Gibbs Energy Of Mixing Research Articles

Thermodynamic Study on Biomimetic Legionella gormanii Bacterial Membranes.

The presented studies were aimed at determining the interactions in model membranes (Langmuir monolayers) created of phospholipids (PL) isolated from Legionella gormanii bacteria cultured with (PL + choline) or without (PL - choline) choline and to describe the impact of an antimicrobial peptide, human cathelicidin LL-37, on PL's monolayer behavior. The addition of choline to the growth medium influenced the mutual proportions of phospholipids extracted from L. gormanii. Four classes of phospholipids-phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), cardiolipin (CL), and their mixtures-were used to register compression isotherms with or without the LL-37 peptide in the subphase. Based on them the excess area (Ae), excess (ΔGe), and total (ΔGm) Gibbs energy of mixing were determined. The thermodynamic analyses revealed that the PL - choline monolayer showed greater repulsive forces between molecules in comparison to the ideal system, while the PL + choline monolayer was characterized by greater attraction. The LL-37 peptide affected the strength of interactions between phospholipids' molecules and reduced the monolayers stability. Accordingly, the changes in interactions in the model membranes allowed us to determine the difference in their susceptibility to the LL-37 peptide depending on the choline supplementation of bacterial culture.

Unveiling the thermodynamic landscape of liquid Ti–Al–Ni alloys through first-principles simulations

We conducted ab initio molecular dynamics simulations to systematically examine the composition-dependent thermodynamic properties and atomic-scale interactions in liquid Ti–Al–Ni alloys throughout the entire ternary phase space at 2033 K. The calculated enthalpies of mixing demonstrated exothermic tendencies, with a distinct minimum in the composition of Ti0.0Al0.50Ni0.50, indicating significant Al–Ni attractive interactions. Incorporating ternary interaction parameters into the Redlich-Kister-Muggianu equation enabled accurate modeling of the complex variations in mixing enthalpy. Analysis of partial pair correlation functions and structure factors revealed chemical and topological short-range ordering (SRO), as well as medium-range ordering, within the liquid alloy. Quantifying deviations from ideal configurational entropy clarifies the coupling between chemical SRO and topological SRO, significantly impacting the overall Gibbs energy of mixing. This comprehensive atomistic study provides insights into the thermodynamics of Ti–Al–Ni alloys, paving the way for tailoring their properties for high-performance applications.

Solubility of 5-(4-methylphenyl)-2-furanpropanoic acid in different organic solvents

In this study, the temperature dependences of the solubility of 5-(4-methylphenyl)-2- furanpropanoic acid in various solvents were evaluated: methyl and ethyl acetate, acetonitrile, propane-1-ol, and propan-2-ol. The results of the analysis are presented in the form of linear equations according to the Schröder model, which allowed us to determine the enthalpies, entropies, and Gibbs energies of solubility at a temperature of 298.15 K. The melting points of the acid were determined using the method of differential thermal analysis, which allowed us to calculate the enthalpies, entropies, and Gibbs energies of mixing.

Surface miscibility of Gemini surfactants and DOPE in binary mixed monolayers

AbstractSurface pressure (π)–molecular area (A) isotherms were gathered to characterize the packing of binary mixed Langmuir monolayers of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphoethanolamine (DOPE) and one of two Gemini surfactants (GS), N,N‐bis(dimethyloctadecyl)‐1,7‐nonanediammonium dibromide (18‐7‐18) or 1,9‐bis(octadecyl)‐1,1,9,9‐tetramethyl‐5‐amino‐1,9‐nonanediammonium dibromide (18‐7NH‐18) of varying molar fractions. Information about miscibility behavior was derived from the π–A curves by examining the excess free energy of mixing (ΔGexc) that was calculated through the surface area additivity rule. Surface compressibility modulus (Cs−1) was also used to characterize intermolecular interactions. Mutual interactions between GS and DOPE were analyzed in terms of excess Gibbs energy of mixing and the value of this parameter depended strongly on the composition of the mixed film. GS and DOPE are generally miscible as DOPE reduces intermolecular repulsion between highly charged GS molecules leading to the formation of more densely packed mixed monolayers. However, GS and DOPE are immiscible in equimolar mixtures due to tail group packing mismatch between saturated and unsaturated alkyl chains. The prevalence of attractive synergistic interactions in the monolayers studied differs from a previous finding of antagonistic mixing behavior in GS/DOPE micelles. These results contribute to the understanding of GS‐lipid interactions and packing that are critical to the in vitro and in vivo stability of liposomes composed of these molecules used for non‐viral gene therapy applications.

