Solid-liquid Phase Transition Research Articles

Formation of synthetic RNA protein granules using engineered phage-coat-protein -RNA complexes

Liquid-solid transition, also known as gelation, is a specific form of phase separation in which molecules cross-link to form a highly interconnected compartment with solid – like dynamical properties. Here, we utilize RNA hairpin coat-protein binding sites to form synthetic RNA based gel-like granules via liquid-solid phase transition. We show both in-vitro and in-vivo that hairpin containing synthetic long non-coding RNA (slncRNA) molecules granulate into bright localized puncta. We further demonstrate that upon introduction of the coat-proteins, less-condensed gel-like granules form with the RNA creating an outer shell with the proteins mostly present inside the granule. Moreover, by tracking puncta fluorescence signals over time, we detected addition or shedding events of slncRNA-CP nucleoprotein complexes. Consequently, our granules constitute a genetically encoded storage compartment for protein and RNA with a programmable controlled release profile that is determined by the number of hairpins encoded into the RNA. Our findings have important implications for the potential regulatory role of naturally occurring granules and for the broader biotechnology field.

Numerical investigation on melting and thermal performances of a phase change material in partitioned cavities with fins for thermal energy storage

The practical application of solid-liquid phase transition latent thermal energy storage devices is restricted by the low value of thermal conductivity in phase change materials (PCMs). To alleviate this problem, a proposal for a newly developed thermal energy storage unit with metal multiple partitions and flat fins coupled is presented in this paper. The design was constructed by dividing the typical vertical rectangular thermal energy storage unit into several partitions (1, 2, 4, and 8), including 4-fins and 8-fins in different partitions. A 2D transient solid-liquid phase change numerical model was firstly validated and then the effect of different configurations was numerically determined to obtain the thermal energy storage characteristics, velocity field, solid-liquid interface, temperature distributions, and thermal transfer performances. The results show that the optimized metal partitioned cavities lower the PCM's melting time with the maximum melting time reduction occurring at a value of 76.8 % compared to the common wooden partition. Because of increased thermal networks or enhanced local natural convection, increasing the cavity partitioning and fins shortens the melting time of the PCM. The 8-partitions cavity coupled with 8-fins generates the shortest melting time. Increasing the quantity of cavity partitioning and fins also leads to a reduction in the time needed to attain the largest amount of stored energy and an increase in the Nusselt number and power.

Experimental design of composite films with thermal management and electromagnetic shielding properties based on polyethylene glycol and MXene

Based on the broad scope of applications in electronics, the development requirements of excellent electronic packaging materials with efficient thermal management performance and high electromagnetic interference shielding effectiveness (EMI SE) are critical, while which are also hardly compatible for a single material such as an elementary substance or a simple chemical compound. Therefore, a series of novel composites filled with phase change material (PCM) polyethylene glycol (PEG) were developed with MXene as the skeleton, and flame retardant Mg(OH)2 was added to achieve flame retardancy for composites under high temperature environment. As a result, the prepared MXene@PEG/Mg(OH)2 in this work could achieve an excellent EMI SE of 38.8 dB in X-band, and the thermal conductivity rose from 0.26 to 0.95 W/m·K, while the composite film also presented certain mechanical properties, with the latent heat of 153.72 J/g. Furthermore, the shape stability of the composite material was favourable due to the capillary function of MXene, which effectively forbade the leakage behavior of PCMs during solid-liquid phase transition. The design of MXene@PEG/Mg(OH)2 composite with stable structure provided a new idea for manufacturing EMI SE materials which often exposed to electromagnetic radiation, which indicated potential great significance for a new generation of packaging materials application in electronic equipment field.

