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Upon heating, ultrastable glassy films transform into liquids via a propagating equilibration front, resembling the heterogeneous melting of crystals. A microscopic understanding of this robust phenomenology is, however, lacking because experimental resolution is limited. We simulate the heterogeneous transformation kinetics of ultrastable configurations prepared using the swap Monte Carlo algorithm, thus allowing a direct comparison with experiments. We resolve the liquid–glass interface both in space and in time as well as the underlying particle motion responsible for its propagation. We perform a detailed statistical analysis of the interface geometry and kinetics over a broad range of temperatures. We show that the dynamic heterogeneity of the bulk liquid is passed on to the front that propagates heterogeneously in space and intermittently in time. This observation allows us to relate the averaged front velocity to the equilibrium diffusion coefficient of the liquid. We suggest that an experimental characterization of the interface geometry during the heterogeneous devitrification of ultrastable glassy films could provide direct experimental access to the long-sought characteristic length scale of dynamic heterogeneity in bulk supercooled liquids. [ABSTRACT FROM AUTHOR]

The temperature dependence of the heat capacity of the sixth generation carbosilane dendrimer with terminal trimethylsilylsiloxane groups was determined by high-precision adiabatic vacuum calorimetry in the temperature range 6–318 K and differential scanning calorimetry in the range 300–600 K. Anomalous changes in the heat capacity were discovered in the range T = 179–200 K due to devitrification of the dendrimer and in the range 380–450 K due to the nanoscale effect characteristic of dendrimers of high generations. The thermal stability of the compound was studied by thermogravimetric analysis, and the temperature of the start of thermal destruction was found to be 600 K. The experimental data obtained were used to calculate the standard thermodynamic functions of the dendrimer for the range from T → 0 to 600 K for various physical states, as well as the standard entropy of its formation in the devitrified state at T = 298.15 K. [ABSTRACT FROM AUTHOR]

Although particular attention has been paid to responses of hydrocarbon storage and percolation capacity to the devitrification concerning lacustrine tuffaceous shale reservoirs in recent years, there is still a lack of systematical and comparative investigation on differential patterns and potential triggering mechanisms concerning development of the pore-microfracture systems and characteristics of surface wettability between the fresh-water and saline lacustrine settings, which is of considerable importance in fully understanding of genesis and spatial distribution of dessert reservoir intervals of tuffaceous shale reservoirs, and to provide further conceptual basis for deciphering shale- oil movability of saline lacustrine fine-grained mixed sedimentary sequences. In this study, tuffaceous shales from both the Upper Triassic Yanchang Formation in the Ordos Basin and Middle Permian Jingjingzigou Formation in the Junggar Basin are targeted to unravel the differential behavior of tuff devitrification and potential impacts on reservoir wettability and pore connectivity concerning fresh-water and saline lacustrine settings, and we present new results here from integrated analyses and combined interpretation of FE-SEM, Image Pro Plus (IPP) software image processing, contact angle and spontaneous imbibition experiments. In view of comparative analysis from representative samples, the tuffaceous shales from saline lacustrine environments are characterized by well-developed intergranular-intercrystalline and dissolution pores, and inorganic microfractures, generally yield a higher plane porosity of representative pore-fracture spaces and spontaneous imbibition slopes, a relatively lower average of n-decane contact angles and corresponding wettability parameters. The saline lacustrine tuffaceous shales are thus suspected to have undergone more intense devitrification resulting in a higher amount of devitrification and associated dissolution pores, and a relatively better connectivity between isolated micropore systems with adjacent microfractures. This would significantly facilitate the interface wettability reversal and occurrence of movable hydrocarbon fluid in microscopic reservoir spaces. Finally, a comprehensive and conceptual model is established illustrating the effects of differential devitrification on reservoir-forming patterns concerning tuffaceous shales developed in the fresh-water and saline lacustrine settings, respectively. These findings are of great theoretical and practical significance to enrich theory of high-quality reservoir formation and shale-oil accumulation in saline lacustrine tuffaceous shale reservoirs, and lay the foundation for guiding efficient exploration of continental fine-grained mixed sedimentary sequences. [ABSTRACT FROM AUTHOR]

To generate red emissions, manganese (IV) ions have recently gained recognition as potent non-rare-earth activators. However, the oxide and fluoride hosts that offer suitable environments for Mn4+ require careful preparation, involving precise control of reaction parameters like redox equilibrium and temperature. In the current work, we show simultaneous oxidation of Mn2+ to Mn4+ by devitrification of glassy Na 2 Ge 4 O 9 : Mn under moderate atmospheric conditions and under the argon atmosphere. The G-sample was devitrified via thermal treatment after the parent glass, which shares the same chemical formula as dilithium tetragermanate (Na 2 Ge 4 O 9), was created through the use of traditional melt-quenching (MQ). Optical spectroscopy and electron paramagnetic resonance (EPR) spectroscopic are utilized to confirm the Mn2+ oxidation to Mn4+ from glass stat to glass ceramic after thermal treatment. Due to the transition from Mn2+ to Mn4+, a sharp 668 nm emission peak is recorded whereas the red emission peaking at 611 nm monitored in glass is steadily reduced. The temperature-dependent PL spectra of the Na 2 Ge 4 O 9 :0.1Mn+4, red-emitting GC in the temperature range ∼295–490 K were recorded. The PL emission intensity decreases gradually with increasing the temperature. The technique showcased for producing Na 2 Ge 4 O 9 :Mn4+ phosphors could be expanded to synthesize other phosphors incorporating activators possessing a high oxidation state. [ABSTRACT FROM AUTHOR]

Bulk Se90Pb10−xSnx (x = 0, 2, 4, 6, and 8) glassy alloys have been obtained by quenching technique, where x indicates the atomic mass percentage (at. mass%) of tin. The differential scanning calorimeter (DSC) technique is used under non-isothermal conditions to determine different characteristic temperatures such as the glass transition temperature Tg, on-set and peak crystallization temperatures Tc and Tp, and melting temperature Tm. The thermal stability parameter of current ternary Se90Pb10−xSnx glasses exhibits A nonlinear compositional dependence with a maximum value for x = 8 at. mass% of Sn. The mean values of the crystallization rate (< Kp >) are lowest at x = 2 and 8, suggesting that a long time is required for these two compositions to fully crystallize. As a result, their stability against devitrification is at its highest, whereas the composition containing 6 at. mass% of Sn has the highest rate of crystallization and the lowest stability against devitrification. [ABSTRACT FROM AUTHOR]

When heated rapidly, glasses often devitrify heterogeneously, i.e., by a softening front that originates at the surface of an amorphous film. Yet the fundamentals of this devitrification regime are not completely understood; depending on experimental conditions, the reported front propagation distances differ by an order of magnitude. Using a high-resolution fast scanning calorimetry technique, we have investigated the softening of glassy methylbenzene films with thicknesses between 30 and 1400 nm. We confirm first that, in all films, the devitrification process begins with the formation of a softening front that propagates through the films over distances of ∼50 nm and that the front propagation kinetics at this stage follow an Arrhenius law. However, we also show that, in films with thicknesses above 165 nm, the front propagation does not terminate with the onset of bulk softening. Specifically, increasing the films' thicknesses above 165 nm yields sharp, clearly discernible endotherms that precede the bulk softening endotherms and that are consistent with a two-fold increase in the enthalpic barrier to front propagation at a well-defined critical temperature. We term this phenomenon "Arrhenius discontinuity" and use reaction rate and continuum front dynamics theories to explain its origins and the physical nature of the resulting distinct heterogeneous devitrification processes. Finally, we discuss the findings in the context of recent theoretical, computational, and experimental studies of heterogeneous devitrification by other research groups. [ABSTRACT FROM AUTHOR]

