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The depth dependence of structural relaxation dynamics is a key part of understanding thin glassy films. Despite this importance and decades of research, a method to provide this information has proved elusive. We measure the isothermal rejuvenation of stable glass films of poly(styrene), and demonstrate that the propagation of the front responsible for the transformation to a supercooled-liquid state serves as a highly localized probe of the local dynamics of the supercooled liquid. We use this connection to probe the depth-dependent relaxation rate with nanometric precision for a series of polystyrene films over a range of temperatures near the bulk glass transition temperature. The analysis shows the spatial extent of enhanced surface mobility and reveals the existence of an unexpected large dynamical length scale in the system. The results are compared with the cooperative-string model for glassy dynamics. The data reveals that the film-thickness dependence of whole film properties arises mainly from the volume fraction of the near-surface region. While the dynamics farthest from the free surface shows the expected bulk-like temperature dependence, the dynamics in the near-surface region shows very little dependence on temperature. This technique can be used in a broad range of thin film materials to gain previously unattainable information about localized structural relaxation. Measurements of depth dependent dynamics are a critical, and so far unattained, component of understanding the properties of thin glassy films. The authors describe the use of rejuvenation of stable glasses to achieve this goal, and apply it to the case of polystyrene glass. [ABSTRACT FROM AUTHOR]

Soft glassy materials experience a significant reduction in viscosity η when subjected to shear flow, known as shear thinning. This phenomenon is characterized by a power-law scaling of η with the shear rate γ ° , η ∝ γ ° − ν , where the exponent ν is typically around 0.7 to 0.8 across different materials. Two decades ago, the mode-coupling theory (MCT) suggested that shear thinning occurs due to the advection. However, it predicts too large ν = 1 (> 0.7 to 0.8) and overestimates the onset shear rate by orders of magnitude. Recently, it was claimed that a minute distortion of the particle configuration is responsible for shear thinning. Here we extend the MCT to include the distortion, and find that both advection and distortion contribute to shear thinning, but the latter is dominant. Our formulation works quantitatively for several different glass formers. We explain why shear thinning is universal for many glassy materials. Despite the importance of shear-thinning rheology which many glassy materials universally experience under shear flow, significant discrepancies between theoretical explanations and experimental observations have remained unaddressed for over two decades. Here the authors renovate the theory to address these discrepancies and establish a universal mechanism of shear thinning. [ABSTRACT FROM AUTHOR]

The supercooled liquid fraction (SLF) in mixed-phase clouds (MPCs) is an essential variable of cloud microphysical processes and climate sensitivity. However, the SLF is currently calculated in spaceborne remote sensing only as the cloud phase–frequency ratio of adjacent pixels, which results in a loss of the original resolution in observations of cloud liquid or ice content within MPCs. Here, we present a novel method for retrieving the SLF in MPCs based on the differences in radiative properties of supercooled liquid droplets and ice particles at visible (VIS) and shortwave infrared (SWI) channels of the geostationary Himawari-8. Liquid and ice water paths are inferred by assuming that clouds are composed of only liquid or ice, with the real cloud water path (CWP) expressed as a combination of these two water paths (SLF and 1-SLF as coefficients), and the SLF is determined by referring to the CWP from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). The statistically relatively small cloud phase spatial inhomogeneity at a Himawari-8 pixel level indicates an optimal scene for cloud retrieval. The SLF results are comparable to global SLF distributions observed by active instruments, particularly for single-layered cloud systems. While accessing the method's feasibility, SLF averages are estimated between 74 % and 78 % in Southern Ocean (SO) stratocumulus across seasons, contrasting with a range of 29 % to 32 % in northeastern Asia. The former exhibits a minimum SLF around midday in summer and a maximum in winter, while the latter trend differs. This novel algorithm will be valuable for research to track the evolution of MPCs and constrain the related climate impact. [ABSTRACT FROM AUTHOR]

Current models estimate global aviation contributes approximately 5% to the total anthropogenic climate forcing, with aerosol‐cloud interactions having the greatest effect. However, radiative forcing estimates from aviation aerosol‐cloud interactions remain undetermined. There is an expected significant increase in aircraft emissions with aviation demand expected to rise by over 4% per year. Soot may play an important role in the ice nucleation of aircraft‐induced cirrus formation due to a high emission rate, but the ice nucleating properties are poorly constrained. Understanding the microphysical processes leading to atmospheric ice crystal formation is crucial for the reliable parameterization of aerosol‐cloud interactions in climate models due to their impact on precipitation and cloud radiative properties. Ice nucleation of aircraft‐emitted soot is potentially affected by particle morphology with condensation of supercooled water occurring in pores followed by ice nucleation. However, soot has heterogeneous properties and undergoes atmospheric aging and oxidation that could change surface properties and contribute to complex ice nucleation processes. This review synthesizes current knowledge of ice nucleation catalyzed by aviation in the cirrus regime and its effects on global radiative forcing. Further research is required to determine the ice nucleation and microphysical processes of cirrus cloud formation from aviation emissions in both controlled laboratory and field investigations to inform models for more accurate climate predictions and to provide efficient mitigation strategies. Plain Language Summary: Aerosol particles can facilitate ice crystal formation in clouds that affect Earth's precipitation and climate by altering the amount of sunlight that clouds reflect and is absorbed by Earth. Human‐induced pollution may affect atmospheric ice nucleation, such as black carbon (soot) from aircraft emissions. It has been known for decades that carbon dioxide is a major greenhouse gas emitted from aircraft that significantly warms Earth's surface, but the climate effects of aerosol‐cloud interactions are still largely unknown. An understanding of what aerosol particles in the atmosphere contribute to ice nucleation is needed to better predict how they will affect future climate. This review summarizes what we currently know about ice nucleation processes from aircraft soot emissions and identifies future research priorities to understand human‐induced ice cloud formation to better predict how it may affect global climate. Key Points: Ice nucleation is a current major uncertainty in predicting future climate from aerosol‐cloud interactionsThis review synthesizes the current state of knowledge on ice nucleation from anthropogenic aircraft emissionsFuture research includes direct observations and laboratory measurements of ice nucleation microphysical processes from aircraft emissions [ABSTRACT FROM AUTHOR]

