Changes In Phase Behavior Research Articles

A ferroelectric nematic liquid crystal vitrified at room temperature

ABSTRACT Most of the current highly polar rod-shaped molecules that form ferroelectric nematic (NF) phase do so only at elevated temperatures and multicomponent mixtures are generally needed to obtain a broad and room temperature range NF phase. In this work, we describe the synthesis, phase characterisation and measurement of various physical properties of a new ferroelectric nematic compound 4-[(4-nitrophenoxy)carbonyl]phenyl 2-isopropoxy-4-methoxybenzoate (RT11165). The molecular structure of RT11165 with a 2-isopropoxy group differs only by a substitution of the 2-methoxy group found in the prototype ferroelectric nematic material 4-[(4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (RM734). This small structure change produces a rather dramatic change in phase behaviour leading to an NF phase from 63°C down to room temperature. Below about 45°C the rotational viscosity of RT11165 increases critically and the temperature dependence indicates a glass transition at ~19°C. The transparent and polar glassy state of RT11165, which should be also piezoelectric, is a good candidate for energy storage, piezoecatalysis, data storage and other applications.

Effects of CO2 variable thermophysical properties and phase behavior on CO2 geological storage: A numerical case study

CO2 injection into the reservoir can effectively reduce greenhouse gas emissions. The thermophysical parameters and phase behavior of CO2 are highly sensitive to pressure and temperature, resulting in drastic change in wellbore and reservoir, and thus affecting the CO2 storage effect. To study the impact of CO2 thermophysical properties and phase behavior on CO2 geological storage, we established a fully coupled 1D+3D wellbore coupled 3D reservoir model. Based on the analysis of non–isothermal flow characteristics, CO2 thermophysical properties and phase behavior, the influence of engineering parameters on the key factors of CO2 geological storage is discussed. The findings indicate that the density and thermal capacity of CO2 are the most important thermophysical parameters that affect wellhead pressure and bottomhole temperature respectively. The efficiency of CO2 storage is greatly influenced by the density and viscosity of CO2, more so than any other thermophysical parameters. CO2 phase behavior and permeability change increase CO2 seepage capacity by 3.50 % and 8.79 % respectively. Engineering parameters will affect the thermophysical properties and permeability of bottom–hole CO2, thereby affecting the injectability and storage efficiency of CO2. This research can offer suggestions and theoretical groundwork for the improved design of CO2 geological storage.

Phase behavior of gas condensate in porous media using real-time computed tomography scanning

The phase behavior of gas condensate in reservoir formations differs from that in pressure–volume–temperature (PVT) cells because it is influenced by porous media in the reservoir formations. Sandstone was used as a sample to investigate the influence of porous media on the phase behavior of the gas condensate. The pore structure was first analyzed using computed tomography (CT) scanning, digital core technology, and a pore network model. The sandstone core sample was then saturated with gas condensate for the pressure depletion experiment. After each pressure-depletion state was stable, real-time CT scanning was performed on the sample. The scanning results of the sample were reconstructed into three-dimensional grayscale images, and the gas condensate and condensate liquid were segmented based on gray value discrepancy to dynamically characterize the phase behavior of the gas condensate in porous media. Pore network models of the condensate liquid ganglia under different pressures were built to calculate the characteristic parameters, including the average radius, coordination number, and tortuosity, and to analyze the changing mechanism caused by the phase behavior change of the gas condensate. Four types of condensate liquid (clustered, branched, membranous, and droplet ganglia) were then classified by shape factor and Euler number to investigate their morphological changes dynamically and elaborately. The results show that the dew point pressure of the gas condensate in porous media is 12.7 MPa, which is 0.7 MPa higher than 12.0 MPa in PVT cells. The average radius, volume, and coordination number of the condensate liquid ganglia increased when the system pressure was between the dew point pressure (12.7 MPa) and the pressure for the maximum liquid dropout, Pmax (10.0 MPa), and decreased when it was below Pmax. The volume proportion of clustered ganglia was the highest, followed by branched, membranous, and droplet ganglia. This study provides crucial experimental evidence for the phase behavior changing process of gas condensate in porous media during the depletion production of gas condensate reservoirs.