The development of high-strength cold spray deposits using amorphous/nanocrystalline aluminum high-entropy alloy (Al HEA) powder is hindered by the lack of understanding of correlations between powder microstructure and its deformation behavior. In this study, gas-atomized Al HEA powder (Al90.05-Y4.4-Ni4.3-Co0.9-Sc0.35 at.%) is devitrified at 298, 345, 362, and 450 °C to optimize strength and deformation for cold spraying. Devitrification-induced atomic rearrangement developed equiaxed Al grains and Al3Ni and Al3Sc precipitates. The amorphous content, growth of grains, hard precipitates, and reduced dislocation density increased the hardness by 16% to 515 HV at 298 °C and decreased the hardness by 55% to 190 HV at 450 °C. The compressive strength of Al HEA powder increased by 5% to 1559 MPa at 298 °C and decreased by 49% to 760 MPa at 450 °C. To enhance the limited sprayability of Al HEA powder, compressive strength is used to model optimized cold spray process maps. Helium gas with temperatures from 300 to 800 °C and a pressure of 40 bar can produce cold spray deposits with deposition efficiency greater than 70%. The scientific insights acquired from the present study provide a gateway toward developing novel lightweight and high-strength aluminum alloy deposits, thus marking an advancement in cold spray technology. [ABSTRACT FROM AUTHOR]

Magma mingling and mixing are common processes at basaltic volcanoes and play a fundamental role in magma petrogenesis and eruption dynamics. Mingling occurs most commonly when hot primitive magma is introduced into cooler magma. Here, we investigate a scenario whereby cool, partially degassed lava is drained back into a conduit, where it mingles with hotter, less degassed magma. The 1959 eruption of Kīlauea Iki, Hawaiʻi involved 16 high fountaining episodes. During each episode, fountains fed a lava lake in a pit crater, which then partially drained back into the conduit during and after each episode. We infer highly crystalline tachylite inclusions and streaks in the erupted crystal-poor scoria to be the result of the recycling of this drain-back lava. The crystal phases present are dendrites of plagioclase, augite and magnetite/ilmenite, at sizes of up to 10 µm. Host sideromelane glass contains 7–8 wt% MgO and the tachylite glass (up to 0.5% by area) contains 2.5–6 wt% MgO. The vesicle population in the tachylite is depleted in the smallest size classes (< 0.5 mm) and has overall lower vesicle number densities and a higher degree of vesicle coalescence than the sideromelane component. The tachylite exhibits increasingly complex 'stretching and folding' mingling textures through the episodes, with discrete blocky tachylite inclusions in episodes 1 and 3 giving way to complex, folded, thin filaments of tachylite in pyroclasts erupted in episodes 15 and 16. We calculate that a lava lake crust 8–35 cm thick may have formed in the repose times between episodes, and then foundered and been entrained into the conduit during drain-back. The recycled fragments of crust would have been reheated in the conduit, inducing glass devitrification and crystallisation of pyroxene, magnetite and plagioclase dendrites and eventually undergoing ductile flow as the temperature of the fragments approached the host magma temperature. We use simple models of magma mingling to establish that stretching and folding of recycled, ductile lava could involve thinning of the clasts by up to a factor of 10 during the timescale of the eruption, consistent with observations of streaks and filaments of tachylite erupted during episodes 15 and 16, which may have undergone multiple cycles of eruption, drain-back and reheating. [ABSTRACT FROM AUTHOR]

The presence of extensive clay minerals in the ancient Noachian terrains of Mars is often used to invoke past climatic conditions that were warmer and supported surfacestable liquid water. These clay-rich regions are also heavily cratered, leading to the possibility of a causal relationship. The aim of this study is to better understand the impact excavation and generation of clays and whether there are any mineralogical or geochemical indicators that could differentiate between these two origins, both on Earth and, by analogy, Mars. Here, we present a detailed field and laboratory investigation of the composition, texture, and setting of clay minerals in impactites at the well-preserved Ries impact structure, Germany. Authigenic impactite (syn- and post-impact) clay minerals in impact melt-bearing breccia deposits are compared with sedimentary-derived clay mineral-bearing units preserved from the time of the impact event. Our findings indicate: (1) impact-generated deposits comprise compositionally diverse, Al-dominant smectitic clay minerals that could have formed without appreciable exogenous volatiles through a combination of autometamorphism, hydrothermal alteration, and devitrification; and (2) the pre-impact sedimentary clay mineral assemblages were similar in composition to those in the impact-generated deposits such that only detailed, successive laboratory treatments and analyses could discern the two sample types. NASA's Perseverance Mars rover mission is presently investigating its first science campaign and has identified secondary alteration products, including possible clay minerals. Our study suggests that the rover may explore impact-generated clay minerals in situ, though their provenance might only be determined from analysis of the returned samples in Earth laboratories. [ABSTRACT FROM AUTHOR]

Metallic glasses exhibit unique mechanical properties. For metallic glass composites (MGC), composed of dispersed nanocrystalline phases in an amorphous matrix, these properties can be enhanced or deteriorated depending on the volume fraction and size distribution of the crystalline phases. Understanding the evolution of crystalline phases during devitrification of bulk metallic glasses upon heating is key to realizing the production of these composites. Here, results are presented from a combination of in situ small‐ and wide‐angle X‐ray scattering (SAXS and WAXS) measurements during heating of Zr‐based metallic glass samples at rates ranging from 102 to 104 Ks−1 with a time resolution of 4ms. By combining a detailed analysis of scattering experiments with numerical simulations, for the first time, it is shown how the amount of oxygen impurities in the samples influences the early stages of devitrification and changes the dominant nucleation mechanism from homogeneous to heterogeneous. During melting, the oxygen rich phase becomes the dominant crystalline phase whereas the main phases dissolve. The approach used in this study is well suited for investigation of rapid phase evolution during devitrification, which is important for the development of MGC. [ABSTRACT FROM AUTHOR]

Polycarbosilanes (PCS) are organosilicon polymers that can be converted into silicon carbide (SiC) ceramics upon pyrolysis. The phase compositions and microstructure of the final ceramic are notably impacted by the interplay of both polymer morphology and chemical functionality. Such characteristics hold tremendous potential for developing polymer derived ceramics (PDCs) with optimized properties if the complexities inherent to such materials are better understood at the atomic-scale. This study investigates the structural changes associated with the polymer-to-ceramic conversion in SiC systems derived from the pyrolysis of commercial PCS: SMP-10, SMP-877 and SMP-730, across a temperature range of 250–1600 °C. Using a combination of synchrotron X-ray spectroscopy and scattering methods, we reveal heterogeneous structures with varied compositions, influenced by both pyrolysis conditions and initial PCS functionalities. This study offers a promising approach for understanding the devitrification and compositional heterogeneity (C vs. SiC phases) in polymer-to-ceramic conversion. [ABSTRACT FROM AUTHOR]

