationally driven materials design for hydrogen storage applications, discussing the challenges, opportunities, and strategies for accelerating the development of high-performance storage materials. This review aims to provide a comprehensive and up-to-date account of the field, stimulating further research efforts to leverage computational methods to unlock the full potential of hydrogen storage materials.

Unusual dynamics of tetrahedral liquids caused by the competition between dynamic heterogeneity and structural heterogeneity.

Tetrahedral liquids exhibit intriguing thermodynamic and transport properties because of the various ways tetrahedra can be packed and connected. Recently, an unusual temperature dependence of the stretching exponent β in a model tetrahedral liquid ZnCl2 from Tm + 85K to Tm + 35K has been reported using neutron-spin echo spectroscopy. This discovery stands in sharp contrast to other glass-forming liquids. In this study, we conducted neural network force field driven molecular dynamic simulations of ZnCl2. We found a non-monotonic temperature dependence of β from liquid to supercooled liquid temperatures. Further structural decomposition and dynamic analysis suggest that this unusual dynamic behavior is a result of the competition between the decrease in the diversity of tetrahedra motifs (structural heterogeneity) and the increase in glassy dynamic heterogeneity. This result may contribute to new understandings of the structural relaxation of other network liquids.

Pressure and speed of sound in two-flavor color-superconducting quark matter at next-to-leading order

Deconfined quark matter at asymptotically high densities is weakly coupled, due to the asymptotic freedom of quantum chromodynamics. In this weak-coupling regime, bulk thermodynamic properties of quark matter, assuming a trivial ground state, are currently known to partial next-to-next-to-next-to-leading order. However, the ground state at high densities is expected to be a color superconductor, in which the excitation spectrum of (at least some) quarks exhibit a gap with a nonperturbative dependence on the strong coupling. In this work, we calculate the thermodynamic properties of color-superconducting quark matter at high densities and zero temperature at next-to-leading order (NLO) in the coupling in the presence of a finite gap. We work in the limit of two massless quark flavors, which corresponds to deconfined symmetric nuclear matter, and further assume that the gap is small compared to the quark chemical potential. In these limits, we find that the NLO corrections to the pressure and speed of sound are comparable in size to the leading-order effects of the gap, and further increase both quantities above their values for nonsuperconducting quark matter. We also provide a parametrization of the NLO speed of sound to guide phenomenology in the high-density region, and we furthermore comment on whether our findings should be expected to extend to the case of three-flavor quark matter of relevance to neutron stars. Published by the American Physical Society 2024

Fixed-node diffusion Monte Carlo shows promise for modeling reaction thermochemistry of hydrocarbon-based radicals.

Reliable thermodynamic and kinetic properties of free radical polymerization reactions are essential for synthesizing both primary polymeric materials and specialty polymers. The computational generation of these data from quantum chemistry requires a time-efficient method capable of capturing the essential physics. One such method, fixed-node diffusion Monte Carlo (FN-DMC) (using single Slater-Jastrow trial wavefunctions), has demonstrated the capability to recover 90%-95% of missing dynamic correlation energy for typical systems. In this study, methyl radical addition to ethylene serves as a simple model to test FN-DMC's ability to calculate enthalpies of reaction and activation energies with different time steps, antisymmetric trial wavefunctions, basis set sizes, and effective core potentials. The FN-DMC computational protocol thus defined for methyl radical addition to ethylene is subsequently benchmarked against Weizmann-1 and experimental reaction enthalpies from Lin et al.'s test set of 21 radical addition and 28 hydrogen abstraction enthalpies. Our findings reveal that FN-DMC consistently generates reaction enthalpies with chemical accuracy, exhibiting mean absolute deviation of 3.5(7) and 1.4(8) kJ/mol from the Weizmann-1 reference for radical addition and hydrogen abstraction reactions, respectively. Given its favorable computational scaling and high degree of parallelizability, we, therefore, recommend more comprehensive testing of FN-DMC with effective core potentials to address more extensive and intricate polymerization reactions and reactions with other radicals.

Enhancing Bioactivity through the Transfer of the 2-(Hydroxymethoxy)Vinyl Moiety: Application in the Modification of Tyrosol and Hinokitiol.

