Solid-liquid Phase Transition Research Articles

Engineering a triple-functional magnetic gel driving mutually-synergistic mild hyperthermia-starvation therapy for osteosarcoma treatment and augmented bone regeneration

Malignant bone tumors result in high rates of disability and death and are difficult to treat in terms of killing tumors and repairing bone defects. Compared with other hyperthermia strategies, magnetic hyperthermia has become an effective therapy for treating malignant bone tumors due to its lack of depth limitations. However, tumor cells express heat shock protein (HSP) to resist hyperthermia, which reduces its curative effect. Competitive ATP consumption can reduce HSP production; fortunately, the basic principle of starvation therapy by glucose oxidase (GOx) is consuming glucose to control ATP production, thereby restricting HSP generation. We developed a triple-functional magnetic gel (Fe3O4/GOx/MgCO3@PLGA) as a magnetic bone repair hydrogels (MBRs) with liquid‒solid phase transition capability to drive magneto-thermal effects to simultaneously trigger GOx release and inhibit ATP production, reducing HSP expression and thereby achieving synergistic therapy for osteosarcoma treatment. Moreover, magnetic hyperthermia improves the effect of starvation therapy on the hypoxic microenvironment and achieves a reciprocal strengthening therapeutic effect. We further demonstrated that in situ MBRs injection effectively suppressed tumor growth in 143B osteosarcoma tumor-bearing mice and an in-situ bone tumor model in the rabbit tibial plateau. More importantly, our study also showed that liquid MBRs could effectively match bone defects and accelerate their reconstruction via magnesium ion release and enhanced osteogenic differentiation to augment the regeneration of bone defects caused by bone tumors, which generates fresh insight into malignant bone tumor treatment and the acceleration of bone defect repair.

Comprehensive Characterization of Kukui Nuts as Feedstock for Energy Production in Hawaii.

Fuel properties of oil-bearing kukui (Aleurites moluccana) nuts, a commonly found crop in Hawaii and tropical Pacific regions, were comprehensively studied to evaluate their potential for bioenergy production. Proximate and ultimate analyses, heating value, and elemental composition of the seed, shell, and de-oiled seed cake were determined across five sampling locations in Hawaii. The aged and freshly harvested kukui seeds were found to have similar oil contents, ranging from 61 to 64%wt. Aged seeds, however, have 2 orders of magnitude greater free fatty acids than those freshly harvested (50% vs 0.4%). The nitrogen content of the de-oiled kukui seed cake was found to be comparable to that of the soybean cake. Aging of kukui seeds can decrease the flashpoint temperature and increase the liquid-solid phase transition temperatures of kukui oil obtained. Mg and Ca are the major ash-forming elements present in the kukui shells, >80%wt of all metal elements detected, which may reduce deposition problems for thermochemical conversion in comparison with hazelnut, walnut, and almond shells. The study also revealed that kukui oil has similar characteristics to canola, indicating that it is well-suited for biofuel production.

Principle and Feasibility Study of Proposed Hydrate-Based Cyclopentane Purification Technology

The separation of azeotropic mixtures has conventionally been one of the most challenging tasks in industrial processes due to the fact that components in the mixture will undergo gas–liquid phase transition at the same time. We proposed a method for separating azeotropes using hydrate formation as a solid–liquid phase transition. The feasibility of hydrate-based separation is determined by analyzing the crystal structure and chemical bonds of hydrate. Taking the azeotrope cyclopentane and neohexane in petroleum as an example, cyclopentane (95%) was purified to 98.56% yield using the proposed hydrate-based cyclopentane purification technology. However, this is difficult to achieve using conventional distillation methods. The proposed method is simple in operation and yields a good separation effect. This study provides a new method for separating cyclopentane and neohexane.