Although particular attention has been paid to responses of hydrocarbon storage and percolation capacity to the devitrification concerning lacustrine tuffaceous shale reservoirs in recent years, there is still a lack of systematical and comparative investigation on differential patterns and potential triggering mechanisms concerning development of the pore-microfracture systems and characteristics of surface wettability between the fresh-water and saline lacustrine settings, which is of considerable importance in fully understanding of genesis and spatial distribution of dessert reservoir intervals of tuffaceous shale reservoirs, and to provide further conceptual basis for deciphering shale-oil movability of saline lacustrine fine-grained mixed sedimentary sequences. In this study, tuffaceous shales from both the Upper Triassic Yanchang Formation in the Ordos Basin and Middle Permian Jingjingzigou Formation in the Junggar Basin are targeted to unravel the differential behavior of tuff devitrification and potential impacts on reservoir wettability and pore connectivity concerning fresh-water and saline lacustrine settings, and we present new results here from integrated analyses and combined interpretation of FE-SEM, Image Pro Plus (IPP) software image processing, contact angle and spontaneous imbibition experiments. In view of comparative analysis from representative samples, the tuffaceous shales from saline lacustrine environments are characterized by well-developed intergranular-intercrystalline and dissolution pores, and inorganic microfractures, generally yield a higher plane porosity of representative pore-fracture spaces and spontaneous imbibition slopes, a relatively lower average of n-decane contact angles and corresponding wettability parameters. The saline lacustrine tuffaceous shales are thus suspected to have undergone more intense devitrification resulting in a higher amount of devitrification and associated dissolution pores, and a relatively better connectivity between isolated micropore systems with adjacent microfractures. This would significantly facilitate the interface wettability reversal and occurrence of movable hydrocarbon fluid in microscopic reservoir spaces. Finally, a comprehensive and conceptual model is established illustrating the effects of differential devitrification on reservoir-forming patterns concerning tuffaceous shales developed in the fresh-water and saline lacustrine settings, respectively. These findings are of great theoretical and practical significance to enrich theory of high-quality reservoir formation and shale-oil accumulation in saline lacustrine tuffaceous shale reservoirs, and lay the foundation for guiding efficient exploration of continental fine-grained mixed sedimentary sequences.

Jadeite is a sought-after jade mineral that is often imitated using natural and artificial materials. A jadeite imitation that is convincing to the naked eye is investigated. The imitation is yellowish green and white, subtranslucent, and exhibits a vitreous luster. Standard gemological testing and spectral characterization revealed the composition to be wollastonite and soda–lime–alumina–silica glass. The wollastonite was added during the sintering process, making it different to wollastonite glasses prepared by devitrification in earlier reports. The findings demonstrated that shifted excitation Raman difference spectroscopy is a cost-effective, efficient, and nondestructive technique for identifying gemstones and their imitations, particularly those showing strong fluorescence. [ABSTRACT FROM AUTHOR]

Three compositions 75V2O5-25MgO (MVL-0), 75V2O5-16MgO-9Li2O (MVL-9) and 75V2O5-13MgO-12Li2O (MVL-12) were synthesized by melt-quench technique. Addition of Li2O instead of MgO promoted the devitrification of magnesium vanadate glass. X-ray diffraction pattern showed the amorphous nature of MVL-0, while MVL-9 and MVL-12 were seen to exhibit a lithium vanadium oxide phase with the presence of some amorphous phase. Densities of the samples increased with the increase in Li2O concentration. Raman spectra of MVL-0 exhibited broad band as compared to the other samples; as Li2O concentration increased, the band became sharp including the appearance of some more new bands. High electrical conductivity was observed for MVL-12; ∼9.615×10–5 S.cm–1 at 50°C to 1.96×10–3 S.cm–1 at 250°C, which is comparable to the conductivity of standard cathode materials used in battery and electrochemical fuel cells. So, these samples may be used as cathode materials due to good conductivity at 250°C for battery and electrochemical fuel cells. [ABSTRACT FROM AUTHOR]

Borosilicate bioactive glasses exhibit excellent bioactivity and degradation properties; however, they suffer from the rapid release of bioactive elements at the initial stage of their degradation. Excessive local concentrations (such as those of B) can affect cell proliferation. Moreover, the degradation and mineralization ability of these glasses deteriorate at the later stages. Aiming to balance the release of bioactive elements during the whole process, herein, a borosilicate bioactive glass 18SiO2–6Na2O–8K2O–8MgO–22CaO–2P2O5–36B2O3 (mol%) was prepared using the melting method. Further, the effects of microcrystallization on the release of bioactive elements and in vitro degradation were studied. Results show that after heat treatment at temperatures over 620 °C, multiple microcrystalline phases, including Ca2SiO4, CaB2O4, and CaMgB2O5, form in the glass. The glass samples heat-treated within the range of 620–640 °C undergo appropriate devitrification degrees, decelerating the rate of pH increase of the immersion solution during the initial stage in comparison to those treated at lower temperatures. This results in a more continuous release of all bioactive elements and allows better control of the overall degradation. Contrarily, the more extensive devitrification degrees of glass samples heat-treated at higher temperatures reverse the pH increase and degradation trends. Since bone marrow mesenchymal stem cells and mouse embryonic osteoblast cells are pH-sensitive, inducing a suitable degree of devitrification proved to favor cell viability and enhance the mineralization capacity. Thus, different microcrystallization degrees provide new approaches for controlling the degradation and release of bioactive elements, resulting in the simultaneous enhancement of biosafety and bioactivity. [ABSTRACT FROM AUTHOR]

This paper provides a detailed technological characterization of the Roman opus sectile glasses (second century AD) coming from the renowned Gorga collection. Nine glass samples corresponding to imitations of the porfido verde antico, cipollino rosso, rosso antico, giallo antico, diaspro nero e giallo, semesanto and agate/alabaster stones were studied. The aim of this study was twofold: (i) archaeometric, i.e., to provide valuable data on the production, raw materials and techniques of these refined Roman glasses that mimic precious stones and (ii) methodological, i.e., to highlight the good performance of combining polished thin sections and local probe measurements for the study of glassy microstructures. Based on the nature of the flux used, the glasses from the samples were classified as either natron-type or mixed-type (natron/plant ash). The latter stem from remelted glasses and contain relict grains of wollastonite that were not found in the pure natron samples. Relict wollastonite crystals appear to be a proficient petrographic marker to spot recycled glasses along with the commonly used chemical fingerprints. Different production and colouring techniques were identified, even for a given type of imitated stone. Metallic Cu, Ca antimonates and Pb-Fe antimonates were the three opacifiers used for the opaque glasses. Based on the crystal morphologies, metallic Cu and Ca antimoniates were possibly synthesized in situ simultaneously with the glass, whilst the Pb-Fe antimonates were prepared ex situ. The working temperatures for these glasses were estimated within the 900–1100 °C range based on the presence and known thermal stability of some identified crystal phases. [ABSTRACT FROM AUTHOR]

The paucity of crystallization resistant bioactive glasses with desired biological functions stands as a bottleneck toward the fabrication of various biomedical constructs such as amorphous coatings, scaffolds, and fibers for advanced tissue engineering applications. In this context, a series of borosilicate‐based bioactive glasses with a range of compositions: (53.88 − x)SiO2–21.7Na2O–21.7CaO–1.7P2O5–xB2O3 (mol%) where x = 0, 13.47, 22.45, 31.43, and 40.41 were prepared to address such limitation. The glasses were primarily investigated for their potential to be processed into amorphous scaffolds through evaluation of crystallization kinetics, sintering behavior, and viscosity–temperature dependence. The inclusion of B2O3 gradually reduces the activation energy of crystallization (Ea), according to the prediction from different kinetic models, whereas Friedman's model‐free method unraveled the variation in Ea as crystallization progresses. The crystallization event is further elucidated by obtaining the Avrami parameter (n) and dimensionality (m) through Matusita–Sakka equation. The optimization of the sintering schedule for amorphous scaffold preparation was accomplished by exploiting isothermal prediction from Avrami–Erofeev model. Moreover, viscosity–temperature relationship for the studied glasses was established to identify the processing window for drawing and sintering. This study proposes a comprehensive approach adopting theoretical models to elucidate suitable high‐temperature process parameters of bioactive glasses avoiding devitrification. [ABSTRACT FROM AUTHOR]