In supercooled liquids, dynamical facilitation refers to a phenomenon where microscopic motion begets further motion nearby, resulting in spatially heterogeneous dynamics. This is central to the glassy relaxation dynamics of such liquids, which show super-Arrhenius growth of relaxation timescales with decreasing temperature. Despite the importance of dynamical facilitation, there is no theoretical understanding of how facilitation emerges and impacts relaxation dynamics. Here, we present a theory that explains the microscopic origins of dynamical facilitation. We show that dynamics proceeds by localized bond-exchange events, also known as excitations, resulting in the accumulation of elastic stresses with which new excitations can interact. At low temperatures, these elastic interactions dominate and facilitate the creation of new excitations near prior excitations. Using the theory of linear elasticity and Markov processes, we simulate a model, which reproduces multiple aspects of glassy dynamics observed in experiments and molecular simulations, including the stretched exponential decay of relaxation functions, the super-Arrhenius behavior of relaxation timescales as well as their two-dimensional finite-size effects. The model also predicts the subdiffusive behavior of the mean squared displacement (MSD) on short, intermediate timescales. Furthermore, we derive the phonon contributions to diffusion and relaxation, which when combined with the excitation contributions produce the two-step relaxation processes, and the ballistic-subdiffusive-diffusive crossoverMSDbehaviors commonly found in supercooled liquids. [ABSTRACT FROM AUTHOR]

A thorough understanding of droplet impact and freezing is vital in preventing ice accretion on many outdoor devices. This simulation-based study investigated the effect of surface morphology on the impacting-freezing process of a supercooled droplet. Also, the variations of Weber number and supercooling temperature were studied numerically. The droplet impact and freezing process were simulated with the volume of fluid method and freezing model. A more accurate simulation was achieved by modeling the supercooled droplet and the dynamic contact angle. At the given ranges of the input parameters, the main factors that guaranteed droplet rebounding after collision were determined. The supercooling temperature and the groove width should be above 266 K and less than 0.21 mm, respectively. The droplet should also maintain its cohesion and integrity during impact. Creating grooves on a surface is novel and paves a new way to understand the impact and solidification of water droplets in supercooled conditions. [ABSTRACT FROM AUTHOR]

A new thermodynamic assessment of the Co–Ti system is presented on the basis of the literature data concerning phase equilibria and thermodynamics. A set of parameters of Gibbs-energy expressions for phases is obtained by means of CALPHAD approach. Excess Gibbs energy of fcc, bcc, and hcp disordered solutions is modeled using Redlich-Kister polynomials. The thermodynamic properties of liquid alloys are described using the associate solution model. Compound Energy Formalism is used to describe the thermodynamic properties of Laves C15 and C36 phases and order-disorder transformations L12-A1 and B2-A2 by applying of the corresponding two-sublattice models. The CoTi2 compound is treated as stoichiometric. The phase diagram, coordinates of invariant equilibria, and thermodynamic properties of liquid and solid phases are calculated. Metastable phase transformations with the participation of supercooled liquid alloys and boundary solid solutions are analyzed. [ABSTRACT FROM AUTHOR]

The hybrid structure of liquid metal units and organic elastomer has huge potential in achieving stretchable and reversible stiffness regulation, while such tuning is often restrained by high energy consumption for liquid metal solidification. Here, we conceive to solve the above challenge through introducing the fully leveraging interaction between supercooled liquid metal and homocrystal seeds within silicone elastomer. It is disclosed that the supercooled liquid metal-elastomer can maintain an extremely stable soft state until the supercooling is eliminated by modulating the mechanical force and elastomer deformation. This circumvents the utilization of intricate refrigeration equipment and offers a highly efficient and concise strategy for stiffness regulation. Moreover, conceptual experiments were performed to demonstrate the practical values of this technology through designing and testing the new shape memory materials, temperature-sensitive switches, and controlled circuits. The solidification mechanisms of supercooled Ga triggered by homocrystal seeds were interpreted. Overall, the present finding has generalized purposes and holds promise to significantly extend the theoretical and technological categories of classical stiffness tunable materials. [ABSTRACT FROM AUTHOR]

Understanding the mechanism of metal solidification holds both theoretical significance and practical importance. In this study, we conducted molecular dynamics simulations to investigate the impact of cooling rates on the solidification of a melted ruthenium alloy using the embedded atom method (EAM) potential. The EAM potential is a widely employed interatomic potential for describing the metallic system, which can capture numerous crucial properties, including mechanical properties, the energy of competing crystal structure dynamics, defects, and liquid structures. Our simulations showed that upon quenching with different cooling rates, the system transformed into a supercooled liquid state at 1200 K, and a hexagonal close-packed cluster emerged as a dominant structure that remained stable even in the supercooled state. A critical cooling rate (1011 K/s) marked the transition from crystal to amorphous phase; this transition exhibited an upward trend as the superheating temperature increased until it reached the maximum achievable cooling rate. Our simulations also revealed that the optimal conditions for undercooling and superheating occur at ∼0.4396 and 1.2893 Tm, respectively, where Tm is the melting temperature. Our results provide comprehensive insights into the evolution of melt structures with changing temperatures during deep undercooling, the formation of homogeneous melt-free crystal regions, and the effect of the molten state on solidification phenomena. [ABSTRACT FROM AUTHOR]

Amorphous alloys possess increased mechanical strength. Currently, the processing and shaping of amorphous alloys employ their superplasticity in the supercooled liquid phase, which has pushed research into the evolution behavior of the supercooled liquid area during the processing of amorphous alloys. In this study, a molecular dynamics technique was applied to analyze the development rules of the supercooled liquid area and the "shear transformation zone" during laser-assisted scratching of Cu50Zr50 amorphous alloy. It was discovered through research on temperature fluctuations that laser irradiation raises the temperature of the processing region, and the formation of the supercooled liquid region moves the characteristic point of material removal to an earlier stage. As the local temperature rises, the distribution of the supercooled liquid region changes from dispersed to an angle of about 30° with regard to the scratching direction, and the angle subsequently decreases. The variable laws of the "shear transformation zone" during the scratching process were explored based on the von Mises strain theory. The findings demonstrate that when laser energy rises, the Newtonian layer warms up and the "shear transformation zone" distribution angle gradually decreases. At 20 eV/ps, the angle between the "shear transformation zone" and the scratching direction achieves its smallest value of 33°, resulting in the largest overlap with the supercooled liquid region and the lowest content of the "shear transformation zone". By constructing a mathematical model for material removal efficiency, it was established that energy in the range of 20 eV/ps to 30 eV/ps demonstrates higher removal efficiency and a steady processing process while reducing surface roughness by 6-7%. [ABSTRACT FROM AUTHOR]

