You are currently viewing a new version of our website. To view the old version click .
  • Tracked forImpact Factor
  • 2.9CiteScore
  • 35 daysTime to First Decision

Liquids

Liquids is an international, peer-reviewed, open access journal on all aspects of liquid material research published quarterly online by MDPI.

All Articles (138)

Liquids like water are not expected to produce a thermal change under shear strain or flow (away from extreme conditions). In this study, we reveal experimental conditions for which the conventional athermal hydrodynamic assumption is no longer valid. We highlight the establishment of non-equilibrium hot and cold thermal states occurring when a mesoscopic confined liquid is set in motion. Two stress situations are considered: low-frequency shear stress at large strain amplitude and microfluidic transport (pressure gradient). Two liquids are tested: water and glycerol at room temperature. In confined conditions (submillimeter scale), these liquids exhibit stress-induced thermal waves. We interpret the emergence of non-equilibrium temperatures as a consequence of the solicitation of the mesoscopic liquid elasticity. In analogy with elastic deformation, the mesoscopic volume decreases or increases slightly, which leads to a change in temperature (thermo-mechanical energy conversion). The energy acquired or released is converted to heat or cold, respectively. To account for these non-equilibrium temperatures, the mesoscopic flow is no longer considered as a complete dissipative process but as a way of propagating shear and thus compressive waves. This conclusion is consistent with recent theoretical developments showing that liquids propagate shear elastic waves at small scales.

9 October 2025

Mechanical response of a water layer of 125 µm confined between high-energy surfaces (alumina) subjected to a low-frequency oscillatory shear strain of 1 rad/s versus increasing shear amplitude (from γ = 1% to 7500%). Measurements carried out at room temperature. The central figure superposes raw waves (blue wave for the shear strain γ and red for the torque Γ(γ)), the shear elastic modulus G′ (■) and the viscous modulus G″ (•), calculated by the rheometer software using the assumption of a sinus stress wave response. The two light-blue dotted squares detail the waves illustrated in inserts (a,b). The white dotted arrow indicates the entrance in the non-linear regime assimilated to a viscous-like behavior according to the viscoelasticity theory. The satellite figures are described as follows. (a) At low shear strain amplitude (2–4%), stress and strain waves are in-phase, indicating an instantaneous (elastic) response (indicated in Figure 1 by the left blue dotted square). (b) At large shear strain amplitude (c), the shear stress signal is a distorted wave leading by a π/2 advance of phase with respect to the imposed strain wave. (c) Stress relaxation: the vertical dotted line corresponds to the moment at which the strain stops (detail of the blue circle in (b)). The shear wave is relaxed within 0.2 s after the mechanical stop.

This study investigates the formation of hydroxyl radicals (OH radicals) in cavitation bubble plasma-treated water (CBPTW) using a chemical probe method. CBPTW samples were prepared with different electrode materials (W, Fe, Cu, and Ag), and the chemical scavenger was added two minutes after the completion of cavitation and plasma treatments. The concentrations of metal ions and hydrogen peroxide (H2O2) generated in the CBPTW were also measured over time. This study reveals a novel mechanism whereby metal nanoparticles and ions released from electrodes catalyze the continuous generation of hydroxyl radicals in CBPTW, which has not been fully addressed in previous studies. The results suggest a continuous generation of OH radicals in CBPTW prepared with W, Fe, and Cu electrodes, with the amount of OH radicals produced in the order Cu > Fe > W. The study reveals a correlation between OH radical production and electrode wear, suggesting that the continuous generation of OH radicals in CBPTW results from the catalytic decomposition of H2O2 by metal nanoparticles or ions released from the electrodes. It should be noted that cavitation bubble plasma (CBP) is fundamentally different from sonochemistry. While sonochemistry utilizes ultrasound-induced cavitation to generate radicals, CBP relies on plasma discharge generated inside cavitation bubbles. No ultrasound was applied in this study; therefore, all observed radical formation is attributable exclusively to plasma processes rather than sonochemical effects. However, the precise mechanism of continuous OH radical formation in CBPTW remains unclear and requires further investigation. These findings provide new insights into the role of electrode materials in continuous OH radical generation in cavitation bubble plasma treated water, offering potential applications in water purification and sterilization technologies.

1 October 2025

A new method is presented for the estimation of contributions to solvation free energy from dispersion, polar, and hydrogen-bonding (HB) intermolecular interactions. COSMO-type quantum chemical solvation calculations are used for the development of four new molecular descriptors of solutes for their electrostatic interactions. The new model needs one to three solvent-specific parameters for the prediction of solvation free energies. The widely used Abraham’s LSER model is used for providing the reference solvation free energy data for the determination of the solvent-specific parameters. Extensive calculations in 80 solvent systems have verified the good performance of the model. The very same molecular descriptors are used for the calculation of solvation enthalpies. The advantages of the present model over Abraham’s LSER model are discussed along with the complementary character of the two models. Enthalpy and free-energy solvation information for pure solvents is translated into partial solvation parameters (PSP) analogous to the widely used Hansen solubility parameters and enlarge significantly their range of applications. The potential and the perspectives of the new approach for further molecular thermodynamic developments are discussed.

25 September 2025

Thermodynamic Constraints on the “Hidden” Folding Intermediates

  • Timur A. Mukhametzyanov,
  • Mikhail I. Yagofarov and
  • Christoph Schick

Experimental data on the folding and unfolding of small globular proteins are often well described assuming a two-state equilibrium process. It means that after careful analysis by a combination of experimental techniques, only folded and unfolded states of the protein are found to be populated under various external conditions with no detectable intermediates. One of the consequences of the two-state behavior is that the equilibrium ratio of the folded to unfolded protein states follows a simple thermodynamic relation, and the enthalpy difference between states can be obtained from the temperature dependence of the equilibrium constant. In this paper, we theoretically investigate the criteria for the two-state equilibrium behavior and discuss the thermodynamic constraint on the properties of the “hidden” folding intermediates. The literature data on the folding mechanism of lysozyme in water and glycerol, which follows a two-state equilibrium behavior but includes kinetic intermediates, is analysed in light of this constraint.

13 September 2025

News & Conferences

Issues

Open for Submission

Editor's Choice

Get Alerted

Add your email address to receive forthcoming issues of this journal.

XFacebookLinkedIn
Liquids - ISSN 2673-8015Creative Common CC BY license