Free electron laser stochastic spectroscopy revealing silicon bond softening dynamics

Time-resolved x-ray emission/absorption spectroscopy (Tr-XES/XAS) is an informative experimental tool sensitive to electronic dynamics in materials, widely exploited in diverse research fields. Typically, Tr-XES/XAS requires x-ray pulses with both a narrow bandwidth and subpicosecond pulse duration, a combination that in principle finds its optimum with Fourier transform-limited pulses. In this work, we explore an alternative experimental approach, capable of simultaneously retrieving information about unoccupied (XAS) and occupied (XES) states from the stochastic fluctuations of broadband extreme ultraviolet pulses of a free electron laser. We used this method, in combination with singular-value decomposition and Tikhonov regularization procedures, to determine the XAS/XES response from a crystalline silicon sample at the ${L}_{2,3}$ edge, with an energy resolution of a few tens of meV. Finally, we combined this spectroscopic method with a pump-probe approach to measure structural and electronic dynamics of a silicon membrane. Tr-XAS/XES data obtained after photoexcitation with an optical laser pulse at 390 nm allowed us to observe perturbations of the band structure, which are compatible with the formation of the predicted precursor state of a nonthermal solid-liquid phase transition associated with a bond softening phenomenon.

Effect of filling configurations on melting heat transfer characteristic of phase change materials partially filled with metal foam

Metal foam embedded in phase change materials (PCM) has been shown to significantly improve the storage of latent heat thermal energy. Nonetheless the presence of metal foam also reduces natural convection, energy storage and increases cost. To address this issue, we modelled the internal flow of heat transfer in a PCM, paraffin wax, filled with metal foam at the top or the bottom, with filling height ratio ξ of 0.25, 0.5 and 0.75. The liquid-solid phase transition was studied by numerical simulations. Results show that natural convection in the pure paraffin wax area is higher, and melting time is shorter, in the bottom-filled than in the top-filled configuration. These differences increase with filling height ratio. By contrast, in metal foam-paraffin composite region, melting time is longer in the bottom-filled configuration due to heat loss. Interestingly, we observed significant changes in the interface shape of liquid-solid PCM at the junction of the pure paraffin and the metal foam-paraffin composite region. The liquid fraction formulas for different metal foam filled configurations are established as the function of Fourier number, Rayleigh number and filling height ratio.

Thermal and Electrical Properties of Liquid Metal Gallium During Phase Transition

Liquid metal gallium has been widely used in numerous fields, from nuclear engineering, catalysts, and energy storage to electronics owing to its remarkable thermal and electrical properties along with low viscosity and nontoxicity. Compared with high-temperature liquid metals, room-temperature liquid metals, such as gallium (Ga), are emerging as promising alternatives for fabricating advanced energy storage devices, such as phase change materials, by harvesting the advantageous properties of their liquid state maintained without external energy input. However, the thermal and electrical properties of liquid metals at the phase transition are rather poorly studied, limiting their practical applications. In this study, we reported on the physical properties of the solid–liquid phase transition of Ga using a custom-designed, solid–liquid electrical and thermal measurement system. We observed that the electrical conductivity of Ga progressively decreases with an increase in temperature. However, the Seebeck coefficient of Ga increases from 0.2 to 2.1 µV/K, and thermal conductivity from 7.6 to 33 W/(K∙m). These electrical and thermal properties of Ga at solid–liquid phase transition would be useful for practical applications.

A phase transition approach to elucidate the propagation of shear waves in viscoelastic materials

In the field of acoustics, a medium has traditionally been considered a liquid if shear waves cannot propagate. For more complex liquids, such as those containing polymer chains or surfactant aggregates, this definition begins to be unclear. By adopting a rheological model-independent approach, this work investigated by means of dynamic elastography, the liquid–solid phase transitions in viscoelastic liquid media. When the storage shear modulus G′ dominated the loss shear modulus G″, a minimal shear wave attenuation frequency region was defined and the medium was considered solid. When G″ dominated G′, the shear waves were strongly attenuated and the medium was considered liquid. The investigated medium, an aqueous solution of xanthan gum, behaved as a bandpass filter with transition bands, showing liquid–solid–liquid behavior from low to high frequency. During these transitions bands, shear waves still propagated but highly attenuated. The limiting values where shear waves were no longer observed were identified as the low and high cutoff frequencies. Finally, the ability of various rheological models to predict the phase transition frequencies and describe the dispersion curves was tested. A three-element rheological model, the Jeffreys model, was required to accurately fit the experimental response of the medium at different concentrations over the entire frequency range. Shear wave propagation methods can overcome the technical limitations of traditional rheometry and explore higher frequencies, rarely investigated in viscoelastic liquids.