Interface-resolved simulation of solid-liquid phase change with thermal convection using discrete unified gas kinetic scheme

This work presents an interface-resolved model for simulating the solid-liquid phase transition problems. In the method, the natural convection flow is handled by the recently proposed discrete unified gas kinetic scheme (DUGKS). Compared with the conventional lattice Boltzmann equation, DUGKS has more advantages on numerical stability and multiscale computation. On the other hand, the ghost-cell (GC) immersed boundary scheme is applied to capturing the solid-liquid interface of pure material. In contrast to the phase-field or enthalpy-based method, the interface here with zero thickness is resolved and explicitly tracked on the fixed Cartesian grid. It is worth noting that due to the adsorption or release of latent heat, the phase front should be evolved according to the Stefan condition. Since compatible with the GC method, the position of the melting front is directly identified by the intersection point, and the complicated treatment of marker inserting and/or deleting in the previous studies is removed. Three numerical examples, including the one-dimension conduction melting, convection melting in a square cavity and melting in a circular cavity with natural convection are conducted to test the present model. The result demonstrates the accuracy of the method for solid-liquid phase change problems.

Theoretical Framework Based on Molecular Dynamics and Data Mining Analyses for the Study of Potential Energy Surfaces of Finite-Size Particles.

Nanoclusters are remarkably promising for the capture and activation of small molecules for fuel production or as precursors for other chemicals of high commercial value. Since this process occurs under a wide variety of experimental conditions, an improved atomistic understanding of the stability and phase transitions of these systems will be key to the development of successful technological applications. In this work, we proposed a theoretical framework to explore the potential energy surface and configuration space of nanoclusters to map the most important morphologies presented by those systems and the phase transitions between them. A fully automated process was developed, which combines global optimization techniques, classical molecular dynamics, and unsupervised machine learning algorithms. To showcase these capabilities of the approach, we explored the example of copper nanoclusters (Cun) where n = 13, 38, 55, 75, 98, 102, and 147. We not only reported a graphical potential energy surface for each size, but also explored the topology of the configuration space via structural and thermodynamic analyses. The effect of size on the potential energy surface and the critical temperature for solid-liquid phase transitions were also reported, highlighting the impact of magic numbers on those quantities.

Continuous and First-Order Liquid-Solid Phase Transitions in Two-Dimensional Water.

Understanding the phase behaviors of nanoconfined water is of importance in fundamental physical science and nanofluidic applications. Herein, we perform sub-microsecond to microsecond long molecular-dynamics (MD) simulations to show evidence of continuous and first-order phase transitions of water confined between two smooth walls with width of h = 1.0 nm. At either relatively low lateral pressure (PL ≤ 10 MPa) or relatively high lateral pressure (PL ≥ 400 MPa), the freezing of the confined water undergoes a first-order phase transition and gives rise to bilayer low-density amorphous (BL-LDA) ice and the trilayer puckered high-density ice (TL-pHDI), respectively. Very interestingly, within a moderate range of lateral pressures (100 MPa ≤ PL ≤ 300 MPa), the confined water appears to undergo a continuous phase transition in the isobaric condition to form a new phase, namely, the bilayer and puckered high-density amorphous (BL-pHDA) ice. A similar continuous phase transition behavior has been reported previously in tens of nanoseconds MD simulations of the freezing of BL water into the BL flat rhombic ice within a narrower hydrophobic nanoslit (h = 0.8 nm) and in the isochoric condition at high densities of water (Han et al. Nat. Phys. 2010, 6, 685). Our simulation results on the pressure-dependent continuous and first-order phase transitions of the confined water extend the previous study in a different way and thereby provide new insights into the novel thermodynamic phase behavior of low-dimensional water in nanoscale confinement.

Germ Granules in Animal Oogenesis.

In eukaryotic cells, many macromolecules are organized as membraneless biomolecular condensates (or biocondensates). Liquid-liquid and liquid-solid phase transitions are the drivers of the condensation process. The absence of membrane borders makes biocondensates very flexible in their composition and functions, which vary in different cells and tissues. Some biocondensates are specific for germ line cells and are, thus, termed germ granules. This review summarizes the recent data on the composition of germ granules and their functions in gametes. According to these data, germ granules are involved in the determination of germline cells in some animals, such as Amphibia. In other animals, such as Mammalia, germ granules are involved in the processes of transposons inactivation and sequestration of mRNA and proteins to temporarily decrease their activity. The new data on germ granules composition and functions sheds light on germ cell differentiation and maturation properties.

