Condensation Phase Transition Research Articles

Thermodynamic geometry of a system with unified quantum statistics.

We investigate the thermodynamic characteristics of unified quantum statistics, a framework exhibiting a crossover between Bose-Einstein and Fermi-Dirac statistics by varying a generalization parameter δ. An intrinsic statistical interaction becomes attractive for δ≤0.5, maintaining positive thermodynamic curvature across the entire physical range. In the range 0.5<δ<1, the system predominantly displays Fermi-like behavior at high temperatures. Conversely, at low temperatures, the thermodynamic curvature is positive, resembling bosonic behavior. Further temperature reduction induces a transition into the condensate phase. We introduce a critical fugacity (z=Z^{*}) at which the thermodynamic curvature changes sign. Below (z<Z^{*}) and above (z>Z^{*}) this critical point, the statistical behavior mimics fermions and bosons, respectively. We explore the system's statistical behavior for various δ values with respect to temperature, determining the critical fugacity and temperature-dependent condensation. Finally, we analyze specific heat as a function of temperature and condensation phase transition temperature for different δ values in various dimensions.

Targeting of biomolecular condensates to the autophagy pathway.

Biomolecular condensates are membraneless compartments formed by liquid-liquid phase separation. They can phase transit into gel-like and solid states. The amount and state of biomolecular condensates must be tightly regulated to maintain normal cellular function. Autophagy targets biomolecular condensates to the lysosome for degradation or other purposes, which we term biocondensophagy. In biocondensophagy, autophagy receptors recognize biomolecular condensates and target them to the autophagosome, the vesicle carrier of autophagy. Multiple types of autophagy receptors have been identified and they are specifically involved in targeting biomolecular condensates with different phase transition states. The receptors also organize the phase transition of biomolecular condensate to facilitate biocondensophagy. Here, we briefly discuss the latest discoveries regarding how biomolecular condensates are recognized by autophagy receptors.

Numerical study on two-phase supersonic expansion refrigeration in novel CO2 refrigeration technology

The serious environmental problems have promoted the development of CO2 natural working fluid refrigerants. The supersonic two-phase expander with supersonic nozzle as the key component is proposed. A novel CO2 supersonic two-phase expansion refrigeration cycle is constructed and its cycle performance is also calculated. Then, the numerical simulation of the flow condensation and liquefaction process of CO2 in the nozzle is carried out. The results show that the inlet parameters of the supersonic two-phase expander have an important effect on the cycle performance. With the increase of inlet pressure, COP first increases and then decreases. The optimal inlet pressure of the system is 5.3 MPa with the corresponding maximum COP by 2.50, and the Relative Carnot Efficiency decreases from 0.809 to 0.755. With the inlet temperature increase, the maximum COP and the Relative Carnot Efficiency are 2.49 and 0.826, respectively. The established model can reasonably describe the supersonic expansion refrigeration characteristics and condensation phase transition characteristics of CO2. With the increase of nozzle inlet pressure and the decrease of temperature, the inlet degree of supercooling increases, while the initial nucleation position moves forward further and the peak nucleation rate decreases. Meanwhile, the droplet number decreases, both the droplet radius and the liquid mass fraction increases. The ideal cycle performs well, which provides a valuable reference for CO2 utilization.

Progress of Seepage Law and Development Technologies for Shale Condensate Gas Reservoirs

With the continuous development of conventional oil and gas resources, the strategic transformation of energy structure is imminent. Shale condensate gas reservoir has high development value because of its abundant reserves. However, due to the multi-scale flow of shale gas, adsorption and desorption, the strong stress sensitivity of matrix and fractures, the abnormal condensation phase transition mechanism, high-speed non-Darcy seepage in artificial fractures, and heterogeneity of reservoir and multiphase flows, the multi-scale nonlinear seepage mechanisms are extremely complicated in shale condensate gas reservoirs. A certain theoretical basis for the engineering development can be provided by mastering the percolation law of shale condensate gas reservoirs, such as improvement of productivity prediction and recovery efficiency. The productivity evaluation method of shale condensate gas wells based on empirical method is simple in calculation but poor in reliability. The characteristic curve analysis method has strong reliability but a great dependence on the selection of the seepage model. The artificial intelligence method can deal with complex data and has a high prediction accuracy. Establishing an efficient shale condensate gas reservoir development simulation technology and accurately predicting the production performance of production wells will help to rationally formulate a stable and high-yield mining scheme, so as to obtain better economic benefits.

