Search

ABSTRACT In the central sector of the Sanandaj‐Sirjan zone of Iran, the Triassic‐to‐Jurassic ‘Hamedan Phyllites’ metamorphic complex shows a polymetamorphic evolution characterised by a main Barrovian‐ to Buchan‐type garnet+staurolite+kyanite/andalusite regional sequence, locally overprinted by a low‐pressure thermal event generated by vigorous Jurassic magmatic activity and the emplacement of voluminous composite plutonic complexes (e.g., Alvand). In this work, we explore the Hamedan phyllites enveloping the Jurassic Alvand granite batholith, particularly in the eastern sector at the transition from cordierite‐bearing hornfels to staurolite‐bearing schists. In this study, we present for the first time the textural characterisation and mineral chemistry of a previously undescribed minor population of post‐kinematic Mn‐rich garnet from the staurolite schists. We developed phase equilibria modelling to define the pressure‐temperature condition of its genesis. We then integrated the existing literature on metapelites from the study area to develop new thermobarometric models with those data to propose a revised evolution of the metapelites enveloping the Alvand batholith and the extent of its contact aureole. On a wider scale, this study provides evidence for the relevance of garnet, as chemical‐physical archive, in deciphering complex polymetamorphic histories where thermal events affect previously regional metamorphosed rocks under relatively hot gradients. [ABSTRACT FROM AUTHOR]

ABSTRACT Eclogite‐facies rocks provide important constraints on the behaviour of convergent plate boundaries and the geometries of tectonic reconstructions due to the high to ultrahigh pressure conditions at which they form. Many eclogite occurrences are documented near the suture zone of active collisional settings where they are interpreted to mark the approximate location of former ocean basin subduction. Such observations influence tectonic interpretations for older eclogites within more deeply eroded and/or less well‐exposed terranes. The eclogitic Glenelg inlier in northwest Scotland is one such example, with c. 1 Ga eclogites having previously been interpreted as marking the trace of a Grenville‐aged collisional suture zone that defines a third ‘arm’ to the Grenville orogen alongside well‐defined sutures in North America and Scandinavia. Here we use a combination of geochronology, phase equilibrium modelling and accessory‐phase thermometry to show that the eclogite‐facies assemblages were produced at ∼$$ \sim $$18–19 kbar and 700°C–750°C from c. 1.1 to 1.0 Ga. Accounting for the foreland basin setting of equivalent‐aged sedimentary rocks in the region and demonstrating the thermal viability of this setting, we show that eclogite formation occurred in deforming foreland crust adjacent to the Grenville orogen, in a setting broadly analogous to fault‐bounded basement uplifts in the forelands of active deformation belts, such as the Himalayas and Andes. Our results demonstrate that eclogite‐facies rocks can form in a greater range of tectonic settings than are sometimes considered, with implications for tectonic reconstructions of collisional zones. In this instance, our results remove the need for a third ‘arm’ of the Grenville orogen by placing Glenelg in a foreland setting, reconciling the absence of plentiful Grenville‐aged metamorphic rocks in northwest Scotland, the sedimentological record and paleomagnetic data in the wider region. [ABSTRACT FROM AUTHOR]

ABSTRACT Petrochronological investigations of granulite‐facies metapelitic rocks from the eastern contact of the Closepet granite in the Central Dharwar Craton (CDC), southern India, provide new pressure–temperature–age (P–T–t) constraints on two seemingly discrete Archean metamorphic events during the Neoarchean and late Paleoarchean eras. Phase equilibrium modelling and conventional thermobarometry coupled with in situ monazite and garnet geochronology constrain Neoarchean (ultrahigh‐temperature; UHT) metamorphic peak conditions to ~930 °C and ~6.7 kbar at c. 2.63 Ga, then cooling and limited decompression to ~5.7 kbar at ≤810 °C. Monazite inclusions in garnet least affected by Neoarchean recrystallisation have distinct positive Eu anomalies and yield ages of c. 3.2 Ga, whereas garnet cores interpreted to have grown at the same time have slightly younger apparent ages of c. 3.1 Ga. We interpret this age mismatch to be the result of extensive resorption of garnet during Neoarchean UHT metamorphism, which led to widespread modification of the initial Lu–Hf systematics in garnet to produce younger apparent ages. The effect of retention and inward intracrystalline diffusion of Lu on the isotopic composition of garnet is most pronounced close to the resorbed grain margins and decreases towards the core, as reflected by progressively younger apparent single‐spot garnet dates from core to rim. Despite extensive overprinting of the sample at c. 2.63 Ga, the trace element composition of Paleoarchean monazite indicates growth in equilibrium with garnet but in the absence of feldspar, which is predicted to occur over a broad stability range at P ≥ 8 kbar and T ≤ 700 °C. Such P–T conditions are uncommon in the metamorphic rock record prior to the Neoarchean, but are typical of Barrovian‐type metamorphism, which is considered to be an expression of accretionary‐to‐collisional orogenesis. Rocks of similar age and metamorphic grade have been reported from the core of the Western Dharwar Craton (WDC) and may reflect regional subduction at the margins of the CDC and WDC since the late Paleoarchean. Neoarchean UHT metamorphism in the Dharwar Craton is coeval with a cluster of other UHT occurrences at 2.7–2.6 Ga, indicating the existence of globally elevated thermal gradients at that time. [ABSTRACT FROM AUTHOR]

This study investigates the thermodynamic characteristics, equilibrium solubility, and solvation dynamics of sildenafil citrate within binary solvent systems composed of propylene glycol and 1-propanol. Utilizing both determination and computational approaches, the solubility patterns of sildenafil citrate were quantitatively assessed, revealing direct proportionality with increments in temperature and the concentration of propylene glycol. A comparative analysis using three distinct mathematical models to represent the solid–liquid phase equilibrium was conducted. Among these, the Jouyban-Acree-van’t Hoff model yielded the most comprehensive correlation by covering the effects of both temperature and solvent composition variations on the solubility, with a mean relative deviation (MRD%) of 6.4%, suggesting a robust alignment between the modelled and experimental solubility data. Previously trained models were tested to predict the solubility of the drug in mono- and mixed-solvents at various temperatures where accurate predictions were obtained with the MRD% of 19.1% (for mono-solvents), 8.1 and 14.4% (for mixed solvent systems). [ABSTRACT FROM AUTHOR]

ABSTRACT Re di Castello is the southernmost unit of the composite Adamello batholith (central Alps, Italy). It was emplaced between 43 and 40 Ma, yet its depth of emplacement is not well constrained. We have studied the contact metamorphism of pelitic country rocks in two localities: the upper Caffaro Valley and the Borzago Valley in the southern and the northern sub‐units of the Re di Castello, respectively. In the Caffaro Valley, the country rocks comprise the Triassic sedimentary Lozio Shale, a carbon‐rich slate–siltstone, which was intruded by quartz‐dioritic magma. Near the contact, the hornfelses display the mineralogical assemblage Kfs‐Crd‐Bt‐Ms‐Pl‐Qz‐Gr, with rare fibrolitic sillimanite in a single sample. Andalusite was never observed throughout the aureole at this locality. In the Borzago Valley, contact metamorphism developed on schists of the pre‐Permian basement with a Variscan, regional metamorphic overprint. The sequence of contact metamorphic mineral assemblages progresses from And‐Bt‐bearing parageneses to the Sil‐Crd‐Bt‐Kfs‐Ms‐Pl‐Qz that characterizes peak conditions, at which incipient melting is also observed. K‐feldspar forms slightly upgrade the first appearance of sillimanite. For samples at both localities, thermodynamic modelling in the NCKFMASHT system failed at predicting a stability field for the sequences of mineral assemblages developed during contact metamorphism. Also the Ti‐in biotite thermometer did not constrain temperatures adequately. The P–T conditions at the thermal peak were thus evaluated by an alternative bathograd‐like approach, considering phase relationships in the simplified NKASH‐C system. To form sillimanite only as product of the incomplete Ms‐Qz breakdown—divariant for the presence of Na in Ms and Kfs and shifted to lower temperature due to the presence of graphite (in the Lozio Shale)—an isobaric path typical of contact metamophism must have crossed above the Msss‐Qz‐Kfsss‐Sil‐And‐fluid invariant point. This constrains an emplacement pressure >3.3 kbar in the Caffaro Valley, and >3.2 kbar in the Borzago Valley. Concerning temperature, the same univariant point also constrains the minimum temperature in the Caffaro Valley as >615°C–620°C, consistent with results of RSCM thermometry on graphite from the Lozio Shale. The evidence of incipient melting in some samples from the Borzago Valley indicates higher temperatures, probably approaching 670°C, near the contact to the intrusion. Assuming an average crust density of 2.7 g cm−3, the estimated pressures correspond to a minimum paleo‐depth of emplacement of about 12 km. These depths are somewhat greater than normally considered and should be regarded as revised constraints on models of the emplacement dynamics of the Adamello batholith and on paleogeographic reconstructions of this part of the Southalpine domain. [ABSTRACT FROM AUTHOR]