Gas–droplet–liquid transitions and fluctuations in soft nano-confinement

One permanent characteristic of the thermodynamics of small systems is environment-dependence, also known as ensemble-dependence. Fluid molecules in soft (deformable) nano-confinement offer a special ensemble that acts as a bridge between classical isobaric (NPT) and isochoric (NVT) ensembles. Here, we discuss the gas–liquid transition taking place in a soft nano-confinement where the cell volume is not fixed but changes when the system pressure is changed. The free energy of the system is calculated as a function of the size of the liquid droplet that appears in the gas phase. We discuss how the phase behavior changes when the condition of the confinement changes from rigid confinement to very soft confinement. For the simple fluid model studied, the coexistence and critical phase behaviors are found to be uniquely determined by αK (αK is the dimensionless elasticity constant of the wall of confined space and is proportional to its ability to resist deformation), and the confinement with moderate softness exhibits richer phase behavior. We then study the fluctuations of pressure, volume, and droplet size for fluid in soft confined spaces, which is again closely related to the wall softness. Under moderate softness, large fluctuations in both fluid pressure and volume are seen in the transition region where fluid pressure increases with volume expansion, accompanied by the strengthened fluctuation of droplet size.

Phase behavior and hydrocarbons distribution in shale oil during EOR with nano-confinement effect

The pore structure of shale reservoirs leads to the complex phase behavior of shale reservoir fluids, which is aggravated due to changes in fluid composition during reservoir development. Effective prediction of changes in the phase behavior of fluids in shale reservoirs is important. This paper proposes a pore-size-dependent Peng-Robinson equation of state (PR-EOS) to describe phase behavior in nanopores. The approach considers the shift of critical parameters and the gas-liquid capillary pressure and compiles by MATLAB. The verification of the model is satisfying by matching the result with Tnavigator PVTi using the published date. The results show that fluids in nanoscale pores are more likely to exhibit near-critical or condensate states. We also compare the changes in phase behavior when fluids dissolve CO2 and CH4 and observe the phase transition (from gaseous to liquid phase) of the lighter crude oil sample that dissolved more gas during the differential liberation experiment (DL). Finally, we use CO2 pre-pad energized fracturing of a shale oil reservoir in northern China as an example to explain abnormal production performances, such as a majority of light hydrocarbons in the produced fluid of the well during the flow back stage, single gas phase production in the early production stage, and stable gas/oil ratio (GOR) in the process of development. Our novel methodology and phase behavior change mechanism can enhance our understanding of the phase behavior of fluids in shale oil reservoirs during enhanced oil recovery.

Dynamic Light Scattering Based Microrheology of End-Functionalised Triblock Copolymer Solutions.

Nano-sized particles functionalised with short single-stranded (ss)DNAs can act as detectors of complementary DNA strands. Here we consider tri-block-copolymer-based, self-assembling DNA-coated nanoparticles. The copolymers are chemically linked to the DNA strands via azide (N3) groups. The micelles aggregate when they are linked with complementary ssDNA. The advantage of such block-copolymer-based systems is that they are easy to make. Here we show that DNA functionalisation results in inter-micellar attraction, but that N3-groups that have not reacted with the DNA detector strands also change the phase behaviour of the tri-block polymer solution. We studied the triblock copolymer, Pluronic® F108, which forms spherical micelles in aqueous solutions upon heating. We find that the triblock chains ending with either an N3 or N3-DNA complex show a dramatic change in phase behaviour. In particular, the N3-functionalisation causes the chain ends to cluster below the critical micelle temperature (CMT) of pure F108, forming flower-micelles with the N3-groups at the core, while the PPO groups are exposed to the solvent. Above the CMT, we see an inversion with the PPO chains forming the micellar core, while the N3-groups are now aggregating on the periphery, inducing an attraction between the micelles. Our results demonstrate that, due to the two competing self-assembling mechanisms, the system can form transient hydrogels.