The process of the devitrification of copper nanoparticles in vacuum and in a silver shell during heating was studied using a molecular dynamics simulation. The results show that there is an inverse relationship between the particle diameter and devitrification temperature. As the size of the particles decreases, the temperature at which devitrification occurs increases due to a higher fraction of atoms near the interface. The presence of a silver shell leads to a significant increase in the devitrification temperature of the copper nanoparticles. For the considered particle sizes, the difference between the devitrification temperatures without a shell and with a shell ranged from 130 K for copper particles with a diameter of 11 nm to 250 K for 3 nm particles. The mechanisms of the nucleation of a crystalline phase in particles in vacuum and in a silver shell are significantly different. In the first case, crystalline nuclei are predominantly formed near the surface, while in the second case, on the contrary, they are formed within the particle's volume. [ABSTRACT FROM AUTHOR]

The composition of 75V2O5–(25-x) MgO–xLi2O (x = 0, 1.5, 3.0, 4.5, and 6.0) is synthesized by the melt quenching method. The effects of Li2O on devitrification, physical, thermal, structural, and conducting properties of the as-quenched samples are analyzed utilizing various experimental techniques. X-ray diffraction and differential thermal analysis confirmed the formation of phase-separated glasses up to 3.0 mol. % of Li2O. Above this concentration of Li2O, the samples are glass ceramic. With an increase in the concentration of Li2O, the density increases in all the samples. The Raman spectra demonstrate that as the concentration of Li2O increases, there is a transition of VO5 units into different structural units of vanadium oxide. The highest conductivity is observed for the composition with x = 4.5, i.e., 10−4 S/cm at 250 °C. The activation energy indicated that the present samples could be mixed conductors in nature. These samples can be used as cathode materials in energy storage devices due to their mixed conduction with an appropriate conductivity at 250 °C. [ABSTRACT FROM AUTHOR]

Biobanking of pancreatic islets for transplantation could solve the shortage of donors, and cryopreservation of vitrified islets is a possible approach. However, a technological barrier is rewarming of large volumes both uniformly and rapidly to prevent ice formation due to devitrification. Here, we describe successful recovery of islets from the vitrified state using a volumetric rewarming technology called "nanowarming," which is inductive heating of magnetic nanoparticles under an alternating magnetic field. Convective warming using a 37°C water bath as the gold standard for rewarming of vitrified samples resulted in a decrease in the viability of mouse islets in large volumes (>1 ml) owing to devitrification caused by slow warming. Nanowarming showed uniform and rapid rewarming of vitrified islets in large volumes. The viability of nanowarmed islets was significantly improved and islets transplanted into streptozotocin‐induced diabetic mice successfully lowered serum glucose. The results suggest that nanowarming will lead to a breakthrough in biobanking of islets for transplantation. [ABSTRACT FROM AUTHOR]

The discovery of ultrastable glasses raises novel challenges about glassy systems. Recent experiments studied the macroscopic devitrification of ultrastable glasses into liquids upon heating but lacked microscopic resolution. We use molecular dynamics simulations to analyze the kinetics of this transformation. In the most stable systems, devitrification occurs after a very large time, but the liquid emerges in two steps. At short times, we observe the rare nucleation and slow growth of isolated droplets containing a liquid maintained under pressure by the rigidity of the surrounding glass. At large times, pressure is released after the droplets coalesce into large domains, which accelerates devitrification. This two-step process produces pronounced deviations from the classical Avrami kinetics and explains the emergence of a giant lengthscale characterizing the devitrification of bulk ultrastable glasses. Our study elucidates the nonequilibrium kinetics of glasses following a large temperature jump, which differs from both equilibrium relaxation and aging dynamics, and will guide future experimental studies. [ABSTRACT FROM AUTHOR]

Bulk metallic glass of Cu38Zr54Al8 nominal composition was synthesized by copper mold casting into 6 mm diameter rods. Disks of the as-cast glass were subjected to severe plastic deformation by high-pressure torsion for different number of revolutions. The microstructure and the thermal behavior of the as-cast, isothermally annealed and deformed glass have been investigated by X-ray diffraction and differential scanning calorimetry, respectively. Continuous heating experiments revealed a two-stage devitrification event with excellent glass forming parameters, such as glass transition (Tg = 671 K), supercooled liquid region (∆Tx = 80 K), reduced glass transition (Tr = 0.57) and gamma parameter (γ = 0.41). Power law crystal growth during diffusion-controlled homogeneous nucleation was observed for isothermal annealings. Glassy state was preserved almost in the entire sample volume of the as-cast alloy during the high-pressure torsion process, corresponding to the extreme stability of the Cu38Zr54Al8 alloy against deformation-induced devitrification. This is in accordance with the transition of the reversible specific heat from the glassy to supercooled liquid state measured by modulated calorimetry. It was also concluded that glassy structure is more ordered in the severely deformed state. [ABSTRACT FROM AUTHOR]

A simulation mathematical model is presented that describes binder vitrification and devitrification. Theoretical estimates of the effective physical and mechanical parameters of the material and microstructural stresses at different temperatures are obtained. A numerical scheme is developed in the form of software that makes it possible to implement the modeling method. Elastic moduli and submicrostructural stresses are estimated. The results can be used to select the composition and parameters of the material at the final stages of the technological process of creating a polymer binder. [ABSTRACT FROM AUTHOR]

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The investigation of devitrification in thermally annealed nanodimensional glassy alloy thin films provides a comprehensive understanding of their thermal stability, which can be used to explore potential applications. The amorphous to crystalline polymorphous transformation of cosputtered Ni-Zr alloy (Ni78Zr22 at. %) films, with a thickness lower than the reported critical limit of devitrification, was studied through detailed structural characterization and molecular dynamics (MD) simulations. Devitrification to a nanocrystalline state (Ni7Zr2 structure) was observed at 800 °C, with an increase in density (∼3.6%) much higher than that achieved in bulk alloys. Variation in the magnetic property of the films and the overall physical structure including morphology and composition were examined before and after annealing. MD simulations were employed to effectively elucidate not only the high densification but also the increased magnetic moment after annealing, which was correlated with the simulated change in the coordination number around Ni atoms. The structural relaxation process accompanying devitrification was described as a disorder-to-order transformation while highlighting the crucial role played by chemical short range order prevalent in glassy materials. [ABSTRACT FROM AUTHOR]

Understanding the impact of individual compositional components on the devitrification of complex multicomponent glasses, for example, 10–50+ oxides, typically requires numerous studies to examine each component's impact. Here we apply exploratory data analysis (EDA) to a heterogeneous data set of silicate glasses to determine the cations' individual and interacting effects on the crystallization of nepheline (nominally NaAlSiO4). Our data consisted of 795 simulated high‐level nuclear waste glasses composed of, on average, 50 oxide components. We determine the interactions in the heterogeneous data that cause deviations from the behavior found in simplified composition studies. Using both univariate and bivariate EDA techniques, we demonstrate the importance of including calculated structural glass parameters on nepheline's devitrification, including field strength, cation‐to‐anion radius ratio, and single‐bond strength. We also show that studies with simplified glass compositions may fall short in generating knowledge directly transferrable to complex glass compositions. The method used in this study has the potential to inform experimental design for simplified compositions (∼6+ oxides) that can generate knowledge directly transferrable to complex, multivariable compositions. The observations reported here have broad implications for any study attempting to map the physical properties of a complex glass containing numerous cations. [ABSTRACT FROM AUTHOR]