The impact of Grb2 on phase condensation in live cells.

Two-dimensional protein condensation phase transitions on the membrane driven by tyrosine phosphorylation have been identified in several receptor signaling systems, including T cell receptor (via LAT)1,2 and EGFR.3 In the cases of both LAT and EGFR, we have found that the receptor scaffold and Grb2 are sufficient to form a membrane surface condensate in reconstituted systems using supported bilayer membranes. Furthermore, phosphorylation at the Y160 residue on Grb2 is sufficient to block this condensation. To follow up on these reconstitution results in live cells, we created a Grb2-knockout jurkat cell line. Results examining the impact of various Grb2 mutations on condensation in the live cell context using this system will be discussed.

Effect of a membrane protein condensation phase transition on reaction-diffusion kinetics.

Reversible biomolecular phase transitions, such as liquid-liquid phase transition in cytosolic proteins, and phosphorylation-driven condensation in membrane-bound systems have been cited as underlying mechanisms for numerous important cellular processes such as signal transduction. For example, condensation of the T cell signaling protein LAT, and, separately, Epidermal Growth Factor Receptor has been shown to elongate the membrane dwell time of the Ras-GEF SOS, enabling it to overcome a series of slow, membrane dependent activation steps. However, evidence from in-vitro reconstitution experiments suggests that formation of a condensed phase may not solely be beneficial to membrane-associated enzyme kinetics. SOS is both a scaffolding component, and a downstream effector of signaling condensates upstream of the Ras/Erk pathway. In such systems, its substrate Ras needs to have access to SOS for nucleotide exchange to take place. Sequestration of SOS proteins within a networked condensate may inhibit the ability of Ras to encounter SOS by diffusion. To investigate, we reconstitute protein condensation phase transitions consisting of the phosphotyrosine tails of either LAT or EGFR on supported lipid bilayers, along with the crosslinking components Grb2 and the PR domain of SOS to induce condensation. Under these conditions, single molecule TIRF microscopy can be used to localize and track membrane diffusion and partitioning between the condensed domains and surrounding sparse phase.

Discrete LAT condensates encode antigen information from single pMHC:TCR binding events

LAT assembly into a two-dimensional protein condensate is a prominent feature of antigen discrimination by T cells. Here, we use single-molecule imaging techniques to resolve the spatial position and temporal duration of each pMHC:TCR molecular binding event while simultaneously monitoring LAT condensation at the membrane. An individual binding event is sufficient to trigger a LAT condensate, which is self-limiting, and neither its size nor lifetime is correlated with the duration of the originating pMHC:TCR binding event. Only the probability of the LAT condensate forming is related to the pMHC:TCR binding dwell time. LAT condenses abruptly, but after an extended delay from the originating binding event. A LAT mutation that facilitates phosphorylation at the PLC-γ1 recruitment site shortens the delay time to LAT condensation and alters T cell antigen specificity. These results identify a function for the LAT protein condensation phase transition in setting antigen discrimination thresholds in T cells.

Kinetic frustration by limited bond availability controls the LAT protein condensation phase transition on membranes.

LAT is a membrane-linked scaffold protein that undergoes a phase transition to form a two-dimensional protein condensate on the membrane during T cell activation. Governed by tyrosine phosphorylation, LAT recruits various proteins that ultimately enable condensation through a percolation network of discrete and selective protein-protein interactions. Here, we describe detailed kinetic measurements of the phase transition, along with coarse-grained model simulations, that reveal that LAT condensation is kinetically frustrated by the availability of bonds to form the network. Unlike typical miscibility transitions in which compact domains may coexist at equilibrium, the LAT condensates are dynamically arrested in extended states, kinetically trapped out of equilibrium. Modeling identifies the structural basis for this kinetic arrest as the formation of spindle arrangements, favored by limited multivalent binding interactions along the flexible, intrinsically disordered LAT protein. These results reveal how local factors controlling the kinetics of LAT condensation enable formation of different, stable condensates, which may ultimately coexist within the cell.

