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Background: During the dissolution of amorphous solid dispersion (ASD) formulations, the drug load (DL) often impacts the release mechanism and the occurrence of loss of release (LoR). The ASD/water interfacial gel layer and its specific phase behavior in connection with DL strongly dictate the release mechanism and LoR of ASDs, as reported in the literature. Thermodynamically driven liquid-liquid phase separation (LLPS) and/or drug crystallization at the interface are the key phase transformations that drive LoR. Methods: In this study, a combination of Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) thermodynamic modeling and in silico molecular simulation was applied to investigate the release mechanism and the occurrence LoR of an ASD formulation consisting of ritonavir as the active pharmaceutical ingredient (API) and the polymer, polyvinylpyrrolidone-co-vinyl acetate (PVPVA64). A thermodynamically modeled ternary phase diagram of ritonavir (PVPVA64) and water was applied to predict DL-dependent LLPS in the ASD/water interfacial gel layer. Microscopic Erosion Time Testing (METT) was used to experimentally validate the phase diagram predictions. Additionally, in silico molecular simulation was applied to provide further insights into the phase separation, the release mechanism, and aggregation behavior on a molecular level. Results: Thermodynamic modeling, molecular simulation, and experimental results were consistent and complementary, providing evidence that ASD/water interactions and phase separation are essential factors driving the dissolution behavior and LoR at 40 wt% DL of the investigated ritonavir/PVPVA64 ASD system, consistent with previous studies. Conclusions: This study provides insights into the potential of blending thermodynamic modeling, molecular simulation, and experimental research to comprehensively understand ASD formulations. Such a combined approach can be leveraged as a computational framework to gain insights into the ASD dissolution mechanism, thereby facilitating in silico screening, designing, and optimization of formulations with the benefit of significantly reducing the number of experimental tests. [ABSTRACT FROM AUTHOR]

This study examines intermolecular interactions in binary mixtures of N,N-dimethyl benzyl amine (DMBA) with short-chain alkoxy ethanols (2-methoxy ethanol (ME), 2-ethoxy ethanol (EE) and 2-butoxy ethanol (BE)). Densities (ρ), speeds of sound (u) and viscosities (η) were measured from 303.15 K to 313.15 K at atmospheric pressure for all compositions. These data were used to determine excess thermodynamic and transport properties: excess molar volume (VE), excess isentropic compressibility (κsE), viscosity deviation (Δη) and excess Gibbs free energy of activation (ΔG*E). Partial and infinite dilution molar partial properties were also calculated. Results focus on complex formation driven by chemical forces. The Jouyban–Acree model predicted these properties, with accuracy assessed using mean relative deviations (MRDs) and individual relative deviations (IRDs). FTIR spectroscopy provided additional insights into intermolecular interactions. [ABSTRACT FROM AUTHOR]

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The suitability of phenyl‐based deep eutectic solvents (DESs) as absorbents for toluene absorption was investigated by means of thermodynamic modeling and molecular dynamics (MD). The thermodynamic models perturbed‐chain statistical associating fluid theory (PC‐SAFT) and conductor‐like screening model for real solvents (COSMO‐RS) were used to predict the vapor–liquid equilibrium of DES–toluene systems. PC‐SAFT yielded quantitative results even without using any binary fitting parameters. Among the five DESs studied in this work, [TEBAC][PhOH] consisting of triethyl benzyl ammonium chloride (TEBAC) and phenol (PhOH), was considered as the most suitable absorbent. Systems with [TEBAC][PhOH] had lowest equilibrium pressures of the considered DES–toluene mixtures, the best thermodynamic characteristics (i.e., Henry's law constant, excess enthalpy, Gibbs free energy of solvation of toluene), and the highest self‐diffusion coefficient of toluene. The molecular‐level mechanism was explored by MD simulations, indicating that [TEBAC][PhOH] has the strongest interaction of DES–toluene compared to the other DESs under study. This work provides guidance to rationally design novel DESs for efficient aromatic volatile organic compounds absorption. [ABSTRACT FROM AUTHOR]

Using thermal adaptation of enzymes as an example, we have proposed a molecular and thermodynamic model for protein adaptation. Key concepts: (1) The working mechanism of enzymatic reactions is not altered in protein adaptation, but the activity of the adapted enzyme is expressed under altered conditions. (2) The alteration of protein conformational stability induced by gene mutation is the fundamental cause of protein adaptation. (3) The population change in active conformations of enzymes induced by protein conformational stability in different temperature ranges is the major cause of protein adaptation. (4) The features of enzyme adaptation must be analyzed or judged by two different aspects: local population change in active conformations near a critical level of an environmental factor; and the position of the whole active conformational curve in the gradient of an environmental factor. (5) Protein adaptation represents a specific mechanism for protein regulation. Several other aspects of protein adaptation are also discussed and reviewed, and specific examples are given of enzymes showing particular types of adaptation. [ABSTRACT FROM AUTHOR]

[Display omitted] The critical micelle concentration, aggregation number, shape and length of spherocylindrical micelles in solutions of zwitterionic surfactants can be predicted by knowing the molecular parameters and surfactant concentrations. This can be achieved by upgrading the quantitative molecular thermodynamic model with expressions for the electrostatic interaction energy between the zwitterionic dipoles and micellar hydrophobic cores of spherical and cylindrical shapes. The correct prediction of the mean micellar aggregation numbers requires precise calculations of the free energy per molecule in the micelles. New analytical expressions for the dipole electrostatic interaction energy are derived based on the exact solutions of the electrostatic problem for a single charge close to a boundary of spherical and cylindrical dielectric media. The obtained general theory is valid for arbitrary ratios between dielectric constants, radii of spheres and cylinders, positions, and orientations of dipoles. The detailed numerical results show quantitatively the effects of the micelle curvature and dielectric properties of the continuum media on the decrease of the dipole electrostatic interaction energy. Excellent agreement was achieved between the theoretical predictions and experimental data for the critical micelle concentration, size and aggregation number of zwitterionic surfactant micelles. This study can be extended to mixed micelles of zwitterionic and ionic surfactants in the presence of salt to interpret and predict the synergistic effect on the rheology of solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Molecular models of keratin constituent units and products of its decomposition are proposed. • Models can reproduce the interaction patters that hold the keratin macrostructure. • Energy requirements of the operations to break the keratin macromolecule were calculated. • Molecular models are competent to reproduce the main features of the operations used to dissolve and regenerate the keratin. Small-size models of keratin constituent units and products of its decomposition are proposed and computed to i) reproduce the interaction patterns that hold the macromolecule structure and its behavior under different reaction media and physico-chemical conditions; ii) estimate the energy of interactions that support the tridimensional structure of the protein, and consequently, the energy requirements to break it. To create these models and evaluate their performance, quantum-chemical, COSMO, and COSMO-RS calculations were performed. They seem to be capable to support process simulations during the conceptual design and optimization of operations and processes to transform the raw keratin into products of higher added value. Besides, proper analyses using these models demonstrated that the cleavage of the disulfide bonds is the primary condition to break the macromolecule but additionally, the intramolecular H-bond network should be dissociated enabling the intramolecular interaction with the chemicals used to dissolve and regenerate the keratin. [ABSTRACT FROM AUTHOR]