ABSTRACT Phase equilibrium modelling is a powerful method for obtaining pressure–temperature (P–T) estimates in metapelites; however, the advantages, disadvantages, and limitations of applying this technique to greenschist‐facies pelites have received little attention. This study uses two greenschist‐facies metapelites from the Nappe Zone in Sardinia (Italy) to examine differences between currently available thermobarometric techniques. First, this work compares P–T estimates from chlorite–K‐white mica–quartz–water and K‐white mica–quartz–water multiequilibrium approaches, the latter integrated with previously published Tmax results from Raman spectroscopy on carbonaceous material. Consistent P–T conditions are retrieved from these methods for both samples, with P–T estimates suggesting a difference in peak metamorphic conditions between the Internal and External Nappe Zones of Sardinia (peak P–T conditions of 0.6–0.8 GPa, 420°C°C–450°C and 0.4–0.5 GPa, 370°C°C–400°C for the Internal and External Nappes, respectively). Second, phase equilibrium modelling was used to assess the ability of six different sets of solution models, alongside their associated thermodynamic datasets, to constrain P–T conditions in the same samples, which are characterized by high‐variance mineral assemblages. Significant differences were found between the six thermodynamic databases, and important discrepancies were recognized between the observed and predicted mineral assemblages and compositions (e.g., Si in K‐white mica). In only one sample, three databases were able to predict the observed natural assemblage. The compositional isopleths for K‐white mica, from the same databases, do not intersect, offering no assistance in constraining P–T conditions. However, one database predicted chlorite's natural composition, yielding a P–T estimate consistent with multiequilibrium methods: ~0.9 GPa, ~350°C°C–400°C for the Internal Nappe Zone and ~0.5 GPa, ~300°C°C–350°C for the External Nappe Zone. Although P–T conditions constrained using calculated isopleths from greenschist‐facies metapelites and databases optimized for modelling low‐grade to medium‐grade pelitic systems may be reliable, they should be applied cautiously and compared with estimates from inverse and independent approaches. [ABSTRACT FROM AUTHOR]

New experimental measurements of phase equilibria in the CaO-FeO-Fe 2 O 3 system at 1120–1740 °C over a wide range of oxygen partial pressures (pO 2 = 1, 10−0.68, 10−2, 10−6, 10−8, 10−10 atm) and in equilibrium with metallic Fe has been obtained. The study was undertaken using equilibration/quenching and electron probe X-ray microanalysis (EPMA) technique enabling the compositions of the liquid and solid phases in equilibrium at temperature to be accurately measured. The data have been used to define the liquidus of hematite (Fe 2 O 3), spinel (Fe,Ca) 3 O 4+x , lime (Ca,Fe)O, wustite (Fe,Ca)O 1+x , 2CaO·Fe 2 O 3 (C 2 F), CaO·Fe 2 O 3 (CF), CaO·2Fe 2 O 3 (CF 2), and a solid phase with composition close to (CaO) 15 (FeO) 8 (FeO 1.5) 77 , which is believed to belong to the Silico-Ferrite of Calcium and Aluminium (SFCA-I) solid solution. Direct oxygen concentration measurements in the liquid and solid phases using EPMA were also undertaken in the present study to determine the Fe2+/Fe3+ ratio in these phases. The experimental data obtained in the present study will be used for thermodynamic re-optimisation of the CaO-FeO-Fe 2 O 3 system, undertaken as part of the study of the 20-component Pb-Zn-Cu-Fe-Si-Ca-O-S-Al-Mg-Cr-Na-As-Sn-Sb-Bi-Ag-Au-Ni-Co system directly relevant to the applications in the ferrous and non-ferrous metallurgical industries. [ABSTRACT FROM AUTHOR]

This research deals with gas hydrates formation and dissociation within a marine quartz-based porous sediment and in batch conditions. Hydrates were formed with small-chain hydrocarbons included in natural gas mixtures: methane and also ethane and propane. The dissociation values were collected and provided both graphically and numerically. The results were then compared with the theoretical hydrate-liquid-vapor phase boundary equilibrium for the same species, defined according to the existing literature. The deviation of the experimental results from the ideal ones, associated with the porous sediment, was quantified and discussed. For the scope, the grain size distribution and chemical composition of the sediment were provided along with the text. The results proved that the different size of guest species and, consequently, the different hydrate structures formed, played a relevant role in determining the promoting, inhibiting or neutral behavior of the porous sediment during the process. [ABSTRACT FROM AUTHOR]

Refractory superalloys (RSAs) are promising candidates for high-temperature, high-strength applications. Two-phase RSAs containing body-centered cubic (BCC) and ordered B2 phases are among the more promising candidates. Systems containing Ru-based B2 precipitates exhibit stable two-phase microstructures at temperatures in excess of 1600 °C. The present study experimentally investigated one potential foundational ternary system for these alloys, Nb-Ti-Ru. Two alloys, (Nb3Ti)0.85Ru0.15 and (Nb4Ti)0.85Ru0.15, were studied to determine phase equilibria and properties at temperatures between 900 °C and 1300 °C. The B2 phase was found to be dominated by RuTi ordering, although considerable Nb solubility was observed up to 18 mol %. The Nb-rich BCC matrix contained up to 15 mol % Ru and 20 mol % Ti. Although a two-phase microstructure of B2 precipitates in a BCC matrix was confirmed, the distribution of elements in the two phases resulted in a larger lattice misfit than expected. The results obtained in this investigation provide valuable information for the future development of RSAs utilizing Ru-based B2 strengthening precipitates. [ABSTRACT FROM AUTHOR]

Adding titanium oxide has become a common practice in modern blast furnace operating procedures. The blast furnace slag is based on the CaO–MgO–Al 2 O 3 –SiO 2 –TiO 2 low titanium slag system rather than CaO–MgO–Al 2 O 3 –SiO 2 system. Phase equilibria in the CaO–SiO 2 –Al 2 O 3 –MgO–TiO 2 system in the low-TiO 2 part have been experimentally determined by means of high temperature equilibration and quenching technique followed by electron probe X-ray microanalysis. Introducing a small quantity of titanium-bearing materials can lower the liquidus temperature. The TiO 2 content in the slag should be controlled below 4.6 wt%, otherwise it will enter the perovskite phase region where the liquidus temperatures increases rapidly. The compositions of the solid solutions corresponding to the liquidus have been precisely measured and should be utilized for developing the thermodynamic database. [ABSTRACT FROM AUTHOR]

