Thermodynamic Approach Research Articles

Divergent Adsorption Regulation in Metal-Organic Frameworks for Highly Efficient CF4/C2F6 Separation.

The efficient removal of low-concentration components from homologous mixtures is often hampered by the co-directional effect of traditional thermodynamic regulation approaches, typically leading to a trade-off between adsorption capacity and selectivity. Focusing this challenge on the critical task of purifying perfluorocarbons in electronics industry, a divergent regulation strategy is reported that significantly improves the separation efficiency of low-concentration hexafluoroethane (C2F6) from tetrafluoromethane (CF4). This approach involves the selective shielding of open metal sites and the modulation of channel geometry within an electron-deficient ligand-based pore environment, thereby facilitating a C2F6 dense-packing accommodation mode while weakening the CF4 affinity due to the reduced host-guest interactions. Simultaneously enhanced C2F6 adsorption and reduced CF4 adsorption are achieved, resulting in record-high low-pressure C2F6 uptake and C2F6/CF4 selectivity. Comprehensive insights into the unique separation mechanism are illustrated through a combination of solid-state MAS nuclear magnetic resonance(SSNMR), molecular simulations, and meticulously designed comparative experiments. As a result, benchmark C2F6/CF4 separation performance is achieved, as demonstrated by the unprecedented electronic-grade (over 99.999%) CF4 productivity (401 L kg-1) obtained from an industrially relevant C2F6/CF4 (3:97) mixture, as well as the excellent water/air/heat stability and recyclability.

Phase transitions, shadows, and microstructure of Reissner-Nordström-Anti-de-Sitter black holes from a geometrothermodynamic perspective

We study the thermodynamic properties of the Reissner-Nordström black hole with cosmological constant, expressed in terms of the curvature radius, using the approach of shadow thermodynamics and the formalism of geometrothermodynamics. We derive explicit expressions for the shadow radius in terms of the horizon, photon sphere, and observer radii. The phase transition structure turns out to strongly depend on the value of the curvature radius, including configurations with zero, one, or two phase transitions. We also analyze the black hole's microscopic structure and find differences between the approaches of thermodynamic geometry and geometrothermodynamics, which are due to the presence of the curvature radius. We impose the important condition that the black hole is a quasi-homogeneous thermodynamic system to guarantee the consistency of the geometrothermodynamic approach.

Evaluation of the efficiency of shell powder as a natural adsorbent for the adsorption of chromium in aqueous solutions: kinetic and thermodynamic approach and modeling of adsorption isotherms

Water pollution by heavy metals such as chromium is a major environmental issue requiring effective remediation solutions. In this study, shellfish powder was used as a natural material to adsorb chromium (III) from aqueous solutions. The results show that shellfish have a significant adsorption capacity, indicating their effectiveness under a variety of conditions. Adsorption kinetics tests showed that the adsorption mechanism followed a pseudo-second-order kinetic model. In addition, thermodynamic parameters show that the adsorption process is a beneficial, spontaneous and endothermic phenomenon. Isotherm models such as Langmuir, Freundlich and Temkin were applied to analyze adsorption behavior. This research could contribute to the development of more sustainable wastewater treatment methods, incorporating natural materials into remediation strategies.

Studies of the Novel Bioactive Acridine‐1,3‐thiazolidin‐4‐one Derivatives With Human Serum Albumin Using Fluorescence Spectroscopy and Molecular Modelling

ABSTRACTIn this study, we employ spectroscopic, thermodynamic and molecular docking approaches to identify the mechanism by which thiazolidinone derivatives 4a–4d bind with human serum albumin. It has been suggested that the affinity of the interaction of derivatives 4a–4d with HSA is within the optimal range necessary for the transportation and distribution of compounds within the organism. The binding constant values for the derivative/HSA complexes were found to be 0.03–5.87 × 105 M−1. Both ΔH0 and ΔS0 values were negative, which indicates that binding occurs mainly through van der Waals forces and hydrogen bonding. The negative values calculated for ΔG0 indicate that the binding of derivatives 4a–4d with HSA is a spontaneous process. Our study also reveals that derivatives 4a–4d bind to the subdomain IB (Site III) of HSA and that this binding alters the conformation and thermodynamic stability of HSA. Molecular docking simulations suggest that the main binding forces are van der Waals interactions, hydrophobic interactions and hydrogen bonds. The studied compounds showed weak DPPH‐scavenging activity at all of the tested concentrations. The results suggest that compound 4b with a phenyl substituent at the nitrogen atom of the 1,3‐thiazolidin‐4‐one moiety can be considered the most potent antioxidant in the series.