Utilizing Density Functional Theory (DFT) calculations at the B3LYP/QZVP level and incorporating the Conductor-like Polarizable Continuum Model (C-PCM) for solvation, the thermodynamic and chemical activity properties of 21-(hydroxymethoxy)henicosadecaenal, identified in cultured freshwater pearls from the mollusk Hyriopsis cumingii, have been elucidated. The study demonstrates that this compound releases formaldehyde, a potent antimicrobial agent, through dehydrogenation and deprotonation processes in both hydrophilic and lipophilic environments. Moreover, this polyenal exhibits strong anti-reductant properties, effectively scavenging free radicals. These critical properties classify the pearl-derived ingredient as a natural multi-functional compound, serving as a coloring, antiradical, and antimicrobial agent. The 2-(hydroxymethoxy)vinyl (HMV) moiety responsible for the formaldehyde release can be transferred to other compounds, thereby enhancing their biological activity. For instance, tyrosol (4-(2-hydroxyethyl)phenol) can be modified by substituting the less active 2-hydroxyethyl group with the active HMV one, and hinokitiol (4-isopropylotropolone) can be functionalized by attaching this moiety to the tropolone ring. A new type of meso-carrier, structurally modeled on pearls, with active substances loaded both in the layers and the mineral part, has been proposed.

Martini 3 Coarse-Grained Model for the Cofactors Involved in Photosynthesis.

As a critical step in advancing the simulation of photosynthetic complexes, we present the Martini 3 coarse-grained (CG) models of key cofactors associated with light harvesting (LHCII) proteins and the photosystem II (PSII) core complex. Our work focuses on the parametrization of beta-carotene, plastoquinone/quinol, violaxanthin, lutein, neoxanthin, chlorophyll A, chlorophyll B, and heme. We derived the CG parameters to match the all-atom reference simulations, while structural and thermodynamic properties of the cofactors were compared to experimental values when available. To further assess the reliability of the parameterization, we tested the behavior of these cofactors within their physiological environments, specifically in a lipid bilayer and bound to photosynthetic complexes. The results demonstrate that our CG models maintain the essential features required for realistic simulations. This work lays the groundwork for detailed simulations of the PSII-LHCII super-complex, providing a robust parameter set for future studies.

Control of spin on structural stability, mechanical, magneto-optoelectronic and thermodynamic properties of RbTaX (X =P and As) materials: Emerging candidates for opto-spintronics and spin filter applications

In the present work, the density functional theory has been utilised in inspecting the ground state-structural, electronic, magnetic, optical, elastic and thermodynamic properties of new semiconductor RbTaX (X = P and As) half-Heuslers. Out of the possible three structures (α, β, γ) studied in ferromagnetic (FM) as well as non-magnetic (NM) phases, α – FM phase is found to be the most stable configuration. Both studied materials have estimated a net magnetic moment of 3μB, following the Slater-Pauling rule (Mtot=Ztot−8). With the use of modified Becke Johnson potential (mBJ) potential, the band profile reveals non-zero band gap in the spins and henceforth display spin filter property in the compounds. The predicted energy band gaps for RbTaP and RbTaAs are 3.04 and 2.87 eV for minority spin channels and 0.137 and 0.26 eV for majority spin channels, respectively. This unique feature of the Heusler compound may be advantageous for quantum information processing and spin-transport in electronic and magnetic devices. Also, a moderate exchange splitting and a Curie temperature well above the room temperature are noted. The stability of the materials under investigation was further confirmed by calculations of cohesive energy, formation energy, and second order elastic constants. The optoelectronic as well as thermodynamic properties of the studied compounds are also investigated. The estimated high value of refractive index (>4) is making them suitable for optical lenses. Moreover, photon energy absorption in the visible and ultraviolet spectrums renders them valuable for UV-VIS absorbers.

Two-dimensional pair-interacting hole gas thermodynamics: Exactly solvable Moshinsky model for lens-shaped quantum dots

The thermodynamic characteristics of a pair-interacting hole gas localized in a Ge/Si lens-shaped quantum dot are studied. The pair-interaction potential is modeled by the oscillator function, which depends on the distance between the particles. The analytical form of the spectra makes it possible to calculate the partition function in Boltzmann approximation. Based on the partition function mean and free energies, heat capacity and entropy of the interacting gas are calculated. Interaction between particles substantially changes the behavior of the thermodynamic properties in comparison with the non-interacting gas case. In particular, the gas undergoes a first-order phase transition driven by the height of the upper (or lower) section of QD, resulting in a changing symmetry of the lens-shaped QD.

Electrolytes for solid state lithium batteries in the [N13pip]ClO4-LiClO4-Al2O3 system for solid state lithium batteries

The transport, electrochemical, structural, and thermal properties of electrolytes in the ternary system [N13pip]ClO4-LiClO4-γ-Al2O3 (N13pip is N-methyl-N-ethyl-piperidinium cation) were investigated at the molar ratio [N13pip]ClO4:LiClO4 = 0.82:0.18. The addition of alumina leads to a change in the thermodynamic properties of the [N13pip]ClO4-LiClO4 system that can be explained by a partial transfer of lithium perchlorate from the organic phase to the surface of γ-Al2O3. The highest ionic conductivity of 6.2∙10–4 S/cm at 110 °C was observed for the composition containing the volume fraction (f) of γ-Al2O3 equal to 0.5. The increase in conductivity compared to the binary system 0.82[N13pip]ClO4-0.18LiClO4 is achieved due to the amorphization of the organic salt near the salt/LiClO4/oxide interfaces. Galvanostatic cycling with Li electrodes shows that composites with f = 0.5 are stable at 110 °C for at least 68 charge/discharge cycles, and the electrolyte is shown to be electrochemically stable up to 5 V. This system can be used as a solid-state electrolyte in lithium-ion current sources.

