Liquid Research Articles

Efficient mapping of phase diagrams with conditional Boltzmann Generators

Abstract The accurate prediction of phase diagrams is of central importance for both the fundamental understanding of materials as well as for technological applications in material sciences. However, the computational prediction of the relative stability between phases based on their free energy is a daunting task, as traditional free energy estimators require a large amount of simulation data to obtain uncorrelated equilibrium samples over a grid of thermodynamic states. In this work, we develop deep generative machine learning models based on the Boltzmann Generator approach for entire phase diagrams, employing normalizing flows conditioned on the thermodynamic states, e.g., temperature and pressure, that they map to. By training a single normalizing flow to transform the equilibrium distribution sampled at only one reference thermodynamic state to a wide range of target temperatures and pressures, we can efficiently generate equilibrium samples across the entire phase diagram. Using a permutation-equivariant architecture allows us, thereby, to treat solid and liquid phases on the same footing. We demonstrate our approach by predicting the solid-liquid coexistence line for a Lennard-Jones system in excellent agreement with state-of-the-art free energy methods while significantly reducing the number of energy evaluations needed.

Two-stage assembly of patchy ellipses: From bent-core particles to liquid crystal analogs.

We investigate the two-dimensional behavior of colloidal patchy ellipsoids specifically designed to follow a two-step assembly process from the monomer state to mesoscopic liquid-crystal phases via the formation of the so-called bent-core units at the intermediate stage. Our model comprises a binary mixture of ellipses interacting via the Gay-Berne potential and decorated by surface patches, with the binary components being mirror-image variants of each other-referred to as left-handed and right-handed ellipses according to the position of their patches. The surface patches are designed so as in the first stage of the assembly the monomers form bent-cores units, i.e., V-shaped dimers with a specific bent angle. The Gay-Berne interactions, which act between the ellipses, drive the dimers to subsequently form the characteristic phase observed in bent-core liquid crystals. We numerically investigate-by means of both Molecular Dynamics and Monte Carlo simulations-the described two-step process: we first optimize a target bent-core unit and then fully characterize its state diagram in temperature and density, defining the regions where the different liquid crystalline phases dominate.

Chiral hydroxypropyl cellulose and nanocellulose liquid crystal structural and phase behavior elucidation and their photonic elastomer advanced manufacturing – A Review

Chiral hydroxypropyl cellulose and nanocellulose liquid crystal structural and phase behavior elucidation and their photonic elastomer advanced manufacturing – A Review

Anomalous release of indoles from amorphous solid dispersion formed with a polymeric network

AbstractAmorphous solid dispersion (ASDs) is a technique used in the pharmaceutical industry to enhance the solubility, dissolution rate, and bioavailability of poorly soluble drugs. Polymeric materials, and recently polymer gels form and stabilize the amorphous structure by inhibiting the aggregation/precipitation of such drugs. In this work indole, 5-aminoindole and 5-hydroxyindole loaded poly (N-isopropylacrylamide) (PNIPA) hydrogels were studied. Swelling and uptake measurements, X-ray diffraction (XRD), liquid and solid phase nuclear magnetic spectroscopy (NMR) and high sensitivity differential scanning calorimetry (DSC) were applied to understand the drug – matrix interactions affecting the release. We confirmed that the hydrogel fostered the fine uniform distribution of the hydrophobic probe molecules and successfully prevented any crystalline or amorphous phase formation during water removal, leading to a glassy solution, a special form of ASD. Despite the limited difference between their chemical composition the probe molecules showed dissimilar drug release behavior from dried loaded gel disks. While Nuclear Overhauser Enhancement Spectroscopy (NOESY) measurements revealed a “bidental” interaction between 5-hydroxiindole and the polymer, no localized interactions were found for indole. The release of the bidentally linked derivatives is rapid and complete: they act as molecular spacers, promoting the rehydration of the chains. In contrast, part of the indole remains irreversibly trapped being confined between the chains without any orientation, shedding light on the role of the steric consequences of the interaction. Our findings also indicate that such drug delivery compositions should be treated as ternary systems (carrier + drug + liquid) already in the design stages of drug release systems.