Innovative Chitosan/Graphene Oxide Composites: A Thermodynamic and Calorimetric Approach to Pharmaceutical Waste Removal from Water

Innovative Chitosan/Graphene Oxide Composites: A Thermodynamic and Calorimetric Approach to Pharmaceutical Waste Removal from Water

Physics-coupled Data-driven Design of High-Temperature Alloys

We present a materials design loop, which streamlines physics-coupled machine learning (ML) surrogate models to discover new alloy chemistries with improved properties. The efficacy is demonstrated by discovering a high-temperature alumina-forming austenitic (AFA) stainless steel with enhanced creep, followed by experimental validation. The ML models have been trained using a well-curated, highly consistent experimental dataset augmented with synthetic microstructural features from a computational thermodynamic approach. We have populated a large number of hypothetical AFA alloys to explore the high-dimensional composition space and have predicted their creep properties by providing the same synthetic input features obtained from the trained ML models. Uncertainties from the ML training were taken as thresholds for truncating predicted results to identify alloys with improved or deteriorated creep. Individual elemental compositions have been determined via probability density distribution analysis from the group of alloys at the top and bottom of the predicted creep values for further virtual and experimental validations. We anticipate that this workflow can be applied to screen desired conditions, such as chemistry and processing parameters, in high-dimensional space through physics-guided data analytics.

Predictions of the interfacial free energy along the coexistence line from single-state calculations.

The calculation of the interfacial free energy between two thermodynamic phases is crucial across various fields, including materials science, chemistry, and condensed matter physics. In this study, we apply an existing thermodynamic approach, the Gibbs-Cahn integration method, to determine the interfacial free energy under different coexistence conditions, relying on data from a single-state calculation at specified pressure and temperature. This approach developed by Laird et al. [J. Chem. Phys. 131, 114110 (2009)] reduces the computational demand and enhances efficiency compared to methods that require separate measurements at each thermodynamic state. The integration scheme computes the excess interfacial free energy using unbiased constant volume, temperature, and number of particle simulations (NVT), where the two phases coexist, to provide input for the calculations. We apply this method to the Lennard-Jones and mW water models for liquid-solid interfaces, as well as the Lennard-Jones and TIP4P/2005 models for liquid-vapor interfaces. Our results demonstrate the accuracy and effectiveness of this integration route for estimating the interfacial free energy along a coexistence line.

Influence of the grain size on the martensitic transformation and strain nanodomains in the Ti-Hf-Ni-Cu shape memory alloy

The martensitic transformation and strain nanodomain were studied in the Ti40.7Hf9.5Ni44.8Cu5 shape memory alloy, whose grain size varied from 130 μm to 160 nm. The largest average grain size (600 μm in length and 130 μm in diameter) was found in the CAST sample. The grains with the smallest size (160 nm) formed during the crystallisation of thin ribbons obtained by the melt spinning technique from the Ti40.7Hf9.5Ni44.8Cu5 ingot (labelled as RIBBON). The average grain size (16 μm) was observed in the sample subjected to high-pressure torsion and post-deformation annealing (labelled as HPT). It was found that the CAST and HPT samples included the NiTi-based matrix and the Ti2Ni-type precipitates, whereas the RIBBON sample contained the NiTi-based matrix only. Regardless of the grain size, all samples underwent the B2 ↔ B19’ transformation on cooling and heating. A decrease in grain diameter from 130 μm to 160 nm decreased the transformation temperatures by more than 100 °C but did not affect the sequence of the transformation. The strain nanodomains formed in all samples on cooling prior to the forward martensitic transformation. The smaller the grain size, the larger the temperature range of the strain nanodomain existence. On heating of HPT and RIBBON samples, the B19 phase transformed to the B2 phase with strain nanodomains, which disappeared only on heating over 120 °C. The influence of grain size on the martensitic transformation and strain nanodomains was analysed from the thermodynamics approach.

Chemistry at Oxide/Water Interfaces: The Role of Interfacial Water.

Oxide-water interfaces host many chemical reactions in nature and industry. There, reaction free energies markedly differ from those of the bulk. While we can experimentally and theoretically measure these changes, we are often unable to address the fundamental question: what catalyzes these reactions? Recent studies suggest that surface and electrostatic contributions are an insufficient answer. The interface modulates chemistry in subtle ways. Revealing them is essential to understanding interfacial reactions, hence improving industrial processes. Here, we introduce a thermodynamic approach combined with cavitation free energy analysis to disentangle the driving forces at play. We find that water dictates chemistry via large variations of cavitation free energies across the interface. The resulting driving forces are both large enough to determine reaction output and highly tunable by adjusting interface composition, as showcased for silica-water interfaces. These findings shift the focus from common interpretations based on surface and electrostatics and open exciting perspectives for regulating interfacial chemistry.