In the present work, a comparison of the P–T equilibrium points of gas hydrates formation in bulk phase and porous medium (large particle size natural quartz sand) was studied for three different gas-hydrates: CO2, CH4 and a sample of natural gas. The effect of the large particle size in the P–T equilibrium conditions during the formation of gas hydrates was analyzed. Isochoric method and a cooling-heating rate of 0.7 K/h were used. The experimental results are compared with literature data and with the software CSMHyd and PVTsim. It was found that the P–T equilibrium points obtained in bulk are similar, within the experimental error, to the P–T points obtained in the large particle size natural quartz sand (gas + water + porous medium), in the range of temperature and pressure of 270–285 K and 1–14 MPa. For the systems gas (CO2, CH4) + water, the results were compared with literature data with an average deviation less than 7%. The system natural gas + water + porous medium was compared with similar experiments reported in the literature with smaller porous size silica (6–100 nm). A similar tendency is observed in systems with a porous size greater than 20 nm. Highlights: Porosity and permeability of quartz sand were measured experimentally. Phase equilibria of CH4, CO2, and natural gas hydrates in quartz sand were measured. The methodology is validated for gas hydrates stability in bulk phase and porous media. Experimental results are compared with literature and software CSMHyd and PVTsim. [ABSTRACT FROM AUTHOR]

CO2 injection into shale oil reservoirs has gained widespread attention as it not only enhances oil recovery but also facilitates the geological storage of CO2. Shale oil reservoirs are characterized by numerous nanopores, and the resident fluid exhibits unique phase behavior due to nanoconfinement effects, resulting in the failure of the traditional theoretical model and microfluidic experiment in depicting the minimum miscible pressure (MMP) of CO2–shale oil in nanopores. This study proposes a method for calculating the MMP of CO2–shale oil in nanopores. It combines the three‐phase equilibrium calculation method of gas phase–liquid phase–adsorbed phase with the multiple mixing cell (MMC) method. The method considers capillary pressure and corrects the critical properties influenced by the nano‐limited domain effect. Using this approach, the phase behavior of CO2–shale oil in nanopores and the MMP are investigated. It is found that as the pore radius decreases, the area of the two‐phase region surrounded by the phase envelope of multicomponent fluids gradually shrinks. The smaller the pore radius, the more significant the shrinkage of the two‐phase region. The entire phase envelope and the critical point shift to the left and down on the coordinates, and this phenomenon is more pronounced for pore radii less than 20 nm. The presence of CO2 increases the system's critical condensation pressure and decreases the critical condensation temperature. The MMP of the 6‐component system of CO2–shale oil for a pore radius of 5 nm in this paper is 63.7 bar at 101°C. [ABSTRACT FROM AUTHOR]

The phase equilibria in the SiO2‐rich region of the Li2O‐, Na2O‐, and K2O‐SiO2 systems at 1550°C to 1650°C were experimentally studied to determine accurate liquidus of SiO2 in the systems. A classical equilibration/quenching method was used, and the equilibrated samples were analyzed by X‐ray diffraction (XRD) and electron probe microanalysis (EPMA). Samples were contained in sealed Pt crucibles and held at the target temperatures for 7–21 days to reach equilibrium condition. Sealed Pt crucibles were employed to avoid the volatile loss of alkali oxides during high temperature phase equilibration and hydration upon quenching. Accurate liquidus of SiO2 in alkali‐silicate systems was determined for the first time, and the results were analyzed using the limiting slope rule in order to understand the dissolution behavior of alkali oxides in SiO2 melt. It was confirmed that alkali oxide dissolves in SiO2 melt by producing Li+, Na+, and K+ cationic species rather than Li22+, Na22+ and K22+ species. [ABSTRACT FROM AUTHOR]

Magnesium phosphate cement (MPC), which belongs to chemically bonded phosphate ceramics, is commonly applied as a repair material and waste stabilization/solidifications. However, studies on the influence of CO2 on the phase assemblages in MPC are limited. A thermodynamic simulation approach is employed to explore the influence of CO2 on the equilibrium phase assemblage of MPC. The mechanisms of natural and enforced carbonation of MPC have been investigated in this work. The results disclose that Mg carbonates are less likely to precipitate in magnesium ammonium phosphate cement (MAPC) cured under CO2, while MgCO3·3H2O is the only carbonation product of magnesium potassium phosphate cement (MKPC). The carbonation resistance of MAPC is better than that of MKPC. The increase of activity of magnesia employed in MPC obviously enhances the formation of brucite and slightly promotes the carbonation of MPC. [ABSTRACT FROM AUTHOR]

Using acrylic acid advanced ester and styrene as raw materials, the long-chain polyester polymer, polyacrylic acid advanced ester-styrene pour point depressant (P-PPD), was synthesized by molecular design, and its structure was characterized by infrared spectroscopy and nuclear magnetic resonance. In addition, this study experimentally investigated the effect of P-PPD on the phase equilibrium and induction time of natural gas hydrate inhibitors in deionized water (DW) and crude oil/water (O/W) systems, respectively. Polyvinylpyrrolidone (PVP) and mono ethylene glycol (EG) were selected as representatives of kinetic hydrate inhibitor (KHIs) and thermodynamic hydrate inhibitor (THIs), respectively. The results exhibit that P-PPD played a sight role in the phase equilibrium of hydrate, while the addition of P-PPD significantly prolonged the induction time of methane hydrate both in O/W + PVP, OW + EG and O/W + PVP + EG system, indicating that the addition of as-synthesized PPD has a synergistic inhibition effect on the nucleation ability of methane hydrate and can prevent hydrate from formatting during oil and gas transport process, and thus guarantee the flow assurance. The findings of this work will provide a data reference for the hybrid use of hydrate inhibitors and pour point depressants in oil and gas transport. [ABSTRACT FROM AUTHOR]

Prediction of mineral phase assemblages is essential to better understand the dynamics of the solid Earth, such as metamorphic processes, magmatism and the formation of mineral ore deposits. While recently developed thermodynamic databases allow the prediction of stable phase mineral assemblages for an increasing range of pressure, temperature and compositional spaces, the increasing complexity of these databases results in a significant increase of computational cost, hindering our ability to perform realistic models of reactive fluid/magma transport. Presently, prediction of stable phase equilibrium in complex systems is therefore largely limited by how efficiently single phase minimization can be performed, as more than 75 % of the total computational time is generally dedicated to individual solution phase minimization. This limitation becomes critical for non-ideal solution phase models that involve both a large number of chemical components, and mixing on a large number of sites, resulting in many inequality constraints of the form 0 ≤ xMl≤ 1, where xMlis the fraction of element l mixing on site M. Here, we present a general reformulation of complex non-ideal solution phases from the thermodynamic database of Holland et al. (2018), which comprises equations of state for multiple mineral solid solutions appearing in magmatic systems, as well as multicomponent silicate melt and aqueous fluid phases. Using a nullspace approach, inequality constraints governing the site fractions are transformed into equality constraints, and the resulting problem is turned into an unconstrained optimization problem, subsequently optimized using efficient gradient-based methods. To test our formulation, we apply it to several equations of state for solution phases known for their complexity and compare the results of our approach against classical optimization algorithms supporting inequality constraints. We find that the BFGS algorithm yields by far the best performance and stability with respect to the other investigated methods, improving the minimization time of individual solution phase by a factor ≥ 10. We estimate that our new approach can improve the computational time of stable phase equilibrium by a factor ≥ 5, thus potentially allowing to model realistic reactive fluid/magmatic systems by directly integrating phase equilibrium calculations in multiphase thermomechanical codes. [ABSTRACT FROM AUTHOR]

