Search

Understanding the density of CO2 + n-decane is crucial for designing and operating CO2 capture, transport, and storage. The safety and effectiveness of CO2 burial is directly affected by the density of CO2 + n-decane mixtures. The liquid densities of CO2(1) + n-decane(2) mixtures with mole fractions of CO2 x1 = 0, 0.2032, 0.4434, 0.7589, and 0.8947 were measured using a vibrating tube densimeter. The combined expanded uncertainties of density with a level of confidence of 0.95 are estimated to be 0.6 kg·m−3. A total of 221 compressed liquid densities of CO2(1) + n-decane(2) mixtures along the five isotherms between T = (283 and 363) K with pressures up to 100 MPa were presented. The densities of mixtures were correlated by the modified Tait equation, resulting in absolute average deviations between the experimental and calculated values of 0.028%, 0.013%, 0.017%, 0.044%, and 0.042%. In addition, the isothermal compressibility, isobaric thermal expansivity, and excess molar volume were derived from the modified Tait equation. [ABSTRACT FROM AUTHOR]

Studying the macroscopic‐phenomenological behavior of amorphous polymers at glass transition is often subject to limitations because the ordinary differential equations that describe the material behavior require numerical solution. To avoid these limitations, ad‐hoc‐formulated models of the glass transition have been proposed. However, their scope of application is expected to be limited due to insufficient theoretical foundation. This work establishes a theoretical framework for models that use the logistic function to approximate the macroscopic‐phenomenological behavior of amorphous polymers at glass transition. For this purpose, an exactly‐solvable Riccati equation is derived within thermodynamics with internal state variables. A closed‐form expression in terms of mathematical functions for the temperature derivative of a single internal state variable is the result. This closed‐form expression contains the logistic function thus featuring a continuous transition region centered around a pressure and cooling‐rate dependent transition temperature. Based on comparison of existing models with the exact solution derived from the Riccati equation, generalized models that approximate the thermal expansion coefficient and heat capacity at glass transition are proposed. This work thus demonstrates the validity of the logistic function in glass transition models of amorphous polymers and provides suggestions as to how existing models can be extended in their applicability. [ABSTRACT FROM AUTHOR]

Density, viscosity, refractive index, and ultrasonic velocity were measured for the pure materials anisole, methanol, and toluene, and for the binary mixtures: methanol—anisole and methanol—toluene. Excess molar volume VE, isobaric thermal compressibility α, excess Gibbs activation energy for fluid flow ΔGE*, and excess isentropic compressibility κSE were calculated from the measured quantities. For both binary mixtures VE and κSE were <0 while Δn > 0 and ΔGE* > 0 over the entire mole fraction composition range. Anisole mixtures exhibited more negative values for VE and κSE while more positive values were displayed for Δn and ΔGE* compared to toluene mixtures. For Δη, negative values were observed at low alcohol concentrations but positive values at high alcohol concentrations for both systems. [ABSTRACT FROM AUTHOR]

The chemical potential of a component in a solution is defined as the free energy change as the amount of that component changes. Computing this fundamental thermodynamic property from atomistic simulations is notoriously difficult because of the convergence issues involved in free energy methods and finite size effects. This Communication presents the so-called S0 method, which can be used to obtain chemical potentials from static structure factors computed from equilibrium molecular dynamics simulations under the isothermal–isobaric ensemble. This new method is demonstrated on the systems of binary Lennard-Jones particles, urea–water mixtures, a NaCl aqueous solution, and a high-pressure carbon–hydrogen mixture. [ABSTRACT FROM AUTHOR]

The high-pressure and high-temperature thermodynamic properties of rhodium (up to 2000 K and 300 GPa) are presented using the first principle approach within the quasi-harmonic approximation. The thermal Helmholtz free energy includes the contribution of both phonon vibrations and electronic excitations. The performance of three popular exchange-correlation functionals—local density approximation [Perdew et al., Phys. Rev. B 23, 5048 (1981)], Perdew–Burke–Ernzerhof generalized gradient approximation (PBE) [Perdew et al., Phys. Rev. Lett. 77, 3865 (1996)], PBE modified for dense solids [Perdew et al., Phys. Rev. Lett. 100, 136406 (2008)] are shown. The simulated thermal expansion coefficient, isobaric heat capacity, mode-Grüneisen parameter, thermodynamic average Grüneisen parameter, and bulk modulus are compared with the available experimental and theoretical reports. The contribution of thermal electronic excitations to the obtained thermodynamic parameters is significant at low pressure and high temperatures, except in bulk modulus, where it is small. The pressure-dependent elastic constant coefficient (Cij) and the Debye temperature are computed at 0 K. The Pugh ratio calculated from Cij indicates that rhodium undergoes brittle to ductile transitions at an average pressure of 7.45 GPa. [ABSTRACT FROM AUTHOR]

The entropy change that occurs upon mixing two fluids has remained an intriguing topic since the dawn of statistical mechanics. In this work, we generalize the grand-isobaric ensemble to mixtures and develop a Monte Carlo algorithm for the rapid determination of entropy in these systems. A key advantage of adiabatic ensembles is the direct connection they provide with entropy. Here, we show how the entropy of a binary mixture A–B can be readily obtained in the adiabatic grand-isobaric (μA, μB, P, R) ensemble, in which μA and μB denote the chemical potential of components A and B, respectively, P is the pressure, and R is the heat (Ray) function, that corresponds to the total energy of the system. This, in turn, allows for the evaluation of the entropy of mixing and the Gibbs free energy of mixing. We also demonstrate that our approach performs very well both on systems modeled with simple potentials and with complex many-body force fields. Finally, this approach provides a direct route to the determination of the thermodynamic properties of mixing and allows for the efficient detection of departures from ideal behavior in mixtures. [ABSTRACT FROM AUTHOR]