Effect of pressure on electronic, magnetic, thermodynamic and thermoelectric properties of RbNpF3 perovskite

This paper delves into an examination of the structural, electronic, magnetic, thermal, and transport properties of RbNpF3 perovskite using first-principle calculations within density functional theory (DFT). Employing the Birch Murghanan's equation of state the geometric optimization of structure confirms the cubic configuration with the Pm-3m (No. 221) space group and stability in ferromagnetic phase. Effect of high pressure on electronic and magnetic properties was also studied. Electronic band structure and density of states assessments confirm metallic character over a wide range of pressure. Furthermore, for the examined compound we have calculated the heat capacity, thermal expansion coefficients and Grüneisen parameter by using the Debye model. We have also calculated the different transport parameters like Seebeck coefficient, electrical conductivity, thermal conductivity and power factor as a function of temperature. These parameters indicate the potential application of the material for generating thermoelectric energy.

Thermal analysis of five flat air solar collectors in Epinal (France) using modelling and simulation

ABSTRACT The purpose of this study is to investigate the effect of the position of the solar collector absorber and stagnant air relative to the airflow path on the thermodynamic properties of traversing air and the overall thermal performance of the collector. A numerical model was developed and validated using five different absorber design positions. Numerical results are validated using experimental data obtained from Epinal (France). The model was subsequently used to parametrically study the influence of these absorber positions on the density, temperature, velocity variations of the airflow through the collector and the thermal efficiency of each case scenario. The study showed the importance of stagnant air in solar collector thermal performance. Also, it showed that when one absorber is used, it is better to locate the absorber on the top of the airflow path than below the airflow path. Sandwiching the airflow path between double absorbers with the upper absorbers having stagnant air between it and the plexiglass cover and the down absorber having stagnant air between it and the bottom of the collector can produce a thermal efficiency of 31% which is 2% higher than the closest case and 13% higher than the worst-case design.

Effects of Solute Concentrations on Thermodynamic Properties of Lake Victoria Waters

Effects of Solute Concentrations on Thermodynamic Properties of Lake Victoria Waters

K2Ag(Ga/In)Br6 lead-free HDPs: Investigation of the elastic, optoelectronic, optical coating, and thermal characteristics for thermoelectric and solar cells

In this study, an investigation of the structural stability, elastic, optoelectronic, thermoelectric, optical thin-film coating, and thermodynamic properties of K2Ag(Ga/In)Br6 (lead-free halide double perovskites, HDPs) was performed using first-principles calculations. The optimized structural parameters are in good agreement with the available data. Furthermore, Goldsmith's tolerance factor indicates an ideal value for both double perovskites, ensuring the structural stability of the cubic perovskites, and the elasticity parameters were analyzed to ensure the mechanical stability of the cubic phase. Direct and reduced band gaps of 0.4524 eV and 1.064 eV with semiconductor behavior are found for K2AgGaBr6 and K2AgInBr6, respectively, through adoption of the modified Becke–Johnson potential scheme. The absorption coefficient, refractive index, and dielectric function, as some of the optical properties, in addition to the optical thin-film properties, are well discussed, and the values suggest that these materials are promising candidates for different devices, such as optoelectronic and photovoltaic energy devices. In terms of the thermodynamics, the HDPs display favorable characteristics across various temperature and pressure ranges. Additionally, we assessed the thermoelectric properties, considering the power factor, Seebeck coefficient, thermal and electronic conductivities, and figure of merit. The current predictions suggest that these lead-free halide double perovskites have strong potential for application in thermoelectricity and photovoltaics.

Unravelling the thermodynamic properties of soil ecosystems in mature beech forests

Thermodynamics is a vast area of knowledge with a debatable role in explaining the evolution of ecosystems. In the case of soil ecosystems, this role is still unclear due to difficulties in determining the thermodynamic functions that are involved in the survival and evolution of soils as living systems. The existing knowledge is largely based on theoretical approaches and has never been applied to soils using thermodynamic functions that have been experimentally determined. In this study, we present a method for the complete experimental thermodynamic characterization of soil organic matter. This method quantifies all the thermodynamic functions for combustion and formation reactions which are involved in the thermodynamic principles governing the evolution of the universe. We applied them to track the progress of soil organic matter with soil depth in mature beech forests. Our results show that soil organic matter evolves to a higher degree of reduction as it is mineralized, yielding products with lower carbon but higher energy content than the original organic matter used as reference. These products have higher entropy than the original one, demonstrating how the soil ecosystem evolves with depth, in accordance with the second law of thermodynamics. The results were sensitive to soil organic matter transformation in forests under different management, indicating potential applicability in elucidating the energy strategies for evolution and survival of soil systems as well as in settling their evolutionary states.