Phase transition dimensionality crossover from two to three dimensions in a trapped ultracold atomic Bose gas

The equilibrium properties of a weakly interacting atomic Bose gas across the Berezinskii-Kosterlitz-Thouless (BKT) and Bose-Einstein condensation (BEC) phase transitions are numerically investigated through a dimensionality crossover from two to three dimensions. The crossover is realized by confining the gas in an experimentally feasible hybridized trap which provides homogeneity along the planar $xy$ directions through a box potential in tandem with a harmonic transverse potential along the transverse $z$ direction. The dimensionality is modified by varying the frequency of the harmonic trap from tight to loose transverse trapping. Our findings, based on a stochastic (projected) Gross-Pitaevskii equation, showcase a continuous shift in the character of the phase transition from BKT to BEC, and a monotonic increase of the identified critical temperature as a function of dimensionality, with the strongest variation exhibited for small chemical potential values up to approximately twice the transverse confining potential.

A two-component protein condensate of the EGFR cytoplasmic tail and Grb2 regulates Ras activation by SOS at the membrane

We reconstitute a phosphotyrosine-mediated protein condensation phase transition of the ∼200 residue cytoplasmic tail of the epidermal growth factor receptor (EGFR) and the adaptor protein, Grb2, on a membrane surface. The phase transition depends on phosphorylation of the EGFR tail, which recruits Grb2, and crosslinking through a Grb2-Grb2 binding interface. The Grb2 Y160 residue plays a structurally critical role in the Grb2-Grb2 interaction, and phosphorylation or mutation of Y160 prevents EGFR:Grb2 condensation. By extending the reconstitution experiment to include the guanine nucleotide exchange factor, SOS, and its substrate Ras, we further find that the condensation state of the EGFR tail controls the ability of SOS, recruited via Grb2, to activate Ras. These results identify an EGFR:Grb2 protein condensation phase transition as a regulator of signal propagation from EGFR to the MAPK pathway.

Current Research Trends in the Process of Condensation of Cooling Zeotropic Mixtures in Compact Condensers

This paper is an introduction to the cycle proposed by the authors related to research directions concerning the problems of condensation of zeotropic refrigerant mixtures. For over a hundred years, research has been conducted on the search for new working fluids in the cycles for cooling devices and heat pumps. Initially, the natural refrigerants used were replaced with homogeneous synthetic refrigerants, followed by mixtures of two or more refrigerants. Among the mixtures, there are azeotropic and zeotropic mixtures. In the case of an azeotrope mixture, a liquid solution of two or more chemical compounds is in thermodynamic equilibrium with the saturated vapor resulting from this mixture. The chemical composition of the liquid and vapor is identical. A zeotropic mixture is a liquid-vapor system in which the composition of a liquid mixture (solution) of two or more chemical compounds is always different from that of the saturated vapor generated from this liquid. This is due to the different boiling and condensation temperatures of the individual components of the mixture at the same pressure. There is a so-called temperature glide. The phase transformations of individual components do not run simultaneously, which means that the boiling or condensation phase transition temperature changes during the process being carried out. This raises a number of computational, design, and operational problems for power equipment. Today, however, zeotropic mixtures find an alternative to refrigerants with a high GWP potential. Despite the disadvantage of temperature glide, they also have advantages. These include ecological, energy, and economic indicators. As a result, they are increasingly used in the energy economy. This prompts researchers to conduct further research in the field of a detailed description of the phenomenon of boiling and condensation phase transformations of zeotropic mixtures under temperature glide, searching for new computational relationships, new design solutions, and applications. It is still an insufficiently recognized research problem. Bearing the above in mind, the authors made an attempt to review the state of knowledge in this area. Particular attention was paid to the progress in modeling the condensation phenomenon of zeotropic mixtures for application in compact heat exchangers. Miniaturization of cooling devices creates great application possibilities in this area.