Detection of Two-Phase Slug Flow Film Thickness by Ultrasonic Reflection

Slug flow is a common phenomenon in closed pipes, occurring in two-phase flow where liquid and gas phases mix, impacting the custody transfer or the efficiency of chemical reactions. This study aims to detect and analyze slug flow film thickness in two-phase flow, providing detailed structural flow information. The ultrasonic or Doppler reflection method is employed to identify slug flow and detect detailed thickness. Additionally, electrical resistance tomography (ERT) is used to image and confirm the presence of slug flow. A high-speed camera records the slug flow's shape in real time, validating its existence. The ultrasonic reflection method offers high accuracy, with a measurement error rate of less than 1% based on experimental results. The study uses a homogeneous block calibration method to measure slug flow thickness. Graphical results reveal clear differences between the slug flow regime, inner pipe wall, and outer pipe wall, with the first echo of slug flow being easily observable. The accuracy of results is attributed to the combination of FPGA (Field-Programmable-Gate-Array) instruments and measurement methods, showcasing the study's novel approach. This research introduces a new perspective or novelty on slug flow in multiphase flow studies, highlighting an innovative method for detecting film thickness.

Experimental investigation of CO2 capture at high pressure using energy-efficient amino acid salt solvents

The increase in energy consumption has led to greenhouse gas emissions, specifically CO2. This has caused many researchers to explore the possibility of capturing CO2 emissions. The utilization of typical water-based solvents, such as amine solutions, poses challenges in large-scale operations owing to the substantial energy consumption associated with their regeneration process. To decrease the energy required to regenerate the solvent, new types of phase change solvents, known as lean water amino acid-based phase change solvents, were invented. This study investigated the absorption capacity of an amino acid salt made up of glutamine and potassium hydroxide in a water-based solution including N,N-dimethylformamide (DMF) as a co-solvent. The measurement of absorption capacity was conducted under elevated pressures ranging from 5 to 30 bar. Additionally, an investigation was conducted to assess the impact of DMF volumetric concentration on absorption capacity. The findings of the study indicated that augmenting both the pressure and concentration of DMF increased the capacity for CO2 absorption. This enhancement was achieved by simultaneously raising the rates of physical and chemical absorption. The results obtained from the C NMR phase analysis revealed that the solid phase had carbon bonds that were related to the absorption of CO2, whilst the upper liquid phase did not contain any CO2. This phase might readily be recycled into the absorption process without the need for regeneration. The absorption capacity of this solvent was also assessed following three absorption-reduction cycles. The results indicated a decrease in absorption capacity by only 6.6 %.

Exact analytical solution of the equations for a quasiequilibrium two-phase domain: permeability and interdendritic spacing

This study is concerned with the theoretical description of a quasi-stationary process of directional crystallization of binary melts and solutions in the presence of a quasi-equilibrium two-phase region. The quasi-equilibrium process is ensured by the fact that the system supercooling is almost completely compensated by heat released during the phase transformation. Quasi-stationarity of the process determining constancy of the crystallization rate is ensured by given temperature gradients in the solid and liquid phases. The system of heat and mass transfer equations and boundary conditions to them under these assumptions is dependent on a single spatial variable in the reference frame moving with the crystallization rate relative to a laboratory coordinate system. Exact analytical solutions to the formulated problem in parametric form are obtained. The parameter of the solution is the solid phase fraction in a two-phase region. The distributions of temperature and impurity concentration in the solid, liquid and two-phase regions of the crystallizing system, the rate of solidification, and the spatial coordinate in the two-phase region depending on the solid phase fraction in it are found. An algebraic equation for the solid phase fraction at the interface between the solid material and the two-phase region is derived. Exact analytical solutions show that the impurity concentration in the two-phase layer increases as the solid phase fraction increases. Moreover, the solid phase fraction at the interface solid phase — two phase region and its thickness increase as the temperature gradient in the solid phase and the solidification rate increase. The developed theory allows us to determine analytically the permeability of the two-phase region and a characteristic interdendritic spacing in it. Analytical solutions show that the relative permeability in the two-phase region increases from a certain value at the interface with the solid phase to unity at the interface with the liquid phase. The selection theory of stable dendritic growth allows us to determine analytically a characteristic interdendritic distance in the two-phase layer that decreases as the temperature gradient in the solid phase increases. An increase of impurity in the molten phase gives a decrease in the interdendritic spacing within a two-phase region.