Oriented High Thermal Conductivity Solid-Solid Phase Change Materials for Mid-Temperature Solar-Thermal Energy Storage.

As the global energy crisis intensifies, the development of solar energy has become a vital area of focus for many nations. The utilization of phase change materials (PCMs) for photothermal energy storage in the medium temperature range holds great potential for various applications, but their conventional forms face several challenges. For instance, the longitudinal thermal conductivity of photothermal PCMs is inadequate for effective heat storage on the photothermal conversion surface, and there is a risk of leakage due to repeated solid-liquid phase transitions. Here, we report a solid-solid phase change material, tris(hydroxymethyl)aminomethane (TRIS), which has a phase change temperature of 132 °C in the medium temperature range, enabling high-grade and stable solar energy storage. To overcome the low thermal conductivity problem, we propose a large-scale production of oriented high thermal conductivity composites by compressing a mixture of TRIS and expanded graphite (EG) using the pressure induction method to create in-plane highly thermally conductive channels. Remarkably, the resulting phase change composites (PCCs) exhibit a directional thermal conductivity of 21.3 W/(m·K). Furthermore, the high phase change temperature (132 °C) and large phase change entropy (213.47 J/g) enable a large-capacity high-grade thermal energy to be used. The developed PCCs, when combined with selected photo-absorbers, exhibit efficient integration of solar-thermal conversion and storage. Additionally, we also demonstrated a solar-thermoelectric generator device with an energy output of 93.1 W/m2, which is close to the power of photovoltaic systems. Overall, this work provides a technological route to the large-scale fabrication of mid-temperature solar energy storage materials with high thermal conductivity, high phase change enthalpy, and no risk of leakage, and also offers a potential alternative to photovoltaic technology.

Fast Charging of a Thermal Accumulator Based on Paraffin with the Addition of 0.3 wt. % rGO

The composite of paraffin with reduced graphene oxide (paraffin/rGO) was obtained at 70 °C by the mechanical mixing of the components followed by ultrasonic dispersion. The introduction of only 0.3 wt.% rGO stained the paraffin black. It has been shown that thermal batteries made from 160 grams of pure paraffin and 160 grams of the composite are equally slow at charging when placed in boiling water. However, two minutes of microwave heating increases the temperature of the pure paraffin battery to only 32 °C, while the temperature of the paraffin/rGO composite battery rises to 74 °C, which is above the paraffin solid–liquid phase transition temperature.

Analytical investigation into the powder distribution and laser beam-powder flow interaction in laser direct energy deposition with a continuous coaxial nozzle

The powder distribution and interaction between the laser beam and powder flow affect the deposition quality during the process of laser direct energy deposition with a continuous coaxial nozzle. In this paper, some key analytical formulae related to the laser beam-powder flow interaction are comprehensively deduced and validated. The powder distribution formulae for different regions are first established considering the divergence angles of powder jet. The energy attenuation formulae of laser beam passing through the powder flow are derived considering the change of powder distribution from annular to circular Gaussian modes. The temperature formulae of powder particles passing through the laser beam are derived based on a proposed temperature formula with the solid-liquid phase transition, and the powder temperature is also further analyzed. These formulae are validated by published deposition examples and used to analyze the laser beam-powder flow interaction.

Characterization of Agarose Gels in Solvent and Non-Solvent Media.

Agarose is known to form a homogeneous thermoreversible gel in an aqueous medium over a critical polymer concentration. The solid-liquid phase transitions are thermoreversible but depend on the molecular structure of the agarose sample tested. The literature has mentioned that agarose gels could remain stable in non-solvents such as acetone or ethanol. However, there has been no characterization of their behavior nor a comparison with the gels formed in a good solvent such as water. In the first step of this article, the structure was characterized using 1H and 13C NMR in both D2O and DMSO-d6 solvents. DMSO is a solvent that dissolves agarose regardless of the temperature. First, we have determined a low yield of methyl substitution on the D-galactose unit. Then, the evolution of the 1H NMR spectrum was monitored as a function of temperature during both increasing and decreasing temperature processes, ranging from 25 to 80 °C. A large thermal hysteresis was obtained and discussed, which aided in the interpretation of rheological behavior. The hysteresis of NMR signals is related to the mobility of the agarose chains, which follows the sol/gel transition depending on the chains' association with H-bonds between water and the -OH groups of agarose for tightly bound water and agarose/agarose in chain packing. In the second step of the study, the water in the agarose gel was exchanged with ethanol, which is a non-solvent for agarose. The resulting gel was stable, and its properties were characterized using rheology and compared to its behavior in aqueous media. The bound water molecules that act as plasticizers were likely removed during the exchange process, resulting in a stronger and more brittle gel in ethanol, with higher thermal stability compared to the aqueous gel. It is the first time that such gel is characterized without phase transition when passing from a good solvent to a non-solvent. This extends the domains of application of agarose.