Featured Application: The research presented in this paper can be used to develop methods for determining optimal conditions for thermal and baric synthesis of materials. By the method of molecular dynamics, computer simulation of the processes of isobaric cooling of argon particle systems under initial conditions with a temperature of 150 K at pressure values from 0.1 to 4 MPa to a temperature of 40 K with cooling rates of 108, 109, 1010, 1011 and 1012 K/s was performed. As a result of a computer experiment, coordinate arrays of particles were obtained, which were subjected to the procedure of three-dimensional Voronoi partitioning to identify and calculate the number of elementary cells of the crystal structure. Analysis of the structure of argon solid phases formed during isobaric cooling allowed us to deduce an estimated pattern between the concentration of FCC (face-centered cubic) cells in solid argon and the cooling rate from the liquid state. The evaluation of the orientation of the axes of translation of crystal cells in the array of particle coordinates made it possible to classify the solid phases formed as a result of cooling as single crystals, glassy media with the inclusion of clusters and single cells of FCC structures. It was revealed that during isobaric cooling at a rate not exceeding 108 K/s, argon completely crystallizes, at isobaric cooling rates of 109–1010 K/s, the union of elementary cells of the crystal structure into clusters is observed in glassy argon, and at rates of 1011 K/s and higher at pressures of 1 MPa and lower, solid vitreous phases of argon are formed in which no crystal structure cells are detected. [ABSTRACT FROM AUTHOR]

Densities of pure furan, toluene, 1-octanol, n-hexane and of binary liquid mixtures containing furan, have been measured from 303.15 to 383.15 K at pressures up to 1.6 MPa, using a vibrating tube densimeter. Excess molar volumes have been calculated from the densities with an average standard uncertainty 0.02 cm3⋅mol−1. Excess molar enthalpies of the binary mixtures were measured at temperatures ranging from 313.15 to 383.15 K at 0.5 MPa and/or 1.0 MPa, using flow mixing calorimeter. The average standard uncertainty on the whole measurements is less than 1%. The excess molar properties derived from experimental data were correlated using Redlich–Kister polynomial functions and NRTL activity coefficient model and Prigogine–Flory–Patterson modelling is described and used to correlate the data. [ABSTRACT FROM AUTHOR]

R-1243zf is a new refrigerant that could replace R-134a. Its thermodynamic properties represented in the equation of state (EOS) play an essential role in analyzing and designing thermal systems. The EOS exists without including caloric property data due to unavailable data during the development time. New EOS was developed explicitly in Helmholtz free energy and optimized to represent the experimental data accurately and maintain thermodynamic consistency. The optimization process undergoes using a genetic algorithm and weighted-least squares regression. The experimental data used in the optimization have a range of 233-430 K and 0.106-34.6 MPa and were validated from the extrapolation and consistency to confirm the reliability. The average absolute deviation from the data is 0.48% for the ideal gas isobaric specific heat, 1.7% for the isochoric specific heat, 0.33% for the speed of sound, 0.22% for the liquid density in single-phase, 0.49% for the vapor density in single-phase, 0.96% for the vapor pressure, 2.2% for the saturated liquid density, and 3.2% for the saturated vapor density. The EOS has a reasonable extrapolation behavior from the triple point up to 700 K and 100 MPa. [ABSTRACT FROM AUTHOR]

We present an experimental investigation of surface tension–driven sintering and associated densification of glassy rhyolitic ash and crystals under shallow volcanic conduit conditions. Rhyolitic glass (< 45 μm) and quartz were run in suites of hydrothermal experiments for 30 min to 9 h. Fluid pressure was isobaric ( P H 2 O = 40 M P a ) for all runs, and temperature was held constant at a value between 675 and 850 °C. Three size populations of quartz were used: 45–76 µm (fine), 90–125 µm (medium), and 250–500 µm (coarse). All samples evolved from loose, cohesion-less particles to a friable, agglutinated framework of glass with an interconnected network of pores of ≥ 15 vol.%. Samples sintered more slowly at cooler temperatures and with finer crystals relative to higher temperatures or coarser crystals. Compared with previous experiments on glass-only samples, all crystal-bearing samples reached a higher final porosity, and those containing fine and medium crystals also sintered more slowly. Permeability was determined via numerical simulation for one sample and was found to be similar to natural samples with equivalent porosity. Our results suggest that solid particles inhibit the sintering process by holding porous networks open. Sintered magma in the shallow conduit that contains crystal (and lithic) particles can thus experience more sustained degassing and outgassing than crystal-free systems. [ABSTRACT FROM AUTHOR]

A fundamental equation of state expressed explicitly in the Helmholtz energy is presented for R-1224yd(Z), an environmentally friendly refrigerant for centrifugal chillers, high-temperature heat pumps, and organic Rankine cycles. The equation of state is based on consistent experimental data for the critical parameters, vapor pressures, saturated liquid and vapor densities, (p , ρ , T) behavior, vapor-phase sound speeds, liquid-phase sound speeds, and ideal-gas isobaric heat capacities. The equation is valid at temperatures from the triple-point temperature (157.8 K) to 473 K and pressures up to 35 MPa. In the valid range, expected relative uncertainties ( k = 2 ) of the equation are 0.04 % for vapor pressures, 0.1 % for saturated liquid densities, 2 % for saturated vapor densities, 0.05 % for liquid densities, 0.3 % for vapor densities, 0.02 % for vapor-phase sound speeds, and 0.04 % for liquid-phase sound speeds, except in the critical region, where more significant uncertainties of up to 2 % are sometimes observed in densities. The equation exhibits reasonable behavior in the critical and extrapolated regions; this is demonstrated by several plots of derived properties over wide ranges of temperature and pressure. [ABSTRACT FROM AUTHOR]

The pressure-volume-temperature-entropy equations of state, P-V-T-S Eos, of polyethylene (PE) for its isothermal, isobaric, isochoric and isoentropic ensembles and the correlation between the P-V-T-S Eos in the various ensembles were reported in our previous reports. The three dimensional plane plot, 3D plane plot, for the various ensembles, such as the 3D (PV-V-SV) isochoric plane plot, and the three dimensional list point plot, 3D list point plot, for the ensemble, such as the 3D (PT, VT, ST) isothermal list point plot, were determined based on the P-V-T-S Eos of PE where the subscripts, T, P, V, and S meaning for the isothermal, isobaric, isochoric and isoentropic ensembles, respectively. In this paper a projection of the 3D list point plot on the 3D plane plot for an appropriate pair of the planes gave a new 3D plot where the list points in the 3D list point plot were found on the surface of the 3D plane plot. [ABSTRACT FROM AUTHOR]