Purification effect of pyrolyzed filler on the flammability of polylactide matrix

Abstract Research efforts are underway around the world to develop efficient recycling of the continuous phase of polymer composites toward reuse. It has already been demonstrated that pyrolyzed filler (PF) can be successfully used as a flame retardant for synthetic polyesters, including recycled ones. Therefore, the purpose of this work was to test the effect of PF on the flammability and thermal properties of the biopolyester phase. For this purpose, the pyrolysis technique was used, which yields a valuable solid phase in addition to the gas and liquid phases. To effectively give it a second life, a proprietary method of modifying the filler recovered by pyrolysis was developed to effectively separate and remove an organic part in the form of a layer of amorphous carbon (a-C), which acts as a universal sorbent. For this purpose, the a-C phase was extracted using binary solvent and replaced it using three types of salts: ammonium salt of benzyl phosphite, 1-butyl-3-methylimidazolium chloride (BMIC), and methyldodecylbenzyl trimethyl ammonium chloride (BMAC). Using a high-temperature processing technique, polylactide composites containing 5% (by weight) additive were obtained. The results of thermal (TGA, DSC) and flammability (PCFC, UL94, LOI) analysis studies show that the use of BMIC and BMAC salts for the intended purpose is particularly promising. The thermal stability of PLA composites containing SF-BMIC and SF-BMAC increased by 30 K and the flammability decreased by 23%. These promising results have opened up new avenues of research toward the synthesis of bio-flame retardants dedicated specifically to polylactide. Graphical abstract

Tandem Methanolysis and Catalytic Transfer Hydrogenolysis of Polyethylene Terephthalate to p‐Xylene over Cu/ZnZrOx Catalysts

We demonstrate a novel approach of utilizing methanol (CH3OH) in a dual role for (1) the methanolysis of polyethylene terephthalate (PET) to form dimethyl terephthalate (DMT) at near‐quantitative yields (~97%) and (2) serving as an in‐situ H2 source for the catalytic transfer hydrogenolysis (CTH) of DMT to p‐xylene (PX, ~63% at 240 °C and 16 h) on a reducible ZnZrOx supported Cu catalyst (i.e., Cu/ZnZrOx). Pre‐ and post‐reaction surface and bulk characterization, along with density functional theory (DFT) computations, explicate the dual role of the metal‐support interface of Cu/ZnZrOx in activating both CH3OH and DMT and facilitating a lower free‐energy pathway for both CH3OH dehydrogenation and DMT hydrogenolysis, compared to Cu supported on a redox‐neutral SiO2 support. Loading studies and thermodynamic calculations showed that, under reaction conditions, CH3OH in the gas phase, rather than in the liquid phase, is critical for CTH of DMT. Interestingly, the Cu/ZnZrOx catalyst was also effective for the methanolysis and hydrogenolysis of C‐C bonds (compared to C‐O bonds for PET) of waste polycarbonate (PC), largely forming xylenol (~38%) and methyl isopropyl anisole (~42%) demonstrating the versatility of this approach toward valorizing a wide range of condensation polymers.

Tandem Methanolysis and Catalytic Transfer Hydrogenolysis of Polyethylene Terephthalate to p-Xylene over Cu/ZnZrOxCatalysts.

