Search Results (170)

Bose–Einstein condensation is an intensely studied quantum phenomenon that emerges at low temperatures. While preceding Bose–Einstein condensation models do not consider what statistics apply above the condensation temperature, we show that neglecting this question leads to inconsistencies. A mathematically rigorous calculation of Bose–Einstein condensation temperature requires evaluating the thermodynamic balance between coherent and incoherent particle populations. The first part of this work develops such an improved Bose–Einstein condensation temperature calculation, for both three-dimensional and two-dimensional scenarios. The progress over preceding Bose–Einstein condensation models is particularly apparent in the two-dimensional case, where preceding models run into mathematical divergence. In the Discussion section, we compare our mathematical model against experimental superconductivity data. A remarkable match is found between experimental data and the calculated Bose–Einstein condensation temperature formulas. Our mathematical model therefore appears applicable to superconductivity, and may facilitate a rational search for higher-temperature superconductors. Full article

This article presents a mini-review of the available data on the thermodynamics of the complexation of amino acids and peptides with some nucleic bases in a buffer medium. Data on changes in thermodynamic parameters (binding constants, Gibbs energy, enthalpy, entropy) during the complexation of nucleic bases with amino acids and peptides as a function of physicochemical properties are given at T = 298.15 K. The effects of complexation on the volumetric properties of nucleic bases, including apparent molar volumes, standard molar volumes, and limiting molar expansibility, over a temperature range of 288.15 to 313.15 K are considered in detail. Differences in the behavior of amino acids and peptides caused by different modes of coordination with nucleic bases are noted. These manifest in the stoichiometry of the formed complexes, the relationship with the acid dissociation constants of carboxyl and amino groups, enthalpy–entropy compensation in the complexation process, the temperature dependence of the transfer volumes, and the effect of hydrophobicity on volumetric characteristics. Full article

Iron-rich bauxite residue (red mud) is a hazardous alkaline solid waste produced during the production of alumina from high-iron bauxite, which poses severe environmental challenges due to its massive stockpiling and limited utilization. In this study, metallic iron was recovered from high-iron red mud using the smelting reduction process. Thermodynamic analysis results show that an increase in temperature and sodium oxide content, along with an appropriate mass ratio of Al₂O₃ to SiO₂ (A/S) and mass ratio of CaO to SiO₂ (C/S), contribute to the enhancement of the liquid phase mass fraction of the slag. During the smelting reduction process of high-iron red mud, iron recoveries for low-alkali high-iron red mud and high-alkali high-iron red mud under optimal conditions were 98.14% and 98.36%, respectively. The metal obtained through reduction meets the industrial standard for steel-making pig iron, which is also confirmed in the pilot-scale experiment. The smelting reduction process of high-iron red mud can be divided into two stages, where the reaction is predominantly governed by interfacial chemical reaction and diffusion control, respectively. The apparent activation energy of high-alkali high-iron red mud is lower than that observed for low-alkali high-iron red mud. The reduced slag can be used as a roadside stone material or cement clinker. This proposed method represents a sustainable process for the comprehensive utilization of high-iron red mud, which also promotes the minimization of red mud. Full article

Thermodynamic parameters play a crucial role in analyzing and optimizing crystallization processes. In this investigation, the solubility profiles of erythromycin thiocyanate dihydrate were determined gravimetrically under atmospheric pressure (0.1 MPa) across six monosolvent systems (methanol, n-propanol, methyl acetate, ethyl acetate, propyl acetate, and water) and two binary solvent mixtures (water–methanol and water–n-propanol), spanning a temperature range of 278.15–318.15 K. The results showed that the solubility of erythromycin thiocyanate dihydrate is apparently affected by temperature and solvent type. For pure solvents, erythromycin thiocyanate dihydrate has higher solubility in alcohol solvents, and lower solubility in ester solvents and water. In mixed solvent systems, erythromycin thiocyanate dihydrate exhibits reduced solubility with higher water content. The experimental solubility values in monosolvent systems were correlated using the Apelblat, Yaws, and Van’t Hoff models, with the Apelblat model showing the best fitting effect. The Apelblat model, Apelblat Jouyban Acre model, and CNIBS/R-K model were employed for data correlation in binary solvent systems, with the Apelblat model and CNIBS/R-K model showing better fitting results. Full article