Platinum-based chemotherapy is commonly used in the treatment of various cancers, including epithelial ovarian cancer (EOC). However, in EOC, chemotherapy failure is mainly caused by platinum resistance. In this present study, we aimed to identify novel biomarkers for predicting platinum chemosensitivity. Fresh specimens of 16 serous high-grade ovarian cancer (HGSC) cases were collected during cytoreductive surgery. Isobaric tags were used to identify differentially expressed proteins in platinum-resistant samples (n = 8) and platinum-sensitive samples (n = 8). Compared to platinum-sensitive samples, 741 significantly differentially expressed proteins were detected, of which 325 were upregulated and 416 were downregulated. To validate the isobaric tags for relative and absolute quantification (iTRAQ) method, western blotting was performed on two upregulated proteins, angiomotin-like protein 1 (AMOTL1) and Lumican. The results showed that platinum-resistant tumor samples expressed significantly higher levels of AMOTL1 and Lumican than platinum-sensitive tumor samples. Altogether, we identified candidate proteins related to platinum resistance in ovarian cancer. Both AMOTL1 and Lumican seem to be promising biomarkers that could distinguish between platinum-resistant and platinum-sensitive EOC. [ABSTRACT FROM AUTHOR]

Evolutionary crystal structure prediction searches have been employed to explore the ternary Li–F–H system at 300 GPa. Metastable phases were uncovered within the static lattice approximation, with LiF3H2, LiF2H, Li3F4H, LiF4H4, Li2F3H, and LiF3H lying within 50 meV/atom of the 0 K convex hull. All of these phases contain H n F n + 1 − (n = 1, 2) anions and Li+ cations. Other structural motifs such as LiF slabs, H 3 + molecules, and Fδ− ions are present in some of the low enthalpy Li–F–H structures. The bonding within the H n F n + 1 − molecules, which may be bent or linear, symmetric or asymmetric, is analyzed. The five phases closest to the hull are insulators, while LiF3H is metallic and predicted to have a vanishingly small superconducting critical temperature. Li3F4H is predicted to be stable at zero pressure. This study lays the foundation for future investigations of the role of temperature and anharmonicity on the stability and properties of compounds and alloys in the Li–F–H ternary system. [ABSTRACT FROM AUTHOR]

In this work, the isothermal vapor–liquid equilibrium (VLE) of trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and 1,1,1,3,3-pentafluoropropane (HFC245fa) binary system, along with the saturated vapor pressures HFO-1234ze(E) and HFC-245fa, were measured by static-analytic apparatus. The VLE measurements of HFO-1234ze(E) + HFC-245fa binary system are performed at temperatures from (293.28 to 333.09) K, while the measurements for vapor pressures of HFO1234ze(E) and HFC-245fa were conducted in the temperature range of (263.08 to 363.01) K. The vapor pressures were correlated by the Peng-Robinson (PR) equation of state (EoS) associated with the Mathias-Copeman (MC) alpha function, and the VLE data were correlated to the PRMC-vdW model where the MC alpha function and the van der Waals (vdW) mixing rules were combined with the PR EoS. The experimental VLE data were compared with the predictive E-PPR78 model. The modeling results of the PRMC-vdW model had good agreement with the experimental VLE data, while the E-PPR78 model shows negative bias in the prediction of equilibrium pressures. The experimental VLE data were also compared with literature data for consistency checks. The two sets of VLE data were basically consistent, while a discrepancy was found when analyzing the relationship between binary interaction parameter kij and temperature. [ABSTRACT FROM AUTHOR]

The relevance of research into the thermophysical properties of lead is associated with the implementation of a BREST-300 reactor project. The enthalpy of solid and liquid lead in the range of 432–1327 K was measured by the mixing method using a massive isothermal calorimeter. The enthalpy of melting was determined. Approximation equations for the temperature dependence of enthalpy in the range of 298.15–1325 K were obtained to determine the isobaric heat capacity. The existence of a heat capacity minimum for liquid lead in the region of 830 K was established. An analysis of existing recommended and experimental data on the caloric properties of lead was performed. The need for new measurements of the enthalpy and heat capacity of a melt at temperatures above 1050 K is substantiated. [ABSTRACT FROM AUTHOR]

Accurate determination of the thermophysical properties of hydrogen is a crucial issue in hydrogen system design. By developing computational programs, a statistical thermodynamic model based on fundamental equations of state was implemented to determine hydrogen's thermophysical properties, including the ortho-hydrogen fraction in equilibrium hydrogen, para-ortho hydrogen conversion heat, isobaric heat capacities and enthalpies. The deviations of calculated para-hydrogen enthalpies from REFPROP data were within 2.22%, ranging from 20 K to 300 K at 0.1 MPa, and within 2.32% between 100 K and 1500 K at pressures from 0.1 MPa to 20 MPa. To quantitatively assess the convenience of the statistical thermodynamic method, the running speeds of programs with different methods for determining hydrogen's thermophysical properties were compared. The time required for statistical thermodynamic calculation was 7.95% that required for treading REFPROP data when the performance of the variable density multilayer insulation combined with a one vapor-cooled shield and para-ortho hydrogen conversion was calculated. The programs developed based on the statistical thermodynamic method can be used to determine the thermophysical properties of hydrogen or other fluids. [ABSTRACT FROM AUTHOR]

