Liquid Phase Transition Research Articles

Liquid structure transition upon cooling of liquid Pd40Ni40P20

The precipitates of nano-crystals during solidification obscured the initiation of structural evolution, which in turn hid the information for the understanding of nucleation. Here, we report an endothermic liquid–liquid phase transition of Pd40Ni40P20 alloy far before the nucleation and verified with the in situ synchrotron radiation high-energy x-ray diffraction method and flash differential scanning calorimetry (DSC) analysis. The variations on structure factor, pair-distribution functions (PDFs) and coordination number proved a typical structure transition happen at around 640 °C. And the results of flash DSC confirmed the phenomenon. The observation verifies the liquid–liquid phase transition before nucleation and deepens the understanding of solidification in atomic scale.

Geometric features in lyotropic liquid crystalline phase transitions observed in aqueous surfactant systems

Lyotropic liquid crystalline phases are widely known to be formed in aqueous surfactant mixtures. Although the phase behavior of several surfactants has been elucidated in the past years, a striking absence of detailed discussion on how molecular geometric parameters vary as different liquid crystals are formed is consistently seen in literature. The current work aimed to partially fill this gap, by determining how several structural parameters changed in a variety of phase transitions previously observed in aqueous surfactant binary and ternary mixtures. The main findings reveal that the cell parameter dimensions are strongly correlated with the packing fraction of small aggregates in each phase; the folding and interpenetration of surfactant hydrocarbon chains are most likely to happen in phases with lower curvature, and can greatly affect other structural parameters; added components can alter the aqueous surfactant phase behavior at different extents; and highly ordered phases are favored by a substantial decrease in the cross-sectional areas per surfactant; among others. The obtained results enable important knowledge on lyotropic liquid crystal formation, in addition to providing detailed information on how to control and obtain such phases, thus prospecting new insights in areas where they are highly desired.

Sustainable and low-cost SUZ-4 synthesis and its application for Cd2+ removal

High value-added utilization of industrial waste is important for environmental protection and sustainability. The objective of this study was to recycle industrial wastes, silica fume (SF) and aluminium ash (AA) as raw materials to substitute chemicals for sustainable and low-cost SUZ-4 zeolite (L-SUZ-4) synthesis in one pot. The synthesis parameters to obtain pure L-SUZ-4 were optimized as xKOH(x = 7.84–9.33):yAl2O3(y = 0.81–1.10):2.6TEAOH:21.2SiO2:zH2O(z = 330.72–712.32) at 150 °C for 96 h. The notably high yield of L-SUZ-4 (up to 85%) indicated that silicon and aluminium species in SF and AA are not only easy to be activated but also liable to be incorporated into the zeolitic framework. Exploration of L-SUZ-4 synthesis process by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) characterizations indicated that the synthesis follows the liquid phase transition mechanism. It can also be observed that the complete dissolution of SF is the rate-determing step during the induction period. Meanwhile, the adsorption ability of L-SUZ-4 for Cd2+ in water was first investigated. A notably maximized adsorption amount (qmax = 263.68 mg/g) of L-SUZ-4 for Cd2+ was obtained, which is higher than the other adsorbents investigated in this work or those described in the literature. The sustainable production and outstanding adsorption performance of L-SUZ-4 make it a very promising adsorbent for heavy metal removal with practical application prospects, which is the typical case of “waste to treat waste”.

Mitochondrial cytochrome c shot towards histone chaperone condensates in the nucleus.

Despite mitochondria being key for the control of cell homeostasis and fate, their role in DNA damage response is usually just regarded as an apoptotic trigger. However, growing evidence points to mitochondrial factors modulating nuclear functions. Remarkably, after DNA damage, cytochrome c (Cc) interacts in the cell nucleus with a variety of well‐known histone chaperones, whose activity is competitively inhibited by the haem protein. As nuclear Cc inhibits the nucleosome assembly/disassembly activity of histone chaperones, it might indeed affect chromatin dynamics and histone deposition on DNA. Several histone chaperones actually interact with Cc Lys residues through their acidic regions, which are also involved in heterotypic interactions leading to liquid–liquid phase transitions responsible for the assembly of nuclear condensates, including heterochromatin. This relies on dynamic histone–DNA interactions that can be modulated by acetylation of specific histone Lys residues. Thus, Cc may have a major regulatory role in DNA repair by fine‐tuning nucleosome assembly activity and likely nuclear condensate formation.