We demonstrate a novel approach of utilizing methanol (CH3OH) in a dual role for (1) the methanolysis of polyethylene terephthalate (PET) to form dimethyl terephthalate (DMT) at near-quantitative yields (~97%) and (2) serving as an in-situ H2 source for the catalytic transfer hydrogenolysis (CTH) of DMT to p-xylene (PX, ~63% at 240 °C and 16 h) on a reducible ZnZrOx supported Cu catalyst (i.e., Cu/ZnZrOx). Pre- and post-reaction surface and bulk characterization, along with density functional theory (DFT) computations, explicate the dual role of the metal-support interface of Cu/ZnZrOx in activating both CH3OH and DMT and facilitating a lower free-energy pathway for both CH3OH dehydrogenation and DMT hydrogenolysis, compared to Cu supported on a redox-neutral SiO2 support. Loading studies and thermodynamic calculations showed that, under reaction conditions, CH3OH in the gas phase, rather than in the liquid phase, is critical for CTH of DMT. Interestingly, the Cu/ZnZrOx catalyst was also effective for the methanolysis and hydrogenolysis of C-C bonds (compared to C-O bonds for PET) of waste polycarbonate (PC), largely forming xylenol (~38%) and methyl isopropyl anisole (~42%) demonstrating the versatility of this approach toward valorizing a wide range of condensation polymers.

Direct Steam Generation Methodology in Horizontal Tubes for Parabolic Trough Solar Collectors Designing

Purpose: The present work has the objective to describe the methodology that is been carried out for the optimization of a computational tool for Parabolic Trough Solar Collector (PTC) designing and assessment, the optimization is centered in a new section where de solar collector produces steam directly, named Direct Steam Generation (DSG). Theoretical reference: A PTC collector consist of a sheet with parabolic cross section with a high reflectance surface, at the focus of the parabola is placed a tube whose material must have high thermal conductivity, this tube must be recovered by a selective coating for high solar radiation absorptivity and less emissivity. Surrounding the absorber, a coating transparent tube is placed concentric with high solar radiation transmissivity value. Into the absorber tube, the heat transfer fluid gains energy due to the concentration of the solar radiation giving as a result, a temperature increase at the outlet of the solar collector. Inside the absorber tube, the working fluid considered in this work is water, due to the objective is to produce steam directly. At the first and third section of the tube, preheating and overheating respectively, a full developed single phase flow is considered and the heat transfer depend on the Reynolds number, Prandtl number, the geometry and conductivity of the tube, related on Dittus-Boelter equation. The mayor analysis is located in the evaporation section, because of the flow patterns formation, depending directly on the mass flow and the steam quality, the Froude number indicates the flow pattern formed during the evaporation process, being the stratified and annular flow patterns the most significant. Method: The first version of the computational tool has some limitations: heat transfer fluid doesn´t have phase change, it means, liquid state is maintained, the parabola rim angle is 90° and only one concentric coating tube is considered. The software’s optimization is centered on the PTC collector designing and assessment for direct steam generation system (DSG). For this purpose, the absorber tube is divided into three sections: first for preheating, where water enters to ambient temperature and at the end reaches saturation temperature, at second section, the evaporation process begins with the water in saturated liquid state and ends to saturated steam state and at the third section, steam is superheated reaching the temperature´s condition imposed by the user. At the evaporation section, the heat transfer coefficient depends on the flow patterns formation as well as the pressure drop, where a separated flow model is applied for this analysis. Results and Conclusion: The optimization methodology for a computational tool, that is used for parabolic trough solar collector designing and assessment for direct steam generation system was analyzed. The absorber tube is divided into three segments, the first one for preheating, reaching the water from initial temperature to saturation temperature for the working pressure, the software will find the minimal length for reaching that condition and necessary mass flow is computed. The second step is evaporation, maintaining constant mass flow, evaporation begin when the saturation temperature is reached at the saturated liquid state and finishes at the saturated steam point, and the software find the minimal length for reaching this condition. The most important and complex variable for this section is the heat transfer coefficient, because of the formation of flow patterns, dominating two main phenomena, nucleate boiling and convective boiling, which are determined using the Froude number. Once saturated steam condition is covered, next section overheats the steam and the software finds the minimal length for the final temperature condition dictated by the user, also the quantity of steam produced maintaining constant mass flow condition. Finally, for the two phase flow phenomena carried out at the evaporation zone, the pressure drop is considered, analyzing some methods for frictional pressure drop in two phase flow, Friedel method is recommended due to the applicability and accuracy. Implications of research: The comprehension of PTC designing with DSG system implies a good knowledge of heat transfer in forced two phase flow into circular tubes, as well as pressure drop using a separated flow model. Originality/value: Using the methodology described in this work, the software´s applicability and versatility is enhanced, because of the implementation of another PTC collector configuration, generating steam directly, avoiding the use of great heat exchangers and synthetic oils as working fluids, which implies the reduction in the installation size and diminishing the total installation price.

