Solid-liquid Transition Research Articles

Stable sodium-sulfur electrochemistry enabled by phosphorus-based complexation

A series of sodium phosphorothioate complexes are shown to have electrochemical properties attractive for sodium-sulfur battery applications across a wide operating temperature range. As cathode materials, they resolve a long-standing issue of cyclic liquid-solid phase transition that causes sluggish reaction kinetics and poor cycling stability in conventional, room-temperature sodium-sulfur batteries. The cathode chemistry yields 80% cyclic retention after 400 cycles at room temperature and a superior low-temperature performance down to -60 °C. Coupled experimental characterization and density functional theory calculations revealed the complex structures and electrochemical reaction mechanisms. The desirable electrochemical properties are attributed to the ability of the complexes to prevent the formation of solid precipitates over a fairly wide range of voltage.

Solid solubility extension and nano-mechanical properties of rapidly solidified Fe-Zr eutectic alloys under free fall condition

The liquid-solid phase transitions and solidified microstructures of highly undercooled Fe-Zr eutectic melts were investigated by the drop tube technique. The quantitative relationships among droplet diameter (D), undercooling (ΔT) and cooling rate (Rc) were calculated for three types of eutectic alloys (Fe-9.8 at. % Zr, Fe-6 at. % Zr and Fe-16 at. % Zr alloys). Furthermore, the evolutions of solidified microstructure with droplet diameter were studied. The results show that the eutectic microstructure for Fe-9.8 at. % Zr droplet transforms from regularly lamellar shape to anomalous shape as the diameter reduces. The α-Fe dendrite in Fe-6 at. % Zr droplet transforms from coarse dendrite to refined dendrite with the decrease of droplet diameter, while the Fe2Zr dendrite in Fe-16 at. % Zr droplet transforms from faceted dendrite to non-faceted grain. Besides, a remarkable solid solubility extension was found in both the α-Fe dendrites of Fe-6 at. % Zr alloy and the Fe2Zr dendrites of Fe-16 at. % Zr alloy. The solid solubility of the α-Fe dendrite increases from 3 at. % to 5.6 at. % when the droplet diameter reduces from 1069 to 212 µm, while it decreases from 31 to 22 at. % in the Fe2Zr dendrite as the diameter reduces from 991 to 228 µm. The microstructural morphology and solid solubility are directly related to the nano-hardness and Young’s elastic modulus of alloys. The nano-mechanical properties of the eutectic gradually increase with the refinement of the layers, and gradually decrease as the irregularity of the anomalous eutectic increases. With the reduction of droplet diameter, the nano-hardness rises and Young’s elastic modulus continuously diminishes for the α-Fe dendrite due to the increase in the solute content of Zr, while these two mechanical properties gradually decrease for the Fe2Zr dendrite because of the reduction in the solute content of Zr.

The role of TCP structures in glass formation of Ni50Ag50 alloys

A molecular dynamics simulation of rapid cooling at a cooling rate of 1011 K/s for Ni50Ag50 alloys was conducted. The rapid cooling process was analyzed by using the system energy, the pair distribution function, and the largest standard cluster analysis. It is found that with a crystallization-like energy curve the solidification of Ni50Ag50 alloy experiences a liquid-liquid and a liquid-solid transition (LLT and LST), finally result in an amorphous solid. In LLT stage the topologically close-packed (TCP) short-range order structures of both crystal (S666) and glass (S555) increase; whereas only glass medium-range order structures are formed. TCP-based long-range order (LRO) structures of glass do not increase until the beginning of the LST. Even in solid (T < Tg) the LRO parameter based on ICO structures fluctuates violently, while that based on TCP structures is quite stable. Therefore, TCP not only is the basic structural characteristics of disordered system but also reasonably represents the metastability of metallic glasses. These findings not only clarify the importance of LLT for the glass forming ability of alloys, but also fully demonstrate the effectiveness and necessity of TCP structures for describing the structure of amorphous systems.

Cover Feature: Tunable Synchronicity of Molecular Valence Tautomerism with Macroscopic Solid‐Liquid Transition by Molecular Lattice Engineering (Chem. Eur. J. 66/2021)

Changing the length of the side chains in a series of cobalt complexes changed the melting temperature and allowed the synchronicity of the valence tautomerism and solid–liquid transition to be controlled. The three complexes exhibit distinct macroscopic transitions from the crystalline phase to violet, blueish, or green liquids; this is represented in the figure by the degree of hand-holding between the two children jumping in the lavender field. More information can be found in the Full Paper by H.-C. Chang et al. (DOI: 10.1002/chem.202103090).

