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Polyphenols from Slovenian hops (Humulus lupulus L.) of the Aurora variety were extracted by different methods and using classical solvents and several deep eutectic solvents (DES) based on choline chloride as the hydrogen bond acceptor component. The obtained extract solutions were analyzed by HPLC for the content of extracted α- and ß-acids and extracted xanthohumol. It was found that choline chloride:phenol DES concentrated aqueous solution had an extraction efficiency close to that of diethyl ether, which is considered one of the best classical extraction solvents for polyphenols from hops. The comparison of the extraction efficiency with other choline chloride-based DESs showed that the chemical similarity of the phenol ring in the solvent DES with the polyphenols in hops may be crucial for a highly efficient extraction with choline chloride:phenol DES. On the other hand, the choice of extraction method and the viscosity of the solvents tested seem to play only a minor role in this respect. As far as we know, this is the first study to attempt to relate extraction efficiency in the extraction of hydrophobic solutes to the compressibility of the DES extractants, the latter of which may be correlated with the extent of hydrophobic hydration around the DES components. In addition, using the heating and stirring method for the preparation of choline chloride-based DES concentrated aqueous solutions we found no support for the occurrence of water in two different roles (in the structural and in the dilution role) in these solvents.

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It is well known that polar organic compounds, such as alcohols and polyols, exert an appreciable influence on water structure and thus have important effects on surfactant micellization. These substances are often used to modify the properties of surfactants in aqueous solutions, increasing the practical applications they have in diverse industries. In this work, the critical micelle concentration (CMC) of decyltrimethylammonium bromide (C10TAB) in water and in 1,2-propanediol aqueous solutions was determined from both sound velocity and surface tension measurements as a function of surfactant concentration in the temperature range of (293.15 to 308.15) K. The critical micelle concentration of the surfactant increases as the concentration of 1,2-propanediol becomes higher, while the effect on temperature does not show important changes within the range considered. At the selected temperatures, the standard thermodynamic parameters of micellization suggests that the addition of 1,2-propanediol makes the micellization process less favorable. Thermodynamic analysis suggests that the micelle formation of C10TAB is an entropy-driven process at the temperatures considered in this study.

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The thermodynamic properties of bioactive peptides provide insights into their functional behavior and their biological efficacy. We conducted precise analyses of the density, the ultrasonic velocity and the relative attenuation of serial dilutions of three commercial dairy peptides prepared by enzymatic methods. From these we determined the partial specific volume and the partial specific adiabatic compressibility coefficient for the peptides. At concentrations greater than ~2.5 â€‹mg â€‹mL-1, the apparent values for specific volume and adiabatic compressibility were constant, differing between the three peptides at ±3% for specific volume and ±70% for compressibility. Both specific volume and adiabatic compressibility were highly dependent on concentration, indicating the importance of precise low concentration measurements to obtain correct values for these thermodynamic parameters. From these parameters it was apparent that restructuring of water molecules around the peptides (and their associated counterions) led to compact solutes that were also incompressible. These thermodynamic analyses are critical for understanding how the properties and the beneficial effects of bioactive peptides are influenced by their chemical environment.

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Drug delivery vehicles such as micelles, vesicles and other nanoemulsions are necessary for enhanced bioavailability of drugs in the body. We have measured and correlated physicochemical properties of an anticancer drug 5-fluorouracil in the micelles of anionic surfactant sodium dodecyl sulfate. cationic surfactant hexadecyltrimethylammonium bromide, and non-ionic surfactant triton X-100 with the energetics of interactions. Thermodynamic signatures accompanying the partitioning of drug into surfactant micelles along with standard partial molar volume and standard partial molar compressibilities of transfer from water to the micelles have been interpreted in terms of strength, nature and extent of partitioning. Functional groups on the drug responsible for interaction/partitioning in micelles have been identified. Interaction of 5-fluorouracil in two or three sequential partitioning behavior depending on the nature of the surfactant micelles has enabled detailed mechanistic analysis of the partitioning process. Structure-property-energetics relationship to obtain deeper insights into the nature of interaction between the drug and micelles has been addressed. Such studies provide information on the significance of functional groups on the drug molecule which can be modified for optimum partitioning in drug delivery vehicles to account for effective target oriented release.

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Physical and chemical structure affect properties of dissolved organic matter (DOM). Recent observations revealed that heating and cooling cycles at higher temperature amplitude lead to a change in DOM physical conformation assumingly followed by a slow structural relaxation. In this study, changes at lower temperature amplitudes and their relation to DOM composition were investigated using simultaneous measurements of density and ultrasonic velocity in order to evaluate the adiabatic compressibility, which is sensitive indicator of DOM structural microelasticity. Six fulvic acids (FAs) having various origins were analyzed at concentrations of 0.12, 0.6 and 1.2 g L-1 and at different temperature amplitudes. First, we validated that the used technique is sensitive to distinguish conclusively the structural changes upon heating and cooling of DOM with heating/cooling amplitude of ±â€¯3 °C and higher. This amplitude was then applied to observe the relationship between change in adiabatic compressibility and chemical composition of FA. No correlation was observed with elemental composition and aromatic structures. Positive correlations were observed with content of alkyl moieties, carboxylic and carbonyl carbons and biological activity. Based on literature data, it was concluded that alkyl moieties undergo (re)crystalization during thermal fluctuation and their structural relaxation back is very slow (if occurs). The polar moieties form a flexible hydrogel responding to thermal fluctuation by moderate dissolution and re-aggregation. Negative correlation was observed in relation to the amount of peptide and O-alkyl systems, which can be attributed to very fast structural relaxation of proteinaceous materials, i.e. their larger content leads to lower difference between original and heat-induced compressibility. Last, the increase of the heating/cooling amplitude from ±â€¯3 to ±â€¯15 °C resulted in an increase of the change of the adiabatic compressibility and in the extension of the relaxation time needed for DOM structure to return to the equilibrium. We conclude that this increase is caused by the increase in inner energy, and DOM conformation can reach a cascade of energy minima, which may influence DOM reactivity and biodegradability.

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Stable cobalt ferrite nanofluids of various concentrations have been prepared through co-precipitation method. Structural and morphological studies of nanoparticles are made with the help of X-ray diffraction technique and Transmission Electron Microscope respectively and it is found that the particles exhibit face centered cubic structure with an average size of 14 nm. The magnetic properties of the nanofluids have been analyzed at room temperature which revealed ferromagnetic behavior and also the very low value of coupling constant which ensures the negligible interparticle interaction in the absence of magnetic field. Ultrasonic investigations have been made for the nanofluids at different temperatures and magnetic fields. The temperature effects are explained with the help of open and close-packed water structure. The inter particle interactions of surface modified CoFe2O4 particles and the cluster formation at higher concentrations are realized through the variations in ultrasonic parameters.

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Sound velocity measurements on liquid propane from 90 to 300 K and for pressures to 34 MPa are reported. Also included are saturated liquid sound velocities from 90 to 290 K. The data were combined with PϱT data to compute compressibility and specific heat ratio. Comparisons were made to computed values of sound velocity of Goodwin and to the data of Lacam.