Stationary structures of spin-orbit coupled polariton condensates in Bessel lattices

&lt;sec&gt;Bessel optical lattice yields a non-spatially periodic column-symmetric optical lattice potential field, which has the characteristics of both infinite deep potential well and the ring-shaped potential well. A deep potential is formed in the center of the 0-order Bessel optical lattice. In the non-zero-order Beseel optical lattice, a ring-shaped shallow potential well with a central barrier can be formed. Exciton-polariton is a semi-light and semi-matter quasi-particle, which can achieve the Bose-Einstein condensate phase transition even at room temperature to form a polariton condensate. In addition, the polariton condensate is likely to realize sufficiently strong spin-orbit coupling due to the cavity-induced TE-TM splitting of the polariton energy levels. The polariton condensate can be realized at room temperature, and there can be spin-orbit coupling in it, which provides a new platform for the studying of quantum physics. &lt;/sec&gt;&lt;sec&gt;In this paper, the Bessel optical lattice is introduced into a polariton condensate. The stationary state structure of spinor two-component polariton condensate with spin-orbit coupling is investigated. By solving the Gross-Pitaevskii equation, we first give a stationary state structures of the polariton condensate both in the laboratory coordinate frame and in the rotating coordinate frame. Owing to the introduction of the Bessel optical lattice, the stationary state structures of polariton condensate are diverse. We dispaly the stationary state structures of the basic Gaussian solitons and multipole solitons in the central deep potential well in the laboratory coordinate frame, and the ring solitons and multipole solitons in the central shallow potential well. We also dispaly the vortex ring soliton that exists in the rotating coordinate frame, and the stationary state structure of the component separation caused by the spin-orbit interaction. We analyze not only the influences of the spin-orbit coupling on the stationary state structures in the two coordinate frames, but also the stability of the multipole solitons in the rotating coordinate frame. It is found that the multipole solitons formed in the ring-shaped shallow potential well have better stability than in the central deep potential well, and they can maintain the relative structure and spatial distribution for a long time in the rotation process. In the rotating coordinate frame, even if the two-component separation conditions are not satisfied, the introduction of spin-orbit coupling can cause the two components to separate.&lt;/sec&gt;

Photon thermalization and a condensation phase transition in an electrically pumped semiconductor microresonator.

We report on an experimental study of photon thermalization and condensation in a semiconductor microresonator in the weak-coupling regime. We measure the dispersion relation of light and the photon mass in a single-wavelength, broad-area resonator. The observed luminescence spectrum is compatible with a room-temperature, thermal-equilibrium distribution. A phase transition, identified by a saturation of the population at high energies and a superlinear increase of the occupation at low energy, takes place when the phase-space density is of order unity. We explain our observations by Bose-Einstein condensation of photons in equilibrium with a particle reservoir and discuss the relation with laser emission.

A General Fret-Based Method to Monitor Protein Oligomerization and Condensate Phase Transition in Cells

Proteins can self-assemble into a wide range of architectures, ranging from microscopically invisible small oligomers to condensates of varying structure and dynamics. These assemblies are essential for the functioning of the cell and are associated with many kinds of diseases. Because the intracellular environment influences assemblies concerning stoichiometry, structure, and dynamics, which is due to chaperone action or nonspecific interactions, it pertinent that these assemblies are monitored in a minimally invasive manner inside cells. Here we present a FRET-based method that allows detailed monitoring of protein self-assembly. The sensitive nature of this method allows monitoring the dynamic aggregation behavior and distinguishing different types of assemblies. We thus observe the dynamic structural transition between unstructured condensates and fibrils and confirm an array of previous observations on aggregations in yeast and HEK293. In addition, we find a distinct cell-to-cell variation in kinetics and structure of the respective condensates. This method is modular and easily implemented in other native or non-native proteins and will provide crucial insight into protein self-assembly.

Stability of the structure and redox state of ferricytochrome c in the desolvation process

Stability of the structure and redox state of ferricytochrome c during continuous changing of the hydration environment from dilute solution to condensed phase was studied based on real-time resonance Raman measurement. Our experimental results indicated that the structure and redox state of ferricytochrome c were sufficiently maintained during the entire desolvation process, which reflected that the stabilizing excluded-volume effect was stronger than the destabilizing crowder-protein interaction, at the case of globular mini-protein itself acting as the crowder. Rapid reduction of ferricytochrome c was observed at measurement sites at the time of solution to condensed phase transition. Similar phenomenon was observed on cytochrome c adsorbed on indium tin oxide surface. At present conditions, the rapid reduction was found to be derived mainly from thermal reduction under laser illumination and secondarily from photoreduction induced by the residual adsorbed ferrocyanide anions. After re-dissolved, the protein which had undergone sufficient desolvation recovered the structure and redox state in the initial solution phase, suggesting that the crowding effect in solution prevented large protein deformations observed in gas phase condition.