We review recent work on Ising-like models with "compressible cells" of fluctuating volume that, as such, are naturally treated in N p T and μ p T ensembles. Besides volumetric phenomena, local entropic effects crucially underlie the models. We focus on "compressible cell gases" (CCG), namely, lattice gases with fluctuating cell volumes, and "compressible cell liquids" (CCL) with singly occupied cells and fluctuating cell volumes. CCGs contemplate singular diameters and "Yang–Yang features" predicted by the "complete scaling" formulation of asymmetric fluid criticality, with a specific version incorporating "ice-like" hydrogen bonding further describing the "singularity-free scenario" for the low-temperature unusual thermodynamics of supercooled water. In turn, suitable CCL variants constitute adequate prototypes of water-like liquid–liquid criticality and the freezing transition of a system of hard spheres. On incorporating vacant cells to such two-state CCL variants, one obtains three-state, BEG-like models providing a satisfactory description of water's "second-critical-point scenario" and the whole phase behavior of a simple substance like argon. Future challenges comprise water's crystal–fluid phase behavior and metastable states. [ABSTRACT FROM AUTHOR]

Liquid–liquid transitions are present in a variety of substances. However, investigating the liquid–liquid transitions occurring in a supercooled liquid is difficult because of the interference from rapid crystallization. Here, we report a strong-to-fragile transition in a Pd32Ni52P16 metallic glass-forming supercooled liquid associated with a liquid–liquid transition. Since the liquid–liquid transition takes place at temperatures smaller than the crystallization temperature, the liquid viscosity can be acquired by creep experiments conducted at temperatures close to the glass transition temperature without interference from crystallization. The strong-to-fragile transition results in a 37% increase of the fragility index and a 56% elongation after thermal-plastic processing. An investigation on the loss-modulus peaks by a dynamic mechanical analyzer implies that the enhanced thermal plasticity is contributed by both glass transition and strong-to-fragile transition. This work highlights how liquid–liquid transition affects liquid fragility and how it may aid the thermal-plastic processing of metallic glass. [ABSTRACT FROM AUTHOR]

Until quite recently, in almost all papers on crystal nucleation in glass-forming substances, it was assumed that nucleation proceeds in a completely relaxed supercooled liquid and, hence, at constant values of the critical parameters determining the nucleation rate for any given set of temperature, pressure, and composition. Here, we analyze the validity of this hypothesis for a model system by studying nucleation in a lithium silicate glass treated for very long times (up to 250 days) in deeply supercooled states, reaching 60 K below the laboratory glass transition temperature, Tg. At all temperatures in the considered range, T < Tg, we observed an enormous difference between the experimental number of nucleated crystals, N(t), and its theoretically expected value computed by assuming the metastable state of the relaxing glass has been reached. Analyzing the origin of this discrepancy, we confirmed that the key parameters determining the nucleation rates change with time as a result of the glass relaxation process. Finally, we demonstrate that, for temperatures below 683 K, this particular glass almost fully crystallizes prior to reaching the ultimate steady-state nucleation regime (e.g., at 663 K, it would take 176 years for the glass to reach 99% crystallization, while 2600 years would be needed for complete relaxation). This comprehensive study proves that structural relaxation strongly affects crystal nucleation in deeply supercooled states at temperatures well below Tg; hence, this phenomenon has to be accounted for in any crystal nucleation model. [ABSTRACT FROM AUTHOR]

Until quite recently, in almost all papers on crystal nucleation in glass-forming substances, it was assumed that nucleation proceeds in a completely relaxed supercooled liquid and, hence, at constant values of the critical parameters determining the nucleation rate for any given set of temperature, pressure, and composition. Here, we analyze the validity of this hypothesis for a model system by studying nucleation in a lithium silicate glass treated for very long times (up to 250 days) in deeply supercooled states, reaching 60 K below the laboratory glass transition temperature, Tg. At all temperatures in the considered range, T < Tg, we observed an enormous difference between the experimental number of nucleated crystals, N(t), and its theoretically expected value computed by assuming the metastable state of the relaxing glass has been reached. Analyzing the origin of this discrepancy, we confirmed that the key parameters determining the nucleation rates change with time as a result of the glass relaxation process. Finally, we demonstrate that, for temperatures below 683 K, this particular glass almost fully crystallizes prior to reaching the ultimate steady-state nucleation regime (e.g., at 663 K, it would take 176 years for the glass to reach 99% crystallization, while 2600 years would be needed for complete relaxation). This comprehensive study proves that structural relaxation strongly affects crystal nucleation in deeply supercooled states at temperatures well below Tg; hence, this phenomenon has to be accounted for in any crystal nucleation model. [ABSTRACT FROM AUTHOR]

We investigate the properties of water along the liquid/vapor coexistence line in the supercooled regime down to the no-man's land. Extensive molecular dynamics simulations of the TIP4P/2005 liquid/vapor interface in the range 198–348 K allow us to locate the second surface tension inflection point with a high accuracy at 283 ± 5 K, close to the temperature of maximum density. This temperature also coincides with the appearance of a density anomaly at the interface known as the apophysis. We relate the emergence of the apophysis to the observation of high-density liquid (HDL) water adsorption in the proximity of the liquid/vapor interface. [ABSTRACT FROM AUTHOR]

Many phase change materials (PCMs) are found to crystallize without exhibiting a glass transition endotherm upon reheating. In this paper, we review experimental evidence revealing that these PCMs and likely other hyperquenched molecular and metallic systems can crystallize from the glassy state when reheated at a standard rate. Among these evidences, PCMs annealed below the glass transition temperature Tg exhibit slower crystallization kinetics despite an increase in the number of sub-critical nuclei that should promote the crystallization speed. Flash calorimetry uncovers the glass transition endotherm hidden by crystallization and reveals a distinct change in kinetics when crystallization switches from the glassy to the supercooled liquid state. The resulting Tg value also rationalizes the presence of the pre-Tg relaxation exotherm ubiquitous of hyperquenched systems. Finally, the shift in crystallization temperature during annealing exhibits a non-exponential decay that is characteristic of structural relaxation in the glass. Modeling using a modified Turnbull equation for nucleation rate supports the existence of sub-Tg fast crystallization and emphasizes the benefit of a fragile-to-strong transition for PCM applications due to a reduction in crystallization at low temperature (improved data retention) and increasing its speed at high temperature (faster computing). [ABSTRACT FROM AUTHOR]

Clotrimazole (CMZ) is a classical antifungal drug for studying crystallization. In this study, a new CMZ polymorph (Form 2) was discovered during the process of nucleation and growth rate determination in the melt. High-quality single crystals were grown from melt microdroplets to determine the crystal structure by x-ray diffraction. Form 2 is metastable and exhibits a disordered structure. The crystal nucleation and growth kinetics of the two CMZ polymorphs were systematically measured. Form 2 nucleates and grows faster than the existing form (Form 1). The maximum nucleation rate of Forms 1 and 2 was observed at 50 °C (1.07 Tg). The summary of the maximum nucleation rate temperature of CMZ and the other six organic compounds indicates that nucleation near Tg in the supercooled liquid is a useful approach to discovering new polymorphs. This study is relevant for the discovering new drug polymorphs through an understanding of nucleation and growth kinetics during melt crystallization. [ABSTRACT FROM AUTHOR]