Vapor–Liquid Equilibria of Quaternary Systems of Interest for the Supercritical Antisolvent Process

In the Supercritical Antisolvent process (SAS), the thermodynamic behavior of complex multicomponent systems can influence the particles’ morphology. However, due to the limited thermodynamic data for multicomponent systems, the effect of solutes is often neglected, and the system is considered as pseudo-binary. It has been demonstrated that the presence of a solute can significantly influence the thermodynamic behavior of the system. In particular, when the SAS process is adopted for the production of drug/polymer coprecipitated microparticles, the effect of both the drug and the polymer in the solvent/CO2 mixture should be considered. In this work, the effect of polyvinylpyrrolidone (PVP), used as the carrier, and of the liposoluble vitamins menadione (MEN) and α-tocopherol (TOC), as model drugs, was investigated as a deviation from the fundamental thermodynamic behavior of the DMSO/CO2 binary system. Vapor–liquid equilibria (VLE) were evaluated at 313 K, with a PVP concentration in the organic solution equal to 20 mg/mL. The effect of the presence of PVP, MEN, and TOC on DMSO/CO2 VLE at 313 K was studied; furthermore, the effect of PVP/MEN and PVP/TOC, at a polymer/drug ratio of 5/1 and 3/1, was determined. Moreover, SAS precipitation experiments were performed at the same polymer/drug ratios using a pressure of 90 bar. Thermodynamic studies revealed significant changes in phase behavior for DMSO/CO2/PVP/TOC and DMSO/CO2/PVP/MEN systems compared to the binary DMSO/CO2 system. From the analysis of the effect of the presence of a single compound on the binary system VLE, it was noted that PVP slightly affected the thermodynamic behavior of the system. In contrast, these effects were more evident for the DMSO/CO2/TOC and DMSO/CO2/MEN systems. SAS precipitation experiments produced PVP/MEN and PVP/TOC microparticles, and the obtained morphology was justified considering the quaternary systems VLE.

The effect of water vapor on the phase behaviors during depletion and CO2 injection in gas condensate reservoir

Gas condensate reservoirs are generally a mixed system of hydrocarbon and water. This paper is aimed to investigate the phase behavior change influenced by water vapor during the development of depletion and CO2 injection. The Gnorth reservoir of Zhanazhol oilfield in Caspian Basin is taken as an example. Two-phase flash was based on QNSS\\Newton method, and multiple contact calculations were performed through cell-to-cell method. The research results indicate that, for the remaining reservoir fluid of depletion development, water vapor has the largest effect on the content change of CH4, followed by C7+, and the smallest effect on C2 to C6. The presence of water vapor makes it easier for the condensate to drop out of the gas phase. For CO2 injection, water vapor is not beneficial to re-evaporation for the formation condensate. Further, the multiple contact miscibility of CO2 and condensate is less affected by water vapor.

Development of a new approach using an artificial neural network for estimating oil formation volume factor at bubble point pressure of Egyptian crude oil

Understanding the phase behavior and volumetric changes of reservoir fluids throughout the extent of reservoir lifetime are crucially required for effective-commercial oil recoveries. Ideally, reservoir fluid properties are experimentally measured by laboratory experiments known as PVT tests nonetheless, these tests are prohibitive, time-consuming, and required to restrict sampling and transporting procedures. For these discernible reasons, several modeling approaches have been developed. By reviewing the literature, one crucial obstacle that encounters field applicability of most extant models is the selection of input variables. Moreover, a great percentage of extant models employ the results of lengthy experimental tests such as differential gas solubility or even the sample’s chemical composition. Replicability of models’ results using different datasets is also one of the main challenges when employing AI models. Frequently, inadequate descriptions for AI models have been provided in many studies which limits their utility. The inadequate description includes the analysis of ANN model weights and biases besides, the final mathematical model. In this study, a rigorous ANN model with its mathematical model has been implemented to predict oil formation volume factors based on 600 compiled datasets from Egyptian oilfields.A detailed comparison between widely used empirical correlations and the proposed new ANN model is provided in this study. Statistical and graphical analysis depicted the outstanding performance of the new model with R2 = 0.974, ARE = −0.0017%, and AARE = 2.13%. The ANN model provides remarkable sustainable performance compared to local Egyptian empirical correlations and all the other global models.