THERMODYNAMICS OF LIQUID–GAS PHASE EQUILIBRIA OF DIISOPROPYLSULFOXIDE–WATER SYSTEM

The saturated vapor pressure of diisopropylsulfoxide aqueous solutions was measered at temperatures of 303.15 K and 308.15 K. It was shown that the total saturated vapor pressure increases with decreasing diisopropylsulfoxide concentration in the solution and with increasing temperature. As in the cases of diethylsulfoxide and dipropylsulfoxide aqueous solutions, a negative deviation from Raoult’s law is also observed. This confirms the ability of diisopropylsulfoxide molecules to associate with water molecules. Based on the results obtained, the partial pressures, the activity coefficients of diisopropylsulfoxide and water and the excess Gibbs energy of their mixing, were calculated. It is shown that the excess Gibbs energy of mixing is negative and reaches its minimum value at a mole fraction of diisopropylsulfoxide equal to 0.38. The obtained data on the excess Gibbs energy of mixing DiPSO and water were treated using the Redlich–Kister equation. It has been established that the interaction between the molecules of diisopropylsulfoxide and water is stronger than in the diethylsulfoxide+water system, and weaker than in the dipropylsulf-oxide+water system. This fact can be explained by an increase in the electron-donating ability of the alkyl group with increasing hydrocarbon chain length, which increases the reactivity of the oxygen atom of the sulfoxide group. As a result, when moving from diethylsulfoxide to diisopropylsulfoxide or dipropylsulfoxide, the ability of their molecules to interact with water molecules to form hydrogen bonds increases. At the same time, a decrease in hydrophobic effects and dispersion forces between diisopropylsulfoxide molecules with a branched hydrocarbon chain leads to a weakening of the interaction between molecules in the diisopropylsulfoxide+water system compared to the dipropylsulfoxide+water system, which is also observed experimentally.

Thermodynamic properties of the BaO-Al2O3 system

Synthesis of the samples in the BaO-Al2O3 system was carried out by solid state synthesis method at the temperature 1250 °C (all samples) and 1500 °C (samples NN 5–10). The characterization of the samples was performed with the use of XRD analysis. The vaporization and thermodynamic properties of BaO-Al2O3 system at 1815 °C from 0.10 to 0.90 Ba mole fractions have been studied by Knudsen effusion differential mass spectrometry.The formation enthalpies from the elements of Ba3Al2O6(s), BaAl2O4(s), BaAl12O19(s) were derived and the recommended values are the following: − 3515 ± 76, − 2338 ± 70 and − 10730 ± 25 kJ/mole respectively. The component activities, Gibbs energies of mixing and excess Gibbs energies were obtained. The thermodynamic properties of the BaO-Al2O3 system at high temperatures are characterized by the negative deviation from the ideal case.

Ternary Mixed Micelle Hexadecyltrimethylammonium Bromide-Dodecyltrimethylammonium Bromide-Sodium Deoxycholate: Gibbs Free Energy of Mixing and Excess Gibbs Energy of Mixing.

Pharmaceutical, food, and cosmetic formulations often contain binary or ternary surfactant mixtures with synergistic interactions amongst micellar building blocks. Here, a ternary mixture of the surfactants hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and sodium deoxycholate is examined to see if the molar fractions of the surfactants in the ternary mixed micellar pseudophase are determined by the interaction coefficients between various pairs of the surfactants or by their propensity to self-associate. Critical micelle concentrations (CMC) of the analyzed ternary mixtures are determined experimentally (spectrofluorimetrically using pyrene as the probe molecule). Thermodynamic parameters of ternary mixtures are calculated from CMC values using the Regular Solution protocol. The tendency for monocomponent surfactants to self-associate (lower value of CMC) determines the molar fractions of surfactant in the mixed micelle if there is no issue with the packing of the micelle building units of the ternary mixed micelle. If a more hydrophobic surfactant is incorporated into the mixed micelle, the system (an aqueous solution of surfactants) is then the most thermodynamically stabilized.