Despite its increasing application to estimate magma decompression rates for explosive eruptions, the embayment speedometer has long awaited critical experimental evaluation. We present the first experimental results on the fidelity of natural quartz‐hosted embayments in rhyolitic systems as recorders of magma decompression. We conducted two high pressure‐temperature isobaric equilibrium experiments and 13 constant‐rate, continuous isothermal decompression experiments in a cold‐seal pressure vessel where we imposed rates from 0.005 to 0.05 MPa s−1 in both H2O‐saturated and mixed‐volatile (H2O + CO2)‐saturated systems. In both equilibrium experiments, we successfully re‐equilibrated embayment melt to new fluid compositions at 780°C and 150 MPa, confirming the ability of embayments to respond to and record changing environmental conditions. Of the 32 glassy embayments recovered, seven met the criteria previously established for successful geospeedometry and were thus analyzed for their volatile (H2O ± CO2) concentrations, with each producing a good model fit and recovering close to the imposed decompression rate. In one H2O‐saturated experiment, modeling H2O concentration gradients in embayments from three separate crystals resulted in best‐fit decompression rates ranging from 0.012 to 0.021 MPa s−1, in close agreement with the imposed rate (0.015 MPa s−1) and attesting to the reproducibility of the technique. For mixed‐volatile experiments, we found that a slightly variable starting fluid composition (2.4–3.5 wt.% H2O at 150 MPa) resulted in good fits to both H2O + CO2 profiles. Overall our experiments provide confidence that the embayment is a robust recorder of constant‐rate, continuous decompression, with the model successfully extracting experimental conditions from profiles representing nearly an order of magnitude variation (0.008–0.05 MPa s−1) in decompression rate. Plain Language Summary: Embayments are pockets of melt within crystals that remain in open communication with the surrounding magma, allowing their compositions to change through time. When rising magma carries an embayment‐bearing crystal toward the surface, volatiles (e.g., H2O, CO2) dissolved in the melt will diffuse through the embayment to maintain equilibrium with the surrounding degassing melt. Upon eruption and rapid cooling, volatile concentration gradients are preserved within embayment channels. This is the basis for the embayment speedometer: the volatile concentration gradients can be directly measured and numerically modeled to estimate the rate of decompression experienced by the magma. Since its formalization over a decade ago, this technique has been applied extensively, with 11 published studies leveraging the embayment speedometer to estimate magma decompression rates for 17 rhyolitic to basaltic explosive eruptions, and several additional studies in preparation. Despite the increasing application of this technique, no work to date has experimentally evaluated embayments to assess their reliability as recorders of magma decompression under controlled conditions. In this study, we use high pressure‐temperature decompression experiments to subject embayments to the conditions experienced during magma ascent. We apply numerical models to volatile analyses of the embayments to evaluate how reliably embayments record the imposed conditions. Key Points: Using equilibrium and decompression experiments, we show that natural embayments partially equilibrate on timescales of magma ascentWe build upon previous work developing embayments as reliable recorders of magma decompression rates between 0.008–0.05 MPa s−1We produce the full range of textures (glassy to vesiculated) observed in natural embayments both inter‐ and intra‐experimentally [ABSTRACT FROM AUTHOR]

This work presents a fundamental equation of state for the thermodynamic properties of R-1336mzz(E). The equation of state is expressed explicitly in the Helmholtz energy with temperature and density as the independent variables, and is based on consistent experimental datasets, including the critical parameters, vapor pressure, saturated liquid and vapor densities, (p , ρ , T) behavior, vapor phase sound speed, and ideal-gas isobaric heat capacity. The equation of state is valid for temperatures from 200.15 K to 410 K and pressures up to 5.7 MPa. In this range, expected relative uncertainties at the 95 % confidence interval ( k = 2 ) are 0.1 % for vapor pressures, 1 % for saturated liquid densities, 1 % for saturated vapor densities, 0.15 % for liquid densities, 0.5 % for vapor densities, and 0.05 % for vapor phase sound speeds, except in the critical region where larger uncertainties of up to 2 % are sometimes observed in densities. The equation exhibits reasonable behavior in the critical and extrapolated regions; this is demonstrated by several plots of derived properties over wide ranges of temperature and pressure. Through the use of the new equation of state, this work also formulates an extended corresponding states (ECS) model for the viscosity and thermal conductivity of R-1336mzz(E) to represent recent experimental data for these properties mostly within their uncertainties. [ABSTRACT FROM AUTHOR]

A dual-capillary apparatus was developed for highly accurate measurements of density of liquids, including the supercooled liquid region. The device was used to determine the density of supercooled heavy water in the temperature range from 254 K to 298 K at pressures ranging from atmospheric to 100 MPa, relative to density at reference isotherm 298.15 K. The measurements of relative density were reproducible within 10 ppm, and their expanded (k = 2) uncertainty was within 50 ppm. To obtain absolute values of density, thermodynamic integration was performed using recent accurate speed of sound measurements in the stable liquid region. An empirical equation of state (EoS) was developed, giving specific volume as a rational function of pressure and temperature. The new experimental data are represented by EoS within their experimental uncertainty. Gibbs energy was obtained by EoS integration allowing computation of all thermodynamic properties of heavy water using Gibbs energy derivatives. Although based on data in relatively narrow temperature and pressure ranges, the developed EoS shows an excellent agreement with literature data for densities, isothermal compressibilities, and isobaric expansivities of deeply supercooled heavy water. The curvature of the thermodynamic surface steeply increases toward low temperatures and low pressures, thus supporting the existence of the hypothesized liquid-liquid coexistence boundary in a close vicinity of existing experimental data. [ABSTRACT FROM AUTHOR]

The process of inserting/deleting a particle during grand-canonical Monte-Carlo (MC) simulations is investigated using a novel, original technique: the trial event is made of a short nonequilibrium molecular dynamics (MD) trajectory during which a coordinate w along a 4th dimension is added to the particle in the course of insertion/deletion and is forced to decrease from large values down to zero (for insertion) or increased from 0 up to large values (for extraction) at imposed vw velocity. The probability of acceptation of the whole MC move is controlled by the chemical potential and the external work applied during the trajectory. Contrary to the standard procedures which create/delete suddenly a particle, the proposed technique gives time to the fluid environment to relax during the gradual insertion/extraction before the acceptation decision. The reward for this expensive trial move is a gain of many orders of magnitude in the success rate. The power and wide domain of interest of this hybrid "H4D" algorithm which marries stochastic MC and nonequilibrium deterministic MD flavors are briefly illustrated with hard sphere, water, and electrolyte systems. The same approach can be easily adapted in order to measure the chemical potential of a solute particle immersed in a fluid during canonical or isobaric simulations. It then becomes an efficient application of the Jarzynski theorem for the determination of solvation free energy. [ABSTRACT FROM AUTHOR]