Eulerian observations of chemical species at fixed positions in a flow field are known to violate conservation laws, while observations tracking moving air parcels are practically unfeasible. Eulerian observations often cause positive correlations between the reactants and products in the atmosphere, which are frequently misinterpreted as evidence of the related chemical conversion. This dilemma has motivated innovative trials. The perturbation technique, widely used in mathematical and physical studies, offers a potential solution. Combining Eulerian observations with perturbation techniques may compensate for this weakness, making this approach particularly valuable for studying the gas–aerosol partitioning of semi-volatile particulate species in ambient air. As an example, we examined this combination through an adiabatic-expansion-induced perturbation study of the gas–aerosol partitioning of dimethylamine (DMA) and trimethylamine (TMA) in ambient air. Eulerian observations of chemical species in size-segregated atmospheric particles ranging from 10 μm to 0.056 μm, coupled with downstream adiabatic-expansion-induced perturbation observations, were performed in coastal and marine atmospheres using a commercial sampler (Nano-MOUDI-II, MSP, Shoreview, MN, USA), followed by an offline chemical analysis. The results revealed that particulate DMA generally tended to evaporate in ambient air during the observational periods, while enhanced adiabatic-expansion-induced perturbations occasionally led to the co-formation of DMAHNO₃ and NH₄NO₃. However, gaseous TMA apparently underwent gas–particle condensation to reach equilibrium in ambient air, with adiabatic-expansion-induced perturbation resulting in the formation of non-ionized TMA particulates. The thermodynamic analysis further supported that the observed particulate TMA was primarily determined by the equilibrium of gaseous TMA with non-ionized particulate TMA rather than ionic TMAH⁺. Full article

We address the scientific “time” concept in the context of more general relaxation processes toward the Wärmetod of thermodynamic equilibrium. More specifically, we sketch a construction of a conceptual ladder of chemical reaction steps that can rigorously bridge a description from the microscopic domain of molecular quantum chemistry to the macroscopic materials domain of Gibbsian thermodynamics. This conceptual reformulation follows the pioneering work of Kenichi Fukui (Nobel 1981) in rigorously formulating the intrinsic reaction coordinate (IRC) pathway for controlled description of non-equilibrium passages between reactant and product equilibrium states of an overall material transformation. Elementary chemical reaction steps are thereby identified as the logical building-blocks of an integrated mathematical framework that seamlessly spans the gulf between classical (pre-1925) and quantal (post-1925) scientific conceptions and encompasses both static and dynamic aspects of material change. All modern chemical reaction rate studies build on the apparent infallibility of quantum-chemical solutions of Schrödinger’s wave equation and its Dirac-type relativistic corrections. This infallibility may now be properly accepted as an added“inductive law” of Gibbsian chemical thermodynamics, the only component of 19th-century physics that passed intact through the revolutionary quantum upheavals of 1925. Full article

In this paper, the thermodynamic properties of terpene mixtures were investigated because they represent a promising group of compounds, usually extracted from biomass, with their most notable application as fuel performance enhancers. The densities, viscosities, refractive indices, and ultrasonic speeds of sound were measured for three binary mixtures, citral + chloroform, limonene + chloroform, and linalool + chloroform, across the full composition range at temperatures between 288.15 K and 323.15 K under atmospheric pressure. Using experimental data, excess molar volumes, viscosity deviations, refractive index deviations, and isentropic compressibility, deviations were calculated. Additionally, properties such as partial molar volumes, excess partial molar volumes, partial molar volumes at infinite dilution, and apparent molar volumes were derived. The excess and deviation properties were analyzed using the Redlich–Kister equation. A single mathematical model, the Heric–Brewer–Jouyban–Acree model, was used to represent densities, viscosities, refractive indices, and ultrasonic speeds of sound. The results obtained in this work suggest that dispersive interactions dominate in the limonene and linalool binary mixtures, while hydrogen bonding plays a significant role in the citral + chloroform system. In summary, dispersive interactions are dominant in nonpolar systems like limonene and linalool, while hydrogen bonding significantly affects the citral-chloroform mixture, where the polar groups in citral interact with chloroform molecules. These differences in intermolecular forces help explain the distinct behavior of each mixture. The modeling outcomes demonstrated that the Heric–Brewer–Jouyban–Acree model accurately correlated the experimental thermodynamic properties, with average percent deviations below 1% for all three systems. Full article