Anisotropic metal foam design for improved latent heat thermal energy storage in a tilted enclosure

The metal foams are a promising candidate for the enhancement of heat transfer in latent heat thermal energy storage (LHTES) units. These foams can be synthesized with engineered local properties such as improved thermal conductivity or permeability in a specified direction. However, the impact of using anisotropic metal foams for thermal energy storage has not been addressed yet. In the current research, an anisotropic metal foam was modeled mathematically with engineered local properties in perpendicular directions. The solid-liquid phase transition of the copper-coconut oil LHTES unit was simulated using the finite element method. The anisotropic metal foam was defined by using an anisotropic parameter and angle. The simultaneous impact of the mounting tilt angle and the anisotropic angle of the copper foam were addressed in the phase transition behavior and charging time of the LHTES unit. The results revealed that the anisotropic angle could notably impact the thermal energy storage power. An optimum tilt angle of -45° or +45° along with a 0° anisotropic angle could lead to the maximum charging power. Thus, designing an LHTES unit using an anisotropic metal foam could save the charging about 15% (for a -45° inclination angle) and 20% (for zero inclination angle) compared to a regular metal foam. Such save in the charging time is without any penalty on the weight increase or capacity reduction for the LHTES unit.

Liquid-Liquid Phase Separation Promotes Protein Aggregation and Its Implications in Ferroptosis in Parkinson's Disease Dementia.

The pathological features of PDD are represented by dopaminergic neuronal death and intracellular α-synuclein (α-syn) aggregation. The interaction of iron accumulation with α-syn and tau was further explored as an essential pathological mechanism of PDD. However, the links and mechanisms between these factors remain unclear. Studies have shown that the occurrence and development of neurodegenerative diseases such as PDD are closely related to the separation of abnormal phases. Substances such as proteins can form droplets through liquid-liquid phase separation (LLPS) under normal physiological conditions and even undergo further liquid-solid phase transitions to form solid aggregates under disease or regulatory disorders, leading to pathological phenomena. By analyzing the existing literature, we propose that LLPS is the crucial mechanism causing abnormal accumulation of α-syn, tau, and other proteins in PDD, and its interaction with iron metabolism disorder is the key factor driving ferroptosis in PDD. Therefore, we believe that LLPS can serve as one of the means to explain the pathological mechanism of PDD. Determining the significance of LLPS in neurodegenerative diseases such as PDD will stimulate interest in research into treatments based on interference with abnormal LLPS.

Beyond Human Touch Perception: An Adaptive Robotic Skin Based on Gallium Microgranules for Pressure Sensory Augmentation.

Robotic skin with human-skin-like sensing ability holds immense potential in various fields such as robotics, prosthetics, healthcare, and industries. To catch up with human skin, numerous studies are underway on pressure sensors integrated on robotic skin to improve the sensitivity and detection range. However, due to the trade-off between them, existing pressure sensors have achieved only a single aspect, either high sensitivity or wide bandwidth. Here, an adaptive robotic skin is proposed that has both high sensitivity and broad bandwidth with an augmented pressure sensing ability beyond the human skin. A key for the adaptive robotic skin is a tunable pressure sensor built with uniform gallium microgranules embedded in an elastomer, which provides large tuning of the sensitivity and the bandwidth, excellent sensor-to-sensor uniformity, and high reliability. Through the mode conversion based on the solid-liquid phase transition of gallium microgranules, the sensor provides 97% higher sensitivity (16.97 kPa-1 ) in the soft mode and 262.5% wider bandwidth (≈1.45MPa) in the rigid mode compared to the human skin. Successful demonstration of the adaptive robotic skin verifies its capabilities in sensing a wide spectrum of pressures ranging from subtle blood pulsation to body weight, suggesting broad use for various applications.