Oil Recovery Dynamics of Natural Gas Huff ‘n’ Puff in Unconventional Oil Reservoirs Considering the Effects of Nanopore Confinement and Its Proportion: A Mechanistic Study

Summary When reservoir fluids are confined by nanoscale pores, pronounced changes in fluid properties and phase behavior will occur. This is particularly significant for the natural gas huff ‘n’ puff (HNP) process as a means of enhanced oil recovery (EOR) technology in unconventional reservoirs. There have been considerable scientific contributions toward exploring the EOR mechanisms, yet almost none considered the effects of nanopore confinement and its proportion on the oil recovery dynamics. To bridge this gap, we developed an approach to calculate fluid phase equilibrium in nanopores by modifying the Rachford-Rice equation and Peng-Robinson equation of state (PR-EOS), completed by considering the shifts of fluid critical properties and oil/gas capillary pressure. Afterward, the effect of nanopore radius (rp) on the phase behavior between the injected natural gas and oil was thoroughly investigated. Compositional simulation was performed using a rigorously calibrated model based on typical properties of a tight reservoir to investigate the production response of natural gas HNP, including the effects of nanopore confinement and its proportion. We demonstrated that the critical pressure and temperature of fluid components decreased with the reduction in rp, especially for heavy constitunts. The saturation pressure, density, and viscosity of the oil in the presence of natural gas all declined linearly with 1/rp in the confined space. The suppression of fluid saturation pressure was indicative of an extended single-phase oil flow period during production. The cumulative oil production was approximately 12% higher if the confinement effect was considered in simulation. Moreover, the average reservoir pressure declined rapidly resulting from this effect, mainly caused by the intensified in-situ gas/oil interaction in nanopores. The results of this paper supplement earlier findings and may advance our understanding of nanopore confinement during natural gas HNP, which are useful for field-scale application of this technique.

THE INFLUENCE OF ISOPROPYL ALCOHOL CONCENTRATION ON THE CHANGE OF PHASE BEHAVIOR IN THE MIXTURE OF OIL - SURFACTANT - ISO PROPYL ALCOHOLFORMATION WATER

Surfactant is surface active agent chemical that has two types of properties; lyophobic (like water) and hydrophobic (like oil). One of enhanced oil recovery methods that is used to improve oil recovery factor, is surfactant flooding. Oil and water are two separated phases and have high interfacial tension value (around 30-40 dyne/cm). Addition of surfactant solution at certain concentration into the mixture of oil-surfactant-formation water will change the phase behavior. In this case, four types possibilities of emulsion formed, these are: • Upper phase; Middle phase (microemulsion); Lower phase; Macroemulsion. According to Prince, L.M (Theory and Practice of Microemulsions), change of phase behavior in the oil-surfactant-formation water mixture is influenced by several factors, one of them is concentration of alcohol. The main focus of this research is to study influence of isopropyl alcohol (IPA) concentration on phase behavior in the oil-surfactant-IPA-formation water mixture.Concentration Behavior Oil - Surfactant - Iso

Manipulation of the crystalline phase diagram of hydrogen through nanoscale confinement effects in porous carbons.