Numerical evaluation of orientation averages and its application to molecular physics.

In molecular physics, it is often necessary to average over the orientation of molecules when calculating observables, in particular when modeling experiments in the liquid or gas phase. Evaluated in terms of Euler angles, this is closely related to integration over two- or three-dimensional unit spheres, a common problem discussed in numerical analysis. The computational cost of the integration depends significantly on the quadrature method, making the selection of an appropriate method crucial for the feasibility of simulations. After reviewing several classes of spherical quadrature methods in terms of their efficiency and error distribution, we derive guidelines for choosing the best quadrature method for orientation averages and illustrate these with three examples from chiral molecule physics. While Gauss quadratures allow for achieving numerically exact integration for a wide range of applications, other methods offer advantages in specific circumstances. Our guidelines can also be applied to higher-dimensional spherical domains and other geometries. We also present a Python package providing a flexible interface to a variety of quadrature methods.

Preparation and performance study of modified diatomite based PCM for construction

Phase change energy storage technology provides a good solution to the spatial and temporal mismatch of energy use in buildings, but organic solid–liquid phase change materials suitable for the building sector limit their application due to leakage problems. To mitigate the effects of the above problems, diatomite (DME) is designed as the carrier for encapsulation in this experiment. Adsorption performance of DME is improved through double effects of 600°C high-temperature calcination and hydrochloric acid modification. The binary low eutectic mixture was prepared by co-melting of lauric acid (LA) and octadecyl alcohol (OD) with mass ratio of 70:30. Shape-stabilized composite phase change material (SSCPCM) was prepared by vacuum adsorption method with LA-OD and DME with a mass ratio of 35:65 and the melting temperature and latent heat of SSCPCM are 39.10°C and 54.02 J/g. It was experimentally evaluated that the surface impurities of modified DME under microscopic conditions were removed and LA-OD was uniformly embedded in the micropores of DME, and the prepared SSCPCM was able to maintain a thermal inertia of 39°C with good thermal properties and thermal stability, thus SSCPCM could be used as a building energy-saving material to reduce building energy consumption, in addition to expanding the utilization of inorganic mineral materials.

Geopolymers made using organic bases. Part III: Cast magnesium, yttrium, and zinc aluminosilicate and silicate ceramics

AbstractIt was shown in Part II of this series of articles that geopolymers synthesized with organic bases could be used as precursors to mullite and mullite + glass composites. A natural next step is to determine whether it is possible to synthesize materials outside the Al2O3·SiO2 and alkali oxide·Al2O3·SiO2 phase systems. Hence, the focus of this study was the use of geopolymer‐like processing to make preceramic bodies with magnesium, yttrium, and zinc aluminosilicate and silicate compositions. These preceramics were successfully fired into monolithic bodies of cordierite, mixed yttrium and aluminum silicates, yttrium disilicate, and willemite. The synthesis of these preceramics employed a guanidine silicate solution, a synthetic oxide powder, and in some cases metakaolin to reach the oxide composition of the ceramic. All solidified within 3 days at 20°C or 50°C, depending on the composition. For the first time, this study showed that Y2O3 and ZnO can react with silicate solutions to give some Y‐O‐Si and Zn‐O‐Si bonding analogous to Al‐O‐Si bonding in geopolymers. These results suggest that other silicate compositions may be possible, such as with the rare earth oxides, which might be valuable to process like a geopolymer rather than by traditional ceramic processing. However, the ceramics made here were generally porous due to the expansion of gases within the sample that were trapped by a viscous liquid phase during firing.