Tracking maze-like hierarchical phase separation behavior in a Fe-Si-V alloy

Optimizing the properties of next-generation high-temperature and corrosion-resistant alloys is rooted in balancing structure-property relationships and phase chemistry. Here, we implement a complementary approach based on transmission electron microscopy (TEM) and atom probe tomography (APT) to ascertain aspects of hierarchical phase separation behavior, by understanding the microstructural evolution and the three-dimensional (3D) nanochemistry of a single crystal Fe79.5Si15.5V5.0 (at%) alloy. A maze-like hierarchical microstructure forms, in which a complex network of metastable disordered α plates (A2 phase) emerges within ordered α1 precipitates (D03 phase). The supersaturation in α1 (D03) precipitates with Fe and V drives the formation of α (A2) plates. The morphology of α (A2) plates is discussed concerning crystal structure, lattice misfit, and elastic strain. Phase compositions and a ternary phase diagram aid the thermodynamic assessment of the hierarchical phase separation mechanism via the Gibbs energy of mixing. A perspective on the stabilization of hierarchical microstructures beyond Fe79.5Si15.5V5.0 is elaborated by comparing hierarchical alloys. We find that the ratio of elastic anisotropy (Zener ratio) serves as a predictor of the hierarchical particles’ morphology. We suggest that the strengthening effect of hierarchical microstructures can be harnessed by improving the temporal and thermal stability of hierarchical particles. This can be achieved through phase-targeted alloying aiming at the hierarchical particles phase by considering the constituents partitioning behavior. Beyond Fe79.5Si15.5V5.0, our results demonstrate a potential pathway for improving the properties of high-temperature structural materials.

Hydrogels Based on Polyacrylamide and Calcium Alginate: Thermodynamic Compatibility of Interpenetrating Networks, Mechanical, and Electrical Properties.

The synthesis and physicochemical properties of hydrogels with interpenetrated physical and chemical networks were considered in relation to their prospective application as biomimetic materials in biomedicine and bioengineering. The study was focused on combined hydrogels based on natural polysaccharide-calcium alginate (CaAlg) and a synthetic polymer-polyacrylamide (PAAm). The series of hydrogels with varying proportions among alginate and polyacrylamide have been synthesized, and their water uptake has been characterized depending on their composition. The equilibrium swelling and re-swelling in water after drying were considered. The compatibility of alginate and polyacrylamide in the combined blend was studied by the thermodynamic approach. It showed a controversial combination of negative enthalpy of mixing among PAAm and CaAlg with positive Gibbs energy of mixing. Mechanical and electrical properties of the combined gels with double networking were studied as relevant for their prospective use as scaffolds for tissue regeneration and working bodies in actuators. The storage modulus and the loss modulus were determined in the oscillatory compression mode as a function of proportions among natural and synthetic polymers. Both moduli substantially increased with the content of CaAlg and PAAm. The electrical (Donnan) potential of hydrogels was measured using the capillary electrode technique. The Donnan potential was negative at all compositions of hydrogels, and its absolute values increased with the content of CaAlg and PAAm.

Extractive desulfurization of thiophene by tetraethylene glycol at T = 298.15 to 313.15 K and liquid–liquid phase equilibrium study

ABSTRACT This study provides the complete liquid–liquid equilibrium (LLE) data including the solubility curves and tie-lines for heptane + thiophene + tetraethylene glycol and cyclohexane + thiophene + tetraethylene glycol ternary mixtures at 298.15–313.15 K under a pressure of 83.4 ± 1 kPa. The experimental data were obtained by the cloud point method. Type 1 phase behavior is observed for the systems. The observed behavior was interpreted based on the type and nature of the interactions between the components. The capability of tetraethylene glycol in extractive desulfurization of thiophene from liquid fuel is evaluated by determining the solute distribution coefficient and selectivity. The high values of the selectivity show that tetraethylene glycol is a good candidate for this purpose. The investigation of the effect of temperature on the area of the biphasic region and distribution ratios shows that the extraction process can be performed at room temperature. The experimental data were successfully correlated with the NRTL model. The reliability of the correlation results was checked by using a Graphical User Interface (GUI) for the representation of Gibbs energy of mixing (GM). The root mean square deviation (RMSD), a measure of the precision of the correlations, ranges from 0.0022 to 0.0040.