Physical aging and structural recovery are the processes with which the structure of a system approaches equilibrium after some perturbation. Various methods exist, that initiate structural recovery, such as changing the temperature or applying a strong, external static field. This work is concerned with high alternating electric fields and their suitability to study structural recovery and aging. The present work demonstrates that rationalizing the nonlinear dielectric response of a supercooled liquid to high-amplitude ac-fields requires multiple fictive temperatures. This feature is in stark contrast to structural recovery after a temperature down-jump or a considerable increase in the static electric field, for which a single parameter, the fictive temperature or material time, describes the structural change. In other words, the structural recovery from a high ac-field does not adhere to time aging–time superposition, which is so characteristic of genuine aging processes. [ABSTRACT FROM AUTHOR]

The first paper of this series [J. Chem. Phys. 158, 034103 (2023)] demonstrated that excess entropy scaling holds for both fine-grained and corresponding coarse-grained (CG) systems. Despite its universality, a more exact determination of the scaling relationship was not possible due to the semi-empirical nature. In this second paper, an analytical excess entropy scaling relation is derived for bottom-up CG systems. At the single-site CG resolution, effective hard sphere systems are constructed that yield near-identical dynamical properties as the target CG systems by taking advantage of how hard sphere dynamics and excess entropy can be analytically expressed in terms of the liquid packing fraction. Inspired by classical equilibrium perturbation theories and recent advances in constructing hard sphere models for predicting activated dynamics of supercooled liquids, we propose a new approach for understanding the diffusion of molecular liquids in the normal regime using hard sphere reference fluids. The proposed "fluctuation matching" is designed to have the same amplitude of long wavelength density fluctuations (dimensionless compressibility) as the CG system. Utilizing the Enskog theory to derive an expression for hard sphere diffusion coefficients, a bridge between the CG dynamics and excess entropy is then established. The CG diffusion coefficient can be roughly estimated using various equations of the state, and an accurate prediction of accelerated CG dynamics at different temperatures is also possible in advance of running any CG simulation. By introducing another layer of coarsening, these findings provide a more rigorous method to assess excess entropy scaling and understand the accelerated CG dynamics of molecular fluids. [ABSTRACT FROM AUTHOR]

Currently, there is a debate whether the structural relaxation of polar liquids is more faithfully reflected (i) by the generically shaped response detected by dynamic light scattering or rather (ii) by the slower, more stretched, system-dependent susceptibility response recorded by dielectric spectroscopy. In this work, nonlinearly induced transients probing structural relaxation reveal that near the glass transition, alternative (ii) is appropriate for propylene glycol. Results from shear rheology and from calorimetry corroborate this finding, underscoring the previously advanced notion (Moch et al., Phys. Rev. Lett. 128, 228001, 2022) that the reorientationally probed structural susceptibility of viscous liquids displays a nongeneric spectral shape. [ABSTRACT FROM AUTHOR]

We consider unsupervised learning methods for characterizing the disordered microscopic structure of supercooled liquids and glasses. Specifically, we perform dimensionality reduction of smooth structural descriptors that describe radial and bond-orientational correlations and assess the ability of the method to grasp the essential structural features of glassy binary mixtures. In several cases, a few collective variables account for the bulk of the structural fluctuations within the first coordination shell and also display a clear connection with the fluctuations of particle mobility. Fine-grained descriptors that characterize the radial dependence of bond-orientational order better capture the structural fluctuations relevant for particle mobility but are also more difficult to parameterize and to interpret. We also find that principal component analysis of bond-orientational order parameters provides identical results to neural network autoencoders while having the advantage of being easily interpretable. Overall, our results indicate that glassy binary mixtures have a broad spectrum of structural features. In the temperature range we investigate, some mixtures display well-defined locally favored structures, which are reflected in bimodal distributions of the structural variables identified by dimensionality reduction. [ABSTRACT FROM AUTHOR]

A fundamental and much-debated issue in glass science is the existence and nature of liquid–liquid transitions in glass-forming liquids. Here, we report the existence of a novel reentrant structural transition in a S-rich arsenic sulfide liquid of composition As2.5S97.5. The nature of this transition and its effect on viscosity are investigated in situ using a combination of differential scanning calorimetry and simultaneous Raman spectroscopic and rheometric measurements. The results indicate that, upon heating significantly above its glass transition temperature (261 K), the constituent S n sulfur chains in the structure of the supercooled liquid first undergo a S n ⇌ S 8 chain-to-ring conversion near ∼383 K, which is exothermic in nature. Further heating above 393 K alters the equilibrium to shift in the opposite direction toward an endothermic ring-to-chain conversion characteristic of the well-known λ-transition in pure sulfur liquid. This behavior is attributed to the competing effects of enthalpy of mixing and conformational entropy of ring and chain elements in the liquid. The existence of reentrant structural transitions in glass-forming liquids could provide important insights into the thermodynamics of liquid–liquid transitions and may have important consequences for harnessing novel functionalities of derived glasses. [ABSTRACT FROM AUTHOR]

Individual heat treatments on bulk Pd40Ni40P20 metallic glass samples were performed in a differential scanning calorimeter to either activate mainly β or both α and β relaxation processes as well as heating into the supercooled liquid. The medium-range order of the final amorphous structure was investigated by fluctuation electron microscopy and compared with that of the as-cast state. The results indicate that first, a defined structural reset was achieved by heating into the supercooled liquid. Second, the annealed states exhibit a lower volume fraction of medium-range order, and third, the strain is increased due to the reduction of excess volume after annealing. [ABSTRACT FROM AUTHOR]

Which phenomenon slows down the dynamics in supercooled liquids and turns them into glasses is a long-standing question of condensed matter. Most popular theories posit that as the temperature decreases, many events must occur in a coordinated fashion on a growing length scale for relaxation to occur. Instead, other approaches consider that local barriers associated with the elementary rearrangement of a few particles or "excitations" govern the dynamics. To resolve this conundrum, our central result is to introduce an algorithm, Systematic Excitation ExtRaction, which can systematically extract hundreds of excitations and their energy from any given configuration. We also provide a measurement of the activation energy, characterizing the liquid dynamics, based on fast quenching and reheating. We use these two methods in a popular liquid model of polydisperse particles. Such polydisperse models are known to capture the hallmarks of the glass transition and can be equilibrated efficiently up to millisecond time scales. The analysis reveals that cooperative effects do not control the fragility of such liquids: the change of energy of local barriers determines the change of activation energy. More generally, these methods can now be used to measure the degree of cooperativity of any liquid model. [ABSTRACT FROM AUTHOR]