Vitrification is a promising cryopreservation technique for complex specimens such as tissues and organs. However, it is challenging to identify mixtures of cryoprotectants (CPAs) that prevent ice formation without exerting excessive toxicity. In this work, we developed a multi-CPA toxicity model that predicts the toxicity kinetics of mixtures containing five of the most common CPAs used in the field (glycerol, dimethyl sulfoxide (DMSO), propylene glycol, ethylene glycol, and formamide). The model accounts for specific toxicity, non-specific toxicity, and interactions between CPAs. The proposed model shows reasonable agreement with training data for single and binary CPA solutions, as well as ternary CPA solution validation data. Sloppy model analysis was used to examine the model parameters that were most important for predictions, providing clues about mechanisms of toxicity. This analysis revealed that the model terms for non-specific toxicity were particularly important, especially the non-specific toxicity of propylene glycol, as well as model terms for specific toxicity of formamide and interactions between formamide and glycerol. To demonstrate the potential for model-based design of vitrification methods, we paired the multi-CPA toxicity model with a published vitrification/devitrification model to identify vitrifiable CPA mixtures that are predicted to have minimal toxicity. The resulting optimized vitrification solution composition was a mixture of 7.4 molal glycerol, 1.4 molal DMSO, and 2.4 molal formamide. This demonstrates the potential for mathematical optimization of vitrification solution composition and sets the stage for future studies to optimize the complete vitrification process, including CPA mixture composition and CPA addition and removal methods. [ABSTRACT FROM AUTHOR]

The Tc (collapse temperature) and thermal history of the solution were studied using freeze-drying microscopy and differential scanning calorimetry (DSC), the Tg´ (glass transition temperature of the maximally freeze-concentrated state) was determined according to the two results obtained. The effects of different heating and freezing rated on Tg´ and Tc of isomaltose (IMO) solution were analyzed. The effect of D-Mannitol solution, according to its characteristics reverse glass transition and enhancement of ice crystal structure, on Tg´ and Tc of IMO solution was investigated. It could be concluded that the low and high temperature transitions presented in the thermal history of sample solutions. The measured Tc existed between the end of low temperature transition and the beginning of high temperature transition, and the low temperature transition was identified to be glass transition according to the freeze-concentrated state of solutions. The freezing rates had no significant effect on Tc and Tg´, and Tc was 3~4 ℃ higher than Tg´. However, the higher the freezing rate, the more obvious the collapse phenomenon, with the increasing of heating rate , Tc and Tg´ increased and collapse phenomenon aggravates, Tc increased more obviously, the drying effect was better at 1 ℃/min. With the reduction of IMO/D-Mannitol ratio, Tg´ decreased and the devitrification phenomenon became more obvious, the most was 5:5, the drying effect of 9:1 and 5:5 was better than that of IMO solution, the collapse was worst at 8:2, Tc was 6~7 ℃ higher than Tg´. When a small amount of D-Mannitol was added, the dried structure was better preserved, Tc was higher than that of IMO solution at 9:1, and the drying layer maintained better.

Cryoprotective agents play a critical role in minimizing cell damage caused by ice formation during cryopreservation. However, high concentrations of CPAs are toxic to cells and tissues. Required concentrations of CPAs can be reduced by utilizing higher cooling and warming rates, but insight into the thermophysical properties of biological solutions in the vitrification method is necessary for the development of cryopreservation protocols. Most studies on thermophysical properties under ultra-rapid cooling conditions have been qualitatively based on visualization. Differential scanning calorimetry methods are ideal for studying the behavior of biomaterials in various freezing conditions quantitatively and accurately, though previous studies have been predominantly restricted to slower cooling rates. Here, we developed an ultra-rapid cooling method for DSC that can achieve minimal cooling rates exceeding 2000 °C/min. We investigated the thermophysical vitrification behavior of ternary solutions of phosphate buffer saline (1X), dimethyl sulfoxide or glycerol and ice blocking polymers (X-1000 or Z-1000). We quantified the impact of solute concentration on ice crystal formation during rapid cooling. Our findings support the expectation that increasing the solute concentration reduces the amount of ice formation, including devitrification. Devitrification increases from 0 % to 40 % (v/v) Me 2 SO and then reduces significantly. The relative amounts of devitrification to the total ice formation are 0 %, 60 %, 0 % in 20 %, 40 %, 60 % (v/v) Me 2 SO, and 2 %, 48 %, 49 % in 20 %, 40 %, 60 % (v/v) glycerol, respectively. The results suggest that at low concentrations, such as below 20 % (v/v) for Me 2 SO or glycerol, increasing the warming rate after ultra-rapid freezing is not essential to eliminate devitrification. Furthermore, ice blocking polymers do not reduce ice formation substantially and cannot eliminate devitrification under ultra-rapid cooling conditions. In conclusion, our results provide insights into the impact of solute concentration on ice formation and devitrification during rapid cooling, which can be practical for optimizing cryopreservation protocols. [ABSTRACT FROM AUTHOR]

Using a thermodynamic database approach (CALPHAD), thermodynamic parameters of crystal growth of 31 stoichiometric and non-stoichiometric glasses are calculated. Together with these parameters, the measured growth rates, taken from both literature and in-house measurements, are interpreted in the framework of four interface-controlled growth models: normal, screw-dislocation, 2D growth and a combination of the latter two. A multiple linear regression model is used to explain the maximum crystal growth rate and viscosity at the liquidus temperature with the above growth mechanisms. This finding seems to reflect a general trend and can therefore be used to avoid unintentional devitrification phenomena or to derive their temperature-time range based on the sole knowledge of glass viscosity and liquidus temperature. In future research, it can also help to reduce the experimental workload required for the development of novel glasses and glass-ceramics. [Display omitted] [ABSTRACT FROM AUTHOR]

The process of the devitrification of copper nanoparticles in vacuum and in a silver shell during heating was studied using a molecular dynamics simulation. The results show that there is an inverse relationship between the particle diameter and devitrification temperature. As the size of the particles decreases, the temperature at which devitrification occurs increases due to a higher fraction of atoms near the interface. The presence of a silver shell leads to a significant increase in the devitrification temperature of the copper nanoparticles. For the considered particle sizes, the difference between the devitrification temperatures without a shell and with a shell ranged from 130 K for copper particles with a diameter of 11 nm to 250 K for 3 nm particles. The mechanisms of the nucleation of a crystalline phase in particles in vacuum and in a silver shell are significantly different. In the first case, crystalline nuclei are predominantly formed near the surface, while in the second case, on the contrary, they are formed within the particle’s volume.

