Mole Fraction Of Water Research Articles

Shutter-Speed DCE-MRI Analyses of Human Glioblastoma Multiforme (GBM) Data.

The shutter-speed model dynamic contrast-enhanced (SSM-DCE) MRI pharmacokinetic analysis adds a metabolic dimension to DCE-MRI. This is of particular interest in cancers, since abnormal metabolic activity might happen. To develop a DCE-MRI SSM analysis framework for glioblastoma multiforme (GBM) cases considering the heterogeneous tissue found in GBM. Prospective. Ten GBM patients. 3T MRI with DCE-MRI. The corrected Akaike information criterion (AICc ) was used to automatically separate DCE-MRI data into proper SSM versions based on the contrast agent (CA) extravasation in each pixel. The supra-intensive parameters, including the vascular water efflux rate constant (kbo ), the cellular efflux rate constant (kio ), and the CA vascular efflux rate constant (kpe ), together with intravascular and extravascular-extracellular water mole fractions (pb and po , respectively) were determined. Further error analyses were also performed to eliminate unreliable estimations on kio and kbo . Student's t-test. For tumor pixels of all subjects, 88% show lower AICc with SSM than with the Tofts model. Compared to normal-appearing white matter (NAWM), tumor tissue showed significantly larger pb (0.045 vs. 0.011, P < 0.001) and higher kpe (3.0 × 10-2 s-1 vs. 6.1 × 10-4 s-1 , P < 0.001). In the contrast, significant kbo reduction was observed from NAWM to GBM tumor tissue (2.8 s-1 vs. 1.0 s-1 , P < 0.001). In addition, kbo is four orders and two orders of magnitude greater than kpe in the NAWM and GBM tumor, respectively. These results indicate that CA and water molecule have different transmembrane pathways. The mean tumor kio of all subjects was 0.57 s-1 . We demonstrate the feasibility of applying SSM models in GBM cases. Within the proposed SSM analysis framework, kio and kbo could be estimated, which might be useful biomarkers for GBM diagnosis and survival prediction in future. 4 TECHNICAL EFFICACY: Stage 1 J. Magn. Reson. Imaging 2020;52:850-863.

Oiling out and Solubility of Trehalose Dihydrate in Water + Isopropanol/1-Propanol/tert-Butanol Solvents from 283.15 to 328.15 K

The solubility of trehalose dihydrate in water + isopropanol/1-propanol/tert-butanol with the mole fraction of water ranging from 0.2 to 0.8 at temperatures from 283.15 to 328.15 K was measured by ...

Phenformin in aqueous co-solvent mixtures of N,N-dimethylformamide, ethanol, N-methylpyrrolidone and dimethyl sulfoxide: Solubility, solvent effect and preferential solvation

The equilibrium mole fraction solubility of phenformin in four co-solvent mixtures of N,N-dimethylformamide (DMF) + water (2), ethanol (1) + water (2) and N-methylpyrrolidone (NMP, 1) + water (2) at temperatures from 278.15 K to 323.15 K and dimethyl sulfoxide (DMSO) (1) + water (2) at temperatures from 293.15 K to 323.15 K were determined via the saturation shake-flask technique. The maximum solubility values were observed in the neat co-solvents of DMF (DMSO, NMP and ethanol). Through the Jouyban-Acree model, the phenformin solubility in the four solvent mixtures was well correlated attaining RAD values less than 3.21% and RMSD values less than 4.84 × 10−4. To describe how solvent affect the solubility, the obtained solubility data were introduced into the linear solvation energy relationships model by taking the cavity term and KAT parameters as solvent’s descriptors. It was shown that the cavity term and hydrogen bond acidity of solvent play the key role on the solubility variation in aqueous DMF, DMSO, ethanol and NMP mixtures. What's more, the quantitative values for local mole fractions of DMSO (DMF, ethanol or NMP) and water around the drug phenformin were calculated by the Inverse Kirkwood–Buff integrals method based on solubility data. Phenformin was preferentially solvated by water in the DMSO/DMSO (1) + water (2) mixtures with compositions 0 < x1 < 0.20 and NMP (1) + water (2) mixture with compositions 0 < x1 < 0.16; while for the ethanol (1) + water (2) mixture with compositions 0.25 < x1 < 1, phenformin is preferentially solvated ethanol.