Environmental pollution poses a major problem now a day. Several dyes, in the form of industrial waste, pollute water body and may cause adverse effects to human health. In this paper ADME and toxicity of fives Phenothiazinium group of dyes Methylene blue (MB), Azure A (AA), Azure B (AB), Azure C (AC) and Toluidine Blue O (TBO) were predicted using Swiss ADME and Protox II tools. Results showed these dyes may herm for living organism due to their carcinogenic, mutagenic and hepatotoxic properties. Removal efficiency of these dyes using okra plant product were determined using spectroscopic, thermodynamic and molecular modeling study. It was revealed that these dyes adsorb on the surface of okra leaf mostly at pH 7.0 and the adsorption isotherms were found to fit in Langmuir and Freundlich isotherm model, while Temkin model fails to do this. Mucilage present in different parts of okra plant plays a significant role on removal of these dyes and is able to remove near about 71–92 % of dyes from water body by itself. As this process did not fit in any of above said adsorption isotherm model, it may be suggested that some other mechanism may happen. Further studies explore that these dyes bound to the hydrophobic pocket of mucilage with binding affinity in the order of 105 M−1 and the bindings were exothermic in nature with enthalpy change in the range of − 2.94 to − 4.28 kcal/mole. Molecular docking study validate all the experimental results obtained from spectroscopic and thermodynamic study and enlighten the role of structure of dyes on their binding affinity to mucilage. This paper will help to systematically understand the role of okra plant products on removal efficiency of Phenothiazinium group of dyes with their structural variations. [Display omitted] • Swiss ADME and Protox II showed phenothiazinium group of dyes may be hazardous to human health. • These dyes can be removed from water body using okra plant product and the optimum pH of removal is 7.0. • Dyes adsorb on okra leaf and the adsorption fit to Langmuir, and Freundlich model. • Removal of dyes using okra plant product follow pseudo 1st order kinetics. • The dyes can bound to mucilage through exothermic reaction process, and the binding controlled by overall structure of dyes. [ABSTRACT FROM AUTHOR]

Combining three numerical methods (forward flux sampling, seeding of droplets, and finite-size droplets), we probe the crystallization of hard spheres over the full range from close to coexistence to the spinodal regime. We show that all three methods allow us to sample different regimes and agree perfectly in the ranges where they overlap. By combining the nucleation work calculated from forward flux sampling of small droplets and the nucleation theorem, we show how to compute the nucleation work spanning three orders of magnitude. Using a variation of the nucleation theorem, we show how to extract the pressure difference between the solid droplet and ambient liquid. Moreover, combining the nucleation work with the pressure difference allows us to calculate the interfacial tension of small droplets. Our results demonstrate that employing bulk quantities yields inaccurate results for the nucleation rate. [ABSTRACT FROM AUTHOR]

A new predictive molecular thermodynamic model (i.e., modified COSMO‐SAC‐UNIFAC) was first proposed and extended to predict the solubility of CO2 in pure and mixed ionic liquids (ILs) at the temperatures down to 263.2 K. It is interesting to discover that with equimolar amounts, the solubility of CO2 in such 1:1 IL pairs, that is, [A1][B1] + [A2][B2] and [A1][B2] + [A2][B1], was consistent at the same temperature and pressure in the case of exchanging their respective cations and anions. The molecular dynamic (MD) simulation for CO2 + mixed ILs was performed to deeply analyze and explain this intriguing phenomenon. Not only the CO2 gas drying experiment with the ILs ([C2mim][OAc], [C2mim][dca], and [C2mim][OAc] + [C2mim][dca]) as absorbents but also the corresponding process simulation and optimization were made to stress the effectiveness and applicability of the new thermodynamic model. Thus, this work ranges from molecular level to systematic scale. [ABSTRACT FROM AUTHOR]

• Investigated phase equilibria of alkali tetraborate and bromide in brines. • Constructed phase diagram and density-composition diagram based on experimental data. • Established a molecular model based on DFT to predict the phase equilibria. • Considered the primary forms of polyborate ions in solution. • An important reference for the separation of alkali tetraborate and bromide. The multitemperature stable phase equilibria of alkali tetraborate and bromide were investigated by isothermal dissolution equilibrium method. Based on the experimental data, the phase diagrams and the density-composition diagrams of the ternary systems were drawn respectively. The results demonstrate that the phase diagrams of alkali tetraborate and bromide ternary systems with water as solvent at 273.2 K, 288.2 K and 308.2 K consist of one invariant point, two univariate solubility curves and two crystallization fields. The density at the invariant points is greater than that at the adjacent points. Additionally, based on density functional theory (DFT), a molecular model of phase equilibria of alkali tetraborate and bromide was creatively established to predict the phase equilibrium solubilities of the ternary systems. Based on results of Raman spectra identification of borate ions in the ternary mixed solutions, the primary forms of borate ions in solution, namely B(OH) 3 , B(OH) 4 −, B 3 O 3 (OH) 4 − and B 4 O 5 (OH) 4 2− were comprehensively considered in this work. By comparing the experimental data of these ternary systems with the calculated results of the DFT model, it is found that the DFT model can describe the solid–liquid equilibria of the ternary systems well, and has high accuracy. The investigation of the multitemperature stable phase equilibria of alkali tetraborate and bromide can provide thermodynamic data for separation of alkali tetraborates and bromides in brines. [ABSTRACT FROM AUTHOR]

[Display omitted] Lipid-based drug delivery systems hold immense promise in addressing critical medical needs, from cancer and neurodegenerative diseases to infectious diseases. By encapsulating active pharmaceutical ingredients – ranging from small molecule drugs to proteins and nucleic acids – these nanocarriers enhance treatment efficacy and safety. However, their commercial success faces hurdles, such as the lack of a systematic design approach and the issues related to scalability and reproducibility. This work aims to provide insights into the drug-phospholipid interaction by combining molecular dynamic simulations and thermodynamic modelling techniques. In particular, we have made a connection between the structural properties of the drug-phospholipid system and the physicochemical performance of the drug-loaded liposomal nanoformulations. We have considered two prototypical drugs, felodipine (FEL) and naproxen (NPX), and one model hydrogenated soy phosphatidylcholine (HSPC) bilayer membrane. Molecular dynamic simulations revealed which regions within the phospholipid bilayers are most and least favoured by the drug molecules. NPX tends to reside at the water-phospholipid interface and is characterized by a lower free energy barrier for bilayer membrane permeation. Meanwhile, FEL prefers to sit within the hydrophobic tails of the phospholipids and is characterized by a higher free energy barrier for membrane permeation. Flory-Huggins thermodynamic modelling, small angle X-ray scattering, dynamic light scattering, TEM, and drug release studies of these liposomal nanoformulations confirmed this drug-phospholipid structural difference. The naproxen-phospholipid system has a lower free energy barrier for permeation, higher drug miscibility with the bilayer, larger liposomal nanoparticle size, and faster drug release in the aqueous medium than felodipine. We suggest that this combination of molecular dynamics and thermodynamics approach may offer a new tool for designing and developing lipid-based nanocarriers for unmet medical applications. [ABSTRACT FROM AUTHOR]

• DFT calculations were performed on the adsorption and reaction behaviors of room environment gases (i.e., O 2 , H 2 , H 2 O) on the PuO 2 (111) surface. • The stoichiometric PuO 2 (111) slab is inert under O 2 atmosphere within a large temperature and pressure range. • H 2 O prefers to stay as molecular state when adsorbing on PuO 2 (111) and dissociative adsorption of H 2 remains thermodynamically stable at H 2 -pressure as low as ∼10−35 bar under room temperature. • Kinetic analysis reveals the dynamical properties of PuO 2 surface under H 2 -rich atmosphere with increased temperature. Adsorption and reaction properties of environmental gases including O 2 , H 2 , and H 2 O on the PuO 2 (111) surface were studied via density functional theory simulations along with thermodynamic and kinetic analysis. Simulation results show that the stoichiometric PuO 2 (111) remains intact under O 2 atmosphere and extremely low or high O 2 pressure is required to form oxygen vacancy or adsorbed-O on the surface. The H 2 O prefers to stay as molecular state when adsorbing on PuO 2 (111) and a relatively high humidity is required for H 2 O to be stably binding on the surface. For H 2 interaction with PuO 2 , the dissociative adsorption of H 2 molecule induces reduction of Pu(IV) ions to Pu(III), and remains thermodynamically stable at H 2 pressure as low as ∼10−35 bar under room temperature. Kinetic modeling shows that at temperature below 350 K, the PuO 2 (111) surface is mainly covered by OH species when exposing to H 2 environment while bare metal sites appear with increased temperature and reaction time. [Display omitted] [ABSTRACT FROM AUTHOR]