The incorporation of disease-relevant targets into ternary complexes in a compound-dependent manner by utilizing an assisting chaperone has become a common modality as far as bifunctional ternary complex-forming compounds are concerned. In contrast, examples of ternary complexes formed by molecular glues are much rarer. Due to their lack of significant binary (independent) target affinity, their identification cannot yet be achieved by rational methods and is, therefore, much more challenging. However, it is precisely for that reason (given the associated advantages) that their systematic identification and application in drug discovery has recently attracted particular interest. In contrast to bifunctional ternary complex-forming compounds, molecular glues retrieve a significant part of their thermodynamic stability through newly induced chaperone–target or glue–target interactions that occur only in the ternary complex. These interactions lead to enhanced ligand binding—termed intrinsic cooperativity α—which can be retrieved via the apparent cooperativity either by monitoring ligand binding through the chaperone or through the target protein. In this publication, the advantage of measuring the apparent cooperativity (to determine the cooperativity α) by the weaker binding protein is discussed and illustrated using the example of ternary complexes between FKBP12, MAPRE1 and macrocyclic molecular glues derived from the rapamycin binding motif for FKBP12. Furthermore, the impact of the following three parameters on the apparent cooperativity is illustrated: (1) the concentration of the monitoring protein, (2) the excess of the counter protein, and (3) the affinity of the glue to the weaker binding protein in combination with the degree of intrinsic cooperativity α. From this, experimental conditions to determine the intrinsic cooperativity α with only one binding assay and without the need for a comprehensive mathematical model covering all simultaneous events under non-saturating conditions are highlighted. However, this framework requires a binding assay capable of measuring or at least estimating very weak binary affinities. If this is not possible for experimental reasons, but binding assays for both proteins are available within a normal bandwidth and the affinity to the stronger binding protein is not too high, it is discussed how the binding curve for the weaker binding protein in the presence of an excess of the weaker binding protein can be used to overcome the missing binary K_d for the weakly binding protein. Full article

The fruit processing agroindustry generates waste, mainly composed of peels, which are often discarded but can be utilized as ingredients for developing new food products. However, their high perishability requires the application of preservation techniques, such as drying, which not only extends shelf life but also adds value and enables their conversion into flour, expanding their applications. This study evaluated the convective drying of pineapple peels for flour production, analyzing bioactive, physical, and thermal properties. Moisture was reduced by 91%, reaching a hygroscopic equilibrium of 6.84%. The Two-Term model provided the best fit for the data, with an R² above 0.9997. Effective diffusivity increased with temperature, ranging from 2.83 × 10⁻¹⁰ m²/s to 7.96 × 10⁻¹⁰ m²/s, with an activation energy of 47.90 kJ/mol, as described by the Arrhenius equation. Thermodynamic properties indicated an endothermic, non-spontaneous process, with reductions in enthalpy (45.21; 45.04 kJ/mol) and entropy (−0.2797; −0.2802 kJ/mol·K) and an increase in Gibbs free energy (135.60–141.20 kJ/mol) at higher temperatures. Fresh peels contained high levels of bioactive compounds, such as phenolics (1740.90 mg GAE/100 g d.b.) and tannins (613.42 mg TAE/100 g d.b.), which were best preserved at 70 °C. Drying altered the physical properties of the flour, resulting in higher absolute, apparent and compact densities, lower porosity (75.81%), and a reduced angle of repose (21.22°) suggesting greater material stability. Thermal analysis identified five mass loss events related to the degradation of water, carbohydrates, proteins, and fibers. Differential scanning calorimetry confirmed the thermal stability of the treatments. Thus, the study highlights pineapple peels as a promising raw material for producing nutrient-rich functional flour, with a drying temperature being a crucial factor in preserving bioactive compounds and achieving desirable product characteristics. Full article