3-Methyl-6-nitroindazole in some aqueous co-solvent mixtures: Solubility determination, preferential solvation and solvent effect analysis

The equilibrium solubility of 3-methyl-6-nitroindazole in co-solvent mixtures of acetonitrile (1) + water (2), ethanol (1) + water (2) and n-propanol (1) + water (2) is reported. Experiments were performed by using the saturation shake-flask technique at temperature range from 278.15 to 328.15 K. The maximum solubility value was observed in neat acetonitrile (ethanol or n-propanol) for each co-solvent mixtures. By using the Jouyban-Acree model, the 3-methyl-6-nitroindazole solubility was well correlated obtaining RAD values smaller than 4.50% and RMSD values smaller than 3.36 × 10−4. Quantitative values for the local mole fraction of acetonitrile (ethanol, n-propanol, DMF or acetone) and water around the 3-methyl-6-nitroindazole were computed by using the Inverse Kirkwood–Buff integrals method applied to the solubility data. 3-Methyl-6-nitroindazole was preferentially solvated by water in water-rich compositions; while within co-solvent-rich and intermediate compositions, 3-methyl-6-nitroindazole is preferentially solvated by acetonitrile (ethanol, n-propanol, DMF or acetone) in the acetonitrile (ethanol, n-propanol, DMF or acetone) + water mixtures. The experimental solubility data were correlated by Kamlet and Taft linear solvation energy relationships to examine the main factors describing solvent effect. The results showed that the change in cavity formation energy over the composition played the main role on the solubility variation of 3-methyl-6-nitroindazole in all aqueous mixtures.

Thermodynamic behavior of [OMIM]-based ionic liquid and H2O systems: Experimental, model prediction and mechanism insights

The vapor pressures of the binary systems (water + [OMIM][BF4], water + [OMIM][Tf2N], and water + [OMIM][PF6]) were measured by a modified equilibrium still at temperatures ranging from 323.15 to 358.15 K and water mole fraction ranging from 0.1 to 0.9 for water + [OMIM][BF4], from 0.1 to 0.4 for water and [OMIM][Tf2N] and from 0.05 to 0.45 for water + [OMIM][PF6] binary systems, respectively. The experimental results indicate that with the addition of ionic liquids (ILs) the vapor pressure of binary systems decreases. In addition, the popular and widely used UNIFAC-Lei model was extended to the corresponding systems to predict the vapor pressures with the average relative deviations (ARDs) of 4.99%, 4.71% and 5.15% for water + [OMIM][BF4]/[OMIM][Tf2N]/[OMIM][PF6] systems, respectively. Moreover, the binding energy, excess enthalpies and σ-profiles were investigated to analyze the thermodynamic behavior at the molecular level. It was found that the interaction between [OMIM][BF4] and water is significantly higher than those between [OMIM][Tf2N]/[OMIM][PF6] and water as shown by the σ-profiles and the binding energy, and the hydrogen bonding interaction is the dominant driving force contributing to the overall excess enthalpy.

Maraviroc in aqueous co-solvent solutions of n-propanol, ethanol, dimethyl sulfoxide and N,N-dimethylformamide: Solubility determination, preferential solvation and solvent effect analysis

The liquid–solid equilibrium and solubility of maraviroc in co-solvent mixtures of n-propanol, ethanol, dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) plus water was obtained via the saturation shake-flask technique between 278.15 K and 323.15 K under 101.2 kPa. For the four aqueous co-solvent mixtures investigated, the mole fraction solubility of maraviroc increased with the increase in the temperature and mass fraction of n-propanol, ethanol, DMSO and DMF. The maximum solubility values of maraviroc were observed in the neat co-solvents. The dependence of the maraviroc solubility on the solvent composition and temperature was mathematically correlated by means of the Jouyban-Acree model. The obtained values of relative average deviation (RAD) and root-mean-square deviation (RMSD) were no more than 4.16 × 10−2 and 49.13 × 10−6, respectively. KAT-LSER model was implemented to get quantitative information about solvent effect on the variation of solubility data. The variation in the maraviroc solubility was dependent upon the hydrogen-bond donation and cavity term in n-propanol + water and ethanol + water mixtures; and the cavity term was the dominant term in the (DMSO + water) and (DMF + water) mixtures. Quantitative study was made for the local mole fraction of ethanol (n-propanol, DMSO and DMF) and water around the maraviroc by the Inverse Kirkwood–Buff integrals method applied to the solubility data determined. Maraviroc was preferentially solvated by ethanol or n-propanol for the aqueous co-solvent mixtures of ethanol or n-propanol in intermediate and ethanol/n-propanol-rich compositions. It was conjecturable that maraviroc could act mainly as a Lewis acid in front to the ethanol or n-propanol molecules. However in the {n-propanol (1) + water (2)} mixture with compositions 0 < x1 < 0.20, ethanol (1) + water (2) mixture with compositions 0 < x1 < 0.25 and DMF/DMSO mixtures within entire compositions, maraviroc was preferentially solvated neither by co-solvent (1) nor by water.