Dynamical phase transition of photon condensate in an optical cavity

We demonstrate the existence of a dynamical phase transition in the quasi-one-dimensional photonic condensate system formed in an axially symmetric optical cavity filled with a suitable thermalizing medium. The dynamical transition is observed to occur between the periodically modulated superfluid phase and the superfluid droplets phase. The parameter domains and conditions leading to such a dynamical phase transition are identified. It is observed that such a transition in the system owes its origin to the collective photon dynamics rather than thermal or quantum effects.

Coupled membrane lipid miscibility and phosphotyrosine-driven protein condensation phase transitions

Lipid miscibility phase separation has long been considered to be a central element of cell membrane organization. More recently, protein condensation phase transitions, into three-dimensional droplets or in two-dimensional lattices on membrane surfaces, have emerged as another important organizational principle within cells. Here, we reconstitute the linker for activation of T cells (LAT):growth-factor-receptor-bound protein 2 (Grb2):son of sevenless (SOS) protein condensation on the surface of giant unilamellar vesicles capable of undergoing lipid phase separations. Our results indicate that the assembly of the protein condensate on the membrane surface can drive lipid phase separation. This phase transition occurs isothermally and is governed by tyrosine phosphorylation on LAT. Furthermore, we observe that the induced lipid phase separation drives localization of the SOS substrate, K-Ras, into the LAT:Grb2:SOS protein condensate.

Kibble-Zurek dynamics in a trapped ultracold Bose gas

The dynamical evolution of an inhomogeneous ultracold atomic gas quenched at different controllable rates through the Bose-Einstein condensation phase transition is studied numerically in the premise of a recent experiment in an anisotropic harmonic trap. Our findings based on the stochastic (projected) Gross-Pitaevskii equation are shown to be consistent at early times with the predictions of the homogeneous Kibble-Zurek mechanism. This is demonstrated by collapsing the early dynamical evolution of densities, spectral functions and correlation lengths for different quench rates, based on an appropriate characterization of the distance to criticality felt by the quenched system. The subsequent long-time evolution, beyond the identified dynamical critical region, is also investigated by looking at the behaviour of the density wavefront evolution and the corresponding phase ordering dynamics.

Thermodynamic geometry, transition between attractive and repulsive interactions and condensation of dual statistics

We consider new generalized statistics based on the generalization of statistical weight. We work out the thermodynamic curvature of an ideal gas with particles obeying such generalized statistics. For different values of generalization parameters; p and q, we observe that both attractive and repulsive intrinsic statistical interaction is expected. As long as p ⩾ q, the thermodynamic curvature is positive in full physical range. We show that for p < q, generally dominant behavior in high temperature is Fermi-like while in low temperature, the thermodynamic curvature is positive and the systems behaves such as bosons. Also, by more decreasing of the temperature, the system transits to the condensate phase. In fact, the attractive statistical interaction is related to parameter p, while by increasing the value of q, the repulsive interaction is induced. Explicitly, the specified fugacity () of the system, where the sign of thermodynamic curvature is changed and for (z > z∗p,q) the statistical behavior is fermion like (boson like ), is explored. Also, we extract the variation of statistical behavior of the system for different values of generalization parameters with respect to the temperature. Finally, we investigate the condensation phase transition temperature of the system for different values of generalization parameters.

Persistent current formation in double-ring geometries

Quenching an ultracold bosonic gas in a ring across the Bose–Einstein condensation phase transition is known, and has been experimentally observed, to lead to the spontaneous emergence of persistent currents. The present work examines how these phenomena generalize to a system of two experimentally accessible explicitly two-dimensional co-planar rings with a common interface, or to the related lemniscate geometry, and demonstrates an emerging independence of winding numbers across the rings, which can exhibit flow both in the same and in opposite directions. The observed persistence of such findings in the presence of dissipative coupled evolution due to the local character of the domain formation across the phase transition and topological protection of the randomly emerging winding numbers should be within current experimental reach.