Significant variability in climate predictions originates from the simulated cloud cover over the Southern Ocean. Historically, Southern Ocean cloud and aerosol properties have been less studied than their northern hemisphere counterparts, and cloud‐sea‐ice interactions over the Southern Ocean also remain largely unexamined. We used data from combined radar, lidar, radiometer, radiosonde, and ERA5 reanalysis profiles to investigate cloud property relationships to cloud temperature, sea‐ice concentration, and boundary layer stability. Our findings show correlations between both cloud macrophysical properties and radiative effects and sea‐ice concentration, and that the marine atmospheric boundary layer is more stable over higher sea‐ice concentrations. Mixed‐phase cloud frequency of occurrence was highest over the sea‐ice zone at 15%, three times higher than over cold water south of the Antarctic Polar Front. For temperatures greater than −15°C, low‐level, single‐layer clouds were more likely to precipitate ice if they were coupled to cold‐water or sea‐ice surfaces than if they were decoupled from these surfaces, with the highest percentage of clouds precipitating ice observed over sea ice. These findings suggest a surface source of ice‐nucleating particles at high southern latitudes that increases cloud glaciation probability. We discuss the implications of our results for future studies into the relationship between cloud properties, aerosols, sea ice, and boundary layer stability at high latitudes over the Southern Ocean. Plain Language Summary: The atmosphere above the Southern Ocean remains difficult for most modern climate models to simulate well. Clouds containing liquid water below 0°C, also known as supercooled liquid water, are likely responsible for much of the simulation difficulties. In this study we investigated observations of the atmosphere made by several different instruments during a shipborne campaign from 2017 to 2018, as well as satellite observations of sea ice. We found that clouds containing supercooled liquid water were more likely to occur above sea ice than above open ocean at high latitudes, and that the lowest layer of the atmosphere is more stable above sea ice than above open ocean. We also found that, over sea ice, clouds containing supercooled liquid water were less likely to contain and precipitate ice when these clouds were separated from the lowest layer of the atmosphere. Key Points: Colder, drier air over Antarctic sea ice is associated with increased inversion strength and stability of the atmospheric boundary layerThe prevalence of mixed‐phase clouds at high southerly latitudes is greatest over sea iceFor temperatures greater than −10°C, clouds coupled to the surface are more likely to contain ice [ABSTRACT FROM AUTHOR]

Multi-stimulus responsive soft materials with integrated functionalities are elementary blocks for building soft intelligent systems, but their rational design remains challenging. Here, we demonstrate an intelligent soft architecture sensitized by magnetized liquid metal droplets that are dispersed in a highly stretchable elastomer network. The supercooled liquid metal droplets serve as microscopic latent heat reservoirs, and their controllable solidification releases localized thermal energy/information flows for enabling programmable visualization and display. This allows the perception of a variety of information-encoded contact (mechanical pressing, stretching, and torsion) and noncontact (magnetic field) stimuli as well as the visualization of dynamic phase transition and stress evolution processes, via thermal and/or thermochromic imaging. The liquid metal-elastomer architecture offers a generic platform for designing soft intelligent sensing, display, and information encryption systems. [ABSTRACT FROM AUTHOR]

Phase‐change materials (PCMs) are an important family of alloys employed in non‐volatile memories and neuromorphic devices. These devices exploit the ability of PCMs to undergo rapid transitions between amorphous and crystalline phases at moderately high temperature. At ambient conditions, both phases are stable. These properties imply a very strong temperature dependence of the crystallization kinetics, which has been attributed to the high fragility of the supercooled liquid phase. In this work, the fragility index of GeTe, an important PCM, is extracted from a computational exploration of the potential energy landscape of the system by molecular dynamics simulations. For this purpose, a neural‐network potential is used to describe the interatomic interactions, which enables the evaluation of the configurational entropy in the deeply supercooled regime. The viscosity and the relaxation times are also calculated in the same temperature range. Finally, the Adam‐Gibbs relation is used to extrapolate the data to low temperatures and estimate the glass transition temperature and the fragility index. The latter quantity turns out to be of the order of 135–140, which shows that liquid GeTe is a highly fragile system. [ABSTRACT FROM AUTHOR]

Under mechanical stimulation, a copper(I) complex in its supercooled liquid state transforms into a crystalline phase, showing a dramatic emission color change from red to green that is accompanied by a 20-fold increase in the photoluminescence quantum yield up to 87%. This reversible phase transition relies on the intriguing ability of this copper complex to form a supercooled metastable state. [ABSTRACT FROM AUTHOR]

A review of the author's works proving the existence of the phenomenon of the electrochemical phase formation in metals and alloys via a supercooled liquid state stage is presented. This review presents all the stages of establishing the above phenomenon in chronological order, as well as examples of its scientific and practical application. The theoretical prediction of the phenomenon, its experimental observation, theoretical substantiation, and some experimental proofs confirming its existence are considered in detail. The mechanism and thermodynamic model of crystallographic texture formation in electrochemical coatings, developed on the basis of the concepts of the phase formation in electrodepositing metals/alloys, taking into account the intermediate stage of the supercooled liquid state, are discussed. Some areas of the practical application of the phenomenon in basic industries (metallurgy, power engineering, and space engineering), concerning the development of the technologies for obtaining electrochemical films/coatings/foils with enhanced properties, are presented. [ABSTRACT FROM AUTHOR]

The paradigmatic view on the transformation of a supercooled liquid into a glass, so‐called vitrification or glass transition, and the subsequent time evolution of the non‐equilibrium glass, addressed as physical aging, relies on the exclusive role of the main α relaxation with super‐Arrhenius temperature dependence. The aim of the present review is to carefully scrutinize the wealth of recent experimental results, above all in polymeric glasses, showing the relevance of other relaxational mechanisms in both vitrification and physical aging. While the α relaxation bears dominant role in both phenomena in proximity of the glass transition temperature, Tg, a broad view on a much wider temperature range indicates that vitrification and physical aging are mediated by non‐α mechanisms of equilibration. This review also shows that a reduction of the typical time scale of equilibration can be achieved in glasses with large free interface, namely with reduced sample size. In this way, fast non‐α mechanisms of equilibration can be exploited to convey glasses to low energy states in experimentally feasible time scales, thereby attaining information on the existence of the so‐called "ideal glass" in small sized samples. [ABSTRACT FROM AUTHOR]