Efficiency Analysis and Optimization of Two-Speed-Region Operation of Permanent Magnet Synchronous Motor Taking into Account Iron Loss Based on Linear Non-Equilibrium Thermodynamics

In this article, the linear non-equilibrium thermodynamic approach is used to mathematically describe the energy regularities of an interior permanent magnet synchronous motor (IPMSM), taking into account iron loss. The IPMSM is considered a linear power converter (PC) that is multiple-linearized at operating points with a given angular velocity and load torque. A universal description of such a PC by a system of dimensionless parameters and characteristics made it possible to analyze the perfection of energy conversion in the object. For IPMSM, taking into account iron loss, a mathematical model of the corresponding PC has been built, and an algorithm and research program have been developed, which is valid in a wide range of machine speed regulations. This allows you to choose the optimal points of PC operation according to the maximum efficiency criteria and obtain the efficiency maps for IPMSM in different speed regions. The results of the studies demonstrate the effectiveness of the proposed method for determining the references of the d and q components of the armature current for both the loss-minimization strategy at the constant torque range of motor speed and the flux-weakening strategy in the constant power range.

Cogeneration processes based on giant reed gasification combined with ORC and district heating for heat recovery: Comparative energy and exergy analysis

This research work develops a comprehensive exergy and energy assessment of a cogeneration process using Giant Reed as feedstock, which consists of a biomass dryer, a fluidized bed gasifier, an internal combustion engine operating in a cogeneration mode (CHP), and two different users for the cogenerated heat. One process layout uses cogenerated heat in a district heating network (CHP + DH layout). In the second process layout, the cogenerated heat produces additional electricity through an Organic Rankine Cycle (CHP + ORC layout). In addition to the performance of reed gasification (cold gas efficiency about 0.6), the results showed that the highest rational efficiency was reached in the cogeneration unit, while the highest relative irreversibilities were found in the gasifier and the dryer. The overall energy efficiencies are 0.46 and 0.22 for the CHP + DH and CHP + ORC layouts, respectively, while the overall exergy efficiencies are 0.21 and 0.20. The difference in the sustainability index is just 2 %. The results and methods of this research work can be used to properly design Giant Reed (or similar biomass) gasification plants and bioenergy systems for combined heat and power production, and developing case-studies considering the sustainable use of this feedstock according to a thermodynamic approach based on the second principle.

Hyperon Production in Bi + Bi Collisions at the Nuclotron-Based Ion Collider Facility and Angular Dependence of Hyperon Spin Polarization

The strange baryon production in Bi + Bi collisions at sNN=9.0 GeV is studied using the PHSD transport model. Hyperon and anti-hyperon yields, transverse momentum spectra, and rapidity spectra are calculated, and their centrality dependence and the effect of rapidity and transverse momentum cuts are studied. The rapidity distributions for Λ¯, Ξ, Ξ¯ baryons are found to be systematically narrower than for Λs. The pT slope parameters for anti-hyperons vary more with centrality than those for hyperons. Restricting the accepted rapidity range to |y|<1 increases the slope parameters by 13–30 MeV, depending on the centrality class and the hyperon mass. Hydrodynamic velocity and vorticity fields are calculated, and the formation of two oppositely rotating vortex rings moving in opposite directions along the collision axis is found. The hyperon spin polarization induced by the medium vorticity within the thermodynamic approach is calculated, and the dependence of the polarization on the transverse momentum and rapidity cuts and on the centrality selection is analyzed. The cuts have stronger effect on the polarization of Λ and Ξ hyperons than on the corresponding anti-hyperons. The polarization signal is maximal for the centrality class, 60–70%. We show that, for the considered hyperon polarization mechanism, the structure of the vorticity field makes an imprint on the polarization signal as a function of the azimuthal angle in the transverse momentum plane, ϕH, cosϕH=px/pT. For particles with positive longitudinal momentum, pz>0, the polarization increases with cosϕH, while for particles with pz<0 it decreases.

