Density Of Liquid Phase Research Articles

Experimental investigations of coupled polymer and membrane phase transitions.

Polymers can separate into polymer dense and polymer dilute liquid phases in solution while multicomponent lipid membranes can separate into distinct phases within the two-dimensional plane of the membrane. Recent theoretical and simulation work predicts the presence of a polymer rich surface phase when these two-phase transitions are coupled by including polymer conjugated lipids in membranes, and that the location of this phase boundary is tuned by both polymer and lipid interactions1. Here, we experimentally observe the predicted domains of polymer rich surface phase when a small subset of polymers are conjugated to membranes. These surface phases appear at concentrations where polymers do not condense in the bulk, and the concentration needed to form surface phase depends on membrane composition. Experiments have been conducted both with a simple polyelectrolyte and with FUS proteins in separate measurements, demonstrating the robustness of this effect. 1. Rouches, M., Veatch, S. & Machta, B. Surface Densities Prewet a Near-Critical Membrane. bioRxiv2021.02.17.431700 (2021).

Calculating densities and viscosities of natural gas with a high content of C2+ to predict two-phase liquid-gas flow pattern

The paper is devoted to the two-phase flow simulation. The gas-condensate mixture flow in a horizontal pipe under high pressure is considered. The influence of the equation of state (EOS) choice for mixture properties modelling on the flow regime calculation results is studied for gas with high content of methane homologues. An analytical overview of the methods to predict the flow pattern is provided. Based on this analysis, two techniques are selected. For these techniques, values of density and viscosity for each phase are required. Density calculation for the gas phase is performed with Van der Waals based EOS. The propriate EOS is selected based on studies of calculation errors for test mixtures. Calculation of liquid phase density is done by means of Patela-Teja and Guo-Du equations, two different models are considered for viscosity estimation. The flow patterns of gas-condensate mixture in a range of temperatures and pressures are calculated and verified via probability map. The results of study allow to recommend the Brusilovsky EOS for calculation of densities for similar gas mixtures and make more rigorous flow regime evaluation. The probability map shows that for the chosen composition and parameters of media the flow pattern is mostly transitional between segregated and annular independent from EOS.

Capillary Electrophoresis Plasma Fractionation for Lipids Analysis.

Extraction of lipids has mainly used density liquid phase separation techniques; however, these methods are limited by their broad extraction and lack specificity. Complex mixtures like blood plasma contain multiple lipid classes, whose distribution in the body are mediated by protein-lipid interactions and integration of lipids in larger lipoprotein complexes. The capillary electrophoresis system separates complex mixtures by electrokinetic forces that preserve protein-lipid complexation and allow for the fractionation of samples. Here we present a methodology for fractionating plasma using the capillary electrophoresis system.

Remediation of the Alluvial Aquifer of the Sardas Landfill (Sabiñánigo, Huesca) by Surfactant Application

Sardas Landfill at Sabiñánigo Huesca is polluted with Dense Non-Aqueous Liquid Phases (DNAPLs) composed of a complex mixture of chlorinated organic compounds (COCs). This DNAPL was produced as liquid waste from lindane production being dumped decades ago in the unlined landfills close to the lindane factory. This DNAPL migrated by gravity through the subsurface and accumulated in the contact between the alluvial and marls layers (about 15 m b.g.l.). Seven injections of an aqueous emulsion of a biodegradable non-ionic surfactant (E-Mulse 3®) were carried out at the most polluted areas of the Sardas alluvial. Injections were carried out between April and November 2021 using different surfactant concentrations (6.7, 20, 25 and 50 g/L), injection volumes (0.2 to 7 m3) and injection flow rates (0.08–0.85 m3/h). Injected fluids were extracted in the same well or surrounding wells, and the time elapsed between surfactant injection and extraction varied between 24 and 72 h. A total of 22 m3 were injected into the alluvial, and more than double this injected volume was extracted. Injection and extraction points were in the contact between the marls and the alluvial layer. Extracted fluid accumulated in tanks, and phases separated. DNAPL recovered here was mobilized rather than solubilized and managed as toxic waste. The aqueous supernatant was treated in a wastewater treatment plant with physicochemical treatment (including adsorption in activated carbon) before being discharged into the environment. The transport of the injected fluids was monitored by conductivity profiles using bromide (260–538 mg·L−1) as a conservative tracer. High radial dispersion of the injected fluid was found. Surfactant losses by adsorption in the alluvial and absorption in DNAPL were noticed, and both surfactant and contamination did not escape from the capture zone. Monitoring since 2018 of the COCS in groundwater and the DNAPL presence in the contact between alluvial and marls layers showed a significant reduction of COCs in the treated zone with the surfactant injections.