Cyclic alcohols are commonly found in natural and synthetic products and are involved in many biological processes. An ability to model their thermodynamic properties is of interest in food, flavouring, and pharmaceutical manufacturing, particularly for mixtures for which available experimental data are limited. Good examples are mixtures including menthol, a naturally occurring cyclic alcohol widely used in the food and pharmaceutical industries, well-known for its cooling-sensation properties and its role in the discovery of the TRPM8 receptor. Here, we extend the SAFT-γ Mie group-contribution method to model cyclic alcohols, by introducing a new cCHOH group (c for cyclic) composed of two identical Mie segments. Three association sites (two electronic sites of type e and one hydrogen site of type H) are also included to mediate hydrogen bonding. New parameters that characterise the group interactions (one new like interaction and 26 new unlike interactions) are developed and are employed to determine the thermophysical properties (vapour pressure, saturation density, vaporisation enthalpy, and second-order thermodynamic derivative properties) of pure cyclic alcohols, and mixture properties (vapour–liquid equilibria, liquid–liquid equilibria, solid–liquid equilibria, density, and excess enthalpy) of cyclic alcohols in several solvents. The quality of the model is evaluated by comparing predictive calculations with experimental data of 76 systems: six pure fluids and 70 binary mixtures, selected from a large range of solvent families: cyclic, linear, and branched alkanes, 1-alcohols, 2-alcohols, 2-ketones, esters, aromatic compounds, water, and carbon dioxide. Very good overall agreement is found, including for the prediction of solid–liquid solubility, which confirms the transferability of the new group parameters. Together with previously developed parameters, these open the way for the prediction of the thermodynamic properties of further complex mixtures. [ABSTRACT FROM AUTHOR]

Supercritical water has attracted much attention from both fundamental and technological perspectives, based largely on its ability to solvate other molecules. Predicting and controlling this requires a deeper understanding of water's polarisation behaviour. Using the computationally efficient Self-Consistent Electrostatic Embedding method, we were able to calculate the water dipole moment over an unprecedented range of thermodynamic conditions, covering gas, liquid and supercritical states, with large simulation systems and a high-level quantum mechanical method. We find a discontinuous change in the dipole moment along subcritical isotherms, corresponding to the sharp transition between the vapour and liquid states, with the latter exhibiting induced dipole moments between 0.5 and 0.9 D, depending on the temperature. In contrast, the dipole moment changes continuously from gas-like to liquid-like behaviour in the supercritical regime, allowing the degree of polarisation to be controlled through manipulating temperature and pressure. The dipole moment was found to be linearly related to the average number of hydrogen-bonded neighbours of water, emphasising the key role of local interactions to the polarisation process. Mean-field approaches based on a dielectric continuum representation of the solvent are unable to predict this behaviour due to the neglect of local interactions. [ABSTRACT FROM AUTHOR]

The possible existence of low-density and high-density fluid phase equilibria in fluids with a simple potential consisting in a combination of a square shoulder and a square well is explored by means of perturbation theory and histogram-reweighting grand canonical Monte Carlo simulation. Theory is useful as a simple and computationally inexpensive way to explore large sets of potential parameters to search for potential shapes susceptible to present multiple fluid phases, later confirmed or discarded from computer simulation. It is found that some combinations of the length and energy parameters of the potential actually give rise to such behaviour. [ABSTRACT FROM AUTHOR]

The Cenozoic collision of India and Eurasia clearly built the high-elevation Tibetan Plateau, but how this collision was accommodated, and the Tibetan Plateau uplifted, remains an area of study. The widespread occurrence of Cenozoic potassic–ultrapotassic lavas provides a valuable opportunity to constrain the relationship between surface deformation and underlying geodynamic processes. In this study, we report sanidine Ar–Ar dating, whole-rock geochemical and clinopyroxene Sr–Nd isotope analyses on pseudoleucite phonolites from the Yulinshan area of south Qiangtang (central Tibet) to determine their petrogenesis and regional tectonic significance. Sanidine Ar–Ar dating yields an Early Oligocene age of ca. 30 Ma, in agreement with previous studies. A high modal abundance of pseudoleucite in the samples indicates their ultrapotassic and silica-undersaturated composition. All of the rocks have typical arc-like geochemical signatures and enriched whole rock and clinopyroxene Sr–Nd isotope signatures. Based on thermodynamic phase equilibria modeling and our detailed study of the textural and in-situ compositional information of clinopyroxene, the intermediate to felsic potassic magmas are interpreted to have been formed through differentiation of primitive, mantle-derived, potassic magmas at shallow crustal levels. The inferred enrichment of the lithospheric mantle is probably related to subduction of the Songpan–Ganze continental lithosphere beneath Qiangtang after India-Asia collision. Voluminous Late Eocene–Early Oligocene magmatism in central Tibet may reflect partial removal of the mantle lithosphere, perhaps triggered by instabilities associated with previous lithospheric thickening. Our work provides additional constraints on the timing of mantle root loss that likely contributed to the surface uplift of central Tibet, which post-dated the cessation of upper crustal shortening and deformation. [ABSTRACT FROM AUTHOR]

Bimodal magmatism is characteristic of the geodynamic evolution of the Main Ethiopian Rift (MER), which is a reference area for the study of the processes leading to continental break-up before seafloor spreading. There are abundant emissions of basalts and rhyolites, which are in possible parent–daughter relationships. However, the P – T –H2O conditions of production and storage of the basaltic end member remain unclear. Crystallization experiments have been conducted on an alkali basalt from the MER to define its pre-eruptive conditions and shed light on the compositional evolution of derivative liquids and source conditions. The experiments were performed at 100 to 200 MPa, 975°C to 1080°C, varying H2O/CO2 ratios, corresponding to melt water contents of 1 to 5 wt %, at f O2 slightly lower than the Fayalite-Magnetite-Quartz (FMQ) solid buffer. Comparison between the petrological attributes of the starting rock and the experiments shows that the basaltic magma was stored at 150 to 200 MPa, 1050 ± 10°C, with 1 to 2 wt % H2O in melt, with f O2 near FMQ prior to eruption. Geochemical modelling shows that the corresponding mantle source contained about 0.1 wt % H2O, reflecting a metasomatized source. Extensive crystallization of such basalts produces SiO2-rich liquids, which are not yet peralkaline, however. This underscores that extreme fractionation (>90 wt %) is required in order to produce peralkaline derivatives from mildly alkaline basalts. This extreme fractionation and the water-rich nature of the starting basalt readily explain the H2O-rich condition of peralkaline rhyolites that have fueled caldera forming eruptions in the Rift. [ABSTRACT FROM AUTHOR]

Sulfate-type salt lakes constitute over half of the total salt lakes in China and are rich in rare elements, such as rubidium and cesium. However, the complex interactions between ions make the separation and extraction process quite challenging. To address this, phase equilibrium studies were conducted on the sulfate system containing rubidium, cesium, and magnesium. Specifically, the phase equilibria of the aqueous quaternary system Rb+, Cs+, Mg2+//SO42− - H2O at 323.2 K were investigated using the isothermal dissolution method. The solubility, density, and refractive index of the system were experimentally measured. The results indicate that the system at 323.2 K belongs to a complex type with the formation of one solid solution (Rb, Cs)2SO4 and two double salts (Rb2SO4·MgSO4·6H2O, Cs2SO4·MgSO4·6H2O). The corresponding phase diagram consists of four quaternary invariant points, nine univariate curves, and six crystallization regions. Among these, the crystalline region for Cs2SO4·MgSO4·6H2O is the largest, while that for the single salt Cs2SO4 is the smallest. Moreover, the crystalline regions for the double salt and solid solutions are significantly larger than those for the single salt, highlighting the difficulty in separation of valuable single salts. A comparison of multi-temperature phase diagrams from 298.2 K to 323.2 K reveals that the crystalline form of MgSO4 changes from MgSO4·7H2O (298.2 K) to MgSO4·6H2O (323.2 K). As the temperature increases, the phase regions for Rb2SO4, Cs2SO4, (Rb, Cs)2SO4, and Cs2SO4·MgSO4·6H2O expand, while the phase region of Rb2SO4·MgSO4·6H2O contracts, indicating that the single salts (Rb2SO4, Cs2SO4) are more readily precipitated at higher temperature, which provides theoretical guidance for the future production and separation of Rb, Cs, and Mg from sulfate-type salt lakes. [ABSTRACT FROM AUTHOR]