Phase‐Transitional Bismuth‐Based Metals enable Rapid Embolotherapy, Hyperthermia, and Biomedical Imaging (Adv. Mater. 42/2022)

Embolic Agents In article number 2205002, Xuyang Sun, Jing Liu, and co-workers propose a novel liquid embolic agent with rapid liquid–solid phase-transition capability, for administrating simultaneous embolotherapy, hyperthermia, and biomedical imaging. Through simple syringe injection, the liquid embolic agent can flow and fill the nutrient supply vessels of the hepatoma to realize fast embolization. This high-image-contrast material with good biocompatibility is also demonstrated to produce a large amount of heat under an external electromagnetic field to enhance the therapeutic efficacy of tumor embolization, which holds great promise in future embolism and theranostic platforms.

Light-Responsive Solid-Solid Phase Change Materials for Photon and Thermal Energy Storage.

We report a series of adamantane-functionalized azobenzenes that store photon and thermal energy via reversible photoisomerization in the solid state for molecular solar thermal (MOST) energy storage. The adamantane unit serves as a 3D molecular separator that enables the spatial separation of azobenzene groups and results in their facile switching even in the crystalline phase. Upon isomerization, the phase transition from crystalline to amorphous solid occurs and contributes to additional energy storage. The exclusively solid-state MOST compounds with solid-solid phase transition overcome a major challenge of solid-liquid phase transition materials that require encapsulation for practical applications.

Soft shape-programmable surfaces by fast electromagnetic actuation of liquid metal networks

Low modulus materials that can shape-morph into different three-dimensional (3D) configurations in response to external stimuli have wide-ranging applications in flexible/stretchable electronics, surgical instruments, soft machines and soft robotics. This paper reports a shape-programmable system that exploits liquid metal microfluidic networks embedded in an elastomer matrix, with electromagnetic forms of actuation, to achieve a unique set of properties. Specifically, this materials structure is capable of fast, continuous morphing into a diverse set of continuous, complex 3D surfaces starting from a two-dimensional (2D) planar configuration, with fully reversible operation. Computational, multi-physics modeling methods and advanced 3D imaging techniques enable rapid, real-time transformations between target shapes. The liquid-solid phase transition of the liquid metal allows for shape fixation and reprogramming on demand. An unusual vibration insensitive, dynamic 3D display screen serves as an application example of this type of morphable surface.

Phase-Transitional Bismuth-Based Metals enable Rapid Embolotherapy, Hyperthermia, and Biomedical Imaging.

Embolization has been an important minimally invasive therapy for occlusion of malfunctioned vasculature and tumor treatment via target delivering embolic agents. The limitation of conventional embolic agents, such as fabrication process, precipitation time, invisibility, and lack of integrated functions often leads to insufficient embolization efficacy. To overcome these drawbacks, a multifunctional bismuth (Bi)-based liquid embolic agent for simultaneous realization of embolotherapy, thermotherapy, as well as high-contrast biomedical imaging is proposed. Benefitting from the suitable melting point, flexible nature, metallic merit, and easygoing operation via injection, the versatile embolic agent can achieve rapid liquid-solid phase transition, magnetic hyperthermia, and multimodal imaging capability. The Bi-based materials are demonstrated with excellent arteriovenous embolization efficiency and favorable biocompatibility according to in vivo investigations. Introduction of the liquid embolic agent to tumor arteries achieves evident tumor regression and rather clear imaging under computed tomography (CT), magnetic resonance imaging(MRI), and thermographs for consistently tracking the implants over the biological body. Further, the combined therapy coupled with thermotherapy exhibits improved therapeutic efficiency with formation of necrosis and total tumor eradiation at day 15after the treatment. The present innovative embolic agent and the surgical principle provide a promising modality for embolization and potential theranostic platform of tumors.