Data-driven insights into the properties of liquisolid systems based on machine learning algorithms

Liquisolid systems (LS) represent a formulation approach where liquid drug or its dispersion is transformed into a powder with good flowability and compactibility, leading to enhanced drug dissolution and bioavailability. Many research groups have focused on the preparation and investigation of LS, leading to a higher need for comprehensive evaluation of factors impacting LS characteristics. The aim of this work was to investigate the applicability of machine learning algorithms in the LS evaluation, using data mined from published literature, and provide an insight into critical factors governing the liquisolid system performance.The dataset was prepared using publication search engines and relevant keywords, with a total of 425 formulations included in the database. The database focused on preparation methods, formulation parameters, and liquisolid system characteristics. Subsequently, critical properties of the liquisolid system, i.e. flowability, compact hardness, and drug dissolution, were analyzed using machine learning algorithms, including Gradient Boosting, Adaptive Boosting and Random Forest.In addition to conventional preparation methods and excipients, novel technologies (fluid bed preparation, extrusion/spheronization) and materials (Neusilin®, Fujicalin®, and Syloid®) enhanced the properties of liquisolid systems. The analysis revealed that formulation factors, such as carrier and coating agent type and content, liquid phase load, model drug type and content, as well as preparation method, significantly influenced liquisolid system characteristics. The models developed exhibited high prediction accuracy when applied on test data (higher than 80 %). This indicates that the machine learning models may provide an insight into the critical attributes affecting the LS performance and may be used as a valuable tool in the development and optimization of these samples.

Influence of the gas phase on a large-scale bubble column fluid dynamics: Gas holdup, flow regime transitions, and bubble size distributions

We present the results of an experimental study of a large-diameter bubble column operating in batch mode with air or CO2 as the gas phase and water as the liquid phase. The bubble column has an inner diameter of 0.24 m and is 5.3 m in height. The superficial gas velocity varied between 0.0037 m/s and 0.0233 m/s. The experimental investigation consists of gas holdup measurements and image analysis. Flow regime transitions were detected by gas holdup measurements, and image analysis was used to investigate the bubble size distributions. The results suggest that the homogeneous flow regime is stabilized when CO2 is used as the gas phase. The gas holdup is higher for the CO2-water system at fixed superficial gas velocity, especially in the heterogeneous flow regime. In the homogeneous flow regime, the mean bubble diameter and the fraction of large bubbles are lower for the CO2-water system, explaining the higher gas holdup.

Production of hydroxyapatite utilizing calcium and phosphorus in sewage sludge incineration ash

Sewage sludge incineration ash (SSIA), enriching the most of phosphorus (P), could be named as promising P source for P recycling and management. The novel strategy including extraction of P from SSIA by acid (HCl), purification and separation to obtain Ca liquid and Al-P liquid that could produce hydroxyapatite was investigated in this study. The P acid leaching rate was 97.9 % from SSIA at 0.2 mol/L HCl for 2 h. In P purification, P combined with Fe and Al to form precipitation (Al-P and Fe-P) with the increase of pH (<4.0). At a pH of around 4.0, the separation of Ca in the liquid phase was maximized, while Al-P and Fe-P precipitated out. Then, the Al-P precipitation could be dissolved in NaOH solution (0.2 mol/L) to separate Fe-P precipitation, that obtaining the Al-P liquid. What’s more, the high P content (P2O5, 25.5 %) in P product could be produced directly under 1.5 Ca/P molar ratio, which could be used in P fertilizer. The heavy metal content in the P product were far below the Chinese, American and EU fertilizer regulation, indicating that its environment safety. The Ca and P elements leached out during the acid leaching process were eventually recombined to form hydroxyapatite by wet-chemical purification. The cost of P recovery from SSIA was $3.06/kg P product demonstrating commercial potential of this strategy.