In situ TEM observation of liquid flow induced dense phase formation and anisotropic nanocrystal growth

The nucleation and growth of crystals from solutions are fundamental to materials synthesis and its applications. The mass transfer at micro/nano region in solution will greatly influence the crystal growth process, however, to our knowledge, there is rarely research at this scale due to the technique limit. By using in situ liquid cell transmission electron microscopy (TEM), we observed the crystal growth at flow condition with high resolution in real time. Interestingly, we found a flow induced formation of the solute rich dense liquid phase near surface at ultra-low precursor concentration, which then transformed to nanocrystals. The dendritic crystal growth was accelerated by the dense phase droplet merging and the anisotropic crystal growth was controlled by dense phase shape evolution. Our study deepens the understanding of crystal growth mechanisms, which is crucial to determine reaction dynamics and design hierarchical nanomaterials.

Framework for In Situ Measurements of Vapor–Liquid Equilibrium Using a Microwave Cavity Resonator

The ability to accurately predict the behavior of multiphase fluid mixtures underpins a broad range of industrial and scientific activity. Expanding the scope and improving the performance of predictive thermodynamic models relies on the availability of accurate experimental data for the complete phase behavior of the corresponding fluid mixtures. Here, we present a novel approach to in situ measurements of heterogeneous two-phase behavior in binary fluid mixtures using a single apparatus. A modified microwave re-entrant cavity apparatus is employed to simultaneously measure the dielectric properties of the liquid and vapor as well as the quality of each phase, based on the frequency shifts caused by a heterogeneous fluid for three independent resonant modes. We report a so far unique mathematical framework to further characterize the thermophysical properties of each phase along tie lines, determining the compositions of the coexisting vapor and liquid phase as well as the vapor and liquid phase densities within the two-phase region based on the Clausius–Mossotti relation between phase dielectric properties, density, and molar polarizability. The framework was validated by comparison of the measured and predicted properties of a (0.35 propane + 0.65 carbon dioxide) mixture throughout the two-phase region along an isothermal pathway at T = 280 K. These proof-of-concept results demonstrate for the first time that thermophysical properties of a binary mixture with a known overall composition can be determined from experiments with a microwave cavity using a synthetic approach.

Large-Eddy Simulation of a Water Jet Exhausting into Quiescent Air

This study focuses on a water injection system, typical of those used to inject water in the motor jet plume of rocket engines to reduce noise, and particularly on the destabilization of the liquid jet that leads to a spray system. For that purpose, a large-eddy simulation is conducted for an experimental water jet of the literature. It is a sprinkler whose Reynolds number is and nozzle exit diameter is , similar to injectors used for jet noise reduction studies at a reduced scale. A diffuse interface method is used to calculate the dense liquid phase, and the dispersed phase containing droplets is calculated with an Eulerian solver. Transfers between the dense and the dispersed phases are modeled in the coupling procedure, including the atomization and impingement processes. The jet mean radius and initial instability frequency are consistent with the experimental data, while the position of the jet transition varies with the fluctuation levels at the nozzle exit. The droplets are created in the shear layer and accumulate on the jet center when only the atomization process is considered. When also implemented, the impingement phenomenon, however, is shown to absorb the droplets before they reach the center.

Proanthocyanidins-loaded complex coacervates-based drug delivery attenuates oral squamous cell carcinoma cells metastatic potential through down-regulating the Akt signaling pathway.

Oral cancer, constituted up to 90% by squamous cell carcinomas, is a significant health burden globally. Grape seed proanthocyanidins (PA) have been suggested as a potential chemopreventive agent for oral cancer. However, their efficacy can be restricted due to the low bioavailability and bioaccessibility. Inspired by sandcastle worm adhesive, we adapted the concept of complex coacervation to generate a new type of drug delivery platform. Complex coacervates are a dense liquid phase formed by the associative separation of a mixture of oppositely charged polyelectrolytes, can serve as a drug delivery platform to protect labile cargo. In this study, we developed a complex coacervates-based delivery of PA. The release kinetics was measured, and anticancer effects were determined in two human tongue squamous cell carcinoma cell lines. The results showed that complex coacervate successfully formed and able to encapsulate PA. Additionally, PA were steadily released from the system in a pH-dependent manner. The drug delivery system could significantly inhibit the cell proliferation, migration, and invasion of cancer cells. Moreover, it could markedly reduce the expression of certain matrix metalloproteinases (MMP-2, 9, and 13) crucial to metastatic processes. We also found that suppression of protein kinase B (Akt) pathway might be the underlying mechanism for these anticancer activities. Taken together, complex coacervates-based delivery of PA can act as an effective anticancer approach for oral cancer therapy.