Mechanism research on crack propagation in coal induced by CO2 phase-transition fracturing under different lateral compression coefficients

To study crack propagation around the fracture hole in the coal body induced by high-pressure CO2 gas produced by CO2 phase transition fracturing, the mechanism of permeability enhancement of fractured coal induced by liquid CO2 phase transition fracturing was studied from two aspects, the process of coal gas displacement by competitive adsorption and physical characteristics of fractured coal induced by phase transition. Crack propagation pattern in coal under different lateral coefficients was explored by using discrete-element numerical simulation software. Distribution characteristics of hoop stress of fractured coal were analyzed through theoretical calculation. The results show that: (1) Micro-cracks in damaged coal body generated during phase transition process are mainly crack_tension type, which are formed by the composite action of tension and compression. The crack propagation is the result of the continuous release of compressive stress from concentrated area to the surrounding units. Micro-cracks are radially distributed in a pattern of “flame”. (2) The main crack formed above the fracture hole grows in the direction of vertical minimum initial stress, and the main crack formed below the fracture hole develops in the direction of horizontal initial stress. As the lateral compression coefficient increases, the extension distance of the second crack will not change after reducing to a certain length. (3) As the distance from the fracture hole increases, the peak compression loaded at the monitoring point decays, and the loop stress in the cracked coal is distributed in a pattern of “peanut”. It provides practical methods and ideas for studying the macroscopic and microscopic development of cracks, as well as theoretical support for the on-site hole layout.

Two Liquid-Liquid Phase Transitions in Confined Water Nanofilms.

The stories behind supercooled bulk and confined water can be different. Bulk water has a metastable liquid-liquid phase transition at deeply supercooled conditions, but the existence of such a phenomenon in confined water is in question. Herein we show simulation results of first-order phase transitions between high- and low-density liquid (HDL and LDL) in confined water in both positive and negative pressures. A mid-density state between these two local states appears, which lets the transition show the hysteresis loop with transiently stable intermediate states. On the basis of Landau theory that we have adapted for mixing of moieties with high- and low-density states, we explain the phase transitions with the order parameter-dependent free energy change which is governed by second- to higher-order interactions among those moieties.

In situ neutron scattering studies of a liquid–liquid phase transition in the supercooled liquid of a Zr–Cu–Al–Ag glass-forming alloy

The presence of a liquid–liquid phase transition in the supercooled-liquid temperature range for a glass-forming Zr–Cu–Al–Ag alloy has been revealed using a suite of in situ neutron scattering techniques, including small-angle neutron scattering (SANS) and total neutron scattering. The SANS data analysis is indicative of the enhancement of nanoscale structural heterogeneities prior to crystallization, which is further supported by the total scattering result that points to an increase in the degree of medium-range ordering during the transition. In addition, a calorimetric anomaly and abnormal thermal expansion behavior were also observed upon heating. As such, this study provides multiscale structural evidence on the liquid–liquid phase transition and helps to gain insight into its underlying mechanism in terms of cluster connectivity.

Enthalpic perspective on thermodynamic equilibrium of bulk and confined liquids: A review

Studying liquid transition to other states of matter encounters certain challenges. The phase transition containing a liquid phase embodies energetic change that can be quantitatively correlated to the equilibrium conditions. The challenges can be more complex if the liquid is geometrically confined in a narrow space in which the energetic interaction between the confinement and confined liquid might become more pronounced. Therefore, it is of great essence to probe the enthalpic perspective of an equilibrium in which at least one liquid phase exists. However, the challenges can be used as opportunities to characterize both the confined liquid as well as the confinement material in terms of phase transition, intermolecular interaction, and pore size distribution.In this article, enthalpic studies of liquid phase equilibrium are carefully discussed. The majority of the discussions address the confined thermodynamic equilibrium that includes a liquid phase, especially the liquid phase transition under confinement to and from vapor and solid phases is elaborated in great details. In addition, enthalpic overviews of bulk equilibrium of liquids are briefed where challenges and opportunities to calorimetrically study these equilibrium states are remarked. An integrative and instructive approach is closely followed in order establish a network of information that can be used not only for comprehensively reviewing the existing state-of-the-art, but also for providing invaluable insight and constructive inputs for future studies to bridge the gaps in the field.