The present work describes a new method to compute accurate spin densities for open shell systems. The proposed approach follows two steps: first, it provides molecular orbitals which correctly take into account the spin delocalization; second, a proper CI treatment allows to account for the spin polarization effect while keeping a restricted formalism and avoiding spin contamination. The main idea of the optimization procedure is based on the orbital relaxation of the various charge transfer determinants responsible for the spin delocalization. The algorithm is tested and compared to other existing methods on a series of organic and inorganic open shell systems. The results reported here show that the new approach (almost black-box) provides accurate spin densities at a reasonable computational cost making it suitable for a systematic study of open shell systems. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) are currently at the research frontier of metallic materials. Understanding the solid solubility limit in HEAs, such a highly concentrated multicomponent alloy system, is scientifically intriguing. It is also technically important to achieve desirable mechanical properties by controlling the formation of topologically or geometrically closed packed phases. Previous approaches to describe the solid solubilities in HEAs could not accurately locate the solubility limit and have to utilize at least two parameters. Here, we propose to use a single parameter, the average energy of d-orbital levels, Md, to predict the solid solubility limit in HEAs. It is found that Md can satisfactorily describe the solid solubilities in fcc structured HEAs containing 3 d transition metals, and also in bcc structured HEAs. This finding will greatly simplify the alloys design and lends more flexibility to control the mechanical properties of HEAs. When 4 d transition metals are alloyed, Md alone cannot describe the solid solubility limit in fcc structured HEAs, due to the large increase of the bond strength that can be gauged by the bond order, Bo. The potential opportunities and challenges with applying the molecular orbital approach to HEAs are discussed. [ABSTRACT FROM AUTHOR]

• Accurate molecular thermodynamic model for R513A/lubricants in refrigeration cycles. • Rigorous energetic investigation of refrigeration cycles with thermodynamic postulates. • PEC5 optimal lubricant for R513A, in view of solubility, miscibility and viscosity. • Procedure allowed quantifying impact of the presence of lubricant on the COP. • Presence of PEC5 in the mixture up to 5% weight led to COP decrease of 3%. Following environmental regulations, refrigerant R134a (Global Warming Potential GWP = 1430), commonly used in air conditioning applications, is required to be replaced by refrigerants with lower GWP. Among them, R513A is investigated as an excellent alternative, with a GWP reduction of 56% compared to R134a. However, further studies are needed in order to assess its use for this application. In this work, the molecular-based polar soft-SAFT equation has been employed to predict the vapour-liquid equilibria (VLE) of R513A and selected lubricants, searching for the optimal lubricant and their performance on a vapour compression refrigeration cycle. First, the binary VLE of the commercial lubricants from the Pentaerythritol Esters (PECs) and Polyethylene Glycol Dimethyl Ethers (PEGDMEs) families with R1234yf and R134a were assessed versus available experimental data, by developing the appropriate molecular models and parameters. Then, the models were used to predict the properties of the ternary mixtures containing the two refrigerants and the lubricants. PEC5 was found to be the optimal lubricant for R513A, considering a balance between solubility, miscibility and viscosity. Molecular modelling combined with thermodynamic and energetic analysis allowed to calculate the performance of a vapour compression refrigeration cooling cycle, quantifying the impact of the presence of the lubricant on the COP. The presence of PEC5 in the mixture was not significant, staying below a COP decrease of 3% in all cases considered, while for TrEGDME, its presence reduced the COP up to 6.1%. The procedure used here allows tuning the performance of the refrigerant/lubricant pair, in a step forward on the search for low GWP refrigerants in air conditioning systems. [Display omitted] [ABSTRACT FROM AUTHOR]

A thermodynamic potential accounting for molecular interactions is used to gain insights into fluid phase molecular interactions over a wide range of temperature and density. It is a lattice based mean field approximation incorporated into a Helmholtz equation of state (EOS) for pure fluids. Excess molar Helmholtz energy is f e = ε − T s c , where ε is thermodynamic interaction potential energy and s c is configurational entropy. (This is not the usual definition of excess over ideal; here P = − (∂ f e / ∂ v) T.) The work shows that at low temperatures ε has the characteristics of a mechanical potential such as the Lennard-Jones potential but with a temperature dependence. At low temperatures there is a definite potential energy well that is washed away by rising temperature. At high temperatures net interactions are strictly repulsive. In the liquid state ε can be calculated using Lennard-Jones Devonshire cell theory for spherically symmetric molecules. This is demonstrated with neon, argon, krypton, and xenon. Van der Waals EOS, when recast as a lattice model, exhibits similar interaction potential behavior as found in this work. A method is proposed for separating potential energy arising from intramolecular bonds from that arising from intermolecular interactions, allowing for models of mixtures with different size molecules. This is demonstrated in a series of n-alkanes. [ABSTRACT FROM AUTHOR]

In this work, seven acrylonitrile derivatives were selected as potential inhibitors of fat and obesity‐related proteins (FTO) by the aid of fluorescence spectroscopy, ultraviolet visible spectroscopy, molecular docking, and cytotoxicity methods. Results show that the interaction between 3‐amino‐2‐(4‐chlorophenyl)‐3‐phenylacrylonitrile (1a) and FTO was the strongest among these derivatives. Thermodynamic analysis and molecular modeling show that the main force between 1a and FTO is hydrophobic interaction. The cytotoxicity test showed that the IC50 value of 1a was 46.64 μmol/L, which indicated 1a had the smallest IC50 value and had the best inhibitory effect on the proliferation of leukemia K562 cells among the seven derivatives. Both our previous results and this work show that chlorine atoms play important role in the binding of small molecules and FTO. This work brings new information for the study of FTO inhibitors. [ABSTRACT FROM AUTHOR]

The aggregation number and length of spherocylindrical (rodlike, wormlike) micelles in solutions of an ionic surfactant and salt can be predicted knowing the molecular parameters and the input concentrations of the species. This can be achieved by upgrading the quantitative molecular thermodynamic model from the previous parts of this series with an expression for the electrostatic component of micelle scission energy that is the excess free energy of the spherical endcaps with respect to the cylindrical part of the micelle. The thermodynamics of micellization is extended to the case of multicomponent system, which may contain several surfactants (both ionic and nonionic) and salts, taking into account the effect of counterion binding in the Stern layer on the micellar surface. Furthermore, the considerations are focused on a system that consists of single ionic surfactant plus salt. Excellent agreement was achieved between the theoretical model and experimental data for wormlike micelles from anionic and cationic surfactants at various concentrations of salt and temperatures. In accord with the experimental observations, at high salt concentrations, the model predicts loss of chemical equilibrium between the endcaps and cylindrical part of the wormlike micelles, which implies transition to self-assemblies of other, e.g. branched, morphology or the onset of crystallization and phase separation. [ABSTRACT FROM AUTHOR]