This study examines marine boundary layer cloud regime transition during a cold air outbreak (CAO) over the Norwegian Sea, simulated by a global storm‐resolving model (GSRM) known as the Simple Cloud‐Resolving Energy Exascale Earth System Model Atmosphere Model (SCREAM). By selecting observational references based on a combination of large‐scale conditions rather than strict time‐matched comparisons, this study finds that SCREAM qualitatively captures the CAO cloud transition, including boundary layer growth, cloud mesoscale structure, and phase partitioning. SCREAM also accurately locates the greatest ice and liquid in the mesoscale updrafts, however, underestimates supercooled liquid water in cumulus clouds. The model evaluation approach adopted by this study takes advantages of the existing computational‐expensive global simulations of GSRM and the available observations to understand model performance and can be applied to assessments of other cloud regimes in different regions. Such practice provides valuable guidance on the future effort to correct and improve biased model behaviors. Plain Language Summary: Cold air outbreaks occur when cold, dry air moves over warmer ocean regions, forming extensive boundary layer clouds. However, current climate models struggle to accurately represent these clouds due to their complex nature. This study examines the performance of the global storm‐resolving model, the Simple Cloud‐Resolving Energy Exascale Earth System Model Atmosphere Model (SCREAM), in simulating marine boundary layer clouds during cold air outbreaks over the Norwegian Sea. This study compares the SCREAM simulated clouds during a cold air outbreak event to observations under similar large‐scale conditions from satellites and ground‐based measurements collected during a field campaign of the Atmospheric Radiation Measurement program. The results indicate that SCREAM successfully simulates three distinct cloud patterns during cold air outbreaks with credible mesoscale structures. Yet, it tends to underestimate supercooled liquid water and consequently, the cloud liquid water fraction, especially in cumulus clouds. The study suggests that using high‐resolution observations under similar large‐scale conditions can effectively evaluate global storm‐resolving models. This approach helps identify areas for improvement without requiring expensive global storm‐resolving model simulation designed for specific cases. Key Points: The Simple Cloud‐Resolving Energy Exascale Earth System Model Atmosphere Model (SCREAMv0), at a resolution of 3 km, simulated three distinctive cloud regimes in cold air outbreaks with credible mesoscale structuresSCREAMv0 qualitatively captures the transition of the cloud phase partitioning based on high‐resolution observationsObservations selected based on similar large‐scale conditions can be important references for global storm‐resolving model evaluation [ABSTRACT FROM AUTHOR]

Supercooled liquid clouds are common at higher latitudes (especially over the Southern Ocean) and are critical for constraining climate projections. We take advantage of the Macquarie Island Cloud and Radiation Experiment (MICRE) to perform an analysis of observed and simulated cloud processes over the Southern Ocean in a region and season dominated by supercooled liquid clouds. Using a single-column version of the European Centre for Medium-range Weather Forecast's (ECMWF) Integrated Forecast System (IFS), we compare two different cloud microphysical schemes to ground based observations of cloud, precipitation and radiation over a 2.5 month period (January 1 – March 17, 2017). Both schemes are able to reproduce aspects of the cloud and radiation observations during MICRE to within the uncertainty of the data, when the thermodynamic profile is prescribed with relaxation. There are differences in water mass and representation of reflectivity between the schemes. A sensitivity study of the cloud microphysics schemes, one a bulk one-moment scheme, and the other a two-moment scheme with prediction of mass and number, indicates that several key processes create differences between the schemes. Surface radiative fluxes and total water path are highly sensitive to the formation and fall speed of precipitation. The prediction of hydrometeor number with the two-moment scheme yields a better comparison with observed reflectivity and radiative fluxes, despite predicting higher liquid water contents than observed. With the two-moment scheme, we are also able to test the sensitivity of the results to the input of liquid Cloud Condensation Nuclei (CCN) and Ice Nuclei (IN). The cloud properties and resulting radiative effects are found to be sensitive to the CCN and IN concentrations. More CCN and IN increase liquid and ice water paths respectively. Thus both the dynamic environment and aerosols, integrated through the cloud microphysics, are important for properly representing Southern Ocean cloud radiative effects. [ABSTRACT FROM AUTHOR]

A series of Ti41Zr25Be34-xNix (x = 4, 6, 8, 10 at.%) and Ti41Zr25Be34-xCux (x = 4, 6, 8 at.%) bulk metallic glasses were investigated to examine the influence of Ni and Cu content on the viscosity, thermoplastic formability, and nanoindentation of Ti-based bulk metallic glasses. The results demonstrate that Ti41Zr25Be30Ni4 and Ti41Zr25Be26Cu8 amorphous alloys have superior thermoplastic formability among the Ti41Zr25Be34-xNix and Ti41Zr25Be34-xCux amorphous alloys due to their low viscosity in the supercooled liquid region and wider supercooled liquid region. The hardness and modulus exhibit obvious variations with increasing Ni and Cu content in Ti-based bulk metallic glasses, which can be attributed to alterations in atomic density. Optimal amounts of Ni and Cu in Ti-based bulk metallic glasses enhance thermoplastic formability and mechanical properties. The influence of Ni and Cu content on the hardness of Ti-based bulk metallic glasses is discussed from the perspective of the mean atomic distance. [ABSTRACT FROM AUTHOR]

A liquid nitrogen cooling circulating unit is a necessary condition for the stable operation of a cryogenic oscillator, which can provide a stable working environment for the oscillator. In this paper, according to the user's functional requirements and performance parameters, a closed cooling system with supercooled liquid nitrogen as the medium was designed using SOLIDWORKS 2021 software, which can provide a suitable working environment for the cryogenic oscillator. Combined with the system heat load analysis, theoretical calculation for and the design of the coil heat exchanger, one of the core pieces of equipment of the unit, were carried out. The performance of the designed nitrogen exhaust heater was studied using FLUENT 2021 software, and the velocity field and temperature field of the nitrogen exhaust heater were analyzed. The results show that the outlet temperature of the nitrogen exhaust heating device can reach up to 310 K, and the outlet flow rate of the heating device is 0.01528 kg/s. The experiments on the liquid nitrogen circulating unit using the simulated load equipment show that the refrigeration power of the unit can reach a design index of 600 W, and the temperature of the liquid nitrogen at the liquid outlet of the unit can reach 77.8 K. The experiments also show that the unit meets the design requirements. [ABSTRACT FROM AUTHOR]