Earthen construction: Demonstration of feasibility at 1/2 scale of poured clay concrete construction

Poured earth construction is a very promising alternative to cement-based construction, however it requires a large increase of productivity. Poured earth concrete can meet this issue, but is currently stabilized with cement leading to a high environmental impact. One possible solution is the use of alginate, a biopolymer, to provide a transient liquid–solid transition before the wall is effectively hardened by the long process of drying. Using design experiment, the impact of four parameters (water to binder ratio, dispersant ratio, alginate ratio and level of acidifier) has been investigated on the consistency and the mechanical properties. In this study the feasibility of the use of poured earth concrete stabilized with biopolymer is demonstrated through low wall manufacturing.

Connecting short-range order for the liquid-solid transition of Al-Cu-Fe alloys

Liquid-solid transition processes have always been mysterious, especially those with the participation of quasicrystal (QC) structures, and are generally far less understood than the conventional solidification process. Here, the liquid structure variation of ternary QC-forming Al60Cu37Fe3 with crystal-forming Al50Cu40Fe10 alloy liquids was compared using synchrotron radiation based on high-energy X-ray diffraction (HE-XRD) and reverse Monte Carlo simulation (RMC). It was noted that the types of short-range order structures are almost the same in the Al60Cu37Fe3 and Al50Cu40Fe10 alloy liquids, while the former has more icosahedral short-range order (ISRO) and the latter has less. The medium-range order (MRO) was characterized by the cluster correlation method and visualization analysis. More obvious structural heterogeneity was found in the Al60Cu37Fe3 liquid, which is due to the strong correlation between clusters with high icosahedral order and the weak correlation between crystal clusters. Moreover, strongly correlated ISRO clusters can form icosahedral medium-range order (IMRO) structures by interpenetrating connections forming a stable structure upon cooling, and some other clusters can even enhance the IMRO stability. Such IMRO will be retained in the liquid upon cooling, leading to QC formation. All the findings provide a further understanding of the liquid-solid transition with ISRO participation.

Bulk rheology of sticky DNA-functionalized emulsions.

We measure by experiment and particle-based simulation the rheology of concentrated, non-Brownian droplet emulsions functionalized with surface-bound single-stranded (ss), "sticky," DNA. In the absence of ssDNA, the emulsion viscosity increases with the dispersed phase volume fraction ϕ, before passing through a liquid-solid transition at a critical ϕ_{c} related to random close packing. Introducing ssDNA leads to a liquid-solid transition at ϕ<ϕ_{c}, the onset being set by the droplet valency N and the ssDNA concentration (or simulated binding strength ε). Using insight from simulation, we identify three key behaviors: (i) jammed suspensions (ϕ>ϕ_{c}≈0.64) show weak effects of functionalization, with elastic rheology instead governed by droplet stiffness; (ii) suspensions with ϕ<ϕ_{c} and N=1, 2 always exhibit viscous rheology, regardless of functionalization; and (iii) for ϕ<ϕ_{c} and N>3, functionalization leads to a controllable viscous-elastic transition. We present state diagrams showing the range of rheological tuning attainable by these means.

Data-driven criterion for the solid-liquid transition of two-dimensional self-propelled colloidal particles far from equilibrium.

We establish an explicit data-driven criterion for identifying the solid-liquid transition of two-dimensional self-propelled colloidal particles in the far from equilibrium parameter regime, where the transition points predicted by different conventional empirical criteria for melting and freezing diverge. This is achieved by applying a hybrid machine learning approach that combines unsupervised learning with supervised learning to analyze a huge amount of the system's configurations in the nonequilibrium parameter regime on an equal footing. Furthermore, we establish a generic data-driven evaluation function, according to which the performance of different empirical criteria can be systematically evaluated and improved. In particular, by applying this evaluation function, we identify a new nonequilibrium threshold value for the long-time diffusion coefficient, based on which the predictions of the corresponding empirical criterion are greatly improved in the far from equilibrium parameter regime. These data-driven approaches provide a generic tool for investigating phase transitions in complex systems where conventional empirical ones face difficulties.

Tunable Synchronicity of Molecular Valence Tautomerism with Macroscopic Solid-Liquid Transition by Molecular Lattice Engineering.