Ideological and political education is a crucial component in talent development, and specialized courses serve as important platforms for implementing this education. This paper focuses on the unique characteristics of the physical chemistry course in traditional Chinese medicine universities and uses the phase diagram of water in the phase equilibrium chapter as an example to explain the design and implementation of ideological and political education in teaching. It explores approaches and methods to effectively integrate ideological and political elements with professional knowledge, aiming to provide valuable insights for incorporating ideological and political education into the teaching of physical chemistry. [ABSTRACT FROM AUTHOR]

In this computational study, molecular dynamics (MD) simulation is utilized to calculate the thermal conductivity of carbon dioxide with nitrogen under supercritical conditions. The large-scale atomic/molecular massively parallel simulator (LAMMPS) software was utilized, along with the transferable potentials for phase equilibria (TraPPE) and the Galassi-Tildesley (GT) force fields, to accurately model the atomic structures of carbon dioxide and nitrogen within the simulation box. The simulation encompassed molar concentrations of nitrogen ranging from 1 % to 3 %, with pressures up to 100 bar and temperatures between 30 °C to 50 °C. In order to verify the precision of the simulation, the thermal conductivity of pure CO2 and a mixture of CO2 and N2 were assessed by comparing them with data from the NIST database as well as experimental data. Remarkably, the simulation findings exhibited excellent agreement with the experimental data and the NIST database, showcasing average absolute errors ranging from 6 % to 11 % for pure CO2 and 6 % to 15 % for the CO2/N2 mixture. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the value of extracellular volume (ECV) fraction and fat fraction (FF) derived from dual- energy CT (DECT) for predicting postpancreatectomy acute pancreatitis (PPAP) after pancreatoduodenectomy (PD). Methods: This retrospective study included patients who underwent DECT and PD between April 2022 and September 2022. PPAP was determined according to the International Study Group for Pancreatic Surgery (ISGPS) definition. Iodine concentration (IC) and FF of the pancreatic parenchyma were measured on preoperative DECT. The ECV fraction was calculated from iodine map images of the equilibrium phase. The independent predictors for PPAP were assessed by univariate and multivariable logistic regression analysis and receiver operating characteristic (ROC) curve analysis. Results: Sixty-nine patients were retrospectively enrolled (median age, 60 years; interquartile range, 55–70 years; 47 men). Of these, nine patients (13.0%) developed PPAP. These patients had lower portal venous phase IC, equilibrium phase IC, FF, and ECV fraction, and higher pancreatic parenchymal-to-portal venous phase IC ratio and pancreatic parenchymal-to-equilibrium phase IC ratio, compared with patients without PPAP. After multivariable analysis, ECV fraction was independently associated with PPAP (odd ratio [OR], 0.87; 95% confidence interval [CI]: 0.79, 0.96; p < 0.001), with an area under the curve (AUC) of 0.839 (sensitivity 100.0%, specificity 58.3%). Conclusions: A lower ECV fraction is independently associated with the occurrence of PPAP after PD. ECV fraction may serve as a potential predictor for PPAP after PD. Clinical relevance statement: DECT-derived ECV fraction of pancreatic parenchyma is a promising biomarker for surgeons to preoperatively identify patients with higher risk for postpancreatectomy acute pancreatitis after PD and offer selective perioperative management. Key Points: PPAP is a complication of pancreatic surgery, early identification of higher-risk patients allows for risk mitigation. Lower DECT-derived ECV fraction was independently associated with the occurrence of PPAP after PD. DECT aids in preoperative PAPP risk stratification, allowing for appropriate treatment to minimize complications. [ABSTRACT FROM AUTHOR]

High-temperature diffusion of major elements may obscure the records of early and peak metamorphic stages in granulites, while trace elements are more likely to preserve these records due to their lower diffusion rates. Thus, using calibrated REE-based thermobarometers has proved essential for reconstructing these key stages, drawing considerable attention and application from scholars. However, the precision of these thermobarometers depends on including both major and trace elements from coexisting minerals to define the correlation coefficients (A, B, and D) among mineral pairs, indicating that the elemental composition of these pairs can affect the results. Our study examines the mafic-ultramafic granulites in the southern granulite terrain, India, employing integrated methods such as petrography, mineral chemistry, phase equilibrium modeling, and REE-based thermobarometers. We aim to determine their metamorphic conditions and evolutionary history and to identify potential challenges in using REE-based thermobarometers. The garnet, clinopyroxene, and orthopyroxene in the mafic-ultramafic granulite samples display homogeneous compositional profiles, with pronounced Fe-Mg diffusion zones at the interfaces between garnet and clinopyroxene. Conversely, the profiles of trace elements within garnet and clinopyroxene are better preserved. Investigations into Fe-Mg exchange and randomly selected mineral pairs significantly influence the accuracy of REE-based thermobarometers. Fe-Mg exchange can increase in coefficient A, while decreasing coefficient B for light rare earth elements (LREEs) and increasing it for heavy rare earth elements (HREEs), ultimately resulting in over-estimations when calculating REE-based thermobarometers. For example, selecting major compositions with an Ex (= (X Mg C − X Mg 0) / X Mg 0 × 100 % ; where X Mg C is the value after Fe-Mg exchange, X Mg 0 is the value before Fe-Mg exchange; X Mg = Mg / (Fe 2 + + Mg) ) value of ∼10 for calculation using the REE-in-Grt-Cpx thermobarometer will result in pressures and temperatures being ∼10 kbar and 30–40°C higher than the true values. Random pairing, such as selections based solely on the core or rim of minerals with changes in trace elements, can severely impact the distribution coefficient D, resulting in substantial discrepancies in thermobarometric calculations and potentially producing anomalous results. Thus, to minimize the impact of these factors, it is necessary to first analyze the profiles of major and trace elements in coexisting minerals before applying the REE-based thermobarometers to evaluate the P-T conditions of granulites. Based on this analysis, major element compositions less affected by Fe-Mg exchange (such as avoiding the selection of major compositions at the boundaries of minerals) and in relative equilibrium in trace element compositions among coexisting minerals (same growth periods) should be selected for pairing. Furthermore, integrating additional methods should also be considered when applying the REE-based thermobarometers, to prevent the misinterpretation of the P-T conditions obtained. [ABSTRACT FROM AUTHOR]

Elements with a high affinity for O and S in molten steel are desirable as deoxidizing and desulfurizing agents in the steel refining process, and Ce has attracted attention. In this study, the thermodynamic properties of sulfur in a CaO–AlO1.5–CeO1.5 slag system at 1873 K are investigated. A chemical equilibrium method using Cu is employed for these measurements. Sulfide capacities are determined in the CaO–AlO1.5–CeO1.5 system to show desulfurization ability; the precipitated phases are identified when large amounts of sulfur are added to the CaO–AlO1.5–CeO1.5 system; the solubility of CaS in the CaO–AlO1.5–CeO1.5 system is determined. It is suggested that the slag of this system can improve sulfur distribution while reducing the Al concentration in the steel. [ABSTRACT FROM AUTHOR]

In this study, we propose a method for estimating liquid–liquid equilibrium with ab initio molecular dynamics (MD) simulation. Additionally, we determined the non‐random two‐liquid model parameters for the systems applicable to the extraction design using a commercial software. The minimized energy of separate liquid phases yielded equilibrium data from a more versatile procedure than the existing MD simulation. Although many experimental measurements with the parameters have been published, the parameters are not always compatible with the software. The performances are graphically illustrated for example systems including ionic liquid and deep eutectic solvent, and the results indicated that the proposed procedures of the estimation and the model parameter determination were satisfactory. [ABSTRACT FROM AUTHOR]