Shape-stabilized 1-hexadecanol/g-C3N4/Cu composite phase change material with high thermal conductivity for efficient photo-thermal conversion

Phase change materials (PCM) have received much attention for thermal energy storage and release in the form of latent heat. 1-hexadecanol (HD), as a representative of organic phase change materials, has the advantages of high thermal storage density, almost constant operating temperature and stable thermochemical properties, which shows outstanding potential in the field of phase change energy storage. Nevertheless, single HD as thermal storage material inevitably faces challenges in terms of liquid phase leakage, low thermal conductivity, and poor photo-thermal conversion. To further improve the practical application of HD, we demonstrate a convenient encapsulation and modification strategy of composite phase change materials (CPCMs) with low liquid leakage and high thermal conductivity. Hence, a novel shape-stabilized Cu-doped HD/ graphitic carbon nitride (g-C3N4) CPCM was developed for efficient photo-thermal storage. By the melt blending method, HD is infiltrated into tightly stacked and aligned nano-porous g-C3N4, and the carbon-based lattice inlay achieves the encapsulation of HD to solve the leakage problem during the solid–liquid phase transition. Then, metallic Cu powder is introduced to further strengthen the thermal conductivity of the materials. With this encapsulation and modification strategy, the obtained 5 wt% Cu-doped HD/g-C3N4 composites (CPCM3) exhibits superior performance in both thermal and optical energy storage. This composite has appropriate phase change temperature and extremely high heat storage density, with melting temperature and latent heat of 48.88 °C and 249.63 J/g. The corresponding solidification temperature and latent heat is 48.52 °C and 242.22 J/g, respectively. Its thermal conductivity is enhanced to 0.5307 W/m·K, which is 59.8% higher than pure HD. The photo-thermal conversion efficiency is up to 81.6% for rapid solar energy harvesting and delivery. In particular, after 100 times thermal cycling tests and thermogravimetric analysis, this special CPCM can maintain good thermal reliability and thermal stability. In conclusion, the composite phase change materials obtained by the synergistic modification strategy of nano-porous g-C3N4 and metallic Cu significantly improved the thermochemical properties of HD. This work provides a practical and efficient synthetic strategy for the preparation of CPCMs, which is expected to present a promising future in the field of solar conversion and storage.

Analysis of liquid–solid interface bonding behaviour of 7075 aluminium alloy/SiCp reinforced aluminium base alloy

The introduction of heterogeneous elements and the presence of the oxide layer on the surface of aluminum alloy usually play a negative role in the interfacial bonding of Al/Al bimetallic composites. To solve these two key problems of interfacial bonding of bimetallic composites. This work proposes to composite SiCp/7075(solid)-7075 alloy(liquid). The main alloying element Zn of 7075 alloy is selected to perform hot dip treatment on SiCp/7075(solid) to reduce the influence of the oxide layer on the surface of the aluminum alloy and the introduction of heterogeneous elements. Al/Al bimetallic composites were prepared by using a hot-dip/non-hot-dip zinc + liquid–solid composite casting process. The bimetallic composite interfacial bonding of SiCp/7075–7075 matrix alloy was studied. The results revealed that an oxide layer existed at the interface of the bimetallic composite upon preheating at 400–475 °C and hot dipping at 400–425 °C. With an increase in the hot-dip temperature, the interface oxide layer disappeared because of the combined effect of thermal expansion deformation, lower solidus temperature of the zinc-rich layer, and volume expansion of the solid–liquid phase transition. Metallurgically bonded interfaces were obtained at the hot-dip temperatures of 450 and 475 °C. The fracture location was on the SiCp/7075 Al matrix composite side, showing that this composite's interfacial bond strength was higher than that of the SiCp/7075 Al matrix composites. The results of this study provide a new idea for the preparation of lightweight wear-resistant Al/Al bimetallic composites by liquid-solid composite casting.