Solvent screening for the purification of monoterpenoids by countercurrent and centrifugal partition chromatography

AbstractBACKGROUNDCountercurrent chromatography (CCC) and centrifugal partition chromatography (CPC) are efficient techniques to purify terpenoids from essential oils. These methods require suitable solvent systems for the partition between the two immiscible liquid phases. In this study, using the analytical shake‐flask method, we measured the partition coefficients of three model monoterpenoids, namely carvone, eucalyptol and thymol, in 11 biphasic solvent systems, at 298.2 K. Moreover, the predictive COSMO‐RS model was applied to represent the partition coefficients of data measured in this work and retrieved from the literature, the liquid–liquid equilibrium (LLE) data of three solvent families suitable for CCC/CPC separations (i.e., Arizona, Modified Arizona and Green Arizona) and the solute's partition coefficients in the three solvent families.RESULTSThe partition coefficients obtained for thymol and eucalyptol are the first partition data available in the literature. The obtained root mean square deviations (RMSDs) between the experimental and predicted partition coefficients (log basis) varied between 0.28 and 0.49. For LLE, RMSDs of 0.040 and 0.048 were achieved for the Arizona and Green Arizona families, respectively.CONCLUSIONThe predictive COSMO‐RS model describes the monoterpenoid partition coefficients and the LLE data of the solvent families well. The most favorable solvent systems to perform the separations were identified, showing that systems with low and intermediate‐to‐low polarities are the most promising options for separating the selected monoterpenoids from their natural matrices by CCC/CPC techniques. © 2024 Society of Chemical Industry (SCI).

A review of the preparation and prospects of amorphous alloys by mechanical alloying

The preparation of amorphous alloys typically involves rapid solidification from a molten state. Since 1980, when Yermo and Koch first achieved the amorphization of alloys by mechanical alloying (MA), researchers worldwide have developed a strong interest in this technique, which allows for the amorphization of alloy components in a non-equilibrium state at room temperature without the need for a liquid phase. MA has been widely applied in the fabrication of both equilibrium and non-equilibrium materials over the past few decades, and it remains a crucial technique for the production of amorphous alloys. This review selectively summarizes research on MA-produced amorphous alloys reported over the past two decades. It explores key issues of MA amorphization from the perspectives of both the mechanism of amorphization and the design of amorphous compositions through MA. The first section primarily elucidates commonly used methods for designing amorphous compositions at present, while the second section expounds on the transformation mechanism of MA amorphization. The third section summarizes the influence of alloy element additions on its properties, and the fourth section mainly illustrates the contribution of computational advancements to the exploration of amorphous mechanisms and the design of amorphous compositions. Finally, prospects for the development trend of preparing amorphous alloys through MA are discussed.

Thermal conductivity measurements of liquid ethane and ethane + propane binary mixtures

Based on the transient hot-wire apparatus, the thermal conductivity of ethane was measured in the temperature range of 146–247 K and pressure < 14 MPa in the liquid phase. The thermal conductivity of ethane + propane binary mixture was measured in the temperature range of 156–288 K and pressure < 25 MPa in the liquid phase. The mole fractions of ethane in binary systems are 0.198, 0.525, and 0.736. The deviation between experimental results and REFPROP calculation falls within 3 % of ethane and mixture. Subsequently, the previous established thermal conductivity model, derived from dimensional analysis, was employed to predict the thermal conductivity of n-alkanes mixture. The mixture critical parameters were obtained first by the mixing rules, and the thermal conductivity of the mixture were calculated. Comparisons were made between the experimental data of ethane and the previously constructed n-alkane model, resulting in an average absolute relative deviation (AARD) of 4.42 %. Similarly, the experimental data of the ethane + propane mixture was compared with the mixture prediction model proposed in this study, yielding an AARD of 1.92 %. The relative deviation between experimental data and model calculations demonstrates good consistency.