The energetic molecular crystal cyclotrimethylene trinitramine (HMX) is a key constituent in common plastic bonded explosives. Its plastic deformation under shock conditions is important in reaction initiation and detonation. Here, we study the effect of high pressure on dislocation slip using isothermal-isobaric atomistic simulations. We consider two slip planes, (011) and (101) , that are reported to be most active under ambient conditions. For all slip systems considered, the effect of pressure is to increase the critical resolved shear stress for dislocation slip. Pressure may fully inhibit dislocation-based plasticity if the resolved shear stress is not increased in proportion. On the other hand, at sufficiently high shear stresses, the crystal loses shear stability. Therefore, in a broad range of shock conditions, plastic deformation takes place by a combination of dislocation glide in some slip systems and localization in some other systems, with dislocation activity being gradually inhibited as the shock pressure increases. This provides new data on the physical basis of plastic deformation in HMX, indicating that mesoscale representations of plasticity must include shear localization, which is more important under these conditions than dislocation plasticity. [ABSTRACT FROM AUTHOR]

We introduce a molecular simulation method to compute the interfacial properties of model systems within the isothermal-isobaric ensemble. We use a free-energy-based approach in which Monte Carlo simulations are employed to obtain an interface potential associated with the growth of a fluid film from a solid substrate. The general method is implemented within "spreading" and "drying" frameworks. The interface potentials that emerge from these calculations provide direct access to spreading and drying coefficients. These macroscopic properties are then used to compute the liquid-vapor surface tension and the contact angle of a liquid droplet in contact with the substrate. The isothermal-isobaric ensemble provides a means to change the thickness of the fluid film adjacent to the substrate by modifying the volume of the simulation box. Molecular insertions and removals are not necessary. We introduce a framework for performing local volume change moves wherein one attempts to modify the density of a narrow region of the simulation box. We show that such moves improve the sampling efficiency of inhomogeneous systems. The approach is applied to a model system consisting of a monatomic Lennard-Jones fluid in the vicinity of a structureless substrate. Results are provided for direct spreading and drying interface potential calculations at several temperatures and substrate strengths. Expanded ensemble techniques are used to evaluate interfacial properties over a wide range of temperatures and substrate strengths. The results obtained using the isothermal-isobaric approach are compared with those previously obtained via a grand canonical approach. [ABSTRACT FROM AUTHOR]

In the Western Gneiss Region in Norway, mafic eclogites form lenses within granitoid orthogneiss and contain the best record of the pressure and temperature evolution of this ultrahigh‐pressure (UHP) terrane. Their exhumation from the UHP conditions has been extensively studied, but their prograde evolution has been rarely quantified although it represents a key constraint for the tectonic history of this area. This study focused on a well‐preserved phengite‐bearing eclogite sample from the Nordfjord region. The sample was investigated using phase‐equilibrium modelling, trace‐element analyses of garnet, trace‐ and major‐element thermobarometry and quartz‐in‐garnet barometry by Raman spectroscopy. Inclusions in garnet core point to crystallization conditions in the amphibolite facies at 510–600°C and 11–16 kbar, whereas chemical zoning in garnet suggests growth during isothermal compression up to the peak pressure of 28 kbar at 600°C, followed by near‐isobaric heating to 660–680°C. Near‐isothermal decompression to 10–14 kbar is recorded in fine‐grained clinopyroxene–amphibole–plagioclase symplectites. The absence of a temperature increase during compression seems incompatible with the classic view of crystallization along a geothermal gradient in a subduction zone and may question the tectonic significance of eclogite facies metamorphism. Two end‐member tectonic scenarios are proposed to explain such an isothermal compression: Either (1) the mafic rocks were originally at depth within the lower crust and were consecutively buried along the isothermal portion of the subducting slab or (2) the mafic rocks recorded up to 14 kbar of tectonic overpressure at constant depth and temperature during the collisional stage of the orogeny. [ABSTRACT FROM AUTHOR]

Solubility of CO 2 in ionic liquids (ILs) is of great importance in absorption refrigeration system as new working pairs. Vapor-liquid equilibrium (VLE) of CO 2 in [BMP][Tf 2 N] (1-butyl-1-methyl-pyrrolidine bis(trifluoromethylsulfonyl)imide) is carried out experimentally using the experiment system at temperature range 303.15 K-363.15 K. The experimental results show that the solubility of CO 2 in [BMP][Tf 2 N] can reach up to 0.1235–0.5324 (molar fraction) within temperature range 283.15∼363.15 K and pressure range of 0.2∼5 MPa. The solubility of CO 2 in [BMP][Tf 2 N] increases with increase of temperature and pressure. The VLE data of CO 2 -[BMP][Tf 2 N] binary system is correlated with two models (SRK equation of state +WS mixing rule +UNIFAC activity coefficient model and PR equation of state +WS mixing rule +UNIFAC activity coefficient model). The excess Gibbs free energy (GE), excess enthalpy (HE) and excess entropy (SE) of the system are obtained and the interaction parameters k ij is regressed based on the VLE of CO 2 -[BMP][Tf 2 N] binary system. The variation trend of GE, HE and SE are obtained with temperature, pressure and molar fraction of CO 2. The calculation results show that the accuracy of SRK equation of state is slightly higher than that of PR equation of state in CO 2 -[BMP][Tf 2 N] binary system. The accuracy of SRK equation of state and PR equation of state decreases with increase of temperature and pressure. [ABSTRACT FROM AUTHOR]

In the article, the real and optimal hourly thermal energy balance of the helical compressor was designed. Through a technically feasible measure, the specific consumption of the helical compressor was reduced, and the effective heat recovered was then calculated. [ABSTRACT FROM AUTHOR]

Elastic properties of strongly anisotropic hard cyclic tetramers are studied in the isobaric–isothermal ensemble using Monte Carlo simulations. The tetramers are model molecules consisting of four hard disks of diameter σ with centers forming a square of side d. Recently, it was shown that 2D crystals of hard cyclic tetramers (with anisotropy parameter α=d/σ=1.7) can form a chiral phase, which is (completely) auxetic, that is, its Poisson's ratio is negative in all directions. Herein, the complete pressure dependence of the Poisson's ratio of the tetramer crystalline phase is presented. These studies show that the auxetic properties occur over a wide pressure range, but the tetramer system is only partially auxetic at low pressures. The Poisson's ratio of the system varies with pressure between −0.597(3) and 0.500(3). [ABSTRACT FROM AUTHOR]