Thermodynamic descriptors of sensible heat driven liquid-liquid phase separation

• Solvent (Water/alcohol) provides the principal contribution in governing the solution thermoresponsive behavior. • Analytical derivation of temperature and concentration dependent gradient of the scaled Gibbs energy of mixing. • Scaled Gibbs energy gradient derived as a function of the Gibbs stability criterion and also in activity coefficient terms. • Scaled/Reduced activity coefficient can delineate LCST/UCST regimes without computing the Gibbs energy of mixing. • All the above parameters successfully characterize LCST/UCST behavior with literature/experimental corroboration. Separation of a homogeneous solution into its constituent liquids through sensible heating obviates the need for vaporization/distillation and the associated latent heat of phase change. Therefore, it could enable alternative more energy efficient cycles in many applications that involve the separation of miscible liquids. This can be achieved by utilizing Lower and Upper Critical Solution Temperature (LCST/UCST) driven phase separation. This study identifies the thermodynamic descriptors for predicting LCST/UCST exhibiting ionic liquid (IL) - water/alcohol (solvent) solutions, and therefore provides a fundamental insight into the underlying energetics responsible for temperature and concentration dependent miscibility of multicomponent solutions. Excess Gibbs energy analysis of 50 solutions revealed that the solvent (water/alcohol) played a pivotal role in phase separation and exhibited contrasting excess Gibbs energy contributions in the LCST and UCST regimes. Furthermore, analysis of scaled Gibbs energy was carried out to elucidate the energetics of phase separation and differentiate between LCST and UCST thermodynamically. Consequently, we introduce the solvent Reduced Activity Coefficient (RAC) which was used to successfully predict the phase separation behavior without evaluating the Gibbs energy function, thus saving significant computation time.

Effect of chitosan on the interactions between phospholipid DOPC, cyclosporine A and lauryl gallate in the Langmuir monolayers

The Langmuir technique allows for the characterization of monolayers of biological and/or biologically active compounds which have high potential for application in tissue engineering to improve the implants biocompatibility. This group of substances includes 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), cyclosporine A (CsA), lauryl gallate (LG), and chitosan (Ch). The single (DOPC, CsA, LG), binary (DOPC-CsA 1:1) and ternary (DOPC-CsA-LG 3:3:2, 1:1:2, 1:1:6 that correspond to χLG = 0.25, 0.50, 0.75) monolayers on the acidic subphase with or without chitosan (Ch) were characterized using the Langmuir technique coupled with the surface potential meter. The dependence of the surface pressure and the surface potential on the area per molecule (π−A and ∆V−A isotherms, respectively) was determined. Based on the above isotherms data, the compression modulus (Cs−1), excess and total Gibbs energy of mixing (∆Gexc and ∆Gmix) as well as the apparent dipole moment (μa) were calculated. These parameters allowed drawing conclusions about the molecular packing, the orientation of molecules, the type and magnitude of interactions within the monolayers, and finally about their stability, depending on the components proportions and the contribution of Ch molecules. The main findings indicated that the insertion of LG to the binary DOPC-CsA 0.50 monolayer resulted in a shift of the π−A isotherms towards smaller areas per molecule, the smaller areas the higher amount of LG. That correlated with an increase in packing density (larger Cs−1 values) and an attraction between the molecules (revealed by the negative ∆Gexc and ∆Gmix values) in the three-component monolayers. Furthermore, the addition of chitosan (Ch) molecules into the subphase stiffened the multicomponent (DOPC-CsA or DOPC-CsA-LG) films. The strengthening of the attractive interactions and better miscibility were observed for all the DOPC-CsA-LG films. Therefore, these monolayers spread on the Ch subphase were found to be thermodynamically stable (among them the most stable was DOPC-CsA-LG 0.50) and could be successfully used for coating implants in order to improve their biocompatibility with the surrounding tissues.

Effect of Ester Moiety on Structural Properties of Binary Mixed Monolayers of Alpha-Tocopherol Derivatives with DPPC.

Phospholipid membranes are ubiquitous components of cells involved in physiological processes; thus, knowledge regarding their interactions with other molecules, including tocopherol ester derivatives, is of great importance. The surface pressure–area isotherms of pure α-tocopherol (Toc) and its derivatives (oxalate (OT), malonate (MT), succinate (ST), and carbo analog (CT)) were studied in Langmuir monolayers in order to evaluate phase formation, compressibility, packing, and ordering. The isotherms and compressibility results indicate that, under pressure, the ester derivatives and CT are able to form two-dimensional liquid-condensed (LC) ordered structures with collapse pressures ranging from 27 mN/m for CT to 44 mN/m for OT. Next, the effect of length of ester moiety on the surface behavior of DPPC/Toc derivatives’ binary monolayers at air–water interface was investigated. The average molecular area, elastic modulus, compressibility, and miscibility were calculated as a function of molar fraction of derivatives. Increasing the presence of Toc derivatives in DPPC monolayer induces expansion of isotherms, increased monolayer elasticity, interrupted packing, and lowered ordering in monolayer, leading to its fluidization. Decreasing collapse pressure with increasing molar ratio of derivatives indicates on the miscibility of Toc esters in DPPC monolayer. The interactions between components were analyzed using additivity rule and thermodynamic calculations of excess and total Gibbs energy of mixing. Calculated excess area and Gibbs energy indicated repulsion between components, confirming their partial mixing. In summary, the mechanism of the observed phenomena is mainly connected with interactions of ionized carboxyl groups of ester moieties with DPPC headgroup moieties where formed conformations perturb alignment of acyl chains, resulting in increasing mean area per molecule, leading to disordering and fluidization of mixed monolayer.