Several approaches to predict and model drug solubility have been used in the drug discovery and development processes during the last decades. Each of these approaches have their own benefits and place, and are typically used as standalone approaches rather than in concert. The synergistic effects of these are often overlooked, partly due to the need of computational experts to perform the modeling and simulations as well as analyzing the data obtained. Here we provide our views on how these different approaches can be used to retrieve more information on drug solubility, ranging from multivariate data analysis over thermodynamic cycle modeling to molecular dynamics simulations. We are discussing aqueous solubility as well as solubility in more complex mixed solvents and media with colloidal structures present. We conclude that the field of computational pharmaceutics is in its early days but with a bright future ahead. However, education of computational formulators with broad knowledge of modeling and simulation approaches is imperative if computational pharmaceutics is to reach its full potential. [ABSTRACT FROM AUTHOR]

The thermodynamic scaling of molecular dynamic properties of rotation and thermodynamic parameters in a nematic phase was investigated by a molecular dynamic simulation using the Gay-Berne potential. A master curve for the relaxation time of flip-flop motion was obtained using thermodynamic scaling, and the dynamic property could be solely expressed as a function of TVγτ, where T and V are the temperature and volume, respectively. The scaling parameter γτ was in excellent agreement with the thermodynamic parameter Γ, which is the logarithm of the slope of a line plotted for the temperature and volume at constant P2. This line was fairly linear, and as good as the line for p-azoxyanisole or using the highly ordered small cluster model. The equivalence relation between Γ and γτ was compared with results obtained from the highly ordered small cluster model. The possibility of adapting the molecular model for the thermodynamic scaling of other dynamic rotational properties was also explored. The rotational diffusion constant and rotational viscosity coefficients, which were calculated using established theoretical and experimental expressions, were rescaled onto master curves with the same scaling parameters. The simulation illustrates the universal nature of the equivalence relation for liquid crystals. [ABSTRACT FROM AUTHOR]

In this study, the modified square well model is combined with perturbed-hard-trimer-chain (PHTC) EOS to correlate the surface tension of normal alkanes and refrigerant fluids. The performance of the proposed model has been evaluated by calculating the surface tension of 15 hydrocarbons range within 112–440 K and pressures up to 4.72 × 10−6 MPa. From 251 data points examined the average relative deviation (ARD) of the correlated and calculated densities and surface tension from the experimental ones was found to be 1.63% and 2.46%. Besides, some surface thermodynamic functions such as the surface entropy (SS) and surface enthalpy (HS) of studied liquids were also computed via our method. The ARD (in %) were found to be equal to 3.94 and 2.44, respectively. Finally, our method has also been employed to estimate the critical temperature of 15 hydrocarbons with ARD (in %) equal to 7.92. R13: Chlorotrifluoromethane, R12: Dichlorodifluoromethane, R143a: Ethane, 1,1,1-trifluoro [ABSTRACT FROM AUTHOR]

• A soft-SAFT molecular model is used to describe HFOs for refrigeration. • Density, surface tension, derivative properties and viscosity are perfectly reproduced. • Binary mixtures of HFOs and HFO-HFC are described in agreement with data. • Thermodynamics of ternary mixtures are predicted without any fitting parameter. • The CoP of several new mixtures is evaluated with process simulation. This work presents a thermodynamic model that characterizes 4th-generation hydrofluoroolefins (HFOs)-based refrigerants with the molecular-based soft-SAFT equation of state (Blas and Vega, 1998) as well as its application in process simulations for a selected refrigeration application. The evaluation of the HFOs has been done building on a molecular model transferred from the equivalent hydrofluorocarbons (HFCs), taking advantage of the similarities between the two chemical families. The model has been used to calculate all thermophysical properties of the selected HFOs relevant for their application as refrigerants, including the saturated density, vapor pressure, heat capacity, speed of sound, surface tension and viscosity, providing good agreement with experimental available data. In addition, phase equilibria, interfacial behavior and viscosity calculations have been performed for blends between HFCs and the two most common HFOs, R1234yf and R1234ze(E). The obtained thermodynamic properties have been used for a process simulation of a vapor compression refrigeration system, comparing the 3rd generation refrigerant R410A with these 4th generation blends, including the Coefficient of Performance for different cases, in order to establish the best alternative to R410A. Overall, this work shows how molecular modeling tools can be used now a day, as a complementary tool to generate reliable data for process simulation, in this case related to the search for alternative refrigerants. [ABSTRACT FROM AUTHOR]

• An optimization-based methodology is proposed for inert reaction solvent design. • A GC-based reaction thermodynamic model is developed to make fast K L calculations. • A SMARTS-based reaction generation algorithm is used to synthesize byproducts. • An MINLP model is established and a decomposition-based strategy is applied. • Two case studies indicate feasibility and effectiveness of the methodology. Solvents have been widely used in process manufacturing industries. When involved in liquid-phase organic synthesis reactions, solvents can reduce the activation energy of reactions between the reactants and the transition state through solvation effects. However, undesirable side reactions can also be performed between solvents and the reaction system (the reactants and products), which should be avoided for producing unnecessary byproducts in the reaction system. In this paper, an optimization-based methodology is proposed for inert reaction solvent design. In this method, first, a Group Contribution (GC)-based reaction thermodynamic model is developed to quantitatively identify the thermodynamic feasibility of side reactions between solvents and the reaction system. Then, the SMARTS (SMiles Arbitrary Target Specification)-based reaction generation algorithm is employed to generate possible side reactions between solvents and the reaction system, helping to integrate the developed GC-based reaction thermodynamic model with the Computer-Aided Molecular Design (CAMD) problem for designing inert reaction solvents through the formulation and solution of the Mixed-Integer Non-Linear Programming (MINLP) model. Due to the nonlinear equations in the MINLP model, a decomposition-based solution strategy is employed to solve the optimization problem. Finally, two case studies are presented to demonstrate the feasibility and effectiveness of the proposed optimization-based methodology for promising inert reaction solvent design. [ABSTRACT FROM AUTHOR]

The present study evaluates the physical stability and intermolecular interactions of Rivaroxaban (RXB) amorphous solid dispersions (ASDs) in polymeric carriers via thermodynamic modelling and molecular simulations. Specifically, the Flory-Huggins (FH) lattice solution theory was used to construct thermodynamic phase diagrams of RXB ASDs in four commonly used polymeric carriers (i.e. copovidone, coPVP, povidone, PVP, Soluplus, SOL and hypromellose acetate succinate, HPMCAS), which were stored under 0%, 60% and 75% relative humidity (RH) conditions. In order to verify the phase boundaries predicted by FH modelling (i.e. truly amorphous zone, amorphous-amorphous demixing zones and amorphous-API recrystallization zones), samples of ASDs were examined via polarized light microscopy after storage for up to six months at various RH conditions. Results showed a good agreement between the theoretical and the experimental approaches (i.e. coPVP and PVP resulted in less physically-stable ASDs compared to SOL and HPMCAS) indicating that the proposed FH-based modelling may be a useful tool in predicting long-term physical stability in high humidity conditions. In addition, molecular dynamics (MD) simulations were employed in order to interpret the observed differences in physical stability. Results, which were verified via differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), suggested the formation of similar intermolecular interactions in all cases, indicating that the interaction with moisture water plays a more crucial role in ASD physical stability compared to the formation of intermolecular interactions between ASD components. [ABSTRACT FROM AUTHOR]