Levulinic acid (LA), a carboxylic acid with a keto-acid structure, has recently been gaining increasing attention as a promising biorefinery platform chemical due to its potential to be feasible and sustainable. This work focuses on using trioctylamine (TOA) to separate LA from an aqueous solution by liquid–liquid extraction. For that, binodal curves and tie lines were determined at T = (293.15, 313.15, and 333.15) K under atmospheric pressure. The slope of the determined tie lines demonstrates that higher extraction efficiencies are possible with higher acid concentrations. Furthermore, infrared spectroscopy (FT-IR) was applied to better understand the behavior of phase diagrams. This study detected the acid-extractant complex formation between (LA) and (TOA). Finally, the experimental data were successfully correlated with the NRTL model at all the measured temperatures. The obtained parameters were applied using a decanter model. [ABSTRACT FROM AUTHOR]

The study investigates the solubility of carbon dioxide (CO 2) in three ionic liquids [BMP][Tf 2 N] (1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide), [HMP][Tf 2 N] (1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide) and [OMP][Tf 2 N] (1-octyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide). The research is conducted over a temperature range of 303.15 to 363.15 K. The phase equilibria of the binary systems are predicted using the Peng-Robinson (PR) equation of state, the Wilson (WS) mixing rule and the UNIFAC activity coefficient model. The interaction parameter k ij is regressed from the vapor-liquid equilibrium (VLE) experimental data. The study also calculates the excess Gibbs free energy (GE), excess enthalpy (HE), and excess entropy (SE) for these systems. The research results indicate that the length of the alkyl chain in the cation has a significant effect on the excess properties of the CO 2 -ionic liquid systems. As the alkyl chain length increases, the excess Gibbs free energy and excess enthalpy decrease, while the excess entropy increases. The CO 2 -[OMP][Tf 2 N] system exhibits stronger interactions between CO 2 and the ionic liquid, indicating a higher capacity for CO 2 absorption. The study results are helpful for optimization of CO 2 capture processes and the broader comprehension of fluid phase equilibria in complex systems. [ABSTRACT FROM AUTHOR]

Understanding the oxidation behavior of hafnium carbide is crucial to its application in extreme environments. In this work, the transition in high‐temperature oxidation kinetics regimes in hafnium carbide is explained based on phase equilibria considerations supported by observed changes in oxide scale microstructure evolution associated with different transformation pathways. Below, a composition‐dependent critical temperature and oxygen pressure, hafnium carbide first transforms to an amorphous material with nominal composition HfO2C followed by phase separation into carbon and hafnia domains. Subsequently, gaseous transport through a nanometric pore network formed by oxidative removal of phase‐separated carbon becomes rate‐limiting. Above this critical point, the oxidation sequence involves a direct transformation from hafnium carbide to hafnia and gaseous products, leading to dissimilar scale morphologies responsible for the reported transition from gaseous to solid‐state diffusion‐limited oxidation regimes at ultra‐high temperatures. [ABSTRACT FROM AUTHOR]

[Display omitted] Phase behavior of nanoconfined fluids adsorbed in metal–organic frameworks is of paramount importance for the design of advanced materials for energy and gas storage, separations, electrochemical devices, sensors, and drug delivery, as well as for the pore structure characterization. Phase transformations in adsorbed fluids often involve long-lasting metastable states and hysteresis that has been well-documented in gas adsorption–desorption and nonwetting fluid intrusion-extrusion experiments. However, theoretical prediction of the observed nanophase behavior remains a challenging problem. The mesoscopic canonical, or mesocanonical, ensemble (MCE) is devised to study the nanophase behavior under conditions of controlled fluctuations to stabilize metastable and labile states. Here, we implement and apply the MCE Monte Carlo (MCEMC) simulation scheme to predict the origins of reversible and hysteric adsorption phase transitions in a series of practical MOF materials, including IRMOF-1, ZIF-412, UiO-66, Cu-BTC, IRMOF-74-V, VII, and IX. The MCEMC method, called the gauge cell method, allows to produce Van der Waals type isotherms with distinctive swings around the phase transition regions. The constructed isotherms determine the positions of phase equilibrium and spinodals, as well as the nucleation barriers separating metastable states. We demonstrate the unique capabilities of the MCEMC method in quantitative predictions of experimental observations compared with the conventional grand canonical and canonical ensemble simulations. The MCEMC method is implemented in the open-source RASPA and LAMMPS software packages and recommended for studies of adsorption behavior and pore structure characterization of MOFs and other nanoporous materials. [ABSTRACT FROM AUTHOR]

This report is the first analysis of the coexistence and microstructure of the equilibrium phases in the Fe-Pd L10 + L12 eutectoid region. Coexistence of L10 + L12 is observed at higher temperatures (650 ∘ C ), resulting in L10 polytwin plates with internal boundaries that are decorated by L12. For higher Pd content, the L10 plates are embedded in an extended L12 matrix, but the L12 wetting layers still persist. For aging at low temperatures (525 ∘ C ), L1' + L12 coexistence is observed, but the microstructure is essentially similar, except that L10 is replaced by L1'. The two-phase region is found to be much narrower than reported in published phase diagrams, of order 0.6 to 1 at pct in extent. There may be a further re-entrant narrowing below the L1' formation temperature. This work establishes L1' as a phase distinguishable from both L10 and L12, but does not yet prove that L1' is an equilibrium phase. The preferred formation of L1' at lower temperatures may relate both to stability conferred by overall ferrimagnetic interactions, and perhaps by kinetics, where L1' should have a reduced nucleation barrier from A1 relative to L10. [ABSTRACT FROM AUTHOR]

Silicon–ferrite from calcium and aluminum (SFCA) is one of the primary binding phases in sinter. To better investigate the reduction process of SFCA under hydrogen-rich conditions in a blast furnace, isothermal reduction experiments were designed using three different hydrogen volume fractions (6%, 10%, and 14%) at temperatures within the blast furnace's lump zone range (1073 K, 1173 K, and 1273 K). The experimental results revealed that the reduction of SFCA proceeds in two stages: in the first stage, SFCA is initially reduced to Fe3O4; in the second stage, Fe3O4 is further reduced to FeO, with the equilibrium phases being FeO, Ca2Al2SiO7, and Ca2SiO4. The fastest reduction rate was observed at 1273 K. When the hydrogen volume fraction was 6% and the temperatures were 1073 K, 1173 K, and 1273 K, the reaction mechanism followed the 3D diffusion model (G-B), with an apparent activation energy of 32.087 kJ· mol − 1 and a pre-exponential factor of 0.1419. In comparison, at hydrogen volume fractions of 10% and 14%, the reaction mechanism shifted to the Shrinking core model (n = 3). The findings of this study can provide guidance for actual production and optimization of blast furnace parameters aimed at achieving low-carbon emissions in the steel-making process. [ABSTRACT FROM AUTHOR]

This study focused on synthesizing AlNiCo and CoNi materials using a low-energy milling process. The aim was to explore the formation of low-energy phases in both systems, contrasting with the typical research on phases formed under high-energy conditions. In the Co-20 wt% Ni system, the phases Co 0.75 Ni 0.25 and Ni were identified, as well as the FCC cubic phase of CoNi, using X-ray diffraction (XRD) with a molybdenum radiation source. The observed behavior aligned closely with the miscibility curve in the equilibrium phase diagram, which included a region of alloys with varying structures and similar compositions. A notable feature was the presence of a predominantly dispersed hexagonal Ni zone, consisting of nanoparticles. Transmission electron microscopy (TEM) was employed to observe the FCC CoNi phase, which displayed a specific arrangement. AlNiCo and CoNi alloys were successfully synthesized through mechanical alloying, incorporating equilibrium and non-equilibrium phases. [ABSTRACT FROM AUTHOR]