Changes in bulk crystallization behavior following devitrification at high pressure are investigated for a Fe78B13Si9 composition metallic glass using in-situ energy dispersive x-ray powder diffraction. Crystallization with time was evaluated for a series of measurements to a maximum pressure of 5.63 ± 0.15 GPa for the Fe78B13Si9 glass. Pressure was found to strongly affect onset bulk crystallization temperature Tx. Crystallization at each pressure was found to progress in two stages. In the first stage, α-Fe precipitates and in the second Fe2B forms while α-Fe continues to crystallize. Complementary high pressure room temperature studies were conducted. [ABSTRACT FROM AUTHOR]

The heat capacity–temperature dependence for a fourth-generation carbosilane dendrimer with terminal trimethylsilylsiloxane groups is determined via adiabatic vacuum calorimetry in the 5–344 K range of temperatures and differential scanning calorimetry in the 310–560 K range of temperatures. An anomalous change in the heat capacity of the dendrimers in the range of T = 46–68 K is detected along with a transition in the range of T = 179–196 K, due to its devitrification. The thermodynamic characteristics of the detected transformations are determined and analyzed. The standard thermodynamic functions of the studied dendrimers in the range T → 0 to 560 K and the standard entropy of its formation at T = 298.15 K are calculated using the obtained experimental data. A comparative analysis is performed of the thermodynamic properties of fourth-generation dendrimers that differ in the nature of their molecular skeletons and terminal groups. [ABSTRACT FROM AUTHOR]

The characterization of diopside –based glass of the composition Cu0.50Ca0.75Mg0.75Si2O6 containing small additions of Cr2O3 or TiO2 was explored. The techniques used for the characterization process include AC conductivity (σac), X-ray diffraction (XRD) and Scanning electron microscopy (SEM). However, the prepared dark green glasses show very little devitrification of traces diopside, cuprite and tenorite. The SEM shows a massive structure at the nanoscale with little scattered clusters of nano crystals of the latter phases. The σac was measured within the frequency range of 0.042 kHz −1 MHz and at the temperature range of 298–573 (K). The electrical conductivity measurements proved that the incorporation of Cr2O3 and TiO2 results in higher conductivity values than those of the free glass sample. The activation energy of each of these glasses was estimated at high temperature range. The calculated activation energy values measured at 100 kHz and 1 MHz of the glass samples lie in the range 0.55–0.98 (eV). The prepared glass samples exhibited semiconducting nature. [ABSTRACT FROM AUTHOR]

The characterization of diopside –based glass of the composition Cu0.50Ca0.75Mg0.75Si2O6 containing small additions of Cr2O3 or TiO2 was explored. The techniques used for the characterization process include AC conductivity (σac), X-ray diffraction (XRD) and Scanning electron microscopy (SEM). However, the prepared dark green glasses show very little devitrification of traces diopside, cuprite and tenorite. The SEM shows a massive structure at the nanoscale with little scattered clusters of nano crystals of the latter phases. The σac was measured within the frequency range of 0.042 kHz −1 MHz and at the temperature range of 298–573 (K). The electrical conductivity measurements proved that the incorporation of Cr2O3 and TiO2 results in higher conductivity values than those of the free glass sample. The activation energy of each of these glasses was estimated at high temperature range. The calculated activation energy values measured at 100 kHz and 1 MHz of the glass samples lie in the range 0.55–0.98 (eV). The prepared glass samples exhibited semiconducting nature. [ABSTRACT FROM AUTHOR]

Gene therapies delivered using adeno-associated virus (AAV) vectors are showing promise for many diseases. Frozen AAV drug products are exposed to freeze-thaw (F/T) cycles during manufacturing, storage, and distribution. In this work we studied the mechanisms of AAV capsid rupture during F/T. We found that exposure to interfaces, exacerbated by F/T, and the mechanical force of excipient devitrification correlated with AAV capsid rupture during F/T. There was no impact of pH shifts, cryo-concentration, or cold-denaturation. Results were similar for AAV8 and AAV9. With these mechanistic insights we identified three formulation mitigation approaches. Addition of ≥0.0005% w/v poloxamer 188 (P188) eliminated substantial recovery losses (up to ∼60% without P188) and minimized rupture to ≤1% per F/T cycle. Elimination of exothermic devitrification events during rewarming, either by formulating with a low buffer concentration, or by adding a cryoprotectant further reduced rupture during F/T. Rupture of AAV9 was <0.2% per F/T cycle in a formulation with 1 mM phosphate, 4.4 mM dextrose, electrolytes, and 0.001% P188 at pH 7.2. Rupture of AAV8 was not detected when formulated with 4% sucrose, 100 mM salt, and 0.001% P188 at pH 7.4. These results provide insights into effective strategies for stabilizing AAVs against rupture during F/T. [Display omitted]. [ABSTRACT FROM AUTHOR]

Magmatic origin of analcime has been discussed for decades (e. g., Karlsson and Clayton 1991, 1993; Pearce 1993). Despite the fact that analcime has been re-classified as zeolite and its secondary (post-magmatic) origin is globally accepted (e. g., Roux and Hamilton 1976, Giannetti and Masi 1989, Wilkinson and Hensel 1994), it is still commonly used in classification of alkaline rocks in the Czech Republic. In these rocks, analcime can be mostly found in the pseudomorphs after leucite (Fig. 1a; see Rapprich 2003), or as a homogeneous anhedral filling in the groundmass (Fig. 1b). In the second case, the boundaries of individual analcime crystals cannot be identified due to the isotropic optical properties of analcime. Therefore, origin and growth of analcime is difficult to reconstruct. For this contribution, we have studied samples of Mesozoic and Cenozoic alkaline rocks from three localities across the Czech Republic, where partly analcimized glass in the groundmass was preserved, with an aim to better understand the origin of analcime in alkaline rocks. Mesozoic augitite from the southwestern slope of the Petřkovice Mt. near Nový Jičín (sample TG05) displays small isometric colourless, optically isotropic domains (analcime) enclosed in originally glassy groundmass (Fig. 1c-f). This texture suggests the analcime is replacing original glass in the groundmass, enclosing also microcrysts of the stable minerals in groundmass. Very similar texture was observed also in Oligocene augitite from Mětikalov in Doupovské hory Mts. (sample DR338, Fig. 2). In this rock, the analcime domains either mantle larger phenocrysts, or are distributed within the groundmass. The growth of the analcime domains on the edges of larger phenocrysts resembles growth of spherulites, which represent products of silica-rich glass recrystallization (e. g., Breitkreuz 2013). To further investigate this possibility, additional samples were collected from Kamenický vrch near Zákupy (Fig. 3). In individual samples, number and size of analcime domains vary, which suggests, that these domains represent various stages of a continuous growth. The X-ray elemental mapping of Al and Na (Fig. 4) then shows, that the analcime domains are represented by single grains of cubic analcime. As a result, we may conclude that analcime in groundmass of Mesozoic and Cenozoic alkaline rocks originates from devitrification of original glass. These rocks hence should not be classified as "analcimites" or "analcimic ..." but rather as "analcimized ..." according to Le Maitre et al. (2005). [ABSTRACT FROM AUTHOR]

Recently, we proposed a low-glycerol cryoprotectant formulation (consisting of 0.4 M trehalose and 5% glycerol) for cryopreservation of human red blood cells (RBCs), which greatly reduced the concentration of glycerol, minimized intracellular ice damage, and achieved high recovery. Although this study was successful in cellular experiments, the nonequilibrium phase transition behaviors of the cryoprotective agent solution have not been systematically analyzed. Therefore, it is essential to provide reliable thermodynamic data to substantiate the viability of this cryopreservation technique. In this study, the phase change behaviors and thermal properties of typical trehalose and/or glycerol solutions quenched in liquid nitrogen were investigated using differential scanning calorimetry and cryomicroscopy. It was found that the glass transition temperatures of both the trehalose aqueous solution (<1.0 M) and glycerol aqueous solution (<40% w/v) did not vary apparently with the concentration at low concentrations, while they increased significantly with increasing concentration at high concentrations. Moreover, it was revealed that the inhibitory effect of trehalose on ice growth was affected by glycerol. We further found that the addition of low concentrations of glycerol facilitates the partial glass transition of trehalose solutions at low concentrations. The results of this work provide reliable thermodynamic data to support the cryopreservation of human RBCs with unusually low concentrations of glycerol.