Thermal characterization of polyethylene glycol 600 in liquid and solid phase and across the phase transition

The polyethylene glycol (PEG) is characterized by experimental means in both solid and liquid phase. Main thermal properties inherent to the phase transition are also provided. More specifically, we focus on PEG 600, whose average molar mass is 600 g mol−1 and melting temperature transition is around 283–298 K. The phase change does not occur at a given temperature but rather over a range of temperature, highlighting the complexity of the material. Several methodologies have been developed and calibrated in order to obtain, in both phases, the density and the thermal conductivity. A temperature dependence fit is proposed for the density in liquid phase. The relative density variation from the liquid to solid phase is significant as it can reach about 35%, meaning a quite large volume shrinkage. Differential Scanning Calorimetry (DSC) has been used for measuring the heat capacity of solid and liquid phase and the effective heat capacity at the transition states. The latent heat of fusion and solidification converge to a value of around 128 kJ kg−1. Undercooling effects are mitigated by performing DSC with slow temperature variation rates. Lastly, we have also observed several exothermic peaks during the solidification process that are related to structural reorganizations of the material.

Experimental measurement of thermophysical properties of some commercial phase change materials (PCM) for air conditioning applications

This paper presents the measurement of liquid phase density, thermal diffusivity, thermal conductivity, and dynamic viscosity of five commercial PCM (RT2HC, RT5HC, OM05-P, OM08, CrodaTherm9.5) in the temperature range 2 − 30 °C. The density of RT2HC, RT5HC, OM05-P is 23-24% lower than water, that of OM08 is 6% higher than water and that of CrodaTherm9.5 is 14% lower than water. The thermal diffusivity of RT2HC, RT5HC, OM05-P is 22-24% lower than water, that of OM08 is around a half of water and that of CrodaTherm9.5 is 38-40% lower than water. The thermal conductivity of the five PCM is 72-74% lower than water. The dynamic viscosity of RT2HC, RT5HC, OM05-P and OM08 is 2 − 3 times higher than water, and that of CrodaTherm9.5 is from 7.4 to 8.3 times higher than water. The five PCM are expected to provide convective heat transfer performance significantly lower than water .

Molecular mechanism of liquid–liquid phase separation in preparation process of crystalline materials

Molecular mechanism of liquid–liquid phase separation (LLPS) before nucleation in the preparation of crystalline materials is not well understood. In this work, the evolutions of solute–solvent intermolecular interactions and molecular self-assembly before and after LLPS were investigated by using citicoline sodium as model compound. Raman spectroscopy and molecular dynamics simulation (MD) were applied to reveal different interactions. It was found that the solute–solvent intermolecular interactions were firstly enhanced and then weakened before and after LLPS, indicating that LLPS was caused by the enhanced solute–solvent intermolecular interactions. Solute molecules will self-assemble to form clusters in binary mixed solvents, according to the 2D 1H–1H NOESY measurements and small angle X-ray scattering (SAXS). The clusters will further self-assemble to form a dense liquid phase with the process proceeding. Based on these results, the molecular mechanism of LLPS was proposed and discussed.

Modeling Alkyl Aromatic Hydrocarbons with Dissipative Particle Dynamics.

Building on previous work studying alkanes, we develop a dissipative particle dynamics (DPD) model to capture the behavior of the alkyl aromatic hydrocarbon family under ambient conditions of 298 K and 1 atmosphere. Such materials are of significant worldwide industrial importance in applications such as solvents, chemical intermediates, surfactants, lubricating oils, hydraulic fluids, and greases. We model both liquids and waxy solids for molecules up to 36 carbons in size and demonstrate that we can correctly capture both the freezing transition and liquid-phase densities in pure substances and mixtures. We also demonstrate the importance of including specialized bead types into the DPD model (rather than solely relying on generic bead types) to capture specific local geometrical constructs such as the benzene ring found in the benzyl chemical group; this can be thought of as representing subtle real-world many-body effects via customized pairwise non-bonded potentials.