The combination of a cobalt-dioxolene core that exhibits valence tautomerism (VT) with pyridine-3,5-dicarboxylic acid functionalized with chains bearing two, four, or six oxyethylene units led to new complexes ConEGEspy (n = 2, 4, and 6). These complexes commonly form violet crystals of the low-spin (ls)-[CoIII (nEGEspy)2 (3,6-DTBSQ)(3,6-DTBCat)] (ls-[CoIII ], 3,6-DTBSQ = 3,6-di-tert-butyl semiquinonato, 3,6-DTBCat = 3,6-di-tert-butyl catecholato). Interestingly, violet crystals of Co2EGEspy in the ls-[CoIII ] transitioned into a green liquid, accompanied by an almost complete VT shift (94 %) to the high-spin (hs)-[CoII (nEGEspy)2 (3,6-DTBSQ)2 ] (hs-[CoII ]) upon melting. In contrast, violet crystals of Co4EGEspy and Co6EGEspy in the ls-[CoIII ] exhibited partial VT (33 %) and only a 9.3 % VT shift after melting, respectively. These data demonstrate the tunability of the synchronicity of the molecular VT and macroscopic solid-liquid transitions by optimizing the tethered chains, thus establishing a new strategy for coupling bistable molecules with the macroscopic world.

Simultaneous derivatization and liquid-solid phase transition microextraction of six biogenic amines in foods followed by narrowbore liquid chromatography-ultraviolet detection

Biogenic amines are quality control criteria for foods that are potentially toxic to humans. In this study, amidation derivatization for biogenic amines and liquid–solid phase transition microextraction were carried out simultaneously for food sample pretreatment. The derivatization reaction was executed in one pot with coumarin-3-carboxylic acid as the derivatizing reagent and (1-cyano-2-ethoxy-2-oxoethylidenaminooxy)dimethylamino-morpholino-carbenium hexafluorophosphate as the coupling agent. Liquid–solid phase transition microextraction was achieved by the salting-out effect, using a phase change salt (1 M disodium hydrogen phosphate) solution. The combined derivatization and microextraction process was completed within 3 min at 30 °C, and the liquid top phase was easily obtained by placing the tube in an ice bath. Finally, a narrowbore liquid chromatograph coupled with a UV detector was used to determine the levels of six biogenic amines. The coupling agent-assisted derivatization and liquid–solid phase transition microextraction parameters were also investigated. The quantitative linear ranges were 3–400 μM for histamine, putrescine, spermidine, cadaverine, and tyramine and 5–400 μM for spermine, and the detection limit was 1 μM. The relative standard deviations of the intra- and inter-batches were <5.3% and 8.4%, respectively, while the relative error was <4.5% for both. We successfully applied this simultaneous derivatization–microextraction method to determine the biogenic amines in fermented foods.

Excess entropy and Stokes-Einstein relation in simple fluids.

The Stokes-Einstein (SE) relation between the self-diffusion and shear viscosity coefficients operates in sufficiently dense liquids not too far from the liquid-solid phase transition. By considering four simple model systems with very different pairwise interaction potentials (Lennard-Jones, Coulomb, Debye-Hückel or screened Coulomb, and the hard sphere limit) we identify where exactly on the respective phase diagrams the SE relation holds. It appears that the reduced excess entropy s_{ex} can be used as a suitable indicator of the validity of the SE relation. In all cases considered the onset of SE relation validity occurs at approximately s_{ex}≲-2. In addition, we demonstrate that the line separating gaslike and liquidlike fluid behaviours on the phase diagram is roughly characterized by s_{ex}≃-1.

ALS-linked FUS mutations dysregulate G-quadruplex-dependent liquid–liquid phase separation and liquid-to-solid transition

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the accumulation of protein aggregates in motor neurons. Recent discoveries of genetic mutations in ALS patients promoted research into the complex molecular mechanisms underlying ALS. FUS (fused in sarcoma) is a representative ALS-linked RNA-binding protein (RBP) that specifically recognizes G-quadruplex (G4)-DNA/RNAs. However, the effects of ALS-linked FUS mutations on the G4-RNA-binding activity and the phase behavior have never been investigated. Using the purified full-length FUS, we analyzed the molecular mechanisms of multidomain structures consisting of multiple functional modules that bind to G4. Here we succeeded to observe the liquid–liquid phase separation (LLPS) of FUS condensate formation and subsequent liquid-to-solid transition (LST) leading to the formation of FUS aggregates. This process was markedly promoted through FUS interaction with G4-RNA. To further investigate, we selected a total of eight representative ALS-linked FUS mutants within multidomain structures and purified these proteins. The regulation of G4-RNA-dependent LLPS and LST pathways was lost for all ALS-linked FUS mutants defective in G4-RNA recognition tested, supporting the essential role of G4-RNA in this process. Noteworthy, the P525L mutation that causes juvenile ALS exhibited the largest effect on both G4-RNA binding and FUS aggregation. The findings described herein could provide a clue to the hitherto undefined connection between protein aggregation and dysfunction of RBPs in the complex pathway of ALS pathogenesis.