[Display omitted] • The solubility of 3-aminophenol was measured in different pure solvents from 283.1 to 323.1 K. • The density of pure solvents and the saturated 3-aminophenol solutions were measured. • The Wilson, NRTL, UNIQUAC, and NRTL-SAC models were used in the modeling. • The predictive models UNIFAC, UNIFAC-DMD, and COSMO-SAC were used. • The values of solvation free energy obtained by molecular dynamics are in agreement with the experimental data. The solubility of 3-aminophenol was measured in water, isopropanol, ethyl acetate, chloroform, and tert -butyl methyl ether (MTBE) from 283.1 to 323.1 K at atmospheric pressure. In addition, the density of pure solvents and the saturated 3-aminophenol solutions was measured. The experimental solubility data were correlated and predicted using four types of thermodynamic models, including correlative (Wilson, NRTL, and UNIQUAC), semi-predictive (NRTL-SAC, and UNIQAUC-SAC), predictive group contribution methods (UNIFAC, and UNIFAC-DMD), and pure predictive COSMO-SAC model. The NRTL-SAC and UNIQUAC-SAC as semi-predictive models were used to obtain 3-aminophenol conceptual segment numbers, and then, using the NRTL-SAC model, the solubility of 3-aminophenol was predicted in 58 FDA approved solvents in the pharmaceutical industry. The predictive models including UNIFAC and UNIFAC-DMD were also used to predict the 3-aminophenol solubility and compared with the experimental data. The results of the COSMO-SAC model have a large deviation from experimental data. In addition, the experimental solubility data were correlated using the PR equation of state with relative success. The segment-based models such as NRTL-SAC and UNIQUAC-SAC are suggested in the fast solvent screening procedure. Finally, the standard dissolution enthalpy (Δ dis H), the standard dissolution entropy (Δ dis S), and the standard dissolution Gibbs energy (Δ dis G) of 3-aminophenol in the selected solvents were calculated by the Van't Hoff model and the Gibbs-Helmholtz equation. These values imply that the solubility of 3-aminophenol is an entropy-driven non-spontaneous endothermic process in all chosen single solvents. Using the molecular dynamic (MD) simulation the solvation free energy of 3-aminophenol was calculated. The order of the absolute value of free energy of solvation is as ethyl acetate > isopropanol > MTBE > water > chloroform which is consistent with the order of solubility data. [ABSTRACT FROM AUTHOR]

To meet the growing demand for protein in underdeveloped countries, the extraction of protein from inexpensive manufacturing by-products plays a crucial role in unlocking the potential of underutilized proteins for food purpose. However, animal-derived protein isolate products often exhibit noticeable off-flavors, significantly hindering the processability of the extracted proteins due to coextraction of off-flavor components that interact with proteins. This work examined the effects of UHP pretreatment (350 MPa/10 min/28 °C) on the interaction between trans , trans -2,4-heptadienal, a representative of off-flavor compounds, and duck liver protein (DLp). The results of multi-spectroscopic characterization suggested the presence of pressure-induced molten globule state (MGs)-like proteins, explaining the increased binding constant values following pressurization. Static quenching was demonstrated during the interaction process between trans , trans -2,4-heptadienal and DLp, without forming novel secondary binding sites. Thermodynamic analysis showed that the spontaneous binding process was mainly driven by hydrogen bonds and van der Waals forces, as corroborated by molecular modeling methodologies, demonstrating the roles of UHP-mediated conformational compression in affecting the flavor-protein complex formation. The interaction of trans , trans -2,4-heptadienal with DLp altered the protein thermostability, which was compromised by UHP pretreatment. The denaturation enthalpy of DLp samples decreased from 1879 J/g to 1225 J/g after UHP, validating the reduced thermostability by UHP and the varied interaction processes of trans , trans -2,4-heptadienal with folded and MGs-like DLp. This investigation demonstrated the tunable interaction processes of off-flavor components with matrix proteins by introducing suitable physical disturbance prior to extraction. [Display omitted] • Trans , trans -2,4-heptadienal (TH) non-covalently bound to duck liver protein (DLp). • Thermodynamics by DSF and DSC confirmed the binding behaviors of TH with DLp. • Pressurization at 350 Mpa/10 min induced the molten-globule state (MGs) of DLp. • UHP significantly weakened the thermostability of TH-DLp complexes. • Molecular dynamic simulation coincided well with the experimental results. [ABSTRACT FROM AUTHOR]

This work explores the optimum detergency conditions of alkyl ethoxylate (CXEOY) surfactants with the integrated free energy model (IFEM). IFEM is a molecular thermodynamic model that calculates the free energy of formation of oil‐swollen spherical micelles, with a core solubilization radius Ro, using surfactants from empty (oil‐free) micelles and oil molecules from a continuous oil phase. The described geometry allows for rapid calculations, using a personal laptop (3.4 GHz processor), where each solubilization energy profile (free energy vs. Ro curve) can be solved in 5 min or less. While previous work showed quantitative agreement between IFEM predictions and experimental solubilization of alkanes in CXEOY micelles, this work explores the possibility of using IFEM as a tool in surfactant selection. Experimental work has shown that detergency improved when operating near the phase inversion temperature (PIT) of the surfactant‐hexadecane system. The IFEM simulations in this work show, for the first time, that IFEM can be used to predict the PIT of surfactant‐oil systems, and that the surfactants selected via this method are consistent with the selection guided by experimental observations. [ABSTRACT FROM AUTHOR]

As part of the effort to develop a comprehensive molecular thermodynamic model for high salinity produced water based on the electrolyte nonrandom two-liquid theory, this work presents the model results for the aqueous Na+-K+-Mg2+-Ca2+-SO 4 2− quinary system. With the binary interaction parameters fully parameterized for the water-electrolyte pairs and the electrolyte-electrolyte pairs, the model satisfactorily describes the thermodynamic properties for the aqueous quinary system and its binary, ternary, and quaternary subsystems for the temperature range 273.15–473.15 K and the salt concentrations up to saturation. The model results are compared with the salt solubility and thermodynamic data available for the subsystems with special attention to systems involving (Ca2+ SO 4 2−). [ABSTRACT FROM AUTHOR]

The interactions of human haemoglobin (HHb) with 5-epi-taiwaniaquinone G (G1) and one structural analogue of 5-epi-taiwaniaquinone G (G2) systematically by UV–vis absorption spectroscopy and fluorescence spectroscopy in combination with molecular modelling are studied in this paper. They caused the fluorescence quenching of HHb by the formation of complex. The binding constants and thermodynamic parameters were obtained. The hydrophobic and electrostatic interactions were the predominant intermolecular forces to stabilise these complexes. Results of thermodynamic analysis and molecular modelling showed that G2 was the stronger quencher and bound to HHb with higher affinity. The result of molecular modelling is close to that obtained by experimental methods. [ABSTRACT FROM AUTHOR]

Abstract This work addresses the molecular thermodynamic and artificial neural network (ANN) modeling of surface tensions of several fatty acid esters and biodiesels. Two biodiesels were considered as pure fluid and the other as a binary mixture. The molecular thermodynamic model is based on the statistical mechanical expression according to Fowler-Kirkwood-Buff approximation. Regarding this, contributions to surface tension from the hard-chain repulsions, Lennard-Jones dispersion forces, and dipolar interactions were considered and assumed to be additive in the model development. The molecular thermodynamic model used three molecular parameters reflecting the hard-core diameter, dispersive energy and segment number as well as the liquid densities for which the values were predicted from perturbed Yukawa-chain equation of state. Further, the model used dipole moment as an adjustable parameter for the accurate calculation of surface tensions. The model could predict 149 surface tension data points for 9 FAEs and 3 biodiesels in 268.6–393 K range with the average absolute relative deviation (AARD) of 1.82%. The degree of accuracy of proposed model has also been compared with some empirical equations. Concerning ANN modeling, a network comprising two hidden layers and 9 neurons for each layer has been trained, according to the constructive approach. The result of the training was quite good, the AARD of the pure fluid dataset of 137 points was found to be 0.44%. Graphical abstract Unlabelled Image Highlights • Surface tension calculation of FAEs and biodiesels based on two different approaches • Molecular thermodynamic modeling based on FKB approximation • ANN modelling with 3 input parameters, 2 layers and 9 neurons for each layer. [ABSTRACT FROM AUTHOR]