Investigation on the density of Al2O3/R1234yf, TiO2/R1234yf and CuO/R1234yf nano-refrigerants

Nano-enhanced refrigerant is one of the promising heat transfer fluids in refrigeration systems. It has the capability to boost the efficiency of vapour compression refrigeration and air conditioning systems. In heat transfer application, the density of the fluid plays a crucial role in identifying various heat transfer characteristics such as the Reynolds number, Nusselt number, the friction factor and the pressure loss. Compared to thermal conductivity and viscosity, determining the density of nanofluids has received very less attention in research. The liquid and vapour densities of alumina (Al2O3), titanium dioxide (TiO2) and cupric oxide (CuO) nanoparticles suspended in 2,3,3,3-tetrafluoropropene (R1234yf) are investigated in this study. The Pak and Cho model was adopted to examine the densities of nano-refrigerants as the volume concentration of particles in the base refrigerant and temperature varies from 1% to 5% and 273 to 323 K respectively. The models are validated using the experimental studies conducted by various researchers on different nano-refrigerants. The analysis results indicated that the liquid and vapour densities of CuO/R1234yf nano-refrigerant are 10.3% and 62.93% greater than that of Al2O3/R1234yf at 5% particle concentration. From the liquid and vapour density point of view, the CuO/R1234yf nano-refrigerant is superior over Al2O3/R1234yf and TiO2/R1234yf. Results also indicated that at 308 K the liquid phase density of CuO added with R1234yf nano-refrigerant is higher by 12.99% and 8.65% than R134a and R141b respectively. Hence CuO/R1234yf significantly enhances the performance of refrigeration systems.

Empty liquid state and re-entrant phase behavior of the patchy colloids confined in porous media.

Patchy colloids with three and four equivalent patches, confined in an attractive random porous medium, undergo re-entrant gas-liquid phase separation with the liquid phase density approaching zero at low temperatures. The (bonding) colloid-colloid interaction causes the liquid-gas phase separation, which is modulated by the presence of the randomly distributed hard-sphere obstacles, attracting the colloids via Yukawa potential. Due to this interaction, a layer of mutually bonded colloids around the obstacles is formed. The network becomes nonuniform, with colloid particles locally centered on the obstacles. Features described in this article may open possibilities to produce equilibrium gels with predefined nonuniform distribution of particles and indicate how complicated the phase behavior of biological macromolecules in a crowded environment may be.

Vibrational analysis of pipes based on the drift-flux two-phase flow model

Linear and nonlinear free vibrations of supported pipes containing two-phase flow were modeled in different flow regimes by including gravitational force, structural and two-phase damping effects. To model the flow, the drift-flux model was utilized. Discretization of the dynamical equation was performed with the help of the Galerkin scheme. The linear vibrational frequency of the system was determined by solving the eigenvalue problem. Also, a mathematical closed-form expression for the nonlinear vibrational frequency is presented. For the validation purpose, theoretical and experimental data were obtained from literature and compared with the results of this work in various operating conditions. A detailed parametric analysis was also carried out to examine the influence of flow parameters, geometry, and physical properties on the dynamics of the system. It was concluded that by increasing the inner and outer pipe diameters, vibrational frequencies of the system decrease and increase, respectively. It was found that a lower liquid phase density leads to an improvement in the vibrational stability of the system. Besides, it was demonstrated that by increasing the void fraction/mixture velocity in the system, linear and nonlinear vibrational frequencies increase/decrease. Furthermore, a higher initial amplitude caused a larger nonlinear frequency shift. The outcomes of the current analysis can be applied as a frame to evaluate and optimize the performance of structures transporting two-phase flows.

Experimental investigations of coupled polymer and membrane phase transitions

Polymers can separate into polymer dense and polymer dilute liquid phases in solution while multicomponent lipid membranes can separate into distinct phases within the two-dimensional plane of the membrane. Recent theoretical and simulation work predicts the presence of a polymer rich surface phase when these two phase transitions are coupled by including polymer conjugated lipids in membranes, and that the location of this phase boundary is tuned by both polymer and lipid interactions1. This poster will describe our progress towards validating these predictions experimentally, using mixtures of simple polyelectrolytes or FUS proteins coupled to supported membranes or vesicles.