Controlling palladium morphology in electrodeposition from nanoparticles to dendrites via the use of mixed solvents.

By changing the mole fraction of water (χwater) in the solvent acetonitrile (MeCN), we report a simple procedure to control nanostructure morphology during electrodeposition. We focus on the electrodeposition of palladium (Pd) on electron beam transparent boron-doped diamond (BDD) electrodes. Three solutions are employed, MeCN rich (90% v/v MeCN, χwater = 0.246), equal volumes (50% v/v MeCN, χwater = 0.743) and water rich (10% v/v MeCN, χwater = 0.963), with electrodeposition carried out under a constant, and high overpotential (-1.0 V), for fixed time periods (50, 150 and 300 s). Scanning transmission electron microscopy (STEM) reveals that in MeCN rich solution, Pd atoms, amorphous atom clusters and (majority) nanoparticles (NPs) result. As water content is increased, NPs are again evident but also elongated and defected nanostructures which grow in prominence with time. In the water rich environment, NPs and branched, concave and star-like Pd nanostructures are now seen, which with time translate to aggregated porous structures and ultimately dendrites. We attribute these observations to the role MeCN adsorption on Pd surfaces plays in retarding metal nucleation and growth.

Parts-per-trillion sensitivity for trace-moisture detection using wavelength-meter-controlled cavity ring-down spectroscopy

We introduced frequency-control and temperature-control systems in wavelength-meter-controlled cavity ring-down spectroscopy. The frequency-control system shifted the wavelength of the probe laser from 1393 nm to 696.5 nm where no strong absorption lines of water exist, and therefore, it could avoid measurement errors in laser frequency due to residual moisture in the built-in Fizeau interferometer of a wavelength meter. We verified the hypothesis that the nonuniform reflectivity of the mirror surface contributes to fluctuations in the ring-down time observed with multi-transverse-mode CRDS signals. The fluctuations due to this effect were greatly suppressed by the temperature-control system. Using this system, we could improve the minimum detectable absorption coefficient by three times on average and also improve the experimental standard deviations of the averages by nine times compared with those without the system. We measured near-infrared spectra of residual moisture in dry nitrogen at an approximately 1 nmol/mol (1 ppb) level and performed least-squares fitting of the averaged spectrum. The standard deviation of the residuals of the fitting was 6.6 × 10−12 cm−1, corresponding to a mole fraction of water of 6.3 pmol/mol (6.3 ppt).

Thermodynamic Properties of Water−Ethanol Films Formed between Hydrophobic Surfaces. Part I.

Based on thermodynamic reasoning we claim that long-ranged, solvophobic surface forces may arise in thin films of associated liquids due to formation of linear aggregates composed of spheroidal, nano-sized molecular clusters. Supposedly, these aggregates can span a narrow gap between two hydrofobic solid surfaces submerged in the film-forming liquid phase, thus giving rise to attraction. Such aggregates are apparantly generated in thin water and water–ethanol films, especially below room temperature and for high mole fractions of water or ethanol, respectively. The surface force recorded for a pure water with film thickness larger than about 20 nm are found to be proportional to the number of bridging cluster aggregates per unit area that cross the mid-plane of a thin film. Moreover, the long-range-ness (decay length) was seen to depend inversely on the work of formation of the elongated middle part of a bridging cluster aggregate. Furthermore, addition of small amounts of ethanol rapidly reduce the surface force generated for pure water films with thickness of a few hundred nm.

Suitability of a Non-Dispersive Infrared Methane Sensor Package for Flux Quantification Using an Unmanned Aerial Vehicle.