Abstract Supercritical carbon dioxide (scCO 2) is widely used in separation processes applied to the food, chemistry, pharmaceutical and material industries. The knowledge of the solubility of solid solutes in scCO 2 , with or without cosolvents, is essential for the design and optimization of extraction, fractionation and purification processes. This work evaluates the accuracy of Cubic Plus Association equation of state (CPA-EoS) to predict the solubility of solutes in ternary and/or quaternary systems from the binary interaction parameters. The solubility of 12 solid solutes in scCO 2 in presence of different organic cosolvents was investigated, totalizing 19 systems at pressures between 8 and 40 MPa, temperatures ranging from 308 K to 353 K and concentrations of cosolvent varying from 0.73 to 10 mol%. The overall average logarithmic deviation (ALD) between experimental and calculated data with CPA-EoS was 0.47, which is better than that obtained with PR + COSMOSAC previously reported in the literature. Furthermore, the effects of temperature, pressure and of cosolvent type and concentration on the solubility were well estimated with the CPA-EoS. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Highlights • The epitaxial S-K InAs/InP(0 0 1) growth is impacted by As/P exchange process. • Two transitions have been observed in S-K InAs/InP(0 0 1) growth (three regimes). • Three regimes are: 2D layer, large 3D islands, and quantum dots growth. • The truncated pyramidal large 3D islands transform into spherical cap quantum dots. • All experimental transitions are explained through thermodynamic modeling. Abstract Quantum Dots (QDs) are considered as an efficient building block of many optoelectronic applications, such as semiconductor laser, photodetector, whereby their physical dimension is the key parameter to be controlled. In this work, we have studied experimentally the growth of InAs QDs on InP(0 0 1) substrate by MOVPE and established a theoretical model explaining the observed epitaxial behaviour. In variance with the classical Stranski-Krastanov growth, we show that during the growth there is an intermediate stage whereby although first large 3D islands are formed, an increased density of small QDs is formed concurrent with the shrinkage of the large 3D islands. As a result, the growth can be divided into three regimes: 2D layer growth, large 3D islands growth and QDs growth. To explain this evolution, a thermodynamic model has been developed accounting for the process driven by surface energy, elastic relaxation energy and inter-island interaction energy. It will be shown that the balance between the surface energy and the elastic relaxation energy provides the transition from 2D layer to large 3D islands (around at 3 ML of InAs growth). This model also supports the energetically favourable truncated pyramidal shape for large 3D islands and the spherical cap shape for QDs. We show in this paper that a balance between surface energy, elastic relaxation energy and inter-island elastic interaction explains the volume shrinkage of the early large 3D islands towards the formation of small QDs in high density. [ABSTRACT FROM AUTHOR]

Highlights • A statistical methodology for estimating dense gas EOS coefficients from data is investigated based on a Bayesian framework. • The Bayesian mixture of models and scenarios (BMSA) is applied in the context of dense gas ows. • A comparison between single and multiple reference data inferences is drawn. • A new approach for estimating the prior mass function of the scenarios is proposed. Abstract A Bayesian approach is developed to quantify uncertainties associated with the thermodynamic models used for the simulation of dense gas flows, i.e. flows of gases characterized by complex molecules of moderate to high molecular weight, in thermodynamic conditions of the general order of magnitude of the liquid/vapor critical point. The thermodynamic behaviour of dense gases can be modelled through equations of state with various mathematical structures, all involving a set of material-dependent coefficients. For several organic fluids of industrial interest abundant and high-quality thermodynamic data required to specify such coefficients are hardly available, leading to undetermined levels of uncertainty of the equation output. Additionally, the best choice for the kind of equation of state (mathematical form) to be used is not always easy to determine and it is often based on expert opinion. In other terms, equations of state introduce both parametric and model-form uncertainties, which need to be quantified to make reliable predictions of the flow field. In this paper we propose a statistical inference methodology for estimating both kinds of uncertainties simultaneously. Our approach consists of a calibration step and a prediction step. The former allows to infer on the parameters to be input to the equation of state, based on the observation of aerodynamic quantities like pressure measurements at some locations in the dense gas flow. The subsequent prediction step allows to predict unobserved flow configurations based on the inferred posterior distributions of the coefficients. Model-form uncertainties are incorporated in the prediction step by using a Bayesian model averaging (BMA) approach. This consists in constructing an average of the predictions of various competing models weighted by the posterior model probabilities. Bayesian averaging also provides a useful tool for making robust predictions from a set of alternative calibration scenarios (Bayesian model-scenario averaging or BMSA). The proposed methodology is assessed for a class of dense gas flows, namely transonic flows around an isolated airfoil, at various free-stream thermodynamic conditions in the dense-gas region. [ABSTRACT FROM AUTHOR]

Abstract In the Migmatite Complex from NE Sardinia, a large lensoid body of coarse-grained, dark-green amphibolite with a schistose to weakly massive aspect crops out. Within this amphibolite centimetre-sized layers locally occur which contain millimetric porphyroblastic garnet. We investigated the amphibolite and the layers applying microstructural analyses and thermodynamic modelling in the NCKFMASH+Ti + Mn system in order to reconstruct the pressure-temperature (P-T) metamorphic evolution. The amphibolite underwent a burial path, recorded by the compositional zoning of garnet, that started at pressures of 0.8 GPa and showed only a slight increase in temperature leading to peak P-T conditions. The garnet rim records peak P-T conditions of 1.3–1.4 GPa at 690–740 °C. As the early exhumation of the amphibolites occurred already at lower temperatures than the burial, an anticlockwise P-T path results which is in contrast to the typical clockwise P-T paths reported for several high-pressure metamorphic rocks from NE Sardinia. We interpret the anti-clockwise path by the location of the studied rocks in the lowermost part of the upper plate and their burial to depths of around 45 km during the Variscan continental collision between Laurussia and Gondwana. This process could have affected some rock slices of the upper plate only owing to tectonic erosion by the downgoing plate. The subsequent uplift occurred in an exhumation channel where these slices were continuously cooled by the upper portion of the lower continental plate. Highlights • First occurrence of anticlockwise P-T path in Sardinia • Anti-clockwise path indicates location in the lowermost part of the upper plate. • Eclogites and amphibolites experienced similar decompression from amphibolite facies. [ABSTRACT FROM AUTHOR]

• Molecular statistical thermodynamic model was used to capture changes in standard molar Gibbs energy of formation of aqueous species. • The model was extended into sub- and super-critical conditions. • Known equilibrium constants for ion association and solubility limits were used to validate the modelling results. The need for sustainable power generation has increased interest in the use of hydrothermal fluids for industrial applications. New high-enthalpy geothermal systems and biowaste-to-fuel processes are two relevant examples that employ supercritical fluids which require an in-depth understanding of complex chemical reactions occurring near the supercritical temperature of water (374 °C). As these processes operate in thermodynamic regimes that are not currently covered by a standard molar Gibbs energy of formation model, only empirical fits for single reaction systems are available which limit the use of multi-component phase equilibria calculations that are standard practice for less extreme environments. Here, we advance a standard molar Gibbs energy of formation model able to operate in these otherwise inaccessible thermodynamic states to include species needed for key mineral solubility systems and ion association reactions. This work extends a model based on molecular statistical thermodynamics (MST) into four new systems (Na 3 PO 4 -H 2 O, LiOH-H 2 O, KOH-H 2 O, and BaSO 4 -H 2 O) by extending the model to cover 10 new species. For each of these systems, model predictions were consistently within the experimental uncertainties for the new systems covered. A breakdown of MST contributions to the model revealed that electrostatic and hard sphere contributions were key to reproducing density dependencies of standard molar Gibbs energy of formation values around the critical point of water. [ABSTRACT FROM AUTHOR]