At ambient conditions two liquids, bromoethane, C2H5Br (MBE, m.p. 154.6 K) and iodoethane, C2H5I (MIE, m.p. 162.1 K), have been crystallized under both isobaric and isochoric conditions using in situ low‐temperature and high‐pressure techniques. The single‐crystal X‐ray diffraction studies, supported by the isothermal compressibility and isobaric differential scanning calorimetry measurements, allowed the monitoring and analysis at low temperature and high pressure of the effects of externally induced changes in MBE and MIE. The monoclinic MBE and MIE crystals are found to be isostructural. They are stable, in the investigated regimes, i.e. down to 100 K/0.1 MPa and up to ∼295 K/3.7 GPa, without undergoing any symmetry or phase change. Both the contraction and compression is mainly noted for the intermolecular separation distances. The Hirshfeld surface analysis of intermolecular contacts clearly shows the nature of occurrence and hierarchy of interactions pointing out the role played by Br/I...Br/I contacts, in particular at ambient temperature and high‐pressure conditions. The preferences for the formation of intermolecular contacts in MIE are more pronounced and do not require such extreme conditions as in the case of MBE. It is notable that the Br/I...Br/I and Br/I...H contacts could be basically classified as type‐I interactions. [ABSTRACT FROM AUTHOR]

Pressure and temperature induced valence changes in the Kondo insulator SmB 6 have been investigated using x-ray absorption spectroscopy (XAS) along several isobaric cooling runs and one isothermal compression. The average valence of Sm at various pressure and temperature conditions is extracted from high quality XAS data by peak fitting procedures. The temperature dependence of the Sm valence at ambient pressure shows changes of slope near the known characteristic temperatures of gap formation (120 K) and the in-gap state (50 K). At higher pressures the average valence also shows similar temperature dependent trends upon cooling but the slope changes are less pronounced. This behavior is discussed in relation to the possible existence of an underlying first order valence transition and its critical end point. At constant temperature (T = 20 K), the Sm valence increases rapidly with pressure; however, it remains far below the expected integer value (3+) near the onset of the magnetic ordering and gap closure. In addition, the local structure of SmB 6 at ambient conditions has been analyzed using extended x-ray absorption fine structure. • Pressure effects on the temperature dependence of Sm valence have been investigated. • Indications of a possible correlation between Kondo insulating behavior and critical valence fluctuations in SmB 6 have been observed. • Local structure of SmB 6 has been investigated using EXAFS refinements. [ABSTRACT FROM AUTHOR]

• Density measurements were conducted for the mixture of 1-butanol and two biodiesels under high-pressure conditions (up to 100 MPa). • Excess volumes were calculated for the blend of 1-butanol + biodiesel. • Correlation with the Tammann-Tait equation was performed, and derived properties were calculated. • Thermodynamic modeling was carried out using the PC-SAFT equation of state. Biodiesel, derived from renewable sources, offers advantages like biodegradability and compatibility with diesel engines. However, high production costs and low-temperature viscosity issues must be addressed. This could be mitigated by blending biodiesel with medium-chain alcohols. This study aims to assess the volumetric properties of the 1-butanol + biodiesel system under high-pressure conditions (0.1 – 100 MPa) and various temperatures (293.15 – 373.15 K) using a DMA HPM device from Anton Paar. Integrating experimental and modeling approaches, we applied equations to obtain derived properties and correlate density data. Equations such as Tammann-Tait and PC-SAFT were applied to the experimental data, yielding maximum mean absolute percentage deviations (DMRA Max.) of 0.011 % and 0.439 %, respectively, indicating satisfactory fits to the experimental data. The excess volumes were calculated, revealing minimal deviation from ideal behavior, with a maximum deviation of 0.15 % of the total volume. This suggests that the volumetric behavior of the 1-butanol + methyl biodiesel system closely resembles that of an ideal solution. We used both equations to obtain derived properties, such as the compressibility (κ T) and the isobaric thermal expansivity (α P). It was observed that the PC-SAFT equation has some limitations in its prediction. From these results, a crossing point in isobaric thermal expansivity (α P) was observed; this could be attributed to increasing biodiesel content, potentially linked to the effects of intermolecular forces. [ABSTRACT FROM AUTHOR]

Isothermal-isobaric path integral centroid molecular dynamics simulations were conducted for fluid 4He at more than 600 state points in the proximity of the critical point to reveal the detailed states and relevant quantumness underlying the supercritical state. Through intensive analyses of the thermodynamic, dynamic, and quantum properties, we revealed the hidden state boundaries that separate the liquid-like and gas-like states in the supercritical region of this fluid. The Widom line, defined as the locus of the maxima of isobaric heat capacity CP, is also the quantum boundary at which there are changes in the isobaric temperature-dependence of the quantum wavelength, λquantum, i.e., maximum amplitude of the Feynman imaginary-time paths (necklaces) of individual atoms. The Frenkel line, the famous dynamic state boundary, was observed to start from nearly the same point, 0.73-0.76 Tc, on the P-T plane as observed for classical fluids. Several state boundaries based on the new criteria were found to emanate from the critical point or its vicinity on the P-T plane and are discussed in comparison with these boundaries. The quantumness of this fluid was expressed as (a) non-classical significant depression of CP observed in the liquid-like state; (b) the depression of the slopes dP/dT of the Widom line and the liquid-gas coexistence line near the critical point; and (c) the depression of the heat of pseudo-boiling across the Widom line. This is explained in terms of the decreasing kinetic energy with temperature observed in the liquid-like state below the Widom temperature TWidom, or alternatively in terms of the lattice model heat capacity, including the λquantum. [ABSTRACT FROM AUTHOR]

Murphy and Koop's 2005 equation is used as a standard for vapor pressure in supercooled water. Recently, however, new measurements of molar heat capacity of supercooled water have emerged that both show a more rapid increase in isobaric heat capacity in the supercooled region and penetrate well below the homogeneous nucleation limit. These new data lead to the need to recalculate the saturation vapor pressure in the supercooled region. An equation describing the temperature dependence of the saturation vapor pressure in the temperature interval from 150 K to 273.16 K is presented. [ABSTRACT FROM AUTHOR]