Point-source methane emission flux quantification is required to help constrain the global methane budget. Facility-scale fluxes can be derived using in situ methane mole fraction sampling, near-to-source, which may be acquired from an unmanned aerial vehicle (UAV) platform. We test a new non-dispersive infrared methane sensor by mounting it onto a small UAV, which flew downwind of a controlled methane release. Nine UAV flight surveys were conducted on a downwind vertical sampling plane, perpendicular to mean wind direction. The sensor was first packaged in an enclosure prior to sampling which contained a pump and a recording computer, with a total mass of 1.0 kg. The packaged sensor was then characterised to derive a gain factor of 0.92 ± 0.07, independent of water mole fraction, and an Allan deviation precision (at 1 Hz) of ±1.16 ppm. This poor instrumental precision and possible short-term drifts made it non-trivial to define a background mole fraction during UAV surveys, which may be important where any measured signal is small compared to sources of instrumental uncertainty and drift. This rendered the sensor incapable of deriving a meaningful flux from UAV sampling for emissions of the order of 1 g s−1. Nevertheless, the sensor may indeed be useful when sampling mole fraction enhancements of the order of at least 10 ppm (an order of magnitude above the 1 Hz Allan deviation), either from stationary ground-based sampling (in baseline studies) or from mobile sampling downwind of sources with greater source flux than those observed in this study. While many methods utilising low-cost sensors to determine methane flux are being developed, this study highlights the importance of adequately characterising and testing all new sensors before they are used in scientific research.

Measurement and Correlation of the Solubility of Aminocaproic Acid in Some Pure and Binary Solvents

The solubilities of aminocaproic acid in four monosolvents (isopropanol, methyl acetate, ethyl acetate, and water) and three binary solvents (methanol–water, ethanol–water, and dimethylformamide–water) were measured by the static analytical method from 283.15 to 323.15 K at atmospheric pressure. In monosolvents, the solubility increases with the increase of temperature. Also, the solubility of aminocaproic acid in water is much higher than that in other organic solvents. In binary solvents, the solubility increases with the increase of the temperature and the mole fraction of water. The solubility data was well correlated by the Apelblat equation, λh equation, and NRTL equation, and the mixing properties of enthalpy, Gibbs energy, and entropy have also been discussed.

Phase equilibria modeling of polar systems with Cubic-Plus-Polar (CPP) equation of state

In this study, an equation of state (EoS), Cubic-Plus-Polar (CPP), has been constructed to model phase equilibria of polar and practical systems in a wide range of temperatures and pressures. In the proposed model, Soave-Redlich-Kwong (SRK) EoS takes into account dispersive forces while a set of polar terms was employed to account for dipolar and quadrupolar interactions. By applying these terms, dipole-dipole, dipole-quadrupole, and quadrupole-quadrupole interactions were directly taken into consideration. The CPP EoS with four pure-compound parameters could accurately correlate both vapor pressure and saturated liquid molar volume of studied pure compounds (water, methanol, ethanol, propanol, 2-propanol, 2-butanol, acetone, N-methyl-2-pyrrolidone (NMP), CO2, and H2S). By utilizing two temperature-dependent binary interaction parameters (BIPs), the phase equilibria of binary mixtures including water-CO2, water-H2S, CO2–H2S, methanol-CO2, ethanol-CO2, propanol-CO2, acetone-CO2, water-acetone, ethanol-acetone, water-NMP, 2-propanol-NMP, and 2-butanol-NMP were satisfactorily calculated by the model. Moreover, the proposed model is sufficiently efficient which is capable of representing minimum water mole fraction in the nonaqueous phase of water-CO2 and water-H2S mixtures. Additionally, the CPP EoS accurately predicted the saturated and single phase mixtures densities of water-CO2 mixture. Finally, the solubility values of CO2 and H2S mixtures in water were reasonably predicted by the model.

Laminar flow in microfluidics investigated by spatially-resolved soft X-ray absorption and infrared spectroscopy.

The application of soft X-ray absorption spectroscopy (XAS) to liquid cells based on microfluidics for chemical state analysis of light elements is much more difficult than hard X-ray absorption since soft X-rays cannot deeply penetrate a microfluidic cell. In this study, we have newly developed a microfluidic cell for spatially resolved XAS, where a 100 nm thick Si3N4 membrane is used for the measurement window to transmit soft X-rays for keeping the microfluidic flow at a width and depth of 50 µm. The π* peak of pyridine near the N K-edge XAS shows characteristic energy shifts near the liquid-liquid interface in a laminar flow of pyridine and water. The distributions of the molar fractions of pyridine and water near the liquid-liquid interface have been determined from the energy shifts of the π* peak probed at different geometric positions, where pyridine is mixed in the water part of the laminar flow and vice versa. The spatial distribution of both species has also been studied by infrared microscopy, using the same microfluidic setup. The present work clearly shows that these spectroscopic techniques are easily applicable to chemical and biological reactions prepared by microfluidics.