We present a coarse-grained model for O-(2-hydroxyethyl) cellulose (HEC) in order to obtain its intrinsic viscosity by applying three theoretical models and Monte Carlo computer simulations (MC). Results are based on a previous experimental study for this substance at neutral conditions and at pH 4.5, at temperatures of 25 ∘C and 40 ∘C (Martínez-Richa, 2012 [3]). The MC primitive model consists of spherocylinder particles whose aspect ratio was determined for 13 samples of HEC of different molecular weights. We consider the Onsager, Simha and Kuhn-Kuhn models, in order to relate the intrinsic viscosity with the aspect ratio of the particles. • Intrinsic viscosity of cellulose derivative HEC is described with hard-spherocylinders/square-well potential. • Monte Carlo simulation results are compared with theoretical predictions. • The method gives insight on the relevant features of computer-simulation models for HEC properties. [ABSTRACT FROM AUTHOR]

Thermodynamic modeling and molecular dynamic investigation of acid gases absorption in ionic liquids. [Display omitted] • Solubility of acid gases in different ionic liquids were thermodynamically modeled. • MPR2-LCVM-Wilson model indicated highest correlation with the experimental data. • Released absorption energies of acid gases in ILs were in tune with their solubility. • Sensitivity analysis results uncovered higher importance of pressure on solubility in ILs. • MD results showed that solute-solvent binding energy increases with increasing pressure. Ionic Liquids (ILs) have emerged as a promising generation of solvents for the absorption of acid gases (e.g., CO 2 and H 2 S) due to their unparalleled physiochemical properties. This study focuses on thermodynamic modeling and molecular dynamic simulation approaches to estimate the solubility and interaction energies of CO 2 and H 2 S gases in/with different frequently-used ILs. For thermodynamic modeling, the GE/EOS method was employed. This method allows for combining activity-coefficient models in the structure of the cubic equation of states. In the GE/EOS method, the modified Peng-Robinson equation of state (MPR2) together with the LCVM mixing rules was used. Excess Gibbs free energy models of Wilson, NRTL, and UNIQUAC were also applied for combination with the GE/EOS models. The prediction results of the combined models were compared with the experimental solubility data. The results demonstrated the capability of these models to predict the thermodynamic behavior of the acid gas-ILs systems. The results uncovered that the MPR2-LCVM-Wilson model can tabulate the highest correlation with the experimental data compared to the other model combinations. Results of the sensitivity analysis on the principal operational variables (temperature and pressure), showed superior effect of pressure on the gas solubility. In addition, the results of the molecular dynamic (MD) simulation disclosed an agreement between the trends of the solubility of acid gases in ILs with those of the released interaction energies of acid gases absorbed by the ILs. MD results also confirmed that the solubility of acid gases in ILs increases with an increase in the binding energy of the molecules with the ILs. [ABSTRACT FROM AUTHOR]

Abstract The difference in the electricity to cooling/heating ratio between a building and combined cooling, heating, and power (CCHP) system has a significant influence on the system configuration and performance. This paper designs a CCHP system coupled with a ground source heat pump (GSHP) to coordinate the match between system supplies and building demands. The energy flows in the cooling and heating work conditions are analyzed, and the thermodynamic models of components constructed. By means of a case study, the performances of the coupling CCHP system, under design and off-design working conditions, are evaluated and analyzed using energetic indicators, including the primary energy ratio and exergy efficiency, respectively. The adjustable areas expressed by electricity and cooling/heating, as well as the adjustable performance distributions, are obtained and discussed in order to guide operation regulation of the CCHP system integrated with the GSHP. Comparisons between the CCHP system with and without GSHP indicate that the coupling CCHP system in the specific case study can save averagely 40.6% and 39.5% of the primary energy in cooling and heating work conditions, respectively. Highlights • Consider the different forms of waste heat to integrate the coupling energy flows of CCHP-GSHP system. • Analyze adjustable areas of the coupling system without thermal energy storage to match the ratios of electricity to heat. • Obtain the distributions of the energy and exergy efficiencies with the adjustable areas. • Discuss the energy-saving and emission-reduction potentials of the coupling system. [ABSTRACT FROM AUTHOR]

This paper reports the experimental and theoretical FT-IR, FT-Raman, 1 H NMR, 13 C NMR and UV–Vis spectral studies on 2-(4,6-dimethyl-1-benzofuran-3-yl) acetic acid (2DBAA). The DFT and HF calculations have been performed for the 2DBAA by using B3LYP/6-311++G (d, p) and 6-311++G (d, p) basis sets, respectively. The experimental geometrical parameters were compared with theoretical data. The fundamental modes of vibrations were assigned by PED, the computed and experimental values support each other. The 1 H NMR and 13 C NMR chemical shifts were estimated by GIAO method and compared with the experimental chemical shifts. The UV–Vis data of the molecule were used to study the visible absorption maxima ( λ max ) by using Time-Dependent DFT. The HOMO-LUMO energy distribution was computed which proves the charge transfer inside the molecule. The natural bonds orbital (NBO) and NLO properties were also computed. Further, the Mulliken charges, thermodynamic properties at different temperatures were presented. The molecular docking studies reveal that 2DBAA play a crucial role in binding with different proteins to exhibit antimicrobial activity. [ABSTRACT FROM AUTHOR]

We demonstrate that a strong surface segregation of one of the components of the binary polycrystalline material can lead to barrier-less pore formation at the triple and quadruple junctions of the grain boundaries. These pores deplete the bulk of the polycrystal from the segregating component, which can lead to a local minimum in the dependence of the Gibbs free energy of the system on the pore size. We show that in some cases a porous polycrystal can be thermodynamically stabilized. [ABSTRACT FROM AUTHOR]

Abstract Global genome nucleotide excision repair (GG-NER) is the main pathway for the removal of bulky lesions from DNA and is characterized by an extraordinarily wide substrate specificity. Remarkably, the efficiency of lesion removal varies dramatically and certain lesions escape repair altogether and are therefore associated with high levels of mutagenicity. Central to the multistep mechanism of damage recognition in NER is the sensing of lesion-induced thermodynamic and structural alterations of DNA by the XPC-RAD23B protein and the verification of the damage by the transcription/repair factor TFIIH. Additional factors contribute to the process: UV-DDB, for the recognition of certain UV-induced lesions in particular in the context of chromatin, while the XPA protein is believed to have a role in damage verification and NER complex assembly. Here we consider the molecular mechanisms that determine repair efficiency in GG-NER based on recent structural, computational, biochemical, cellular and single molecule studies of XPC-RAD23B and its yeast ortholog Rad4. We discuss how the actions of XPC-RAD23B are integrated with those of other NER proteins and, based on recent high-resolution structures of TFIIH, present a structural model of how XPC-RAD23B and TFIIH cooperate in damage recognition and verification. [ABSTRACT FROM AUTHOR]

The study of the solid-liquid phase equilibrium for (NaCl + NaClO 3  + H 2 O) system is of significance to understand the thermodynamic property of the aqueous solution of ionic membrane electrolysis process to promote the production of sodium hydroxide (caustic soda). The solubilities and the physicochemical properties including density, refractive index and pH for this ternary system at 293.15 and 333.15 K and 0.1 MPa were measured using the isothermal dissolution method. Based on Pitzer ion-interaction model and its extended HW model, the solubility equilibrium constants K sp of NaClO 3 and the mixing ion-interaction parameters ( θ Cl,ClO3 , Ψ Na, Cl,ClO3 ) at 293.15 and 333.15 K were parameterized in this work. The Debye-Hückel limiting slope A ø , the Pitzer single-salt parameters of NaCl and NaClO 3 and the solubility equilibrium constants K sp of NaCl at 293.15 and 333.15 K were taken from the relative temperature-dependence formula in the literature. A comparison shows that the calculated solubilities of the ternary system at 293.15 and 333.15 K agree well with the experimental data. The calculated results of densities and refractive indices using the empirical equations agree well with the experimental data at 293.15 and 333.15 K. [ABSTRACT FROM AUTHOR]