As part of the work the high-pressure sorptomat - a novel apparatus for sorption tests under conditions of high gas pressure was developed. The sorption measurement is carried out using the volumetric method, and the precise gas flow pressure regulator is used in the device to ensure isobaric conditions and regulate the sorption pressure in the range of 0-10 MPa. The uniqueness and high precision of sorption measurements with the constructed apparatus are ensured by the parallel use of many pressure sensors with a wide measurement range as well as high precision of measurement - due to the use of precise pressure sensors. The obtained results showed, i.a. that the time of reaching the isobaric conditions of the measurement is about 6-7 seconds and it is so short that it can be considered a quasi-step initiation of sorption processes. Moreover, the results of the measurement pressure stabilization tests, during the CO2 sorption test on activated carbon, have shown that the built-in pressure regulator works correctly and ensures isobaric sorption measurement conditions with the precision of pressure stabilization of ±1% of the measurement pressure. The maximum range of sorption measurement using the high-pressure sorptomat is 0-86 400 cm3/g, and the maximum measurement uncertainty is ±2% of the measured value. The activated carbon sample used for the tests was characterized by a high sorption capacity, reaching 104.4 cm³/g at a CO2 pressure of 1.0 MPa. [ABSTRACT FROM AUTHOR]

In our previous report, an empirical partition function, f , for polyethylene (PE) was determined based on a pressure (PV) – temperature (TV) – volume (V) – entropy (SV) equation of state where the variables, PV, TV and SV, were isochoric variables with V = const. evaluated by using the experimental P-V-T data and the isobaric heat capacity, CP, at 1 atm. In this work we describe the proposal of a modified, reformed partition function of the Debye model, l n f m − R D , where the l n f m − R D is expressed by the summation of the terms of T, T−1 and T3 and the Boltzmann factors of e − i θ 1 T for i = 1, 2, 3 and 6. The modified reformed pressure, P m − R D , at constant volume calculated based on the l n f m − R D showed that the Boltzmann factors, e − i θ 1 T , for i = 3 and 6 were dominant and increased with increasing temperature and the T 2 and T 4 terms were negative and decreased with increasing temperature, while the modified reformed entropy, S m − R D , showed that the Boltzmann factors of e − i θ 1 T for i = 3 and 6 were also dominant and increased with increasing temperature and the T 3 term increased rapidly over a higher temperature range. All Boltzmann factors of e − i θ 1 T for i = 1, 2, 3 and 6 in the modified reformed isochoric heat capacity, CV,m-RD, calculated based on the l n f m − R D , were positive, which was different from that in the previous work where one negative Boltzmann factor was observed. [ABSTRACT FROM AUTHOR]

Equations of state for n-hexadecane (C16H34) and n-docosane (C22H46) have been developed as functions of the Helmholtz energy with independent variables of temperature and density. The equations were developed based on experimental values of density, speed of sound, isobaric heat capacity, and vapor pressure. With these equations, all thermodynamic properties of n-hexadecane and n-docosane can be calculated. For n-hexadecane, the uncertainty in vapor pressure is 0.5 %. The uncertainty of the saturated liquid density is 0.05 % from the triple point up to 400 K, and 0.2 % at higher temperatures. The uncertainty in densities is within 0.5 %. The speed of sound and isobaric heat capacity can be calculated within 0.25 %. The uncertainties of the properties calculated with the equation for n-docosane are 5 % for vapor pressure, 0.1 % for saturated liquid density, 1 % for density, 0.5 % and 1 % for speed of sound at atmospheric pressure and higher pressures, respectively, and within 3 % for heat capacity. [ABSTRACT FROM AUTHOR]

• Physico-chemical parameters are involved through the grand canonical ensemble. • The internal energy of the WPT-AC/ethanol and M-AC/ethanol systems are calculated. • The enthalpy and entropy functions of the adsorption cooling cycles are derived. • The COP is calculated by means of statistical physics treatment • Discussion of the obtained COP for different two cycles was showed. Thermodynamic analysis of two different adsorption cooling cycles was presented; the first cycle is based on an isobaric adsorption process and the second one projects an isothermal adsorption instead of an isobaric adsorption. These cooling cycles are carried out by employing the grand canonical ensemble of the statistical physics formalism. This investigation is done for two different adsorbate/adsorbent pairs i.e. Ethanol/Waste Palm Trunk (WPT-AC) and Ethanol/Mangrove wood (M-AC). The corresponding adsorption isotherms have been fitted by statistical physics models to give a description of the adsorption process through interpretations of the evolution of the involved physico-chemical parameters, specific for this process. The results showed that the ethanol molecules have been mainly adsorbed with a multimolecular process and non-parallel to the adsorbent surface involving an aggregation process before molecules adsorption. Their adsorption energies are varying from 1.40 to 3.64 kJ/mol for WPT-AC and from 3.2 to 3.81 kJ/mol for the M-AC. These values reflected a physisorption process. The calculated internal energy values suggested the exothermicity and the spontaneity of the ethanol adsorption process. The investigation aims providing a methodology of calculation of the COP for an adsorption cooling cycle by using the statistical physics treatment. The entropy and the enthalpy functions are calculated and used to perform the thermodynamic evaluation and to calculate the coefficient of performance (COP). This parameter was found to be in the interval [0.12–0.69] for ethanol/WPT-AC and [0.11-0.6] for ethanol/M-AC for the first cycle and for the second cycle [0.15-0.81] and [0.15-0.74] respectively. [ABSTRACT FROM AUTHOR]