Interplay of long-chain tetrazine derivatives and biomembrane components at the air-water interface.

Tetrazine (Tz) is an emerging bioorthogonal ligand that is expected to have applications (e.g., bioimaging) in chemistry and chemical biology. In this review, we highlight the interactions of reduced tetrazine (rTz) derivatives insoluble in aqueous media with biological membrane constituents or their related lipids, such as dipalmitoyl-phosphatidylcholine, dipalmitoyl-phosphatidylethanolamine, dipalmitoyl-phosphatidylglycerol, palmitoyl-sphingomyelin, and cholesterol in the Langmuir monolayer state at the air-water interface. The two-component interaction was thermodynamically elucidated by measuring the surface pressure (π) and molecular area (A) isotherms. The monolayer miscibility between the two components was analyzed using the excess Gibbs energy of mixing and two-dimensional phase diagram. The phase behavior of the binary monolayers was studied using the Brewster angle, fluorescence, and atomic force microscopy. This study discusses the affinities of the rTz moieties for the hydrophilic groups of the lipids used.

Vaporization and thermodynamic properties of the SrO-Al2 O3 system studied by Knudsen effusion mass spectrometry.

Strontium aluminates can be used as refractory construction materials at temperatures up to 2000°С or as the materials for immobilization of long-lived radioactive waste. The SrО-Al2 O3 system is one of the more complicated oxide systems used for the creation of new radio-transparent materials. The exploitation of such materials at high temperatures demands the knowledge of the thermal stability of the compounds and solid solutions formed in the SrО-Al2 O3 system. The synthesis of the samples in the SrO-Al2 O3 system was carried out by a ceramic method at 1250°C. The characterization of the samples was accomplished with the use of X-ray diffraction (XRD). The vaporization of the samples under study was performed from a twin tungsten effusion cell using the Knudsen effusion mass spectrometry method. The temperature dependences of partial pressures of vapor species over 4SrO·Al2 O3 , 3SrO·Al2 O3 , SrO·Al2 O3 , SrO·2Al2 O3 and SrO·6Al2 O3 in a wide range of temperatures were determined. The component activities, the Gibbs energies of mixing and the standard enthalpies of individual strontium aluminates were obtained. The thermodynamic properties of the SrO-Al2 O3 system at high temperatures are characterized by negative deviation from ideality. The vaporization processes and thermodynamic properties of the SrO-Al2 O3 system were obtained for the first time.

Thermodynamics of liquid Al–In, Ag–In and In–Sb alloys from a four-atom cluster model

Abstract A model based on a cluster of four atoms has been used to obtain higher-order conditional probabilities that describe the atomic correlations in Al–In, Ag–In and In–Sb liquid alloys. Using the value of the ordering energy obtained from the model, some thermodynamic quantities such as Gibbs energy of mixing and concentration-concentration fluctuations in the long wavelength limit were calculated for these alloys. Our study of the energetics of these liquid alloys reveals that while In–Sb and Ag–In are both chemically ordered or heterocoordinated systems, Al–In is a segregating system. Furthermore, the degree of order in liquid In–Sb alloys is higher than that in liquid Ag–In alloys.

Activity measurements of Ga in liquid Ga–Tl alloys by EMF method with zirconia solid electrolyte

Abstract Electromotive force measurements (EMF) of an electrochemical cell with zirconia as solid electrolyte were performed to determine the Ga activity from 973 to 1273 K in the entire composition range of liquid Ga–Tl alloys. In the whole concentration range, the activity of Ga shows large positive deviations from ideality, and the activity of Tl which is derived by the Gibbs–Duhem equation shows also positive deviation from ideality. The parameters of the Redlich – Kister equation for excess Gibbs energies of mixing are determined from the results obtained in this study which were compared with Chou’s model calculation.