Precipitant-Free Crystallization of Lysozyme and Glucose Isomerase by Drying

Protein crystallization is usually conducted by using precipitants, although the “salting-out” phenomenon is still unclear and complex. Moreover, the addition of precipitants sometimes results in irreversible disordered precipitation of protein molecules. Although precipitant-free lysozyme crystals obtained by centrifugal concentration showed significant changes in three-dimensional structure compared to the structure of salted-out crystals, it was rather difficult to mount crystals from a viscous dense liquid phase after centrifugal concentration, and the quality of the crystals often deteriorated during the mounting process. Here we present novel precipitant-free crystallization methods, which were effective for lysozyme and glucose isomerase. Tetragonal lysozyme crystals were successfully crystallized in a glass capillary simply by drying highly concentrated lysozyme solution in the presence of 0.01 M hydrochloric acid without using any precipitants. Glucose isomerase dissolved in ultra-pure water was also successfully crystallized in hanging drops by drying highly concentrated solution under low-humidity conditions. Oscillation images of the obtained crystals were safely collected without handling; they clearly indicated the crystals had a tetragonal form for lysozyme and an orthorhombic form for glucose isomerase, and their lattice parameters are similar to those of previously reported crystals obtained by salting-out methods.

Optimizing Lennard-Jones parameters by coupling single molecule and ensemble target data

This contribution is a proof-of-concept that a diverse set of training observables leads to a meaningful force field even if a very limited number of thermodynamic state points (i.e. temperatures) is used. This approach generates optimized force-field parameters, enabling the user to extract additional information from MD simulations. The ultimate goal is to extend this approach and enable an increased amount of observables to be reproduced using a single force field for a series of chemically similar molecules (e.g. oligomer hydrocarbons). Specifically, we present a new optimization strategy to expand the limits of existing force fields and investigate how much added error is introduced to already reproducible observables. For this purpose, we optimized the Lennard-Jones parameters of n-octane using an isolated molecule's relative conformational energies and the liquid-phase density (293.15 K) for a molecular ensemble as optimization objectives. To test the impact on other observables, additional substances and temperatures that were not part of the training set were evaluated. This evaluation includes the surface tension, viscosity and density for n-hexane, n-heptane, n-octane and n-nonane at 293.15, 315.15 and 338.15 K. We show that it is possible to expand the limits of a force field, improving its overall accuracy at a small cost to its previously well-reproduced observables. Additionally, we propose approaches for further developments of the optimization strategy to increase the observables accuracies that suffer a loss in exchange for the capability of reproducing additional properties.

Contact angle of water on a model heterogeneous surface. A density functional approach

We use a density functional approach to calculate the contact angle of the water model on a heterogeneous, graphite-like surface. The surface heterogeneity results from the pre-adsorption of a layer of spherical species. The pre-adsorbed molecules can also be a mixture of molecules of different sizes. The presence of pre-adsorbed layer causes geometrical and energetical heterogeneity of the surfaces. Two cases are considered. The pre-adsorbed molecules can either behave like hard-sphere obstacles, or they can also attract the molecules of water. In the first case, an increase of the amount of pre-adsorbed species leads to an increase of the wetting temperature, but this increase does not depend linearly on the amount of obstacles. In the case of obstacles exerting attractive forces on water molecules, the curves describing the dependence between the amount of pre-adsorbed species and the contact angle can exhibit a maximum. In addition, we have also studied how the pre-adsorbed species influence the local densities of gaseous and liquid phases in contact with a modified solid surface.

Development of peptide binder design method for disease-related phase separation proteins

Neurodegenerative diseases such as dementia and Alzheimer's disease are caused by liquid-liquid phase separation (LLPS) proteins. LLPS is a phenomenon in which a dense liquid phase of proteins is formed in a liquid phase in which proteins are dispersed at a low concentration. The concentrated proteins enable highly efficient chemical reactions, but at the same time, there is a risk of forming insoluble aggregates that cause diseases. In fact, neurodegenerative disease-related proteins form insoluble aggregates, which cause great damage to nerves, resulting in memory and motor disorders. Drug discovery requires the design of drug candidates that can strongly bind to the intrinsically disordered region of a phase-separated protein and control the phase-separated state. This paper mainly introduces our research on peptide design that binds to phase-separated proteins. For peptide drug discovery, it is necessary to efficiently search for drug candidates among a huge number of peptides. As an efficient search method for peptides that control phase-separated proteins, we searched for amino acids that can control liquid-liquid phase separation, and devised a method for designing peptides containing effective amino acids. It was demonstrated that this method can be used to control the LLPS and solid aggregate formation of the neurodegenerative disease-related protein FUS. Furthermore, we devised a method for rationally designing a peptide that binds complementarily to the intrinsically disordered region of the target, and demonstrated the functional control of the cancer disease-related protein p53. Finally, we discuss the possibility of peptide drug discovery for disease-related LLPS proteins.