Temperature self-regulating electrothermal pseudo-slippery surface for anti-icing

Ice accretion has become an urgent problem and considerably decreases the reliability of aerospace, power network, and transportation equipment. Herein, a temperature self-regulating electrothermal pseudo-slippery surface with intelligent anti-icing ability was introduced by combining electrothermal effect and phase transition lubricant, which exhibits positive temperature coefficient (PTC) effect and interfacial state switching performance. The coating exerts its PTC effect to realize smart temperature accommodation, and automatically regulates its EPD for anti-icing under various cold loads, greatly decreasing the energy consumption of anti-icing by ~ 30% at an initial electric power density of 1.5 W/cm2 (compared with general electrothermal coating) and preventing overheating even at an initial electric power density of 5 W/cm2 without requiring complex regulatory equipment. After heating, the reversible solid to liquid phase transition of the lubricant assisted the switch from pseudo-slippage to slippage of the surface, decreasing ice accretion on the coating (by ~ 40% after icing for 120 s at –40 ± 3 °C). Furthermore, the mechanical function of PTC–ESS was highly stable in continuous humid airflow/sand scour tests. The integration strategy will provide inspiration for designing intelligent anti-icing surfaces and promote their engineering applications.

Photoliquefiable DNA-surfactant ionic crystals: Anhydrous self-healing biomaterials at room temperature

Development of photoliquefiable solid-state biomaterials at room temperature would address scientific challenges in life science. However, external stimuli-induced phase transitions are difficult for some biomacromolecules based materials, due to the high rigidity of these biomolecules. In this present work, by delicate molecule design on azobenzene-type ammonium surfactants, two new types of DNA-surfactant materials are fabricated. At room temperature, these DNA materials show photoliquefaction of ionic crystals to isotropic liquids under UV light, and fast self-assembly from isotropic liquids back to crystals after ceasing UV light, under the assistance of azobenzene isomerization. To achieve this objective, the designed solid-state DNA materials should have melting points near room temperature and an immediate liquid crystal to isotropic liquid transition process just above the melting points, which highly depends on the stoichiometric charge ratio between DNA and surfactants. As proved by the successful self-healing tests, these DNA ionic crystals are good biomaterials with potential applications in biomedicine and life science. This work would provide a new strategy for designing anhydrous functional biomaterials at room temperature by using rigid biomacromolecules. Statement of SignificanceAt room temperature, solid-state biomaterials with photoregulated crystal⇄isotropic liquid phase transition property are attractive functional materials in life science, considering the body temperature and living environment temperature of human beings. Although several kinds of anhydrous materials achieved isothermal photoresponsive phase transitions, the photoregulated phase transition of anhydrous biomacromolecules based materials has not been achieved at room temperature, due to the high rigidity of these biomolecules. In this work, by delicate molecule design on ammonium surfactants, we synthesized two kinds of anhydrous DNA-surfactants ionic crystals. These DNA materials show fast photoliquefaction under UV light and self-assembly after ceasing light, which affords excellent self-healing biomaterials. This work would provide a new strategy for designing anhydrous photoresponsive biomaterials by using rigid biomacromolecules.

Publisher Correction: Solid–liquid phase transition induced electrocatalytic switching from hydrogen evolution to highly selective CO2 reduction

Publisher Correction: Solid–liquid phase transition induced electrocatalytic switching from hydrogen evolution to highly selective CO2 reduction

Semiconductor to metal transition in the solids/melts of Te and pseudo-binary of Hg1−xCdxTe for x = 0, 0.1, and 0.2

This paper reports the experimentally measured thermal and electrical conductivities from which the Lorenz numbers as functions of temperature were derived for the solids and melts of elemental Te and samples of Hg1−xCdxTe of x = 0, 0.1, and 0.2. The structural changes in the vicinity of the solid–liquid phase transition of elemental Te and various Hg1−xCdxTe solid solutions were assessed by closely examining these experimental properties and the derived Lorenz numbers. The values of Lorenz numbers for the solids of these samples were higher than the value of L0, i.e., the Lorenz number for the free-electron gas derived by Sommerfeld [Naturwissenschaften 15, 825 (1927)], implying the characteristics of a non-degenerate semiconductor. With the increasing value of x, or the larger bandgap, the materials become more non-degenerate with larger deviation from L0. As the solids started to melt, the measured values of the Lorenz number for all samples started to decrease and eventually reached and maintained at values close to L0 at higher temperatures. The trend of the Lorenz number indicates the transition from a non-degenerate semiconductor of the solid samples to a metal or degenerate semiconductor when the temperatures of the samples reached above their liquidus temperatures.