Thermodynamic properties of [formula omitted] double quantum wire in the presence of impurity and Rashba spin-orbit interaction

We investigate the effects of impurities and Rashba spin-orbit interaction on the thermodynamic properties in the InxGa1−xN double quantum wire. The energy and eigenvectors of our system are obtained through analytical diagonalization in the presence of external fields, Rashba spin-orbit interaction, and impurities. These energy levels are used to analyse the entropy, mean energy, heat capacity, and free energy of the InxGa1−xN double quantum wire. The system's entropy increases with temperature and Rashba spin-orbit interaction but decreases with impurity. At low temperatures, entropy appears weakly dependent on impurity and exhibits minimal dependence on it. The heat capacity shows a peak structure and rises as impurity and the Rashba spin-orbit interaction increase at low temperatures. At low temperatures, the system's mean energy gradually increases. As the temperature rises, the mean energy becomes independent of interaction strength and increases more rapidly. The mean energy decreases with increasing impurity and Rashba spin-orbit interaction. The thermodynamic properties of our system, such as entropy, heat capacity, mean energy, and free energy, make it suitable for applications in electronics (such as the fabrication of energy storage devices and transistors), industry (such as the operation of magnetic levitation trains), and medicine (such as MRI).

Enhanced mechanical and thermophysical properties of Mg2Ca, Al2Ca, and Al4Ca bulk metallic glasses in comparison to crystalline alloys for bone grafting applications: A molecular dynamics investigation

We investigate the glassy-state properties of Mg2Ca, Al2Ca, and Al4Ca from the grafting application viewpoint. We employed classical molecular dynamics to examine the phase transition, structural, thermodynamic, transport, and mechanical properties in the amorphous state. All properties suggest successful simulations of the glass phase at and below the glass transition temperature, ranging between 550 and 689 K for Mg2Ca, Al2Ca, and Al4Ca. Computed results are compared and discussed with the reported findings and known mechanical and thermal properties of the various parts of the human bones and biocomposites. The comparison establishes that the mechanical, thermal, and transport properties significantly improve in the glass phase compared to its crystalline alloy form. At 300 K, studied glasses have densities in close agreement with human bone density. Structural analysis and heat capacity show the second-order phase transition, verifying the formation of the glass structure. The targeted glasses exhibit excellent thermal conductivity and thermal diffusivity compared to other commonly used biocomposites for bone grafting. Furthermore, the simulated elastic properties, viz., the Poisson ratio, G/B ratio, Cauchy's pressure, and yield strength, are in close agreement with the mechanical properties of various parts of human bone. The predicted ductility nature, contrary to the brittle character of Mg2Ca, Al2Ca, and Al4Ca crystalline alloys, proves the superiority of the glassy form for the implant's functioning. The minimum enthalpy of formation and thermodynamic stability of studied compounds benefit the synthesis process; hence, we propose that the studied glasses are persuasive materials for experimental synthesis aimed at bone grating applications.

Comparative analysis of KXH3(X= Mg, be) hydride cubic perovskites for hydrogen storage properties: A computational approach

The burgeoning potential of hydrogen as a future clean energy source has spurred intense research into hydrogen storage solutions. Novel hydride perovskite materials aside metal hydride are at the forefront of this effort, engaging researchers worldwide. This study utilizes Ab-initio calculations based on density functional theory (DFT) implemented in VASP to compare the electrical, elastic, thermodynamic, and optical properties of cubic KXH3 (X = Mg, Be) compounds. Generalized gradient approximation (GGA) with the Perdew-Burke-Ernzrhof (PBE) scheme is employed for optimization. Our calculations agree well with previously reported results. However, the tolerance factor suggests KBeH3 may not be stable in the cubic form. The electronic structure reveals KMgH3 to be semiconductive, while KBeH3 exhibits metallic behavior. Both compounds exhibit mechanical stability within the study. Optical properties are also investigated, showing suitability for hydrogen storage in the low energy range. Additionally, the mechanical parameters satisfy the Born stability criterion, indicating good mechanical stability for both compounds. Finally, the gravimetric ratios for hydrogen storage are calculated as 5.86 wt% and 4.52 wt% for KMgH3 and KBeH3, respectively. These high values suggest both compounds hold significant promise for diverse renewable energy applications and long-term hydrogen fuel storage.