Condensed phases of molecular hydrogen (H2) are highly desired for clean energy applications ranging from hydrogen storage to nuclear fusion and superconductive energy storage. However, in bulk hydrogen, such dense phases typically only form at exceedingly low temperatures or extremely high (typically hundreds of GPa) pressures. Here, confinement of H2 within nanoporous materials is shown to significantly manipulate the hydrogen phase diagram leading to preferential stabilization of unusual crystalline H2 phases. Using pressure and temperature-dependent neutron scattering at pressures between 200-2000 bar (0.02-0.2 GPa) and temperatures between 10-77 K to map out the phase diagram of H2 when confined inside both meso- and microporous carbons, we conclusively demonstrate the preferential stabilisation of face-centred cubic (FCC) solid ortho-H2 in microporous carbons, at temperatures five times higher than would be possible in bulk H2. Through examination of nanoconfined H2 rotational dynamics, preferential adsorption and spin trapping of ortho-H2, as well as the loss of rotational energy and severe restriction of rotational degrees of freedom caused by the unique micropore environments, are shown to result in changes to phase behaviour. This work provides a general strategy for further manipulation of the H2 phase diagram via nanoconfinement effects, and for tuning of anisotropic potential through control of confining material composition and pore size. This approach could potentially provide lower energy routes to the formation and study of more exotic non-equilibrium condensed phases of hydrogen that could be useful for a wide range of energy applications.

Temperature effects on alcohol aggregation phenomena and phase behavior in n-butanol aqueous solution

Liquid-liquid phase separation is an important phenomenon that prevails from simple to complex molecular systems where temperature plays a crucial role in the fundamental understanding of phase behavior in a theoretical and industrial perspective. The n-butanol aqueous solutions have two separate liquid phases of alcohol-rich and water-rich formed at room temperature. The change in phase behavior occurs from two phases to one with an increase of temperature, exhibiting an upper critical solution temperature (UCST) behavior. We carried out molecular dynamics simulations and graph theoretical analysis to understand how temperature regulates n-butanol aggregation and the network properties of water at various concentrations.The theoretical studies suggest that the n-butanol molecules form two distinct alcohol aggregates, water-compatible or water-incompatible, determined by the interactions between alcohol and solvent molecules. Moreover, the proposed bifurcating aggregation pathway is sensitive to the temperature and composition of the n-butanol aqueous solution. The current study shows how temperature is significant in modulating the alcohol aggregation behavior and affects water structure which determines the phase behavior of aqueous solution systems. The effect of temperature on the alcohol aggregation pattern and water structure in n-butanol/water mixtures provides a critical clue in the fundamental understanding and determining the phase behavior of binary water mixtures. The current study also provides a molecular framework to examine and govern the UCST behavior of aqueous solution systems.

Bipolar Imidazolium-Based Lipid Analogues for Artificial Archaeosomes.

Archaeal lipids have harvested biomedical and biotechnological interest because of their ability to form membranes with low permeability and enhanced temperature and pressure stability. Because of problems in isolating archaeal lipids, chemical synthesis appears to be a suitable means of producing model lipids that mimic the biological counterparts. Here, we introduce a new concept: we synthesized bipolar alkylated imidazolium salts of different chain lengths (BIm10-32) and studied their structure and lyotropic phase behavior. Furthermore, mixtures of the bolalipid analogues with phospholipid model biomembranes of diverse complexity were studied. DSC, fluorescence and FTIR spectroscopy, confocal fluorescence microscopy, DLS, SAXS, and TEM were used to reveal changes in lipid phase behavior, fluidity, the lipid's conformational order, and membrane morphology over a wide range of temperatures and for selected pressures. It could be shown that the long-chain BImN32 can form monolayer sheets. Integrated in phospholipid membranes, it reveals a fluidizing effect. Here, the two polar head groups, connected by a long alkyl chain, enable the integration into the bilayer. Interestingly, addition of BImN32 to fluid DPPC liposomes increased the lipid packing markedly, rendering the membrane system more stable at higher temperatures. The membrane system is also stable against compression as indicated by the high-pressure stability of the system, mimicking an archaeal lipid-like behavior. BImN32 incorporation into raft-like anionic model biomembranes led to marked changes in lateral membrane organization, topology, and fusogenicity of the membrane. Overall, it was found that long-chain imidazolium-based bolalipid analogues can help adjust membrane's biophysical properties, while the imidazolium headgroup provides the ability for crucial electrostatic interaction for vesicle fusion or selective interaction with membrane-related signaling molecules and polypeptides in a synthetically tractable manner. The results obtained may help to develop new approaches for rational design of extremophilic bolalipid-based liposomes for various applications, including delivery of drugs and vaccines.