Frosting occurs due to the freezing of condensed water droplets on a supercooled surface. The nucleated frost propagates through interdroplet bridges and covers the entire surface, resulting from the deposition of highly supersaturated vapor surrounding tiny droplets. While inhibition of the formation of frost bridges is not possible, the propagation of frost can be delayed by effectively removing tiny droplets. Passive technologies, such as superhydrophobic surfaces (SHS) and hydrophobic slippery liquid‐infused porous surfaces (SLIPS), rely on static growth and direct contact with densely distributed droplets. However, use of these approaches in delaying frost propagation involves challenges, as the interdroplet distance remains small. Here, we report a new approach of spontaneous droplet movement on hydrophilic SLIPS to delay the formation of interdroplet frost bridges. Surface tension forces generated by the hydrophilic oil meniscus of a large water droplet efficiently pull neighboring droplets with a diameter of less than 20 μm from all directions. This causes a dynamic separation between water droplets and an adjacent frozen droplet. Such a process delays the formation and propagation of interdroplet frost bridges. Consequently, there is significant delay in frosting on hydrophilic SLIPS compared to those on SHS and hydrophobic SLIPS. [ABSTRACT FROM AUTHOR]

This paper is dedicated to studying the effect of replacing molybdenum with vanadium on the tendency to amorphisation, structure, and thermal properties of high-entropy alloys of the (Fe0.25Ni0.25Co0.25Cr0.125Mo0.125‑xVx)100‑yBy system, where x = 0; 0.0625; 0.125 and y = 17–25. The alloy structure was analyzed using X‑ray diffraction, scanning and transmission electron microscopy methods. Thermal properties were determined by differential scanning calorimetry. It was found that the replacement of molybdenum with vanadium leads to the formation of crystalline particles of complex nitrides (V, Cr, Mo)(N, B) in the ribbon structure. The dependences of the characteristic alloy temperatures have been established. Molybdenum replacement with vanadium was shown to stabilize the supercooled liquid in alloys with completely amorphous structure. [ABSTRACT FROM AUTHOR]

This paper studied a snow event over North China on 21 February 2017, using aircraft in-situ data, a Lagrangian analysis tool, and WRF simulations with different microphysical schemes to investigate the supercooled layer of warm conveyor belts (WCBs). Based on the aircraft data, we found a fine vertical structure within clouds in the WCB and highlighted a 1–2 km thin supercooled liquid water layer with a maximum Liquid Water Content (LWC) exceeding 0.5 g kg−1 during the vertical aircraft observation. Although the main features of thermodynamic profiles were essentially captured by both modeling schemes, the microphysical quantities exhibited large diversity with different microphysics schemes. The conventional Morrison two-moment scheme showed remarkable agreement with in-situ observations, both in terms of the thermodynamic structure and the supercooled liquid water layer. However, the microphysical structure of the WCB clouds, in terms of LWC and IWC, was not apparent in HUJI fast bin scheme. To reduce such uncertainty, future work may focus on improving the representation of microphysics in bin schemes with in-situ data and using similar assumptions for all schemes to isolate the impact of physics. [ABSTRACT FROM AUTHOR]

In this study, we developed and evaluated the Korean Forecast Icing Potential (K-FIP), an in-flight icing forecast system for the Korea Meteorological Administration (KMA) based on the simplified forecast icing potential (SFIP) algorithm. The SFIP is an algorithm used to postprocess numerical weather prediction (NWP) model forecasts for predicting potential areas of icing based on the fuzzy logic formulations of four membership functions: temperature, relative humidity, vertical velocity, and cloud liquid water content. In this study, we optimized the original version of the SFIP for the global NWP model of the KMA through three important updates using 34 months of pilot reports for icing as follows: using total cloud condensates, reconstructing membership functions, and determining the best weight combination for input variables. The use of all cloud condensates and the reconstruction of these membership functions resulted in a significant improvement in the algorithm compared with the original. The weight combinations for the KMA's global model were determined based on the performance scores. While several sets of weights performed equally well, this process identified the most effective weight combination for the KMA model, which is referred to as the K-FIP. The K-FIP demonstrated the ability to successfully predict icing over the Korean Peninsula using observations made by research aircraft from the National Institute of Meteorological Sciences of the KMA. Eventually, the K-FIP icing forecasts will provide better forecasts of icing potentials for safe and efficient aviation operations in South Korea. Significance Statement: In-flight aircraft icing has posed a threat to safe flights for decades. With advances in computing resources and an improvement in the spatiotemporal resolutions of numerical weather prediction (NWP) models, icing algorithms have been developed using NWP model outputs associated with supercooled liquid water. This study evaluated and optimized the simplified forecast icing potential, an NWP model–based icing algorithm, for the global model of the Korean Meteorological Administration (KMA) using a long-term observational dataset to improve its prediction skills. The improvements shown in this study and the SFIP implemented in the KMA will provide more informative predictions for safe and efficient air travel. [ABSTRACT FROM AUTHOR]

Melt treatment is well known to have an important influence on the properties of metallic glasses (MGs). However, for the MGs quenched from different melt temperatures with a quartz tube, the underlying physical origin responsible for the variation of properties remains poorly understood. In the present work, we systematically studied the influence of melt treatment on the thermal properties of a Zr50Cu36Al14 glass-forming alloy and unveiled the microscopic origins. Specifically, we quenched the melt at different temperatures ranging from 1.1 T l to 1.5 T l (T l is the liquidus temperature) to obtain melt-spun MG ribbons and investigated the variation of thermal properties of the MGs upon heating. We found that glass transition temperature, T g, increases by as much as 36 K, and the supercooled liquid region disappears in the curve of differential scanning calorimetry when the melt is quenched at a high temperature up to 1.5 T l. The careful chemical analyses indicate that the change in glass transition behavior originates from the incorporation of oxygen and silicon in the molten alloys. The incorporated oxygen and silicon can both enhance the interactions between atoms, which renders the cooperative rearrangements of atoms difficult, and thus enhances the kinetic stability of the MGs. [ABSTRACT FROM AUTHOR]

Dual-polarization radar often detects columnar regions of enhanced differential reflectivity (ZDR) extending vertically above the environmental 0 °C level. Indicative of supercooled liquid drops and wet ice particles lofted by strong updrafts, these ZDR columns are increasingly understood to be of use in predicting extreme rainfall. With the aim of achieving practical application of ZDR column measurements, this paper focuses on the relationship between the height of ZDR columns and rainfall intensity near the ground. All the data on ZDR columns analyzed in this study was collected from weather radar stations in Japan. The height of each column and rainfall rates at low levels were analyzed using an automated algorithm. A regression analysis result reveals peak column height to be positively correlated with maximum rainfall rate near ground level, and that rainfall intensity on the ground is likely to exceed 50 mm h-1 when radar identifies a ZDR column. Furthermore, extreme rainfall with an intensity of 180 mm h-1 or more is likely associated with a column over 3 km tall from the 0 °C level. These findings suggest that surveillance of ZDR columns can contribute to the reliability of very short-range forecasts or nowcasts as well as assist with the issue of early warnings of extreme rainfall and flash floods. [ABSTRACT FROM AUTHOR]