A new high-temperature allothermal gasification technology is used to process three types of oil waste: ground oil sludge (GOS), tank oil sludge (TOS), and petcoke. The gasifying agent (GA), mainly composed of H₂O and CO₂ at a temperature above 2300 K and atmospheric pressure, is produced by pulsed detonations of a near-stochiometric methane-oxygen mixture. The gasification experiments show that the dry off-gas contains 80–90 vol.% combustible gas composed of 40–45 vol.% CO, 28–33 vol.% H₂, 5–10 vol.% CH₄, and 4–7 vol.% noncondensable C₂–C₃ hydrocarbons. The gasification process is accompanied by the removal of mass from a flow gasifier in the form of fine solid ash particles with a size of about 1 μm. The ash particles have a mesoporous structure with a specific surface area ranging from 3.3 to 15.2 m²/g and pore sizes ranging from 3 to 50 nm. The measured wall temperatures of the gasifier are in reasonable agreement with the calculated value of the thermodynamic equilibrium temperature of the off-gas. The measured CO content in the off-gas is in good agreement with the thermodynamic calculations. The reduced H₂ content and elevated contents of CH₄, CO₂, and C_xH_y are apparently associated with the nonuniform distribution of the waste/GA mass ratio in the gasifier. To increase the H₂ yield, it is necessary to improve the mixing of waste with the GA. It is proposed to mix crushed petcoke with oil sludge to form a paste and feed the combined waste into the gasifier using a specially designed feeder. Full article

In recent years, the employment of rejuvenators and warm mix asphalt (WMA) additives for reclaimed asphalt pavement (RAP) has been recognized as a popular approach to increase the recycling rate of waste materials and promote the sustainable development of pavement engineering. However, the composition of warm mix recycled asphalt binder is complicated, and the microstructural changes brought about by the rejuvenators and WMA additives are critical in determining its macroscopic mechanical properties. This research focuses on the atomic modeling of the rejuvenators and WMA additives diffusion behavior of the warm mix recycled asphalt binder. The objective is to reveal the thermodynamic performance and diffusion mechanism of the WMA binder under the dual presence of rejuvenators and WMA additives. Three types of mutual diffusion systems (Aged and oil + virgin + wax, Aged + virgin + wax, and Aged and oil + virgin) were established, respectively, for a comparative investigation of the glass transition temperature, viscosity, thermodynamics, free volume, and diffusion behavior. The results indicate a 44.27% and 31.33% decrease in the glass transition temperature and apparent viscosity, respectively, after the incorporation of 5% oil rejuvenators in the Aged + virgin + wax asphalt binder, demonstrating the improved cracking resistance and construction workability. The presence of the RAP binder and organic WMA additives raised the cohesion of the asphalt binder and decreased self-healing ability and free volume, and these detrimental influences can be offset by the introduction of rejuvenators. The combined use of rejuvenators and organic WMA additives remarkably enhanced the de-agglomeration to asphaltenes, stimulated the activity of aged RAP macromolecular components, and ultimately improved the blending efficiency of virgin binders with the overall structure of RAP binders. Full article

The thermodynamic study of protein folding shows the generation of a narrow range of ΔG° values, as a net result of large changes in the ΔH° and TΔS° values of the folding process. The obvious consequence of this narrow range of values is that a linear enthalpy–entropy relationship, showing apparent enthalpy–entropy compensation (EEC), is clearly observed to be associated with the study of protein folding. Herein, we show the ΔH°, TΔS°, and ΔG° values for a set of 583 data from protein folding processes, at various temperatures, as calculated by using the Gibbs–Helmholtz equations. This set of thermodynamic data was calculated from the melting temperature (Tm), the melting enthalpy (ΔHm), and the change in heat capacity (ΔCp°) values, all of them associated with the heat-induced protein unfolding processes and included in the ProTherm Data Base. The average values of enthalpy (ΔH°av), entropy (TΔS°av), and free energy (ΔG°av) for the folding process were calculated within the range of temperature from 0 °C to the average value of Tm. The values and temperature dependency of TΔS°av within this temperature range are practically equal to those corresponding to ΔH°av, while ΔG°av remains small and displaying a curve with a minimum at about 10 °C and a value of ΔG° = −30.9 kJ/mol at the particular temperature of 25 °C. The large negative value of TΔS°av, together with the also large and negative value of ΔCp°av, suggests large conformational changes and important EEC, thus causing the small average value of ΔG° for protein folding, which is enough to guarantee both protein stability and molecular flexibility to allow for adaptation to the chemical potentials of the environment. Our analysis suggests that EEC may be the quantum-mechanical evolutive mechanism to make functional proteins adaptative to environmental temperature and metabolite concentrations. The analysis of protein folding data, compared with those of protein–ligand interaction, allows us to suggest strategies to overcome EEC in the design of new drugs. Full article