THERMODYNAMIC CALCULATIONS OF HIGH ENTROPY (FE-MN) BINARY ALLOY SYSTEM USING CALPHAD METHOD BASED ON THERMO-CALC PACKAGE AND PBINE,FEDATE DATABASES.

The thermodynamic analysis and calculations of the high entropy metastable binary alloy ironmanganese system have been carried out using the CALPHAD (Calculation of phase Diagram) method based on THERMO-CALC (thermodynamic calculations) package and FEDATE database. Thermodynamic analysis contain the assessment and calculation of phase diagram, Gibbs energy of mixing, excess Gibbs energies, thermodynamic molar activities, coefficient of activities, partial and integral values of enthalpy for Fe-Mn alloy system at three elevated temperatures 1200K, 1225K, and 1250K.The entropy of the said alloy system is calculated by showing linear accordance with temperature. The sudden increase is found in enthalpy curve due to overlapping of grain boundaries of the system. The high enthalpy shows increasing heat contents of the said alloy system with increasing temperature range. The alloy shows a positive deviation from Vegard’s law, Henry’s law and corresponding negative deviation from Raoults’s law ideal Gibbs curve. The obtained results show that the ferromagnetic states of Fe-Mn alloy is the most stable state FCC_A1#1. For Mn and Fe system, the phase equilibria show activity curve data for solid state and show ideal characteristics behaviors. Small positive deviation from Henry’s law was observed from the ideal curve. The alloy shows equilibrium and good stability.

Comprehensive thermodynamic study of three Co(II)- and Fe(II)-based octacyanoniobates

A comprehensive study of thermodynamic properties of three samples of bimetallic molecular magnets [Co$^{\mathrm{II}}$(pyrazole)$_{4}$]$_{2x}$[Fe$^{\mathrm{II}}$(pyrazole)$_{4}$]$_{2(1-x)}$[Nb$^{\mathrm{IV}}$(CN)$_{8}$]$\cdot$4H$_{2}$O with $x$=0 (Co$_{2}$Nb), 0.5 (CoFeNb), and 1 (Fe$_{2}$Nb) is reported. The three samples display the same crystallographic structure crystallizing in the tetragonal system with space group $I4_1/a$. Their heat capacities are measured in the temperature range 0.36-100 K without applied field as well as in the field of $\mu_0 H$ = 0.1, 0.2, 0.5, 1, 2, 5, and 9 T. The results imply the presence of the second-order phase transitions to magnetically ordered phases at 4.87(8) K, 7.1(2) K, and 8.44(3) K for $x$=0, 0.5, and 1, respectively. The corresponding thermodynamic functions are analyzed to discuss the stability of the mixed compound and the magnetocaloric effect (MCE). The Gibbs energy of mixing is found to be positive but smaller in magnitude than the energy of thermal fluctuations indicating that the mixed sample is marginally stable in the full detected temperature range. The enthalpy of mixing is negative, which points to an ordered arrangement of the Co(II) and Fe(II) ions in the solid solution CoFeNb. The negative values of the entropy of mixing are explained by considering the enhanced rigidity of the crystal lattice of the solid solution sample. To extract the magnetic contribution to the heat capacity an approach based on a reasonable frequency spectrum is adopted. Taking advantage of the in-field heat capacity measurements MCE was described in terms of the isothermal entropy change $\Delta S_\mathrm{M}$ and the adiabatic temperature change $\Delta T_\mathrm{ad}$. The magnitudes of these quantities are typical for the class of molecular magnets.

Experimental measurement and thermodynamic modeling of solubility of flufenamic acid in different pure solvents

Flufenamic acid (FFA) is a BCS II class drug having low solubility and high permeability in the gastrointestinal tract. The solubility enhancement techniques of BCS II class drugs such as co-crystallization, solid dispersion or fine particle generation by supercritical or liquid antisolvent method require the knowledge of solubility of API in the organic solvent. In the present work, the equilibrium solubility of FFA was determined in methanol, ethanol, 1-propanol and 2-propanol at a temperature ranging from 298 to 318 K. Different models such as the modified Apelblat equation, λh equation, NRTL and Wilson were used to correlate the experimental solubility of FFA in these solvents. The enthalpy of mixing (ΔmH), entropy of mixing (ΔmS) and Gibbs energy of mixing (ΔmG) were computed in the real binary mixture of FFA – solvent to examine the nature of mixing thermodynamically.