In this study, thermodynamic modeling is performed to predict the P-T equilibrium conditions of methane gas hydrate formation in presence of ionic liquids. The imidazolium-based ionic liquids including [EMIM][HSO 4 ], [EMIM][EtSO 4 ], [BMIM][BF 4 ], [OH-EMIM][BF 4 ], [BMIM][Cl] and [BMIM][Br] are modeled through two-step hydrate formation theory of Chen and Guo coupled with CPA EoS for calculating the fugacities of species in liquid and gas phase. The CPA pure component parameters for ionic liquids and also the majority of binary interaction parameters are adjusted using the liquid density and binary VLE data, respectively. The thermodynamic modeling is carried out in the presence of 0.1 weight fractions of all the studied imidazolium based ionic liquids. Moreover, the effect of three various concentrations of [BMIM][BF 4 ] on the P-T equilibrium diagram of methane hydrate are predicted at 0.1, 0.15 and 0.20 weight fractions of this ionic liquid. The results indicate that the CPA EoS can satisfactorily model the phase behavior of aqueous solutions of imidazolium based ionic liquids considering 2B scheme for the association term. In addition, the results indicate good predictions of the proposed model for methane hydrate equilibrium conditions in the presence of imidazolium-based studied ionic liquids including concentration changes such that the absolute average deviations of methane hydrate formation pressures is obtained below 4.2%. [ABSTRACT FROM AUTHOR]

A study of the reaction mechanism and thermodynamic modeling of pentavalent vanadium V(V) extraction from NaVO 3 -H 2 SO 4 -H 2 O solutions using Di-(2-ethylhexyl) phosphoric acid (D2EHPA or HA) extractant was carried out. The effects of initial pH of the solution, extractant concentration, and temperature on the extraction of V(V) were examined. The stoichiometry of the extraction reaction was determined using the slope analysis method. The extracted species was shown to be VO 2 A. A thermodynamic modeling approach was proposed for the prediction of equilibrium concentrations and pH of the system based on the known initial concentrations and process temperature. In the presented approach, the non-ideality of both aqueous and organic phases was taken into account. The activity coefficients of all organic components were calculated using UNIQUAC-NRF model, while the Electrolyte-UNIQUAC-NRF model was employed to calculate the activity coefficients of ions in aqueous phase. The equilibrium constant of the extraction reaction and the unknown parameters of the models were adjusted through the regression of experimental data at 25 °C, 35 °C, and 45 °C. Adjusted parameters were used for the prediction of equilibrium vanadium concentration in organic phase and equilibrium pH of the aqueous phase. Both of regressed and predicted values were in very good agreement with the experimental data. Moreover, calculated standard molar enthalpy of the reaction indicated the endothermicity of extraction reaction between VO 2 + and D2EHPA. [ABSTRACT FROM AUTHOR]

This work evaluated the solubility of caffeic acid (CA) in mixtures of supercritical carbon dioxide (scCO 2 ) and ethanol at different temperatures (313, 323 and 333 K), pressures (20, 30 and 40 MPa) and concentrations of ethanol (2.2, 5.4 and 10.2 mol%). The Soave-Redlich-Kwong and Cubic Plus Association (CPA) equations of state were used to correlate the binary mixture data and to predict the ternary system data. CA solubility in ethanol is approximately 10 6 times higher than its solubility in pure scCO 2 . By using 10.2 mol% ethanol in scCO 2 , CA solubility increased 30,000 times at 313 K and 20 MPa. Both models provided reasonable descriptions of the experimental data for the binary systems. However, CPA-EoS can better describe the strong interactions between acid molecules and ethanol, and can predict that the addition of small amounts of ethanol to scCO 2 provides a large increase in CA solubility. [ABSTRACT FROM AUTHOR]

The purpose of this study is to select an appropriate thermodynamic model among the ones available in commercial process simulators for representing the phase behavior of the carbon dioxide + ethanol + water system. The following versions of the Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) cubic equations of state (EoS) were considered: Panagiotopoulos-Reid, modified Panagiotopoulos-Reid, Huron-Vidal-NRTL, Modified Huron-Vidal (MHV2-UNIFAC), Predictive Soave-Redlich-Kwong (PSRK) and Volume-Translated Peng–Robinson (VTPR). The Polar Perturbed-Chain SAFT EoS deriving from the Statistical Associating Fluid Theory (PPC-SAFT) was also selected for the present investigation. This study highlighted that the optimal thermodynamic models for the application of interest have to be chosen among the VTPR, PSRK and MHV2-UNIFAC EoS. Once identified a suitable thermodynamic model for the CO 2  + ethanol + water ternary system, it has been possible then to simulate the extraction process of polar compounds from natural products and to discuss how water influences the process efficiency. [ABSTRACT FROM AUTHOR]

Liquid organic hydrogen carriers (LOHCs) are promising candidates for storage and transport of renewable energy due to their reversible reaction characteristics. For the proper assessment of candidate molecules, various thermochemical properties are required, and significant experimental efforts are necessary. In this work, we suggest a systematic method for the estimation of thermochemical properties for LOHC candidate molecules combining Density Functional Theory (DFT) calculations, Conductor-like Screening Model (COSMO) and Molecular Dynamics (MD) simulations. We applied the suggested method for the assessment of previously reported LOHC materials. Based on the analysis, new candidates of carbazole-derivative compounds ( N -acetylcarbazole, N -phenylcarbazole, N -benzoylcarbazole, and 4-methyl-4H-benzocarbazole) are suggested, and their properties are estimated and reviewed. Calculation results show that these candidates can provide high theoretical hydrogen uptake capacities above 6 wt% and optimal heats of dehydrogenation in the liquid phase. Analysis on the stereoisomerism showed that the structure-selectivity toward less stable stereoisomers of the hydrogen-rich form is preferable for the dehydrogenation process. [ABSTRACT FROM AUTHOR]

Amino acids partitioning including phenylalanine, glutamic acid, and tryptophan in aqueous and ionic liquid phases at temperature of 298.15 K and atmospheric pressure were measured. 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide used in this work can produce two phases with water immediately. The effect of aqueous solution pH on amino acids partitioning was studied and revealed that amino acid partitioning coefficient was decreased with increasing pH. This phenomenon pertains to the electrostatic interaction between cations of amino acid and the anions of ionic liquid which is decreased when pH increases. Considering the effect of pH, liquid-liquid equilibrium data of amino acids were obtained in a pH owning maximum partitioning coefficient. It was observed that chemical structure of amino acid has an important effect on partitioning of amino acids between two phases. Experimental data indicated that glutamic acid is mostly transferred to aqueous phase while tryptophan moves to the ionic liquid phase. In the modeling section, equilibrium behavior of water, amino acid and ionic liquid system were predicted by SAFT equation of state. Necessary parameters of water and pure ionic liquid for equation of state were measured and amino acid parameters were obtained from literature. Binary interactions of components were optimized by equilibrium data. NRTL model was used in order to analyze cabapility of SAFT EoS to predict the behavior of system. The results indicate that SAFT model anticipates liquid-liquid equilibrium of the system better than NRTL model. The percentage of average absolute deviation for SAFT equiation is <1.2% while for NRTL model is >1.9%. [ABSTRACT FROM AUTHOR]