The calculation of Gibbs free energy via the statistical multifractal analysis of airborne observations indicates that the atmosphere is not at local thermodynamic equilibrium. Both climate models and meteorological analyses assume that it is. Satellite retrievals use spectroscopic data taken at equilibrium in laboratories, leading to apparent consistency that is to some degree faulty. Line shapes of radiatively active species, the rotational energy of molecular nitrogen and oxygen, and the translational energy of all molecules are involved, resulting in less energy in models than exists in the real atmosphere. The resulting formulation of turbulence is from the smallest scales up and has implications for astronomical observation by adaptive optics. Kolmogorov (isotropy) is not evident. The effect of temperature on the overhead water vapour column at ground-based telescopes is also open to the effects of climate change. The degree to which the dynamic operational temperature differs from that obtained by the use of local thermodynamic equilibrium assumptions needs to be established by observational measurements. Some of the considerations will apply to the atmospheres of exoplanets with regard to photochemistry and signatures of life. Full article

The coal–oxygen composite reaction is a complex physicochemical reaction process, and different heating rates have a great influence on this reaction. In order to reveal the influence of different heating rates on the coal–oxygen composite reaction of coking coal, the TG-DSC experimental method was adopted to analyze the hysteresis effect of the characteristic temperature, inflection point temperature, and peak temperature under different heating rates. Furthermore, the KAS method was employed to calculate the apparent activation energy, and the Málek method was utilized to infer the most probable mechanism functions and determine the compensation effects at different stages of the coal oxidation process. The results show that with an increase in heating rate, the temperature values corresponding to each characteristic temperature point increase, the characteristic temperature exhibits a hysteresis phenomenon, and the heat flow rate and heat flux rate also show an increasing trend. The apparent activation energy gradually increases in Stages II and III, with a maximum value of 198.7 kJ/mol near the ignition point T₃, which first increases and then gradually decreases in Stage IV, where the maximum value is around the temperature point T₄ of the maximum mass loss rate, which is 170.02 kJ/mol. The variation trend in the pre-exponential factor is consistent with the apparent activation energy, and the dynamic compensation effect is greater in Stage IV. The three different oxidation stages have different mechanism functions: a three-dimensional diffusion mode is present in Stages II and III, which is ultimately transformed into an accelerated form α-t curve with E₁ and n = 1 in Stage IV. Full article

The pairs of Cu₂O/CuO and CoO/Co₃O₄ as the carriers of transferring oxygen and storing heat are essential for the recently emerged high-temperature thermochemical energy storage (TCES) system. Reported research results of Cu₂O and CoO oxidation kinetics show that the reaction rate near equilibrium decreases with the temperature, which leads to the negative activation energy obtained using the Arrhenius equation and apparent kinetics models. This study develops a first-principle-based theoretical model to analyze the Cu₂O and CoO oxidation kinetics. In this model, the density functional theory (DFT) is adopted to determine the reaction pathways and to obtain the energy barriers of elementary reactions; then, the DFT results are introduced into the transition state theory (TST) to calculate the reaction rate constants; finally, a rate equation is developed to describe both the surface elemental reactions and the lattice oxygen concentration in a grain. The reaction mechanism obtained from DFT and kinetic rate constants obtained from TST are directly implemented into the rate equation to predict the oxidation kinetics of Cu₂O without fitting experimental data. The accuracy of the developed theory is validated by experimental data obtained from the thermogravimetric analyzer (TGA). Comparing the developed theory with the traditional apparent models, the reasons why the latter cannot appropriately predict the true oxidation characteristics are explained. The reaction rate is jointly controlled by thermodynamics (reaction driving force) and kinetics (reaction rate constant). Without considering the effect of the reaction driving force, the negative apparent activation energy of Cu₂O oxidation is obtained. However, for CoO oxidation, the negative apparent activation energy is still obtained although the effect of the reaction driving force is considered. According to the DFT results, the activation energy of the overall CoO oxidation reaction is negative, but the energy barriers of the elementary reactions are positive. Moreover, according to the first-principle-based rate equation theory, the pre-exponential factor in the kinetic model is dependent on the partition function ratio and decreases with the temperature for the Cu₂O and CoO oxidation near equilibrium, which results in the apparent activation energy being slightly lower than the actual value. Full article