Spinning Liquid Metal Droplets on Ice.

The non-contact and non-wetting droplet motion isolated from the solid surface has a high degree of freedom and thus can exhibit many peculiar interfacial phenomena. Here, an experimental phenomenon of spinning liquid metal droplets on an ice block is discovered, which adopts the dual solid-liquid phase transition of the liquid metal and the ice. The whole system is somewhat a variant of the classic Leidenfrost effect, which directly uses the latent heat released by the spontaneous solidification of the liquid metal droplet as a heat source to melt the ice and create an intervening lubricant water film. Interestingly, it is found that the droplets on ice become very mobile and undergo rapid spin as the solidification process proceeds. A series of comparative experiments clarify that the circumferential driving force comes from the escaping bubbles as the ice melts. Furthermore, by comparing the motion characteristics of different kinds of liquid metal droplets and solid balls on ice and investigating their physical properties and heat transfer, it is disclosed that the spin effect can be universal for objects of different materials, as long as the two necessary elements of rapid liquid film establishment and gas bubble release can be satisfied simultaneously.

Investigation of high-enthalpy organic phase-change materials for heat storage and thermal management

The growing interest in phase-change materials (PCM) is related to their possible role in thermal energy storage and thermal management. The choice of materials depends strongly on the required temperature range, whereas the latent heat of solid–liquid phase transition has to be as high as possible. Among other organic PCM, sugar alcohols have gained some attention due to their availability and certain advantageous properties. However, the thermal processes in these materials still require investigation. In the present work, we focused on the materials with solid–liquid phase change within 80 °C–100 °C. A comprehensive literature survey was conducted to elucidate the available sugar alcohols relevant to this range. It was found that the use of pure materials of this type is not very practical, because of their scarcity in the required range and their specific features, like difficulties with crystallization and solidification. On the other hand, based on the literature, we have discerned three eutectic mixtures of erythritol with other organic materials, namely, erythritol–xylitol, erythritol–urea and erythritol– trimethylolethane (TME). In all those cases, it is remarkable that while the components commonly have rather high melting temperatures, the eutectic mixtures had the phase transitions in the required range. Still, each of these mixtures has its own peculiar features, especially at cooling and solidification. An extensive experimental study was performed to provide detailed visualization of these major processes. The results revealed the melting temperature and latent heat of the mixtures to be: 84 °C and 190 J g−1 for erythritol–xylitol, 82 °C and 227 J g−1 for erythritol–urea. Erythritol–TME has two phase transitions at 82 °C and 97 °C, with total latent heat of 198 J g−1. Based on the present findings, the erythritol–urea mixture is the best PCM candidate for the melting range within 80 °C–100 °C.

Novel insight into the self-lubricating mechanism of Cu–Pb bearing alloy during sliding friction with the guidance of molecular dynamics

The self-lubricating mechanism of Cu–Pb bearing alloy is discussed by molecular dynamics (MD). MD friction tests are conducted on the pure Cu and Cu–Pb models. The Pb-rich secondary phases (PSPs) melt due to the frictional heat. The solid–liquid phase transition of Pb is characterized by the radial distribution function (RDF) and the potential energy. An obvious drop of motion resistance of the abrasive debris is observed in Cu–Pb alloy once the debris moves close to the soft PSP which protect the matrix from abrasion by embedding the debris and promoting the formation of a liquid lubricant film. The synchrotron radiation technology is employed to in-situ observe the phase transition of Pb, and the MD results match the experimental results well.