Physicochemical Characterization and Simulation of the Solid-Liquid Equilibrium Phase Diagram of Terpene-Based Eutectic Solvent Systems.

The characterization of terpene-based eutectic solvent systems is performed to describe their solid–liquid phase transitions. Physical properties are measured experimentally and compared to computed correlations for deep eutectic solvents (DES) and the percentage relative error er for the density, surface tension, and refractive index is obtained. The thermodynamic parameters, including the degradation, glass transition and crystallization temperatures, are measured using DSC and TGA. Based on these data, the solid–liquid equilibrium phase diagrams are calculated for the ideal case and predictions are made using the semi-predictive UNIFAC and the predictive COSMO RS models, the latter with two different parametrization levels. For each system, the ideal, experimental, and predicted eutectic points are obtained. The deviation from ideality is observed experimentally and using the thermodynamic models for Thymol:Borneol and Thymol:Camphor. In contrast, a negative deviation is observed only experimentally for Menthol:Borneol and Menthol:Camphor. Moreover, the chemical interactions are analyzed using FTIR and 1H-NMR to study the intermolecular hydrogen bonding in the systems.

Hysteretic Control of Near‐infrared Transparency Using a Liquescent Radical Cation

AbstractA liquescent dihydrophenazine radical cation, 1.+⋅NTf2−, showed drastic changes in near‐infrared (near‐IR) transparency and opaqueness through hysteretic phase transitions with no measurable degradation of the compound even under aerated conditions. During the heating and slow cooling process (0.5 K min−1), its electronic and magnetic properties were altered clearly and repeatedly changed between solid and liquid states. The liquid state was transparent to near‐IR light (940 nm), but the solid state was opaque, despite both samples exhibiting a similar green color under room light. Additionally, the liquid state was changed to a glass state under a fast cooling process (2–10 K min−1). UV/Vis/near‐IR and electron spin‐resonance spectroscopy revealed that these drastic changes were attributable to the dynamic dissociation and association of a π‐dimer structure for 1.+ accompanying with the solid–liquid phase transitions even under the neat conditions.

Solid–liquid phase transition induced electrocatalytic switching from hydrogen evolution to highly selective CO2 reduction

Conventional strategies for modifying electrocatalysts for efficient CO2 reduction are mainly based on doping, defect/morphology engineering, substrate design and so on. In most cases, these methods can only tune their structures, electronic states and thereby catalytic properties in a gradual way. Here we report that the solid–liquid phase transition of Ga–Sn/Ga–In alloys can induce an instant and radical transformation of their atomic and electronic structures during electrocatalysis, which dramatically impacts their catalytic properties. The transition of Sn/In active components from phase-segregated clusters to dispersed single atoms during melting results in a unique electronic structure through further reduction of both metallic Sn/In and Ga. Such atomic/electronic structure transitions can correlate well with suppression of the hydrogen evolution reaction and an enhanced formate Faradaic efficiency from 95%. This two-state switching strategy may be extended to other catalytic reactions to determine correlations between their structures and catalytic properties. Common strategies for catalyst design explore ways of fine-tuning continuous structure–property relationships. Here, the abrupt solid–liquid transition of Ga–In and Ga–Sn alloys is shown to have a profound impact on the CO2 electroreduction performance, with the molten alloy achieving a Faradaic efficiency of 95% formate production.

Electrically Induced Liquid–Liquid Phase Transition in a Floating Water Bridge Identified by Refractive Index Variations

A horizontal electrohydrodynamic (EHD) liquid bridge (also known as a “floating water bridge”) is a phenomenon that forms when high voltage DC (kV·cm−1) is applied to pure water in two separate beakers. The bridge, a free-floating connection between the beakers, acts as a cylindrical lens and refracts light. Using an interferometric set-up with a line pattern placed in the background of the bridge, the light passing through is split into a horizontally and a vertically polarized component which are both projected into the image space in front of the bridge with a small vertical offset (shear). Apart from a 100 Hz waviness due to a resonance effect between the power supply and vortical structures at the onset of the bridge, spikes with an increased refractive index moving through the bridge were observed. These spikes can be explained by an electrically induced liquid–liquid phase transition in which the vibrational modes of the water molecules couple coherently.