Tuning the Bulk and Surface Properties of PDMS Networks through Cross-Linker and Surfactant Concentration.

The elastic modulus and hydrophilicity of cross-linked poly(dimethylsiloxane) (PDMS) are tunable via cross-linker concentration and the addition of a simple surfactant, C12E4, before curing. However, the surfactant concentration, [C12E4], reduces the elastic modulus (73% lower for 6.3% w/w) because it reduces the extent of curing. This is likely because the hygroscopic surfactant results in water poisoning of the catalyst. Three distinct time-dependent hydrophilicity profiles were identified using water contact angle analysis with [C12E4] determining which profile was observed. This indicates the concentration-dependent phase behavior of C12E4 within PDMS films. Changes in phase behavior were identified using small-angle neutron scattering (SANS) and a compatibility study. No surface excess or surface segregation of surfactant was observed at the PDMS–air interface. However, a surface excess revealed by neutron reflectivity against a D2O interface indicates that the increase in hydrophilicity results from the migration of C12E4 to the film interface when exposed to water.

Incorporating phase behavior constraints in the multi-objective optimization of a warm vaporized solvent injection process

The warm vaporized solvent injection process has been proposed as a more environmentally friendly alternative to steam-based technologies for bitumen recovery. The process typically involves injecting heated solvent vapor into a horizontal injector; the solvent condenses and dissolves into bitumen, while the diluted oleic phase would flow towards a horizontal producer. Despite the promising results reported from several pilot projects near Fort McKay, Alberta, successful commercial-scale extraction is costly and would require a detailed optimization of the pertinent design variables. The main challenge is that this is a multi-objective optimization (MOO) problem, which aims to balance the trade-offs between conflicting performance objectives while honoring the various operational constraints. In this study, a systematic workflow is formulated to optimize these multiple conflicting performance objectives considering phase behavior constraints. A 2D synthetic model based on typical Athabasca oil sands properties is constructed to simulate the warm vaporized solvent process. The addition of non-condensable gas (methane) into the solvent (propane) is examined. The resultant changes in thermodynamic properties and equilibrium phase behavior are considered in determining the practical limits of the decision variables (e.g., bottom-hole injection pressure and temperature). The objective functions, including oil recovery factor, solvent retained-to-oil ratio, and energy consumption, are defined, and a factorial experimental design is employed to identify a subset of decision variables that exhibit minimal redundancy internally and create the dataset for proxy model development. To reduce the computational costs associated with reservoir simulations, proxy models, e.g., the artificial neural network (ANN), is developed and applied. Finally, a Pareto-based MOO scheme is implemented to estimate the optimal decision variables. Despite the higher front-end loading requirement of the ANN proxy modeling, the MOO with proxy modeling still requires significantly less execution/running time as compared to a MOO with traditional flow simulation (e.g., a 97% reduction in CPU time). This reduced running time is important for alleviating the computational load when evaluating the objective functions during the optimization process. More importantly, this optimization scheme is capable of identifying a set of optimal decision variables. This work presents a practical workflow for optimizing various design variables associated with many solvent-based bitumen recovery processes. Specific considerations including the practical limits for operating constraints and computational efficiency are examined and incorporated. It is anticipated that this workflow can be readily integrated into the design and decision-making processes in reservoir management.