Zero-point motion of liquid and solid hydrogen

We present an inelastic neutron scattering study of liquid and solid hydrogen carried out using the wide Angular Range Chopper Spectrometer at Oak Ridge National Laboratory. From the observed dynamic structure factor, we obtained empirical estimates of the molecular mean-squared displacement and average translational kinetic energy. We find that the former quantity increases with temperature, indicating that a combination of thermal and quantum effects is important near the liquid-solid phase transition, contrary to previous measurements. We also find that the kinetic energy drops dramatically on melting of the crystals, a consequence of the large increase in molar volume together with the Heisenberg indeterminacy principle. Our results are compared with quantum Monte Carlo simulations based on different model potentials. In general, there is good agreement between our findings and theoretical predictions based on the Silvera-Goldman and Buck potentials.

Analysis of weak solutions of a phase-field model for sea ice evolution

This paper is devoted to the study of the well-posedness of an initial-boundary value problem (IVBP) for a three-dimensional two-phase system, which is a phase-field model consisting of two coupled parabolic equations and is used to describe the solid–liquid phase transition of sea ice growth. First, we give the derivation of this model. Then, we prove the global-in-time existence and uniqueness of the weak solutions to the IBVP by means of the Galerkin approximation argument and the energy method. In addition, we establish a maximum principle that guarantees the model is physically consistent. Finally, the regularity of weak solutions is also established.

Evaluating the transferability of machine-learned force fields for material property modeling

Machine-learned force fields have generated significant interest in recent years as a tool for molecular dynamics (MD) simulations, with the aim of developing accurate and efficient models that can replace classical interatomic potentials. However, before these models can be confidently applied to materials simulations, they must be thoroughly tested and validated. The existing tests on the radial distribution function and mean-squared displacements are insufficient in assessing the transferability of these models. Here we present a more comprehensive set of benchmarking tests for evaluating the transferability of machine-learned force fields. We use a graph neural network (GNN)-based force field coupled with the OpenMM package to carry out MD simulations for Argon as a test case. Our tests include computational X-ray photon correlation spectroscopy (XPCS) signals, which capture the density fluctuation at various length scales in the liquid phase, as well as phonon density-of-states in the solid phase and the liquid-solid phase transition behavior. Our results show that the model can accurately capture the behavior of the solid phase only when the configurations from the solid phase are included in the training dataset. This underscores the importance of appropriately selecting the training data set when developing machine-learned force fields. The tests presented in this work provide a necessary foundation for the development and application of machine-learned force fields for materials simulations.

Influence of ALS-linked M337V mutation on the conformational ensembles of TDP-43321-340 peptide monomer and dimer.

The transactive response (TAR) DNA/RNA-binding protein 43 (TDP-43) can self-assemble into both functional stress granules via liquid-liquid phase separation (LLPS) and pathogenic amyloid fibrillary aggregates that are closely linked to amyotrophic lateral sclerosis. Previous experimental studies reported that the low complexity domain (LCD) of TDP-43 plays an essential role in the LLPS and aggregation of the full-length protein, and it alone can also undergo LLPS to form liquid droplets mainly via intermolecular interactions in the 321-340 region. And the ALS-associated M337V mutation impairs LCD's LLPS and facilitates liquid-solid phase transition. However, the underlying atomistic mechanism is not well understood. Herein, as a first step to understand the M337V-caused LLPS disruption of TDP-43 LCD mediated by the 321-340 region and the fibrillization enhancement, we investigated the conformational properties of monomer/dimer of TDP-43321-340 peptide and its M337V mutant by performing extensive all-atom explicit-solvent replica exchange molecular dynamic simulations. Our simulations demonstrate that M337V mutation alters the residue regions with high helix/β-structure propensities and thus affects the conformational ensembles of both monomer and dimer. M337V mutation inhibits helix formation in the N-terminal Ala-rich region and the C-terminal mutation site region, while facilitating their long β-sheet formation, albeit with a minor impact on the average probability of both helix structure and β-structure. Further analysis of dimer system shows that M337V mutation disrupts inter-molecular helix-helix interactions and W334-W334 π-π stacking interactions which were reported to be important for the LLPS of TDP-43 LCD, whereas enhances the overall peptide residue-residue interactions and weakens peptide-water interactions, which is conducive to peptide fibrillization. This study provides mechanistic insights into the M337V-mutation-induced impairment of phase separation and facilitation of fibril formation of TDP-43 LCD.