Liquid–liquid phase transition in molten cerium during shock release

The identification of the liquid–liquid phase transition (LLPT) in liquids under shock compression is a long-standing challenge. In this Letter, by designing shock-release experiments in shock-driven molten Ce, we observe a first-order LLPT along the release path. The volume change associated with the transition is less than 6%, much smaller than the one (14%) obtained in static compression experiments, indicating that the LLPT in molten Ce is strongly rate dependent. The identified timescale for the LLPT is on the order of 200 ns. Our results, therefore, provide kinetic information of the LLPT in an unprecedented manner, which is extremely valuable for the construction of a non-equilibrium phase diagram.

In-vitro development of Nauclea diderrichii (de Willd. & Th. Dur) Merrin liquid-M Smedia supplemented with benzyl amino purine (BAP) and naphthalene acetic acid (NAA)

The growth of plantlets in Temporary Immersion Bioreactor system (TIBs) relies on initial successful liquid phase transition process. The response of N. diderrichii explants was assessed in liquid-M Smedia with a view to mass produce its seedlings using TIBs. Seven treatments consisting (A) 0.0/0.0, (B) 0.0/0.1, (C) 0.1/0.0, (D) 0.2/0.1, (E) 0.3/0.2, (F) 0.4/0.3 and (G) 0.5/0.4mg/lBAP/NAA combinations were studied. Each group consist of seven replicates and group A without Growth Regulators (GR) serves as control. The results at 4 Weeks after Inoculation (WAI) showed that effects of the growth regulators were significant on shoot length and number of adventitious shoots while number of roots and leaves were closely related. Treatment E produced highest number of adventitious shoots (3.6) which was higher than 0.9 shoots from treatment G and closely related to others. Maximum number of leaves (16.6) was produced by treatment F followed by E (15.7) while the least (12) was obtained in treatment A. The highest number of roots (4.9) was obtained from treatments B, followed by E (4.3) with the lowest being recorded in C (2.43). Liquid MS medium supplemented with 0.3/0.2mg/lBAP/NAA shows some promise for plantlets generation for the purpose of multiple shoot production of N. diderrichii in TIBs.

Thermochemical properties of pyrazine derivatives as seminal liquid organic hydrogen carriers for hydrogen storage

This work contributes to our primary interest in applications of experimental and computational thermochemistry methods for providing the basic data required in chemical-process design. Pyrazine derivatives are considered as a seminal liquid organic hydrogen carriers. The standard molar enthalpies of vaporisation/sublimation of pyrazine derivatives were derived from the vapour pressure temperature dependences measured by the static and transpiration method. Enthalpies of fusion of the solid compounds were measured using DSC. Thermodynamic data on solid–gas, liquid–gas, and solid–liquid phase transitions available in the literature were collected and combined with own experimental results. We have evaluated and recommended the set of vaporisation and formation enthalpies of pyrazine derivatives at 298.15 K as the reliable benchmark properties for further thermochemical calculations. Gas phase molar enthalpies of formation of pyrazine derivatives calculated by the high-level quantum-chemical method G4 were in agreement with the recommended experimental data. Compilation of experimental and theoretical results derived in this work is useful for optimisation of hydrogenation/dehydrogenation reactions involved in the hydrogen storage technologies.

Fermi liquid theory sheds light on hot electron-hole liquid in 1L−MoS2

Room-temperature electron-hole liquid has recently been experimentally identified in low-dimensional transition metal dichalcogenides. Here, the authors demonstrate that a first-principles Fermi liquid model effectively predicts the photoluminescence response of this phenomenon. Using density functional theory, in conjunction with previous Raman and photoluminescence spectroscopy results, they present a consistent quantitative picture of the electron-hole liquid phase transition in suspended, heat-strained 1$L$-MoS${}_{2}$ monolayers. They show a 23-fold increase in photoluminescence per unit of direct gap carrier density and 9:1 indirect-direct hole population ratio at high strain.