Dissolved water in jet fuels: a low-temperature quality and water solubility study

While undesirable, water contamination of jet fuels is unavoidable. It is essential to understand the impacts of dissolved water on the fuel properties and the water-fuel interactions. In this study, the impacts of dissolved water on low-temperature qualities of aviation fuels were determined. The liquid–solid phase transition temperature was found to increase with the jet fuels saturated with dissolved water under increased temperatures owing to the increase of fuel water solubility. The conductor-like screening model for realistic solvation (COSMO-RS) method was employed to predict the water solubility in petroleum and sustainable aviation fuels (PAFs and SAFs) over a temperature range of −40 to 50 °C based on fuel composition data obtained by comprehensive GC × GC chromatography. The calculation results are in good agreement with experimental values at temperatures below 20 °C, with RMSE = 17.1 and 17.7 ppm for PAFs and SAFs, respectively. Results calculated for these complex fuel chemistries predicted experimental values more closely than calculations performed for simpler PAF and SAF surrogates. COSMO-RS was also employed to calculate water solubility in PAF and SAF blends (RMSE = 18.3 ppm). Results demonstrate that the COSMO-RS method has potential as a tool in new SAF certification.

Pyroreflectometry as a technique for the accurate measurement of very high temperatures in molten materials.

Experimental research into severe nuclear accidents often requires the accurate measurement of high temperatures of molten materials. Measurements of very high temperatures (1500-2500 °C) in liquid materials using standard pyrometry can entail uncertainties in the order of 5%-10%. Pyroreflectometry is a powerful technique with the potential to significantly reduce these uncertainties. A method is proposed to optimize pyroreflectometry temperature measurements in the 1500-2500 °C range and to allow more easily the detection of the solid-liquid phase transition. The originality of this research essentially relies on the use of pyroreflectometry based on two wavelengths (1.3 and 1.55μm) and its application to liquid materials at high temperature, which implies to adapt technological elements and metrological procedures. The proposed procedure first requires temperature calibration, which is undertaken using three eutectic fixed-point cells, reducing temperature uncertainty. Second, precise settings are adopted to enable reflectivity measurements on specular surfaces, such as the surfaces of molten metals. Pyroreflectometry measurements on liquid surfaces have been validated on an iron sample. Subsequently, the application of pyroreflectometry at very high temperatures was validated on various materials: metal (iron and 18MND5 steel), oxide (alumina), and carbide (rhenium-carbon eutectic). For each of these samples, the uncertainties of temperature measurements in the 1500-2500 °C range were estimated in the range of 1%-2%, performing well against standard pyrometry measurements. The principal difficulties encountered during the pyroreflectometry characterization were the fine-tuning of parameters (optical head orientation and lens focusing) to enable measurements on highly specular surfaces and ensuring inert interactions between the samples and the crucible.

Smart Protein Refolding System Based on UCST-Type Ureido Polymers.

We have reported that ureido polymers exhibit upper critical solution temperature (UCST)-type phase behavior in solution, which is the opposite of lower critical solution temperature (LCST)-type behavior. Furthermore, UCST-type ureido polymers undergo liquid-liquid phase separation (LLPS) upon cooling rather than the liquid-solid phase transition of the typical LCST-type polymers. In this study, ureido polymers with hydrophobic groups were prepared to evaluate the effects of cooling-induced LLPS of UCST-type polymers on refolding of proteins. When protein was heated with a ureido polymer functionalized with undecyl groups, aggregation of the protein was prevented. Subsequent cooling incubation resulted in the spontaneous release of the protein from the polymer. The released protein had enzymatic activity, suggesting that the protein refolded properly. Interestingly, efficient refolding was observed when the solution of the UCST-type ureido polymer and protein was incubated at around the phase separation temperature of the polymer, implying that cooling-induced LLPS of the polymer enhanced the release of the protein. Additionally, by centrifugation at 4 °C, the refolded protein was readily separated from the ureido polymers, which precipitated upon cooling.