Thermodynamic study on the phase assemblage of MPC exposed to natural and accelerated carbonation conditions

AbstractMagnesium phosphate cement (MPC), which belongs to chemically bonded phosphate ceramics, is commonly applied as a repair material and waste stabilization/solidifications. However, studies on the influence of CO2 on the phase assemblages in MPC are limited. A thermodynamic simulation approach is employed to explore the influence of CO2 on the equilibrium phase assemblage of MPC. The mechanisms of natural and enforced carbonation of MPC have been investigated in this work. The results disclose that Mg carbonates are less likely to precipitate in magnesium ammonium phosphate cement (MAPC) cured under CO2, while MgCO3·3H2O is the only carbonation product of magnesium potassium phosphate cement (MKPC). The carbonation resistance of MAPC is better than that of MKPC. The increase of activity of magnesia employed in MPC obviously enhances the formation of brucite and slightly promotes the carbonation of MPC.

Pop the bubbles and let the current flow: mechanochemistry of micron and nano-sized openings in dielectric layers

Thin or ultra-thin dielectric layers have been widely used in various applications such as capacitors, piezo-electrics, and solar cells. This study explains the mechanism and chemistry of creating nano- and micron-sized openings in atomic-layer-deposited aluminum oxide-based dielectric layers using the alkali metal salt selenization technique. The necessary components for this mechanism are excess methyl groups present in the dielectric layer, supply of selenium and alkali metals, and a minimum annealing temperature. It is shown and explained that to create openings in the dielectric layer, heavier alkali halide metal salts require less energy, or - in other words - a lower annealing temperature. The overall hypothesis is explained via a thermodynamic approach with supportive thermochemical reactions. Thus, an easy way to engineer the dielectric layer to form openings at low temperatures is presented, beneficial for various applications like photovoltaics, optoelectronics, or micro-electro-mechanical systems (MEMS).

Thermodynamic and Kinetic Analysis of TiN Precipitation in Nickel-Based Superalloys During Solidification.

Large TiN inclusions in nickel-based superalloys promote micropore formation, compromising the mechanical properties of the alloys. However, current research lacks a comprehensive coupled model that considers both solute element microsegregation and TiN precipitation specifically in nickel-based superalloys. This study investigated TiN precipitation during the solidification of IN718 alloys through a combined thermodynamic and kinetic approach. A modified Clyne-Kurz model was applied to account for multi-element microsegregation, enabling an integrated analysis of both microsegregation and precipitation processes. The results indicated that solute elements in the molten alloy segregated to varying degrees during solidification. At an initial nitrogen concentration of 25 ppm, TiN inclusions precipitated when the solid fraction reached 0.256, eventually resulting in a total TiN precipitation of 64 ppm by the end of solidification, while residual nitrogen in the liquid phase decreased to 1.3 ppm. Increasing the initial nitrogen concentration from 10 ppm to 40 ppm advanced the onset of TiN precipitation and raised the total amount from 16 ppm to 126 ppm. Further analysis indicated that cooling rates of 0.03 °C/s, 0.06 °C/s, and 0.18 °C/s did not significantly affect the final TiN accumulation.

Thermophysical Insights into the Anti-Inflammatory Potential of Magnetic Fields.

Background: Inflammation is caused by an excess of Sodium ions inside the cell. This generates a variation in the cell's membrane electric potential, becoming a steady state from a thermodynamic viewpoint. Methods: This paper introduces a thermodynamic approach to inflammation based on the fundamental role of the electric potential of the cell membrane, introducing an analysis of the effect of heat transfer related to the inflammation condition. Results: The direct proportionality between the reduction in temperature and the increase of Na+ outflow may ameliorate the inflammation cascade. Conclusions: Based on these ion fluxes, we suggest the consideration of a 'companion' electromagnetic therapeutic wave concept in support of the present anti-inflammatory treatment.

Atomic‐Level Structural Responses of Chang'e‐5 Ilmenite to Space Weathering

AbstractSpace weathering records provide insights to better understand the formation and evolution of the lunar regolith. Ilmenite has contrasting responses to different space weathering processes. However, the atomic‐scale structural modification of ilmenite induced using different space weathering processes remains poorly understood. Here, we investigate the effects of spacing weathering on lunar ilmenite grains returned from Chang'e‐5 (CE‐5) mission using a combination of transmission electron microscopy and thermodynamic modeling approaches. Experimental results show that melt shock induces the formation of twining structures and vein‐like Si‐Ca‐rich nanostructures in the outermost and sub‐outermost layers of ilmenite, respectively. In contrast, solar wind causes the formation of multilayered nanostructures surrounding the ilmenite grains. These structures are characterized by an outermost amorphous Si‐rich vapor deposited layer, a middle layer rich in titanium (Ti) oxides and zero‐valent iron (Fe0) nanoparticles, and an innermost layer hosting crystallographic orientation defect. The Ti oxides were identified as poorly crystallized anatase. Thermodynamic calculations indicate that the disruptive sputtering of solar wind and the reduction of hydrogen under lunar surface pressure conditions can promote ilmenite transformation into Fe0 and Ti oxides; nevertheless, the pressure increase associated with melt shock can lead to a rise in the decomposition temperature of ilmenite. In other words, solar wind irradiation plays a more significant role in promoting nanoparticle (such as anatase and Fe0) formation as compared to melt shock. Thus, unlike the chemical alteration of ilmenite induced by the solar wind irradiation, melt shock mainly causes physical changes in ilmenite grains.