Supercooling during the freezing of pharmaceutical solutions often leads to suboptimal freeze-drying results, such as long primary drying times or a collapse in the cake structure. Thermal treatment of the frozen solution, known as annealing, can improve those issues by influencing properties such as the pore size and collapse temperature of the lyophilisate. In this study we aimed to show that annealing causes a rearrangement of water molecules between ice crystals, as well as between the freeze-concentrated amorphous matrix and the crystalline ice phase in a frozen binary aqueous solution. Ice crystal sizes, as well as volume fractions of the crystalline and amorphous phases of 10% (w/w) sucrose and trehalose solutions, were quantified after annealing using freeze-drying microscopy and image labelling. Depending on the annealing time and temperature, the amorphous phase was shown to decrease its volume due to the crystallisation of vitreous water (i.e., glassy state relaxation) while the crystalline phase was undergoing coarsening (i.e., Ostwald ripening). These results allow, for the first time, a quantitative comparison of the two phenomena. It was demonstrated that glassy state relaxation and Ostwald ripening, although occurring simultaneously, are distinct processes that follow different kinetics. [ABSTRACT FROM AUTHOR]

Magnesium aluminosilicate glass-ceramics are one of the important glass-ceramics with good mechanical performance. However, most of these magnesium aluminosilicate glass-ceramics are colored and non-transparent. In this work, transparent magnesium aluminosilicate glass-ceramics containing ZrO 2 are investigated. Devitrification of these magnesium aluminosilicate glass-ceramics is investigated using thermal analysis, X-ray diffraction, Raman spectroscopy, transmission electron microscope, transmission spectra, and Vickers hardness. It is found that crystals precipitated in these glasses and transparency of the glass-ceramics are strongly affected by the concentration of ZrO 2. Magnesium aluminosilicate glass-ceramics are found to be nontransparent when the ZrO 2 concentration is lower than 6.45 mol.%. With the increase in heat-treatment temperature ZrO 2 nanocrystals, MgAl 2 O 4 nanocrystals, and Al 6 Si 2 O 13 nanocrystals are sequentially precipitated, and Vickers hardness as high as 9.2 GPa are realized in glass-ceramics containing 7.19 mol.% ZrO 2. [ABSTRACT FROM AUTHOR]

The microstructure evolution of amorphous FeCrAlTiMo coatings during annealing process, and the effects of structural relaxation and crystallization on its mechanical properties and LBE corrosion resistance are systematically investigated. With increasing annealing temperatures, three coatings with different microstructure, including relaxation and crystallization, could be obtained. The structural relaxation is beneficial to improve the LBE corrosion resistance of the coating, but it is accompanied by the loss of mechanical properties (interface bonding strength and wear resistance). The crystalline coating with multi-phase microstructure of BCC, FCC and HCP (<2％) exhibits the best LBE corrosion resistance and mechanical properties. • The relaxed and crystalline FeCrAlTiMo coatings are obtained after specific annealing • Structural relaxation is beneficial to improve the LBE corrosion resistance, but it is accompanied by the loss of mechanical properties • The crystalline coating with the multi-phase microstructure of BCC, FCC and HCP (<2％) exhibits the best LBE corrosion resistance and mechanical properties [ABSTRACT FROM AUTHOR]

The formation of Nickel-di-silicide inclusions in silicon whiskers grown during low temperature Ni Metal Induced Lateral Crystallization of amorphous Silicon was studied by High Resolution Transmission Electron Microscopy, Scanning Transmission Electron Microscopy, and Electron Energy Loss Spectroscopy. The heat treatment of the samples lasted for 11þ11 days at 413 °C for the first 11 days and 442 °C for the rest of the time. The size of the inclusions ranges from just a few atoms to 15-20 nm. It was shown that the NiSi2 inclusions have the form of tetrahedrons, which are bound by {111} coherent interfaces with the Si matrix. These inclusions are homogeneously distributed along the whiskers, and the Ni percentage incorporated in these is 0.035 at. %. The tetrahedral inclusions are formed by trapping NiSi2 clusters at the Si/NiSi2 interface during whisker growth. [ABSTRACT FROM AUTHOR]

As cryo-EM approaches the physical resolution limits imposed by electron optics and radiation damage, it becomes increasingly urgent to address the issues that impede high-resolution structure determination of biological specimens. One of the persistent problems has been beam-induced movement, which occurs when the specimen is irradiated with high-energy electrons. Beam-induced movement results in image blurring and loss of high-resolution information. It is particularly severe for biological samples in unsupported thin films of vitreous water. By controlled devitrification of conventionally plunge-frozen samples, the suspended film of vitrified water was converted into cubic ice, a polycrystalline, mechanically stable solid. It is shown that compared with vitrified samples, devitrification reduces beam-induced movement in the first 5 e Å−2 of an exposure by a factor of ∼4, substantially enhancing the contribution of the initial, minimally damaged frames to a structure. A 3D apoferritin map reconstructed from the first frames of 20 000 particle images of devitrified samples resolved undamaged side chains. Devitrification of frozen-hydrated specimens helps to overcome beam-induced specimen motion in single-particle cryo-EM, as a further step towards realizing the full potential of cryo-EM for high-resolution structure determination.

• Rapidly quenched CoFe-based alloy was prepared in the form of microwires of different diameters. • Thin wires are well quenched indicated by delayed devitrification temperature. • The thinnest microwire (D m : 70 µm) shows the highest magneto-impedance change with dual peak (DP) which is associated to enhanced circumferential permeability. • Joule annealing enhanced the GMI property due to structural relaxation. • Optimal combination of GMI operating parameters and Joule annealing current density was identified. The investigation addresses the dependence of rapidly quenched (Co 94 Fe 6) 72.5 Si 12.5 B 13 Cr 2 microwire diameters on their phase transformation evidenced during devitrification and consequent giant magneto-impedance (GMI) behavior. Phase segregation / nucleation in thicker microwires as compared to thinner ones were detected through thermal studies. In addition to such nucleation, the stress effect was more pronounced in thinner microwires as evidenced from GMI output. Structural relaxation through Joule annealing further enhanced the properties. Appropriate choice of operating frequency, alternating current and Joule heating current density vis-à-vis microwire diameter is essential for sensor design. [ABSTRACT FROM AUTHOR]

The limited glass forming ability (GFA) poses a pervasive challenge in different metallic glass (MG) systems. This study systematically investigated the GFA of Ni Nb binary alloys, particularly those near the eutectic composition, aiming to explore the intrinsic factors contributing to the disparities in GFA among Ni Nb binary MGs. The relationship between liquid-like atomic structures and resistance to devitrification is thoroughly examined through the application of k -nearest neighbor machine learning methods. The results indicate that the critical diameter of Ni 61 Nb 39 , Ni 61.5 Nb 38.5 , and Ni 62 Nb 38 MGs reaches upto 2 mm. An amorphous-amorphous transition is discerned within Ni Nb MGs exhibiting superior GFAs. These alloys exhibit low thermodynamic driving forces for crystallization, resulting in correspondingly elevated fragility coefficients. Furthermore, the presence of icosahedral-like clusters and the probability density of crystal-like clusters are observed to be intricately linked to GFA and the resistance to crystallization in Ni Nb MGs. The heightened abundance of crystal-like clusters within the liquid-like domain renders the alloy more susceptible to crystallization. Concurrently, icosahedral-like ordered clusters exert a "pinning effect" on the crystal-like regions, effectively inhibiting crystallization. These results collectively shed light on the fundamental nature of glass formation in Ni Nb binary MGs. • The critical diameter of Ni 100- x Nb x (x = 38, 38.5, 39 at.%) MGs reaches upto 2 mm. • An amorphous-amorphous transition is observed in Ni Nb MGs with superior GFAs. • The roles of icosahedral-like and crystal-like clusters in glass formation and crystallization are revealed. [ABSTRACT FROM AUTHOR]