β -relaxation has been a universal behavior in various glasses with bond kinds of covalent and metallic, as well as the metavalent, which is the typical bonding of chalcogenide phase-change materials (PCMs). Recently, the fragile-to-strong (F–S) transition kinetics has been a significant feature in supercooled liquids of PCMs, to alleviate the contradiction between good thermal stability nearby glass transition temperature and fast crystallization speed around melting temperature. By analyzing the results from the measurements of powder mechanical spectroscopy and flash differential scanning calorimetry, in this work, we revealed the link between β -relaxation and F–S crystallization kinetics in GeTe-GeSe chalcogenide glass system. It was found a positive correlation between β -relaxation and F–S transition, which is accompanied by the results of resistance drift, crystallization temperature, as well as the maximum crystal growth rate. However, the GeTe component, which has large β -relaxation behavior but no F–S transition, does not obey the positive correlation because of the large activation energy of α -relaxation. These findings are expected to build a foundation and illustrate the microscopic mechanism between F–S crystallization kinetics and β -relaxation behavior in chalcogenide glasses. [ABSTRACT FROM AUTHOR]

On approaching the dynamical transition temperature, supercooled liquids show heterogeneity over space and time. Static replica theory investigates the dynamical crossover in terms of the free energy landscape (FEL). Two kinds of static approaches have provided a self-consistent equation for determining this crossover, similar to the mode coupling theory for glassy dynamics. One uses the Morita–Hiroike formalism of the liquid state theory, whereas the other relies on the density functional theory (DFT). Each of the two approaches has advantages in terms of perturbative field theory. Here, we develop a replica field theory that has the benefits from both formulations. We introduce the generalized Franz–Parisi potential to formulate a correlation functional. Considering fluctuations around an inhomogeneous density determined by the Ramakrishnan–Yussouf DFT, we find a new closure as the stability condition of the correlation functional. The closure leads to the self-consistent equation involving the triplet direct correlation function. The present field theory further helps us study the FEL beyond the mean-field approximation. [ABSTRACT FROM AUTHOR]

Groundmass textures of volcanic rocks provide valuable insights into the processes of magma ascent, crystallization, and eruption. The diktytaxitic texture, characterized by a lath-shaped arrangement of feldspar microlites forming glass-free and angular pores, is commonly observed in silicic dome-forming rocks and Vulcanian ashfall deposits. This texture has the potential to control the explosivity of volcanic eruptions because its micropore network allows pervasive degassing during the final stages of magma ascent and eruption. However, the exact conditions and kinetics of the formation of diktytaxitic textures, which are often accompanied by vapor-phase cristobalite, remain largely unknown. Here, we show that the diktytaxitic texture and vapor-phase minerals, cristobalite and alkali feldspar, can be produced from bulk-andesitic magma with rhyolitic glass under water-saturated, near-solidus conditions (± ~10 MPa and ± ~20 °C within the solidus; 10–20 MPa and 850 °C for our starting pumices). Such crystallization proceeds through the partial evaporation of the supercooled melt, followed by the deposition of cristobalite and alkali feldspar as a result of the system selecting the fastest crystallization pathway with the lowest activation energy. The previously proposed mechanisms of halogen-induced corrosion or melt segregation by gas-driven filter pressing are not particularly necessary, although they may occur concurrently. Diktytaxitic groundmass formation is completed within 4–8 days, irrespective of the presence or composition of the halogen. These findings constrain the outgassing of lava domes and shallow magma intrusions and provide new insights into the final stages of hydrous magma crystallization on Earth. [ABSTRACT FROM AUTHOR]

Liquids and gases are distinct in their extent of dynamic atomic correlations; in gases, atoms are almost uncorrelated, whereas they are strongly correlated in liquids. This distinction applies also to electronic systems. Fermi liquids are actually gas-like, whereas strongly correlated electrons are liquid-like. Doped Mott insulators share characteristics with supercooled liquids. Such distinctions have important implications for superconductivity. We discuss the nature of dynamic atomic correlations in liquids and a possible effect of strong electron correlations and Bose–Einstein condensation on the high-temperature superconductivity of the cuprates. [ABSTRACT FROM AUTHOR]

The kinetics of the first order liquid–liquid transition (LLT) in a single-component liquid D-mannitol have been examined in detail by the high rate of flash differential scanning calorimetry measurements. By controlling the annealing temperature, the phase X formation from the supercooled liquid is distinguished by either a nucleation-growth or a spinodal-decomposition type of LLT. In the measured time–temperature-transformation curve the portion covering the nucleation-growth type of LLT can be well fitted with a classical nucleation theory analysis. [ABSTRACT FROM AUTHOR]

A supercooled fluid close to the glass transition develops nonlocal shear-stress correlations that anticipate the emergence of elasticity. We performed molecular dynamics simulations of a binary Lennard-Jones mixture at different temperatures and investigated the spatiotemporal autocorrelation function of the shear stress for different wavevectors, q, from a locally measured and Fourier-transformed stress tensor. Anisotropic correlations are observed at non-zero wavevectors, exhibiting strongly damped oscillations with a characteristic frequency ω(q). A comparison with a recently developed hydrodynamic theory [Maier et al., Phys. Rev. Lett. 119, 265701 (2017)] shows a remarkably good quantitative agreement between particle-based simulations and theoretical predictions. [ABSTRACT FROM AUTHOR]

In previous work, water's second glass transition was investigated based on an amorphous sample made from crystalline ice [Amann-Winkel et al., Proc. Natl. Acad. Sci. U. S. A. 110, 17720 (2013)]. In the present work, we investigate water's second glass transition based on the genuine glassy state of high-density water as prepared from micron-sized liquid water droplets, avoiding crystallinity at all stages. All the calorimetric features of water's second glass transition observed in the previous work are also observed here on the genuine glassy samples. This suggests that the glass transition indeed thermodynamically links amorphous ices continuously with deeply supercooled water. We proceed to extend the earlier study by investigating the effect of preparation history on the calorimetric glass transition temperature. The best samples prepared here feature both a lower glass transition temperature Tg,2 and a higher polyamorphic transition temperature Tons, thereby extending the range of thermal stability in which the deeply supercooled liquid can be observed by about 4 K. Just before the polyamorphic transition, we observe a spike-like increase of heat capacity that we interpret in terms of nucleation of low-density water. Without this spike, the width of water's second glass transition is 15 K, and the Δcp amounts to 3 ± 1 J K−1 mol−1, making the case for the high-density liquid being a strong liquid. We suggest that samples annealed at 1.9 GPa to 175 K and decompressed at 140 K to ≥0.10 GPa are free from such nuclei and represent the most ideal high-density amorphous glasses. [ABSTRACT FROM AUTHOR]