A new carbon-negative hydrogen production cycle for better sustainability

Carbon dioxide removal is considered by many as an essential piece to achieve global net zero targets which was also mentioned by the third working group of Intergovernmental Panel on Climate Change. On top of this, green hydrogen is badly needed to achive carbon-free society long-term sustainability. This study proposes a new five-step sodium hydroxide thermochemical cycle for simultaneous hydrogen production and carbon dioxide removal, which is driven by the heat at least 400 °C. The proposed integrated cycle can be driven by clean energy sources that can be utilized to generate heat at required temperatures. The proposed system is designed and analyzed by using energy and exergy approaches of thermodynamics. A case study is also developed in order to understand the effects of changing parameters on system performance. A thermochemical hydrogen production cycle is designed with an unequilibrium reaction where the respective heat capacity calculation models are employed. According to the calculations, more than half of the energy content of process heat can be converted into hydrogen, where maximum energy and exergy efficiencies of the thermochemical cycle are found as 50.05% and 76.61% when the separation reaction is carried out at 400 °C. According to the case study results, a parabolic trough collector type concentrated solar energy system with 295 kW of heat sink capacity, can generate 5216.65 kg of hydrogen and capture 19,991.97 kg of carbon dioxide in a location where 1500.11 kWh of solar energy is reached per m2 of area in a typical year.

The Entropy of Mixing in Self-Assembly and the Role of Surface Tension in Modeling the Critical Micelle Concentration

A theory for the micelle formation of nonionic head-tail amphiphiles (detergents) in aqueous solutions is derived based on the traditional molecular thermodynamic modeling approach and a variant of the Flory–Huggins theory that goes beyond lattice models. The theory is used to analyze experimental values for the critical micelle concentration of n-alkyl-ß-D-maltosides within a mass action model. To correlate those parts of the micellization free energy, which depend on the transfer of hydrophobic molecule parts into the aqueous phase, with molecular surfaces, known data for the solubility of alkanes in water are reanalyzed. The correct surface tension to be used in connection with the solvent-excluded surface of the alky tail is ~30 mN/m. This value is smaller than the measured surface tension of a macroscopic alkane–water interface, because the transfer free energy contains a contribution from the incorporation of the alkane or alkyl chain into water, representing the change in free volume in the aqueous phase. The Flory–Huggins theory works well, if one takes into account the difference in liberation free energy between micelles and monomers, which can be described in terms of the aggregation number as well as the thermal de Broglie wavelength and the free volume of the detergent monomer.

Modeling of the perovskite nickelate SmNiO3 nucleation from amorphous thin films: A Volmer's thermodynamical approach

We present a thermodynamical model based on Volmer's nucleation theory adapted to the case of the perovskite nickelate SmNiO3 crystallization (SNO) from an amorphous (aSNO) thin film. This amorphous phase is synthesized via reactive magnetron sputtering and then subsequently annealed in air at temperatures between 725 and 925 K to crystallize it. This model allows to predict the theoretical nucleation rate of the crystallized perovskite phase according to the annealing temperature, the type of the nucleation (homogeneous and heterogeneous mechanisms) and to estimate some physical and thermodynamical data related to this transformation. A theoretical evaluation of the nucleation rate shows that the optimum temperature for crystallization is close to 800 K for which the nucleation rate can reach 1021 m-3.s-1 if considering both homogeneous and heterogeneous nucleation mechanisms. As the annealing temperature moves away from 800 K, the theoretical nucleation rate drops drastically, as observed experimentally by X-ray Diffraction (XRD) when we annealed 200 nm thick aSNO films. The good agreement between the presented model and the experimental crystallization results allows us to numerically evaluate some physical parameters not yet reported to date in the literature for SNO perovskites such as the surface energy between the amorphous and the crystallized SNO phases, the strain energy when the crystallization occurs and the enthalpy associated with crystallization.