Self-sustained non-equilibrium co-existence of fluid and solid states in a strongly coupled complex plasma system

A complex (dusty) plasma system is well known as a paradigmatic model for studying the kinetics of solid-liquid phase transitions in inactive condensed matter. At the same time, under certain conditions a complex plasma system can also display characteristics of an active medium with the micron-sized particles converting energy of the ambient environment into motility and thereby becoming active. We present a detailed analysis of the experimental complex plasmas system that shows evidence of a non-equilibrium stationary coexistence between a cold crystalline and a hot fluid state in the structure due to the conversion of plasma energy into the motion energy of microparticles in the central region of the system. The plasma mediated non-reciprocal interaction between the dust particles is the underlying mechanism for the enormous heating of the central subsystem, and it acts as a micro-scale energy source that keeps the central subsystem in the molten state. Accurate multiscale simulations of the system based on combined molecular dynamics and particle-in-cell approaches show that strong structural nonuniformity of the system under the action of electostatic trap makes development of instabilities a local process. We present both experimental tests conducted with a complex plasmas system in a DC glow discharge plasma and a detailed theoretical analysis.

Improvement effect of a double-level phase change material on compressive strengths of Portland cementitious materials after elevated temperatures

In this investigation, a specially prepared double-level phase change material (DL-PCM) was introduced to ordinary Portland cement(OPC) to improve compressive strengths after elevated temperatures. Solid-liquid phase transition characteristics of DL-PCM and changes in compressive strength, water absorption, mass, as well as meso structures and mineral compositions of OPC after elevated temperatures were determined to clarify improvement mechanisms of DL-PCM on compressive strengths of OPC after elevated temperatures. Results show after 500 °C and 600 °C exposures, compressive strengths of OPC added with DL-PCM were basically equal to or a little higher than those at room temperatures. Cracks in DL-PCM introduced OPC matrix and water absorptions were significantly reduced. During the heating and cooling process, DL-PCM experienced solid-liquid-solid phase transitions, forming hard densifed solids to fill cracks and pores, significantly improving integrity of OPC matrix. Consequently, compressive strengths of DL-PCM introduced OPC were significantly increased compared to those without DL-PCM after elevated temperatures.

Enthalpy-based immersed boundary-lattice Boltzmann model for solid-liquid phase change in porous media under local thermal non-equilibrium condition

Heat transfer enhancement structures are adopted to improve the performance of latent heat thermal energy storage (LHTES) systems, such as metallic porous matrix, multi-tube, and fin. The metallic porous matrix and complex geometries of the structures bring difficulties to the numerical studies of the solid-liquid phase transition in the enhanced LHTES system. In this work, an enthalpy-based immersed boundary (IB)-lattice Boltzmann (LB) model is proposed for solid-liquid phase change problems in porous media under the local thermal non-equilibrium (LTNE) condition. In this model, to reduce the numerical diffusion across the solid-liquid interface, a two-relaxation-time (TRT)-LB model is developed to obtain the temperature field of phase change material (PCM). Two single-relaxation-time (SRT)-LB equations (LBEs) are employed for the velocity field of the liquid PCM and the temperature field of the porous matrix, respectively. The partially saturated method is used for the non-slip boundary condition on the moving solid-liquid interface. Different discrete source term schemes are employed for source terms induced by surface heat transfer and IB. Based on the source term treatment, the multi-direct-forcing IB-LB method is employed for the implementation of velocity, enthalpy and temperature boundary conditions on the complex boundary. The proposed model is verified by four cases: one-dimensional conduction melting under the LTNE condition, natural convection in a metallic porous matrix-filled cavity, conduction melting in an annulus filled with metallic porous matrix, and constrained melting in an isothermal circular cylinder without porous media. As an example of application, a metallic porous matrix-enhanced LHTES system with different multi-tube arrangements at different Rayleigh numbers (Ra) and porosities is investigated.