Natural convection of water and nano‐emulsion phase change material inside a square enclosure to cool the electronic components

The usage of natural convection has many applications for cooling and controlling the temperature of electronic components. Therefore, in the present simulation, the average Nusselt number and maximum temperature of surface's electronic components are studied by adding nano-emulsion phase change material (NPCM) with water as the base fluid. Because, the previous studies show that adding NPCM to a base fluid can increase the specific heat capacity of a mixture in order to change the phase in the solid–liquid transition. The used NPCM consists of n-eicosane as a core and sodium lauryl sulphate as a shell. The geometry includes a square enclosure with the top wall as a cold wall and the bottom wall as a hot electronic component with constant heat flux. In the current study, the effects of Rayleigh numbers (), cold wall temperature (), and volume fraction of NPCM () are investigated to understand the behaviors of NPCM on heat transfer parameters. The observations show that the average Nusselt number is directly related to Rayleigh number and thickness of the phase change zone. Moreover, the optimal value of volume fraction is 0.012 that increases average Nusselt number 7.3% and 5.4% for low and high Rayleigh numbers, respectively.

Solid-liquid transition induced by the anisotropic diffusion of colloidal particles

We numerically study the phase behaviors of colloids with anisotropic diffusion in two dimensions. It is found that the diffusion anisotropy of colloidal particles plays an important role in the phase transitions. A strong diffusion anisotropy induces the large vibration of particles, subsequently, the system goes into a disordered state. In the presence of the strong-coupling, particles with weak diffusion anisotropy can freeze into hexagonal crystals. Thus, there exists a solid-liquid transition. With the degree of diffusion anisotropy increasing, the transition points are shifted to the stronger-coupled region. A competition between the degree of diffusion anisotropy and coupling strength widens the transition region where the heterogeneous structures coexist, which results in a broad-peak probability distribution curve for the local order parameter. Our study may be helpful for the experiments related to the phase behavior in statistical physics, materials science and biophysical systems.

Experimental evidence of the effect of aging on the yielding and pre-yielding behavior of bentonite and laponite suspensions

Thixotropic yield stress materials show a shear-induced solid-liquid transition at the yielding point, characterized by yield stress and yield strain. It is well known in the literature that the elastic modulus and the yield stress of thixotropic materials increase with aging time. In the current work, we propose a discussion on the brittleness of a suspension of swollen bentonite in water, focusing mainly on the role of aging times on the yield strain and on the critical strain at the linear to nonlinear viscoelastic transition of the material. The yield strain was measured in creep and constant shear rate start-up experiments, whereas the linear to nonlinear viscoelastic transition was evaluated from Fourier transforms on transient data in oscillatory shear stress amplitude sweeps. We show that aging increases material brittleness since the yield strain decreases with the resting time. On the other hand, the linear to nonlinear viscoelastic transition strain is surprisingly unaffected by the aging process. Other thixotropic systems were also investigated: 8 and 10 wt. % suspensions of bentonite in water and a 2 wt. % suspension of Laponite® in tap water. These lead to similar observations, showing constant linear to nonlinear viscoelastic strains and decreasing yield strains over increasing aging times. These findings bring relevant information to the intricate open-discussion issue on how to describe the behavior of thixotropic materials below the yield stress.