Study of nanoconfined mixtures of decane and water: Structure and dynamic

In the last years, the phase behaviour of multi-component hydrocarbon systems in shale reservoirs has received significant attention. The main complexities in modelling the phase behaviour is the confinement. It is presented in this work, the results obtained by molecular dynamics simulation in the NPT ensemble of n-decane/water liquid mixture confined in an amorphous hydrophobic nanometric tube. Nanotube walls are made up of a Lennard-Jones binary mixture similar to a Kob-Andersen system. As it happens in a macroscopic flow of biphasic fluid, a transition from drop to a thread is observed in this confined system when increasing water molar fraction. Different values of the water tetrahedral bond distribution, water density profiles, and the mean square-displacement of water were found for a drop to a thread transition. The calculated quantities, substantially differ from those corresponding to the bulk system.

Axisymmetric Linear Hyperspectral Absorption Spectroscopy and Residuum-Based Parameter Selection on a Counter Flow Burner

Chemical species tomography enables non-invasive measurements of temperatures and concentrations in gas phase processes. In this work, we demonstrate the recently introduced linear hyperspectral absorption tomography (LHAT) on an axisymmetric counterflow burner used for speciation studies of Oxyfuel combustion. As LHAT reconstructs spectrally resolved local absorption coefficient spectra, the physical plausibility of these reconstructed spectra degrades with an over-regularization of the tomographic problem. As presented in this work, this behavior can be employed in a novel regularization parameter choice method based on the residuals of local spectroscopic fits to the reconstructed spectra. After determining the regularization parameter, the reconstructions of the temperature and water mole fraction profiles of different flames are compared to numerical simulations, showing a good agreement.

Selective water vapor permeation from steam/non-condensable gas mixtures via organosilica membranes at moderate-to-high temperatures

The removal of water vapor from humid gas streams is important for steam recovery in power plants and reaction enhancement in a membrane reactor that produces water as a by-product, and so on. The prospect of future applications for organosilica membranes in these fields prompted the present investigation of humid gas separation properties via 1,2-bis(triethoxysilyl)ethane (BTESE)-derived membranes. In this work, binary humid gas separation (H2O/H2 and H2O/N2) was performed on BTESE-derived membranes at temperatures ranging from 80 to 200 °C under feeds of water mole fractions ranging from 0.1 to 0.9. Permeance and the permeance ratios of H2O/H2 and H2O/N2 were confirmed to be dependent on temperature and vapor pressure, and found to be correlated using the water adsorption potential, which accounted for both the temperature and the vapor pressure. The highest levels of water permeate flux, permeance, and permeance ratios of H2O/H2 and H2O/N2 were 37 kg/(m2 h), 5.5 × 10−6 mol/(m2 s Pa)), and 84 and infinity (>6700), respectively, at 150 °C where the partial pressure difference of water across the membrane was 107 kPa. The high performance of BTESE-derived organosilica membranes shows promise for their future applications in humid gas separation at moderate-to-high temperatures.

Solubility of chloroxine in aqueous co-solvent mixtures of N,N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone and 1,4-dioxane: Determination, solvent effect and preferential solvation analysis

The equilibrium solubility of amorphous chloroxine in four co-solvent mixtures of dimethyl sulfoxide (DMSO) (1) + water (2), N,N-dimethylformamide (DMF) (1) + water (2), N-methyl-2-pyrrolidone (NMP) (1) + water (2) and 1,4-dioxane (1) + water (2) is reported. Experiments were performed by using the saturation shake-flask technique over the temperature range from (293.15 to 333.15) K. The maximum solubility was observed in neat DMF (DMSO, NMP or 1,4-dioxane) for the four co-solvent mixtures. By using the Jouyban-Acree model, the chloroxine solubility was well correlated obtaining RAD values lower than 3.64% and RMSD values lower than 8.82 × 10−6. Quantitative values for the local mole fraction of DMSO (DMF, NMP or 1,4-dioxane) and water around the chloroxine were computed by using the Inverse Kirkwood–Buff integrals method applied to the determined solubility data. Chloroxine was preferentially solvated by water for the studied mixtures in water-rich compositions; while within intermediate and co-solvent-rich compositions, chloroxine is preferentially solvated by DMSO (DMF, NMP or 1,4-dioxane) in DMSO (DMF, NMP or 1,4-dioxane) + water mixtures. Moreover, in the light of Kamlet and Taft linear solvation energy relationships model, the co-solvency effect was rationalized, and the relative importance of solvent-solute and solvent-solvent interactions was recognized. It was shown that the change in solvent-solvent interaction energy accounted by cavity term governed the solubility variation of chloroxine in all aqueous mixtures.