This paper presents equations derived from thermodynamic equations for calculating the liquidus and solidus temperatures, the liquidus slope, and the partition ratio for solidification simulations. The constants of these equations can be easily determined from measurement data obtained by digitalisation from known diagrams or can be calculated using a CALPHAD-based software. ESTPHAD has a hierarchical system; the developed functions of the binary systems are used in the calculation of the functions of the ternary systems, the functions of the ternary systems in the calculation of the function of quaternary systems, and so on. The developed method is demonstrated by processing the liquidus and solidus of Si–Ge isomorphous and Al–Mg and Al–Si eutectic equilibrium phase diagrams. The use of this method for calculating the functions of ternary systems will be shown in Part II. The advantages of this method are that the equations are simple, can be determined very quickly, and can be built into the simulation software very easily. The most significant advantage is that the calculation time is shorter by some order of magnitude than that of a CALPHAD-type calculation. [ABSTRACT FROM AUTHOR]

To improve the use of nanoparticles, it is imperative to comprehend the patterns and mechanisms driving their melting. The melting transformation thermodynamics has many formulas because of the phase equilibrium integrity and equilibrium presupposition of the different models. The analysis of the melting temperature depression for the nanoparticles has been done using a variety of melting models that have been published in the literature. These models include the following: Pawlow theory; Homogenous growth model; Heterogeneous growth model; Liquid nucleation & growth model; Liquid shell model; Homogenous melting and growth model; Bond order length strength model; Homogenous melting hypothesis; Liquid skin melting model; Reiss melting model and Rie melting model; Liquid drop model; Gibbs Thomson equation; Surface phonon instability model; and so on. In order to lower the melting point of the nanoparticles, this study reviews several melting models. The melting models align with the observed value of minute particles. Furthermore, the relationship between exact thermodynamic equations and their approximate counterparts is presented, as is the shift in melting temperature that occurs when nanoparticles melt. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phase equilibria in the ZrO2–YO1.5–NbO2.5 system were experimentally studied at 1300°C, and a comparison with the existing ZrO2–YO1.5–TaO2.5 (ZYTO) was conducted. Ternary fluorite phases on the Y:Nb > 1 side extend from binary ZrO2‐YO1.5 to YO1.5–NbO2.5 system, generating a continuous solid solution region. Furthermore, it was observed that three phases of M‐YNbO4, fluorite, and m‐ZrO2 were in equilibrium. On the Y:Nb < 1 side, two three‐phase equilibrium regions were measured, namely M‐YNbO4+m‐ZrO2+O‐Nb2Zr6O17 and h‐Nb2O5+O‐Nb2Zr6O17+M‐YNbO4. The tetragonal YNbO4 and ZrO2 phases both extend nearly along with Y:Nb = 1. The t‐ZrO2 phases with slightly lower stabilizer content were found to transform into their monoclinic polymorph during the cooling process. However, in the ZrO2–YNbO4 subsystem, the tetragonal ZrO2 was nontransformable due to larger YO1.5 and NbO2.5 co‐dopants, and the maximum solubility is about 18.1 mol%. Upon cooling, the tetragonal YNbO4 phase, even with the maximum ZrO2 content, is transformable to monoclinic form. The maximum solubility of ZrO2 in YNbO4 is determined to be about 20.7 mol%. Finally, the high‐temperature liquidus in the ZrO2–YNbO4 system was first determined based on the cooling traces, and a vertical section diagram was proposed for further speculation. A eutectic reaction of Liquid→YNbO4+ZrO2 was discovered, and the eutectic composition and temperature were measured as 39.2ZrO2–29.2YO1.5–31.6NbO2.5 and 1813°C. This study provides the basis for thermodynamic assessment of ZrO2–YO1.5–NbO2.5 and is valuable for the design and development of the ZrO2–YO1.5–NbO2.5‐based ceramic materials. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a system of ordinary differential equations involving a non-autonomous Lotka-Volterra system of competition between the two species. Using the Taylor expansion, we consider the qualitative properties of the equilibrium points in the phase plane. Moreover, we examine the conditions for the persistence and extinction of the species. In addition, we show that the techniques used can be applied to a system of partial differential equations. Finally, we give numerical examples illustrated by the vector field around the equilibrium points to verify the theoretical results. [ABSTRACT FROM AUTHOR]

Many molecular systems and physical phenomena are controlled by local fluctuations and microscopic dynamical rearrangements of the constitutive interacting units that are often difficult to detect. This is the case, for example, of phase transitions, phase equilibria, nucleation events, and defect propagation, to mention a few. A detailed comprehension of local atomic environments and of their dynamic rearrangements is essential to understand such phenomena and also to draw structure–property relationships useful to unveil how to control complex molecular systems. Considerable progress in the development of advanced structural descriptors [e.g., Smooth Overlap of Atomic Position (SOAP), etc.] has certainly enhanced the representation of atomic-scale simulations data. However, despite such efforts, local dynamic environment rearrangements still remain difficult to elucidate. Here, exploiting the structurally rich description of atomic environments of SOAP and building on the concept of time-dependent local variations, we developed a SOAP-based descriptor, TimeSOAP (τSOAP), which essentially tracks time variations in local SOAP environments surrounding each molecule (i.e., each SOAP center) along ensemble trajectories. We demonstrate how analysis of the time-series τSOAP data and of their time derivatives allows us to detect dynamic domains and track instantaneous changes of local atomic arrangements (i.e., local fluctuations) in a variety of molecular systems. The approach is simple and general, and we expect that it will help shed light on a variety of complex dynamical phenomena. [ABSTRACT FROM AUTHOR]

We introduce a method for solving the "inverse" phase equilibria problem: How should the interactions among a collection of molecular species be designed in order to achieve a target phase diagram? Using techniques from convex optimization theory, we show how to solve this problem for phase diagrams containing a large number of components and many coexisting phases with prescribed compositions. We apply our approach to commonly used mean-field models of multicomponent fluids and then use molecular simulations to verify that the designed interactions result in the target phase diagrams. Our approach enables the rational design of "programmable" fluids, such as biopolymer and colloidal mixtures, with complex phase behavior. [ABSTRACT FROM AUTHOR]

The effects of a dissolved gas on the behavior of liquid in cylindrical nanopores are investigated in the framework of Gibbsian composite system thermodynamics and classical nucleation theory. An equation is derived relating the phase equilibrium of a mixture of a subcritical solvent and a supercritical gas to the curvature of the liquid–vapor interface. Both the liquid and the vapor phases are treated nonideally, which is shown to be important for the accuracy of the predictions in the case of water with dissolved nitrogen or carbon dioxide. The behavior of water in nanoconfinement is found to be only affected when the gas amount is significantly more than the saturation concentration of these gases at atmospheric conditions. However, such concentrations can be easily reached at high pressures during intrusion if there is sufficient gas present in the system, especially considering gas oversolubility in confinement. By including an adjustable line tension term in the free energy equation (−44 pJ/m for all points), the theory can make predictions in line with the few data points available from recent experimental work. However, we note that such a fitted value empirically accounts for multiple effects and should not be interpreted as the energy of the three-phase contact line. Compared to molecular dynamics simulations, our method is easy to implement, requires minimal computational resources, and is not limited to small pore sizes and/or short simulation times. It provides an efficient path for first-order estimation of the metastability limit of water–gas solutions in nanopores. [ABSTRACT FROM AUTHOR]

Sintering is an important consolidation step employed in sinter-based metal additive manufacturing processes. Binder Jetting (BJT) starts with green components with low green density (40–60 %) that results in large sintering shrinkages and geometrical shape distortions caused by external forces (e.g. gravity). Consequently, the prediction of the final sintered geometry is crucial during the design process. In this work, a novel sintering simulation framework for gravity-affected sintering of stainless-steel components is presented, including the Rios-Olevsky-Hryha sintering model and the methodology for the identification of the required material parameters. The constitutive law includes material constants to account for the powder packing effects and the delta-ferrite transformation occurring at high temperatures. The material shear viscosity was explicitly related to the equilibrium phase fraction of austenite and delta-ferrite during sintering temperatures. Dilatometry experiments were conducted and followed by the data postprocessing for the model calibration. The calibrated model was incorporated in a FEM code and validated against experimental data from BJT sintered components, showing the remarkably accuracy of the numerical simulations, with small geometric deviations (0.56 mm) related to the assumption of isotropic shrinkage in the model proposed. In parallel, other alternative models were implemented based on different normalized bulk viscosity formulations, which underestimate/overestimate the sintered distortions. [ABSTRACT FROM AUTHOR]