The setup and working principle of a device designed for thermoplastic embossing and investigating rheological changes during fast-resistive heating of bulk metallic glasses (BMGs) is presented. The device was developed and custom-built at the Leibniz Institute for Solid State and Materials Research Dresden (Leibniz IFW Dresden) and is integrated into a universal testing machine. By varying the electrical-current pulse signal, the rate at which BMGs are resistively heated is controlled. Next to temperature and electrical resistance, the displacement of the punch, which penetrates the sample during rapid heating, is monitored. Additional pre-heating controlled by thermocouples allows for stable heating conditions to minimize heat extraction from the resistively heated specimen, which could eventually lead to damage of the device. The main focus of this device is to study fundamental phenomena under kinetic constraints evoked by fast heating conditions and to structure the surface of BMGs by thermoplastic embossing. A case study, which is carried out with Zr52.5Cu17.9Ni14.6Al10Ti5 BMG, demonstrates the device's performance covering heating rate ranges of three magnitudes and the access to rheological changes during the devitrification and subsequent crystallization of the BMG during rapid heating. Furthermore, the present device was successfully used to nanostructure the surface of the BMG at elevated heating rates. [ABSTRACT FROM AUTHOR]

We have investigated laser-patterning and devitrification as a novel method to realize emergent properties in modified regions at the ribbon surface consisting of periodic localized laser spots thermally treated under rapid heating and cooling conditions. Fe-based amorphous ribbons were annealed for systematically varied laser power. Extremely high heating and cooling rates on the order of 108-1010K/s have been estimated by finite element analysis simulations. Observations suggest surface melting followed by rapid solidification fast enough to quench and form an amorphous structure upon cooling. Diffusion of heat occurs from the laser irradiated surface region so that a finite volume of material surrounding this region rises in temperature above the crystallization temperature relevant for conventional isothermal annealing experiments. The underlying mechanism of laser annealing and consequences of heat transients involved are discussed in terms of impacts upon micro/nanostructure, residual stresses, and magnetic domain structure surrounding the laser irradiated region. The study illustrates the potential to exploit spatially optimized phase transformations in a scalable manufacturing process of amorphous and nanocrystalline alloys to locally access otherwise inaccessible extreme heating and cooling rates. [ABSTRACT FROM AUTHOR]

Thick sequences of silicic ignimbrites contain complex emplacement and cooling histories, often masking contacts between ignimbrite flow packages. Mineralogical and textural variations in these sequences are primarily a function of emplacement temperature and cooling time. Here, we focus on the use of the silica polymorph tridymite to understand the association of vapor-phase crystallization and devitrification within ignimbrite flow packages. As opposed to the common occurrence of cristobalite, the restricted domains in which we observe tridymite may provide more relevant constraints for interpreting post-emplacement devitrification and vapor-phase alteration. This study examines sections through the Whakamaru (New Zealand), Bishop (U.S.A.), and Grey's Landing (U.S.A.) ignimbrites by combining textural observations with measurements of density, groundmass crystallinity, and the distribution and proportion of tridymite to cristobalite. The rheomorphic Grey's Landing ignimbrite represents a high-temperature end-member scenario, with widely distributed tridymite (up to 20%) resulting from a high-magmatic temperature and rapid devitrification in a low-porosity deposit. In the welded Whakamaru and Bishop ignimbrites, metastable tridymite (up to 13%) is concentrated along boundaries between flow packages. Here tridymite is interpreted to crystallize in transient permeable zones, forming during vapor-phase alteration prior to compaction, where upper denser-welded flow materials serve as vapor seals. Our results suggest that tridymite may link the initial cooling and welding history of ignimbrites to vapor-phase alteration and devitrification, and may serve as a potential mineralogical fingerprint of depositional contacts, important for consideration of lateral transport of fluids in geothermal reservoirs. [ABSTRACT FROM AUTHOR]

The successful rewarming of cryopreserved organs has always been a big challenge for the cryopreservation technology aimed at improving the shortage of available organs for transplantation. The traditional water bath rewarming produces more obvious devitrification and thermal stress damages, resulting in negative effects on the organ structure and physiological function. Nanowarming technology via induction heating of iron oxide nanoparticles for rewarming large-volume frozen biosamples is a promising strategy to overcome related problems. In this study, Fe3O4 nanoparticles modified with carboxylic acid are used for nanowarming to rewarm the whole frozen kidney. The key steps including loading and elution of the cryoprotectant and magnetic nanoparticles (mNPs), vitrification of large-volume samples, and nanowarming of the whole kidney are explored in detail to achieve whole kidneys with a more integrated structure. Compared with water bath thawing, the nanowarming method could reduce the maximum thermal stress of the whole kidney by 2 orders of magnitude and has enough rewarming rate to avoid the devitrification phenomenon, so as to obtain a lower cell apoptosis rate, a more integrated vascular network, and a lower residual amount of mNPs inside the kidneys after elution. The optimization of the nanowarming method for the whole kidney could provide effective guidance for the large organ cryopreservation in clinical transplantation. [ABSTRACT FROM AUTHOR]

The article discusses problems of migration, sorption, and redistribution of uranium in felsic volcanic rocks (ignimbrites) and volcanic glasses of different compositions from the Tulukuev and Novogodnee deposits, located at the upper structural level (the cover of volcano-sedimentary rocks) of the Streltsovka caldera, which hosts Russia's largest Streltsovka uranium ore field (SOF). The research covers the entire sorption series of rocks and minerals: from abnormally high uranium contents in felsic volcanic rocks and volcanic glasses of the Novogodnee deposit, located in a reducing geochemical environment, to complete uranium removal from mineral concentrators in an oxidizing environment in the Tulukuevsky open pit deposit. The uranium distribution and variations in its content were studied using f-radiography in different zones of metasomatic aureoles, minerals, rock fragments, the matrix and fiamme of ignimbrites, elements of deformational alterations, including mineralized and open fractures of different morphology, as well as in cataclasis, microbrecciation, and veinlet zones, etc. Integrated geological-structural, mineralogical-geochemical, and petrophysical studies and hydrogeochemical and isotope-geochemical monitoring studies of fracture-vein and atmospheric waters have been conducted since 2000 and continue at present. It is shown that the Tulukuev and Novogodnee deposits are unique objects, which can be used for studying the conditions, migration paths, migration mechanisms, and accumulation of uranium in different structural settings under varying redox conditions. It was established that the most important mechanism of uranium retardation is sorption processes on permeable reaction barriers under reducing conditions, formed currently within hydraulically active faults, crosscutting blocks of oxidized rocks. At these natural physicochemical barriers, U(VI) is effectively retained and transformed into insoluble U(IV) form due to the reactivity of Fe–Mn oxyhydroxides, impregnated carbonaceous matter, and vital activity products of microorganisms (ferrihydrides). Comparing the sorption capacity of minerals with respect to uranium allowed us to develop a comparative series of minerals and mineral aggregates in descending order from amorphous Fe and Ti oxides to feldspar and quartz. The above studies can be used when substantiating the search, exploration, and mining of uranium ores at uranium-ore deposits and when considering possible sources of ore matter. The radiogeoecological aspect of surveys involved with substantiating the long-term isolation of radioactive materials and remediation of radionuclide-polluted areas and groundwater horizons is also crucial. [ABSTRACT FROM AUTHOR]