Kinetic model of ethylene oxidation by p-benzoquinone in solutions of cationic palladium(ii) complexes in a binary acetonitrile—water solvent

A kinetic model was developed for the reaction of ethylene oxidation to acetaldehyde by p-benzoquinone (Q) at 30 ℃ catalyzed by the cationic palladium(II) complexes in a binary acetonitrile—water solvent at a molar fraction of water of 0.67. The three-route mechanism was proposed that adequately describes all experimental dependences of the concentrations of consumed ethylene on time at various partial ethylene pressures and concentrations of palladium, perchloric acid, and Q. The time-dependent (a) palladium distribution between the intermediates and (b) ratio of the rates of steps of acetaldehyde oxidation via different routes were analyzed. The role of the PdII, PdI, and Pd0 complexes in the catalytic formation of olefins was discussed. The quantum chemical estimates of the composition of the coordination sphere for several intermediates and probabilities of some elementary steps in the reaction mechanism were obtained.

Solubility of 1-methyl-4-nitropyrazole in three binary solvent mixtures from 283.15 K to 323.15 K at 0.1 MPa

In order to find a more suitable solvent system, the solubility of 1-methyl-4-nitropyrazole (1-M-4-NP) in three different binary solvents (i.e., water + acetone, water + methanol and water + ethanol) with different mass fraction of water (0.1000, 0.2000, 0.3000, 0.4000, 0.5000, 0.6000 and 0.7000) was firstly determined by a dynamic laser monitoring within a temperature range of 283.15 K to 323.15 K at atmospheric pressure (P = 0.1 MPa). The experimental results indicated that the solubility of 1-M-4-NP in selected binary solvents increases with the increasing temperature, while decreases with the rising water mole fraction ranging. Besides, the results showed that the value of solubility is largest in water + acetone and the value is smallest in water + ethanol when the mole fraction of water and temperature are constant. Therefore, the (solid + liquid) equilibrium values in the studied solvents were correlated based on the modified Apelblat equation, van't Hoff equation, CNIBS/R-K model and Jouyban-Acree model, and the modified Apelblat equation provide a more accurate result of the experimental values than other three models. In addition, the NRTL model was applied to calculate the thermodynamic properties of 1-M-4-NP including mixing enthalpy, mixing entropy and mixing free Gibbs energy in the studied binary solvent mixtures at given temperature, and it's easy to understand that the dissolution is an endothermic process from the results. Furthermore, the experimental solubility values, model parameters and thermodynamic properties of 1-M-4-NP in different mixed solvents will provide necessary support for its preparation, crystallization process and further theoretical studies.

Surface Tension of 50 Deep Eutectic Solvents: Effect of Hydrogen-Bonding Donors, Hydrogen-Bonding Acceptors, Other Solvents, and Temperature

Surface tension is a key physiochemical property for the application of deep eutectic solvents (DESs) in the field of interface and colloid. However, the surface tension of DESs has not been systematically studied. Here, a comprehensive investigation on the surface tension of 50 typical DESs was carried out. The effect of hydrogen-bonding donors (HBDs) and hydrogen-bonding acceptors (HBAs) on the surface tension was investigated. Furthermore, the surface tension of mixed systems of DESs with other solvents, water, water+salt (e.g., KCl), ethanol, acetone, isopropyl alcohol, and ethyl acetate (EtAc), was studied. It was found that both HBDs and HBAs had a significant influence on the surface tension of DESs. The presence of crystal water in the salt component of DESs would decrease the surface tension of DESs. Besides, the surface tension of DESs increased significantly when the water mole fraction was higher than 0.9, which was well consistent with the tendency of IR spectra. However, the surface tension ...