Structural Evidence for a Reinforcing Response and Retention of Hydration During Confinement of Cartilage Lipids

Lipids have an important role in the complex lubrication of articulating joints, however changes in lipid phase behavior that occur owing to mechanical confinement are not well understood. Here, a surface force-type apparatus has been combined with neutron reflectometry to measure confinement-induced changes in the structure of lipids, the major surface-active component of the lubricant in articulating joints. The same incompressible state was accessed under low uniaxial stress (1 bar), irrespective of whether the lipids had started out unconfined above or below the Lα phase transition, and irrespective of whether they were fully or partially hydrated. In this incompressible state, the lipid component had thickened indicating extension and rearrangement of the lipid chains in response to the applied stress. The small amount of water remaining between each lipid bilayer was found to be similar for all chain lengths and starting phases. This represents the first structural evidence of the tightly bound water layer at the headgroups, which is required for hydration lubrication under load.

The numerical simulation of radiant floor cooling and heating system with double phase change energy storage and the thermal performance

Being dependent statistics, building energy consumption has accounted for 2/5 of the world's total energy consumption. The combination of phase change energy storage materials with floor radiant cooling and heating system has become one of the main technical means of energy-saving buildings. Based on double phase change energy storage capillary floor radiant heating system, considering the effect of natural convection, wide phase transition area and latent heat release, combining with the characteristics of phase change materials phase behavior change, a novel three phase zone heat transfer model was established, and the Finite Volume method was used to solve the numerical problem. Then the heat storage and heat release of phase change energy storage floor under different working conditions in winter and summer were simulated to decide the phase-change heat transfer characteristics, the best water supply temperature, and the change rule of the surface temperature of the floor were analyzed. The research results can provide theoretical support for to draw up intermittent cooling and heating schemes.

Lipid Peroxidation Enhances LO/LD Domain Phase Separation in Giant Plasma Membrane Vesicles

Lipid peroxidation is an oxidative process in which free radicals lead to the degradation of membrane lipids. The prime action of oxidative reactions in biomembranes is to increase reactive oxygen species (ROS) and form fatty acid hydroperoxides. This leads to changes in membrane fluidity, disruption of plasma membrane integrity, and impairment of lipid-protein interactions that ultimately facilitate the modification of nucleic acids and proteins by the release of reactive aldehydes and bioactive products, thus disrupting gene transcription and signal transduction. Lipid peroxidation has been linked to a number of diseases such as Alzheimer's disease. However, the effects of lipid peroxidation on plasma membrane lipids and proteins are still incompletely understood. Therefore, we used giant plasma membrane vesicles (GPMVs) as a model system to examine lipid peroxidation-induced changes in plasma membrane phase behavior. In particular, we investigated how lipid peroxidation induced using a combination of Fe(II) and Cumene hydroperoxide alters membrane physical properties, especially lipid rafts (Lo) and non-raft (Ld) phases. We find that lipid peroxidation causes dramatic enhancement of phase separation at room temperature that is accompanied by a significant increase in the fraction of the non-raft phase. These effects were concentration dependent, and similar results were observed in GPMVs derived from different cell types. Interestingly, lipid peroxidation also decreased the affinity of the model raft protein YFP-GL-GPI for raft domains, indicating that protein composition of membrane domains is also impacted by lipid peroxidation. Taken together, these findings highlight the utility of this approach to study the impact of lipid peroxidation on cell membranes and suggest a potential mechanism by which lipid peroxidation can influence cellular functions.

Physicochemical Properties and its Variation Law of Microemulsion Phase When Microemulsion Flooding

The composition change of microemulsion system in microemulsion flooding will inevitably cause the change of phase behavior. Microemulsion with different phase types directly affects its performance and displacement efficiency of microemulsion flooding. Therefore, in order to accurately describe this change, this paper, starting from the composition of microemulsion, gives the physicochemical properties characterization methods of microemulsion phase density, viscosity and interfacial tension, and simulates the change of physicochemical properties of microemulsion phase caused by microemulsion entering the high water-oil ratio zone in the process of flooding. The research results are of great significance for screening microemulsion systems and determining the displacement efficiency.