The pressure–volume–temperature–entropy equations of state, P–V–T–S Eos, of polyethylene (PE) for its isothermal, isobaric and isochoric ensembles were reported in our previous report (Part 1). In this report the correlation between the P–V–T–S Eos in the various ensembles was analyzed quantitatively where it was found that the three dimensional P–T–V plane for the PT–T–VT Eos in the isothermal ensemble was almost the same as that for the P–TP–VP Eos in the isobaric ensemble, while the 3D T–P–S plane for the T–PT–ST Eos in the isothermal ensemble was almost the same as that for the TP–P–SP Eos in the isobaric ensemble where the subscript of T and P mean isothermal and isobaric ensembles, respectively. The isothermal bulk modulus, κ T , and its first and second pressure derivatives ( ∂ κ T ∂ P ) T , and ( ∂ 2 κ T ∂ P 2 ) T , were calculated and it was found that the 3D T–PT– κ T plane in the isothermal ensemble was almost the same as that for the TP–P– κ T in the isobaric ensemble, and the 3D T–PT– ( ∂ K T ∂ P ) T plane in the isothermal ensemble was different only slightly from the 3D TP–P– ( ∂ K T ∂ P ) T plane in the isobaric ensemble, while a considerable difference was observed between the 3D T–P– ( ∂ 2 K T ∂ P 2 ) T planes for the isothermal and isobaric ensembles. [ABSTRACT FROM AUTHOR]

A review of recent advances in the study of the energy splitting between excited isobaric analogue states is presented. Some of the experimental developments, and new approaches, associated with spectroscopy of the most proton-rich members of isobaric multiplets, are discussed. The review focuses on the immense impact of the shell-model in the analysis of energy differences and their interpretation in terms of nuclear structure phenomena. [ABSTRACT FROM AUTHOR]

A new fundamental equation of state is presented for 2,3,3,3-tetrafluoroprop-1-ene (R1234yf). The equation is valid from the triple point temperature (121.6 K) to 410 K at pressures up to 100 MPa, where typical expanded uncertainties (k = 2) in calculated properties from the equation are 0.1 % for vapor pressures at temperatures above 270 K and 0.3 % at lower temperatures, 0.1 % for liquid densities at pressures below 40 MPa and 0.25 % at higher pressures, 0.2 % for vapor densities, 0.02 % for vapor phase sound speeds, 0.05 % for liquid phase sound speeds, 1 % for vapor phase isobaric heat capacities, 2 % for liquid phase isobaric heat capacities, and 2 % for liquid phase isochoric heat capacities. At very low temperatures around 200 K, uncertainties for vapor pressures may be larger than 0.5 %. Various plots of constant-property lines demonstrate that not only does the equation exhibit correct behavior over all temperatures and pressures within the range of validity, but also that it shows reasonable extrapolation behavior at extremely low and high temperatures, and at high pressures and densities. The equation of state is the best currently available property representation for R1234yf, and has been adopted as an international standard by the ISO working group, which recently revised ISO/DIS 17584 (Refrigerant properties). [ABSTRACT FROM AUTHOR]

Due to the advantages of high temperature stability, low corrosion, and good heat transfer performance, potassium nitrate aqueous solution holds application potential in absorption systems. In order to further improve its absorption ability, ionic liquids (ILS) such as [Emim]Cl, [Emim]Ac, and [Emim]Br were selected as additives. In this paper, vapor pressures of four {KNO3 + ILS + H2O} ternary systems were measured by a dynamic boiling point method, including {KNO3 + [Emim]Cl + H2O}, {KNO3 + [Emim]Ac + H2O}, {KNO3 + [Emim]NO3 + H2O}, and {KNO3 + [Emim]Br + H2O}. Molar ratios between KNO3 and ILs were 1:1 for these systems, and the total absorbent mass fractions were in the range of 0.20 to 0.70. Experimental data were regressed by Antoine-type equations, and the average absolute relative deviations (AARD%) between the experimental and calculated values were no more than 0.78%, which showed good consistency of these experiments. Vapor–liquid equilibrium behavior of these different ionic liquid ternary systems were compared and [Emim]Ac showed best performance in reducing vapor pressure at relatively higher mass fractions. [ABSTRACT FROM AUTHOR]

This work aims to present results of density (ρL), isobaric thermal expansivity coefficient (αP,L) and isothermal compressibility coefficient (kT,L) correlations for n-dodecane and n-nonane as a function of temperature and pressure, able to obtain these properties at any temperature and pressure in the range of 4 °C to 40 °C and 0.1 MPa to 15.0 MPa, with low uncertainties (in the case of n-dodecane: 0.00025 g⋅cm−3 for ρL; 0.00020 °C−1 for αP,L and 0.00022 MPa−1 for kT,L and in the case of n-nonane: 0.00026 g⋅cm−3 for ρL; 0.00006 °C−1 for αP,L and 0.00032 MPa−1 for kT,L). The density measurements were performed using a pycnometer that was calibrated which presents a volume uncertainty of 0.020 cm3. [ABSTRACT FROM AUTHOR]

The present study was carried out in the frame of the optimization of the synthesis process of 1,1,4,4-tetramethyl-2-tetrazene (TMTZ), a prospective liquid propellant. The liquid–liquid (LL) equilibria of the TMTZ + H2O binary system were studied under atmospheric pressure and in the temperature range from 278.15 up to 348.15 K. These results established the conditions leading to a spontaneous demixing of TMTZ from the aqueous synthesis solutions. The experimental study of the liquid–vapor (LV) equilibria of the TMTZ + H2O system using DSC, under atmospheric pressure, highlighted the various equilibrium domains involved in the distillation step. Besides, a heteroazeotropic invariant was identified at TH = 366.3 K for x (TMTZ) = 0.254. Lastly, the thermodynamic modeling of those equilibria, using various models (Van Laar, NRTL, Wilson), enabled to improve the experimental results in order to enhance the extraction conditions leading to the production of ultra-pure TMTZ. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations of an embedded atom copper system in the isobaric-isenthalpic ensemble are used to study the effective solid-liquid interfacial free energy of quasi-spherical solid crystals within a liquid. This is within the larger context of molecular dynamics simulations of this system undergoing solidification, where single individually prepared crystallites of different sizes grow until they reach a thermodynamically stable final state. The resulting equilibrium shapes possess the full structural details expected for solids with weakly anisotropic surface free energies (in these cases, ~5% radial flattening and rounded [111] octahedral faces). The simplifying assumption of sphericity and perfect isotropy leads to an effective interfacial free energy as appearing in the Gibbs-Thomson equation, which we determine to be ~177 erg/cm², roughly independent of crystal size for radii in the 50-250 Å range. This quantity may be used in atomistically informed models of solidification kinetics for this system. [ABSTRACT FROM AUTHOR]