Melting of two-dimensional biological tissues containing active Ornstein–Uhlenbeck cells

The solid–liquid transition of biological tissues is numerically investigated in the presence of Ornstein–Uhlenbeck noise. We demonstrate that the melting scenario of the system is controlled by three parameters: temperature, the persistence time that controls the nonequilibrium properties of the system, and the target shape index that characterizes the competition between cell–cell adhesion and cortical tension. An increase in the persistence time always causes the system to transition from disordered (liquid state) to ordered (solid state). For stiff cells (small target shape index), on increasing temperature, the system undergoes the first order melting for short persistence time, while it undergoes a continuous solid–hexatic transition followed by a discontinuous hexatic–liquid transition for long persistence time. For soft cells (large target shape index), the melting always occurs via a continuous solid–hexatic transition followed by a discontinuous hexatic–liquid transition and the parameter range where the hexatic phase occurs increases with the persistence time. These behaviors are confirmed by the evolution of the density of topological defects. The phase diagrams of the system are also presented based on three parameters (temperature, the shape index, and the persistence time). Our study may contribute to the understanding of melting in two dimensional systems with many-body interactions and deformable particles.

Low-latitude forcing: A new insight into paleo-climate changes

Low-latitude forcing: A new insight into paleo-climate changes

Synthesis and properties of high thermal conductivity Ag shell-coated phase change materials

Phase change micro/nanocapsules with high thermal conductivity shells have extensive application prospects in solar energy storage systems and electronics cooling. To improve the heat transfer of the capsules, a method of preparing Ag-shell coated phase change micro/nanocapsules was developed, where the AgBr ultrafine solid particles are introduced to enhance the rigidity of emulsion droplets in the liquid-solid phase transition process, and by employing hydroquinone as the reductant to repeatedly reduce the AgBr that had been adhered to the surface of the emulsion droplets, an Ag shell is formed on the surface of the cores. In this work, palmitic acid (PA) is used as the core material, and the prepared PA/Ag nanocapsules (100–600 nm) exhibit high thermal storage capability and good thermal reliability. The bulk thermal conductivity of the nanocapsules can be as high as 4.072 W/(m·K), indicating that the Ag shell can effectively improve the thermal conductivity of the nanocapsules. Besides, the thermal response of the nanocapsules is estimated by simulating a single-particle heat transfer process considering nanoscale effects, and the results demonstrate that the thermal response time of PA/Ag nanocapsule (350 nm) in working fluid (water, 80 °C) could be as short as 150ns.

Sustainable lignin‐based polyols as promising thermal energy storage materials

AbstractSix lignin‐based polyols (LBPs) have been prepared by cationic ring opening polymerization of an oxirane in the presence of an organosolv lignin in tetrahydrofuran (THF) as reaction media and co‐monomer. The prepared LBPs have been characterized and tested for the first time as phase change materials (PCMs) for thermal energy storage (TES) at low temperature. It was found a strong influence of the LBPs composition on their performance to storage thermal energy. Thus, LBPs with higher THF wt% content and lower oxirane/THF mass ratio exhibit the highest latent heats. Furthermore, a clear inversely proportional trend between the oxirane/THF mass ratio and the melting temperatures of the prepared LBPs was noticed. Among the prepared LBPs, the highest obtained latent heat was 53.7 J/g demonstrating the potential application of lignin as feedstock for PCMs preparation. To the best of our knowledge, this is the first time that a biomass derived PCM based on lignin has been studied and considered for TES applications at low temperature. LBPs show energetic solid–liquid transitions that point out their promising potential as bio‐PCMs. This work paves the way to introduce new bio‐based PCMs from lignin in TES systems, for example, in a more sustainable construction sector.

Nanoclay Suspension-Enabled Extrusion Bioprinting of Three-Dimensional Soft Structures

Abstract Three-dimensional (3D) extrusion printing of cellular/acellular structures with biocompatible materials has been widely investigated in recent years. However, the requirement of a suitable solidification rate of printable ink materials constrains the utilization of extrusion-based 3D printing techniques. In this study, the nanoclay yield-stress suspension-enabled extrusion-based 3D printing system has been investigated and demonstrated to overcome solidification rate constraints during printing. Utilizing the liquid–solid transition property of nanoclay suspension, two fabrication approaches, including nanoclay support bath-enabled printing and nanoclay-enabled direct printing, have been proposed. For the former approach, nanoclay (Laponite® EP) has been used as a support bath material to fabricate alginate-based tympanic membrane patches. The constituents of alginate-based ink have been investigated to have the desired mechanical property of alginate-based tympanic membrane patches and facilitate the printing process. For the latter approach, nanoclay (Laponite® XLG) has been used as an internal scaffold material to help print poly (ethylene glycol) diacrylate (PEGDA)-based neural chambers, which can be further cross-linked in air. Mechanical stress analysis has been performed to explore the geometric limitation of printable Laponite® XLG-PEGDA neural chambers.