Hydrate-based gas separation (HBGS) has good potential in the separation of helium from helium-rich natural gas. HBGS should be carried out under a pressure higher than the thermodynamic equilibrium hydrate formation pressure (Peq) to ensure the formation of hydrate so that the accurate prediction of Peq is the basis of the determination of HBGS pressure. In this work, the Peq of the helium-rich natural gases with different helium contents (1 mol%, 10 mol%, and 50 mol%) in gas and different tetrahydrofuran (THF) contents (5 wt%, 10 wt%, and 19 wt%) in liquid at different temperatures were experimentally investigated through the isothermal pressure search method. A new thermodynamic model was proposed to predict the Peq of helium-rich natural gas. This model can quantitatively describe the effects of THF and helium on Peq, and it predicts the Peq of the helium-rich natural gases in this work accurately. The average relative deviation of the model is less than 3%. This model can guide the determination of the operating condition of the HBGS of helium-rich natural gas. [ABSTRACT FROM AUTHOR]

This research focuses on modeling CO2 absorption into alkanolamine solvents using multilayer perceptron (MLP), radial basis function network (RBF), Support Vector Machine (SVM), networks, and response surface methodology (RSM). The parameters, including solvent density, mass fraction, temperature, liquid phase equilibrium constant, CO2 loading, and partial pressure of CO2, were used as input factors in the models. In addition, the value of CO2 mass flux was considered as output in the models. Trainlm, trainbr, and trainscg algorithms trained the networks. The results showed that the best number of neurons for MLP with one layer is 16; with two layers, 5 neurons in the first layer and 12 neurons in the second layer; and with three layers, 9 neurons in the first layer, 5 neurons in the second layer, and 1 neuron in the third layer. The best spread in RBF was found to be 2.202 for optimal network performance. Furthermore, statistical data analysis revealed that the trainlm function performs best. The coefficients of determination for RSM, MLP, RBF, and SVM for optimized structures are obtained at 0.9802, 0.9996, 0.9940, and 0.8946, respectively. The results demonstrate that MLP and RBF networks can model CO2 absorption using the trainlm, trainbr, and trainscg algorithms. [ABSTRACT FROM AUTHOR]

The objective of this work is to predict the methane hydrate phase boundary equilibrium temperature in the presence of ionic liquids (ILs) using machine learning techniques to overcome the limitations of the existing empirically proposed models. To achieve the objectives of this work, five deep neural networks (DNN) algorithms; Adadelta, Ftrl, Adagrad, Adam, and RMSProp coupled with six activation functions (elu, leaky relu, sigmoid, relu, tanh, and selu) were used on 610 experimental datasets from literature. The independent variables used to predict the ILs methane hydrate boundary temperature were pressure (2.39–100.43 MPa), concentration (0.10–50 wt.%), and ILs molecular weight (91.11–339.50 gmol−1). The study revealed that Adadelta DNN optimization algorithm and elu activation functions gave the best predictions with an average RMSE of 0.6727 and 0.6989, respectively. The findings suggest that the use of Adadelta coupled with elu accurately predicts the methane hydrate phase boundary condition in the presence of ionic liquids. The excellent performance of Adadelta and elu resides in their ability to predict exponential data trends which is the fundamental behavior of hydrate phase behavior condition. This work pioneered the use of machine learning techniques to predict hydrate behavior conditions in IL systems. Thus, the findings in this work will enhance the development of simple hydrate phase behavior properties predictive software for IL systems. [ABSTRACT FROM AUTHOR]

The Poroshiri ophiolite (Hidaka metamorphic belt, Japan) occurs within a crustal‐scale network of high‐temperature, dextral shear zones that accommodated hundreds of kilometres of displacement due to the opening of the Japan Sea in the Neogene. The opholitic rocks comprise ultramafic, mafic and sedimentary protoliths that have been variably hydrated and metamorphosed. This work investigates the mechanisms and timing of fluid influx relative to viscous deformation in metagabbros and amphibolites deformed during exhumation from granulite‐ to amphibolite‐facies conditions. We consider a range of microstructures, from low strain domains and 1–2 mm thick shear bands to mylonites with a thickness of a few meters. Low strain domains of metagabbros exhibit corona textures with symplectites consisting of pargasitic amphibole (Ed0.7) ‐ anorthitic plagioclase (An80–92) ± orthopyroxene ± clinopyroxene forming around olivine and igneous pyroxene and with similar plagioclase–amphibole‐orthopyroxene ± clinopyroxene granoblastic aggregates in micrometric‐thick fractures. These textures result from hydration under low fluid‐rock ratio, with elevated H2O content only occurring locally (H2O > 1–1.2 wt%). Igneous mineral replacement leads to grain size reduction from 1 mm to ~10 μm. Amphibole exhibits a strong core‐rim zonation primarily controlled by the high diffusivity of Fe, Mg and OH and the low diffusivity of Al. Mineral compositional equilibrium is achieved at the scale of 100–200 μm. In mm‐thick localized shear bands and in metric‐scale mylonitic amphibolites, the heterogeneous mineral composition of amphibole (Ed0.2–0.5) and plagioclase (An40−An80) indicates only partial re‐equilibration (at the scale of 200–500 μm) despite higher fluid‐rock ratios and more pervasive fluid percolation than in metagabbros. Plagioclase–amphibole thermometry and equilibrium phase diagrams indicate that the initial fluid infiltration and corona formation occurred at 800–850°C by fracturing and percolation along grain boundaries. This was followed by the main fluid percolation and mylonitization event, which occurred during exhumation and cooling at conditions of 720–580°C, ~4 kbar. Continuous hydration during retrogression was achieved by the influx of dominantly seawater‐derived fluid, as attested by the high chlorine (Cl) contents (>300–400 ppm) of amphiboles in fractures. The heterogeneous distribution of fractures controls the distribution of fluid from the earliest stages of hydration, creating positive feedback where the growth of hydrous minerals as amphibole (up to +300 vol% of amphibole in high strain areas relative to the low‐strain ones) and the formation of fine‐grained mixed domains that led to further localization of viscous strain and mass transfer (variations of ± 30–40% in major elements). The Poroshiri ophiolite therefore represents a good fossil example of a former transpressional plate boundary where coupled metamorphic and deformation processes were triggered by seawater‐derived fluid that percolated to depths of ~15 km. [ABSTRACT FROM AUTHOR]

According to the data provided in the literature and to the results of experiments and calculations using the NRTL and UNIFAC equations, hydrolytic polycondensation of silicone monomers RnSiX4−n (X = Cl; —OR′, —OCOR) is an autocatalytic process that is accelerated by the products of the process (silanols, alcohols, acids) owing to their effect on the increase in solubility and, as a consequence, on the increase in the concentration of the reagent (water) in the reaction zone. This is also facilitated by an increase in both the intensity of mixing of reagents and temperature. Modeling of changing phase quasi-equilibria during the hydrolysis of silicone monomers showed that in the kinetic regime, the supply of water from the aqueous phase exceeds its consumption in the reaction, which leads to an increase in the rate of hydrolysis. The autocatalytic nature of the hydrolysis and condensation of alkoxy- and acetoxysilanes offers prospects for the catalyst- and solvent-free synthesis of polyorganosiloxanes. [ABSTRACT FROM AUTHOR]